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Title:
SHEET MATERIAL HANDLING APPARATUS FOR LIFTING, TRANSPORTING AND PLACING PLANIFORM ARTICLES
Document Type and Number:
WIPO Patent Application WO/2018/130990
Kind Code:
A1
Abstract:
The present invention relates to a sheet material handling apparatus for individually lifting and placing planiform articles (2) and which comprises a suction lifting apparatus (110) with an array of suction lifters (120) each of which comprises a downwardly oriented suction cup (121) provided with a vacuum pressure and being adapted to be placed on a top side (19) of an article to be lifted. An actuation system (8) is configured to move the suction lifting apparatus (110) and a controller (12) is configured to control the operation of the suction lifting apparatus (110) and actuation system (8). A plurality of primary supporting members (46) are spaced apart in parallel and each have at least one primary track (54) that extends in a first substantially horizontal direction (91). A plurality of secondary supporting members (56) are each slideably mounted along the first horizontal direction, each secondary supporting member comprising a secondary track (58) that extends in a second substantially horizontal direction (92) transverse to the first horizontal direction. Each suction lifter comprises a mounting portion (7) by which each suction lifter is slideably mounted to a corresponding one of the secondary tracks, at least one of said mounting portions comprising a clamp between which frictions pads (95, 96) and a resiliently compressible compression member (37) is pressed, and whereby the location in a substantially horizontal plane of each suction cup relative to other suction cups is: a) manually adjustable in the first direction by sliding the mounting portion of the secondary supporting member to which the corresponding suction lifter is mounted in the first direction along said primary track; and b) manually adjustable in the second direction by sliding the mounting portion of said suction lifter to which said suction cup is supported in the second direction along said secondary track.

Inventors:
WADE, Colin Maxwell (14 Boundary Road, Red LodgeBury St. Edmunds, Suffolk IP28 8JQ, IP28 8JQ, GB)
Application Number:
IB2018/050215
Publication Date:
July 19, 2018
Filing Date:
January 12, 2018
Export Citation:
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Assignee:
WADE, Colin Maxwell (14 Boundary Road, Red LodgeBury St. Edmunds, Suffolk IP28 8JQ, IP28 8JQ, GB)
International Classes:
B65H3/08; B65H5/14; F16B5/02; F16B31/04; F16B43/00
Foreign References:
CN2430407Y2001-05-16
EP2514565A12012-10-24
JPH08301468A1996-11-19
EP1394049A12004-03-03
Attorney, Agent or Firm:
MCLEAN, Robert et al. (Dummett Copp LLP, 25 The SquareMartlesham Heat, Ipswich Suffolk IP5 3SL, IP5 3SL, GB)
Download PDF:
Claims:
second direction along said secondary track;

and wherein at least one of said mounting portions comprises:

a clamp between which friction pads are pressed against sliding surfaces of the corresponding track; and

- a resiliently compressible compression member compressed within said clamp, said clamp being manually adjustable to vary said compression of the compression member, and the compression of said compression member determining the pressure applied by said clamp to said friction pads of said mounting portion, whereby in use a desired level of sliding friction of said friction pads of the said mounting portion is set as said friction pads slide along the corresponding sliding surfaces.

2. A sheet material handling apparatus as claimed in Claim 1 , in which:

the primary track comprises an elongate primary slot extending between opposite first and second surfaces of the primary supporting member, said first and second surfaces of the primary supporting member each providing corresponding sliding surfaces of the primary track laterally adjacent opposite side walls of the primary slot;

the primary mounting portion comprises at least one first friction pad positioned to slide along the sliding surfaces provided by the first surface of the primary track and at least one second friction pad positioned to slide along the sliding surfaces provided by the second surface of the primary track; and

the primary mounting portion comprises a primary clamp between which said first and second friction pads of the primary mounting portion are pressed against the corresponding sliding surfaces, and a resiliently compressible primary compression member compressed within the primary clamp, the primary clamp being manually adjustable to vary said compression of the primary compression member, and the compression of the primary compression member determining the pressure applied by the primary clamp to said first and second friction pads of the primary mounting portion, whereby in use a desired level of sliding friction of said first and second friction pads of the primary mounting portion is set as said friction pads slide along the corresponding sliding surfaces.

3. A sheet material handling apparatus as claimed in Claim 1 or Claim 2, in which:

the secondary track comprises an elongate secondary slot extending between opposite first and second surfaces of the secondary supporting member, said first and second surfaces of the secondary supporting member each providing corresponding sliding surfaces of the secondary track laterally adjacent opposite side walls of the secondary slot;

the secondary mounting portion comprises at least one first friction pad positioned to slide along the sliding surfaces provided by the first surface of the secondary track and at least one second friction pad positioned to slide along the sliding surfaces provided by the second surface of the secondary track; and

the secondary mounting portion comprises a secondary clamp between which said first and second friction pads of the secondary mounting portion are pressed against the corresponding sliding surfaces, and a resiliently compressible secondary compression member compressed within the secondary clamp, the secondary clamp being manually adjustable to vary said compression of the secondary compression member, and the compression of the secondary compression member determining the pressure applied by the secondary clamp to said first and second friction pads of the secondary mounting portion, whereby in use a desired level of sliding friction of said first and second friction pads of the secondary mounting portion is set as said friction pads slide along the corresponding sliding surfaces.

4. A sheet material handling apparatus as claimed in any preceding claim, in which said primary supporting member is an elongate member.

5. A sheet material handling apparatus as claimed in Claim 4, in which said primary supporting member is an elongate beam. 6. A sheet material handling apparatus as claimed in Claim 5, in which said elongate beam has a hollow interior extending along its length, said interior conveying air pressure for providing said vacuum pressure.

7. A sheet material handling apparatus as claimed in Claim 6, in which each suction lifter comprises a housing and beneath said housing said downwardly oriented suction cup, and each suction cup being provided with said vacuum pressure from a suction bore through the housing.

8. A sheet material handling apparatus as claimed in Claim 7, in which for each suction lifter, there is an individual hose connection between said housing and a tap through said elongate member to said hollow interior, each of said taps being located proximate the corresponding suction lifter in order thereby to limit the necessary length of the corresponding hose connection.

9. A sheet material handling apparatus as claimed in preceding claim, in which the primary track comprises a downwardly facing elongate primary slot in a lower face of the primary supporting member.

10. A sheet material handling apparatus as claimed in Claim 9, in which said primary slot has an opening that leads to an expanded interior of said the primary slot, the opening being constricted relative to said interior, the secondary supporting members each comprising a key that extends through said opening and that is engaged within the interior of the primary slot and slidable along the length thereof.

1 1 . A sheet material handling apparatus as claimed in Claim 10, when dependent from Claim 2, in the key is part of said primary clamp, the key having a at least one ramp surface that is engaged with an opposing ramp surface of the interior of the primary slot, said opposed ramp surfaces being pressed into engagement with one another as the primary clamp is manually tightened.

12. A sheet material handling apparatus as claimed in any preceding claim, in said secondary supporting member is removeably connected to the primary supporting member by the mounting portion of the secondary supporting member.

13. A sheet material handling apparatus as claimed in Claim 12, in which said connection between the secondary supporting member and the primary supporting member comprises engaged anti-rotation features between said members that fix an angle between said first and second directions.

14. A sheet material handling apparatus as claimed in preceding claim, in which the secondary track is provided by an elongate main body that extends laterally away from a primary clamping connection between the main body and the primary track.

15. A sheet material handling apparatus as claimed in Claim 14, in which the secondary track comprises a secondary slot between opposite top and bottom faces of the main body.

16. A sheet material handling apparatus as claimed in Claim 15, in which the said secondary slot extends longitudinally over a central portion of the main body.

17. A sheet material handling apparatus as claimed in Claim 15 or Claim 16, when dependent from Claim 3, in which the secondary slot is elongate along the length of the elongate main body, the secondary slot being bounded at a first end by a mounting portion of the main body at which said secondary supporting member is mounted to the primary supporting member.

18. A sheet material handling apparatus as claimed in Claim 19, in which said the secondary slot is bounded at a second end by an end stop configured to limit movement of the suction lifter in a direction away from the primary supporting member.

19. A sheet material handling apparatus as claimed in preceding claim, in which the mounting portion of the suction lifter is connected to said suction cup via a connection shaft that extends downwardly from said mounting portion.

20. A sheet material handling apparatus as claimed in Claim 19, in which the suction lifter mounting portion comprises a vertically oriented sleeve and a portion of the connection shaft is slidable within said sleeve whereby the suction cup is movable in upwards and downwards directions relative to said mounting portion of the suction lifter, the suction lifter further comprising a spring biasing means configured to apply a force to bias said movement in the downwards direction. 21 . A sheet material handling apparatus as claimed in Claim 20, in which the spring biasing means is a coil spring, the connection shaft extending along an axis of the coil spring, and the coil spring being compressed along the length of the connection shaft when the suction cup is moved upwards relative to said mounting portion.

22. A sheet material handling apparatus as claimed in preceding claim, in which the secondary supporting member has an elongate main body, the main body having an upper surface and a lower surface, and the mounting portion of the suction lifter comprises a downwardly facing upper bearing surface and an upwardly facing lower bearing surfaces, said upper and lower bearing surfaces being in sliding contact with, respectively, the upper and lower surfaces of the secondary supporting member.

23. A sheet material handling apparatus as claimed in Claim 22, in which the secondary track is a substantially horizontally elongate secondary slot extending between said upper and lower surfaces of said main body, the secondary slot providing a passage for movement of said connection shaft of the suction lifter

24. A sheet material handling apparatus as claimed in Claim 23, in which said upper bearing surface slides on said upper surface on opposite sides of said secondary slot, and said lower bearing surface slides on said lower surface on opposite sides of said secondary slot.

25. A sheet material handling apparatus as claimed in any of Claims 19 to 24, in which the connection shaft extends downwards towards said suction cup from a secondary clamping connection between the main body of the secondary supporting member and the mounting portion of the suction lifter.

26. A sheet material handling apparatus as claimed in any one of Claims 19 to 25, when dependent from Claim 3 in which the secondary mounting portion comprises a pair of said first and second friction pads, one each on opposite upper and lower surfaces of the main body of the secondary supporting member against which said friction pads are pressed, said friction pads being friction washers axially aligned with said sleeve and through which the connection shaft passes.

27. A sheet material handling apparatus as claimed in Claim 26, in which each of said friction washers is compressed, on the one hand, between the corresponding upper or lower surface of the main body and, on the other hand, an upper or a lower annular washer that is affixed around said sleeve.

28. A sheet material handling apparatus as claimed in Claim 27, in which one of said upper or lower annular washers is a fixed locking washer, and the other of said upper or lower annular washers is a manually adjustable washer screw-fitted to said sleeve, whereby the manually adjustable washer may, in use, be turned to increase or decrease the compression of said friction washers.

Description:
SHEET MATERIAL HANDLING APPARATUS FOR LIFTING, TRANSPORTING

AND PLACING PLAN I FORM ARTICLES

BACKGROUND a. Field of the Invention

The present invention relates to a sheet material handling apparatus for individually lifting and placing planiform articles, for example semi-rigid sheet plastic, sheet metal, paper-backed foam board, plywood sheeting, solid cardboard, and corrugated cardboard and any other types of sheet materials which in a production environment may need to be lifted and placed by machinery. b. Related Art There is often a need in a manufacturing operation to individually handle sheets of material, particularly those with sufficient strength to support their own weight. A process step may be used to modify the material, or the material may simply be moved. The sheet material may, for example, be cut, creased, folded, embossed, printed upon, transported or stacked. The sheet material may need to be placed on a work surface, for example a cutting table or folding flaps, where the process step is to take place, or placed on a belt conveyor or a set of rollers which then transport the sheet material to the work surface. The term "process step" also includes the process of forming a stack of planiform articles, by stacking one layer of sheet material on another, and the process of drawing from a stack of sheets, by lifting the top layer from the one below. For convenience, any such location where planiform articles are to be placed on and/or lifted off by sheet material handling equipment is referred to herein as a "work station", and any process accomplished by such an action is referred to as a "process step". A specific example of a prior art work stations that may be used to cut or score fold lines in cardboard, are those supplied by Esko-Graphics bvba (see https://www.esko.eom/en/Drociucl:s/koriasberq-cuttiria-table s). Cuts in sheet material are made by reciprocating vertical blade that is moved on a 2-axis Cartesian robotic actuator that moves over the work surface. Score lines can be formed in a similar manner by a scoring wheel mounted to the actuator. The cuts or fold lines for more than one such box may be made in a single sheet, depending on the size of the boxes being formed.

These work stations can be used with robotic sheet material handlers than comprise a machine vision system and an array of downwardly facing flexible suction cups, connected to a vacuum supply. The array is typically a square or rectangular array having a plurality of suction cups along both horizontal (X- and Y-) directions. An actuation system then moves the array in at least one horizontal linear direction and in both directions along the vertical (Z-) direction. The actuation system may be a robotic arm with multiple degrees of freedom of movement and rotation at a manipulating end of the arm. The array of suction cups is then supported on a horizontally extending frame, supported centrally at the manipulating end of the arm. Such an arm may lift and deposit sheet material within the reach of the arm anywhere on the cutting or scoring work station and adjacent stacking working stations, within the reach of the arm

Other types of robotic sheet material handlers may alternatively be used, for example, a linearly movable gantry that spans the cutting and scoring work station, beneath which is supported the array of suction cups. This is a simpler and more economical way for lifting, moving and depositing sheet material, but is limited to drawing from or forming a stack along the line of travel of the gantry. These production systems work well, but the stacked material after processing will usually need sorting or separating. An example of this is the cutting of sheets of corrugated cardboard, prior to forming into box containers, for example by folding and gluing operations. The initial sheet stock may have standard dimensions, such as, for example, 3.2 m χ 1 .6 m. After placement on the work station, the cardboard may be held down in a horizontal orientation a vacuum hold-down, while cutting and scoring process steps are completed. Such cutting operations generate waste material that has to be separated later on from the desired, or processed, sheet material. Another potential difficulty is when sections of cut material are not properly engaged by the suction cups, in which case such sections may not be properly lifted or may come loose during transport to the stacking work station by the array of suction cups.

Generally, time is lost owing to the above difficulties, and even when such difficulties do not arise, a minimum time will be needed for workers to safely move planiform articles, during which expensive equipment is left idle. As a result, in some production environments it is still preferred to use workers to handle the sheet material, both the place the sheet material at the processing station and afterwards when the desired and waste material is to be moved off the processing station. An advantage of this is that the waste material can be manually separated at the same time as the desired material is stacked, which can save time in the next processing state. There are, however, many disadvantages to using human hands to perform such work, including cost, speed and accuracy of handling and placement of the sheet material.

It is an object of the present invention to provide a more convenient apparatus for lifting and placing planiform articles, that addresses at least some of these problems.

SUMMARY OF THE INVENTION

According to the invention, there is provided a sheet material handling apparatus for lifting, transporting and placing planiform articles at a work station, comprising a suction lifting apparatus for applying a suction lift to said articles, an actuation system configured to move the suction lifting apparatus during said lifting, transporting and placing of said articles and a controller configured to control the operation of said suction lifting apparatus and actuation system, wherein the suction lifting apparatus comprises:

an array of suction lifters, each suction lifter having a downwardly oriented suction cup being adapted to be placed on a top side of one of said articles in contact therewith to apply a vacuum lifting force; at least one primary supporting member, said primary supporting member being coupled to the actuation system whereby aid actuation system is configured to move said primary supporting member during said lifting, transporting and placing of said articles said primary supporting member comprising at least one primary track that extends in a first substantially horizontal direction;

a plurality of secondary supporting members, each of said secondary supporting members comprises a primary mounting portion by which said secondary supporting member is slideably mounted to said primary track whereby said secondary supporting members are spaced apart on the or each primary track along the first substantially horizontal direction, each secondary supporting member comprising a secondary track that extends in a second substantially horizontal direction, the second substantially horizontal direction being transverse to first substantially horizontal direction; and

each suction lifter comprises a secondary mounting portion by which each suction lifter is slideably mounted to a corresponding one of said secondary tracks, whereby the location in a substantially horizontal plane of each suction cup relative to other suction cups is:

a) manually adjustable in the first direction by sliding the primary mounting portion of the secondary supporting member to which the corresponding suction lifter is mounted in the first direction along said primary track; and

b) manually adjustable in the second direction by sliding the secondary mounting portion of said suction lifter to which said suction cup is supported in the second direction along said secondary track;

and wherein at least one of said mounting portions comprises:

- a clamp between which friction pads are pressed against sliding surfaces of the corresponding track; and

a resiliently compressible compression member compressed within said clamp, said clamp being manually adjustable to vary said compression of the compression member, and the compression of said compression member determining the pressure applied by said clamp to said friction pads of said mounting portion, whereby in use a desired level of sliding friction of said friction pads of the said mounting portion is set as said friction pads slide along the corresponding sliding surfaces. In a preferred embodiment of the invention, adjustment of said clamp is by means of a manually graspable compression adjustment control, for example a knob or ring. In this way, a user can quickly adjust the applied compression either make it easier to slide the mounting portion or to lock the mounting portion in place, without the need to use tools, which is time-consuming in a production environment.

A particular advantage of the invention is that the resiliently compressible compression member has the effect providing a gradual change in applied pressure for a given adjustment of the clamp. For example, the clamp may have opposed surfaces which move together or away when adjusted by the compression adjustment control. Because the resiliently compressible compression member deforms resiliently, the pressure within the clamp changes more gradually as a result of this clamp movement than would be the case were there were no resiliently compressible compression member within the clamp. Therefore, the compressibility of the compression member determines the pressure applied by the clamp to the friction pads for given amount of manual adjustment, or clamp movement.

As a result, a user can more precisely set a desired pressure within the clamp, and hence has better control of the pressure exerted by the friction pads on the sliding surfaces. The friction pads and sliding surfaces preferably have a relatively low coefficient of friction.

This arrangement permits grip of the clamps on one or both of the primary and secondary tracks to be adjustable over a range that permits a user to easily slide the mounting portion(s) to adjust the (X,Y) position of individual suction lifters without having to spend time, or use tools, to first loosen the grip of the clamps, while at the same time having sufficient grip so that, once set, the position of the suction lifters does not shift during lifting and depositing of articles (typically, the main forces exerted on the suction lifters are vertical, not horizontal), owning to the clamp providing sufficient static friction.

This is not the case with clamps not having resiliently compressible compression members, because then the clamp when adjusted will quickly transition between a locked condition, in which a user may be unable to exert sufficient force to move the suction lifters by hand, and an unlocked state in which the suction lifters are so free to move, that the (X, Y) position will not be held during lifting and depositing of articles.

The primary track may comprise an elongate primary slot extending between opposite first and second surfaces of the primary supporting member, said first and second surfaces of the primary supporting member each providing corresponding sliding surfaces of the primary track laterally adjacent opposite side walls of the primary slot.

The primary mounting portion may comprise at least one first friction pad positioned to slide along the sliding surfaces provided by the first surface of the primary track and at least one second friction pad positioned to slide along the sliding surfaces provided by the second surface of the primary track.

The primary mounting portion may comprise a primary clamp between which said first and second friction pads of the primary mounting portion are pressed against the corresponding sliding surfaces, and a resiliently compressible primary compression member compressed within the primary clamp, the primary clamp being manually adjustable to vary said compression of the primary compression member, and the compression of the primary compression member determining the pressure applied by the primary clamp to said first and second friction pads of the primary mounting portion, whereby in use a desired level of sliding friction of said first and second friction pads of the primary mounting portion is set as said friction pads slide along the corresponding sliding surfaces.

The secondary track may comprise an elongate secondary slot extending between opposite first and second surfaces of the secondary supporting member, said first and second surfaces of the secondary supporting member each providing corresponding sliding surfaces of the secondary track laterally adjacent opposite side walls of the secondary slot. The secondary mounting portion may comprise at least one first friction pad positioned to slide along the sliding surfaces provided by the first surface of the secondary track and at least one second friction pad positioned to slide along the sliding surfaces provided by the second surface of the secondary track.

The secondary mounting portion may comprise a secondary clamp between which said first and second friction pads of the secondary mounting portion are pressed against the corresponding sliding surfaces, and a resiliently compressible secondary compression member compressed within the secondary clamp, the secondary clamp being manually adjustable to vary said compression of the secondary compression member, and the compression of the secondary compression member determining the pressure applied by the secondary clamp to said first and second friction pads of the secondary mounting portion, whereby in use a desired level of sliding friction of said first and second friction pads of the secondary mounting portion is set as said friction pads slide along the corresponding sliding surfaces.

The secondary supporting members may extend transversely away from either, or from both sides of the, or each, primary supporting member which is preferably elongate.

Preferably, there is a plurality of the primary supporting members, which may be supported in a parallel arrangement on a frame adapted to be lifted and moved by the actuation system.

A user of the sheet material handling apparatus, finding that not all suction cups are optimally oriented with respect to the planiform articles to be lifted, can then, without the need for tools, quickly shift the one or more of suction lifters along the first and/or second directions to improve the performance of the suction lifting apparatus.

Preferably, each housing supports a corresponding one of the downwardly oriented suction cups. Each secondary supporting member is preferably slideably mounted to the primary track by a corresponding primary clamp of the mounting portion of the secondary supporting member. The primary clamp may then be manually adjustable to vary a grip of the primary clamp with the primary track in order to set a desired level of friction between the primary clamp and the primary track.

In this way, the secondary supporting member is, in use, manually slideable along the primary track and then held in position by static friction without having to loosen the primary clamp to permit movement or tighten the primary clamp to secure in place.

Each secondary supporting member may have at least one friction pad that is compressed against the primary supporting member and which, in use, facilitates sliding movement of the secondary supporting member relative to the primary supporting member.

Each suction lifter is preferably slideably mounted to the secondary track by a corresponding secondary clamp of the mounting portion of said suction lifter. The secondary clamp may then be manually adjustable to vary a grip of the secondary clamp with the secondary track in order to set a desired level of friction between the secondary clamp and the secondary track.

In this way, each suction lifter is, in use, manually slideable along the secondary track and then held in position by static friction without having to loosen the secondary clamp to permit movement or tighten the secondary clamp to secure in place.

Each suction lifter preferably has least one friction pad that is compressed against the secondary supporting member and which, in use, facilitates sliding movement of the suction lifter relative to the secondary supporting member.

In a preferred embodiment of the invention, the primary supporting member is an elongate member, for example an elongate beam. The elongate beam may advantageously have a hollow interior extending along its length, the interior conveying air pressure for providing the vacuum pressure. Each suction lifter may comprise a housing and beneath the housing a downwardly oriented suction cup. Each suction cup may then be provided with vacuum pressure from a suction bore through the housing

Preferably, for each suction lifter, there is an individual hose connection between the housing and a tap through the elongate member to the hollow interior. Each of the taps may then be located proximate the corresponding suction lifter in order thereby to limit the necessary length of the corresponding hose connection.

The primary track may comprise a downwardly facing elongate primary slot in a lower face of the primary supporting member.

The primary slot may have an opening that leads to an expanded interior of the primary slot, the opening being constricted relative to the interior. The secondary supporting members may then each comprise a key that extends through the opening and that is engaged within the interior of the primary slot and slidable along the length thereof.

In a preferred embodiment of the invention, the primary slot interior is substantially mushroom shaped in section.

The key will, in general, be part of the primary clamp. The key may have at least one ramp surface that is engaged with an opposing ramp surface of the slot interior, the opposed ramp surfaces being pressed into engagement with one another as the primary clamp is manually tightened.

Each secondary supporting member has a mounting portion at which the secondary supporting member is mounted or connected to the primary supporting member. The connection will, in general, be between the secondary supporting member and the primary supporting member and preferably comprises engaged anti-rotation features between the members that fix an angle between the first and second adjustment directions. The secondary track is preferably provided by an elongate main body that extends laterally away from a primary clamping connection between the main body and the primary track.

In a preferred embodiment of the invention, the secondary track is a secondary slot between opposite top and bottom faces of the main body. The secondary slot may extend longitudinally over a central portion of the elongate main body.

The secondary slot is preferably elongate along the length of the elongate main body, and the secondary slot is bounded a first end by a mounting portion of the main body at which the secondary supporting member is mounted to the primary supporting member.

The first end then serves to limit movement of the suction lifter in a direction towards the primary supporting member.

The secondary slot may be bounded and at a second end by an end stop configured to limit movement of the suction lifter in a direction away from the primary supporting member. The suction lifter may comprise a mounting portion at which the suction lifter is mounted to the secondary supporting member. The mounting portion of the suction lifter may be connected to the suction cup via a connection shaft that extends downwardly from this mounting portion. In a preferred embodiment of the invention, the mounting portion is connected to the housing by this connection shaft, and the housing then supports the suction cup.

In a preferred embodiment of the invention, the suction lifter mounting portion comprises a vertically oriented sleeve. A portion of the connection shaft is then slidable within the sleeve whereby the suction cup, and housing if provided, are movable in upwards and downwards directions relative to the mounting portion of the suction lifter.

The suction lifter may further comprise a spring biasing means configured to apply a force to bias the movement in the downwards direction.

Preferably, the spring biasing means is a coil spring. The connection shaft may then extend along an axis of the coil spring, with the coil spring being compressed along the length of the connection shaft when the suction cup is moved upwards relative to said mounting portion.

In a preferred embodiment of the invention, the coil spring is compressed between the housing and mounting portion of the suction lifter when the house and suction cup are moved upwards relative to this mounting portion.

The advantage of this arrangement is that this helps to ensure that all suction cups are pressed with an even force up against the planiform article to be lifted. The actuator system can then move the supporting components of the suction lifting apparatus closer to the article to be lifted, while ensuring this positive contact, and without making any one suction cup push too hard against the planiform article.

In a preferred embodiment of the invention, the secondary supporting member has an elongate main body, the main body having an upper surface and a lower surface. The mounting portion of the suction lifter may then comprise a downwardly facing upper bearing surface and an upwardly facing lower bearing surface. The upper and lower bearing surfaces are then configured to be in sliding contact with, respectively, the upper and lower surfaces of the secondary supporting member.

Also in a preferred embodiment of the invention, the secondary track is a substantially horizontally elongate secondary slot extending between the upper and lower surfaces of the main body. The secondary slot then provides a passage for movement of the connection shaft of the suction lifter

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be further described, by way of example only, and with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a sheet material handling apparatus for lifting, transporting and placing planiform articles at a work station, according to the prior art, in which a multi-axis robot arm is configured to manipulate a comprising a suction lifting apparatus having an array of suction lifters, to lift sheet corrugated cardboard from a feeding stack, place the cardboard on an automatic cutting table, and then remove the cut cardboard from the cutting table and stack the cut cardboard sheets in an output stack;

Figure 2 is a perspective view of a suction lifting apparatus having an array of suction lifters for incorporation in a sheet material handling apparatus for lifting, transporting and placing planiform articles at a work station, according to a preferred embodiment of the invention, in which each suction lifter is mounted on primary and secondary supporting members which permit sliding movement in X- and Y-directions so that the location of each suction lifters can be manually adjusted;

Figure 3 is a perspective view of a suction lifter and secondary supporting member, the components of the suction lifter shown disassembled along an axis of the suction lifter;

Figure 4 is an end view of the assembled suction lifter and secondary supporting member; and

Figure 5 is a sectional view of suction lifter and secondary supporting member, taken along line V-V of Figure 4. DETAILED DESCRIPTION

Figure 1 shows a prior art sheet material handling apparatus 1 , for lifting, transporting and placing planiform articles, which in this example are sheets of corrugated cardboard 2, at a work station. In this example, there are three work stations. The first work station 4' provides an input stack 5' of fresh, unmarked and uncut sheets of cardboard 2'. The second work station 6 is an automated cutting table, such as that supplied by supplied by Esko-Graphics bvba under the brand name "Kongsberg Automate" (Trade Mark). The third work station 4" has an output stack 5" of cut and scored cardboard sheets 2".

The sheet material handling apparatus 1 comprises a suction lifting apparatus 10 that is operable to apply a suction lift to the articles to be handled, and an actuation system 8 for moving the suction lifting apparatus. In this example, the actuation system 8 is a multi-axis robotic arm 8, that is configured to raise, move, rotate and lower the suction lifting apparatus 10 in order to lift, transport and place the planiform articles throughout a repetitive cycle of operation. The operation of both the robotic arm 8 and the suction lifting apparatus 10 carried by the arm is controlled by a controller 12. The details of the robotic arm 8 and its control by the controller 12 are not central to the invention, and will also be familiar to those skilled in the art, and so will not be further described in detail.

The automated cutting table 6, which is also well-known by those skilled in the art, has fixed working surface 14 provided by a rectangular table top, behind which is a vacuum hold-down (not illustrated) to securely hold down any sheet material placed on the table surface 14. The vacuum hold-down is also controlled by the controller 12. In use, the robotic arm 8 lifts a fresh cardboard sheet 2 taken from the input work station 4' and deposits this either on a first side or half 17' of the table surface 14 (which in this example, is the side nearest to the input stack 5') or on a second side or half 17" of the table work surface (which in this example, is the side nearest to the output stack 5"). In this example, the first side or half 17' of the table surface 14 is an input side of the table surface 14 and the second side or half 17" of the table surface is an output side of the table surface. In Figure 1 , one cardboard sheet 2, for which cutting and creasing operations have just been completed, is shown on the output side 17" of the table surface. The robotic arm 8 is shown in the process of moving the next, fresh cardboard sheet 2 toward the cutting table 6 for deposition on the input side 17' of the table surface 14, following which the controller will release the vacuum hold down on the finished sheet 2 so that the arm 8 can place the suction lifting apparatus 10 on top of the sheet 2 on the output side 17" of the table surface, prior to lifting of the finished sheet into the output stack 5". While the arm 8 is handling a finished sheet lifted from either one of the table sides 17', 17", a movable cutting and embossing head 30 starts work on the newly deposited sheet, held down by vacuum on the other one of the table sides.

The suction lifting apparatus 10 comprises a regular square or rectangular array of suction lifters 20, each suction lifter having a downwardly oriented suction cup 21 . Each cup is provided with a vacuum pressure from a source of vacuum pressure, which may be driven from an air compressor 22. For sake of clarity, connecting air lines are not shown between the compressor and each suction lifter 20. The suction cups 21 all lie in a plane so that these may be placed on a top side 19 of one of the planiform articles 2' to be lifted by the applied vacuum lifting force.

The suction lifters 20 are fixedly mounted on a plurality of parallel, spaced apart elongate mounting members, in this example bars 23, that are fixedly mounted to a common elongate support 24 that extends at right angles to the length of the bars. The bars 23, which are directly laterally adjacent to each other, are mounted to a lower side of the common support at a mid-point of the length of each bar, so that the lifting apparatus is substantially balanced about a central axis 25 of the common support. At a mid-point along the length of the elongate support member, there is on an upper side 26 of the elongate support member a mounting bracket 27 to connect to a manipulating end 28 of the robotic arm 8. The suction lifting apparatus 10 is therefore substantially balanced about the central axis 25 of the common support 24, and also about an axis 29 perpendicular to the central axis 25.

A cutting and embossing head 30 is movably mounted on a rail 31 such that the head 30 can be moved in a Y-direction 32, perpendicular to an X-direction 16. In this example, the X-direction is parallel with the length of the rectangular table top 14 and the Y-direction is parallel with the width of the table top.

The rail itself is movably mounted to a pair of tracks, one of which 15 is visible in Figure 1 , that extend along opposite first and second sides 18', 18" of the cutting table 6 such that the rail 31 and therefore head 30 can be moved in the X-direction 32.

The head 30 houses a reciprocating vertical blade 1 1 which when lowered cuts the cardboard 2 along a line defined by the combined movement of the belt and head. Score lines, or crease lines, to facilitate folding of the cardboard material, can be formed in a similar manner by a scoring wheel mounted to the actuator.

As an alternative to this arrangement, the cutting and creasing work station may use a cutting blade and/or a creasing implement moves by a 2-axis Cartesian robotic actuator that moves over the work surface, which therefore remains stationary.

The cuts or fold lines for more than one such box may be made in a single sheet, depending on the size of the boxes being formed. In Figure 1 , cuts are indicated schematically by solid lines 34. The head 30 also houses a rotating wheel (not shown) which when lowered and moved relative to the cardboard 2 presses against the cardboard to form crease marks, so that the cut shape can be folded into a box. In Figure 1 , crease lines are indicated schematically by dotted lines 35. Superimposed on this pattern are letters "x" which indicate schematically the location of the each of the suction cups 21 when the robot arm 8 moves the suction lifting apparatus 10 into engagement with the upper surface 19 of the cardboard 2 to be lifted. It can be seen that some of the letters "x" coincide with the cut lines 34 and crease lines 35. It has been noted in use that this can cause problems with some cut and crease patterns. Sometimes, suction pressure is diminished where air finds a passage along a crease of through a cut. Other times, a cut portion of the shape can be inadequately held by the suction pressure, and may separate along cut lines from adjacent portions which are securely held to the suction lifting apparatus by the suction pressure.

To deal with these issues, the invention makes use of a different suction lifting apparatus 1 10, an example of which is shown in Figure 2. This suction lifting apparatus 1 10 may be used with the same or similar arrangement of actuator and control systems as described above, or with other types of robotic sheet material handlers such as those that have a linearly movable gantry than spans the area of one or more work stations.

The suction lifting apparatus 1 10 has an array of suction lifters 120. Details of the apparatus, including the suction lifters, are illustrated in Figures 3 to 5.

In use, the suction lifting apparatus 1 10 of the invention is used in place of the prior art suction lifting apparatus 10 of Figure 1 . As the features and operation of the other aspects of the equipment shown in Figure 1 is the same, this will not for the sake of conciseness be described again.

Each suction lifter has a housing 40, the housing supporting a downwardly oriented suction cup 121 . Each cup is provided with a vacuum pressure from a vertically oriented suction bore 41 through the housing and is adapted to be placed on a top side of a planiform articles in contact therewith to apply a vacuum lifting force.

The Venturi effect is used to create the vacuum pressure. Each housing 40 is connected to two air lines (shown in Figure 3 but omitted from the other views for the sake of clarity), one of which 42 supplies a steady blowing pressure, which passes transversely across the top of the suction bore and exits substantially horizontally through an aperture 43 in the housing on an opposite side to which the air line 42 is connected. The advantage of this, as opposed to applying suction pressure directly from a negative pressure reservoir of air, is that if one suction cup 121 does not make contact with a planiform article to be lifted, then there is no loss of suction pressure at any of the other suction cups.

A second air line 44 applies a pneumatic pressure to an air valve 45 for controlling the Venturi airflow. When air line 44 is un-pressurised, then air flows freely out from air line 44 across the top of the suction bore 41 , and when air line 44 is pressurised, the valve closes to stop the Venturi airflow.

The suction lifting apparatus 1 10 comprises preferably more than one primary supporting member 46, and in this example there are seven primary supporting members. The supporting members are preferably elongate beams, and in this example each beam is hollow, having at least one air channel 47 (see Figure 5) that extends long its length. An opening 57 at the end of each one of these air channels at one end of the beams is visible in Figure 2. These openings 57 are connected by air lines (not shown) to the compressor 22, and each of the Venturi air lines 42 are connected at taps 39 tapped into these air channels 47 along the length of each beam 46, which simplifies the routing of air lines to each suction lifter as the Venturi air lines are all then relatively short, being connected to a fitting (not shown on the beam close to its location in the apparatus 1 10.

Although not shown in the drawings, the control air lines 43 from each suction lifter are routed to a port or aperture 48 in a top surface 49 of a central housing 50 of the suction lifting apparatus 1 10, inside of which electrically powered control valves, operating under the control of the controller 12, either apply or block pressure to the Venturi control valves 45 of each suction lifter 120. This avoids the need to route electrical cables across the full extent of the suction lifting apparatus 1 10, which simplifies contraction and improves safety and reliability. Most of the electrical connections are therefore routed centrally.

One exception are electrical connections, again not shown for the sake of clarity, that are routed to one or more downwardly oriented cameras, positioned around the periphery of the suction lifting apparatus. In this example, two cameras 51 are shown in Figure 2. Such cameras provide the input to a machine vision system that is implemented within the controller 12. The suction lifting apparatus 1 10 is coupled to the actuation system 8 at a central mount 127, which is located on the top surface 49 of the central housing 50 for connection to the manipulating end 28 of the robotic arm 8, in a similar manner as in the prior art, whereby the lifting apparatus 1 10, which preferably has a square or rectangular form in plan view, is substantially balanced about its centre. In the present example, the lifting apparatus 1 10 is rectangular in plan, having along its long dimension a longitudinal axis 125 parallel with the primary supporting members, and at right angles to this a transverse axis 129. The mount 127 is therefore connect to the manipulating end 28 of the robotic arm 8, with the suction lifting apparatus 1 10 being therefore substantially balanced about its longitudinal and transverse axes 125, 129.

The parallel primary supporting members 46 are preferably spaced apart in a fixed relationship to each other and supported by a frame. In this example, the primary supporting members are mounted to a pair of spaced apart transverse elongate frame members 52 that extend equidistantly either side of the transverse axis 129 either side. Preferably, as illustrated, the fame members extend above the elongate primary supporting members 46, so that the primary members are suspended beneath the transverse frame members, for example by brackets 53 as illustrated. The central housing 50 is also located between the transverse frame members 52, and may be secured to this by screws, bolts (not shown) or other such connection means to both the frame members 52. As the central housing 50 may be configured to support the central mount 127 for the actuator 8, it is preferable if the central housing and/ or the central mount 127 are also connected to one or more of the elongate primary supporting members 46 directly beneath the housing.

In this way, the actuation system 8 is configured to move the primary supporting members 46 during lifting, transporting and placing of planiform articles 2. As shown in Figure 5, each primary supporting member 46 comprises at least one primary track 54 that extends in a first substantially horizontal direction, which in this example is a direction parallel with the longitudinal axis of the lifting apparatus 1 10. The apparatus 1 10 also comprises a plurality of secondary supporting members 56, each of these secondary supporting members being slideably mounted to a corresponding one of the primary tracks 54, whereby the secondary supporting members are spaced apart on the primary tracks along the first substantially horizontal direction 91 .

In this example, the primary tracks 54 each comprise an external slot 55, referred to hereinafter as a "primary" slot, in a lower surface 68 of the primary supports 46. Each primary slot 55 in each primary support 46 is therefore laterally bounded on its lower side by the adjacent portions of the lower surface 69 that extend along opposite lateral sides of the primary slot. The primary track 54 therefore further comprises these adjacent portions of the lower surface 68 laterally adjacent the primary slot Each primary slot leads upwards to a mushroom-shaped interior 59 as viewed in section. This interior 59 has opposite ramp or funnel shaped surfaces that are laterally adjacent the primary slot and which are constricted in the downwards direction where these meet vertically extending primary slot side walls 36

These funnel shaped surfaces are therefore upper surfaces 69 that laterally bound the primary slot 55 on its upper side. Like the lower surface 68, the upper surface 69 has portions that extend along opposite lateral sides of the primary slot. The primary track 54 therefore further comprises these adjacent portions of the upper surface 69 laterally adjacent the primary slot 55.

The secondary supporting members 56 each have a primary mounting portion 3 that engages with the primary slot by means of an oppositely profiled key or plug 70 that has friction pads 64, each of which is angled to be parallel with one or the other of the funnel shaped upper surfaces 61 , such that when the plug 70 is pulled downward, these come into engagement with the funnel shaped upper surfaces 61 adjacent the primary slot. The plug is moved vertically when a compression adjustment knob 63, provided on a lower surface 78 of the secondary supporting member, is tightened by hand. The compression adjustment knob 63 turns a shaft 65 having a threaded end portion 65' that passes upwards through a vertically extending smooth bore 66 that is located towards a first or proximal end 71 of an elongate main body 60 of the secondary supporting member 56. Above the smooth bore, the threaded end portion 65' of the shaft engages inside a similarly threaded bore 75 inside the plug 70 so that the plug is driven downwards into engagement with the interior 59 of the primary slot 55 when the compression adjustment knob 63 is turned in one direction. In this way, the primary mounting portion 3 provides a clamp between which friction pads 64 are pressed against sliding surfaces of the primary track 54.

Between the lower surface 78 of the secondary supporting member and the compression adjustment knob 63 is a resiliently compressible compression member. In this example, this resiliently compressible compression member is a resiliently compressible washer 74 having an annular shape and with an outer diameter that is preferably comparable to that of the compression adjustment knob 63 below.

An advantage of this arrangement is that this copes well with variations in the width of the primary slot 55, which is commonly seen in commercially available rail-like supports 46 such as the one described and shown in the drawings. Such rails are usually formed of extruded aluminium. If the width of the primary slot varies along its length, the tapered or ramped side surfaces of the plug 70 continue to be engaged with the side walls of the primary slot, owing to the compression of the resiliently compressible washer 74 provided between a shoulder 77 of the shaft 65 and the lower surface 78 of the secondary supporting member elongate main body 60. The ramped side surfaces of the plug 70 therefore accommodate primary slot width variations.

The plug 70 has a plate-like stem portion 81 which is located inside a similarly shaped straight sided groove 82 in an upper surface 79 of the elongate main body 60. The plate and straight groove are parallel with the length of the primary slot 55 that provides the main track in the lower surface 68 of the primary support member 46. As the knob 63 is turned, the plate-like stem portion 81 is pulled further into the straight groove 82.

Although not visible in Figure 2, the primary slot 55 extends to one end of the primary supporting member so that each key 70 can be inserted into the exposed end of the primary slot. After this, an end-cap 87 covers over the primary slot 55. If it is necessary to remove or add suction lifters, then the end-cap can be temporarily taken off for this purpose. Each secondary supporting member is therefore removeably connected to the primary supporting member.

. The elongate main body 60 on its opposite upper surface 79 at least one pair of friction pads 84 on opposite sides of the smooth bore. In this example, as shown particularly by Figure 3, there are two such pairs of pads 84, each of which is discshaped and seated in a cylindrical recess 83 in the upper surface 79 of the main body 60.

When the knob is tightened, pressure is steadily brought to bear on the resiliently compressible washer 74 and pads 84. The resiliently compressible washer 74 is held in compression between an upwardly facing annular shoulder on the knob 63 and the lower surface 78 of the of the secondary supporting member elongate main body 60. The resiliently compressible washer 94 is made of an elastomeric material which deforms like a spring when under pressure and compressed, and which springs back when compressive pressure is relieved. The compressible washer 94 therefore accommodates movement of the compression adjustment ring 93 both towards and away from the head 102.

When the compression adjustment ring 93 is tightened, pressure is steadily brought to bear on the elastomeric washer 94 which becomes resiliently compressed such that it exerts a correspondingly increased pressure on opposing surfaces against which the elastomeric washer bears. In this example, an upper surface of the elastomeric washer 94 bears against an opposed lower surface of the compression adjustment ring 93 and the lower surface bears against an upper surface 108 of the upper friction pad or washer.

The pads are preferably of a resilient plastic, for example nylon or PTFE. The lower surface 68 of the primary supporting member 46 against the pads 84 is smooth and permits sliding movement of the secondary supporting member when the knob is tightened over a range, yet providing sufficient static friction to resist movement owing, for example, to lateral forces imparted owing to lateral movement of the actuator 8 or the planiform article 2 held by the apparatus 1 10.

Each secondary supporting member 56 has a secondary track 58. The secondary track is provided by the elongate main body 60 that extends laterally away from a primary clamping connection between the main body and the primary track 54.

In this example, the secondary track is provided by a vertically extending elongate channel or slot 67, referred to hereinafter as a "secondary" slot, through the elongate main body 60 and by the upper and lower surfaces 79, 78 of the of the elongate main body 60, each of which extend along opposite lateral sides of the secondary slot. The elongate secondary slot has along its length vertically extending side walls 38. The secondary slot 67 preferably bisects a central portion of the elongate main body 60 between a first or proximal end 71 and a second or distal end 72 of the main body. The secondary slot 67 and the upper and lower surfaces 79, 78 on lateral sides adjacent the secondary slot together provide the secondary track 58. The secondary slot 67 and the upper and lower surfaces 79, 78, and therefore the secondary track, extend laterally away from the primary track 54 in a second substantially horizontal direction between opposite first and second ends 61 , 62 of the secondary slot 67, these ends being respectively proximate the first and second ends 71 , 72 of the main body 60 of the secondary supporting member 56. The primary and secondary tracks 54, 58 provide two degrees of freedom of movement in a substantially horizontal plane, within the limits of the extent of the tracks, for each suction lifter 120. The first and second substantially horizontal directions are indicated schematically in Figure 2 by orthogonal arrows 91 , 92 which indicate, respectively, directions parallel to the first and second directions of adjustable movement for each of suction lifters.

In this example, the first and second directions are substantially perpendicular to each other; however, this could in principal be varied away from a right angle as long as these directions were transverse to each other so that the position of the suction lifters can be adjusted within a two-dimensional adjustment area.

Each suction lifter 120 has a secondary mounting portion 7 that engages with the secondary slot 67 in the main body 60 by means of a connection sleeve 90 that has a central portion 97 that extends through the secondary slot 67, and by upper and lower friction pads of the secondary mounting portion 7 that slide along portions of the upper and lower surfaces 79, 78 that are laterally adjacent the slot. A lower end of the connection sleeve is a manually grip-able head 102 of larger diameter than the sleeve central portion 97, such that the head presents a flange 108 with an upwardly facing annular shoulder 103 that supports the lower friction pad. In this example, this upwardly facing shoulder is annular, and the lower friction pad is a washer 96 having an annular shape and with an outer diameter that overlaps the width of the secondary slot 67 to bear against the adjacent portions of the lower surface 78.

An upper end of the connection sleeve 90 is a threaded portion 99 having a cylindrically external thread 101 onto which is screwed a manually operable compression adjustment ring 93. The sleeve threaded portion 99 of the connection sleeve has a lesser diameter than the sleeve central portion 97 such that there is an annular shoulder 1 13 between the sleeve central portion and threaded portion 99. This annular shoulder is axially recessed just below the level of upper surface 79 of the main body 60, so that it does not bear on any other components of the mounting portion 7.

The outer diameter of the sleeve central portion 97 is matched to slide with clearance within the width of the secondary slot 67 of the main body so that there is minimal lateral play between the secondary mounting portion 7 and the substantially vertical side walls 38 of the secondary slot as the suction lifter 120 slides along the secondary slot between its opposite ends 61 , 62. The upper friction pad extends around a lower end of the threaded portion 99. In this example, the upper friction pad is a washer 95 having an annular shape and with an outer diameter that overlaps the width of the secondary slot 67 to bear against the adjacent portions of the upper surface 79. Above the washer 95 providing the upper friction pad is a resiliently compressible compression member. In this example, this resiliently compressible compression member is a resiliently compressible washer 94 having an annular shape and with an outer diameter that is preferably less than or no more than that of the washer 95 below.

Above the washer 94 providing the resiliently compressible compression member is a compression adjustment member for compressing the resiliently compressible compression member and the upper and lower friction pads. In this example, the compression adjustment member is a compression adjustment ring 93 which is internally threaded and screwed onto the threaded portion 99 of the connection sleeve 90.

The compression adjustment ring 93 can be turned manually relative to the connection sleeve 90 to increase or decrease the compression. Although not illustrated the compression adjustment ring 93 and/or the head 102 of the connection sleeve 90 may optionally be provided with grip features, for example a knurled circumference (not shown), to give users a better grip when manually tightening or loosening the compression adjustment ring 93.

The resiliently compressible washer 94 is held in compression between the upwardly facing annular shoulder 103 on the head 102 and the compression adjustment ring 93. The resiliently compressible washer 94 is made of an elastomeric material which deforms when under pressure and compressed, and which springs back when compressive pressure is relieved. The compressible washer 94 therefore accommodates movement of the compression adjustment ring 93 both towards and away from the head 102.

When the compression adjustment ring 93 is tightened, pressure is steadily brought to bear on the elastomeric washer 94 which becomes resiliently compressed such that it exerts a correspondingly increased pressure on opposing surfaces against which the elastomeric washer bears. In this example, an upper surface of the elastomeric washer 94 bears against an opposed lower surface of the compression adjustment ring 93 and the lower surface bears against an upper surface 108 of the upper friction pad or washer.

The friction pads are preferably of a resilient plastic, for example an ester polyurethane, nylon or PTFE. such that the connection sleeve, compression adjustment ring and assembled washers 94-96 are slidable along the upper and lower surfaces 79, 78 either side of the secondary slot 67. The compression adjustment ring 93 and sleeve head 102 may be turned manually relative to each other to tighten or loosen the compression of the intervening washers 94-96 to control how easily the assembly may be slid along the main body 60. In this way, the secondary mounting portion 7 provides a clamp between which friction pads 95, 96 are pressed against sliding surfaces 79, 78 of the secondary track 56.

A generally cylindrical bushing 98 is held inside the connection sleeve 90 below the level of the sleeve threaded portion 99, such that the bushing and sleeve threaded portion present a vertically oriented sleeve having a common bore 33 sized so that the assembled connection sleeve 90, compression adjustment ring 93, bushing 98 and washers 94-96 are freely slidable along a cylindrical surface provided by a connection shaft 88 that extends downwardly from the secondary mounting portion 7 of the suction lifter to the housing 40.

Slidable movement of the assembled connection sleeve 90, compression adjustment ring 93, washers 94-96 and bushing 98 is limited in an upwards direction by a circlip 100 proximate a top end 109 of the connection shaft 88. The circlip is engaged with an annular groove 104 near the top end 109 of the shaft 88 and has an external diameter greater than the shaft 88 and less than the internal diameter of the compression adjustment ring 93, so that the compression adjustment ring abuts the circlip 100 when the shaft 88 moves fully downwards.

Slidable movement of shaft 88 relative to this clamping assembly 93-98, 102 is limited in an upward direction by compression of a coil spring 37 which spirals around the shaft 88 and which has opposite upper and lower ends 37', 37" configured to apply a force to bias relative movement of the secondary mounting portion 7 upwards and movement of the housing 40 and suction cup 121 downwards.

The connection shaft 88 extends along an axis 13 of the coil spring 37. The coil spring is configured to be compressed between the housing 40 and secondary mounting portion 7 of the suction lifter when the housing and suction cup 121 are moved upwards relative to this mounting portion. The housing and suction cup are therefore movable in an upwards direction against this biasing force and will, except when forced by contact against a planiform article to be lifted, move downwards away from the secondary mounting portion 7 of the suction lifter.

The housing 40 of each suction lifter 120 is therefore slideably mounted to a corresponding one of the secondary tracks 58 through the connection shaft 88 and secondary mounting portion 7 of the suction lifter.

The secondary mounting portion 7 of the suction lifter comprises a pair of the friction pads, one each on the opposite upper and lower surfaces 79, 78 of the main body 60 of the secondary supporting member 56. In this example, the friction pads are upper and lower friction washers 95, 96 axially aligned with the sleeve and through which the connection shaft 88 passes. These washers 95, 96 have a relatively low surface friction, being formed in a resilient plastic material, for example an ester polyurethane, nylon or PTFE. The upper and lower friction washers 95, 96 bear against the opposite upper and lower surfaces 79, 78 of the main body 60 of the secondary supporting member 56 to provide downwardly and upwardly facing bearing surfaces to facilitate sliding movement of the suction lifter 120 along the secondary track 58. The upper and lower bearing surfaces are therefore configured to be in sliding contact with, respectively, the upper and lower surfaces of the secondary supporting member along opposite sides of the secondary slot 67.

The connection shaft 88 therefore extends downwards towards the suction cup 121 from a secondary clamping connection between the main body 60 of the secondary supporting member and the secondary mounting portion 7 of the suction lifter.

Each of the friction washers 95, 96 is compressed. The upper friction washer 95 is compressed between the corresponding upper surface 79 of the main body 60 and by an upper resiliently compressible washer 94 that is assembled around the connection sleeve 90. The top-most compression adjustment ring 93 bears against the upper resiliently compressible washer 94 to maintain the set compression of the reliantly compressible upper and lower friction washers 95, 96. The lower friction washer 96 is compressed between the corresponding lower surface 78 of the main body 60 and the upwardly facing annular shoulder 103 on the head 102 of the connection sleeve 90.

The upper compression adjustment ring 93 can be turned by hand to tighten or loosen the compression of the upper and lower friction washers 95, 96 and upper resiliently compressible washer 94, and so ease or restrict sliding movement of the suction lifter along the secondary track 58.

The manually adjustable uppermost compression adjustment ring 93 may therefore, in use, be turned to increase or decrease the compression of the friction and resiliently compressible washers 94, 95, 96. In the embodiment described above, the material used for the friction pads 64, 84, 95, 96, is a copolymer acetal (polyoxymethylene) material, having a tensile strength of 9,800 psi, a flexural modulus of 370,000 psi and a dynamic coefficient of friction of 0.21 .

In the embodiment described above, the material used for the resiliently compressible compression members 74, 94 is an ester polyurethane. The primary compression members 74 each have Shore Hardness A 70. The secondary compression members have Shore Hardness A 50.

In the invention described above, the location in a substantially horizontal plane 91 , 92 of each suction cup 121 relative to other suction cups is therefore: a) manually adjustable in the first direction 91 by sliding the primary mounting portion 3 of the secondary supporting member 56 to which the corresponding suction lifter 121 is mounted in the first direction along the primary track 54; and b) manually adjustable in the second direction 92 by sliding the secondary mounting portion 7 of the suction lifter 120 to which said suction cup is supported in the second direction along the secondary track 58.

By doing this, a worker can readily adjust the lifting locations of any suction lifters for which a problem in operation is noted, or simply to accommodate different shapes of planiform articles to be lifted.

This helps in the achievement of a more optimal lifting pattern of suction cups, and helps to avoid loss of suction, for example on a score line, a cut line, or near and edge.

The invention therefore provides a more convenient and useful apparatus for lifting and placing planiform articles. CLAIMS

1 . A sheet material handling apparatus for lifting, transporting and placing planiform articles at a work station, comprising a suction lifting apparatus for applying a suction lift to said articles, an actuation system configured to move the suction lifting apparatus during said lifting, transporting and placing of said articles and a controller configured to control the operation of said suction lifting apparatus and actuation system, wherein the suction lifting apparatus comprises:

an array of suction lifters, each suction lifter having a downwardly oriented suction cup being adapted to be placed on a top side of one of said articles in contact therewith to apply a vacuum lifting force;

at least one primary supporting member, said primary supporting member being coupled to the actuation system whereby said actuation system is configured to move said primary supporting member during said lifting, transporting and placing of said articles said primary supporting member comprising at least one primary track that extends in a first substantially horizontal direction;

a plurality of secondary supporting members, each of said secondary supporting members comprises a primary mounting portion by which said secondary supporting member is slideably mounted to said primary track whereby said secondary supporting members are spaced apart on the or each primary track along the first substantially horizontal direction, each secondary supporting member comprising a secondary track that extends in a second substantially horizontal direction, the second substantially horizontal direction being transverse to first substantially horizontal direction; and

- each suction lifter comprises a secondary mounting portion by which each suction lifter is slideably mounted to a corresponding one of said secondary tracks, whereby the location in a substantially horizontal plane of each suction cup relative to other suction cups is:

a) manually adjustable in the first direction by sliding the primary mounting portion of the secondary supporting member to which the corresponding suction lifter is mounted in the first direction along said primary track; and

b) manually adjustable in the second direction by sliding the secondary mounting portion of said suction lifter to which said suction cup is supported in the