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Title:
ELECTRICAL COLLECTOR FOR PALLETIZED LOADS WRAPPING MACHINES
Document Type and Number:
WIPO Patent Application WO/2001/086761
Kind Code:
A1
Abstract:
The collector comprises an annular stator structure (1) designed for coaxial fixing to the upward-and-downward moving annular structure (S) of the wrapping machine and having a U-shaped section which is rotated through 90° and in the cavity of which, directed towards the axis of this structure, an annular lining (2) of electrically insulating material is fixed, said lining supporting, on several levels and coaxially, the electrically conducting annular tracks (3) connected by means of respective electric cables (20) to the fixed electric power supply and control panel. The space circumscribed by the said stator structure houses an annular rotor structure (9) on which there is mounted the brush-holder (13) which co-operates with the said conducting and static tracks (3) and which is connected by cables (19) to the electrical appliances of the carriage mounted on the rotating ring (A) of the wrapping machine, to which the said rotor structure (9) is constrained by special joining means (11, 12). The two annular structures (1, 9) of the collector are connected together by rolling means (10) which secure them in the coaxial and mutually rotating condition and are also connected by sealing means (24, 24', 25, 25') by means of which the toric chamber (z), which is defined by the said structures and inside which the electrical circuit (3, 13) of the collector is located, is isolated from the external environment.

Inventors:
PIERI DANICA (IT)
Application Number:
PCT/EP2001/004326
Publication Date:
November 15, 2001
Filing Date:
April 17, 2001
Export Citation:
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Assignee:
PIERI SRL (IT)
PIERI DANICA (IT)
International Classes:
H01R39/64; (IPC1-7): H01R39/64
Foreign References:
EP0747287A11996-12-11
US5850726A1998-12-22
Attorney, Agent or Firm:
Porsia, Attilio (3/2 Genova, IT)
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Claims:
CLAIMS
1. Electrical collector with a high level of insulation, in particular for machines used for wrapping palletized loads of the socalled ring type, characterized in that it comprises an annular stator structure (1) designed for coaxial fixing to the upward anddownward moving annular structure (S) of the wrapping machine and having a Ushaped section which is rotated through 90° and in the cavity of which, directed towards the axis of this structure, a suitable annular lining (2) of electrically insulating material is fixed, said lining supporting, on several levels and coaxially, the electrically conducting annular tracks (3) connected by means of respective electric cables (20) to the fixed electric power supply and control panel, the said collector being provided in the space circumscribed by the said stator structure with an annular rotor structure (9) on which there is mounted the brushholder (13) which cooperates with the said conducting and static tracks (3) and which is connected by cables (19) to the electrical appliances of the carriage mounted on the rotating ring (A) of the wrapping machine, to which the said rotor structure (9) is constrained by special joining means (11,12), the two structures (1, 9) of the collector being connected together by rolling means (10) which secure them in the coaxial and mutually rotating condition and being also connected by sealing means (24, 24', 25,25') by means of which the toric chamber (Z), which is defined by the said structures and inside which the electrical circuit (3,13) of the collector is located, is isolated from the external environment.
2. Collector according to Claim 1, characterized in that the stator structure (1) is formed by two annular structures with an Lshaped profile mounted in sandwich fashion on the annular structure (2) which is made of electrically insulating material and has a comblike profile and which supports the electrically conducting annular tracks (3), the said Lshaped structures being fixed together with suitable means, for example with welds (5), and being provided externally with holed lugs (6,7) for fixing with screws onto the upwardand downward moving annular structure (S) of the wrapping machine.
3. Collector according to Claim 1, in which the stator structure (1) has loadbearing characteristics and is designed to support the rotor structure (9) by means of rolling means (10) mounted on this latter structure.
4. Collector according to Claim 1, in which the rotor structure (9) has a Ushaped cross section directed with its cavity towards the axis of the said collector and this structure has, mounted on it, horizontalaxis rolling means (10) which cooperate with travelling tracks located on the flanges of the stator structure (1).
5. Collector according to Claim 4, in which the rotor structure (9) is provided with internal reinforcing ribs (109) opposite the point where the rolling means (10) are constrained.
6. Collector according to Claim 4, in which the rolling means (10) are mounted projecting radially and on the outside of the vertical wall of the rotor structure (9) and with their contact surface cooperate with the flanges of the stator structure (1).
7. Collector according to Claim 6, in which the rolling means (10) have a contact surface with a profile similar to that of the wheels of a vehicle travelling on rails and the flanges of the stator structure (1) are profiled suitably so as to cooperate with the contact surface of the said rolling means.
8. Collector according to Claim 6, in which the rolling means (10) have a contact surface with a conical profile and cooperate with inclined tracks (101) formed on the internal surface of the flanges of the stator structure (1).
9. Collector according to Claim 1, in which the rotor structure (9) is provided with means allowing constraining to the ring (A) of the wrapping machine, so as to receive from the latter the rotational movement, but not any axial, radial or composite vibrations.
10. Collector according to Claim 9, in which the rotor structure (9) is provided on the bottom flange with one or more holes (11) in which respective pins (12), integral with the rotating ring (A) of the wrapping machine, are inserted with suitable axial and radial play.
11. Collector according to Claim 1, in which the sealing means are formed by flat rings (24,24', 25, 25') which are made wholly or partly of material with a low coefficient of friction, are fixed with screws (26, 27) onto the external surfaces of the flanges of the two structures (1, 9) of the collector, are directed towards each other and mutually touch with the projecting parts so as to sealingly close off from the outside the chamber (Z) which contains the electrical circuit (3, 13) of the said collector.
12. Collector according to Claim 11, in which the sealing rings (25,25') of the rotor structure (9) are superimposed on those (24,24') of the stator structure (1) so that, if axial play occurs in the said rotor structure and the latter drops as a result of gravity, the contact between the said sealing rings is maintained.
13. Collector according to Claim 11, in which the sealing rings (24,24', 25,25') have a small thickness and are flexible, are of a number greater than one for each of the flanges of the stator and rotor structures on which they are mounted and are intercalated in comb fashion so as to form a labyrinthtype seal.
Description:
TITLE OF THE INVENTION Electrical collector for palletized loads wrapping machines.

BACKGROUND AND SUMMARY OF THE INVENTION The present invention is concerned with the machines for wrapping palletized loads of the so-called ring type, in which the carriage which supports the reel of wrapping film and the motorized unit for pre- stretching the film unwound from this reel travel on a round and horizontal annular structure which is connected to raising and lowering means and in the centre of which the load to be wrapped with helical winding of the said pre-stretched film is positioned.

The end of the wrapping film is initially retained by a gripper device with associated cutting means, which may be located in a fixed position, laterally with respect to the load, or which may be associated with the said annular structure.

In this type of machine, the motor of the pre- stretching unit and the safety devices located on the rotating carriage are connected to the fixed power supply and control panel by means of a ring-type collector which comprises a plurality of brushes associated with the said carriage and co-operating with corresponding electrically conducting annular tracks which are mounted with suitable electrical insulation coaxially on the said annular structure.

Machines of this type at present have the limitation that they cannot be used in those industrial sectors which require a high level of insulation of the electrical plants, as required for example by the international safety standards IP 55, since the brushes and the rings of the collector are of the exposed type, namely are in free communication with the air of the working environment. The invention intends to overcome this limitation of the prior art using the following proposed solution. The collector is formed with a first external annular structure which has a grooved profile and is fixed in a coaxial condition on the annular upward-and-downward moving structure of the machine. Inside this first annular structure which will be defined as"stator structure", the various coaxial, electrically conducting annular tracks of the collector are fixed with the necessary electrical insulation. In the space circumscribed by the said first annular stator structure, a second annular structure-which will be defined as"rotor structure" in that it is intended to be constrained to the rotating ring which carries the film distribution carriage-is arranged and the brushes making contact with the annular tracks of the said first stator structure are mounted on this rotor structure. The two annular structures of the distribution device are connected together and are secured in the coaxial condition by rolling means which allow the external stator structure to be fixed to the annular upward-and- downward moving structure of the machine and the internal rotor structure to be connected to the ring rotating with the carriage of the said wrapping machine in a non-rigid manner so that the small irregularities in movement of the said ring, due to imprecision in manufacture and assembly of this component, do not affect the collector.

According to the invention, the two annular structures of the collector are connected together also by sealing means which complete and isolate from direct contact with the atmosphere the toric chamber inside which the brushes and the electrically conducting annular tracks of the collector operate, the collector thus complying with the current safety standards.

BRIEF DESCRIPTION OF THE DRAWINGS Further characteristic features of the invention and the advantages arising therefrom will emerge more clearly from the following description of a preferred embodiment thereof, illustrated purely by way of a non- limiting example in the figures of the two accompanying plates of drawings, in which: Figure 1 shows a cross-sectional view of a section of the collector mounted on the wrapping machine; -Figure 2 is a schematic and plan view, from below, of a section of the collector according to Figure 1; -Figure 3 shows the collector cross-sectioned along one of the rolling means which rotatably connect the two parts of the said collector; -Figure 4 shows the collector cross-sectioned along the brush-holder unit.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION In Figure 1, S denotes the annular and horizontal structure of the wrapping machine, which is connected to the known raising and lowering means (not shown). A denotes the coaxial ring which is located inside the structure S and on which the carriage with the wrapping film distribution means is mounted and which externally supports integrally the coaxial grooved ring B on which a rotational belt C is driven, the parts B and C being supported by horizontal-and vertical-axis rollers D which are constrained by means of special supports E to the annular structure S and suitably distributed within the round angle.

The electrical collector according to the invention comprises an external annular structure 1 with a grooved profile, for example in the form of a "rotated through 90° and such as to have the cavity directed towards the centre of this structure 1. On the bottom of the groove of the structure 1 there is mounted the electrically insulated part 2, with a comb- like profile, which houses the electrically conducting annular tracks 3, in an appropriate number and suitably spaced from each other. In order to be able to assemble the parts 2,3, the annular structure 1 is formed for example with two annular structures with an L-shaped profile mounted in sandwich fashion on the said parts 2,3 and fixed together for example by means of welding, as indicated by 5.

The stator part 1 has, fixed on the outside, in an appropriate number and suitably distributed within the round angle, lugs 6, for example with an L-shaped profile, which have a respective hole 7 and by means of which the said structure 1 is placed and fixed with screws 8 on the annular structure S of the wrapping machine.

In the space circumscribed by the annular structure 1, which will be defined as"stator structure"for connection to the structure S, at an appropriate distance and coaxially with the said structure 1 there is provided the annular structure 9 of the collector, which will be defined as"rotor structure"in that it is intended for connection to the rotating ring A of the wrapping machine. The structure 9 has for example a U-shaped profile rotated through 90° and directed with the cavity towards the axis of the collector.

As shown in detail in Figure 3, the rotor structure 9 supports rolling means 10 of any suitable type which co-operate, for example, with the flanges of the stator structure 1, so as to ensure a sufficiently precise axial alignment between the said parts 1 and 9 of the collector, avoiding both excessive axial play and excessive radial play. According to a possible embodiment of the invention, the said rolling means 10 consist, for example, of horizontal-axis rollers with a conical contact surface which are distributed in an appropriate number within the round angle and co- operate with the internal inclined surfaces 101 of the flanges of the structure 1 which is made with material and dimensions such as to have load-bearing characteristics, while the structure 9 may be made with more slender dimensions of its walls, having exclusively the function of a part for covering and supporting the brush-holder (see below) and said rolling means 10, opposite which the said structure 9 may be provided with special reinforcing ribs 109. It is understood that, instead of the conical rollers, cylindrical rollers may be used, with either a horizontal or vertical arrangement or only with a horizontal-axis arrangement with a profile which is similar to that of the wheels of a vehicle travelling on rails.

The rotor structure 9 is provided at the bottom with one or more holes 11 allowing constraining to the rotating ring A of the wrapping machine by means of special joining means 12. Since, owing to imprecision in the manufacture and rotational assembly on the structure S, the ring A is subject to small axial and radial displacements during rotation, in order to prevent these movements from affecting the collector the connection provided by the said means 12 is preferably of the loose type and sufficient to ensure that the said ring A is able to drive rotatably the structure 9 of the collector which is rotatably supported with its own rolling means by the stator structure 1.

The loose connection provided by the means 12 is also able to compensate for any imprecision in the coaxial arrangement of the stator structure 1 and the upward-and-downward moving structure S of the machine.

The joining means 12 for example consist of a pin integral with the ring A, parallel to the axis of the collector and such as to co-operate with suitable play with a corresponding hole 11, so that in the said hole the said pin 12 has freedom of both radial and axial movement.

As shown in detail in Figure 4, at a point on the rotor structure 9 which is close to the film distribution carriage mounted on the ring A shown in Figure 1, the brush-holder 13 is mounted on the same structure 9, being provided with a plurality of brushes 14 which each co-operate with the electrically conducting tracks 3 of the stator structure 1. The brush-holder 13 has, for example, an L-shaped profile and has its base 113 which passes through a side opening 15 of the rotor structure 9 and which is fixed with screws 16 onto a flange of this structure. 17 denotes a cover which sealingly closes the said opening 15 and which is made of any suitable material and on which the cable sleeve 18 is mounted, said sleeve receiving the electric cables 19 which connect the various brushes 14 to the appliances of the said film distribution carriage. The rotor structure 9 may be provided, at 180° with respect to the brush-holder 13, with a suitable dynamic balancing mass, which is not shown in that it may be deduced by persons skilled in the art.

The electrically conducting annular tracks 3 of the stator structure 1 are instead connected to cables 20 which pass through a side opening 21 of the structure 1 and are wired up to the fixed control panel of the wrapping machine. The opening 21 is sealingly closed by a cover 22 and by a seal 23 which is made for example with a suitable resin and in which the terminals of the said cables 20 are embedded.

The collector is completed by means which ensure that the toric chamber Z, which exists between the structures 1 and 9 and inside which the electrical circuit 3,13 of the said collector is housed, is isolated from the external atmosphere. These means may for example comprise flat rings 24,24'and 25,25' which are fixed externally onto the flanges of the structures 1 and 9 of the collector, for example by means of screws 26 and 27, and which are partly superimposed on each other so as to form the necessary externally sealed closure of the said toric chamber Z.

The rings 24,24', 25,25'are made wholly or partly with a material which has a low coefficient of friction. In the solution illustrated in the drawings, the rings 24,24'of the stator structure are located underneath the rings 25,25'of the rotor structure so that, if there is axial play between the structures 1 and 9 of the collector, the contact between the sealing rings may be maintained by the weight of the rotor structure.

According to a constructional variant, not illustrated, the sealing rings may be made with a suitable flexible material, may consist of a number greater than one for each flange of the structures 1 and 9 to be sealingly closed, and may be intercalated in comb fashion so as to form a labyrinth-type barrier.

If the collector is intended to operate in particularly dusty environments, sealing skirts formed for example with annular brushes may be provided outside of the sealing zone, all of which may be deduced and easily realized by persons skilled in the art.

It is understood that the above description refers to a preferred embodiment of the invention. It is also understood that the invention may be subject to numerous constructional variations and modifications relating, for example, to the means for sealing the chamber Z or to the rolling means 10 which instead of being located inside the said chamber may be external and may be supported by either one of the structures 9 and 1.