The present invention relates to an assembly for facili¬ tating in industrial premises, when conveying heavy objects such as press tools, workpieces and the like, the movement of the objects from or to a storage position such as a bench, a shelf or a table in a press or other mach ine tool .

The invention relates more particularly to the known type of such assemblies which is made up of a unit which can be arranged on the forks of a forklift truck and which, when arranged on the forks, form a sliding plane, moving in the longitudinal direction of the latter, for carrying the objects and which comprises an operating mechanism designed so as to be able to pull an object, situated on a storage position level with and outside the sliding plane, onto the sliding plane and along it towards the inner end of the sliding plane to a conveying position or, in the opposite direction, to push the object from the conveying position along the sliding plane and past its outer end to a storage position situated at the same level .

In a commercially available assembly of this type the operating mechanism consists of two parallel, electrically driven ball screws which have their ball nuts connected to a toggle on the top side of the sliding plane. The toggle consists of a couple of links which can operate in two different relative positions, of which one, when the links are pulled together and stand at an angle to the sliding plane, can be used when, for example, a press tool is moved resting on the sliding plane, while the second relative position, when the toggle is adjusted so that the links lie in line with each other and with the sliding plane and thus can reach outside the sliding plane, is the one which has to be used for the tool to be transferred from the sliding plane to a press table or other storage position, just as when transferring in the

opposite direction onto the sliding plane.

With each such transfer of large and heavy objects from or to a storage position the toggle has to be adjusted between these two working positions, and this adjustment requires that the ball screws operate while the object is lying still on the sliding plane. This discontinuous working method delays and complicates the handling of the objects. Also, because of the design of the operating mechanism, the assembly is unnecessarily expensive.

It is also previously known to incorporate, in a forklift truck, a hydraulic-mechanical operating mechanism for hand¬ ling press tools and the like. The forklift truck is made specially for this purpose and so cannot be used generally as a goods and transport vehicle. It therefore remains unused throughout the period which elapses in a plant be¬ tween tool changes taking place there and similar opera¬ tions which can be carried out with the truck. In addi- tion to the fact that it is uneconomical, this forklift truck has the disadvantage that its operating mechanism operates hydraul ical ly, i.e. it does not permit handling of such heavy objects as are found in the engineering industry, which demands manoeuvring distances of 1 metre or more.

The aim of the invention is to make use of the great transport economy advantages which lie in an assembly, which is to be used to facilitate the movement of objects in an industrial plant by means of a forklift truck, con¬ stituting a unit which can be arranged on the forklift truck at the times when such movement is to be carried out, but which, in the interim, can be kept separate from the forklift truck so that this can be used for other conveying work arising in the industrial plant. The in¬ vention seeks to combine this advantage with an attempt to produce an assembly suitable for this purpose and which, as an accessory to a forklift truck, is made up of

simple mechanical components and is easy and inexpensive to manufacture, and is simple to run in operation.

At the same time the invention seeks to eliminate the disadvantages which are found in the abovement i oned assemblies of the type . in which a continuous displacement movement is not possible.

These aims are achieved, according to the primary charac- terizing features of the invention, by the operating mechanism comprising a pair of drive elements displace¬ able in the I orig i tud i nal direction of the forks, which drive elements run in: parallel tracks which extend below and along the sliding plane from the outer to the inner end, and which drive elements are designed to be longi¬ tudinally displaced the entire length that the object is respectively pulled or pushed to or from the conveying position, and carrier elements which are attached to the drive elements and which stick up from the drive elements above the sliding plane and participate in the longitudi¬ nal displacement along the said length, thereby trans¬ mitting the manoeuvring force necessary for displacement of the object.

The drive elements according to the invention are prefer¬ ably made up of roller chains or the like which are dis¬ placeable in unison in the said tracks each one by means of its gear wheel which is arranged on a transverse driving shaft behind the inner end of the sl iding plane.

Compared with the previously known design with ball screws and toggle, an assembly having the features mentioned here is considerably simpler and less expensive. By virtue of the fact that the roller chains or equivalent drive ele- ments of the assembly are designed to effect the entire dis¬ placement length that an object is to be pulled or pushed during its loading onto the truck or, respecti ely, unloadin from the same, the assembly is able to effect every such

displacement without any interrupt on, which speeds up the handling and facilitates the work for the truck operator.

A further design simplification compared with the known technology is achieved, according to a particular charac¬ terizing feature of the invention, by designing roller chains which run in endless tracks, each one with an operative chain part which is guided both in the trans- verse direction and in the vertical direction in a straight groove emanating from the driving gear wheel, so that the said chain parts can transmit both pulling and push iπg force.

The invention will be explained in greater detail herein¬ after with reference to the attached drawing in which Fig. 1 is a perspective view illustrating the assembly according to the invention in use on a press. Fig. 2 shows, again in perspective, the assembly according to the invention, in which smaller parts are cut away.

Fig. 3 is a longitudinal section of the assembly along the line 111—111 in Fig. 4, which is a plan view. Figs. 5 and 6 are cross-sections along the lines V-V and VI-VI respectively in Fig. 4, and Fig. 7 is a side view of the assembly in an alternative embodiment.

An assembly according to the invention can be used in many different types of industries where movement of heavy and large objects, such as tools, castings or other work-pieces, commonly takes place, and where a forklift truck is used for such movements. In a typical case, as is illustrated in Fig. 1, it may be a question, in an engineering work¬ shop or other industrial plant, of moving a press tool A to or from a storage position B which, in the use example shown, is a press table in an excentre press C.

By means of a forklift truck D, partially shown in the figure, the tool A is thus conveyed, carried by the forks

E of the truck, between the press and another storage position which can be a storage shelf or a loading bench. As is known, the forklift truck D, when used for conveying of this type, has an assembly which is generally desig- nated by 1 and constitutes a unit which can be arranged on the forks E of the truck when the latter is to be used for moving press tools or other heavy objects, while the assembly, during the time when such movements do not take place, can be kept separate from the truck, so that the latter can be used for other conveying work arising in the plant .

The assembly 1 is built on a largely plate-shaped panel forming two leg parts 2, 3 which project from a motor part 4 and which extend parallel to each other in the same relative position as the forks E. When the assembly is in use, the leg parts thus come to rest on the forks, as emerges most clearly from Fig. 6, and the top side of the leg parts thus together defines a sliding plane 5 on which the tool A is to be carried. The sliding plane extends in the longitudinal direction of the forks from the motor part 4, where the sliding plane has its inner end 6, along the entire length of the forks, so that the outer end 7 of the sliding plane ends at or slightly in front of the front edge F of the forks.

The said inner end 6 of the sliding plane normally cor¬ responds to the position which the truck driver wishes the tool A to assume while he is driving the latter from or to the press table B, and, in order to be able to move the object along the sliding plane 5 in towards the conveying position or outwards from the latter, the assembly has, as is known, an operating mechanism which is generally des¬ ignated by 8 in the drawing.

The operating mechanism operates e lee t romechaπ i cal ly and according to the invention comprises a pair of drive ele¬ ments 9, 10 which are longitudinally displaceable in the

assembly and which are preferably made up of roller chains, for example of the type used in bicycles. Alter¬ natively, the drive elements can consist of gear belts. The drive elements 9, 10 run in parallel tracks 11 and 12 respectively, preferably situated on the inside of the leg parts 2 and 3 respectively, i.e. in the space between the forks E, and the tracks extend below and along the sliding plane 5 from its outer end 7 to the inner end 6. In this connection the drive elements are to be designed so that they can be longitudinally displaced in the tracks the same length as the tool A is displaced when it is to be transferred .from its operative position on the press table B to its conveying position furthest in on the sliding plane 5, or when it is to be pushed in the oppo- site direction and set down on the press table or on a storage shelf.

The operating mechanism 8 moreover comprises carrier ele¬ ments 13 which are attached to the drive elements 9, 10 and follow these in the longitudinal movement along the entire said length which is designated by L in Fig. 3. The carrier elements stick up from the drive elements above the sliding plane 5 so that they can act on the inward side of the tool A and transmit to it the manoeuvring force which is required for the displacement.

In the embodiment of the invention which will now be described in greater detail with reference to Figs. 2-6, each leg part 2, 3 is made integral with a U-shaped rail 14, 15. The plates, which define the tracks in which the drive elements 9, 10 are operative, are shown here to follow the inner side of the respective fork E when the assembly is in place on the truck. Depending on the relative distance between the forks and the width of the objects which are to be conveyed, the rails can have another position, such as on the outside or alternatively top side of the forks. In the case of such a greater lateral spacing, it may be advantageous to arrange a third

drive element operating in the centre of the assembly between the two forks.

As emerges most clearly from Figures 2 and 6, the leg parts 2, 3 have cut-outs 16 towards the front which are directed downwards and are made by punching and bending of a square piece of the panel material. The cut-outs are intended to fit into the recesses G which are standard for forklift trucks, and the cut-outs thus provide, to- gether with the rails 14, 15, a defined working position for the assembly when it is set down from above onto the forks, and without other holding means being required.

Incorporated in the rails 14, 15 are profiles which form continuous longitudinal grooves 17 for the drive elements. The profiles can be made up of three parts held together in the rails or, as shown in Fig. 6, can be designed in a single piece fixed with screws 18. The material of the profiles is expediently Teflon or another material which provides low friction with respect to the drive elements and has good wear resistance. As emerges from the figure, each profile forms a pair of opposite groove walls 19 and 20 which, in the transverse direction and vertical direc¬ tion respectively, surround and guide a drive element inserted in the groove 17. The drive element is thus forced to be straight when executing a linear displacement movement in the groove, even when it is subjected to a coβpressive load in the longitudinal direction. According to an important characteristic feature of the invention, the drive element can therefore be made up of a roller chain piece which operates in an endless track.

In this embodiment of the operating mechanism each drive element thus requires only one gear wheel 21 forming the centre point of the endless track which, by means of the abovement ioned straight groove 17, extends tangentially to the upper part of the gear wheel. On the opposite side there extends, l ikewise tangentially to the gear

wheel 21, a rectangular tube 22 of sheet steel which moves along the underside of the U-shaped rail 14, 15 parallel to the latter or in a slightly converging di¬ rection relative thereto and ends under the sliding plane end 7 where the endless track 11, 12 has its two end points. The tube 22 forms a guide in which the lower chain part 9', which does not transmit any man¬ oeuvring force, can run freely to and fro.

The two gear wheels 21 are attached to a transverse drive shaft 23 which is the output shaft of a gear 24 which is driven by an electric motor 25. The gear can expediently be made up of a worm transmission with the worm screw arranged vertically and in front of the worm wheel 26, by which means the motor acquires a central position at the rear of the assembly with good clearance relative to the framework H of the forklift truck.

The upper chain part 9" which is force-guided by the groove 17 has its outermost link, which in the conveying position is located immediately in front of the gear wheel 21, connected to a runner 27 incorporated in the carrier element 13. The runner, which is shown in section in Fig. 6, has a cross-section which, like the chain links, fits between the four groove walls 19 and 20 and is, as emerges from Fig. 3, considerably longer than the height of the groove 17, as a result of which the runner is guided satisfactorily in the latter. Projecting from the runner is a plate-shaped part 28 which is expediently designed integral with the runner and is considerably narrower than the latter so that it fits into the longi¬ tudinal slot 29 which is formed at the top of the groove 17 and is located immediately below and parallel to the sliding plane 5.

On the top side of the sliding plane the plate-shaped parts 28 of the carrier elements are extended forwards so that two similarly positioned and freely projecting

bars are formed. The ends of these are connected to each other by means of a rod-shaped electromagne 30 which extends at right angles to the track of the drive elements over at least the central part of the sliding plane 5. The length of the said bars is adapted such that, when the drive and carrier elements have been displaced the length L and assume the outer end position shown by dot-and-dash lines in Fig. 3, they reach out past the front edge of the sliding plane 5 and across onto the press table B to a sufficient extent for the press tool A, with the magnetic rod 30 as an impact, to take up the intended position on the press C.

When this end position of the operating mechanism is as- su ed and the tool has, by means of the pushing force from the operative chain parts 9" and 10", been moved for¬ wards along the sliding plane 5, the current to the motor 25 is cut out or acquires an inverted phase sequence under the action of an end position breaker 31. The latter can be situated immediately in front of one of the gear wheels 21, which position the outer end of the idle parts 9* and 10' of the chains has now reached, and in such a case the end position breaker can expediently be connected in such a way that it reacts when the last link of one of the idle chain parts 10' passes it. In this way the operating mechanism is stopped or, upon inversion of the phases, returns to the conveying position.

When the press tool A is to be removed from the press, the operator connects the electromagnet 30 by means of one of the buttons on the change-over switch 32 connected to the forklift truck power supply system, after which, with the forks E at the correct level relative to the press table B, he drives forwards to the press at the same time as which he presses another of the buttons on the change-over switch, which supplies current to the motor 25, so that the operating mechanism is allowed to push the carrier forward to the outer end position.

The contact between the rod magnet 30 and the press tool A, which is assumed to be of magnetic material, means that the operator can, by means of starting up the motor 25 and the drive elements 9, 10 in the other direction, pull the tool, without manual intervention, from the press table and thereafter move it inwards along the sliding plane 5 towards the conveying position. When this posi¬ tion is reached, a second end position breaker 33 comes into operation. This breaker can be situated in the move- ment track of a part of the carrier elements 13, for exam¬ ple one of the plate-shaped parts 28, whose rearward edge strikes the breaker 33 and stops the movement of the drive and manoeuvring elements and thus of the tool A.

In the embodiment now described the upper chain parts 9" and 10", since they are guided along their entire length, are able to transmit both pulling and pushing force. An alternative method of producing the same force exertion is shown in principle in Fig. 7.

In this alternative the assembly comprises a frame 34 which has a flat top side 35 along which, in analogy to the above ent ioned sliding plane, it will be possible to move heavy objects inwards or outwards and, as in the preceding example, it will be possible for the assembly to be arranged in a fixed position on the forks of a truck, in which connection the top side can coincide with or be slightly higher than the level of the forks.

Arranged in the frame 34 is an operating mechanism 36 with drive elements 37, preferably two chains which are operated by a reversible motor 38 via a transverse driving shaft 39 with a gear wheel 40. From here the chains extend outwards in closed tracks which are parallel to each other and to the top side 35 and each one of which has a freely running gear wheel 41 at the outer end 42 of the frame.

In the parts 37' of the drive elements moving underneath between the wheels 40, 41 there are incorporated only conventional chain links whereas, in the two upper chain parts 37", a plate-shaped part 43 is inserted in place of a number of l inks, which plate-shaped part sticks up above the top side 35 of the frame and belongs to the carrier element 44 of the assembly. In the same way as mentioned above for the parts 28, the parts 43 can be extended forwards and connected to each other with a transverse magnet or, as shown in Fig. 7, can each have a hook 45 or other purely mechanically acting element which can take ^' hold of a lug or the like on the tool A, in which connection, regardless of the design of the carrier elements, the length will be such that the tool can be pushed out to a sufficient extent past the end 42 to the storage position in question, or can be pulled from this to a conveying position on the assembly.

Since the tracks of the drive elements are not endless, the operative parts 37" are subjected to tensile stress during each displacement, regardless of whether it is in¬ wards or outwards, and, moreover, since the part 43 has a considerable length, these chain parts are kept straight. The profile 17, which guides the drive elements in the embodiment in Figs. 2-6, is therefore not needed for the design in Fig. 7.