GB2301338A - A Handling System for Workpieces - Google Patents

Abstract

In a production island, a handling system is provided which serves for the feeding and removal of workpieces 3 to and from a machine 2 respectively. The handling system contains a storage device 7 with several storage locations for workpieces 3, stacks of workpieces, pallets of workpieces, or stacks of such pallets. The linkage to the machine is effected by a single handling device, in the embodiment, a gantry conveyance device 1. The workpieces are introduced without restacking directly from the storage device 7 into the machine 2 and are returned from the latter into the storage device.* Thus the stacking procedures are dispensed with, the availability of the machine is not restricted by the handling system and the whole production island can be set up in a space-saving manner. The gantry conveyance device can have one or two gripper arms 26, 27 and can have one gripper or two, reversible grippers (Figs 3-6). The gripper arms can be vertically movable, rotatable about their own axis or the grippers rotatable about an horizontal axis. The storage locations can be adjustable in height for ease of loading/unloading and removing/replacing by the grippers. * The storage device has a loading/unloading station (17, Fig 2) and at least two, spaced, transfer stations 18, 19. Workpieces are picked up from transfer station 18, machined and then returned directly to the transfer station 19.

Description

A Handling System for Workpieces The invention concerns an apparatus for the feeding and removing of workpieces to or from machines.

In the series production of workpieces, in particular in the mechanical processing of workpieces, these have as a rule to be fed one after another to various machines and have to be taken out of them after the respective working step has been executed.

For this purpose, workpiece conveyance systems are known which ensure a fully automatic conveyance of the workpieces between processing stations or machines arranged in a processing sequence. Such apparatuses for the conveyance of workpieces are as a rule tailored for a specific product or product group to be manufactured in the same, or substantially the same, processing sequence.

Moreover, such workpiece conveyance systems, which take over the conveyance of the workpieces between processing stations in a comprehensive manner, as a rule require the machine to be set up in a way adapted to the flow rate of the workpieces. Furthermore, with all the required component parts, such as handling systems, automatic workpiece buffers, switch points and the like, they constitute complicated devices and therefore entail a considerable investment expenditure.

To render possible a more flexible adaptation of production installations to smaller product runs, to a wider production spectrum, and to requirements changing in other ways, production systems are used which, in contrast to the fully interlinked production installations, have individual machines, or groups of machines, which are each provided with a handling system that links the respective machines to a store or buffer for workpieces. Such production islands process a supply of workpieces held in a store, in which arrangement they are frequently capable of working in a fully automatic mode during this time, which may amount to as much as one to two hours, and thus they do not require any further attendance.This interlinkage, in a workpiece flow, of such machines arranged in the manner of an island is effected by conveying larger lots of workpieces between the individual storage units of various machine islands, this conveyance being for instance controlled or actuated by hand. This conveyance is flexible, whereby the production sequences can be readily reorganized, the work of unused machines can be taken over by others, and the production runs can be altered. In the case of appropriate handling and storage systems, the main thing is that the storage stations can be set independently of the work of the machine provided in the island.

DE-G-9404713.8 discloses a handling system for palletized workpieces, wherein a plafform rotatable round a vertical axis is arranged in a chamber that is closed and accessible through doors. The plafform has two diametrically opposite recesses into which it is possible to insert stacks of pallets. By rotating the plafform through 1800, the pallet stacks are carried along the paths of circular arcs and change their positions. In this arrangement, one of the points which can be occupied by the stacks is a feeding point that is accessible through the doors, and the other diametrically opposed point forms a transfer point.Moreover, the handling system has two conveyance devices of which a first serves to take out pallets from the pallet stack located at the transfer point and to reload them onto a further storage location described as a waiting location. From this waiting location, individual pallets of the reloaded stack are transferred to the feeding location situated between the waiting location and the transfer point, from which feeding location individual workpieces are fed to the machine by means of a second conveyance device (a gripper device).

During the feeding of the machine, there is a need for a restacking procedure from the transfer point into the waiting position, during which there is no processing of the workpieces. Moreover, the space requirement of this handling system is relatively large; with the loading and unloading points, the transfer point, waiting location, and feeding location provision is made for four storage locations arranged linearly one after the other for pallet stacks to which locations there are assigned, including the rotatable plafform, the device for transferring the stacks, and the gripper device, three conveyance devices in all.

Starting from this basis, it is the object of the present invention to create a handling system which does not restrict the utilization of the assigned machine and which has a space-saving design.

Accordingly the present invention provides an apparatus for feeding and removing workpieces to or from machines, including : storage means which has take-up means for the take-up of workpieces and which is equipped for conveying the workpieces in a circle and has a fixed feeding station for the introduction and outward carriage of the workpieces, as well as two fixed transfer stations that are spatially separated from the feeding station, and handling means, by means of which the workpieces can be extracted from the storage means and be inserted therein, at the transfer stations, and which is equipped for the feeding of the workpieces to the machine and for the outward carriage from the machine.

This apparatus has a conveyance or storage device with a loading and unloading point or a feeding point and two transfer points in all. The transfer points are spatially separated from each other, preferably with one designed as an unloading point and the other as a loading point. The only handling device provided in addition to the storage device is arranged so as to extract workpieces from the storage device at the unloading point and to feed them to the machine, as well as to return to the storage device at the loading point workpieces taken out of the machine. Thus the workpieces pass through a path which starts at the storage point of the storage device and returns via the machine to the loading point of the storage device. Thus the handling device cooperates directly with the storage device.

Additional stops, such as are provided in the state of the art for restacking workpieces or pallets or for repositioning whole pallet stacks, are dispensed with.

A handling system is obtained which is compact as a whole, whose space requirement is small and whereby a continuous working of the machine becomes possible without restricting its utilization. This is achieved in that the handling device cooperates without intermediate elements with the storage device, which elements would require operating time and/or additional installation space.

The handling device may be a simple gantry conveyance device. This generally has a support arranged horizontally, whereon a trolley or a carriage is mounted for longitudinal displacement. The support has a drive for the controlled displacement of the carriage. One or two grippers, mounted for adjustment in height, are secured on the carriage and can be caused to come into or out of engagement with the workpieces and to ensure their conveyance in the vertical direction, also designated as the Z axis.

Such a gantry conveyance device can be set up in a space-saving manner, also with a view to feeding a machine from overhead, and it virtually does not require its own installation area. In devices with a single gripper, the insertion of blanks into the machines, and the removal of processed workpieces, are undertaken successively, in which process the gripper executes either two full conveyance sequences, that is to say, it covers twice over the path between the transfer points concerned and the machine, or it briefly deposits, at a support provided at the machine, the workpiece that has been taken out or the one to be inserted. But this is not to be equated with the intermediate stacking of whole pallet stacks which is the case in the prior art. The short term intermediate deposit of workpieces does not require any additional conveyance time, but even saves conveyance time. Moreover, the space requirement for this purpose is in any case small.

In another variant the carriage of the gantry conveyance device has two grippers which can be moved independently of each other in the Z axis. One serves for the removal of a workpiece from the machine, and the other serves for the insertion of a workpiece into the machine. Thus the conveyance of the workpiece between the machine and the two transfer points can be obtained with a single displacement of the carriage or the trolley along the horizontal axis, also designated as the Y axis.

The conveyance time is minimized by this means.

The storage device can be designed basically in various ways. In a simple variant, the storage device is designed in the manner of a Ferris wheel with three take-up points for pallet stacks or workpieces packaged in other ways. The lowest position is the feeding position whereat, independently of the processes taking place at the transfer points, it is possible to remove workpieces individually or as stacks. This point is preferably flush with the ground, that is to say at ground level, so that it can be reached by lifting trucks. The transfer points are offset by 1200 with respect to the feeding points and are arranged at the same level so that the workpieces available at that point are easily accessible for the gantry conveyance device.In particular, only short displacement paths of the grippers are necessary along the Z axis, which saves conveyance time and investment costs for the grippers.

The storage device may also be designed in such a way that the take-up devices execute a rotational movement round a vertical axis. The workpieces or stacks of workpieces, pallet stacks, or the like are thus carried in a circle as on a carousel, in an arrangement such that a chosen point is designed as the feeding point. The carousel may have, in all, three points, or four or even more points, in which arrangement in the variant with four points, there are two points disposed diametrically opposite each other and linked at transfer points to the handling device. This variant has the advantage that workpieces to be taken out can be taken up at the same angle, that is to say with the same orientation as the workpieces to be deposited.

To obtain, in addition, a vertical adjustment facility in the storage device for the workpieces or pallets it is possible for the take-up devices to be capable of being lifted and lowered, for example by means of a hydraulic system. As has already been stated, the vertical adjustment facility of the take-up devices has the advantage that the handling device has to execute a shortened travel in the Z direction, whereby the handling device can, in individual cases, be designed in a lighter version and with a smaller space requirement.

The only handling device, that is to say the gantry conveyance device, serves both the loading and the unloading point. For this reason, it may advantageously be designed in such a way that it transfers empty pallets from the unloading point into the loading point.

A control device controlling the handling system can control the conveyance of the workpieces within the production island automatically so that, apart from the manual feeding and removal of workpieces or pallet stacks at the feeding point, the work of the machine and the conveyance of the workpieces from the unloading point and to the loading point is undertaken automatically.

In order that the present invention may more readily be understood the following description is given, merely by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a very schematic side view showing a production island with a handling system; Fig. 2 is a schematic top view in a cutout representation, showing the handling system of Figure 1; Fig. 3 is a schematic side view showing a production island with a handling system of an alternative design; Fig. 4 is a schematic top view in a cutout representation, showing the handling system of Figure 3; Fig. 5 is a schematic front view in a cutout representation, showing the handling system according to Figures 3 and 4; and Fig. 6 is a schematic side view showing a modified handling system with a gantry conveyance device having a double gripper.

In Figure 1 there is shown a production island or unit 1 which has a merely symbolically indicated machine 2 for processing workpieces 3 at a handling system 4 that both supplies the machine 2 with workpieces 3 to be processed and takes out finished workpieces 3 from the machine 2. The handling system 4 thus forms a storage and conveyance system.

This handling system 4 is subdivided into (i) a gantry conveyance device 6 and (ii) a storage carousel 7 that constitutes an independent storage and conveyance device, while the gantry conveyance device 6 is a handling device effecting the conveyance of the workpieces between the storage carousel 7 and the machine 2.

The storage carousel 7, represented in a top view in Figure 2, has at its centre a rotation and lifting unit 9 which comprises an upright column 11 and is approximately square in cross-section. This is mounted for rotation round a vertical axis and is connected to a drive device, not shown in detail, which can be actuated in a controlled manner by a control device which has also not been shown. With an appropriate actuation of the drive device, the column 11 executes on each occasion a rotation, limited in its angular extent, round the vertical axis.

The rotation and lifting unit 9 has, moreover, a total of four take-up devices 12 which are each of a fork-shaped design and which respectively project radially away from the flat side of the column 11. For distinguishing purposes, the take-up devices 12 are provided in Figure 2 with the suffix letters a to d. The take-up devices 12 are mounted on the column 11 for vertical adjustment by means of a respective guidance device, in which arrangement a shared lifting guide unit 14 is allocated to each take-up device 12a to 12d. It is also possible to provide a respective lifting unit for each take-up device 12a...12d. The lifting drive units 14, merely schematically indicated in Figure 2, are arranged in the interior of the column 11 and are formed by appropriate hydraulic devices or motor units.

The storage carousel 7 is surrounded by a cylindrical fencing 15 which prevents access towards the internal zone of the storage carousel 7. In this arrangement the fencing is arranged coaxially with the column 11 and its diameter is such that pallet stacks taken up by the take-up devices 12 can freely rotate within the fencing 15.

At a point marked in Figure 2 by the take-up device 12a, the fencing 15 has a door 16. This point is a feeding station 17, by means of which the pallet stacks can be inserted into the take-up device 12a and can be taken out therefrom.

The position marked in Figure 2 by the take-up device 12b is an unloading station 18, at which workpieces can be taken from the gantry conveyance device 6 and be fed to the machine 2.

While the following point defined by the take-up device 12c represents an intermediate position, the opposed point marked by the take-up device 12d is a loading station 19 at which workpieces are inserted into the storage carousel 7.

These are workpieces that have been processed by the machine 2 and have been fed by the gantry conveyance device 6. At the unloading station 18 and the loading station 19, the workpieces 3 are transferred, which is the reason why they are also described as transfer stations 18, 19.

The gantry conveyance device 6, also belonging to the handling system 14, is shown in particular in Figure 1 as having a running rail 21 extending substantially in a horizontal direction and mounted at both its ends on vertically arranged stands 22, 23. In this arrangement, the running rail 21 extends above the storage carousel 7, and the machine 2 extends along a horizontal Y axis and is arranged, for example, at a height of approximately 3 metres. It is arranged above the storage carousel 7 and the machine 2, so that a carriage 24 mounted on the running rail 21 for longitudinal displacement can be positioned both above the storage carousel 7 and also above the machine 2, in that it is displaced appropriately in the longitudinal direction. For this purpose, the carriage 24 has a drive device 25, only schematically indicated in Figure 1.

On the carriage 24, there are, moreover, two gripper arms 26, 27 that are adjustable along the vertical axis, also described as the Z axis. These each carry at their respective bottom end one gripper 28, 29 which is equipped to seize a workpiece 3 and can be brought into and out of engagement with the workpiece 3 under the control of the control device. By adjusting the height of the gripper arms 26, 27 in the Z axis, and the longitudinal displacement of the carriage 24 along the horizontal or Y axis, the grippers 28, 29 are capable of running through a lifting-conveyancelowering movement which serves for the insertion of workpieces 3 into the machine 2 and for removing workpieces 3 and for depositing the same in a controlled manner.

In the gantry conveyance device 6 represented in Figure 11 the grippers 28, 29 are each mounted on the gripper arms 26, 27 for rotation round a vertical axis. For this purpose, a rotation device 31 is arranged between the gripper arm 26 and the gripper 28, which device is also controlled or actuated by the control device. A further rotation device 32 is arranged between the gripper 29 and the gripper arm 27, by means of which the gripper 29 can be rotated under the control of a control device round a vertical axis.

The production island 1 described so far operates as follows: Let it be assumed that the storage carousel 7 represented in Figure 2 is at first quite empty and contains neither pallets nor workpieces. In manually operated installations with conveyance rollers, an assembly consisting of a conveyance roller and an empty pallet is now fed in.

After the door 16 has been closed, the storage carousel 7 rotates through 90" in the direction of the drawn arrows so that the pallet stack passes into the unloading station 18. Now an assembly with an empty pallet is again fed in and rotated through 90". In both the intermediate location 12c and the loading location 12b, there will now be disposed a respective carriage, each with an empty pallet.

The first filling of the store has now been completed. As from now on, only full pallets with blanks are fed in and, after completion of the working cycle, full pallets with finished parts are taken out. For this purpose, a pallet stack with workpieces to be processed is moved into the feeding station 17, while the door 16 is open.

This may be done by means of a fork lift, by a lifting truck, by conveyance rollers,or similar conveyance means. At this point the take-up device 12a is fully lowered.

As shown in Figure 1, the lifting drive unit 14 is controlled in such a way that the take-up devices 12 are raised in the unloading station 18 and in the loading station 19, while they are lowered to ground level in the feeding station 17. The lifting of the pallet stacks has the effect that the grippers 28, 29 do not need to be lowered so far, thereby saving conveyance time and allowing the gripper arms 26, 27 to be kept relatively short. This saves installation height, that is to say the free space required above the running rail 21 remains limited to a tolerable extent.

Starting from the rotation and lifting position of the storage carousel 7, the gantry conveyor device 6 conveys the workpieces 3 one after another into the machine 2 as indicated in Figure 1, and after processing in turn deposits them onto the stack of finished parts in the loading station 19. In detail, the gripper 29 grips a workpiece of the top pallet and lifts it up from the pallet. The carriage 24 now runs in the Y direction to the machine, during which time, with an appropriate arrangement of the machine, a rotation of the workpiece through 90" may be effected on the run by means of the rotation device 32. Although the carriage 24 need not stop for this purpose, this section of the path may also be considered to be an "orientation station".

As soon as the carriage 24 is in its position indicated on the right hand side in Figure 1, the gripper 28 takes a finished workpiece 3 out of the machine 2 by gripping the workpiece and extracting it upwards out of the machine whereupon, after an appropriate repositioning of the carriage 24, the gripper 29 inserts into the machine 2 a workpiece 3 to be subsequently processed.

After the change of workpieces has been effected, the carriage 24 is run into its position indicated in Figure 1 at the extreme left, where the gripper 28 deposits the finished part, that is to say the processed workpiece 3, onto the pallet held ready in the loading station 19.

This procedure is repeated often until a complete pallet of workpieces has been worked on, whereupon the pallet is transferred by the grippers 28, 29.

During the whole processing time, a new pallet stack can be inserted into the feeding station 17 (Figure 2), or a pallet stack with finished workpieces 3 may be taken out beforehand if such a stack exists. The exact point of time at which the pallet stack is changed in the feeding station 17 is not determined. This may take place at any time while the pallet stack situated in the unloading station 18 is being worked off.

A modified example of the embodiment of the invention is represented in Figures 3 to 5. Components having the same design and function as in the preceding embodiment are in this representation provided with the same reference numerals without any renewed explanation. The differences lie in the simplified design of the gantry conveyance device 6 and of the storage carousel 7. The carousel is provided with a horizontally disposed pin and has only three take-up devices 12a, 12b, 12c. In this arrangement, the point marked in Figure 3 by the take-up device 12 forms the feeding station 17, the point marked by the take-up device 1 2b is the unloading station 18, and the position assumed in Figure 3 by the take-up device 12c is the loading station 19.

The gantry conveyance device 6 has a passive carriage 24 moved by means of a chain, rope, or belt drive; this carriage carries a single gripper arm 26. The gripper 28 mounted at the end of the arm 26 can be brought into and out of engagement with the workpiece 3, and in this arrangement it is possible to provide if necessary only one direction of rotation between the gripper 28 and the gripper arm 26.

However, in the production island 1 represented in Figure 3, this is not necessary.

The workpieces have on each occasion the same orientation both in the machine 2 and in the unloading station 18 and loading station 19. Turning is not required.

In Figure 6, a production island or production unit 1' is represented which largely agrees with that represented in Figure 1. The description of the production unit 1 of Figure 1 refers correspondingly to that in Figure 6. For distinguishing purposes the same reference numerals are used but are primed on Figure 6. An essential difference of the production unit 1' lies in the design of the gantry conveyance device 6'. On the running rail 21' of the gantry conveyance device 6', there runs the carriage 24' which carries a single arm 26' adjustable in the vertical direction designated as the Z axis.At its bottom end, the gripper arm 26' is provided with a rotation device 41 which carries the two grippers 28', 29'. The rotation device 41 defines a horizontal axis of rotation 42 which is preferably aligned parallel to the running rail 21', round which axis the grippers 28', 29' can be rotated. The grippers 28', 29' are disposed in this arrangement in such a way that they exactly change their places during one rotation of the rotation device 41 round the axis of rotation 42.

In addition, the rotation device 41 may have a device mounted for rotation round the vertical axis 43. In this rotating or pivoting movement, the workpieces 3' received by the grippers 28', 29' are respectively pivoted in a horizontal plane round the vertical axis whereby they can alter their longitudinal alignment. In Figure 6, this is illustrated in connection with the alignment of the workpieces 3' in the unloading station 18' and the machine 2'. While the workpiece 3' is orientated with its longitudinal axis parallel to the running rail 21' in the machine 2', it is orientated transversely to the machine in the loading and unloading stations 18', 19'.

The double gripper formed by the grippers 28', 29' may serve to change workpieces 3' in the machine 2', in which action a single longitudinal displacement travel is sufficient, and no intermediate deposit of the workpieces 3' is required. For example, if the gripper 29' takes up a workpiece 3' in the unloading station 18', the double gripper rotates round the axis 42 so that the still empty gripper 28' passes downwards, the carriage 24' runs meanwhile into the zone of the machine 2' and lowers the arms 26'. The empty gripper 28' now takes the workpiece 3' out of the machine, whereupon the rotation device 41 allows the grippers 28', 29' to change their positions again by means of a rotation round the axis of rotation 42.

Therewith the gripper 29 inserts the new workpiece into the machine. In a final step, the carriage is moved into the position which is at the extreme left in Figure 6 so as to deposit at the unloading station 19' the processed workpiece 3' located in the gripper 28'.

In an alternative embodiment, not represented in greater detail in the Figures, it is, moreover, possible to provide the storage carousel with a vertical axis of rotation and merely three take-up devices. The feeding station, the loading station, and the unloading station are then separated at angles of 1200, and in this arrangement a lifting device has to be provided for lifting the stacks of workpieces located in the unloading station and the loading station. In this embodiment, the workpieces have in the unloading station and in the loading station a different orientation which can be compensated by an appropriate rotation of the grippers.

All the production islands 1,1' described above effect the processing independently and automatically of a palletized stack of workpieces. The independent working period of the production islands 1, 1' amounts to approximately one hour, after which a manual or automatic feeding is required. The automatic working period can be substantially increased still further if the storage device 7 is preceded by a feeding unit. This feeding unit can be, for example, a conveyance device that feeds the pallet stacks on a linear path, or one carried in a different way in sequence towards and away from the feeding station 17. At the feeding station 17 the conveyance device has an outward transfer point at which the pallet stacks leave the preset path laterally and can thus be introduced into the feeding station 17.

Moreover, a pallet stack of finished workpieces available in the feeding station 17 may be laterally passed out of that station and thus be inserted into the conveyance device disposed up the line. In this way, it is possible to allow the production island 1 to work automatically over a whole layer.

In a production island, a handling system is provided which serves for the feeding and removal of workpieces to and from a machine respectively. The handling system contains a storage device with several storage locations for workpieces, stacks of workpieces, pallets of workpieces, or stacks of such pallets. The linkage to the machine is effected by a single handling device, in the preferred case a gantry conveyance device. The workpieces are introduced, without restacking, directly from the storage device into the machine and are returned from the machine into the storage device. The stacking procedures are dispensed with, the availability of the machine is not restricted by the handling system, and the whole production island can be set up in a space-saving manner.

Claims (19)

1. An apparatus for feeding and removing workpieces to or from machines, including : storage means which has take-up means for the take-up of workpieces and which is equipped for conveying the workpieces in a circle and has a fixed feeding station for the introduction and outward carriage of the workpieces, as well as two fixed transfer stations that are spatially separated from the feeding station, and handling means, by means of which the workpieces can be extracted from the storage means and be inserted therein at the transfer stations, and which is equipped for the feeding of the workpieces to the machine and for the outward carriage from the machine.

2. A conveyance system according to claim 1, wherein the transfer stations are spatially separated from each other and can be reached by the handling device.

3. A conveyance system according to claim 2, wherein one of the transfer stations is an unloading station, and the other of the transfer stations is a loading station.

4. A conveyance system according to claim 3, wherein the handling station is equipped to take the workpieces out of the storage device at the unloading station and to feed them directly to the machine without intermediate stacking, as well as to take a processed workpiece from the machine and to feed it to the storage device without intermediate stacking at the loading station.

5. A conveyance system according to any one of claims 1 to 4, wherein the handling device (6) is a gantry conveyance device.

6. A conveyance system according to claim 5, wherein the gantry conveyance device has at least one gripper which is adjustable in height and can be moved between the machine and the transfer stations.

7. A conveyance system according to claim 5, wherein the gantry conveyance device has two grippers which can be moved between the machine and the transfer stations, and which can be jointly adjusted in height.

8. A conveyance system according to claim 5, wherein the gantry conveyance device has two grippers which can be adjusted in height independently of each other, and which can be moved between the machine and the transfer stations.

9. A conveyance system according to any one of the preceding claims, wherein the storage device has three take-up means and two transfer stations which are linked to the machine through the handling device.

10. A conveyance system according to any one of the preceding claims, wherein the take-up devices of the storage device are designed to be adjustable in height.

11. A conveyance system according to any one of the preceding claims, wherein the take-up devices of the storage device are supported in such a way that they are capable of executing a rotational movement round a horizontal axis.

12. A conveyance system according to any one of the preceding claims, wherein the take-up devices are equipped for the taking up of pallet stacks.

13. A conveyance system according to any one of the preceding claims, wherein the handling device is equipped for the transfer of pallets from the unloading station into the loading station.

14. A conveyance system according to any one of the preceding claims, wherein the handling device has four take-up means for taking up workpieces, as well as two transfer stations.

15. A conveyance system according to any one of the preceding claims, wherein the take-up devices of the storage device are supported in such a way that they are capable of executing a rotational movement round a vertical axis.

16. A conveyance system according to claim 15, wherein the take-up devices are adjustable in height independently of each other by means of a height adjustment device.

17. A conveyance system according to any one of the preceding claims, wherein the feeding station is spatially separated from the transfer stations in such a way that a loading and unloading of the storage device with workpieces, or pallet stacks with workpieces, is rendered possible independently of the operation of the handling device.

18. A conveyance system according to any one of the preceding claims, wherein the storage device and the handling device can be controlled by a control device which automatically controls the conveyance of the workpieces.

19. Apparatus for feeding and removing workpieces, substantially as hereinbefore described with reference to and as illustrated in Figures 1 and 2, or Figures 3 to 5, the accompanying drawings.