GB2104470A - Installation for changing and storing workpiece carriers for machining stations - Google Patents

Abstract

An installation for feeding workpiece carriers 15 successively to a machine tool station 22 comprises a feed station 20, a storage station 1 with a plurality of equispaced shelves 10 and a platform 21 for receiving carriers 15 at station 22. Each shelf 10, platform 21 and feed station 20 has a sprocket wheel 13 for engaging a chain 18 on a carrier 15 so as to move it on rollers 16. In operation, a first carrier 15 is moved from feed station 20 across bottom shelf 10 onto platform 21. While machining takes place, top shelf 10 is lowered to receive a second carrier 15 and then raised again. A third carrier is placed on feed station 20. The first carrier is returned to bottom shelf 10. Top shelf 10 is then lowered to locate it between feed station 20 and platform 21 at the same level therewith. The second carrier is then moved onto platform 21 and simultaneously the third carrier is moved onto the top shelf. The shelves are then raised again so that the first carrier can be moved from bottom shelf 10 back to feed station 20. <IMAGE>

Description

SPECIFICATION Installation for changing and storing workpiece carriers for machining stations The invention relates to an installation for the purpose of storing workpiece carriers in the immediate zone of a machining station and changing them automatically between the store and the machining station.

Various installations for changing workpiece carriers are known. For instance, German Democratic Republic Patent Specification 95510 discloses an installation for the changing of workpiece carriers, wherein two guide systems for the workpiece carriers are disposed upstream of the machine table parallel one beside the other on a carriage, which can be so displaced transversely of the guiding direction that each guide system is aligned with the guide system on the machine table.

The main disadvantage of this arrangement is that the workpiece carriers can be only changed, but not stored. However, changing installations are also known which are so constructed that storage sites are disposed parallel or in star-shape one beside the other and the workpiece carriers are fed, for example, via a rail-travelling or horizontally pivotable transfer device, from the changing device to the particular vacant storage site.

These constructions have the disadvantage that they require a separate system for transferring the workpiece carriers from the changing device to the store. Moreover, a very large surface area is required, which depends directly on the number and superficial area of the work-piece carriers used.

Installations are also known for the storage of workpiece carriers in which the workpiece carriers are deposited in stores built up after the fashion of shelves. For instance, U.S. Patent Specification 4035905 discloses a system for workpiece carrier storage wherein storage locations are disposed one above and beside one another in a fixed shelf. The individual storage locations are supplied by a vertical lifting device which can be driven along the storage shelf, in combination with a stationary raisable and lowerable transfer device to the machine.

The disadvantage of this storage system is mainly that it requires a separate changing device which can be moved on rails along the storage shelf and whose rail system takes up about the same surface area as the storage shelf.

It is an object of the invention to provide an installation for changing and storing workpiece carriers for machining stations which, using relatively simple means, enable the workpiece carriers to be both changed and stored in the immediate zone of the machining station, while at the same time occupying a minimum surface area.

It is a further object of the invention to provide an installation for changing and storing workpiece carriers for machining stations, wherein each workpiece carrier can slide horizontally along guide systems horizontally from a clamping means via a storage shelf to the machining station and vice versa, and can be moved vertically by means of a lifting device.

To this end, in the installation according to the invention, a storage shelf has in the vertical direction synchronously adjustable, equally spaced-out staged platforms, each staged platform has guide and drive systems, and, after each lifting movement, the guide system of one staged platform is in alignment with the other guide systems in the horizontal sliding plane, the adjusted height of the lifting device being limited by the distance of the lower staged platform in the horizontal sliding plane from the setting-up surface of the storage shelf, and the number of lifting movements being determined by the staged platforms to be ranged in that zone.

This on the one hand ensures the horizontal conveyance of a workpiece carrier between the machining station and the clamping means, and on the other hand a workpiece carrier prepared on the clamping means, or a workpiece carrier returned from the machining station, can be given intermediate storage by the vertical movement of the staged platforms in the storage shelf in the immediate vicinity of the machining station, without the need for any additional interlinking system for servicing the shelves.

In a preferred embodiment of the invention, the storage shelf has a box-shaped frame with four parallel, synchronously driven screwthreaded spindles at the corners, each of the spindles bearing a number of equally spaced-out screwthreaded nuts corresponding to the number of staged platforms, the nuts being connected rotatablyfast by carriers which are disposed transversely of the horizontal sliding plane and on which guide rails are borne at right angles.

According to a further feature of the invention, the workpiece carrier has on the underside running rollers which correspond with the guide rails, and a T-groove disposed in the horizontal sliding direction, with a roller chain which is coupled to the drive system. According to this feature, associated with each staged platform is a self-locking or braked drive, the drives being controllable independently of one another.

A further feature of the invention is that a number of storage shelves are disposed in the horizontal sliding direction of the workpiece carrier between the machining station and the clamping means, their staged platforms corresponding in vertical distance.

As a result the storage capacity, which is limited in a storage shelf by the possible height of the lifting movement and the height of the workpiece carrier and the workpiece, is substantially increased, although the surface area required is in each case increased only by the area of a workpiece carrier.

Due to the arrangement in the immediate zone of the machining station, a computer control system can be used for controlling the most rational courses of movement.

Conveniently, the store for the associated machining station is designed with a capacity such that it can receive enough workpiece carriers for one shift.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 7 is a diagrammatic view of the basic construction of the installation in association with a machining station, Figure 2 is a plan view of a storage shelf, Figure 3 is a cross section taken along the line A-A in Figure 2, Figure 4 shows a detail of a workpiece carrier conveyor means, Figure 5 is a cross section through a workpiece carrier guide, taken along the line B-B in Figure 4, Figure 6 shows a variant of the construction having two storage shelves, and Figure 7shows a variant of the installation for workpieces of small height.

The basic principle of the invention is shown in Figures 1 to 5. A storage shelf 1 comprises a box-shaped framework 2 in which, disposed adjacent the corners, are parallel screwthreaded spindles 3 each of which bears via a bearing 4 against the base, and can be rotated synchronously by means of a drive 5.

The screwthreaded spindles 3, the bearings 4 and the drive 5 form a lifting device 6. As can be seen in Figures 2 and 3, disposed on the screwthreaded spindles 3, at the same height and at a predetermined distance from one another, are screwthreaded nuts 7 of which two are always held rotatably fast by means of carriers 8.

Guide rails 9 are disposed on the carriers 8 transversely of the carrier direction, the result being the formation of a so-called staged platform 10 in each case. A drive 11 with a shaft 12 and a sprocket wheel 13 is disposed on the staged platform 10.

Also disposed on the guide rails 9 of each staged platform 10 is a workpiece carrier 15 with running rollers 16. On the underside of the workpiece carriers 15, the mid-location between the running rollers 16 is formed, in the longitudinal direction, with a T-groove 17 in which a roller chain 18 is guided. The chain 18 is connected via the sprocket wheel 13 and the shaft 12 with the corresponding drive 11 (Figures 4 and 5). The drives 11 can be controlled independently of one another and are constructed to be self-locking or braked.

The basic construction of the installation (Figure 1) includes, in addition to the storage shelf 1, a clamping means 20 and an adapter 21 for the particular machining station 22. Both the clamping means 20 and the adapter 21 have drive and guide systems (not shown in detail).

Figure 6 shows a variant of the installation which has a larger storage capacity for workpiece carriers 15, due to the introduction of a further storage shelf 1.

Figure 7 shows how, with the use offlatwork- pieces, three workpiece carriers 15 are accommodated per storage shelf 1.

The installation operates as follows: A workpiece to be machined is clamped tightly on the workpiece carrier on the clamping means 20. By successively switching on the drives 11 disposed on the clamping means 20, the lower staged platform 10 of the storage shelf 1, and the adapter 21, by means of the shaft 12, sprocket wheel 13 and roller chain 18 respectively, the workpiece carrier 15 is conveyed, via the guide rails 9 at the same height of the lower staged platform 10 of the storage shelf 1 and the guide rails (not shown) of the adapter 21 to the machine table of the machining station 22, where the carrier is fixed in position and clamped in known manner.

During the machining of the first workpiece at the machining station 22, a further workpiece is secured on a second workpiece carrier 15 at the clamping means 20.

At the same time, the drive 5 and the screwthreaded spindles 3 can effect lowering of the top staged platform 10 to the height of the guide rail 9 of the clamping means 20. Then the second workpiece carrier 15 of the clamping means 20 can be fed in the same manner as the first one to the top staged platform 10 of the storage shelf 1 and retained in the centre on the guide rails 9 by braking of the drive 11.

Then the lifting device 6 lifts the two staged platforms 10 until the lower one comes to a stop at the height of the guide rail 9 of the clamping means 20.

A third workpiece carrier 15 with a workpiece for machining is then prepared in the clamping means 20. On completion of the machining of the first workpiece at the machining station 22, the workpiece carrier 15 on the machine table is fed via the adapter 21 in the reverse direction to the bottom staged platform 10 of the storage shelf 1 and retained fast in the centre.

Then the staged platforms 10 are lowered in the manner described, so that the top staged platform 10 is again in the horizontal sliding plane. The workpiece carrier 15 on the staged platform 10 is fed via the adapter 21 to the machine table of the machining station 22. At the same time, the third workpiece carrier 15 is conveyed from the clamping means 20 to the vacated top staged platform 10 and stopped.

Then the staged platforms 10 are raised again, and the workpiece carrier 15 on the lower staged platform 10 changes to the clamping means 20, to exchange the machined workpiece for one still to be machined.

This changing and storing cycle is repeated after each workpiece is finished.

The variants illustrated in Figures 6 and 7 operate in like manner to the basic construction illustrated in Figure 1. Multiple one-sided or alternate-sided raising or lowering of the staged platforms 10 in both storage shelves 1, followed in each case by the transference of a workpiece carrier 15 of a staged platform 10 to the adjacent storage shelf 1, enables all the workpiece carriers 15 to be interchanged from the storage shelves 1 to the machine table of the machining station 22, and to the clamping means 20, and vice versa.

Claims (6)

1. An installation for changing and storing workpiece carriers for machining stations, wherein each workpiece carrier can slide horizontally along guide systems horizontally from a clamping means via a storage shelf to the machining station and vice versa, and can be moved vertically by means of a lifting device, wherein a storage shelf has in the vertical direction synchronously adjustable, equally spaced-out staged platforms, each staged platform has guide and drive systems, and the arrangement is such that, after each lifting movement, the guide system of one staged platform is in alignment with the other guide systems in the horizontal sliding plane, the adjusted height of the lifting device being limited by the distance of the lower staged platform in the horizontal sliding plane from the setting-up surface of the storage shelf, and the number of lifting movements being determined by the staged platforms ranged in that zone.

2. An installation according to claim 1, wherein the storage shelf has a box-shaped frame with four parallel, synchronously driven screwthreaded spindies at the corners, each of the spindles bearing a number of equally spaced-out screwthreaded nuts corresponding to the number of staged platforms, the nuts being connected rotatably fast by carriers which are disposed transversely of the horizontal siding plane and on which guide rails are borne at right angles.

3. An installation according to claim 2, wherein the workpiece carrier has on the underside running rollers which correspond with the guide rails, and a T-groove disposed in the horizontal sliding direction with a roller chain which is coupled to the drive system.

4. An installation according to any of claims 1 to 3, wherein, associated with each staged platform, is a self-locking or braked drive, the drives being controllable in independently of one another.

5. An installation according to any of claims 1 to 4, wherein a number of storage shelves are disposed in the horizontal sliding direction of the workpiece carrier between the machining station and the clamping means, their staged platforms corresponding in vertical distance.

6. An installation for changing and storing workpiece carriers substantially as hereinbefore described with reference to the accompanying drawings.