GB2168628A

GB2168628A - Pallet store

Info

Publication number: GB2168628A
Application number: GB08530635A
Authority: GB
Inventors: Pekka Tapio Siponen
Original assignee: Valmet Oy
Current assignee: Valmet Oy
Priority date: 1984-12-21
Filing date: 1985-12-12
Publication date: 1986-06-25
Also published as: FI845111L; FR2575099A1; FI845111A0; GB2168628B; SE8505982D0; DE3543579A1; SE8505982L; GB8530635D0; JPS61159356A

Abstract

The invention is concerned with a pallet store, to be joined in connection with at least one machining center (1), wherein the pallets (5) and workpieces (6) attached to them, if any, are arranged in storeys substantially in circular form. A space remains in the middle of the pallet store (3), in which is disposed rotatable and vertically movable handling equipment (4). The pallet handling equipment (4) is arranged so as to handle two similar or different machining pallets (5) at the same time. Thereby, a new pallet (5) is arranged to be shifted by means of the pallet handling equipment (4) to the machining center (1) or onto the shelf of the pallet store (3) immediately after the preceding pallet (5) has been shifted from there onto the pallet handling equipment (4). <IMAGE>

Description

SPECIFICATION Pallet store The present invention is concerned with a pallet store, in particular with a pallet store to be joined in connection with at least one machining center, NC-machine tool, or some other machine or device, in which said store the machining pallets and/or transport pallets and the workpieces attached to them, if any, are arranged to be stored in several storeys placed one above the other.

In view of improving the reliability of operation and the degree of utilization of machine tools, attempts are being made to automatize such machines to an ever higher extent. Besides the circumstance mentioned above, automation also gives some other considerable advantages, e.g. that the machinery can be operated either fully unmanned or partly manned for quite a long period of time, e.g.

for one working shift. If a machine tool or a machine in general is supposed to be made to operate for a long time unmanned, there must be quite a large store of blanks in the proximity of the machine, from which said store the pieces to be machined, placed on machining pallets, move into the machining center so as to be machined. Traditionally, the pallets have been stored in connection with the machine tool or machining centre in one plane, as a rule at the level of the working plane of the machine tool or on the floor plane. However, a considerable drawback resulting from this is the abundant requirement of floor area, because of which a large store cannot be kept in connection with a machining center. This again results in the fact that the period of unmanned working obtainable by means of a machining center is quite limited.

In prior art, solutions are also known in which a pallet store of large size is placed in connection with a machine tool or machining center, the pallets being placed in several storeys in the said store. By means of such a solution, economies of floor area are obtained in the proximity of the machine tool. Such solutions are described, e.g., in the US patents 4,035,904, 4,237,598, and 4,369,563 as well as in the published DE Patent Applications 2,441,095, 3,212,224, 3,223,729, and 3,225,280. In the constructions in accordance with all of the above publications, the pallet stores are oblong and multi-storey stores in which the pallet handling device is displaced in the longitudinal direction of the store.The location of the machine tool or of the machining center in connection with the store can, however, not be chosen freely, but it can be placed at either one of the long sides of the store only. In a solution like this, the pallet exchange speed cannot be made very high, for if the store is very long and if the machining center is located at one end of the store and the piece to be machined next at the opposite end of the store, the pallet exchanger needs quite a lot of time in fetching the next machining pallet to the machining center.

According to the present invention there is provided a pallet store in which pallets can be stored in several storeys with the pallets in each storey positioned such that there passes therethrough a circle substantially centered on a space that remains in the middle of the pallet store, there being in this space a pallet handling equipment that can revolve about a substantially vertical axis, this equipment being arranged for automatically feeding from the pallet store workpieces placed on the pallets and for shifting workpieces into the pallet store, the pallets in respect of their grasping points and/or size being either similar or dissimilar. This store can be integrated with a machining center, NC-machine tool, or some other machine or device, and the pallets can be machining pallets and/or transport pallets.

The feed of workpieces from the pallet store can be onto the table of the machining center or equivalent or to any other working or handling station, and the shifting of workpieces into the store can be the shifting of machined workpieces from the machining center or equivalent into the pallet store.

Several advantages are obtained, of which, e.g., the following might be mentioned.

A long working period with no manning or with restricted manning is achieved. The time of performance of the unmanned period can be chosen freely. The pallet store can be connected to most existing NC-machining centers, of which, combined with a pallet store, a socalled flexible manufacturing cell can be made.

In connection with the store, it is possible to operate several machining centers, advantageously 1 to 3 machining centers or other working stations, at the same time. The pallet store is suitable for use with pallets of several different sizes, also at the same time. At the same time, it is also possible to store goods placed on load pallets in the pallet store. Several pallet stores with connected machining centers may be combined into joint operation by means of an appropriate conveyor, e.g. a roller conveyor.

The invention will be described in the following in more detail with reference to the figures in the accompanying drawing.

Figure 1 is a perspective view of one embodiment of a pallet store, Figure 2 is a vertical sectional view seen from the side of a pallet store, Figure 3 is an axonometric view of the pallet handling equipment with its turning and lifting gear.

Figure 4 is a vertical sectional view seen from the side of the pallet store, taken perpendicularly to the section shown in Fig. 2, and Figure 5 is a cross-sectional view seen from the top of a pallet store.

Fig. 1 is an axonometric view of a pallet store 3 which is connected with a machining center 1 operated by means of its own control system, e.g. by the intermediate of a control desk 2. As is shown in Fig. 1, the store 3 is a high store of the shape of a polyhedron, in which the pallets 5 and the workpieces 6 placed on them are stored in several storeys. The frame 23 of the store shelf system is built of module components which form a rigid structure when assembled. The frame and shelf beams may be, e,g., of steel or aluminium profile or equivalent. The store shelf system 3 is preferably enclosed in a protective wire-net fence 25, which prevents falling down of objects outside the store in cases of accident.

The store 3 is preferably provided with a convevor 22, such as, e.g., a roller conveyor of the sort shown in the Figure, along which the workpieces are transferred into the store from the workpiece attaching position 21. In the pallet store 3, the pallets 5 and the workpieces 6 placed thereon are placed on the shelves 24 near the outside faces of the store alongside the protective net 25 so that the middle part of the store remains free from these pallets 5. Tne shelves 24 are also placed at the outside of the store, whereby a free space remains in the middle part of the store. The pallet handling equipment 4 with its lifting, turning and transfer gear is installed in this free space in the middle.

By means of the pallet handling equipment 4, the pallets and the workpieces 6 to be machined and placed on the pallets are fetched from the store 3 and shifted to the machining center 1 for machining. Correspondingly, the pallet handling equipment 4 fetches the machined pieces from the machining center 1 and shifts them onto the conveyor 22, which carries them out of the store, or the pieces are shifted to a new location in the store 3 to wait for further processing. The pallet handling equipment 4 is installed on a lifting slide 7, which is arranged as moving in the vertical direction so that it can operate at the levels of different shelves.The lifting slide 7 is arranged as moving in the vertical direction in the vertical frame 9 of the turning equipment, which is again installed as revolving relative the vertical centre axis of the store 3, whereby, by means of the pallet handling equipment 4, a pallet 5 can be fetched from any shelf or conveyor whatsoever placed around the centre axis. Correspondingly, the pallet may, of course, be placed onto any shelf or conveyor whatsoever.

The vertical sectional view from the side, in Fig. 2, illustrates the construction of the pallet store 3 in more detail. In Fig. 2, the pallet store 3 is shown without machining center 1 and without conveyor 22. The pallet store 3 itself consists of frame modules 23 and of shelves 24 as well as of a protective wire net 25 surrounding the store. As is shown in Fig.

2, the shelves 24 and the pallets 5 placed thereon are located along the walls of the store, so that there is a fully free space in the middle of the store. According to fig. 2, and so also according to Figs. 4 and 5, the pallet handling equipment 4 is installed on the vertical centre axis of the store, which said equipment 4 is displaceable in the vertical direction so as to permit its operation at the levels of the different shelves. The pallet handling equipment 4 is installed on a lifting slide 7, which can be shifted up and down along the vertical frame 9 of the turning equipment. This construction is also illustrated by means of the axonometric view in Fig. 3.

In accordance with Figures 2 to 5, the pallet handling equipment 4 is designed such that, by its means, two pallets can be handled at the same time. Such an embodiment can be considered preferable, and thereat the pallets to be handled may also be different as regards their size, construction and grasping points, of two different types. Such an embodiment is also possible in which the pallet handling equipment 4 carries only one pallet 5 at a time. The pallet handling equipment 4 includes means for grasping the pallets, socalled pallet grasps, which are fitted as moving horizontally in horizontal guides 8 provided in the frame of the lifting slide 7. The pallet grasps are fitted so as to grasp the grasping points placed at the sides of the pallets 5, or to grasp underneath the pallets.The drive unit of the pallet handling equipment 4 is advantageously a two-speed switching motor provided with a torque clutch. By means of the equipment, precision parking of the pallets is performed advantageously against a hydraulically attenuated stop.

The lifting slide 7, on which the pallet handling equipment 4 is installed, is fitted so as to move vertically along the vertical guides 10 provided in the vertical frame 9 of the turning equipment. The lifting slide 7 is preferably assembled by welding out of steel beams or profiles. The lifting slide 7 is preferably provided with guide rolls 11 or with equivalent members which move along the guides 10 in the vertical frame. The vertical frame 9 of the turning equipment is preferably made of two vertical steel beams placed side by side, the lifting slide 7 being installed movably between the said beams. The guides 10 along which the slide 7 moves are mounted on the said vertical beams. The vertical frame 9 is journalled centrally as turning relative a substantially vertical axis, which coincides with the centre axis of the pallet store 3. At its top end, the vertical frame 9 is journalled by means of a bearing 16 on the frame 23 of the pallet store 3. At its bottom end, the vertical frame 9 is mounted stationarily on a base 15.

which is again journalled by means of a bearing 17 on the floor or on the frame part 23 of the store.

The lifting slide 7 is displaced vertically preferably by means of chains 12, even though power transmission members of other types may also be used. The lifting mechanism 14 is fixed to the bottom end or top end or to the base 15 of the vertical frame 9, which said mechanism 14 displaces the lifting slide 7 by the intermediate of the chains 12. In the embodiment shown in the figures, guide gears 13 are mounted at the top end of the vertical frame 9, the chain; 12 passing over the said gears 13 from the lifting mechanism 14 to the lifting slide 7. By means of the lifting mechanism 14, the lifting slide 7 is displaced vertically between the different shelf planes 24 and the machining centre 1. The placing of a pallet 5 into a shelf position 24 takes place, in respect of the vertical movement, by means of the lifting mechanism 14.At the bottom end or in the base 15 of the vertical frame 9, a fine-parking equipment 20 is also installed, or can be installed, by means of which the movement of the lifting slide 7 is adjusted so that the pallet 5 can be placed onto the table of the machining center 1 highly accurately or more accurately than would be possible by means of the lifting and turning mechanisms.

As the lifting mechanism 14, advantageously a two-speed switching motor is used, which is mounted on the shaft driving the liftinc chains 12. The vertical frame 9 is turned on the bearings 16 and 17 by means of a rotating equipment 18, which permits handling of the pallet between different shelves 24, which are placed on the sides of a regular polygon in the pallet store 3.

As can be seen from Fig. 1 and in particular from Fig. 5, the cross-section of the pallet store 3 is of octogonal form, and in this store the shelves 24 are placed at the walls of the store, i.e. almost on the arc of a circle. In other words, the arrangement of pallets in the store is such that in each storey there is a circle that passes through all the pallets in the storey, these circles for all the storeys being of the same radius centered on the free space in the middle part of the store.

As the rotating equipment is used favourably a two-speed switching motor, which is installed stationarily on the floor or on the frame structures 23 of the store. From the motor of the turning mechanism, the power is transmitted to the vertical frame by means of a suitable power transmission member, such as, e.g., chain transmission, friction transmission, gear transmission, or equivalent. The locating of the turning movement of the vertical frame 9 is performed by means of locating equipment 19, by means of which the vertical frame 9 is locked in the desired position more accurately than what can be accomplished by means of the turning motor alone. As the locating equipment, it is possible to use, e.g., an axial-movement motor in accordance with Figs. 2 and 5, whose spindle is locked in its position, e.g., by means of counter-pieces placed in the base 15.The locating equipment 19 locks the revolving movement of the vertical frame 9 in an adjustable precise position.

As was already stated above, a fine-parking equipment 20 is installed at the bottom end of the vertical frame 9, preferably on the base 15, by means of which said equipment 20 it is possible to perform the exchanging of the pallet both in machining centers exchanging horizontally and in those exchanging vertically.

By means of the fine-parking equipment mechanism, the accurate positioning of the pallet handling equipment 4 is performed in the vertical direction when the pallet is being exchanged. As the fine-parking equipment mechanism is used preferably a lifting device operating by the eccentric principle and driven by a switching motor.

The control of the pallet store is based on a freely programmable microcomputer or on a programmable logic. The operation is performed advantageously by means of a display terminal placed in the control desk 2. The necessary actuating means and detectors are connected by means of binary I/O cards. The control includes a relay and protection system which prevents functions dangerous for the equipment. In the control, three different modes of operation are provided, namely automatic operation, manual operation, and service operation. In automatic operation, the control performs the operations in accordance with the programs and is in direct connection with the machining centers. With manual operation, the operating commands are given to the equipment by means of the display terminal. An operating command consists of an address and of a pallet handling operation.The service operation functions are arranged so that the due performance of the various operations can be checked readily and that the service operations can be carried out easily.

Next, a brief description will be given of the operation of the pallet.

When the manufacture of a new workpiece 6 is started, its attachments are given numbers, so-called pallet codes. On the basis of the number, the control system 2 knows the machining program, the related tools, and knows the locations of the empty or full pallets 5 or of the pallets 5 with machined pieces 6 present in the store 3. The attaching of the pieces to the attachment on the pallet takes place in the attaching position 21 placed at the side of the store 3. After the attaching, the pallet 5 is sent to the store 3, whereby, e.g., the code reading device present on the handling devices reads the code, and the control system selects the storage address for the pallet.

On the basis of the drawn-up program and the priority sequence, the control system 2 determines the following pallet 5 bound to pass to the machining center 1 and fetches it ready to the pallet handling equipment 4 for the next exchange of pallet 5. This permits uninterrupted production. The exchange of pal; let is performed when the control of the machining center 1 asks for it. The pallet 5 with the machined piece is passed either to the store 3 or to the attaching position 21. The removal of machined pieces and the placing of new ones onto the attachments after the unmanned working shift can be performed in the sequence of machining or by calling the pallets determined by the store bookkeeping to the attaching position 21. The control system 2 is provided with an extensive set of programs which diagnosticizes various disturbance situations automatically. The control system also stores the disturbance reports, and by its means it is possible to perform various statistical duties.

Above, the invention has been described with reference to the preferred exemplifying embodiments of the invention shown in the figures only. This is, however, by no means supposed to restrict the invention so as to cover these exemplifying embodiments only, but many variations are possible within the scope of the inventive idea defined in the following patent claims.

Claims

1. A pallet store in which pallets can be stored in several storeys with the pallets in each storey positioned such that there passes therethrough a circle substantially centered on a space that remains in the middle of the pallet store, there being in this space a pallet handling equipment that can revolve about a substantially vertical axis, this equipment being arranged for automatically feeding from the pallet store workpieces placed on the pallets and for shifting workpieces into the pallet store, the pallets in respect of their grasping points and/or size being either similar or dissimilar.

2. A pallet store as claimed in claim 1, wherein the pallet handling equipment can handle two pallets at the same time, whereby a new pallet can be fed from the pallet store or can be shifted into the pallet store immediately after the preceding pallet has been fed from the store or has been handled by the pallet handling equipment for shifting into the store.

3. A pallet store as claimed in claim 1 or 2, wherein the pallet handling equipment is installed on a lifting slide which can move vertically.

4. A pallet store as claimed in claim 3, wherein the lifting slide moves vertically along guides which are mounted on a vertical frame journalled for turning relative to said substantially vertical axis.

5. A pallet store as claimed in claim 4, wherein lifting mechanism of the lifting slide is installed in the vertical frame, and wherein a power transmission member for transmitting lifting power is passed from the lifting mechanism via the vertical frame to the lifting slide.

6. A pallet store as claimed in claim 4 or 5, wherein the vertical frame is journalled by its top end on a frame of the pallet store and by its bottom end on the floor or on the frame of the pallet store.

7. A pallet store as claimed in any one of the preceding claims, wherein said substantially vertical axis coincides with the vertical centre axis of the pallet store.

8. A pallet store as claimed in any one of the preceding claims, wherein viewed in the vertical direction, the cross-sectional form of the pallet store is substantially that of a regular polyhedron to at least one of the faces of which a machining center, an NC-machine tool, or some other machine or device is connected.

9. A pallet store as claimed in any one of the preceding claims for storing pallets that are machining pallets and/or transport pallets.

10. A pallet-store substantially as hereinbefore described with reference to the accompanying drawings.