GB2087764A

GB2087764A - Pallet for workpieces

Info

Publication number: GB2087764A
Application number: GB8129402A
Authority: GB
Original assignee: Reishauer AG
Current assignee: Reishauer AG
Priority date: 1980-11-26
Filing date: 1981-09-29
Publication date: 1982-06-03
Also published as: IT1144881B; IT8168263A0; JPS5796942A; DE3135009C2; JPH0144467B2; DK432981A; SE451004B; GB2087764B; DK150335C; SE8105643L; CH647739A5; DE3135009A1; DK150335B

Abstract

A pallet for conveying and storing workpieces intended for use in conjunction with devices for automatically loading workpieces into machine tools is formed with a number of regularly spaced workpiece receiving holes 3, and formations 5 which are used as entraining means when moving the pallet. The bottom surface of the pallet may be formed with a longitudinal groove 15 for cooperation with a guide rail. If a number of pallets are disposed laterally adjacent one another, the formations 5 of one pallet engage recesses 16 in the neighbouring pallet. <IMAGE>

Description

SPECIFICATION Pallet for workpieces This invention relates to a pallet for conveying and storing workpieces more particularly for an automatic device for loading workpieces on to machine tools, the pallet having regularly spaced formations for receiving workpieces and manipulation parts by which the pallet may be gripped and moved through such a device.

Swiss Patent Specification 570,237 describes a device for supplying and removing pallets of the aforementioned kind bearing workpieces. The work pieces take up a guided position, depending on the manufacturing conditions, and are thus supplied on the palletto the device for loading and unloading a machine tool. Workpieces are taken in succession from the pallet and, after being machined, are returned to the pallet at the same place and in the same guided position. The pallets are disposed parallel to one another and at uniform intervals on a conveyor and are moved stepwise by a timing means. The device has automatic gripping means for taking individual pallets from the conveying means or pushing a pallet off a guide rail.Means are also provided for supplying the pallet to the device for loading and unloading the machine tool, for rhythmically conveying the pallet through the device and for returning the pallet, bearing machined workpieces, to the conveyor or the guide rail thereon.

The pallet discussed in Swiss Patent Specification No. 570,237 can be moved longitudinally only by being guided along a straight bar engaging a longitudinal groove formed in the base of the pallet member. The two longitudinal sides of the pallet are formed with V-shaped grooves at an angle to the direction of motion, the spacing and position of the grooves coinciding with that of the workpiecereceiving holes on the top side of the pallet. These V-shaped grooves can be used with only one embodiment of a mechanism for gripping and cyclically moving the pallets forward.

The aforementioned pallet has a completely symmetrical cross-section, so that pallets can be inserted with their longitudinal sides the wrong way round on the supply or conveying means. For example, when taps having three grooves are machined on a thread-grinding machine, it is important that the tap workpieces, which are guided along the square tap shaft, should also retain their position relative to one of the two longitudinal sides, which has to be marked, and for the pallets to be all inserted in the same manner relative to the marked side.

Another disadvantage of the known embodiments is that when pallets bearing workpieces are moved by hand, they have to be grasped individually, since if two or more closely adjacent pallets are taken hold of they may easily slip apart and fall to the ground. It is also impossible to dispose the pallets on storage plates or the like so that their longitudinal sides are in the right position and they cannot fall out.

The object of the invention is to produce a pallet which can keep an unambiguous, guided position and can also be mechanically secured. The pallet must also be designed so that it is versatile in use, i.e. can be used with a number of different devices for gripping and rhythmically moving it. Finally, it must be possible for a numer of parallel pallets to be gripped together without difficulty.

According to the invention there is provided a pallet for conveying and storing workpieces, more particularly for an automatic device for loading workpieces on to machine tools, the pallet having regularly-spaced formations for receiving work pieces and manipulation parts by which the pallet may be gripped and moved through such a device, wherein the manipulation parts include cams dis posed along a longitudinal side of the pallet, the number and spacing of the cams corresponding to that of the receiving formations and the other longitudinal side of the pallet is formed with a recess for receiving the cams of an adjacent, identical, pallet if the latter pallet is brought against the side of the first mentioned pallet.

An embodiment of the invention will now be described in detail with reference to the drawings, in which Figure 1 is a perspective view of a pallet with holes for receiving workpieces; Figure 2 is a perspective view of another pallet having spigots for receiving workpieces; Figure 3 shows a view in section through the pallet of Figure 1, with a second pallet alongside being diagrammatically indicated, the section being along the line Ill-Ill in Figure 4, and Figure 4 is a view, partly in section, through a store in which the pallet of Figures 1 and 3 is disposed.

In the embodiment described here, a pallet 1 is designed to receive guided workpieces in a single row in the longitudinal direction. Pallet 1, which is made of plastics or metal or the like, has a number of holes 3 in its top surface 2 for receiving the workpieces. Holes 3 are square, since they are adapted to receive tools in guided manner, and are all diposed in exactly corresponding positions. If the workpieces are to be returned to exactly the same, guided position in pallet 1,the device for loading and unloading the machine tool must return the workpieces to pallet 1 in the same guided position from which they were taken when the pallet 1 was loaded.

The distances B between the holes 3 in the longitudinal direction of pallet 1 are adapted to the shape or diameter of the workpieces. A pattern of grooves 4 are formed in one of the two longitudinal sides of pallet 1 at an angle to the direction of motion of the pallet and can have e.g. a V cross-section and enable pallet 1 to be gripped by suitable gripping devices on the machine tool when the pallets are cyclically guided through the workpiece charging and return station or when pallet 1 is introduced or discharged. In order to meet the requirements of other systems of devices for supplying or movig pallets through, one longitudinal side of pallet 1 is formed with cams 5 which have two flat abutment surfaces 7, 8 at an angle to the direction of motion of pallet 1 and projecting vertically from the side surface 6 of the pallet.The spacing C between the cams corresponds to the spacing D between the pattern of grooves 4 and the spacing B between the centres of holes 3. The positions of grooves 4, cams 5 and holes 3 must not coincide in the longitudinal direction of pallet 1. The longitudinal side bearing cams 5 has further projections 13, the height E of which corresponds to that of cams 5. The top surfaces 11, 12 of cams 5 and projections 3 are aligned in a plane 6 parallel to the longitudinal side of pallet 1.

Pallet 1 has a square cross-section formed by the bottom surface 9, plane 6, side surface 10 and top surface 2. Projections 13 are used only to obtain an unambiguous given geometrical abutment in the case when pallet 1 has to be guided in a U-shaped guide, or if a number of pallets 1 have to be disposed in a line alongside one another, e.g. on a storage plate 14. A U-shaped channel guide will be used e.g.

if, for any reason, pallet 1 is not guided along its bottom longitudinal groove 15. The presence of two guide facilities greatly increases the range of application of the pallet 1 according to the invention.

Projections 13 can also be continuous strips. When pallets 1 are in close-set rows and hold workpieces, it is very important for the cleaning fluid to flow between pallets 1 and thus entrain dirt. For this reason, the strip is not made continuous.

The other longitudinal side 10 is formed with two grooves 16, 17 which can receive the aforementioned cams 5 and projections 13 when pallets 1 are pushed together side by side. In this manner a number of pallets 1 in lateral contact can be gripped and raised by a single hand, since the cams and projections 13 engage in grooves 16, 17 and the pal lets cannot slide apart or fall to the ground, more particularly when they bearworkpieces and are therefore heavy.

When pallets are moved alongside, the top surfaces 11,12 of cams 5 and projections 13 of one pallet 1 touch the bottom surfaces 18, 19 of grooves 16, 17 of the other pallet 1. The height E of cams 5 and projections 13 is greater than the depth F of grooves 16 and 17, so that when the long sides of two pallets 1 abut, a gap having the width G is left through which the cleaning fluid can flow.

When, for example, three-slotted taps are being machined on a thread-grinding machine it is important that the position of the tap workpieces, which is guided around the square tap shaft, should be also maintained relative to one of the two longitudinal sides 6 and 10. The method hitherto has been to mark one of the sides 6 or 10 so that the flutes of the tap workpieces can always keep exactly the same position relative to it. Another condition is that when the pallets are inserted into the conveyor or the like, the marked sides of the pallets are disposed in corresponding positions. Since the pallets are initially inserted by hand, they may have their sides reversed by mistake.

The longitudinal groove 15 is placed eccentrically relative the side surfaces 6, 10 so that if pallet 1 is placed with its sides reversed, the pallet can be stopped by suitable auxiliary devices. If the pallet is being guided along a straight bar engaging in longitudinal groove 15, a pallet 1 inserted with sides reversed can be stopped e.g. by a shutter having a width and position corresponding to the pallet cross-section. Alternatively, if pallet 1 is guided along its outer surface, e.g. in a U-shaped section member, a pallet 1 inserted with its sides reversed can be stopped e.g. by a cam having a side and position corresponding to groove 15.

The pattern of grooves 4 and cams 5 disposed on one side also ensures that if pallet 1 is inserted with its sides reversed it will not be gripped by the gripping means or rythmically conveyed by the stations for loading and returning workpieces from the machine tool. Even if no workpiece is damaged, operation is interrupted and adversely affects the manufacturing time.

In order to ensure that pallets 1 are disposed on the right side, even during preliminary treatment, the end surfaces 20, 21 of pallet 1 have transverse grooves 22, 23 respectively at different distances H, K from the bottom surface 9, so that pallet 1 must be in a single given position to be pushed on to storage plate 14 or the like, since on one side of the storage plate there is a guide rail 24 which engages in groove 22 or groove 23. The U-shaped construction of plate 14 or the like and the guide rail 24 secured thereon prevent the pallets from changing position or falling out.

As shown in Figure 3, the receiving holes 3 may be through holes opening into the bottom longitudinal groove 15, each hole having a constriction 25 for supporting the bottom of a workpiece inserted into the hole.

In another embodiment of pallet 1 according to Figure 2, holes 3 are replaced by upwardly projecting spigots 26 for receiving workpieces having an inner bore. As before, the cross-sectional shape must be adapted to that of the inner bore of the workpiece. In other respects, like parts bear reference numbers corresponding to those in the previously-mentioned embodiment.

Claims

1. A pallet for conveying and storing workpieces, more particularly for an automatic device for loading workpieces on to machine tools, the pallet having regularly-spaced formations for receiving workpieces and manipulation parts by which the pallet may be gripped and moved through such a device, and wherein the manipulation parts include cams disposed along a longitudinal side of the pallet, the number and spacing of the cams corresponding to that of the receiving formations, and the other longitudinal side of the pallet is formed with a recess for receiving the cams of an adjacent, identical, pallet if the latter pallet is brought against the side of the first-mentioned pallet.

2. A pallet according to claim 1, in which the two end faces of the pallet have distinguished features which can be mechanically scanned.

3. A pallet according to claim 2, in which the distinguishing features are transverse grooves disposed at different distances from the bottom surface of the pallet.

4. A pallet according to claim 1, in which the longitudinal side having the cams is provided with additional projections having a height equal to that of the cams, and the opposite side of the pallet has another recess for receiving such additional projections of an adjacent identical pallet.

5. A pallet according to claim 4, in which the top surfaces of the cams and said additional projections lie in a plane parallel to the longitudinal sides of the pallet so that the pallet, which has a rectangular cross-section, can be moved longitudinally along a U-shaped guide track.

6. A pallet according to claim 1, in which the workpiece receiving formations are upwardly projecting spigots or holes.

7. A pallet according to claim 1, in which in addition to the cams there are other, differentlyshaped manipulation parts, the number and spacing of which likewise correspond to that of the receiving components.

8. A pallet according to claim 7, in which the position of the manipulation parts is the same or different relative to one another and also relative to the receiving formations in the longitudinal direction of the pallet.

9. A pallet according to claim 1, in which the cams have each two transversely extending flat abutment surfaces projecting vertically from the side surface of the pallet.

10. A pallet according to claim 4, in which the height of the cams and said additional projections is greater than the depth of said recesses so that when the longitudinal sides of identical pallets abut, a gap is left therebetween through which a cleaning fluid can flow.

11. A pallet according to claim 6, in which the receiving formations are through holes opening into a bottom longitudinal groove of the pallet, each hole having a constriction for supporting the bottom of a workpiece inserted into the hole.

12. A pallet according to claim 11, in which the bottom longitudinal groove is eccentrically disposed relative to the side surfaces of the pallet.

13. A pallet substantially as hereinbefore described with reference to, and as shown in, Figures 1, 3 and 4 of the accompanying drawings.

14. A pallet substantially as hereinbefore described with reference to, and as shown in, Figure 2 of the accompanying drawings.

15. Any novel feature or combination of features described herein.