Workpiece stocker

Abstract

The present invention provides a workpiece stocker with replaceable workpiece transfer tables.　Provided is a workpiece stocker with a replaceable pallet (11), the workpiece stocker including: a roller chain (13) looped in an oval shape around two sprockets; a drive motor that rotates one of the sprockets; and a plurality of workpiece transfer tables (3) lined up in the circumferential direction and mounted to the roller chain; and a control device that causes a designated workpiece transfer table from among the workpiece transfer tables, which move all together by control over the drive motor, to stop at a set position. Between the workpiece transfer tables and the roller chain, an attachment / detachment section is configured to allow detachment of the workpiece transfer tables from the roller chain. For example, the attachment / detachment section is configured such that coupling pins (55) that couple an outer link (52) and an inner link (51) constituting the roller chain are hollow in shape, and the workpiece transfer tables have formed thereon mounting pins (27) that can be inserted into the coupling pins.

Description

Work Stocker

[0001] The present invention relates to a work stocker with a replaceable work transport table.

[0002] In automatic machining using machine tools, a work stocker is used to load multiple workpieces and transport them in order to a predetermined position to supply them to the machine tool. Patent Document 1 below discloses a conventional work stocker. In this work stocker, an endless chain is hung on a pair of sprockets on a table, and multiple workpiece carriers are connected to the endless chain. The multiple workpiece carriers are then moved simultaneously in the circumferential direction by drive control of the work stocker, and the corresponding workpiece carrier is positioned at, for example, the transfer position of an autoloader.

[0003] Japanese Patent Application Publication No. 4-354649

[0004] A work stocker is loaded with a variety of workpieces to be processed by machine tools, and these workpieces vary in size. Conventional work stockers used the same work transport table with a pallet to accommodate workpieces from small to large, so the pallet was designed to accommodate the largest workpiece. However, while the work transport table designed for the largest workpiece was capable of loading all workpieces, it was not possible to increase the total number of workpieces that could be loaded on the work stocker when processing small workpieces. In other words, the larger the pallet, the fewer work transport tables could be attached to the work stocker, and therefore there was a limit to the number of workpieces that could be loaded.

[0005] SUMMARY OF THE INVENTION In order to solve this problem, an object of the present invention is to provide a work stocker in which the work transport table is replaceable.

[0006] In one aspect of the present invention, a work stocker comprises a roller chain stretched around two sprockets in an oval shape, a drive motor that imparts rotation to one of the sprockets, a plurality of work transport tables attached in a circumferential row to the roller chain, and a control device that stops a suitable one of the work transport tables moving simultaneously at a set position by controlling the drive motor, and a detachable section is configured between the work transport table and the roller chain that allows the work transport table to be detached from the roller chain.

[0007] According to the above configuration, the roller chain is rotated by the control of the drive motor by the control device, and the multiple work transport tables attached thereto move in a line in the circumferential direction, and a corresponding work from among them stops at a set position, for example, where the work is to be loaded or unloaded. In such a work stocker, a detachable attachment / detachment part is configured between the work transport table and the roller chain, and the work transport table can be removed from the roller chain, so that it is possible to replace, for example, a work transport table that needs to be replaced due to a malfunction or a work transport table that matches the size of the work.

[0008] FIG. 1 is a perspective view showing an embodiment of a work stocker. FIG. 2 is an internal plan view showing an embodiment of a work stocker. FIG. 3 is a perspective view showing a work transport table. FIG. 4 is a cross section cut at a straight portion on one side of a roller chain that is hung in an oval shape at a reversal point where a sprocket is located. FIG. 5 is a cross section of the work transport table. FIG. 6 is a perspective view showing the work transport table from below. FIG. 7 is a plan view showing an image of a work stocker equipped with work transport tables of different sizes. FIG. 8 is a flow chart showing work transport processing by a work transport program.

[0009] An embodiment of a workpiece stocker according to the present invention will be described below with reference to the drawings. Figures 1 and 2 show one embodiment of the workpiece stocker, with Figure 1 being a perspective view and Figure 2 being an internal plan view. The workpiece stocker 1 of this embodiment is installed in a processing machine line in which a plurality of machine tools and the like are arranged side by side, and functions as a workpiece supply device that supplies workpieces to the processing machine line, and a workpiece recovery device that recovers machined workpieces.

[0010] The work stocker 1 is entirely covered by an exterior cover 2, and contains a work transport mechanism 5. The work transport mechanism 5 has a plurality of work transport tables 3 on which workpieces can be stacked, and is configured to position the corresponding work transport table 3 at the work delivery position P. In this embodiment, 18 work transport tables 3 are arranged in a line on an oval track, and are connected by an endless roller chain 13 shown by the dashed line in Fig. 2, so that they move simultaneously in the circumferential direction and stop at predetermined positions.

[0011] A pair of sprockets 15, 16 are journaled at the front and rear of the work stocker 1, with a roller chain 13 stretched across them. A drive motor 14 is connected to the sprocket 15 on the rear side of the machine body, and the roller chain 13 is rotated a predetermined amount in a predetermined direction by controlling the drive, so that the 18 work transport tables 3 move all at once. In this work stocker 1, the turn-back position of the sprocket 16 becomes the work transfer position P, and multiple workpieces stacked on the work transport table 3 are transported out by an autoloader, or machined workpieces are transported in.

[0012] Next, Figure 3 is a perspective view showing the workpiece conveying table 3. Three guide rods 21 that penetrate the pallet 11 are projected vertically into the workpiece conveying table 3. Three slits 22 are formed radially at 120-degree intervals in the disk-shaped pallet 11, and the three guide rods 21 are erected so as to pass through the three slits 22. These three guide rods 21 can be adjusted in the radial direction to match the size of the workpiece by moving within the slits 22.

[0013] The workpiece conveying table 3 has one transmission gear 25 journaled on a base plate 23, and three adjustment gears 26 journaled around the transmission gear 25 engage with the transmission gear 25. The pallet 11 is positioned so that its center coincides with the rotation center of the transmission gear 25, and the three adjustment gears 26 are positioned so that their rotation centers are spaced 120 degrees apart from the central transmission gear 25. Guide rods 21, each aligned with the three adjustment gears 26, are fixed in a vertically upright position.

[0014] The position of the workpiece transport table 3 can be adjusted by an operator by moving the guide rods 21 radially along the slits 22. That is, the three adjustment gears 26 rotate simultaneously by the same angle via the transmission gear 25, and accordingly, the three guide rods move simultaneously by the same distance in the radial direction. Therefore, by adjusting the workpiece transport table 3 by an operator, the three guide rods 21 protruding from the pallet 11 are positioned on the same circumference in accordance with the size of the workpiece. In this way, the workpiece stocker 1 can accommodate workpieces of various sizes.

[0015] However, if all work transport tables 3 are the same size, when small workpieces are to be transported, the empty space on the pallet 11 becomes large and wasteful. That is, the work stocker 1 shown in Figures 1 and 2 has 18 work transport tables 3 connected to the endless roller chain 13, which affects the size of the pallet 11. Therefore, if the pallet 11 could be made smaller, it would be possible to connect even more work transport tables 3 to a roller chain 13 of the same length. That is, the amount of workpieces that can be loaded on the work stocker 1 can be increased.

[0016] Therefore, the work stocker 1 of this embodiment is provided with a structure that allows the work transport table 3 to be replaced with respect to the roller chain 13. Figures 4 and 5 are cross-sectional views showing the structure for replacing the work transport table 3. In particular, Figure 4 is a cross-section taken at a straight portion on one side of the roller chain 13 that is stretched over in an oval shape at the reversal point where the sprocket 15 (16) is located. Figure 5 is a cross-sectional view of the work transport table 3. Furthermore, Figure 6 is a perspective view showing the work transport table 3 from below.

[0017] The roller chain 13 is composed of inner links 51 and outer links 52 connected alternately. The inner links 51 are roller links, with two hollow bushings press-fitted between two inner plates, and hollow rollers fitted around the outside of each bushing. The outer links 52 are pin links, with two connecting pins 55 press-fitted into the two outer plates. The connecting pins 55 pass through the bushings of the inner links 51, connecting the inner links 51 and the outer links 52 alternately to form the roller chain 13. The roller chain 13 of this embodiment in particular uses hollow connecting pins 55, which serve as positioning holes for the workpiece transport table 3.

[0018] The workpiece transport table 3 has a lower plate 24 stacked on the underside of a base plate 23, and two retaining pins 27 fixed to the base plate 23 so as to protrude downward from the lower plate 24. The spacing between the two retaining pins 27 matches the spacing between the two connecting pins 55 of the outer links 52 that make up the roller chain 13, and they are formed with a thickness that allows them to be inserted into the pipe-shaped connecting pins 55. The two retaining pins 27 are formed so as to be positioned closer to the roller chain 13 than the transmission gear 25, which is located in the center.

[0019] Furthermore, in the work stocker 1, the work transport table 3, which moves while being pulled by the roller chain 13, is configured so that its lower plate 24 is supported by support rollers 17, as shown in Fig. 5. A plurality of support rollers 17 are arranged along the roller chain 13, at the outer position of the oval shown in the figure, and at the inner position of the oval not shown in the figure. Therefore, the work transport table 3, which moves in the circumferential direction, is pulled by the roller chain 13 via the mounting pins 27, and is supported by the support rollers 17, so that the base plate 23 moves while maintaining a horizontal attitude.

[0020] The work stocker 1 is provided with a plurality of types of work transport tables 3 of different sizes depending on the size of the workpieces. Figure 7 is a plan view conceptually showing a work stocker equipped with such work transport tables 3 of different sizes. The drawing shows two types of work transport tables 3 (31, 33) of different sizes. The different-sized work transport tables 31, 33, etc. provided for the work stocker 1 all have the same configuration as the work transport table 3 shown in Figure 3, etc., and the base plate 23, adjustment gear 26, etc. are designed according to the diameter of the pallet 11.

[0021] Furthermore, the position of the retaining pins 27 and the size of the lower plates of the work transport tables 31, 33, etc. are designed so that the lower plates rest on the support rollers 17. However, even if the sizes are different, the work transport tables 31, 33, etc. have the same two retaining pins 27, and are configured so that they can be inserted into the connecting pins 55 of the outer links 52. Therefore, for the work stocker 1, the work transport tables 3 (31, 33, etc.) can be selected according to the size of the work, and any combination can be made within the range of the length of the roller chain 13.

[0022] The work stocker 1 is configured with a pallet lifting device 18 at the workpiece transfer position P. The pallet lifting device 18 has a vertical support column 41 fixed to the front of the machine body, and a lifting platform 42 attached to a slide rail formed on the vertical support column 41. A two-pronged support plate 43 that supports the pallet 11 from below is fixed to the lifting platform 42, and an elevator that moves the lifting platform 42 up and down is provided inside the support column 41. The lifting platform 42 is fixed to an elevator chain that is stretched between upper and lower sprockets, and the height of the lifting platform 42 is adjusted by driving an elevator motor connected to one of the sprockets.

[0023] Incidentally, in conventional work stockers, all identical work transport tables are arranged at equal intervals, so positioning at the work transfer position P can be controlled by detecting the rotation angle of the drive motor with a proximity switch. However, in a work stocker 1 that can accommodate work transport tables 3 of different sizes, as in this embodiment, it is difficult to accurately stop the work transport table at the work transfer position P with conventional drive control. Therefore, as shown in Figure 6, the work stocker 1 is configured so that a dog 35, which is a detectable object, is fixed to the lower plate 24 of each work transport table 3, and by detecting this, a specified work transport table 3 is stopped at a set position.

[0024] The work stocker 1 requires accurate stopping control to stop the work transport table 3 at the work transfer position P and to reliably raise and lower the pallet 11. Therefore, as shown in Figure 7, deceleration proximity switches 37 and 39 are provided on either side of a stop proximity switch 38 at the work transfer position P, and the dog 35 is detected at each position. The control device 6, which controls the drive of the work stocker 1, stores a work transport program for executing drive control of the drive motor 14 in response to detection signals from the stop proximity switch 38 or the deceleration proximity switches 37 and 39.

[0025] Information regarding the number and arrangement (position numbers, etc.) of the work transport tables 3 (31, 33, etc.) mounted on the work stocker 1 is input to the control device 6, and a predetermined work (work transport table 3) is selected in accordance with the machining program for the machining line. Therefore, in accordance with a work transport command from the machining program, a corresponding one of the multiple work transport tables 3 is sent to the work delivery position P. At this time, in the work transport program, based on the work transport command, the work transport tables 3 simply move one by one to the next, or move several at a time, or such movement is performed by changing the direction of rotation.

[0026] 8 is a flowchart showing the workpiece transport process according to the workpiece transport program. In the workpiece transport process, first, movement information is obtained for the workpiece transport table 3 on which the corresponding workpiece is mounted based on the workpiece transport command (S101). The movement information is information for the corresponding workpiece transport table 3 to move the shortest distance to the workpiece delivery position P, and the rotation direction of the roller chain 13 (drive motor 14) and the number of the workpiece transport table 3 in that rotation direction are obtained from the count number N. Then, rotation control of the drive motor 14 in the specified direction is started (S102).

[0027] After the drive motor 4 starts to drive, the count number N is checked to determine whether the corresponding work transport table 3 is identified (S103). That is, by checking whether the count number N is "1", it is determined whether the next work transport table 3 moving to the work transfer position P will be the target of detection by the stop proximity switch 38. If the count number N is not "1" (S103: NO), the detection signal of the stop proximity switch 38 is ignored to allow the inappropriate work transport table 3 to pass, and the count number N is counted down by "1" in accordance with the detection signals of the two deceleration proximity switches 37, 39 (S104: YES) (S105).

[0028] Thereafter, in accordance with steps S103-S105, the roller chain 13 is rotated by the driving motor 14, and the non-matching workpiece conveying table 3 passes through the workpiece transfer position P. Then, when the count number N becomes "1" (S103: YES), the workpiece conveying table 3 that has reached the workpiece transfer position P is controlled to stop.

[0029] In the stop control, a detection signal transmitted by the deceleration proximity switch 37 (or 39) upon detection of the dog 35 is confirmed (S106). Then, deceleration control of the drive motor 14 is performed in accordance with the detection signal, and the moving speed of the workpiece conveying table 3 decreases just before the workpiece transfer position P (S106: YES, S107). Next, a detection signal transmitted by the stop proximity switch 38 upon detection of the dog 35 is confirmed (S106). Then, stop control of the drive motor 14 is performed in accordance with the detection signal, and the workpiece conveying table 3 stops at the workpiece transfer position P (S108: YES, S109), and the workpiece conveying process ends.

[0030] Therefore, in the work stocker 1 of this embodiment, since the work transport tables 3 can be attached and detached, it is easy to replace a work transport table 3 that needs to be replaced due to a malfunction or the like. Also, by providing work transport tables 3 of different sizes, the number of workpieces that can be loaded can be increased in the case of small workpieces. In the example shown in Figure 7, only ten large work transport tables 31 can be attached to the roller chain 13, but by replacing half of those, or five, it is possible to attach ten small work transport tables 33. In other words, twice as many small workpieces can be loaded on the work stocker 1 compared to when only the work transport tables 31 are used.

[0031] Furthermore, the workpiece transport table 3 can be removed simply by inserting the retaining pin 27 into the roller chain 13, making replacement extremely simple. Furthermore, the configuration of the workpiece transport table 3 and other components does not require significant changes compared to conventional systems, so the above-mentioned effects can be achieved by making slight improvements to conventional workpiece stockers. Furthermore, with regard to positioning control to stop the workpiece at the workpiece transfer position P, it is only necessary to add a small amount of configuration, such as the dog 35, the stop proximity switch 38, the deceleration proximity switches 37 and 39, and a workpiece transport program.

[0032] Although one embodiment of the present invention has been described, the present invention is not limited to this, and various modifications are possible without departing from the spirit of the present invention. In the above embodiment, the dog 35 is detected by the stop proximity switch 38 and the deceleration proximity switches 37, 39, and stop control of the workpiece conveying table 3 at the workpiece transfer position P is performed, but stop control may be performed using a different configuration.

[0033] DESCRIPTION OF SYMBOLS 1...Work stocker 3 (31, 33)...Work transport table 5...Work transport mechanism 6...Control device 11...Pallet 13...Roller chain 14...Drive motor 15, 16...Sprocket 18...Pallet lifting device 21...Guide rod 23...Base plate 27...Mounting pin 35...Dog 37, 39...Deceleration proximity switch 38...Stop proximity switch 51...Inner link 52...Outer link 55...Connecting pin P...Work transfer position

Claims

1. A work stocker comprising: a roller chain stretched around two sprockets in an oval shape; a drive motor that imparts rotation to one of the sprockets; a number of work transport tables attached in a row circumferentially to the roller chain; and a control device that stops a relevant one of the work transport tables which move in unison at a set position by controlling the drive motor, wherein a detachable section is configured between the work transport table and the roller chain to enable the work transport table to be detached from the roller chain.

2. A work stocker as described in claim 1, wherein the detachable portion has a hollow connecting pin that connects the outer link and inner link that make up the roller chain, and the work transport table has an attachment pin that can be inserted into the connecting pin.

3. A work stocker according to claim 1, wherein the plurality of work transport tables attached to the roller chains include work transport tables of different sizes.

4. A work stocker as claimed in any one of claims 1 to 3, wherein a detectable object is attached to the work transport table, a positioning detection member is provided at the set position, and the control device performs stop control to position the corresponding work transport table at the set position in accordance with a detection signal corresponding to the detectable object by the positioning detection member.

5. A work stocker as described in claim 4, wherein the positioning detection members are a stopping proximity switch for stopping the work transport table at the set position, and a deceleration proximity switch for slowing down the moving speed to the stopping position.

Images