Circulating pallet transport device

Abstract

To provide a circulation type pallet carrying device which can easily change an interval between pallets and is relatively low-cost.SOLUTION: A circulation type pallet carrying device includes an upper and lower guide rails 21, 31 which are separated in a vertical direction and are provided in parallel to each other, upper and lower pallet sending means 40, 50 which carry a pallet 15 along the upper and lower guide rails 21, 31 and pallet lifting means 60 which lifts the pallet 15 and moves from the upper or lower guide rail to the lower or upper guide rail. The upper pallet sending means is a linear motor 40 which has a fixer 41 continuously provided along the upper guide rail 21 and a movable element 42 provided on the pallet 15 so as to be opposed to the fixer 41, and the lower pallet sending means 50 contains such a movable body 51 that the pallet 15 provided along the lower guide rail 31 is constituted so as to be engageable. Belts 51 as the movable body are provided protrusively from both sides of the lower guide rail 31.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a circulating pallet transport device that transports pallets on which workpieces can be mounted in a circulating manner. [Background technology]

[0002] Conventionally, a pallet conveying device has been known in a manufacturing line, in which workpieces to be processed are placed on a pallet and the pallet is conveyed together with the workpieces. In this pallet conveying device, a machine tool at a processing station to which the workpieces are conveyed performs predetermined processing on the workpieces placed on the pallet. The applicant has proposed a pallet conveying device that conveys a plurality of pallets carrying workpieces to the processing station in a circulating manner along a square orbit (see, for example, Patent Document 1).

[0003] This pallet conveying device has a structure in which a belt is provided along a rail on which the pallet is movably mounted, a pallet is formed so that it can engage with this belt, and the belt is circulated to convey the pallet engaged with the belt along the rail.

[0004] Furthermore, a linear conveyor using a linear motor has been proposed as a pallet transport device that transports pallets mounted on rails along the rails without using such a belt (see, for example, Patent Document 2). With this linear conveyor, the pallets are moved by a linear motor, and it is expected that multiple pallets mounted on rails can be transported quickly. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-93032 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-49109 Summary of the Invention [Problem to be solved by the invention]

[0006] However, a pallet conveying device that engages a pallet with a belt engages the pallet at any position on the circulating belt. Therefore, when multiple pallets are mounted on a rail, all of the multiple pallets engage with a single belt, making it difficult to change the spacing between the multiple pallets while they are mounted on the rail, which remains an issue that needs to be resolved.

[0007] On the other hand, in a linear conveyor using a linear motor, the pallets are moved by the linear motor, which makes it possible to easily change the spacing between multiple pallets while they are mounted on the rail. However, a linear motor has a stator with multiple armature coils and a mover with magnetic poles attached to the pallet so as to face the stator, and is known to be relatively expensive due to its complex structure.

[0008] Therefore, in a circulating pallet conveying device that circulates pallets by moving them forward and then back, if a linear motor is used for all of the pallet's reciprocating movements, there is a problem in that the unit price of the circulating pallet conveying device will be significantly increased.

[0009] SUMMARY OF THE INVENTION An object of the present invention is to provide a relatively inexpensive circulating pallet transport device that can easily change the spacing between pallets that are mounted on rails on the working side and move. [Means for solving the problem]

[0010] The present invention is an improvement to a circulating pallet transport device that includes upper and lower guide rails that are arranged parallel to each other and spaced apart vertically and on which pallets are movably mounted, upper and lower pallet feeding means that transport the pallets along the upper and lower guide rails, and pallet lifting means that are arranged at both ends of the upper and lower guide rails and that lift and lower the pallets, moving them from the upper or lower guide rail to the lower or upper guide rail.

[0011] Its distinctive configuration is that the upper pallet feeding means is a linear motor having a stator arranged continuously along the upper guide rail and a movable element arranged on the pallet opposite the stator, and the lower pallet feeding means includes a moving body arranged along the lower guide rail so that the pallet can be engaged.

[0012] If the moving body is a belt that is endlessly circulated along the lower guide rail, it is preferable that the belt protrudes from both sides of the lower guide rail so as to engage with the pallet lowered by the pallet lifting means, and if unevenness extending in the width direction is formed on the belt alternately and continuously in the longitudinal direction, it is preferable that unevenness be formed on the pallet that can engage with the unevenness when mounted on the lower guide rail.

[0013] On the other hand, the pallet lifting means preferably comprises a short rail on which the pallet is movably mounted, a lifting means for raising and lowering the short rail between an elevated position in which it communicates with the upper guide rail and a lowered position in which it communicates with the lower guide rail, and a stator that is provided along the short rail and, together with a movable element provided on the pallet, forms a linear motor to move or stop the pallet mounted on the short rail. [Effects of the Invention]

[0014] In the circulating pallet conveying device of the present invention, a linear motor is used as the upper pallet feeding means for moving the pallet mounted on the upper guide rail, so even if multiple pallets are mounted on the upper guide rail, the spacing between the multiple pallets can be easily changed while they are mounted on the rail.

[0015] On the other hand, since a moving body is used as the lower pallet feeding means for moving the pallet mounted on the lower guide rail, it can be made cheaper than a linear motor.

[0016] Therefore, by making the upper guide rail the working side, it is possible to provide a relatively inexpensive circulating pallet conveying device that can easily change the spacing between pallets that are mounted on the rail and move. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a front view of a circulating pallet transport device according to an embodiment of the present invention. FIG. [Figure 2] FIG. 2 is a top view of the circulating pallet transport device. [Figure 3] 2 is a cross-sectional view taken along line AA in FIG. 1, showing the pallet feeding means. [Figure 4] 2 is a cross-sectional view taken along line BB in FIG. 1, showing the pallet lifting means. [Figure 5] FIG. 10 shows the pallet moving from the upper guide rail to the short rail. [Figure 6] FIG. 10 is a diagram showing the state in which the short rail descends together with the pallet. [Figure 7] 10 is a diagram showing the state in which the pallet moves from the lower guide rail to the short rail. [Figure 8] FIG. 10 is a diagram showing the state in which the short rail rises together with the pallet. DETAILED DESCRIPTION OF THE INVENTION

[0018] Next, an embodiment of the present invention will be described in detail with reference to the drawings.

[0019] 1 and 2 show a circulating pallet transport device 10 according to the present invention. In each figure, three mutually orthogonal axes, X, Y, and Z, are set, with the X axis extending in a substantially horizontal lateral direction, the Y axis extending in a substantially horizontal front-rear direction, and the Z axis extending in a vertical direction. The configuration of this circulating pallet transport device 10 will be described below.

[0020] This circulating pallet conveying device 10 conveys a pallet 15 carrying workpieces in one direction (X-axis direction), stops the pallet 15 in front of machine tools 1 to 5 (Figure 2) arranged along the conveying path, maintains this state, and allows the machine tools 1 to 5 to process the workpieces carried on the pallet 15.After all the workpieces have been processed, the pallet 15 alone is conveyed in the opposite direction to return it to its original position, and then the workpieces are loaded and conveyed in one direction again, and the newly loaded workpieces are processed.This is the type of device used.

[0021] Although Figure 2 shows five machine tools 1 to 5 lined up, this is just one example, and the number of machine tools 1 to 5 varies depending on the workpieces that need to be machined, and the number of pallets 15 is increased or decreased as appropriate depending on the number of machine tools 1 to 5.

[0022] As shown in Figure 1, this circulating pallet conveying device 10 comprises upper and lower guide rails 21, 31 that are arranged vertically spaced apart and parallel to each other and on which a pallet 15 is movably mounted, and upper and lower pallet feeding means 40, 50 that separately transport the pallet 15 along the upper and lower guide rails 21, 31.

[0023] The upper and lower guide rails 21, 31 are provided on bases 22, 32, respectively, the lower base 32 on which the lower guide rail 31 is provided is provided on the base 9 via a pedestal 12, and the upper base 22 on which the upper guide rail 21 is provided is provided on a torii member 13 provided so as to straddle the lower base 32.

[0024] As shown in Figure 3, the base 12 in this embodiment has a base plate 12a attached to the base 9, a support plate 12b erected on the base plate 12a, and a mounting plate 12c that is provided continuously with the upper edge of the support plate 12b and has the lower base 32 attached to its upper surface.

[0025] On the other hand, as shown in Figure 1, multiple torii members 13 spanning the lower base 32 are provided on the base 9 at predetermined intervals in the X-axis direction, and the upper base 22 is erected on these multiple torii members 13 so that the upper guide rail 21 is parallel to the lower guide rail 31.

[0026] The upper base 22 and the lower base 32 have the same structure, and the upper and lower bases 22, 32 are frames made of a non-magnetic material such as aluminum and / or austenitic stainless steel. As shown in Fig. 3, a pair of rail pedestal portions 22a, 22b, 32a, 32b extending in the X direction and spaced apart in the Y direction are provided on the upper surfaces of the upper and lower bases 22, 32, and guide rails 21, 31 extending in the X direction are installed on the rail pedestal portions 22a, 22b, 32a, 32b, respectively.

[0027] The upper guide rail 21 fixed to the upper base 22 and the lower guide rail 31 fixed to the lower base 32 are the same, and even if a pallet 15 mounted on one of the guide rails 21, 31 is moved and mounted on the other guide rail 21, 31, the pallet 15 is configured to be movable mounted on the other guide rail 21, 31.

[0028] Furthermore, partition portions 22c and 32c are erected from the upper surfaces of the upper and lower bases 22 and 32 between the rail base portions 22a, 22b, 32a, and 32b to which the upper and lower guide rails 21 and 31 are attached. These partition portions 22c and 32c are also extended in the X direction like the rail base portions 22a, 22b, 32a, and 32b.

[0029] In this way, the upper and lower guide rails 21, 31 are arranged parallel to each other with a vertical gap between them via the upper and lower bases 22, 32, and the pallet 15 mounted on these upper and lower guide rails 21, 31 has a mounting plate 16 on whose upper surface a workpiece is mounted, a slider frame 17 on whose upper surface the mounting plate 16 is attached, and a linear motion block 18 attached to the underside of the slider frame 17 and configured to be movable on the guide rails.

[0030] The mounting plate 16 and slider frame 17 are made of a metal block such as aluminum, and a mounting fixture 19 for mounting a workpiece (not shown) is further provided on the upper surface of the mounting plate 16. This mounting fixture 19 is used to mount a workpiece (not shown), and the structure of this mounting fixture 19 can be modified as needed depending on the type and shape of the workpiece to be mounted on the pallet 15 and processed.

[0031] On the other hand, the linear motion block 18 is attached to the underside of the slider frame 17 at positions facing the upper and lower guide rails 21, 31. This linear motion block 18 is a commercially available product sold as a pair with the upper and lower guide rails 21, 31, and is equipped with bearings (not shown) that rotate due to relative movement with the upper and lower guide rails 21, 31.

[0032] When the linear motion block 18 is fitted into the upper or lower guide rail 21 or 31 from the X-direction end, the linear motion block 18 engages with the upper or lower guide rail 21 or 31, and the pallet 15 is thereby mounted on the upper or lower guide rail 21 or 31. The pallet 15 thus mounted is configured to move in the X-direction along the guide rails 21, 31 by upper and lower pallet feeding means 40, 50.

[0033] 1 to 3, in the circulating pallet transport device 10 of the present invention, the upper pallet feeding means for moving the pallet 15 mounted on the upper guide rail 21 comprises a linear motor 40. This linear motor 40 comprises a stator 41 that extends in the transport direction on the upper base 22 and is continuously provided parallel to the upper guide rail 21, and a mover 42 that is provided on the pallet 15.

[0034] This linear motor 40 is commercially available, and as shown in the enlarged view of Figure 1, its stator 41 has a holder 41a extending in the conveyance direction and a plurality of unit electromagnets 41b arranged in a row on the holder 41a. In the figure, the holder 41a is made of a non-magnetic material such as aluminum, and a plurality of unit electromagnets 41b are fitted into this holder 41a while being aligned in a row in the X direction.

[0035] In this way, the stator 41, in which a plurality of unit electromagnets 41b are arranged in a row in the X direction on the holder 41a, has an elongated, approximately rectangular columnar shape with rectangular end faces, similar to the upper guide rail 21. In this embodiment, the stator 41 is positioned between one of the upper guide rails 21 and the partition portion 22c and is continuously attached to the upper base 22 (Figure 3).

[0036] The mover 42, which constitutes the linear motor 40 together with the stator 41, is attached to the underside of the slider frame 17. The mover 42 includes a plurality of permanent magnets 42a (shown by dotted lines in FIG. 3) arranged in the X direction, and a back yoke 42b that holds these permanent magnets 42a. The back yoke 42b has the function of holding the permanent magnets 42a and forming a magnetic path.

[0037] 3, back yoke 42b has a gate-shaped structure that opens downward, and stator 41 is configured to fit into mover 42 that forms this gate-shaped structure. Multiple permanent magnets 42a are arranged with N poles and S poles alternately on each of a pair of side plates (surfaces facing stator 41) of back yoke 42b, and mover 42 is attached to slider frame 17 on pallet 15 in a state spaced apart and directly above stator 41.

[0038] The linear motor 40 is configured by such a mover 42 and stator 41, and is configured to be able to stop the pallet 15 mounted on the upper guide rail 21 at any position.

[0039] In this way, the circulating pallet conveying device 10 of the present invention uses a linear motor 40 as the upper pallet feeding means and stops the pallet 15 at any position, so a position detection means 46 is provided to detect the position of the pallet 15 mounted on the upper guide rail 21.

[0040] 3, a position sensor 47 is attached to the side of a partition section 22c that stands upright from the top surface of the upper base 22, and a mounting piece 17a that faces the partition section 22c while mounted on the upper guide rail 21 is attached downwardly to the lower part of the slider frame 17. A magnetic scale 48 is attached to this mounting piece 17a so as to face the position sensor 47.

[0041] Such position sensor 47 and magnetic scale 48 constitute a position detection means 46 that detects the position of the pallet 15, and the position sensor 47 is configured to detect the position of the pallet 15 mounted on the upper guide rail 21 via the magnetic scale 48 attached to the slider frame 17 on the pallet 15.

[0042] The detection output of such position detection means 46 is connected to the control input of a controller (not shown), and the controller controls the energization of the unit electromagnets 41b in the stator 41 based on the input position information, and the magnetic flux of the unit electromagnets 41b and the permanent magnet of the mover 42 attached to the slider frame 17 interacts with each other to generate a magnetic thrust force in the mover 42. This causes the pallet 15 to which the mover 42 is attached to move in the X direction and to stop at any position.

[0043] Returning to Figure 1, the lower pallet feeding means 50 that moves the pallet 15 mounted on the lower guide rail 31 comprises a moving body arranged along the lower guide rail 31, and in this embodiment the moving body is an endless belt 51 that is circulatable along the lower guide rail 31.

[0044] That is, this lower pallet feeding means 50 is configured to be able to engage with the pallet 15, and is equipped with a circular circulating belt 51 that is arranged along the lower guide rail 31 and circulates to become a moving body, and a moving means 52 that is arranged on the base 12 that supports the lower guide rail 31 and moves this circular circulating belt 51 so that it circulates.

[0045] Specifically, the base 12 is formed to have the same length as the lower guide rail 31, and support posts 53 are erected on the base 9 spaced apart from both ends of the base 12 that supports the lower guide rail 31. A pair of driven pulleys 54 spaced apart in the vertical direction are respectively provided on the support posts 53, and the circulating belt 51 is wound around these four driven pulleys 54 so as to surround them.

[0046] The support pillar 53 is erected at a distance from the edge of the lower guide rail 31 at a distance that allows for the installation of a pallet lifting means 60, which will be described later, and as a result, the driven pulley 54 is provided at a distance from the edge of the lower guide rail 31, and the belt 51 that is looped around this has its upper side extending along the lower guide rail 31 and protruding from both sides of the lower guide rail 31. When the pallet 15 is lowered by the pallet lifting means, which will be described later, the pallet 15 engages with the protruding belt 51.

[0047] On the other hand, a servo motor 52, which is a moving means for circulating the circulating belt 51, is provided on the base 9, and a drive pulley 55 is connected to the rotation shaft 52a of the servo motor 52. The drive pulley 55 is provided on the same plane as the four driven pulleys 54, and a pair of diverting pulleys 56 are pivotally supported near the drive pulley 55 to diverge the circulating belt 51 so that the circulating belt 51 is wound around the drive pulley 55.

[0048] When the servo motor 52 is driven by a command from a controller (not shown), the drive pulley 55 rotates, and the circulating belt 51, which is looped around the drive pulley 55 and installed along the lower guide rail 31, is configured to circulate while surrounding the four driven pulleys 54.

[0049] The circulation belt 51 is a so-called toothed belt 51. As shown in the enlarged view of Fig. 1, this circulation belt 51 is a belt 51 in which unevennesses 51a and 51b extending in the width direction are alternately continued in the longitudinal direction, and in a state where the circulation belt 51 is mounted on the lower guide rail 31, a locking member 14 overlapping the belt 51 is provided on the pallet 15.

[0050] Then, uneven portions 14a, 14b that can engage with the unevenness 51a, 51b of the belt 51 are formed on the locking member 14 provided on the mounting plate 16 of the pallet 15, and the uneven portions 14a, 14b of this locking member 14 are configured to engage with the unevenness 51a, 51b of the circulating belt 51.

[0051] That is, when the pallet 15 is mounted on the lower guide rail 31, the locking member 14 is configured to overlap with the circulating belt 51, and when the locking member 14 overlaps with the circulating belt 51, the uneven portions 14a and 14b formed on the locking member 14 engage with the uneven portions 51a and 51b formed on the circulating belt 51, so that the pallet 15 mounted on the lower guide rail 31 is prohibited from moving in the X-axis direction independently of the circulating belt 51.

[0052] As a result, when the servo motor 52, which is the moving means, is driven to circulate the circulating belt 51 to which the pallet 15 is engaged, the pallet 15 mounted on the lower guide rail 31 moves together with the circulating belt 51, and the pallet 15 is transported along the lower guide rail 31 along which the circulating belt 51 follows.

[0053] Here, reference numeral 57 in FIG. 1 denotes a support member 57 that prevents the circulating belt 51 between the driven pulleys 54 from loosening and prevents the circulating belt 51 from separating from the engaging member 14, and reference numeral 58 denotes a mounting fixture 58 that attaches the support member 57 to the base 12.

[0054] In addition, this circulating pallet conveying device 10 is provided with pallet lifting means 60 on both sides of the upper and lower guide rails 21, 31, which lift and lower the pallet 15 and move the pallet 15 from the upper or lower guide rail 21 or 31 to the lower or upper guide rail 21 or 31, respectively, so as to connect the end edges of the upper and lower guide rails 21, 31.

[0055] That is, the pallet lifting means 60 moves the pallet 15 mounted on the upper guide rail 21 downward to the lower guide rail 31, or conversely, moves the pallet 15 mounted on the lower guide rail 31 upward to the upper guide rail 21, and the pallet lifting means 60 provided on both sides of the upper and lower guide rails 21, 31 have the same structure.

[0056] As shown in Figures 4, 6 and 8, the pallet lifting means 60 in this embodiment comprises a short rail 61 configured to be able to mount a pallet 15, a short base 62 on which the short rail 61 is mounted, and a Z-axis direction telescopic actuator 63 that moves the short rail 61 together with the short base 62 upward or downward between an elevated position continuous with the upper guide rail 21 and a lowered position continuous with the lower guide rail 31.

[0057] The short rail 61 is the same as the upper and lower guide rails 21, 31, and the short base 62 on which the short rail 61 is mounted has the same cross-sectional shape as the upper and lower bases 22, 32 on which the upper and lower guide rails 21, 31 are mounted. The length W (FIG. 2) of the short rail 61 and the short base 62 to which it is attached in the X-axis direction is the same as or longer than the length L (FIG. 2) of the pallet 15 in the X-axis direction.

[0058] The Z-axis telescopic actuator 63 that moves such a short rail 61 moves the short base 62 to which the short rail 61 is attached in the Z-axis direction relative to the base 9, and this Z-axis telescopic actuator 63 is made up of a long and narrow box-shaped housing 63d, a ball screw 63b that is provided inside the housing and extends in the longitudinal direction and is driven to rotate by a servo motor 63a, and a follower 63c that is threadedly engaged with this ball screw 63b and moves in parallel, etc.

[0059] The Z-axis direction telescopic actuator 63 is configured so that when the servo motor 63a is driven to rotate the ball screw 63b, the follower 63c that is threadedly engaged with the ball screw 63b can move along the longitudinal direction of the housing 63d.

[0060] In this embodiment, a short base 62 provided with a short rail 61 is attached to a follower 63c of a Z-axis extension actuator 63 so as to be movable in the Z-axis direction, and a servo motor 63a in this Z-axis extension actuator 63 is connected to the control output of a controller (not shown) that controls it, and the Z-axis extension actuator 63 is configured to be able to raise and lower the short rail 61 in the Z-axis direction in response to a command from the controller.

[0061] 5 and 7, when the short rails 61 of the pallet lifting means 60 are continuous with the upper and lower guide rails 21, 31, the pallet 15 moving on the upper guide rail 21 or the lower guide rail 31 can move from these guide rails 21, 31 to the short rail 61. Alternatively, in such a continuous state, the pallet 15 mounted on the short rail 61 can be moved to either the upper or lower guide rail 21, 31.

[0062] 4, 6 and 8, a stator 71 is attached to the short base 62 in parallel with the short rail 61. This stator 71 has the same structure as the stator 41 mounted on the upper guide rail 21, and a plurality of unit electromagnets 71b are arranged in succession on a holder 71a.

[0063] That is, this stator 71 constitutes a linear motor 70 together with a mover 42 (FIGS. 6 and 8) provided on the pallet 15, and when the pallet 15 is mounted on the short rail 61 and a controller (not shown) energizes the unit electromagnet 71b, the pallet 15 to which the mover 42 is attached is maintained in a state mounted on the short rail 61, or the pallet 15 is moved in the X direction so that it can be moved to the upper guide rail 21 or the lower guide rail 31.

[0064] A position sensor 47 is also attached to the side of a partition portion 62c that stands upright from the top surface of the short base 62, and when the pallet 15 is mounted on the short rail 61, a magnetic scale 48 attached to the mounting piece 17a of the pallet 15 faces this position sensor 47 and is configured to detect the position of the pallet 15 on the short rail 61. The detection output of this position sensor 47 is also connected to the control input of a controller (not shown).

[0065] The circulating pallet conveying device 10 of the present invention, in which such pallet lifting means 60 are provided at both ends of the upper and lower guide rails 21, 31, is capable of circulating the pallet 15 by loading the pallet 15, which has moved along the upper guide rail 21 as shown in Figure 5, from its edge onto the short rail 61 of one of the pallet lifting means 60 and lowering it as shown in Figure 6, moving the pallet 15 from that short rail 61 to the lower guide rail 31, moving the lower guide rail 31 in the opposite direction to return it, and loading it from its edge onto the short rail 61 of the other pallet lifting means 60 as shown in Figure 7 and raising it as shown in Figure 8.

[0066] Next, the machining of workpieces using this circulating pallet transport device will be described.

[0067] A workpiece (not shown) to be machined is placed on a pallet 15, and the pallet 15 with the workpiece placed on it is moved while being placed on an upper guide rail 21. Here, the workpiece may be placed on the pallet 15 which is placed on the upper guide rail 21, or the pallet 15 on which the workpiece is already placed may be placed on the upper guide rail 21.

[0068] In this embodiment, the pallet 15 is provided with a mounting tool 16 for mounting a workpiece, and the workpiece is mounted on the pallet 15 via this mounting tool 16.

[0069] Furthermore, when loading the pallet 15 onto the upper guide rail 21, the linear motion block 18 of the pallet 15 is loaded from the side end of the upper guide rail 21. In this case, the pallet 15 may be loaded from the end of the upper guide rail 21 with the short rail 61 of the pallet lifting means 60 lowered, or the pallet 15 may be loaded onto the upper guide rail 21 via the short rail 61 even when the short rail 61 is raised and connected to the upper guide rail 21.

[0070] Once the pallets 15 are loaded onto the upper guide rails 21, the upper pallet feeding means 40 transports the pallets 15 along the upper guide rails 21. The pallets 15 loaded onto the upper guide rails 21 are transported until they face each of the machine tools 1 to 5 (Fig. 2), and when the pallet 15 faces each of the machine tools 1 to 5, the controller stops the movement of the pallet 15, and the workpieces loaded on the pallet 15 are machined in each of the machine tools 1 to 5.

[0071] Here, since the upper pallet feeding means is a linear motor 40, the pallet 16 can be stopped at any position, and even if multiple pallets 15 are mounted on the upper guide rail 21, the multiple pallets 15 can be moved separately and stopped at a position where the pallets 15 face each of the machine tools 1 to 5.

[0072] In this way, by using the linear motor 40 as the upper pallet feeding means, even if the spacing or processing time of each machine tool 1 to 5 arranged along this upper guide rail 21 is different, by stopping the multiple pallets 15 in a state where the spacing between them matches the spacing between each machine tool, the multiple pallets 15 can be made to face each machine tool, and it is also possible to move only the pallets 15 that have finished processing.

[0073] When all processing of the workpieces mounted on the pallet 15 by each of the machine tools 1 to 5 is completed, the pallet 15 reaches the downstream end of the upper guide rail 21, and the workpieces for which processing has been completed are removed from the pallet 15.

[0074] Then, the pallet 15 from which the workpieces have been removed is moved back to the lower guide rail 31 located below. This movement of the pallet 15 is performed by one of the pallet lifting means 60 provided at the downstream end of the upper guide rail 21.

[0075] 5, the specific procedure is to load the pallet 15, which has reached the end of the upper guide rail 21, onto the short rail 61 of the pallet lifting means 60. To load the pallet 15 onto this short rail 61, the Z-axis telescopic actuator 63 is used to raise the short rail 61 so that the short rail 61 is connected to the upper guide rail 21. In this state, the linear motor 40 is used to move the pallet 15, which is moving on the upper guide rail 21, up to the short rail 61 that is connected to the upper guide rail 21.

[0076] As shown in Figure 6, when a pallet 15 is mounted on a short rail 61 that is continuous with the upper guide rail 21, the mover 42 attached to the pallet 15 is inserted into a stator 71 that is arranged parallel to the short rail 61, and when electricity is applied to the stator 71 from a controller (not shown), the movement of the pallet 15 is stopped by the interaction of the magnetic flux of the permanent magnet of the mover 42 attached to the pallet 15, and the pallet 15 is maintained in its mounted state on the short rail 61.

[0077] Thereafter, the short rail 61 is lowered together with the pallet 15 mounted thereon as shown by the dashed arrow, and the short rail 61 with the pallet 15 mounted thereon is moved from a position connected to the upper guide rail 21 located above to a lower position connected to the lower guide rail 31. This movement is performed by the Z-axis direction telescopic actuator 63.

[0078] In this circulating pallet conveying device 10, the belts 51 constituting the pallet lifting means 60 arranged along the lower guide rail 31 are arranged to protrude from both sides of the lower guide rail 31, so that when the short rail 61 connects to the lower guide rail 31, the belts 51 engage with the pallet 15.

[0079] That is, when the short rail 61 is lowered and connected to the lower guide rail 31, the locking member 14 provided on the pallet 15 overlaps with the belt 51, and the uneven surfaces 14a, 14b provided on the pallet 15 engage with the uneven surfaces 51a, 51b of the circulating belt 51 provided along the lower guide rail 31 (enlarged view of Figure 1).

[0080] Therefore, after the uneven surfaces 14a, 14b of the pallet 15 engage with the uneven surfaces 51a, 51b of the circulating belt 51, the power supply to the stator 71 arranged along the short rail 61 is stopped to release the restraint on the pallet 15, and the servo motor 52, which serves as the drive mechanism, is driven to circulate the circulating belt 51, thereby moving the pallet 15 mounted on the short rail 61 from the short rail 61 to the guide rail 31 below, and by further circulating the circulating belt 51, the pallet 15 is transported in the reverse direction along the guide rail 31 below.

[0081] When the pallet 15 returns to the starting end side of the lower guide rail 31, the pallet 15 is raised by the other pallet lifting means 60 provided on the starting end side and returned to the starting end side of the upper guide rail 21.

[0082] That is, as shown in Figure 7, the Z-axis telescopic actuator 63 of the other pallet lifting means 60 lowers the short rail 61 so that the short rail 61 is continuous with the lower guide rail 31. In this circulating pallet transport device 10, the belts 51 that make up the pallet lifting means 60 provided along the lower guide rail 31 are provided to protrude from both sides of the lower guide rail 31, so when the circulating belt 51 is circulated with the short rail 61 continuing with the lower guide rail 31, as shown by the solid arrow in Figure 7, the pallet 15 moving towards the starting end of the lower guide rail 31 will move from the lower guide rail 21 to the short rail 61 that is continuous with it and be loaded onto it.

[0083] When a pallet 15 is mounted on a short rail 61 that is continuous with the lower guide rail 31, as shown in Figure 8, the mover 42 attached to the pallet 15 is inserted into a stator 71 that is arranged parallel to the short rail 61, and when electricity is applied to the stator 71 from a controller (not shown), the movement of the pallet 15 is stopped by the interaction of the magnetic flux of the permanent magnet of the mover 42 attached to the pallet 15, and the pallet 15 is maintained in a state where it is mounted on the short rail 61.

[0084] In this way, the pallet 15 is mounted on the short rail 61 connected to the lower guide rail 31 and its movement is stopped, and in this state, the Z-axis telescopic actuator 63 of the other pallet lifting means 60 raises the short rail 61 together with the pallet 15 as shown by the dashed arrow, so that the short rail 61 is connected to the upper guide rail 21.

[0085] In this circulating pallet conveying device 10, the belts 51 that constitute the pallet lifting means 60 arranged along the lower guide rail 31 are arranged to protrude from both sides of the lower guide rail 31, so that when the short rail 61 is raised together with the pallet 15, the locking member 14 arranged on the pallet 15 moves away from the belts 51, and the engagement between the pallet 15 and the belts 51 is released.

[0086] Then, after connecting the short rail 61 to the upper guide rail 21, the stator 71 provided along the short rail 61 and the stator 41 provided along the upper guide rail 21 are energized to move the pallet 15 mounted on the short rail 61 from the short rail 61 to the upper guide rail 21. In this way, the pallet 15 is circulated.

[0087] Here, the pallet 15 is loaded again on the starting end of the upper guide rail 21, and a workpiece (not shown) is loaded on it, and the pallet 15 moves again downstream to be machined.

[0088] In this way, in the circulating pallet conveying device 10 of the present invention, a linear motor 40 is used as the upper pallet feeding means for moving the pallet 15 mounted on the upper guide rail 21, so even if multiple pallets 15 are mounted on the upper guide rail 21, the spacing between the multiple pallets 15 can be easily changed while they are mounted on the upper guide rail 21.

[0089] On the other hand, because the moving body 51 is used as the lower pallet feeding means 50 that returns the pallets 15 mounted on the lower guide rails 31 to their starting ends, it can be made less expensive than the linear motor 40. Therefore, it is possible to provide a relatively inexpensive circulating pallet conveying device 10, even though the spacing between the pallets 15 that are mounted on the upper guide rails 21 and move can be easily changed.

[0090] In particular, in this embodiment, a stator 71 that constitutes a linear motor 70 together with the movable element 42 on the pallet 15 is provided as a pallet movement stopping means for moving or preventing the movement of the pallet 15 mounted on the short rail 61. This makes it possible to easily change and adjust the position of the pallet 15 mounted on this short rail 61, and also makes it possible to mount a workpiece on the pallet 15 mounted on this short rail 61 and process it.

[0091] In the above embodiment, the pallet movement stopping means for moving or prohibiting the movement of the pallet 15 mounted on the short rail 61 is provided with the stator 71 that constitutes the linear motor 70 together with the mover 42 of the pallet 15. However, the pallet movement stopping means is not limited to a linear motor as long as it can move or prohibit the movement of the pallet 15 mounted on the short rail 61. For example, it may be something that mechanically moves or prohibits the movement of the pallet 15 mounted on the short rail 61.

[0092] In the above-described embodiment, the moving body is an endless belt 51 that is circulatable along the lower guide rail 31. However, this moving body is not limited to a belt 51 as long as it is capable of moving the engaged pallet 15. For example, it may be a moving body that is threaded onto a ball screw, and the pallet 15 is engaged with the moving body by the rotation of the ball screw to move it, or the rotation may be stopped to prevent the pallet from moving. [Explanation of symbols]

[0093] 10. Circulating pallet transport device 14a,14b Uneven surface 15 palettes 21 Upper guide rail 31 Lower guide rail 40 Linear motor (upper pallet feeding means) 41 Stator 42 Mover 50 Lower pallet feeding means 51 Belt (moving object) 51a,51b unevenness 60 Pallet lifting means 61 Short Rail 63 Lifting means 71 Stator

Claims

1. an upper guide rail (21) and a lower guide rail (31) that are provided parallel to each other and spaced apart in the vertical direction; At least one pallet (15) movably mounted on each of the upper guide rail (21) and the lower guide rail (31); an upper pallet feeding means (40) for conveying the pallet (15) along the upper guide rail (21); a lower pallet feeding means (50) for conveying the pallet (15) along the lower guide rail (31); a pallet lifting means (60) provided at both ends of the upper guide rail (21) and the lower guide rail (31) for lifting and lowering the pallet (15) to move the pallet (15) from the upper guide rail (21) or the lower guide rail (31) to the lower guide rail (31) or the upper guide rail (21), the upper pallet feeding means (40) is a linear motor (40) having a stator (41) continuously provided along the upper guide rail (21) and a mover (42) provided on the pallet (15) so as to face the stator (41), The lower pallet feeding means (50) includes an endless belt (51) circulatably wound around a plurality of pulleys (54) whose rotation centers are horizontal, The pulleys (54) are pivotally supported on support posts (53) provided at a distance from both ends of the lower guide rail (31) so that the upper belt (51) between the pulleys (54) is aligned along the lower guide rail (31), The pallet lifting means (60) is disposed between the end of the lower guide rail (31) and the support (53) on which the pulley (54) is pivotally supported, The outer periphery of the belt (51) has widthwise extending unevenness (51a, 51b) alternately and continuously formed in the longitudinal direction, The pallet (15) is formed with recesses (14a, 14b) that can be engaged with the recesses (51a, 51b), When the pallet (15) is lowered by the pallet lifting means (60), the uneven surfaces (14a, 14b) engage with the uneven surfaces (51a, 51b), and when the pallet (15) is raised by the pallet lifting means (60), the engagement between the pallet (15) and the belt (51) can be released. A circulating pallet transport device characterized by:

2. The lower pallet feeding means (50) comprises the belt (51) and a moving means (52) provided on a base (12) supporting the lower guide rail (31) to move the belt (51) so that it circulates, The support columns (53) are respectively provided on a base (9) spaced apart from both ends of the base (12) that supports the lower guide rail (31), Two support columns (53) are provided on a base (9) spaced apart from both ends of the pedestal (12), and each column (53) is provided with a pair of pulleys (54) spaced apart in the vertical direction. The belt (51) is wound around these four pulleys (54).

2. The circulating pallet transport device according to claim 1.

3. A circulating pallet conveying device as described in Claim 2, wherein the two pillars (53) are erected at a distance from the edge of the lower guide rail (31) with a gap that allows the pallet lifting means (60) to be interposed therebetween, and the four pulleys (54) are provided at a distance from the edge of the lower guide rail (31).

4. The pallet lifting means (60) a short rail (61) on which the pallet (15) is movably mounted; a lifting means (63) for lifting the short rail (61) between a raised position in which the short rail (61) communicates with the upper guide rail (21) and a lowered position in which the short rail (61) communicates with the lower guide rail (31); a stator (71) provided along the short rail (61) and constituting a linear motor together with a mover (42) provided on the pallet (15) to move or stop the pallet (15) mounted on the short rail (61); 4. The circulating pallet transport device according to claim 1, further comprising:

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