Pallet lifting device, pallet transport device, and pallet transport method

Abstract

To provide a device for resolving misalignment of lifted pallets and changing the order and spacing of pallets to be conveyed.SOLUTION: Pallet lifting device lifts a pallet 11 being conveyed on a belt 20 in the middle of conveyance, and is equipped with lifting actuators 51 provided on both sides of the belt 20, a loading member 52 provided to be raised and lowered by the lifting actuators and configured to load the pallet 11 being conveyed in the lowered position and a fixing means 61 that sandwiches the pallet 11 together with the loading member 52 when the loading member 52 is in the raised position. In the pallet conveying device 10 equipped with this pallet lifting device 50, the belt 20 is circulatively mounted on a pair of plates 16, 16, lifting actuators 51 are provided as sandwiching the pair of plates 16, 16 and the pallet lifting device 50 is mounted in such a way that both sides of the pallet 11 conveyed on the belt 20 in the lowered state can be loaded onto the loading member 52.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pallet lifting device that lifts a pallet on which a workpiece is mounted during transportation, and a pallet transport device equipped with the same. [Background technology]

[0002] Conventionally, in a manufacturing line, a pallet transport device consisting of a free-flow conveyor is provided to connect a number of machine tools, and a pallet carrying a workpiece is loaded onto the free-flow conveyor and transported to a machine tool at the destination, where the workpiece is subjected to a specified processing.

[0003] With this type of pallet transport device, if there is a pallet carrying workpieces that is currently being processed or that is not being processed in front of a pallet carrying a processed workpiece, the pallet carrying the processed workpieces cannot be transported until the processing of these workpieces is completed, and the pallet becomes stuck in place. This is a frequent occurrence.

[0004] In order to solve this problem, a lifting device has been proposed that lifts up a pallet that is mounted on a conveyor and is being transported, and allows another pallet to pass underneath it (see, for example, Patent Document 1).

[0005] This lifting device grasps both sides of a pallet as it is being transported and lifts it up in that state, and it is expected that by allowing another pallet to pass underneath it, it will be possible to alleviate pallet congestion. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5498943 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the conventional pallet lifting device described above, the lifting head corrects and grips the pallet as soon as it begins to rise, meaning that the time required to reliably correct the misalignment is too short. In particular, when a workpiece is loaded, the impact on the workpiece is stronger than if the time required to correct the misalignment was longer, and there is a risk that the workpiece will shift from its designated position on the pallet or fall.

[0008] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a pallet lifting device which is capable of eliminating misalignment of the pallet during lifting.

[0009] Another object of the present invention is to provide a pallet conveying device which is capable of changing the order and intervals of pallets which are mounted on a belt and conveyed. [Means for solving the problem]

[0010] The present invention is a pallet lifting device that lifts a pallet that is carried on a moving belt during transport.

[0011] Its distinctive configuration comprises lifting actuators arranged on both sides of the belt to sandwich the belt, a mounting member arranged so as to be raised and lowered by the lifting actuators and configured to be capable of mounting a pallet which is mounted on the belt and transported at a lowered position, and a fixing means for fixing the pallet to the mounting member by sandwiching the pallet together with the mounting member when the mounting member carrying the pallet is raised by the lifting actuator.

[0012] In this case, the fixing means preferably comprises a lifting rod mounted on the mounting member so as to be able to move up and down, a pressure plate attached to the upper end of the lifting rod and disposed above the mounting member with a predetermined distance therebetween, a biasing means for biasing the pressure plate to widen the gap between the pressure plate and the mounting member, a slide plate attached to the lower end of the lifting rod, and a limiting member for abutting against the slide plate to prohibit the lifting rod from rising when the mounting member is raised by the lifting actuator.

[0013] It is preferable to form a step on the pressure plate which contacts the side of the pallet to limit the widthwise movement of the pallet, and if a tapered pin is formed at a diagonal position on either the mounting member or the pressure plate, it is further preferable to form a hole in the pallet through which the pin can be inserted.

[0014] On the other hand, another aspect of the present invention is a pallet transporting device equipped with the above-mentioned pallet lifting device, characterized in that a belt is circulably attached to a pair of plates arranged at a predetermined interval in the width direction of the transport direction, a flange-like member is formed on the pallet which exceeds the upper edges of the pair of plates when mounted on the belt, and the pallet lifting device is attached so that the flange-like members on both sides of the pallet transported on the belt can be mounted on a mounting member in a lowered state.

[0015] In this case, it is preferable that a guide member for limiting the widthwise movement of the pallet mounted on the belt and transported is attached to the upper edge of the plate, a notch capable of accommodating the mounting member in a lowered state is formed in the guide member, and a spare guide member for covering the notch when the mounting member is in a raised state is provided on the pallet lifting device, and when unevenness extending in the width direction is formed on the belt in a continuous alternating manner in the longitudinal direction, uneven projections and recesses are formed on the pallet capable of engaging with the unevenness when mounted on the belt, and a pressing member is provided on the guide member for preventing the pallet mounted on the belt and transported at high speed from floating off the belt or tilting relative to the belt. Effect of the Invention

[0016] In the pallet lifting device of the present invention, the fixing means fixes the pallet to the mounting member when the mounting member carrying the pallet is in an elevated state. Therefore, even if some misalignment occurs when the pallet is mounted on the mounting member in a lowered state, the misalignment can be eliminated as the mounting member is elevated, making it possible to eliminate the misalignment of the pallet at the stage of lifting.

[0017] Furthermore, in a pallet conveying device equipped with such a pallet lifting device, after the other pallets except for the lifted pallet have been conveyed a predetermined distance, the lifted pallet is lowered and placed back on the circulating belt, thereby increasing the gap between the preceding pallet and decreasing the gap between the following pallet.

[0018] Then, when the pallet lifting device has lifted a pallet, another following pallet can be passed under the lifted pallet, thereby changing the transport order of the pallets. [Brief description of the drawings]

[0019] [Figure 1] 1 is a partially cutaway front view of a pallet transport device equipped with a pallet lifting device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a top view of a pallet transport device equipped with the pallet lifting device. [Diagram 3] 2 is a cross-sectional view taken along line AA in FIG. 1. [Figure 4] FIG. 2 is a cross-sectional view taken along line BB in FIG. [Diagram 5] FIG. 2 is an enlarged front view of a portion C in FIG. 1 showing the pallet lifting device. [Figure 6] 5 is a view corresponding to FIG. 4 and showing the state in which the pallet lifting device has lifted the pallet. [Figure 7] 6 is a view corresponding to FIG. 5 and illustrating the state in which the pallet lifting device has lifted the pallet. [Figure 8] 7 is a view corresponding to FIG. 6, showing a state in which the fixing means of the pallet lifting device has fixed the lifted pallet. FIG. [Figure 9] 8 is a view corresponding to FIG. 7, showing a state in which the fixing means of the pallet lifting device has fixed the lifted pallet. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Next, the best mode for carrying out the present invention will be described with reference to the drawings.

[0021] The pallet lifting device 50 of the present invention lifts the pallet 11, which is carried on the moving belt 20, during the transportation.

[0022] For this reason, in this embodiment, a pallet lifting device 50 is provided on a pallet conveying device 10 that moves a belt 20 and loads a pallet 11 onto the belt 20 for transport, and a pallet conveying device 10 equipped with this pallet lifting device 50 is shown in Figures 1 and 2.

[0023] In each figure, three mutually perpendicular 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. This pallet conveying device 10 will be described.

[0024] As shown in Figures 1 and 2, the pallet conveying device 10 in this embodiment comprises a circulating belt 20 that extends along a conveying path and is circulatable, and carries a pallet 11, and a driving means 30 that moves the circulating belt 20 in a circulating manner to convey the pallet 11 carried on the circulating belt 20.

[0025] This pallet conveying device 10 is used in such cases that a pallet 11 carrying workpieces (not shown) is loaded onto a circulating belt 20 which moves in a circular motion and conveyed, and the conveyance of the pallet 11 is stopped by stopping the circulation of the circulating belt 20 in front of machine tools 1-4 (Figure 2) arranged along the conveying path, so that the workpieces (not shown) mounted on the pallet 11 are machined by those machine tools 1-4.

[0026] In addition, Figure 2 shows a case where four machine tools 1 to 4 are provided on one side of the pallet conveying device 10, but this is just one example, and the number of machine tools 1 to 4 varies depending on the workpiece that needs to be machined, and the number of pallets 11 is increased or decreased as appropriate depending on the number of machine tools 1 to 4.

[0027] In this embodiment, the pallet conveying device 10 has a stand 9 that extends to connect a number of machine tools 1 to 4, and a pair of plates 16 are fixed parallel to each other and spaced a predetermined distance apart in the width direction (Y axis direction) on the stand 9 along the conveying path (X axis direction) of the pallet 11.

[0028] In the figure, a pair of plates 16 are fixed parallel to each other while floating above the stand 9 via a plurality of support legs 19 (FIG. 1) that are erected on the stand 9 at a predetermined interval in the conveying path (X-axis direction). The circulating belts 20 in the pallet conveying device 10 are provided on the opposing sides of the pair of plates 16 so as to support both sides of the pallet 11 in the width direction, and the pallet 11 is configured to be mountable on the pair of circulating belts 20.

[0029] The circulating belts 20 provided on the opposing portions of a pair of parallel plates 16, 16 are provided in a symmetrical structure. To explain the circulating belt 20 provided on one plate 16 as a representative example, as shown in FIG. 1, driven pulleys 22 around which the circulating belt 20 is wound are provided at the ends of the opposing sides of the plates 16.

[0030] The circulating belt 20 surrounds these driven pulleys 22 and is looped around the opposing sides of the plate 16 so that its upper edge is horizontally continuous.

[0031] In addition, an upper support member 17a is attached to the opposing portions of the pair of plates 16, 16, supporting the continuous upper edge of the circulating belt 20 surrounding the driven pulley 22 and preventing it from slackening, and a lower support member 17b is attached to the opposing portions of the pair of plates 16, 16, supporting the continuous lower edge of the circulating belt 20 surrounding the driven pulley 22 and preventing it from slackening.

[0032] The upper support member 17a and the lower support member 17b in the figure are each screwed to the plate 16, and these upper support member 17a and lower support member 17b are shown to house the circulating belt 20 and to have grooves 17c, 17d (FIG. 3) formed therein to prevent the belt from moving in the width direction.

[0033] The driving means 30 for circulating the circulating belt 20 includes a driving pulley 23 around which the circulating belt 20 is wound, and a motor 31 for rotating the driving pulley 23 .

[0034] Specifically, as shown in FIG. 3, support plates 32 are attached to the ends of the pair of plates 16, respectively, and drive shafts 23a are supported by these support plates 32. Drive pulleys 23 of the same shape and size are attached to the opposing sides of the pair of plates 16 of the drive shafts 23a.

[0035] The drive pulley 23 is provided on the opposite side of the plate 16 on the same plane as the driven pulley 22 around which the circulating belt 20 is wound, and is configured to wind the circulating belt 20 turned by the driven pulley 22 around the drive pulley 23. A turning pulley 24 is pivotally supported on the support plate 32 to guide the circulating belt 20 turned around the drive pulley 23 to the lower support member 17b.

[0036] The motor 31 that rotates the drive pulley 23 is attached to one of the support plates 32, and is configured to be driven by a command from a controller (not shown) to rotate the drive shaft 23a. That is, when the motor 31 is driven, it rotates the drive shaft 23a, and simultaneously rotates the drive pulleys 23 on the opposing sides of the pair of plates 16 in the same direction, and circulates the circulating belts 20 that are wrapped around the drive pulleys 23 and exist on the opposing sides of the plates 16 in the same direction while surrounding the driven pulleys 22.

[0037] On the other hand, the circulating belt 20 in this embodiment is a so-called toothed belt 20 in which unevenness 20a, 20b extending in the width direction is formed alternately and continuously in the longitudinal direction on the outer surface, which is the mounting surface of the pallet 11, as shown in the enlarged view of Figure 1.

[0038] As shown in Figure 3, the pallet 11 mounted on such a pair of circulating belts 20 comprises a base 12 which is rectangular in top view and has both sides supported by the circulating belts 20, a flange-shaped member 15 which is horizontally arranged on both sides of the width of the lower part of the base 12 so as to protrude from the side edges, a mounting fixture 13 which is arranged on the upper surface of the base 12 and which mounts a workpiece (not shown) to be machined by the machine tools 1 to 4, and a contact material 14 which is arranged on the underside of the base 12 and which comes into direct contact with the circulating belt 20.

[0039] Here, the shape of the mounting fixture 13 varies depending on the type of workpiece to be transported, and multiple pallets 11 equipped with this mounting fixture 13 are prepared in order to transport multiple workpieces continuously.

[0040] 1, the contact member 14 provided on the base 12 of the pallet 11 has the uneven portions 14a, 14b formed thereon, which are capable of engaging with the uneven portions 20a, 20b of the circulating belt. That is, the uneven portions 14a, 14b of the contact member 14 are configured to have the same shape and size in cross section so as to engage with the uneven portions 20a, 20b of the circulating belt 20.

[0041] When the pallet 11 is loaded onto the circulating belt 20 and the contact material 14 is overlapped with the circulating belt 20, the uneven surfaces 14a, 14b formed on the contact material 14 engage with the uneven surfaces 20a, 20b formed on the circulating belt 20, and movement of the pallet 11 in the X-axis direction independent of the circulating belt 20 is prohibited.

[0042] 3, with the circulating belt 20 supporting both sides of the pallet 11 in the width direction via the contact members 14, both sides of the base 12 reach the upper edges of the upper support members 17a, and the flange-like members 15 provided on both sides of the base 12 are configured to pass through the upper edges of the plates 16 and protrude to the outside of the pair of plates 16. A guide member 36 is attached to the upper edge of the plate 16, which holds the pallet 11 including the flange-like members 15 in the width direction with a specified gap between them.

[0043] This guide member 36 is attached to the upper edges of the pair of plates 16 so as to bulge outward beyond the flange-shaped members 15 which protrude outward in the width direction of the plates 16, and this guide member 36 is formed with a step portion 36a which faces the outer edge of the flange-shaped member 15 in the width direction. This step portion 36a faces the outer edge of the flange-shaped member 15, and is configured to prevent the pallet 11 including the flange-shaped member 15 from shifting in the width direction without impeding its movement in the conveying direction.

[0044] In addition, the guide member 36 is provided with a pressing member 18 which holds the flange-like member 15 of the pallet 11 together with the guide member 36 from above and below with a specified gap between them. The pressing member 18 in the figures is a flat plate attached to the upper surface of the guide member 36, and this pressing plate 18 is formed in a size such that its edge faces the side edge of the base 12 and prevents the base 12 from moving in the width direction.

[0045] The presence of this pressing member 18 prevents the pallet 11 mounted on the circulating belt 20 from floating off the circulating belt 20 or tilting relative to the belt, thereby maintaining an engagement state between the uneven surfaces 14a, 14b formed on the contact material 14 on the pallet 11 and the uneven surfaces 20a, 20b formed on the circulating belt 20, and is configured to transport the pallet 11 while prohibiting movement of the pallet 11 independent of the circulating belt 20.

[0046] That is, when the motor 31, which is the driving means 30, is driven to circulate the circulating belt 20 on which the pallet 11 is mounted, the pallet 11 moves while mounted on the circulating belt 20 and is transported a distance equal to the movement of the circulating belt 20.

[0047] Returning to FIG. 1, the pallet conveying device 10 is provided with a pallet lifting device 50 that lifts the pallet 11, which is carried on the circulating belt 20 that moves in a circular manner, during the conveyance.

[0048] This pallet lifting device 50 comprises a pair of lifting actuators 51 provided on both sides of the circulating belt 20, i.e., on both sides thereof so as to sandwich a pair of plates 16 on which the circulating belt 20 is circulatable, and a mounting member 52 which is configured to be raised and lowered by the lifting actuators 51 and to be capable of mounting a pallet 11 to be transported by the circulating belt 20 at a lowered position.

[0049] Specifically, as shown in Figures 4 and 5, a base plate 53 that constitutes the pallet lifting device 50 is installed on a stand 9 on the outside of a pair of plates 16 arranged along the conveying path (X-axis direction) of the pallet conveying device 10, and a pair of pillars 54, 54 spaced apart in the conveying direction are erected on this base plate 53, and a mounting plate 56 is erected on the upper ends of the pair of pillars 54, 54.

[0050] The lifting actuator in this embodiment is a fluid pressure cylinder 51 with its retractable rod 51b facing upward, as shown in FIG. 5. This fluid pressure cylinder 51 has its retractable rod 51b penetrating its mounting plate 56 from below, and its main body 51a is attached to the underside of the mounting plate 56 facing vertically.

[0051] As shown in Figure 5, a guide member 36 is provided on the upper edge of a pair of plates 16 arranged along the conveying path (X-axis direction) of the pallet conveying device 10, and a notch 36b is formed at a position where a pallet lifting device 50 is provided to lift the pallet 11, and a mounting member 52 is attached to the upper part of the retractable rod 51b so as to cover this notch 36b.

[0052] As shown in FIG. 4, the mounting member 52 has an attachment portion 52a to which the retractable rod 51b (FIG. 5) is attached, and a placement portion 52b formed to protrude upward from the edge of the mounting portion 52a on the plate 16 side, on which the pallet 11 is actually mounted.

[0053] As shown in FIG. 1, the length W of the cutout 36b in the guide member 36 is longer than the length L1 of the pallet 11 in the conveying direction, and as shown in FIG. 5, the length L2 of the mounting member 52 is equivalent to the length L1 (FIG. 1) of the pallet 11 in the conveying direction and is formed to a length that can close the cutout 36b of the guide member 36.

[0054] 5, the mounting member 52 descends with the retractable rods 51b retracted into the main body 51a, and as shown in Fig. 4, when the pallet 11 moves and is transported while being mounted on the circulation belt 20, the flange-like members 15 protruding laterally from the plate 16 move and pass above the placement portion 52b of the mounting member 52. In other words, when the mounting member 52 is in the descending state, the mounting member 52 is configured to allow the movement of the pallet 11 mounted on the circulation belt 20.

[0055] On the other hand, when the pallet 11 faces the pallet lifting device 50, i.e., when the brim member 15 of the pallet 11 is positioned on the mounting portion 52b of the mounting member 52, and the retractable rod 51b protrudes upward from the main body portion 51a as shown in Figure 7, the fluid pressure cylinder 51 raises the mounting member 52 as shown in Figure 6, and the pallet 11 mounted on the mounting portion 52b of the mounting member 52 is configured to rise via the cutout 36b (Figure 7).

[0056] In addition, the pallet lifting device 50 is provided with a fixing means 61 for fixing the pallet 11 in a predetermined position on the mounting member 52 when the mounting member 52 carrying the pallet 11 is raised by the lifting actuator 51.

[0057] As shown in Figures 4 and 5, the fixing means 61 in this embodiment comprises a lifting rod 64 that is mounted on the mounting member 52 so as to be able to move up and down, a pressure plate 62 attached to the upper end of the lifting rod 64 and disposed above the mounting member 52 with a predetermined distance therebetween, a biasing means 63 (Figure 5) that biases the pressure plate 62 to widen the distance between the mounting member 52 and the pressure plate 62, a slide plate 66 attached to the lower end of the lifting rod 64, and a limiting member 67a that prohibits the lifting rod 64 from rising so that the pressure plate 62 clamps the pallet 11 together with the mounting member 52 when the mounting member 52 carrying the pallet 11 is raised by the flow-resistant cylinder 51.

[0058] 5, a pair of linear bushings 67 are attached to the mounting plate 56 so as to sandwich the main body 51a of the flow pressure resistant cylinder 51 from both sides in the conveying direction, and a linear bushing 69 is also attached coaxially to the mounting part 52a of the mounting member 52. In addition, a collar 67a that surrounds the linear bushing 67 on the lower side of the mounting plate 56 and serves as a limiting member, and that is longer than the linear bushing 67, is further attached to the lower side of the mounting plate 56.

[0059] Lifting rods 64 are inserted so as to be axially movable through both the linear bushings 67 provided on the attachment plate 56 and the linear bushings 69 provided on the mounting member 52. A pressing plate 62 is mounted on the upper ends of the pair of lifting rods 64 that penetrate both the attachment plate 56 and the mounting member 52.

[0060] The biasing means is a coil spring 63 interposed between the mounting member 52 and the pressing plate 62, and a floating joint 57 is provided at the tip of the rod 51b of the fluid pressure cylinder 51, and this floating joint 57 is attached to the mounting member 52. In other words, the mounting member 52 is attached to the tip of the rod 51b via this floating joint 57.

[0061] In the floating joint 57, a stripper bolt 58 penetrating the mounting member 52 is provided so as to extend the rod 51b coaxially with the rod 51b, and a stopper 59 through which the stripper bolt 58 passes is attached to a pressing plate 62. The stopper 59 is configured to come into contact with the stripper bolt 58, thereby preventing the gap between the mounting member 52 and the pressing plate 62 from opening beyond a predetermined value due to the biasing force of a coil spring 63 (FIG. 5).

[0062] A slide plate 66 is attached to the lower part of the pair of lifting rods 64, 64, and as shown in Figure 7, when the pair of lifting rods 64, 64 rise and the slide plate 66 abuts against a collar 67a which acts as a limiting member, further rising of the pair of lifting rods 64, 64 is prohibited.

[0063] Therefore, in the fixing means 61 having such a configuration, when the pallet 11 faces the pallet lifting device 50 and is mounted on the mounting member 52 and raised as shown in Figures 6 and 7, when the slide plate 66 abuts against the collar 67a, which acts as a limiting member, further lifting of the pressing plate 62 provided on the pair of lifting rods 64, 64 is prohibited.

[0064] However, since further rise of the mounting member 52 is allowed from this state, when the fluid pressure cylinder 51 causes its protruding rod 51b to protrude further upward from the main body portion 51a, the gap between the pressing plate 62 and the mounting member 52 narrows against the biasing force of the biasing means 63, as shown in Figures 8 and 9, and ultimately, the placement portion 52b of the mounting member 52 is configured to clamp the flange-shaped member 15 of the pallet 11 together with the pressing plate 62, thereby fixing the pallet 11 to the mounting member 52.

[0065] 4, the mounting member 52 is provided with a pin 52c tapered toward the tip thereof so as to protrude toward the flange-shaped member 15. Meanwhile, the flange-shaped member 15 to which the pin 52c faces is formed with a hole 15a facing the pin 52c, into which the pin 52c can enter.

[0066] In this embodiment, as shown in FIG. 1, the pins 52c are formed at diagonal positions of the mounting member 52, and the inner diameter of the holes 15a is slightly larger than the outer diameter of the pins 52c.

[0067] As a result, the gap between the pressing plate 62 and the mounting member 52 narrows against the biasing force of the biasing means 63, and when the placement portion 52b of the mounting member 52 clamps the flange-shaped member 15 of the pallet 11 together with the pressing plate 62 as shown in Figure 8, the pin 52c is inserted into the hole 15a in the flange-shaped member 15 of the pallet 11 as shown in the enlarged view of Figure 8, and in this state, the pallet 11 is configured to be mounted in the correct position on the mounting member 52.

[0068] Furthermore, the slide plate 66 is provided with an auxiliary guide member 71 that covers the cutout 36b in the guide member 36 when the mounting member 52 is in the elevated state. This auxiliary guide member 71 is such as to surround the flange-shaped member 15 of the pallet 11 from the side, and has the same cross section as the guide member 36 and the pressing member 18 attached to the upper part of the plate 16.

[0069] That is, in this embodiment, the spare guide member 71 has a side wall portion 71a that faces the side edge of the flange-shaped member 15 of the pallet 11 that has entered the cutout 36b while blocking the cutout 36b, and an upper plate portion 71b that faces the upper surface of the flange-shaped member 15.

[0070] This spare guide member 71 is attached to the slide plate 66 via supports 72, and when the slide plate 66 abuts against the collar 67a which protects the linear bushing 67 and acts as a limiting member, the spare guide member 71 rises together with the slide plate 66 and blocks the notch 36b in the guide member 36, so that the side wall portion 71a faces the flange-shaped member 15 of the pallet 11 passing therethrough in the width direction and the upper plate portion 71b faces it from above, thereby preventing the pallet 11 from shifting in the width direction and preventing the pallet 11 from floating off the circulating belt 20 or tilting relative to the belt 20 without impeding the movement of the pallet 11 in the conveying direction.

[0071] Next, a pallet conveying method using the above-mentioned pallet conveying device will be described.

[0072] Using the above-mentioned pallet conveying device 10, a method is achieved in which a plurality of pallets 11 carrying workpieces to be machined are sequentially loaded onto the circulating circulating belt 20 for conveyance. The circulation of this circulating belt 20 is performed by a driving means 30, which drives a motor 31 as the driving means to simultaneously rotate the driving pulleys 23, and the circulating belts 20 that are wound around the driving pulleys 23 and present so as to be continuous on the opposing sides of the plate 16 are each circulated in the same direction.

[0073] Pallet 11 carrying workpieces (not shown) is transported by being placed on circulation belt 20, and when pallet 11 is transported to the front of machine tools 1-4 (FIG. 2) provided along the transport path, the circulation of circulation belt 20 is temporarily stopped and pallet 11 is stopped in a state corresponding to machine tools 1-4. This makes it possible for the machine tools 1-4 to process the workpieces (not shown) carried on pallet 11.

[0074] That is, the workpiece (not shown) is placed on the placement tool 13 of the pallet 11 , and the pallet 11 on which the workpiece is placed is placed on the upstream end of the circulating belt 20 .

[0075] When the pallet 11 is loaded onto the circulating belt 20, the contact material 14 on the pallet 11 overlaps with the circulating belt 20, and as shown in the enlarged view of Figure 1, the uneven surfaces 14a, 14b formed on this contact material 14 engage with the uneven surfaces 20a, 20b formed on the circulating belt 20, and movement of the pallet 11 in the X-axis direction independent of the circulating belt 20 is prohibited. Furthermore, the presence of the pressing member 18 prevents the pallet 11 loaded onto the circulating belt 20 from floating off the circulating belt 20, so the engagement between the uneven surfaces 14a, 14b and the uneven surfaces 20a, 20b is not released.

[0076] Therefore, the pallet 11 is transported downstream at a speed equal to the circulation speed of the circulating belt 20, and when the pallet 11 reaches the front of the machine tool 1 arranged opposite the upstream circulating belt 20, the circulation of the circulating belt 20 is temporarily stopped, thereby halting the transport of the pallet 11.

[0077] While the pallet 11 is stopped facing the machine tool 1, the machine tool 1 machines a workpiece (not shown) that is mounted on the pallet 11 whose movement has been stopped.

[0078] When the workpiece mounted on that pallet 11 is being processed, if a pallet 11 carrying another workpiece (not shown) is loaded onto the upstream end of the circulating belt 20 at a distance equal to the distance between the machine tools 1 and 2, the next pallet 11 carrying that workpiece can be stopped at a waiting location near the processing location.

[0079] When the machining of the workpieces mounted on the pallet 11 at the machining location by the machine tool 1 is completed, the pallet 11 with the workpieces mounted thereon is transported downstream. The start of this transport causes the circulation of the circulating belt 20 to begin, and the pallet 11 moves downstream together with the upper edge of the circulating belt 20 which moves downstream as it circulates.

[0080] If a pallet 11 is also stopped at a waiting point upstream of the processing point, the pallet 11 at the waiting point moves to the processing point, and while the previous pallet 11 faces the machine tool 2, the following pallet 11 faces the machine tool 1. By preventing further transportation, processing can immediately begin at the machine tools 1 and 2.

[0081] Once machining by these machine tools 1 and 2 is completed, the pallet 11 is transported downstream again together with the workpieces. This transport begins by circulating the circulating belt 20, causing the pallet 11 to move downstream again. This transport and stopping of the pallet 11 is repeated, and the pallet 11 carrying the workpieces that have been machined by the necessary machine tools 1 to 4 is collected from the downstream end of the circulating belt 20 together with the workpieces machined by each of the machine tools 1 to 4.

[0082] Here, since the pallet conveying device 10 of the present invention is equipped with a pallet lifting device 50, it is possible to lift the pallet 11, which is carried on the circulating belt 20 that moves in a circular manner, during its transport and to detach the pallet 11 from the circulating belt 20.

[0083] In this pallet lifting device 50, when the mounting member 52 is lowered in the normal pallet transport state, and the pallet 11 moves and is transported while mounted on the circulating belt 20 as shown in Figure 4, the brim-shaped member 15 protruding laterally from the plate 16 moves and passes above the placement portion 52b of the mounting member 52, thereby allowing the pallet 11 mounted on the circulating belt 20 to move through the pallet lifting device 50.

[0084] As shown in Figure 5, a notch 36b is formed in the guide member 36 at the location where the pallet lifting device 50 is provided, and there is no pressure plate 18. Therefore, when lifting the pallet 11, the pallet 11 faces the pallet lifting device 50, as shown in Figure 7, the retractable rod 51b protrudes upward from the main body portion 51a, and as shown in Figure 6, the fluid pressure cylinder 51 raises the mounting member 52, and the pallet 11 mounted on the placement portion 52b of the mounting member 52 is raised by passing it through the notch 36b.

[0085] When the pallet 11 is lifted in this manner, the lifted pallet 11 is detached from the circulating belt 20, and when the circulating belt 20 is circulated in this state, the other pallets 11 except for the lifted pallet 11 are transported a distance equal to the movement of the circulating belt 20.

[0086] Therefore, after the other pallets 11 except for the lifted pallet 11 have been transported a predetermined distance, the fluid pressure cylinder 51 lowers the mounting member 52, and the lifted pallet 11 is lowered together with the mounting member 52 and re-mounted on the circulating belt 20, thereby increasing the gap between the preceding pallet 11 and decreasing the gap between the following pallet 11.

[0087] Also, as shown in Figures 6 and 7, if the lifting height of a pallet 11 by the pallet lifting device 50 exceeds the height of the work on the following pallet 11, the pallet lifting device 50 can lift the pallet 11 and circulate the circulating belt 20 to pass another following pallet 11 under the lifted pallet 11, thereby changing the transport order of the pallets 11.

[0088] For example, if a subsequent pallet 11 is passed underneath a pallet 11 lifted by a pallet lifting device 50 and the subsequent pallet 11 is placed opposite a machine tool 4 (Figure 2) located downstream of the pallet lifting device 50, it becomes possible for the machine tool 4 to machine the workpiece mounted on the subsequent pallet 11.

[0089] In this case, although a notch 36b capable of accommodating the mounting member 52 in the lowered state is formed in the guide member 36, a spare guide member 71 is provided on the slide plate 66 to cover the notch 36b when the mounting member 52 is in the raised state, so that the notch 36b of the guide member 36 does not become an obstacle when a subsequent pallet 11 passes under the lifted pallet 11.

[0090] In other words, when the subsequent pallet 11 passes underneath the lifted pallet 11, the spare guide member 71 covering the cutout 36b has its side wall portion 71a facing the flange-shaped member 15 of the pallet 11 that has entered the cutout 36b in the width direction, and its upper plate portion 71b facing it from above, thereby preventing the movement of the subsequent pallet 11 in the conveying direction, and preventing the pallet 11 from shifting in the width direction, and from floating away from the circulating belt 20 or tilting relative to the circulating belt 20, so that the subsequent pallet 11 can quickly pass underneath the lifted pallet 11 while being mounted on the circulating belt 20 which moves in a circulating manner.

[0091] Furthermore, if a machine tool 3 (FIG. 2) is placed opposite the pallet lifting device 50, the machine tool 3 can be used to machine the workpiece mounted on the lifted pallet 11.

[0092] In this case, a fixing means 61 is provided for clamping the pallet 11 together with the mounting member 52 when the mounting member 52 carrying the pallet 11 is raised by the lifting actuator 51, thereby preventing the raised pallet 11 from shifting during the machining of the workpiece mounted thereon, and causing no hindrance to the machining of the workpiece.

[0093] In particular, although this fixing means 61 does not fix the pallet 11 while it is rising, the pressing plate 62 has a step 62a which comes into contact with the side of the flange-like member 15 of the pallet 11 to limit the widthwise movement of the pallet 11. Therefore, even if there is some misalignment when the pallet 11 is mounted on the mounting member 52 in the lowered state, the step 62a eliminates the misalignment as the mounting member 52 rises, and the fixing means 61 fixes the pallet 11 in a misaligned state to the mounting member 52, making it possible to process the workpiece mounted on the pallet 11 without any misalignment.

[0094] In other words, even if some misalignment occurs when the pallet 11 is mounted on the mounting member 52, the misalignment can be eliminated in the raised state, making it possible to carry out processing that requires highly precise positioning.

[0095] In particular, as shown in FIG. 4, the mounting member 52 has a pin 52c that tapers toward the tip and protrudes toward the flange-shaped member 15, and the flange-shaped member 15 has a hole 15a formed opposite the pin 52c into which the pin 52c can enter. Therefore, as shown in FIG. 8, when the placement portion 52b of the mounting member 52 clamps the flange-shaped member 15 on the pallet 11 together with the pressing plate 62, the pin 52c is inserted into the hole 15a in the flange-shaped member 15 of the pallet 11, as shown in the enlarged view.

[0096] Therefore, even if the pallet 11 is slightly misaligned when mounted on the mounting member 52, once the fixing means 61 fixes the pallet 11 to the mounting member 52, the tapered pins 52c enter the holes 15a and the pallet 11 is returned to its correct position on the mounting member 52 and mounted there, so that the misalignment does not make processing by the processing machine 3 provided opposite the pallet lifting device 50 difficult.

[0097] In this embodiment, the pins 52c are formed at diagonal positions on the mounting member 52 (Figure 2), so that the spacing between the pins 52c on both sides of the width of the pallet 11 is larger than when they are located at symmetrical positions, thereby reducing the amount of misalignment of the pallet 11 relative to the mounting member 52 and making it possible to mount the pallet in a more correct position.

[0098] In the above-described embodiment, contact materials 14 are provided on both sides of the lower part of the base 12, and the contact materials 14 are overlapped with the circulating belt 20. However, as long as the pallet 11 mounted on the circulating belt 20 can be transported, the base 12 may be mounted directly on the circulating belt 20 without providing contact materials 14.

[0099] In the above-described embodiment, the circulating belt 20 is a so-called toothed belt 20 in which unevenness 20a, 20b extending in the width direction are formed alternately and continuously in the longitudinal direction on the outer surface, which is the mounting surface for the pallet 11, as shown in the enlarged view of Figure 1. However, as long as the pallet 11 loaded on the circulating belt 20 can be accurately transported, this belt 20 may be a belt without unevenness 20a, 20b.

[0100] In the above embodiment, the pins 52c are formed on the mounting member 52, but as long as the misalignment of the pallet 11 can be eliminated, the pins 52c may be formed on the pressing plate 62.

[0101] In the above embodiment, the pallet conveying device 10 is described as connecting four machine tools 1 to 4. However, although not shown, the pallet conveying device 10 may be configured to connect five or more machine tools. Even if the number of processing steps increases due to an increase in the number of machine tools in this way, by providing a pallet lifting device 50 that lifts the pallets 11, which are carried on the moving belt 20 and are carried, during the transportation, it is possible to change the interval (pitch) between the pallets 11 carrying the workpieces and reduce the number of pallets 11 required.

[0102] Furthermore, in the above embodiment, a pallet conveying apparatus 10 has been described that includes one pallet lifting device 50. However, although not shown, the pallet conveying apparatus 10 may include two or more pallet lifting devices 50. If two or more pallet lifting devices 50 are provided, even if the number of processing steps increases due to an increase in machine tools, the number of places where the interval (pitch) or order of the pallets 11 can be changed increases, enabling a variety of conveying modes of the pallets 11. [Explanation of symbols]

[0103] 10 Pallet transport device 11 Palette 14a,14b Uneven surface 15 Flange-shaped member 15a hole 16 Plate 18 Holding member 20 Belt 20a,20b unevenness 36 Guide member 36a Notch 50 Pallet lifting device 51 Flow-resistant cylinder (lift actuator) 52 Mounting materials 52c Pin 61 Fixing means 62 Pressing plate 62a Stepped section 63 Coil spring (biasing means) 64 Lifting rod 66 Slide Plate 67 Restriction member 71 Spare guide member

Claims

1. A pallet lifting device (50) for lifting a pallet (11) being carried on a circulating belt (20) during transport, lifting actuators (51) provided on both sides of the belt (20) so as to sandwich the belt (20); a mounting member (52) that is provided so as to be able to be raised and lowered by the lifting actuator (51) and that is configured so as to be able to mount the pallet (11) that is to be carried on the belt (20) and transported at a lowered position; a fixing means (61) for clamping the pallet (11) together with the mounting member (52) and fixing the pallet (11) to the mounting member (52) in a state where the mounting member (52) on which the pallet (11) is mounted is elevated by the lifting actuator (51); Equipped with The fixing means (61) a lifting rod (64) provided on the mounting member (52) so as to be movable up and down; a pressing plate (62) attached to the upper end of the lifting rod (64) and provided above the mounting member (52) with a predetermined gap therebetween; a biasing means (63) for biasing the pressing plate (62) and the mounting member (52) so as to widen the gap between them; a slide plate (66) attached to the lower end of the lift rod (64); a limiting member (67) that abuts against the slide plate (66) when the mounting member (52) is raised by the lifting actuator (51) to prohibit the lifting rod (64) from rising; Equipped with A pallet lifting device characterized by:

2. a pair of plates (16, 16) provided at a predetermined interval in the width direction of the conveyance direction and having circulable belts (20) attached to opposing sides thereof so as to extend in the conveyance direction; a pallet (11) that is loaded on the belt (20) and transported by the circulation of the belt (20); a flange-like member (15) formed on the pallet (11) and extending beyond the upper edges of the pair of plates (16, 16) when the pallet (11) is mounted on the belt (20); lifting actuators (51) provided on both sides of the pair of plates (16, 16) so as to sandwich the pair of plates (16, 16); a mounting member (52) that is movable up and down by the lifting actuator (51) and that is configured to mount the flange-shaped member (15) that protrudes outward from the pair of plates (16, 16) of the pallet (11) that is mounted on the belt (20) and transported at a lowered position; a fixing means (61) for fixing the pallet (11) to the mounting member (52) in a state in which the mounting member (52) on which the flange-shaped member (15) is mounted is elevated by the lifting actuator (51); A pallet transport device comprising:

3. A guide member (36) for limiting the widthwise movement of the pallet (11) carried by the belt (20) is attached to the upper edge of the plate (16), A notch (36b) capable of accommodating the mounting member (52) in a lowered state is formed in the guide member (36), A spare guide member (71) is provided which is capable of rising and falling together with the mounting member (52) and which closes the notch (36b) when raised together with the mounting member (52).

3. The pallet transport device according to claim 2.

4. The belt (20) has widthwise extending unevenness (20a, 20b) formed alternately and continuously in the longitudinal direction, The pallet (11) is formed with recesses (14a, 14b) that can be engaged with the recesses (20a, 20b) when the pallet is mounted on the belt (20), A pressing member (18) is provided on the guide member (36) to prevent the pallet (11) mounted on the belt (20) from floating off the belt (20) or tilting relative to the belt (20).

4. The pallet transport device according to claim 3.

5. A pallet conveying method in which a pallet (11) carrying a workpiece to be machined is placed on a circulating belt (20) and conveyed, Lifting actuators (51) are provided on both sides of the belt (20) so as to sandwich the belt (20), a mounting member (52) configured to be capable of mounting the pallet (11) to be transported on the belt (20) at a lowered position, the mounting member (52) being capable of being raised and lowered by the lifting actuator (51); When processing the workpiece, the mounting member (52) carrying the pallet (11) is raised by the lifting actuator (51), and the pallet (11) carrying the workpiece is fixed to the mounting member (52) in the raised state. A pallet transport method characterized by the above.

6. A belt (20) is circulably attached to a pair of plates (16) provided at a predetermined interval in the width direction of the conveying direction, The pallet (11) is formed with a flange-like member (15) that exceeds the upper edges of the pair of plates (16) when mounted on the belt (20), When the mounting member (52) is in a lowered state, the flange-shaped member (15) moves and passes above the mounting member (52).

6. The pallet transport method according to claim 5.

7. A guide member (36) for limiting the widthwise movement of the pallet (11) carried on the circulating belt (20) is attached to the upper edge of the plate (16), A notch (36a) capable of accommodating the mounting member (52) in a lowered state is formed in the guide member (36), When the mounting member (52) is in the raised state, the auxiliary guide member (71) that rises together with the mounting member (52) closes the notch (36a).

7. The pallet transport method according to claim 6.

8. The belt (20) has widthwise extending unevenness (20a, 20b) formed alternately and continuously in the longitudinal direction, The pallet (11) is formed with recesses (14a, 14b) that can be engaged with the recesses (20a, 20b) when mounted on the belt (20), A pressing member (18) provided on the guide member (36) prevents the pallet (11) mounted on the belt (20) from floating from the belt (20) or tilting relative to the belt (20). The pallet transport method according to claim 7.

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