Pallet conveying device

Abstract

To provide a pallet conveying device that can return a pallet quickly.SOLUTION: A pallet conveying device 1 comprises: a conveying path 11; a return path 21 arranged beneath the conveying path 11; a connection path 71 formed, along an other end-side circular arc track A3 connecting a downstream end 11B of the conveying path 11 to an upstream end 21A of the return path 21, between the downstream end 11B of the conveying path 11 and the upstream end 21A of the return path 21; a pallet 31 that can move on the conveying path 11, the connection path 71 and the return path 21, on which a work-piece W can be placed; a first rotary guide 81, installed at an outer periphery side of the other end-side circular arc track A3, which guides movement of the pallet 31 on the connecting path 71; and a stopper 91, provided on an upper part at a downstream side of the conveying path 11, which contacts a work-piece W placed on the pallet 31. When the work-piece W is in contact with the stopper 91, a front end part 36 of the pallet is positioned on the connection path 71.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pallet transport device. [Background technology]

[0002] Patent document 1 discloses a conveying device in which a pallet containing a workpiece is stopped by a stopper that only contacts the workpiece, and when the workpiece is removed from the pallet, the pallet passes through the stopper and is automatically transported into a conveying section, and then automatically transported from the conveying section to a return chute. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-120468 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the conveying device of Patent Document 1, when returning a pallet after removing workpieces, the conveying section located at the extension of the chute rotates due to the weight of the pallet and returns it to the return chute. Therefore, it takes time to return the pallet.

[0005] An object of the present invention is to provide a pallet conveying device that can quickly return a pallet. [Means for solving the problem]

[0006] A pallet conveying device according to an aspect of the present invention includes a conveying path, a return path disposed below the conveying path, and a connection path formed along the other-end-side arc orbit connecting the downstream end of the conveying path and the upstream end of the return path between the downstream end of the conveying path and the upstream end of the return path. A pallet that is movable above the conveying path, the connection path, and the return path and on which a workpiece can be placed, a first rotation guide installed on the outer peripheral side of the other-end-side arc orbit to guide the movement of the pallet in the connection path, and a stopper provided above the downstream side of the conveying path and abutting against the workpiece placed on the pallet. When the workpiece is in contact with the stopper, the front end portion of the pallet is located on the connection path.

Effect of the Invention

[0007] According to the present invention, it is possible to provide a pallet conveying device capable of quickly returning a pallet.

Brief Description of the Drawings

[0008] [Figure 1] It is a side view of a pallet conveying device according to an embodiment. [Figure 2A] It is a perspective view showing the structure of a pallet according to an embodiment. [Figure 2B] It is a perspective view showing the structure of a pallet according to an embodiment. [Figure 2C] It is a perspective view showing the structure of the lower surface of a pallet according to an embodiment. [Figure 3A] It is a cross-sectional view showing the positional relationship between the conveying path and the pallet according to an embodiment. [Figure 3B] It is a cross-sectional view showing the positional relationship between the return path and the pallet according to an embodiment. [Figure 4A] It is an enlarged view showing the operation of a pallet conveying device according to an embodiment. [Figure 4B] It is an enlarged view showing the operation of a pallet conveying device according to an embodiment. [Figure 4C] It is an enlarged view showing the operation of a pallet conveying device according to an embodiment. [Figure 4D] It is an enlarged view showing the operation of a pallet conveying device according to an embodiment. [Figure 5A] 5A and 5B are schematic diagrams showing a connection structure between a slider and a lifting portion according to the embodiment. [Figure 5B] 5A and 5B are schematic diagrams showing a connection structure between a slider and a lifting portion according to the embodiment. [Figure 6A] 5A and 5B are schematic diagrams showing a connection structure between a sub-slider and a push-up portion according to the embodiment. [Figure 6B] 5A and 5B are schematic diagrams showing a connection structure between a sub-slider and a push-up portion according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a pallet conveying device 1 according to an embodiment will be described with reference to the drawings.

[0010] The pallet conveying device 1 includes a conveying path 11, a return path 21, a pallet 31 on which a workpiece W can be placed, a lifting section 41, and a pushing section 51. Here, for convenience of explanation, the height direction of the pallet conveying device 1 is defined as the up-down direction, and the direction perpendicular to the up-down direction is defined as the horizontal direction. In the left-right direction in FIG. 1, the left side is defined as one side, and the right side in FIG. 1 is defined as the other side. In the left-right direction in FIG. 1, the left side of the conveying path 11 is defined as the upstream side, and the right side of the conveying path 11 is defined as the downstream side. In the left-right direction in FIG. 1, the right side of the return path 21 is defined as the upstream side, and the left side of the return path 21 is defined as the downstream side. The direction from the upstream side to the downstream side of the conveying path 11 is defined as the conveying direction, and the direction from the upstream side to the downstream side of the return path 21 is defined as the return direction. In the horizontal direction, the direction perpendicular to the conveying direction and the return direction is defined as the width direction. Note that the directions such as "up-down" and "left-right" are defined for convenience of explanation, and do not limit the actual arrangement of each element.

[0011] The conveying path 11 is configured by three rows of roller ways R arranged in parallel in the width direction (see FIG. 3A). The three rows of roller ways R are arranged at a predetermined interval in the width direction. The roller ways R are configured by a plurality of rollers having rotation axes in the width direction arranged in the conveying direction. The conveying path 11 is inclined downward from the upstream side to the downstream side (see FIG. 1). The inclination angle of the conveying path 11 with respect to the horizontal direction is set to angle α1. The pallet 31 is movable on the conveying path 11, and the workpiece W, which is the object to be conveyed, can be placed on the pallet 31. That is, the pallet 31 can easily move from the upstream side to the downstream side of the conveying path 11 with the workpiece W placed thereon.

[0012] A plurality of pallets 31 carrying workpieces W can be arranged in the conveying direction on the conveying path 11. That is, by placing workpieces W on the pallets 31 and moving them sequentially in the conveying direction, a plurality of pallets 31 carrying workpieces W can be stored on the conveying path 11. When a workpiece W is removed from the pallet 31 located at the most downstream side of the conveying path 11 among the stored pallets 31, the pallet 31 passes through a connecting path 71 described later and slides down to the return path 21, and is returned from the upstream side to the downstream side of the return path 21 (see FIG. 1).

[0013] The workpiece W according to the embodiment is a bumper fascia to be attached to a vehicle body. For example, the workpiece W that has completed a predetermined process can be placed on a pallet 31 on the conveying path 11, and the pallet 31 can be moved in sequence in the conveying direction and stored on the conveying path 11. This allows the workpiece W to be moved to the next process to be conveyed and stored. The empty pallet 31 from which the workpiece W has been removed is returned through the return path 21 and is lifted up to the conveying path 11 by a lifting unit 41, which will be described later. Thus, the pallet 31 circulates through the pallet conveying device 1. The number of pallets 31 that can be stored on the conveying path 11 can be appropriately set by adjusting the lengths of the conveying path 11 and the return path 21. In addition, the type of workpiece W and the use of conveying and storing the pallet 31 are not limited to those described above.

[0014] The conveying path 11 may have a first inclined portion 11C inclined at an angle α2 with respect to the horizontal direction, and a second inclined portion 11D inclined at an angle α3 with respect to the horizontal direction downstream of the first inclined portion 11C. In this case, the angle α2 may be set smaller than the angle α3. Furthermore, the angle α2 may be set to 0°, and the first inclined portion 11C may be installed horizontally. In this case, the first inclined portion 11C can suppress the pallet 31 before the workpiece W is placed thereon from moving downstream in the conveying direction due to its own weight. The second inclined portion 11D can easily move the pallet 31 with the workpiece W placed thereon downstream in the conveying direction.

[0015] The return path 21 is disposed below the conveying path 11. The return path 21 is configured by arranging two rows of roller ways R in parallel in the width direction (see FIG. 3B). The two rows of roller ways R are arranged at a predetermined interval from each other in the width direction. The roller ways R are configured by arranging a plurality of rollers having a rotation axis in the width direction in the conveying direction. The return path 21 is inclined downward from the upstream side to the downstream side of the return path 21 (see FIG. 1). The inclination angle of the return path 21 with respect to the horizontal direction is set as angle β1. The pallet 31 that has taken out the workpiece W passes through the connection path 71 described later, turns upside down, and slides down onto the return path 21. That is, the pallet 31 is arranged on the return path 21 in a state that is upside down from the state where it is arranged on the conveying path 11, and moves on the return path 21 from the upstream side to the downstream side.

[0016] In the embodiment, the angle α1, which is the inclination angle of the conveying path 11 with respect to the horizontal direction, is set to be smaller than the angle β1, which is the inclination angle of the return path 21 with respect to the horizontal direction (see FIG. 1). Therefore, on the conveying path 11, the pallet 31 on which the workpiece W is placed moves gently toward the downstream side. On the return path 21, the pallet 31 from which the workpiece W has been removed can be quickly moved toward the downstream side of the return path 21.

[0017] The pallet 31 that has moved to the downstream side of the return path 21 is pulled up to the upstream side of the conveying path 11 by the lifting unit 41 (see FIG. 1). The lifting unit 41 has a movable engagement unit 42 that can engage with the pallet 31 (see FIG. 4A). The movable engagement unit 42 can reciprocate along an arc-shaped track A1 that connects the upstream end 11A of the conveying path 11 and the downstream end 21B of the return path 21. On the arc-shaped track A1, the movable engagement unit 42 has a first rotation position L1 that corresponds to the downstream end 21B of the return path 21 and a second rotation position L2 that corresponds to the upstream end 11A of the conveying path 11 (see FIG. 4A). With the movable engagement portion 42 engaged with the pallet 31 on the return path 21, the movable engagement portion 42 can be moved forward from the first rotation position L1 to the second rotation position L2 on the arcuate orbit A1, thereby lifting the pallet 31 from the downstream side of the return path 21 to the upstream side of the conveying path 11 (see Figure 4A).

[0018] The movable engagement part 42 according to the embodiment is rotatable around a rotation shaft 42A extending in the width direction, and is configured at the tip of an arm 42B extending in the radial direction from the rotation shaft 42A (see FIG. 1). The rotation shaft 42A is provided between the upstream end 11A of the conveying path 11 and the downstream end 21B of the return path 21 in the vertical direction. The movable engagement part 42 can reciprocate around the rotation shaft 42A along an arcuate orbit A1 from a first rotation position L1 to a second rotation position L2 within an angle range of approximately 180°.

[0019] The movable engaging portion 42 is provided with an engaging claw 42C for engaging with the pallet 31 (see FIG. 4A). The engaging claw 42C is formed extending radially from the movable engaging portion 42. An engaged portion 34 protruding upward is provided at the front of the pallet 31 on the return path 21 (see FIG. 3B). In other words, the engaged portion 34 is formed protruding from the lower surface of the tray 32 in the posture of the pallet 31 on the conveying path 11. Since the pallet 31 on the return path 21 is disposed in an upside-down posture, the engaged portion 34 protrudes upward on the return path 21. When the movable engaging portion 42 is moved forward from the first rotation position L1 in a state in which the pallet 31 is located on the downstream side of the return path 21, the engaging claw 42C is engaged with the engaged portion 34, and the movable engaging portion 42 and the pallet 31 are engaged with each other. By further moving the movable engaging portion 42 forward, the pallet 31 can be pulled upward while maintaining the engaged state. By moving the movable engagement portion 42 forward to the second rotation position L2, the pallet 31 can be pulled up to the conveying path 11. The shapes of the engagement claws 42C and the engaged portion 34 are not limited to those described above, and any shape may be used as long as the pallet 31 can be pulled up while the movable engagement portion 42 and the pallet 31 are maintained in an engaged state.

[0020] The pushing unit 51 is configured to be movable between the upstream side and the downstream side of the conveying path 11 (see FIG. 1). By moving forward from the upstream side to the downstream side of the conveying path 11, the pushing unit 51 can push the pallet 31 to the downstream side of the conveying path 11. The pushing unit 51 according to the embodiment is disposed directly below the conveying path 11 and has a pushing claw 52 protruding upward (see FIG. 1). The pushing unit 51 is connected to a slider 53 that can reciprocate on a rail via an arm (not shown). The rail is provided along the horizontal direction connecting one end side and the other end side of the pallet conveying device 1. On the rail, the movement of the slider 53 from one end side to the other end side is the forward movement, and the movement of the slider 53 from the other end side to the one end side is the return movement. Therefore, the pushing unit 51 moves between the upstream side and the downstream side of the conveying path 11 by reciprocating the slider 53. The push-out claws 52 push the pallet 31 downstream as the slider 53 moves forward. The push-out claws 52 move from the downstream side to the upstream side of the conveying path 11 as the slider 53 moves backward, and return to their original position from which they can push the pallet 31 downstream of the conveying path 11.

[0021] Furthermore, the push-out unit 51 and the lift-up unit 41 are connected so as to be interlocking with each other. More specifically, the movable engagement unit 42 is configured to move forward along the arc-shaped track A1 as the push-out unit 51 moves from the upstream side to the downstream side of the conveying path 11. Therefore, as the slider 53 moves forward, the push-out claws 52 push the pallet 31 on the conveying path 11 downstream, and the movable engagement unit 42 moves forward along the arc-shaped track A1.

[0022] The push-out section 51 and the pull-up section 41 are connected by a first string-like member S1 (see Figs. 5A and 5B). One end of the first string-like member S1 is connected to the slider 53. The other end of the first string-like member S1 is connected to the arm 42B of the pull-up section 41. As the slider 53 moves forward, the slider 53 pulls the first string-like member S1, which pulls the arm 42B in the forward direction, causing the movable engagement section 42 to move forward. When the slider 53 moves backward, the tensile force of the first string-like member S1 is no longer applied, and the movable engagement section 42 is moved backward by the weight connected to the first string-like member S1. The first string-like member S1 is connected so as to be able to transmit power due to tension through a pulley, axle, pulley, tensioner, weight, etc. as appropriate. The first string-like member S1 can be made of any material capable of transmitting power, such as a fishing line, a belt, a chain, or a rope.

[0023] The lifting unit 41 lifts the pallet 31 to the upstream side of the conveying path 11. However, depending on the length of the pallet 31 relative to the arcuate track A1, the weight, etc., this lifting operation may not be sufficient to lift the pallet 31 onto the conveying path 11. A push-up unit 61 is provided to push the pallet 31 lifted by the lifting unit 41 further onto the conveying path 11. The push-up unit 61 has a second movable engagement unit 62 that can engage with the pallet 31 (see FIG. 1). The second movable engagement unit 62 can reciprocate along the second arcuate track A2 connected to the upstream end of the conveying path 11 between a third rotational position L3 corresponding to the upstream end of the conveying path 11 and a fourth rotational position L4 below the third rotational position L3 (see FIG. 4D). The second movable engagement portion 62 is moved back to the fourth rotation position L4 as the push-out portion 51 moves forward, and is moved forward along the second arcuate orbit A2 while engaged with the pallet 31 as the push-out portion 51 moves back, thereby pushing the pallet 31 up onto the conveying path (see Figure 4D).

[0024] The second movable engagement part 62 according to the embodiment is configured at the tip of a radially extending arm 62B rotatable around a rotation shaft 62A extending in the width direction. The rotation shaft 62A is provided in common with the rotation shaft 42A. The second movable engagement part 62 is provided with an engagement claw 62C for engaging with the pallet 31. The engagement claw 62C is formed extending in the radial direction from the second movable engagement part 62. When the second movable engagement part 62 is moved forward from the fourth rotation position L4 of the second arcuate orbit A2, the engagement claw 62C is engaged with the rear end of the pallet 31, and the second movable engagement part 62 and the pallet 31 are engaged with each other. By further moving the second movable engagement part 62 forward, the pallet 31 can be pushed out onto the conveying path 11 while maintaining the engagement state. The second movable engagement portion 62 can reciprocate around the rotation shaft 62A along the second arcuate path A2 within an angle range of approximately 90° from the fourth rotation position L4 to the third rotation position L3.

[0025] The push-up portion 61 is connected to the push-out portion 51 so as to be movable in conjunction with it. When the push-out portion 51 is moved back, the second movable engagement portion 62 is moved forward from the fourth rotation position L4 to the third rotation position L3. This forward movement pushes the pallet 31 up onto the conveying path 11. Furthermore, as described above, when the push-out portion 51 is moved back, the movable engagement portion 42 is moved back from the second rotation position L2 to the first rotation position L1.

[0026] The slider 53 of the pushing-out section 51 has a sub-slider 53A. The sub-slider 53A and the push-up section 61 are connected by a second string-like member S2 (see Figs. 6A and 6B). One end of the second string-like member S2 is connected to the sub-slider 53A. The other end of the second string-like member S2 is connected to the arm 62B of the push-up section 61. The sub-slider 53A moves forward on the rail together with the forward movement of the slider 53, and stops when it moves forward to a predetermined position. At this time, the arm 62B moves back to the fourth rotation position L4 by its own weight. When the slider 53 moves back and reaches a predetermined position, the sub-slider 53A moves back together with the slider 53. At this time, as the slider 53 moves back, the sub-slider 53A pulls the second string-like member S2, and the arm 62B is pulled in the forward movement direction, causing the second movable engagement section 62 to move forward. The second string-like member S2 is connected so as to be capable of transmitting power by tension, appropriately via a pulley, axle, pulley, tensioner, weight, etc. The second string-like member S2 can be made of any material capable of transmitting power, such as fishing line, belt, chain, rope, etc.

[0027] A second rotary guide 82 and a third rotary guide 83 are provided on the outer periphery and inner periphery of the arcuate track A1, respectively. The second rotary guide 82 is formed on an arc at a predetermined distance away from the arcuate track A1 on the outer periphery side. The third rotary guide 83 is formed on an arc at a predetermined distance away from the arcuate track A1 on the inner periphery side.

[0028] A connection path 71 is provided between the downstream end 11B of the conveying path 11, which is the other end side of the pallet conveying device 1, and the upstream end 21A of the return path 21 (see FIG. 1). The connection path 71 is formed along the other end side arc track A3 that connects the downstream end 11B of the conveying path 11 and the upstream end 21A of the return path 21. The connection path 71 extends from the downstream end of the conveying path 11 along the other end side arc track A3, curves downward, and is formed by folding back toward the downstream side of the return path 21. The tip portion 71A of the folded back connection path 71 is deviated from the other end side arc track A3 and is disposed above the upstream end 21A of the return path 21. Therefore, the pallet 31 located near the downstream end 11B of the conveying path 11 slides downward while rotating along the connection path 71, and moves upside down to the vicinity of the upstream end 21A of the return path 21. A first rotary guide 81 formed of a plate-like member curved along the other end side arcuate track A3 is installed on the outer periphery of the connection path 71 (see FIG. 1). The first rotary guide 81 is formed on an arc away from the surface of the connection path 71 on the outer periphery by a predetermined distance greater than the thickness of the pallet 31.

[0029] The connection path 71 in the embodiment is formed by extending the downstream end 11B of the conveying path 11, but the connection path 71 may be formed independently of the conveying path 11 and the return path 21. The configuration of the connection path 71 is not limited to the above, as long as the pallet 31 located near the downstream end 11B of the conveying path 11 slides down while rotating and falls upside down near the upstream end 21A of the return path 21. Therefore, the connection path 71 may be formed with a plate-like curved portion that curves along the other end side arc track A3. The configuration of the first rotating guide 81 is also not limited to the above, and may be formed, for example, by a roller way R.

[0030] The pallet 31 has a plate-like tray 32 that can be bent in the thickness direction, and a buffer section 33 formed on the upper surface of the tray 32 (see Figs. 2A and 2B). Here, the upper surface of the tray 32 means the surface of the tray 32 that faces upward when the pallet 31 is placed on the conveying path 11. On the upper surface of the tray 32, a plurality of convex sections 32A extending in the width direction are arranged with a certain gap in the conveying direction. The buffer sections 33 are formed at both ends in the width direction of the upper surface of the tray 32, protruding upward from the upper surface of the convex sections 32A. The buffer sections 33 are made of, for example, urethane foam. The buffer sections 33 may be formed to extend in the conveying direction, or may be formed in a block shape and independently arranged on the convex sections 32A.

[0031] Two guide portions 35, 35 protruding downward are formed on the underside of the tray 32 (see FIG. 2C). The guide portions 35, 35 are arranged sandwiched between the adjacent roller ways R in the width direction when the pallet 31 is placed on the conveying path 11. In other words, the guide portions 35, 35 are arranged sandwiching the central roller way R among the three rows of roller ways R. Therefore, in the conveying path 11, the pallet 31 is conveyed downstream while being guided by the sliding between the guide portions 35, 35 and the roller ways R. The guide portions 35, 35 are provided at the front of the underside of the tray 32, but may also be provided at the center or rear.

[0032] The pallet 31 is placed on the return path 21 upside down compared to the conveying path 11. That is, when the pallet 31 is placed on the return path, the buffer section 33 protrudes downward from the tray 32. At this time, the inner walls 33A on the widthwise inner side of the buffer section 33 are respectively disposed on the widthwise outer sides of the two rows of roller ways R on the return path 21. Therefore, the inner walls 33A can slide with the roller ways R on the widthwise outer sides of the roller ways R, respectively. Therefore, on the return path 21, the pallet 31 is returned downstream while being guided by the sliding between the inner walls 33A and the roller ways R.

[0033] A receiving portion 33B for holding and positioning the workpiece W may be formed on the upper surface of the buffer portion 33 (see Figs. 2A and 2B). By placing the workpiece W on the receiving portion 33B, the workpiece W placed on the pallet 31 can be positioned and held in an appropriate position, and contact between the workpieces W can be prevented. In addition, the workpiece W can be reliably placed in a stable position on the pallet 31. The shape of the receiving portion 33B is not particularly limited, and can be set appropriately according to the shape of the workpiece W, etc.

[0034] A stopper 91 that abuts against the workpiece W placed on the pallet 31 is provided above the downstream side of the conveying path 11 (see FIG. 1). That is, the pallet 31 on which the workpiece W is placed moves on the conveying path 11, and a plurality of pallets 31 are stored on the conveying path. The workpiece W on the leading pallet 31 abuts against the stopper 91, and the pallet 31 is stopped. The stopper 91 abuts only against the workpiece W. When the stopper 91 abuts against the workpiece W, the front end 36 of the pallet 31 is located downstream of the conveying path 11 from the stopper 91, is located on the connecting path 71, and approaches the connecting path 71. In other words, the front end 36 of the pallet 31 is bent downward along the connecting path 71. Therefore, when the workpiece W is removed from the pallet 31, the pallet 31 quickly slides down the connecting path 71.

[0035] The operation of the pallet conveying device 1 according to the embodiment will be described in order along with a series of movements of the pallet 31. First, the workpiece W is placed on the pallet 31 on the conveying path 11. With the workpiece W placed on the pallet 31 arranged on the conveying path 11, the push-out unit 51 is moved forward. That is, the slider 53 is moved from one end to the other end on the rail. As a result, the push-out claws 52 provided directly below the conveying path 11 move from the upstream side to the downstream side of the conveying path 11. Due to this movement, the pallet 31 is pushed out by the push-out claws 52 to the downstream side of the conveying path 11. The pallet 31 on which the workpiece W is placed moves to the downstream side of the conveying path 11 while being guided by the guide units 35, 35 (pushing operation).

[0036] A stopper 91 provided above the downstream side of the conveying path 11 stops the movement of the pallet 31 on which the workpiece W is placed downstream. That is, the stopper 91 abuts against the placed workpiece W, and the pallet 31 stops at the position of the stopper 91. As a result, a plurality of pallets 31 on which the workpiece W is placed can be stored upstream of the pallet 31. When the workpiece W abuts against the stopper 91, the front end 36 of the pallet 31 is located on the connecting path 71. Therefore, at this time, a part of the pallet 31 is approaching the connecting path 71. In other words, the front end 36 of the pallet 31 is bent downward along the connecting path 71. When the workpiece W on the pallet 31 is removed in this state, the pallet 31 quickly slides down the connecting path 71 and moves to the return path 21 (moving operation).

[0037] The pallet 31 slides down the connecting path 71, turns upside down, and moves onto the return path 21. The return path 21 is inclined downward toward the downstream side. Therefore, the pallet 31 is quickly returned to the downstream side while being guided by the inner wall 33A (return operation). In the return path 21 according to the embodiment, deceleration rollers 22 are provided on the upstream side of the return path 21 in order to adjust the return speed of the pallet 31. When the pallet 31 passes through the upstream side of the return path 21, the deceleration rollers 22 come into contact with the surface of the pallet 31, and the pallet 31 is appropriately decelerated by the rotation friction of the deceleration rollers 22. In addition, a return stopper 23 is provided on the downstream side of the deceleration rollers 22. The return stopper 23 can limit the number of pallets 31 returned to the downstream end 21B of the return path 21 to a predetermined number. The return stopper 23 has a rotation shaft extending in the width direction. When a pallet 31 is disposed downstream of the rotation shaft, the portion of the return stopper 23 downstream of the rotation shaft abuts against the pallet 31 and rotates upward. This causes the portion of the return stopper 23 upstream of the rotation shaft to rotate downward, stopping the return of the pallet 31 upstream of the rotation shaft.

[0038] The returned pallet 31 reaches the downstream end 21B of the return path 21. At this time, when the slider 53 is moved back, the movable engagement part 42 moves back to the first rotation position L1. When the slider 53 is moved forward in this state, the movable engagement part 42 moves forward along the arcuate track A1. As a result, the engagement claw 42C of the movable engagement part 42 is engaged with the engaged part 34 of the pallet 31 on the return path 21, and the movable engagement part 42 and the pallet 31 are engaged with each other (see FIG. 4A). While maintaining this state, the movable engagement part 42 moves forward from the first rotation position L1 to the second rotation position L2, and the pallet 31 is pulled up to the conveying path 11 (pulling up operation) as shown in FIGS. 4B and 4C. Meanwhile, the sub-slider 53A also moves forward to a predetermined position in accordance with the forward movement of the slider 53. At this time, the second movable engagement portion 62 returns to the fourth rotation position L4 due to its own weight (see FIGS. 4B-4D).

[0039] Next, the slider 53 that has moved forward is moved backward. As a result, the sub-slider 53A also moves backward from the predetermined position, and the second movable engagement portion 62 moves forward along the second arcuate path A2. As shown in FIG. 4D, with the engagement claws 62C engaged with the pallet 31, the pallet can be pushed up onto the conveying path 11 (pushing-up operation). Meanwhile, the movable engagement portion 42 moves backward from the second rotation position L2 to the first rotation position L1. By repeating the above-mentioned operation, the pallet 31 can be circulated in the pallet conveying device 1.

[0040] The pallet conveying device 1 according to the embodiment includes a conveying path 11, a return path 21 disposed below the conveying path 11, a connecting path 71 formed between the downstream end 11B of the conveying path 11 and the upstream end 21A of the return path 21 along the other end side arcuate track A3 connecting the downstream end 11B of the conveying path 11 and the upstream end 21A of the return path 21, a pallet 31 that can move on the conveying path 11, the connecting path 71 and the return path 21 and on which a workpiece W can be placed, a first rotating guide 81 that is installed on the outer periphery of the other end side arcuate track A3 and guides the movement of the pallet 31 on the connecting path 71, and a stopper 91 that is provided above the downstream side of the conveying path 11 and abuts against the workpiece W placed on the pallet 31. When the workpiece W abuts against the stopper 91, the front end 36 of the pallet is located on the connecting path 71.

[0041] With the above configuration, when the workpieces W on the pallet 31 are removed, the pallet 31 moves quickly to the connection path 71 and the return path 21, making it possible to quickly return the pallet 31. In addition, since a configuration such as a chute for returning the pallet 31 is not required, the size of the device can be reduced.

[0042] In the embodiment, the conveying path 11 is inclined downward from the upstream side to the downstream side of the conveying path 11, and the return path 21 is inclined downward from the upstream side to the downstream side of the return path 21. Angle α1, which is the inclination angle of the conveying path 11 with respect to the horizontal direction, is smaller than angle α2, which is the inclination angle of the return path 21 with respect to the horizontal direction. Therefore, in the conveying path 11, the workpieces W placed on the pallets 31 can be conveyed while preventing them from contacting each other. In the return path 21, by making the inclination relatively large, the pallets 31 on which the workpieces W are not placed can be quickly returned.

[0043] Further, in the embodiment, the return path 21 has two rows of roller ways R arranged in parallel in the width direction, each of which is configured by arranging a plurality of rollers having a rotation axis in the width direction perpendicular to the conveying direction in the conveying direction. The pallet 31 has a plate-shaped tray 32 that can be bent in the thickness direction, and a buffer section 33 that protrudes upward from the upper surface of the tray 32 at both ends in the width direction of the tray 32 and extends in the conveying direction. The inner walls 33A of the buffer section 33 on the inner side in the width direction are respectively arranged on the outer side in the width direction of the two rows of roller ways R. As a result, the pallet 31 can be returned in the return path 21 using the buffer section 33 as a guide. Therefore, the return path 21 can be configured with a simple configuration, and the pallet conveying device 1 can be made lighter.

[0044] Furthermore, in the embodiment, the conveying path 11 has three rows of roller ways R arranged in parallel in the width direction. The pallet 31 has a guide portion 35 that protrudes downward from the lower surface of the tray 32 and extends in the conveying direction. The guide portion 35 is arranged by being sandwiched between the inner sides of the adjacent roller ways R in the width direction. This allows the pallet 31 on which the workpiece W is placed to be stably conveyed on the conveying path 11.

[0045] In the embodiment, the lifting unit 41 has a movable engagement unit 42 that can reciprocate along an arc-shaped track A1 connecting the upstream end 11A of the conveying path 11 and the downstream end 21B of the return path 21 and can engage with the pallet 31. The lifting unit 41 moves the movable engagement unit 42 forward along the arc-shaped track A1 while engaging the movable engagement unit 42 with the pallet 31 on the return path 21, thereby lifting the pallet 31 to the upstream side of the conveying path 11. The pushing unit 51 pushes the pallet 31 on the conveying path 11 to the downstream side of the conveying path 11 by moving from the upstream side to the downstream side of the conveying path 11. The pushing unit 51 and the lifting unit 41 are connected to be interlocked with each other so that the movable engagement unit 42 moves forward along the arc-shaped track A1 as the pushing unit 51 moves from the upstream side to the downstream side of the conveying path 11.

[0046] The above-mentioned configuration makes it possible, with a simple configuration, to transport the pallet 31 to the downstream side of the transport path 11 and to lift the pallet 31 from the return path 21 to the transport path 11. In particular, by moving the movable engagement part 42 forward along the arcuate track A1 in a state where the movable engagement part 42 is engaged with the pallet 31 on the return path 21, the pallet 31 can be smoothly lifted from the return path 21 to the transport path 11. In addition, since no drive motor or the like is required for the transport, return and lifting of the pallet 31, it is also possible to reduce manufacturing costs, installation space and operating power.

[0047] Further, in the embodiment, the movable engagement portion 42 has a first rotational position L1 corresponding to the downstream end 21B of the return path 21 and a second rotational position L2 corresponding to the upstream end 11A of the conveying path 11 on the arcuate path A1. The push-up portion 61 has a second movable engagement portion 62 that can reciprocate between a third rotational position L3 corresponding to the upstream end 11A of the conveying path 11 and a fourth rotational position L4 below the third rotational position L3 along the second arcuate path A2 connected to the upstream end 11A of the conveying path 11 and can engage with the pallet 31. The push-up portion 61 moves the second movable engagement portion 62 back to the fourth rotational position L4 in accordance with the forward movement of the push-out portion 51, and moves the second movable engagement portion 62 forward along the second arcuate path A2 in a state in which the second movable engagement portion 62 is engaged with the pallet 31 in accordance with the backward movement of the push-out portion 51, thereby pushing up the pallet 31 onto the conveying path 11. The push-up unit 61 is connected to be interlocking with the push-out unit 51. The push-out unit 51 is moved forward to push out the pallet 31 to the downstream side of the conveying path 11, and the movable engagement unit 42 is moved forward from the first rotation position L1 to the second rotation position L2, thereby lifting the pallet 31 to the upstream side of the conveying path 11. The push-out unit 51 is moved backward to move the movable engagement unit 42 from the second rotation position L2 to the first rotation position L1, and the second movable engagement unit 62 is moved forward from the fourth rotation position L4 to the third rotation position L3, thereby pushing up the pallet 31.

[0048] Therefore, the reciprocating motion of the push-out part 51 makes it possible to lift the pallet 31 from the return path 21 onto the conveying path 11. In particular, by moving the second movable engagement part 62 forward along the second arcuate track A2 in a state in which the second movable engagement part 62 is engaged with the pallet 31, the pallet 31 can be smoothly lifted up onto the conveying path 11.

[0049] In the embodiment, a second rotating guide 82 and a third rotating guide 83 that guide the lifting of the pallet 31 by the lifting unit 41 are provided on the outer periphery and inner periphery of the arcuate track A1, respectively. As a result, when the pallet 31 on the return path 21 is lifted onto the conveying path 11, it can be lifted smoothly by the second rotating guide 82 and the third rotating guide 83.

[0050] In the above embodiment, the conveying path 11 is configured with three rows of roller ways R arranged in parallel in the width direction, and the return path 21 is configured with two rows of roller ways R arranged in parallel in the width direction, but these configurations are not limited to the above. Also, two guide parts 35, 35 are formed on the lower surface of the tray 32, but the number and arrangement of the guide parts are not limited to the above.

[0051] As described above, the embodiment of the present invention has been described, but the description and drawings forming a part of this disclosure should not be understood as limiting this invention. From this disclosure, various alternative embodiments, examples and operating techniques will become apparent to those skilled in the art. [Explanation of symbols]

[0052] 1 Pallet transport device 11 Transport path 11A Upstream end of the conveying path 11B Downstream end of conveying path 21 Return Route 21A Upstream end of return path 21B Downstream end of return path 31 Palette 32 Tray 33 Buffer section 33A Inner wall 35 Guide section Front end of the 36 pallets 41 Lifting part 42 Movable engaging part 51 Extrusion part 61 Pushing-up part 62 Second movable engaging part 71 Connection path 81 First rotation guide 82 Second rotation guide 83 Third rotation guide 91 Stopper A1 Arc track A2 Second arc track A3 Arc track on the other end side L1 First rotation position L2 Second rotation position L3 Third rotation position L4 Fourth rotation position R Roller way W Workpiece α1, β1 Angles

Claims

1. A conveying path; A return path disposed below the conveying path; a connecting path formed between the downstream end of the conveying path and the upstream end of the return path along an arcuate track on the other end side connecting the downstream end of the conveying path and the upstream end of the return path; a pallet that is movable on the conveying path, the connecting path, and the return path and on which a workpiece can be placed; A first rotary guide is installed on the outer periphery of the other end side arcuate track and guides the movement of the pallet in the connection path; a stopper provided above the downstream side of the conveying path and adapted to come into contact with the workpiece placed on the pallet; A pallet conveying device, wherein when the workpiece is in contact with the stopper, the front end of the pallet is positioned on the connecting path.

2. the conveying path is inclined downward from the upstream side to the downstream side of the conveying path, The return path is inclined downward from the upstream side to the downstream side of the return path, 2. The pallet conveying device according to claim 1, wherein an inclination angle of said conveying path with respect to the horizontal direction is smaller than an inclination angle of said return path with respect to the horizontal direction.

3. The return path is configured by arranging a plurality of rollers having rotation axes in a width direction perpendicular to the conveying direction in the conveying direction, the roller ways being arranged in two rows parallel to the width direction, The pallet includes a plate-shaped tray that is bendable in a thickness direction, and a buffer portion that protrudes upward from an upper surface of the tray at both ends in the width direction of the tray and extends in the conveying direction, The pallet conveying device according to claim 1 or 2, wherein inner walls on the inner side in the width direction of the buffer section are respectively arranged on the outer sides in the width direction of two rows of the roller ways.

4. The conveying path has three rows of roller ways arranged in parallel in the width direction, the pallet has a guide portion that protrudes downward from a lower surface of the tray and extends in the conveying direction, The pallet transport device according to claim 3 , wherein the guide portions are arranged to be sandwiched between the inner sides of adjacent roller ways in the width direction.

5. a lifting section that is reciprocable along an arcuate path connecting an upstream end of the conveying path and a downstream end of the return path, has a movable engagement section that can engage with the pallet, and lifts the pallet to the upstream side of the conveying path by moving the movable engagement section forward and backward along the arcuate path while the movable engagement section is engaged with the pallet on the return path; a push-out unit that moves from an upstream side to a downstream side of the conveying path to push out the pallet on the conveying path to the downstream side of the conveying path; Equipped with A pallet conveying device as described in claim 1 or 2, wherein the push-out portion and the lift-up portion are connected to be interlocked with each other so that the movable engagement portion moves forward and backward along the arcuate orbit as the push-out portion moves from the upstream side to the downstream side of the conveying path.

6. the movable engagement portion has a first rotation position on the arcuate path corresponding to a downstream end of the return path and a second rotation position corresponding to an upstream end of the conveying path, a push-up section connected to be interlocked with the push-out section, the push-up section having a second movable engagement section capable of reciprocating along a second arcuate track connected to the upstream end of the transport path between a third rotational position corresponding to the upstream end of the transport path and a fourth rotational position lower than the third rotational position and capable of engaging with the pallet, the push-out section returning the second movable engagement section to the fourth rotational position as the push-out section moves forward, and in a state in which the second movable engagement section is engaged with the pallet as the push-out section moves backward, thereby pushing up the pallet onto the transport path; Equipped with the push-out portion is moved forward to push out the pallet toward the downstream side of the conveying path, and the movable engagement portion is moved forward from the first rotation position to the second rotation position to lift the pallet toward the upstream side of the conveying path; The pallet conveying device of claim 5, wherein the pallet is pushed up by moving the push-out portion back, moving the movable engagement portion back from the second rotation position to the first rotation position, and moving the second movable engagement portion forward from the fourth rotation position to the third rotation position.

7. 7. The pallet conveying device according to claim 6, further comprising a second rotary guide and a third rotary guide provided on an outer periphery side and an inner periphery side of the arcuate track, respectively, for guiding the lifting of the pallet by the lifting section.

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