Pallet conveying device

Abstract

To provide a pallet conveying device that can convey and return a pallet, with a simple structure.SOLUTION: A pallet conveying device 1 comprises a conveying path 11, a return path 21 arranged beneath the conveying path, a pallet 31 that can move on the conveying path and the return path, on which a work-piece W can be placed, a pulling-up part 41 that pulls up the pallet to the conveying path, and a pushing-out part 51 that pushes out the pallet to a downstream side of the conveying path. The pulling-out part has a movable engaging part 42 that can reciprocate along a circular arc track connecting an upstream end 11A of the conveying path to a downstream end 21B of the return path and can engage with the pallet, which makes the movable engaging part engage with the pallet on the return path and reciprocate to pull up the pallet to the upstream side of the conveying path. The pushing-out part moves from the upstream side of the conveying path to the downstream side thereof to push out the pallet to the downstream side of the conveying path. The pushing-out part is connected to the pulling-up part to be able to move together so that movable engaging part reciprocates by movement of the pushing-out part from the upstream side of the conveying path to the downstream side thereof.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 pallet transport device that includes a transport conveyor, a return conveyor, and a drive motor that drives these conveyors. The pallet transport device can transport pallets without changing the pallets, and circulate them between the transport conveyor and the return conveyor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-120564 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the pallet transport device of Patent Document 1 requires a drive motor for driving the forward conveyor and the return conveyor, so the device is complex and large-scale. When the pallet transport device is installed and used in a factory, it may be relocated depending on changes in the production plan, etc. Therefore, there is a demand for the pallet transport device to have a simpler configuration.

[0005] An object of the present invention is to provide a pallet transport device that can transport and return pallets with a simple configuration. [Means for solving the problem]

[0006] A pallet conveying device according to one aspect of the present invention includes a conveying path, a return path disposed below the conveying path, a pallet that is movable on the conveying path and the return path and on which a workpiece can be placed, a lifting section that lifts the pallet to the upstream side of the conveying path, and a pushing section that pushes the pallet on the conveying path to the downstream side of the conveying path. The lifting section has a movable engagement section that is reciprocable along an arc-shaped track that connects the upstream end of the conveying path and the downstream end of the return path and is engageable with the pallet. With the movable engagement section engaged with the pallet on the return path, the movable engagement section is moved forward along the arc-shaped track to lift the pallet to the upstream side of the conveying path. The pushing section moves from the upstream side to the downstream side of the conveying path to push the pallet on the conveying path to the downstream side of the conveying path. The pushing section and the lifting section are interlockingly connected so that the movable engagement section moves forward along the arc-shaped track as the pushing section moves from the upstream side to the downstream side of the conveying path. Effect of the Invention

[0007] According to the present invention, it is possible to provide a pallet transport device that is capable of transporting and returning pallets with a simple configuration. [Brief description of the drawings]

[0008]

Figure 1

Figure 2A

Figure 2B

Figure 2C

Figure 3A

Figure 3B

Figure 4A

Figure 4B

Figure 4C

Figure 4D

Figure 5A

Figure 5B

Figure 6A

Figure 6B

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

[0025] The lifting portion 61 is connected to be interlocked with the pushing portion 51. When the pushing portion 51 is moved backward, the second movable engaging portion 62 is moved forward from the fourth rotation position L4 to the third rotation position L3. By this forward movement, the pallet 31 is pushed up onto the conveyance path 11. Also, as described above, when the pushing portion 51 is moved backward, the movable engaging portion 42 is moved backward from the second rotation position L2 to the first rotation position L1.

[0026] The slider 53 of the extrusion section 51 has a sub-slider 53A. The sub-slider 53A and the lifting 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 lifting 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 backward to the fourth rotation position L4 due to its own weight. When the slider 53 moves backward and reaches a predetermined position, the sub-slider 53A moves backward together with the slider 53. At this time, as the slider 53 moves backward, the sub-slider 53A pulls the second string-like member S2, so that the arm 62B is pulled in the forward movement direction, and the second movable engagement portion 62 is moved forward. The second string-like member S2 is connected through a pulley, a wheel axle, a pulley, a tensioner, a weight, etc. as appropriate so as to be able to transmit power by tension. Note that the second string-like member S2 can use any material capable of transmitting power, such as a tegus, a belt, a chain, a rope, etc.

[0027] A second rotation guide 82 and a third rotation guide 83 are respectively provided on the outer peripheral side and the inner peripheral side of the arc track A1. The second rotation guide 82 is formed on an arc at a predetermined distance from the arc track A1 on the outer peripheral side. The third rotation guide 83 is formed on an arc at a predetermined distance from the arc track A1 on the inner peripheral 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 pallet 31 that is movable on the conveying path 11 and the return path 21 and on which a workpiece W can be placed, a lifting section 41 that lifts the pallet 31 to the upstream side of the conveying path 11, and a pushing section 51 that pushes the pallet 31 on the conveying path 11 to the downstream side of the conveying path 11. The lifting section 41 has a movable engaging section 42 that can reciprocate along an arcuate track A1 that connects 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 section 41 lifts the pallet 31 to the upstream side of the conveying path 11 by moving the movable engaging section 42 forward along the arcuate track A1 while the movable engaging section 42 is engaged with the pallet 31 on the return path 21. The push-out unit 51 moves from the upstream side to the downstream side of the conveying path 11, thereby pushing out the pallet 31 on the conveying path 11 to the downstream side of the conveying path 11. The push-out unit 51 and the lift-up unit 41 are connected to be interlocked with each other so that the movable engagement unit 42 moves forward along the arc trajectory A1 as the push-out unit 51 moves from the upstream side to the downstream side of the conveying path 11.

[0041] 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.

[0042] In the embodiment, the movable engagement part 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 track A1. The pallet conveying device 1 includes a push-up part 61 that is interlockingly connected to the push-out part 51 and pushes up the pallet 31 onto the conveying path 11. The push-up part 61 has a second movable engagement part 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 a second arcuate track A2 connected to the upstream end 11A of the conveying path 11 and can engage with the pallet 31. The second movable engagement part 62 is returned to the fourth rotational position L4 as the push-out part 51 moves forward. The push-up unit 61, with the second movable engagement unit 62 engaged with the pallet 31 as the push-out unit 51 moves back, moves the second movable engagement unit 62 forward along the second arcuate track A2, thereby pushing up the pallet 31 onto the conveying path 11. The pallet conveying device 1 moves the push-out unit 51 forward to push out the pallet 31 to the downstream side of the conveying path 11, and moves the movable engagement unit 42 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 pallet conveying device 1 moves the push-out unit 51 back, moves the movable engagement unit 42 back from the second rotation position L2 to the first rotation position L1, and moves the second movable engagement unit 62 forward from the fourth rotation position L4 to the third rotation position L3, thereby pushing up the pallet 31.

[0043] 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.

[0044] Furthermore, 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. Therefore, the conveying of the pallet 31 from the upstream side to the downstream side of the conveying path 11 and the returning of the pallet 31 from the upstream side to the downstream side of the return path 21 can be performed with a smaller force.

[0045] In the embodiment, the angle α1, which is the inclination angle of the transport path 11 with respect to the horizontal direction, is smaller than the angle α2, which is the inclination angle of the return path 21 with respect to the horizontal direction. Therefore, in the transport path 11, the workpieces W placed on the pallets 31 can be transported while being prevented 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.

[0046] Furthermore, in another embodiment, the conveying path 11 has a first inclined portion 11C inclined with respect to the horizontal direction, and a second inclined portion 11D downstream of the first inclined portion 11C, the inclination angle of which with respect to the horizontal direction is greater than the inclination angle of the first inclined portion 11C. This makes it possible to prevent the pallet 31 on which the workpiece W is not placed from being conveyed downstream on the conveying path 11. Also, after the workpiece W is placed on the pallet 31, the pallet can be returned to the downstream side of the return path 21 with a smaller force.

[0047] 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.

[0048] Furthermore, in the embodiment, in the conveyance path 11, three rows of roller ways R are 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 conveyance direction. The guide portion 35 is disposed sandwiched between the inner sides in the width direction of adjacent roller ways R. Thereby, on the conveyance path 11, the pallet 31 on which the workpiece W is placed can be stably conveyed.

[0049] Also, in the embodiment, between the downstream end 11B of the conveyance path 11 and the upstream end 21A of the return path 21, a connection path 71 is provided along the other-end-side arc orbit A3 that connects the downstream end 11B of the conveyance path 11 and the upstream end 21A of the return path 21. On the outer peripheral side of the other-end-side arc orbit A3, a first rotation guide 81 for guiding the movement of the pallet 31 in the connection path 71 is installed. Thereby, when moving the pallet 31 on the conveyance path 11 to the return path 21, it can be smoothly moved by the first rotation guide 81.

[0050] Furthermore, in the embodiment, on the outer peripheral side and the inner peripheral side of the arc orbit A1, a second rotation guide 82 and a third rotation guide 83 for guiding the lifting of the pallet 31 by the lifting portion 41 are respectively provided. Thereby, when lifting the pallet 31 on the return path 21 onto the conveyance path 11, it can be smoothly lifted by the second rotation guide 82 and the third rotation guide 83.

[0051] Also, in the embodiment, above the downstream side of the conveyance path 11, a stopper 91 that abuts against the workpiece W placed on the pallet 31 is provided. Thereby, since the pallet 31 on which the workpiece W is placed can be stopped, a plurality of pallets 31 on which the workpiece W is placed can be stored on the conveyance path 11.

[0052] Furthermore, in the embodiment, when the workpiece W abuts against the stopper 91, the front end 36 of the pallet 31 is located on the connecting path 71. As a result, when the workpiece W on the pallet 31 is removed, the pallet 31 quickly moves to the connecting path 71 and the return path 21, so that the pallet 31 can be quickly returned.

[0053] 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.

[0054] 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]

[0055] 1 Pallet transport device 11 Transport path 11A Upstream end of the conveying path 11B Downstream end of conveying path 11C 1st slope 11D 2nd slope part 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 36 Front end of pallet 41 Lifting section 42 Movable engagement part 51 Extrusion section 61 Push-up section 62 Second movable engagement part 71 Connecting Road 81 First Rotary Guide 82 Second Rotary Guide 83 3rd Rotary Guide 91 Stopper A1 Circular orbit A2 Second circular arc orbit A3 Other end side circular orbit L1 First rotation position L2 Second rotation position L3 Third rotation position L4 Fourth rotation position R Rollaway Double work α1, α2, α3, β1 angles

Claims

1. A conveying path; A return path disposed below the conveying path; a pallet that is movable on the conveying path and the return path and on which a workpiece can be placed; 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 in which the push-out section and the lift-up section are interlockingly connected so that the movable engagement section moves forward and backward along the arcuate orbit as the push-out section moves from the upstream side to the downstream side of the conveying path.

2. 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 1, 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.

3. the conveying path is inclined downward from the upstream side to the downstream side of the conveying path, The pallet conveying device according to claim 1 or 2, wherein the return path is inclined downward from the upstream side to the downstream side of the return path.

4. 4. The pallet conveying device according to claim 3, 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.

5. 4. The pallet conveying device of claim 3, wherein the conveying path has a first inclined portion inclined with respect to the horizontal direction, and a second inclined portion downstream of the first inclined portion, the second inclined portion having an inclination angle with respect to the horizontal direction greater than the inclination angle of the first inclined portion.

6. The return path is configured such that a plurality of rollers having rotation axes in a width direction perpendicular to the conveying direction are arranged in the conveying direction, and the roller ways are 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 3 , 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.

7. 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 6 , wherein the guide portions are arranged to be sandwiched between the inner sides of adjacent roller ways in the width direction.

8. a connecting path is provided between the downstream end of the conveying path and the upstream end of the return path, the connecting path being formed 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; 7. A pallet transport device according to claim 6, further comprising a first rotary guide disposed on an outer periphery of the other end side arcuate track for guiding movement of the pallet in the connecting path.

9. 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.

10. 9. The pallet conveying device according to claim 8, further comprising a stopper disposed above the downstream side of the conveying path, the stopper coming into contact with the workpiece placed on the pallet.

11. 11. A pallet conveying device according to claim 10, wherein when the workpiece is in contact with the stopper, the front end of the pallet is positioned on the connecting path.

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