Pallet carrying in / out device

Abstract

To provide a pallet carrying in / out device capable of adjusting positional deviation of a stop position of left and right movable frames with a simple structure.SOLUTION: Each of load carrying in / out mechanisms of a pallet carrying in / out device comprises movable frames 21L, 21R, and a movable frame moving mechanism 5 for advancing / retracting the movable frame with respect to a working area S. The movable frame moving mechanism 5 includes: a pair of stoppers 55A, 55B; a pair of abutting parts 56A, 56B; a main sensor 86 for detecting that the movable frame moving mechanism 5 and a first abutting part abut on the stopper; and a control device 100 for selectively executing a first stop control for stopping a drive mechanism 8 by causing time lag between detection timing of the main sensor and stop timing of the drive mechanism 8, and a second stop control for stopping the drive mechanism without causing time lag.SELECTED DRAWING: Figure 18

Description

[Technical Field]

[0001] The present invention relates to a pallet carrying-in / out device used in a load conveying device used to transport loads between multiple floors in a factory, warehouse, etc., for carrying pallets in and out of a lifting table of a lifting mechanism. [Background technology]

[0002] Conventionally, such a load conveying device includes, as shown in Figure 26, a lifting mechanism 1 having a lifting table 10 that moves up and down between multiple floors (between the first and second floors in Figure 26), and a pallet loading / unloading device 2 that is installed at entrances G1, G2 on each floor of the lifting mechanism 1 and is capable of loading and unloading loaded pallets (hereinafter referred to as "loaded pallets") P1 and unloaded pallets (hereinafter referred to as "empty pallets") P2 to and from the lifting table 10 simultaneously.

[0003] In the following description, the direction facing the entrances G1 and G2 of the lifting mechanism 1, i.e., the direction indicated by arrow X in Figure 26, will be referred to as the front-to-back direction, the width direction of the entrances G1 and G2 of the lifting mechanism 1, i.e., the direction indicated by arrow Y in Figure 26, will be referred to as the left-to-right direction or both-side direction, and the direction perpendicular to the front-to-back direction and left-to-right direction, i.e., the direction indicated by arrow Z in Figure 26, will be referred to as the up-down direction.

[0004] The lifting mechanism 1 has a lifting table 10 provided with two upper and lower transport conveyors 11, 12 for horizontally transporting a loaded pallet P1 and an empty pallet P2 in the forward and backward directions, respectively. The pallet loading / unloading device 2 is comprised of a pair of load loading / unloading mechanisms 200L, 200R, each of which includes a load transport chain conveyor 3, 3 that operates in conjunction with the upper transport conveyor (hereinafter referred to as the "first conveyor") 11 of the lifting table 10 to load and unload the loaded pallet P1, and an empty pallet transport chain conveyor 4, 4 that operates in conjunction with the lower transport conveyor (hereinafter referred to as the "second conveyor") 12 of the lifting table 10 to load and unload the empty pallet P2. The first and second conveyors 11, 12 of the lifting table 10 are, for example, roller conveyors.

[0005] The left and right chain conveyors 3, 3 for transporting loads and the left and right chain conveyors 4, 4 for transporting empty pallets face each other across a spatial area for work (hereinafter referred to as the "work area") S facing the entrances G1, G2 of the lifting mechanism 1, and move forward and backward from both the left and right sides of the work area S. Each load loading / unloading mechanism 200L, 200R incorporates, although not shown, a first conveyor moving mechanism that moves the load transport chain conveyor 3 forward and backward, and a second conveyor moving mechanism that moves the empty pallet transport chain conveyor 4 forward and backward.

[0006] Each load carrying-in / out mechanism 200L, 200R further includes a pallet loading / unloading mechanism 7. Each pallet loading / unloading mechanism 7 includes a pallet support mechanism 70L, 70R that supports a pallet. Each pallet support mechanism 70L, 70R has support claws 71 that support flange portions on the side edges of a loaded pallet P1 and an empty pallet P2. Each support claw 71 is attached to a chain 73, and by simultaneously raising and lowering each support claw 71 using the chain 73, the loaded pallet P1 is loaded / unloaded onto the chain conveyor 3 for transporting loads, and the empty pallet P2 is loaded / unloaded onto the chain conveyor 4 for transporting empty pallets.

[0007] When lifting loaded pallet P1 or empty pallet P2 during loading and unloading of each pallet, the chain conveyors 3, 4 for transporting loads and empty pallets become an obstacle and must be removed from the work area S. For this reason, first and second conveyor movement mechanisms are incorporated into each of the left and right load loading / unloading mechanisms 200L, 200R. However, incorporating two conveyor movement mechanisms into each load loading / unloading mechanism 200L, 200R complicates the structure, leading to an increase in size and cost of the pallet loading / unloading device.

[0008] To solve the above problems, the applicant proposed a pallet loading and unloading device as shown in Patent Document 1. In the pallet loading and unloading device of Patent Document 1, as shown in Fig. 27, movable frames 150L, ​​150R are provided in each load loading and unloading mechanism 200L, 200R, and a chain conveyor 3 for transporting loads and a chain conveyor 4 for transporting empty pallets are provided parallel to each other above and below on the surface of each movable frame 150L, ​​150R facing the working area S. Fig. 27 shows movable frame 150R and a movable frame moving mechanism that moves movable frame 150R, but movable frame 150L has a similar configuration to movable frame 150R. Movable frames 150L, ​​150R are each moved forward and backward by the movable frame moving mechanism.

[0009] The movable frame movement mechanism comprises a pair of parallel link mechanisms 160, 160 arranged along the front-rear direction and a reciprocating mechanism 170. Each parallel link mechanism 160 includes first and second parallel links 161, 162. A drive-side link 161b of the first parallel link 161 and a drive-side link 162b of the second parallel link 162 are connected together by a drive plate 163, and a driven-side link 161a of the first parallel link 161 and a driven-side link 162a of the second parallel link 162 are connected together by a driven plate 164. The reciprocating mechanism 170 is driven by a motor 171 equipped with a speed reducer that can rotate forward and backward, and includes a crank mechanism 172 that converts the rotational motion of the motor 171 into reciprocating linear motion and transmits it to the parallel link mechanisms 160, 160. The crank mechanism 172 is connected to the center of the drive plate 163. The pair of parallel link mechanisms 160 are swung together by the reciprocating mechanism 170, whereby the movable frames 150L, ​​150R move forward and backward in the direction of arrow A1 relative to the working area in an upright position. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2022-88840 A Summary of the Invention [Problem to be solved by the invention]

[0011] In the pallet loading / unloading device described in Patent Document 1, a pair of parallel link mechanisms 160, 160 are used to move the movable frames 150L, ​​150R back and forth relative to the work area S, which makes the structure of the mechanism for moving the movable frames complex, increases the number of parts, and leads to higher costs.

[0012] Furthermore, in order for the chain conveyor 3 for transporting loads and the chain conveyor 4 for transporting empty pallets to stably load and unload pallets, the left and right movable frames 150L, ​​150R on which the chain conveyors 3, 4 are mounted must be stopped parallel to each other at appropriate stopping positions, sandwiching the work area S. For this reason, a pair of parallel link mechanisms 160, 160 is provided at both ends of the width of each movable frame 150L, ​​150R to move the movable frames 150L, ​​150R. However, the pair of parallel link mechanisms 160, 160 must be assembled in symmetrical positions about the center of the width of the movable frames 150L, ​​150R, and both parallel link mechanisms 160, 160 must be synchronized to operate smoothly, which requires a lot of work to assemble and adjust the operations.

[0013] The present invention has been made in response to the above-mentioned problems, and aims to provide a pallet loading / unloading device that has a simple structure and can adjust the positional deviation of the stopping positions of the left and right movable frames. [Means for solving the problem]

[0014] The pallet loading / unloading device of this invention is installed outside the load loading / unloading entrance of a lifting mechanism and loads pallets onto and unloads pallets from a lifting table. The pallet loading / unloading device comprises a pair of load loading / unloading mechanisms arranged opposite each other across a work area facing the load loading / unloading entrance, and each load loading / unloading mechanism includes a fixed frame installed on the floor, a movable frame movably supported on the fixed frame and provided with a chain conveyor on the side facing the work area for loading and unloading pallets onto and from the lifting table, a pallet loading / unloading mechanism for loading and unloading pallets onto the chain conveyor, and a movable frame moving mechanism for moving the movable frame toward and away from the work area along a guide mechanism provided between the movable frame and the fixed frame. The movable frame moving mechanism comprises a drive mechanism that applies a driving force to the movable frame to move the movable frame toward and away from the working area, a pair of stoppers provided on the fixed frame, a pair of abutment portions provided at both ends of the movable frame and arranged opposite the pair of stoppers, a main sensor that detects when a predetermined one of the pair of abutment portions abuts against one of the stoppers, and a control device that can selectively execute a first stop control that stops the drive mechanism by creating a time lag between the detection timing of the main sensor and the stop timing of stopping the drive mechanism, and a second stop control that stops the drive mechanism at the detection timing of the main sensor without creating a time lag.

[0015] During the above-mentioned pallet loading and unloading operation, the movable frame is moved while maintained in an upright position by the movable frame movement mechanism, and the chain conveyor moves forward and backward toward the work area. A pair of stoppers is provided on the fixed frame, and a pair of abutment portions is provided at both ends of the movable frame, facing the pair of stoppers. The movable frame moves forward and stops at a position where the pair of abutment portions abut against the pair of stoppers. The pair of stoppers and the pair of abutment portions are provided at positions that ensure an appropriate stopping position for the movable frame. When the main sensor detects that one abutment portion has abutted against one of the stoppers, the control device selectively executes first stop control or second stop control to stop the drive mechanism.

[0016] The movable frame moves along a guide mechanism between the movable frame and the fixed frame. However, due to wear and tear on the sliding parts of the guide mechanism over time, the movable frame may stop at a position that is displaced from the appropriate stopping position. In the first stop control, a time lag is set between when the main sensor detects that one contacting part has contacted one of the stoppers and when the drive mechanism is stopped. During the time lag, the drive mechanism of the movable frame drive mechanism continues to operate, and the movable frame is subjected to a force in the forward direction. Even if a positional deviation occurs such that the other contacting part is not contacting the other stopper at the detection timing of the main sensor, the movable frame can move forward during the time lag, so the other contacting part will contact the other stopper and the movable frame will stop at the appropriate stopping position. If a time lag is not required, the second stop control stops the drive mechanism at the detection timing of the main sensor without causing a time lag.

[0017] In this way, the positional deviation of the stop positions of the left and right movable frames can be adjusted with a simple structure, without using a movable frame mechanism with a complex structure such as a parallel link mechanism as in the prior art.

[0018] In a preferred embodiment, the drive mechanism includes a motor capable of rotating forward and reverse, and a power transmission mechanism that converts the rotational motion of the motor into reciprocating linear motion and transmits it to the center position in the width direction of the movable frame.

[0019] In a preferred embodiment, the chain conveyor is arranged in two tiers, one above the other, with a first chain conveyor for transporting loaded pallets and a second chain conveyor for transporting empty pallets.

[0020] In a preferred embodiment, the guide mechanism includes a guide portion provided on the fixed frame side and a sliding portion provided at a position opposite the guide portion on the movable frame side, and the contact portion of the sliding portion with the guide portion is made of a synthetic resin plate.

[0021] According to the above embodiment, the contact portion of the sliding portion with the guide portion is made of a synthetic resin plate, so the friction force generated between the sliding portion and the guide portion can be reduced compared to when the sliding portion and the guide portion are made of metal.

[0022] In a preferred embodiment, of the first stop control and the second stop control, the control device executes only the first stop control, which stops the drive mechanism by creating a time lag between the detection timing of the main sensor and the stop timing of stopping the drive mechanism.

[0023] In the case where there is a positional deviation in the stopping position of the movable frame and it is not clear which of the pair of contact portions will contact the contact portion first, the stop control according to this embodiment is executed, and the drive mechanism is stopped with a delay corresponding to the time lag from the detection timing of the main sensor.

[0024] In a preferred embodiment, the control device executes a first stop control to stop the drive mechanism by creating a time lag between the detection timing of the main sensor and the stop timing of the drive mechanism when the other abutment portion abuts against the other stopper at a timing after the detection timing of the main sensor, and executes a second stop control to stop the drive mechanism at the detection timing of the main sensor without creating a time lag when the other abutment portion abuts against the other stopper at a timing before the detection timing of the main sensor.

[0025] Regarding the positional deviation of the stop position of the movable frame, if it is determined that the other contact portion has come into contact with the other stopper at a timing after the detection timing of the main sensor, the first stop control is executed. In the first stop control, even after the main sensor detects that one contact portion has come into contact with one stopper, the drive mechanism is not stopped but continues to be driven for a time corresponding to the time lag, thereby ensuring that the movable frame stops at the appropriate stop position.

[0026] If it is determined that a positional deviation has occurred, such that the other contact portion abuts the other stopper, at a timing prior to the detection timing of the main sensor, a second stop control is executed. In the second stop control, by stopping the drive mechanism at the detection timing of the main sensor, the movable frame is reliably stopped at an appropriate stop position, and it is possible to prevent the drive force of the drive mechanism from acting unnecessarily on the movable frame or the stopper, thereby shortening the time required to correct the positional deviation.

[0027] In a preferred embodiment, the device further includes an auxiliary sensor that detects when the other abutment portion abuts against the other stopper, when the detection timing of the auxiliary sensor is later than the detection timing of the main sensor, the control device executes a first stop control to generate a time lag between the detection timing of the main sensor and the stop timing of the drive mechanism and stop the drive mechanism at the detection timing of the auxiliary sensor; If the detection timing of the auxiliary sensor is earlier than the detection timing of the main sensor, a second stop control is executed to stop the drive mechanism at the detection timing of the main sensor without causing a time lag.

[0028] According to the above embodiment, an auxiliary sensor is provided that detects when the other contact portion contacts the other stopper, so that the drive mechanism can be stopped at the timing of detection by the auxiliary sensor, minimizing the set time lag and shortening the time required to correct the positional misalignment. [Effects of the Invention]

[0029] According to the present invention, even if the stop position of the movable frame becomes displaced from the proper position due to aging caused by wear of the sliding parts, etc., the displacement can be easily corrected. Furthermore, since there is no need to use a pair of parallel link mechanisms as in the conventional example, the structure of the movable frame movement mechanism can be simplified. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a side view of one (left side) load carrying-in / out mechanism of a pallet carrying-in / out device according to an embodiment of the present invention, as viewed from the work area side. FIG. [Figure 2] FIG. 10 is a side view of one of the load carrying-in / out mechanisms as viewed from the opposite side to the work area. [Figure 3] FIG. 10 is a front view of the pallet support mechanism of one of the load loading and unloading mechanisms. [Figure 4] FIG. 2 is a perspective view showing the configuration of a movable frame and a movable frame moving mechanism. [Figure 5] FIG. 2 is an enlarged perspective view showing the configuration of the vicinity of the lower end portion on the rear side of the movable frame. [Figure 6] FIG. 10 is a side view of the rear side of the movable frame when the movable frame is in a retracted position. [Figure 7] FIG. 10 is a side view of the rear side of the movable frame when the movable frame is in a forward position. [Figure 8] FIG. 10 is a plan view of the movable frame when the movable frame is in a retracted position. [Figure 9] FIG. 10 is a plan view of the movable frame when the movable frame is in a forward position. [Figure 10] FIG. 2 is a block diagram illustrating the function of a control device. [Figure 11] 10A and 10B are explanatory diagrams of the forward movement of the movable frame, in which (A) shows the movable frame in a retracted position, (B) shows the movable frame in a displaced position, and (C) shows the movable frame in a forward position. [Figure 12] 10 is a time chart of the forward and backward movement when the first stop control is performed. [Figure 13] 10 is a flowchart showing a preparation process. [Figure 14] 10 is a flowchart showing a processing procedure of a first stop control. [Figure 15] 10A and 10B are diagrams illustrating another example of a state in which the movable frame is misaligned. [Figure 16] 10 is a flowchart showing a processing procedure of a second stop control. [Figure 17] 10A and 10B are diagrams showing a state in which the movable frame is displaced when in the retracted position. [Figure 18] FIG. 10 is a block diagram illustrating functions of a control device according to another embodiment. [Figure 19] 10 is a flowchart showing a processing procedure of a first stop control according to another embodiment. [Figure 20] 10A and 10B are explanatory diagrams of the forward movement of the movable frame, in which (A) shows the movable frame in a retracted position, (B) shows the movable frame in a displaced position, and (C) shows the movable frame in a forward position. [Figure 21]10A and 10B are front views for explaining the operation of carrying out a load from the pallet carrying-in / out device to the lift table. [Figure 22] 10A and 10B are front views for explaining the operation of carrying out a load from the pallet carrying-in / out device to the lift table. [Figure 23] FIG. 10 is a front view illustrating the operation of transporting a load from the pallet transport device to the lift table. [Figure 24] 10A and 10B are front views for explaining the operation of carrying in a load from the lifting table to the pallet carry-in / out device. [Figure 25] 10A and 10B are front views for explaining the operation of carrying in a load from the lifting table to the pallet carry-in / out device. [Figure 26] 1 is a perspective view showing a schematic configuration of a load transport device using a pallet. [Figure 27] FIG. 1 is an explanatory diagram of a conventional technique. DETAILED DESCRIPTION OF THE INVENTION

[0031] (Overall configuration of the load transport device) The load conveying device places loads on pallets and conveys the loads in both horizontal and vertical directions, and the overall configuration of the device is generally the same as that shown in Figure 26. The load conveying device shown in Figure 26 includes a lifting mechanism 1 having a lifting table 10 that moves up and down between multiple floors, and a pallet carry-in / out device 2 installed near the outside of entrances G1, G2 on each floor of the lifting mechanism 1. The pallet carry-in / out device 2 is capable of simultaneously carrying in and out loaded pallets P1 and empty pallets P2 to and from the lifting table 10 of the lifting mechanism 1. While Figure 26 shows a two-story lifting mechanism 1, the load conveying device of the present invention can also be implemented with a lifting mechanism 1 that is three or more stories tall.

[0032] The lifting table 10 is raised and lowered by a lifting drive device (not shown). The operation of the lifting drive device is controlled so that the lifting table 10 stops at the positions of entrances G1 and G2 on each floor. The lifting table 10 is provided with two conveyors, one above the other: a first conveyor 11 for horizontally transporting loaded pallets P1 between the lifting table 10 and the pallet loading / unloading device 2 on each floor, and a second conveyor 12 for horizontally transporting empty pallets P2. The second conveyor 12 is not shown in Figure 26, but is indicated by a dotted leader line.

[0033] The first and second conveyors 11 and 12 are roller conveyors. A conveyor drive device (not shown) drives each conveyor 11 and 12 individually, and each conveyor is driven to rotate in both forward and reverse directions. Note that instead of roller conveyors, chain conveyors can also be used as the first and second conveyors 11 and 12.

[0034] The pallet used in the pallet loading / unloading device 2 is made of metal and has vertical side walls 16, 16 on both side edges of a horizontal loading surface 15, and an outwardly facing horizontal flange 17 bent at the upper edge of each side wall 16. When the loaded pallet P1 or empty pallet P2 is raised or lowered, the front and rear positions of the left and right flanges 17 are supported by support claws 71, 71 of pallet support mechanisms 70L, 70R provided on the left and right load loading / unloading mechanisms 200L, 200R.

[0035] (Configuration of pallet loading / unloading device 2) The pallet loading / unloading device 2 installed on each floor is composed of left and right load loading / unloading mechanisms 200L, 200R. The load loading / unloading mechanisms 200L, 200R are arranged opposite each other on both sides of the work area S facing the entrances G1, G2 of the lifting mechanism 1 on each floor. The symbol "200L" represents the load loading / unloading mechanism located on the left side as one faces the entrances G1, G2, and the symbol "200R" represents the load loading / unloading mechanism located on the right side as one faces the entrances G1, G2. Hereinafter, the letter "L" will be used as necessary to indicate the components related to the left load loading / unloading mechanism 200L, and the letter "R" will be used as necessary to indicate the components related to the right load loading / unloading mechanism 200R.

[0036] In the following explanation, unless otherwise specified, the direction in which loaded pallets P1 and empty pallets P2 are transported in Fig. 1, i.e., the direction indicated by arrow X, is referred to as the front-to-rear direction X of the pallet loading / unloading device 2, with the side closer to the lifting mechanism 1 referred to as the front side and the side farther from the lifting mechanism 1 referred to as the rear side. The direction perpendicular to the front-to-rear direction on the same plane and in which the load loading / unloading mechanisms 200L, 200R are arranged with the working area S between them, i.e., the direction indicated by arrow Y in Fig. 26, is referred to as the left-to-right direction Y or both-side direction Y, and the direction perpendicular to the front-to-rear direction and the left-to-right direction, and the direction indicated by arrow Z in Fig. 3, is referred to as the up-down direction Z.

[0037] (Configuration of the load loading / unloading mechanism 200R, 200L) 1 to 4 show the configuration of the left load carrying-in / out mechanism 200L of the left and right load carrying-in / out mechanisms 200L, 200R. The configuration of the left load carrying-in / out mechanism 200L will be mainly described below, but the configuration of the right load carrying-in / out mechanism 200R is similar to this, so illustrations and descriptions thereof will be omitted.

[0038] The load carrying-in / out mechanism 200L has a fixed frame 20L installed on the floor surface, a movable frame 21L that moves as a whole, a pallet loading / unloading mechanism 7, and a movable frame moving mechanism 5.

[0039] (Fixed frame 20L) The fixed frame 20L comprises a rectangular lower frame 24 supported on the floor, a rectangular upper frame 25 located at a predetermined height above the lower frame 24, and an intermediate frame 27 located between the lower frame 24 and the upper frame 25. The lower frame 24 and the upper frame 25 are connected by a vertical frame 26, and the intermediate frame 27 is supported by the vertical frame 26. The intermediate frame 27 is provided at a height position that does not interfere with the forward and backward movement of the movable frame 21L.

[0040] (movable frame 21L) The movable frame 21L is movably supported in an upright position on the lower frame 24 of the fixed frame 20L by a movable frame moving mechanism 5 shown in Figures 4 to 6. The movable frame moving mechanism 5 also moves the movable frame 21L forward and backward relative to the working area S while maintaining the upright position. The configuration of the movable frame moving mechanism 5 will be described in detail later.

[0041] On the surface 21d of the movable frame 21L facing the working area S (hereinafter referred to as the "inner surface 21d", and the surface opposite the inner surface 21d referred to as the "outer surface 21e"), there are provided two parallel tiers, one above the other: a chain conveyor 3 for transporting cargo in conjunction with a first conveyor 11 on the upper level of the lifting table 10 to transport loaded pallets P1 onto and off the lifting table 10; and a chain conveyor 4 for transporting empty pallets in conjunction with a second conveyor 12 on the lower level of the lifting table 10 to transport empty pallets P2 onto and off the lifting table 10.

[0042] The chain conveyors 3, 4 for transporting loads and empty pallets are located at the same height as the chain conveyors 3, 4 for transporting loads and empty pallets of the movable frame 21L of the other load loading / unloading mechanism 200L. The chain conveyors 3, 3 for transporting loads of the left and right movable frames 21L, 21R work together to transport loaded pallets P1, and the chain conveyors 4, 4 for transporting empty pallets work together to transport empty pallets P2. The loaded pallet P1 and empty pallet P2 are supported from below by outward flanges 17 on both sides of a pair of chain conveyors 3, 3 for transporting loads and a pair of chain conveyors 4, 4 for transporting empty pallets, and are transported horizontally between each chain conveyor 3, 4 and the first and second conveyors 11, 12 of the lifting table 10.

[0043] As shown in FIG. 4, the movable frame 21L in the illustrated example is formed by bending a metal plate material, and includes a side plate 21a facing the working area S, and a front plate 21b and a rear plate 21c that are perpendicular to the side plate 21a and face each other in the front-rear direction. Furthermore, as shown in FIG. 5, the movable frame 21L also includes support plates 54a that are provided at the lower ends of the front plate 21b and the rear plate 21c and have lengths substantially equal to the widths of the front plate 21b and the rear plate 21c, and a connecting plate 59 that connects the support plates 54a. The support plate 54a constitutes a guide mechanism 50, which will be described later. Second side plate portions 21f, which are perpendicular to the front plate 21b and the rear plate 21c and parallel to the side plate 21a, are formed on the rear end sides of the front plate 21b and the rear plate 21c, respectively. The side plate portion 21a faces the side plate portion 21a of the other movable frame 21L across the working area S. On the inner surface of each side plate portion 21a, horizontally long chain conveyor boxes 22, 23 are attached horizontally and parallel to each other in two upper and lower tiers. The upper tier chain conveyor box 22 houses an endless first conveyor chain 30 that constitutes the chain conveyor 3 for transporting loads, and the lower tier chain conveyor box 23 houses an endless second conveyor chain 40 that constitutes the chain conveyor 4 for transporting empty pallets, with only the horizontally running upper edge portion of each housed exposed upward.

[0044] (Chain conveyor 3, 4) The chain conveyor 3 for transporting loads is located at a height corresponding to the position of the first conveyor 11 when the lifting table 10 is stopped. In addition, the chain conveyor 4 for transporting empty pallets is located at a height corresponding to the position of the second conveyor 12 when the lifting table 10 is stopped. In this embodiment, the first and second conveyors 11, 12 of the lifting table 10 are configured as roller conveyors, so the height of the upper surfaces of the conveyors 11, 12 when the lifting table 10 is stopped matches the height of the loading surface 15 of the pallet supported by the chain conveyors 3, 4.

[0045] (Chain Conveyor 3) 1 and 2, the chain conveyor 3 for transporting loads is made up of a first conveyor chain 30 and a wheel group consisting of a plurality of (five in this embodiment) sprocket wheels 32 to 36. The first conveyor chain 30 is endlessly stretched between the sprocket wheels 32 to 36 so that the upper side 30a, which supports and transports the load pallet P1, runs horizontally in both forward and reverse directions.

[0046] Of this wheel group, sprocket wheels 32, 33 located at both ends are positioned at the same height and mesh with the first conveyor chain 30. Sprocket wheels 3, 4 located in the center of the middle section are positioned lower than the sprocket wheels 32, 33 at both ends and mesh with the bottom side portion 30b that causes the first conveyor chain 30 to return. Two sprocket wheels 35, 36 are located near both sides of the central sprocket wheels 3, 4, which cause the bottom side portion 30b of the first conveyor chain 30 to detour towards the sprocket wheels 3, 4.

[0047] The sprocket wheels 3, 4 in the central position are driven by a motor 37 that can rotate in both forward and reverse directions. The forward and reverse rotation of the sprocket wheels 3, 4 causes the upper side 30a of the first conveyor chain 30 to run in both forward and reverse directions. A highly efficient, general-purpose AC motor with a reducer is used for the motor 37. The motor 37 is attached to the outer surface 21d of the side plate portion 21a of the movable frame 21L, and the sprocket wheels 3, 4 in the central position are attached to the output shaft of the reducer.

[0048] (Chain Conveyor 4) The chain conveyor 4 for transporting empty pallets is made up of a second conveyor chain 40 and multiple (two in this embodiment) sprocket wheels 41, 42. The second conveyor chain 40 is stretched endlessly between the sprocket wheels 41, 42 so that the upper edge 40a, which supports and transports the empty pallet P2, runs horizontally in both forward and reverse directions. The sprocket wheels 41, 42 are located at the same height and mesh with the second conveyor chain 40.

[0049] The movable frame 21L is provided with a power transmission mechanism 6 that transmits the driving force of the motor 37 to the second conveyor chain 40. The power transmission mechanism 6 in this embodiment includes a first power transmission sprocket wheel 62 located on the same shaft 61 as the sprocket wheel 35, a second power transmission sprocket wheel 64 located on the same shaft 63 as one of the sprocket wheels 41 that meshes with the second conveyor chain 40, a power transmission chain 65 that is stretched between the first power transmission sprocket wheel 62 and the second power transmission sprocket wheel 64, and a sprocket wheel 66 that meshes with the chain 65 to apply tension.

[0050] The power transmission mechanism 6 transmits driving force to the second conveyor chain 40 so that the second conveyor chain 40 runs in the opposite direction to the first conveyor chain 30. The sprocket wheel 35 that meshes with the first conveyor chain 30 rotates in the opposite direction to the sprocket wheels 3 and 4, and this rotational motion is transmitted by a power transmission chain 65 to the sprocket wheel 41 that meshes with the second conveyor chain 40, causing the second conveyor chain 40 to run in the opposite direction to the first conveyor chain 30 in synchronization with it.

[0051] The power transmission mechanism 6 is not limited to that of this embodiment, as long as it transmits power to the second conveyor chain 40 so that the second conveyor chain 40 runs in the opposite direction to the first conveyor chain 30. Furthermore, in the above embodiment, the chain conveyor 3 for transporting loads is driven by a motor 37 and the driving force is transmitted to the chain conveyor 4 for transporting empty pallets, but the chain conveyor 4 for transporting empty pallets may also be driven by a motor and the driving force transmitted to the chain conveyor 3 for transporting loads.

[0052] (Pallet loading / unloading mechanism 7) 1 to 3, the load carrying-in / out mechanism 200L is equipped with a pallet loading / unloading mechanism 7 for loading and unloading a loaded pallet P1 onto the chain conveyor 3 for transporting loads, and for loading and unloading an empty pallet P2 onto the chain conveyors 4, 4 for transporting empty pallets. The load carrying-in / out mechanism 200L on the left side (not shown) is also equipped with a similar pallet loading / unloading mechanism 7, and both pallet loading / unloading mechanisms 7, 7 work together to load and unload the loaded pallet P1 and empty pallet P2.

[0053] Each pallet loading / unloading mechanism 7 is equipped with pallet support mechanisms 70L, 70R for supporting the left and right flanges 17 of the loaded pallet P1 and empty pallet P2 at the front and rear positions. The pallet support mechanisms 70L, 70R of the left and right load carrying-in / out mechanisms 200L, 200R move up and down synchronously at positions on both sides of the work area S.

[0054] The configuration of one of the pallet support mechanisms 70L will be described below. The pallet support mechanism 70L includes a pair of support claws 71, 71 that can be engaged with and disengaged from the flanges 17 of the loaded pallet P1 and the empty pallet P2 at the front and rear, lifting guides 72, 72 for each support claw 71 that are provided on the fixed frame 20L, and chains 73, 73 that move each support claw 71 up and down along each lifting guide 72. Each chain 73 is hung between upper and lower sprocket wheels 74, 74 that are provided on the lower frame 24 and upper frame 25 of the fixed frame 20L, and runs in the vertical direction.

[0055] The support claws 71 are attached to the lower end of a slide plate 75. The slide plate 75 is attached to a chain 73 via a shock-absorbing spring 77. The support claws 71 move up and down by rotating upper and lower sprocket wheels 74, 74 to run the chain 73. The slide plate 75 is provided with a plurality of guide rollers 76 that roll along an elevation guide 72, and operating pieces (not shown) that operate limit switches (not shown) located at the elevation stop positions of each support claw 71.

[0056] A rotating shaft 91 is disposed on the upper frame 25 of the fixed frame 20L, and a sprocket wheel 74 is attached to the rotating shaft 91. The rotating shaft 91 is driven in either forward or reverse direction by a transmission mechanism 9 made up of a motor 90, sprocket wheel, chain, etc. As the sprocket wheel 74 rotates, the support claws 71 move up and down simultaneously along the lifting guides 72. As the support claws 71 rise, they engage with the flanges 17 of the loaded pallet P1 and empty pallet P2, supporting the pallets P1 and P2.

[0057] (Movable frame movement mechanism 5) The movable frame moving mechanism 5 moves the movable frame 21L forward and backward along a guide mechanism 50 provided between the movable frame 21L and the lower frame 24 of the fixed frame 20L. During the forward and backward movement, the movable frames 21R, 21L maintain an upright posture, and when the movable frames 21R, 21L advance toward the working area S and stop, the inner surfaces 21d of the movable frames 21R, 21L become parallel to each other.

[0058] The advancing and retreating movements refer to forward and backward movements, and the movable frame 21L moves forward or backward along the left-right direction Y. The left-right direction Y coincides with the advancing and retreating direction of the movable frames 21L, 21R (the direction of arrow A1 in FIG. 4), and the direction toward the working area S along the left-right direction Y is called the forward direction or inward direction, and the direction away from the working area S along the left-right direction Y is called the retreating direction or outward direction.

[0059] 2 and 4 to 10, the movable frame moving mechanism 5 includes a drive mechanism 8 that applies a driving force to the movable frame 21L to move the movable frame 21L toward and away from the working area S, a pair of stoppers 55A, 55B provided on the fixed frame 20L, a pair of contact portions 56A, 56B provided on both sides of the movable frame 21L in the front-rear direction X and arranged opposite the pair of stoppers 55A, 55B, a main sensor 86 that detects when a selected (rear) contact portion 56B of the pair of contact portions 56A, 56B contacts the rear stopper 55B, a backward detection sensor 87 that detects when the movable frame 21L reaches the backward position, and a control device 100 (FIG. 10) that controls the start and stop operations of the drive mechanism 8. The movable frame moving mechanism 5 also includes a power supply circuit 113 connected to the control device 100 and driving the motor 80 of the drive mechanism 8.

[0060] (Guide mechanism 50) As shown in FIG. 5, the guide mechanism 50 includes a guide portion 51 provided on the fixed frame 20L side and a sliding portion 53 provided at a position facing the guide portion 51 on the movable frame 21L side. The guide portion 51 is fixed to the lower frame 24 of the fixed frame 20L and is provided at both ends of the movable frame 21L in the front-rear direction X. The guide portion 51 is formed by fixing a first band-shaped plate 52a, a second band-shaped plate 52b, and a spacer 52c together to the lower frame 24 with bolts (not shown). The second band-shaped plate 52b is disposed above the first band-shaped plate 52a and faces the first band-shaped plate 52a with a gap therebetween provided by the spacer 52c. The spacer 52c, the first band-shaped plate 52a, and the second band-shaped plate 52b are arranged so that their respective ends on one side in the width direction (front-rear direction X) are aligned, and the second band-shaped plate 52b has a shorter widthwise length than the first band-shaped plate 52a. Therefore, a portion of the upper surface of the first band-shaped plate 52a is open. The space surrounded by the spacer 52c, the first band-shaped plate 52a, and the second band-shaped plate 52b forms the recessed groove 51a.

[0061] The sliding portion 53 includes a support plate 54a provided at the lower end of the front plate 21b and the rear plate 21c of the movable frame 21L, respectively, and a synthetic resin plate 54b attached to the lower surface of the support plate 54a with an adhesive or the like. The synthetic resin plate 54b is provided over the entire length of the support plate 54a. The outer end of the synthetic resin plate 54b in the width direction (front-rear direction X) protrudes outward beyond the width direction end of the support plate 54a.

[0062] The outer edge of the synthetic resin plate 54b fits into the recessed groove 51a, and the lower surface of the synthetic resin plate 54b is in surface contact with the upper surface of the first band-shaped plate 52a. When the movable frame 21L moves back and forth, the synthetic resin plate 54b slides on the upper surface of the first band-shaped plate 52a in the moving direction Y while being guided by the recessed groove 51a. The sliding of the synthetic resin plate 54b of the sliding portion 53 against the guide portion 51 reduces the frictional force compared to when the support plate 54a slides directly on the guide portion 51.

[0063] (Drive mechanism 8) As shown in FIG. 4, the drive mechanism 8 includes a motor 80 with a reversible speed reducer as a drive source, and a crank mechanism 81 (power transmission mechanism) that converts the rotational motion of the motor 80 into reciprocating linear motion and transmits it to a central position in the width direction of the movable frame 21L (the front-rear direction X of the pallet loading / unloading device 2). The motor 80 is fixed to the lower frame 24 of the fixed frame 20L. The crank mechanism 81 is made up of two cranks 82, 83 connected by a pin. An output shaft 84 of the motor 80 is connected to one end of one of the cranks 83 in the longitudinal direction, and one end of the other crank 82 in the longitudinal direction is connected to the other end by a pin. The other end of the other crank 82 is rotatably connected by a pin to a protruding plate 85 provided at a central position in the front-rear direction X of the connecting plate 59 of the movable frame 21L.

[0064] When the motor 80 rotates in the forward or reverse direction, the movable frame 21L moves forward or backward relative to the work area S along the guide mechanism 50.

[0065] (Stopper 55A, 55B) As shown in FIGS. 4 and 5 , the front and rear stoppers 55A, 55B are provided via a plate 52d on the upper surface of the second band-shaped plate 52b of the guide portion 51 fixed to the lower frame 24 of the fixed frame 20L. The front and rear stoppers 55A, 55B each have a contact surface 55a against which the front and rear contact portions 56A, 56B come into contact, and the contact surface 55a is provided along a plane perpendicular to the left-right direction Y. In this embodiment, the stoppers 55A, 55B are L-shaped members formed by bending a band-shaped member to have a substantially L-shaped cross section, and their side edges are fixed to a plate 52d on the second band-shaped plate 52b of the lower frame 24. The contact surface 55a is one surface of one half of the L shape.

[0066] (Abutting parts 56A, 56B) As shown in FIGS. 4 and 5 , the front and rear contact portions 56A, 56B are provided on the undersides of the outer surfaces of the front plate portion 21b and the rear plate portion 21c of the movable frame 21L, respectively. Each of the front and rear contact portions 56A, 56B includes a bolt 57 and a mounting member 58 for mounting the bolt 57 to the front plate portion 21b and the rear plate portion 21c. The mounting member 58 has an L-shaped cross section, and one piece 58a of the L-shape faces the contact surfaces 55a of the stoppers 55A, 55B. The bolt 57 is inserted into a through-hole provided in the one piece 58a and fixed with a nut 57a. The length of the bolt 57 protruding from the one piece 58a toward the stoppers 55A, 55B can be adjusted with the nut 57a.

[0067] When the movable frame 21L is moved forward by the drive mechanism 8 and the tip of the bolt 57 abuts against the abutment surface 55a of the stopper 55A, 55B, the movable frame 21L stops without moving further forward. That is, the stop position (forward position) of the movable frame 21L after moving forward is the position where the front and rear abutment portions 56A, 56B abut against the front and rear stopper 55A, 55B, respectively. When the movable frame 21L is in the forward position, loaded pallets P1 and empty pallets P2 can be transported in and out by the chain conveyors 3, 4 for transporting loads and empty pallets provided on the movable frame 21L. In the forward position, the faces 21d of the movable frames 21L, 21R facing the working area S are parallel to each other and to a plane including the front-rear direction X and the up-down direction Z. The forward position is adjusted by the protruding length of the bolt 57.

[0068] (Main sensor 86) The main sensor 86 detects when the rear contact portion 56B contacts the rear stopper 55B. As shown in FIGS. 1, 2, 8, and 9, the main sensor 86 is attached via an attachment member to the underside of the intermediate frame 27 of the fixed frame 20L at a predetermined front or rear side along the front-rear direction. In this embodiment, the main sensor 86 is provided on the rear side. The main sensor 86 is, for example, a photoelectric sensor including a light-emitting portion 86a that emits light and a light-receiving portion 86b that receives the light emitted from the light-emitting portion 86a. The light-emitting portion 86a and the light-receiving portion 86b are provided on the underside of the intermediate frame 27 at an interval along the front-rear direction X.

[0069] A light-shielding plate 88B is provided on the upper side of the outer surface of the rear plate 21c of the movable frame 21L. As shown in FIG. 4, the light-shielding plate 88B includes a light-shielding piece 88a formed by bending one longitudinal end of a strip-shaped member upward and an attachment piece 88b formed by bending the other longitudinal end downward. The attachment piece 88b of the light-shielding plate 88B is attached to the rear plate 21c. As shown in FIGS. 7 and 9, the light-shielding plate 88B is attached to the rear plate 21c so that the light-shielding piece 88a is positioned between the light-emitting unit 86a and the light-receiving unit 86b when the rear abutting portion 56B of the movable frame 21L abuts against the rear stopper 55B (FIG. 9). The light-shielding piece 88a of the light-shielding plate 88B blocks light from being received by the light-receiving unit 86b, and the light-receiving unit 86b outputs a detection signal indicating that no light is being received, i.e., the detection signal is turned on.

[0070] In this embodiment, the main sensor 86 is provided on the rear side, but it may also be provided on the front side and detect when the front contact portion 56A contacts the front stopper 55A. In addition, in this embodiment, a photoelectric sensor including a light-emitting portion 86a and a light-receiving portion 86b is used as the sensor, but a reflective photoelectric sensor may also be used. A reflective photoelectric sensor integrally includes the light-emitting portion 86a and the light-receiving portion 86b, and light emitted from the light-emitting portion 86a of the photoelectric sensor is reflected by the light-shielding plate 88 and received by the light-receiving portion 86b of the photoelectric sensor, which then outputs an ON detection signal. In addition, a proximity sensor or the like may be used instead of the photoelectric sensor.

[0071] (Backward detection sensor 87) The backward movement detection sensor 87 detects that the movable frame 21L is in a position (backward position) where it stops after moving backward. The backward position of the movable frame 21L is set to a position where the movable frame 21L does not interfere with the lifting and lowering operation of the loaded pallet P1 and empty pallet P2 by the pallet support mechanisms 70L, 70R.

[0072] The reverse detection sensor 87 is attached to the underside of the intermediate frame 27 of the fixed frame 20L via an attachment member on the opposite side of the main sensor 86 in the front-rear direction. In this embodiment, the reverse detection sensor 87 is provided on the front side. The reverse detection sensor 87 is configured, for example, by a photoelectric sensor including a light-emitting portion 86a and a light-receiving portion 86b. Since the configuration of the reverse detection sensor 87 is the same as that of the main sensor 86, detailed description of the reverse detection sensor 87 will be omitted. The reverse detection sensor 87 outputs a detection signal when light is blocked by a light-blocking piece 88a of a light-blocking plate 88A provided on the upper side of the outer surface of the front plate 21b of the movable frame 21L. The light-blocking plate 88A includes a light-blocking piece 88a formed by bending one longitudinal end of a strip-shaped member upward and an attachment piece 88b formed by bending the other longitudinal end downward. The attachment piece 88b of the light-blocking plate 88B is attached to the front plate 21b.

[0073] 8 and 9, in this embodiment, the reverse detection sensor 87 is disposed on the same straight line as the main sensor 86 in the front-rear direction X. The light-shielding piece 88a of the light-shielding plate 88A corresponding to the reverse detection sensor 87 is located to the right (in the forward direction) in the left-right direction of the light-shielding piece 88a of the light-shielding plate 88B corresponding to the main sensor 86, and the light-shielding plate 88A is attached to the front plate 21b so that the light-shielding piece 88a is located between the light-emitting portion 86a and the light-receiving portion 86b when the movable frame 21L is in the reverse position (FIG. 8).

[0074] (reverse limiting mechanism 130) The pair of rearward limiting mechanisms 130 are intended to prevent the movable frame 21L from moving further rearward than the rearward position due to a malfunction of the drive mechanism 8, etc. The pair of rearward limiting mechanisms 130 are provided on the rearward side of the underside of the intermediate frame 27 along the front-to-rear direction, at positions corresponding to the front plate portion 21b and the rear plate portion 21c of the movable frame 21L. Each rearward limiting mechanism 130 includes a bolt 131 and an attachment member 132 for attaching the bolt 131 to the underside of the intermediate frame 27. When the movable frame 21L is in the rearward position, the bolt 131 abuts against the second side plate portion 21f of the movable frame 21L.

[0075] (Power supply circuit 113) The power supply circuit 113 (FIG. 10) is connected to the control device 100, the motor 80 of the drive mechanism 8, and the power source 112, and serves to supply or stop power from the power source 112 to the motor 80 of the drive mechanism 8. When the power supply circuit 113 receives from the control device 100 a forward movement start signal indicating the timing to start a forward movement or a backward movement start signal indicating the timing to start a backward movement, the power supply circuit 113 supplies power to the motor 80 so that the motor 80 rotates forward or backward in accordance with this signal. Furthermore, when the power supply circuit 113 receives a stop signal from the control device 100, it stops supplying power to the motor 80.

[0076] (Control device 100) The control device 100 controls the operation of the drive mechanism 8, thereby controlling the advance / retreat movement of the movable frame 21L. The control device 100 can be configured as a general-purpose computer, and includes, as its hardware configuration, a processor such as a CPU or GPU, a main memory device such as a DRAM or SRAM (not shown), and an auxiliary memory device 101 such as an HDD or SSD. The auxiliary memory device 101 stores a set time lag and also stores various control programs for operating the control device 100, including an advance / retreat start control program and a stop control program (described below) for performing first stop control and second stop control.

[0077] The control device 100 includes, as functional blocks, a selection program acquisition unit 102, a time lag acquisition unit 103, a main sensor detection signal acquisition unit 104, a clock count unit 105, a comparison unit 106, a stop signal output unit 107, a reverse detection sensor detection signal acquisition unit 108, a forward start signal output unit 109, and a reverse start signal output unit 110. In this embodiment, each of these units is realized in software by the processor of the control device 100 reading a control program into the main storage device and executing it.

[0078] (Forward movement of the movable frame 21L) Next, the forward movement of the movable frame 21L will be described with reference to FIG. 11. The forward movement is the movement of the movable frame 21L, which is in the retracted position, to start moving forward and stop at the forward position so that a loaded pallet P1 or an empty pallet P2 can be transported in or out using the chain conveyors 3, 4 for transporting loaded and empty pallets provided on the movable frame 21L. Note that FIG. 11 and FIGS. 15, 17, and 19, which will be described later, are diagrams for explaining the forward and backward movement and do not represent the actual shapes, positions, or sizes of the main sensor 86, movable frame 21L, contact portions 56A, 56B, stoppers 55A, 55B, and light shielding plates 88A, 88B shown in the figures. FIG. 12 is a time chart of the forward and backward movement when the first stop control is performed.

[0079] (Start of forward movement) The forward movement start signal output unit 109 of the control device 100 executes transmission of the forward movement start signal to the power supply circuit 113. In other words, the advance / retract start program causes the control device 100 to execute transmission of the forward movement start signal. The power supply circuit 113 supplies power to the motor 80 of the drive mechanism 8 for rotation in the forward direction. The movable frames 21L, 21R receive the driving force of the motor 80 and begin moving forward toward the work area S. The timing of generating the forward movement start signal is controlled by the advance / retract start program stored in the control device 100, and is the timing after the pallet support mechanisms 70L, 70R have lifted or lowered the loaded pallet P1 or the empty pallet P2.

[0080] (Stop forward movement) Regarding the forward movement of the movable frame 21L (similarly to the movable frame 21R), it is desirable that the surface 21d of the movable frame 21L facing the working area S move while maintaining parallelism with a plane including the forward-backward direction X and the up-down direction (see FIGS. 11A and 11C). However, due to aging or other factors, the movable frame 21L may shift from its forward position, which is an appropriate stopping position, and the surface 21d of the movable frame 21L facing the working area S may shift diagonally relative to the forward-backward direction X in a plan view (see, for example, FIG. 11B). For this reason, the control device 100 selectively performs first stop control or second stop control to correct the positional shift when the movable frame 21L is shifted. The positional shift refers to the surface 21d of the movable frame 21L facing the working area S shifting diagonally in a plan view, rather than being parallel to the forward-backward direction X.

[0081] The control device 100 stops the moving forward movable frame 21L at an appropriate position by controlling the stop timing of the drive mechanism 8. The control device 100 selectively executes a first stop control that stops the motor 80 of the drive mechanism 8 by creating a time lag between the detection timing of the main sensor 86 and the stop timing of the drive mechanism 8, and a second stop control that stops the motor 80 at the detection timing of the main sensor 86 without creating a time lag. The first stop control and the second stop control will be described in detail later.

[0082] The following describes the process in which the control device 100 sends a stop signal to the power supply circuit 113. Figures 13 and 14 are flowcharts showing the processing procedure for stopping the forward movement of the movable frame 21L according to this embodiment, and the functional blocks of the control device 100 execute steps S1 to S3 in Figure 13 and S11 to S14 in Figure 14. That is, a stop control program causes the control device 100 to execute steps S1 to S3 and S11 to S14.

[0083] 13 is a flowchart showing the processing procedure of the preparation step. The preparation step is carried out in advance before the movable frame 21L starts moving forward, preferably before operating the pallet carry-in / out device 2. In step S1 (program selection and acquisition step), the selected program acquisition unit 102 acquires selection information input by the operator from the input unit 111, which is composed of a touch panel, keyboard, monitor, etc., i.e., information on whether the first stop control or the second stop control has been selected, and stores this information in the auxiliary storage device 101.

[0084] If the worker recognizes in advance that a misalignment (see FIG. 11B) has occurred in which the front contact portion 56A has come into contact with the front stopper 55A at a timing after the detection timing of the main sensor 86 (i.e., the timing when the rear contact portion 56B comes into contact with the rear stopper 55B), the worker selects the first stop control. If the worker recognizes in advance that a misalignment (see FIG. 15) has occurred in which the front contact portion 56A has come into contact with the front stopper 55A at a timing before the detection timing of the main sensor 86, the worker selects the second stop control. If the worker does not recognize whether the timing when the rear contact portion 56B comes into contact with the rear stopper 55B is a misalignment before or after the timing when the front contact portion 56A comes into contact with the front stopper 55A (i.e., either the misalignment shown in FIG. 11B or FIG. 15), the worker selects the first stop control.

[0085] If the first stop control is selected in step S1, in step S2 (time lag acquisition step), the time lag acquisition unit 103 acquires a time lag input by the operator via the input unit 111. The time lag refers to the time from when the control device 100 receives a detection signal indicating that the rear contact portion 56B has contacted the rear stopper 55B until when it outputs a stop signal. The operator confirms or predicts in advance the time required from when the rear contact portion 56B contacts the rear stopper 55B until when the front contact portion 56A contacts the front stopper 55A, and sets the time lag to a time slightly longer than this time (for example, a value of 1 second or less). In step S3, the time lag acquisition unit 103 stores the acquired time lag in the auxiliary storage device 101. Then, the preparation process ends.

[0086] If the second stop control is selected in step S1, step S3 is not performed and the preparation process ends.

[0087] (First stop control) Next, the processing procedure of the first stop control will be described using the flowchart shown in Fig. 14. In the following explanation, an example will be given in which a positional deviation occurs (Fig. 11(B)) such that the front contact portion 56A contacts the front stopper 55A at a timing after the detection timing of the main sensor 86 (i.e., the timing at which the rear contact portion 56B contacts the rear stopper 55B). At the start of the processing procedure of the first stop control, the motor 80 of the drive mechanism 8 is driven and the movable frame 21L is moving forward.

[0088] In step S11 (detection signal acquisition step), the main sensor detection signal acquisition unit 104 acquires a detection signal from the main sensor 86. The main sensor 86 turns on a detection signal when the rear contact portion 56B contacts the rear stopper 55B, and the main sensor detection signal acquisition unit 104 acquires this detection signal. At this time, as shown in FIG. 11(B), the front contact portion 56A is not in contact with the front stopper 55A, and the movable frame 21L is tilted obliquely with respect to the front-rear direction X, causing a positional deviation.

[0089] In step S12 (clock count step), the clock counting unit 105 starts counting the clock from the timing of acquiring the detection signal.

[0090] In step S13 (comparison step), comparison unit 106 reads the time lag setting value stored in auxiliary storage device 101 and compares it with the count value counted by clock count unit 105. If the count value matches the value corresponding to the time lag setting value, the process proceeds to step S14 and resets the count of clock count unit 105. If they do not match, step S13 is repeated until they match.

[0091] That is, during execution of step S13, the motor 80 of the drive mechanism 8 is driven, and a driving force in the forward direction is applied to the movable frame 21L. Therefore, as shown in FIG. 11(C), during execution of step S13, the front contact portion 56A moves forward and contacts the front stopper 55A, and the surface 21d of the movable frame 21L facing the working area S becomes parallel to a plane including the front-rear direction X and the up-down direction. That is, the surface 21d of the movable frame 21L facing the working area S is located in the forward position. Because the rear contact portion 56B is already in contact with the rear stopper 55B, even if a driving force for forward movement is applied to the rear stopper 55B, the rear stopper 55B prevents the rear side of the movable frame 21L from moving forward beyond the forward position.

[0092] In step S14 (stop signal output step), the stop signal output unit 107 outputs a stop signal to the power supply circuit 113.

[0093] Upon receiving the stop signal, the power supply circuit 113 stops supplying power to the motor 80, thereby stopping the forward movement of the movable frame 21L.

[0094] 15, if a positional misalignment occurs such that the front contact portion 56A contacts the front stopper 55A before the detection timing of the main sensor 86, when the main sensor detection signal acquirer 104 acquires a detection signal from the main sensor 86 in step S11, the front and rear contact portions 56A, 56B contact the front and rear stoppers 55A, 55B, respectively, and the movable frame 21L is already in the forward position, as shown in FIG. 11C. Therefore, while steps S11 to S13 are being executed, the driving force continues to be applied to the movable frame 21L and the front and rear stoppers 55A, 55B. However, the front and rear stoppers 55A, 55B prevent the movable frame 21L from moving forward and prevent it from moving forward beyond the forward position, so that the surface 21d of the movable frame 21L facing the working area S is parallel to a plane including the front-rear direction X and the up-down direction.

[0095] (Second stop control) Next, the processing procedure of the second stop control will be described with reference to the flowchart shown in Fig. 16. As described above, the second stop control is selected by the operator when it is recognized in advance that a positional deviation has occurred in which the front contact portion 56A contacts the front stopper 55A before the detection timing of the main sensor 86 as shown in Fig. 15.

[0096] In step S21 (detection signal acquisition step), the main sensor detection signal acquisition unit 104 acquires a detection signal from the main sensor 86. Upon acquiring the detection signal, the process proceeds to step S22 (stop signal output step), where the stop signal output unit 107 outputs a stop signal to the power supply circuit 113.

[0097] Upon receiving the stop signal, the power supply circuit 113 stops supplying power to the motor 80, thereby stopping the forward movement of the movable frame 21L. That is, in the second stop control, when the detection signal acquisition unit acquires a detection signal from the main sensor 86, the forward movement of the movable frame 21L is stopped without any time lag.

[0098] (Retraction of the movable frame 21L) Next, the operation of moving the movable frame 21L from the forward position to the backward position will be described. The backward operation is an operation of starting and stopping the backward movement in order to perform the lifting operation of the loaded pallet P1 and the empty pallet P2 by the pallet support mechanisms 70L, 70R.

[0099] (Start of retreat movement) The reverse start signal output unit 110 of the control device 100 executes transmission of a reverse start signal to the power supply circuit 113. In other words, the reverse start program causes the control device 100 to execute transmission of the reverse start signal. As a result, the power supply circuit 113 supplies power to the motor 80 of the drive mechanism 8 for rotation in the reverse direction. The movable frame 21L receives the driving force of the motor 80 and begins to move backward from the working area S. The timing of generation of the reverse start signal is controlled by the forward / backward start program stored in the control device 100. The reverse start signal is generated at a timing after a loaded pallet P1 or an empty pallet P2 has been carried in or out by the chain conveyors 3, 4 for transporting loads and empty pallets, respectively, provided on the movable frame 21L.

[0100] (Stop backward movement) The movable frame 21L moves backward, and the detection signal acquisition unit of the control device 100 acquires a detection signal from the backward detection sensor 87 (FIG. 11(A)). The stop signal output unit 107 outputs a stop signal to the power supply circuit 113. This causes the movable frame 21L to stop moving backward.

[0101] 17(A) and 17(B), the movable frame 21L may also stop in a position that is displaced diagonally rather than along the front-to-rear direction X. However, the movable frame 21L is located closer to the rearward position than the forward position, and it is sufficient that it is in a position that does not interfere with the lifting and lowering operation of the loaded pallet P1 and empty pallet P2 by the pallet support mechanisms 70L and 70R, so it may stop in a displaced position.

[0102] (Other embodiments) 18 to 20 is the embodiment shown in Figures 1 to 10, to which an auxiliary sensor 120 is further added. In the following explanation, the differences from the embodiment shown in Figures 1 to 10 will be explained.

[0103] The auxiliary sensor 120 detects when the front contact portion 56A contacts the front stopper 55A. As shown in FIGS. 19(A) to 19(C), the auxiliary sensor 120 is disposed on the same straight line as the reverse detection sensor 87 in the left-right direction Y and further forward than the reverse detection sensor 87. The detection output of the auxiliary sensor 120 is turned on and off by a light-shielding plate 88A disposed on the upper side of the outer surface of the front plate 21b of the movable frame 21L. When the front contact portion 56A of the movable frame 21L contacts the front stopper 55A, the light-shielding plate 88a is positioned between the light-emitting portion 120a and the light-receiving portion 120b of the auxiliary sensor 120. The configuration of the auxiliary sensor 120 is the same as that of the main sensor 86, so a description of the configuration of the auxiliary sensor 120 will be omitted.

[0104] In this embodiment, the control device 100 does not include the time lag acquisition unit 103, the clock count unit 105, and the comparison unit 106, but instead includes an auxiliary sensor detection signal acquisition unit 121 that acquires a detection signal from the auxiliary sensor 120, and a determination unit 122 that determines whether or not a detection signal has been acquired from the auxiliary sensor 120. The control device 100 determines the time between acquiring a detection signal from the main sensor 86 and receiving a detection signal from the auxiliary sensor 120 as the time lag.

[0105] In the preparation process, only the program selection and acquisition step of step S1 is performed, and the time lag acquisition step of step S2 is not performed.

[0106] The first stop control is selected and executed when the operator recognizes that the detection timing of the auxiliary sensor 120 will be later than the detection timing of the main sensor 86. In this embodiment, that is, the first stop control is executed when the timing at which the front contact portion 56A contacts the front stopper 55A will be later than the timing at which the rear contact portion 56B contacts the rear stopper 55B (see FIG. 19(B)).

[0107] The processing procedure of the first stop control will be explained using the flowchart in Fig. 20. In step S31 (detection signal acquisition step), the main sensor detection signal acquisition unit 104 acquires a detection signal from the main sensor 86. In step S32 (determination step), the determination unit 122 determines whether the auxiliary sensor detection signal acquisition unit 121 has acquired a detection signal from the auxiliary sensor 120. If so, in step S33 (stop signal output step), the stop signal output unit 107 outputs a stop signal to the power supply circuit 113. That is, the time between acquiring the detection signal from the main sensor 86 and receiving the detection signal from the auxiliary sensor 120 is the time lag.

[0108] The second stop control is executed when the detection timing of the auxiliary sensor 120 is earlier than the detection timing of the main sensor 86. In this embodiment, that is, the second stop control is executed when the timing at which the front contact portion 56A contacts the front stopper 55A is earlier than the timing at which the rear contact portion 56B contacts the rear stopper 55B (see FIG. 15).

[0109] The processing procedure for the second stop control is the same as that shown in the flowchart of Fig. 16, and therefore will not be described here. In this case, when the main sensor detection signal acquirer 104 acquires a detection signal from the main sensor 86, it stops the forward movement of the movable frame 21L without causing a time lag.

[0110] According to this embodiment, by setting a time lag between the timing of detection by the main sensor 86 and the timing of stopping the advancing / retracting movement of the movable frame 21L, even if the stop position of the movable frame 21L after advancing deviates from the appropriate position due to aging, such as wear of the sliding parts of the guide mechanism 50, the positional deviation can be easily corrected. Furthermore, since it is possible to select between the first stop control and the second stop control, for example, in a case where the abutment portion 56A on the side opposite the side on which the main sensor 86 is provided abuts against the stopper 55A before the abutment portion 56B on the side on which the main sensor 86 is provided abuts against the stopper 55B, no time lag is required, and therefore the second stop control, which does not set a time lag, can be selected. This prevents unnecessary driving force from being applied to the movable frame 21L and the stoppers 55A and 55B, thereby shortening the time required for the advancing movement.

[0111] Furthermore, in the prior art, a pair of parallel link mechanisms is used as the movable frame movement mechanism to prevent misalignment of the movable frame. On the other hand, in this embodiment, even if misalignment does occur, the control device 100 can prevent the misalignment by moving the movable frame 21L back and forth as described above. This eliminates the need for a movable frame movement mechanism with a complex structure as in the prior art, simplifies the structure of the movable frame movement mechanism 5, reduces the number of parts, reduces manufacturing costs, and eliminates the need for laborious assembly and adjustment work.

[0112] (Operation of load transport device) Next, the operation of the load conveying device having the above configuration will be described with reference to FIGS. At a predetermined floor of the lifting mechanism 1, the pallet carrying-in / out device 2 carries in / out the loaded pallet P1 and the empty pallet P2 to / from the lifting table 10 simultaneously in parallel. First, the operation of the pallet loading / unloading device 2 on any floor when a loaded pallet P1 is unloaded onto the lifting table 10 and an empty pallet P2 is loaded from the lifting table 10 will be explained in detail with reference to Figures 21 to 23.

[0113] FIG. 21(A) shows a state in which an empty pallet P2 placed on the floor G has been loaded with goods, that is, a state in which a loaded pallet P1 is waiting. In this standby state, in the left and right load loading / unloading mechanisms 200L, 200R, the support claws 71 of the pallet support mechanisms 70L, 70R of the pallet loading / unloading mechanism 7 are positioned below the flange 17 of the loaded pallet P1. In addition, the movable frames 21L, 21R of the left and right load loading / unloading mechanisms 200L, 200R are retracted, and the chain conveyor 3 for transporting loads and the chain conveyor 4 for transporting empty pallets are retracted outside the working area S.

[0114] When the pallet loading / unloading mechanism 7 begins operation, the support claws 71 of each pallet support mechanism 70L, 70R support the loaded pallet P1 and lift it to a position above the load-transporting chain conveyors 3, 3, as shown in Figure 21(B). When the loaded pallet P1 is being lifted, the load-transporting chain conveyor 3 and the empty pallet-transporting chain conveyor 4 are retracted outside the work area S, so the chain conveyors 3, 4 do not interfere with the lifting operation of the loaded pallet P1.

[0115] Next, as shown in Figure 22(A), in the left and right load carrying-in / out mechanisms 200L, 200R, the motors 80 of the drive mechanisms 8 are driven synchronously, and the cranks 81 are extended. As a result, each movable frame 21L, 21R moves forward from the retracted position to the advanced position while maintaining an upright posture, and the load-transporting chain conveyors 3, 3 are positioned directly below the flange 17 of the loading conveyor P1. At this time, the control device 100 controls the stopping timing of the movable frames 21L, 21R to eliminate any misalignment of the movable frames 21L, 21R, so that the faces 21d of the movable frames 21L, 21R facing the working area S become parallel to each other.

[0116] Thereafter, the support claws 71 of each pallet support mechanism 70L, 70R are lowered, and as shown in Figure 22(B), the loading pallet P1 is lowered onto the chain conveyors 3, 3 for transporting loads. As the support claws 71 are further lowered, they are disengaged from the flanges 17 of the loading pallet P1.

[0117] Next, in each of the load carrying-in / out mechanisms 200L, 200R, when the motors 37 of the load transport chain conveyors 3 are rotated in synchronization, the load transport chain conveyors 3 are driven and the conveyor chains 30 run in the direction to carry out the loaded pallet P1. The rotational drive force of each motor 37 is transmitted to the chain conveyor 4 for transporting empty pallets via the power transmission mechanism 6, and the conveyor chains 40 of the chain conveyor 4 for transporting empty pallets run in the direction to carry in the empty pallet P2.

[0118] The chain conveyor 3 for transporting loads and the first conveyor 11 of the lifting table 10 are linked together, and the first conveyor 11 is driven in the direction to take in loads from the pallet carry-in / out device 2. In addition, the chain conveyor 4 for transporting empty pallets and the second conveyor 12 of the lifting table 10 are linked together, and the second conveyor 12 is driven in the direction to send the empty pallet P2 to the pallet carry-in / out device 2.

[0119] Figure 23 shows a state in which a loaded pallet P1 on a chain conveyor 3,3 for transporting cargo is transported onto the first conveyor 11 of the lifting table 10, and at the same time, an empty pallet P2 on the second conveyor 12 of the lifting table 10 is transported onto the chain conveyor 4,4 for transporting empty pallets.

[0120] Next, with reference to Figures 24 and 25, the operation when a loaded pallet P1 is transported into the pallet transport device 2 on any floor from the lifting table 10 of the lifting mechanism 1 and an empty pallet P2 is simultaneously transported from the pallet transport device 2 onto the lifting table 10 will be explained in detail.

[0121] Figure 24(A) shows a state in which a loaded pallet P1 is transported from the lifting table 10 onto the chain conveyors 3,3 for transporting cargo by linking the first conveyor 11 of the lifting table 10 with the chain conveyors 3,3 for transporting cargo of the pallet loading / unloading device 2, and at the same time, an empty pallet P2 is transported from the chain conveyors 4,4 for transporting empty pallets to the lifting table 10 by linking the chain conveyors 4,4 for transporting empty pallets with the second conveyor 12 of the lifting table 10. In this state, the left and right pallet support mechanisms 70L, 70R of the pallet loading / unloading mechanism 7 position the support claws 71 below the flanges 17 of the loading pallet P1.

[0122] Figure 24(B) shows the state in which the left and right pallet support mechanisms 70L, 70R of the pallet loading / unloading mechanism 7 are driven to raise the support claws 71. When raised, the support claws 71 engage with and support the flanges 17 of the loading pallet P1, and further raise the loading pallet P1 above the chain conveyors 3, 3 for transporting goods.

[0123] Thereafter, in the left and right load carrying-in / out mechanisms 200L, 200R, the motors 80 of the drive mechanisms 8 rotate in the opposite direction to the above, and the cranks 81 contract. As a result, the movable frames 21L, 21R move backward while maintaining an upright position, and the load-transporting chain conveyors 3, 3 and the empty pallet-transporting chain conveyors 4, 4 move outward from their positions directly below the flange 17 of the loading conveyor P1.

[0124] Thereafter, the support claws 71 of the pallet support mechanisms 70L, 70R are lowered as shown in Figure 25(A) to lower the loading pallet P1 onto the floor surface G, and then, as shown in Figure 25(B), the cargo is removed from the loading pallet P1 by a forklift.

[0125] In the above embodiment, cargo is loaded onto an empty pallet P2 placed on the floor G, and then removed from the loaded pallet P1 which has been lowered to the floor G. However, it is also possible to load cargo onto the empty pallet P2 while it is supported on the chain conveyor 4 for transporting empty pallets, or to remove cargo from the loaded pallet P1 without lowering it to the floor G. [Explanation of symbols]

[0126] 1 Lifting mechanism 10. Lift table 11 First conveyor (transport conveyor) 12 Second conveyor (transport conveyor) 2 Pallet loading / unloading device 3 Chain conveyors for transporting goods 4 Chain conveyor for transporting empty pallets 7 Pallet loading and unloading mechanism 8 Drive mechanism 20L, 20R fixed frame 21L, 21R movable frame 21a Side plate part 21b Front plate part 21c Rear plate part 50 Guide mechanism 51 Guide section 53 Sliding part 54b Synthetic resin board 55A, 55B stopper 56A, 56B Contact part 80 Motor 81 Crank mechanism 86 Main sensor 87 Reverse detection sensor 100 control device 120 Auxiliary Sensor 200L,200R loading / unloading mechanism P1 Loading pallet P2 Empty Palette G1,G2 entrance / exit S work area

Claims

1. A pallet loading / unloading device that is installed outside a load loading / unloading entrance of a lifting mechanism and loads pallets onto and unloads pallets from a lifting table, a pair of load carrying-in / out mechanisms arranged opposite to each other across a work area facing the load carrying-in / out entrance, Each of the load carrying-in / out mechanisms is a fixed frame installed on the floor; a movable frame movably supported on the fixed frame and provided with a chain conveyor on the side facing the work area for transporting pallets to and from the lift table; a pallet loading / unloading mechanism for loading / unloading pallets onto / from the chain conveyor; a movable frame moving mechanism that moves the movable frame toward and away from the work area along a guide mechanism provided between the movable frame and the fixed frame, The movable frame moving mechanism includes: a drive mechanism that applies a drive force to the movable frame to move the movable frame toward and away from the working area; a pair of stoppers provided on the fixed frame; a pair of abutment portions provided at both ends of the movable frame and arranged opposite the pair of stoppers; a main sensor that detects that a predetermined one of the pair of contact portions has come into contact with one of the stoppers; A pallet loading / unloading device comprising a control device capable of selectively executing a first stop control that stops the drive mechanism by creating a time lag between the detection timing of the main sensor and the stop timing of stopping the drive mechanism, and a second stop control that stops the drive mechanism at the detection timing of the main sensor without creating a time lag.

2. The pallet loading / unloading device described in claim 1, wherein the drive mechanism includes a motor capable of rotating forward and reverse, and a power transmission mechanism that converts the rotational motion of the motor into reciprocating linear motion and transmits it to the center position in the width direction of the movable frame.

3. 2. A pallet loading / unloading device as described in claim 1, wherein the chain conveyor is configured in two tiers, one above the other, with a first chain conveyor for transporting loaded pallets and a second chain conveyor for transporting empty pallets.

4. 2. A pallet loading / unloading device as described in claim 1, wherein the guide mechanism includes a guide portion provided on the fixed frame side and a sliding portion provided at a position opposite the guide portion on the movable frame side, and the contact portion of the sliding portion with the guide portion is made of a synthetic resin plate.

5. 2. The pallet loading / unloading device of claim 1, wherein the control device executes only the first stop control, of the first stop control and the second stop control, which stops the drive mechanism by creating a time lag between the detection timing of the main sensor and the stop timing of stopping the drive mechanism.

6. The control device of claim 1, wherein when the other abutment portion abuts against the other stopper at a timing after the detection timing of the main sensor, the control device executes a first stop control to stop the drive mechanism by creating a time lag between the detection timing of the main sensor and the stop timing of the drive mechanism, and when the other abutment portion abuts against the other stopper at a timing before the detection timing of the main sensor, the control device executes a second stop control to stop the drive mechanism at the detection timing of the main sensor without creating a time lag.

7. further comprising an auxiliary sensor that detects that the other abutment portion has abutted against the other stopper; when the detection timing of the auxiliary sensor is later than the detection timing of the main sensor, the control device executes a first stop control to generate a time lag between the detection timing of the main sensor and the stop timing of the drive mechanism, and to stop the drive mechanism at the detection timing of the auxiliary sensor; A pallet loading / unloading device as described in claim 1, wherein if the detection timing of the auxiliary sensor is earlier than the detection timing of the main sensor, a second stop control is executed to stop the drive mechanism at the detection timing of the main sensor without causing a time lag.

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