Forklift cargo handling control system

Abstract

The present invention provides a forklift cargo handling control device that can suppress deformation and damage to pallets when loading cargo onto them. [Solution] The cargo handling control device 1 includes a placement control unit 34 that controls the lift cylinder 17 to lower the forks 9 to a height position where the pallet 10 is placed on the upper surface 21a of the loading platform 21; an upward control unit 35 that controls the lift cylinder 17 to raise the forks 9 to a height position above the lower wall portion 13 of the pallet 10 after the control of the lift cylinder 17 by the placement control unit 34 has been performed; a tilting control unit 36 ​​that controls the tilt cylinder 18 to tilt the forks 9 forward and return them to their normal position after the control of the lift cylinder 17 by the upward control unit 35 has been performed; and an extraction control unit 37 that controls the forklift 2 to extract the forks 9 from the fork holes 11 of the pallet 10 after the control of the tilt cylinder 18 by the tilting control unit 36 ​​has been performed.

Description

Technical Field

[0005]

[0001] The present invention relates to a cargo handling control device for a forklift.

Background Art

[0002] As a cargo handling control device for a forklift, for example, the technology described in Patent Document 1 is known. The cargo handling control device described in Patent Document 1 transports the load to above the loading place with the forks tilted backward, then places the load at the loading place with the forks tilted forward and leveled, and then reverses the forklift to remove the forks from the fork pockets of the load.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when automatically placing a pallet by the automatic operation of a forklift, in order to shorten the placement time, the pallet may be placed on the truck bed or the like with the forks tilted backward, and in this state, the forks may be tilted forward to return to the horizontal position. However, when the forks are tilted forward to return to the horizontal position while the forks are in contact with the inner wall surface of the lower wall portion of the pallet, the following problems occur. That is, since the tilting center of the forks becomes the L-shaped corner portion of the forks, when trying to return the forks to the horizontal position, the inner wall surface of the lower wall portion of the pallet is pushed by the forks, which may cause deformation and damage of the inner wall surface of the pallet.

[0005] An object of the present invention is to provide a cargo handling control device for a forklift that can suppress the occurrence of deformation and damage of a pallet when placing the pallet.

Means for Solving the Problems

[0006] (1) One aspect of the present invention is a cargo handling control device for a forklift that includes a lift cylinder for raising and lowering forks capable of holding a pallet, and a tilt cylinder for tilting the forks, and loads a pallet by lifting the forks inserted into the fork holes of the pallet with the lift cylinder and tilting the forks backward from their normal position with the tilt cylinder, comprising: a placement control unit that controls the lift cylinder to lower the forks to a height position where the pallet is placed on the placement surface; a lifting control unit that controls the lift cylinder to raise the forks to a height position above the lower wall of the pallet after the lifting control unit has performed control of the lift cylinder; a tilting control unit that controls the tilt cylinder to tilt the forks forward and return them to their normal position after the lifting control unit has performed control of the lift cylinder, or simultaneously with the lifting control unit having performed control of the lift cylinder; and a withdrawal control unit that controls the forklift to withdraw the forks from the fork holes of the pallet after the tilting control unit has performed control of the tilt cylinder.

[0007] In such a cargo handling control device, when a pallet is placed with the forks holding the pallet tilted backward from their normal position, the lift cylinder is controlled to lower the forks to a height position where the pallet will be placed on the loading surface. Then, after the lift cylinder is controlled to raise the forks to a height above the lower wall of the pallet, or simultaneously with the lift cylinder being controlled to raise the forks to a height above the lower wall of the pallet, the tilt cylinder is controlled to tilt the forks forward to return them to their normal position. In this state, the forks are withdrawn from the fork holes in the pallet. By raising the forks to a height above the lower wall of the pallet and then tilting them forward to return them to their normal position, or by raising the forks to a height above the lower wall of the pallet and simultaneously tilting them forward to return them to their normal position, the forks are not tilted forward while in contact with the inner wall surface of the lower wall of the pallet. Therefore, the lower wall of the pallet is not pushed by the forks. As a result, deformation and damage to the pallet are suppressed when the pallet is placed.

[0008] (2) In (1) above, the lift control unit may control the lift cylinder to raise the fork to a height position where it does not come into contact with the upper wall of the pallet.

[0009] In this configuration, even if the forks are raised to a height above the lower wall of the pallet, the forks do not come into contact with the inner wall surface of the upper wall of the pallet. Therefore, the upper wall of the pallet is not pushed by the forks. Consequently, deformation and damage to the pallet are further suppressed when loading goods onto the pallet.

[0010] (3) In the above (2), the cargo handling control device further comprises a lifting height detection unit for detecting the lifting height of the forks and a tilt angle detection unit for detecting the tilt angle of the forks, and the lifting control unit may determine the amount to which the forks should be raised so that the forks do not come into contact with the lower and upper walls of the pallet, based on the lifting height of the forks detected by the lifting height detection unit and the tilt angle of the forks detected by the tilt angle detection unit, and control the lift cylinder to raise the forks according to the amount of rise.

[0011] In this configuration, with the pallet placed on the mounting surface, a fork lifting amount suitable for the fork's lifting height and tilt angle relative to the mounting surface can be obtained.

[0012] (4) In (3) above, the fork has a mounting portion attached to the mast of the forklift and a claw portion that extends forward from the lower end of the mounting portion and is inserted into the fork hole, the lower limit of the fork lift is calculated based on the thickness of the lower wall of the pallet and the distance from the base end of the claw portion to the mounting surface, and the upper limit of the fork lift may be calculated based on the thickness of the lower wall of the pallet, the height of the fork hole, the distance from the base end of the claw portion to the mounting surface, the length of the claw portion, the thickness of the tip of the claw portion and the tilt angle of the fork.

[0013] In this configuration, the appropriate fork lifting height and tilt angle relative to the mounting surface can be obtained using a simple calculation formula. [Effects of the Invention]

[0014] According to the present invention, deformation and damage to pallets can be suppressed when pallets are used for loading goods. [Brief explanation of the drawing]

[0015] [Figure 1] This is a block diagram showing the configuration of a cargo handling control device for a forklift according to one embodiment of the present invention. [Figure 2]A schematic side view (including a partial cross-section) showing a reach forklift holding a pallet by forks together with the truck bed. [Figure 3] A side view showing a state where a pallet is placed on the truck bed. [Figure 4] A schematic side view (including a partial cross-section) showing a state where the pallet held by the forks is placed on the truck bed and then the forks are lifted. [Figure 5] A flowchart showing the procedure of the lift control process executed by the lift control unit shown in FIG. 1. [Figure 6] A schematic side view (including a partial cross-section) showing parameters for determining the lift amount of the forks in the lift control unit shown in FIG. 5. [Figure 7] A schematic side view (including a partial cross-section) showing a state where the forks are tilted forward to return to the normal position and then the forks are pulled out from the fork holes of the pallet. [Figure 8] A schematic side view (including a partial cross-section) showing a counterbalanced forklift holding a pallet by forks together with the truck bed.

MODE FOR CARRYING OUT THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant descriptions are omitted.

[0017] FIG. 1 is a block diagram showing the configuration of a cargo handling control device for a forklift according to an embodiment of the present invention. In FIG. 1, the cargo handling control device 1 of the present embodiment is mounted on a reach forklift 2 as shown in FIG. 2.

[0018] The forklift 2 has a vehicle body 3, a pair of left and right reach legs 4 extending from the lower part of the vehicle body 3 forward of the vehicle body 3, front wheels 5 disposed at the tip (front end) of each reach leg 4, rear wheels 6 disposed at the rear part of the vehicle body 3, a mast 7 disposed between the reach legs 4 and movable in the front-rear direction of the vehicle body 3 along the reach legs 4, and a pair of left and right forks 9 connected to the mast 7 via a connecting part 8 and capable of being lifted and tilted and holding a pallet 10.

[0019] The pallet 10 is a cargo handling platform for loading the load M. The pallet 10 is, for example, a flat pallet. The pallet 10 has a substantially rectangular shape in plan view. The pallet 10 is provided with two fork holes 11 into which each fork 9 of the forklift 2 is inserted.

[0020] As shown in FIGS. 2 and 3, the pallet 10 has an upper wall portion 12, a lower wall portion 13 disposed below the upper wall portion 12, two side wall portions 14 connecting both ends of the upper wall portion 12 and both ends of the lower wall portion 13 respectively, and a partition wall portion 15 connecting the central portion of the upper wall portion 12 and the central portion of the lower wall portion 13. The fork holes 11 are defined by the inner wall surface 12a of the upper wall portion 12, the inner wall surface 13a of the lower wall portion 13, the inner wall surface 14a of the side wall portion 14, and the inner wall surface 15a of the partition wall portion 15.

[0021] As shown in FIG. 2, the fork 9 has an L shape in side view. The fork 9 has a mounting portion 9a attached to the mast 7 via a connecting part 8, and a claw portion 9b extending forward of the forklift 2 from the lower end of the mounting portion 9a and inserted into the fork hole 11 of the pallet 10. The tilting center of the fork 9 is the base end portion of the claw portion 9b, that is, the L-shaped corner portion of the fork 9.

[0022] In the state where the fork 9 is in its normal position (see FIG. 7), the mounting portion 9a extends in the vertical direction so as to be parallel to the mast 7. In the state where the fork 9 is in its normal position, the claw portion 9b extends in the horizontal direction. The horizontal state here includes not only a completely horizontal state but also a state slightly inclined from the completely horizontal state.

[0023] A spacer 16 is attached to the base end of the fork 9. A limit sensor (not shown) is placed on the spacer 16 to detect whether the fork 9 is inserted into the fork hole 11 of the pallet 10.

[0024] Furthermore, as shown in Figure 1, the forklift 2 includes a lift cylinder 17 for raising and lowering the forks 9, a tilt cylinder 18 for tilting the forks 9, and a reach cylinder 19 that moves the forks 9 in the forward and backward directions by moving the mast 7 in the forward and backward directions.

[0025] As shown in Figure 2, the forklift 2 uses a lift cylinder 17 to lift the forks 9 inserted into the fork holes 11 of the pallet 10, and a tilt cylinder 18 to tilt the forks 9 backward from their normal position, thereby placing the pallet 10 on the truck bed 21 of the truck 20. The upper surface 21a of the truck bed 21 is the loading surface on which the pallet 10 is placed. Side panels 22 are connected to the edge of the truck bed 21 so as to be openable and closable.

[0026] Returning to Figure 1, the cargo handling control device 1 is a device that controls the forklift 2 to automatically place the pallets 10 onto the cargo bed 21 of the truck 20. The pallets 10 are placed sequentially, for example, from the front to the rear of the truck 20.

[0027] The cargo handling control device 1 includes a laser sensor 23, a laser sensor 24, a camera 25, a lifting height sensor 26, a tilt angle sensor 27, a travel drive unit 28, a cargo handling drive unit 29, and a controller 30.

[0028] The laser sensor 23 is mounted on the upper part of the forklift 2's body 3 (see Figure 2). The laser sensor 23 emits a laser beam around the forklift 2 and receives the reflected laser light to detect the distance to objects around the forklift 2 and acquire point cloud data. The point cloud is a collection of laser reflection points. The horizontal irradiation range of the laser by the laser sensor 23 is 360 degrees. For example, a 3D LIDAR can be used as the laser sensor 23.

[0029] The laser sensor 24 is attached to column members 40 erected on both sides of the forklift body 3 (see Figure 2). The laser sensor 24 emits a laser beam toward the side of the forklift 2 and detects the distance to objects located beside the forklift 2 by receiving the reflected laser light, thereby acquiring point cloud data. The horizontal irradiation range of the laser by the laser sensor 24 is narrower than that of the laser sensor 23. For example, a 3D LiDAR can be used as the laser sensor 24.

[0030] Camera 25 is attached to the column member 40 (see Figure 2). Camera 25 is positioned vertically relative to the laser sensor 24. Camera 25 captures images of the side of the forklift 2 and acquires image data.

[0031] The lifting height sensor 26 is attached to the mast 7 of the forklift 2 (see Figure 2). The lifting height sensor 26 is a lifting height detection unit that detects the height position (lifting height) of the forks 9 of the forklift 2.

[0032] The tilt angle sensor 27 is attached to the mast 7 of the forklift 2 (see Figure 2). The tilt angle sensor 27 is a tilt angle detection unit that detects the tilt angle (tilting angle) of the forks 9 of the forklift 2.

[0033] The drive unit 28 is the drive unit that moves the forklift 2. The drive unit 28 includes, for example, a drive motor that rotates the rear wheels 6 and a steering motor that steers the front wheels 5, although these are not shown in the figures.

[0034] The cargo handling drive unit 29 is a drive unit that operates the lift cylinder 17, tilt cylinder 18, and reach cylinder 19. The cargo handling drive unit 29 is, for example, an oil control valve located between the hydraulic pump and the lift cylinder 17, tilt cylinder 18, and reach cylinder 19 (though not shown in the figure).

[0035] The controller 30 consists of a CPU, RAM, ROM, and an input / output interface, etc. The controller 30 includes a self-position estimation unit 31, a cargo placement position detection unit 32, a travel control unit 33, a placement control unit 34, a lifting control unit 35, a tilting control unit 36, and a pull-out control unit 37.

[0036] The self-position estimation unit 31 estimates the self-position of the forklift 2 based on the point cloud data from the laser sensor 23 and pre-stored map data. Specifically, the self-position estimation unit 31 estimates the self-position of the forklift 2 by matching the point cloud data from the laser sensor 23 with the map data, for example, using the SLAM (simultaneous localization and mapping) method. SLAM is a self-position estimation technique that uses sensor data and map data to estimate the self-position.

[0037] The cargo placement position detection unit 32 detects the placement position on the truck bed 21 of the truck 20 where the pallets 10 will be placed, based on the point cloud data from the laser sensor 24 and the image data from the camera 25. The cargo placement position detection unit 32 acquires the point cloud data from the laser sensor 24 and the image data from the camera 25 with the forklift 2 facing sideways to the truck bed 21 of the truck 20, and detects the placement position. The placement position of the first (initial) pallet 10 is at the front end of the truck bed 21. The placement positions of the second and subsequent pallets 10 are adjacent to the rear side of the truck 20 relative to the pallet 10 that was previously placed. The cargo placement position detection unit 32 may also detect the placement position based on only one of the point cloud data from the laser sensor 24 and the image data from the camera 25.

[0038] The travel control unit 33 controls the travel drive unit 28 to move the forklift 2 to a position corresponding to the loading position detected by the loading position detection unit 32, based on the self-position of the forklift 2 estimated by the self-position estimation unit 31. At this time, the travel control unit 33 tilts the forks 9 backward from the normal position toward the mast 7 using the tilt cylinder 18, and raises the pallet 10 to a position higher than the loading platform 21 using the lift cylinder 17, and then moves the forklift 2 to the position corresponding to the loading position.

[0039] Alternatively, the travel control unit 33 may control the travel drive unit 28 to move the forklift 2 to a position just before the loading position, and then control the reach cylinder 19 via the cargo handling drive unit 29 so that the forks 9 move forward (reach out) to the loading position.

[0040] After the travel control unit 33 controls the travel drive unit 28, the loading control unit 34 controls the lift cylinder 17 via the cargo handling drive unit 29 to lower the fork 9 to a height position where it will be placed on the cargo bed 21 of the truck 20, based on the height position of the fork 9 detected by the lift height sensor 26.

[0041] The controller 30 knows in advance the height position of the truck bed 21. Therefore, the loading control unit 34 calculates the amount of descent of the forks 9 based on the height position of the forks 9 detected by the lifting height sensor 26 and the height position of the truck bed 21, and controls the lift cylinder 17 via the cargo handling drive unit 29 to lower the forks 9 according to that amount of descent.

[0042] When the loading control unit 34 controls the lift cylinder 17, as shown in Figure 4(a), the forks 9 descend, and the pallet 10 held by the forks 9 is placed on the loading platform 21. At this time, even after the pallet 10 is placed on the loading platform 21 of the truck 20, the forks 9 continue to descend slightly while remaining tilted backward from their normal position. Therefore, the forks 9 are positioned below the inner wall surface 12a of the upper wall portion 12 of the pallet 10. The loading control unit 34 controls the lift cylinder 17 via the cargo handling drive unit 29 to lower the forks 9 to the height position at which it is placed on the loading platform 21 of the truck 20, as described above.

[0043] After the lifting control unit 34 has controlled the lift cylinder 17, the lifting control unit 35 controls the lift cylinder 17 via the cargo handling drive unit 29 to raise the forks 9 to a height above the lower wall portion 13 of the pallet 10. The lifting control unit 35 controls the lift cylinder 17 via the cargo handling drive unit 29 to raise the forks 9 to a height where they do not come into contact with the upper wall portion 12 of the pallet 10.

[0044] The lifting control unit 35 determines the amount by which the forks 9 should be raised so that they do not come into contact with the lower wall portion 13 and the upper wall portion 12 of the pallet 10, based on the lifting height of the forks 9 detected by the lifting height sensor 26 and the tilt angle of the forks 9 detected by the tilt angle sensor 27, and controls the lift cylinder 17 via the cargo handling drive unit 29 to raise the forks 9 according to that amount.

[0045] When the lift control unit 35 controls the lift cylinder 17, the forks 9 rise slightly so as not to contact the lower wall 13 and upper wall 12 of the pallet 10, as shown in Figure 4(b). The control process of the lift cylinder 17 by the lift control unit 35 is the process of controlling the lift cylinder 17 via the cargo handling drive unit 29 so that the forks 9 rise to a height above the lower wall 13 of the pallet 10, as described above.

[0046] Figure 5 is a flowchart showing the procedure for the lifting control process performed by the lifting control unit 35. In Figure 5, the lifting control unit 35 first acquires the detected values ​​of the lifting height sensor 26 and the tilt angle sensor 27 (procedure S101).

[0047] Next, the lifting control unit 35 determines the amount of lifting of the forks 9 based on the detected values ​​of the lifting height sensor 26 and the tilt angle sensor 27 (procedure S102). At this time, the lower limit of the amount of lifting of the forks 9 is calculated based on the thickness of the lower wall portion 13 of the pallet 10 and the distance from the base end of the claw portion 9b of the forks 9 to the upper surface 21a of the truck bed 21 of the truck 20. The upper limit of the amount of lifting of the forks 9 is calculated based on the thickness of the lower wall portion 13 of the pallet 10, the height of the fork holes 11 of the pallet 10, the distance from the base end of the claw portion 9b to the upper surface 21a of the truck bed 21, the length of the claw portion 9b, the thickness of the tip of the claw portion 9b, and the tilt angle (tilting angle) of the forks 9.

[0048] Specifically, as shown in Figure 6, when the thickness of the lower wall portion 13 of the pallet 10 is a, the height of the fork holes 11 of the pallet 10 is b, the distance from the base end of the claw portion 9b of the fork 9 to the upper surface 21a of the loading platform 21 is c, the length of the claw portion 9b is L, the thickness of the tip of the claw portion 9b is d, and the tilt angle of the fork 9 is θ, the amount of rise x of the fork 9 is expressed by the following formula. ac <x<a+b-c-d-Lsinθ …(A)

[0049] The distance c from the base end of the claw portion 9b to the upper surface 21a of the loading platform 21 is obtained from the lifting height of the fork 9. Furthermore, distance c also includes response delays and physical variations specific to the forklift 2.

[0050] Next, the lifting control unit 35 controls the cargo handling drive unit 29 to raise the forks 9 according to the lifting amount x that satisfies the above equation (procedure S103). This prevents the forks 9 from hitting the upper wall portion 12 of the pallet 10 and lifting the pallet 10.

[0051] Returning to Figure 1, the tilt control unit 36 ​​controls the tilt cylinder 18 via the cargo handling drive unit 29 to tilt the fork 9 forward and return it to its normal position after the lift control unit 35 has controlled the lift cylinder 17.

[0052] When the tilt control unit 36 ​​controls the tilt cylinder 18, the fork 9 returns to its normal position, as shown in Figure 7(a). The control process of the tilt cylinder 18 by the tilt control unit 36 ​​is a process of controlling the tilt cylinder 18 via the cargo handling drive unit 29 to tilt the fork 9 forward and return it to its normal position, as described above.

[0053] In the normal position, as described above, the claw portion 9b of the fork 9 extends horizontally. In the normal position, the claw portion 9b of the fork 9 extends parallel or approximately parallel to the inner wall surface 12a of the upper wall portion 12 and the inner wall surface 13a of the lower wall portion 13 of the pallet 10.

[0054] The withdrawal control unit 37 controls the travel drive unit 28 so that the forks 9 are withdrawn from the fork holes 11 of the pallet 10 as the forklift 2 moves backward after the tilt control unit 36 ​​has controlled the tilt cylinder 18.

[0055] When the withdrawal control unit 37 controls the travel drive unit 28, the fork 9 is withdrawn from the fork hole 11 of the pallet 10, as shown in Figure 7(b). The control process of the travel drive unit 28 by the withdrawal control unit 37 is the process of controlling the travel drive unit 28 so that the fork 9 is withdrawn from the fork hole 11 of the pallet 10, as described above.

[0056] The extraction control unit 37 may also control the reach cylinder 19 via the cargo handling drive unit 29 so that the fork 9 retracts (reachs in) and is pulled out from the fork hole 11 of the pallet 10.

[0057] In the cargo handling control device 1 described above, when loading a pallet 10 held by the forks 9, as shown in Figure 2, the forklift 2 travels toward the truck 20 with the forks 9 tilted backward toward the mast 7 from their normal position by the tilt cylinder 18, so that the load M on the pallet 10 does not fall.

[0058] Then, with the forklift 2 positioned sideways to the truck 20, the placement position of the pallet 10 on the truck bed 21 is detected based on the point cloud data from the laser sensor 24 and the image data from the camera 25. The forklift 2 then travels to the position corresponding to the placement position, raising the pallet 10 to a position higher than the upper surface 21a of the truck bed 21 using the lift cylinder 17. As a result, the pallet 10, held by the forks 9, reaches above the placement position on the truck bed 21.

[0059] In this state, the forks 9 are lowered by the lift cylinder 17, and as shown in Figure 4(a), the pallet 10 held by the forks 9 is placed on the upper surface 21a of the loading platform 21. Even after the pallet 10 is placed on the loading platform 21, the forks 9 continue to lower slightly while remaining tilted backward.

[0060] Next, as shown in Figure 4(b), the lift cylinder 17 slightly raises the forks 9 to a height where they do not contact the upper wall 12 of the pallet 10. Then, as shown in Figure 7(a), the tilt cylinder 18 tilts the forks 9 forward so that they return to their normal position. This makes the claw portion 9b of the forks 9 horizontal. In this state, as shown in Figure 7(b), the forklift 2 moves backward, pulling the forks 9 out of the fork holes 11 of the pallet 10.

[0061] As described above, in this embodiment, when the pallet 10 is placed on the pallet 10 with the forks 9 holding the pallet 10 tilted backward from its normal position, the lift cylinder 17 is controlled to lower the forks 9 to a height position where the pallet 10 is placed on the upper surface 21a of the loading platform 21. After the lift cylinder 17 is controlled to raise the forks 9 to a height position above the lower wall portion 13 of the pallet 10, the tilt cylinder 18 is controlled to tilt the forks 9 forward to return it to its normal position. Then, in that state, the forks 9 are withdrawn from the fork holes 11 of the pallet 10. By raising the forks 9 to a height position above the lower wall portion 13 of the pallet 10 and then tilting the forks 9 forward to return it to its normal position, the forks 9 are not tilted forward while in contact with the inner wall surface 13a of the lower wall portion 13 of the pallet 10. Therefore, the lower wall portion 13 of the pallet 10 is suppressed from being pushed by the forks 9. As a result, when the pallet 10 is placed on the pallet 10, scratches, deformation and damage to the pallet 10 are suppressed. Furthermore, this prevents interference with the operation of fork 9, which could lead to hydraulic malfunctions in forklift 2.

[0062] Furthermore, in this embodiment, the lift cylinder 17 is controlled to raise the forks 9 to a height position where they do not come into contact with the upper wall portion 12 of the pallet 10. In this case, even if the forks 9 are raised to a height position above the lower wall portion 13 of the pallet 10, the forks 9 do not come into contact with the inner wall surface 12a of the upper wall portion 12 of the pallet 10, thus preventing the upper wall portion 12 of the pallet 10 from being pushed by the forks 9. Therefore, when loading cargo onto the pallet 10, the occurrence of scratches, deformation, and damage to the pallet 10 is further suppressed.

[0063] Furthermore, in this embodiment, based on the lifting height of the fork 9 detected by the lifting height sensor 26 and the tilt angle of the fork 9 detected by the tilt angle sensor 27, the amount of lift x of the fork 9 is determined so that the fork 9 does not come into contact with the lower wall portion 13 and the upper wall portion 12 of the pallet 10, and the lift cylinder 17 is controlled to raise the fork 9 according to the amount of lift x. In this case, with the pallet 10 placed on the upper surface 21a of the loading platform 21, an amount of lift x of the fork 9 suitable for the lifting height and tilt angle of the fork 9 relative to the upper surface 21a of the loading platform 21 is obtained.

[0064] Furthermore, in this embodiment, the lower limit of the fork lift amount x is calculated based on the thickness a of the lower wall portion 13 of the pallet 10 and the distance c from the base end of the claw portion 9b of the fork 9 to the upper surface 21a of the loading platform 21, while the upper limit of the fork lift amount x is calculated based on the thickness a of the lower wall portion 13 of the pallet 10, the height b of the fork holes 11 of the pallet 10, the distance c from the base end of the claw portion 9b to the upper surface 21a of the loading platform 21, the length L of the claw portion 9b, the thickness d of the tip of the claw portion 9b, and the tilt angle θ of the fork 9. In this case, the fork lift amount x suitable for the lifting height and tilt angle of the fork 9 relative to the upper surface 21a of the loading platform 21 can be obtained by a simple calculation formula.

[0065] It should be noted that the present invention is not limited to the above embodiments. For example, in the above embodiments, the control of the lift cylinder 17 by the lift control unit 35 is performed first, followed by the control of the tilt cylinder 18 by the tilt control unit 36, but the invention is not limited to such a configuration. The control of the lift cylinder 17 by the lift control unit 35 may be performed simultaneously with the control of the tilt cylinder 18 by the tilt control unit 36. In other words, the lift control unit 35 may control the lift cylinder 17 to raise the fork 9 to a height above the lower wall portion 13 of the pallet 10, while the tilt control unit 36 ​​may control the tilt cylinder 18 to tilt the fork 9 forward and return it to its normal position.

[0066] In this manner, by raising the forks 9 to a height above the lower wall portion 13 of the pallet 10 and simultaneously tilting the forks 9 forward to return to their normal position, the forks 9 are not tilted forward while in contact with the inner wall surface 13a of the lower wall portion 13 of the pallet 10. In this case as well, the lower wall portion 13 of the pallet 10 is prevented from being pressed by the forks 9, thus preventing scratches, deformation, and damage to the pallet 10 when it is placed on the pallet. Furthermore, in this case, the raising motion of the forks 9 and the motion of tilting the forks 9 forward to return to their normal position are performed simultaneously, thus shortening the time required to place the pallet 10.

[0067] Furthermore, in the above embodiment, the amount of rise x of the fork 9 is determined based on the lifting height and tilt angle (tilting angle) of the fork 9, and the fork 9 rises according to that amount x, but the embodiment is not limited to such a configuration. For example, regardless of the weight of the load M, if the tilt cylinder 18 tilts the fork 9 backward from its normal position, and the tilt angle θ of the fork 9 and the distance c from the base end of the claw portion 9b of the fork 9 to the upper surface 21a of the loading platform 21 are predetermined, then the amount of rise x of the fork 9 may be a constant value that satisfies equation (A) above.

[0068] Furthermore, in the above embodiment, the lift cylinder 17 is controlled to raise the forks 9 to a height where they do not contact the upper wall portion 12 of the pallet 10, while the pallet 10 held by the forks 9 is placed on the loading platform 21 of the truck 20. However, the system is not limited to this configuration. For example, if the forks 9 do not lift the pallet 10 placed on the loading platform 21 of the truck 20, the tips of the forks 9 may slightly contact the upper wall portion 12 of the pallet 10.

[0069] Furthermore, although the cargo handling control device 1 is mounted on a reach-type forklift 2 in the above embodiment, the cargo handling control device of the present invention may also be mounted on a counterbalanced forklift 2A, as shown in Figure 8. The forklift 2A shown in Figure 8 comprises a body 51, a mast 53 tiltably connected to the body 51 via a connecting part 52, and the above-mentioned forks 9 mounted on the mast 53 so as to be able to move up and down via a lift bracket 54. In this case, the forks 9 tilt together with the mast 53 by a tilt cylinder 18 (see Figure 1).

[0070] Furthermore, although the pallet 10 is placed on the cargo bed 21 of the truck 20 in the above embodiment, the configuration is not limited to this, and the pallet 10 may be placed on the cargo bed of a truck berth or the like, or on the floor surface. [Explanation of Symbols]

[0071] 1...Cargo handling control device, 2,2A...Forklift, 7...Mast, 9...Fork, 9a...Mounting part, 9b...Fork part, 10...Pallet, 11...Fork hole, 12...Upper wall part, 13...Lower wall part, 17...Lift cylinder, 18...Tilt cylinder, 21...Loading platform, 21a...Upper surface (mounting surface), 26...Lifting height sensor (lifting height detection part), 27...Tilt angle sensor (tilting angle detection part), 34...Mounting control unit, 35...Lifting control unit, 36...Tilt control unit, 37...Pulling control unit, a...Thickness, b...Height, c...Distance, d...Thickness, L...Length, θ...Tilt angle (tilting angle), x...Lifting amount.

Claims

1. A forklift cargo handling control device comprising a lift cylinder for raising and lowering forks capable of holding a pallet, and a tilt cylinder for tilting the forks, wherein the lift cylinder lifts the forks inserted into the fork holes of the pallet, and the tilt cylinder tilts the forks backward from their normal position, thereby loading the pallet, A mounting control unit controls the lift cylinder so as to lower the fork to a height position where the pallet is placed on the mounting surface, After the lift cylinder is controlled by the mounting control unit, the lifting control unit controls the lift cylinder to raise the fork to a height above the lower wall of the pallet, After the lift control unit controls the lift cylinder, or simultaneously with the lift control unit controlling the lift cylinder, a tilt control unit controls the tilt cylinder to tilt the fork forward and return it to the normal position, A forklift cargo handling control device comprising: a withdrawal control unit that controls the forklift so that the forks are withdrawn from the fork holes of the pallet after the tilting control unit has performed control of the tilt cylinder; and a withdrawal control unit that controls the forklift so that the forks are withdrawn from the fork holes of the pallet.

2. The lifting control unit controls the lift cylinder to raise the forks to a height position where they do not come into contact with the upper wall of the pallet, as described in claim 1.

3. A lifting height detection unit for detecting the lifting height of the fork, The system further includes a tilt angle detection unit for detecting the tilt angle of the fork, The lifting control unit determines the amount by which the forks should be raised so that the forks do not come into contact with the lower and upper walls of the pallet, based on the lifting height of the forks detected by the lifting height detection unit and the tilt angle of the forks detected by the tilt angle detection unit, and controls the lift cylinder to raise the forks according to the amount of rise, as described in claim 2.

4. The fork has a mounting portion attached to the mast of the forklift, and a claw portion that extends from the lower end of the mounting portion toward the front of the forklift and is inserted into the fork hole. The lower limit of the fork's upward movement is calculated based on the thickness of the lower wall of the pallet and the distance from the base end of the claw to the aforementioned surface. The cargo handling control device for a forklift according to claim 3, wherein the upper limit of the fork lift is calculated based on the thickness of the lower wall portion of the pallet, the height of the fork hole, the distance from the base end of the claw portion to the aforementioned surface, the length of the claw portion, the thickness of the tip of the claw portion, and the tilt angle of the fork.

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