JPH06115897A - Stacking method for post pallet for fork-lift - Google Patents

Abstract

PURPOSE:To perform simple and reliable vertical stacking of post pallets, in a stacking work for the post pallets for a fork-lift. CONSTITUTION:Marks 32 are formed on a plurality of spots on the upper surface of a post pallet W2, which are positioned facing a pair of right and left forks 10, and mark sensors 17 and 18 are arranged on the under surface, positioned facing the marks 32, of the fork 10. This constitution causes placing of a post pallet W3, on which the fork 10 is placed, on the post pallet W2 when the corresponding marks 32 of the post pallet W2 positioned below the mark detecting sensors are detected by the mark detecting sensors 17 and 18 when the fork 10 is lowered to the post pallet W2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forklift cargo handling operation, and more particularly to a method of stacking post pallets.

[0002]

2. Description of the Related Art Conventionally, in the loading and unloading work of an unmanned forklift truck 50, as shown in FIG. 13, between stations S in which luggage is stored, one station S performs unloading and the other station S unloads. There is a thing to put the cargo on. An electromagnetic induction wire L is laid on the road surface between the stations S, and an induction signal for guiding the unmanned forklift 50 is sent. A mark plate 51 is arranged on the electromagnetic induction line L in front of each station S, and the mark plate 51 instructs operation information to the unmanned forklift 50.

The unmanned forklift 50 temporarily stops at a predetermined position of the station S by the mark plate 51, and then moves the forks in a predetermined order to carry out the unloading. After that, the direction is reversed and it moves to a predetermined position of the next station S. Then, the forks are moved again in a predetermined order to load the goods.

The operation of the series of unmanned forklift trucks is controlled by a predetermined control program. Further, this control program presupposes that the related loads are always placed at the correct positions in each work of loading and unloading. That is,
The stop position of the unmanned forklift and the operation amount of the fork are
Highly accurate control is required.

[0005]

By the way, when stacking post pallets, it is necessary to fit each leg of the post pallets to a support formed on the upper part of the lower post pallet. As a result, the stacking of post pallets required a very high level of work.

Therefore, even when the unmanned forklift truck is controlled with high precision, it is necessary to reduce the operating speed of the unmanned forklift truck to carry out the cargo handling work so that the operation of the unmanned forklift truck does not cause an error. . However, if the operation speed is reduced, it will be a great obstacle in improving the efficiency of cargo handling work. Therefore, the stacking of post pallets by an unmanned forklift was almost impossible.

The present invention has been made to solve the above problems, and its object is to easily and reliably stack the post pallets in the vertical direction when stacking the post pallets by a forklift. It is to provide a method of stacking post pallets of a forklift.

[0008]

In order to achieve the above object, the present invention provides marks on a plurality of upper surfaces of a post pallet facing a pair of left and right forks, and detects marks on the lower surface of the fork facing the marks. When the fork is lowered from above with respect to the post pallet by providing a sensor, when each mark detection sensor detects the mark of the corresponding post pallet located below, the post pallet mounted on the fork is moved to the lower post. The gist is the method of stacking post pallets that are placed on a pallet.

[0009]

Therefore, according to the present invention, the relative position between the post pallet mounted on the fork and the lower post pallet is the normal position only when each mark detection sensor detects the corresponding mark of the lower post pallet. Will be facing. As a result, if the fork is lowered from that state, the post pallet mounted on the fork is reliably placed on the lower post pallet.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment embodying the present invention will now be described with reference to FIGS.
This will be described with reference to FIG. FIG. 1 shows the appearance of a reach type unmanned forklift 1.

The unmanned forklift 1 is provided with a pair of left and right leg portions 7 at the lower front portion. A pickup coil 3 for detecting an electromagnetic induction wire (not shown) is provided in front of the lower surface of the unmanned forklift 1, and a pair of mark plate sensors 4 for detecting a mark plate is provided in the center of the lower surface. ing.

A mast 5 is provided in front of the unmanned forklift 1.
Is provided, and the mast 5 moves back and forth along the pair of leg portions 7 as the reach cylinder 6 extends and contracts. The range of movement of the mast 5 before and after is defined by two limit switches M1 and M2 provided on the side of the reach cylinder 6.

The mast 5 is composed of an outer mast 5a and an inner mast 5b, and the inner mast 5b moves up and down as the lift cylinder 8 expands and contracts. A chain wheel (not shown), on which a chain (not shown) is hooked, is rotatably attached to the inner side of the inner mast 5b. A pair of left and right forks 10 are suspended and supported on the chain via lift brackets 9. When the inner mast 5b is moved up and down to wind up and unwind the chain, the lift bracket 9 moves up and down, and at the same time, the fork 10 moves up and down.

A rotary encoder 11 is connected to the chain wheel mounted on the inner side of the inner mast 5b. The rotary encoder 11 detects the rotation amount of the chain wheel.

A tilt cylinder 12 is provided between the lift bracket 9 and the inner mast 5b. The tilt cylinder 12 tilts the fork 10 via the lift bracket 9. Inside the body of the unmanned forklift 1, a hydraulic control circuit for driving and controlling the cylinders 6, 8 and 12 is provided. Then, a cargo handling pump 13 that supplies hydraulic oil to each of the cylinders 6, 8 and 12,
A cargo handling motor 14 that rotationally drives the cargo handling pump 13 is provided. Further, an electromagnetic control valve V for controlling the hydraulic oil to extend and contract each cylinder 6, 8, 12 is provided.

Inside the body of the unmanned forklift 1,
A steering motor 15 for steering and rotating the driving wheels E, a traveling motor 16, and a microcomputer C for controlling these are provided. The unmanned forklift 1 moves forward and backward by the forward / reverse rotation of the drive wheel E and the forward / reverse rotation of the driven wheel D following the forward / reverse rotation,
Carry luggage placed at each station.

2 and 3 show the appearance of the bottom and sides of the fork 10. A pair of mark detection sensors 17 and 18 are provided at symmetrical positions on the bottom surface of the front portion directly below the front surface 10b of the vertical portion of the fork 10. The mark detection sensors 17 and 18 are composed of light emitting diodes and phototransistors. The light emitting diode emits light downward. Further, the phototransistor receives the reflected light of the light emitted downward.

FIG. 4 shows the appearance of the post pallet W0 used in this embodiment. The post pallet W0 is a crosspiece 27a connecting the four pillars 26 and the upper portions of the adjacent pillars 26,
28 a and crosspieces 27 b and 28 b connecting the lower part, and a bottom plate 29. Each pillar 26 has an upper portion as a supporting portion and a lower portion as a leg portion. Also, the crosspiece 27
A net 30 is provided between the a, 27b, 28a, 28b and the pillar 26 to prevent objects from falling. Further, the base of each pillar 26 is provided with a base 31 extending on a quadrangular pyramid.
As shown in FIG. 6, the cross section of the base 31 is a space 31a on a quadrangular pyramid, and a support portion of the column 26 of another post pallet W1 is accommodated in this space 31a. This allows the post pallets W1 to be easily stacked on W0.

As shown in FIGS. 4 and 5, the fork 1 is provided on the upper surface of the crosspiece 27a at the upper part in the longitudinal direction of the post pallet W0.
A pair of marks 32 detected by the mark detection sensors 17 and 18 embedded in the bottom surface of 0 are provided. The mark 32 corresponds to the mark detection sensor 17 of the fork 10.
The mark detection sensors 17 and 18 provided on the fork 10 are provided at the same intervals so that they can be simultaneously detected by 18. That is, when the mark 32 is simultaneously detected by the mark detection sensors 17 and 18,
Fork 10 with the post pallet W0 positioned above
It has come to be judged that they have a correct positional relationship with.

Next, the electrical construction of the unmanned forklift 1 will be described with reference to FIG. The microcomputer C includes a central processing unit (hereinafter referred to as a CPU) 19, a read-only memory (same as the RO) storing a control program.
M) 20, a readable / writable memory (same RAM) 21 for temporarily storing the calculation result of the CPU 19, and the like.

The CPU 19 calculates the deviation of the unmanned forklift 1 from the electromagnetic induction wire based on the detection signal of the pickup coil 3. Then, based on the calculation result, the drive circuit 22 is arranged to correct the deviation from the electromagnetic induction wire.
The steering motor 15 is driven and controlled by. Also, C
The PU 19 inputs the signal from the mark plate sensor 4 and determines the operation information of the mark plate. That is,
Based on the operation information judged from the arrangement pattern of the mark plate, the drive circuit 23 causes the traveling motor 16
Drive control.

Then, the CPU 19 drives and controls the electromagnetic control valve V by the drive circuit 25 in order to carry out the loading and unloading according to the control program. The electromagnetic control valve V expands and contracts the reach cylinder 6, lift cylinder 8 and tilt cylinder 12. Further, the CPU 19 uses the detection signal of the rotary encoder 11 to detect the fork 10
Calculate the elevation position of. Further, according to the instruction of the control program, the driving circuit 24 drives the cargo handling motor 14 to rotate the cargo handling pump 13.

Further, the CPU 19 receives the detection signals from the mark detection sensors 17 and 18 provided on the bottom surface 10a of the forks 10 in the stacking work.
And the positional relationship of the post pallet W0 located below the fork 10 are determined. If both or one of the mark detection sensors 17 and 18 does not detect the mark 32, the CPU 19
Determines that the fork 10 is not in the correct positional relationship with the post pallet W0. Then, the CPU 19 controls the drive of the reach cylinder 6, the steering motor 15, and the traveling motor 16 by the drive circuits 22, 23, 25 by the control program in order to correct the fork 10 to a predetermined position with respect to the post pallet W0. To do.

When the mark detection sensors 17 and 18 simultaneously detect the mark 32, the CPU 19 determines that the fork 10 has been corrected to a predetermined position with respect to the post pallet W0, and ends the correction operation.

Next, the operation of the unmanned forklift 1 and the post pallet configured as described above will be described. 8 and 9 are plan views showing the positional relationship between the post pallet W2 previously placed on the station and the post pallet W3 lifted by the fork 10. At this time, each mark detection sensor 1 of the fork 10
Marks 32 provided on the crosspieces 27a of the post pallet W3 are located directly below the reference numerals 7 and 18, respectively.

The unmanned forklift 1 having the post pallet W3 mounted on the fork 10 detects the mark plate in front of the station and stops. A post pallet W2 is placed on the station. According to the control program, the unmanned forklift 1 first drives the lift cylinder 8 to move the fork 10 to the post pallet W.
Lift to a position higher than 2 by a predetermined amount. Then, the reach cylinder 6 is extended and the fork 10 is moved forward by a predetermined amount.

At this time, if the fork 10 and the post pallet W2 have the positional relationship shown in FIG.
The 0 mark detection sensors 17 and 18 simultaneously detect the mark 32 provided on the upper surface of the post pallet W2. Then, the CPU 19 determines that the post pallet W2 is placed at the regular position, drives the lift cylinder 8, and lowers the fork 10 by a predetermined amount. As a result, the notch 31a formed in the base 31 of each pillar 26 of the upper post pallet W3 fits on the upper end of each pillar 26 of the lower post pallet W2, so that the post pallet W3 is above the post pallet W2. Placed on. After that, the reach cylinder 6 is contracted, the fork 10 is pulled out from the post pallet W3, and the loading operation is completed.

On the other hand, as shown in FIGS. 8 (b), 9 (a), and 9 (b), when the positional relationship between the fork 10 that has been inserted and the lower post pallet W2 is displaced, the fork 1 is
One or both of the zero mark detection sensors 17 and 18 do not detect the mark 32 of the post pallet W2. In this case, the CPU 19 does not move to the operation of loading the post pallet W3, determines the positional relationship in each case, and issues a command to correct the position of the fork 10 in accordance with the position of the post pallet W2. That is, in order to correct the position of the vehicle body of the unmanned forklift 1, the operation amounts of the traveling motor 16 and the steering motor 15 are calculated, and the command signals for performing the operations are given to the respective drive circuits 22 and 23.
Output to. Also, it outputs a command signal for driving the reach cylinder 6 to the drive circuit 25.

The unmanned forklift 1 is instructed by the CPU 19
Corrects the position of the fork 10 and the mark detection sensors 17 and 18 of the fork 10 simultaneously detect the mark 32 of the post pallet W2, the CPU 19 determines the positional relationship between the post pallet W2 and the fork 10 as shown in FIG. When it is determined that the post pallet W3 has been corrected to such a positional relationship, a predetermined operation of placing the post pallet W3 on the post pallet W2 is performed.

As described in detail above, according to this embodiment,
In the post pallet stacking operation of the unmanned forklift 1, the position of the post pallet W2 on which the unmanned forklift 1 is placed first is set to the fork 10 when loading.
This can be easily determined by detecting the pair of marks 26 provided on the upper surface of the post pallet W2 by the pair of mark detection sensors 17 and 18 provided in the.

Therefore, in the stacking work of the post pallets by the unmanned forklift 1, the post pallets can be stacked easily in the vertical direction.
The present invention is not limited to the above-described embodiments, and may be configured as follows, for example, within the scope of the invention.

(1) In the above embodiment, the mark detecting sensor 1 for detecting the post pallet on the bottom surface of the fork 10 is used.
The forks 10 and 18 were buried in symmetrical positions.
The position of embedding is not limited as long as the position of the post pallet W2 below can be determined. For example, in FIGS.
As shown in, the mark detection sensors 34, 35 may be provided in the front-back direction only on one bottom surface 33a of the fork 33. In this case, the mark 3 provided on the post pallet W4
The position of 6 is as shown in FIG. Here, the mark detection sensors 34, 35 provided on one side of the fork 31
The space in the front-back direction is the mark 36 of the post pallet W4.
Equal to the interval.

(2) In the above embodiment, the fork 10 is detected by detecting the position of the post pallet W2 placed first.
The position was corrected so as to match the position of the post pallet W2, but the sensor is also provided on the upper surface of the fork 10 and the detection mark is provided on the lower surface of the post pallet W3. The positional relationship between the fork 10 and the fork 10 may be corrected. (3) In the above embodiment, the unmanned forklift 1 controls cargo handling, but it may be used for stacking in a manned forklift. In this case, the position shift of the post pallet W2 can be warned by a buzzer, a lamp, or the like. (4) The sensor on the fork and the mark on the luggage are
Any form may be used as long as the position of the post pallet can be detected. Further, the number of sensors may be three or more so as to correspond to post pallets of different sizes.

[0034]

As described in detail above, according to the present invention, in the stacking work of the post pallets, the post pallets can be reliably stacked in the vertical direction.

[Brief description of drawings]

FIG. 1 is a side view of an unmanned forklift according to an embodiment.

FIG. 2 is a plan view of the fork.

FIG. 3 is also a side view of the fork.

FIG. 4 is a perspective view of the same post pallet.

FIG. 5 is a plan view of the post pallet.

FIG. 6 is an operation explanatory view of a base portion of the post pallet.

FIG. 7 is a block diagram of an unmanned forklift controller.

8A is a plan view showing a state where a mark detection sensor detects a mark on a post pallet, and FIG. 8B is a plan view showing a state where the mark detection sensor does not detect a mark on a post pallet. is there.

9 (a) and 9 (b) are plan views showing a state in which the mark detection sensor does not detect a mark on the post pallet.

FIG. 10 is a plan view showing a fork of another example.

FIG. 11 is a side view showing the same fork.

FIG. 12 is also a plan view of the post pallet.

FIG. 13 is a plan view showing the outline of a conventional unmanned transport system.

[Explanation of symbols]

10 ... Fork, 10a ... Fork bottom, 17, 18 ...
Mark detection sensor, 32 ... Mark, W0, W1, W2
W3 ... Post pallet.

Claims (1)

[Claims] 1. A mark is provided on a plurality of upper surfaces of a post pallet facing a pair of left and right forks, and mark detection sensors are provided on the lower surfaces of the forks facing the marks, respectively. During the lowering operation, when each mark detection sensor detects the mark of the corresponding post pallet positioned below, the post pallet mounted on the fork is placed on the lower post pallet. Stacking method.