JP2003267695A - Fork withdrawal device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein, under poor flatness of a floor on which a pallet is placed, when forks are withdrawn from inside the pallet, lower surfaces of the forks press on an upper surface of a bottom deck board of the pallet, and if withdrawn in the state, the forks drag the pallet. <P>SOLUTION: A fork withdrawal device comprises a withdrawable time detecting means 31 for detecting a withdrawable time of each of two forks of a forklift truck when the two forks are lowered so that they are withdrawn from a pallet after they place the pallet in a given place, a lowering distance measuring means 33 for measuring a lowering distance over which the two forks are lowered evenly between the former withdrawable time and the latter withdrawable time, and a withdrawal effecting means 38 for withdrawing both two forks from the pallet if the measured lowering distance is within a predetermined distance. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fork removing device for removing a fork from a pallet after placing a pallet carrying a load on a predetermined position.

[0002]

2. Description of the Related Art FIG. 9 shows a side view of an unmanned forklift 1 having an automated cargo handling operation. A mast device 2 is provided at the front of the vehicle body of the unmanned forklift 1.
A drive unit 3 is provided on the front surface of the mast device 2 so as to be vertically movable along the mast device 2.

The drive unit 3 is provided on the front surfaces of the racks 4 and 4 so as to be movable in the left-right direction, and is provided on both sides of a flat plate-shaped support plate 5 provided on the tip side of the drive unit 3. Two substantially L-shaped forks 6 are provided. The two forks 6 are configured to be movable in the front-back direction by driving the main body of the unmanned forklift 1 and in the left-right direction by the drive unit 3.

FIG. 10 shows the construction of a removal sensor A for detecting when each fork 6 can be removed from the pallet 7 after the pallet 7 is placed at a predetermined position by the two forks 6. The removal sensor A is provided on each fork 6, and has a transmissive photoelectric sensor 8 and a rotary lever 9, as shown in FIG.

The rotary lever 9 is rotatably supported by a shaft 10 below a drive unit 3 on the rear end side of the fork 6 via a spring (not shown). Further, the rotary lever 9 has a working surface 13 that comes into contact with the lower surface 12 of the upper deck board 11 of the pallet 7. When the drive unit 3 raises the fork 6 and lifts the pallet 7, the working surface 13 causes the lower surface 1 of the upper deck board 11 of the pallet 7 to move.
When pushed down by 2, the rotary lever 9 rotates clockwise around the shaft 10.

On the other hand, when the drive unit 3 lowers the fork 6 to separate the fork upper surface 14 from the lower surface 12 of the upper deck board 11 of the pallet 7, the rotary lever 9 returns to its original position. .

A switch piece 15 is provided on the rotary lever 9 so as to face the working surface 13. FIG. 11 is a side view of each of the transmissive photoelectric sensors 8 and FIG. 12 is a partial sectional front view thereof. As shown in FIGS. 11 and 12, a slit 16 is formed in the lower part of the transmission type photoelectric sensor 8, and an inner surface of the slit 16 faces the light emitting side sensor 17 and the light receiving side. A sensor 18 is provided.

Then, the switch piece 15 rotates in accordance with the rotation of the rotary lever 9, and the switch piece 15 passes or blocks light between the light emitting side sensor 17 and the light receiving side sensor 18. Thus, each of the above elements is configured. When the upper surface 14 of the fork is separated from the lower surface 12 of the upper deck board 11 of the pallet 7 by a predetermined clearance, light passes from the light emitting side sensor 17 to the light receiving side sensor 18, and the fork 6 is moved from the pallet 7 to the pallet 7. The removal sensor A is configured so that it can be detected that it can be removed.

Next, the operation of the removal sensor A will be described. The drive unit 3 of the forklift 1 aligns each fork 6 with the insertion position of the pallet 7 and creates a gap 20 in the pallet 7.
, And each fork 6 is lifted. At that time, in each fork 6, the action surface 13 of the rotary lever 9 is moved to the pallet 7
Since it is pressed by the lower surface 12 of the upper deck board 11, the rotary lever 9 rotates about the shaft 10 in the clockwise direction.

When the rotary lever 9 rotates clockwise,
Along with that, the switch piece 15 also rotates clockwise. With this rotation, the switch piece 15 is inserted into the slit 16 of the transmission photoelectric sensor 8. Then, the passage of light from the light emitting side sensor 17 in the slit 16 to the light receiving side sensor 18 is blocked. As a result, the transmissive photoelectric sensor 8 is turned on.
The signal is output to the control device described later. When an ON signal is received from each transmission photoelectric sensor 8 provided on each of the two forks 6 in this way, the control device described later recognizes that each fork 6 lifts the pallet 7. Then, the drive unit 3 places the pallet 7 at a predetermined position.

Next, a case where the forks 6 are pulled out from the pallet 7 will be described with reference to FIGS. 13 and 14. FIG. 13 is a block diagram of the control device when the forks 6 are pulled out from the pallet 7. FIG. 14 is a flowchart showing the operation procedure of the removal control when the forks 6 are pulled out from the pallet 7.

When the forks 6 are pulled out of the pallet 7, the forklift 1 places the pallet 7 at a predetermined position and then further lowers the forks 6 to lower the forks 6 (step 101). . Then, the upper surface 14 of each fork 6 separates from the lower surface 12 of the upper deck board 11 of the pallet 7. At this time, in the removal sensor A provided on each fork 6, the rotary lever 9 rotates counterclockwise around the shaft 10 and returns to the original position. Then, the upper surface 14 of each fork 6 is separated from the lower surface 12 of the upper deck board 11 of the pallet 7, and the switch piece 15 provided on the rotary lever 9 is also rotated counterclockwise, so that the light emitting side sensor in the slit 16 is located. The light passes from 17 to the light receiving side sensor 18.

Thus, regarding the right fork 6R,
When the light passes from the light emitting side sensor 17 to the light receiving side sensor 18, the removal sensor AR provided on the right fork 6R becomes
An OFF signal indicating that the right fork 6R can be removed from the gap 20 of the pallet 7 is transmitted to the removal possible time detection means 51. Similarly, with respect to the left fork 6L, when light passes from the light emitting side sensor 17 to the light receiving side sensor 18, the removal sensor AL provided on the left fork 6L removes the left fork 6L from the gap 20 of the pallet 7. An OFF signal indicating that it is possible is transmitted to the removal possible detection means 51.

The removal possible detection means 51 is a removal sensor A
It is detected whether or not the OFF signal is received from the R and the removal sensor AL (step 102). The lift continues to descend until the detachable state detection means 51 receives the OFF signal from both the detachment sensors A, and the two forks 6 accordingly descend.

When the withdrawal possible detection means 51 receives the OFF signal from both the withdrawal sensor AR and the withdrawal sensor AL (step 102), the lift descent stop means 52 stops the descent of the lift (step 103). When the descent of the lift is stopped, the descent of the left and right forks 6 is stopped. When it is confirmed that the fork has stopped descending, the removal executing means 53 removes the left and right forks 6 from the pallet 7 (step 104).

[0016]

[Problems to be Solved by the Invention] As shown in FIG.
When the pallet 7 is placed on the pallet 107, the pallet 107 is usually installed on the floor P in a horizontal state, and the pallet 7 is placed on the pallet 107. However, as shown in FIG. 16, for example, there are cases where the pallet 107 is placed on the uneven floor R and the pallet 7 must be placed on the pallet 107.

In the case shown in FIG. 16, the right fork 6R
Although the left fork 6L can be removed from the pallet 7 earlier than the left fork 6L, when the right fork 6R can be removed, the left fork 6L cannot be removed yet. That is, even if a predetermined clearance is secured between the upper surface 14 of the right fork 6R and the lower surface 12 of the upper deck board 11 of the pallet 7, the upper surface 14 of the left fork 6L and the lower surface of the upper deck board 11 of the pallet 7 are formed. Predetermined clearance is not yet secured between 12 and 12. Then, the lift is lowered so that a predetermined clearance is secured between the upper surface 14 of the left fork 6L and the lower surface 12 of the upper deck board 11 of the pallet 7.

When a predetermined clearance is secured between the upper surface 14 of the left fork 6L and the lower surface 12 of the upper deck board 11 of the pallet 7 and the left fork 6L can be removed, the two forks are removed. The fork 6 can be removed. However, in the case where the floor R as shown in FIG. 16 has unevenness, when the left fork 6L can be removed, the right fork 6R is in a state PS in which the lower deck board upper surface 22 of the pallet 7 is pressed. There are cases.

At this time, conventionally, the removable detection means 51 receives the OFF signal from both the removal sensor AR and the removal sensor AL provided on each of the left and right forks 6, so that the left and right forks are received. It is judged that 6 can be removed.

Then, the left and right forks 6 are pulled out from the pallet 7. As the right fork 6R presses the lower deck board upper surface 22 of the pallet 7 as described above, the left and right forks 6 are left as they are. When 6 is pulled out from the pallet 7, the right fork 6R drags the pallet 7 in the pulling direction. As a result, an accident such as dropping the cargo on the pallet 7 and damaging it occurs.

In addition, the upper deck board and the lower deck board of the pallet may have different thicknesses, or the clearance between the upper deck board and the lower deck board of the pallet may differ accordingly. Further, the forks of the forklift may be different in height, or the forklift itself may be tilted due to poor floor accuracy. Also in these cases, similarly to the above, conventionally, when the OFF signal is issued from all the removal sensors provided on each fork,
Although each of the forks 6 is removed, there may be a problem that one of the forks drags the pallet when the forks are removed.

In view of the above conventional problems, the present invention has an object of providing a fork removing device for removing a fork from a pallet so as not to drag the pallet when the fork is removed.

[0023]

A fork removing device of the present invention is a fork removing device for removing a plurality of forks from an insertion port of a pallet, and when the fork descends with respect to the pallet, the fork removing device descends. Detecting means for detecting that the fork is separated from the upper surface of the insertion opening, and the detecting means is provided in each of the plurality of forks,
From receiving the signal from the detecting means that was the earliest to the detection, until receiving the signal from the detecting means that was the slowest, computing means for computing how much the fork detected earliest descended, Comparison operation means for performing a comparison operation of the descent distance of the fork obtained by the operation means and an allowable descent distance stored in the storage means in advance; and when the descent distance of the fork is shorter than the allowable descent distance, Control means for outputting a signal for pulling out the fork from the insertion port of the pallet.

With the above construction, when the descending distance of the fork obtained by the computing means is shorter than the allowable descending distance, all of the plurality of forks are removed from the pallet, so that the fork is palletized. It is possible to prevent the pallet from dragging when it is removed from the pallet.

Further, the fork removing device of the present invention is provided with a warning means for issuing a warning when the descending distance of the fork calculated by the calculating means is longer than the allowable descending distance.

The warning means warns that there is a danger of dragging the pallet if the fork is removed as it is, so that the pallet dragging and accidents associated therewith can be prevented.

According to the present invention, even if the detection means of each fork detects that all the forks are separated from the upper surface of the insertion port, the withdrawal operation is not performed by itself, and further,
It is to calculate how much the first detected fork descends until the last fork is detected, and to compare and calculate whether or not the descending distance is an allowable descending distance.

The permissible descent distance is a distance determined that if the fork detected first falls further, the fork will come into contact with the pallet when the fork is removed. The height of the insertion port and the thickness of the fork are set and stored arbitrarily.

If, as a result of the comparison calculation by the comparison calculation means, the first descending distance of the fork is larger than the allowable descending distance, for example, all the detecting means move the forks away from the upper surface of the insertion port. Even if it is detected that it is present, it is not removed.

When the fork removal device is attached to a manned forklift, the warning means is also attached at the same time to notify the operator that the fork will not be removed as it is. As a warning method by the warning means, it is conceivable to generate a sound or a light. The operator who receives the warning can carry out a safe cargo handling work without dragging the pallet when the fork is removed, by re-mounting the pallet again or changing the pallet storage location.

Also, when the fork removing device is attached to an automatic guided vehicle, if the descending distance of the first fork is larger than the allowable descending distance as a result of the comparison calculation by the comparison calculating means, for example, all Even if the detection means determines that the fork is away from the upper surface of the insertion port, the fork is not removed. In such a case, the automatic guided vehicle interrupts the work and performs a control operation such as issuing a contact signal to a monitoring center or the like monitored by a person or resetting the pallet.

The upper surface of the insertion port means the lower surface of the upper deck board of the pallet.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The present invention is a fork removal device, and the entire structure of the forklift and the removal sensor are the same as those described in the conventional example, and therefore detailed description thereof will be omitted. Further, elements having the same functions as those of conventional elements are designated by the same reference numerals, and detailed description thereof will be omitted.

(Embodiment 1) First, a fork removing device according to Embodiment 1 of the present invention will be described.

In the present embodiment, an unmanned forklift having two forks is taken as an example.
The control when the book fork is removed from the pallet will be described.

FIG. 1 is a block diagram of a fork removing device according to the first embodiment of the present invention. FIG. 2 is a flow chart showing an operation procedure of the removal control when the fork 6 is pulled out from the pallet 7, which is performed by the fork removal device of the present embodiment.

Like the conventional fork removing device, the fork removing device of the first embodiment sends the above-mentioned ON signal and OFF signal separately from each of the removing sensors AR and AL provided on the left and right forks 6, respectively. obtain. The removal sensors AR and AL correspond to the detection means of claim 1. Then, the ON signal and the OFF signal are input to the detachable time detecting means 31.

As in the conventional case, when the removal sensor AR sends the OFF signal to the removal possible detection means 31, the fork 6R provided with the removal sensor AR is provided.
Upper surface 14 of pallet 7 and lower surface 1 of upper deck board 11 of pallet 7
It is assumed that a predetermined clearance 21 (see FIG. 3) is secured between the fork 6 and the fork 6R and the fork 6R can be removed from the pallet 7. Similarly, when the removal sensor AL sends the OFF signal to the removal possible detection means 31, the fork 6 provided with the removal sensor AL is provided.
It is assumed that a predetermined clearance 21 (see FIG. 3) is secured between the upper surface 14 of the L and the lower surface 12 of the upper deck board 11 of the pallet 7 so that the fork 6R can be removed from the pallet 7.

Further, in the first embodiment, the predetermined pallet 107 is placed on the floor R having the unevenness as shown in FIG. 16, and the pallet 7 having the predetermined load is placed on the pallet 107. A situation where the fork is placed and the two forks are removed from the pallet 7 will be described with reference to FIGS. 3 and 4. 3 and 4, only the pallet 7 and the two forks 6 are shown in cross section in order to simplify the description.

When the pallet 7 with a predetermined load is placed on the pallet 107, the lift is lowered (step 1) and the two forks 6 are lowered accordingly. Thus, the floor R having the unevenness as shown in FIG.
After the pallet 7 is placed on the pallet 107 located above, when the lift is lowered, the upper surface 14 of the right fork 6R and the upper deck board 11 of the pallet 7 are first moved as shown in FIG. Predetermined clearance 2 with the lower surface 12
1 is secured, and the right fork 6R can be removed.

When the right fork 6R can be removed in this way, the removal sensor AR provided on the right fork 6R sends the above-mentioned OFF signal indicating that the removal is possible to the removal possible detection means 31. . Then, the detachable state detecting means 31 outputs to the descending distance measuring means 33 the first detachable information which means that one of the forks 6 is detachable. The descending distance measuring means 33
When the above first removable information is sent (below,
The height of the lift "when it can be removed for the first time" is detected. The height of the lift is measured by the encoder 34.

By the way, when the right fork 6R can be removed, the upper surface 14 of the left fork 6L and the pallet 7 are removed.
A predetermined clearance 21 is not yet secured between the upper deck board 11 and the lower surface 12 of the upper deck board 11. Therefore,
The OFF signal is not transmitted from the removal sensor AR provided on the left fork 6L to the removal possible detection means 31. Then, since all the removal sensors have not transmitted the OFF signal to the removal possible detection means 31 (step 2), the lifts for uniformly raising and lowering the left and right forks 6 continue to descend.

After that, when the lift is further lowered, as shown in FIG.
As shown by the solid line, a predetermined clearance 21 is secured between the upper surface 14 of the left fork 6L and the lower surface 12 of the upper deck board 11 of the pallet 7, and the left fork 6L can be removed. The position of the fork 6 drawn by the broken line in FIG. 4 indicates the position of the fork 6 shown in FIG. That is, it shows the positions of the left and right forks 6 when only the right fork 6R can be removed.

When the left fork 6L becomes removable as described above, the removal sensor AL provided on the left fork 6L transmits the OFF signal indicating that the removal is possible to the removal possible detection means 31. To do. Then, the removable detection means 31 detects that the OFF signals have been received from all the removable sensors (step 2). Then, the removal possible time detection means 31 transmits a stop signal for stopping the lowering of the lift to the lift lowering stop means 32, and the lift lowering stop means 32 stops the lowering of the lift based on the stop signal. (Step 3).

When the left fork 6L can be pulled out, the detachable state detecting means 31 is moved downward by the descending distance measuring means 33.
In response to this, the final removable information indicating that the other fork 6 has become removable is output. Then, the descending distance measuring means 33 detects the height of the lift at the time when the last removal possible information is sent (hereinafter, referred to as “the last removal possible”), and from the time when the first removal is possible. The descending distance X of the lift until the last removal is possible is measured (step 4). That is, the descending distance measuring means 33 measures the descending distance X of the left and right forks 6 that has uniformly descended from the time when the first withdrawal is possible to the time when the last withdrawal is possible. The descending distance measuring means 33 corresponds to the calculating means of claim 1.

In this way, when the descending distance X of the lift (left and right forks 6) from the time when the first removal is possible to the time when the last removal is possible is measured, the comparison means 36 causes the storage means 35.
The predetermined distance “a” stored in the above is compared with the descending distance X measured by the descending distance measuring means 33.
The comparison means 36 corresponds to the comparison calculation means of claim 1. Further, the storage means 35 corresponds to the storage means in claim 1. The predetermined distance a stored in the storage means 35 is smaller than the value obtained by subtracting the thickness of the fork 6 from the gap 20 between the upper deck board and the lower deck board of the pallet 7, The lower deck board 1 of the pallet 7 when the lower surface of the fork 6 that can be removed is the last fork 6 that can be removed.
It is a value for determining whether or not it is in contact with the upper surface of 9.

Then, when the descending distance X is less than or equal to the predetermined distance a (hereinafter, referred to as "when X≤a") (step 5), the comparing means 36 causes the left and right forks 6 to move to the pallet 7.
Removal execution means 37 for removing the removal execution signal for removing
And the removal executing means 37 removes the left and right forks 6 from the pallet 7 (step 6). The removal execution means 37 corresponds to the control means of claim 1.

On the other hand, when the descending distance X is larger than the predetermined distance a (hereinafter, referred to as "when X>a") (step 5), the comparing means 36 outputs a warning signal to the warning means 38 and outputs the warning signal. The warning means 38 audibly or visually gives a warning by using sound or lighting an emergency light (step 7). The warning means 38 corresponds to the warning means of claim 2.

As described above, the control device of the present embodiment compares the distance a stored in the storage means 35 with the descending distance X measured by the descending distance measuring means 33, and X ≦ a. Sometimes, from pallet 7 to left and right forks 6
Since the proper distance a is stored in the storage means 35, the pallet 7 can be prevented from being dragged when the left and right forks 6 are removed from the pallet 7.

When X> a, the left and right forks 6
Since a warning is issued without removing the pallet 7 from the pallet 7, the operator knows that if the left and right forks 6 are removed from the pallet 7, the pallet 7 will be dragged. Can be applied.

(Second Embodiment) Next, a second embodiment of the present invention will be described.

FIG. 5 shows four forks 6a, 6b, 6
It is a top view showing the state where four pallets 7 are held by a forklift having c and 6d. The forklift lifts and lowers the four forks 6a, 6b, 6c, 6d uniformly. Then, each of the forks 6 holds four pallets 7 in the front, rear, left and right directions and transports them at once. Further, each fork 6 is provided with a removal sensor A as in the conventional case.

FIG. 6 is a block diagram of a fork removing device having the above-mentioned four forks 6. The elements having the same functions as those described in Embodiment 1 with reference to FIG. 1 are designated by the same reference numerals. In the second embodiment, the control by the fork removal device of the second embodiment will be described with reference to the flowchart shown in FIG.

Now, in the second embodiment, four pallets 7 are placed at predetermined places, and four pallets 7 are placed in the direction of the arrow in FIG.
Two pallets 7 on the front side when looking at one pallet 7
, But it looks as shown in FIG. That is, of the two pallets 7 on the front side, the pallet 7a on the right side
However, like the pallet 7 described in the first embodiment, it is assumed that the left side is tilted so that the left side is lower than the right side, and the pallet 7 is placed at a predetermined place. It is assumed that the other pallets 7b, 7c, 7d are placed horizontally.

When the four pallets 7 are placed at the predetermined places in this way, the lift is lowered to lower the four forks 6 for the purpose of removing the four forks 6 from the pallet 7. (Step 1).

The removal sensor A provided on each of the four forks 6 corresponds to the fork 6 on which it is provided.
When a predetermined clearance 21 is secured between the upper surface 14 of the fork 6 and the lower surface 12 of the upper deck board 11 of the pallet 7 with which the upper surface of the fork 6 is in contact (see FIG. 3), the fork 6 can be removed. , OFF meaning removable
The signal is transmitted to the detecting means 41 when the signal can be removed. The removal sensor A corresponds to the detection means of claim 1.

As described with reference to FIG. 7, among the four pallets 7, the pallets 7b, 7c and 7d are horizontally mounted, but the pallet 7a on the front right side is lower than the right side on the left side. Since the lift is lowered, the forks 6a and 6b of the four forks 6 can be removed first.

Then, the withdrawal sensors Aa and Ab provided on the forks 6a and 6b output the OFF signal to the withdrawable detection means 41. Then, the detachable state detecting means 41 transmits to the descending distance measuring means 43 the first detachable information which means that the forks 6a and 6b can be removed. The descending distance measuring means 43 detects the height of the lift when the first removable information is sent (hereinafter, referred to as "first removable time"). The height of the lift is measured by the encoder 44.

By the way, even if the forks 6a and 6b can be removed, the forks 6c and 6d cannot be removed yet (step 2), so the lift is further lowered.

When the lift is further lowered, next,
The fork 6d can be removed, and the removal sensor Ad provided on the fork 6d outputs the OFF signal to the removal possible detection means 41. The detachable time detecting means 41 is different from the descending distance measuring means 43 with respect to the fork 6
Removable information indicating that d is removable is output. However, even if the fork 6d can be removed as described above, the fork 6c cannot be removed yet (step 2), and therefore the lift is further lowered.

After that, when the lift is further lowered, FIG.
As shown by the solid line, a predetermined clearance 21 is secured between the upper surfaces 14 of all the forks 6 including the forks 6c and the lower surface 12 of the upper deck board 11 of the pallet 7, and all the forks 6 can be removed. . The position of the fork 6 drawn by the broken line in FIG. 8 indicates the position of the fork 6 shown in FIG. That is, the forks 6a, 6
The position of each fork 6 when only b can be removed is shown.

As described above, when the fork 6c is finally removable, the removal sensor Ac provided on the fork 6c detects the OFF signal when the fork 6c can be removed.
Send to 1. Then, the removal possible time detection means 41 detects that the OFF signals have been received from all the removal sensors (step 2). Then, the removable detection means 41
Transmits a stop signal for stopping the lowering of the lift to the lift lowering stop means 42, and the lift lowering stop means 42 stops the lowering of the lift based on the stop signal (step 3).

When the fork 6c can be removed,
The detachable state detecting means 41 transmits the last detachable information indicating that the fork 6c is detachable to the descending distance measuring means 43. Then, the descending distance measuring means 43 detects the height of the lift at the time when the last removable information is transmitted (hereinafter, referred to as “the last removable time”), and from the first removable time. The descending distance X of the lift until the last removal is possible is measured (step 4). That is, the descending distance measuring means 43 measures the descending distance X of each fork 6 that has descended uniformly from the time when the first withdrawal is possible to the time when the last withdrawal is possible. The descending distance measuring means 43 corresponds to the comparison calculating means of claim 1.

In this way, when the descending distance X of the lift (four forks 6) from the time when the first removal is possible to the time when the last removal is possible is measured, the comparison means 46 causes the storage means 45.
The predetermined distance “a” stored in the above is compared with the descending distance X measured by the descending distance measuring means 43.
The comparison means 46 corresponds to the comparison calculation means of claim 1,
The storage means 45 corresponds to the storage means in claim 1. The predetermined distance a stored in the storage unit 45 is
Is a value smaller than the value obtained by subtracting the thickness of the fork 6 from the gap 20 between the upper deck board and the lower deck board of the pallet 7, and the lower surface of the fork 6 that can be removed first can be removed last. It is a value for determining whether or not the fork 6 that has become contacted with the upper surface of the lower deck board 19 of the pallet 7 is in contact with it.

Then, when the descending distance X is less than or equal to the predetermined distance a (hereinafter referred to as "when X≤a") (step 5), the comparing means 46 causes the forks 6 to be removed from the pallet 7. The removal execution signal is output to the removal execution means 47, and the removal execution means 47 removes all four forks 6 from the pallet 7 (step 6). The removal executing means 47 corresponds to the control means of claim 1.

On the other hand, when the descending distance X is larger than the predetermined distance a (hereinafter referred to as "when X>a") (step 5), the comparing means 46 outputs a warning signal to the warning means 48, and outputs the warning signal. The warning means 48 gives a warning by using a sound or turning on an emergency light (step 7). The warning means 48 corresponds to the warning means in claim 2.

As described above, the fork removing device according to the second embodiment has the distance a stored in the storage means 45.
And the descending distance X measured by the descending distance measuring means 43 are compared, and when X ≦ a, the four forks 6 are removed from the pallet 7, so that the appropriate distance a is stored in the storing means 4
If it is stored in 5, the four forks 6 are placed on the pallet 7
It is possible to prevent the pallet 7 from being dragged when being removed from the pallet.

When X> a, the four forks 6
Since a warning is issued without removing the pallet 7 from the pallet 7, the operator knows that if the four forks 6 are removed from the pallet 7, the pallet 7 will be dragged. Can be applied.

[0069]

As is apparent from the above description, the present invention can provide a fork removing device for removing a fork from a pallet so that the pallet is not dragged when the fork is removed.

[Brief description of drawings]

FIG. 1 is a block diagram of a fork removing device according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a control procedure of the fork removal device in the embodiment of the present invention.

FIG. 3 is an operation explanatory diagram showing a state in which the left fork has not secured clearance.

FIG. 4 is an operation explanatory view showing a state in which all forks have secured clearance.

FIG. 5 is a plan view of a fork portion of a lift having four forks.

FIG. 6 is a block diagram of a fork removing device according to a second embodiment of the present invention.

FIG. 7 is an operation explanatory view showing a state in which one fork does not secure a clearance.

FIG. 8 is an operation explanatory view showing a state in which all forks have secured clearance.

FIG. 9: Side view of forklift

FIG. 10 is a configuration diagram of the removal sensor portion of FIG.

FIG. 11 is a side view of the main part of the removal sensor.

12 is a partially sectional front view of FIG.

FIG. 13 is a block diagram of a conventional fork removal device.

FIG. 14 is a flowchart showing a control procedure of a conventional fork removal device.

FIG. 15 is an explanatory diagram showing a pallet installed horizontally.

FIG. 16 is an illustration showing a pallet installed at an angle.

[Explanation of symbols]

1 forklift 6 forks 7 pallets 11 Deck board on pallet 12 Pallet upper deck board lower surface 19 Pallet under deck board 20 pallet gap 21 Predetermined clearance 22 Upper surface of deck board under pallet 31, 41 Detachable detection means 32, 42 Lift lowering stop means 33, 43 descending distance measuring means 35, 45 storage means 36,56 Comparison means 37, 47 Removal execution means 38,48 Warning means A removal sensor X fork descent distance a predetermined distance

Claims (2)

[Claims] 1. A fork removing device for removing a plurality of forks from an insertion port of a pallet, wherein when the forks descend relative to the pallet, it is detected that the descended forks are separated from an upper surface of the insertion port. Detecting means and the detecting means are provided on each of the plurality of forks, and between the receiving of the signal from the detecting means having the earliest detection and the receiving of the signal from the detecting means having the latest detection, Computation means for computing how much the fork detected earliest has descended, and comparison computation means for carrying out comparison computation of the fork descent distance obtained by the computation means and the allowable descent distance stored in the storage means in advance. And a control for issuing a signal for removing the fork from the insertion port of the pallet when the descending distance of the fork is shorter than the allowable descending distance. Fork removal device, characterized in that it comprises a stage, a. 2. The fork removing device according to claim 1, further comprising warning means for issuing a warning when a descending distance of the fork is longer than an allowable descending distance.