JP2009120273A - Conveying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conveying device capable of performing an accurate conveying operation irrespective of the weights and loading positions of cargos on a fork. <P>SOLUTION: The tilt angle θ of an upper fork part is recognized by an output from a tilt sensor (S1). When the tilt angle θ is lower than a threshold B for low speed (S2), the amount of deflection of the fork is determined to be negligible, and the forward and backward movement of the fork 1 is performed in a normal speed pattern P1 (S3). When the tilt angle θ is equal to or higher than the threshold B for low speed and equal to or lower than a threshold A for stoppage (S4), the fork is determined to have an amount of deflection that is not negligible, and the forward and backward movement of the fork is performed in a low speed pattern P2 (S5). When the tilt angle θ exceeds the threshold A for stoppage, the amount of deflection of the fork is determined to exceed the limit, and the movement of the fork is stopped (S6). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a transfer device, and more particularly to a transfer device that transfers a load by sliding a fork with a drive device.

  2. Description of the Related Art Conventionally, a slide fork type transfer device that is mounted on a carriage that can be raised and lowered and transfers a load in a stacker crane or the like of an automatic warehouse is known. For example, as shown in FIG. 9A, this type of transfer device includes a lower fork portion 1a, a middle fork portion 1b that can move forward and backward with respect to the lower fork portion 1a, and a middle fork portion 1b. A fork 1 having an upper and lower upper fork portion 1c is provided, and a lower fork portion 1a is fixed on a carriage (not shown). The lower fork portion 1a, the middle fork portion 1b and the upper fork portion 1c are coupled to each other via a chain or the like, and are shown in FIG. 9B by driving the electric motor 2 disposed on the lower fork portion 1a. As shown, the middle fork portion 1b moves forward and backward with respect to the lower fork portion 1a and the upper fork portion 1c moves forward and backward with respect to the middle fork portion 1b, and the load W placed on the upper fork portion 1c moves. Done.

  A stop dog 3 is fixed to an intermediate portion of the middle fork portion 1b in the advancing / retreating direction, and a stop sensor 4 for detecting the stop dog 3 is disposed at the tip of the lower fork portion 1a. As shown in c), when the stop sensor 4 detects the stop dog 3, the movement of the fork 1 by the electric motor 2 is stopped.

Here, when there is no load W on the upper fork portion 1c or when the weight of the load W can be ignored, as shown in FIG. 9C, the fork can be moved even if the upper fork portion 1c is advanced. 1 will not bend. However, since the fork 1 is actually bent due to the weight of the load W, when the upper fork portion 1c is advanced, the stop position accuracy of the fork 1 is reduced due to the load fluctuation caused by the bending, There is a possibility that the electric motor 2 is overloaded. Further, when the fork 1 has a large amount of deflection, the tip of the upper fork 1c may drop too much and the load W may not be transferred normally.
Therefore, in Patent Document 1, load weight information is obtained based on a driving power value of a lifting motor that lifts and lowers a carriage, and a fork advance / retreat operation is started based on this weight information until deceleration is started. A transfer device for adjusting the elapsed time for starting deceleration is disclosed.

JP 2007-119136 A

However, even if the load has the same weight, the moment acting on the fork differs depending on the mounting position on the fork. For example, when the load is placed on the tip side of the fork, The amount of bending of the fork becomes larger than when the load is placed, and the fork stop position accuracy is lowered, or the fork advance / retreat motor may be overloaded.
Also, if the fork is greatly bent due to an excessively heavy load and the tip of the fork is lowered too much, the load cannot be transferred normally even if the elapsed time for starting deceleration is adjusted. The bug is not solved.
Furthermore, since the amount of deflection of the fork varies not only with the weight of the load but also with the center of gravity, temperature, etc. of the load, it is difficult to grasp the amount of deflection of the fork only with the weight information of the load.

  The present invention has been made to solve such a conventional problem, and provides a transfer device capable of performing a high-accuracy transfer operation regardless of the weight of the load on the fork and the mounting position. The purpose is to provide.

  The transfer device according to the present invention is a transfer device that transfers a load by sliding a fork with a drive device, and is detected by an inclination sensor that is disposed on the fork and detects an inclination angle of the fork, and an inclination sensor. And a control device that controls the moving speed of the fork by the driving device in accordance with the inclination angle of the fork.

Preferably, the control device stops the movement of the fork when the inclination angle of the fork detected by the inclination sensor exceeds a preset stop threshold value.
Further, the control device moves the fork in a predetermined normal speed pattern when the inclination angle of the fork detected by the inclination sensor is lower than the low speed threshold value set in advance to a value smaller than the stop threshold value. When the speed is lower than the low speed threshold and lower than the stop threshold, the fork can be moved in a predetermined low speed pattern set at a speed lower than the normal speed pattern.

  According to the present invention, since the control device controls the moving speed of the fork by the driving device according to the inclination angle of the fork detected by the inclination sensor, high accuracy can be achieved regardless of the weight of the load on the fork and the mounting position. It is possible to perform the transfer operation.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 shows a transfer apparatus according to an embodiment of the present invention. This transfer device is mounted on a liftable carriage in a stacker crane of an automatic warehouse. The transfer device includes a lower fork portion 1a fixed on a carriage (not shown), a middle fork portion 1b that can move forward and backward with respect to the lower fork portion 1a, and an upper fork portion 1c that can move forward and backward with respect to the middle fork portion 1b. The fork 1 is provided. The lower fork portion 1a, the middle fork portion 1b and the upper fork portion 1c are coupled to each other via a chain or the like, and an electric motor 2 for causing the lower fork portion 1a to move the fork 1 back and forth is provided. Has been placed.

A stop dog 3 is fixed to an intermediate portion of the middle fork portion 1b in the advancing / retreating direction, and a stop sensor 4 for detecting the stop dog 3 is disposed at the tip of the lower fork portion 1a. The upper fork portion 1c is provided with an inclination sensor 5 for detecting the inclination angle of the upper fork portion 1c. As the tilt sensor 5, for example, a sensor of a type that linearly outputs the tilt angle with a voltage value by detecting the liquid level of the liquid contained therein can be used.
A motor drive circuit 6 is electrically connected to the electric motor 2, and the electric motor 2 and the motor drive circuit 6 form a drive device of the present invention. Further, a CPU 7 is electrically connected to the motor drive circuit 6. The CPU 7 constitutes the control device of the present invention, and outputs from the stop sensor 4 and the tilt sensor 5 are input to the CPU 7. The CPU 7 stores in advance a normal speed pattern P1 and a low speed pattern P2 as shown in FIG. The low speed pattern P2 is set at a lower speed than the normal speed pattern P1. Further, the CPU 7 is preset with a stop threshold A relating to the inclination angle of the upper fork portion 1c and a low speed threshold B set to a value smaller than the stop threshold A.

  Next, the loading operation of the transfer apparatus according to this embodiment will be described with reference to the flowchart of FIG. When the electric motor 2 is driven in a state where the load W is placed on the upper fork portion 1c as shown in FIG. 1, the middle fork portion with respect to the lower fork portion 1a as shown in FIG. As 1b advances and retreats, the upper fork portion 1c advances and retreats with respect to the middle fork portion 1b, and the load W moves as the upper fork portion 1c moves.

At this time, the CPU 7 recognizes the inclination angle θ of the upper fork portion 1c based on the output from the inclination sensor 5 in step S1 of FIG. 3, and in step S2, the inclination angle θ is set for a low speed set in advance. Compare with threshold B.
If the inclination angle θ of the upper fork portion 1c is below the low speed threshold B as a result of the comparison, the CPU 7 determines that the amount of bending of the fork 1 is negligible, and stores it in advance in step S3. The electric motor 2 is driven by the motor drive circuit 6 so that the fork 1 is moved back and forth at the normal speed pattern P1. As a result, the load W can be quickly transferred according to the normal speed pattern P1. Then, as shown in FIG. 5, when the stop dog 3 of the middle fork portion 1b is detected by the stop sensor 4 disposed in the lower fork portion 1a, the movement of the fork 1 by the electric motor 2 is stopped, and the load W is transferred to a shelf or the like (not shown).

On the other hand, if the inclination angle θ of the upper fork portion 1c is equal to or greater than the low speed threshold value B as a result of the comparison in step S2, the process proceeds to step S4, and this time, the inclination angle θ is set to be used for stopping. Compare with threshold A.
Then, as shown in FIG. 6, if the inclination angle θ of the upper fork portion 1 c is equal to or smaller than the stop threshold value A, the CPU 7 determines that the fork 1 has a deflection amount that cannot be ignored. In step S5, the electric motor 2 is driven by the motor drive circuit 6 so that the fork 1 is moved back and forth with the low-speed pattern P2 stored in advance. Thereby, the transfer operation of the load W is performed according to the low speed pattern P2 set to a speed lower than the normal speed pattern P1. For this reason, it is possible to prevent a problem that the accuracy of the stop position is lowered when the fork 1 is pushed out, or the electric motor 2 is overloaded when the fork 1 is retracted.

  As a result of the comparison in step S4, as shown in FIG. 7, if the inclination angle θ of the upper fork portion 1c exceeds the stop threshold A, the CPU 7 determines that the amount of bending of the fork 1 exceeds the limit. In step S6, the drive of the electric motor 2 is stopped by the motor drive circuit 6 so that the movement of the fork 1 is urgently stopped. For this reason, it is possible to prevent the forward and backward movement of the fork 1 from being continued in a state where the load W cannot be transferred normally, and it is possible to avoid interference between the load W and the shelf in advance. It becomes.

The loading operation has been described above, but the loading operation can be performed in the same manner.
In order to detect the amount of bending of the fork 1, the inclination sensor 5 is preferably arranged at the tip of the upper fork 1c. For this reason, for example, in the fork 1 that moves forward and backward in both directions and transfers the load to the shelves on both sides, as shown in FIG. 8, the upper fork portion 1c has both ends in the forward and backward direction. Inclination sensors 5a and 5b are arranged, and the inclination sensor on the tip side can be selected and used according to the transfer direction.

In the above embodiment, the CPU 7 stores two types of speed patterns, the normal speed pattern P1 and the low speed pattern P2. However, three or more types of speed patterns are stored, and the inclination angle θ of the upper fork portion 1c is stored. Any one of the speed patterns may be selected according to the above. Alternatively, instead of storing a plurality of types of speed patterns in advance, the CPU 7 may be configured to calculate a speed pattern corresponding to the inclination angle θ.
Further, the fork 1 has three fork parts including a lower fork part 1a, a middle fork part 1b, and an upper fork part 1c. However, two fork parts or four or more fork parts are configured to move forward and backward. Fork may be used.
In the above embodiment, the transfer device mounted on the stacker crane has been described. However, the present invention is not limited to this, and the present invention is a slide fork type transfer mounted on an unmanned forklift, a tracked carriage, or the like. It can also be applied to a mounting device.

It is a figure which shows the structure of the transfer apparatus which concerns on embodiment of this invention. It is a graph which shows the speed pattern of the fork advance / retreat operation memorize | stored beforehand by CPU. It is a flowchart which shows operation | movement of embodiment. It is a side view which shows the mode of a fork movement in case the amount of bending of a fork can be disregarded. It is a side view which shows the state which extruded the fork. It is a side view which shows the mode of a fork movement in case the fork has the bending amount which cannot be disregarded. It is a side view which shows a fork when the amount of bending of a fork has exceeded the limit. It is a top view which shows the fork of the transfer apparatus which concerns on other embodiment. It is a side view which shows the transfer operation in the conventional transfer apparatus in order of steps.

Explanation of symbols

  1 fork, 1a lower fork, 1b middle fork, 1c upper fork, 2 electric motor, 3 stop dog, 4 stop sensor, 5, 5a, 5b tilt sensor, 6 motor drive circuit, 7 CPU, W load.

Claims (3)

In a transfer device that transfers a load by sliding a fork with a drive device,
An inclination sensor disposed on the fork and detecting an inclination angle of the fork;
A transfer device comprising: a control device that controls a moving speed of the fork by the drive device according to an inclination angle of the fork detected by the inclination sensor.   The transfer device according to claim 1, wherein the control device stops the movement of the fork when an inclination angle of the fork detected by the inclination sensor exceeds a preset stop threshold.   When the inclination angle of the fork detected by the inclination sensor falls below a low speed threshold value set in advance to a value smaller than the stop threshold value, the control device moves the fork to a predetermined normal speed pattern. The shift according to claim 2, wherein the fork is moved in a predetermined low speed pattern set at a speed lower than the normal speed pattern when the low speed threshold is not less than the stop threshold and not more than the stop threshold. Mounting device.

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