JPH0797011A - Stacker crane - Google Patents

Abstract

PURPOSE:To reduce a cycle time by composing a stacker crane in a twin fork type, and keeping the stacker crane stand-by till the condition where of two articles can be transferred from/to entry and discharge stations simultaneously is satisfied before actuating it. CONSTITUTION:A stacker crane 3 rugs between plural rack lines 2 to transfer an article W between each rack 1 in each rack line 2 and an entry/-discharge station 4, 5. In the meanwhile, a running carriage 8 puts the article W to the entry station 4, and receives the articles W from the discharge station 5. Two forks are disposed on an elevation table 6 of the stacker crane 3. At this time, for entry or discharge, the stacker crane 3 is kept stand-by till the condition where both forks are capable of transferring the two articles W to both of the entry and discharge stations 4, 5 is satisfied. The articles W are thus placed on all buffers 5a-d at the time of discharge, while the stacker crane is kept stand-by till both the two buffers 4c, 4d have the articles W for entry.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stacker crane for an automatic warehouse, and more particularly to a stacker crane having a plurality of forks capable of simultaneously carrying two or more articles.

[0002]

2. Description of the Related Art As shown in FIG. 2, in a factory, a warehouse or the like, a shelf station 2 composed of a plurality of shelves 1 arranged in a matrix and a shelf station in order to temporarily store a finished product or a semi-processed product. An automatic warehouse consisting of a stacker crane 3 running in front of the frontage of the frontage 2 is used. Stacker crane 3 in Fig. 2
Can deliver two items at the same time
It is a twin fork type in which the lifting table 6 is provided with two forks 7 so that two articles can be conveyed each time.

[0003]

Such a twin-fork type stacker crane 3 can simultaneously deliver two articles and can convey two articles at a time. However, the instruction does not always occur in units of two articles, and an instruction may be issued to store and retrieve only one article. In such cases, 1
If a similar work instruction is issued while the carrying work of only one article is being performed, it will be twice as troublesome, the cycle time will be lengthened, and the margin ratio will be lowered.

Therefore, an object of the present invention is to provide a stacker crane having a plurality of forks which can reduce the cycle time as compared with the conventional one.

[0005]

In order to achieve the above object, the present invention provides a stacker crane capable of transferring at least two articles, to a loading / unloading station,
A stacker crane is provided with means for determining whether or not the crane can transfer the at least two articles at the same time, and means for operating the crane when the crane can perform loading and carrying operations.

[0006]

Since the present invention has the above-mentioned structure, it has the following effects.

In the stacker crane according to the present invention, it is determined whether or not two or more articles that can be simultaneously transferred by the crane can be simultaneously transferred to the loading / unloading station, and the loading and transport operations of the crane are performed. Operate the crane when possible.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments shown in the drawings will be described below.

FIG. 1 is a view for explaining the operation of an embodiment of the stacker crane according to the present invention.

In FIG. 1, the stacker crane 3 travels between the racks 2 and 2, and an entrance station 4 and a exit station 5 are provided near the ends of the racks 2 and 2, respectively.
And the articles W are transferred between the racks 2 and the racks 1 of the racks 2. The traveling vehicle 8 places the article W on the entry station 4 and receives the article W from the exit station 5.

The stacker crane 3 is a twin-fork type, and the lifting platform 6 of the stacker crane 3 has a structure as shown in FIG.
As shown in, two forks 7, 7 are provided,
By operating the forks 7 and 7 at the same time, the two articles Wa and Wb can be transferred at once, and the two articles can be conveyed while being placed on the forks 7 and 7, respectively.

The upper surfaces of the loading station 4 and the loading station 5 are roller conveyors capable of moving the articles W in the directions of the arrows, and one article W is provided in each of the buffers 4a-4d and 5a-5d.
Can be placed. Therefore, each of the receiving station 4 and the leaving station 5 simultaneously receives four articles W.
Can be placed.

The article W includes buffers 4a and 4b of the receiving station 4 and a buffer 5a of the issuing station 5,
Delivery is made at the positions of 5b. The article W placed at the position of the buffer 4d of the receiving station 4 is
It moves in the direction of the arrow and is passed to the stacker crane 3 at the buffer 4a or 4b. Further, the stacker crane 3 is provided with the buffer 5a or 5b of the delivery station 5.
The article W put out from the shelf 1 is placed on the
Moves to the position of the buffer 5d and is transferred to the traveling carriage 8. A control device (not shown) of the stacker crane 3 detects at which position of each buffer of each station the article W is placed by a sensor (not shown).

The operations of the stacker crane 3, the loading station 4, and the shipping station 5 are managed by a host computer (not shown). That is, the host computer prepares a schedule for the delivery request and the entry request, and manages the operations of the stacker crane 3, the stations 4, 5, and the traveling vehicle 8.

The stacker crane 3 of this embodiment has two forks 7 and 7 at each station 4 for loading and unloading.
It is controlled by the control device of the stacker crane so as to wait for the two items to be transferred to the unit 5 before they are ready to be transferred.

Specifically, in the delivery, the host computer prepares a delivery request schedule so that two articles can be delivered, whereas the stacker crane control device responds until the delivery station 5 is full, that is, Control is performed so that the goods leaving work is performed until the articles W are placed on all of the buffers 5a to 5d. In this case, even if the buffers 5a and 5b at the unloading position are occupied, if the buffers 5c and 5d are vacant, the article W in the buffers 5a and 5b is moved to the buffers 5c and 5d and the unloading is immediately performed. Since the position is vacant, it is determined that two articles can be delivered, and the delivery operation is performed. However, if only one of the buffers 5a to 5d has a free space, the articles are delivered to the traveling carriage 8 in a relatively short time, and therefore the delivery processing is waited until two empty spaces are available.
If there is no free space, the shipping process is not performed.

At the time of storage, the stacker crane 3 immediately carries out the loading work even if the articles W are loaded only in one of the buffers 4a and 4b at the loading position of the loading station 4 and the loading work is possible. First, it is detected whether there are articles in the buffers 4c and 4d of the receiving station 4 and moving to the loading position, or whether the traveling carriage 8 is delivering the article to the receiving station 4 or receives data from the host computer. 2 items buffer 4 in a short time
If it is found that the items a and b are aligned, control is performed so as to wait for the warehousing process until they are aligned.

When two articles are conveyed at the same time during storage, if there is an empty shelf 1 adjacent to the shelf string 2, the forks 7 and 7 are operated synchronously and one for each of the two shelves 1. By storing two articles W at the same time, 1
It is possible to complete the warehousing in a fork time.

As described above, the twin fork type stacker crane of this embodiment operates after waiting for a state in which two articles can be simultaneously delivered to each of the stations 4 and 5, so that the cycle time is reduced. Can be shortened and the margin rate can be increased.

The embodiment of the present invention has been described above.
It is needless to say that the present invention is not limited to the above-mentioned embodiments and can be appropriately modified within the scope of the gist of the present invention.

For example, although the twin fork type stacker crane has been described in the illustrated embodiment, the present invention is also applicable to a device having three or more sets of forks.

[0022]

According to the stacker crane of the present invention, the cycle time for loading and unloading processing can be shortened, and
It is possible to improve the margin rate.

[Brief description of drawings]

FIG. 1 is a plan view showing an example of an automatic warehouse system including an embodiment of a stacker crane according to the present invention.

FIG. 2 is a perspective view showing the embodiment of FIG.

[Explanation of symbols]

 1 shelves 2 shelves 3 stacker cranes 4 receiving stations 4a to 4d buffers 5 issuing stations 5a to 5d buffers 8 traveling carriages

Claims (1)

[Claims] 1. A stacker crane capable of transferring at least two articles, a means for judging whether or not the crane can simultaneously transfer the at least two articles to a loading / unloading station, and a stacker crane. A stacker crane having means for operating the crane when loading and carrying operations are possible.