JPH05253810A - Physical distribution controller - Google Patents

Abstract

PURPOSE:To reduce a buffer capacity by providing two buffers for storing articles, a switching device for switching to a buffer to which articles are to be fed and a switching device for switching to a buffer from which the articles are to be delivered and contriving switching control of each switching device. CONSTITUTION:In a physical distribution controller whose throughput of post- process I is inferior to the throughput of the pre-process B, when an inventory number in the first buffer F detected by a counter E exceeds the set value (for example two) in a controller D, a device A in the pre-process B is made to stop and articles from the pre-process B are switched to a condition of being sent to the second buffer G by the first switching device C. Or the inventory number in the first buffer F is made to be compared with the minimum limit number (for example one) and when the inventry number is less than the limit value, the second switching device H is switched to the second buffer G side. The articles are delivered until the inventory number in the buffer G becomes zero and when it reaches zero, the second switching device H is switched to the first buffer F side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a physical distribution control device mainly composed of a buffer for temporarily storing articles sent from a previous process and sending them to a subsequent process.

[0002]

2. Description of the Related Art As a method of adjusting the capacity balance between a pre-process and a post-process, as schematically shown in FIG. 2, a method of providing a buffer for temporarily storing articles transferred between the processes between the processes. It has been known. In other words, by giving the preceding process a higher capacity than the succeeding process, increasing / decreasing the stock amount in the buffer and switching the operation / stop of the preceding process (stopping the device if it cannot be stopped halfway) It adjusts their real ability. An example of this is JP-A-3-148200.
It is disclosed in Japanese Patent Publication No. In this case, the processing capacity of the previous process (n1 pieces / H) is 1 of the processing capacity of the subsequent step (n2 pieces / H).
There is some margin such as 10 to 120%.

In the system shown in FIG. 2, a means E for counting the number of stocks in the buffer J and a controller D are used, and the controller D performs a pre-process when the counted number of stocks (E) exceeds a set value (L). When the in-process stop of B is instructed, on the other hand, when the counted inventory quantity (E) is less than the set value (L), the in-process execution of the previous process B is instructed. As a result, the stop and the execution of the work in process of the previous process are switched, so that a large inventory is not generated in the buffer J or a stockout is not generated.

[0004]

However, when the processing time T of the previous process is long, the process of the previous process is stopped when the stock quantity E exceeds the set value L as illustrated at the timing t1 in FIG. However, the articles already set in the previous process are continuously sent to the buffer J for the time T thereafter.
Therefore, the stock quantity of the buffer J continues to increase at a ratio according to the difference between the number of articles sent per unit time and the number of articles sent out per unit time (see line K). When the time T has elapsed, the effect of the in-process stop at the timing t1 begins to appear, and the number of stocks in the buffer J starts to decrease (see line M). When the stock number E falls below the set value L (timing t3), the work in process is restarted. However, the effect of the restart of the work process appears later than that by T time, so the stock number continues to decrease during that time. That is, the inventory quantity (E) is L-n at the timing t4.
It keeps decreasing until it becomes 2 * T. As is clear from the figure, the maximum value of the buffer J is L + (n1-n2) * T in the buffer J.
At the minimum, L-n2 * T pieces are accommodated, and the difference is n1 * T pieces.

Here, in order not to cause a stockout, L-n
2 * T needs to be positive, and the set value L needs to be set to n2 * T or more. Also, even if L is set equal to n2 * T, the buffer L must still have a capacity to accommodate n1 * T. For example, if the previous process requires 8 hours and the number of processes per hour is 150, a large capacity buffer capable of accommodating 1200 is required. Therefore, the present invention proposes a new physical distribution control device capable of reducing the capacity required for the buffer.

[0006]

Therefore, according to the present invention, the concept is schematically shown in FIG. 1, that is, the physical distribution control device, that is, the article sent from the pre-process B is received and the post-process I is accepted.
And a first buffer F for storing the article, a second buffer G for storing the article, and a first buffer F for storing the article sent from the previous step B.
To the first buffer F or the second buffer G in the subsequent step I, and the second switch H to switch between the first buffer F and the second buffer G. A means E for counting the number of articles in stock in the first buffer F, and when the number of articles (E) counted by the counting means E exceeds a set value L, an instruction to stop the in-process of the preceding step B is given and When the first switch C is switched to the state of sending to the second buffer G, and the inventory quantity (E) counted by the counting means E is below the set value L, the previous step B
A physical distribution control device having a controller D for instructing the execution of the in-process and switching the first switch C to the state of sending to the first buffer F has been created.

[0007]

According to this apparatus, when the stock quantity E in the first buffer F exceeds the set value L, the work in process is stopped and the articles sent from the previous process B flow into the first buffer F. I will not stay. Therefore, the stock quantity of the first buffer F changes in the same manner as when the effect of stopping the work is generated in a short time, in other words, the stock quantity change similar to that when the processing time of the previous process B is short. Will occur.

On the other hand, when the number of stocks in the first buffer F falls below a set value, the articles that have not flown into the first buffer F until then start to flow in. That is, a phenomenon equivalent to that of the effect of restarting the work in process to the previous process in a short time occurs. In other words, the same inventory quantity changes as when the processing time of the previous process B is short.

As described above, according to the present apparatus, although the previous process actually takes a long time, the stock quantity change in the first buffer causes the same change as in the case where the previous process takes only a short time. It becomes possible. For this reason, the overshoot and undershoot values in feedback control become small. As a result, the total capacity of the first and second buffers can be made significantly smaller than the capacity of the conventional buffer J.

[0010]

EXAMPLES Next, specific examples of the present invention will be described. This example
This physical distribution control device is applied between a pretreatment process having a processing capacity of 150 pieces per hour and a post-processing step having a processing capacity of 130 pieces per hour. .. In this case, it is theoretically possible to set the capacity of the first buffer F to only 3, the set number L to 2 and the capacity of the second buffer G to 1.

When the stock quantity E in the first buffer F exceeds the set value L (2 pieces), the controller D stops the work in process of the previous process, and the first switch C sends it from the previous process B. The state in which the article is sent to the second buffer G is switched. On the other hand, when the value is below the set value L (two pieces), the work in process of the previous process is restarted, and the first switch C switches the product sent from the previous process B to the first buffer F. Further, the controller D has a function of comparing the stock quantity E in the first buffer F with the minimum limit value (l in this example), and when the stock quantity E falls below the limit value, the second switching unit H is operated. In the post-process I, the state is switched to the state of sending out from the second buffer G. In this embodiment, when the second switching unit H is switched to the state of sending out the articles from the second buffer G, the state is continued until the stock quantity in the second buffer G becomes zero, and when it becomes zero, the The 2 switch H is switched to a state in which the article is sent out from the first buffer F.

Alternatively, when the stock quantity in the first buffer F exceeds the minimum limit value, the second switch H may be switched to the state of being sent out from the first buffer F. Furthermore, if the device of the previous process is stopped at the timing of t5 to t6, the second switching unit H is switched to the state of sending out from the second buffer G at the timing delayed by T time, that is, the timing of t5 + T to t6 + T. May be. Even in this case, the stock quantity in the second buffer G fluctuates little by little, and a large capacity is not required.

In the case of this embodiment, the total capacity of the first and second buffers can be practically set to about 200 in order to cope with an unexpected line stop. The term "above" or "below" in this invention means
"More than" and "less than" or "exceeded" and "less than"
Alternatively, it may be either “exceeding” or “less than”.

[0014]

According to the physical distribution control device of the present invention, the first and second
Since the buffer is provided and the first switch is provided between the first buffer and the preceding process, even if the preceding process actually takes a long time, the number of stocks in the first buffer is reduced by the preceding process. It is possible to make the same change as in the case where it takes only a short time, and it is possible to reduce the number of overshoots or undershoots by stopping and executing the work in progress in the previous process in small steps. Therefore, the buffer capacity can be reduced, and the equipment cost and space can be saved. Moreover, since the number of intermediate stocks can be reduced, it is possible to shorten the work of finding defective products.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing the concept of the present invention.

FIG. 2 is a diagram schematically showing a conventional technique.

FIG. 3 is a diagram showing a problem of the prior art.

[Explanation of symbols]

 B Pre-process C 1st changer D Controller E Counter F 1st buffer G 2nd buffer H 2nd changer I Post-process

Claims (1)

[Claims] 1. A physical distribution control device that receives an article sent from a previous step and sends it to a subsequent step, the first buffer storing the article, and the second buffer storing the article. A first switcher for switching whether the article sent from the previous step is sent to the first buffer or the second buffer; and in the subsequent step, the article is sent from the first buffer or the second buffer
A second switch for switching whether to send the article from the buffer, a means for counting the number of articles in stock in the first buffer, and an in-process stop of the previous process when the number of articles in stock counted by the counting means exceeds a set value. At the same time as instructing, the first switch is switched to a state of sending to the second buffer, and when the inventory quantity counted by the counting means is less than a set value, the in-process execution of the previous process is instructed and the first switch is switched to the first switch. A physical distribution control device having a controller for switching to a state of sending to one buffer.