JP2007137642A - Conveyance system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conveyance system capable of facilitating layout of a buffer and preventing a bottleneck on a running route. <P>SOLUTION: When using a load port 24 of a group A of handling devices as the next conveyance destination, the buffers are laid out from the upstream side by giving priority to the immediate upstream side at such a frequency that a group 32-1 of buffers in an area on the immediate upstream side and then a group 32-2 of buffers in an area on the upstream side come in this order. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a transport system such as an overhead traveling vehicle system, a tracked bogie system, and an automatic guided vehicle system that travels on the ground without a track, and particularly relates to buffer allocation in a transport command.

The applicant has proposed that in a transport system such as an overhead traveling vehicle, a buffer is provided on the side or below the traveling rail to store the transported article (Patent Document 1). Thereafter, the applicant studied the optimization of buffer allocation in each conveyance command, and reached the present invention.
JP 2005-206371 A

An object of the present invention is to facilitate buffer allocation and prevent congestion of a travel route.
An additional problem in the invention of claim 2 is to more reliably prevent a traffic jam on the travel route.
An additional problem in the invention of claim 4 is to prevent congestion of a local route having a particularly large number of conveyance commands.

According to the first aspect of the present invention, a plurality of processing devices and a plurality of buffers are arranged along the travel route, and the transport vehicle is caused to travel on the travel route by a transport command from the controller. In a system that delivers articles between, the travel route is divided into a plurality of areas, and among the plurality of areas, an area to which a processing device that processes articles next belongs, and at least one other area A buffer is provided, and the controller searches for an empty shelf in the buffer in an area other than the area to which the processing device belongs, and assigns a transport command to transport the article to the searched empty shelf. Features.
As a general rule, each area is provided with one to a plurality of processing devices and a buffer that can store a plurality of articles, and when it is possible to carry directly to the next processing device without going through the buffer, a conveyance command via the buffer Instead, it is preferable to create a conveyance command for conveying directly to the processing apparatus.

  Preferably, a plurality of areas each having a buffer are provided in addition to an area to which a processing device that processes an article next belongs, and a buffer in each area is allocated to the processing devices in the plurality of areas. The empty shelf of the buffer is searched from the area immediately upstream of the area to which the processing device to process the item belongs to the upstream side, and a transfer command for transferring the article to the searched empty shelf is assigned to the transfer vehicle.

In the invention of claim 3, a plurality of processing devices and a plurality of buffers are arranged along the travel route, and the transport vehicle is caused to travel on the travel route by a transport command from the controller, and the processing device or the buffer and the transport vehicle are In the system in which the goods are transferred between the vehicles, the travel route is further divided into a plurality of local routes and a basic route that connects the local routes, and the controller includes a local device to which a processing device that processes the goods next belongs. The present invention is characterized in that an empty shelf in a buffer of a local route different from the route is searched, and a transfer command for transferring an article to the searched empty shelf is assigned to the transfer vehicle.
As a general rule, each area is provided with one to a plurality of processing devices and a buffer that can store a plurality of articles, and when it is possible to carry directly to the next processing device without going through the buffer, a conveyance command via the buffer Instead, it is preferable to create a conveyance command for conveying directly to the processing apparatus. In principle, a plurality of areas are provided for each local route, but a local route having only one area may exist in part. When there are many conveyance commands, not only the buffer for the local route on the upstream side, but also a buffer or stocker provided for the basic route on the upstream side may be used together.

  Preferably, the controller is provided with means for determining the number of conveyance commands for the local route, and if the number of conveyance commands for the local route to which the processing device for processing an article next belongs is equal to or less than the set number, The empty shelf in the buffer is searched, and a transfer command for transferring the article to the searched empty shelf is assigned to the transport vehicle.

  According to the first aspect of the present invention, the transport vehicle that stops in order to exchange with the buffer is stopped in an area that is different from the area to which the processing device that processes the article next belongs. For this reason, it is possible to reduce the movement of the transport vehicle that stops in order to interact with the processing device by the transport vehicle that stops in order to interact with the buffer. It is possible to smoothly receive and supply articles to the apparatus.

  In the invention of claim 2, the transport time from the buffer can be shortened by transporting the article from the area immediately upstream, where the transport time is short, from the area to which the processing apparatus to which the article is transported next is short. , It is possible to prevent the traffic from being concentrated on the buffer in the area and congesting.

  According to the third aspect of the present invention, it is possible to prevent the local route from being congested by suppressing the approach of the transport vehicle to the local route to which the transport device for processing the article next belongs.

  Further, in the invention of claim 4, when there is no possibility that the local route to which the processing apparatus for processing the next article belongs will be congested, it is possible to eliminate the need for conveyance between the local routes by directly carrying it into the buffer of the local route.

  In the following, an optimum embodiment for carrying out the present invention will be shown.

  Although an Example is shown in FIGS. 1-7 for the overhead traveling vehicle system 2 as an example, it can implement similarly with another conveyance system. The overhead traveling vehicle system 2 is installed in a clean room, for example, and accommodates articles such as semiconductors in a container such as a cassette and conveys the cassette as a conveyed article. In addition, the kind of conveyance article is arbitrary. In each figure, 4 is a logistics control system that manages the entire overhead traveling vehicle system 2, and 6 is a production management system that manages semiconductor processing equipment, inspection equipment, etc. While requesting transportation, the status (load / empty) of the load port of each processing apparatus is notified, and a report of the transportation result is received from the physical distribution control system 4.

  The logistics control system 4 is provided with a statistics management unit 8 to create various statistics related to the overhead traveling vehicle system 2. The statistics include the total number of conveyances (conveyance commands), their destinations (To positions), and departure places. There is a distribution of (From position), etc., and these are statistically expressed in units such as bays and processing device groups. The statistics include a long-term average and a short-term average within a predetermined time such as the past one hour. From this average, it can be determined in which bay and in which processing device group the conveyance work is concentrated, and in particular, from the short-time average of the distribution of the To position and the From position, it is possible to grasp the traffic situation of the bay and the processing device group. Further, the statistical management unit 8 statisticizes the buffer occupancy rate (the ratio of the buffer occupied by the article) for each bay and each processing device group, and the buffer capacity in the bay and processing device group is determined from this. .

  The conveyance command management unit 10 creates a conveyance command in response to a request from the production management system 6 and assigns it to each overhead traveling vehicle 20. Constituent elements of the transport command are the ID of the transport command, the ID of the transported article, the From position and the To position, and when the buffer is the transport destination, the address is the To position. In this case, the transfer command management unit 10 is notified from the production management system 6 of the To position of the load port to be transferred next from the buffer. The conveyance command management unit 10 manages the execution status of the conveyance command, and changes the conveyance command as necessary. For example, if the production management system notifies that the load port of the next destination is available before the estimated arrival time to the buffer after instructing transport to the buffer, the destination may be changed from the buffer to the load port. good.

  Based on the address of the load port to be transported next, the buffer allocation unit 11 selects a buffer of the upstream buffer group and determines the address of the transport destination buffer. In general, the From position and To position are the load port, buffer, or stocker of the processing device, and the From position and To position are designated by the address. One area includes one processing device group and one buffer group. Buffers are assigned to each processing device group from a plurality of areas on the upstream side. Allocate a buffer to the transport command.

  The inventory management unit 12 manages the inventory under the management of the physical distribution control system 4, and the inventory data includes the ID, From position, To position, and inventory position of the inventory item itself. For example, when articles are stored in a buffer or stocker, the stock position is the buffer or stocker, the From position is the position before the buffer or stocker is loaded, and the To position is the planned position to transport the article from the buffer or stocker. It is. In addition to this, the inventory management unit 12 also manages articles being transported by the overhead traveling vehicle 20 as inventory, and the inventory position is the overhead traveling vehicle. When the article is unloaded to the load port 24, the article is deleted from the inventory data. When the article is loaded from the load port 24, the article is added to the inventory data.

  The transfer master file 14 stores data necessary for managing the overhead traveling vehicle system 2, which includes the arrangement of the interbay route 28 and the intrabay route 30, the arrangement of the buffer 22, the stocker 26, and the load port 24. The data necessary for the traveling of the overhead traveling vehicle 20 such as the traveling time of the vehicle is included. In addition to this, the transport master file 14 stores the characteristics of each processing device group. This will be described later with reference to FIG.

  A plurality of overhead traveling vehicle controllers 16 are connected to the logistics control system 4 via a LAN or the like, and the controllers 16 are provided, for example, in units of bays, and are divided into a plurality of long-distance backbone routes such as interbay routes. Thus, a controller 16 is provided for each. The overhead traveling vehicle controller 16 communicates with the overhead traveling vehicle 20 by wireless communication or the like, transmits a conveyance command to the overhead traveling vehicle 20, and receives the execution result and other data from the overhead traveling vehicle 20.

  The overhead traveling vehicle 20 has a traveling drive unit that travels along an inter-bay route or an intra-bay route, a lifting platform that holds articles such as cassettes freely, a lifting drive unit that lifts and lowers the lifting platform, and a lifting drive unit as a traveling route. On the other hand, it is provided with a lateral feed portion that moves in the lateral direction, and the configuration itself is known. The overhead traveling vehicle 20 transfers articles to and from the buffer 22, the stocker 26, the load port 24, and the like. The stocker 26 is provided in units of bays or in units of one for a plurality of bays, but the stocker 26 may not be provided so that the transported articles are stored in the buffer 22.

  In the embodiment, the buffer 22 is an open-type shelf placed below or on the side of the traveling route of the overhead traveling vehicle 20, and as a general rule, does not include a loading / unloading device, a transfer device, etc. Deliver goods using a table. In the embodiment, the buffer 22 is not provided with a sensor, communication means, etc., and the overhead traveling vehicle 20 determines the presence / absence of the buffer by the loading sensor, or the presence / absence according to the buffer presence / absence data in the inventory management unit. And load and unload goods.

  FIG. 2 shows the arrangement of travel routes in the overhead traveling vehicle system 2. Reference numeral 28 denotes an interbay route, which is a long-distance route that serves as a backbone connecting a plurality of intrabay routes 30. Here, each intrabay route 30 is a circuitous route. It is assumed that traveling is possible, and the overhead traveling vehicle 20 travels on the routes 28 and 30 in one way. The intra-bay route 30 is provided with a plurality of processing device groups A to D, and the number of groups is arbitrary. Reference numeral 34 denotes an individual processing apparatus including one to a plurality of load ports 24. The processing device groups A to D are a collection of devices having a plurality of processing devices of the same type, and devices that are connected in the process, such as processing devices and inspection devices. In addition, the processing device groups A to D may be composed of a single device when a semiconductor factory is installed, and it is normal to increase the number of devices in the processing device group as the production capacity increases. is there.

  As shown in FIG. 2, buffer groups 32-1 to 32-4 are provided, for example, on the side of the intra-bay route 30, and the buffer groups are arranged facing, for example, the physical device group. The subscripts 1 to 4 of the buffer groups 32-1 to 32-4 indicate the order along the circumferential direction of the overhead traveling vehicle 20, and the larger the subscript, the more upstream the buffer group 32-4 is located immediately upstream of the buffer group 32-4. There is 32-1. Here, one buffer group is assigned to a plurality of processing device groups, and conversely, one processing device group is assigned buffers from a plurality of buffer groups. The buffer groups 32-1 to 32-4 are a collection of buffers that can accommodate a plurality of articles. Physically, the buffer groups 32-1 to 32-4 may be one buffer shelf or a plurality of buffer shelves. It is.

  A buffer is allocated to the processing device group from the buffer group on the immediately upstream side. For example, for the processing unit group A in FIG. 2, a maximum number of buffers are allocated from the buffer group 32-1 immediately upstream, and a slightly smaller number of buffers are allocated from the upstream buffer group 32-2. A smaller number of buffers are allocated from the buffer group 32-3, and a minimum number of buffers are allocated from the opposed buffer group 32-4. The number of buffers allocated to each processing unit group is the maximum in the buffer group immediately upstream, the number of buffers allocated is reduced as it becomes an upstream buffer group, and the number of buffers allocated from the opposing buffer groups Is minimized. A bypass route 36 bypasses the interbay route 28, and a buffer 38, a stocker, and the like are provided in this portion.

  3 and 4 show buffer allocation to each processing device group. First, the required total capacity of the buffer is determined, and this is determined from the production capacity in the semiconductor factory, the time required for substrate processing, the required amount of safety stock, and the like. When a stocker or the like is provided, the total capacity of the buffer may be reduced accordingly. Once the total capacity of the buffer is determined, it is determined at what ratio this is allocated to each bay. Here, the concept of fluidity is used, which is the ratio at which the load port in the bay is designated as the starting point or destination in the transport command. From the semiconductor manufacturing process and production capacity, for example, the total number of transports per day, here, the total number of transport commands, can be predicted, and the rate at which one bay is involved is the flow rate. When one conveyance is counted twice at the departure point and the destination point, the sum of the flow rates for all bays is 100%. For example, the buffer is distributed to each bay at a rate corresponding to the flow rate.

  Even if the flow rate is the same, it is preferable to allocate more buffers when the lead time of the processing device is short and the number of load ports of the processing device is small. Therefore, the lead time LT and the load port number n may be obtained for the processing devices in the bay, and the number of buffers may be corrected according to the characteristics of the processing devices based on these. In this case, a buffer is allocated to each bay in accordance with two factors, a flow rate and a characteristic. For buffer allocation, for example, the portion determined by the flow rate is set to X1 to X2%, and the portion determined according to the characteristics of the processing apparatus is set to Y1 to Y2%.

  When the total number of buffers to be assigned to each bay is determined, assignment in units of processing device groups is determined. The factors in this case are the lead time LT and the number of load ports n of the devices in each processing device group. For example, the table 40 of FIG. 4 is provided in the transfer master file 14 and the device number, lead time, and number of load ports are stored for each device in each processing device group. Here, the lead time is classified into three stages of short (S), medium (M), and long (L), and classification into several stages is used rather than obtaining an accurate lead time. The lead time is the time from when an article is carried into the processing apparatus from the load port until the processing is completed and carried out to the load port. Other definitions, for example, after the article is carried in, the next article It is also possible to use the time until it becomes possible to carry in. The load port number n is the number of load ports provided in each processing apparatus. When the lead time LT and the load port number n are determined, the number of buffers required for the processing apparatus is determined accordingly. For example, in the processing device 1 with a short lead time and a small number of load ports, a large number of buffers may be allocated, and in the processing device 3 with a long lead time and a large number of load ports, the number of buffers may be, for example, 1 to 0.

  Next, when the necessary number of buffers for each processing device is added in units of processing device groups, the required number of buffers in units of processing device groups is determined. When the buffer assigned to the bay is assigned to each processing device group according to the number of buffers required for the processing device group, the assignment is completed. Here, as described with reference to FIG. 2, buffers for one processing device group are distributed over a plurality of buffer groups, and a larger number of buffers are provided in the upstream buffer group than the buffer group facing each processing device group. Allocate a buffer. Particularly preferably, the maximum buffer is allocated from the buffer group on the upstream side, and the number of buffers to be allocated is reduced every time the buffer group is further upstream, and the minimum buffer is allocated from the buffer group facing the processing device group. The number of buffers allocated from the buffer group facing the processing device group may be zero, for example.

  If a buffer for one processing device group is allocated from a plurality of buffer groups, the congestion of the intra-bay route 30 can be alleviated. When the transfer work is concentrated on one processing device group, if only the buffers of the buffer group facing each other are used, the transfer work with the load port and the transfer work with the buffer are concentrated in a narrow area. There is a traffic jam. The time during which the overhead traveling vehicle 20 stops before the articles are loaded into the load port is one time for unloading to the buffer and loading from the buffer, and one time for unloading to the load port. While a traveling overhead traveling vehicle does not cause congestion on the intrabay route, a suspended overhead traveling vehicle stops the subsequent overhead traveling vehicle and causes traffic congestion. Therefore, by allocating buffers from a plurality of buffer groups, the positions where the transfer work with the buffers is performed are distributed, and the congestion of the intrabay route 30 is alleviated.

  By allocating a buffer from the upstream side of the processing device group, it is possible to temporarily store the incoming goods at a position where the traveling time to the processing device group is short. One processing unit group is allocated with buffers from a plurality of buffer groups, but may be used from, for example, buffers in the buffer group immediately upstream, or buffers allocated from a plurality of buffer groups are randomly allocated. May be. The inventory management unit 12 in FIG. 1 stores which ID of the article is stored in which buffer position and which load port is the next destination.

  5 to 7 show buffer allocation. As described above, buffers are assigned to the processing unit group A of the intra-bay route 30-1 in the order from the buffer group 32-1 on the upstream side to the buffer group 32-4 on the farthest side. The same applies to the device groups B to D. Then, in a transport command in which a certain processing device group is set as the next transport destination, a buffer is assigned with priority given to the buffer group in the upstream area. In this case, it is optional to give priority to the buffer group immediately upstream as much as possible, or to randomly select a buffer from the buffer group assigned to the next transfer destination processing apparatus group.

  Here, assuming that the load port 24-1 in FIG. 6 is the next transport destination, the article is stored in the buffer 42 facing the load port 24-1 or assigned to the device group A such as the buffer group 32-1 on the upstream side. Consider whether to store in a buffer. When the buffer 42 is used, the overhead traveling vehicle stops excessively at the position facing the load port 24-1 twice by unloading to the buffer 42 and loading from the buffer 42, and in the area facing the device group A Prone to traffic jams. On the other hand, when the buffer group 32-1 or the like is used, the article can be delivered to the buffer in another area, and the stop position of the overhead traveling vehicle is dispersed in the intra-bay route 30-1 to reduce the traffic jam. Can be prevented. The advantage of using the buffer 42 is that the article can be transferred from the buffer 42 to the load port 24-1 while the overhead traveling vehicle is stopped. However, such a buffer has only one article, and it is difficult to allocate the buffer. In addition, the travel time from the buffer group 32-1 to the load port 24-1 is generally shorter than the article delivery time.

  When transport commands are concentrated in a specific bay, the traffic in the intra bay route 30 becomes conspicuous if a buffer in that bay is used. This is because if the overhead traveling vehicle 20 stops for delivery to the buffer, the succeeding overhead traveling vehicle cannot travel. Therefore, the statistical management unit 8 in FIG. 1 counts the number of conveyance commands passing through each bay, and obtains the short-time average or a predicted value in the future. As for the number of transport commands, the load port in the bay is set to the From position or To position, or the buffer in the bay is added as the From position or To position, etc. Instead of counting, only one of them, such as the From position or the To position, may be counted. The prediction is made, for example, by correcting the average value of the number of recent transport commands with the increase / decrease tendency.

  When the number of conveyance commands passing through the bay exceeds a predetermined value α, a buffer outside the bay is used, and when the number of conveyance commands is less than the predetermined value α, the buffer in the bay is used. It is not necessary to shift the buffer to be used from the 100% bay to the bay outside the predetermined value α, and the ratio of using the buffer outside the bay may be increased according to the number of transport commands passing through the bay.

For example, when the number of conveyance commands passing through the intra-bay route 30-1 in FIG. 5 is equal to or greater than a predetermined value α, the intra-bay route adjacent to the processing device groups A and B and the processing device groups A and B are relatively Buffers are allocated from the adjacent buffer groups 32-5 and 32-6 on the upstream side in the adjacent intrabay route. Similarly, buffers are allocated to the processing device groups C and D from an intra bay route (not shown) adjacent to the left side of FIG. When the buffer 38 can be allocated from the bypass 36 or the like, the buffer 38 is allocated to the intra-bay route 30-1 having a large number of conveyance commands. Since the buffer 38 is in the interbay route, there are a large number of traveling vehicles traveling, the created conveyance command can be easily assigned, and the time until actual conveyance can be reduced. In particular, since the buffer 38 is provided in the bypass 36 of the interbay route, even if the transport vehicle stops at the buffer 38 for transfer, it is possible to prevent the main route from being affected.

The block diagram which shows the control system of the conveyance system of an Example The principal part top view of the layout of the conveyance system of an Example The flowchart which shows the arrangement | positioning algorithm of the buffer in an Example A part of the table in the transfer master file in the embodiment is shown, and a description of characteristics of each device in the device group is shown. The figure which shows the allocation of the buffer to the apparatus group in an Example The figure which shows the allocation of the buffer by the individual conveyance command in the embodiment Flowchart showing buffer allocation algorithm in the embodiment

Explanation of symbols

2 Overhead Vehicle System 4 Logistics Control System 6 Production Management System 8 Statistics Management Unit 10 Transport Command Management Unit 11 Buffer Allocation Unit 12 Inventory Management Unit 14 Transport Master File 16 Overhead Vehicle Controller 20 Overhead Vehicle 22 Buffer 24 Load Port 26 Stocker 28 Interbay route 30 Intrabay route 32-1-4 Buffer group 34 Processing device 36 Bypass route 38 Buffer 40 Table 42 Buffer A to D Processing device group

Claims (4)

A plurality of processing devices and a plurality of buffers are arranged along the traveling route, and the conveyance vehicle is caused to travel on the traveling route in accordance with a conveyance command from the controller so that the article is delivered between the processing device or the buffer and the conveyance vehicle. In the system
While dividing the driving route into multiple areas,
Among the plurality of areas, a buffer is provided in an area to which a processing apparatus that processes the article next belongs and at least one other area, and the controller has an empty buffer in an area other than the area to which the processing apparatus belongs. A transport system, wherein a shelf command is retrieved and a transport command for transporting articles to the retrieved empty shelf is assigned to the transport vehicle. Next, in addition to the area to which the processing device for processing the article belongs, a plurality of areas with buffers are provided, and the buffers in each area are assigned to the processing devices in the plurality of areas
The controller searches for an empty shelf in the buffer from the area immediately upstream of the area to which the processing device for processing the article next belongs to the upstream side, and issues a conveyance command to convey the article to the searched empty shelf. 2. The transfer system according to claim 1, wherein the transfer system is assigned to the transfer system. A plurality of processing devices and a plurality of buffers are arranged along the traveling route, and the conveyance vehicle is caused to travel on the traveling route in accordance with a conveyance command from the controller so that the article is delivered between the processing device or the buffer and the conveyance vehicle. In the system
The driving route is further divided into a plurality of local routes and backbone routes connecting the local routes.
The controller searches the empty shelf of the buffer of the local route different from the local route to which the processing device that processes the article next belongs, and assigns a conveyance command to convey the article to the searched empty shelf to the conveyance vehicle. A transport system characterized by. The controller is provided with means for determining the number of conveyance instructions for the local route, and if the number of conveyance commands for the local route to which the processing device for processing the next article belongs is equal to or less than the set number, 4. The transport system according to claim 3, wherein a search is made for an empty shelf, and a transport command for transporting an article to the searched empty shelf is assigned to a transport vehicle.

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