JP4389225B2 - Transport system - Google Patents

Description

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

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 considered the optimization of the arrangement of the buffers in the transport system and arrived at the present invention.
JP 2005-206371 A

An object of the present invention is to optimize the buffer arrangement.
An additional object of the invention of claim 2 is to optimize the buffer allocation to each processing apparatus.
An additional problem in the invention of claim 3 is to shorten the transport time from the buffer to the processing device.
An additional problem in the invention of claim 4 is to optimize the buffer allocation to each bay.

  According to the present invention, a plurality of processing devices having a load port are disposed along a travel route of the transport vehicle, a buffer is disposed, and a transport article is delivered between the transport vehicle and the load port and between the transport vehicle and the buffer. In the transport system, at least one of the plurality of processing devices has characteristics different from the others, and a plurality of the buffers are provided, and a buffer is allocated to each processing device according to the characteristics of the processing device. It is characterized by.

  Preferably, the characteristics are a processing device lead time and a load port number.

  Preferably, the travel route is divided into a plurality of areas in one-way, the buffer and the plurality of processing devices are each divided into a plurality of groups, and the area directly upstream from the area to which each processing device group belongs Allocate a buffer group for the processor group.

  Preferably, the travel route includes an inter bay route and an intra bay route, the processing device is provided along the intra bay route, and the number of transports including a load port in each bay as a start or destination of a transport command. The buffers of each bay are assigned to the own bay and the other bays according to the ratio to the number of transports of the entire transport system. This assignment may be changed during the operation of the transport system and optimized each time.

  In the present invention, buffers are allocated according to the characteristics of the processing device. The buffer is, for example, for storing articles that are to be carried into the processing apparatus. If a sufficient number of buffers are allocated, the next article can be carried in without delay when the load port of the processing apparatus becomes available. . It is important to shorten the delay time. In the present invention, since the buffer arrangement can be optimized for each processing apparatus, the conveyance efficiency is improved.

  In an apparatus having a long lead time, the production efficiency is not lowered even if the delivery of the article is delayed. However, in an apparatus having a short lead time, the production efficiency is remarkably lowered even if the delivery is delayed by the same time. Furthermore, in an apparatus having a large number of load ports, the effect on production efficiency is small even if the delivery of articles is delayed by the same amount of time as compared with an apparatus having a small number of load ports. Therefore, if the characteristics of the apparatus are determined based on the lead time of each processing apparatus and the number of load ports, the allocation of buffers to the processing apparatuses can be optimized.

  The travel route is divided into a plurality of areas in one way, the buffer and the plurality of processing devices are divided into a plurality of groups, and the processing device group is arranged in an area immediately upstream of the area to which each processing device group belongs. When a buffer group is provided, when the article is conveyed from the buffer to the processing apparatus, the article is carried from the area immediately upstream to the processing apparatus, so that the conveyance time is shortened. That is, the transport time becomes longer than when the buffer just beside or upstream of the target load port is used in the same area, but then the transport time becomes shorter. In addition, the number of buffers that can be used increases more than the buffer directly beside or upstream of the target load port, and the probability of temporary storage in the buffer increases. Further, since only the buffer on the downstream side of the processing device can be used in the same area, it is possible to prevent the vehicle from traveling around the travel route. Furthermore, since the area for transporting to the buffer and the area for transporting to the load port can be made different, it is possible to prevent congestion in the area to which the processing apparatus with a large load belongs.

  Consider buffer allocation for a system consisting of an interbay route and an intrabay route. Here, if a buffer is allocated to a bay based on the ratio of the number of transports that pass through each bay to the total number of transports, the buffer allocation can be optimized on a bay basis.

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

  Although an Example is shown in FIGS. 1-6 by taking the overhead traveling vehicle system 2 as an example, it can be similarly implemented in other transport systems such as an automatic guided vehicle 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 transports, the destination (To position), and the departure place (From position). There are distributions and the like, and these are statistically expressed in units such as a bay or a group of processing devices including one or more processing devices. 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 transport command management unit 10 is notified of the To position of the load port to be transported next from the buffer by the production management system 6, and determines the address of the transport destination buffer according to this position. 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. 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.

  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. 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 group of buffers that can accommodate a plurality of articles, and may physically be one buffer shelf or a plurality of buffer shelves. Since the intra bay route 30 is a circular route, each processing device group has an upstream buffer group, and the buffer group facing each processing device group is the most upstream buffer group, that is, the farthest buffer group in the bay. And

  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 32-4. 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 32-2. 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. This is determined from the production capacity at 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 rate 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 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. The flow rate is determined at the start-up of a semiconductor factory or the like, for example, but changes depending on the subsequent addition or replacement of the processing apparatus, the layout change of the travel route, or the like. Furthermore, when the load for each processing apparatus changes depending on the time of day, the flow rate changes depending on the time of day. Therefore, the liquidity is calculated at the time of start-up of the semiconductor factory, etc., and at an appropriate time thereafter, and the buffer for each bay and the one for the other bay are moved according to the liquidity. Is preferably assigned.

  Even if the flow rate is the same, if the production lead time of the processing apparatus is short and the number of load ports of the processing apparatus is small, it is preferable to allocate more buffers. Therefore, the production 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 according to two factors, the flow rate and the characteristics of the processing device.

  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 production lead time LT and the load port number 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, production lead time, and number of load ports are stored for the devices of each processing device group. Here, the production 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 production lead time. The production 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 carrying the article, The time until the article can be carried in may be used. The load port number n is the number of load ports provided in each processing apparatus. When the production lead time LT and the number of load ports 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 production lead time and a small number of load ports, a large number of buffers are allocated, and in the processing device 3 with a long production lead time and a large number of load ports, the number of buffers may be, for example, 1 to 0. . The load port is an entry / exit port for articles to / from the processing apparatus, but is also a temporary storage place while the processing apparatus processes processed articles such as wafers. In addition to load ports, if temporary storage shelves (internal buffers) are provided inside the processing apparatus, not only the number n of load ports but also the number of shelves, for example, is added to the number n of load ports. It is preferable to determine the number of buffers.

  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 assigned to 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. Buffers are assigned to one processing unit group from a plurality of buffer groups. For example, buffers from the upstream buffer group may be used, or buffers assigned from a plurality of buffer groups are randomly assigned. 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 and 6 show the allocation of buffers outside the bay. 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 transports passing through each bay, and obtains the short-time average or a predicted value in the future. As the number of transports, 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, and counting is performed for both the From position and the To position. Instead, only one of them may be counted, such as the From position or the To position. The prediction is made, for example, by correcting the average value of the latest number of conveyances based on the increase / decrease tendency.

  When the number of transports through the bay exceeds a predetermined value α, a buffer outside the bay is used, and when the number of transports is less than the predetermined value α, the buffer in the bay is used. There is no need to shift the buffer to be used from 100% to the outside of the bay with the predetermined value α as a boundary, and the ratio of using the buffer outside the bay may be increased according to the number of transports passing through the bay.

For example, in the case of FIG. 5, when the number of conveyances via the bay 30-1 is equal to or greater than the predetermined value α, the buffer groups 32-5 and 32-6 in the intra-bay route adjacent to the processing device groups A and B are thereafter used. Allocate a buffer. 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 bay 30-1 having a large number of conveyances. In this case as well, buffers are allocated from a plurality of buffer groups so that delivery work is not concentrated on a specific buffer group. In this way, for a bay with a large number of conveyances, it is possible to relieve congestion by transferring the buffer to the bay. When the number of transports in the bay 30-1 decreases below α, a buffer in the bay 30-1 is allocated.

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 Flowchart showing buffer allocation algorithm in the embodiment

Explanation of symbols

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

Claims (4)

In a system in which a plurality of processing devices having a load port are disposed along a travel route of the transport vehicle and a buffer is disposed, and a transport article is transferred between the transport vehicle and the load port and between the transport vehicle and the buffer. ,
At least one of the plurality of processing devices has characteristics different from the others,
A transport system, wherein a plurality of the buffers are provided, and buffers are assigned to the respective processing devices in accordance with characteristics of the processing devices. The transport system according to claim 1, wherein the characteristics are a lead time of the processing apparatus and the number of load ports. The travel route is divided into a plurality of areas in one way, and the buffer and the plurality of processing devices are each divided into a plurality of groups, and the processing device group is arranged in an area immediately upstream from the area to which each processing device group belongs. The transport system according to claim 1 or 2, characterized in that a buffer group is allocated for the above. The travel route consists of an interbay route and an intrabay route, and the processing device is provided along the intrabay route,
In addition, according to the ratio of the number of transports including the load port in each bay as the start or destination of the transport command to the transport number of the entire transport system, buffers for each bay are allocated to the own bay and other bays. The conveyance system according to any one of claims 1 to 3, wherein

Images