喜歡就充值下載吧，，資源目錄下展示的全都有，，下載后全都有，dwg格式的為CAD圖紙，有疑問咨詢QQ：414951605 或1304139763 Pergamon Computers ind. Engng Vol. 33, Nos 3-4, pp. 677-680, 1997 1997 Elsevier Science Ltd Printed in Great Britain. All rights reserved 0360-8352/97 $17.00 + 0.00 PII: S0360-8352(97)00220-9 An Operation Analysis of Movable Rack Type ASIRS by Use of System Simulator Norio YAMAGUCHI*, Kazuhiro SHIMODA Dept. of Information Systems Engineering, Kyushu Tokai University Kumamoto, JAPAN Abstract We perform the operation analyses of movable rack type AS/RS which is built in among manufacturing resources. Processing time and processing cost to handle each pallet are investigated. We employ the system simulator approach for the analyses. It is clarified that, if the operation conditions such as the speed of the stacker crane and/or rack are properly adjusted, the processing time of each pallet is not so increased in comparison with that in the fixed rack type case. Further, under our assumed conditions concerning the investment, we found that the cost performance of the movable rack type AS/RS accompanied with medium speed stacker crane is comparable with that of the fixed rack type AS/RS equipped with high speed stacker crane. 1997 Elsevier Science Ltd Keywords : AS/RS, System simulator, Movable rack 1. Introduction Considering the recent surroundings of production activities that the product needs of the end user change in a short time and span wide range in kinds, quick findings of the demand and prompt supply are becoming more and more important to every manufacturers. That is, the manufacturer is forced to supply various kinds of products in a short lead time to satisfy users demand. In order to construct the robust manufacturing system which can stand for the above mentioned tough requisitions, designs of manufacturing systems are investigated from various viewpoints 1 . Among them, the optimal operation of material handling facilities is the important factor to be considered to realize the smooth flow of the materials through the system 2,3,4. And, as one solution for the efficient use of various resources in the system, automatic storage and retrieval system (AS/RS) is sometimes built in among resources 5. The functions of this AS/RS are (1) To store and retrieve the common tools used by many resources. (2) To store and retrieve the WIP materials temporally. All the materials are forked with pallet in this AS/RS Here, to build in this type of AS/RS in a restricted space of the factory, we have to take into account both of high density in terms of capacity and swift handling of pallets. 6?7 In this respect, AS/RS which has movable rack is becoming popular. It is certain that we can attain high density in terms of capacity by introducing the movable rack. However, this may lead the increment of the processing time of each pallet because of the concurrent movement of rack and crane. So, we first compare, using system simulator, the processing time of each pallet between fixed and movable rack AS/RSs under various operation conditions. As the next step, we estimate the cost performance of both systems. 2. Modeling The layout of fixed rack type AS/RS we analyze for comparison is shown in Fig.1. In this figure, the bold line indicates the route of stacker crane and intersections 2,4 and 6 are in/out stations for the pallets. In this AS/RS, there are 6 racks, each of which contains 50 cells (10 columns, 5 rows) and hence, we can store 300 pallets. F I I I i I / IIIIiii= i/ I I I I I I I I I I I / llllll, Fig.1 Layout of Fixed Rack Type AS/RS We show in Fig.2 the layout of movable rack type AS/RS we analyze. In this figure, the rack moves along the arrow line and 8 racks, each containing 50 cells, are arranged. / 678 Proceedings of 1996 ICC&IC Fig.2 Layout of Movable Rack Type AS/RS Thus, this AS/RS can store 400 pallets. This means that the capacity increases 33% in comparison with fixed rack type case for the same space. It is noticed that, in this case, the additional route of stacker crane is attached in order that the crane access to the appointed cell is not hindered by the placement of rack. Specifications of AS/RSs are as follows. Cell size is 3 (W)*3 (D)*2 (H) (ft). Distance between I/O station and rack edge is 6 (ft). Crane speed along vertical line is 2 (sec/row). Pick and place time at the I/O station is N(10,2) (sec). Pick and place time at the cell is N(10,2) (sec). The crane works as follows depending on the function. STORE : move to the appointed I/O station - pick the requesting pallet - move horizontally to the place where appointed cell is located - go up to the cell - place the pallet to the cell - go down to the ground line - wait for the next job Experimental conditions are summarized as follows. (a) Job request occurs randomly and inter arrival time of the request follows exponential distribution. (b) Storage and retrieval jobs occur under equal frequency. (c) Cell is appointed randomly. (d) For the movable rack type case, neighboring racks move pair wise, if necessary. Simulation of 8 hours is performed, using system simulator SIMAN 6, for various values of mean inter arrival time of the request. The horizontal speed of the crane is also varied. Obtained results on the mean processing time (including both of storage and retrieval jobs) of a pallet are shown in Fig.3. In this figure, the upper half means the fixed rack type case and the lower one is the case of movable rack type, respectively. 3 lO 3 o RETR/EVE : move horizontally to the place where appointed cell is located - go up to the cell - pick the requesting pallet from the cell - go down to the ground line - move horizontally to the appointed I/(3 station - place the pallet to the station - wait for the next job Here, we employ the following principles for the crane allocation. The crane is allocated to the nearest requesting pallet disregarding its request time. For the pallets which are equally apart from the crane, the FIFO principle is applied. 3, Results and Discussion mean intq ov ne reques iecj 3 0-100 (seo) 300-400 (see) 100-200 (see) n 400-500 (sec) I I 200-300 (see) 500-600 (seo) Fig.3 Mean Processing Time of a Pallet Here, for the movable rack type case, the speed of the rack is taken as 5(sec/depth). We first notice, in this figure, that the mean processing time in the movable rack type case is always longer than that in the fixed rack type case. To make it clear, the area where the processing time is Proceedings of 1996 ICC&IC 679 comparable is shaded with the same pattern in this figure. Next, in both cases, it is noticed that, as the frequency of the request increases beyond the ability of the crane, the processing time increases drastically. From this figure, we may say that the proper combination of crane speed and inter ardval time of the request should be considered. Next, for the movable rack type, we show in Fig.4 how the processing time is affected during the simulation run by the rack speed. Here, the mean inter arrival time of the request is taken as 45 (sec). =I t rack speed = 7 (see/depth) !:f ,= rack speed = 9 (sec/depff) rack speed = 11 epth) i=0 o coo o (o eo xm iota iota ,ooao simulation time (sec) Fig.4 Processing Time of Each Pallet It is noticed that, even for the same inter arrival time, the deviation of the processing time changes depending on the rack speed. This suggests that, if we select the appropriate speed of the rack considering the frequency of the request, we can hold the small processing time in spite of the additional wasting time generated by the rack movement. costs are to be depreciated over ten years. As to the running cost, we assume the following conditions. Wages for the operator are I (10 4 yen/day) regardless of the rack type. Electd power cost is 0.55 (104 yen/day) for fixed rack type and 0.60 (104 yen/day) for movable rack type, respectively. From above conditions, we can calculate the processing cost of a pallet. We show in Fig.5 the cost performance of the system in terms of the crane speed. 13 o 3 12.6 12 11.6 105 . xed rack type / . a. . 5 7 g crane speed (it/see) Fig.5 Processing Cost of a Pallet It is certain that, so far as we focus only on the cost performance, the fixed rack type is superior for wide range of crane speed. Here, we notice that the processing cost in the movable rack type at crane speed of 7 (ft/sec) is comparable with that in the fixed rack type case at crane speed of 11 (ft/sec). And we remember that the capacity of movable rack AS/RS is33% larger than that of the fixed rack AS/RS. Here we meet the trade off problem. That is, we have to consider (a) processing time, (b) cost performance and (c) capacity of AS/RS altogether. Considering the obtained results total wise, we may say that the movable rack type AS/RS accompanied with medium speed stacker crane is preferable to the fixed rack type AS/RS equipped with high speed stacker crane. From now, we discuss on the effect of the capital investment. Assuming that the initial cost becomes more expensive as the speed of the crane increases, we express the initial cost F(v) as FI(v) = 1200 + 100v (104 yen), (1) 4. Conclusions We performed, using system simulator, the operation analyses of AS/RS. System performances are compared between fixed rack type case and movable rack type case. Conclusions are summarized as follows. where v is the horizontal speed of the crane (ft/sec). Next, additional cost F2 to make the rack movable is set up as 500 (104 yen) regardless of the rack speed. These initial For the movable rack type AS/RS, if we choose the crane speed and rack speed appropriately considering the frequency of the request, the 680 Proceedings of 1996 ICC&IC processing time is not increased so much in spite of the concurrent movement of rack and crane. In terms of the capacity and cost performance, it is better to employ a movable rack type AS/RS with medium speed stacker crane rather than a fixed rack type ASIRS equipped with high speed stacker crane. References 1. Noble, J.S. and Tanchoco, J.MA., 1993, Design Justification of Manufacturing Systems-A Review, The Int. J. of Flexible Manufacturing Systems, 5:5-25 2. ed. by Hollier, R.H., 1985, Proc. of the 6th Int. Conf. on Automation in Warehousing, and references therein 3. Ashayeri, J., Gelders, L. and Wassenhove, L.V., 1985, A Microcomputer-based Optimization Model for the Design of Automated Warehouses, Int. J. of Production Research, 23:4:825-839 4. Takakuwa, S., 1989, Module Modeling and Economic Optimization for Large-scale AS/RS, Proc. of the 1989 Winter Simulation Conference, 795-801 5. LIM, J.M. and Hwang, H., 1994, The Machine Layout Problem in a Flexible Manufacturing System with built-in Automated Storage/Retrieval System, Proc. of APORS94, 366-373 6. Pegden, C.D., Shannon, R.E. and Sadowski, R.P., 1990, Introduction to Simulation Usinq SIMAN, McGraw-Hill, Inc., New York