翻译原文-自动设计系统开发的级进模设计.pdf

An automated design system for progressive die S. Kumar a, R. Singhb aDepartment of Mechanical Engineering, S.V. National Institute of Technology, Surat, India bDepartment of Mechanical Engineering, D.C.R. University of Science and Technology, Murthal, Haryana, India a r t i c l ei n f o Keywords: Progressive die Knowledge-base system Production rules AutoCAD a b s t r a c t This paper describes an automated design system developed for design of progressive die. The proposed system is organized in 27 knowledge-base modules. The production rule based knowledge-base system (KBS) approach is utilized for constructing the system modules. Modules are user interactive and designed to be loaded into the prompt area of AutoCAD. The system is capable of automating all major activities of design of progressive die such as checking the design features of sheet metal parts, design of strip-layout, selection of progressive die components, modeling of die components and die assembly, and selection of materials for progressive die components. The system is implemented on a PC having AutoCAD software and therefore its low cost of implementation makes it affordable by small and medium size enterprises. ? 2010 Elsevier Ltd. All rights reserved. 1. Introduction A progressive die is used worldwide for mass production of sheet metal parts. Design of progressive die is a complex and highly specialized procedure and typically progressive die design takes 20% of the lead time from the concept design to the fi nal stamping manufacture. The diverse nature of products produced by progressive die demands a high level of knowledge on the part of the die designer that can only be achieved through years of prac- tical experience. Checking the design features of sheet metal parts, design of strip-layout, selection of die components, selection of materials for die components; and modeling of die components and die assembly are major activities for designing a progressive die. The traditional methods of carrying out these tasks require expertise and are largely manual and therefore tedious, time con- suming and error-prone. The quality of die design depends to a large extent on the designers skill, experience and knowledge. A number of researchers have tried to develop computer aided sys- tems for progressive die. For example, Murikama and Shirai (1989) developed a CAD/CAM system which is capable of generat- ing assembly and dimensioned part drawings as the fi nal output but the strip and die layouts have to be done manually by the de- signer. Researchers at National University of Singapore and Insti- tute of High Performance Computing, Singapore also reported to have developed an integrated modelling and process planning system (2002) for planning bending operations of progressive dies. Sima, Lee, and Jang (2004) carried out the study on the develop- ment of center carrier type progressive die for U-bending part pro- cess. Ghatrehnaby and Arezoo (2009) reported to develop an automated nesting and piloting system for progressive dies. Some researchers reported to have developed intelligent CAD systems for progressive die. For example, Duffy and Sun (1991) developed a knowledge-based system for the design of progressive stamping dies using a feature-based approach. Lee, Lim, and Nee (1993) developed IKOOPP, an intelligent knowledge-based process plan- ning system for the manufacture of progressive die plates. Cheok, Foong, and Nee (1996) reported to have developed an intelligent planning aid for progressive die design using PC development tools. Ismail, Chen, and Hon (1996) have also worked on expert systems for progressive piercing and blanking die design. Zheng, Wang, and Li (2007) have developed intelligent CAPP system for automobile panels. Commercially available CAD/CAM systems are providing a great deal of assistance in drafting and analysis in die design process, but human expertise is still needed to arrive at the fi nal design. Also, the high cost associated with setting up such systems is quite often beyond the reach of small-scale sheet metal industries. Some researchers have used AI techniques to conserve experienced based knowledge of die design experts. But the use of these sys- tems is very limited. They can either handle only blanking and piercing operations or parts with relatively simple geometry. It appears that the development in progressive die automation have not kept pace with advancement in AI technology. Thus, there is a stern need to develop an automated design system for progressive dies having low cost of implementation using both CAD and AI approach collectively, which can be easily affordable by small and medium scale sheet metal industries. This paper describes an automated design system for accomplishing the tedious and time 0957-4174/$ - see front matter ? 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.eswa.2010.09.121 Corresponding author. Mob.: +91 9824590088. E-mail address: skbudhwarmed.svnit.ac.in (S. Kumar). Expert Systems with Applications 38 (2011) 44824489 Contents lists available at ScienceDirect Expert Systems with Applications journal homepage: /locate/eswa consuming design task of progressive die with very ease and in a very short time period. 2. Considerations for design of progressive die 2.1. Strip-layout design As a fi rst step in the planning of manufacture of a sheet metal part, it is useful to check whether certain of its design features are conducive to ease of manufacture. Such checks are useful to avoid manufacturing defects, section weakness, and need of new dies, tools or machines. Dimensions and location of internal and external features such as holes, extended holes, internal contours, external contours, cuts, notches, bosses, cups, slots and bends should be tested against rules of good practice. Strip-layout design is to arrange layout of the operations and subsequently determine the number of stations required. Strip layout is mainly governed by the geometrical features of the part, tolerance on dimensions of the part, direction of sharp edge of stock strip and other technical requirements. There is no unique best solution for the strip-layout design but the some basic guidelines (Kumar, 2006) are generally considered during this important activity. 2.2. Selection of die components Die block, die gages, stripper plate, punch plate, back plate, punches, pilots, die-set and fasteners are major components of a progressive die. The size of the die block depends on sheet thick- ness, direction of sharp edge, strip-width, type of die material and length of strip-layout. Size of die gages mainly depend on the sheet thickness. But the minimum thickness of die gauges is also restricted by risk of camber, which may occur during heat treatment process of their manufacturing. The width of die gages may sometimes be increased to maintain the symmetry of progres- sive die. Strippers are of two types: fi xed or stationary and spring loaded or movable. The size of stripper plate corresponds to the size of die block. The width of channel in the stripper should be equal to the strip width plus adequate clearance to allow for vari- ations in the strip width. The punch plate is used to position and support the punches. The punch plate should have suffi cient thick- ness for providing enough support, good dowelling to ensure accu- rate alignment and adequate screws to overcome the stamping load. The thickness of punch plate is a function of punch diameter. In case two or more than two punches are mounted, the punch having biggest diameter is considered for selecting suitable thick- ness of punch plate. Punch plate thickness should also be propor- tional to the overall punch height. The length and width of the punch plate is usually same as of die block. Hardened back-up plates are normally interposed between small perforator punches and the punch holder. The backup plate is generally about 10 12 mm thick. In the selection process of die-set of progressive die, one should consider part quantity, dimensional tolerance of the component, clearance between punch and die, and clearance between guideposts and bushings. It is considered a good practice to use steel die-sets to prevent fractures of the die holder. The main steps usually carried out for selecting a die-set are determination of the type of the die-set (two pillar, four pillar, rear pillar, center pillar, diagonal pillar, etc.), selection of the die area and choice of the die holders. Selection of the kind of die-set depends upon the type of sheet metal operation, part quantity and job accuracy. The dimensions of the die-set depend upon the length and width of the die and its placement in the die-set. If available, standard die-sets can be used or these can be custom-built. In industries, the number and size of fasteners (screws and dowels) are selected on the basis of size of die block. Dowels are usually located near diagonally opposite corners of the die block, for maximum locating effect. Screws and dowels are preferably located about 1.52.0 times their diameter from the outer edges or the blanking contour. Screws are used to assemble the die details on top and bottom bol- ster of die-set. The number and size of screws may be calculated by estimating the space available and the load to be resisted. 2.3. Selection of materials for die components Selection of materials for progressive die components for a gi- ven application depends on which die failure mechanisms domi- nates. For selecting the suitable material for a progressive die component, the die designer properly investigates the functional requirements of that component and then a critical study is carried out to identify the required mechanical properties and possible causes, which may result the failure of the component. The basic idea of a die designer is to select a suitable material for a particular die component such that all other failure mechanisms except wear are eliminated. The wear can then be optimized to match the re- quired production quantity of sheet metal parts. To obtain longer die life and hence higher productivity, tool steels are being widely used as materials for die components. One of the most important advantages of using steels as cutting tool materials is that, they are originally soft and machineable, by applying suitable heat treatment, they become extremely hard and wear resistant. Selec- tion of suitable hardness range of selected materials of die compo- nents depends on the geometry of the part to be manufactured on progressive die. 2.4. Modeling of die components and die assembly Modeling of progressive die involves the modeling of plate ele- ments and die-set. Modeling of plate elements requires the dimen- sional data of die block, die gages, stripper plate, punch plate and back plate. The dimensions of plate elements as recommended by an intelligent system and stored in various output data fi les can be utilized for their modeling. Drawing commands of AutoCAD such as LINE, PLINE, CIRCLE, FILLET, LAYER etc. can be invoked for modeling of plate elements. Further for automatic modeling of plate elements, one may recall the strip-layout stored in a fi le and may insert it appropriately in the plan view of plate elements. For automating modeling of die-set, the dimensional data of bot- tom and top bolster of die-set, diameters of guide pillars and guide bushes stored in an output data fi le can be utilized. Based on the above considerations, an automated system namely INTPDIE is developed for design and modeling of progres- sive die components. 3. Automated design system: INTPDIE 3.1. Procedure for development of the proposed automated design system The procedural steps for the development of the proposed auto- mated system include knowledge acquisition, framing of produc- tionrules, verifi cationofproductionrules,sequencingof production rules, identifi cation of hardware and computer lan- guage, construction of knowledge base, choice of search strategy, and preparation of user interface. The technical knowledge for the development of system is collected through die design hand- books, industrial brochures, technical reports, and highly experi- enced progressive die designers and tool manufacturers. The knowledge thus acquired is analyzed and tabulated in form of pro- duction rules of IF-THEN variety. The production rules so framed are verifi ed from a team of progressive die design experts and tool S. Kumar, R. Singh/Expert Systems with Applications 38 (2011) 448244894483 manufacturers. Production rules in each module of the proposed system are arranged in a structured manner. The proposed system is implemented on PC (Pentium 4 CPU, 2.4 GHz, 256 MB of RAM) with Autodesk AutoCAD 2004. The production rules incorporated in all the modules of the proposed intelligent system have been therefore coded in AutoLISP language. The production rules and the knowledge base of the system are linked together by an infer- ence mechanism, which makes use of forward chaining. In forward chaining, the user interactively supplies system data or facts about the problem to be solved. The system works with input informa- tion supplied by the user coupled with knowledge stored in the knowledge base, to draw conclusions or recommendations. The system searches the IF conditional data to determine which rules are satisfi ed by the given facts. Whenever a particular IF condition is found to be satisfi ed then the THEN portion of the rule is acti- vated leading to a conclusion or an advice. The developed knowl- edge-based system INTPDIE overall comprises of more than 1000 production rules of IF-THEN variety. A sample of production rules incorporated in various modules of the system INTPDIE is given in Table 1. 3.2. Organization of the system As the progressive die design process comprises of many activ- ities, the whole system INTPDIE has been structured into various sub-systems, modules and sub-modules. Organization of the devel- oped system INTPDIE is shown in Fig. 1. The various modules and sub-system of the system INTPDIE are briefl y described as under: 3.2.1. Module CCKBS The module CCKBS is developed for checking the design fea- tures of sheet metal parts from manufacturability point of view. The module is capable of checking the part design features such as size of blank, size of holes, hole pitch, corner radius, distance of the internal features from the edge of the part, distance between two internal features, width of recesses or slots or projections, bend corner radius etc. It also recommends the minimum scrap web allowances for manufacturing the parts on a progressive die. This module incorporates an interface for displaying friendly prompts to guide the user during a consultation session. The data supplied by the user is also stored in a fi le, called as COMP.DAT for use in subsequent modules. 3.2.2. Module SELDIE The module SELDIE is developed to assist the die designer and process planner in the selection of a suitable type of die for manu- facturing of sheet metal parts. The module is designed to take re- quired inputs such as production requirement and tolerance on the part from the part data fi le COMP.DAT. The user is also invited to enter other required inputs involving number and type of sheet metal operations through the prompt area of AutoCAD. As soon as the user enters these inputs, the module imparts intelligent advice for selection of suitable type of die. 3.2.3. Module MAXUTL The module MAXUTL is developed for determining the angle of orientation of blank. The module incrementally alters the orienta- tion of blank by 1? and then calculates the material utilization of sheet at each angle till the blank has been rotated by 180? from its initial position. The orientation that has the maximum utiliza- tion ratio is the optimal. The outputs of the module are automati- cally stored in a data fi le labeled as MAXUTL.DAT. 3.2.4. Sub-system ISSLD The sub-system ISSLD is developed for intelligent design of strip-layout for metal stamping work on progressive die. The exe- cution of the sub-system is shown through a fl ow chart in Fig. 2. This sub-system comprises of six modules. The fi rst module OPR- PLAN determines the type of sheet metal operations required to manufacture the part. The module invites the user to supply rele- vant input data namely dimensional tolerance and geometrical fea- tures of the part. The outputs of this module are in the form of recommendations for the type of sheet metal operations required to manufacture the part. The next module OPRSEQ of the sub-sys- tem determines the sequencing of recommended sheet metal oper- ations. It takes its input directly from the output data fi le OPRPLAN.DAT generated during the execution of module OPR- PLAN. The module PLTSEL is developed for selection of proper piloting scheme for positioning the strip accurately in each station of progressive die. The next module OPRSTAGE is developed for Table 1 A sample of production rules included in the system INTPDIE. S. No.IF (condition)THEN (action) 1Sheet material = soft steel or brass or aluminium; and shape of hole = round; and 0.4 mm 6 minimum round hole diameter P sheet thickness Accept the diameter of round hole 2Production quantity P 100,000; and 0.001 4.0; and required tonnage 6 8.0, and required production rate/min 50; and required production rate/min 6 1200; and type of sheet metal operations = shearing Select hand or mechanical or hydraulic or pneumatic press of 10 or 20 tons capacity 7Sheet thickness 6 1.6 mm; and die material = tool steelSelect thickness of die block = 28.0 mm 8100.0 5 Kgf/mm2; and shear strength of sheet material 6 20 Kgf/mm2; and type of operations = shearing; and production quantity 6 100,000 Please select an easily available material for punch and die/inserts from the following: EN-31 (5660 HRC) (AISI 52100) (IS 103 Cr 2) OR UHB-ARNE (5462