This paper presents a methodology for implementing the feature recognition system for achieving

the Computer Aided Design/ Computer Aided Manufacturing (CAD/CAM) integration goals. The Featurebased

modeling is being used to model the solid models. The features being considered in this paper is hole

form feature. The input of the feature recognition system is the Standard for the Exchange of Product Model

Data (STEP) files. The set of feature recognition rules is generated by using ruled based technique

Ismail, N.

Tan, CheeFai

English

Universiti Teknikal Malaysia Melaka (UTeM) Repository

World Applied Sciences Journal 21 (8): 1162-1166, 2013ISSN 1818-4952© IDOSI Publications, 2013DOI: 10.5829/idosi.wasj.2013.21.8.2126Corresponding Author: Chee Fai Tan, Integrated Design Research Group (IDeA), Faculty of Mechanical Engineering,Universiti Teknikal Malaysia Melaka, Melaka, Malaysia.Tel: +6062346710,  Fax: +6062346884.1162Design of a Feature Recognition System for CAD/CAM IntegrationChee Fai Tan, V.K. Kher and N. Ismail1 1 2Integrated Design Research Group (IDeA), Faculty of Mechanical Engineering,1Universiti Teknikal Malaysia Melaka, Melaka, MalaysiaFaculty of Engineering, Universiti Putra Malaysia, Selangor, Malaysia2Abstract: This paper presents a methodology for implementing the feature recognition system for achievingthe Computer Aided Design/ Computer Aided Manufacturing (CAD/CAM) integration goals. The Feature-based modeling is being used to model the solid models. The features being considered in this paper is holeform feature. The input of the feature recognition system is the Standard for the Exchange of Product ModelData (STEP) files. The set of feature recognition rules is generated by using ruled based technique.Key words: CAD/CAM  Form feature  STEP  Feature-based modeling  Feature recognitionINTRODUCTION applications is based on the possibility to associateDuring the past 10 years, research on CAD/ CAM Product and process information can be retrieved from theintegration had focused on product representation feature-based model to support manufacturing tasks suchtechniques or product modeling that contains more as process planning, assembly planning and fixturecomplete product information and providing better design [1].interfacing opportunities between CAD and CAM Data exchange and system integration have becomesystems. One of the most popular modeling approaches important consideration in computer-aided systems infor manufacturing activities involves the use of feature order to improve productivity. This had led to thebased models [1]. The commercial CAD/CAM marketplace development of neutral format that is used to facilitateis still very much in its infancy, with many vendors product data exchange between manufacturingfulfilling limited niches, each with their own particular components. In the early 1980s, National Institute ofsuite of integrated software modules and data structures. Standards  and  Technology  (NIST) have adopted STEPA de facto CAD/CAM integration scheme has yet to to   represent  product  data  throughout  its  life-cycle.emerge  [2].  For the CAD/CAM integration, the basic The standard is an extension of previously definedparts  are  the  feature  and feature-based representation. standards such as IGES, VDAF and DXF. STEP providesIn general, the feature can be viewed as higher level a wider coverage of product model to encompass severalentities that integrate the information between design and computer-aided applications and as a basis towards fullymanufacturing. For example, the topological and integrated system [3]. There are two main approaches thatgeometrical  information  consists in CAD, feature can be have been developed in conjunction with feature basedused to represent how the part can be manufactured. models [4]:Feature based modeling is viewed from themanufacturing viewpoint as more suitable for modeling Design-by-features in which the designer create thebecause it deals with shape attributes related to part directly as a combinations of standard features;manufacturing. With feature based models, shape andinformation and other information (such as functional and Feature recognition which involves computationallynon-geometrical information) can be stored. The potential recognizing features from conventional geometricalof feature based CAD in supporting manufacturing models.feature  types  with manufacturing process models.Block CylinderHoleBossThrough slotWorld Appl. Sci. J., 21 (8): 1162-1166, 20131163The feature recognition approach is to extract theinformation that are needed from the CAD database.Feature recognition is a step to reduce the lead timebetween design and manufacturing. Abdalla [5] hadproposed a technique that has the capability to extractrequired feature directly from the database of a CAD solidmodeling system. The technique has the capability to (a) Design featuresextract the necessary topological and geometricalinformation from the solid modeler. There are manyapproaches that have been proposed to recognize andextract the feature from B-rep solid models, which areArtificial Intelligent (AI), Graph-based, Syntactic Patternrecognition and Neural Network (NN) [4].This paper focuses on feature recognition of formfeature from 3D CAD models such as hole by using STEPfile. The UniGraphics (UG) CAD system had been adoptedin this paper for the feature-based modeling environmentand generation of STEP files. The STEP files that consist (b) Manufacturing featuresof geometrical information will used in feature recognitionsystem. The feature recognition rules are generated by Fig. 1: Design Features and Manufacturing Features [6]using ruled based technique.Form Feature and Feature: A feature is an entity or region of a closed oriented surface bounded by onegeometric  form.  Its  attributes (dimensions, shape, etc.) or more edge loops.are very important for various industrial functions, suchas analysis, evaluation and process planning. The feature For B-rep models, it was found out that the moreattributes must be represented explicitly in terms of forms useful data are the topological and the geometricalthat match available manufacturing knowledge. Example information. The topology data describes theof form features are holes, slots, cuts, rounds and notches connectedness between the components while geometry[5]. specifies the dimensions and location of each componentRecently, there are two classifications of features, [6].which are manufacturing features and design features.The manufacturing features used by production planning Feature-Based Modeling: Recently research towardsengineers in manufacturing process planning, whereas the CAD/CAM integration has concentrated on feature-baseddesign features is the features that defined by design models to design the part model. Part description inengineers at the design stage [11-13]. Fig. 1 shows the current CAD model is in the form of basic geometrydifferences between the two features. Feature contains (faces, lines, points) and topology that is unsuitable formanufacturing oriented information where it is the basis direct application in manufacturing process such asfor integration between CAD/CAM [6]. The feature process planning. This problem can be overcome byrepresentation in this paper is using boundary defining  a  part in terms of high level geometric entitiesrepresentation (b-rep). According to Ismail [1], the like holes, steps and slots,. which are called features [7].elements of the B-rep data structure has the following The feature-based modelings for this paper is under thecharacteristics: UG  CAD  system. The form features are modeled usingA vertex (v ) is a unique point in x, y, z coordinates. A system, the designer has to create a base feature and addivertex is typically shared by three faces or surfaces). the features by subtracting them from the base feature.An edge (e ) is a finite, a non self-intersecting, The form features being considered in this paper areidirected space curve bounded by two vertices. holes. According to Salomons [8], from a design point ofA set of connected edges that form the close view, feature based modeling has much better potentialboundary of a non-self-intersecting face is known as for computer support of the design process than currenta loop or also referred to as an edge loop. non-feature-based  CAD system. Features able to help theA face is a finite connected, non-self-intersectingthe feature available in the UG feature library. In thisModel part using design-by-features approachConvert to STEP fileExtracting geometrical data from STEP filesDevelopment of feature recognition systemForm FeatureHoleThrough BlindWorld Appl. Sci. J., 21 (8): 1162-1166, 20131164designer to speed up their design process based onstandardization. The feature is able to reduce the designcost, shorter time to market, better design quality as wellas able to integrate different applications such as processplanning and analysis.System Implementation: The solid model will produce aSTEP  file  using  Unigraphics postprocessor. The STEPfile  contains  the  geometrical  data  of  the solid model.The information in the STEP file maintains the structureand dimensions of the solid model and B-rep informationof the solid. The STEP representation format can be usedin different CAD system.The feature recognition system in this paper is Fig. 2: The methodology for feature recognitionimplemented in three modules which are as follows.Module 1 - generate the STEP file. The UG STEPgeneration tools being used to translate the part tostandard STEP representation and store as STEP file.Module 2 – interrogate and extract the geometricinformation of STEP file. The data is then processedand input to the feature recognition system.Module 3 – feature recognition using geometrical andrule-based technique.Fig. 2 Shows the methodology for feature recognitionin this paper. Fig. 3: Taxonomy of features (Hole)In this paper, the hole has been proposed to use infeature recognition system. The taxonomy of a hole is RESULT AND DISCUSSIONSshown in Fig. 3. The STEP file contains the entities suchas circles, lines, planes and text. Every entity has The  B-rep  is  a  explicit  feature   representation.  Aassociated with various attributes like color and linetype. B-rep  solid  model is constructed using entities like lineTo take an example, the line entity in STEP may look (or edges),  faces  and  points  (or  vertices). Fig. 4 andas follows: Fig. 5 shows the examples of B-rep model of through and#37= LINE(‘’,#34,#36); the entity type The B-rep models are converted to STEP#39=CARTESIAN_POINT(‘’,(2.,0.,2.)); the first point representation  format  through UG postprocessor [10].#41=CARTESIAN_POINT(‘’,(0.,0.,2.)); the second point The output of the 3D model for Figure 4 in the STEP#35=DIRECTION(‘’,(-1.,0.,0.)); the extrusion direction representation format is shown in Fig. 6.The rule-based approach uses AI technique to paper. The type of a form feature can be recognized bydevelop a set of rules. According to Ismail [9], the using the following approach:algorithms identify a feature based on certain pre-specified  rules  that  are  characteristic  to  the  feature. IF [A] THEN [B]The following set of heuristic rules is used to describe athrough hole feature [9]: where  A  are  the condition and B are the results. TheIF circular edges are found and recognize the through hole and blind hole. ThePoint in cir_edge1 and cir_edge2 is 1 recognition of through hole was proposed through theTHEN identify through hole following rule:blind hole which is proposed to be recognize in this paper.The rules for feature recognition are proposed in thisrules that had been proposed for this paper is used to#19=CARTESIAN_POINT('',(0.,0.,0.));#20=DIRECTION('',(0.,0.,1.));#21=DIRECTION('',(1.,0.,0.));#22=AXIS2_PLACEMENT_3D('',#19,#20,#21);#23=CARTESIAN_POINT('',(1.,1.,2.));#24=DIRECTION('',(0.,0.,-1.));#25=DIRECTION('',(-1.,0.,0.));#26=AXIS2_PLACEMENT_3D('',#23,#24,#25);#27=CIRCLE('',#26,0.5);#28=EDGE_CURVE('',#30,#30,#27,.T.);#29=CARTESIAN_POINT('',(0.5,1.,2.));#30=VERTEX_POINT('',#29);#31=ORIENTED_EDGE('',*,*,#28,.T.);#32=EDGE_LOOP('',(#31));#33=FACE_BOUND('',#32,.T.);#34=CARTESIAN_POINT('',(1.,0.,2.));#35=DIRECTION('',(-1.,0.,0.));#36=VECTOR('',#35,1.);#37=LINE('',#34,#36);#38=EDGE_CURVE('',#40,#42,#37,.T.);#39=CARTESIAN_POINT('',(2.,0.,2.));#40=VERTEX_POINT('',#39);#41=CARTESIAN_POINT('',(0.,0.,2.));#42=VERTEX_POINT('',#41);#43=ORIENTED_EDGE('',*,*,#38,.F.);#44=CARTESIAN_POINT('',(2.,1.,2.));#45=DIRECTION('',(0.,-1.,0.));#46=VECTOR('',#45,1.);#47=LINE('',#44,#46);#48=EDGE_CURVE('',#50,#40,#47,.T.);#49=CARTESIAN_POINT('',(2.,2.,2.));#50=VERTEX_POINT('',#49);#51=ORIENTED_EDGE('',*,*,#48,.F.);#52=CARTESIAN_POINT('',(1.,2.,2.));#53=DIRECTION('',(1.,0.,0.));#54=VECTOR('',#53,1.);#55=LINE('',#52,#54);#56=EDGE_CURVE('',#58,#50,#55,.T.);#57=CARTESIAN_POINT('',(0.,2.,2.));#58=VERTEX_POINT('',#57);#59=ORIENTED_EDGE('',*,*,#56,.F.);#60=CARTESIAN_POINT('',(0.,1.,2.));#61=DIRECTION('',(0.,1.,0.));#62=VECTOR('',#61,1.);#63=LINE('',#60,#62);World Appl. Sci. J., 21 (8): 1162-1166, 20131165Fig. 4: B-rep model of a part with through holeFig. 5: B-rep model of a part with blind holeIFTotal circle number = 2 &Total cylindrical number = 1 &Face type = cylindrical_surface &The two circle are subtract from the adjacent planeThe two circle are adjacent to cylindrical_surfaceTHENFeature type = hole (through)The blind hole was recognized through the followingproposed rule:IFTotal circle number = 2 & Face type of one circle = plane & Fig. 7: The User interface main menuFig. 6: Output of STEP file for part with through holeWorld Appl. Sci. J., 21 (8): 1162-1166, 20131166Total cylindrical number = 1 & 3. Shaharoun, A.M. and J.A. Razak, 1999. STEP-BasedFace type = cylindrical_surface & Central Repository for Product Data Sharing AmongOne circle is subtract from the adjacent plane Computer-Aided Systems in ManufacturingOne circle is adjacent and perpendicular to cylincrical - Applications. Proceeding of Worlds Engineeringsurface Congress 1999- Towards the Engineering Vision:THEN 4. Shah, J.J. and M. Mantyla, 1995. Parametric andFeature type = hole (blind) Feature-Based CAD/CAM. John Wiley and Sons,Inc. Tseng.The proposed rules for through hole and blind hole 5. Abdalla, H.S. and J. Knight, 1994. An Expert Systemwill input to the feature recognition system. The rules will for Concurrent Product and Process Design ofuse to define the STEP file accordingly. The user interface Mechanical Parts. Proceeding Institution Mechanicalfor feature recognition system also being developed in Engineers, 208: 167-172.this paper. Fig. 7 show the user interface and the 6. Ismail, N., C.F. Tan and S.M. Sapuan, 2000. Formparameter selection menu respectively. Feature for Concurrent Engineering. 2000 TENCONCONCLUSION for the New Millennium, 3: 468-471.A prototype feature recognition system has been Features from B-rep Solid Models. ASEAN Journal ofproposed to support the CAD/CAM integration. Science and Technology Development, 14(2): 35-49.Currently  the  form  features recognized through holes 8. Salomons, O.W., 1995. Computer Support in theand blind holes. The part is modeled using the design-by- Design of Mechanical Products. Ph.D Thesis,features approach of the UG CAD system module. Then University of Twente.geometric description of part is presented in STEP neutral 9. Ismail, N. and N. Abu Bakar, 1997. Recognition ofdata format. For the purpose of feature recognition Machined Features from Solid Database of Prismaticprocess,  the  STEP  format  must  be  sorted  first. The Components. Pertanika Journal of Science andrule-based  technique  had  been proposed for this paper Technology, 5(2): 231-240.in order to extract the features data. The user interface 10. Unigraphics User Menual Version 13, 1997also being proposed for the feature recognition system. (Electronic Data System Corporation, UnigraphicsFor future research, the recognition of complex hole Division, MO USA).features and other features such as slots, pockets, 11. Sunil, V.B. and S.S. Pande, 2008. Automaticbosses, step and ribs can be developed. Recognition of Features from Freeform Surface CADREFERENCES 12. Ran, J.Q. and M.W. Fu, 2010. Design of Internal Pins1. Ismail,   N., N.   Abu   Bakar,   M.R.   Osman  and Recognition of Undercut Features. Computer-AidedS.M. Sapuan, 1999. Feature Recognition Approach Design, 42(7): 582-597.for Computer Aided Manufacturing. Proceeding of 13. De Martino, T., B. Falcidieno and F. Giannini, 1994.Worlds Engineering Congress 1999- towards the An Adaptive Feature Recognition Process forEngineering Vision: Global Challenges and Issues, Machining Contexts. Advances in Engineeringpp: 325-329. Software, 20(2-3): 91-105.2. Regli, W., 1995. Geometric Algorithms forRecognition of Feature from Solid Models. Ph.Dthesis, University of Maryland.Global Challenges and Issues, pp: 215-219.Proceedings: Intelligent Systems and Technologies7. Ismail, N. and A.N. Bakar, 1997. Recognition ofModels. Computer-Aided Design, 40(4): 502-517.in Injection Mold CAD via the Automatic

Design of a Feature Recognition System for CAD/CAM Integration

http://eprints.utem.edu.my/id/eprint/7369/1/J_WASJ_cft-vkk-ni.pdf

Design of a Feature Recognition System for CAD/CAM Integration

Abstract

Similar works

Full text

Available Versions

Universiti Teknikal Malaysia Melaka (UTeM) Repository