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  1. 1. Shrikant.V.Peshatwar, L.P Raut / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 3, Issue 1, January -February 2013, pp.1591-1596 Design and Development of Fixture for eccentric shaft: A Review Shrikant.V.Peshatwar* L.P Raut ** *M-Tech(CAD/CAM) Student,Department of Mechanical Engineering G.H. Raisoni college of Engineering Nagpur-16. India**Assistant Professor, Department of Mechanical Engineering G.H. Raisoni college of Engineering Nagpur-16 .IndiaABSTRACT This paper present a fixture design Steel Institute) classification and SAEsystem of eccentric shaft for ginning machine.. 1020 first two digit indicate the class to which theFixture is required in various industries steel belongs, the last two digit indicate carbonaccording to their application. Designer design contain.fixture according to dimension required by CLASS TYPES OF STEELindustry to fulfill our production tar gate. In 1) 10XX Plain carbon steeltraditional manufacturing process performing 2) 11XX Free cutting (carbon )steeloperation on eccentric shaft is critical. so holding 3) 13XX Manganese steelsa work piece in proper position during a 4) 2XXX Nickel steelsmanufacturing operation fixture is very 5) 3XXX Nickel –chromium steelsnecessary and important. Because the shaft is 6) 4XXX Molybdenum steelseccentric so for this requirement of 7) 5XXX Chromium steelsmanufacturing process Designer design proper 8) 6XXX Chromium vanadium steelsfixture for eccentric shaft. 9) 7XXX Tungsten steelsFixtures reduce operation time and increases 10) Nickel chromium molybdenumproductivity and high quality of operation is 8XXX steelspossible. 11) Silicon manganese steels 9XXXKeywords- Eccentricity, Fixture design, Computer SAE 1015 and below are highly ductile and are usedaided fixture design (CAFD) for press work but not for fixture.(ref from Jig and Fixture Design manual by Erik Karl Henriksen)1. INTRODUCTION The fixture is a special tool for holding a 2 .LITERATURE REVIEWwork piece in proper position during manufacturing 2.1 Fixture designers support expert system andoperation. It is provided with device for supporting concurrent engineeringand clamping the work piece. Fixture eliminates Researcher give the main lines of theirfrequent checking, positioning, individual marking, process, that fixture design support system isvacillate uniform quality in manufacture. This developed on the basis of an expert system shell.increase productivity and reduce operation time. Researcher show how the use of that kind of tool isFixture is widely used in the industry practical determinant factor for reactivity in the fixture designproduction because of feature and advantages. process in concurrent engineering. Eccentric shaft is a circular or cam type The paper focuses of the development ofdisc solidly fixed to rotating axel with its centre fixture designer‟s support. Researcher present aoffset from that of the axel. eccentric shaft is the structuring of the design method and expression ofimportant element, which plays the important role in the trade rules in the expert system formalism.ginning operation. Researcher has developed using industrial expertise Shaft provides an oscillatory motion to SEACMU (System Expert dAide il la Conceptionmoving knives and widely appreciated for its des Montages dUsinage for expert system forfeatures like effective performance, corrosion fixture design). That is a fixture designers supportresistance, reliability, long service. Reducing expert system..SEACMU is based on a fitted partmanufacturing cycle time and achieving high quality modeling to the fixture design.of operation fixture design is very important. The correspondent model is defined fromDesigner design a compact type fixture for eccentric the part CAD/CAM data using RI rules. RI rules areshaft for fulfilling production target and high quality the necessary link between the part CAD/CAM andof work and increases productivity. the future design expert system. The general organization set out on figure 3 results of the1.1 Material of fixture decomposition in rules basis. Steel specified by SAE (Society ofAutomobile Engineers) and AISI(American Iron and 1591 | P a g e
  2. 2. Shrikant.V.Peshatwar, L.P Raut / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 3, Issue 1, January -February 2013, pp.1591-1596 Fig.3. Flow diagram of the CAFD system [2] The jig and fixture parts and component areFig.1.Knowledge bases organization[1] divided into following categories: (a) Locating components, (b) Clamping mechanisms,(c) ToolA simultaneously development of the fixture design, guiding components, (d) Support components,the manufacturing schedule establishment and the (e)Body of fixture, (f) Fixing components forNC programmed design is then allowed[1]. fixture, (g) Auxiliary mechanisms, (h) Operating elements, (i) Power mechanisms, (j) Miscellaneous components.. Paper explored the technology of intelligence and optimization in the process of the jig and fixture design [2]. Two conformability metrics are introduced to account for global and local conformability‟s his design variables are: the number and position of fixture element, fixture element length, static coefficient, fixture element tip radius, and direction of the fixture principal stiffness. Both force Fig.2. Fig.3 controlled and displacement controlled fixtures are Sequential form Concurrent of It was found that conformability and stability of the steps [1] the part its can either increases nor decrease with the positionmachining of contacts depending on their proximity to the line process[1] of action of the external perturbation. Clamping intensity and principal stiffness directions have opposing effects on the stability of force controlled2.2 FIXTURE DESIGN SYSTEM and displacement controlled fixtures [3].(COMPUTER AIDED FIXTURE DESIGN) The manual design of fixture is 2.2 PARAMETRIC STUDY`traditionally a time consuming work in A. Number and position of fixture elementmanufacturing and the experience of designer plays Fig. 4 shows that the local conformabilityan important role in fixture design. metric for P-controlled and U-controlled fixtures (CZ,, and Cza, respectively) follow very similar trends as L4 moves in the +XA direction. In scenario #2 (P2), the addition of L4 came‟s an increase in both conformability metrics and also an increase in stability with respect to the reference case. Locator L4 helps to support the bottom part of the sphere. This explains the increase in stability from PI to P2.Conformability and stability decrease as L4 moves from P2 to P5 as shown in Fig.4 1592 | P a g e
  3. 3. Shrikant.V.Peshatwar, L.P Raut / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 3, Issue 1, January -February 2013, pp.1591-1596Fig.4.Effect of the number and position of fixtureelement[3] Fig.6.Effect of the Clamp Orientation.[3]B. Clamping intensityFor the case of the P-controlled fixture, theclampingForce was changed from 800 N in PI to 900 N in P2andto l000 N in P3. Similarly, the prescribed clampingDisplacements for P2. P3 and P4 are 12.5, 15.0 and17.5pm, respectively. Fig. 5 shows that S, and CzpincreaseWith clamping intensity. Higher clamping loadsproduce larger work piece and contact elasticdeformations causing an increase in Czp. In the caseof the U-controlled fixture stability decreasesslightly with increasing clamping intensity while Cz, Fig.7. Effect of the Static Coefficient of Frictionis not significantly affected. [3]The normal clamping loads necessary to produce the Requirements should be satisfied forprescribed displacements of the U-controlled fixturedo not change significantly when going from 12.5 to fixture:(i)total restraint of the work piece or form17.5 pm (DF,, = 659 N, D2F=n 590 N for 12.5 pm; closure;(ii)accurate locating of work piece ;DIFn= 680 N, D2F,=, 623 N for 17.5 pm). As a (iii)limited deformation of work piece; noresult, the fixture-work piece reaction forces remain interference between fixture components andalmost unchanged from PI to P4. This explains the machine tool;(iv)including ease ofsmall variation of Czu shown in Fig.5 [3]. loading/unloading a work piece. The first two requirements that are essential for the design of fixture layout and can be viewed as the first step of fixturing system design for determination of the number, type and location of fixturing points. researcher propose an efficient algorithm to identify seven frictionless fixturing point ensuring form closure and small positioning error of the work piece from original dense set. Paper addressed the problem of fixture layout design for a 3D curved work piece [4]. Facing a continuously increasing competition worldwide, manufacturing industry are undergoing a critical transition from traditional methods to advanced manufacturing technology many of which are computer based.Fig.5. Effect of the Clamping Intensity [3] In order to increase competitiveness, manufacturers are seeking to improve product quality. Lower production costs, and increase the speed of bringing innovative products to the market. Early years of computer aided fixture design (CAFD), the designer simply used the CAD tool to 1593 | P a g e
  4. 4. Shrikant.V.Peshatwar, L.P Raut / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 3, Issue 1, January -February 2013, pp.1591-1596assemble the drawings on computer screen with a Fixture requires simple configuration, smalllibrary of standard fixture components. clamping force, multi-varieties and small batch Fixture assembly operations are performed production, short design and manufacturing cycle,by specifying coordinates and rotation angles in x-y and low cost. Compare to conventionalplane, which still takes time for manipulating manufacturing processes, the primary advantage ofgeometric entities. One of the most important goals RP is its ability to create almost any shape orof CAFD is to reduce the manufacturing lead time. geometric feature, in this case, production efficiencythe problems associated with current CAFD and manufacturing flexibility will be greatlyapplications include: 1) functions of automated improved.fixture design systems are limited and many The evaluation method proposed in thiscomplex fixture designs still need human interaction paper is going to evaluate the clamping plan fromand using CAFD systems with commercial CAD several aspects as follows: Area factor. Stabilitypackages is time consuming as it manipulates factor, location of clamping point factor. Thegeometric entities around on screen. automation of fixture planning plays a vital role in Outline of rapid fixture design system improving the efficiency of fixture design and(RFDS) which includes several modules and manufacture [7].databases: a) locating method selection‟s) work Fixture layout is the primary task of thepiece information retrieval; c) locator/clamp fixture design. Fixture design is a practical problemselection; d) fixture unit generation and placement; and is crucial to product manufacturing. During thee) interactive fixture design modification; f) locating course of manufacturing processes, such asmethod database and g) fixture component database. machining, assembly, or inspection, it is necessaryIn fixture design, the locating method and locator to immobilize, support, and locate the work piece,clamp selection are based on fixturing requirement this is also referred to as work holding.analysis. A fixture is comprised of a number of basic To help fixture designers in the locating work holding elements such as locators, supports,method selection, a menu-driven locating method and clamps. The task of fixture layout is toclassification tree is designed which makes the determine the number, type, and location of thefixture design process more logical and requires less work holding elements. Second task is referred to asexperience. fixture setup, and its main concern is to avoid Researcher presents a rapid fixture design collision and interference between the machine toolsystem which combines the automated modular and the fixture. Basic Fixture Components isfixture configuration design technique for fixture locator, support, clamps. Fixtures have six basicunit generation and interactive fixture design functional Requirements: (a) stable resting, (b)functions for selections of locating methods and accurate localization.(c) Support reinforcement, (d)locating clamping components [5]. stable clamping, (e) force-closure (or total restraint), Only concerned with achieving three point and (f) quality performance.contacts, which is necessary to re-use the fixture, The focus of the researcher paper is onManufacturing and installation of fixtures are costly effective fixture modeling and efficient numericalfor high volume production runs. In this paper we techniques for automatically generating, analyzing,address the problem of the re-usability of fixtures. and optimizing fixture layout designs for anyResearcher addresses both types of variation in the complex-shaped 3D work pieces [8].context of modular fixtures. For tolerance variation, A fixture is usually modeled as a set ofthey give a method for comparing fixtures in terms supporting, locating and clamping points calledof how much geometric tolerance they will permit fixels. These fixturing points (or fixels) should bebefore failing. For design variation, they identify selected to satisfy two fundamental requirements:design rules that can rapidly check if a proposed part the form-closure constraint and accurate locating ofdesign is consistent with a given previous fixture the work piece in addition to requirements like even[6]. load distribution among the fixturing points, non- Fixture design is a critical manufacturing intersection among the fixels, etc.activity in the production cycle and has great effect The form-closure constraint guarantees thaton product quality, lead time, and cost targets. the work piece is fully constrained without being With the development of computer aided disturbed by any force and moment generatedfixture design (CAFD) system, the efficiency of during manufacturing processes. The requirement offixture design and the cost of production have been accurate localization is to ensure accuracy ofimproved obviously. Fixture planning is an manufacturing operations.important early step in CAFD process, which A fixture must satisfy various functionaldetermines the locating and clamping points on and non-functional requirements listed as follows:work piece surfaces, it contributes so much to total restraint of the work piece or form-closure, i.e.fixture design. able to reject any force and moment generated during manufacturing courses; Accurate locating of 1594 | P a g e
  5. 5. Shrikant.V.Peshatwar, L.P Raut / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 3, Issue 1, January -February 2013, pp.1591-1596the work piece, i.e. the positioning Errors of the Optimum design approach to providework piece should be minimized with given comprehensive analyses and determine an overallpositioning accuracy of the fixturing points; even optimal design to fulfill the multi-functional andload distribution among the fixturing points. high performance fixturing requirements [8]. DualNo interference between fixture components and fixture layout and dynamic clamping forcesMachine tools and “Goodness “under various optimization method based on optimal fixture layoutcriteria, including ease of Loading/unloading a work could minimize the deformation and uniform thepiece. deformation most effectively and it is meaningful Researcher paper presents a simple and for deformation control in NC machining [10].complete algorithm for automatic and optimal An attempt is made in this paper various design andfixture design on 3D work pieces represented by analysis methods in the context of to improve thediscrete points. A new performance index is life of fixture, different fixture geometries areproposed to simultaneously address three compared experimentally and are selected. Thefundamental requirements: form-closure constraint, proposed eccentric shaft fixture will fulfilledminimum locating errors of the work piece, and researcher Production target and enhanced theeven load distribution among the fixturing points efficiency, fixture reduces operation time and[9]. increases productivity, high quality of operation, A fixture is used to establish and maintain reduce scarp.the required position and orientation of a work piecein machine tool. A poor design can lead to REFERENCESundesirable work piece deformation. Consequently, [1] E. Caillaudli 2, 3, D. Noyes2, G. Anglerot1the positions of the locators, clamps and supports and P. Padillal “Concurrent Engineering:should be strategically designed and appropriate an expert system for fixture design” 1995clamping forces should be applied. Typically, it IEEE.relies heavily on the designer‟s experience to choose [2] Zhang Yuru ,Peng Gaoliangthe positions of the fixture elements and to “Development of and integrated systemdetermine the clamping forces. for setup planning and fixture design in The fixture layout and the clamping forces CAPP” International Conference onoptimization become two important aspects in Advanced Intelligent Mechatronicsfixture design. The positions of locators and clamps Monterey, California, USA, 24-28 July,should be properly selected, and the clamping forces 2005J. Newman, Electrochemical Systems,should be calculated so that the work piece 2nd ed., Prentice-Hall, Englewood Cliffs,deformation is minimized and uniformed. In this NJ, 1991.paper, a dual optimization method is presented for [3] Jose F. Hurtado, Shreyes N. Melkote,the fixture layout design and dynamic clamping “Effect of Fixture Design Variables onforces optimization. The objective is to minimize Fixture-Work piece Conformability andthe maximum elastic deformation of the machined Static Stability” 2001 IEEHASMEsurfaces and maximize the uniformity of the International Conference on Advanceddeformation [10]. Intelligent Mechatronic Proceedings 8-12 July 2001 COW Italy3. DISCUSSION AND CONCLUSION [4] Dan Ding Guoliang Xiang Yun-Hui Liu The system has enhanced the efficiency and Michael Yu Wang “Fixture Layoutand reliability of the jig and fixture design and has Design for Curved Workmade the result of the jig and fixture design more pieces*”Proceedings of the 2002 IEEreasonable [1]. international Conference on Robotics 8 It was found that conformability and Automation Washington, DC May 2002stability can either increase or decrease with the [5] Zhang Yuru ,Peng Gaoliangposition of contacts depending on their proximity to “Development of anthe line of action of the external perturbation. It was integrated system for setup planning andalso found that clamping intensity and the principal fixture design in CAPP” Internationalstiffness directions have opposing effects on the Conference on Advanced Intelligentstability of force-controlled and displacement Mechatronics Monterey, California, USA,controlled fixtures [2]. 24-28 July, 2005J. Newman, The problem of fixture layout design for a Electrochemical Systems, 2nd ed.,3D curved work piece [3].Fixture design support Prentice-Hall, Englewood Cliffs, NJ, 1991.that use technological entities to represent the part [6] Yiming (Kevin) Rong, Xingsen (Corry) Li[4]. The problem of the re-usability of fixtures [6]. “Locating Method Analysis based RapidThe automation of rapid fixture planning based on Fixture Configuration Design” Intelligentrapid prototype [7]. Design and Manufacturing, ASME WAM, 1595 | P a g e
  6. 6. Shrikant.V.Peshatwar, L.P Raut / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 3, Issue 1, January -February 2013, pp.1591-1596 PED-Vol. 64, NO. 1, 1992, pp. 15-28.pp. 43-66.1993, pp. 267-271[7] Yan Zhuang, Ken Goldberg “Design Rules for Tolerance-Insensitive and Multi- purpose Fixtures*” ICAR „91Monterey, CA, July 7-9, 1997[8] Jing Yu, Ting Wen, Qingxi Hu “Research on Automatic Planning of Main Clamping Points in Rapid Fixture Design System” 2010 Seventh International Conference on Fuzzy Systems and Knowledge Discovery (FSKD 2010)[9] Michael Yu Wang “OPTIMUM 3D FIXTURE LAYOUT DESIGN” Proceedings of the 3“ World Conference on Intelligent Control and Automation June 28-July 2,2000, Hefei, P.R. China.[10] Yun-Hui Liu “Optimal Fixture Layout Design for 3D Work pieces” Proceedings of the 2004 IEEE International Conference on Robotics 8 Automation New Orleans, LA April 2004.[11] Jig and Fixture Design Manual by Erik Karl Henriksen. 1596 | P a g e