The Study of Globoidal Indexing Cam CNC Machine Tools

Transcription

1 Advanced Materials Research Online: ISSN: , Vols , pp doi: / Trans Tech Publications, Switzerland The Study of Globoidal Indexing Cam CNC Machine Tools Tian Xia 1, a, Ling Xu 1, b, and Jianxing Si 1, c 1 College of Mechanical & Electrical Engineering, Shaanxi University of Science & Technology, Xi an , China a @qq.com, b @qq.com, c @qq.com Keywords: globoidal indexing cam; Solidworks ; five-axis linkage; gantry machine Abstract: Briefly analyzed the development status of the globoidal indexing cam, processing principles and process, put forward the necessity of researching and developing new type NC machine of globoidal indexing cam, the structural design of five-axis linkage NC machine tool of Globoidal indexing Cam. On the basis of using the Solidworks 3D modeling and motion simulation, interference check. Introduction Globoidal indexing cam mechanism works as a new gearing transmission of the automatic machinery to achieve high-speed, high-precision intermittent indexing movement. It has advantages of good motion characteristics, dynamic property, select or design a rich and flexible cam curve to meet the requirements of a variety of complex motion control. It is easier to achieve a good orientating function, wide range of indexing, load capacity and good movement without attaching other devices. In addition, this agency also has advantages of a less design limitation, less control components, low failure rate of the parts, high reliability, compact structure, easy installation and maintenance when compare to traditional intermittent drive mechanism such as a ratchet mechanism, geneva mechanism, incomplete gear. What s more, the development of five-axis globoidal indexing cam machine tools can achieve the cambered cam machining high precision, high quality requirements and improving production efficiency. This study could promote the technology of manufacturing progress to make the production of globoidal internationalization, standardization and serialization. The Machining Principle of the Globoidal Indexing Cam Globoidal indexing cam mechanism was used as two vertical staggered intermittent axis stepper drives. Driving wheel and cam profile were made into arc revolving, ridge-like, separately. Rollers were uniformly distributed on the driven wheel along the radial of the rotary. The indexing paragraph outline promotes the roller to translocation the indexing plate; when the cam goes to the position of intermittent contour, two of the rollers located on the driven wheel cross caught in the cam ring surface protruding ridge to force it stop rotating. The machining principle of the globoidal indexing cam is shown in Fig 1. All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, (ID: , Pennsylvania State University, University Park, USA-06/03/16,15:11:39)

2 Advanced Materials Research Vols Fig 1. The machining principle of the globoidal indexing cam The processing of the globoidal indexing cam is according to the generating theory. The tool is equivalent to the rollers in driven plate which we called active parts. When we treat the arc cam as the passive parts or workpiece, however, it turns out with reverse rotation. The space position and geometric parameters of the relationship were adjusted between the tool which belong to driven plate roller and workpiece (globoidal indexing cam) to make it meet the design requirement. In addition, relative cutting movement of the tool and the workpiece is according to the law of motion which has been set to process the cam. In this situation, the rotation of the rollers in driven plate not only around the roller axis but also the axis of the driven plate; the workpiece is equivalent to globoidal indexing cam which does rotary indexing movement for requirement. Therefore, the globoidal indexing cam processing machine must have dual rotary coordinates. The Processing of the Globoidal Indexing Cam Profile The process of globoidal indexing cam profile is typically use the keyway cutter or flat end mill. The cam rotates around its own axis to ω and meshes with the contour roller (follower) in order to drive indexing coiled axis o and rotates to θ, in addition, the two rotary meet a certain functional relationship θ=f(ω) to make sure that it fellows the transmission requirements of the law. Generally, the camshaft line and roller axis are located on the same plane. In the cutting process, end mills are equivalent to the roller in the transmission process, the tool rotates around its own axis to do the cutting motion and the rotation of cam rough around its own axis ω f to feed motion with the tool which rotates around the o. θ f and ω f meet the same functional relationship of θ f =F(ω f ) as θ and ω. The processing of contour profile of the globoidial indexing cam is shown in Fig 2. The feed motion synthesis by the rotary motion ω f and θ f ; feed velocity vector f is a viable which is associated with θ f, ω f the position of the tool and cutting point position.

3 890 Materials Processing and Manufacturing III Fig 2. The processing of contour profile of the globoidial indexing cam The Integral Structure of the Globoidal Indexing Cam CNC Machine This study according to the research status of globoidal indexing cam CNC machine at home and abroad and based on the development of virtual manufacturing technology to research and develop the cam CNC machine. It determined the five-axis CNC planer milling machine s overall scheme design by comparison with the traditional ones. Meanwhile, the 3D software of Soildworks was used for three-dimensional modeling and parts assembling for the purpose of structural of optimization design to make it meet the design requirement. The five-axis linkage NC machine of the globoidal indexing cam is shown in Fig 3. It has the advantages of easy to modify the parameters of the model of the machine s structure, check the movement interference and drive the update of the solid model. Fig 3. Five-axis linkage of globoidal CNC machine Five-axis linkage CNC machine tool is described in this paper, using the mobile structure of gantry milling machine. The machine tool has the advantage of small occupation area, good dynamic response performance, in order to better ensure the machine accuracy. The rationality of

4 Advanced Materials Research Vols the design of lathe bed affects the stiffness of the machine directly. The upper plane bed has a T-shaped slot and completely through, easy to bed and T-slots finish planed. The gantry frame beam and column will be design as a whole, better rigidity, horizontal milling head can move along the column, to achieve the movement of the Z axis, the horizontal table move along the T-shaped slot to achieve Y axis movement, on which is equipped with vertical worktable to realize X axis feed, the swing of A axis through CNC machine head and the rotation of C axis of the workpiece clamping through NC rotary table. Using the five-axis CNC machine tools, makes it easy to clamping workpiece, processing without special fixture, reduce the cost of the fixture avoid multiple clamping, improves the machining accuracy of globoidal indexing cam. Five axis machine tool can reduce the spindle length in the processing, improving the rigidity of spindle greatly, increase the effective tool cutting edge length, reduce the cutting force, improve the cutting tool service life and reduce cost. Summary According to the existing globoidal indexing cam CNC machine tools, typically, a horizontal CNC milling which has a spindle elongation is excessive, less rigid and the spindle frame stiffness and strength of the material performance requirement is strict is chose for the machine. Therefore, cost of the machine is higher. However, in this study the tool we used is five-axis linkage of globoidal CNC machine which improves rigidity of the spindle obviously. The gantry structure has advantages of simple structure and light, and the stability of the bracing which guarantees it to achieve the accuracy requirement. What s more, the lighter structure is easy to installation and commission. Generally, the machine with simple structure would reduce manufacturing costs. References [1] Hocken R. Three dimensional methodology.annals of tbe CIRP,1994,26: [2] Cao. Ju-Jiang: Proceedings of the 2009 ASME/IFToMM International Conference on Reconfigurable Mechanisms and Robots, ReMAR 2009, p , 2009, [3] Tsay, D. M; Ho, H. C. Consideration of manufacturing parameters in the design of grooved globoid cam indexing mechanisms. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science [4] Farin G. Curves and Surfaces for Computer Aided Geometric Design:A Practical Guide [M]. New York: Academic Press, (1 990) [5] Z.M. Cai. The study of globoidal indexing cam. (2000). In Chinese. [6] X. M. Dai. The virtual modeling and simulation analysis of the high speed gantry machining center. (2005). In Chinese. [7] Wiens G J.An overview of virtual manufacturing.in:virtual Manufacturing-Proceeding of Agile Manufacturing conference (AMC 95X Albuquerque,New Mexico,USAl995.ERI Press:lap

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