A Unified Approach to the Analytical Design of Three-Dimensional Cam Mechanisms

Dhande, S. G.; Bhadoria, B.S.; Chakraborty, Jyoti Prasad

doi:10.1115/1.3438558

Cited by 30 publications

(9 citation statements)

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“…These cam-profile synthesis methods assumed that the cam operated at a constant speed. Dhande et al (1975) provided generalised expressions for equations of the conjugate profile, the pressure angle, and the locations of the cutter. Tesar and Mathew (1976) used analytical functions to synthesise cam profiles.…”

Section: Literature Reviewmentioning

confidence: 99%

Optimisation of cam-follower motion using B-splines

Sateesh¹,

Rao

Reddy

2009

International Journal of Computer Integrated Manufacturing

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This paper proposes design of cam-follower velocity curve by using B-spline polynomials. B-spline polynomials are smooth curves defined by control points. Curve shape can be modified by changing the control points. The traditional design method for improving the motion characteristics of the follower is to find an optimum displacement curve for which follower velocity, acceleration curves to be continuous and their peak values as small as possible (i.e. minimum jerk). B-spline polynomials of degree three and six control points are used in design of follower velocity curve. The B-spline curve is used to approximate the various basic curves which have better motion characteristics. A computer-aided design and computer-aided manufacturing (CAD/CAM) system is developed which generates follower motion curves, i.e. displacement, velocity, acceleration, jerk and cam profiles. An analysis is carried out on B-splines with basic curves for maximum accelerations to select the best cam follower motion. It also provides cam profile coordinates to manufacture a cam on computer numerical control (CNC) machines.Keywords: disc-cams; cam profile, B-spline; computer numerical control (CNC); computer-aided design and computer-aided manufacturing (CAD/CAM); R-D-R-D (rise-dwell-return-dwell) IntroductionA cam is mechanical member used to transform rotary motion into translating or oscillating motion to its follower by direct contact (Roth Bart 1956, Jensen 1965. Cam may be a plate cam or a disc cam which is cut out of a piece of flat metal, drum cam in which a groove is cut on the surface of cylinder, globoidal cam and circular cam. Applications of these cams are found in packaging machines, wire-forming machines, internal combustion engines, mechanical and electronic computers. Requirements for high performance of such machinery demands efficient methods for the design and manufacture of cams.In a cam-follower mechanism, the load produced by inertia forces induces deflections and creates vibrations. These affect the operating life of the cam. So the design of motion curves to minimise dynamic loading is of importance for high-speed cam mechanisms. It is well known that the velocity and acceleration curves are required to be continuous and to have the peak values as small as possible (i.e. minimum jerk). The purpose of this paper is to develop a CAD/CAM system for cam-follower mechanisms and to design follower velocity curve using B-splines in view of improving motion characteristics.

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Section: Literature Reviewmentioning

confidence: 99%

Optimisation of cam-follower motion using B-splines

Sateesh¹,

Rao

Reddy

2009

International Journal of Computer Integrated Manufacturing

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“…Dhande et al (11) as well as Chakraborty and Dhande (1) proposed a systematic procedure to generate the profile surfaces of planar and spatial camfollower systems. It used the theory of screws to find the condition of contact between the cam and the follower surfaces.…”

Section: Co6396 Q Imecbe 1996mentioning

confidence: 99%

Profile Determination of Planar and Spatial Cams with Cylindrical Roller-Followers

Tsay

Lin

1996

Proceedings of the Institution of Mechanical Engineers, Part C:

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A simple and useful procedure that can be used to determine profile surfaces of planar and spatial cams with cylindrical roller-followers is presented. Based on the rigid-body transformation between the cam and the roller-follower, the pitch (curve) surface which is the path of the point of the roller centre can be easily generated. Then the analytical profile surface of the cam can be represented by the offset surface of the pitch surface with a distance equal to the radius of the roller. T o illustrate the ease and effectiveness of the approach, analytical expressions of profile surfaces of a disc cam, two cylindrical cams and two globoidal cams are typically given. Furthermore, in order to show the validity of this method, the results are then compared to those derived by an earlier procedure based on the screw theory.

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“…Erdman [7] gave reviews of many studies on the cam mechanisms. The four applied approaches to the derivation of cam surfaces are based on the offset surface method [8][9][10], the screw theory [11][12][13], the envelope theory [14][15][16] and the conjugate theory [17][18][19][20][21]. Among them, the method based on the conjugate theory and the offset surface method are mainly applied.…”

Section: Introductionmentioning

confidence: 99%