Polynomial and Fourier Series Cam Curves. Chapter 5. Cam Motion Synthesis Using Spline Functions. Chapter 6. Elements of Cam Profile Geometry. Displacement, Velocity and. Acceleration Diagrams when the Follower Moves with Cycloidal Motion. Construction of Cam. Profiles. Cams with Specified. Cam: specially shaped part designed to move a follower in a controlled fashion Design double dwell cam profiles using a variety of motion types. Cam Motion.
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ME CAM Handout. Background Information: A cam is a component on which a particular profile has been machined. The profile of the cam imparts (causes). PDF | The design solutions for breadth cam mechanism were presented. The main topics of the shape design for breadth cam was to calculate the coordinate at. This paper proposes a novel method to design high-speed cam profiles for vibration reduction by using command smoothing technique. Using.
Solved problems based on CAM Profiles | Kinematics of Machines Tutorials
In general the motion of the follower is only determined positively by the cam during a part of each stroke whilst during the remainder of the stroke contact between the cam and the follower has to be maintained by an external force, often supplied by a spring. In this connection it should be noticed that the cam does not, as would at first appear likely, determine the motion of the follower during the whole of the its out-stroke.
Actually, owing to the inertia of the follower, it is only during the first part of the out-stroke and the latter part of the return that the motion of the follower is positively controlled by the cam. Cams are classified according to the direction of displacement of the follower with respect to the axis or oscillation of the cam.
The two most important types are : Disc or Radial Cams In these the working surface of the cam is shaped that the reciprocation or oscillation of the follower is in a plane at right angles to the axis of the cam. Followers can be divided according to the shape of that part which is in contact with the cam.. The following diagram shows some of the more common types: Knife edged.
These are not often used due to the rapid rate of wear of the knife edge. This design produces a considerable side thrust between the follower and the guide. Roller Follower. The roller follower has the advantage that the sliding motion between cam and follower is largely replaced by a rolling motion. Note that sliding is not entirely eliminated since the inertia of the roller prevents it from responding instantaneously to the change of angular velocity required by the varying peripheral speed of the cam.
This type of follower also produces a considerable side thrust. Flat or Mushroom Follower.
These have the advantage that the only side thrust is that due to friction between the contact surfaces of cam and follower. The relative motion is one of sliding but it may be possible to reduce this by off setting the axis of the follower as shown in the diagram. This results in the the follower revolving under the influence of the cam.
Flat faced Follower. These are really an example of the mushroom follower and are used where space is limited. The most obvious example being automobile engines. Limits imposed on the shape of the cam working surface by the choice of follower type.
Analytical developments are undergoing at LARM in Cassino, mainly with the aim to conceive a procedure and a system that can be more convenient and easy operated as cam testing. The same scheme can be used for analyzing any cam profile by using as circular-arc a suitable portion of the osculating circle at the profile point under evaluation.
The equivalence of the slider-crank mechanism is valid up to the second order kinematic characteristics since the osculating circle describes second order contact with the osculated profile.
Solved problems based on CAM Profiles | Kinematics of Machines Tutorials
In particular, the coupler link is determined as the link connecting the center Ci with the point Pi of the osculated profile and the crank is the link connecting the frame joint to the ideal joint at point C i.
A slider-crank mechanism equivalent to a cam profile transmission at a profile point Pi with curvature center Ci.
Equivalent slider-crank mechanism for a three circular-arc cam in Fig. Once the equivalent slider-crank mechanism is determined, the cam behavior can be analyzed by looking at the kinematics of the slider point of the slider-crank mechanism that is related to each circular-arc portion of the cam profile.
In particular, Fig. Figure 12b shows the velocity diagram in which one can note the non-continuity of the curve at the points joining the circular- arcs. At the point B and C the change of curvature radii gives a cusps in the velocity diagram.
An experimental analysis of performances The geometric model and use of equivalent slider-crank mechanisms have suggested also a mechanical design of a low-cost easy-operation test-bed for circular-arc cams.
The fundamental idea consists in taking advantage of the fairly simple kinematics of a slider- crank mechanism and use the kinematic equivalence in order to perform experimental tests that can give a fairly understandable characterization of the cam behavior.
The test-bed has been conceived with a mechanical design having those characteristics that meet with the kinematics of equivalent slider-crank mechanisms and with a measuring equipment that does not complicate the operation of the tests. The test-bed is shown in Fig. It is composed of commercial measuring sensors and equipment, with the aim of not to complicate the test-bed design and operation.
Thus, it has been thought convenient to use LabView software National Instruments, with NI E Acquisition Card National Instruments, , in order to work with suitable virtual instruments, which manage commercial sensors.
Referring to Figs. In addition, dynamic properties can be experimentally evaluated by using a dynamic torsionmeter S2 FGP Instr.
A signal conditioner and amplifier U2 has been used in order to provide suitable power supply to S 2 and to reduce the noise in the measured signal. One tachimeter S3 Hewelett Packard, and one encoder S4 , Baumer Electric, have been installed also on the cam shaft. In particular, the encoder gives the possibility to monitor the angle of the cam shaft, whereas the tachymeter is used to monitor the angular velocity of the cam shaft.
A signal conditioner and amplifier U1 has been used in order to provide suitable power supply to S3 and S4 to reduce the noise in the measured signal.
Three different power supply sources A1 , A2 and A3 have been used in order to provide different input voltages for the sensors S1 , S3 and S4 and motor M.
S1 S3 S4 S2 Fig. A view of the built test-bed for circular-arc cams at LARM. Illustrative results are shown in Figs. The diagrams of measured accelerations are characterized by eight significant points only, as sketched in Fig. Points B1 seems to be coincident with point B because the jump is so near that is not experimentally observable. For this reason in Fig. If one compares the acceleration plot of Fig. Experimental results on the follower of the test-bed for the three circular-arc cam design when the shaft velocity is 88 rpm: a velocity plot; b acceleration plot; c torque plot.
A general scheme for acceleration diagram of Fig.
A Computer Aided Method for Cam Profile Design
The differences among the case of Figs. For the numerical simulation of Fig. But, during the experimental measurements regarding with Fig.
However, even if the experimental measurements are carried out by using a suitable wheel, the value of the actuator torque cannot be achieved as constant, although the value of the output torque can be considered approximately constant.
Experimental on the follower of the test-bed for the three circular-arc cam design results when the shaft velocity is rpm: a angular velocity plot; b acceleration plot; c torque plot. Experimental results on the follower of the test-bed for the three circular-arc cam design when the shaft velocity is rpm: a angular velocity plot; b acceleration plot; c torque plot.
The plots in Fig. Similarly, Fig.
Solved problems based on CAM Profiles
The plots are similar to those for the case of Fig. The experimental evaluation of the acceleration diagram by using the proposed test-bed and procedure can be used to verify the cam profile not only by referring to the kinematic characteristics of a cam, but mainly to identify the cam profile itself.
The diagram of the acceleration, its shape and its values are representative of the geometry of the cam profile and its manufacture quality. Conclusions At LARM in Cassino a research line is dedicated to investigate on circular-arc cam profiles with the aim to develop modern computer-oriented analysis procedures and synthesis algorithms.
An algebraic formulation has been deduced in form that can be used both for analysis and synthesis purposes, with no great computational efforts. Achieved results have obtained suitable designs for two and three circular-arc cams. The need of experimental validation has suggested the conception of a low-cost easy-operation test-bed that has been used also for a better characterization of cam behavior.
In this paper, the overview of the obtained results up today has given the possibility to enlight future extension of the design formulation and experimental test procedure not only to circular-arc profiles. It is believed by the authors that the approach for circular-arc cam profiles can be extended also to any planar profiles with the final goal of determining a fairly simple low-cost procedure for curvature identification of cam profiles.
Angeles J. BHG Bianchi A. In Italian. Carbone G. Ceccarelli M. In print Chen F.
Chen F. Chironis N. FGP Instr.
Greco G.Simple cams form the basis of rotary cam timers which are used to control some household appliances, car engine would not work without the cams and many industrial machine tools rely upon them. Dimarogonas A. However, if you rest the cam after the function that is second dwell for 0.
Precisely, I think you need cam profile.