Cam Synthesis - Rob Hampton

Cam Synthesis for Project 8-1 from Norton Design of Machinery

Problem Statement & Information

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Approach to Solution

I started out by drawing my own plot and determining the different beta’s of each cycle. I then started to analysis the rise and fall motions of the cam, in an attempt to determine which motion program to use. Based on the problem statement I need little to no velocity at B (end of cycle 2) and a low enough velocity at C (end of cycle 3) so that it won’t bend the filament. Next, I used the student addition of DYNACAM which came with our textbook to design a cam that would meet the requirements of the project. I entered all my motion information and chose the motion programs for each Beta as seen below (Figure 1).

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After several hours of trying many different types of motion programs and analyzing their Displacement (S)-Velocity (S)-Acceleration (A)-Jerk (J) graphs, as shown below (Figure 2); I narrowed my choices to two motion programs which I thought would work the best.

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Solution

The Modified Sinusoidal had the lowest peak velocity and the Modified Trapezoidal which has the lowest peak acceleration as pictured below in Table 8-3 from our textbook. I chose to use the Modified Sinusoidal for the first rise (Beta2) because it offered zero velocity at point B and I chose the Modified Trapezoidal motion program for the rest of the rise and fall actions since it offered a relatively low peek velocity and the lowest peak acceleration.

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After deciding on my motion programs, I then proceeded to size the Cam. The problem didn’t specify any specific requirements for the dimensions of the cam. I decided on using the following dimension shown below in (Figure 3): Prime Radius-15mm, Follower Radius-2mm and an Offset-2mm. I chose to use a radial cam with a translating motion and a roller follower in order to allow my cam to be as compact as possible.

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