Widgets Perfected Inc.

100 Institute Rd.
Worcester, Massachusetts
Memorandum

To: Young Swans’ Design Groups
From: Chief Swan
Subject: In and Out (ME 3310 Project 3 Term D-96)
Date: Assigned 4/19/96 – Final report due on 5/2/96 @ 4 PM

    A machine manufacturing company has supplied us with a cam drawing and cam contour specifications for a pick and place mechanism that loads parts into an automated machine. A small metal part is advanced into the gripper jaws of the machine by the follower train of the cam system. The camshaft rotates at 200 rpm and the cam has 10 lobes. You are given the displacement coordinates for one of the 10 lobes of the existing cam. From this information you can determine the approximate maximum and minimum velocities, accelerations and jerks of the existing cam roller-follower. (Try a spreadsheet or TKSolver to do this). Based on your analysis of the existing cam program, redesign it to reduce the maximum acceleration and maximum velocity of the follower to the greatest degree possible, while maintaining the total lift and always obeying the fundamental law of cam design.

    As with any design problem, there is an infinity of solutions possible. You are expected to come up with the best solution you can design. To do so you will have to try out many alternate designs and iterate to your 'best' solution. You should expect to typically go through at least ten iterations before arriving at an acceptable one. Some measures of "better" designs will be: lower peak accelerations, smoother jerk, smaller physical cam size, good pressure angles and reasonable follower size. You are required to compute the s, v, a, j functions, the pressure angles and radii of curvature of the entire cam(s) and draw the cam profile. All of these tasks can be accomplished with program Dynacam.

    You are also required to document your solution in a professional engineering report which adheres to the Project Report Specifications document previously distributed. This report will document the process by which you iterated to your final design as well as the design itself. Do not just describe the final result. Rather show me how you arrived at it, including the failures encountered along the way. This will demonstrate to me that you understand the engineering concepts and the relevant course material. Note that unreferenced and undiscussed computer or other illustrations will be considered to be report "filler" and be ignored. Do not put anything in the report unless you discuss its meaning. NO model of your design is required. But, please do include a computer disk with your DYNACAM solution files on it.

    For this project, no specific background research is required beyond reading your textbook and asking questions of our resident manufacturing and cam design experts. See Chapters 9 and 17 and section 2-15. You may begin your report with the goal statement and task specifications followed by the design description phase of the design process. You may also include background research information if you wish, as an option. The report must include the following figures for each cam IN THE ORDER LISTED!

    -    S-V-A-J diagrams in one plot

    -    separate S, V, A, J plots (in 4 figures)

    -    pressure angle plot

    -    radius of curvature plot

    -    the (3) boundary condition tables for any different segment of the cam

    -    the cam profile

    -    any other data you think necessary

      IMPORTANT! IMPORTANT!

IT IS CRUCIAL THAT YOU START THIS PROJECT RIGHT AWAY! Do not kid yourself that you can knock this off over the weekend before it is due! You cannot! This type of problem requires incubation periods. Work on it until stumped, then put it aside and do other coursework. Then come back to this problem after your subconscious has had a chance to work on it. You'll be surprised how effective this 'time-sharing' of your tasks can be. Read The Design Process in Chapter 1 for more information on this phenomenon. Incubation really does work. You should plan to have all the design work done at least 2 days before the due date, and use that time to write it up. It will take about three times longer to write up the report than you think it will. Allow at least two days for the write-up.

    The report must be word processed and spell checked! WordPerfect and WORD (with built-in spell checkers) are available on the Novell Network. If you have your own PC and word processor, that's fine too. Letter quality output is NOT required, but DARK type is. Use a good printer ribbon, or better yet, take your disk to CCC and laser print the final draft.

Regarding cooperation between students: This is a very gray area. I do not object to your discussing the problem with your classmates or others. Much learning can take place by 'bouncing' ideas off other technically competent people (ESPECIALLY including your instructors). So you should not work on these projects in a vacuum. BUT, and this is a very large BUT, the final result must be your own. Any duplication of results or designs in the final reports will be quite obvious and will result in a very tense confrontation between you and me. So, brainstorm ideas among yourselves if that helps, but make sure that the final result is your own and that you fully explain its intricacies in your report. This is NOT a group project.

    Now please re-read this document to ensure you understand what is being requested. If you are the least bit confused, ASK QUESTIONS IN CLASS OR SECTION MEETING or come to my office, knock on the door, and wake me up to ask for help. I promise I won’t bite! Above all, Have Fun!