A manufacturing company has supplied us with a timing diagram and critical-extreme-position specifications for a two-station pick and place mechanism to load parts into an automatic assembly machine. The attached figures show the desired arrangement. The nests are carried on a constant velocity conveyor. A tracking platform that rides on linear bearings (see Figure 2-21) and which is driven by a cam, follows the conveyor and matches its motion for a part of the cycle.

    Two product parts, labeled A and B, are to be inserted sequentially into each nest as it passes by. The cam-follower mechanisms to insert these parts are carried on the tracking platform and push their part into the nest at the proper time in the cycle. Part A must be inserted before part B as shown in the attached timing diagram. Part A requires a 1.5 inch insertion stroke and part B a 1 inch insertion stroke. The goal is to manufacture 150 parts per minute.

    The station distance from nest to nest on the conveyor is 4 inches. The conveyor sprockets are 10.186 inch pitch diameter and the conveyor belt is 10 feet long center to center. Power for the tracking platform drive is to be taken from the conveyor sprockets. You must specify the necessary gear ratio to drive your tracking platform cam from the conveyor. The A, B insertion cams will require an additional motor, the speed of which you must specify. The manufacturer has cam blanks available in both 8 inch and 10 inch diameter and prefers to use 1.25 inch diameter roller followers.

    There are three sub-tasks within this project:

1 Design a cam-driven mechanism to move the tracking platform at the conveyor velocity and return.

2 Design a cam-driven mechanism to insert part A.

3 Design a cam-driven mechanism to insert part B.

    These tasks are interrelated and interdependent. An overall design is needed to integrate the three sub tasks. The timing of each event should be as defined in the attached timing chart but there may be trade-offs in respect to the cycle time allotted for each event. Your team will have to work out those conflicts including modification of the timing chart if necessary. The team should assign its resources as appropriate to cover all aspects of the problem. Definite tasks should be assigned to each team member and these assignments must be documented in the final report. You are expected to integrate the designs of your cam-follower mechanisms such that they package in a reasonable size.

    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 may use either a flat faced or roller follower on any cam (but note manufacturer’s preference above). 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. An authorship page MUST be included that indicates what each group member contributed. This report will document the process by which you iterated to your final design as well as describing the design itself. Do not just describe the final result. Rather show us how you arrived at it, including the failures encountered along the way. This will demonstrate to us 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!

-    The timing diagram for the whole cycle showing all events.

-    S-V-A-J diagrams in one plot for each sub task

-    separate S, V, A, J plots (4 figures) for each sub task

-    pressure angle plot for each sub task

-    radius of curvature plot for each sub task

-    the boundary condition tables for each of your segments that use polynomials, for each sub task

-    a cam profile for each sub task

-    multi-view sketches of your cam-follower trains for each sub task

-    any other data you think necessary

IMPORTANT! IMPORTANT!