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C-4. (a) The 3D graphic shows a radial plate cam - Leaving Cert DCG - Question C-4 - 2020
Question C-4
C-4. (a) The 3D graphic shows a radial plate cam. Fig C-4(a) shows the details of a similar cam. The cam rotates in a clockwise direction and has a 20mm camshaft. ... show full transcript
Worked Solution & Example Answer:C-4. (a) The 3D graphic shows a radial plate cam - Leaving Cert DCG - Question C-4 - 2020
Step 1
Draw the cam profile and the displacement diagram
Answer
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Draw Camshaft and Circular Arcs: Start by sketching the camshaft, ensuring it is represented accurately. Then, draw the two circular arcs corresponding to the cam profile as specified, maintaining the correct proportions.
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Divide Circle into 12 Equal Parts: Mark the circumference of the cam into 12 equal segments. This can be done using a protractor to ensure accuracy at every 30° interval.
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Horizontal Divisions at 12mm: For each of the 12 divisions, draw horizontal lines extending outwards at a distance of 12mm on the displacement diagram to represent the different angles.
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Transfer Heights to Displacement Diagram: Using the data provided (0° to 90° as Rise, 90° to 180° as Dwell, and 180° to 360° as Return), translate these heights onto the displacement diagram accurately.
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Establish Height at 90° Interval: Measure and establish the height of the cam profile at every 90° interval. This will help illustrate the cam's rise, dwell, and return.
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Draw the Dwell Line: Ensure that there is a clear horizontal line at the height established for the dwell phase (between 90° and 180°). This line should be properly labeled.
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Construction of Simple Harmonic Motion (SHM): To create the SHM curve, identify the minimum and maximum heights and plot the curve accurately based on these points, representing the motion back to the initial position.
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Complete Cam Profile: Finally, ensure the cam profile is complete, smoothing out any curves appropriately based on your earlier work.
Step 2
Draw the locus of point T
Answer
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Outline the Digger: Begin by outlining the given shape of the digger including line AB. Make sure the proportions are accurate according to the diagram provided.
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Divide Wheel Rotation into 30° Intervals: Mark the wheel rotation from its initial position in 30° increments to represent its change in position accurately.
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Step Horizontal Divisions: For each 30° interval, step out corresponding divisions horizontally from the center of rotation, ensuring alignment with the outline of the digger.
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Locate Points on Locus: Using the horizontal divisions drawn, locate the respective points on the locus at each 30° interval. This includes calculating the new positions of the arm and bucket.
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Draw the Required Locus: Finally, connect the located points to illustrate the path followed by point P accurately throughout the digger's movement.