When we export cam-coordinates to SolidWorks, the coordinates of the cam in SolidWorks becomes the XYZ table of a Curve feature.
After the transfer is finished, we must use the Convert Entities sketch tool to convert the Curve feature to a Spline sketch-element. We extrude, or cut, the Spline to become the cam surface.
A 'standard rotating-cam' is a closed shape. The contact-point between the cam and the cam-follower steadily moves around the cam as the MMA increases from 0 to 360.
It is easy to export and extrude these cams to SolidWorks as the Cam's XY Points do not self-intersect or interfere with a different point.
However, with a 'Slot-Cam*', the contact-point may not move along the cam steadily. SolidWorks will not be able to create the Curve feature
This topic describes how to solve this problem.
* Any cam in which the contact-point does not move steadily along the cam.
There are two possible complications:
If the cam-follower changes its direction, the contact-point of 'Cam 1', as calculated by MechDesigner, moves from one cam-flank to the other cam-flank
*'Dithers' : small directional changes
If the cam-follower becomes stationary relative to the cam - usually at each end of the Slot-Cam - the contact-point also becomes stationary. While the contact-point is stationary, the cam-coordinates continue to be calculated as the MMA increases.
When the cam-coordinates have complications as described in A or B, or A and B, SOLIDWORKS cannot create the Curve feature.
Example Calculations with Slot Cams
Example of a cam with the two complications.
Refer to the image to the left:
Sliding-part moves horizontally. A 'connecting-rod' joins the sliding-part to a point that has a complex 'looping' motion' as identified by the Trace-Point.
Thus, the sliding-part moves to the right and left, then right again but with a complex motion, rather than move with a simple motion that is to the right and then to the left.
Each time the sliding-part changes its direction, the contact-point moves from one cam-flank to the other cam-flank.
A line is drawn between the cam-flanks each time the contact moves across.
SolidWorks will NOT be able to create a Curve Feature with this Cam.
Before we export the cam to SolidWorks, we must remove the two 'complications'.
There are two ways:
Linearise is the best option.
Linearise the Independent Input to the Cam.
The full range of the sliding-part in the real model is : Real Sliding Range = Maximum – Minimum
Use a Measurement FB to measure the Sliding-Part Range, and connect to a Graph FB, and take a note of the Minimum and Maximum values.
Important: The input to the Dummy Slider should increase at a constant rate with a range equal to Sliding-Part-Range in the 'Real Model'
To do this: connect a Linear-Motion FB to the input of a Gearing FB . The output from the Gearing FB is connected to the input of the Motion-Dimension FB to the Dummy Slider.
Edit the Gearing FB to set the Gearing Ratio parameter = Real Sliding Range / 360.
The output from the Gearing FB will increase steadily from 0 to Real Sliding Range (mm) in one machine cycle.
If, with the original model, the Maximum Measurement is 340mm, and the Minimum Measurement is 20mm, then the Range is 340-20 = 320mm.
Thus the Gearing Ratio = 320/360 = 0.88889. Enter this, as an equation - that is, enter 320/360 in the Gearing Ratio parameter box of the Gearing FB dialog-box.
Connect wires from the output-connector of the Linear-Motion FB to the Gearing FB to the input-connectors of the Motion-Dimension FB.
Now the Slider will move with Constant-velocity from 0 to 320mm
Now, the Cam-Coordinates will not change flanks.
When you export the cam, SolidWorks can create the Curve entity and the Cam feature.
Note: You may need to delete the last point in the saved cam-coordinate data or from the Curve feature in SolidWorks.