At present, cam-actuated wheel brakes are used in the air brake systems of all domestic cars and some foreign cars. The surface contour of the brake cam is a center-symmetrical two-section eccentric circle with an involute contour. The size of the profile error of the brake camshaft will directly affect the quality and safety of the vehicle, so the detection of the profile of the brake camshaft has become an indispensable link.
The brake camshaft is an angle-related component, which is mostly detected on the optical indexing head with an Abbe head. The conventional detection method of the brake camshaft needs to use the probe to find the turning point to determine the lowest point of the camshaft. Then turn the corresponding angle to ensure that the measurement starts from the starting point of the involute, but the arc surface at the lowest point of the camshaft is relatively flat, resulting in insensitive response when finding the turning point, so the measurement error is relatively large.
Now introduce a method to measure from any point and directly measure the length of the involute, because the straight probe of the Abbe head can only measure the length of the radial line from the center of the cam to the contour surface, and cannot measure the length from the base circle to the contour surface The extended length of the involute, so a probe base needs to be redesigned to meet the measurement requirements.
