PURPOSE: To obtain a coated cemented carbide chaser which is long-life and free from damage with a good finish surface by making the coat thickness on a chaser edge and its neighborhood thinner or removing the coat.
CONSTITUTION: A chaser tool, which is used in cutting comparatively large diameter and high-precision screw threads for oil well piping, etc., consists of a base 4 and a coated layer 5; (minimum thickness b of coated layer)/(average thickness a of coated layer 5)×100 is referred to as a coat thickness ratio (%). Therefore, the coat thickness on the chaser edge and its neighborhood is made thinner than that of the other area or the coat is removed. In addition, the chaser uses cemented carbide for the base 4, and the coated layer 5 is made by use of the CVD method. And the rake face and the relief face are wrapped at the same time. With this configuration, it is possible to obtain a chaser which is long-life and free from damage with a good finish surface.
ONO TATSUO
YOSHIDA TSUNEO
