Computing stresses in the wear zone of a radius end mill cutter

The paper proposes a technique for computing stress state of the radius end mill cutting edge when machining surfaces and taking into account the wear and the inclination angle. It uses as the experimental data on the wear zone and cutting force geometriic charcteristics as the initial data. The wear zone along the tool flank surface is determined from the photographs obtained using a digital microscope. Load distribution over the tool surfaces is performed using a typical graph constructed based on study results obtained in free cutting. Based on computation results for the wear zone of the tool cutting tooth flank surface with an area of 0.2 mm² and the cutting force projections F_x = 135 N, F_y = –252 N and F_z = –786 N, stress distribution in the radius milling cutter cutting edge is obtained. Maximum values of the equivalent, normal and shear stresses are 2338, –2051 and –1195 MPa, respectively. The paper shows that stresses decrease with increasing the distance from the cutting edge of the tool surface and the wear width along the back surface, the highest values are found in the rounding zone of the tool cutting edge. It demonstrates that the tool cutting edge is subjected to the all-round compression. To test the tool cutting part strength under the all-round compression, criterion of the first theory of strength is used. Dependences of maximum stresses in the tool cutting edge on the wear width along the back surface and the inclination angle are derived.
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