Cutting insert and crank shaft milling tool
A disc milling tool including cutting inserts is provided. The cutting insert includes a top face and a bottom face parallel to the top face. Four side faces and four corner faces extend between the top and bottom faces. At least one cutting edge is formed at an intersection of the top face and at least one of the corner faces and two of the side faces connected to the corner face. The top face forms a rake surface, while an upper part of the corner face and the two side faces form a relief surface connected to the cutting edge. In order to reduce the cycle time for crank shaft milling, the cutting insert has two diagonally opposed corners including an acute angle between 70° and 85°. At least one of the acute angled corners including the corner face providing a corner cutting edge.
1 . A cutting insert holder for a crank shaft milling tool, the holder comprising:
at least a partly cylindrical body having at least a peripheral surface section and two oppositely arranged radial surfaces adjoining the peripheral surface;
a plurality of cutting insert seats formed as recesses at a transition of at least one of the radial surfaces to the peripheral surface section, each of the insert seats having a bottom support surface and at least two side support surfaces extending perpendicular to the bottom support surface;
a cutting insert arranged within each of the insert seats, the cutting insert having a central through hole extending through the cutting insert; wherein the bottom support surface of the seat includes a substantially central threaded clamping hole for receiving a clamping screw extending through the central clamping through hole of the cutting insert, wherein a normal of the bottom support surface points axially and radially away from the at least part cylindrical body at a negative axial rake angle at an absolute value of at least 10° with respect to a radial plane and by a negative radial rake angle at an absolute value of at least 8° with respect to a tangential plane to the peripheral cylindrical surface at the location of the bottom of the insert seat and extending through the center of the bottom support surface.
2 . The cutting insert holder according to claim 1 , wherein the absolute value of the negative axial rake angle is larger than 15°, and the absolute value of the negative radial rake angle is more than 12°.
3 . The cutting insert holder according to claim 1 , wherein the each of the insert seats, which are formed as the recesses at opposite radial surfaces, have a mirror symmetric shape and are arranged without being relatively shifted along a circumferential direction.
4 . The cutting insert holder according to claim 1 , wherein at least one cutting edge of each cutting insert adjoining an acute angled cutting corner of the cutting inserts extends in a tangential plane, while another cutting edge adjoining the same cutting corner extends within a radial plane.