Double-sided cutting insert and helical milling cutter

A double-sided cutting insert arranged for use in a helical milling cutter, the cutting insert being turnable into four different working positions the cutting insert comprising:

• first and second major faces arranged on opposite sides of the cutting insert and serving as top and bottom faces of the cutting insert, the cutting insert having a centre axis that extends between the first and second major faces and a median plan that extends halfway between the first and second major faces perpendicularly to the centre axis wherein the cutting insert has an essentially rectangular basic shape when seen in a direction along the centre axis and wherein each one of said first and second major faces includes an abutment surface that is configured to serve as a tangential abutment surface of the cutting insert in two of said working positions of the cutting insert and abut against a corresponding tangential support surface in an insert seat in a tool body of a helical milling cutter when the cutting insert is mounted in the insert seat in any of these two working positions;
• a peripheral surface extending around the cutting insert between the first and second major faces and comprising:
• a first main side face and a second main side face arranged opposite to each other on two opposite long sides of the cutting insert,
• a third main side face and a fourth main side face arranged opposite to each other on two opposite short sides of the cutting insert,
• a first corner side face arranged between the first and fourth main side faces,
• a second corner side face arranged between the first and third main side faces,
• a third corner side face arranged between the second and third main side faces ,and
• a fourth corner side face arranged between the second and fourth main side faces;
• a curved first corner cutting edge formed at an intersection between the first corner side face and the first major face;
• a curved second corner cutting edge formed at an intersection between the second corner side face and the first major face;
• a curved third corner cutting edge formed at an intersection between the third corner side face and the first major face;
• a curved fourth corner cutting edge formed at an intersection between the fourth corner side face and the first major face;
• a curved fifth corner cutting edge formed at an intersection between the second corner side face and the second major face;
• a curved sixth corner cutting edge formed at an intersection between the first corner side face and the second major face;
• a curved seventh corner cutting edge formed at an intersection between the fourth corner side face and the second major face;
• a curved eighth corner cutting edge formed at an intersection between the third corner side face and the second major face;
• a first main cutting edge formed at an intersection between the first major face and the first main side face, the first main cutting edge extending between the first and second corner cutting edges;
• a second main cutting edge formed at an intersection between the first major face and the second main side face, the second main cutting edge extending between the third and fourth corner cutting edges;
• a third main cutting edge formed at an intersection between the second major face and the first main side face, the third main cutting edge extending between the fifth and sixth corner cutting edges;
• and
• a fourth main cutting edge formed at an intersection between the second major face and the second main side face, the fourth main cutting edge extending between the seventh and eighth corner cutting edges;
• an inclined first chip guiding surface extending between the first major face and the third main side face and located between the second corner side face and the third corner side face, the first chip guiding surface having a first edge that forms a boundary between the first chip guiding surface and the first major face and a second edge that forms a boundary between the first chip guiding surface and the third main side face, wherein the first chip guiding surface is bounded by these first and second edges and the first edge meets the second edge at a first end of the first chip guiding surface facing the second corner cutting edge and also at a second end of the first chip guiding surface facing the third corner cutting edge ;
• an inclined second chip guiding surface extending between the first major face and the fourth main side face and located between the first corner side face and the fourth corner side face, the second chip guiding surface having a first edge that forms a boundary between the second chip guiding surface and the first major face and a second edge that forms a boundary between the second chip guiding surface and the fourth main side face, wherein the second chip guiding surface is bounded by these first and second edges and the first edge meets the second edge at a first end of the second chip guiding surface facing the fourth corner cutting edge and also at a second end of the second chip guiding surface facing the first corner cutting edge;
• an inclined third chip guiding surface extending between the second major face and the fourth main side face and located between the first corner side face and the fourth corner side face the third chip guiding surface having a first edge that forms a boundary between the third chip guiding surface and the second major face and a second edge that forms a boundary between the third chip guiding surface and the fourth main side face, wherein the third chip guiding surface is bounded by these first and second edges and the first edge meets the second edge at a first end of the third chip guiding surface facing the sixth corner cutting edge and also at a second end of the third chip guiding surface facing the seventh corner cutting edge;
• and
• an inclined fourth chip guiding surface extending between the second major face and the third main side face and located between the second corner side face and the third corner side face, the fourth chip guiding surface having a first edge that forms a boundary between the fourth chip guiding surface and the second major face and a second edge that forms a boundary between the fourth chip guiding surface and the third main side face, wherein the fourth chip guiding surface is bounded by these first and second edges and the first edge meets the second edge at a first end of the fourth chip guiding surface facing the eighth corner cutting edge and also at a second end of the fourth chip guiding surface facing the fifth corner cutting edge that,
• wherein each one of the first and second chip guiding surfaces intersects said abutment surface of the first major face on both sides of a longitudinal plane of the cutting insert that extends halfway between the first and second main side faces perpendicularly to the median plane and that contains the centre axis that,
• wherein each one of the third and fourth chip guiding surfaces intersects said abutment surface of the second major face on both sides of said longitudinal plane,
• wherein the cutting insert has a transverse plane that extends halfway between the third and fourth main side faces perpendicularly to the median plane and perpendicularly to the longitudinal plane and that contains the centre axis, wherein each chip guiding surface of said first, second, third and fourth chip guiding surfaces has such an inclination in relation to the transverse plane that the first edge of the chip guiding surface is located closer to the transverse plane than the second edge of the same chip guiding surface as seen in the longitudinal plane and as seen in any plane that extends across the chip guiding surface and is parallel to the longitudinal plane.