Retaining member and cutting tool

A retaining member for fixing a cutting insert to a holder, the retaining member comprising:

• a first main body portion in which a coolant inflow opening is formed;
• a second main body portion in which a coolant ejection opening is formed;
• and
• a third main body portion located between the first main body portion and the second main body portion, wherein
• a first flow path is formed in the first main body portion so as to be contiguous to the coolant inflow opening and extend along a first direction,
• a second flow path is formed in the second main body portion so as to be contiguous to the coolant ejection opening and extend along a second direction inclined with respect to the first direction,
• a boundary flow path is formed in the third main body portion so as to be contiguous to each of the first flow path and the second flow path,
• the boundary flow path is constituted of a pair of boundary wall surfaces facing each other in a first cross section intersecting each of the first flow path, the boundary flow path, and the second flow path,
• an inclination of a tangent to at least one of the pair of boundary wall surfaces is continuously changed,
• in a second cross section perpendicular to a direction in which coolant flows, a lateral width of the first flow path is larger than a longitudinal width of the first flow path and a lateral width of the second flow path is larger than a longitudinal width of the second flow path when a longitudinal direction represents a direction in which the pair of boundary wall surfaces face each other and a lateral direction represents a direction perpendicular to the longitudinal direction, and
• in a third cross section parallel to each of the first direction and the lateral direction, the narrowed portion is constituted of a first side surface and a second side surface facing each other, such that either
• the first side surface is in a form of a straight line and the second side surface is in a form of a curve, or
• each of the first side surface and the second side surface is in a form of a straight line, and each of the first side surface and the second side surface is inclined with respect to the first direction.

A retaining member for fixing a cutting insert to a holder, the retaining member comprising:

• a first main body portion in which a coolant inflow opening is formed;
• a second main body portion in which a coolant ejection opening is formed;
• and
• a third main body portion located between the first main body portion and the second main body portion, wherein
• a first flow path is formed in the first main body portion so as to be contiguous to the coolant inflow opening and extend along a first direction,
• a second flow path is formed in the second main body portion so as to be contiguous to the coolant ejection opening and extend along a second direction inclined with respect to the first direction,
• a boundary flow path is formed in the third main body portion so as to be contiguous to each of the first flow path and the second flow path,
• the boundary flow path is constituted of a pair of boundary wall surfaces facing each other in a first cross section intersecting each of the first flow path, the boundary flow path, and the second flow path,
• an inclination of a tangent to at least one of the pair of boundary wall surfaces is continuously changed,
• in a second cross section perpendicular to a direction in which coolant flows, a lateral width of the first flow path is larger than a longitudinal width of the first flow path and a lateral width of the second flow path is larger than a longitudinal width of the second flow path when a longitudinal direction represents a direction in which the pair of boundary wall surfaces face each other and a lateral direction represents a direction perpendicular to the longitudinal direction,
• in the first cross section, the second flow path is constituted of a third side surface and a fourth side surface facing each other,
• the third side surface has a first wall surface separated by more than or equal to 1 mm from the coolant ejection opening,
• the fourth side surface has a second wall surface separated by more than or equal to 1 mm from the coolant ejection opening, and
• the first wall surface is parallel to the second wall surface.