Abstract: The shell of this helical broach (1) is formed by stacking a plurality of wafer shells (20W(1)-20W(N)) in the axial direction, and is obtained by forming on the wafer shells (20W(1)-20W(N)) finishing blades (30W(1)-30W(N)) corresponding to teeth grooves on a piece to be cut (W) and forming the finishing blades (30W(1)-30W(N)) such that the blade width gradually increases with each of the aforementioned wafer shells (20W(1)-20W(N)) from the leading end of the cutting direction toward the trailing end of the cutting direction.

Abstract: The finishing part (4) of this helical broach (1) is formed by a first shell (20) and a second shell (30) which are divided in the axial direction, and is obtained by forming a first finishing blade (50), which comprises a prescribed gear tooth helix angle (?) end a first blade groove helix angle (?1), on the aforementioned first shell (20) and forming a second finishing blade (60), which comprises the aforementioned prescribed gear tooth helix angle (?) and a second blade groove helix angle (?2) which differs from the aforementioned first blade groove helix angle (?1), on the aforementioned second shell (30).

Abstract: The finishing part (4) of this helical broach (1) is formed by a first shell (20) and a second shell (30) which are divided in the axial direction, and is obtained by forming a first finishing blade (50), which comprises a prescribed gear tooth helix angle (?) end a first blade groove helix angle (?1), on the aforementioned first shell (20) and forming a second finishing blade (60), which comprises the aforementioned prescribed gear tooth helix angle (?) and a second blade groove helix angle (?2) which differs from the aforementioned first blade groove helix angle (?1) on the aforementioned second shell (30).

Abstract: The shell of this helical broach (1) is formed by stacking a plurality of wafer shells (20W(1)-20W(N)) in the axial direction, and is obtained by forming on the wafer shells (20W(1)-20W(N)) finishing blades (30W(1)-30W(N)) corresponding to teeth grooves on a piece to be cut (W) and forming the finishing blades (30W(1)-30W(N)) such that the blade width gradually increases with each of the aforementioned wafer shells (20W(1)-20W(N)) from the leading end of the cutting direction toward the trailing end of the cutting direction.

Abstract: A helical broach 1 for roughing includes a cutting tooth part 30 in which n spline teeth 31 are arranged side by side in an axial direction. The spline teeth 31 each include cutting teeth 32 which are arranged at a predetermined helix angle. The cutting teeth 32 each have an acute angle portion and an obtuse angle portion on both sides thereof in a circumferential direction. The cutting teeth disposed on the first to n?1th spline teeth 31 (S1 to Sn?1) in the circumferential direction are each formed in such a way that its height on the acute angle portion side differs from that on the obtuse angle portion side. The cutting teeth (Sn) of the nth spline tooth (Sn) are each formed in such a way that its height stays constant in the circumferential direction.

Abstract: A helical broach 1 for roughing includes a cutting tooth part 30 in which n spline teeth 31 are arranged side by side in an axial direction. The spline teeth 31 each include cutting teeth 32 which are arranged at a predetermined helix angle. The cutting teeth 32 each have an acute angle portion and an obtuse angle portion on both sides thereof in a circumferential direction. The cutting teeth disposed on the first to n?1th spline teeth 31 (S1 to Sn?1) in the circumferential direction are each formed in such a way that its height on the acute angle portion side differs from that on the obtuse angle portion side. The cutting teeth (Sn) of the nth spline tooth (Sn) are each formed in such a way that its height stays constant in the circumferential direction.