A broaching cutter includes a plurality of initial cutting blade stages for cutting formation portions to be tooth body portions in internal teeth, a plurality of intermediate cutting blade stages for cutting the formation portions to be the tooth body portions further deeply, and a plurality of final cutting blade stages for cutting formation portions to be clearance portions located deeper than the tooth body portions, the initial cutting blade stages, the intermediate cutting blade stages, and the final cutting blade stages being sequentially arranged from an upstream side in a cutting direction S. Each of a pair of distal end corners of each of cutting blades in the intermediate and final cutting blade stages has a chamfered shape larger than that of a curved shape of a pair of distal end corners of each of the cutting blades in the initial cutting blade stages.

A broaching cutter includes a plurality of initial cutting blade stages for cutting formation portions to be tooth body portions in internal teeth, a plurality of intermediate cutting blade stages for cutting the formation portions to be the tooth body portions further deeply, and a plurality of final cutting blade stages for cutting formation portions to be clearance portions located deeper than the tooth body portions, the initial cutting blade stages, the intermediate cutting blade stages, and the final cutting blade stages being sequentially arranged from an upstream side in a cutting direction S. Each of a pair of distal end corners of each of cutting blades in the intermediate and final cutting blade stages has a chamfered shape larger than that of a curved shape of a pair of distal end corners of each of the cutting blades in the initial cutting blade stages.

A tool for machining splines on a workpiece comprises a base, a first tooth extending radially from the base and a second tooth extending radially from the base. The second tooth is spaced circumferentially from the first tooth. The first tooth has a first height, the second tooth has a second height and the second height is less than the first height. The first tooth tapers from the base to the tip of the first tooth, the second tooth tapers from the base to the tip of the second tooth and the first tooth is identical to the second tooth to the second height.

A helical broach which eliminates the need for a fixing means for fixing a workpiece during gear machining is provided. The helical broach includes: a plurality of cutting edges; a spiral flute formed between adjacent cutting edges to extend in a spiral manner with a predetermined helix angle with respect to an axial direction of the helical broach; and a gullet formed between adjacent cutting edges to extend with a predetermined helix angle with respect to a circumferential direction of the helical broach. In the helical broach, the expression: 0.5tan /tan(+)0.7 is satisfied, wherein is the helix angle of the spiral flute, and (90) is the helix angle of the gullet with reference to a central axis of the helical broach. An internal gear machining method using the helical broach is also provided.

A helical broach which eliminates the need for a fixing means for fixing a workpiece during gear machining is provided. The helical broach includes: a plurality of cutting edges; a spiral flute formed between adjacent cutting edges to extend in a spiral manner with a predetermined helix angle with respect to an axial direction of the helical broach; and a gullet formed between adjacent cutting edges to extend with a predetermined helix angle with respect to a circumferential direction of the helical broach. In the helical broach, the expression: 0.5tan /tan(+)0.7 is satisfied, wherein is the helix angle of the spiral flute, and (90) is the helix angle of the gullet with reference to a central axis of the helical broach. An internal gear machining method using the helical broach is also provided.

A broach tool includes a broach tool rake face with a tailored surface topography.

A broach tool includes a broach tool rake face with a tailored surface topography.

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

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

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 (.sub.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 (.sub.2) which differs from the aforementioned first blade groove helix angle (.sub.1), on the aforementioned second shell (30).