A method for manufacturing a rack including a toothing with variable pitch includes a roughing step, in which a blank of the rack is produced, the blank including at least one extra thickness on at least one zone of the toothing compared to a desired dimensional feature of the rack. The method also includes a finishing step, in which the at least one extra thickness of the blank is removed.

A method for manufacturing a rack including a toothing with variable pitch includes a roughing step, in which a blank of the rack is produced, the blank including at least one extra thickness on at least one zone of the toothing compared to a desired dimensional feature of the rack. The method also includes a finishing step, in which the at least one extra thickness of the blank is removed.

An axial hob (14) with cutting teeth (16) which are arranged around a cylinder (19) in a helical pattern. The cutting front (18) is perpendicular to the helix. The re-grindable blade thickness is oriented in the direction of the helix lead direction. While the tool rotates, the active cutting front changes from one blade to the next which, depending on the hand of rotation, is an advanced or retracted position. However, the rotation will not give the individual blades a chip removing motion but only position the following blade in an advanced or retracted location, such as in a gear slot to be machined.

An axial hob (14) with cutting teeth (16) which are arranged around a cylinder (19) in a helical pattern. The cutting front (18) is perpendicular to the helix. The re-grindable blade thickness is oriented in the direction of the helix lead direction. While the tool rotates, the active cutting front changes from one blade to the next which, depending on the hand of rotation, is an advanced or retracted position. However, the rotation will not give the individual blades a chip removing motion but only position the following blade in an advanced or retracted location, such as in a gear slot to be machined.

This broach includes a broach body having a shaft shape and a cutting edge section in which cutting edges protrude and are arranged in a longitudinal direction on an outer circumference of the broach body. The cutting edge section includes, in the order from a front side of the broach body, an circumference cutting section in which an outer diameter of each of the cutting edges sequentially increases rearward, and a tooth thickness cutting section in which a thickness of each of the cutting edges sequentially increases from the cutting edges at a rear end of the circumference cutting section toward the rear side. At least a rear end portion of the circumference cutting section is a high-feed cutting section in which the cutting depth per cutting edge is set in a range of 0.15 mm or more and 0.30 mm or less.

This broach includes a broach body having a shaft shape and a cutting edge section in which cutting edges protrude and are arranged in a longitudinal direction on an outer circumference of the broach body. The cutting edge section includes, in the order from a front side of the broach body, an circumference cutting section in which an outer diameter of each of the cutting edges sequentially increases rearward, and a tooth thickness cutting section in which a thickness of each of the cutting edges sequentially increases from the cutting edges at a rear end of the circumference cutting section toward the rear side. At least a rear end portion of the circumference cutting section is a high-feed cutting section in which the cutting depth per cutting edge is set in a range of 0.15 mm or more and 0.30 mm or less.

This broach includes a broach body having a shaft shape and a cutting edge section in which cutting edges protrude and are arranged in a longitudinal direction on an outer circumference of the broach body. The cutting edge section includes, in the order from a front side of the broach body, an circumference cutting section in which an outer diameter of each of the cutting edges sequentially increases rearward, and a tooth thickness cutting section in which a thickness of each of the cutting edges sequentially increases from the cutting edges at a rear end of the circumference cutting section toward the rear side. At least a rear end portion of the circumference cutting section is a high-feed cutting section in which the cutting depth per cutting edge is set in a range of 0.15 mm or more and 0.30 mm or less.

This broach includes a broach body having a shaft shape and a cutting edge section in which cutting edges protrude and are arranged in a longitudinal direction on an outer circumference of the broach body. The cutting edge section includes, in the order from a front side of the broach body, an circumference cutting section in which an outer diameter of each of the cutting edges sequentially increases rearward, and a tooth thickness cutting section in which a thickness of each of the cutting edges sequentially increases from the cutting edges at a rear end of the circumference cutting section toward the rear side. At least a rear end portion of the circumference cutting section is a high-feed cutting section in which the cutting depth per cutting edge is set in a range of 0.15 mm or more and 0.30 mm or less.

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.