JPH0627297Y2 - Brochure for processing internal gears - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a broach for machining an internal gear, which is mainly used for finishing an internal gear.

(Prior Art) Broaches are often used to process internal gears. Such a broach has a so-called "alternate round blade" in which a spline cutting blade (1) for cutting a flank surface and a round blade (2) for cutting a small diameter portion are alternately arranged as shown in FIG. By simultaneously cutting the flank surface of the internal gear with the spline cutting edge (1) and the small diameter part (3) with the round blade (2) in one cutting process, the pitch circle and the small diameter of the internal gear can be reduced. He had the concentricity of part (3).

(Problems to be solved by the invention) In the above-mentioned conventional type broach, as described above, at least two spline cutting blades (1) mesh with the work material (W) in FIG. 6 for cutting engagement. In the case of (P ₁ + P ₂ = P), the above effect cannot be obtained unless the round blade (2) is in a cutting state. In other words, the length (l) of the work material (W)
However, there is a problem in that it cannot be applied to products shorter than (P). Further, since the outer periphery is machined on the basis of the internal gear, the machining process is complicated and the cycle time is long.

(Means for Solving Problems) This invention is an internal gear machining with a spline cutting edge that cuts the flank surface of the spline from the bite side to the finishing side and a bottom cutting edge that cuts a small diameter part. Brooch for
By forming a bottom cutting edge on the bottom of the spline cutting edge, the above problems are solved.

(Operation) As shown in FIG. 4, cutting is performed by forming the cutting edges (7) and (8) on both flanks (AL) and (AR) sides of the spline cutting edge (6). Bottom cutting edge formed on the spline cutting edge (6) at the same time
For (9), cut the small diameter part (3). Therefore, highly accurate concentricity of the gear pitch circle and the small diameter portion (3) can be obtained. Chips are easily discharged from three directions to form U-shaped chips (10),
As shown in FIG. 5, if a small-diameter chamfer (C) is applied in advance to the cutting edge located on the biting side (4), the chips will be divided into curls and the chips will be discharged smoothly. .

(Embodiment) An embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the broach body (T) has a biting side (4) on the left side and a finishing side (5) on the right side in the figure, and in the meanwhile, a large number of tooth thicknesses gradually increase toward the finishing side. Involute spline cutting blades (6 _{1 to} 6 _n ) (hereinafter referred to as spline cutting blades) are formed to configure a cutting blade group. Further, each cutting edge (6 _{1 to} 6 _n ) has a plurality of spline cutting edges (6 a, 6 b, 6 c ...) In the circumferential direction, as is clear from FIG. 2.
For example, the internal gear of an automobile transmission is cut.

As shown in FIGS. 3 and 4, each spline cutting edge (6) has a tooth thickness (H) that becomes larger (Ha <Hb) in the cutting direction indicated by an arrow (F). Cutting edges (7), (8) are formed on both flanks (AL), (AR) of the spline cutting edge (6), and a bottom cutting edge (9) is formed on the bottom of the blade following the cutting edge. It Further, the diameter (DR) of the bottom cutting edge (9) is also gradually increased in the cutting direction. That is, DR _a <DR _b in the drawing. Incidentally, (P) is the pitch, and (α) is the clearance angle of the bottom cutting edge (9).

Further, on the biting side (4), a plurality of cutting blades having small-diameter chamfers (C) and (C) are formed on the cutting edge formed on the bottom cutting blade (9). By carrying out such a small-diameter chamfer, the discharged chips are easily separated and curled, and the discharge becomes good.

(Effect) According to the broach for machining an internal gear according to the present invention, the flank surface and the small diameter portion of the internal gear are cut at the same time as described above, so that the concentricity of the pitch circle and the small diameter portion is φ0. .
It became 01 to φ0.03. In the conventional brooch with alternating round blades, the concentricity was about φ0.03 to φ0.06, so the concentricity was 1/2 or less, and the accuracy could be significantly improved.

For this reason, the one that has been conventionally machined on the outside of the internal gear can be used as the standard of the small diameter portion, so that the machining process can be simplified and the cycle time can be improved.

Further, since the pitch (P) of the cutting edges is 1/2 compared to the pitch (P) of the spline cutting edges of the conventional alternating circular cutting edge type broach, it is a workpiece with a short cutting length. It can also be applied to and the range of application has dramatically improved.

[Brief description of drawings]

FIG. 1 is a partially cutaway side view of an embodiment of the present invention, FIG. 2 is a sectional view taken along line II-II of FIG. 1, FIG. 3 is a partially enlarged sectional view of an essential part of the present invention, and FIG. FIG. 5 is an explanatory view showing a cutting state of a small diameter chamfer, and FIG. 6 is a partial sectional view showing a cutting state of a conventional product. 1 …… Spline cutting edge (conventional product) 2 …… Round blade (conventional product) 3 …… Small diameter part 4 …… Budded part 5 …… Finishing side 6 …… Spline cutting edge 9 …… Bottom cutting edge AL …… Frank surface AR ... Frank surface

Claims (1)

[Scope of utility model registration request] 1. A broach for internal gear machining, comprising a spline cutting edge for cutting a flank surface of a spline from a biting side to a finishing side and a bottom cutting edge for cutting a small diameter portion, the blade of the spline cutting edge being provided. A broach for machining an internal gear, which has a bottom cutting edge formed on the bottom.