JP2003089015A - Chisel for fabricating internal gear and fabricating method of internal gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chisel capable of fabricating quickly and accurately an internal gear for use in a small-sized planetary gear device. SOLUTION: A metal rod is furnished with a first, a second and a third tooth-form forming part 1, 2 and 3 at a predetermined interval, and they constitute one chisel 10 furnished with cutting blades having the same tooth stripes and with their machining parts increasing gradually in compliance with the tooth form, and the inner gear is fabricated by press fitting the chisel 10 into a hollow gear blank 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chisel suitable for producing an internal gear used in a small multi-stage planetary gear device and a production method for producing an internal gear using the chisel. .

[0002]

2. Description of the Related Art An internal gear having a tooth width smaller than a pitch circle diameter and a large module is manufactured by a pressing method. In addition, for those having a large tooth width, there are a die casting method and a molding method using a resin material. Further, there is a gear cutting method using a pinion cutter.

[0003]

The internal gear produced by the above press method cannot have a large tooth width (tooth thickness). Further, the dimension from the root circle to the outer circle of the internal gear cannot be reduced, and the tooth surface is rough and the transmission efficiency is poor, so that it cannot be used in a multi-stage planetary gear device.

FIG. 4 is a cross-sectional view of an internal gear manufactured by a mold such as die casting or resin molding. Mode
The product formed by the mold requires a removal taper, which is necessary when the mold is removed.

This removal taper is represented by the ratio of Δd and L shown in FIG. 4, Δd / L, and is usually about 1/50. That is, if L is 15 mm, Δd is 0.3
mm, for example, in the case of a gear having a module of 0.3, the tooth height value is about 0.6 mm, so 1/2 of the tooth height does not mesh with the mating gear.

Further, the value of L at which 90% of the tooth height meshes is about 3.4 mm, and when the module is 0.1, it is 1.1 mm.
It becomes the tooth width of. As described above, the internal gear molded by the molding die is used by connecting a plurality of internal gears for use in a multi-stage planetary gear device.

Further, the resin-made one does not have the bearing capacity of the teeth and cannot increase the torque of the output shaft. FIG. 5 shows a pinion cutter, A is a plan view, B is a partially cutaway side view, and 71 is a cutting blade.

FIG. 6 shows a state of gear cutting of an internal gear by a pinion cutter. 81 is a pinion cutter, 8
2 is a gear blank of the gear to be cut. 83 indicates the center of the pinion cutter, and 84 indicates the center of the gear blank. The pinion cutter 81 reciprocates inside the gear blank 82 in the tooth striation direction to perform tooth cutting.

At this time, the pinion cutter 81 and the gear blank 82 are rotated at a predetermined rotation ratio with their centers 83 and 84 as rotation centers. As described above, in the gear cutting method using the pinion cutter 81, the pinion cutter 81 must be reciprocated by at least the number of teeth, which requires a long machining time.

Further, the pinion cutter 81 and the gear blank 82 must be precisely rotated at a predetermined rotation ratio. Therefore, there is a problem that a complicated machine tool is required and the machining time is long.

It is an object of the present invention to propose a chisel as a tool capable of accurately forming an internal gear having a long tooth width in a short time, and a method of manufacturing an internal gear using the chisel.

[0012]

In order to achieve the above-mentioned object, in the present invention, a plurality of diameter-expanded portions are arranged at a predetermined interval along a longitudinal direction of a metal rod body, and We propose a chisel for manufacturing an internal gear, characterized in that each of the expanded diameter portions has the same tooth profile and is provided with a cutting edge that sequentially increases the cutting portion according to the tooth profile.

Further, in the chisel described above, an inner gear made of metal is manufactured by press-fitting the chisel into a hollow portion of a hollow member made of a metal material. Suggest me.

Further, in the present invention, a plurality of expanded diameter portions are arranged along the longitudinal direction of the metal rod body at a predetermined interval, and the expanded diameter portions have the same tooth teeth. Along with the tooth profile, a cutting edge was provided that increased the cutting portion in sequence, and the chisel was pressed into the hollow part of the hollow member, and the entire circumference of the inner surface of the hollow part was We propose a method for manufacturing an internal gear, which is characterized by cutting to form a tooth profile.

[0015]

[Operation] The chisel of the above construction is inserted into the hollow portion of the hollow member,
The teeth are formed on the entire inner surface of the hollow portion by press-fitting with a predetermined pressing force. At this time, among the plurality of expanded parts, the tooth tip of the internal gear is formed by the cutting edge of the expanded part that is inserted first into the hollow part, and the cutting edge of the expanded part that is subsequently inserted. The tooth profile is formed by cutting toward the root of the tooth. Then, the tooth profile of the internal gear is completed by the cutting edge of the radially expanded portion that is finally inserted.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a chisel 10 for manufacturing an internal gear of the present invention. In this figure, 1 is a first tooth profile forming part, 2 is a second tooth profile forming part, 3 is a third tooth profile forming part, and 3rd tooth profile forming part 3 is an involute.
Tooth type, cycloid and other tooth profile types, module size,
A tooth profile is provided which satisfies the well-known specifications of the desired internal gear, such as the number of teeth and the amount of shift.

The second tooth profile forming portion 2 has the same tooth profile as the tooth profile forming portion 3, but the tooth height value is set to 2/3 of the tooth height value of the tooth profile forming portion 3.

The first tooth profile forming portion 1 has the same tooth profile as the tooth profile forming portion 3, but the tooth height value is set to 1/3 of the tooth height value of the tooth profile forming portion 3. The phases of the tooth bottom positions of the tooth profile forming section 1, the tooth profile forming section 2, and the tooth profile forming section 3 are the same.

Reference numeral 4 shown in FIG. 1 denotes a mounting shaft to a power unit (not shown) for moving the chisel 10 parallel to the central axis 8, and its shape corresponds to that of the power unit.

Reference numeral 5 is a hollow material for forming an internal gear, which is a gear blank, and 6 is a tooth profile forming surface of the gear blank 5, the diameter of which is a tip circle of the internal gear to be created (in the tooth profile forming portion 3, the tooth bottom is a tooth bottom). It becomes almost the same).

Reference numeral 7 is an introduction portion of the gear blank 5 to the tooth profile forming surface 6, and its diameter is substantially the same as the diameter of the tooth profile forming surface 6.

Reference numeral 9 denotes a small-diameter connecting portion provided between each of the introduction portion 7 and the tooth profile forming portion 1, the tooth profile forming portion 1 and the tooth profile forming portion 2, and the tooth profile forming portion 2 and the tooth profile forming portion 3.

FIG. 2 is a sectional side view of the chisel 10.
The same parts as those in FIG. 1 are denoted by the same reference numerals. 21, 2
2, 23 are the first tooth profile forming portion 1, the second tooth profile forming portion 2,
These are cutting blades provided at each end of the third tooth profile forming portion 3 for cutting a tooth profile, and these cutting blades have an acute angle, and the angle of the blade is determined by the material of the gear blank 5.

Reference numeral 24 denotes a chip reservoir surrounded by the introduction portion 7, the first tooth profile forming portion 1, the small diameter connecting portion 9, and the tooth profile forming surface 6 when the introduction portion 7 is inserted into the gear blank 5. It is a space to be formed. 25 and 26 are also spaces for forming a chip reservoir similar to the space 24.

The volume of the chip reservoir formed in these spaces 24, 25, 26 is sufficient to accommodate the chips produced by the cutting blades 21, 22, 23 when the chisel 10 is passed through the gear blank 5. There is as a size. In addition, it is preferable to change the volume of the chip reservoir according to the length L of the gear blank 5.

Further, the tooth profile forming portions 1, 2, 3 shown in FIG.
The pitch P between the two is shorter than the length L of the gear blank 5. Therefore, the second tooth profile forming section 2 cuts the same phase position as the first tooth profile along the striations of the first tooth profile part formed by cutting by the first tooth profile forming section 1
The tooth profile portion of is formed. Similarly, the third tooth profile forming portion 3
In the same manner as above, the cutting is performed at the same phase as the second tooth profile portion.

FIG. 3 is a partial sectional view of the chisel 10.
(A) is a first tooth profile forming part 1, (b) is a second tooth profile forming part 2, and (c) is a partial sectional view showing a cutting edge part of a third tooth profile forming part 3. Reference numeral 31 shown in FIG. 3 denotes a portion corresponding to the completed tooth profile of the internal gear, and 32 denotes the tooth profile of the third tooth profile forming portion 3.

Then, assuming that the height of this tooth profile is h, FIG.
The tooth profile height hb in the second tooth profile forming portion 2 shown in (b) is 2h / 3, and the tooth profile height ha in the first tooth profile forming portion 1 shown in FIG. 3 (a) is h / 3. There is.

The height hb of the tooth profile described above is determined by the tooth profile 3
2 for the cross-sectional area S between the root circle and the tip of the tooth.
The cross-sectional area S of the same portion of the second tooth profile forming portion 2 shown in (b)
b is 2S / 3, and the tooth profile height ha
Is the cross-sectional area S of the tooth profile 32 from the root circle.
Area Sa of the same portion of the first tooth profile forming portion 1 shown in (a)
Can be determined so that it becomes S / 3.

When the heights ha, hb, h of the tooth profile are assigned by the above-mentioned cross sections Sa, Sb, S, the cutting edges 21, 22,
The amount of chips generated by 23 can be made uniform,
Moreover, the stresses applied to the cutting edges 21, 22, and 23 during cutting can be made substantially the same.

The internal gear is manufactured by penetrating the chisel having the above-mentioned structure through the gear blank. In the above description, the case where the number of the tooth profile forming portions of the chisel is set to three has been described, but the number is not limited to three and may be any number as necessary.

Since the completed tooth profile is determined by the insertion of the third tooth profile forming section 3, the first and second tooth profile forming sections 1, 2 are formed.
3A is not limited to the cutting edge shape shown in FIGS. 3A, 3B, and 3C, and a cutting edge shape that can be sequentially cut according to the tooth profile can be used.

[0033]

As described above, the chisel according to the present invention is
The internal gear applicable to the multi-stage planetary gear device can be accurately produced in a short time. Further, since an internal gear having a long tooth width can be produced, a multi-stage planetary gear device can be easily assembled and the cost can be reduced.

Further, it is also suitable for producing a small-diameter internal gear, and an internal gear having a module of 0.1 or less and a pitch circle diameter of 5 mm or less can be produced, and the planetary gear device can be miniaturized.

Further, since the internal gear can be made of metal, the teeth have a high yield strength and a large output torque can be obtained when the planetary gear device is used as a speed reducer. In addition,
The internal gear prepared as described above can be used not only for the planetary gear device but also for various gear devices such as a harmonic drive speed reducer.

[Brief description of drawings]

FIG. 1 is a perspective view of a chisel and a gear blank for manufacturing an internal gear according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the axial direction of the chisel.

FIG. 3 is a partial cross-sectional view of the chisel shown in FIG.
3 (b) is a partial sectional view of the second tooth profile forming portion, and FIG. 3 (c) is a partial sectional view of the third tooth profile forming portion.

FIG. 4 is a cross-sectional view of a conventional resin-molded internal gear.

5 (a) and 5 (b) are a plan view and a partially cutaway side view of a pinion cutter which is a conventional gear cutting tool.

FIG. 6 is an explanatory diagram of gear cutting by a pinion cutter.

[Explanation of symbols]

1 First tooth profile forming part 2 Second tooth profile forming part 3 Third tooth profile forming part 4 mounting shaft 5 gear blank 6 Tooth profile forming surface 7 Introduction 8 central axis 9 Thin connection 10 Tagger 21, 22, 23 cutting edge 24, 25, 26 space 31 Part corresponding to completed tooth profile 32 tooth profile

Claims (3)

[Claims] 1. A plurality of enlarged diameter portions are arranged along a longitudinal direction of a metal rod body at predetermined intervals, and the enlarged diameter portions have the same teeth, and A chisel for manufacturing internal gears, which is characterized by being provided with cutting edges that sequentially increase the cutting portion according to the tooth profile. 2. The internal gear manufacturing according to claim 1, wherein the internal gear made of metal is manufactured by press-fitting the chisel into the hollow portion of a hollow member made of a metal material. Use it. 3. A plurality of diameter-expanded portions are arranged along the longitudinal direction of the metal rod body at predetermined intervals, and the diameter-enlarged portions have the same teeth, and According to the tooth profile, a chisel was constructed with cutting edges that gradually increase the number of cutting parts, and this chisel was press-fitted into the hollow part of the hollow member, and the entire circumference of the inner surface of the hollow part was cut at one time to form a tooth profile. A method of manufacturing an internal gear, which comprises forming.