JP2003181721A - Hob arbor for precision machining and gear machining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hob arbor and a gear machining method having an improved tool profile accuracy of machined gears by increasing bending rigidity of the hob arbor to prevent generation of an eccentricity on the hob due to bend of the hob arbor when the hob is attached to the hob arbor by fastening it with a hexagonal nut. <P>SOLUTION: The arbor of the hob arbor 1 is made of a high-speed tool-steel, and two keyways 2 and 3 for parallel keys in the arbor axial direction are machined on the arbor at symmetrical positions apart 180° in circumferential direction. A driving parallel key 4 is assembled in one of the keyways, the keyway 2, and a sinking parallel key 5 is assembled in the other keyway 3. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hob arbor and a gear machining method which are used by being attached to a hobbing machine in hobbing gears and the like.

[0002]

2. Description of the Related Art As a prior art of a hob arbor, as shown in a schematic sectional view of a conventional hob arbor 10 in FIG. 4, the hob arbor material used is generally a carburized and hardened material such as SCM415 or SCM420. In the case of the hole inner diameter keyed type, the groove 2 for the parallel key for drive of the hob arbor is machined only at one position in the axial direction of the arbor, and the parallel key 4 for drive is attached to the parallel key groove for drive 2. Furthermore, if the hob has an end surface keyway, that is, if the inner diameter keyway cannot be formed with a small-diameter hob with a small wall thickness, there are two (sometimes one) end surface keyway in the radial direction of the end surface of the hob boss. When attached, the key groove of the hob arbor is machined at two points on the hob arbor collar on the radial surface of the arbor shaft (not shown). Is generally attached (not shown).

[0003]

The conventional SCM 4 shown in FIG.
When the hob is attached to the hob arbor which is carburized and quenched in carburizing material such as 20 and tightened with the hexagon nut, the hob may be eccentric due to the bending of the hob arbor. The cause of bending of the hob arbor is that the carburized material has a small longitudinal elastic modulus and no rigidity. Furthermore, in the case of a hob arbor with a parallel inner diameter key, since only one key groove is machined, bending stress tends to work due to the asymmetry of the arbor cross-sectional shape, and in the case of the hob arbor for the end surface key, the unidirectional end surface It is also a factor of bending that the torsional stress originating from the key portion tends to work. Even if the hob is a high-precision product, the tooth profile of the machined gear becomes uneven due to the difference in the entrance and exit of the hob cutting edge caused by the eccentricity of the hob, and the tooth profile accuracy of the gear is significantly higher than the hob accuracy. It may decrease. Further, if the gear is continuously machined while the hob is eccentric, abnormal wear is likely to be induced due to uneven wear at each cutting edge of the hob, and the hob itself may have a short life.

The present invention solves the problems of the prior art,
In the hob arbor used for the hobbing machine, the flexural rigidity of the hob arbor is improved, and when the hob is attached to the hob arbor and tightened with a hexagon nut, the hob does not become eccentric due to the bending of the hob arbor, and the tooth profile accuracy of the machined gear is improved. It is an object of the present invention to provide a hob arbor and a gear processing method capable of further improving the above.

[0005]

Therefore, according to the present invention, in a hob arbor used in a hobbing machine, high-speed tool steel is used as the material of the arbor, and the key groove for the parallel key in the arbor axial direction is 180 ° in the circumference. Hob arbor for high-precision machining and gear machining, characterized in that drive parallel key is assembled in one of the key grooves and embedding parallel key is assembled in the other key groove The above-mentioned problems were solved by providing a law.

[0006]

With the above construction, according to the present invention, in the hob arbor used for the hobbing machine, the material of the arbor is the heat-treated material of the high speed tool steel, and the key groove for the parallel key in the arbor axial direction is 180 ° around the circumference. Machining at two symmetrical positions, by mounting the drive parallel key in one key groove and by mounting the parallel key for embedding in the other key groove, the flexural rigidity of the hob arbor is improved, and the hob is attached to the hob arbor. When tightening the hexagon nut, the bending of the hob arbor was suppressed as much as possible.

In the high precision machining hob arbor having the above structure,
By attaching a hob and using a hobbing machine to create a high-precision tooth profile, the tooth profile accuracy of the machined gear is further improved. That is, using the conventional hob arbor,
Even if the hob is a high-precision product, the tooth profile of the machined gear becomes uneven due to the difference in the hob's cutting edge coming in and out due to the eccentricity of the hob, and the tooth profile accuracy of the gear drops significantly relative to the hob accuracy. However, when the high precision machining hob arbor of the present invention is used, such a problem disappears.
Furthermore, if the gear is continuously machined with the hob eccentric,
Abnormal wear was likely to be induced due to uneven wear at each cutting edge of the hob, and the hob itself had a short life.However, when the high-precision machining hob arbor of the present invention is used, the hob arbor can be processed without such a problem. The tooth profile accuracy of the gear is improved.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A is a schematic sectional view of a high precision machining hob arbor according to an embodiment of the present invention, and FIG. 1B is a sectional view taken along line BB of FIG. 1A. Show. High-precision machining hob arbor 1 of the present invention used for hobbing machines
In order to manufacture an arbor with a high flexural rigidity, first, the material of the arbor is a heat-treated material of high-speed tool steel, which has a larger longitudinal elastic modulus and is less likely to bend than the carburized and hardened material such as SCM415 or SCM420. In order to eliminate the bending stress and disperse the bending stress, the key grooves 2 and 3 for the parallel key in the direction of the arbor axis, which has been conventionally processed only at one position, are provided at two positions symmetrical about 180 ° on the circumference, and the hob drive Since there is only one parallel key groove 2 attached to the key groove, only one parallel key 4 may be attached to the key groove. It was possible to further alleviate the asymmetry of and to further improve the flexural rigidity of the hob arbor 1.

FIG. 2 is a schematic side view of the high-precision machining hob arbor 1 shown in FIG. 1 in which the hob is attached. The hob 6 is a hob arbor so that the contact surfaces of the circular annular spacers 9 and 10 are in contact with both end surfaces of the hob. The state after being attached to No. 1 and tightened with the hexagon nut 13 is shown. The assembly in the state of FIG. 2 is attached to a hobbing machine and gear machining is performed.

[0010]

EXAMPLE Now, as shown in FIG. 2, the hob 6 is attached to a conventional hob arbor and a high-precision machining hob arbor so that the contact surfaces of the circular annular spacers 9 and 10 contact both end surfaces of the hob. Then, a comparative test was conducted on the hob eccentricity when tightened with the hexagon nut 13.
The amount of eccentricity of the hob 6 depends on the hob boss A of the assembly in the state shown in FIG.
7, the hob boss B8 was judged by the change amount of the outer peripheral shake, and the result is shown in FIG. However, the same hob and spacers 9 and 10 are used for the conventional hob arbor and the high-precision machining hob arbor, respectively. As can be seen from the graph of FIG. 3 showing the results of this comparative test, when the nut is tightened in the conventional hob arbor, the hob boss outer circumference runout changes by as much as 0.015 to 0.023 mm, but for high precision machining. Hob arbor is only 0.00
Only changes between 2 and 0.004 mm. Further, in the conventional hob arbor, a change in the runout also occurs in the arbor tip metal side taper portion 12 and the main metal side taper portion 11 as the hob boss outer circumference runout changes. From the above, it was confirmed that the high-precision machining hob arbor is more effective than the conventional hob arbor against bending of the hob arbor and can suppress the eccentricity of the hob as much as possible.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a high precision machining hob arbor according to an embodiment of the present invention.

FIG. 2 is a schematic side view showing a state in which a hob is attached to the high-precision machining hob arbor shown in FIG.

FIG. 3 shows the state of FIG. 2 with the conventional hob arbor.
Is a graph showing the results of a comparative test in which the hob eccentricity amount is measured by attaching the hob arbor for high precision machining.

FIG. 4 is a schematic sectional view of a conventional hob arbor.

[Explanation of symbols]

1 ・ ・ High precision machining hob arbor 2 ・ ・ Parallel key groove for drive 3 ・ ・ Parallel key groove for embedding 4 ・ ・ Parallel key for drive 5 ・ ・ Parallel key for embedding 6 ・ ・ Hob

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yutaka Tsukamoto             1-1 1-1 Fujikoshi Honmachi, Toyama City, Toyama Prefecture             Ceremony company Fujikoshinai (72) Inventor Kanji Ishiba             1-1 1-1 Fujikoshi Honmachi, Toyama City, Toyama Prefecture             Ceremony company Fujikoshinai (72) Inventor Michitaka Okugawa             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Kazuhiro Tsubota             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Susumu Sao             28 Kamitaba Kamoda, Minami-ku, Kyoto             Inside Shifuji F term (reference) 3C025 FF06

Claims (2)

[Claims] 1. A hob arbor used in a hobbing machine,
High-speed tool steel is used as the material for the arbor, and the keyways for the parallel keys in the arbor axis direction are machined in two locations at 180 ° symmetry around the circumference. One of the keyways has the drive parallel key. A high precision machining hob arbor that is assembled and has a parallel key embedded in the other key groove. 2. A hob arbor used in a hobbing machine,
High-speed tool steel is used as the material for the arbor, and the keyways for the parallel keys in the arbor axis direction are machined in two locations at 180 ° symmetry around the circumference. One of the keyways has the drive parallel key. A gear machining method characterized by attaching a hob to a high-precision machining hob arbor, which is assembled, and a parallel key for embedding is embedded in the other key groove, and creates a high-precision tooth profile using a hobbing machine.