JP2007113675A - Worm gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a worm gear of which the manufacturing cost is suppressed and having high power transmission capacity with a long service life. <P>SOLUTION: The worm gear is composed of a first gear and a second gear having an axis orthogonal to an axis of the first gear and meshed with the first gear, wherein a wheel 4 which is the second gear, is constituted by machining, with a hob, a high hardness material 2 formed by making a blank highly hard. The worm gear having the wheel of high accuracy having high power transmission capacity with a long service life can thereby be obtained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a worm gear used for a speed reducer or a speed increaser.

  The worm gear includes a worm that is a first gear and a wheel that is a second gear that meshes with the first gear on a rotation axis orthogonal to the rotation axis of the first gear. For the tooth processing of the wheel, a hob having the same tooth profile shape and pitch circle diameter as the worm tooth profile shape and pitch circle diameter is used, and the wheel and hob are arranged so that the axial direction of the wheel and the axial direction of the hob are perpendicular to each other. The ratio of the rotation speed of the hob to the rotation speed of the wheel is the same as the ratio of the number of teeth of the worm to the number of teeth of the wheel, and the hob is engaged with the worm and the wheel while creating the wheel teeth in the axial direction of the wheel. Push to the same position as the position. The wheel thus machined meshes smoothly with the worm.

  For example, as described in Patent Document 1, since the wheel is chopped with a hob, the material of the wheel is easily processed, and the material having high strength and wear resistance includes phosphor bronze, Lead bronze or the like is used, or phosphor bronze teeth are provided around the boss made of cast iron to reduce the cost.

  In consideration of workability and wear resistance, generally, steel that has not been hardened is used, and the steel material is first cut with a hob to increase the hardness of the tooth surface of the wheel. A method of coating a tooth surface with a high hardness material after carburizing or induction hardening, or cutting a tooth with a hob is conceivable.

JP-A-10-34312 (Page 2-3, FIG. 18)

  In the conventional technology, as described above, the material of the wheel uses a material that is easy to process, such as phosphor bronze, in order to create a gear with a hob. Since it is a material that is easy to process, it cannot be said that its strength is sufficient, and there is a problem that the power transmission capability is low.

  In addition, after quenching the tooth with a hob, if it is quenched, it deforms due to quenching distortion, the accuracy of the tooth surface of the wheel deteriorates, and consequently it is difficult to increase power transmission There is.

  In addition, since the wheel has a complicated three-dimensional tooth surface shape, there is a problem that a polishing technique for removing quenching distortion has not been established.

  Further, in the method of coating a high hardness material onto the tooth surface of the wheel, accuracy and hardness can be ensured, but there is a problem that the manufacturing cost becomes high, and the film thickness of the coating is about several tens of μm. Therefore, there is a problem that the life due to wear is shortened.

  An object of the present invention is to provide a worm gear with reduced manufacturing cost, long life, and high power transmission capability.

  The worm gear according to the present invention is the second gear in the worm gear constituted by a first gear and a second gear having an axis orthogonal to the axis of the first gear and meshing with the first gear. A wheel is formed by processing a high hardness material obtained by increasing the hardness of a blank with a hob.

  According to the worm gear according to the present invention, a high-hardness material obtained by increasing the hardness of a blank is processed with a hob and finished into a wheel, so that a highly accurate wheel with a long life and high power transmission capability can be obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
1 to 4 and 7 are perspective views showing a method of processing a wheel in a worm gear according to the present invention.

  In FIG. 1A, the wheel material 2 is a high-hardness material formed by sintering a high-hardness metal compound, for example. As shown in FIG. 1 (b), the wheel 4 is manufactured by cutting the wheel material 2 with a hob 3. In FIG. 1B, each tooth of the wheel 4 is formed in an arch shape in which the bottom portion and the central portion of the top portion of the tooth are lowered as a whole so as to match the outer diameter of the worm. Moreover, the processing conditions at the time of gear-cutting a high-hardness material with the hob 3 can be processed so that cracks and cracks of the hob do not occur by setting the following conditions.

  Further, in the gear cutting by the hob 3, the hob 3 is cut into the wheel material 2 in the axial direction indicated by the straight arrow in FIG. 1B, the rotation speed of the hob 3 is Nh, and the number of teeth of the wheel is set. Assuming Z2, the wheel 4 is formed by gear cutting by setting the relationship between the rotation speed Nh of the hob and the rotation speed N2 of the wheel material 2 to be Nh / N2 = Z2 / Nh. The same applies to FIGS. 2 to 4 and FIG.

  According to the wheel processing method shown in FIG. 1, the wheel material 2 with high hardness is processed with the hob 3 to finish the wheel 4, so that a wheel with high hardness and high accuracy can be obtained.

  In FIG. 2, the blank material 1 in FIG. 2A is formed by cutting and cutting a round steel material such as S45C or SCM material or forging material, and the wheel material 2 in FIG. 2B is blank. The material 1 is made a high-hardness material by induction quenching or carburizing quenching and tempering. As shown in FIG. 2 (c), the wheel 4 is manufactured by cutting the wheel material 2 with the hob 3. In FIG.2 (c), it forms in the arch shape which the center part of the tooth bottom part and the tooth top became low so that it might match | combine with the outer periphery diameter of a worm | warm.

  According to the wheel processing method shown in FIG. 2, the high hardness wheel material 2 that has been made hard by heat treatment is processed with the hob 3 to finish the wheel 4, so that a high hardness and high accuracy wheel can be obtained.

  In FIG. 3, the blank material 1 in FIG. 3A is manufactured by cutting and cutting a round steel material such as S45C or SCM material or forging S45C or SCM material, as shown in FIG. 3B. As described above, the blank material 1 is cut by the hob 3 to produce the rough finish gear 5. The rough finish gear 5 is a helical gear having the same tooth height in the axial direction. In FIG. 3 (c), the rough-finished gear 5 is a gear 6 that has been subjected to high hardness treatment by induction hardening treatment or carburizing quenching treatment and tempering, and in FIG. The wheel 4 is manufactured by gearing the processed gear 6. In FIG.3 (d), it forms in the arch shape which the center part of the tooth root part and the tooth upper part became low so that it might match | combine with the outer periphery diameter of a worm | warm.

  According to the wheel processing method shown in FIG. 3, in the case of a worm gear having a large module, it is difficult to directly cut the hard material. However, after cutting in advance by rough finishing, By making the wheel 4 high in hardness, the precision finishing machining allowance can be reduced and the machining becomes easy.

  In FIG. 4, many blank materials 1 similar to those shown in FIG. 2 and FIG. 3 are stacked (FIG. 4A), and as shown in FIG. The rough-finished gears (helical gears) 5 are produced by gear cutting by the following steps. In FIG. 4C, each of the rough-finished gears 5 is subjected to high-hardness processing by induction hardening, carburizing and quenching, and tempering. In FIG. 4 (d), the gear 6 having a high hardness is formed into an arcuate shape in which the center portion of the tooth bottom portion and the top portion of the tooth is lowered so as to match the outer diameter of the worm with the hob 3. The wheel 4 is produced by gear cutting.

  According to the wheel machining method shown in FIG. 4, the machining time can be further shortened in the worm gear having a large module shown in FIG.

  FIG. 5 is a front view showing a contact state between the wheel and the worm when the wheel is manufactured by making the hob pitch circle diameter larger than the pitch circle diameter of the worm and gear cutting. Normally, when gears of high hardness are cut with a hob, the worm gear is usually made to have the same pitch circle diameter of the worm and the hob, but FIG. 5 (a) and FIG. 5 (b) (FIG. 5 (a) As shown in the enlarged view of part A)), since the contact 11 is point contact in the contact state between the worm 8 and the wheel 10 processed by the hob 3 having a larger pitch circle diameter than the worm, assembly is performed. An error can be tolerated, and the lubricating oil can be drawn between the tooth surfaces.

  FIG. 6 is a front view showing a contact state between the wheel and the worm when the wheel is manufactured by gear cutting with the hob pitch diameter equal to the pitch diameter of the worm. As shown in FIGS. 6 (a) and 6 (b) (enlarged view of portion A in FIG. 6 (a)), a wheel 7 that is a high-hardness material processed with a hob having the same pitch circle diameter as the worm, Since the tooth contact 9 with the worm 8 is in line contact, if there is an assembling error, one contact occurs.

As described above, in FIGS. 1 to 6, each tooth of the wheel 4 is a helical gear formed in an arcuate shape in which the bottom part of the tooth and the central part of the top part of the tooth are lowered to match the outer diameter of the worm. An example is shown.
In FIG. 7, the helical gear (FIG. 7 (a)) in which the wheel 4 directly cuts a hard material with the hob 3 is engaged with the wheel 4 and the worm 8 (FIG. 7 (b)). Is shown.

  In FIG. 7 (a), each tooth of the wheel 4 is a helical gear having rectangular teeth formed linearly at the bottom and top of the tooth between the axial directions instead of the arcuate shape. The worm 8 can be meshed well at any position in the four axial directions.

  FIG. 8 shows an example in which the wheel 12 manufactured as shown in FIGS. 1 to 7 is applied to the cylindrical worm 13 (FIG. 8A) and the hourglass worm 14 (FIG. 8B). The wheel in the worm gear of the present invention is applicable to both the cylindrical worm 13 and the hourglass worm 14.

  In the above wheel processing method, the processing conditions when the high-hardness material after induction hardening or carburizing quenching and tempering is geared with a hob are 50 to 100 m / min. The hob processing feed (the pushing amount of the hob per one rotation of the wheel) is set to 0.05 mm or less. Moreover, it processes without supplying lubricating oil and cooling oil to a process part.

  By setting it as such processing conditions, since the crack of a hob or crack generation can be prevented, productivity is improved.

  The worm gear described above is a geared motor with a worm (first gear) attached to the rotating shaft of the motor and a wheel (second gear) meshing with the worm, thereby reducing the size of the motor with low noise. Can be made.

  The worm gear according to the present invention can be effectively used for a geared motor or the like in which a motor and a speed reducer are integrally formed and a first gear is formed at one end of a motor shaft.

It is a perspective view which shows the processing method of the wheel in the worm gear which concerns on this invention. It is a perspective view which shows the processing method of the wheel in the worm gear which concerns on this invention. It is a perspective view which shows the processing method of the wheel in the worm gear which concerns on this invention. It is a perspective view which shows the processing method of the wheel in the worm gear which concerns on this invention. It is a front view which shows the contact state of a wheel and a worm at the time of manufacturing a wheel by making the pitch circle diameter of a hob larger than the pitch circle diameter of a worm, and gear cutting. It is a front view which shows the contact state of a wheel and a worm when the wheel is manufactured by gear cutting by making the pitch circle diameter of the hob the same as the pitch circle diameter of the worm. It is a perspective view which shows the processing method of the wheel in the worm gear which concerns on this invention. It is a front view which shows the example which applied the wheel to the cylindrical worm, and the example applied to the hourglass worm.

Explanation of symbols

1 blank material, 2 wheel material (high hardness material), 3 hob,
4, 7, 10, 12 wheel, 5 rough finish gear, 6 high-hardness processed gear,
8 worms, 9 wire contact teeth, 11 point contact teeth, 13 cylindrical worms,
14 Hourglass warm.

Claims (9)

A worm gear comprising a first gear and a second gear having an axis perpendicular to the axis of the first gear and meshing with the first gear, wherein the wheel being the second gear increases the hardness of the blank. A worm gear formed by processing a hard material with a hob. The peripheral speed of the hob is 50 to 100 m / min, the hob processing feed is 0.05 mm or less, and the high hardness material is processed to form a wheel without supplying lubricating oil and cooling oil to the processing part. The worm gear according to claim 1. The worm gear according to claim 1, wherein the blank material is processed with a hob after being made into a high-hardness material by carburizing or induction hardening. After roughing the blank in advance with a hob to form a rough finish gear, the rough finish gear is subjected to a quenching treatment, and the rough finish gear subjected to the quenching treatment is finished with a hob to form the wheel. The worm gear according to claim 1 or 2, wherein 5. The worm gear according to claim 4, wherein two or more of the blanks are stacked and rough-cut with a hob to form a rough-finished gear. 3. The worm gear according to claim 1, wherein the second gear is a wheel processed by a pitch circular hob larger than a pitch circle diameter of the first gear. The worm gear according to claim 1 or 2, wherein the second gear is a helical gear having rectangular teeth extending in the axial direction. 3. The worm gear according to claim 1, wherein the first gear is a cylindrical worm or a hourglass worm. A geared motor, wherein the worm gear according to any one of claims 1 to 8 is applied.

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