JP2010017795A - Grind finishing method of worm wheel and worm gear device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grind finishing method of a worm wheel using a steel worm wheel having high accuracy and combination reproducibility in a combination of the steel worm wheel subjected to surface hardening treatment and a steel worm. <P>SOLUTION: The steel worm wheel which is roughly cut by a worm hobbing machine is hardened by heat treatment, and then grind finishing is carried out, according to grinding conditions which has been set, by using a grindstone allowing highly hard abrasive grains to be electrically deposited on a conical shape which corresponds to a valley of a tooth formed by rotation of the tooth profile of the worm wheel. The grindstone is rotated while allowing the rotating shaft of the grindstone to be turned around the rotating shaft of the worm, and the worm wheel is simultaneously turned along a twisting angle of a tooth face. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for grinding a worm wheel using a steel worm wheel as a worm gear device, and a worm gear device combining the worm wheel and a steel worm.

In the conventional worm gear device, since the worm and the worm wheel transmit power while making sliding contact, the worm is usually made of steel and the worm wheel is made of a familiar copper alloy.
However, since copper alloys have low hardness, there is a problem that they are easily worn. In order to solve this problem, a steel worm wheel as disclosed in Patent Document 1 is disclosed. The worm gear device using the worm wheel of Patent Document 1 is a gear device that combines a worm made of hardened steel and a worm wheel made of hardened steel after being hobbed to mesh with the worm, and is small and large. The purpose is to transmit torque efficiently.

  The conventional grinding of gears and the dressing method of a grinding tool presented in Patent Document 2 relate to general grinding of gears, but of course can also be applied to worm gears combining worms and worm wheels. In the case of a worm grinding wheel or worm wheel grinding wheel, the worm and worm wheel are ground using a hob-type grindstone in which carbide abrasive grains are electrodeposited on the grinding tooth surface of the grindstone base material. And a method in which diamond abrasive grains harder than the cemented carbide grains on the surface of the grinding wheel are electrodeposited.

JP 2006-57778 A (paragraphs <0014> to <0021>) Japanese Patent No. 3096557 (paragraph <0013>)

  Copper alloy is often used for the worm wheel of the conventional worm gear device. Since the copper alloy has low hardness, when power is transmitted in combination with a steel worm, the familiarity of the teeth is good, but the wear resistance is low, so there is a problem that the power transmission ability is low and the wear easily occurs. Further, when tooth surface grinding for improving the tooth surface finish is performed, the material is soft, so that the grindstone is clogged and grinding work cannot be performed, and it becomes difficult to improve the tooth surface roughness.

When a torque is transmitted by combining a steel worm wheel as in the example of Patent Document 1 with a steel worm, the relative slip is large and the seizure is likely to occur in the normal involute tooth profile, and the speed cannot be increased. Power transmission capability is reduced. Further, the hob-type grindstone as disclosed in Patent Document 2 has a problem that it cannot be applied to the drum-type worm or the Neiman tooth worm.
The present invention relates to a worm wheel grinding method and a worm gear using a steel worm wheel with high accuracy and combination reproducibility in a combination of a steel worm wheel and a steel worm subjected to surface hardening treatment. An object is to provide an apparatus.

With respect to the above problems, the present invention aims to solve the problems by the following means.
(1) The first means for grinding and finishing the worm wheel is a tooth ridge formed by rotating a worm wheel tooth profile after heat-hardening a steel worm wheel roughly cut and formed by a worm hobbing machine. Use a grindstone electrodeposited with high-hardness abrasive grains in a conical shape equivalent to, and rotate the grindstone while rotating the grindstone's rotation axis around the rotation axis of the worm. At the same time, the worm wheel adjusts the torsion angle of the tooth surface. It rotates along, and it grinds according to the set grinding conditions, It is characterized by the above-mentioned.

(2) The worm wheel grinding finish method of the second means is the same as the worm wheel grinding finish method of (1) described above, in which the worm wheel tooth profile electrodeposited with high-hardness abrasive grains is rotated and molded. The cone-shaped grinding wheel is slightly narrower than the root width of the teeth of the worm wheel. The grinding wheel rotates while rotating the rotation axis of the grinding wheel around the rotation axis of the worm, and at the same time, the worm wheel follows the torsion angle of the tooth surface. When rotating, the grindstone is applied to one side of the teeth of the worm wheel, and both tooth surfaces are ground and finished according to the set grinding conditions.
(3) A third means for grinding and finishing the worm wheel is a method in which a worm wheel made by rough cutting with a worm hobbing machine is heat treated and hardened, and then the worm meshes with the teeth of the worm wheel electrodeposited with high-hardness abrasive grains. Rotate the shape of the grindstone around the rotation axis of the worm, grind the grindstone on both sides of the tooth surface of the worm wheel at the time of worm wheel grinding, rotate to a speed ratio set for the worm-shaped grindstone, The tooth surfaces on both sides are ground and ground simultaneously according to set grinding conditions.

(4) A fourth means for grinding and finishing the worm wheel is a method of grinding the worm wheel, which has been rough-cut by a worm hobbing machine, heat-treated and hardened, and then electrodeposited with high-hardness abrasive grains. A worm-shaped grindstone with a slightly narrower width was rotated around the rotation axis of the worm, and when grinding the worm wheel, the grindstone was grounded against one side of the tooth surface of the worm wheel and set for the worm-shaped grindstone. It is characterized by rotating to a speed ratio and grinding the tooth surfaces on both sides one by one according to the set grinding conditions.

(5) The fifth means of the worm wheel grinding finish method is the above-described worm wheel grinding finish method of (1) to (4), wherein the high-hardness abrasive grains electrodeposited on the grindstone are diamond fine grains or CBN ( It is characterized by being a fine grain of ultrahard material such as cubic boron nitride).

(6) The worm wheel grinding finish method of the sixth means is the pitch of the grindstone electrodeposited with high-hardness abrasive grains for grinding the worm wheel in the worm wheel grinding finish method of (1) to (5) above. The diameter is slightly larger than the pitch diameter of the worm combined with the worm wheel, and the crowning is applied to the tooth profile of the worm wheel.

(7) The worm wheel grinding finish method of the seventh means is the worm wheel cut and ground by the worm wheel grinding finish method of (1) to (6) above, and the worm tooth profile combined with the worm wheel is The simultaneous contact line is a Neiman tooth profile that intersects at a large angle with respect to the pitch circle.

(8) The worm gear device of the eighth means is characterized by combining a steel worm wheel and a steel worm processed by the worm wheel grinding finishing method of (1) to (7) above. And

  The invention according to claims 1 to 8 is a grinding finishing method of the above first to eighth means and a worm gear device manufactured by using this grinding finishing method, and it is accurate because the wear resistance is improved. Even if it is operated for a long time when it needs to be indexed properly (for example, used for driving a rotary table), there is no backlash fluctuation, and the accuracy of the stop position can be maintained. In addition, since steel material is used for the worm wheel, the bending stress and the surface pressure stress of the teeth are large, and the power transmission capacity of the worm gear device is remarkably increased.

  Also, since the grinding wheel is formed with the worm combined with the worm wheel as the base, the tooth contact in the actual machine of the worm and worm wheel is good, the finish grinding of the worm wheel is only once, the production process is shortened and low cost, Gears are interchangeable, and reproducible and accurate worm gear finishing is possible.

(First embodiment)
A method for grinding a worm wheel according to the first embodiment will be described with reference to the drawings. FIG. 1 is a block diagram showing processing steps of a worm wheel and a worm manufactured by the worm wheel processing method according to the first embodiment, and FIG. 2 is a Neiman tooth profile used for the worm and the worm wheel and a general involute. FIG. 3 is a perspective view showing a meshing state of a combination of a worm and a worm wheel made by using the Neiman tooth profile of FIG. 2, and FIG. 4 is a perspective view of a hob for roughing the worm wheel. FIG. 5 and FIG. 5 are perspective views showing grinding using a grinding tool for grinding and finishing the worm wheel according to the present embodiment.

The processing steps for the worm and the worm wheel will be described with reference to FIG.
C1: Worm material (hardenable steel).
C2: Lathe machining of the outer periphery other than the machining of worm teeth.
C3: Coarse cutting of the worm tooth profile into a Neiman tooth profile using a threading machine (lathe).
C4: Heat treatment by quenching only the tooth surface by quenching the processed product of C3 as a whole or induction quenching.
C5: Polishing of the outer diameter of the shaft diameter and outer diameter.
C6: A toothpaste in which the Neiman tooth profile worm 11 is completed by polishing the tooth surface with a rotating grindstone that creates a Neiman tooth profile.

D1: Worm wheel material (hardenable steel).
D2: Lathe machining of the outer periphery other than the machining of the teeth of the worm wheel.
D3: The tooth surface of the worm wheel is coarsely cut by the Neiman tooth profile hob 20 (FIG. 4). Reference numeral 25 denotes a Neiman tooth profile cutting blade.
D4: Quenching heat treatment of only the tooth surface by quenching the whole processed product of D3 or induction hardening. By this heat treatment, the rough finish worm wheel 14 is obtained.
D5: As shown in FIG. 5, while rotating the conical worm wheel finishing grindstone 17 for the Neiman tooth profile around the rotation axis Y ′ of the worm (W direction), the grindstone 17 is rotated in the V direction and simultaneously roughed. The worm wheel 14 rotates in the U direction along the torsion angle of the tooth surface, and the set grinding conditions (the V direction rotation speed of the grindstone 17, the W direction rotation speed of the worm rotation axis Y ′, the worm wheel) The grinding wheel finishes the worm wheel 12 by grinding according to the rotational speed of the 14 U direction, etc.). In FIG. 5, the portion represented by the dot pattern on the conical worm wheel finishing grindstone 17 is an electrodeposition grindstone portion 17a.

E1: Tooth contact inspection such as tooth contact and backlash performed by combining the worm wheel 12 and the Neiman tooth profile worm 11.
E2: Completion inspection such as dimensional inspection, scratches, scratches, etc. The worm gear device 10 as shown in FIG. 3 is completed.

In the tooth surface finish grinding according to the first embodiment, the conical worm wheel finishing grindstone 17 simultaneously grinds both surfaces of the teeth of the rough finish worm wheel 14. Further, since the rotational speed of the grindstone 17 can be rotated at a high speed as long as the electrodeposited grindstone portion 17a of the superhard abrasive grains electrodeposited on the grindstone 17 is not altered or peeled off, the grinding ability is high. Raised. As the abrasive grains forming the electrodeposited grinding wheel portion 17a, high-hardness abrasive grains having a Knoop hardness of 4000 kg / mm ² or more are used, more preferably diamond fine grains (Knoop hardness of 8000 to 8500 kg / mm ² ) or heat resistance. Super-hard abrasive grains such as fine grains such as CBN (cubic boron nitride: Knoop hardness 4700 kg / mm ² ), which are excellent in the above, are used. This grinding method is preferable when the quenching distortion of the tooth surface by the heat treatment step D4 is small.

  FIG. 2 shows a worm gear device 10 using a Neiman tooth profile worm 11 and a worm wheel 12 using a Neiman tooth profile, and a worm gear device 30 using a general involute tooth profile used for an involute tooth profile worm 31 and a worm wheel 32. FIG. 5 is a view showing respective meshing contact lines. The crossing angle β between the Neiman tooth profile contact line 13 and the pitch circle of the Neiman tooth profile worm 11 of FIG. 2-(I) is the pitch circle of the involute tooth profile contact line 33 and the involute tooth profile worm 31 of FIG. In the meshing operation of the worm and the worm wheel, the Neiman tooth profile in FIG. 2- (I) has a larger rolling element than the involute tooth profile in FIG. 2- (II). The involute tooth profile of (II) shows that relative slip is larger than the Neiman tooth profile of FIG. 2- (I). That is, it is suggested that the Neiman tooth profile in Fig. 2- (I) has less seizure factors between teeth than the involute tooth profile in Fig. 2- (II) in the transmission of meshing torque between the steel worm and the steel worm wheel. ing.

  In FIG. 5, the radius of curvature of the grinding surface is completed by slightly increasing the pitch diameter of the conical worm wheel finishing grindstone 17 for grinding the rough finish worm wheel 14 to be slightly larger than the pitch diameter of the finished Neiman tooth worm 11. If the radius of curvature of the tooth surface of the finished Neiman tooth profile worm 11 combined with the finished worm wheel 12 is made slightly larger so that the crowning is applied to the tooth profile of the finished worm wheel 12, the lubricity is further improved. Is done.

  If it is confirmed that the Neiman tooth profile worm 11 and the worm wheel 12 have good contact with each other, and the Neiman tooth profile worm 11 is ground according to the optimum grinding conditions of the worm grinding wheel, then the Neiman tooth profile worm 11 and the worm wheel 12 are actually machined. In the tooth contact inspection in, only the final process is required, and the finish grinding of the worm is only once, the production process is shortened, and the reproducible and accurate worm finish is possible at low cost.

(Second Embodiment)
The worm wheel grinding finishing method of the second embodiment is different from the worm wheel grinding finishing method of the first embodiment in the worm and worm wheel machining steps described above in the worm wheel in the grinding step D5. Since only the grinding method is used and all other processes are the same, the description is omitted except for the grinding process D5.

  In FIG. 5, a conical worm wheel finishing grindstone 17 in which high-hardness abrasive grains are electrodeposited into a conical shape formed by rotating a Neiman tooth profile is slightly narrower than the tooth valley width of the rough worm wheel 14. When the grindstone 17 is rotated around the rotation axis Y ′ of the worm, the grindstone 17 is rotated in the V direction, and at the same time, the rough finish worm wheel 14 is rotated in the U direction so that the tooth surface follows the twist angle. The electrodeposition grindstone portion 17a of the grindstone 17 is applied to one side of the teeth of the rough finish worm wheel 14, and the set grinding conditions (V-direction rotation speed of the grindstone 17 and W-direction rotation of the worm rotation axis Y ′) are set. Both the tooth surfaces are ground and finished one by one in accordance with the speed, the rotational speed of the worm wheel 14 in the U direction, and the like.

  In addition, when the quenching distortion of the tooth surface by said heat processing process D4 is comparatively large, since the machining allowance by grinding must be increased, this grinding method becomes suitable. If the Neiman tooth profile worm 11 is ground by the optimum grinding conditions and it is confirmed that the contact between the Neiman tooth profile worm 11 and the worm wheel 12 is good, the tooth contact inspection in the actual machine of the Neiman tooth profile worm 11 and the worm wheel 12 is as follows. Only the final process is required, the production process is shortened, and low-cost, accurate reproducible worm finishing is possible.

(Third embodiment)
The worm wheel grinding finishing method of the third embodiment is different from the worm wheel grinding finishing method of the first embodiment in the worm and worm wheel machining steps described above in the grinding step D5 worm wheel. Since only the grinding method is used and all other processes are the same, the description is omitted except for the grinding process D5.

As shown in FIG. 6, in the grinding step D5 of the worm wheel grinding finish method of the third embodiment, the steel rough finish worm wheel 14 roughly cut and formed by the Neiman tooth profile hob 20 is heat treated in the heat treatment step D4. After hardening, a worm-shaped worm grinding grindstone 18 (made following the Neiman tooth profile worm 11 that actually meshes with the teeth of the coarsely finished worm wheel 14) electrodeposited with high-hardness abrasive grains is rotated about the rotation axis Y. However, when the central portion of the grindstone 18 coincides with the central portion of the rough finish worm wheel 14, the movement of the grindstone 18 in the rotational axis Y direction is stopped, and thereafter the rough finish worm is moved. The wheel 14 is rotated in the U direction, and grinding is continued while maintaining a relative speed that matches the speed ratio.
In FIG. 6, what is indicated by a dot pattern on the worm grinding wheel 18 is an electrodeposited grinding wheel portion 18a.

  At the time of grinding, the worm grinding wheel 18 is ground on both sides of the tooth surface of the rough finish worm wheel 14, and the worm-shaped worm grinding wheel 18 rotates to a set speed ratio, and the set grinding condition (the worm grinding wheel 18 is set. The grinding finish is performed according to the rotational speed in the T direction, the rotational speed in the U direction of the rough finish worm wheel 14, etc.). This grinding method is suitable when the quenching distortion of the tooth surface due to the heat treatment step D4 is small.

  In the third embodiment, similarly to the first embodiment, the pitch diameter at the time of processing the worm grinding wheel 18 is slightly larger than the pitch diameter of the finished Neiman tooth worm 11, so The radius of curvature is slightly larger than the radius of curvature of the tooth surface of the finished Neiman tooth profile worm 11, so that the crowning is applied to the tooth profile of the finished worm wheel 12.

(Fourth embodiment)
The worm wheel grinding finishing method of the fourth embodiment is different from the worm wheel grinding finishing method of the first embodiment in the worm and worm wheel machining steps described above in the worm wheel in the tooth grinding step D5. Since only the grinding method is used and all other processes are the same, the description is omitted except for the grinding process D5.

  The worm wheel grinding finishing method of the fourth embodiment will be described with reference to FIG. The steel rough finish worm wheel 14 roughly cut and formed by the Neiman tooth profile hob 20 of FIG. 4 is heat-treated and hardened in the heat treatment step D4, and then high-hardness abrasive grains are electrodeposited, and the tooth valley width of the rough finish worm wheel 14 A worm-shaped worm grinding wheel 180 made with a slightly narrower width is moved around the rotation axis Y while rotating around the rotation axis Y, and the center of the grindstone 180 coincides with the center of the rough finish worm wheel 14. Then, the movement of the grindstone 180 in the direction of the rotation axis Y is stopped, and thereafter, the rough finish worm wheel 14 is rotated in the U direction, and the grinding is continued while maintaining the relative speed matching the speed ratio.

  In this case, the grindstone 180 is ground on one side of the tooth surface of the rough finish worm wheel 14, rotated to a speed ratio set with respect to the worm-shaped grindstone 180, and both sides one side at a time according to the set grinding conditions. Grind finish of the tooth surface. When the quenching distortion of the tooth surface due to the heat treatment step D4 is relatively large, the grinding allowance must be increased, so this grinding method is suitable. Further, when the grindstone 180 is applied to the rough finish worm wheel 14, there is a gap in which the grindstone 180 can move in the axial direction, so that the grindstone 180 is moved in the outer diameter direction (X direction) of the rough finish worm wheel 14. Is possible, and grinding work is easy.

It is a block diagram which shows the manufacturing process of the worm wheel and worm manufactured by the processing method of the worm wheel concerning embodiment of this invention. It is the figure which showed the meshing contact line of each Niemann tooth profile used for the worm | warm and worm wheel of this invention, and a general involute tooth profile. It is a perspective view which shows the combined meshing state of the worm | worm and worm wheel produced using the Neiman tooth profile of FIG. It is a perspective view of the Neiman tooth profile hob which rough-finishes a worm wheel. It is a perspective view which shows the grinding process using the grinding tool which grind-finishes the worm wheel concerning the 1st and 2nd embodiment of this invention. It is a perspective view which shows the grinding process using the grinding tool which grind-finishes the worm wheel concerning the 3rd and 4th embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Worm gear apparatus 11 Neiman tooth profile worm 12 Worm wheel 13 Contact line 14 of Neiman tooth profile Rough finish worm wheel 17 Conical worm wheel finishing grindstone 17a, 18a Electrodeposition grindstone 18, 180 Warm grinding grindstone (worm type)
20 Neiman tooth profile hob

Claims (8)

  A grindstone in which high-hardness abrasive grains are electrodeposited in a conical shape corresponding to the valley of a tooth formed by rotating the tooth profile of a worm wheel after heat-treating and hardening a steel worm wheel that has been roughly cut by a worm hobbing machine The wheel is rotated while rotating the rotation axis of the grinding wheel around the rotation axis of the worm, and at the same time, the worm wheel is rotated along the torsion angle of the tooth surface and finished in accordance with the set grinding conditions. A method for grinding and finishing a worm wheel. In the worm wheel grinding finishing method according to claim 1,
The cone-shaped grinding wheel formed by rotating the tooth profile of the worm wheel electrodeposited with high hardness abrasive grains is slightly narrower than the valley width of the worm wheel tooth, and the rotation axis of the grinding wheel is around the rotation axis of the worm. When rotating the grinding wheel while rotating, and simultaneously rotating the worm wheel along the torsion angle of the tooth surface, apply the grinding wheel to one side of the tooth of the worm wheel and grind both tooth surfaces one by one according to the set grinding conditions A method for grinding a worm wheel, characterized by finishing.   A steel worm wheel roughly cut and formed by a worm hobbing machine is heat-treated and hardened, and then a worm-shaped grindstone that meshes with the teeth of the worm wheel electrodeposited with high-hardness abrasive grains is rotated around the rotation axis of the worm, and the worm wheel During grinding, the grinding wheel is applied to both sides of the tooth surface of the worm wheel, and the wheel is rotated to a speed ratio set for the worm-shaped grinding wheel, and the tooth surfaces on both sides are simultaneously ground according to the set grinding conditions. A method for grinding and finishing a worm wheel.   A steel worm wheel roughly cut and formed by a worm hobbing machine is heat-treated and hardened, and then a worm-shaped grindstone with a width slightly narrower than the valley width of the teeth of the worm wheel electrodeposited with high-hardness abrasive grains is rotated around the rotation axis of the worm During grinding of the worm wheel, the grinding wheel is applied to one side of the tooth surface of the worm wheel to grind it, rotate to the speed ratio set for the worm-shaped grinding wheel, and according to the set grinding conditions, A method for grinding a worm wheel, characterized by grinding a tooth surface. In the worm wheel grinding finishing method according to claims 1 to 4,
A grinding method for a worm wheel, characterized in that the high-hardness abrasive grains electrodeposited on the grindstone are diamond fine grains or fine grains of superhard material such as CBN (cubic boron nitride).   The worm wheel grinding finishing method according to any one of claims 1 to 5, wherein the pitch diameter of the grindstone electrodeposited with high-hardness abrasive grains for grinding the worm wheel is slightly larger than the pitch diameter of the worm combined with the worm wheel. A method for grinding and finishing a worm wheel, characterized in that crowning is applied to the tooth profile of the worm wheel.   The worm wheel to be cut and ground by the method according to claim 1 and the tooth profile of the worm combined with the worm wheel are Neiman tooth profiles in which simultaneous contact lines intersect at a large angle with respect to the pitch circle. How to finish grinding worm wheel.   A worm gear device comprising a combination of a steel worm wheel and a steel worm finished by the grinding finishing method according to claim 1.

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