JP2002120116A - Manufacturing method of outer tooth gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an outer tooth gear having low manufacturing cost allowing improvement of a lubricating state of a tooth surface of the outer tooth gear with less processes than the prior art. SOLUTION: This manufacturing method of the outer tooth gear internally contacting and engaging with an inner tooth gear inside the inner tooth gear comprises a process of machining a material to a disk, a process of opening in the disk a central hole 11, a carrier pin hole 15, and an inner pin hole 17 required for constituting a transmitting mechanism, a process of forming a tooth form in the outer periphery of the disk by hobbing, a process of hardening the surface of the tooth by a thermal treatment after the hole forming process and the tooth form forming process, and a process of finishing the central hole 11 and the inner pin hole 17 while supporting the tooth form with three pins 40 as reference points after the thermal treatment process. Surface roughness of the tooth surface especially in the tooth stripe direction is kept in a finished product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an external gear that meshes with the internal gear inside the internal gear.
In particular, the present invention relates to a method for manufacturing an external gear used for a gear transmission in which the center of the internal gear is inside the periphery of the external gear.

[0002]

2. Description of the Related Art Conventionally, a gear transmission having an external gear internally meshed with the internal gear inside the internal gear, and the center of the internal gear is inside the periphery of the external gear. 2. Description of the Related Art A device (a transmission device corresponding to the international classification F16H1 / 32) is widely known.

[0003] As a typical example of this type of transmission, a first shaft, an eccentric body that rotates by rotation of the first shaft, and an eccentric body that is attached to the eccentric body via a bearing to enable eccentric rotation. A plurality of external gears, an internal gear that meshes internally with the external gear via internal teeth formed of external pins, and an internal pin that extracts only the rotation component of the external gear to the external gear. And a second shaft connected through the shaft.

FIGS. 4 and 5 show a conventional example of this structure.
In this conventional example, the first shaft is used as an input shaft and the second shaft is used as a second shaft.
The above structure is applied to a "reduction gear" by using a shaft as an output shaft and fixing an internal gear.

In FIGS. 4 and 5, reference numeral 1 denotes a reduction gear casing, and a first casing 1A and a second casing 1B at both ends, and a main casing 1 serving as a central internal gear 7 at both ends.
C. 2 is an input shaft, 3 is an output shaft, 4 and 5 are bearings that rotatably support the input shaft 2, and 6 is a bearing that rotatably supports the output shaft 3. The input shaft 2 and the output shaft 3 are arranged on the same axis, and the bearing 6 supporting the output shaft 3 is fitted to the first casing 1A.

The gear transmission mechanism in this reduction gear is mounted on the outer periphery of the input shaft 2 by two eccentric bodies 8 provided so as to rotate integrally with the input shaft 2, and mounted on the outer periphery of the eccentric body 8 via a bearing 9. The external gear 10 includes two external gears 10 rotatable eccentrically with respect to the input shaft 2, and the internal gear 7 also serving as a casing in which the external gear 10 meshes internally. The bearing 9 that supports the external gear 10 around the eccentric body 10 is fitted in the center hole 11 of the external gear 10. On the outer periphery of the external gear 10, external teeth such as a trochoid tooth shape and an arc tooth shape are provided, and on the inner periphery of the internal gear 7, internal teeth made of an external pin 12 are provided.

[0007] A pair of carriers 13 and 14 are arranged on both sides of the two external gears 10. Both carriers 13, 14
Are integrally connected by a plurality of carrier pins 16 penetrating through carrier pin holes 15 of the external gear 10. The external gear 10 is provided with a plurality of inner pin holes 17, into which the inner pins 18 are loosely fitted. Thus, only the rotation component of the external gear 10 is transmitted to the carriers 13 and 14 on both sides via the inner pin 18.

The other end of the carrier 14 is formed integrally with the base end of the output shaft 3, and a bearing 5 for supporting the other end of the input shaft 2 is fitted into a recess formed in the carrier 14. Have been combined.

A bearing 4 for supporting one end of the input shaft 2 is fitted on the inner periphery of the carrier 13 on one end, and the carrier 13 on one end is fitted into a bearing 19 inside the second casing 1B.
It is rotatably supported via. And input shaft 2
The components constituting the gear mechanism such as the gear and the external gear 10 are incorporated into the main casing 1C also serving as the internal gear 7, and the first and second casings 1 are bolted to the main casing 1C.
By fixing A and 1B, the illustrated speed reducer is completed.

The operation of the speed reducer will be described.

When the input shaft 2 makes one rotation, the eccentric body 8 makes one rotation. One rotation of the eccentric body 8 causes the external gear 10 to oscillate around the input shaft 2, but its rotation is restricted by the internal gear 7, so that the external gear 10
Performs almost only rocking while inscribed in the internal gear 7.

For example, if the number of teeth of the external gear 10 is N and the number of teeth of the internal gear 7 is N + 1, the difference N between the teeth is 1. Therefore, each time the input shaft 2 rotates, the external gear 10
Is shifted by one tooth (rotates) with respect to the internal gear 7 fixed to the casing 1. This is input shaft 2
Means that the rotation of the external gear 10 has been reduced to the rotation of -1 / N.

The rotation of the external gear 10 is absorbed by the gap between the inner pin hole 17 and the inner pin 18 so that the swinging component is absorbed.
Only the rotation component is transmitted to the output shaft 3 via the inner pin 18.

As a result, deceleration at a reduction ratio of -1 / N (minus represents reverse rotation) is achieved.

The structure of the internally meshing planetary gear is currently applied to various speed reducers or speed-increasing gears. For example, in the above structure, the first shaft is used as the input shaft, the second shaft is used as the output shaft, and the internal gear is fixed. However, the first shaft is used as the input shaft, and the internal gear is used as the output shaft. Along with
The speed reducer can also be configured by fixing the second shaft. Furthermore, in these structures, a “speed-increasing gear” can be configured by using the second shaft as the input shaft.

By the way, the external gears constituting this kind of internally meshing planetary gear mechanism have been conventionally manufactured in the following steps. This will be described with reference to FIG.

(1) First, a material is formed on a disk.

(2) Next, holes (center hole 11, carrier pin hole 15, and inner pin hole 17) necessary for forming a transmission mechanism are formed in the disk.

(3) A trochoid tooth profile is formed on the outer periphery of the disk by hobbing.

Either of the steps (2) and (3) may be performed first.

(4) Next, the tooth surface is hardened by heat treatment.

(5) Next, the center hole 11 is finished by grinding or cutting, and the inner pin hole 17 is finished with the center hole 11 as a reference.

(6) Next, the tooth surface is ground. in this case,
To ensure efficiency and accuracy, the diameter of the grinding wheel is set to be sufficiently large with respect to the tooth width, and the grinding wheel is rotated in the tooth trace direction to grind the tooth surface on the peripheral surface of the grinding wheel. Then, irregularities on the tooth surface formed in the hobbing stage are removed. Note that the tooth trace direction is the arrow S direction in the figure, and the tooth profile direction is the arrow K direction in the figure.

Through the final grinding step as described above, a finished external gear before being incorporated as a transmission mechanism is obtained. In some cases, the next step is added after that.

(7) Perform shot peening or barrel processing.

(8) A chemical conversion treatment is further performed.

The chemical conversion treatment (8) is a technique for forming a chemical conversion coating such as a phosphate film on the sliding portion to lower the friction coefficient of the sliding portion. This chemical conversion treatment film is not a low coefficient of friction per se, but has a small amount of lubricating oil retained on minute irregularities to reduce the coefficient of friction.

In this case, there is an example in which a chemical conversion coating is directly formed on the sliding contact surface. However, the chemical conversion coating itself is liable to wear and has a weak point that the coating peels off in a short time. No. 36825 (Patent No. 1623717)
No.), an uneven surface is formed in advance in the tooth trace direction of the tooth profile and in a direction (tooth profile direction) intersecting with the tooth trace direction of the tooth profile, and a chemical conversion treatment is performed with a film thickness lower than the height of the irregularities. We propose a technique for applying a film.

[0029]

As described above, in the conventional method of manufacturing an external gear, the tooth surface after hobbing is ground so as to positively eliminate the surface roughness due to hobbing. ing. This was a common practice in the production of this type of gear, which itself did not raise any particular questions. The present invention, based on a review of this previously unquestioned method from a different angle, has found a new merit that could not be expected in the past, based on that knowledge, It is an object of the present invention to provide a method of manufacturing an external gear with less manufacturing costs by improving the lubrication state of the tooth surface of the external gear with fewer steps than before.

[0030]

According to a first aspect of the present invention, there is provided a method of manufacturing an external gear which is internally meshed with the internal gear inside the internal gear. Drilling the necessary holes to configure the transmission mechanism,
A step of forming a tooth profile on the outer periphery of the disk by hobbing, and a step of performing a heat treatment after the perforating step and the tooth profile forming step to harden the tooth surface, and the surface of the tooth surface by the hob cutting. The problem has been solved by maintaining the roughness in the finished product.

According to a second aspect of the present invention, there is provided a method of manufacturing an external gear which is internally meshed with the internal gear inside the internal gear, wherein a step of processing a material into a disk and a transmission mechanism are formed on the disk. Forming a tooth profile by hobbing the outer periphery of the disk, performing a heat treatment after the hole forming process and the tooth profile forming process to harden the tooth surface, Finishing the hole while supporting the tooth profile as a reference point after the step, and solving the above problem by maintaining the surface roughness of the tooth surface by the hobbing in the finished product. is there.

According to the first and second aspects of the present invention, the tooth surface of the finished external gear before being incorporated into the transmission mechanism is dared.
Surface roughness (unevenness) in hobbing is left. That is, as a finish of the tooth surface after hobbing, grinding was conventionally performed, but by daringly omitting the grinding that was performed with common sense, hobbing is particularly performed in the tooth trace direction of the tooth surface. This is a finished product with no irregularities left before being incorporated into the transmission mechanism.

In recent years, with the improvement of the basic performance of processing machines,
The surface irregularities created by hobbing have become quite small. However, these irregularities still have to be said to be considerably large as the surface roughness of the tooth profile of this type of external gear, and therefore, conventionally, the subsequent grinding is considered to be "essential". Was.

However, the inventor paid attention to the unevenness of the surface due to the hobbing from another angle. That is, the surface irregularities formed by the hobbing can be formed not only in the "tooth direction" but also in the "tooth trace direction". In particular, the unevenness in the tooth trace direction is periodically formed due to the characteristics of hobbing, and the amplitude is relatively stable. The unevenness in the tooth trace direction does not have much adverse effect upon meshing unlike the unevenness in the tooth profile direction.
On the other hand, the unevenness is sufficiently large as a space for holding the lubricating oil. If sufficient lubricating oil is supplied to the tooth surface, the meshing resistance and the meshing noise can be reduced even if the surface (in the tooth profile direction) is somewhat rough. Therefore, if heat treatment is performed on this so that the unevenness in the tooth trace direction is not easily crushed, it is possible to hold the lubricating oil in this space for a long time,
There is a possibility that the predetermined performance (within an acceptable range) can be maintained for a long period of time.

This attention was confirmed not to be incorrect by subsequent tests and studies by the inventor, and became the basis of the present invention. That is, according to the present invention, the unevenness formed on the tooth surface of the external gear by the hobbing, particularly in the tooth trace direction, is effectively utilized, and a large amount of lubricating oil is retained in the unevenness, and an oil film is formed on the tooth surface. , The engagement resistance can be reduced and the wear can be reduced. As a result, it is possible to reduce the meshing noise, improve the efficiency, and the like, and not only satisfy the performance required for this type of gear, but also maintain the performance for a long period of time. Above all, the machining time can be shortened by omitting the grinding process, and the machining cost can be reduced by omitting the grinding device.

Either of the hole making step and the hobbing step may be performed first. Therefore, an arrangement in which only this order is reversed is included in the present invention.

In general, holes of this type of external gear are important elements in constituting a power transmission mechanism. If distortion occurs due to heat treatment, assembly accuracy may be reduced. Therefore, in the invention of claim 2, after the heat treatment step, the final finishing is performed for the purpose of reducing the distortion of the hole. In this case, the accuracy of the hole with respect to the tooth profile can be improved by finishing the hole with reference to a plurality of predetermined positions on the tooth profile of the external gear.
As a method of supporting a plurality of predetermined positions on the tooth profile as a reference, for example, a method of supporting three or more pins in contact with the tooth profile can be used. After heat treatment, thermal distortion of the external teeth also remains, but in the case of this type of external gear, since the number of meshing with the internal teeth is large, the error is leveled out, which is a problem especially in ordinary applications. It has also been confirmed that it should not.

According to a third aspect of the present invention, there is provided a method of manufacturing an external gear which is internally meshed with the internal gear inside the internal gear, wherein a step of processing the material into a disk and a transmission mechanism are formed on the disk. Forming a tooth profile by hobbing on the outer periphery of the disk, and after forming the tooth profile by hobbing, shot peening or barreling the tooth surface in the hobbed state. A step of performing processing and a step of performing a heat treatment after the step to harden the tooth surface, and maintaining the surface roughness of the shot-peened or barrel-processed tooth surface in the finished product, It is a solution to the problem.

According to a fourth aspect of the present invention, there is provided a method of manufacturing an external gear which is internally meshed with the internal gear inside the internal gear, wherein a step of processing a material into a disk and a transmission mechanism are formed on the disk. Forming a tooth profile by hobbing on the outer periphery of the disk, and after forming the tooth profile by hobbing, shot peening or barreling the tooth surface in the hobbed state. A step of performing processing, a step of performing a heat treatment after the step to surface harden the tooth surface, and a step of finishing the hole while supporting the tooth profile as a reference point after the heat treatment step, and shot peening. Alternatively, the above problem has been solved by maintaining the surface roughness of the tooth surface subjected to barrel processing in the finished product.

According to the third and fourth aspects of the present invention, the tooth surfaces in the hobbed state are subjected to shot peening or barrel processing, followed by heat treatment. As a result, in the tooth trace direction, a state in which the lubricating oil is more easily retained (rougher) is formed while basically leaving the unevenness of the hobbing, and on the other hand, in the tooth profile direction that has an influence on the meshing resistance and the meshing noise. As a result, it is possible to form a state in which unevenness in hobbing is smoothed. As a result, it is possible to more rationally maintain and secure the lubricating oil and reduce the meshing resistance and the meshing noise.

In addition, when shot peening or barrel processing is performed before the heat treatment step, processing is performed at a stage where the hardness of the material is lower than when shot peening or barrel processing is performed after the conventional heat treatment step. Therefore, the processing time can be reduced, and the processing cost can be reduced.

Of course, also in this case, the processing time can be reduced by omitting the grinding process, and the processing cost can be reduced by omitting the grinding device.

In the third and fourth aspects of the present invention, either of the hole making step and the hobbing step may be performed first, and even if the order is changed, they belong to the scope of these inventions.

[0044]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

The external gear to be manufactured in this case is the same as the external gear 10 shown in FIGS. 4 and 5 in terms of shape.

The external gear 10 has a trochoidal tooth profile on the outer periphery, and is processed as a completed product in the following process order. The numbers in the parentheses in the figure correspond to the respective steps.

(1) First, the material is processed into a disk.

(2) Three kinds of holes (a center hole 11, a carrier pin hole 1) necessary for forming a transmission mechanism are formed on the disk.
5. Open the inner pin hole 17).

(3) A tooth profile is formed on the outer periphery of the disk by hobbing.

(4) Heat treatment is performed to harden the tooth surface.

(5) The center hole 11 and the inner pin hole 17 are finished while supporting a plurality of predetermined positions on the tooth profile as reference points.

Here, the "hob cutting" of (3) is a kind of a conventionally known generating gear cutting method, and is a virtual rack formed by a cutting edge of a tool by rotating a screw-shaped tool (hob). By giving the gear material the ideal meshing rotation,
The teeth are sequentially processed.

For finishing (5), for example, 3
The center hole 11 and the inner pin hole 17 are finished by grinding or cutting while holding the pin 40 in contact with three places on the tooth profile.

The external gear 10 is completed only by going through the above-mentioned steps, that is, it is completed without dare grinding the tooth surface. (Unevenness in the direction) is left as it is after the heat treatment, and is incorporated as an element of the transmission mechanism.

As described above, since the unevenness due to the hobbing remains in the tooth surface of the external gear 10 particularly in the tooth trace direction, a large amount of lubricating oil is held in the unevenness of the tooth surface, and The formation of an oil film on the surface is facilitated, so that frictional resistance can be reduced and wear over a long period can be reduced. As a result, the noise value can be reduced, the efficiency can be improved, and the predetermined performance as this type of gear can be obtained.

Further, since the grinding process is intentionally omitted, the processing time for that purpose can be shortened, and the processing cost can be reduced by omitting the grinding device, thereby facilitating the manufacturing and reducing the manufacturing cost. Products can be provided. Either the hole making step or the hobbing step may be performed first.

Further, finishing of the central hole 11 and the inner pin hole 17 which are important in constituting the transmission mechanism is performed based on three points of the tooth shape of the external gear 10 after the heat treatment step. Therefore, the positional accuracy of the holes 11 and 17 with respect to the tooth profile can be maintained high.

Here, in order to further secure the performance as an external gear, shot peening or barrel processing is performed between the above-mentioned (3) hobbing step and (4) heat treatment step.

The shot peening process is a type of spraying process in which a steel ball (shot) is accelerated by air pressure or centrifugal force or the like, and the steel ball (shot) collides with a tooth surface. By generating residual compressive stress on the tooth surface, the tooth surface can be smoothed and the durability can be improved by work hardening.

The barrel processing is a process in which an abrasive and a chemical (compound) are mixed in a tank (barrel), and rotation or vibration is applied to the outer gear and the abrasive in the tank. And a method of grinding and polishing the surface of the external gear, which is also known per se. The barrel processing can also be expected to improve the durability due to surface smoothing or work hardening.

By adding a step of performing shot peening or barrel processing on the tooth surface in the hobbed state, in the finished product, the tooth surface in the tooth profile direction is particularly smoothed, and the cross-sectional shape in the tooth trace direction is obtained. Can be formed in a shape that can more easily hold the lubricating oil.

The difference in the surface roughness of the external gear between the case where the external gear is manufactured by the conventional process and the case where the external gear is manufactured by the process of the present invention will be described with reference to experimental data.

FIG. 2 shows the roughness data when measured in the tooth trace direction, and FIG. 3 shows the roughness data when measured in the tooth profile direction. FIG. (B) shows data in the case of barrel processing after hobbing (the present invention), and (c) shows data in the case of hobbing only (the present invention). In addition, the reason why each data when measured in the tooth profile direction of FIG. 3 is (to the right) downward right is that the tooth profile of the measurement portion has such a profile.

When barrel processing is performed after grinding (conventional),
A certain degree of smoothness is ensured in both the tooth trace direction and the tooth profile direction, and (at least in initial performance) a result sufficiently satisfying various characteristics required for this type of external gear is obtained.

However, the performance of retaining lubricating oil is rather inferior to the extent that the entire surface is smooth, and depending on the operating conditions, there is a possibility that the durability may decrease due to the oil film running out of the tooth surface. Above all, processing takes time and processing costs are high.

On the other hand, in the case of hobbing only (the present invention), in both the tooth trace direction and the tooth profile direction, larger irregularities remain than in the case of barrel processing after conventional grinding. This unevenness is considerably large, and it is conventionally considered that the characteristics required for the tooth surface of this type of external gear cannot be satisfied as it is.

However, in reality, on the contrary, the unevenness functions to form a space for holding the lubricating oil, and does not cause a problem as large as the dimensional roughness. This has been confirmed by a test by the inventor as described above.

Further, in the case where the barrel processing is performed after the hobbing (the present invention), the lubricating oil is more easily held in the tooth trace direction than in the hob cutting alone, but the lubricating oil is formed in the tooth profile direction. Is very smooth. The main factor that adversely affects the meshing resistance and meshing noise in meshing this type of gear is the roughness in the tooth profile direction. It can be said that the characteristic of being provided gives a more rational characteristic (compared to the case of only hobbing).

The same qualitative tendency can be obtained when shot peening is performed after hobbing.

[0070]

As described above, according to the present invention,
The grinding process after hobbing, which was conventionally performed by common sense, was omitted daringly, and the finished product before assembling as a transmission mechanism the roughness of the tooth surface as hobbed (particularly the roughness in the tooth trace direction). Since it is maintained, the lubricating oil holding capacity of the tooth surface can be remarkably enhanced in a state where the transmission mechanism is assembled. Therefore, it is possible to reduce the frictional resistance and the noise, and it is possible to maintain, for a long period of time, the characteristics of this type of external gear that have no practical problem.

Further, since the grinding step can be omitted, the manufacturing cost can be greatly reduced, and inexpensive products (such as reduction gears) can be provided.

[Brief description of the drawings]

FIG. 1 is a process explanatory view of a method for manufacturing an external gear according to an embodiment of the present invention.

FIG. 2 is a view showing the surface roughness in the tooth trace direction of the external gear formed by the conventional method and the method of the present invention. FIG. 2 (a) shows the conventional hobbing, grinding and then barreling. FIG. 4B is a diagram showing the surface roughness in the case, FIG. 4B is a diagram showing the surface roughness when the barrel processing is performed without grinding after the hobbing,
(C) is a diagram showing the surface roughness of the hob cut as it is.

FIG. 3 is a diagram showing the surface roughness in the tooth profile direction of the external gear formed by the conventional method and the method of the present invention. FIG. 3 (a) shows the case where the conventional hobbing is performed, followed by grinding and then barreling. The figure which shows the surface roughness of the case where barrel processing was performed without performing grinding after hobbing,
(C) is a diagram showing the surface roughness of the hob cut as it is.

FIG. 4 is a sectional view of an internally meshing planetary gear mechanism including an external gear to be manufactured according to the present invention.

FIG. 5 is a sectional view taken along the line VV in FIG. 4;

FIG. 6 is a process explanatory view of a conventional method for manufacturing an external gear.

[Explanation of symbols]

 7 Internal gear 10 External gear 11 Center hole 17 Internal pin hole

 ──────────────────────────────────────────────────の Continued on the front page F term (reference) 3C025 AA16 3J027 FA20 GA01 GB03 GC03 GC24 GC26 GD03 GD08 GD12 GE14 3J030 AC01 AC03 BA01 BC03

Claims (4)

[Claims] 1. A method of manufacturing an external gear which is internally meshed with the internal gear inside the internal gear, comprising: a step of processing a material into a disk; and a hole required for forming a transmission mechanism in the disk. Forming a tooth profile by hobbing on the outer periphery of the disk; and performing a heat treatment after the hole forming process and the tooth profile forming process to harden the tooth surface. A method of manufacturing an external gear, comprising maintaining surface roughness of a tooth surface in a finished product. 2. A method for manufacturing an external gear in which an internal gear meshes with the internal gear inside the internal gear, comprising: a step of processing a material into a disk; and a hole required for forming a transmission mechanism in the disk. Forming a tooth profile on the outer periphery of the disk by hobbing; performing a heat treatment after the hole forming process and the tooth profile forming process to harden the tooth surface; and forming the tooth profile on the tooth profile after the heat treatment process. Finishing the hole while supporting a plurality of predetermined points as reference points, and maintaining the surface roughness of the tooth surface by the hobbing in the finished product. Production method. 3. A method of manufacturing an external gear in which an internal gear meshes with the internal gear inside the internal gear, comprising: a step of processing a material into a disk; and a hole required for forming a transmission mechanism in the disk. Opening the teeth, forming a tooth profile by hobbing on the outer periphery of the disk, and forming a tooth profile by hobbing, and then performing shot peening or barreling on the tooth surface in the hobbed state. An external gear having a surface roughness of the tooth surface subjected to the shot peening or the barrel processing in a finished product, comprising a step of subjecting the tooth surface to a surface hardening by performing a heat treatment after the step. Manufacturing method. 4. A method of manufacturing an external gear in which an internal gear meshes with the internal gear inside the internal gear, comprising: a step of processing a material into a disk; and a hole required for forming a transmission mechanism in the disk. Opening the teeth, forming a tooth profile by hobbing on the outer periphery of the disk, and forming a tooth profile by hobbing, and then performing shot peening or barreling on the tooth surface in the hobbed state. A step of performing a heat treatment after the step to surface harden the tooth surface; and a step of finishing the hole while supporting the plurality of predetermined positions on the tooth profile as reference points after the heat treatment step, A method for manufacturing an external gear, characterized in that surface roughness of a tooth surface subjected to shot peening or barrel processing is maintained in a finished product.