JP2003071632A - Manufacturing method for gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a simpler and more inexpensive gear than the prior art. SOLUTION: This manufacturing method comprises a constraining process of coaxially engaging a cylindrical original gear 21 having teeth in the inner surface with a constraint fixture 11 having an inner surface 111 of which clearance G of the inner surface facing to the cylindrical outer surface of the original gear 21 is axially different, and a deforming process of pressing the outer surface 211 of the original gear 21 onto the inner surface 111 of the constraint fixture 11 by heating and thermally expanding the original gear 21 and plastically deforming the original gear 21 so that the outer surface 211 of the original gear 21 has a shape corresponding to the shape of the inner surface 111 of the constraint fixture 11. In other words, the outer surface 211 of the original gear 21 is pressed onto the constraint fixture 11 by the thermal expansion in thermally treating the original gear 21, and the original gear 21 plastically deforms in response to different size of the clearance G between the constraint fixture 11 and the original gear 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear manufacturing method, and more particularly to a gear manufacturing method capable of favorably manufacturing a gear with crowning.

[0002]

2. Description of the Related Art Generally, a gear is provided with a crowning which is a bulge of teeth provided in the tooth trace direction. The crowning is provided in order to prevent uneven contact of the tooth contact of the gear pair due to play of each part, deflection under load, and the like. In general, one-sided contact often causes a decrease in tooth strength and an increase in gear noise.

As a method for manufacturing a gear with crowning formed thereon, a method of forming a crowning on a gear by mechanical processing such as grinding or shaving after manufacturing a gear without crowning is disclosed, for example, in Japanese Patent Application Laid-Open No. Hei 7-1999. −
As disclosed in Japanese Patent No. 51788, a method of manufacturing a gear with crowning by plastic working is performed.

[0004]

However, as for the gear (external gear) having teeth on the outer surface, the gear with crowning can be easily manufactured by the above-mentioned conventional technique, but Regarding gears provided with teeth (internal gears), it has not been possible to easily manufacture high-precision gears by the conventional method. Particularly, as a conventional technique for manufacturing an internal gear, Japanese Patent Application Laid-Open No. 8-31
As disclosed in Japanese Patent No. 8345, there is a method in which a gear without crowning is processed by a straightening die to form a gear with crowning, but it is expensive and it is difficult to say that it is simple.

Therefore, it is an object of the method of manufacturing a gear of the present invention to provide a method of manufacturing a gear that is simpler and lower in cost than the prior art.

[0006]

As a result of intensive studies for solving the above problems, the present inventors have focused their attention on the heat treatment of gears that is mostly performed in the gear manufacturing process, and at the same time, perform crowning at the same time. We succeeded in minimizing the increase in cost by forming the.

That is, according to the method of manufacturing a gear of the present invention, a cylindrical original gear having teeth formed on at least one of the inner surface and the outer surface is provided with a gap between the inner surface facing the cylindrical outer surface of the original gear and the axial direction. A restraining step of coaxially fitting to a restraining jig having different inner surfaces, and heating and thermally expanding the original gear to press the outer surface of the original gear against the inner surface of the restraining jig, A deforming step of plastically deforming the original gear such that the outer surface of the original gear has a shape corresponding to the shape of the inner surface of the restraining jig (claim 1).

That is, the outer surface of the original gear is pressed by the restraint jig due to thermal expansion during heat treatment of the original gear, and the original gear is moved in accordance with the difference in the gap between the restraint jig and the original gear in the cylindrical axis direction. It is used to cause plastic deformation. For example, when the present invention is applied to the internal gear, the internal teeth can be crowned by making the size of the gap larger at both end portions than at the central portion of the original gear in the cylindrical axis direction. (Claim 2).

In the method for manufacturing a gear according to the present invention which solves the above-mentioned problems, the amount of quenching to a cylindrical original gear having teeth on at least one of the inner surface and the outer surface is determined by the axial direction of the original gear. The method further comprises a deforming step of deforming the original gear according to the expansion amount of the original gear due to the amount of quenching (claim 3).

That is, quenching expansion due to a change in the crystal structure of the constituent material due to the heat treatment of the original gear (for example, in the case of a steel material, the heat treated portion becomes martensite due to the heat treatment condition and the volume expands as compared with that before the heat treatment). The original gear is deformed by quenching expansion by varying the quenching depth in the axial direction of the gear.

For example, in the case of applying the present invention to an internal gear, the internal teeth of the original gear are crowned in the deformation step by quenching as much as possible at both ends in the cylindrical axial direction of the gear. (Claim 4). This is because the amount of quenching expansion at both ends that have been deeply quenched increases, and the diameter of the gear at both ends increases.

In addition, before the deformation step, a constraint step of fitting a constraint jig to the outer surface of the original gear with almost no space is added, and in the deformation step, quenching is performed from the inner surface of the original gear to form a cylindrical shaft of the original gear. The inner teeth can also be crowned by deeper quenching toward the central portion in the direction (claim 5). When the outer surface of the original gear is pressed by the restraint jig fitted to the outer surface due to expansion due to heating and expansion due to quenching, the amount of heating and quenching increases toward the central part, so the gear undergoes greater plastic deformation. Is.

Further, according to the method of manufacturing a gear of the present invention for solving the above problems, a restraining jig is fitted to the outer surface of a cylindrical original gear having teeth on at least one of the inner surface and the outer surface with substantially no gap. The restraining step of combining and the amount of heat applied to the original gear are varied along the cylindrical axis direction of the original gear to press the outer surface of the original gear against the restraining jig in accordance with the varying thermal expansion amount. And a deformation step of plastically deforming the original gear (claim 6).

That is, the gear is plastically deformed by pressing the outer surface of the gear that has been thermally expanded by heating by the restraint jig that fits tightly on the outer surface of the gear. By varying the heating of the gear in the axial direction, the degree of thermal expansion of the gear is also varied, and the plastic deformation of the gear due to being pressed by the restraint jig can be controlled. For example, with respect to the internal gear, by increasing the heating amount toward the central portion of the original gear in the cylinder axis direction, the internal teeth can be crowned.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for manufacturing a gear according to the present invention will be described in detail with reference to Examples. Here, the gear to which the gear manufacturing method of the present invention can be applied is a cylindrical gear and is a known gear such as a spur gear or a helical gear, and the shape of the tooth is not particularly limited. Further, the positions where the teeth are formed may be provided not only on the outer surface or the inner surface, but also on both the inner and outer surfaces. The term "cylinder" in the present specification is a concept including not only a mathematically perfect cylinder but also a "cone or a shape obtained by cutting a part of a cone". Further, the drawings used for the description are schematic diagrams, and the scales and details of the configurations are not necessarily accurate. Further, even though the elements are different as a whole, the elements that are considered to have the same configurations for the individual elements are denoted by the same reference numerals for simplification of description.

(Embodiment 1) The method for manufacturing a gear of this embodiment has a restraining step of fitting a restraining jig to a cylindrical original gear and a deforming step of plastically deforming the original gear.

The positional relationship among the original gear 21, the restraint jig 11, and the heating means 31 after the restraining step and before the deforming step in this manufacturing method is shown in FIGS. 1 and 2A. Position where the original gear of the restraint jig 11 is fitted (inner surface 11
In 1), the outer surface 211 of the original gear 21 is coaxially fitted through a gap G whose size varies in the cylindrical axis direction of the original gear 21. As shown in FIG. 2, the size of the gap G gradually increases from the central portion of the original gear 21 in the cylindrical axial direction toward both ends. The size of the gap G is uniform in the cylinder circumferential direction of the original gear 21, that is, it is rotationally symmetrical with respect to the cylindrical axis of the original gear 21, unless otherwise required.

The fluctuation of the size of the gap G in the axial direction of the cylinder is adjusted by making the outer surface 211 of the original gear 21 into a drum shape. Therefore, the inner surface 111 of the restraint jig 11 is cylindrical. The size of the difference in the gap G (the difference between the smallest gap G and the largest gap G, the same applies hereinafter) depends on the size of the crowning required for the finally manufactured gear and the original amount in the deformation process described later. Although it is a value that changes depending on the heating temperature to the gear 21, the size of the difference in the gap G required to give the crowning (size of several μm) required for a general gear depends on the heating conditions and the type of material. The maximum value is about several mm, although it varies depending on the like.

The restraint jig 11 includes an inner surface 111 on which the original gear 21 is fitted through a gap G and a restraint jig 11 for the original gear 21.
It is a member into which the original gear 21 can be fitted via a positioning portion 112 that determines the position in the cylindrical axis direction inside. Therefore, with respect to the inner surface 111 of the restraint jig 11, the original gear 21
However, the shape of the outer surface of the restraint jig 11 is not particularly limited. In this embodiment, the inner surface 1
Similarly to 11, the outer surface of the restraint jig 11 is also cylindrical. Note that it is preferable to consider the durability of the restraint jig 11 because the inner surface 111 is pressed by the outer surface 211 of the original gear 21 at a high pressure in the deformation step described later.

As described above, the original gear 21 has a drum-shaped outer surface 211 that bulges toward the center of the cylindrical shaft. The shape of the outer surface 211 of the original gear 21 can be manufactured by mechanical processing such as correction with a die, grinding and shaving. Since the processing is performed on the outer surface of the cylinder, there are few processing problems as described in the section of the above-mentioned problem. The outer surface 211 of the original gear 21 can be drum-shaped by manufacturing the original gear 21 by plastic working such as powder molding or die forging. The outer surface 211 can be shaped like a drum by ironing the outer surface of the original gear 21 that has been molded by stress relaxation when the molded product is removed from the mold. This is particularly remarkable in powder molding, and the original gear 21 used in this embodiment is preferably a powder molded product. Further, teeth are formed on the inner surface of the original gear 21, and the shape of the teeth is substantially uniform in the axial direction of the cylinder and no crowning is applied.

The deforming step is a step of heating the inner surface of the original gear 21 to a predetermined temperature. Here, the predetermined temperature is equal to or higher than the temperature at which the outer surface 211 of the original gear 21 is pressed by the restraining jig 11 due to thermal expansion and the original gear 21 is plastically deformed. In addition, since it is preferable that the deformation step also serves as heat treatment for the tooth surface of the gear that is normally performed from the viewpoint of cost reduction, it is preferable to set the temperature at which the necessary heat treatment is performed. S, which is a material generally used for induction hardening gears
To explain using a gear using 45C as an example, the predetermined temperature is preferably about 800 to 900 ° C. Also, the heating time is a value that varies depending on the type of material of the original gear 21 and the type of heat treatment required, but during about 1.0 to 5.0 seconds, the temperature of the inner surface of the original gear 21 is a predetermined temperature. It is preferably selected to be retained above.

The heating means 31 is not particularly limited as long as it can heat the inner surface of the original gear 21 to a predetermined temperature.
High frequency induction heating is preferred. This is because the heating temperature, the heating time, and the heating depth can be easily adjusted by the value of the current flowing through the heating means, the frequency, and the like. In the present embodiment, it is preferable that the inner surface of the original gear 21 can be heated substantially uniformly, so that the heating means 31 is used as the original gear 21.
It is preferable to make the heating even by making the length larger than the length in the axial direction of the cylinder. Further, although not shown in the figure, the heat treatment of the original gear 21 can be effectively performed by providing a cooling means to heat the original gear 21 and then quenching it.

Due to the above-mentioned structure, the manufacturing method of this embodiment has the following effects. First, the manufactured original gear 21 is fitted between the outer surface 211 thereof and the inner surface 111 of the restraint jig 11 via a gap G (restraint step). The side surface of the original gear 21 comes into contact with the positioning portion 112 of the restraint jig 11, so that the original gear 21 inside the restraint jig 11 is in contact.
Is determined in the cylinder axial direction. Then, heating means 3
1, the original gear 21 is heated from the inner surface. At this time,
The original gear 21 thermally expands by being heated to a required depth from the inner surface of the original gear 21 at a predetermined temperature or higher. Thermal expansion mainly occurs in the cylinder circumferential direction of the original gear 21, and as a result, the outer diameter of the original gear 21 increases. Since the original gear 21 is heated substantially uniformly, it is considered that the expansion of the outer diameter is also substantially uniform in the cylindrical axis direction, but the gap between the outer surface 211 of the original gear 21 and the inner surface 111 of the restraint jig 11 is considered. Since G is not uniform in the cylinder axis direction, first, the outer surface 211 of the original gear 21 and the inner surface 11 of the restraint jig 11 near the center of the cylinder axis where the gap G is small.
1 and 1 contact.

The heating temperature, heating time, and heating range of the original gear 21 are set so that stress is applied in the direction in which the outer diameter of the original gear 21 increases even after the original gear 21 contacts the restraining jig 11. Due to the deformation due to the stress, the deformation of the original gear 21 reaches the plastic deformation area beyond the elastic deformation area, and even after the heating is finished, the original gear 21 remains permanently deformed and the target gear 91 is obtained. (FIG.2 (b)). This deformation is greatest in the vicinity of the central portion of the cylindrical shaft of the original gear 21 having the smallest gap G, and as a result, crowning is performed on the teeth provided on the inner surface of the original gear 21 (deforming process). Here, by providing a cooling step in which the raw gear 21 is rapidly cooled after being heated, martensite conversion progresses in a steel material or the like, and heat treatment can be performed on the tooth surface.

The deformation of the drum-shaped outer surface of the original gear 21 in FIG. 2A and the gear 91 in FIG.
The actual deformation is exaggerated for easy recognition. Also, in the following FIGS. 3, 4, 5, and 6, similarly, it is depicted by appropriately modifying the actual one.

(Modification 1 of Example 1) Instead of the restraint jig 11 used in the manufacturing method of Example 1, a restraint jig 12 shown in FIG. 3A is used. According to the restraint jig 12, the form of the original gear 21 is also the original gear 22 shown in FIG. The other elements are the same as those in the first embodiment.

The restraint jig 12 has an outer surface 221 of the original gear 22.
The protrusion 1211 is provided in the vicinity of the central portion of the cylindrical shaft of the original gear 22 on the inner surface 121 that contacts with. The protruding portion 1211 is provided continuously on the inner surface 121 of the restraint jig 12 in the circumferential direction of the original gear 22. The height at which the protrusion 1211 protrudes from the inner surface 121 of the restraint jig 12 (that is, the difference in the gap as described above) is finally the deformation required for the original gear 22 (the size of crowning) and the protrusion. It is determined according to the width of the original gear 2211 in the cylindrical axis direction. Protrusion 1
The height of 211 is about 0.1 to 5.0 mm. The width of the protrusion 1211 in the cylindrical axis direction of the original gear 22 is
The smaller the value, the greater the effect of deforming the original gear 21.

The original gear 22 has a substantially cylindrical outer surface 221 and is not in the shape of a drum like the original gear 21 of the first embodiment. In the sectional view of FIG.
Is almost linear.

As a result of the above construction, when the inner surface of the original gear 22 is heated in the deformation step, the original gear 22 is thermally expanded and the outer surface 221 of the original gear 22 is restrained by the restraining jig 12 as in the first embodiment. Abut the inner surface 121. At that time, the outer surface 221 of the original gear 22 first comes into contact with the protruding portion 1211 of the inner surface 121 of the restraint jig 12. Therefore, the original gear 2
2 is deformed more in the vicinity of abutment with the protruding portion 1211 near the center of the cylindrical shaft than in both ends, so that the original gear 2
The deformation of No. 2 has a portion which exceeds the elastic deformation region and reaches the plastic deformation region, and even after the heating is finished thereafter, the original gear 22 is left with permanent deformation and the internal gear is crowned, which is the target gear 92. Is obtained (FIG. 3 (b)).

(Modification 2 of Embodiment 1) Instead of the restraint jig 11 used in the manufacturing method of Embodiment 1, a restraint jig 13 shown in FIG. 4A is used. According to the restraint jig 13, the form of the original gear 21 is also the original gear 22 used in the modification 1 shown in FIG. The other elements are the same as those in the first embodiment.

The restraint jig 13 has an outer surface 221 of the original gear 22.
It has a drum-like shape protruding toward the center of the cylindrical shaft of the original gear 22 on the inner surface 131 that abuts against. As a result, the gap between the outer surface 221 of the original gear 22 and the inner surface 131 of the restraint jig 13 gradually increases from the central part of the cylindrical axis of the original gear 22 to both ends. The outer surface 221 of the original gear 22 and the inner surface 13 of the restraint jig 13
Although the difference between the clearance and 1 is finally determined according to the deformation (crowning size) required for the original gear 22, the maximum value is about 0.1 to 5.0 mm.

As a result of the above construction, when the inner surface of the original gear 22 is heated in the deformation step, the original gear 22 is thermally expanded and the outer surface 221 of the original gear 22 is restrained by the restraining jig 13 as in the first embodiment. The inner surface 131 of the. At that time, the original gear 22
Since the gap between the outer surface 221 of the gear and the inner surface 131 of the restraint jig 13 is not uniform in the cylinder axis direction, the outer surface 221 of the original gear 22 and the restraint jig 13 are first near the central portion of the cylinder shaft where the size of the gap is small. The inner surface 131 contacts.

Even after the original gear 22 comes into contact with the restraint jig 13 by heating, stress is applied in a direction in which its outer diameter increases.
Due to the deformation due to the stress, the deformation of the original gear 22 exceeds the elastic deformation range and reaches the plastic deformation range, and even after the heating is finished, the original gear 22 remains permanently deformed and the target gear 9
3 is obtained (FIG. 4 (b)). This deformation is the original gear 22
The largest around the center of the cylinder axis is
It will be crowning for the teeth provided on the inner surface of the.

(Modification 3 of Embodiment 1) In the present embodiment, the original gear 21 is an internal gear having teeth only on the inner surface, but in addition, it has teeth on the outer surface 211. May be. In that case, it is optional to have teeth on the inner surface.
When the outer surface 211 of the original gear 21 has teeth, the shape of the inner surface 111 of the restraint jig 11 can be made to match the shape (tooth shape) of the outer surface 211 of the original gear 21, or It can also be an envelope surface with which the tips of the teeth provided on the outer surface 211 are in contact.

When the original gear having teeth on the outer surface is also used, the size of the gap between the outer surface of the original gear and the inner surface of the restraint jig is changed according to the direction in which the original gear is to be deformed. A portion with a smaller gap undergoes greater plastic deformation than a portion with a larger gap.

(Embodiment 2) The method of manufacturing a gear according to this embodiment has a deformation step of plastically deforming an original gear.

The deformation process in this manufacturing method will be described with reference to FIG. The original gear 22 has teeth formed on its inner surface and has a cylindrical shape. The shape of the tooth is almost uniform in the axial direction of the cylinder and no crowning is applied, but the shape is not particularly limited. Further, the manufacturing method, the material, etc. are not particularly limited, but it is necessary to quench the material by heat treatment.

The deformation step is a step of quenching the inner surface 222 of the original gear 22. The quenching depth is deeper in both end portions of the original gear 22 in the cylinder axis direction than in the central portion. Inner surface 2
Quenching into 22 is performed by heating the inner surface 222 of the original gear 22 to a predetermined temperature. Further, it also includes a step of cooling thereafter if necessary. Here, the predetermined temperature is a temperature at which the inner surface 222 of the original gear 22 is hardened.
800 for S45C materials that are generally used for gears
It is about 900 ° C., and includes a step of quenching thereafter.
The heating time is a value that varies depending on the type of raw material of the original gear 22 and the type of heat treatment required, but it is necessary to keep the temperature of the inner surface of the original gear 22 at a predetermined temperature or higher for 1 to 5 seconds. Is preferably selected.

The heating means 32 is not particularly limited as long as it can heat the inner surface of the original gear 22 to a predetermined temperature.
High frequency induction heating is preferred. This is because the heating temperature, the heating time, and the heating depth can be easily adjusted by the value of the current flowing through the heating means, the frequency, and the like. Then, the heating means 32 heats the inner surface 222 of the original gear 22 deeper toward both end portions in the cylindrical axis direction, so that the both end portions are heated to a predetermined temperature or higher to a deeper portion. Heating means 3
When 2 is a high frequency induction heating device, the quenching depth can be adjusted by the distance between the heating means 32 composed of an induction coil and the inner surface 222. Specifically, the distance between the heating means 32 and the inner surface 222 at both ends is made closer than the distance at the central portion.

The manufacturing method of the present embodiment having the above-mentioned structure has the following effects. First, the manufactured original gear 22 is heated from its inner surface 222. The heating depth from the inner surface 222 heated to a predetermined temperature is deeper than the central portion because both ends of the original gear 22 in the cylindrical axis direction are deeper than the central portion. The crystal structure of the material in the part where the original gear 22 is hardened is changed. For example, in an iron-based material, the volume of the iron-based material expands more than before quenching due to a change in crystal structure accompanying martensite formation. Therefore, as a result of the expansion becoming larger toward both ends in the axial direction of the cylinder in which the deepening is deepened, the outer diameter and the inner diameter of the original gear 22 fluctuate in the axial direction of the cylinder, and the gear 94 with teeth crowned on the inner surface is provided. Becomes In addition, the inner surface 22 of the original gear 22
Since 2 (tooth surface) is quenched, the tooth surface can be strengthened at the same time.

(Modification of Embodiment 2) The manufacturing method of the gear according to this modification is different from the manufacturing method of Embodiment 2 in that before the deformation step, a restraining jig is applied to the cylindrical original gear. There is a restraint process for fitting.

FIG. 6A shows the positional relationship among the original gear 22, the restraint jig 11, and the heating means 33 after the restraining step and before the deforming step in this manufacturing method. The outer surface 221 of the original gear 22 is coaxially fitted to the position (inner surface 111) where the original gear of the restraint jig 11 is fitted with almost no gap.

The restraint jig 11 has an inner surface 111 to which the original gear 22 is fitted, and a positioning portion 112 that determines the position of the original gear 22 in the restraint jig 11 in the cylindrical axis direction.
It is a member that can fit two. Therefore, the restraint jig 11
The inner surface 111 of No. 1 depends on the shape of the outer surface 221 of the original gear 22, but the shape of the outer surface of the restraint jig 11 is not particularly limited. In this embodiment, like the inner surface 111, the outer surface of the restraint jig 11 is also cylindrical. The restraint jig 11
In the deformation process described later, the inner surface 111 is the original gear 2
It is preferable to consider the durability because the second outer surface 221 is pressed at a high pressure.

Further, the heating means 33 is used in place of the heating means 32 of the second embodiment. The heating means 33 is described in the second embodiment except that the shape thereof is about half the thickness of the original gear 22 in the cylindrical axis direction, and the arrangement position is near the central portion of the original gear 22 in the cylindrical axis direction. It is the same as the heating means 32. As a result, the vicinity of the central portion of the original gear 22 in the cylindrical axis direction can be heated deeper.

Due to the above-mentioned structure, the manufacturing method of this modification has the following effects. First, the manufactured original gear 22 is fitted between the outer surface 221 and the inner surface 111 of the restraint jig 11 (restraint step). Raw gear 22
The side surface comes into contact with the positioning portion 112 of the restraint jig 11, so that the position of the original gear 22 in the restraint jig 11 in the cylindrical axis direction is determined. Then, the heating means 33 heats the original gear 22 from the inner surface. At this time, by quenching from the inner surface 222 of the original gear 22 to a required depth, the original gear 22 expands. This expansion mainly occurs in the cylinder circumferential direction of the original gear 22, and as a result, the outer diameter of the original gear 22 increases. Since the raw gear 22 is deeply quenched near the central portion in the cylinder axial direction, it is considered that the expansion of the outer diameter also increases near the central portion in the cylindrical axial direction.
21 is fitted into the inner surface 111 of the restraint jig 11 with almost no clearance, and as a result, the expansion thereof is suppressed.
The deformation exceeds the elastic deformation range and reaches the plastic deformation range, and the target gear 95 is obtained with permanent deformation remaining in the original gear 22 (FIG. 6B). This deformation is greatest near the central portion of the cylindrical axis of the original gear 22, resulting in crowning of the teeth provided on the inner surface of the original gear 22.

(Modification 2 of Embodiment 2) In this embodiment,
The shape of the original gear 22 is an internal gear having teeth only on the inner surface, but it may be a shape having teeth on the outer surface 221. In that case, it is optional to have teeth on the inner surface. When the outer surface 221 of the original gear 22 has teeth, it is necessary to appropriately change the depth for quenching.

(Third Embodiment) The manufacturing method of this embodiment is substantially the same as the first modification of the second embodiment except that the heating of the inner surface of the original gear 22 in the deforming step is performed regardless of whether quenching is performed or not. It has a similar configuration.

Therefore, according to the manufacturing method of this embodiment, even if the material of the original gear is not hardened or the desired gear is not desired to be hardened, only the thermal expansion by heating is applied to the second embodiment. It is possible to obtain a gear with crowning similar to that of the first modification.

(Modification 1 of Example 3) In this example,
The shape of the original gear 22 is an internal gear having teeth only on the inner surface, but it may be a shape having teeth on the outer surface 221. In that case, it is optional to have teeth on the inner surface. When the outer surface 221 of the original gear 22 has teeth, it is necessary to appropriately change the heating depth.

(Test Example) A gear was manufactured by the method of Example 1 using the apparatus shown in FIG. 22mm wide,
Original gear 21 with internal teeth of helical teeth with an outer diameter of Φ135.0 mm
(Module 1.3, BBD: Between ball diameter Φ
102.1 mm) was formed by powder molding. Raw gear 2
As is clear from the value of the outer diameter with respect to the distance from the upper end surface of the work as shown in FIG. 7, No. 1 had a drum shape in which the diameter was larger in the central portion in the width direction. Then, from the result of the tooth profile shown in FIG. 8 and the value of BBD shown in FIG. 9,
The tooth traces of the teeth formed on the original gear 21 are substantially straight lines and are not crowned. This is because the original gear 21 is formed by powder molding, and thus the outer surface is drum-shaped by the ironing process when the original gear 21 is die-cut.

This internal gear 21 is fitted into the jig 11 having an inner diameter of 135.3 mm (restraint process), and the frequency is 40 kHz.
z, output 100 kW, after heating for 4.2 seconds, 9.
It cooled with the water-based coolant for 0 second (deformation process).

The resulting gear has an outer diameter shown in FIG.
As shown in FIG. 11, the drum shape is deformed from the initial drum shape to the opposite shape. Correspondingly, the center portion of the BBD shown in FIG. 11 also projects in the tooth thickness direction from both end portions. Further, from the tooth profile of the manufactured gear shown in FIG. 12, it can be seen that the central portion is more bulged than the both end portions, and crowning is provided.

This is because the drum-shaped bulge existing on the outer surface of the original gear 21 is pressed against the inner surface of the jig 11, and the original gear 21 is plastically deformed in the direction opposite to the drum-shaped bulge. It is considered that the internal teeth on the inner surface opposite to the outer surface were also plastically deformed.

[0054]

As described above, according to the gear manufacturing method of the present invention, a complicated process such as crowning can be applied to a gear by a simple operation similar to the conventional heat treatment. It is possible to provide a simple and low-cost manufacturing method of a gear.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating a manufacturing method of Example 1 and a test example.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a schematic diagram illustrating a manufacturing method according to a first modification of the first embodiment.

FIG. 4 is a schematic diagram illustrating a manufacturing method according to a second modification of the first embodiment.

FIG. 5 is a schematic view illustrating the manufacturing method of the second embodiment.

FIG. 6 is a schematic view illustrating a manufacturing method of a modified example 1 of the second embodiment and a third embodiment.

FIG. 7 is a diagram showing an outer diameter of an original gear in a test example.

FIG. 8 is a diagram showing a tooth trace profile of an original gear in a test example.

FIG. 9 is a diagram showing a BBD of an original gear in a test example.

FIG. 10 is a diagram showing an outer diameter of a manufactured gear in a test example.

FIG. 11 is a diagram showing a BBD of a manufactured gear in a test example.

FIG. 12 is a diagram showing a tooth trace profile of a manufactured gear in a test example.

[Explanation of symbols]

11, 12, 13 ... Restraining jigs 21, 22 ... Original gears 211, 221 ... Outer surface 22
2 ... Inner surface G ... Gap 31, 32, 33 ... Heating means 91, 92, 93, 94, 95 ... Gear

[Procedure amendment]

[Submission date] September 27, 2001 (2001.9.2)
7)

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 7

[Correction method] Change

[Correction content]

[Figure 7]

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toru Shimada             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Toshiya Yamaguchi             Tokyo Sintered Gold 438 Daisenji-cho, Kasugai City, Aichi Prefecture             Within the corporation F-term (reference) 4K042 AA18 BA13 BA14 DA01

Claims (7)

[Claims] 1. A restraining jig having a cylindrical original gear having teeth on at least one of an inner surface and an outer surface, the inner surface having a gap between the inner surface facing the cylindrical outer surface of the original gear and axially different from each other. A restraining step of coaxially fitting the tool, and heating and thermally expanding the original gear to press the outer surface of the original gear against the inner surface of the restraining jig so that the outer surface of the original gear is restrained. And a deformation step of plastically deforming the original gear so as to have a shape corresponding to the shape of the inner surface of the tool. 2. The method of manufacturing a gear according to claim 1, wherein the original gear has teeth on its inner surface, and the gap is larger at both end portions than at the central portion of the original gear in the cylindrical axis direction. 3. The original gear according to the amount of quenching by varying the amount of quenching in a cylindrical original gear having teeth on at least one of the inner surface and the outer surface in the cylinder axial direction of the original gear. A method of manufacturing a gear, comprising a deformation step of deforming the original gear according to the expansion amount of the gear. 4. The original gear is provided with teeth on the inner surface thereof, and the deforming step is a step of quenching the inner surface of the original gear as much as it goes to both ends of the original gear in the cylindrical axial direction. Item 5. A method for manufacturing a gear according to Item 3. 5. The original gear is provided with teeth on the inner surface, and further has a restraining step of fitting a restraining jig to the outer surface of the original gear with substantially no gap before the deforming step. In the deforming step, quenching is performed from the inner surface of the original gear,
4. The method for manufacturing a gear according to claim 3, which is a step of quenching deeper toward a central portion of the original gear in the cylinder axis direction. 6. A restraining step of fitting a restraining jig to the outer surface of a cylindrical original gear having teeth on at least one of an inner surface and an outer surface thereof, and a heating amount to the original gear. A deforming step of plastically deforming the original gear by pressing the outer surface of the original gear against the restraining jig in accordance with the amount of thermal expansion that is changed by changing the cylindrical gear in the cylindrical axis direction. Characteristic gear manufacturing method. 7. The gear according to claim 6, wherein the original gear is provided with teeth on the inner surface thereof, and the deforming step is a step of increasing the heating amount toward a central portion of the original gear in the cylindrical axis direction. Manufacturing method.