JP2002011541A - Toothed component of power transmission mechanism, and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toothed component and its manufacturing method in which the use of a material can be reduced, the working time can be shortened, and the cost of the component can be reduced. SOLUTION: Two components used in a power transmission mechanism of a car or the like have a female tooth profile and a male tooth profile, tooth flanks of the male and female tooth profiles are hardened by the cold forging and have the predetermined surface hardness. The tooth flanks are hardened by at least two or more cold forgings.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a toothed component of a power transmission mechanism in various technical fields, and a method of manufacturing such a toothed component.

[0002]

2. Description of the Related Art A typical example of a component having a male tooth shape is a spline. A spline is a toothed shaft used in machine tools, automobiles, aircraft, and the like. A typical example of a female tooth profile is a spline hole (a counterpart hole that fits a spline shaft). Such components include, for example, hub driven and hub turbine. Due to their properties, these components require special processing to obtain a special shape and high strength.

For example, a conventional hub-driven manufacturing method generally includes the following steps.

[0004] First, the material is cut (step 1), and then hot forging is performed to obtain a processed product (step 2). Thereafter, the processed product is quenched and tempered to obtain a predetermined hardness (Step 3).
Further, the processed product is entirely cut (step 4), and the processed product is broached to form a spline hole (step 5). Thereby, a spline hole is formed in the processed product.

[0005] A conventional method for manufacturing a hub turbine is as follows.
The following steps are common.

First, the material is cut (step 1), and then hot forging is performed to obtain a processed product (step 2). Thereafter, the processed product is annealed (Step 3), and the scale is removed from the surface of the processed product by shot blasting (Step 4).
Further, a lubricating film is formed (step 5). Then, the first cold forging (step 6) and the second cold forging (step 7) are performed. After the first cutting (Step 8), a hardened layer is formed on the surface of the processed product by carburizing and quenching (Step 9). Finally, a part of the carburized and quenched product is decarburized by performing a second cutting (step 10).

As described above, conventionally, the surface of the spline or the spline hole formed in the component is made to have a desired hardness by various heat treatments (hot forging, quenching, tempering, annealing, etc.). Was common.

[0008]

However, in the conventional method, since heat treatment is performed, the consumption of heating energy is large and the cost is high.

Further, in the case of machining a spline hole, broach cutting or cutting of a quenched product is performed. Therefore, the amount of material used is about 20% larger than that in the case of cold forging, and the cutting time is shorter than that in the case of cold forging. It required 2.5 to 3 times the forging.

[0010] Further, in order to obtain a desired surface hardness, tempering or annealing is necessary after quenching.

Further, when performing broach cutting, it is necessary to cut a high-hardness workpiece. Therefore, the service life of the broach was short. As a result, the surface roughness of the spline tooth surface was deteriorated by using the broach for a short time.

In view of the above-mentioned problems of the prior art, the present invention provides a toothed component of a power transmission mechanism that can reduce the amount of material used and the processing time and can greatly reduce the manufacturing cost. It is intended to provide a manufacturing method thereof.

[0013]

According to one aspect of the present invention, a toothed component of a power transmission mechanism has a tooth surface hardened by cold forging. Preferably,
The surface hardness differs between the root and the tooth tip on the tooth surface, the fibers flow smoothly, and the hardening depth changes smoothly. For example, it is preferable that the tooth bottom has a greater surface hardness than the tooth tip.

Preferably, the hardest surface of the tooth surface has a Rockwell hardness of 25 HRc or more. The smallest surface hardness of the tooth surface is Rockwell hardness 18HRc
It is as follows.

The Rockwell hardness of the part that has not been hardened by cold forging is 5 to 25 HRc.

In both the female and male teeth, when the hardened depth of the root is d ₁ and the hardened depth of the tooth tip is d ₀ ,
It is preferable that d ₁ and d ₀ have a relationship of d ₁ = 1.5 to 3.0 × d ₀ .

Another solution of the present invention is a method of manufacturing a toothed component of a power transmission mechanism, in which a tooth profile is formed on the component, at the same time or after that, the tooth surface is hardened by cold forging. A method for manufacturing a component part characterized by the following.

By performing cold forging at least twice, the surface hardness is changed at the tooth tip and the tooth bottom. It is preferable that the hardness of the hardest part of the tooth surface is equal to or higher than the Rockwell hardness of 25 HRc. In addition, for example, it is preferable that the tooth bottom has a greater surface hardness than the tooth tip.

Further, the hardening depth is smoothly changed between the tooth bottom and the tooth tip.

[0020]

In a preferred embodiment of the present invention, the surface hardness of the female and male teeth is increased by plastic working, particularly by cold forging. It is preferable to obtain the desired surface hardness of the female and male teeth by performing the cold forging twice or more (steps). It is particularly preferable to change the surface hardness and the curing depth at the tooth tip and the tooth bottom.

An example in which the present invention is applied to the manufacture of four types of components, namely, a hub driven and a hub turbine having a female tooth profile, a shaft main transformer and a gear having a male tooth profile will be described. In this case, the female tooth profile is a spline hole,
The male teeth are splines (toothed shafts).

A preferred example of the manufacturing process is performed in the following order.

A. Hub driven manufacturing process Using a cold forging machine (trade name "Parts Homer"), the coil material is sheared at predetermined lengths, and each piece is preformed by cold forging.

Step 2. Cold forging of the spline pilot hole is performed on the molded product. For example, a hole having a diameter of 15.5 mm is formed by cold forging. Then, it is slightly cut so as to form a hole having a diameter of 16.0 mm. Thereby, exact position accuracy and straightness accuracy of the hole are obtained.

Step 3. Perform lubrication coating on the processed product.

Step 4. The surface of the spline hole of the processed product is plastically formed (cold forged), and the desired tooth surface hardness (depth 0.2
A Rockwell hardness of 25-40 HRc) is obtained in mm.

Step 5. The outer periphery of the processed product is cut and finished.

B. Manufacturing process of hub turbine The coil material is sheared for each predetermined dimension by a cold forging machine (trade name “Parts Homer”), and then each piece is cold forged into a predetermined shape.

Step 2. Anneal the molded article. The hub turbine molded product is softened due to a large deformation rate.

Step 3. The first cold forging spline hole is formed inside the molded product, and the flange portion is preformed on the outside by cold forging.

Step 4. In addition to the first spline hole processing, a second cold forging spline hole processing is performed so as to increase the hole diameter. Further, finish forming of the cold forging of the flange portion is performed.

Step 5. Induction hardening of the molded product. Thereby, the end face (the thrust needle rolling face) is partially hardened.

Step 6. Perform finish cutting.

In the production of the hub driven, it is preferable to perform the plastic drilling (cold forging) twice (step) in the above-mentioned step 1.

In the manufacturing process of the hub turbine, it is preferable to perform the plastic drilling (cold forging) twice (stage) in the above-described process 1.

C. Example of manufacturing spline (toothed shaft) Using a cold forging machine (trade name "Parts Homer"), the coil material is sheared at predetermined lengths, and each piece is preformed by cold forging.

Step 2. A spline preliminary shape is formed on the molded product by cold forging. After that, it is slightly cut. Thereby, exact position accuracy and straightness accuracy of the spline male tooth profile are obtained.

Step 3. Perform lubrication coating on the processed product.

Step 4. The surface of the spline male tooth profile of the processed product is plastically formed (cold forged) to obtain a desired tooth surface hardness (Rockwell hardness 25 to 40 HRc at a depth of 0.2 mm).

Step 5. A predetermined part of the processed product is cut and finished.

D. Other Examples of Spline Manufacturing Step 1. The coil material is sheared for each predetermined dimension by a cold forging machine (trade name “Parts Homer”), and then each piece is cold forged into a predetermined shape.

Step 2. Anneal the molded article.

Step 3. The spline male teeth are machined inside the molded product by the first cold forging.

Step 4. In addition to the first processing of the spline male tooth profile, the second cold forging spline male tooth processing is performed so as to reduce the diameter.

Step 5. Induction hardening of the molded product. Thereby, the surface is partially cured.

Step 6. Perform finish cutting.

In the present invention, at least one surface of the male and female teeth is hardened by cold forging, and preferably, plastic processing is performed twice (steps) or more to make the surface of the tooth shape have a desired hardness. What you want to do.

In a preferred embodiment of the present invention, the optimum material is selected, the material hardness before cold forging is appropriately set, and the cold forging rate before tooth forming is improved. For example,
Suitable materials are S35C, SCM415H, SCr41
5H or the like, and a preferable material hardness before cold forging is HRB75.
~ 90.

In another preferred embodiment of the present invention, the surface hardness of the tooth bottom is not less than 25 HRc in Rockwell hardness and the surface hardness of the tooth tip is not less than that in both the female and male types. Smaller, and furthermore, the Rockwell hardness of the part that has not been hardened by cold forging is 5 to 25 HRc,
The curing depth changes smoothly between the root and the tooth tip. For example, the tooth tip of the hardening depth of the tooth surface as d _0, when the curing depth of the tooth bottom and the d _1, d ₁ and d ₀ is the d ₁ = 1.5~3.0 × d ₀ Have a relationship.

Further, the flow of the fiber is smoothened during the cold forging between the root and the tooth tip of the male and female teeth.

[0051]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
4 will be described.

In the first and second embodiments of the present invention, a spline hole is finished by cold forging as a typical example of the toothed component of the power transmission mechanism. In Embodiments 3 and 4 of the present invention, a spline is finished by cold forging as a typical example of a toothed component having a power transmission function.

First, referring to FIGS. 1 and 2, a series of processing steps of the toothed component of the power transmission mechanism will be described in detail.

Embodiment 1 FIGS. 1A to 1H show an example of a manufacturing process when the present invention is applied to manufacturing of a hub driven (one example of a component). (A)-(H) have shown the process of a series of cold forging.

The cold forging of (A) to (G) is preferably performed by a cold forging machine commercially available under the trade name of “Parts Homer”.

The spline plastic forming of (H) is preferably carried out by a cold forging machine commercially available under the trade name of “My Press”.

(A) shows a round bar-shaped raw material 20 before processing. The material of this round bar-shaped material 20 is SCM4
15H or SCr415H. The axial length of the material 20 and the outer diameter of the intermediate portion 25 are 30.3 mm and 3 mm, respectively.
8 ( ⁺ _0-0.1 ) mm.

In (B), the above-mentioned round bar-shaped material 20 is used.
Is subjected to plastic working to form a semi-finished product 24. The outer periphery of the lower surface 22 of the blank 24 has a radius R. A depression 28 is formed at the center on the lower surface 22 side.

The outer diameter of the intermediate portion 25 is 35 ( ⁺ _0-0.05 ) m
m. The axial length of the blank 24 is 27.5 (
⁺ _0.3-0 ) mm. The radius R of the roundness is 6 mm. The depth and inner diameter of the depression 28 are 2 mm and 14.5 m, respectively.
m. The outer diameter of the lower surface 22 is 26 mm.

(C) shows a state in which a slightly deeper hole 30 is formed at the recess 28 of the lower surface 22 by cold forging. The lower outer periphery of the blank 24 is formed into a portion 32 having a small diameter due to the drawing.

The inner diameter and depth of the hole 30 are respectively set to 14.
3 mm and 13.8 mm. The outer diameters of the intermediate portion 25 and the small diameter portion 32 are 35.18 mm and 29.
92 mm, and the length in the axial direction is 16.4 m each.
m, 14.15 mm, and the axial length of these connections is 2.65 mm.

In (D), a large diameter portion 36 is formed by cold forging the end face 34 of the semi-finished product 24.

The outer diameters of the large diameter portion 36, the middle diameter portion 25, and the small diameter portion 32 are 42 mm and 36.6, respectively.
The length in the axial direction is 10.5 mm, 5 mm, and 14.9 mm, respectively. The inner diameter and depth of the hole 30 are 14.3 mm and 13.
8 mm.

(E) shows a state in which the hole 30 is formed deeper by cold forging.

The outer diameters of the large diameter portion 36, the middle diameter portion 25, and the small diameter portion 32 are 42.2 mm, 3
It is 6.65 mm, 30.025 mm, and the axial lengths are 10.3 mm, 5 mm, and 14.9 mm, respectively. The inner diameter and depth of the hole 30 are 14.3 mm, respectively.
27 mm.

The holes 30 in the steps (C) to (E) shown above
Plastic forming (perforation) corresponds to a series of steps of the first plastic working (perforation). In these steps (C) to (E), the inner diameter of the hole 30 is kept constant and the portion 3 having a small diameter is used.
Cold forging is performed by keeping the outer diameter of No. 2 constant.

(F) shows a state in which the inner diameter of the hole 30 is slightly widened to form a hole 38 having a large diameter. At this time, the outer diameter of the thin portion 32 is kept constant. Hole 3
The 0 and larger holes 38 are connected via frusto-conical surfaces 44. A flange 40 is formed on the outer periphery of the upper end 34 of the blank 24 by swaging deformation. Further, a convex portion 42 is formed at the center.
The region R indicated by the arrow is in a state where the surface hardness has increased due to the upset deformation.

Such a step is a series of steps of the second plastic drilling. By setting the dimensions of the holes 30 and 38, it is possible to obtain a desired hardened layer depth.

The outer diameters of the flange 40, the large diameter portion 36, the intermediate portion 25, and the small diameter portion 32 are 52 ( ⁺¹⁾
_-0 ) mm, 42.4 mm, 36.65 mm, 30.02
5 mm, the axial length is 4.8 mm,
They are 4.1 mm, 5 mm, and 14.9 mm. The inner diameters of the holes 30 and 38 are 14.2 mm and 15.5 mm, respectively.
It is. The total depth including the hole 30, the truncated conical surface 44, and the hole 38 is 30.5 mm. The outer diameter of the projection 42 is 20
mm. This processing is performed with a load of 173 to 220 tons.

(G) shows a state in which the semi-finished product 24 is formed through the hole 46. The hole 46 is formed as described in (F) above.
Is formed by extending a hole 38 having a large diameter in FIG.

After the processing of (G), a small amount of the hole 46 is cut to obtain an accurate position and straightness of the hole 46.
The diameter of the hole 46 after the processing is 16 mm, which is used as a spline pilot hole.

Subsequently, a lubricating coating process is performed on the processed product, and thereafter, spline plastic forming of the hole 46 is performed.

(H) shows plastic forming of the hole 46 (cold forging).
Shows a state in which a spline hole 48 is formed in the axial direction of the processed product. The spline teeth 12 are formed on the inner periphery of the spline hole 48. Both ends in the axial direction of the spline teeth 12 are inclined. The inclined portions are each inclined at 30 ° with respect to the axial direction. The hardness of the tooth surface is a Rockwell hardness of 25 to 40 HRc at a measurement depth of 0.2 mm.

Thereafter, the outer peripheral portion of the processed product is cut and finished.

The outer diameters of the flange 40, the large diameter portion 36, the intermediate portion 25, and the small diameter portion 32 are respectively 52 (
^+1.5 _-0 ) mm (forging), 42.3 ( ^+0.3 _-0 ) mm (forging), 36 ( ⁺⁰ _-0.025 ) mm ｛forging 36.5 ( ^+0.3 _-0 )
mm｝, 30 mm, and their axial lengths are 4.1 (± 0.1) mm, 4 mm, 5 mm, 14.3 mm, respectively.
4 mm. The flange 40 and the thick portion 36
The combined axial length is 8.1mm ｛forged 8.4 (
^+0.4 _-0 ) mm｝. The large diameter D, the small diameter d, and the tooth height are 18 mm, 16 mm, and 1 mm, respectively.

Embodiment 2 FIG. 2 shows an example in which the present invention is applied to the manufacture of a hub turbine (another example of a component).

(A) to (D) show a series of cold forging steps. These processes can be performed by a cold forging machine marketed under the name of “Parts Homer”.

The processing steps (E) and (F) can be performed by a cold forging machine marketed under the trade name “My Press”.

(A) shows a semi-finished product 50 formed by shearing a round bar material and plastically processing one end thereof.

The outer diameter of the blank 50 is 35 mm, and the length in the axial direction is 36 mm.

(B) shows the end faces 52, 54 of the blank 50.
The state where the depressions 56 and 58 are respectively formed is shown. On the outer periphery of one end surface 54, a cylindrical outer peripheral portion 57 is provided.
And an inclined surface 59 that connects to the main body.

The inner diameter and the depth of the depressions 56 and 58 are 19 mm and 18 mm, respectively.

The forging process shown in FIGS.
Performed with a load of 80 tons.

(C) shows the depressions 56 and 58 shown in (B).
Is forged to form two holes 60 and 62 at both ends. A narrow portion 64 is formed on the outer periphery on the end face 54 side by a diaphragm.

The forging shown in (C) is performed with a load of 85 to 100 tons. The inner diameters of the two holes 60 and 62 are 18 mm and 17.5 mm, respectively, and the depths of the holes are 6.3 mm and 9.5 mm, respectively. The outer diameter of the thin portion 64 is 27 mm.

The drilling step shown in (C) corresponds to the first plastic drilling. In the first plastic drilling, the outer diameter of the outer peripheral portion 57 is kept constant.

Thus, the first surface hardening of the hole 60 is performed by the cold forging shown in FIG.

(D) shows the semi-finished product 50 shown in (C).
Is shown in a state of being turned upside down. By the cold forging, a thick portion 68 is formed on the outer periphery of the intermediate portion in the axial direction.

The cold forging shown in FIG.
It is performed with a load of 60 tons. The inner diameters of the two holes 60 and 62 are both 17.5 mm. The outer diameters of the thin portion 64 at one end, the thick portion 68 at the middle, and the thin portion 57 at the other end are 27.5 mm, 56 mm, 35.
5 mm, the length in the axial direction is 6.0 mm,
9.5 mm and 9.8 mm.

The step shown in (D) corresponds to the diameter expansion by the second plastic drilling. Thereby, a desired surface hardness is obtained.

After the step (D), the two holes 60 and 62 are made to penetrate. The load at this time is 20 to 30 tons.

(E) shows a state in which a part 68 is formed as a flange 72 by cold forging a large diameter part 68. The flange 72 protrudes outward,
It projects a little further down. Spline teeth 76 are formed on the inner surface of the through hole 74 from near the center in the axial direction toward the end surface 54.

The outer diameters of the flange 72, the thick portion 68, the intermediate portion 57, and the end surface 52 are 69 ( ⁺ _2-0 ) m, respectively.
m, 64 ( ⁺ _0.3-0 ) mm, 36 ( ⁺ _0.2-0 ) mm, 32.
5 mm. The inner diameter of the lower end face 73 is 60 mm. The axial length of the small diameter portion 64 is 6.3 mm. The large diameter D and small diameter d of the spline hole are 18 mm and 16 mm, respectively.
mm.

(F) shows the semi-finished product 50 shown in (E).
Shows a state in which the upper and lower parts have been processed. The thick part 68 and the flange 72 are thinned in the axial direction by cold forging. An oil groove 78 is formed in the end face 52. A hole 80 having a small diameter is formed in the inner periphery of the hole 74 on the end face 52 side by cold forging.

The outer diameters of the thin portion 64, the thick portion 68, the flange 72, and the outer peripheral portion 57 are 27 mm, respectively.
64.5 ( ⁺ _0.3-0 ) mm, 72 ( ⁺ _1-0 ) mm, 36.2
A ^{(+0 .2} _-0) mm. The maximum inner diameter of the small diameter hole 80 is 1
5 mm. The large diameter D and the small diameter d of the spline hole are 20 mm and 19 mm, respectively.

FIGS. 3A and 3B and FIG. 8 are enlarged views of a main part showing a modification of the tip end portion of the spline hole. FIG.
(A) and (B) and FIG. 8 correspond to (F) in FIG.

In FIG. 3A, the cylindrical surface formed by the root circle of the spline teeth 76 has its upper part reduced in diameter at an angle of 45 ° with respect to the axis, and the truncated conical surface is formed there. Has formed. The upper end of the frusto-conical surface touches a small diameter hole 80 beyond the tip circle, where a circle having a diameter of 16 mm is formed. The large diameter D of the spline teeth 76 is 20 mm, and the small diameter d is 18 mm. The boundary between the truncated conical surface and the cylindrical surface formed by the tooth root circle has a radius of R (0.5 mm). The inner diameter of the small diameter hole 80 is a maximum of 15.5 mm, and the thickness in the axial direction is 4.5 mm.

In FIG. 3B, the cylindrical surface formed by the root circle of the spline teeth 76 is reduced in diameter at an angle of 45 ° with respect to the axis at the upper part thereof, and the truncated conical surface is formed there. Has formed. The upper end of the frusto-conical surface slightly extends beyond the addendum circle and from there again forms a small-diameter cylindrical surface. The upper end of the small diameter cylindrical surface is connected to the small diameter portion via a small frusto-conical surface.

The large diameter D of the spline teeth 76 is 20 mm, and the small diameter d is 18 mm. The diameter of the thin cylindrical surface is 1
7.9 mm. The boundary between the truncated conical surface and the cylindrical surface formed by the root circle has a radius of R (0.5 mm). The boundary between the truncated conical surface and the cylindrical surface having a small diameter is a radius R
(0.5 mm). The inner diameter of the small diameter portion is up to 15.5 mm, and the thickness in the axial direction is 3 mm.

In FIG. 8, the large diameter and the small diameter of the spline teeth 76 are slightly larger at the tip of the spline hole, and the bulge 81 is formed. Swelling 8
1 is formed by forging using the center pin 83. The hole 80 having a small diameter is forged so as to come into contact with a portion of the center pin 83 having a diameter d ₀ .

FIG. 4A shows the result of measuring the surface hardness of the spline hole of the hub driven manufactured according to the preferred embodiment of the present invention. The horizontal axis shows the measured depth when the surface of the spline hole is set to 0, and the vertical axis shows Rockwell hardness (HRc) and Vickers hardness (H) at various depths.
v). In FIG. 4A, line a, line b
Line and c line are the first plastic drilling (cold forging) respectively
The figure shows the surface hardness of the spline hole at the time of completion and completion of the second plastic hole.

To explain these in detail, the line a (open circle) in FIG. 4A has a diameter of 14.3 m after the first forging.
m indicates the surface hardness of the spline hole, and line b (large black circle) indicates the surface hardness of the spline hole having a diameter of 15.5 mm in the second forging. FIG. 4B is a conceptual diagram of the measurement positions of the a-line and the b-line. The c-line (black square) indicates the surface hardness of the spline teeth 12 of the finished product that has been finished. A conceptual diagram of the measurement position at this time is shown in FIG. The arrow K in FIG. 4C indicates the surface of the spline hole teeth, and the arrow L indicates the measurement location of the finished product.

In the example of the three-stage plastic working, the hole diameter is 14.3 mm for a and 15.5 mm for b.
In the case of c, the hole diameter is 16 mm, and the diameter gradually increases.

Referring to FIG. 4A, the hardness of line b is generally higher than the hardness of line a. From this, the diameter 1
It can be seen that the hardness of the hole has increased due to the plastic deformation that expands the diameter from 4.3 mm to a diameter of 15.5 mm. Further, even after finishing the spline holes, as can be seen from the c-line, the tooth surface hardness up to a depth of 0.6 mm maintains Vickers hardness 270 Hv or more and Rockwell hardness HRc 25 or more. .

FIGS. 5A and 5B show an example of the pattern of the depth of the hardened layer in the example of the three-step processing shown in FIG. FIG.
5A shows an example of the pattern of the depth of the hardened layer of the spline hole 159, and FIG. 5B shows an example of the pattern of the depth of the hardened layer of the spline shaft 169.

In FIG. 5 (A), cold forging was performed for 3
The hardness and the depth of the hardened surface of the spline hole 150 are changed by performing the rotation. For example, the tooth bottom 151 has a hardened surface that is harder and deeper than the tooth tip 152. In a preferred numerical example, the tip 152
The cure depth and d _0, when the curing depth of the tooth base 151 as d _1, is as follows.

D ₁ = 1.5-3.0 × d ₀ d ₀ and d ₁ are set to appropriate values by selecting the material and the number of steps of cold forging.

The depth of the hardened layer changes smoothly from deep to shallow from the tooth bottom 151 to the tooth tip 152. Moreover, although not shown in the drawing, the flow of the fiber between them is smooth.

In FIG. 5A, reference numeral 153 denotes a vertical symmetry line of the spline hole, reference numeral 154 denotes a left and right symmetry line of the spline hole, and reference numeral 155 denotes an intersection thereof, that is, a center line of the spline hole. And 159 is a hole.
However, the shape of the spline hole is exaggerated and differs from the actual one.

Also in FIG. 5 (B), the cold forging was
By performing the rotation, the hardness and depth of the hardened surface of the spline shaft 169 are changed. For example, the tooth bottom 161 has a hardened surface with a higher hardness and a greater depth than the tooth tip 162. In a preferred numerical example, the tip 162
The cure depth and d _0, when the curing depth of the tooth base 161 as d _1, is as follows.

D ₁ = 1.5 to 3.0 × d ₀ d ₀ and d ₁ are set to appropriate values by selecting the material and the number of steps of cold forging.

The depth of the hardened layer smoothly changes from deep to shallow from the tooth bottom 161 to the tooth tip 162. Moreover, although not shown in the drawing, the flow of the fiber between them is smooth.

In FIG. 5B, 163 is a line of symmetry above and below the spline axis, 164 is a line of symmetry of the right and left of the spline axis, and 165 is their intersection, that is, the center line of the spline axis. And 169 is an axis.
However, the shape of the spline shaft is exaggerated and differs from the actual one.

Next, an example of a spline (toothed shaft) manufactured by the method of the present invention will be described with reference to FIGS.

Embodiment 3 FIGS. 6 to 9 show an example in which the present invention is applied to the manufacture of a shaft main transformer (another alternative example of a component).

FIG. 6 shows the entirety of the shaft main transformer 90, FIG. 7 shows a cross section taken along the line aa of FIG. 6, and FIG.
The portion E of FIG.

At both ends in the axial direction of the shaft main transformer 90, thin portions 91 and 92 having holes opened outward in the axial direction are formed. A thin portion 91,
A square spline 93 and an involute serration 94 are connected to the inside of the shaft 92 in the axial direction.

The square spline 93 and the involute serration 94 are connected via a cylindrical portion 98 provided with two thick portions 95 and 96 having a large diameter.

The large-diameter portion 96 has a recess 97 in which the diameter of the outer peripheral surface is partially reduced.

The shaft main transformer 90 is formed from a coil material by cold forging. In this case, the surface of the spline tooth profile is hardened by plastic deformation accompanied by diameter reduction. The shaft main transformer 90 preferably has no harmful defects such as scratches, cracks, dents, fog and burrs. Suitable surface hardness after cold forging is, for example, HRB7
3 to 98.

An example of the dimensions is as follows.
3, the large diameter D1, the small diameter d1, and the number of teeth are respectively 20.25.
± 0.1mm, is a 17 ^-0.29 _-0.47 mm, 6. The large diameter D2, the small diameter d2, the module and the number of teeth of the involute serration 94 are 19.8 ⁰ _-0.3 mm and 17.
6 ⁰ _-0.3 mm, 1.0 mm and 19. The width of the depression 97 is 0.5 to 1 mm, and the depth is 0.1 to 0.3 mm.

Embodiment 4 FIGS. 10 to 11 show an example in which the present invention is applied to the manufacture of a gear 100 (still another example of a component).

FIG. 10 shows the entire gear 100, and FIG.
Indicates an enlarged region B in FIG.

A gear 101 is formed at one end of the gear 100, and a thick portion 102 is connected to the inside of the gear 100 in the axial direction.

The other end of the gear 100 has a small diameter portion 103.
Is formed, and the involute serration 104 is connected to the inner side in the axial direction.

The large-diameter portion 102 and the involute serration 104 are connected via a cylindrical portion 105.

The gear 100 is formed by cold forging from a coil material. In this case, the tooth-shaped surface of the gear 101 is hardened by plastic deformation accompanied by diameter reduction. Suitable surface hardness is HR 25-40.

It is preferable that the tooth surface of the gear is free from scratches and irregularities.

As an example of the dimensions, the size of the gear 101 is large.
The diameter, small diameter and number of teeth are each 14.2 ⁰ _-0.08mm, 1
0.6 mm and 15. Involute serration
The large diameter, small diameter, module and number of teeth of 104 are 1
2^-0.15 _-0.25mm, 10 mm, 1.00 mm, 11
You.

As shown in FIG. 11, the axial length L and the radial length l of the sag formed on the tooth surface of the gear 101 are preferably 1.5 mm or less and 0.5 mm or less, respectively.

[0131]

According to the present invention, by employing cold forging, energy consumption can be greatly reduced as compared with hot forging.

Further, according to the present invention, when forming female teeth, it is not necessary to perform broach cutting or cutting of hardened products, so that the amount of material used is reduced by 20 to 30% as compared with the conventional case. can do.

Further, since the tooth profile can be processed only by cold forging, the cutting time can be reduced by about 45 to 55% as compared with the case where hot forging is performed.

Further, since a desired tooth surface hardness is obtained by cold forging, a quenching step, a tempering step or a carburizing and quenching step can be omitted.

[Brief description of the drawings]

1 (A) to 1 (H) are views showing a series of manufacturing steps for manufacturing a hub driven (one example of a component) by the method of the present invention.

FIGS. 2A to 2F are views showing a series of manufacturing steps for manufacturing a hub turbine (another example of a component) by the method of the present invention.

FIGS. 3A and 3B respectively correspond to FIG. 2F and are enlarged views of main parts of two modified examples.

FIG. 4 (A) is a graph showing the results of measuring the hardness of a splined hole manufactured by the method of the present invention for a semi-finished product (shown by white circles and black circles) and a finished product (shown by black squares). (B) is a conceptual diagram showing the hardness measurement positions of semi-finished products (white circles and black circles). (C) is a conceptual diagram showing a hardness measurement position of a finished product (black square).

FIG. 5A is an explanatory diagram showing one pattern of a curing depth on the surface of a spline hole. (B) is an explanatory view showing one pattern of the curing depth on the surface of the spline shaft.

FIG. 6 shows a shaft main transformer (another alternative example of a component) manufactured by the method of the present invention.

FIG. 7 is a sectional view taken along the line aa in FIG. 6;

FIG. 8 is a view corresponding to FIG. 2 (F), illustrating a main part of a modified example and a processing method thereof in an enlarged manner.

FIG. 9 is an enlarged view of a portion E in FIG. 6;

FIG. 10 shows a gear (still another example of a component) manufactured by the method of the present invention.

FIG. 11 is an enlarged view of a region B in FIG. 10;

[Explanation of symbols]

 Reference Signs List 10 hub driven 12 spline teeth 20 material 22, 34, 52, 54 end face 24, 50 semi-finished product 25, 57 intermediate part 28, 56, 58, 97 hollow 30, 60, 62, 159 hole 32, 64, 91, 92, 103 Thin part with diameter 36, 68, 95, 96, 102 Thick part with diameter 40, 72 Flange 42 Convex part 44 Truncated conical surface 46, 74 Through hole 48, 150 Spline hole 76 Spline tooth 90 Shaft main transformer 93, 101 Square splines 94, 104 Involute serrations 98, 105 Cylindrical part 100 Gears 151, 161 Teeth bottoms 152, 162 Tooth tips 153, 163 Vertical symmetry lines 154, 164 Left and right symmetry lines 155, 165 Center line 156, 166 Tooth surface 160 Splines Shaft 169 Shaft D1, D2 Large diameter d1, 2 small

Claims (12)

[Claims] 1. A toothed component of a power transmission mechanism, wherein a tooth surface is hardened by cold forging, a surface hardness is different between a tooth bottom and a tooth tip, and fibers are formed on the tooth surface. A component characterized by flowing smoothly along. 2. The component according to claim 1, wherein the hardest surface of the tooth surface has a Rockwell hardness of 25 HRc or more. 3. The Rockwell hardness of a portion not hardened by cold forging is 5 to 25 HRc.
The component according to any one of the above. 4. When the hardening depth of the tooth bottom is d ₁ and the hardening depth of the tooth tip is d ₀ , d ₁ and d ₀ are d ₁ = 1.5 to 3.0 × d ₀ . The component according to any one of claims 1 to 3, wherein the component has a relationship. 5. The method according to claim 1, wherein the hardening depth changes smoothly between the tooth bottom and the tooth tip on the tooth surface.
5. The component according to any one of items 4 to 4. 6. The component according to claim 1, wherein the surface hardness of the tooth tip is smaller than the surface hardness of the tooth bottom. 7. A method of manufacturing a toothed component of a power transmission mechanism, wherein a tooth profile is formed on the component, and simultaneously or subsequently, the tooth flank of the tooth profile is hardened by cold forging. Manufacturing method of a component part. 8. The hardness of the hardest part of the tooth flank is increased by a Rockwell hardness of 2 by performing cold forging at least twice.
The method for manufacturing a component according to claim 7, wherein the component is set to 5HRc or more. 9. The method according to claim 7, wherein the hardening depth is smoothly changed between the root and the tooth tip on the tooth surface.
A method for manufacturing a component according to any one of claims 8 to 13. 10. When the hardening depth of the tooth bottom is d ₁ and the hardening depth of the tooth tip is d ₀ , d ₁ and d ₀ are d ₁ = 1.5 to 3.0 × d ₀ . The method for manufacturing a component according to claim 7, wherein the component has a relationship. 11. The method according to claim 7, wherein the flow of the fiber is smooth along the tooth surface during cold forging between the root and the tooth tip. Manufacturing method of component parts. 12. The method according to claim 7, having a male tooth shape, wherein the surface hardness of the tooth bottom is smaller than the surface hardness of the tooth tip.
12. The method for manufacturing a component according to any one of items 11 to 11.