JPH09256058A - Method for manufacturing ring-shaped member - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To sufficiently reduce the grinding cost by ensuring sufficient accuracy of a ring-shaped member only by finish grinding after heat treatment. After quenching a turning ring-shaped member having an eccentricity ratio of inner and outer diameters of 0.015% or less and a dimensional tolerance ratio of 0.04% or less for low temperature temper straightening and 0.08% or less for high temperature temper straightening. The straightening tempering is performed within the range of the straightening tempering processing ratio of 0.2% to δ _max % determined by the following equation. δ _max = K ₁₀ + K ₂₀ T (however, K ₁₀ = 0.43 ± 0.03, K ₂₀
= (100.4 ± 0.2) α, T is the maximum temperature reached by the ring-shaped member (° C), α is the coefficient of linear expansion)

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for manufacturing a thin ring-shaped member that requires heat treatment.

[0002]

2. Description of the Related Art Conventionally, in a method of manufacturing a thin ring-shaped member which requires strength and dimensional accuracy, it has been general to perform grinding after performing necessary heat treatment. The reason why grinding is performed after the heat treatment is that deformation and dimensional change occur after the heat treatment even if the dimensional accuracy of the turned product before the heat treatment is improved. Therefore, it was essential to grind after heat treatment to improve dimensional accuracy.

Further, in order to improve the dimensional accuracy, Japanese Patent Laid-Open No. 5-3.
Proposal of straightening quenching by an outer diameter constrained quenching device as disclosed in Japanese Patent No. 3059 has been made. Here, the outer diameter of the turned product having an outer diameter immovableness of 15 to 50 μm is corrected at the time of quenching to complete a quenched product having a dimensional accuracy of 10 to 60 μm.

[0004]

However, in the former method for manufacturing a ring-shaped member, the amount of heat treatment deformation is large, and therefore, the grinding allowance after the heat treatment is excessively required, which increases the grinding cost. There was a problem.

In the latter method of straightening and quenching, surface roughening due to heavy working and the dimensional accuracy of the turned product are worse than the dimensional accuracy of the finished product. However, the product precision is not good. That is, these correction methods are also based on the premise that the grinding step is required after the heat treatment.

The present invention has been made in order to eliminate such inconvenience, and a manufacturing method of a ring-shaped member which can be manufactured by eliminating the grinding step after heat treatment or finishing barrel processing or finishing grinding if necessary. The purpose is to provide.

[0007]

In order to achieve the above object, after quenching a turned ring-shaped member having a dimensional tolerance of 0.04% or less for low temperature temper straightening and 0.08% or less for high temperature temper straightening. It is characterized in that the straightening tempering is carried out within a range of a straightening tempering working ratio of 0.2% to δ _max % determined by the following equation.

Δ _max = K ₁₀ + K ₂₀ T (provided that K ₁₀ = 0.43
± 0.03, K ₂₀ = (100.4 ± 0.2) α, T is the maximum temperature reached (° C) of the ring-shaped member, α is the linear expansion coefficient) The dimensional tolerance of the turned ring-shaped member is 0.04 when low-temperature tempering is straightened. %, And 0.08% or less during high temperature tempering straightening is because high temperature tempering straightening can more sufficiently remove stress than low temperature tempering straightening, and therefore high temperature tempering straightening is more effective for the same processing rate. This is because the straightening effect becomes higher, and therefore, it becomes possible to increase the upper limit of the dimensional tolerance ratio in the finished product after turning at a higher temperature.

However, if the upper limit of the dimensional tolerance ratio of the finished turning product is exceeded, even if the straightening tempering ratio is within the above range, it approaches free tempering, and the outer and inner diameter dimensional tolerance ratio of the heat treated finished product becomes It cannot be 0.06% or less, which is the range of good products.

Further, when the eccentricity ratio of the inner and outer diameters of the finished turning product exceeds 0.015%, even if the dimensional tolerance ratio of the outer diameter of the finished turning product is satisfied, the eccentricity of the inner diameter dimensional tolerance ratio after heat treatment is eccentric. The eccentricity is preferably 0.015% or less because it is wrinkled and deteriorates.

Further, if the straightening and quenching treatment in the austenite region is performed before the straightening and tempering, the dimensional tolerance ratio after the quenching can be made equivalent to that of the finished product, and the heat treatment is completed even in the low temperature straightening and tempering with a low straightening effect. The dimensional tolerance ratio of the inner and outer diameters of the product is improved. If the dimensional tolerance ratio of the inner and outer diameters of the finished heat-treated product can be set to 0.02% or less, the finishing process can be omitted by only removing the grinding step or improving the surface roughness by finishing barrel processing after the heat treatment. it can.

In the present invention, the dimensional tolerance ratio of the inner and outer diameters of the heat-treated product is 0.06% or less, and the eccentricity ratio of the inner and outer diameters is 0.015% or less.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory cross-sectional view for explaining a straightening and tempering apparatus used in a method for manufacturing a ring-shaped member according to a first embodiment of the present invention, and FIG. 2 is a diagram showing the maximum work temperature reached and the straightening and tempering rate. 3 is a graph showing the relationship.
Is a graph showing the relationship between the dimensional tolerance of the turning completed product, the dimensional tolerance of the heat-treated completed product, and the straightening tempering rate when the maximum temperature is 250 ° C. Fig. 4 shows the relationship when the maximum temperature is 500 ° C. FIG. 5 is a graph showing the relationship between the dimensional tolerance rate of the finished product, the dimensional tolerance rate of the heat-treated finished product, and the straightening tempering rate. FIG. It is a graph which shows a relationship.

First, for convenience of explanation, the straightening and tempering apparatus will be described with reference to FIG.
A cylindrical ceramic mold 22 having a magnetic permeability of 1.5 or less is mounted inside the device body 21. The work W, which is a ring-shaped member, is inserted into the inner diameter surface of the mold 22 with the outer diameter surface being constrained.

A high frequency induction heating coil 23 for heating the work W is disposed above and below the die 22 close to the die end surface. In this case, in order to bring the high-frequency induction heating coil 23 as close as possible to the work W which is the object to be heated, the mold 22 is made as thin as possible, and the coil shape is double wound so that induction heating can be performed uniformly from both ends of the work W. . The inner diameter of each coil 23 is slightly larger than the inner diameter of the mold 22.

A die temperature controller 24, which is in close contact with the upper end surface of the ceramic die 22 and adjusts the temperature of the die 22, is disposed outside the high frequency induction heating coil 23 in the radial direction. In the mold temperature controller 24 of this embodiment, a steel material (SC material) plate 25 is used as a heat transfer material that conducts heat well, and a temperature adjusting source 26 such as an electric heater or a heat medium liquid is used for this.
And a temperature sensor 27 such as a thermocouple (not shown) are built in, and the upper surface is formed in a donut plate shape covered with a heat insulating material 28, so that the flat surface of the steel material plate 25 is brought into close contact with the flat surface of the mold 22. It has become.

The mold temperature controller 24 has a mold temperature of 300.
Up to about ° C, the heating medium oil is circulated in the coil-shaped groove formed inside the regulator 24 or the heating method is performed by the electric heater embedded in the die temperature controller 24, and the die temperature is 30
When the temperature is higher than 0 ° C., the problem of heat deterioration of the heat carrier oil occurs, so it is preferable to use the heating method using an embedded electric heater. When cooling is required to keep the mold temperature constant, water or oil is circulated in the coil-shaped groove formed in the mold temperature adjuster 24 for cooling.
The temperature control is performed by switching the heating source and the cooling source based on the detection signal of the temperature sensor 27 embedded in the mold temperature controller 24.

Although the mold 22 is close to the high frequency induction heating coil 23, since it is made of a ceramic having a magnetic permeability of 1.5 or less, it is not heated by the magnetic lines of force of the high frequency induction heating coil 23 and does not cause a temperature rise. Therefore, the temperature of the mold 22 can be independently adjusted by the mold temperature controller 24.

On the central axis of the apparatus main body 21, a work press-fitting jig 30 and a main cylinder 31 for raising and lowering the work are inserted upward.
And a work supporting jig 32 and a sub-cylinder 33 for raising and lowering the work supporting jig 32.

A work W insertion port 36 and an insertion chute 37 are provided on the upper side surface of the apparatus main body 21, and a work take-out cylinder 38 and a processing-completed work take-out opening 39 and a take-out side are provided on the lower side surface of the apparatus main body 21. A chute 40 is provided.

Next, the operation of the straightening and tempering device 20 will be described. Initially, the work press-fitting jig 30 and the work supporting jig 32 are both in the upper and lower retracted positions.

First, the work supporting jig 32 is moved to the work insertion port 36 above the apparatus by the operation of the sub-cylinder 33 below the apparatus.
Up to Next, the work is inserted into the work support jig 32 from the insertion chute 37 through the work insertion opening 36.
The center of the inserted work W with respect to the mold 22 is automatically determined. When the work W is put on the work support jig 32, the work cylinder 30 is lowered by the operation of the main cylinder 31, The work W is sandwiched by the jigs 30 and 32. In this way, the work W is lowered while being held horizontally, passes through the high-frequency induction heating coil 23 above, and is press-fitted into the center of the die 22 from the upper taper portion of the inner diameter surface of the ceramic die 22. After press-fitting, the work press-fitting jig 30 rises, while the work supporting jig 32 descends and separates from the work W. In this state, the high frequency induction heating coil 23 is operated to work the work W.
High frequency induction heating. The maximum temperature reached by the workpiece W is 2
It is preferable that the induction heating time for holding the work W at 50 to 500 ° C. and the maximum reached temperature is 30 seconds or less. Even if the heating is performed for more than 30 seconds, the tempering effect and the deformation correcting ability are not improved, and thus it is wasted.

Here, in this embodiment, the range where the work maximum temperature reaches 250 to 350 ° C. is set as the low temperature straightening tempering temperature range, and the range of 400 to 500 ° C. is set as the high temperature straightening tempering temperature range.

When the heating is completed, the main cylinder 31 is operated to largely lower the work press-fitting jig 30 to push the work W below the mold 22, and the work W is received by the lifted work supporting jig 32 and received downward. To the position of the work take-out port 39. Then, the work take-out cylinder 38 is operated to operate the work W on the work support jig 32.
Shoot out to the work take-out port 39 and take-out chute 4
0 to complete one cycle of operation.

When it is desired to further increase the efficiency of high frequency induction heating, or when a high-frequency power source having a small capacity is used for the work, both the work press-fitting jig 30 and the work supporting jig 32 are used. It is advisable to insert a high magnetic permeability member between the contact surfaces with the work W and perform high-frequency induction heating while holding the work. In this method, the high-permeability member is first induction-heated to a high temperature, and the heat transfer effect is utilized to efficiently heat the work W.

Further, according to the straightening and tempering device 20,
In order to improve the surface roughness of the outer diameter surface of the work W, it is possible to subject the work W to ironing in the ceramic mold 22 during heating.

Next, a comparative experiment of straightening and tempering performed by using the straightening and tempering device 20 will be described. A steel turning ring-shaped member was used as the work W, and the steel type was SUJ2. This work W is heated to 840 ° C and heated to 3
After holding at that temperature for 0 minutes, quenching was performed with quenching oil at 60 ° C., and quenching and hardening were performed to obtain test pieces. The ceramic mold 22 for straightening and tempering has an inner diameter of 47.0.
The maximum reaching temperature of the work by the high frequency induction heating coil 23 was set to two kinds of 250 ° C (heating temperature for low temperature straightening and tempering) and 500 ° C (heating temperature for high temperature straightening and tempering). Further, the work size was intentionally set in order to obtain several kinds of processing rates (%) with respect to a constant die having an inner diameter of 47.000 mm. However, all heights are h = 7m
m, and the wall thickness was constant at 1.75 mm. Table 1 shows the outer diameter dimension and the inner diameter dimension of the test piece set as described above.

[0028]

[Table 1]

Table 2 is a list of test conditions and test results.

[0030]

[Table 2]

The column of dimensional tolerance ratio (%) in Table 2 shows two types of dimensional tolerance ratios of the inner and outer diameters of the work in the finished turning product and the dimensional tolerance ratios of the inner and outer diameter of the work in the finished heat treatment product. Both are calculated by the following equation. Here, in this embodiment, the dimensional tolerance ratio (%) of the inner and outer diameters of the workpiece in the finished turning product is 0.04% or less at the time of low temperature temper straightening at 250 ° C, and at the time of high temperature temper straightening at 500 ° C. 0.08% or less.

The column of processing rate (%) in Table 2 shows the straightening and tempering processing rate δ, which is calculated by the following equation. δ = {D / d (1 + α · T) −1} × 100 (1) where D: Work outside diameter (mm) before straightening and tempering d: Straightening die inner diameter (mm) α: Steel Linear expansion coefficient of type (for example, SUJ2 is 0.00
0012) T: Maximum work temperature (° C) By the way, the work straightening tempering rate of the mold straightening in this experiment is Is required. The lower limit of the processing rate is the minimum processing rate at which the work deformation can be corrected, and the mold dimension below this cannot correct the work. On the other hand, the upper limit of the above processing rate is the maximum processing rate at which the work can be pressed into the mold. If the die size exceeds this, the work (normal temperature) is compared with the inner diameter of the die.
Since the outer diameter of is too large, it cannot be press-fitted.

The upper limit of the straightening tempering rate δ is determined as follows. Now, if the inner diameter d of the straightening die is constant, the maximum outer diameter that can be press-fitted into the work before straightening and tempering is D
_Set to ₀ . On the other hand, the straightening and tempering processing ratio δ is expressed (1)
The formula is δ = {(D−d) / d + DαT / d} × 100 = K ₁ + K ₂ T ... (2) (where K ₁ = 100 × (D−d) / d, K ₂ = 100
Since Dα / d) can be transformed, D = D in the above K ₁ and K _2.
The curve defined by K ₁ = K ₁₀ and K ₂ = K ₂₀ obtained by substituting ₀ represents δ _max (%) at which press fitting is possible.

That is, the upper limit of the straightening tempering rate δ is regulated by δ _max = K ₁₀ + K ₂₀ T (3)

In the case of this embodiment, since the outer diameter of the work W was 47.20 mm, which was the limit of press-fitting, from Table 2, the work heating temperatures of 250 ° C. and 500 ° C.
In the case of, the upper limit δ of the straightening and tempering processing rate, that is, δ in (3)
_A trial calculation of _max (%) shows that the linear expansion coefficient α of steel type SUJ2
Is 0.000012, so at 250 ° C., δ _max = {47.20 / 47.000 (1 + 0.000012 × 250) −1} × 100 = 0.73% At 500 ° C., δ _max = {47 20 / 47.000 (1 + 0.000012 × 500) −1} × 100 = 1.03%.

Further, the above K ₁₀ and K ₂₀ are respectively K ₁₀ = 100 × (47.20−47.00) /47.00
≈0.43 K ₂₀ = 100 × 47.20 × α / 47.00≈100.4α. Note that K ₂₀ is 1.21 when α = 0.000012 is substituted.
× 10 ^-3 .

As described above, K ₁₀ and K ₂₀ are d = 47.
The results obtained experimentally in the case of 000 mm,
K ₁₀ = 0.43 ± 0.03 K ₂₀ = (100.4 ± 0.2) α can be set even if the roundness of the work after quenching is varied and the size of the work and the straightening die are changed. .

In the above equations (1) to (3) and the like, the difference between room temperature and 0 ° C. and the variation of α of the correction type due to the temperature are neglected, but they are all very small values. Considering the elastic deformability of the work, there is substantially no problem by approximating with the above equations.

FIG. 2 shows the test piece A1 in the column of the example of the present invention in Table 2.
-A3, D1-D3 and test pieces G1 and K1 in the columns of Comparative Examples
From the test results, the relationship between the maximum work temperature (horizontal axis) and the straightening tempering rate was taken and plotted. In the figure, a horizontal line having a straightening and tempering working rate of 0.2% represents the lower limit of the working rate, that is, the minimum working rate at which the work can be straightened. Further, the test pieces A1 to A3, D of the present invention example
1 to D3 and the test rate lines plotted for each of the test pieces G1 and K1 of the comparative example are shown, but the upper limit of the work rate, that is, the limit of the straightening and tempering work rate at which the work W can be pressed into the mold is shown. As described above, in this embodiment, the test pieces A3, D
3 (other than the plot of FIG. 2, other B3, C
3, G4, E3, F3 and K4 also correspond to this case. )
It was found that it is defined by the processing rate line in the case of. That is, in the equation (3), K ₁₀ = 0.43 ± 0.03, K ₂₀ = (100.
4 ± 0.2) Determined by the curve obtained within the range of α.

That is, the maximum work temperature reached is 250 to 500 °
In the range of C, it is possible to raise the working rate to a minimum of 0.20% and to the working rate upper limit δ determined as above at the highest limit. In FIG. 2, the shaded area in the center is the work W.
It is within the range of the maximum work temperature and the straightening tempering rate that can be press-fitted into the mold and satisfy the effects of the present invention described later. In Table 3, the maximum value (max) of the upper limit and the average value (me) of the straightening tempering rate δ in the present invention are shown.
an) and the minimum value (min) are straightening and tempering temperature is 250
The case of ° C and the case of 500 ° C are shown separately.

[0041]

[Table 3]

The column of eccentricity (%) in Table 2 shows two types of eccentricity of the inner and outer diameters of the workpiece in the finished turning product and the eccentricity of the inner and outer diameters of the work in the finished heat treatment products. It is calculated by the formula. Here, in this embodiment, the eccentricity (%) of the inner and outer diameters of the finished turning product is set to 0.015% or less so that the dimensional tolerance ratio of the outer diameter of the finished turning product satisfies The eccentricity is prevented from being deteriorated due to the eccentricity of the inner diameter dimension tolerance ratio of. The test pieces A2, B2, D in Table 2 are shown in FIG.
2, E2, O1 and O2 show the relationship between the eccentricity of the inner and outer diameters with respect to the outer diameter of the test piece and the difference in the dimensional tolerance ratio of the inner and outer diameters after heat treatment. As is clear from the figure, the eccentricity is 0.015
%, A2, B2, D2 and E2 having a dimensional tolerance ratio of the inner and outer diameters after completion of the heat treatment are “0”, while O1 and O2 having an eccentricity of more than 0.015% are after the heat treatment is completed. It can be seen that the difference in the dimensional tolerance ratio between the inner and outer diameters is as large as 0.1 and 0.2, respectively.

Then, referring to Table 2 and FIG. 3, 250
In low temperature straightening tempering of ° C, the dimensional tolerance ratio of inner and outer diameters (0.04% or less), straightening tempering ratio (0.2 to 0.73%) and eccentricity of the finished turning products The rate (0.015% or less) is all within the above range A
Regarding 1 to A3 and B1 to B3, the dimensional tolerance rate of the heat-treated finished product is 0.06% or less for both the inner and outer diameters, and the eccentricity is "0".
Therefore, the product can be commercialized only by finish grinding after heat treatment.

On the other hand, the dimensional tolerance ratio of the inner and outer diameters (0.04% or less) and the straightening and tempering processing ratio (0.2
~ 0.73%) and eccentricity of finished products (0.015%)
% (1% or less), G1 (dimension tolerance ratio and straightening tempering ratio in the finished product are out of range), G2, G
3, G4 (both of which the dimensional tolerance ratio of the finished turning product is out of range), G5 (the dimensional tolerance ratio of the finished turning product and the rate of straightening tempering are out of range), H1, H2, I1, I2 (all are straightened) If the tempering rate is out of the range), the dimensional tolerance rate of the heat-treated finished product becomes 0.08% or more for both the inner and outer diameters, which deteriorates.

On the other hand, referring to Table 2 and FIG. 4, 500 °
At the time of high temperature straightening and tempering of C, the dimensional tolerance ratio of the inner and outer diameters of the finished turning product (0.08% or less), the straightening tempering processing ratio (0.2 to 1.03%), and the eccentricity ratio of the finished turning product ( 0.015% or less) is all within the above range D1
For D3, E1 to E3, and F1 to F3, the dimensional tolerance ratio of the heat-treated finished product is 0.06% or less for both the inner and outer diameters, and the eccentricity is "0". Therefore, only final grinding after heat treatment is commercialized. In particular, for F1 to F3, which have a dimensional tolerance of 0.02% in the finished turning product, the dimensional tolerance in the finished heat treatment product is 0.02% for both the inner and outer diameters, and the eccentricity is "0". Therefore, the grinding process after the heat treatment can be eliminated or, if necessary, the product can be produced only by the finishing barrel.

On the other hand, the dimensional tolerance ratio of the inner and outer diameters (0.08% or less) and the straightening tempering ratio (0.2
〜1.03%) and eccentricity of finished products (0.015%)
% Or less), K1 and K5 (both of which are out of the range of the dimensional tolerance ratio and straightening tempering ratio of the finished turning product), K2, K3, K4 (all of which have the dimensional tolerance ratio of the finished turning product) Out of range), L1, L2, M1, M2, N1, N
Regarding 2 (both of which the rate of straightening and tempering is out of range),
The dimensional tolerance ratio of the heat-treated product exceeds 0.1% for both the inner and outer diameters and deteriorates. Also, for O1 and O2 that do not satisfy only the eccentricity of the finished product after turning, the dimensional tolerance ratio of the outer diameter of the finished product is corrected apparently because it is corrected from the outer diameter, but eccentricity wrinkles on the inner diameter. The eccentricity is getting worse.

Next, a method of manufacturing the ring-shaped member according to the second embodiment of the present invention will be described with reference to FIGS. FIG. 6 is an explanatory sectional view for explaining the straightening and quenching apparatus used in the method for manufacturing the ring-shaped member of this embodiment, and FIG. 7 is a graph showing the relationship between the straightening and quenching working rate and the dimensional tolerance rate after quenching. It is a figure.

In this embodiment, the work W after turning is completed
By performing the straightening quenching treatment in the austenite region described later in place of the quenching treatment of the first embodiment described above, the outer diameter dimensional tolerance ratio equivalent to the finished turning product is achieved after quenching, and thereby the straightening effect Even in the low temperature straightening and tempering product having a low temperature of 250 ° C., the dimensional tolerance ratio of the heat treatment completed product can be made 0.02% or less for both the inner and outer diameters. After such straightening and quenching, the same low temperature straightening and tempering treatment as in the first embodiment described above is performed.

First, for convenience of description, the straightening and hardening apparatus 50 will be described with reference to FIG.
A cylindrical outer diameter correction mold 52 is mounted inside the apparatus main body 51. The work W is arranged on the inner diameter surface of the mold 52. High-frequency heating coils 53 are arranged above and below the mold 52 so as to be close to the mold end surface. On the central axis of the apparatus main body 51, a cooling liquid injection nozzle 54 is arranged so as to be able to move up and down by a raising and lowering drive means such as a cylinder (not shown), and a work support jig 56 is provided below and upward and downward drive means such as a cylinder and the like. It is arranged so that it can be moved up and down. On the outer peripheral portion of the tip of the cooling liquid jet nozzle 54, a plurality of injection ports 55 are formed in the circumferential direction in which the cooling liquid is jetted to the inner diameter surface of the work W to complete the quenching when descending.

Next, the operation of the straightening and hardening device 50 will be described. Initially, the cooling liquid injection nozzle 54 and the work supporting jig 56 are both in the upper and lower retracted positions.

First, the work supporting jig 56 is lifted by the operation of the elevating and lowering means below the apparatus, and the work W is loaded on the work supporting jig 56. Next, the work supporting jig 56 is lowered to dispose the work W on the inner diameter surface of the outer diameter correction die 52, and in this state, the high frequency induction heating coil 53 is operated to perform high frequency induction heating of the work W to perform quenching deformation. Make a correction. The maximum temperature reached by the work W is 820 to 1200 ° C
The temperature is set according to the material. From the start of heating, the work W undergoes thermal expansion, its outer diameter surface is brought into close contact with the inner diameter surface of the outer diameter correcting die 52, and high frequency induction heating is terminated after the specified temperature is reached. Immediately after the induction heating, the elevating and lowering drive means above the apparatus is operated to lower the cooling liquid injection nozzle 54 to move the injection port 55.
Reaches the work W position, and the cooling liquid is sprayed from the injection port 55 onto the inner diameter surface of the work W to complete the straightening and quenching. Work W
Since the outer diameter is constrained in the austenite state, quenching deformation can be minimized, and 0.05-1.0%
It is possible to make the outer diameter dimension tolerance ratio after quenching 0.10% or less by the straightening quenching workability ratio (described later). By the way, the processed work W has a
Expansion of about 0.1 to 0.3% occurs.

As described above, in this embodiment, the work W is a perfect circular work W having no distortion or deformation by performing the deformation correction by the plastic working on the work W in the austenite structure of the steel.
To produce This is because in the austenite state, the hardness and tensile strength of steel decrease as is known in hot forging, while the elongation and drawing increase, which facilitates plastic working.

In the correction of deformation by plastic working, the correction ability changes depending on the correction hardening rate. The straightening quenching rate is a value obtained by dividing the difference between the outer diameter dimension D of the work W and the inner diameter dimension d of the mold by the outer diameter dimension D of the work W, and is represented by the following formula (4).

Straightening quenching processing rate = [(D−d) / D] × 100% (4) Here, each dimension in the measurement of the straightening hardening processing rate is at room temperature (20 to 30 ° C.). Shall be measured. Work W
The actual size during the work straightening increases due to thermal expansion, and the straightening quenching work ratio in the austenite state becomes higher than the above calculated value. Therefore, a value obtained by substituting the outer diameter dimension measured at room temperature into the equation (4) and adding a correction value represented by the following equation (5) was used as the outer diameter constraint rate. . However, T (unit: ° C) is a straightening temperature.

Correction value = (T-300) / 500% (5) FIG. 7 shows the relationship between the rate of straightening and quenching and the dimensional tolerance rate after quenching. As is apparent from the figure, the straightening effect (the outer diameter dimension tolerance ratio after quenching is 0.10% or less) can be obtained at a straightening and quenching work rate of 0.02% or more. Here, in this embodiment, the range of the straightening and quenching processing rate is 0.05 to
1.0%.

If the rate of straightening and hardening is less than 0.05%,
In some cases, the dimensional tolerance ratio after quenching becomes high and the work straightening effect cannot be expected, and when it is less than 0.02%, the dimensional tolerance ratio after quenching rapidly increases and the work straightening effect cannot be expected at all. Further, increasing the rate of straightening and quenching gives a kind of energy to the work W, which is a workpiece, and promotes the martensite transformation induced by the working to increase the rigidity, and as a result, the deformation straightening ability gradually increases. The dimensional tolerance ratio after quenching becomes unstable, and a larger pressing force is required. Therefore, depending on the size and thickness of the work W, the straightening work becomes difficult with a normal press quench equipment. Therefore, the upper limit of the straightening and quenching rate is 1.0%. However, if the work is performed with a high straightening and quenching work ratio, the surface to be work-corrected may become rough and affect the subsequent work, so it is preferably set to 0.7%.

Next, in the method of measuring the dimensional tolerance ratio after quenching
Regarding the outer diameter D of the workpiece W, the maximum
Large diameter D_maxAnd the minimum diameter D_minAnd the difference (D_max
-D _min) Is the roundness. And this roundness (m
m) is the average diameter D_meanQuenching the value divided by
It was defined as the dimensional tolerance ratio.

Here, in this embodiment, as a general rule, the work straightening is completed before the martensitic transformation starts. Ordinary quenching method, that is, when the deformation is corrected by using only the phenomenon of expansion due to martensitic transformation, distortion remains after the correction, and the subsequent cooling process, cleaning process, tempering process and subsequent finishing process, etc. Deformation may occur again when the strain is released.

This is because the strength is remarkably improved by transformation during the straightening process, plastic deformation cannot be completed only by the superplasticity phenomenon (trip phenomenon) that occurs during martensitic transformation, and the portion that is elastically deformed without plastic deformation and other This is because the plastically deformed portion is mixed and the internal strain remains after the correction.

Then, referring to Table 2, test pieces C1, C2, C having a dimensional tolerance rate of 0.02% for the inner and outer diameters of the finished turning product.
3 (invention example) and J1 and J2 (comparative example) were straightened and hardened at a straightening and hardening rate of 0.3% using the straightening and hardening device 50 described above, and the outer diameter dimension tolerance ratio after hardening was set in advance. After improving to within 0.10%, a low temperature straightening tempering process of 250 ° C. was performed by the straightening tempering apparatus 20 used in the first embodiment under each test condition shown in Table 2.

Referring to Table 2 and FIG. 3, the dimensional tolerance ratio of the inner and outer diameters of the completed turning product (0.04% or less), the straightening tempering ratio (0.2 to 0.73%) and the completed turning product. C in which the eccentricity (0.015% or less) is within the range of the present invention.
For 1, C2 and C3, the dimensional tolerance ratio of the heat-treated finished product is 0.02% or less for both the inner and outer diameters, and the eccentricity is "0". Therefore, even in the low temperature tempered product with a low straightening effect, It can be removed or commercialized with only the finishing barrel if necessary.

On the other hand, for J1 and J2 whose straightening and tempering processing ratios are out of the range of the present invention, the dimensional tolerance ratios of the heat-treated finished products are both 0.08%, which is bad. In this embodiment, the deformation correction is performed in the austenite state before the martensite transformation, but the deformation correction need not necessarily be completed before the martensite transformation. For example, the correction is often completed 3 seconds after the start of the deformation correction (especially for small workpieces), which does not mean that the deformation correction is completed before the martensitic transformation, but in principle the deformation correction is performed in the austenite region. Is. And desirably, it means that the deformation correction is completed before the martensitic transformation.

Therefore, the work straightening does not necessarily have to be completed before the martensitic transformation starts, and once the work straightening is performed in the austenite state, even if the martensite transformation subsequently starts, a large work straightening is not performed, Fine correction can be performed by utilizing the superplasticity phenomenon (trip phenomenon) that occurs during martensitic transformation, and a round work with less residual strain and less deformation can be obtained, which may be used.

[0064]

As is apparent from the above description, according to the present invention, by straightening and tempering after quenching a ring-shaped member having a size substantially equal to or slightly inferior to the dimensional accuracy of the final product,
It is possible to manufacture ring-shaped members with high dimensional accuracy after heat treatment is completed.Therefore, sufficient precision can be secured by eliminating the grinding process after heat treatment or by finishing barrel processing or finish grinding if necessary, and significantly reducing grinding costs. Reduction is possible.

[Brief description of drawings]

FIG. 1 is an explanatory cross-sectional view for explaining a straightening and tempering device used in a method for manufacturing a ring-shaped member according to a first embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the maximum work temperature and the straightening tempering rate.

FIG. 3 is a graph showing a relationship between a dimensional tolerance rate of a finished product, a dimensional tolerance rate of a finished heat-treated product, and a straightening tempering rate when the maximum temperature reaches 250 ° C.

FIG. 4 is a graph showing a relationship between a dimensional tolerance rate of a finished product, a dimensional tolerance rate of a heat-treated completed product, and a straightening tempering rate when the maximum temperature reached is 500 ° C.

FIG. 5 is a graph showing the relationship between the eccentricity of the inner and outer diameters and the difference in the dimensional tolerance of the inner and outer diameters with respect to the outer diameter of the test piece.

FIG. 6 is an explanatory cross-sectional view for explaining a straightening and quenching apparatus used in the method for manufacturing a ring-shaped member according to the second embodiment of the present invention.

FIG. 7 is a graph showing the relationship between the straightening and quenching work rate and the dimensional tolerance rate after quenching.

Claims (1)

[Claims] 1. The dimensional tolerance is 0.0 when tempered at low temperature.
4% or less, 0.08% or less at the time of high temperature temper straightening, after quenching the turning ring-shaped member, the straightening tempering rate is 0.2% ~
A method for producing a ring-shaped member, comprising straightening and tempering within a range of δ _max % determined by the following formula. δ _max = K ₁₀ + K ₂₀ T (however, K ₁₀ = 0.43 ± 0.03, K ₂₀
= (100.4 ± 0.2) α, T is the maximum temperature reached by the ring-shaped member (° C), α is the coefficient of linear expansion)