JP4559933B2 - Machining tool and its manufacturing method - Google Patents

Description

  The present invention relates to a processing tool used when, for example, forging a workpiece, and a manufacturing method thereof.

Conventionally, tool steel, bearing steel, high-speed steel, or the like is used as a material for a processing tool for performing strong processing such as a forging die or a die. This type of processing tool is desired to have strength to withstand high surface pressure during processing and to have high wear resistance. In order to improve the strength of the processing tool and increase the wear resistance, nitriding treatment or ion implantation may be performed after the heat treatment, or a wear-resistant film may be formed. For example, TiN, TiCN, TiAlN, etc. are known as anti-wear coatings. (For example, see Patent Document 1 below)
Japanese Patent Laid-Open No. 11-158606

  As described above, conventionally, nitriding treatment, ion implantation, and the like have been proposed as measures for improving the service life of processing tools, but these are not always effective for improving the service life due to the shallow hardening depth. In addition, when a wear-resistant coating such as TiN, TiCN, or TiAlN is applied, there is a problem in the adhesion of the coating. In addition, there is a problem that the cost is high because a special film processing apparatus is required and the film processing takes time.

  By the way, it is known that about 15 to 35% of retained austenite exists when quenching high alloy steel and high speed steel. The presence of residual austenite reduces the static strength but improves the dynamic strength. For example, in bearing steel, when repeated stress is applied to the surface of a material due to the rolling motion of the bearing, the retained austenite on the surface portion undergoes a work-induced transformation and becomes martensite. It is said that this martensite increases the hardness and improves the rolling fatigue life. The increase in hardness tends to increase as the amount of retained austenite increases, but the fatigue life decreases if the amount of retained austenite increases too much.

  As a means of increasing the retained austenite, it is conceivable to devise the chemical components and heat treatment of the material, but both require special chemical components and heat treatment, which increases the cost or requires special technology This is not a practical method.

  Accordingly, an object of the present invention is to provide a processing tool that can suppress an increase in cost, obtain a deep curing depth, and improve the life, and a manufacturing method thereof.

  The processing tool of the present invention has a heat-treated tool main body made of high carbon steel such as tool steel, bearing steel, and high-speed steel, and is centered on a surface portion of the tool main body in the state after the heat treatment. It is characterized by containing more retained austenite than the part, and is suitable for processing tools that perform strong processing such as forging, rolling, and drawing. The high carbon steel mentioned here is, for example, an Fe—C alloy containing 0.4% or more of carbon.

The amount of retained austenite (γ _R ) is measured from the X-ray intensity ratio of α (ferrite or martensite) on the (200), (211) plane and γ (austenite) on the (200), (220) plane as follows: It was obtained by the equation (1) and averaged.

γ _R (%) = [1 / {(I _α R _γ ) / (I _γ R _α ) +1}] × 100 (1)
In equation (1), I _α and I _γ are X-ray intensities, and R _α and R _γ are material constants determined by the X-rays and the lattice plane. The X-ray diffraction conditions for measuring the amount of retained austenite are as follows.

X-ray diffractometer: manufactured by Rigaku Corporation (RINT 2500)
X-ray: Co-Kα
Tube voltage: 40 kV
Tube current: 200 mA
Divergent slit: 1/2 deg
Scattering slit: 1/2 deg
Receiving slit: 0.15mm
Scanning range: 54.7-104.8deg
Scan speed: 1 deg / min
Scan step: 0.05 deg
In the preferable form of this invention, the thickness of the surface part containing more retained austenite than the center part is 0.5 mm or more. Further, the content of retained austenite in the center is preferably 5% or more. Further, the hardness of the central part is preferably Hv950 or more. Furthermore, it is preferable that the hardness of the surface portion is Hv 100 or higher than the central portion, and the internal hardness from the surface to at least a depth of 0.5 mm is Hv 1000 or higher.

  Furthermore, the W content of the surface portion is preferably 20% or more and the C content is 2% or more. In a preferred embodiment of the present invention, the surface roughness of the surface portion is preferably Ra 0.43 μm or more and Rz 2.5 μm or more.

  The manufacturing method of the present invention includes a step of forming a tool main body made of high carbon steel into a predetermined shape, and a surface portion of the tool main body by hitting a large number of fine grains at high speed on the annealed tool main body. By applying a heat treatment of quenching and tempering to the tool main body after the fine particle striking step that causes processing strain in the fine particle striking step, the surface of the tool main body is more than the center portion. And a heat treatment step for generating retained austenite.

  In a preferred embodiment of the present invention, the retained austenite existing in the surface portion is changed to martensite by processing the workpiece using the tool main body portion subjected to the heat treatment step. In the fine grain hitting step, for example, the fine grains may be hit to the surface portion with a projection energy of 0.05 MPa for 5 minutes or more. Part of the fine particles can be adhered to the surface portion by the fine particle hitting step.

  In a preferred embodiment of the present invention, the surface roughness of the surface portion is processed to Ra 0.43 μm or more and Rz 2.5 μm or more by the fine grain hitting step. Further, shot peening may be further added after the heat treatment step.

  In a conventional process for manufacturing a processing tool, shot peening or honing is usually performed after heat treatment for the purpose of removing an oxide film and imparting compressive residual stress. On the other hand, in the present invention, after the tool is formed into a predetermined shape, a fine grain striking process such as shot peening or honing is performed in an annealed state, and then heat treatment such as quenching or tempering is performed. In the present invention, through such a process, a part of the hard fine particles (for example, a part of WC particles or ceramic particles such as TiC and TiN) is attached to the surface portion, and the surface roughness of the tool is appropriately adjusted. In addition, a large amount of retained austenite is present on the surface of the tool. Thereafter, the retained austenite is martensite by a stress load when the tool is used (when the workpiece is machined). By doing this, the toughness of the tool (improvement of strength), the adhesion of some of the hard fine particles to the surface, and the formation of an appropriate surface roughness (lubricant pool), the friction of Reduce tool life and improve tool life.

  According to the present invention, in addition to martensite on the tool surface obtained during heat treatment, residual austenite abundantly present on the surface after heat treatment is converted into martensite when the workpiece is processed. Depth can be obtained, and wear and cracking of the processing tool are suppressed. According to the present invention, it is possible to improve the life of a processing tool without using a special process or chemical component that causes an increase in cost.

[Example 1]
Using a melted material of high-speed tool steel (SKH59), a machining tool for forging the head of the screw was manufactured through the following manufacturing process. An example of the processing tool is a forging punch 11 having a tool main body 10 corresponding to the shape of the processed part, as shown in FIG. An example of the size of the tool body 10 is about 2 mm in height and about 4 mm in width.

SKH59 is an example of high carbon steel, and its chemical composition (% by weight) is as follows.
C: 1.00-1.20%, Cr: 3.50-4.50%, Mo: 9.00-10.00%, W: 1.20-1.90%, V: 0.90 1.40%, Co: 7.50-8.50%, Si: 0.50% or less, Mn: 0.40% or less, balance Fe.

The manufacturing process of the processing tool of this embodiment will be described below.
First, in a molding process, a processing tool is molded into a predetermined shape by using a melting material of SKH59. Material hardness before quenching of the molded processing tool (annealed condition) _is, H _RC 19 to 23, a soft state as H V 236~253.

  Next, a shot peening process, which is an example of a fine grain hitting process, is performed on the annealed tool, thereby removing an oxide film on the tool surface and applying a large processing strain to the surface portion.

In this shot-peening step, to the tool material state before the heat treatment (H _RC 19 to 23), by striking a large number of fine particles having a projection energy exceeding a certain threshold at a high speed, the surface portion of the tool Causes processing strain. The shot peening conditions are a WC having a diameter of 0.1 mm, a direct pressure type nozzle, a tumbler type, and a projection pressure of 0.05 MPa for 5 minutes. By this shot peening process, hard particles (W content is 20% or more, C content is 2% or more) made of a part of the fine particles adhere to the surface of the tool, and the roughness is Ra 0.43 μm. Rz 2.54 μm and relatively large irregularities were formed. Ra is arithmetic average roughness, and Rz is ten-point average roughness.

After the shot peening, the tool was subjected to heat treatment for quenching and tempering in the heat treatment step. The heat treatment conditions are 1160 ° C. quenching, 560 ° C., 3 tempering, and tempering hardness H _RC 63-65 in an N ₂ gas atmosphere.

  Processing strain is accumulated on the surface portion of the tool by the shot peening process (fine grain striking process). When the quenching is performed in a state where the working strain is accumulated, the martensitic transformation itself occurs quickly because the nucleation sites of the martensitic transformation are increased by the working strain energy. However, because the nuclei interfere with each other, the growth of martensite is hindered. For this reason, when the retained austenite increases, so-called retained austenite processing is stabilized.

  When the tempered tool is tempered, a part of retained austenite is decomposed, and when the tempering is cooled, the second and third martensitic transformations are caused to further harden. Residual austenite that cannot be fully martensitic transformed by this tempering remains to some extent.

  The workpiece made of SUSXM7 (18Cr-9Ni-3.5Cu) as a workpiece was forged by the tool subjected to the heat treatment (tempering). In this specification, this forging process is referred to as hammering. Due to the strong processing of hammering, the retained austenite, which could not be completely martensitic transformed only by the heat treatment, was cured by martensitic transformation, and a deep curing depth was obtained. The surface residual stress after hammering was −135 MPa.

[Example 2]
Using the same high-speed tool steel as in Example 1, the processing tool was molded into a predetermined shape by the same molding process as in Example 1. The hardness of the tool before quenching (annealed state) is equivalent to that of Example 1.

  Next, in the shot peening process, by using the same shot material as in Example 1 for the annealed tool, shot peening is performed at 0.10 MPa for 5 minutes, thereby causing processing strain on the surface portion of the tool. It was. By this shot peening, the surface roughness of the tool was Ra 0.49 μm and Rz 3.30 μm.

  Then, after the shot peening, the tool was subjected to heat treatment of quenching and tempering. The heat treatment conditions are the same as in Example 1.

  The workpiece (SUSXM7) was forged in the same manner as in Example 1 with the tool. Due to this strong processing, the retained austenite that could not be fully martensitic transformed only by the heat treatment was cured by causing martensitic transformation, and a deep curing depth was obtained. The surface residual stress after hammering was -184 MPa.

[Example 3]
Using the same high-speed tool steel as in Example 1, the processing tool was molded into a predetermined shape by the same molding process as in Example 1. The hardness of the tool before quenching (annealed state) is equivalent to that of Example 1.

  Next, in the shot peening step, the annealed tool is subjected to shot peening at 0.20 MPa for 5 minutes using the same shot material as in Example 1, thereby causing processing strain on the surface portion of the tool. It was. By this shot peening, the surface roughness of the tool was Ra 0.68 μm and Rz 3.70 μm.

  Then, after the shot peening, the tool was subjected to heat treatment of quenching and tempering. The heat treatment conditions are the same as in Example 1.

  The workpiece (SUSXM7) was forged in the same manner as in Example 1 with the tool. Due to this strong processing, the retained austenite that could not be fully martensitic transformed only by the heat treatment was cured by causing martensitic transformation, and a deep curing depth was obtained. The surface residual stress after hammering was −108 MPa.

[Example 4]
Using the same high-speed tool steel as in Example 1, the processing tool was molded into a predetermined shape by the same molding process as in Example 1. The hardness of the tool before quenching (annealed state) is equivalent to that of Example 1.

  Next, in the shot peening step, the annealed tool is subjected to shot peening at 0.30 MPa for 5 minutes using the same shot material as in Example 1, thereby causing processing strain on the surface portion of the tool. It was. By this shot peening, the surface roughness of the tool was Ra 0.99 μm and Rz 4.90 μm.

  FIG. 2 shows the hardness distribution (test force 0.25 N) of the tool of Example 4 on which the shot peening was performed. The surface portion of the tool is hardened by Hv100 or more than the center portion by work hardening.

  Then, after the shot peening, the tool was subjected to heat treatment of quenching and tempering. The heat treatment conditions are the same as in Example 1.

  FIG. 3 is a photograph taken by enlarging the surface texture of the tool of Example 4 with a SEM (scanning electron microscope) 2000 times. The part that appears white in the tissue is carbide. It can be seen that a part of the hard shot material (fine WC particles appearing in white on the surface portion) adheres to the surface portion of Example 4.

  The workpiece (SUSXM7) was forged in the same manner as in Example 1 with the tool. Due to this strong processing, the retained austenite that could not be fully martensitic transformed only by the heat treatment was cured by causing martensitic transformation, and a deep curing depth was obtained. The surface residual stress after hammering was -130 MPa.

  The surface residual stress value immediately after the heat treatment of the tool of Example 4 was a tensile stress of +15 MPa, but changed to a compressive stress of -130 MPa after hammering. This also confirmed that the retained austenite on the surface portion was changed to martensite.

  The inventor measured the amount of retained austenite of the tool before and after hammering by X-ray diffraction. As a result, the amount of retained austenite in the surface portion was 7.1% and the amount of retained austenite in the center portion was 5.9% before hitting, and the amount of retained austenite in the surface portion was higher than that in the center portion. It was confirmed that there were many. On the other hand, after hammering, the amount of retained austenite on the surface is 5.8% and the amount of retained austenite on the center is 5.9%, and the retained austenite on the surface becomes martensite by hammering. It decreased by.

  In the state after the heat treatment, if the thickness of the surface portion containing more retained austenite than the center portion is 0.5 mm or more, it is particularly effective in increasing the hardening depth obtained by martensite formation. It was. It has also been found that if the content of retained austenite at the center is 5% or more, it is effective in increasing the depth of the hardened layer.

  Forging tools, heat cracks occur due to repeated temperature rise and cooling due to the generation of frictional heat when machining a workpiece (workpiece), and the repetition of the compression force applied to the tool during forging and the frictional force during extraction Therefore, it is considered that cracks gradually develop and cause chipping and destruction.

  Therefore, in order to improve the tool life, it is important to increase the strength of the tool and reduce the frictional force. In Examples 1 to 4, not only high hardness is maintained from the tool surface to a deep region of about 2 mm, but also by performing shot peening with high projection energy on the tool in the material state (annealed material), The surface portion is deformed, a part of the high hardness shot material (fine particles) adheres, and the surface roughness is moderately roughened.

  For this reason, the friction coefficient at the time of machining (for example, when driving) is reduced by reducing the coefficient of friction due to shot material adhesion and increasing the effect that the lubricant (for example, oil) used during workpiece processing accumulates on the unevenness of the tool surface. Decreases. These synergistic effects have improved the durability of the tool.

  In particular, when the roughness of the surface portion is Ra 0.43 μm or more and Rz 2.5 μm or more, the lubricant can be sufficiently accumulated on the unevenness of the tool surface, which is particularly effective in improving the durability of the tool.

  When the components of the surface portion before the hammering test of Example 4 were analyzed by EPMA (Electron Probe Micro Analyzer), the W content was 22.5% and the C content was 2.18%, which was much on the surface portion. It was confirmed that W and C existed. When the W content in the surface portion was 20% or more and the C content was 2% or more, the effect of reducing the friction coefficient by the shot material adhesion was great.

  As described above, in the shot peening process of the first to fourth embodiments, a high energy shot having a certain threshold value or more is projected onto the tool (completely annealed material) before quenching, and the shot projection energy is implemented from the first embodiment. It becomes large toward Example 4 in order. Further, the surface roughness of the tool is also gradually increased from the first embodiment to the fourth embodiment in accordance with the projection energy. In these Examples 1 to 4, since the heat treatment is performed after shot peening, the surface residual stress is −200 MPa or less.

[Comparative Example 1 (prior art)]
Using the same high-speed tool steel as in Example 1, the processing tool was molded into a predetermined shape by the same molding process as in Example 1. The hardness of the tool before quenching (annealed state) is equivalent to that of Example 1.

Next, heat treatment was performed. The heat treatment conditions are the same as in Example 1.
After the heat treatment, a honing process (glass blasting), which is an example of a fine grain hitting process, was performed using glass bead shots, thereby removing the oxide film and applying compressive residual stress. The honing conditions are that the shot material is glass # 150, the projection pressure is 0.5 MPa, and is 4 seconds. With this glass blasting, the surface roughness of the tool was Ra 0.39 μm and Rz 2.23 μm. The surface residual stress was -1069 MPa.

  When the amount of retained austenite in Comparative Example 1 was examined, the amount of retained austenite in the surface portion was 2.3%, the amount of retained austenite in the center portion was 3.4%, and the surface portion was before the hammering. It was confirmed that the amount of retained austenite was smaller than that in the center. After hammering, the amount of retained austenite in the surface portion was reduced to 1.6% due to the martensite of the retained austenite in the surface portion.

  FIG. 4 is a photograph taken by enlarging the surface texture of the tool of Comparative Example 1 with a SEM (scanning electron microscope) 2000 times. The parts that appear white in the photo are carbides. The unevenness of the surface portion of Comparative Example 1 is smaller than the unevenness of the surface portion of Example 4 shown in FIG. 3, and the shot material hardly adheres to the surface portion.

  When the components of the surface portion before the hammering test of Comparative Example 1 were analyzed by EPMA, the W content was 2.6% and the C content was 1.33%, which was higher than that of Example 4 in terms of W and C. The content was small, and the effect of reducing the friction coefficient due to adhesion of the shot material was not expected.

[Comparative Example 2]
Using the same high-speed tool steel as in Example 1, the processing tool was molded into a predetermined shape by the same molding process as in Example 1. The hardness of the tool before quenching (annealed state) is equivalent to that of Example 1.

Next, heat treatment was performed. The heat treatment conditions are the same as in Example 1.
A shot peening process was performed after the heat treatment. The shot peening conditions are the same high pressure shot of 0.3 MP as in the fourth embodiment. By this shot peening, the surface roughness of the tool was Ra 0.42 μm and Rz 3.77 μm. The surface residual stress was −1347 MPa.

[Comparative Example 3]
Using the same high-speed tool steel as in Example 1, the processing tool was molded into a predetermined shape by the same molding process as in Example 1. The hardness of the tool before quenching (annealed state) is equivalent to that of Example 1.

  Next, a honing process (glass blasting) was performed. Honing conditions are the same as in Comparative Example 1. By this glass blasting, the surface roughness of the tool was Ra 0.73 μm and Rz 4.67 μm.

  And it heat-processed after glass blasting. The heat treatment conditions are the same as in Example 1. The surface residual stress after the heat treatment was -204 MPa.

[Comparative Example 4]
Using the same high-speed tool steel as in Example 1, the processing tool was molded into a predetermined shape by the same molding process as in Example 1. The hardness of the tool before quenching (annealed state) is equivalent to that of Example 1.

  Next, WPC treatment was performed. The WPC treatment conditions are that the shot material is a high speed steel system # 400, an arc height of 100 mm, a projection pressure of 0.2 MPa, and a projection time of 30 seconds. By this WPC treatment, the surface roughness of the tool was Ra 1.12 μm and Rz 6.71 μm.

  Heat treatment was performed after the WPC treatment. The heat treatment conditions are the same as in Example 1. The surface residual stress after the heat treatment was -195 MPa.

  FIG. 5 is a result of examining the hardness distribution (test force 0.25 N) after heat treatment of Example 4 and Comparative Examples 1 and 2 before and after hammering. The hardness before hammering in Example 4 is a level (Hv 950 to 1000) substantially equal to that in Comparative Example 1. However, it can be seen that Example 4 is significantly hardened by martensite formation of retained austenite after hammering and that the hardening depth of Hv1000 or more is as deep as about 2 mm.

  On the other hand, Comparative Example 2 performs shot peening with high projection energy after heat treatment (quenching and tempering). For this reason, the surface hardness is hardened to the same level as in Example 4 by work hardening by shot peening. However, the curing depth of Comparative Example 2 is shallower than that of Example 4.

  That is, in Comparative Example 2, a large compressive residual stress was applied by shot peening after heat treatment, and the surface hardness was hardened to the same level as in Example 4, but the hardening depth was as shallow as about 0.1 mm. , There was little effect to improve the tool life. On the other hand, in Comparative Example 1, honing was performed after the heat treatment. However, since the projection energy was small, work hardening was small and almost no increase in surface hardness was observed.

  FIG. 6 shows the results of a hammering test using the working tools of Examples 1 to 4 and Comparative Examples 1 to 4. The workpiece is SUSXM7 (18Cr-9Ni-3.5Cu). In this hammering test, the number of cracks generated in the tool was counted from the protrusions transferred to the workpiece every 1000 hammering.

  According to the results of this hammering test, in Comparative Examples 1 to 4, cracks 12 and wear 13 as shown in FIG. About 100 cracks were confirmed around 10,000 hammers.

  In particular, Comparative Examples 1 and 2 had a small effect of suppressing crack generation despite a large compressive residual stress of −1000 MPa or more on the tool surface. In Comparative Example 3, since the projection time was short and the projection energy was small in the honing process, the effect of suppressing the occurrence of cracks was small. In Comparative Example 4, since the projection time was short and the projection energy was small in the WPC process, the effect of suppressing the occurrence of cracks was small.

  On the other hand, in Examples 1-4 of this invention, although the compressive residual stress after heat processing is small compared with Comparative Examples 1-4, generation | occurrence | production of a crack is fully suppressed. The effect of suppressing the crack was greater as the shot projection energy in the shot peening process was larger (for example, Example 4). For this reason, in the shot peening process, it is desirable to strike fine particles with a projection energy of 0.05 MPa for 5 minutes or more.

  In order to increase the curing depth, the hardness of the central portion is preferably Hv950 or more. Further, it is more preferable that the hardness of the surface portion is Hv 100 or more than that of the central portion, and the internal hardness from the surface to at least a depth of 0.5 mm is Hv 1000 or more.

  Table 1 below shows the wear rate (μm) per 1000 hammers of Examples 1-4 and Comparative Examples 1-4. From Table 1, it can be seen that in Examples 1 to 4, the wear rate is smaller than in Comparative Examples 1 to 4, and the wear resistance is excellent. In particular, the wear resistance of Example 4 having a high shot projection energy in the shot peening process (fine grain hitting process) is excellent.

The reason why the abrasion resistance of Example 4 is most excellent is that the hardness of the tool surface portion is high, the friction of the surface portion is reduced due to adhesion of a part of the hard shot material (fine particles), and This is a synergistic effect due to the fact that the surface roughness is large and the lubricant accumulation effect is high. In order to enhance the accumulation effect of the lubricant, the shot peening process (fine grain striking process) performed in the raw material state (annealed material) is performed so that the surface roughness is Ra 0.43 μm or more and Rz 2.5 μm or more. It is good to do.

  In Examples 1 to 4, the workpiece is beaten with a tool after heat treatment (used as a forging punch), but the remaining austenite is martensite before use as a punch to increase the strength. As means for achieving this, shot peening may be added immediately after quenching or after tempering. Further, after the heat treatment, a nitriding treatment or a coating treatment such as TiN, TiC, TiCN, TiAlN or the like may be performed.

The perspective view of the processing tool of one Embodiment of this invention. The figure which shows the hardness distribution (test force 0.25N) after the shot peening of the processing tool shown in FIG. The photograph which expanded the surface texture of the processing tool shown in Drawing 1 by 2000 times with SEM (scanning electron microscope). The photograph which expanded the surface texture of the comparative example 2000 times with SEM (scanning electron microscope). The figure which shows the result of having investigated the hardness distribution (test force 0.25N) of each processing tool of an Example and a comparative example before hammering and after hammering. The figure which shows the impact test result of each processing tool of an Example and a comparative example. The perspective view which shows the state which the crack produced in the processing tool of a comparative example.

Explanation of symbols

10 ... Tool body 11 ... Punch for forging (tool for processing)

Claims (14)

A machining tool for machining a workpiece,
Having a heat treated tool body made of high carbon steel,
In the state after the heat treatment, the surface of the tool main body includes a larger amount of retained austenite than the center.   2. The processing tool according to claim 1, wherein a thickness of a surface portion containing more retained austenite than the center portion is 0.5 mm or more.   The machining tool according to claim 1, wherein the content of retained austenite in the central portion is 5% or more.   The machining tool according to any one of claims 1 to 3, wherein the hardness of the central portion is Hv950 or more.   5. The processing tool according to claim 4, wherein the hardness of the surface portion is Hv 100 or more than that of the central portion, and the internal hardness from the surface to at least a depth of 0.5 mm is Hv 1000 or more. .   6. The processing tool according to claim 1, wherein the surface portion has a W content of 20% or more and a C content of 2% or more.   7. The processing tool according to claim 1, wherein a surface roughness of the surface portion is Ra 0.43 μm or more and Rz 2.5 μm or more.   The processing tool according to claim 1, wherein the high carbon steel is an Fe—C alloy containing 0.4% or more of carbon. Forming a tool body made of high carbon steel into a predetermined shape;
A fine grain striking step for causing processing strain on the surface portion of the tool main body by hitting a large number of fine grains at high speed on the tool main body in an annealed state,
After the fine grain hitting step, by performing heat treatment of quenching and tempering on the tool body part, a heat treatment process for generating more retained austenite than the center part on the surface part of the tool body part, and
The manufacturing method of the tool for processing characterized by comprising.   The manufacturing method of the processing tool according to claim 9, wherein the work is processed using the tool main body portion on which the heat treatment step has been performed to change the retained austenite of the surface portion to martensite.   The method for manufacturing a processing tool according to claim 9, wherein the fine grain hitting step hits the fine grain on the surface portion with a projection energy of 0.05 MPa for 5 minutes or more.   The method for manufacturing a processing tool according to claim 9, wherein a part of the fine particles is adhered to the surface portion by the fine particle hitting step.   10. The method for manufacturing a processing tool according to claim 9, wherein the surface roughness of the surface portion is processed to Ra 0.43 [mu] m or more and Rz 2.5 [mu] m or more by the fine grain hitting step.   The method for manufacturing a processing tool according to claim 9, further comprising adding shot peening after the heat treatment step.

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