JP6563571B1 - Mold manufacturing method - Google Patents

Abstract

Disclosed is a mold manufacturing method, and in particular, a mold manufacturing method capable of extending the life of a mold by improving a surface treatment process at the time of manufacturing a die casting mold. (A) A steel material is subjected to shot blasting treatment on the surface of the steel material after machining or electric discharge machining to remove the work-affected layer, and (B) shot peening treatment is performed after the shot blasting treatment. And a step of adjusting the surface roughness and applying compressive residual stress. And (C) a step of performing nitriding after the shot peening treatment. [Selection] Figure 6

Description

  The present invention relates to a mold manufacturing method, and more particularly, to a mold manufacturing method capable of extending the life of a mold by improving a surface treatment process when manufacturing a die-cast mold.

  Since die casting is excellent in productivity and can provide high quality castings, most of the aluminum castings are currently die casting products. Many of the products are automobile parts, and high quality and light weight of parts are required due to recent high performance and light weight. For this reason, die casting molds are also required to have high quality and long life, and high performance steel materials and many surface treatments have been proposed and put into practical use.

Moreover, as a process of manufacture of a metal mold | die, generally, it is performed at the following processes (1)-(12).
(1) Design (2) Machining data creation (3) Roughing (4) Finishing (5) Machining (machining)
(6) Electrical discharge machining (7) Polishing (8) Dimensional inspection (mold part)
(9) Assembly (10) Trial hit (11) Dimensional inspection (Product)
* Die modification as necessary (12) Surface treatment (nitriding, etc.)

  With regard to such a mold manufacturing method, Non-Patent Document 1 has various factors such as mold material, heat treatment, casting conditions, and other factors that influence the mold life. Generally, as described above, machining and electrical discharge machining are used for machining the mold, and in any case, after machining, an altered layer (melted and re-solidified layer) is formed on the machined surface of the steel material. It is necessary to perform polishing for removing the deteriorated layer. Specifically, the roughness (Rz) of the machining surface or electrical discharge machining surface in the above process is usually about 5 to 20 μm, and “polishing” is performed to smooth this surface and remove the altered layer during processing. (Polishing) ". In addition, the polishing in the above-described step (7) is still performed manually in many cases even today and consumes a lot of manpower, time and cost. This is because, as disclosed in Non-Patent Documents 2 to 4, an altered layer occurs on the electric discharge machined surface, and this altered layer has a fragile layer and microcracks due to local dissolution and re-solidification, and tensile residual stress. Therefore, if it is not completely removed, the mold life will be adversely affected.

  Further, it is said that unevenness (tool mark) on the processed surface remains even when the machining is completed only by machining without using electric discharge machining for the mold, and this is the starting point of occurrence of cracks. Furthermore, it is said that there is also a tensile residual stress, and polishing of the processed surface is required even in the case of machining (Non-Patent Document 5).

  Further, as described above, after the post-machining polishing or the electro-discharge polishing, a test punching is performed, and after the dimensions of the product can be confirmed, a surface treatment such as nitriding is performed. This is because, if surface treatment such as nitriding is performed before checking the dimensions, it is not easy to correct the dimensions of the mold if there is a dimensional defect in the product.

  In addition, as for the mold surface treatment in the step (12), a great number of treatments are actually performed. It is known that smoothing of the mold surface by shot peening and compressive residual stress have a good effect on the mold life, and a technique combining shot peening and nitriding is also proposed. (Patent Document 1 and Patent Document 2).

Masahiko Hihara, “Die-casting tool life improvement and countermeasures”, Light Metal Communications Co., Ltd., September 1994 Masahiko Hihara, Koji Yatsushiro, “Study on Life of Die Casting Die Steel”, Yamagata Industrial Technology Center, 1993, No. 7, p53-59 Masahiko Hihara, Shigeru Sugawara, Koji Yatsushiro, Masaaki Sano, “Development of Advanced and Precision Technology for Production Molds (3rd Report)”, Yamagata Industrial Technology Center Research Report, 1996, No. 10, p1 Masui Kiyonori, Sone Takumi, Sato Yukihiro, Minamihisa, “Trouble Cases of EDM Surfaces in Mold Manufacture and Countermeasures”, Journal of Electrical Machining Society, 2000, Vol. 34, no. 76, p42-49 Hidehiko Takeyama, “University Lecture Cutting”, Maruzen Publishing, 1997, p132

JP 2011-23531 A JP 2004-14836 A

  In the manufacture of molds, the polishing of the above step (7) has been conventionally performed to remove the deteriorated layer. However, since the polishing work is mainly performed manually, there is a problem that time and cost are consumed. was there. Therefore, there has been a demand for a method for removing the deteriorated layer in place of polishing.

  In addition, although trial punching is performed after polishing after machining or after polishing after electric discharge machining, there is a case in which a fine crack enters the mold at the time of trial punching, which adversely affects the life of the mold. For this reason, it is required to perform a treatment that can prevent the occurrence of fine cracks without hardening the mold surface, such as nitriding, and to perform nitriding after the trial. In addition, the trial punching in the above step 10 is a step necessary for performing a dimensional inspection of the product before the surface treatment of the mold, and correcting the mold if necessary. A fine crack is generated in the metal, and if this fine crack is present, the crack becomes a starting point even after the nitriding treatment, which may adversely affect the mold life. However, at present, there are no examples that mention the mold manufacturing process by paying attention to the crack at the time of trial hitting.

  Furthermore, although the techniques described in Patent Documents 1 and 2 are considered to be effective for labor saving, cost reduction, or mold life extension, respectively, the cost reduction for the entire mold manufacturing process, shortening the work period, and high quality of the mold. It was hard to say that it was the best for the development. Further, in order to manufacture a long-life mold at a low cost, various ideas have been made in each process as described above, but the processing content and the processing process are not always clear.

  Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art, focusing on fine cracks at the time of trial hitting, which has been pointed out as a problem but was not sufficiently addressed, and before and after The present invention provides a mold manufacturing method capable of extending the service life of a mold at a short construction period and at low cost by making the processing contents of the mold manufacturing process appropriate.

  As a result of intensive studies to solve the above problems, the present inventors have found that the object can be achieved by performing shot peening after shot blasting, and have completed the present invention. .

That is, the mold manufacturing method of the present invention is:
(A) A step of performing a shot blast treatment on the surface of the steel material after machining or electric discharge machining of the steel material to remove the work-affected layer;
(B) A step of performing shot peening after the shot blasting to adjust the surface roughness and applying compressive residual stress;
It is characterized by having.

Moreover, the manufacturing method of the metal mold | die of this invention is as follows.
(A) A step of performing a shot blast treatment on the surface of the steel material after machining or electric discharge machining of the steel material to remove the work-affected layer;
(B) A step of performing shot peening after the shot blasting to adjust the surface roughness and applying compressive residual stress;
(C) performing a nitriding process after the shot peening process;
It is characterized by having. Furthermore, it is preferable that the surface hardened layer depth in the steel material after the nitriding treatment is 50 to 100 μm. More preferably, in the nitriding treatment, a nitriding treatment in which a so-called “white layer” generated on the steel material surface by ordinary gas nitriding or the like does not occur is desirable.

  Further, the mold manufacturing method of the present invention is a shot blasting process in which the shot blasting process is performed using an F10 to F320 alumina or silicon carbide shot material at an air pressure of 0.2 MPa to 0.6 MPa, The shot peening treatment is preferably a shot peening treatment performed using a peening material of glass beads, steel beads, zircon beads or zirconia beads corresponding to # 120 to # 320 at an air pressure of 0.2 MPa to 0.6 MPa. In the present invention, “F” and “#” are according to JIS R6001.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the metal mold | die which can aim at the lifetime improvement of a metal mold | die can be provided by the improvement of the surface treatment process at the time of die-casting metal mold manufacture.

It is a photograph of the surface after electric discharge machining (sample No. 1-1). It is a photograph of the section of the surface after electric discharge machining (sample No. 1-1). It is a photograph of the surface after carrying out shot blasting after electric discharge machining (sample No. 1-2). It is a photograph of the cross section of the surface after performing shot blast processing after electric discharge machining (sample No. 1-2). It is a photograph of the surface after performing shot blast processing after electric discharge machining, and also shot peening processing (sample No. 1-3). It is a photograph of the cross section of the surface after performing shot blast processing after electric discharge machining, and also shot peening processing (sample No. 1-3). It is a photograph of the surface after performing shot peening processing after electric discharge machining (sample No. 1-4). It is a photograph of the section of the surface after performing shot peening processing after electric discharge machining (sample No. 1-4). It is a figure which shows the thermal fatigue testing machine used for a thermal fatigue test. It is a graph which shows the thermal cycle in a thermal fatigue test. It is the photograph of the surface state after the test of the test piece (test piece 3-1) which performed # 400 paper finishing after machining finish. It is a photograph of the surface state after the test of the test piece test piece (3-2) subjected to shot blasting and further shot peened after machining finish. It is a photograph of the surface state after the test of a test piece (test piece 4-1) that is subjected to # 400 paper finish after machining finish and has no nitriding treatment. It is a photograph of the surface state after the test of a test piece (test piece 4-2) that is subjected to shot blasting treatment and further shot peening treatment after machining finish and further subjected to nitriding treatment. It is a photograph of the surface state after the test of the test piece (test piece 4-3) subjected to shot blasting, further shot peening, and nitrided after machining finish.

Hereinafter, a method for manufacturing a mold according to the present invention (a method for surface treatment of a steel material in mold manufacture) will be specifically described.
The mold manufacturing method of the present invention includes (A) a step of performing a shot blasting process on the surface of the steel material after machining or electric discharge machining of the steel material to remove a work-affected layer, and And a step of performing a shot peening treatment after the treatment to adjust the surface roughness and impart compressive residual stress. In this way, by performing shot blasting and shot peening after machining or electrical discharge machining, it is possible to remove the altered layer and tensile residual stress on the processed surface of the steel, to adjust the surface roughness and to apply compressive residual stress As a result, the time and cost of the polishing work can be reduced, and in addition, the generation of microcracks during trial strikes can be prevented. The machining can be performed using a machining machine such as a vertical machining center MB-46VA (trade name) manufactured by Okuma Corporation. ) Or the like.

  The mold manufacturing method of the present invention includes (A) a step of performing a shot blasting process on the surface of the steel material after machining or electric discharge machining of the steel material, and removing a work-affected layer (B) A step of performing shot peening after the shot blasting to adjust the surface roughness and imparting compressive residual stress; and (C) a step of performing nitriding after the shot peening. To do. Thus, by performing test punching after shot peening, and performing nitriding after the test punching, it is possible to extend the mold life. Instead, it is necessary to prevent the occurrence of fine cracks by shot blasting and subsequent shot peening, and to perform nitriding after trial firing.

  It is important to prevent the occurrence of fine cracks at the time of trial hitting in order to maintain the subsequent mold life, and for this purpose, the surface alteration layer of the steel material is removed after the mold processing to suppress crack generation. It is desirable to apply. Thus, as a result of intensive studies, it has been found that shot blasting is effective for removing the deteriorated layer, and that shot peening is effective for imparting surface modification and compressive residual stress. As a result, in the present invention, by performing an appropriate mold surface treatment in an appropriate process at the time of manufacturing an aluminum die casting mold, it is possible to shorten the construction period, reduce costs, and provide a long-life mold. Is something that can be done.

  Shot blasting is a process in which a particle called a projection material (shot material (shot media)) collides with a workpiece, and is generally used for dirt removal and cleaning. Various media and blasting conditions are used. It is. A certain level of scouring force is required to remove the deteriorated layer, but the scouring force is so strong that it is not preferable to make the surface unnecessarily rough. For this reason, it is necessary to select shot materials and shot blasting conditions in consideration of the finishing state of machining or electric discharge machining, and shot blasting under appropriate conditions is necessary. The shot peening process after the shot blasting process is a process in which a small sphere of an infinite number of steels or non-ferrous metals collides with the metal surface at high speed, and adjusts the surface roughness and imparts compressive residual stress. Also in this case, it is necessary to use an optimal shot material or to use peening conditions in consideration of the finished state of the shot blasting process.

  Therefore, the method for producing a mold of the present invention is a shot blasting process in which the shot blasting process is performed using an F10 to F320 alumina or silicon carbide shot material at an air pressure of 0.2 MPa to 0.6 MPa, The shot peening treatment is preferably a shot peening treatment performed using a peening material of glass beads, steel beads, zircon beads or zirconia beads corresponding to # 120 to # 320 at an air pressure of 0.2 MPa to 0.6 MPa. Further, the mold manufacturing method of the present invention is a shot blasting process using an F54 to F240 alumina or silicon carbide shot material at an air pressure of 0.3 MPa to 0.5 MPa, and the shot peening process is performed as follows: It is more preferable that the shot peening treatment is performed using a peening material of # 120 to # 240 glass beads, steel beads, zircon beads or zirconia at an air pressure of 0.3 MPa to 0.5 MPa. By setting it as this shot blasting condition, the work time for removing the deteriorated layer on the mold surface can be shortened, and processing can be performed in a balance that does not unnecessarily roughen the surface roughness.

  In the present invention, the order of the steps of the shot blasting process and the shot peening process cannot be reversed. This is also shown in the following examples, but it is difficult to remove the altered layer by shot peening treatment on the processed surface of the steel material, and when shot blast treatment is performed after shot peening treatment, This is because it is difficult to make the steel material a smooth surface as compared with the case where the shot peening treatment is performed.

  Further, in the present invention, nitriding can be performed after the shot blasting and shot peening. As described above, shot blast treatment is performed after mold processing to remove the altered layer, and surface modification is performed by shot peening treatment to give compressive residual stress, thereby reducing the short construction period and low cost at the time of trial firing. If it is possible to provide a mold having a high crack prevention effect and prevent the occurrence of cracks at the time of trial hitting, the effect of the subsequent nitriding treatment will be greater than when nitriding treatment is performed in the presence of fine cracks. . Furthermore, as a pretreatment for nitriding treatment, surface blasting by shot blast treatment is used to clean and activate the surface, facilitating nitriding treatment and removing extremely fine cracks on the surface. Further, by performing shot peening treatment, the surface roughness can be adjusted and compressive residual stress can be applied.

  In the present invention, as described above, the effect of extending the life of the mold by surface hardening by nitriding is further exhibited by these pretreatments, but the depth of the hardened layer by nitriding treatment (surface hardened layer depth) As for it, it is preferable that 50-100 micrometers is effective from the heat crack resistance of a metal mold | die, and it does not produce what is called a white layer on the surface. Further, by performing shot peening after nitriding, a greater compressive residual effect is imparted and the mold life can be further extended.

  In the present invention, the nitriding method is not particularly limited as long as the steel material can be nitrided, and the effects of the present invention can be obtained. Ion nitriding method, plasma nitriding method, gas nitriding method, gas soft nitriding A method such as a law can be mentioned. The conditions for the nitriding treatment are not particularly limited as long as the steel material can be nitrided and the effects of the present invention can be obtained, but the gas soft nitriding method is preferred.

  Moreover, it is preferable that nitriding temperature is 500-600 degreeC and a nitrided layer is 50-100 micrometers from a metal mold | die surface. As the nitriding treatment, cracks occurred during the use of the mold by controlling the nitriding conditions so as not to produce iron and nitrogen compounds (Fe4N and Fe2-3N), so-called “white layers” on the surface of the steel material. In this case, nitriding can be performed again.

  Furthermore, in the present invention, examples of the mold (die casting mold) include a die casting mold used for casting aluminum alloy, magnesium alloy, and the like. The mold steel material is not particularly limited as long as the effects of the present invention can be obtained, and examples thereof include JIS G 4404 SKD61.

  Furthermore, in this invention, the process which can be used for the manufacturing method of a normal metal mold | die can be added in the range which does not impair the effect of this invention. For example, the method for manufacturing a mold of the present invention may include a step of discharge coating or oxidation treatment.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example, this invention is not limited to these Examples.

Example 1
Under the conditions shown in Table 1 below, the SKD61 heat treated steel was processed. The electric discharge machining was performed using an EDGE3 electric discharge machine (trade name) manufactured by Makino Milling Co., Ltd. under the electric discharge machining conditions during normal mold production. Moreover, the surface and cross section of the steel material after a process were image | photographed with the VHX-6000 digital microscope (brand name) by Keyence Corporation. Furthermore, the surface roughness of the steel material after the treatment was measured using a surf test SJ-400 manufactured by Mitutoyo Corporation, and is also shown in Table 1. The surface roughness is measured by a method defined in JIS B 0601: 2001.

  1 is a photograph of the surface after electrical discharge machining (Sample No. 1-1), FIG. 2 is a photograph of a cross section of the surface after electrical discharge machining (Sample No. 1-1), and FIG. FIG. 4 is a photograph of the surface after shot blasting after EDM (Sample No. 1-2), and FIG. 4 is a photograph of a cross section of the surface after shot blasting after EDM (Sample No. 1-2). 5 is a photograph of the surface after shot blasting after electric discharge machining and further shot peening (Sample No. 1-3), and FIG. 6 is shot blasting after electric discharge machining and further shot peened. FIG. 7 is a photograph of the cross section of the surface after the treatment (Sample No. 1-3), FIG. 7 is a photograph of the surface after the shot peening treatment after the electric discharge machining (Sample No. 1-4), and FIG. Shot pein after electric discharge machining A cross-sectional photograph of the surface after treatment (Sample No. 1-4). From FIG. 1, the surface after electric discharge machining is rough, and from FIG. 2, it can be confirmed that a white deteriorated layer is generated in the cross section of the steel material after treatment. Further, it can be confirmed from FIG. 3 and FIG. 4 that the surface-affected layer is removed and the surface is smooth after shot blasting. Furthermore, from FIG. 7 and FIG. 8, it can be confirmed that the surface-modified layer is not removed on the surface and cross section of the sample subjected to only shot peening after electric discharge machining. On the other hand, from FIG. 5 and FIG. 6, by performing shot blasting after electric discharge machining and further performing shot peening, 1-2 and sample no. Compared with 1-4, it can confirm that it is smooth. This can also be confirmed from the surface roughness results in Table 1.

(Example 2)
Under the conditions shown in Table 2 below, the SKD61 heat treated steel was processed. Machining was performed with a vertical machining center MB-46VA (trade name) manufactured by Okuma Corporation. Further, the surface roughness of the steel material after the treatment was measured using a surf test SJ-400 manufactured by Mitutoyo Co., Ltd., and the compressive residual stress (MPa) after the treatment was measured by an X-ray diffraction residual stress measuring device. These are also shown in Table 2. In Table 2, shot blasting was performed under conditions of blasting with F240 alumina and an air pressure of 0.4 MPa, and shot peening was performed under conditions of peening with # 120 Zr beads and 0.6 MPa air pressure.

  From the results in Table 2, when the steel material of the SKD61 heat-treated material is machined, there are cases of “shot blasting and then shot peening after machining” and “shot peening after machining and shot. The effect on surface roughness and residual stress differs greatly in the case of `` blasting '', and the surface roughness is smaller and the compressive residual stress is larger when shot blasting is performed after machining and then shot peening is performed. Thus, the surface of the steel material could be improved and the life of the mold could be extended.

(Example 3)
Under the conditions shown in Table 3 below, the SKD61 heat treated steel was processed. Moreover, the following thermal fatigue test was done with respect to the steel material after a process on the conditions of following Table 3, and the surface state photograph was image | photographed.

(Thermal fatigue test)
FIG. 9 is a diagram showing a thermal fatigue tester used for the thermal fatigue test, and FIG. 10 is a graph showing a thermal cycle in the thermal fatigue test. 9A is a diagram showing a state during heating and pressurization, and FIG. 9B is a diagram showing a state during cooling. In FIG. 9, 1 is a heater, 2 is a heating block, 3 Is a test piece, 4 is a cylinder, 5 is a water tank, 6 is a rod connected to the cylinder 4, 2a is a thermocouple, arrow a is the direction of movement of the rod 6 during heating and pressurization, and arrow b is a rod 6 for cooling and heating. Indicates the switching direction. As shown in FIG. 9A, the test piece 3 is placed at the tip of the rod 6, and the cylinder 4 is heated and pressurized in the direction of arrow a. Thereafter, when the test piece 3 reaches 560 ° C., as shown in FIG. 9B, the test piece 3 is rotated in the direction of the arrow b and cooled in the water tank 5 containing water. As shown in FIG. 10, this was repeated for the number of cycles described in the table, and a photograph of the surface state was taken.

  FIG. 11 is a photograph of the surface state after the test of the test piece (test piece 3-1) subjected to # 400 paper finishing after the machining finish. It was confirmed by the penetrant testing that a large number of cracks occurred. On the other hand, FIG. 12 is a photograph of the surface state after the test of the test piece (test piece 3-2) subjected to shot blasting and then shot peening after the machining finish. Cracks could not be confirmed. From this, compared with the case where the polishing treatment is performed, by performing the mold manufacturing method of the present invention, the occurrence of cracks can be prevented and the surface of the steel material can be improved, and the life of the mold can be extended. I was able to plan.

Example 4
Under the conditions shown in Table 4 below, the SKD61 heat treated steel was processed. Moreover, the said thermal fatigue test was done with respect to the steel materials after a process on the conditions of following Table 4, and the photograph of the surface state was image | photographed. The nitriding treatment was performed by gas soft nitriding, and nitriding was performed so that the depth of the hardened layer (surface hardened layer depth) by the nitriding treatment was 50 μm.

  FIG. 13 is a photograph of the surface state after a test of a test piece (test piece 4-1) that was subjected to # 400 paper finish after machining finish and was not subjected to nitriding treatment. It was confirmed by the penetrant testing that a large number of cracks occurred. FIG. 14 is a photograph of the surface state after the test of a test piece (test piece 4-2) that has been subjected to shot blasting treatment and further shot peening treatment after machining finish, and without nitriding treatment. Further, FIG. 15 is a photograph of the surface state after the test of the test piece (test piece 4-3) subjected to the shot blasting process, the shot peening process, and the nitriding process after the machining finish. It was confirmed that the generation of cracks was further suppressed when shot peening was performed after shot blasting and further nitriding was performed.

(Example 5)
Experiments were conducted on the polishing time and surface roughness when the electric discharge machining surface was polished by shot blasting, and the results are shown in Table 5 below. In Table 5, the electric discharge machining conditions were the same as those in Example 1 above, and the test piece was a 50 mm × 90 mm × 5 mmt SKD61 material. When the shot material was fine, the surface roughness was fine but the polishing time was long. Also, the lower the shot pressure, the finer the surface roughness but the longer it took. On the other hand, when the shot material is rough, the erosion time is shortened, but the surface roughness is rough. Therefore, it is necessary to select shot blasting conditions for efficiently removing the surface altered layer depending on the finished roughness of the electric discharge machined surface or the machined surface. Furthermore, it is necessary to satisfy the required finishing roughness of the mold surface. Conventionally, it has been desirable that the mold surface has a smooth surface. However, in recent years, there are cases in which the mold surface has irregularities to improve the casting quality. Requirements are diversifying. Therefore, when finishing the surface smoothly, it is desirable that the shot material is finer and the shot pressure is lower, but from the viewpoint of work efficiency, if the shot material is lower than F220, it takes too much time and is economically viable. It ’s hard. Similarly, the shot pressure is inefficient when it is 0.2 MPa or less. On the other hand, if the shot material is rough and the shot pressure is increased, the working efficiency increases, but as shown in Example 6 below, it may be difficult to adjust the roughness by shot peening after shot blasting. Usually, there is almost no need to process the roughness of the entire mold surface to about 100 μm or more, so there is no need to make the shot material rougher than F10, and the shot pressure is the air pressure used in general factories. There is no need to make it larger than 6 MPa.

(Example 6)
Experiments were conducted when the shot blast surface was smoothed by shot peening, and the results are shown in Table 6 below. The test piece used was a 50 mm × 90 mm × 5 mmt SKD61 plate, F220, F54, and F10 alumina were projected onto the test piece to perform shot blasting, and further, # 120 zircon beads were applied to the test piece. Second projection. When the peening pressure is increased, the surface roughness decreases. However, at 0.4 MPa or more, even if the peening pressure is increased, the rate of decrease in the surface roughness decreases. Therefore, in the case of shot peening, the same can be said from the point of work efficiency as in the case of shot blasting, and the treatment at 0.2 to 0.6 MPa, particularly 0.3 to 0.5 MPa is efficient. .

DESCRIPTION OF SYMBOLS 1 Heating heater 2 Heating block 2a Thermocouple 3 Test piece 4 Cylinder 5 Water tank 6 Rod arrow a Heating / pressurizing direction arrow b Cooling heating switching direction

Claims (3)

(A) A step of performing a shot blast treatment on the surface of the steel material after machining or electric discharge machining of the steel material to remove the work-affected layer;
(B) A step of performing shot peening after the shot blasting to adjust the surface roughness and applying compressive residual stress;
The manufacturing method of the metal mold | die characterized by having. (A) A step of performing a shot blast treatment on the surface of the steel material after machining or electric discharge machining of the steel material to remove the work-affected layer;
(B) A step of performing shot peening after the shot blasting to adjust the surface roughness and applying compressive residual stress;
(C) performing a nitriding process after the shot peening process;
The manufacturing method of the metal mold | die characterized by having.   The method for producing a mold according to claim 2, wherein a surface hardened layer depth in the steel material after the nitriding treatment is 50 to 100 µm.