TW201736013A - Formed material manufacturing method and formed material - Google Patents

Abstract

In the present invention, in producing a molding material by a molding process including at least one squeezing process, and at least one drawing process performed after said squeezing process, the width of a punch 31 used for the squeezing process is made wider at a rear end side than the width at a leading end side, and by pushing a material metal plate 2 along with the punch 31 into a push-in hole 30a, an ironing process is performed on a region corresponding to a flange section of the material metal plate. At such time, a material metal plate comprising a metal having a body-centered cubic structure is used, and the flange diameter reduction rate obtained from the flange diameter after the drawing process and the diameter of the material metal plate is set to be 0.42 or less.

Description

Forming material manufacturing method and the forming material

The present invention relates to a method for producing a molded material, which is a molded material having a tubular body portion and a flange portion formed at an end portion of the body portion.

For example, as shown in the following Non-Patent Document 1 and the like, a molding material having a tubular main body portion and a flange portion formed at an end portion of the main body portion is produced by performing a drawing process. Further, as shown in Patent Document 1, a multi-stage drawing process is also performed in which the tubular main body portion is extended by performing a plurality of drawing processes. Here, in the drawing process, the body portion is formed by introducing a material metal plate between the dies. Therefore, the region corresponding to the flange portion of the metal plate is contracted as a whole corresponding to the formation of the body portion, and the diameter of the flange portion becomes smaller than the material diameter. In addition, the material is sometimes referred to as "blank" below.

One of the processing defects in the re-stretch forming of the multi-stage deep drawing process has a longitudinal crack. The longitudinal split is the outer ring (cup) after the multi-stage drawing process The phenomenon that the edge or the body portion is broken like a bamboo in parallel with the depth direction of the outer ring is one of the brittle fractures visible in the metal of the body-centered cubic structure such as iron.

In the multi-stage drawing process, the material of the flange portion is deformed by a large compression-shrinkage flange to be compressed, and the thickness thereof is increased, thereby embrittlement. In the flange portion which is deformed by the contraction flange, the residual stress of the stretching acts in the circumferential direction, and as the flange reduction ratio increases, the residual stress also increases.

Further, the flange reduction ratio can be obtained by the following formula (first formula).

On the other hand, the strength of the grain in the material is increased by work hardening, and the strength of the grain boundary is relatively lowered, so that the grain boundary is deteriorated at a low strength. Furthermore, the longitudinal crack is related to the so-called transition temperature at which the material is brittle and brittle at a low temperature, and the higher the transition temperature of the material, the more likely the longitudinal crack is generated. In addition, the embrittlement phenomenon is specific to a metal having a body-centered cubic crystal structure, and is a case where a metal having a crystal structure of a face-centered cubic structure, such as nickel, aluminum, or Worthfield iron-based stainless steel is used as a material metal plate. Invisible phenomenon.

The longitudinal crack can be avoided, for example, by adding an appropriate amount of C (carbon), reducing P (phosphorus) and S (sulfur) as much as possible, and adding a very small amount of B (boron).

Regarding the method of avoiding the longitudinal cracking from the viewpoint of processing, it is conceivable to perform the multi-stage drawing processing without introducing the material as much as possible, and as a result, the flange diameter is kept large and the flange reduction ratio is reduced.

Titanium (Ti) ultra-low carbon steel sheets are mainly used in iron-based materials in the processing of multi-stage deep drawing processes in the case of motor cases. The Ti-added ultra-low carbon steel sheet has a material having a small amount of solid solution carbon which suppresses the effect of the generation of the longitudinal crack, and therefore is particularly prone to cause a longitudinal crack due to embrittlement. When the drawing is performed without leaving a flange during re-drawing after the first stretching as in Patent Document 1, the flange reduction ratio becomes large at the stage before the thinning process is performed. The value of the result is embrittled to produce a longitudinal crack. Further, it can be understood that the flange edge corresponding to the length of the flange portion is further bent to be spread, thereby imparting a large tensile stress, which is an adverse effect against the longitudinal crack.

Further, the multi-stage stretching processing method of Patent Document 1 is feasible because the material is an aluminum alloy which does not cause embrittlement. The same method cannot be applied when the material is an iron-based material.

[Previous Technical Literature]

[Patent Literature]

Patent Document 1: Japanese Laid-Open Patent Publication No. SHO 59-178139.

[Non-patent literature]

Non-Patent Document 1: Nakagawa Weixiong and the other two were working on the "pressing of thin sheets", the fifth printing, Shijiao Publishing Co., Ltd., August 20, 1985, p. 150 to p.

In the above-described conventional method for producing a formed material, by forming a molded material having a tubular body portion and a flange portion formed at an end portion of the body portion by a drawing process, the flange diameter is smaller than the blank diameter. .

The flange end portion is embrittled while being work hardened due to the reduced diameter. As the degree of processing becomes larger, that is, as the reduction ratio of the flange becomes larger, the degree of embrittlement becomes larger. Therefore, the larger the blank diameter, the smaller the flange diameter of the molded material after the multi-stage drawing processing (the flange diameter of the formed material before trimming), and the more embrittled. Therefore, in the multi-stage deep drawing process of the formed product having a large flange diameter reduction ratio, the longitudinal crack which often occurs from the flange end portion sometimes becomes a problem.

The present invention has been made to solve the above problems, and an object of the invention is to provide a method for producing a molded material which can prevent longitudinal cracking at an end portion of a flange and the molded material.

In the case of performing multi-stage deep drawing processing, it is preferable to be able to withstand the bending and straightening of the shoulder of the die after re-stretching, and In the initial stretching (first stretching) of the material metal sheet itself, molding is performed under mild conditions in such a manner as to exert an unnecessary burden on the material. That is, in the first stretching, the gap between the die and the punch, that is, the clearance of the die, is usually set to 1.15 times to 1.25 times the thickness of the material to be formed.

Here, in the case of forming a relatively large flange like a motor casing, the portion corresponding to the flange portion can be pulled in the re-stretching after the first stretching, and the The portion remains as a flange and is formed. This means that the portion corresponding to the flange portion is not subjected to bending and straightening of the shoulder of the die after re-stretching. In this way, after the re-stretching, the portion corresponding to the flange portion is not pulled in, and the portion remains as a flange, so that the damage caused by the processing is hardly caused, and the situation is focused on In the first stretching, the case where the portion corresponding to the flange portion was thinned was examined.

In the method for producing a formed material according to the present invention, a material having a cylindrical main body portion and a flange portion formed at an end portion of the main body portion is produced at least twice by at least two forming operations on the material metal plate. The forming process includes at least one drawing process and at least one drawing process performed after the drawing process, and the drawing process is performed using a die including a die having a press-in hole and a punch, so that the punch is performed The width of the end side is wider than the width of the front end side, whereby the interval between the die and the punch in a state where the punch is pressed into the press-fitting hole of the die is narrower on the rear end side than the front end side , Ladaga In the work, the material metal plate and the punch are pressed together into the press-in hole, thereby thinning the area corresponding to the flange portion of the material metal plate.

Further, the molding material of the present invention is produced by at least two forming processes on a material metal plate, and the molding material has a tubular body portion and a flange portion formed at an end portion of the body portion, at least two The secondary forming process includes at least one drawing process and at least one drawing process performed after the drawing process, and thinning the region corresponding to the flange portion of the material metal plate in the drawing process. The thickness of the flange portion is made thinner than the thickness of the peripheral wall of the body portion.

Further, the molding material of the present invention is produced by at least two forming processes on a material metal plate, and the molding material has a tubular body portion and a flange portion formed at an end portion of the body portion, at least two The secondary forming process includes at least one drawing process and at least one drawing process performed after the drawing process, and thinning the region corresponding to the flange portion of the material metal plate in the drawing process. The thickness of the flange portion is made thinner than the thickness of the material metal plate.

According to the method of manufacturing a formed material of the present invention and the formed material, the material metal plate is introduced into the press-in hole together with the punch in the drawing process, thereby thinning the area corresponding to the flange portion of the material metal plate machining. In the subsequent re-stretching process, the thinned portion is left as a flange and is not to be Since the thinned portion is drawn and processed, the flange diameter is increased by the compression of the flange end portion, the increase in the thickness of the flange, and the embrittlement of the work hardening, and the flange reduction ratio can be reduced. It can prevent the occurrence of longitudinal cracks. This configuration is particularly useful for various application objects represented by a molded material formed by multi-stage deep drawing processing such as a motor casing.

1‧‧‧Formed materials

2‧‧‧Material sheet metal

3‧‧‧Mold

4‧‧‧Mold

10‧‧‧ Body Department

11‧‧‧Flange

20‧‧‧First Intermediate

21‧‧‧Second intermediate

22‧‧‧ Third intermediate

23‧‧‧ Fourth Intermediate

30‧‧‧Mold

30a‧‧‧Indented hole

31‧‧‧ Punch

31a‧‧‧Width Change Department

32‧‧‧ cushion

40‧‧‧Mold

40a‧‧‧ pressed into the hole

41‧‧‧ Punch

42‧‧‧ stretching sleeve

100‧‧‧ top wall

101‧‧‧Walls

310‧‧‧ front end of the punch

311‧‧‧End side of the punch

C _30-31 ‧‧‧Mold gaps, intervals

Rd‧‧‧ lower shoulder

Rp‧‧‧ upper shoulder

t ₁₁ ‧‧‧Shelf thickness of the flange

t ₁₀₁ ‧‧‧The thickness of the wall

W ₃₁₀ ‧‧‧Width of the front side of the punch

W ₃₁₁ ‧‧‧Width of the end side after the punch

Fig. 1 is a perspective view showing a molded material produced by the method for producing a molded material according to the first embodiment of the present invention.

Figure 2 is a cross-sectional view taken along line II-II of Figure 1.

Fig. 3 is an explanatory view showing a method of manufacturing a molded material for producing the formed material of Fig. 1;

Fig. 4 is an explanatory view showing a mold used for the drawing process of Fig. 3.

Fig. 5 is an explanatory view showing a drawing process using the mold of Fig. 4.

Fig. 6 is an explanatory view showing the punch of Fig. 4 in more detail.

Fig. 7 is an explanatory view showing a mold used for the first drawing process of Fig. 3.

Fig. 8 is an explanatory view showing a first drawing process using the mold of Fig. 7.

Fig. 9 is a graph showing the plate thickness distribution of the produced formed material.

Fig. 10 is an explanatory view showing a position at which the thickness distribution of Fig. 9 is measured.

Fig. 11 is a graph showing the relationship between the thinning ratio and the flange diameter of the formed product before trimming.

Figure 12 shows the flange reduction ratio of the formed product and the formed product before trimming. Diagram of the relationship.

Hereinafter, the form for carrying out the invention will be described with reference to the drawings.

Embodiment 1.

Fig. 1 is a perspective view showing a molded material 1 produced by the method for producing a molded material according to the first embodiment of the present invention. As shown in FIG. 1, the molded material 1 manufactured by the method for producing a molded material of the present embodiment has a main body portion 10 and a flange portion 11. The body portion 10 is a cylindrical portion having a top wall 100 and a peripheral wall 101 extending from the outer edge of the top wall 100. The top wall 100 differs depending on the orientation in which the formed material 1 is used, and other names such as a bottom wall may be used. In FIG. 1, the main body portion 10 has a substantially circular cross section, but the main body portion 10 may have other shapes such as a cross-sectional ellipse or a rectangular tube shape. For example, the top wall 100 may be further processed by forming a protrusion or the like that protrudes further from the top wall 100. The flange portion 11 is a plate portion formed at an end portion (an end portion of the peripheral wall 101) of the main body portion 10.

2 is a cross-sectional view taken along line II-II of FIG. 1. 2, the thickness of the flange portion 11 of the line ₁₁ to the thickness T 10 of the peripheral wall 101 of the T ₁₀₁ is thinner than the main body portion. This is because the details of the region corresponding to the flange portion 11 of the material metal plate 2 (see FIG. 3) are thinned as will be described later. In addition, the thickness t _{11 of the} flange portion 11 refers to a flange portion from the lower end of the lower shoulder portion Rd between the peripheral wall 101 and the flange portion 11 to the outer end of the flange portion 11. The average value of the plate thickness of 11. Similarly, the plate thickness t ₁₀₁ of the peripheral wall 101 means the average value of the thickness of the peripheral wall 101 from the upper end of the lower shoulder portion Rd to the lower end of the upper shoulder portion Rp.

Next, Fig. 3 is an explanatory view showing a method of manufacturing a molded material for producing the formed material 1 of Fig. 1. In the method for producing a molded article of the present invention, the formed material 1 is produced by at least two forming processes of the flat material metal plate 2. At least one drawing process and at least one drawing process performed after the drawing process are included in at least two forming processes. In the method for producing a molded article according to the present embodiment, the molded material 1 is produced by one drawing process and four times of re-stretching (first stretching process to fourth drawing process). The drawing process performs the initial processing on the material metal plate 2 itself, and the four re-stretching processes are sequentially processed after the drawing process.

In the drawing process, a first intermediate body 20 having a bottomed cylindrical shape is formed. In the first stretching process to the third drawing process, the second intermediate body 21 to the fourth intermediate body 23 having the flanges are formed. The formed material 1 is obtained by subjecting the fourth intermediate body 23 obtained by the third drawing process to a fourth drawing process.

Here, it is important that the height (depth) of the main body portion is increased without changing the flange diameter in the first to fourth stretching processes as the re-stretching process. In other words, in the re-stretching process, the end portion (flange portion) of the main body portion formed by the drawing process is not subjected to bending and straightening, and only the portion other than the end portion of the main body portion is bent and straightened. machining. Assumption When two or more drawing processes are performed, the bending and straightening processing is performed on the end portion of the main body portion obtained for the first time, so that the second and subsequent drawing processes are not included in the re-stretching. In the first stretching process to the fourth drawing process, the flange which is close to the flange diameter of the final product is left as much as possible. In particular, in the case of re-stretching, the drawing is pulled into the flange with a smaller diameter than the flange diameter of the final product, which leads to an increase in the reduction ratio of the flange and must be extended to the final product in a subsequent step. The flange diameter. The increase in the flange reduction ratio and the expansion in the subsequent steps induce longitudinal cracks, which is not preferable.

As the material metal plate 2, a metal plate composed of a metal having a body-centered cubic structure can be used. Specific examples of the material metal plate 2 include a cold-rolled steel sheet, a ferritic stainless steel sheet, and a plated steel sheet using these steel sheets as the original sheets.

4 is an explanatory view showing a mold 3 used for the drawing process of FIG. 3, and FIG. 5 is an explanatory view showing a drawing process using the mold 3 of FIG. As shown in FIG. 4, the mold 3 for drawing processing includes a die 30, a punch 31, and a cushion 32. The die 30 is provided with a press-fitting hole 30a into which the material metal plate 2 and the punch 31 are pressed together. The cushion 32 is disposed at an outer circumferential position of the punch 31 so as to face the outer end surface of the die 30. As shown in FIG. 5, in the drawing process, the outer edge portion of the material metal plate 2 is not completely restrained by the die 30 and the cushion pad 32, and is pulled until the outer edge portion of the material metal plate 2 is separated from the die 30. And the constraint of the cushion 32. Can also The entire material metal plate 2 is pressed into the press-fitting hole 30a together with the punch 31 to perform drawing.

Next, Fig. 6 is an explanatory view showing the punch 31 of Fig. 4 in more detail. As shown in FIG. 6, the width w ₃₁₁ of the end side 311 after the punch 31 for drawing is set to be wider than the width w ₃₁₀ of the front end side 310 of the punch 31. On the other hand, the width of the press-fitting hole 30a is substantially uniform along the insertion direction of the punch 31 to the press-fitting hole 30a. In other words, the inner wall of the die 30 extends substantially parallel to the insertion direction of the punch 31.

That is, the interval C _30-31 between the die 30 and the punch 31 in a state where the punch 31 is pressed into the press-fitting hole 30a as shown in Fig. 6 is set to the rear end side of the punch 31. The 311 is narrower than the front end 310 of the punch 31. The interval C _30-31 between the end faces 311 of the punch 31 is set to be narrower than the plate thickness of the material metal plate 2 before the drawing process. Thereby, by pressing the material metal plate 2 together with the punch 31 into the press-fitting hole 30a in the drawing process, the outer edge portion of the material metal plate 2, that is, the area corresponding to the flange portion 11 is thereby Perform thinning. By thinning, the thickness of the region corresponding to the flange portion 11 is reduced, and the material is stretched.

Further, between the end side 310 and the rear end side 311 of the punch 31, a width changing portion 31a composed of an inclined surface in which the width of the punch 31 continuously changes is provided. The width changing portion 31a is disposed in such a manner that the material metal plate 2 and the punch 31 are pressed together into the press-in hole 30a in the drawing process. In the middle, the width changing portion 31a and the inner wall of the die 30 are in contact with the region of the material metal plate 2 corresponding to the lower shoulder portion Rd (see Fig. 2).

Next, Fig. 7 is an explanatory view showing a mold 4 used for the first drawing process of Fig. 3, and Fig. 8 is an explanatory view showing a first drawing process using the mold 4 of Fig. 7. As shown in FIG. 7, the mold 4 for the first drawing process includes a die 40, a punch 41, and a stretching sleeve 42. The die 40 is provided with a press-fitting hole 40a into which the first intermediate body 20 formed by the above-described drawing process is pressed together with the punch 41. The stretching sleeve 42 is disposed at an outer circumferential position of the punch 41 so as to face the outer end surface of the die 40. As shown in FIG. 8, in the first drawing process, the region corresponding to the body portion 10 of the first intermediate body 20 is subjected to drawing processing, and the first intermediate portion is restrained by the die 40 and the stretching sleeve 42 The flange portion 11 is formed at the outer edge portion of the body 20. Further, the purpose of the sleeve 42 is to prevent generation of wrinkles during stretching, and may be omitted when wrinkles are not generated.

Although not shown, the second drawing process and the third drawing process of FIG. 3 can be carried out using a well-known mold. In the second stretching process, the region corresponding to the main body portion 10 of the second intermediate body 21 (see FIG. 3) formed by the first drawing process is subjected to drawing processing. The third drawing process performs a thinning process on the region corresponding to the main body portion 10 of the third intermediate body 22 (see FIG. 3) formed by the second drawing process. The fourth drawing process corresponds to a restrike step of thinning the region corresponding to the main body portion 10 of the fourth intermediate body 23 (see FIG. 3) formed by the third drawing process.

In the first stretching process to the fourth drawing process, a compressive stress due to shrinkage deformation occurs in a region corresponding to the flange portion 11 corresponding to a decrease in the flange diameter, and thickening occurs in the region. . However, by sufficiently reducing the thickness of the region corresponding to the flange portion 11 in the drawing process in advance, the flange diameter can be increased in the formed material 1 which is subjected to the re-stretching process, and the first step can be reduced. The flange reduction ratio obtained by the formula.

At the same time, in the formed material 1 in which the re-stretching is completed, the thickness t _{11 of} the rough-diameter flange portion 11 is made thinner than the thickness t ₁₀₁ of the peripheral wall 101 of the main body portion 10.

The amount of stretching of the material corresponding to the region of the flange portion 11 in the drawing process can be appropriately adjusted by changing the interval C _{30-31 of the} end side 311 of the punch 31 of the die 3 for drawing.

That is, the first intermediate body 20 (refer to FIG. 3) can be formed higher by thinning the outer edge portion (the region corresponding to the flange portion 11) of the material metal plate 2 in the drawing process. (deep). Further, in the re-stretching process, the outer edge portion of the thinned material metal plate 2 is not processed, and the outer edge portion is left as a flange. Although the diameter of the flange is slightly reduced in the re-stretching, the outer edge portion of the material metal plate 2 is thinned in advance, that is, by ensuring that the area remaining as the flange is wide, the aforementioned The flange reduction ratio obtained by the first formula.

The examples are enumerated. The inventors of the present invention prepared a circular plate having a thickness of 1.8 mm, a diameter of 118 mm, and a length of 112 mm which was subjected to Zn-Al-Mg plating on a cold-rolled steel sheet of ordinary steel as a material metal plate 2. Then, the drawing process is first performed under the following processing conditions. Here, the Zn-Al-Mg alloy plating is applied to both surfaces of the steel sheet, and the adhesion amount by plating is 90 g/m ² per one surface.

. The thinning ratio corresponding to the region of the flange portion 11 is -20% to 60%.

. The radius of curvature of the mold 3: 6 mm.

. The diameter of the press-in hole 30a is 70 mm.

. The diameter of the front end side 310 of the punch 31 is 65.7 mm.

. The diameter of the end side 311 after the punch 31 is 65.7 mm to 68.6 mm.

. The shape of the width changing portion 31a: an inclined surface or a right angle step.

. The position of the width changing portion 31a is a region corresponding to the lower shoulder portion Rd, a region corresponding to the flange portion 11, or a region corresponding to the body portion 10.

. Press oil: TN-20.

. SKD11 (HRC60) is used for both the die and the punch.

<Evaluation of thinning rate>

When the thinning ratio is 30% or less (the diameter of the end side 311 after the punch 31 is 67.5 mm or less), the processing is performed without any problem. On the other hand, when the thinning ratio is more than 30% and 50% or less (when the diameter of the end side 311 of the punch 31 is larger than 67.5 mm and 68.2 mm or less), it is confirmed to be slight with the sliding portion of the die 30. Scratch. Further, in the case where the thinning ratio exceeds 50% (when the diameter of the end side 311 of the punch 31 is larger than 68.2 mm), burning or cracking with the inner wall of the die 30 occurs. From this, it is understood that the thinning ratio of the region corresponding to the flange portion 11 in the drawing process is preferably 50% or less, and more preferably 30% or less. However, the scratching can be improved by performing a ceramic coating treatment or the like on the die or the punch, and thus it is not a big problem. Further, the 50% thinning rate can be set as 50% of the thickness of the material metal plate by the interval C _30-31 between the punch 31 and the die 30 which is to be thinned (refer to FIG. 6). And reached. Similarly, a 30% thinning ratio can be achieved by setting the mold gap C _30-31 to 70% of the sheet thickness of the material metal sheet.

<shrinkage rate>

Furthermore, the definition of the thinning ratio is set as follows (the second formula). At this time, the value of the plate thickness of the material metal plate can be used as the plate thickness before the thinning process.

<Evaluation of the shape of the width changing portion 31a>

When the width changing portion 31a is formed by the inclined surface as shown in Fig. 6, the processing can be performed without any problem. On the other hand, when the width changing portion 31a is formed by the right-angle step, that is, the front end side 310 and the rear end side 311 of the punch 31 are formed by the step difference of the first step, the contact with the right-angle step is performed. Plated slag is produced in the part. From this, it is preferable to form the width changing portion 31a by the inclined surface.

<Evaluation of the position of the width changing portion 31a>

When the width changing portion 31a is provided in contact with the region corresponding to the lower shoulder portion Rd, the thinning processing corresponding to the region of the flange portion 11 can be favorably performed. On the other hand, when the width changing portion 31a is provided in contact with the region corresponding to the flange portion 11, one of the flange portions 11 cannot be sufficiently thinned. Further, when the width changing portion 31a is provided in contact with the region corresponding to the main body portion 10, one portion of the main body portion 10 becomes thinner than the target plate thickness. From this, it is preferable to provide the width changing portion 31a so as to be in contact with the region corresponding to the lower shoulder portion Rd.

In addition, the position of the width changing portion 31a is determined by the mold condition at the time of mass production, and the molding until the completion of the re-stretching of the molding material is performed in advance, and corresponds to the lower side shoulder portion Rd of the molding material. The position is back calculated and decided.

Furthermore, FIG. 9 is a graph showing the thickness distribution of the molded material 1 which is subjected to the re-stretching process. Fig. 10 is an explanatory view showing the measurement position of the plate thickness of Fig. 9;

According to the method for producing a molded material of the present invention, the drawing process is performed before the re-stretching process, and the region corresponding to the flange portion is thinned. As a result, the measurement position of the flange portion of the molded material is 90 mm or more. The plate thickness of the portion is smaller than the formed material formed by the conventional ordinary stretching method. In other words, it is known that the thickness of the flange portion 11 can be reduced in the final molded material 1 by performing the drawing process with the thinning before the drawing process, and the portion corresponding to the flange portion can be made. Length extension.

<Evaluation of longitudinal cracks>

Next, Table 1 shows the flange diameter, the flange reduction ratio, and the longitudinal crack evaluation of the molding material which changes the thinning ratio in the drawing process. In addition, Table 2 shows the dimensions of the punch used in each step of the re-stretching process.

[Table 2]

In addition, FIG. 11 is a view showing the relationship between the thinning ratio and the flange diameter of the formed material which is subjected to the re-stretching process. Further, Fig. 12 is a view showing the relationship between the thinning ratio and the flange reduction ratio of the formed material which is subjected to the re-stretching process. As is apparent from Fig. 11 and Fig. 12, the larger the thinning ratio in the drawing process, the larger the flange diameter of the formed material which is subjected to the re-stretching processing, and the smaller the flange reduction ratio.

Further, in this embodiment, in order to carry out the evaluation of the promotion of the longitudinal crack, the longitudinal end of the blank was artificially imparted with a metal trowel.

In Comparative Example 1 of Table 1, the thinning ratio in the drawing process was set to -20%, the flange reduction ratio was as large as 0.45, and the longitudinal crack generation rate was also as high as 30%. However, in Inventive Example 2 in which the thinning ratio was set to 0%, the flange reduction ratio was 0.42, and the longitudinal crack generation rate was rapidly lowered to 3%. Further, as shown in Inventive Example 4 to Inventive Example 7, by giving a thinning ratio of 12% or more, the occurrence of longitudinal cracking can be completely suppressed.

In addition, the thinning ratio of the comparative example 1 is -20%, and the die gap C _30-31 (see FIG. 6) of the punch and the die in the drawing process is set to 1.2 times the thickness of the material plate. . At this time, the area corresponding to the flange after the drawing process was 120% thick with respect to the thickness of the material plate. Similarly, the thinning ratio of the invention example 2 is 0%, and the interval C _30-31 (see FIG. 6) is set to be the same as the material thickness. At this time, the increase in the thickness of the flange due to the drawing process is eliminated by the thinning process. From this, it is preferable that the interval C _30-31 (see FIG. 6) between the punch 31 and the die 30 which is to be thinned is set to be 100% or less of the thickness of the material metal plate.

Further, in this embodiment, as described above, in order to carry out the evaluation of the promotion of the longitudinal crack, the metal trowel is used to artificially impart longitudinal damage to the end face of the blank. Even if the thinning process of 0% or more is applied to the drawing process as shown in the invention example 2 or the invention example 3, the longitudinal crack can be suppressed almost. In other words, it is considered that the longitudinal crack can be completely suppressed practically by setting the thinning ratio to 0% or more.

When the thinning ratio was set to 60% as in Comparative Example 8, the forming force in the step of the first drawing process exceeded the breaking force of the shoulder of the punch, causing breakage (α-break) at the shoulder of the punch. Further, as in Comparative Example 9, the thinning ratio in the drawing process was set to 0%, and when the drawing process was also performed in the two steps, the longitudinal crack occurred when the flange diameter was enlarged in the three steps.

Inventive Example 10 is a formed material obtained by drawing a 50% thinning ratio. On the other hand, Comparative Example 1 is a molded material which has a thinning ratio of -20% and is subjected to drawing processing without a thinning process. The flange diameters of these formed materials are all the same. At this time, the blank diameter of Inventive Example 10 was 112 mm, which was smaller than the blank diameter of Comparative Example 1 of 118 mm. As a result, the flange reduction ratio of the invention example 10 is small, and the occurrence of the longitudinal crack can be prevented.

Further, the blank diameter was reduced by performing the thinning process, and as a result, the weight of the molded material of Inventive Example 10 was about 10% smaller than that of Comparative Example 1.

Further, when the drawing process is performed with thinning, the region corresponding to the flange portion 11 of the material metal plate 2 is stretched. In order to perform the re-stretching of the formed material 1 (for example, the invention example 10) which is subjected to the drawing process with the thinning, and the formed material 1 (for example, the comparative example 1) which is not subjected to the drawing process with the thinning. The flange diameter of the formed material is the same size, and it is only necessary to use a small material metal plate 2 or an unnecessary portion of the flange portion 11 in consideration of the amount of the flange portion 11 to be stretched.

In the method of manufacturing such a formed material and the formed material 1, the material metal plate 2 and the punch 31 are introduced into the press-fitting hole 30a together in the drawing process, and the material metal plate 2 is equivalent to the convex material. The area of the edge portion 11 is thinned. In the subsequent re-drawing process, the thinned portion is left as a flange, and the thinned portion is not pulled and processed, so that the thickness of the flange is hardly increased or The embrittlement of the work hardening increases the flange diameter, and the flange reduction ratio can be reduced, and as a result, the occurrence of the longitudinal crack can be prevented. This configuration is particularly useful for an application object formed by a multi-stage deep drawing process such as a motor casing.

Further, since the interval between the portions to be thinned in the drawing process is 50% or more and 100% or less of the thickness of the material metal plate, the occurrence of burning or cracking can be avoided.

Further, a width changing portion 31a formed by an inclined surface in which the width of the punch 31 continuously changes is provided between the front end side 310 and the rear end side 311 of the punch 31, so that the width and the width of the thinning process can be avoided. The plating slag is generated by the contact of the changing portion 31a.

Further, since the width changing portion 31a is disposed in contact with a region corresponding to the lower shoulder portion Rd formed between the peripheral wall 101 of the main body portion 10 and the flange portion 11, the flange portion 11 can be sufficiently thinned. And the body portion 10 can be made into a target plate thickness more reliably.

In addition, first, a thinning process is performed as a drawing process, and in the subsequent re-stretching process, the portion subjected to the thinning process is not pulled in, and the portion is left as a flange portion and subjected to multi-stage deep drawing. Therefore, it is hardly subject to the brittleness caused by the bending and straightening processing in the multi-stage deep drawing process, and the reduction in the flange reduction ratio can be achieved. Further, in the drawing process, the thinning rate of the thinning process corresponding to the portion corresponding to the flange portion is set to 0% or more and 50% or less, and the flange reduction ratio is set to 0.42 or less, so that there is no such Since the flange end face is excessively thickened by the multi-stage deep drawing process and is brittle, the occurrence of the longitudinal crack can be prevented.

In the present embodiment, the second step to the sixth step are performed five times of re-stretching, but the number of times of re-stretching may be appropriately determined according to the size of the formed material 1 or the required dimensional accuracy. change.

1‧‧‧Formed materials

10‧‧‧ Body Department

11‧‧‧Flange

100‧‧‧ top wall

101‧‧‧Walls

Claims (11)

A method for producing a formed material by forming at least two of a tubular body portion and a flange portion formed at an end portion of the body portion by at least two forming processes on the material metal plate; The secondary forming process includes at least one drawing process and at least one drawing process performed after the drawing process; the drawing process is performed using a die including a die having a press-in hole and a punch; The width of the end side of the punch is wider than the width of the front end side, whereby the interval between the die and the punch in a state where the punch is pressed into the press-fitting hole of the die is the aforementioned The rear end side is narrower than the front end side; in the drawing process, the material metal plate is pressed into the press-fitting hole together with the punch, thereby corresponding to the flange portion of the material metal plate The area is thinned. The method for producing a molded article according to claim 1, wherein the interval at which the thinning is performed is 50% or more and 100% or less of a thickness of the material metal plate. The method for producing a molded article according to claim 1 or 2, wherein a width changing portion formed by an inclined surface in which the width of the punch continuously changes is provided between the end side and the rear end side of the punch. The method of manufacturing a molded article according to claim 1 or 2, wherein the width changing portion is disposed in contact with a region corresponding to a shoulder formed between a peripheral wall of the main body portion and the flange portion. The method of producing a molded article according to claim 1 or 2, wherein the thickness of the flange portion of the molded material is smaller than the thickness of the material metal plate. The method for producing a molded article according to claim 1 or 2, wherein in the at least one stretching process, the end portion of the body portion formed by the drawing is not bent and straightened, thereby The end portion of the main body portion formed by the drawing process remains as a flange portion. A molding material produced by at least two forming processes of a material metal plate, wherein the molding material has a cylindrical body portion and a flange portion formed at an end portion of the body portion, at least twice The forming process includes at least one drawing process and at least one drawing process performed after the drawing process; and the thinning process is performed on the region corresponding to the flange portion of the material metal plate in the drawing process, Thereby, the thickness of the flange portion is made thinner than the thickness of the peripheral wall of the main body portion. A molding material produced by at least two forming processes of a material metal plate, wherein the molding material has a cylindrical body portion and a flange portion formed at an end portion of the body portion, at least twice The forming process includes at least one drawing process and at least one drawing process performed after the drawing process; In the drawing process, a region corresponding to the flange portion of the material metal plate is thinned, whereby the thickness of the flange portion is made thinner than the thickness of the material metal plate. The formed material according to claim 7 or 8, wherein the material metal plate is a metal of a body-centered cubic structure. The molding material according to claim 7 or 8, wherein the flange reduction ratio obtained by the flange diameter of the molding material and the diameter of the material metal plate is 0.42 or less. The formed material according to claim 7 or 8, wherein the thickness of the flange portion of the formed material is smaller than the thickness of the flange portion of the formed material obtained by drawing the same material metal sheet without drawing.