Ironing punch and method for manufacturing thin-walled metal cylinder using said punch

Abstract

To provide a punch for ironing which is excellent in drawability after ironing.SOLUTION: In a punch 1 for ironing used for ironing of a metal, dot-shaped recesses 3 are distributed on an outer peripheral surface 1a of the punch 1, and a raised section 5 is formed at a peripheral edge part of each dot-shaped recess 3.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an ironing punch used in ironing, and further to a method for producing a thin-walled metal cylinder by ironing using the ironing punch. [Background technology]

[0002] Ironing is a severe plastic processing method used to thin metals. It is used to manufacture thin-walled, high-height cylindrical metal bodies (thin-walled cylindrical metal bodies), such as thin-walled seamless cans. This ironing process involves passing a hollow metal body through a narrow space between an annular die and a rod-shaped punch. Specifically, the punch is inserted into the metal body to be thinned, and the metal body is sandwiched between the punch and the annular die. The punch and the annular die are then moved (slid) relative to each other to thin the metal body. For example, Patent Documents 1 and 2 disclose techniques for manufacturing seamless cans (drawn and ironed cans) using this ironing process.

[0003] In this ironing process, the punch must be removed from the thinned metal cylindrical body after the ironing process is completed. The problem here is that in the ironing process, the metal cylindrical body, which is the workpiece, is strongly pressed against the outer circumferential surface of the punch, which causes large frictional resistance and makes it difficult to remove the punch smoothly, resulting in low productivity and, in some cases, in problems such as damage to the inner surface of the formed metal cylindrical body during removal. The reality is that little research has been done on the pullability of the punch during such ironing.

[0004] For example, Patent Document 3 discloses a seamless metal can having a thermoplastic resin layer formed on the inner surface, in which numerous dot-like protrusions are formed in the thermoplastic resin layer on the inner surface. This technology alleviates the molecular orientation of the thermoplastic resin layer caused by the ironing process by forming the dot-like protrusions, thereby suppressing a decrease in dent resistance caused by the molecular orientation in the thermoplastic resin layer. That is, in Patent Document 3, to form the dot-like protrusions in the thermoplastic resin layer on the inner surface of the can, the ironing process is performed using a punch having dot-like recesses formed on the outer periphery. As can be seen from this, Patent Document 3 also does not consider at all the pull-out properties of the ironing punch. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] WO2017 / 033791 [Patent Document 2] Patent Publication No. 2018-69256 [Patent Document 3] Patent No. 3327137 Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an ironing punch that has excellent drawability after ironing. Another object of the present invention is to provide a method for producing a thin-walled metal cylinder by ironing using the above ironing punch. [Means for solving the problem]

[0007] According to the present invention, there is provided an ironing punch for use in ironing metal, The outer peripheral surface of the punch is provided with a diameter of 0.2 mm formed by plastic deformation. ~1.1 mm, and its depth is 0.2~10.0 μmThere is provided an ironing punch having dot-shaped recesses distributed therein, and having raised portions formed on the periphery of the dot-shaped recesses due to plastic deformation of the dot-shaped recesses.

[0008] According to the present invention, there is also provided a method for manufacturing a thin-walled metal cylinder, characterized in that the thin-walled metal cylinder is obtained by ironing the metal cylinder using the above-mentioned ironing punch.

[0009] In the production method of the present invention, (1) The metal cylindrical body to be subjected to the ironing process is a laminate having an organic resin coating on the inner surface of a metal substrate. (2) The organic resin coating is formed from a thermoplastic resin. (3) The metal cylinder to be subjected to the ironing process is a bottomed cylinder, and the thinned metal cylinder is a seamless can. is preferred. According to the present invention, furthermore, in a manufacturing method of an ironing punch used in ironing a metal, the outer peripheral surface of the ironing punch is struck using a jig to be recessed by plastic deformation, thereby forming a recess on the outer peripheral surface of the ironing punch. The diameter is 0.2 to 1.1 mm and the depth is 0.2 to 10.0 μm. A method for manufacturing an ironing punch is provided, which is characterized by forming recesses distributed in a dot pattern and forming raised portions on the peripheries of the recesses. [Effects of the Invention]

[0010] The ironing punch of the present invention has dot-shaped recesses distributed on its outer peripheral surface, and is characterized in that raised portions are formed on the peripheries of these dot-shaped recesses. That is, when a metal cylinder is ironed using a punch having dot-shaped recesses distributed in the manner described above, convex portions corresponding to the dot-shaped recesses are formed on the inner peripheral surface of the metal cylinder as the metal cylinder is thinned by the ironing process. However, when the punch is removed after ironing, the pressure between the outer surface of the punch and the inner peripheral surface of the metal cylinder is alleviated by the raised portions around the dot-shaped recesses. As a result, the ironing punch can be easily removed, ensuring high productivity. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram for explaining thinning of a workpiece (metallic cylindrical body) by ironing. [Figure 2] 1 is a partially enlarged schematic vertical cross-sectional view showing the engagement relationship between the outer peripheral surface of the ironing punch of the present invention and the inner peripheral surface of a thin-walled workpiece (metallic cylindrical body). [Figure 3] 3 is a partially enlarged schematic plan view of the outer peripheral surface of the ironing punch shown in FIG. 2. [Figure 4] 3 is a partially enlarged schematic plan view of the inner peripheral surface of the workpiece (metallic cylindrical body) shown in FIG. 2. [Figure 5] 1 is a schematic vertical cross-sectional view showing the positional relationship between the ironing punch and the thinned seamless can at the end of ironing when the workpiece is a metal seamless can. FIG. [Figure 6] 10A and 10B are diagrams for explaining the form of rollback that occurs when the ironing punch is withdrawn. [Figure 7] FIG. 1 is a diagram showing an example of a press forming process using ironing. [Figure 8] FIG. 10 is a diagram showing an example of a forming process when ironing is performed in multiple stages. DETAILED DESCRIPTION OF THE INVENTION

[0012] <About ironing> Ironing is known as a representative technique for plastic processing of metals and is widely used, for example, to manufacture thick, thin-walled seamless metal cans. As shown in Figure 1, ironing involves moving a workpiece, a metal cylindrical body B, in the processing direction with an ironing punch (ironing punch) A, while pressing an ironing die C against and rubbing the outer surface of the cylindrical body B, thereby thinning the wall of the cylindrical body B. Therefore, in this ironing process, the inner surface of the metal cylindrical body B is firmly pressed against the outer surface of the ironing punch A.

[0013] In this type of ironing process, the ironing rate is expressed by the following formula, where t0 is the thickness of the metal cylindrical body before ironing and t1 is the thickness after ironing. The higher this ironing rate, the greater the surface pressure applied to the ironing die C and punch A, resulting in severe forming. Squeezing rate (%) = 100 × (t0-t1) / t0

[0014] The ironing punch A has a tubular (cylindrical) shape, is generally made of the same cemented carbide as the ironing die C described below, and is formed with a relatively thick wall so as not to deform during ironing. A drive shaft S (not shown in FIG. 1, but indicated by S in FIG. 5) for moving the punch A in the processing direction is connected to the inner surface of one end of the punch A (the upstream side in the processing direction in FIG. 1).

[0015] The metal constituting the metal cylinder B subjected to the ironing process may be any of a variety of metals or alloys, such as aluminum, copper, iron, or alloys containing these metals, or even surface-treated steel sheets such as tin-plated steel sheets or aluminum sheets that have undergone chemical conversion treatment. The inner peripheral surface of the metal cylinder B (the surface that comes into close contact with the outer peripheral surface of the ironing punch A) may be coated with a thermoplastic resin, for example, a polyester resin such as polyethylene terephthalate. Such a resin coating can prevent corrosion and scratches on the inner surface.

[0016] Furthermore, the ironing die C must be made of a fairly hard material because the surface pressure increases significantly as the ironing rate increases. Examples of such hard materials include cemented carbides obtained by sintering a mixture of tungsten carbide (WC) and a metal binder such as cobalt; cermets obtained by sintering a mixture of a metal carbide such as titanium carbide (TiC) or a titanium compound such as titanium carbonitride (TiCN) with a metal binder such as nickel or cobalt; and hard ceramics such as silicon carbide (SiC), silicon nitride (Si3N4), alumina (Al2O3), and zirconia (ZrO2). Furthermore, the working surface of such an ironing die C (the surface that comes into contact with the workpiece, i.e., the cylindrical body B) can be coated with a carbon film such as a diamond film. Such a carbon film can be formed by vapor deposition, such as CVD.

[0017] <Ironing punch and metal cylinder of the present invention> The above-mentioned ironing punch (hereinafter simply referred to as ironing punch) and the metal cylindrical body are in close contact with each other during ironing, and with this in mind, please refer to FIGS.

[0018] That is, the ironing punch 1 of the present invention, generally designated 1, has a large number of dot-shaped recesses 3 formed on its outer peripheral surface 1a, and a raised portion 5 formed around each of the dot-shaped recesses 3 (see particularly FIGS. 2 and 3). That is, the raised portion 5 is a portion that rises from the punch outer peripheral surface 1a around the recesses 3. As a result of the dot-shaped recesses 3 being formed on the outer peripheral surface 1a of the ironing punch 1, a large number of dot-shaped protrusions 15 are formed on the inner peripheral surface 11a of the thinned metal cylindrical body 11. That is, the dot-shaped protrusions 15 correspond to the dot-shaped recesses 3 formed on the ironing punch 1 (see particularly FIGS. 3 and 4).

[0019] After the ironing process is completed, the ironing punch 1 is inserted into the thinned metal cylindrical body 11, and the outer peripheral surface 1a of the ironing punch 1 is held in firm contact with the inner peripheral surface of the thinned metal cylindrical body 11. For example, in the example shown in Fig. 5, the metal cylindrical body 11 has a bottom 17 like a seamless can, and the ironing punch 1 extends to the bottom 17 of the cylindrical body 11. A region Q where the outer peripheral surface 11a of the ironing punch 1 contacts the inner peripheral surface of the metal cylindrical body 11 functions as a holding surface during the ironing process. Generally, a drive shaft S is connected to the ironing punch 1 above region Q. Drive of this shaft S moves the ironing punch 1 in the processing direction, and after the ironing process is completed, the ironing punch 1 is moved in the withdrawal direction, which is the opposite direction to the processing direction.

[0020] Therefore, after the ironing process is completed, the movement of the metal cylindrical body 11 in the height direction of the punch 1 is restricted by the stopper 20 so that the ironing punch 1 can be withdrawn. 5, when the metal cylinder 11 has a bottom 17, such as a can, assist air is blown in at the same time as the drive shaft S pulls it out, making it easy to pull out the ironing punch 1. When the metal cylinder 11 does not have a bottom 17, such as a hollow pipe, one end of the cylinder 11 (the end on the processing direction side) is formed with a small diameter so that the ironing punch 1 can firmly hold and move the metal cylinder 11, preventing the punch 1 from slipping out.

[0021] If the outer peripheral surface of the ironing punch 1 and the inner peripheral surface of the metal cylindrical body 11 were in complete contact with each other at the region Q when the ironing punch 1 was withdrawn from the post-ironing configuration shown in FIG. 5, frictional resistance would be extremely large, resulting in poor drawing efficiency and a decline in productivity. This would also cause roughening of the inner peripheral surface of the metal cylindrical body 11 (or peeling of a thermoplastic resin layer, if present). Furthermore, the load on the drive shaft S and other components would increase, shortening the life of the equipment. However, according to the present invention, numerous raised portions 5 are distributed on the outer peripheral surface 1a of the ironing punch 1, and the upper ends of these raised portions 5 are merely pressed against the inner peripheral surface 11a of the metal cylindrical body 11, significantly reducing the contact area between the two. As a result, frictional resistance is significantly reduced when the ironing punch 1 is withdrawn, allowing the ironing punch 1 to be withdrawn smoothly without applying a large load, resulting in extremely high ironing productivity.

[0022] In the present invention, the raised portions 5 formed on the outer peripheral surface 1a of the ironing punch 1 are formed by forming recesses 3 on this outer peripheral surface 1a through plastic deformation. That is, the recesses 3 are formed around the raised portions 5 by striking the outer peripheral surface 1a of the ironing punch 1 with a tool such as a punch. For example, Patent Document 3 (Japanese Patent No. 3327137) describes means for forming point-like recesses on the outer peripheral surface 1a of the ironing punch 1, such as ultrasonic machining, ion irradiation, laser machining, and electron beam irradiation (see paragraph

[0064] ). However, these means cannot form raised portions. This is because the recesses are formed by scraping, not by plastic processing.

[0023] The size (D2-D1) and height h of such raised portions 5 depend on the diameter D1 and depth d of the dot-shaped recesses 3, and to ensure that the raised portions 5 are not damaged during ironing, it is preferable that the diameter D1 of the dot-shaped recesses 3 is about 0.2 to 1.1 mm and the depth d is about 0.2 to 10.0 μm. Although this will vary somewhat depending on the material of the punch 1, by setting the diameter D1 and depth d of the dot-shaped recesses 3 within the above ranges, the size (D2-D1) and height h of the raised portions 5 will be appropriate, making it possible to avoid excessive forceful extraction and allowing the punch 1 to be extracted without causing unnecessary deformation of the metal cylindrical body 11, which is the workpiece.

[0024] For example, if the diameter D1 or depth d of the dot-shaped recesses 3 is outside the above range, the size (D2-D1) or height h of the raised portion 5 becomes unnecessarily large or small, resulting in a significant increase in the frequency of deformation (rollback) in which the upper opening of the metal cylindrical body 11 protrudes outward when the punch 1 is withdrawn. In other words, in an ideal configuration, the upper opening of the metal cylindrical body 11 is straight as shown in FIG. 6(a). However, if the punch 1 is withdrawn forcefully, rollback occurs in which the upper opening protrudes outward, as shown in FIG. 6(b). By setting the diameter D1 or depth d of the dot-shaped recesses 3 within an appropriate range, the occurrence of such rollback can be reduced to almost zero. If the diameter D1 or depth d is not within the appropriate range, or if the ironing process is performed using a punch 1 that does not have a raised portion 5 formed on the periphery of the dot-shaped recesses 3, the amount of rollback is likely to be 5.0 mm or more, and the frequency of such large rollbacks occurring may be 20 to 30 or more per 100 pieces.

[0025] Furthermore, it is preferable for the ironing punch 1 to be smoothly pulled out by distributing the raised portions 5 in the region Q of the ironing punch 1 so as to be uniformly distributed in the longitudinal and circumferential directions of the ironing punch 1. Furthermore, from the viewpoint of greatly reducing the frictional resistance without significantly reducing the strength of the punch 1, it is preferable to distribute the raised portions 5 in the region Q at a density of 30 to 400 portions / cm. 2It is desirable that the protrusions 5 are distributed in an area ratio of .

[0026] The planar shape of the dot-shaped recesses 3 is not particularly limited and may be circular, elliptical, rectangular, or the like, but this shape depends on the shape of the punch used to form the recesses 3, and a circular shape is particularly preferable. This is because a circular shape has no anisotropy and is the shape least likely to break during drawing.

[0027] Furthermore, the metal cylinder (workpiece) 11 obtained by ironing (thinning) using the ironing punch 1 as described above will have dot-shaped protrusions 15 formed on its inner surface 11a corresponding to the dot-shaped recesses 3 described above.

[0028] Thus, according to the present invention, by forming a large number of raised portions 5 on the outer peripheral surface of the ironing punch 1, ring-shaped recesses 13 are formed on the inner peripheral surface 11a of the metal cylindrical body 11 during the ironing process in correspondence with these raised portions 5, and as a result, frictional resistance when the ironing punch 1 is pulled out is greatly reduced.

[0029] <Press forming process using ironing> The ironing process using the ironing punch 1 described above is used to thin the walls of various metal cylindrical bodies 11, but is most preferably used in press molding to produce thin-walled, high-height metal cans (seamless cans). Figure 7 shows the manufacturing process for such metal cans.

[0030] 7, a blank (e.g., an aluminum plate) 101 used to form a metal can is first punched to obtain a disk 103 for the metal can (see FIG. 7(a)). One surface of this blank 101, particularly the side that will become the inside surface of the can, may be coated with an organic resin. The thickness of the base plate 101 varies depending on the type of metal, the purpose or size of the can, but is generally preferably 0.10 to 0.50 mm. In particular, in the case of a surface-treated steel plate, the thickness is preferably 0.10 to 0.30 mm, and in the case of a light metal plate such as aluminum, the thickness is preferably 0.15 to 0.40 mm.

[0031] Organic resin coatings include coatings derived from paints such as acrylic paints, urethane paints, silicone paints, and fluorine paints, as well as those derived from thermoplastic resins, and have been used conventionally for corrosion resistance and to suppress surface roughness during severe molding processes, etc. In the present invention, organic resin coatings formed from thermoplastic resins are particularly suitable.

[0032] That is, the thermoplastic resin coating can be easily laminated onto the base sheet 101 using a laminating roll, and the molecular orientation occurs through bending and stretching by drawing and ironing, thereby improving the barrier properties against corrosive components and heat resistance. On the other hand, as disclosed in Patent Document 3, the molecular orientation of the organic resin coating tends to cause the resin to fibrillate, which makes the can more susceptible to cracking in the height direction upon impact and tends to deteriorate dent resistance. However, in the present invention, dot-shaped protrusions 15 are formed on the inner surface of the can by ironing using a punch 1 having dot-shaped recesses 3, and these protrusions 15 mitigate the molecular orientation, preventing a decrease in dent resistance.

[0033] Examples of the thermoplastic resin include polyolefins such as low-density polyethylene, high-density polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, and random or block copolymers of α-olefins such as ethylene, propylene, 1-butene, and 4-methyl-1-pentene; ethylene-vinyl compound copolymers such as ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, and ethylene-vinyl chloride copolymer; styrene resins such as polystyrene, acrylonitrile-styrene copolymer, ABS, and α-methylstyrene-styrene copolymer; polyvinyl compounds such as polyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinylidene chloride copolymer, polymethyl acrylate, and polymethyl methacrylate; polyamides such as nylon 6, nylon 6-6, nylon 6-10, nylon 11, and nylon 12; thermoplastic polyesters such as polyethylene terephthalate and polybutylene terephthalate; polycarbonate; polyphenylene oxide; and mixtures thereof. Among these thermoplastic resins, polyester resins are particularly suitable in terms of processability, corrosion resistance, and ability to retain the flavor of the contents of the can.

[0034] The punching process uses a punch 105 having an outer diameter corresponding to the diameter of the disk 103, and a die 107 that holds the blank 101 and has an opening corresponding to the diameter of the disk 103. That is, the blank 101 held on the die 107 is punched out by the punch 105 to obtain a disk 103 of a predetermined size. Depending on the shape of the molded product to be produced in this manufacturing process, the blank 101 may be punched out into other shapes (for example, rectangular).

[0035] The disk 103 obtained as described above is subjected to drawing, thereby obtaining a low-height drawn can (bottomed cylindrical body) 109 (see FIG. 7(b)). In this drawing process, the punched disk 103 is held on a die 111, and the periphery of this disk 103 is held by a clamping jig 113. An opening is formed in the die 111, and by using a drawing punch 115 to push the disk 103 into the opening of the die 111, a drawn can 109 is obtained. The upper corner of the opening of the die 111 (the side holding the disk 103) is rounded (curved), so that the disk 103 can be pushed into the opening of the die 111 quickly and without breaking, and the outer diameter of the punch 115 is set smaller than the diameter of the opening of the die 111 by an amount roughly equivalent to the thickness of the disk 103. In other words, this drawing process hardly results in thinning. The drawing process may be performed multiple times depending on the shape of the molded product.

[0036] Next, the drawn can 109 obtained above is subjected to an ironing process, whereby a metal can (thin-walled seamless can) 11 with a large height and thin wall is formed (see FIG. 7(c)). In this ironing process, an ironing punch 1 according to the present invention is inserted into the drawn can 109 obtained by the above-mentioned drawing process, and the punch 1 is lowered while pressing the outer surface of the cylindrical body 109 against the inner surface of a ring-shaped ironing die 121, thereby thinning the sidewall of the drawn can (cylindrical body) 109 by the die 121. This results in a metal can (thin-walled seamless can) 11 according to the present invention that has been thinned and whose height has increased depending on the degree of thinning.

[0037] As can be seen from Figure 7, in this series of punching, drawing, and ironing steps, sliding properties are not necessary during punching, but as the process progresses from drawing to ironing, sliding properties become more important between the die and the workpiece. Ironing, in particular, requires the most sliding properties because a surface pressure exceeding the yield stress of the workpiece is applied. This means that a large surface pressure is also applied between the inner surface of the workpiece (drawn can 109) and the outer surface 1a of the ironing punch 1. As a result, contact with the raised portion 5 of the ironing punch 1 forms a ring-shaped recess 13 on the inner surface of the drawn can 109.

[0038] The ironing process can also be performed in multiple stages. For example, by arranging a plurality of ironing dies in the ironing direction and performing the ironing process in multiple stages, it is possible to increase the ironing rate and obtain a thinner-walled, taller metal can 11. Figure 8 shows an example of a process in which the ironing process is performed in multiple stages.

[0039] In the process shown in FIG. 8, a ring-shaped redraw die 111a and ironing dies 121a to 121c are arranged in this order along the processing direction, and a guide ring 135 is disposed downstream of the ironing die 121c, which is located furthest downstream in the processing direction, and a retaining ring 137 and a retaining rod 137a, which form the bottom portion, are disposed further downstream in this order.

[0040] The ironing dies 121a to 121c have smaller diameters as they are arranged downstream in the processing direction, so that more severe thinning can be performed.

[0041] In this type of multi-stage ironing process (re-drawing-ironing), the drawn can 109 is held on the redraw die 111a by a holder 141, and in this state the ironing punch 1 of the present invention is inserted into the inside of the drawn can 109. The punch 1 is moved in the processing direction while pressing the outer surface of the drawn can 109 against the inner surfaces (processing surfaces) of the redraw die 111a and ironing dies 121a to 121c, thereby performing the re-drawing and ironing processes, thinning the side walls of the drawn can 19 and producing a taller metal can 11 (metallic cylinder).

[0042] Although three ironing dies are arranged in FIG. 8, it is of course possible to arrange two ironing dies, or to arrange more than three ironing dies.

[0043] After the ironing process shown in Figures 7 and 8 is completed, a stopper 20 is placed on the top end of the metal can 11, and the ironing punch 1 is withdrawn while its movement is restricted, as shown in Figure 5. In other words, in the present invention, the frictional resistance during this withdrawal is greatly reduced, thereby improving the production efficiency of the ironing process.

[0044] The drawing and ironing processes in the processes shown in Figures 7 and 8 can be performed under wet conditions with a coolant flowing through them, or they can be performed under dry conditions using a low-lubrication method with a solid lubricant or a no-lubrication method without using a coolant.

[0045] After the ironing punch 1 is pulled out, the metal can 11 (metallic cylindrical body) undergoes, for example, exterior printing or neck-in processing, and is then put up for sale. [Explanation of symbols]

[0046] A: Ironing punch B: Metal cylinder (workpiece) C: Ironing die 1: Squeezing Punch 1a: Outer surface of ironing punch 1 3: Dot-shaped recesses 5: Protuberance 11: Metal cylindrical body 11a: inner circumferential surface of metal cylindrical body 11 15: Dot-shaped convex part

Claims

1. In ironing punches used in metal ironing, The punch for ironing is characterized in that dot-shaped depressions, each having a diameter of 0.2 to 1.1 mm and a depth of 0.2 to 10.0 μm, are distributed on the outer peripheral surface of the punch and formed by plastic deformation, and raised portions are formed on the peripheries of the dot-shaped depressions due to the plastic deformation of the dot-shaped depressions.

2. 2. A method for producing a thin-walled metal cylinder, comprising the steps of: ironing a metal cylinder using the ironing punch according to claim 1; and obtaining a thin-walled metal cylinder.

3. 3. The manufacturing method according to claim 2, wherein the metal cylindrical body to be subjected to the ironing process is a laminated body having an organic resin coating on the inner surface of a metal substrate.

4. 4. The manufacturing method according to claim 3, wherein the organic resin coating is formed from a thermoplastic resin.

5. 5. The manufacturing method according to claim 2, wherein the metal cylinder subjected to the ironing process is a bottomed cylinder, and the thinned metal cylinder is a seamless can.

6. A method for manufacturing an ironing punch used in metal ironing, The outer surface of the ironing punch is struck with a jig to create a depression through plastic deformation. A method for manufacturing an ironing punch, characterized in that recesses having a diameter of 0.2 to 1.1 mm and a depth of 0.2 to 10.0 μm are formed on the outer peripheral surface of the ironing punch in a dot pattern, and raised portions are formed on the periphery of the recesses.

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