Punch and method for manufacturing a punch

Abstract

It can be manufactured with simpler processing, and the strength and rigidity of the punch can be increased, allowing for more precise processing. [Solution] The punch is used for forming or punching holes by cold forging, and has a land of a certain thickness, with a tip portion that is pressed against the material at one of its ends, and a film made by PVD (Physical Vapor Deposition) or CVD (Chemical Vapor Deposition) deposited on the land, and the surface of the film is made uneven by arranging shapes that form curved or contours closed by multiple straight lines, and the other end of the land is connected to a portion that is thicker than the thickness of the land.

Description

Technical Field

[0001] The present invention relates to a punch and a method for manufacturing a punch, and more particularly to a punch used for forming or punching by cold forging press working and a method for manufacturing the punch.

Background Art

[0002] For forming or punching by cold forging press working, a punch and a die are used as dies. Dies having various coatings are also used.

[0003] FIG. 10 is a view showing the configuration of a conventional punch 301 for forming a cylindrical hole. The punch 301 includes a tip portion 321, a land 322, a relief portion 323, a shank 324, and a head 325. The tip portion 321 is a portion that is pressed against the material surrounded by the die. The land 322 is formed on a side surface close to the tip portion 321. The land 322 is a die surface portion that forms a parallel gap for allowing the material to flow out of the die during cold forging press working. The tip portion 321 and the land 322 have a shape corresponding to the shape of the molded product or the shape of the hole formed by cold forging press working, that is, a circular cross-sectional shape. Here, the punching diameter d of the land 322 refers to the diameter of the circumference of the cylindrical land 322.

[0004] The relief portion 323 is a cylindrical portion formed on the tip end 321 side of the punch 301, following the tip end 321 and the land 322. The relief portion 323 is inserted into the paired die during cold forging or drilling. The relief portion 323 connects to the land 322 with a 5% taper that narrows towards the relief portion 323. The relief portion 323 is formed as a cylinder with a diameter d' that is slightly smaller than the drilling diameter d of the land 322. Typically, the diameter d' of the relief portion 323 is -0.02 mm to -0.1 mm smaller than the drilling diameter d. The length of the relief portion 323 is formed such that the lengths of the tip end 321, land 322, and relief portion 323 are longer than the depth A of the molded product or hole. Also, the length L of the land 322 is shorter than the depth A of the molded product or hole. The relief portion 323 allows for avoidance of contact with the material during molding.

[0005] The relief section 323 tapers towards the shank 324 and connects to the shank 324. The shank 324 is a mounting section provided for attachment to a forging machine. The shank 324 is formed to be thicker than the relief section 323. The head 325 is the so-called punch head and receives the longitudinal force of the punch 301 applied from the forging machine.

[0006] Figures 11 and 12 show the configuration of a conventional punch 501 for forming a gear-shaped hole. Figure 11 is a side view showing the side of the punch 501. Figure 12 is a front view showing the tip side of the punch 501. The punch 501 consists of a tip 521, a land 522, a relief 523, a shank 524, and a head 525. The tip 521 is the part that is pressed against the material surrounded by the die. The land 522 is formed on the side adjacent to the tip 521. The land 522 is a die surface portion that forms a gap with the die during cold forging, creating a parallel gap for the material to flow out of the die. The tip 521 and the land 522 have a shape corresponding to the shape of the molded product or the shape of the hole formed by cold forging, i.e., a gear-shaped cross-section. Here, the drilling diameter d of the land 522 is the longest distance between two points on the outer edge of the circumference of the columnar land 22, which has a gear-shaped cross-section.

[0007] The relief portion 523 is a part formed on the tip portion 521 side of the punch 501, following the tip portion 521 and the land 522. The relief portion 523 is formed in a columnar shape with a gear-like cross-sectional shape corresponding to the cross-sectional shape of the land 522.

[0008] The relief portion 523 is inserted into the paired die during cold forging or drilling. The relief portion 523 connects to the land 522 with a taper that narrows towards the relief portion 523. The relief portion 523 is formed with a diameter d' that is slightly smaller than the drilling diameter d of the land 522. Here, the diameter d' of the relief portion 523 is the longer of the distances between two points on the outer edge of the circumference of the columnar land 522, which has a gear-shaped cross-section. Typically, the diameter d' of the relief portion 523 is -0.02 mm to -0.1 mm less than the drilling diameter d. The length of the relief portion 523 is formed such that the lengths of the tip portion 521, land 522, and relief portion 523 are longer than the depth A of the molded product or hole. The relief portion 523 allows for avoidance of contact with the material during molding.

[0009] The relief section 523 tapers towards the shank 524 and connects to the shank 524. The shank 524 is a mounting section provided for attachment to a forging machine. The shank 524 is formed to be thicker than the relief section 523. The head 525 is the so-called punch head and receives the longitudinal force of the punch 501 applied from the forging machine.

[0010] A method for manufacturing an outer ring for a constant velocity joint has been proposed, which involves using a forging die equipped with a punch and a die having a laminated structure of a CrN layer and a TiAlN layer formed on its inner surface, inserting a workpiece into the die, and then extruding the workpiece backward (see, for example, Patent Document 1). Another proposed method for hot forging steel materials has been developed, which involves using a forging punch with a surface treatment having a compound layer of oxygen-containing iron sulfide particles and iron nitride particles on the surface of the punch, and forging steel materials at 1000 to 1200°C, by spraying or applying a water-soluble polymer lubricant to the punch surface at a surface temperature of 250 to 350°C to deposit a film of 35 μm or more on the punch surface, and then forging forward or backward extrusion while cooling and lubricating the punch so that the temperature of the punch is 250 to 350°C at a position 3 mm from the surface using the water-soluble polymer lubricant (see, for example, Patent Document 2).

[0011] Furthermore, some molds have a coating formed on the surface of at least the parts of the die and punch that come into contact with the workpiece, containing at least one of Ni-P, Cr, nitrides, borides, carbon compounds, titanium compounds, tungsten compounds, diamond, and diamond-like crystals, and also have a lubricating substance added to the coating formed on the surface of the parts of the die and punch where the coefficient of friction is set to 85% or less, containing B, C, F, or at least one of nitrides, borides, carbon compounds, fluorides, and sulfides (see, for example, Patent Document 3).

[0012] The surface of the counterpunch is coated with a hard ceramic coating, and it has also been proposed that a number of dimples be spaced apart on the first and second processing surfaces (see, for example, Patent Document 4). [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] Japanese Patent Publication No. 2010-247188 [Patent Document 2] Patent No. 4224219 [Patent Document 3] Japanese Patent Application Publication No. 9-253770 [Patent Document 4] Japanese Patent Publication No. 2020-49537 [Overview of the project] [Problems that the invention aims to solve]

[0014] However, forming the relief portion 323 or relief portion 523 is extremely difficult. Also, because the relief portion 323 or relief portion 523 is thinner than other parts, the strength or rigidity of the punch is reduced.

[0015] This invention was made in view of these circumstances, and aims to enable manufacturing with simpler processing, and to increase the strength and rigidity of the punch, thereby enabling more precise processing. [Means for solving the problem]

[0016] One aspect of the present invention is a punch used for forming or drilling by cold forging, and is provided with a tip portion that is pressed against the material at one of its ends. In cold forging, a land is a gap between the die and the material, which is a die surface portion that forms a parallel gap for the material to flow out of the die, or a die surface portion that engages with the die and forms a predetermined parallel gap with the die for forming a hole in the material. A land of a certain thickness is provided, and a film is deposited on the land by PVD (Physical Vapor Deposition) or CVD (Chemical Vapor Deposition). The surface of the film is made uneven by arranging shapes that form curved or contours closed by multiple straight lines, and one end of the land is connected to a part that is thicker than the land.

[0017] A film can be formed from the tip side of the land toward the other end with a length longer than the depth of the hole formed in the material.

[0018] The contour of the shape with irregularities on the surface of the film can be a single closed curve or a polygon.

[0019] Irregularities with 30% to 60% of the total area of the film being concave can be formed on the surface of the film.

[0020] Irregularities reaching a depth of 1 μm to 5 μm from the surface of the film can be formed on the surface of the film.

[0021] By arranging the shapes with irregularities in a zigzag spiral arrangement around the land, irregularities can be formed on the surface of the film.

[0022] Deeper irregularities can be formed in the film on the end side of the tip side, and shallower irregularities can be formed in the film on the other end side.

[0023] Irregularities with a larger concave area can be formed in the film on the end side of the tip side, and irregularities with a smaller concave area can be formed in the film on the other end side.

[0024] By arranging circular, elliptical, oval or oval-shaped contours on the surface of the film, irregularities can be formed on the surface of the film.

[0025] By arranging holes of a shape in the film, irregularities can be formed.

[0026] The diameter of the holes arranged in the film on the surface of the film can be 20 μm to 100 μm.

[0027] The diameter of the holes arranged in the film on the surface of the film can be made smaller on the end side of the tip side and larger on the other end side.

[0028] The arrangement of shaped protrusions on the coating allows for the formation of uneven surfaces.

[0029] One aspect of the present invention is a method for manufacturing a punch used for forming or drilling by cold forging, wherein one end of the punch is provided with a tip portion that is pressed against the material, and the other end is connected to a thicker portion. A land is a die surface portion that forms a parallel gap between the die and the material during cold forging, allowing the material to flow out of the die, or a die surface portion that engages with the die and forms a predetermined parallel gap between the die and the material to form a hole in the material. A granule is formed on the punch body, a PVD or CVD coating is deposited on the land, and a shape with curved or multiple straight lines forming a contour is arranged on the surface of the coating to create irregularities on the surface of the coating.

[0030] Another aspect of the present invention is a method for manufacturing a punch used for forming or drilling by cold forging, wherein one end of the punch is provided with a tip portion that is pressed against the material, and the other end is connected to a thicker portion. A land is a die surface portion that forms a parallel gap between the die and the material during cold forging, allowing the material to flow out of the die, or a die surface portion that engages with the die and forms a predetermined parallel gap between the die and the material to form a hole in the material. A surface is formed on the punch body, and a shape with curved or multiple straight lines forming a contour is arranged on the surface of the land portion of the body to create irregularities on the surface of the land portion of the body. A PVD or CVD coating is then formed on the land portion of the body where the irregularities have been formed. [Effects of the Invention]

[0031] As described above, according to the present invention, the punch can be manufactured with simpler processing, and the strength and rigidity of the punch can be increased, allowing for more precise processing. [Brief explanation of the drawing]

[0032] [Figure 1] This is a side view showing an example of the configuration of the punch 11 according to an embodiment of the present invention. [Figure 2] This is a front view showing the tip side of punch 11. [Figure 3] This is an enlarged cross-sectional view showing a magnified cross-section of the coating 32. [Figure 4] This figure shows examples of the shapes of the irregularities formed on the surface of the coating 32. [Figure 5] This figure shows another example of the shape of the irregularities arranged on the surface of the coating 32. [Figure 6] This is a side view showing an example of the configuration of the punch 101 according to an embodiment of the present invention. [Figure 7] This is a front view showing the tip side of punch 101. [Figure 8] This is a flowchart illustrating an example of a manufacturing method for punch 11. [Figure 9] This is a flowchart illustrating another example of how to manufacture punch 11. [Figure 10] This diagram shows the configuration of a conventional punch 301 for forming a cylindrical hole. [Figure 11] This is a side view showing the configuration of a conventional punch 501 for forming gear-shaped holes. [Figure 12] This is a front view showing the configuration of a conventional punch 501 for forming gear-shaped holes. [Modes for carrying out the invention]

[0033] The embodiments of the present invention will be described below, and the correspondence between the constituent elements of the present invention and the embodiments described in the detailed description of the invention is illustrated as follows. This description is intended to confirm that embodiments supporting the present invention are described in the detailed description of the invention. Therefore, even if there are embodiments described in the detailed description of the invention but not described here as embodiments corresponding to the constituent elements of the present invention, this does not mean that such embodiments do not correspond to those constituent elements. Conversely, even if an embodiment is described here as corresponding to a constituent element, this does not mean that such an embodiment does not correspond to any constituent elements other than that one.

[0034] One aspect of the present invention is a punch (for example, punch 11 in Figure 1) used for forming or punching by cold forging, and has a land of a certain thickness (for example, land 22 in Figure 1) with a tip portion that is pressed against the material at one of its ends, and a coating (for example, coating 32 in Figure 1) made by PVD (Physical Vapor Deposition) or CVD (Chemical Vapor Deposition) is formed on the land, and a shape that forms a curved or concave shape closed by a plurality of straight lines (for example, recess 41 in Figure 4) is arranged on the surface of the coating, thereby forming an uneven surface on the coating, and the other end of the land is connected to a portion thicker than the thickness of the land.

[0035] Hereinafter, an embodiment of the punch of the present invention will be described with reference to Figures 1 to 9.

[0036] First, the configuration of the punch 11 according to one embodiment of the present invention will be described. Figure 1 is a side view showing an example of the configuration of the punch 11 according to an embodiment of the present invention. Figure 2 is a front view showing the tip side of the punch 11. Figure 3 is an enlarged cross-sectional view showing an enlarged cross-section of the coating. Figure 4 is a diagram showing an example of the shape of the irregularities formed on the surface of the coating.

[0037] The punch 11 is a die component that enters the container hole or the inside of the material during forging and applies load. Here, the material is a metallic material that is to be formed by forging, such as steel, aluminum alloy, copper alloy, titanium alloy, or magnesium alloy. The punch 11 is also called a punch or pin. The punch 11, together with its paired die, constitutes a die. That is, the punch 11, together with the die, constitutes a pair of die in the vertical or horizontal direction.

[0038] The punch 11 is used for forming or punching holes by cold forging. For example, the punch 11 is formed in the shape of a round bar overall. The punch 11 is pressed against a material surrounded by a die to form it.

[0039] The punch 11 can be described as a solid metal body whose surface is shaped to match the dimensions or shape of the forged product, in order to press it against the material and shape it.

[0040] The punch 11 is formed from a single piece of metal. The punch 11 comprises a tip 21, a land 22, a shank 24, and a head 25. The tip 21 is the part that is pressed against the material surrounded by the die. The land 22 is formed on the side adjacent to the tip 21. The land 22 is formed in a cylindrical shape of a predetermined length. The land 22 is a die surface portion that forms a gap with the die during cold forging, creating a parallel gap for the material to flow out of the die. Alternatively, the land 22 is a die surface portion that engages with the die during cold forging to create a predetermined parallel gap with the die for forming a hole in the material.

[0041] In other words, a tip portion 21 is provided at one end of the land 22, which is pressed against the material. The land 22 is formed to a certain thickness d. Here, the thickness d of the land 22 refers to the diameter of the circumference of a cylindrical land 22, or the longest distance between two points on the outer edge of the circumference of a columnar land 22 with a desired cross-sectional shape. For example, in the punch 11, the thickness d of the land 22 refers to the diameter of the circumference of a cylindrical land 22. The length of the land 22 is formed such that the length of the tip portion 21 and the land 22 are longer than the depth A of the molded product or hole.

[0042] The tip portion 21 and land 22 are shaped to correspond to the shape of the molded product or the shape of the hole formed by cold forging. For example, the tip portion 21 and land 22 form a cylindrical hole in the material. For example, the tip portion 21 and land 22 create a circular hole.

[0043] The other end of the land 22 is connected to the shank 24.

[0044] The shank 24 is a mounting portion provided for attachment to a forging machine. That is, the punch 11 is attached to the forging machine by holding the shank 24. The shank 24 is formed to be thicker than the land 22. That is, one end of the land 22 is connected to a portion that is thicker than the land 22.

[0045] The head 25 is the so-called punch head and receives the longitudinal force of the punch 11 applied from the forging machine. For example, when forming or punching by cold forging, a force is applied to the head 25 of the punch 11 from the forging machine in the direction from left to right in Figure 1, pressing the tip 21 and land 22 against the material. For example, after forming or punching by cold forging, a force is applied to the head 25 of the punch 11 from the forging machine in the direction from right to left in Figure 1, pulling the tip 21 and land 22 out of the material.

[0046] The punch 11 is formed from a single body 31 that includes a tip 21, a land 22, a shank 24, and a head 25. The body 31 is made of a metal such as carbon tool steel, low alloy tool steel, high alloy tool steel, high-speed steel, or powder high-speed tool steel.

[0047] As shown in Figure 1, a coating 32 is formed on the surface of the land 22. The length of the coating 32 is formed to be longer than the depth A of the molded product or hole. That is, the coating 32 is formed to be longer than the depth A of the molded product or hole from the tip 21 side toward the shank 24. The coating 32 is a coating made by PVD (Physical Vapor Deposition) or CVD (Chemical Vapor Deposition). Here, PVD is a method of obtaining a coating by evaporating metals or compounds using physical methods such as resistance heating, electron beam heating, or sputtering, and depositing them on a substrate (object (in this case, the main body 31)). Typical methods of PVD include vacuum deposition, ion plating, and sputtering. For example, the coating 32 on the surface of the land 22 is formed by ion plating. Ion plating is a method of deposition in which a positive charge is applied to the deposition material in a plasma and a negative charge is applied to the substrate. When forming the coating 32 by PVD, a wide variety of materials can be used for the coating 32, and in particular, multi-component alloys can be used as the coating 32. Furthermore, when forming the coating 32 by PVD, the coating 32 can be deposited at a lower temperature, which can suppress dulling and dimensional changes of the main body 31. The thickness of the PVD coating 32 is approximately 0.5 μm to 10 μm.

[0048] CVD is a chemical film deposition method that operates at atmospheric pressure or medium vacuum (100 Pa to 10°C). -1This method involves introducing gaseous raw materials into a Pa atmosphere and applying energy such as heat, plasma, or light to excite or accelerate a chemical reaction, thereby synthesizing thin films or fine particles, which are then adsorbed and deposited onto the surface of a substrate or base material. Typical CVD methods include thermal CVD, plasma CVD, and photoCVD. For example, a coating 32 made of diamond or DLC (Diamond-Like Carbon) is formed on the surface of a land 22 by CVD. When forming a coating 32 by CVD, a relatively uniform coating 32 can be formed even if the land 22 has a three-dimensional shape. Furthermore, the coating 32 formed by CVD has excellent adhesion and abrasion resistance. In addition, the film thickness of the coating 32 formed by CVD is approximately 5 μm to 20 μm.

[0049] The coating 32 includes at least one of the following: a TiN (Titanium Nitride) film, a TiAlN (Titanium Aluminium Nitride) film, a CrN (Chromium Nitride) film, a TiCN (Titanium Carbon Nitride) film, or a DLC (Diamond-Like Carbon) film. The coating 32 may consist of a multilayer film including a TiN layer, a TiAlN layer, a CrN layer, a TiCN layer, or a DLC layer. For example, the thickness of the coating 32 is 1 μm to 10 μm.

[0050] As shown in Figures 3 and 4, the surface of the coating 32 has irregularities. In Figure 3, the horizontal direction corresponds to the horizontal direction in Figure 1. In Figure 3, the horizontal direction corresponds to the depth direction in Figure 2. Note that in Figure 3, the horizontal scale and the vertical scale are different. In Figure 4, the vertical direction corresponds to the horizontal direction in Figure 1. In Figure 4, the vertical direction corresponds to the depth direction in Figure 2. In Figure 4, the horizontal direction corresponds to the circumferential direction of the land 22. That is, in Figure 4, the horizontal direction corresponds to the direction along the circumference (vertical direction in Figure 1) when the cylindrical land 22 is unfolded on a plane as the side surface of a cylinder.

[0051] The surface irregularities of the coating 32 are formed by arranging recesses 41 and protrusions 42, which have a shape that forms irregularities with curves or contours closed by multiple straight lines, in a repeating manner on the surface of the coating 32. In other words, the surface irregularities of the coating 32 are formed by the arrangement of recesses 41 and protrusions 42. Arrangement includes equally spaced arrangements, staggered arrangements, randomly spaced arrangements, and patterned arrangements, and includes arranging in rows at desired intervals and arranging in a direction that intersects the orientation of the rows so that a predetermined offset occurs.

[0052] Multiple recesses 41 are formed on the surface of the coating 32. The protrusions 42 are the parts of the surface of the coating 32 other than the recesses 41. Each recess 41 is a circular-shaped hole on the surface of the coating 32. For example, each recess 41 is formed in the shape of a spherical cap (a part of a sphere cut by a plane). For example, each recess 41 may be formed in an arbitrary curved shape, or it may be formed so that its bottom surface is flat, or it may be formed so that its cross-section is a straight slope.

[0053] As shown in Figure 3, the recess 41 does not reach the main body 31. In other words, the recess 41 is a recess within the coating 32. To put it another way, the depth of the recess 41 is less than the thickness of the coating 32.

[0054] For example, the diameter of the recess 41 is set to 50 μm. Preferably, the diameter of the recess 41 is 20 μm to 100 μm. In this case, an increase in the number of times the punch 11 can be used for cold forging was observed.

[0055] In the land 22, a recess 41 with a smaller diameter can be formed in the coating 32 on the tip portion 21 side, and a recess 41 with a larger diameter can be formed in the coating 32 on the shank 24 side. For example, in the land 22, a recess 41 with a diameter of 20 μm can be formed on the tip portion 21 side. Also, for example, in the land 22, a recess 41 with a diameter of 100 μm can be formed on the shank 24 side. In the land 22, the diameter of the recess 41 can be changed linearly or nonlinearly with respect to the distance from the tip portion 21.

[0056] For example, multiple recesses 41 are formed on the surface of the coating 32 and are arranged at regular intervals on the surface of the coating 32. That is, the recesses 41 are arranged on the surface of the coating 32. For example, the arrangement of the recesses 41 is a staggered arrangement in which they are arranged alternately in two rows. For example, the recesses 41 are arranged in two rows in a predetermined direction on the surface of the land 22, forming two spirals. More specifically, the recesses 41 are arranged in two rows in the longitudinal direction of the punch 11 on the surface of the land 22, forming two spirals.

[0057] For example, the recesses 41 may be arranged in a single spiral shape on the surface of the land 22, while being aligned in a single row in a predetermined direction. More specifically, the recesses 41 may be arranged in a single spiral shape on the surface of the land 22, while being aligned in a single spiral shape in the longitudinal direction of the punch 11.

[0058] Thus, the recesses 41 are arranged in a spiral pattern, one or more times, on the surface of the land 22. In other words, the recesses 41 can be arranged in a spiral pattern on the surface of the land 22.

[0059] For example, the area of ​​the recesses 41 on the surface of the coating 32 is set to 45% of the total surface area of ​​the coating 32. Preferably, the area of ​​the recesses 41 on the surface of the coating 32 is 30% to 60% of the total surface area of ​​the coating 32. In this case, an increase in the number of times the punch 11 can be used for cold forging was observed.

[0060] In the land 22, more recesses 41 can be formed in the coating 32 on the tip portion 21 side, and fewer recesses 41 can be formed in the coating 32 on the shank 24 side. For example, in the land 22, recesses 41 are formed that occupy 60% of the surface area of ​​the coating 32 on the tip portion 21 side. Also, for example, in the land 22, recesses 41 are formed that occupy 30% of the surface area of ​​the coating 32 on the shank 24 side. In the land 22, the area of ​​the recesses 41 relative to the surface of the coating 32 can be changed linearly or nonlinearly with respect to the distance from the tip portion 21.

[0061] For example, the depth of the recess 41 is 2 μm from the surface of the coating 32. The recess 41 is formed within the film thickness of the coating 32 and does not reach the main body 31. The depth of the recess 41 is preferably 1 μm to 5 μm from the surface of the coating 32. In this case, the number of times the punch 11 can be used for cold forging has clearly increased.

[0062] In the land 22, a deeper recess 41 can be formed in the coating 32 on the tip portion 21 side, and a shallower recess 41 can be formed in the coating 32 on the shank 24 side. For example, in the land 22, a recess 41 with a depth of 5 μm from the surface of the coating 32 is formed on the tip portion 21 side. Also, for example, in the land 22, a recess 41 with a depth of 1 μm from the surface of the coating 32 is formed on the shank 24 side. In the land 22, the depth of the recess 41 from the surface of the coating 32 can be changed linearly or nonlinearly with respect to the distance from the tip portion 21.

[0063] Figure 5 shows another example of the shape of the irregularities arranged on the surface of the coating 32. For example, as shown in Figure 5(A), a plurality of recesses 61 are formed on the surface of the coating 32. The contours of the recesses 61 are elliptical on the surface of the coating 32. On the surface of the coating 32, the parts other than the recesses 61 are convex.

[0064] For example, as shown in Figure 5(B), multiple recesses 62 are formed on the surface of the coating 32. The contours of the recesses 62 are oval on the surface of the coating 32. The parts of the surface of the coating 32 other than the recesses 62 are convex.

[0065] Furthermore, the contour of the recess can be egg-shaped or oval-shaped on the surface of the coating 32.

[0066] For example, as shown in Figure 5(C), multiple recesses 63 are formed on the surface of the coating 32. The contours of the recesses 63 are rounded rectangles on the surface of the coating 32. The parts of the surface of the coating 32 other than the recesses 63 are convex.

[0067] Furthermore, the contour of the recess can be a quadrilateral, such as a rectangle, square, or trapezoid, on the surface of the coating 32. In addition, the contour of the recess can be a convex polygon, such as a triangle, pentagon, or hexagon, on the surface of the coating 32. Moreover, the contour of the recess can be a concave polygon, such as a gear shape (cross-sectional shape in a cross section perpendicular to the axis of rotation of a gear) or a star shape (star polygon), on the surface of the coating 32.

[0068] Furthermore, while it was explained that the contours of recesses 41, 61, or 62 on the surface of the land 22 may be circular, elliptical, or oblong, respectively, and that the contours of the recesses may also be egg-shaped or oval, the contours of the convex portions 42 on the surface of the land 22 may also be circular, elliptical, oblong, egg-shaped, or oval. In this case, the contour of the convex portion 42 can be made into a predetermined shape by carving away the recess so as to leave the convex portion 42. Similarly, while it was explained that the contour of recess 63 on the surface of the land 22 may be a rounded rectangle, and that the contours of the recesses may also be quadrilaterals such as rectangles, squares, or trapezoids, convex polygons such as triangles, pentagons, or hexagons, or concave polygons such as gear shapes or star shapes, the contours of the convex portions 42 on the surface of the land 22 may also be quadrilaterals, convex polygons, or concave polygons.

[0069] In this way, the surface of the coating 32 can be made to have a shape in which a recess is surrounded by a single closed curve. Alternatively, the surface of the coating 32 can be made to have a shape in which a recess is surrounded by a polygon.

[0070] Furthermore, the surface of the coating 32 can be shaped such that the protrusions are surrounded by a single closed curve. Alternatively, the surface of the coating 32 can be shaped such that the protrusions are surrounded by a polygon.

[0071] In this way, the surface of the coating 32 is formed such that a shape consisting of irregularities enclosed by a single closed curve or an irregularity enclosed by a polygon is repeated on the surface of the coating 32, thereby creating irregularities on the surface of the coating 32.

[0072] In other words, the surface of the coating 32 is made uneven by arranging shapes that form curved or contoured shapes closed by multiple straight lines in a repeating manner.

[0073] In this way, by forming a coating 32 on the land 22 and creating irregularities on the surface of the coating 32, friction with the material is reduced to the same extent as when conventional reliefs are provided.

[0074] Furthermore, by forming a coating 32 on the land 22 and arranging shapes that form curved or multiple straight-line-bound contours on the surface of the coating 32, an uneven surface is formed on the surface of the coating 32. When a liquid lubricant is used during cold forging, the liquid lubricant can be retained in the recesses on the surface of the coating 32, making it easier to maintain liquid lubrication more uniformly in the recesses on the surface of the land 22. As a result, even if the surface pressure increases, the breakdown of the boundary lubrication film at the convex parts of the surface is suppressed, and adhesion is less likely to occur.

[0075] Furthermore, by forming a coating 32 on the land 22 and arranging shapes that form curved or contoured shapes closed by multiple straight lines on the surface of the coating 32, an uneven surface is formed on the surface of the coating 32. Therefore, when cold forging is performed and pressure is applied, the coating 32 near the uneven surface deforms with less force, and a steady lubrication state is maintained with less deformation resistance from the coating 32, making it less likely for the coating to break.

[0076] Furthermore, by forming a coating 32 on the land 22 and arranging shapes that form curved or multiple straight-line-bound contours on the surface of the coating 32, an uneven surface is created on the coating 32. As a result, when cold forging, micro-sludges penetrate the uneven surface of the coating 32, allowing for more precise processing without increasing friction with the material. Moreover, the number of defects is reduced.

[0077] Since there is no need to create a relief section that tapers away from the land, machining can be done more easily, and machining costs are further reduced. In particular, the cost of tools required for machining the punch can be reduced.

[0078] Since there is no need to create a relief section that tapers away from the land, the strength and rigidity of the punch can be increased. Because the twisting and bending of the punch during machining are reduced, the durability of the punch increases and machining accuracy improves. In particular, the straightness of the punch relative to the hole being machined improves, thus improving machining accuracy.

[0079] Next, the configuration of a punch 101 according to one embodiment of the present invention will be described. Figure 6 is a side view showing an example of the configuration of a punch 101 according to an embodiment of the present invention. Figure 7 is a front view showing the tip side of the punch 101.

[0080] Punch 101, like punch 11, is a die component that enters the container hole or the inside of the material during forging and applies load. Punch 101 is used for forming or punching by cold forging. For example, punch 101 is formed as a whole in the shape of a round bar. Punch 101 is pressed against the material surrounded by the die to form it.

[0081] The punch 101 is pressed against the material to form a gear-shaped hole or to create a gear-shaped opening.

[0082] The punch 101 is formed from a single piece of metal. The punch 101 consists of a tip 121, a land 122, a shank 124, and a head 125. The tip 121 is the part that is pressed against the material surrounded by the die. The land 122 is formed on the side adjacent to the tip 121. The land 122 is formed in a gear-like (spur gear-like) shape of a predetermined length. The tip 121 and the land 122 create a gear-shaped hole.

[0083] Land 122 is a die surface portion that forms a gap with the die during cold forging, creating a parallel gap to allow the material to flow out of the die. Alternatively, land 122 is a die surface portion that engages with the die during cold forging to create a predetermined parallel gap with the die to form a gear-shaped hole in the material.

[0084] In other words, a tip portion 121 is provided at one end of the land 122, which is pressed against the material. The land 122 is formed to a certain thickness d. The thickness d of the land 122 here refers to the longest distance between two points on the outer edge of the circumference of the columnar land 122, which has a gear-shaped cross-section. The thickness d of the land 122 can also be said to be the diameter of the circle inscribed in the outer circumference of the land 122. The length of the land 122 is formed such that the length of the tip portion 121 and the land 122 are longer than the depth A of the molded product or hole.

[0085] The other end of the land 122 is connected to the shank 124. For example, the other end of the land 122 is connected to the shank 124 by a taper, where the gear-like portion becomes thicker and wider as it approaches the shank 124.

[0086] The shank 124 is a mounting portion provided for attachment to a forging machine. That is, the punch 101 is attached to the forging machine by holding the shank 124. The shank 124 is formed to be thicker than the land 122. That is, one end of the land 122 is connected to a portion that is thicker than the land 122.

[0087] The head 125 is the so-called punch head and receives the longitudinal force of the punch 101 applied from the forging machine. For example, when forming or punching by cold forging, a force is applied to the head 125 of the punch 101 from the forging machine in the direction from left to right in Figure 6, pressing the tip 121 and land 122 against the material. For example, after forming or punching by cold forging, a force is applied to the head 125 of the punch 101 from the forging machine in the direction from right to left in Figure 6, pulling the tip 121 and land 122 out of the material.

[0088] The punch 101 is formed from a single body 131 that includes a tip 121, a land 122, a shank 124, and a head 125. The body 131 is made of a metal such as carbon tool steel, low alloy tool steel, high alloy tool steel, high-speed steel, or powder high-speed tool steel.

[0089] A coating 132 is formed on the surface of the land 122. The length of the coating 132 is formed to be longer than the depth A of the molded product or hole. That is, the coating 332 is formed to be longer than the depth A of the molded product or hole from the tip 121 side toward the shank 124. The coating 132 is a PVD or CVD coating.

[0090] The coating 132 includes at least one of a TiN film, a TiAlN film, a CrN film, a TiCN film, or a DLC film. The coating 132 may consist of a multilayer film including a TiN layer, a TiAlN layer, a CrN layer, a TiCN layer, or a DLC layer. For example, the thickness of the coating 132 is 1 μm to 10 μm.

[0091] The surface of coating 132 has irregularities, similar to coating 32. Since the structure of the irregularities on coating 132 is the same as that of coating 32, a detailed explanation is omitted.

[0092] In this way, by forming a coating 132 on the land 122 and creating irregularities on the surface of the coating 132, friction with the material is reduced to the same level as when conventional reliefs are provided. The effect of reducing friction is particularly great when the contact area between the land 122 and the material is large.

[0093] Furthermore, by forming a coating 132 on the land 122 and arranging shapes that form curved or multiple straight-line-bound contours on the surface of the coating 132, an uneven surface is formed on the surface of the coating 132. When a liquid lubricant is used during cold forging, the liquid lubricant can be retained in the recesses on the surface of the coating 132, making it easier to maintain liquid lubrication more uniformly in the recesses of the surface across the entire surface of the land 122. As a result, even if the surface pressure increases, the breakdown of the boundary lubrication film at the convex parts of the surface is suppressed, and adhesion is less likely to occur. In particular, when the shape of the land 122 surface is complex, it becomes easier to maintain liquid lubrication across the entire surface of the land 122.

[0094] Furthermore, by forming a coating 132 on the land 122 and arranging shapes that form curved or multiple straight-line-bound contours on the surface of the coating 132, an uneven surface is formed on the surface of the coating 132. Therefore, when cold forging is performed and pressure is applied, the coating 132 near the uneven surface deforms with less force, and a steady lubrication state is achieved with less deformation resistance from the coating 132, making coating breakage less likely. When the shape of the land 122 surface is complex, coating breakage is particularly less likely to occur in the convex portion corresponding to the tip of a gear-like shape.

[0095] Furthermore, by forming a coating 132 on the land 122 and arranging shapes that form curved or multiple straight-line-bound contours on the surface of the coating 132, an uneven surface is created on the coating 132. As a result, when cold forging, micro-sludges penetrate the uneven surface of the coating 132, allowing for more precise processing without increasing friction with the material. Moreover, the number of defects is reduced.

[0096] Since there is no need to create a relief section that tapers away from the land, machining can be done more easily, and machining costs are further reduced. In particular, the cost of the tools required for machining the punch can be reduced. Machining becomes especially easier when the shape of the land 122 surface is complex.

[0097] Since there is no need to provide a relief section that tapers away from the land, the strength and rigidity of the punch can be increased. Because the twisting and bending of the punch during machining are reduced, the durability of the punch is increased and machining accuracy is improved. In particular, the straightness of the punch relative to the hole being machined is improved, thus improving machining accuracy. When the land 122 has a shape that protrudes from the center outward, the strength and rigidity of the punch tend to decrease, but since there is no need to provide a relief section that tapers away from the land, the strength and rigidity of the punch can be increased, especially. When the land 122 has a shape that protrudes from the center outward, even in the part close to the center, machining is performed by surface contact, so machining can be performed with higher accuracy.

[0098] Furthermore, the punch 101 can also have its land 122 formed in a helical gear shape to form a helical gear-shaped hole.

[0099] Next, the manufacturing method of punch 11 or punch 101 will be described. The manufacturing method of punch 101 is the same as that of punch 11, so the following explanation will use the manufacturing method of punch 11 as an example. Figure 8 is a flowchart illustrating an example of the manufacturing method of punch 11. In step 11, a land 22 that is directly connected to the shank 24 is formed on the body 31 of punch 11. That is, a land 22 is formed on the body 31 of punch 11, with a tip portion 21 that is pressed against the material at one end and the other end connected to a thicker portion.

[0100] For example, in step 11, a land 22 directly connected to the shank 24 is formed on the body 31 of the punch 11 by cutting or powder metallurgy, heat treatment such as quenching or annealing, or polishing. In step S12, a coating 32 is formed on the land 22 by CVD or PVD. For example, in step S12, a coating 32 is formed on the surface of the land 22 by ion plating. For example, in step S12, a coating 32 which is a DLC coating is formed on the surface of the land 22 by plasma CVD.

[0101] In step S13, irregularities are formed on the surface of the coating 32 by arranging shapes that form a closed contour on the surface of the coating 32. For example, in step S13, irregularities are formed on the surface of the coating 32 by arranging recesses 41, recesses 61, or recesses 62 in a repeating manner. For example, in step S13, irregularities are formed on the surface of the coating 32 by arranging recesses 63 in a repeating manner. In this way, irregularities are formed on the surface of the coating 32 by arranging shapes that form a single closed curve or polygonal contour on the surface of the coating 32. For example, in step S13, irregularities are formed on the surface of the coating 32 by laser processing (laser removal processing). In this way, irregularities are formed on the surface of the coating 32 by arranging shapes that form a curve or a plurality of straight lines that form a closed contour on the surface of the coating 32.

[0102] In this way, a land 22 is formed on the body 31 of the punch 11, with a tip portion 21 that is pressed against the material at one end and the other end connected to a thicker portion. A coating 32 is deposited on the land 22 by CVD or PVD, and irregularities are formed on the surface of the coating 32 by arranging shapes that form curved or contours closed by multiple straight lines.

[0103] Next, another example of the manufacturing method of the punch 11 will be described with reference to the flowchart in Figure 9. In step 31, a land 22 that connects directly to the shank 24 is formed on the body 31 of the punch 11. The procedure in step 31 is the same as that in step 11, so a detailed explanation will be omitted.

[0104] In step S32, irregularities are formed on the surface of the land 22 portion of the main body 31 by arranging shapes that form a closed contour. For example, in step S32, irregularities are formed on the surface of the land 22 portion of the main body 31 by arranging recesses that are similar in shape to any of the recesses 41, 61, or 62 in a repeating manner. For example, in step S32, irregularities are formed on the surface of the land 22 portion of the main body 31 by arranging recesses that are similar in shape to the recess 63 in a repeating manner. In this way, in step S32, irregularities are formed on the surface of the land 22 portion of the main body 31 by arranging shapes that form a single closed curve or polygonal contour. For example, in step S32, irregularities are formed on the surface of the land 22 portion of the main body 31 by laser processing (laser removal processing). Thus, in step S32, a shape that forms curves or contours closed by multiple straight lines is arranged on the surface of the land 22 portion of the main body 31, thereby forming irregularities on the surface of the land 22 portion of the main body 31.

[0105] In step S33, a coating 32 is formed on the land 22 by CVD or PVD. That is, in step S33, a coating 32 is formed on the surface of the land 22 portion of the main body 31 by CVD or PVD. For example, in step S33, a coating 32 is formed on the surface of the land 22 portion of the main body 31 by ion plating. For example, in step S33, a coating 32, which is a DLC coating, is formed on the surface of the land 22 portion of the main body 31 by plasma CVD. More specifically, in step S33, a coating 32 of a certain thickness is formed on the surface of the land 22 portion of the main body 31 by CVD or PVD, and the surface of the coating 32 has irregularities that correspond to the irregularities formed on the surface of the land 22 portion of the main body 31.

[0106] In this way, a land 22 is formed on the body 31 of the punch 11, with a tip portion 21 that is pressed against the material at one end and the other end connected to a thicker portion. By arranging shapes that form curves or contours closed by multiple straight lines on the surface of the land 22 portion of the body 31, irregularities are formed on the surface of the land 22 portion of the body 31, and a coating 32 is formed on the land 22 portion of the body 31 where irregularities have been formed by PVD.

[0107] Furthermore, by forming irregularities on the land 22 of the main body 31 and then depositing a coating 32 on the land 22, the adhesion of the coating 32 to the land 22 is improved.

[0108] Additionally, one or more grooves can be spirally carved into the land 22 as recesses.

[0109] As described above, it can be manufactured with simpler processing, and the strength and rigidity of the punch can be increased, allowing for more precise processing.

[0110] Furthermore, when forming the coating 32 on the land 22 by PVD, masking may be used to create irregularities on the surface of the coating 32. Alternatively, irregularities may be created on the surface of the coating 32 by etching.

[0111] Punch 11 or punch 101 is used for forming or punching by cold forging. Land 22 or land 122 has a tip 21 or tip 121 at one end that is pressed against the material. Land 22 or land 122 has a constant thickness. A coating 32 or coating 132 is formed on land 22 or land 122 by PVD (Physical Vapor Deposition) or CVD (Chemical Vapor Deposition). The surface of coating 32 or coating 132 is made uneven by arranging shapes that form curves or contours closed by multiple straight lines. The other end of land 22 or land 122 is connected to a shank 24 or shank 124, which is a portion thicker than the land 22 or land 122.

[0112] A coating 32 or coating 132 can be formed on the land 22 or land 122 from the tip 21 or tip 121 side toward the shank 24 or shank 124 side, with a length longer than the depth of the hole formed in the material.

[0113] The contours of the irregular shapes on the surface of the coating 32 or coating 132 can be a single closed curve or a polygon.

[0114] It is possible to form irregularities on the surface of the coating 32 or coating 132 such that 30% to 60% of the total surface area of ​​the coating 32 or coating 132 is recessed.

[0115] Irregularities reaching a depth of 1 μm to 5 μm from the surface of the coating 32 or coating 132 can be formed on the surface of the coating 32 or coating 132.

[0116] By arranging the irregular shapes in a staggered spiral pattern around the periphery of land 22 or land 122, irregularities can be formed on the surface of coating 32 or coating 132.

[0117] Deeper irregularities can be formed on the coating 32 or coating 132 at the end side of the tip portion 21 or tip portion 121, and shallower irregularities can be formed on the coating 32 or coating 132 at the end side of the shank 24 or shank 124.

[0118] It is possible to form irregularities on the coating 32 or coating 132 that result in a larger recessed area on the end side of the tip portion 21 or tip portion 121, and irregularities on the coating 32 or coating 132 that result in a smaller recessed area on the end side of the shank 24 or shank 124.

[0119] By arranging circular, elliptical, oblong, or oval contours on the surface of the coating 32 or coating 132, irregularities can be formed on the surface of the coating 32 or coating 132.

[0120] By arranging holes of the aforementioned shape in the coating 32 or coating 132, an uneven surface can be formed.

[0121] The diameter of the holes arranged in the coating 32 or coating 132 on the surface of the coating 32 or coating 132 can be 20 μm to 100 μm.

[0122] The diameter of the holes arranged in the coating 32 or coating 132 on the surface of the coating 32 or coating 132 can be made smaller at the end side towards the tip 21 or tip 121 and larger at the end side towards the shank 24 or shank 124.

[0123] The surface can be made uneven by arranging protrusions of a specific shape on the coating 32 or the coating 132.

[0124] The punch 11 or punch 101 is manufactured by forming a land 22 or land 122 on the body 31 or body 131 of the punch 11 or punch 101, which has a tip portion 21 or tip portion 121 that is pressed against the material at one end and the other end connected to a thicker portion, depositing a PVD or CVD coating 32 or coating 132 on the land 22 or land 122, and arranging shapes that form curved or contoured irregularities on the surface of the coating 32 or coating 132, thereby forming irregularities on the surface of the coating 32 or coating 132.

[0125] Furthermore, the punch 11 or punch 101 is manufactured by forming a land 22 or land 122 on the body 31 or body 131 of the punch 11 or punch 101, with a tip portion 21 or tip portion 121 that is pressed against the material at one end and the other end connected to a thicker portion. The body 31 or body 131 is then manufactured by arranging shapes that form curved or multiple straight-line-bound contours on the surface of the land 22 or land 122 portion of the body 31 or body 131, thereby creating irregularities on the surface of the land 22 or land 122 portion of the body 31 or body 131, and then depositing a PVD or CVD coating on the land 22 or land 122 portion of the body 31 or body 131 where the irregularities have been formed.

[0126] Furthermore, the embodiments of the present invention are not limited to those described above, and various modifications are possible without departing from the spirit of the invention. [Explanation of Symbols]

[0127] 11 Punch, 21 Tip, 22 Land, 24 Shank, 25 Head, 31 Body, 32 Coating, 41 Recess, 42 Protrusion, 61 to 63 Recesses, 101 Punch, 121 Tip, 122 Land, 124 Shank, 125 Head, 131 Body, 132 Coating

Claims

1. In a punch used for forming or drilling by cold forging, A land is provided which, during cold forging, is a die surface portion that forms a parallel gap for allowing the material to flow out of the die, or a die surface portion that engages with the die to form a predetermined parallel gap for forming a hole in the material, and has a land of a certain thickness. A film is deposited on the aforementioned land by PVD (Physical Vapor Deposition) or CVD (Chemical Vapor Deposition). The surface of the coating is made uneven by arranging shapes that form curves or contours closed by multiple straight lines, The other end of the aforementioned land is connected to a portion that is thicker than the width of the land. punch.

2. In the punch according to claim 1, The coating is formed on the land from the leading edge to the other end, with a length longer than the depth of the hole formed in the material. punch.

3. In the punch according to claim 1, The contour of the shape that forms irregularities on the surface of the coating is a single closed curve or a polygon. punch.

4. In the punch according to claim 1, The surface of the coating has irregularities that are recessed, with an area of ​​30% to 60% of the total surface area of ​​the coating being recessed. punch.

5. In the punch according to claim 1, Irregularities extending to a depth of 1 μm to 5 μm are formed on the surface of the coating. punch.

6. In the punch according to claim 1, The uneven surface of the coating is formed by arranging the aforementioned shapes, which form irregularities, in a staggered spiral pattern around the periphery of the land. punch.

7. In the punch according to claim 1, Deeper irregularities are formed in the coating at the tip end, and shallower irregularities are formed at the other end. punch.

8. In the punch according to claim 1, The coating has irregularities that are recessed over a larger area at the tip end and irregularities that are recessed over a smaller area at the other end. punch.

9. In the punch according to claim 1, The surface of the coating is made uneven by arranging the aforementioned shapes, which have circular, elliptical, oblong, or oval contours, on the surface of the coating. punch.

10. In the punch according to claim 9, A punch in which holes of the aforementioned shape are arranged in the coating, thereby forming a textured surface.

11. In the punch according to claim 10, A punch in which the diameter of the holes arranged in the coating on the surface of the coating is 20 μm to 100 μm.

12. In the punch according to claim 11, The diameter of the holes arranged in the coating on the surface of the coating is smaller at the tip end and larger at the other end of the punch.

13. In the punch according to claim 9, A punch in which protrusions of the aforementioned shape are arranged on the coating, thereby forming an uneven surface.

14. In a method for manufacturing a punch used for forming or drilling by cold forging, A land is formed on the body of the punch, having a tip portion at one end that is pressed against the material and the other end connected to a thicker portion, and during forming by cold forging, the land is a mold surface portion that forms a parallel gap with the die to allow the material to flow out of the mold, or a mold surface portion that engages with the die to form a predetermined parallel gap with the die to form a hole in the material. A film is formed on the aforementioned land by PVD or CVD. The surface of the coating is made uneven by arranging shapes that form curved or contoured outlines closed by multiple straight lines. Manufacturing method.

15. In a method for manufacturing a punch used for forming or drilling by cold forging, A land is formed on the body of the punch, having a tip portion at one end that is pressed against the material and the other end connected to a thicker portion, and during forming by cold forging, the land is a mold surface portion that forms a parallel gap with the die to allow the material to flow out of the mold, or a mold surface portion that engages with the die to form a predetermined parallel gap with the die to form a hole in the material. By arranging shapes that form curved or multiple straight lines forming a closed contour on the surface of the land portion of the main body, an uneven surface is formed on the surface of the land portion of the main body. A PVD or CVD coating is formed on the land portion of the main body, which has an uneven surface. Manufacturing method.

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