Punch and method for manufacturing the punch

Abstract

To improve the durability of a punch more than by simply forming a coating. [Solution] The punch is a punch used for forming or drilling by cold forging, and has a coating formed on the land by PVD (Physical Vapor Deposition), and the surface of the coating is formed with an arrangement of irregular shapes with curved or multiple straight line closed contours, thereby forming irregularities on the surface of the coating.

Description

[Technical Field]

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

[0002] Forging involves forming or drilling holes using punches and dies. Dies coated with various types of coatings are also used.

[0003] A method for manufacturing an outer ring for a constant velocity joint has been proposed, which uses a forging die equipped with a punch and a die having a coating formed on the inner surface thereof with a laminated structure of a CrN layer and a TiAlN layer, inserts a workpiece into the die, and then backward extrusion-forms the workpiece (see, for example, Patent Document 1). Another proposed method for hot forging steel material includes forging a steel material at 1000 to 1200°C using a forging punch whose surface has been treated to have a compound layer composed of oxygen-containing iron sulfide particles and iron nitride particles, spraying or applying a water-soluble polymer lubricant to the surface of the punch at a surface temperature of 250 to 350°C to form a coating with a thickness of 35 μm or more on the punch surface, and performing forward or backward extrusion-forging while cooling and lubricating the punch using the water-soluble polymer lubricant so that the temperature of the punch is 250 to 350°C at a position 3 mm from the surface (see, for example, Patent Document 2).

[0004] Furthermore, there is a mold in which a coating containing at least one of Ni-P, Cr, nitrides, borides, carbon compounds, titanium compounds, tungsten compounds, diamond, and diamond-like crystals is formed on the surfaces of at least the portions of the die and punch that come into contact with the workpiece, and a lubricating substance containing B, C, F, or at least one of nitrides, borides, carbon compounds, fluorides, and sulfides is added to the coating formed on the surfaces of the portions of the die and punch where the friction coefficient is set to 85% or less (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-247188 [Patent Document 2] Patent No. 4224219 [Patent Document 3] Japanese Patent Application Publication No. 9-253770 Summary of the Invention [Problem to be solved by the invention]

[0006] However, there is a limit to how much the durability of the punch can be improved simply by forming a coating on the punch and changing the composition of the coating.

[0007] The present invention has been made in view of the above circumstances, and aims to improve the durability of the punch to a degree greater than that achieved by simply forming a coating. [Means for solving the problem]

[0008] A punch according to one aspect of the present invention is a punch used for forming or drilling by cold forging, and has a land on which a coating is formed by physical vapor deposition (PVD), and the surface of the coating has an array of concave-convex shapes with a closed contour formed by curves or a plurality of straight lines, thereby forming concave-convex shapes on the surface of the coating. The unevenness reaches a depth of one-third to two-thirds of the coating thickness from the surface of the coating, and the unevenness causes a depression of 15% to 30% (excluding 30%) of the total area of ​​the land coating. .

[0009] The contour of the uneven shape on the surface of the coating can be a single closed curve or a polygon.

[0011] The unevenness can be formed on the surface of the coating by arranging uneven shapes in a spiral around the periphery of the land.

[0012] The surface of the coating can be provided with an arrangement of circular, elliptical, oval or oval contour shapes to form irregularities on the surface of the coating.

[0013] By arranging holes of the above shape in the coating, it is possible to form unevenness.

[0014] The holes arranged in the coating may have a diameter of 20 μm to 100 μm at the surface of the coating.

[0015] By arranging shaped protrusions on the coating, it is possible to form unevenness.

[0016] The coating may include a TiN film, a TiAlN film, a CrN film, a TiCN film, or a DLC (Diamond Like Carbon) film.

[0017] The coating can be composed of multiple films.

[0018] A manufacturing method according to one aspect of the present invention is a method for manufacturing a punch used for forming or drilling by cold forging, in which a land is formed on the body of the punch, a coating is formed on the land by PVD, and a shape having a curved or a closed contour formed by a plurality of straight lines is arranged on the surface of the coating to form concaves and convexes on the surface of the coating. The unevenness reaches a depth of one-third to two-thirds of the thickness of the coating from the surface of the coating, and the unevenness causes a depression of 15% to 30% (excluding 30%) of the total area of ​​the land coating. It is something.

[0019] Another aspect of the manufacturing method of the present invention is a manufacturing method of a punch used for forming or drilling by cold forging, in which a land is formed on the body of the punch, and a shape having a closed contour formed by a curve or a plurality of straight lines is arranged on the surface of the land portion of the body to form the irregularities on the surface of the land portion of the body, and a coating is formed by PVD on the land portion of the body where the irregularities are formed. The unevenness on the surface of the coating reaches a depth of one-third to two-thirds of the thickness of the coating from the surface of the coating, and the unevenness on the surface of the coating causes a depression of 15% to 30% (excluding 30%) of the total area of ​​the land coating. It is something. [Effects of the Invention]

[0020] As described above, according to the present invention, the durability of the punch can be improved more than by simply forming a coating. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a side view showing an example of the configuration of a punch 11 according to an embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged view showing the tip end side of the punch 11. [Figure 3] FIG. 2 is an enlarged cross-sectional view showing a cross section of a coating. [Figure 4] 1A and 1B are diagrams showing examples of the shape of projections and recesses formed on the surface of a coating; [Figure 5] 10A and 10B are diagrams showing other examples of the shape of the projections and recesses formed on the surface of the coating. [Figure 6] 10 is a flowchart illustrating an example of a manufacturing method of the punch 11. [Figure 7] 10 is a flowchart illustrating another example of a method for manufacturing the punch 11. [Figure 8] FIG. 10 is a diagram showing the shape of the actual irregularities formed on the surface of the coating 32. [Figure 9] 10 is a diagram showing the measurement results of the depth of an actual recess 41 formed in a coating 32. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0022] The following describes embodiments of the present invention. The correspondence between the constituent features of the present invention and the embodiments described in the Detailed Description of the Invention is exemplified as follows: This description is intended to confirm that the embodiments supporting the present invention are described in the Detailed Description of the Invention. Therefore, even if there is an embodiment described in the Detailed Description of the Invention that corresponds to a constituent feature of the present invention but is not described here, this does not mean that the embodiment does not correspond to that constituent feature. Conversely, even if an embodiment is described here as corresponding to a constituent feature, this does not mean that the embodiment does not correspond to constituent features other than the constituent feature.

[0023] A punch according to one aspect of the present invention is a punch (e.g., punch 11 in FIG. 2) used for forming or drilling by cold forging, in which a coating is formed on a land (e.g., land 22 in FIG. 2) by physical vapor deposition (PVD), and the surface of the coating has an arrangement of irregular shapes (e.g., recesses 41 in FIG. 4) with contours closed by curves or multiple straight lines, thereby forming irregularities on the surface of the coating.

[0024] A punch according to an embodiment of the present invention will now be described with reference to FIGS.

[0025] First, the configuration of a punch 11 according to an embodiment of the present invention will be described. Fig. 1 is a side view showing an example of the configuration of the punch 11 according to an embodiment of the present invention. Fig. 2 is an enlarged view showing the tip end side of the punch 11. Fig. 3 is an enlarged cross-sectional view showing the cross section of the coating. Fig. 4 is a view showing an example of the shape of the projections and recesses formed on the surface of the coating.

[0026] The punch 11 is a die component that enters a container hole or the inside of a material during forging and applies a load. Here, the material is a metal material to be forged, 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 constitutes a die together with a mating die. In other words, the punch 11 and the die constitute a pair of dies in the vertical or horizontal direction.

[0027] The punch 11 is used for forming or punching by cold forging. For example, the punch 11 is formed in the shape of a round bar as a whole. The punch 11 is pressed against the material surrounded by the die to form it.

[0028] The punch 11 can be said to be a strong metal body whose surface is shaped to fit the dimensions or shape of the forged product, in order to press it against the material to form it.

[0029] The punch 11 is integrally formed from metal. The punch 11 includes a tip 21, a land 22, a cutting edge 23, a shank 24, and a head 25. The tip 21 is the portion that is pressed against the material surrounded by the die. The land 22 is formed on the side surface close to the tip 21. The land 22 is a mold surface portion that forms a gap with the die during forming by cold forging, and is a parallel gap that allows the material to flow out of the die. Alternatively, the land 22 is a mold surface portion that engages with the die to form a predetermined parallel gap with the die to form a hole (hole) in the material during punching by cold forging.

[0030] The tip portion 21 and the land 22 are formed to have a shape corresponding to the shape of the formed product formed by cold forging or the shape of the hole.

[0031] The cutting edge 23 is a portion formed on the tip 21 side of the punch 11, following the tip 21 and the land 22. The cutting edge 23 is also used as the name of a portion including the tip 21 and the land 22. The cutting edge 23 is inserted into a mating die during forming by cold forging or punching. For example, the cutting edge 23 is formed slightly thinner than the land 22.

[0032] The shank 24 is a mounting portion provided for mounting to a forging machine. That is, the punch 11 is mounted to the forging machine by holding the shank 24. For example, the shank 24 is formed thicker than the cutting edge 23. The head 25 is the so-called punch head portion and receives a force applied from the forging machine in the longitudinal direction of the punch 11. For example, when forming or drilling by cold forging, a force is applied from the forging machine to the head 25 of the punch 11 in a direction from left to right in FIG. 1, pressing the tip 21 against the material. For example, after forming or drilling by cold forging, a force is applied from the forging machine to the head 25 of the punch 11 in a direction from right to left in FIG. 1, removing the cutting edge 23 from the material.

[0033] The punch 11 is formed of an integral body 31 that includes a tip 21, a land 22, a cutting edge 23, 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.

[0034] As shown in FIGS. 2 and 3 , a coating 32 is formed on the surface of the land 22. The coating 32 is formed by physical vapor deposition (PVD). PVD is a method of evaporating metals or compounds using physical methods such as resistance heating, electron beam heating, or sputtering, and depositing them on a substrate (target object (in this case, the main body 31)) to form a coating. Typical PVD methods include vacuum deposition, ion plating, and sputtering. For example, the coating 32 is formed on the surface of the land 22 by ion plating. Ion plating is a deposition technique in which a deposition material is positively charged in plasma and a substrate is negatively charged. Because the coating 32 is formed by PVD, a wide variety of materials are available for the coating 32, and multi-component alloys can be particularly used for the coating 32. Furthermore, because the coating 32 is formed by PVD, the coating 32 can be formed at a lower temperature, thereby suppressing dulling and dimensional changes in the main body 31.

[0035] The coating 32 includes at least one of a TiN (Titanium Nitride) film, a TiAlN (Titanium Aluminum Nitride) film, a CrN (Chromium Nitride) film, a TiCN (Titanium Carbon Nitride) film, and a DLC (Diamond Like Carbon) film. The coating 32 may be made 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 5 μm.

[0036] As shown in Figures 3 and 4, the surface of the coating 32 is uneven. In Figure 3, the horizontal direction corresponds to the horizontal direction in Figures 1 and 2. Note that the horizontal scale and the vertical scale are different in Figure 3. In Figure 4, the vertical direction corresponds to the horizontal direction in Figures 1 and 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 periphery (the vertical direction in Figures 1 and 2) when the cylindrical land 22 is developed into a plane as the side surface of a cylinder.

[0037] The unevenness on the surface of the coating 32 is formed by repeatedly arranging depressions 41 and protrusions 42, each having an uneven shape with a closed contour formed by a curve or a plurality of straight lines, on the surface of the coating 32. That is, the unevenness on the surface of the coating 32 is formed by arranging depressions 41 and protrusions 42. The term "arranged" includes an evenly spaced arrangement in which they are lined up at equal intervals, a staggered arrangement in which they are lined up alternately, a randomly spaced arrangement in which they are lined up at random intervals, a pattern arrangement in which they are lined up at intervals in a predetermined pattern, and so on, and also includes arranging them in rows at desired intervals and arranging them so that there is a predetermined offset in a direction intersecting the direction of the rows.

[0038] A plurality of recesses 41 are formed on the surface of the coating 32. The protrusions 42 are the portions of the surface of the coating 32 other than the recesses 41. Each recess 41 is a hole with a circular outline 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). Note that, for example, each recess 41 may be formed in any curved shape, may be formed so that the bottom surface is flat, or may be formed so that the cross section is a linear slope.

[0039] 3, the recess 41 does not reach the main body 31. That is, the recess 41 is a recess in the coating 32. In other words, the depth of the recess 41 is less than the film thickness of the coating 32.

[0040] For example, a plurality of 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 in an array on the surface of the coating 32. For example, the recesses 41 are arranged in a single spiral on the surface of the land 22, while being aligned in a row in a predetermined direction. More specifically, the recesses 41 are arranged in a single spiral on the surface of the land 22, while being aligned in a row in the longitudinal direction of the punch 11.

[0041] For example, the recesses 41 may be arranged in two rows in a predetermined direction and in a double spiral on the surface of the land 22. More specifically, the recesses 41 may be arranged in two rows in the longitudinal direction of the punch 11 and in a double spiral on the surface of the land 22.

[0042] In this way, the recesses 41 are arranged in one or more spirals on the surface of the land 22. That is, the recesses 41 can be arranged in a spiral on the surface of the land 22.

[0043] For example, the area of ​​the recesses 41 on the surface of the coating 32 is set to 20% of the entire surface of the coating 32. The area of ​​the recesses 41 on the surface of the coating 32 is preferably 5% to 50% of the entire surface 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.

[0044] More preferably, the area of ​​the recesses 41 on the surface of the coating 32 is 10% or more and 40% or less of the entire surface of the coating 32. In this case, the number of times that the punch 11 can be used for cold forging is significantly increased. When durability of the punch 11 is important, the area of ​​the recesses 41 is set to 15% or more and 30% or less of the entire surface of the coating 32. In this case, the number of times that the punch 11 can be used for cold forging is significantly increased.

[0045] For example, the depth of the recess 41 reaches half the thickness of the coating 32 from the surface of the coating 32. The depth of the recess 41 preferably reaches one-quarter to three-quarters the thickness of the coating 32 from the surface of the coating 32. In this case, the number of times the punch 11 can be used for cold forging is clearly increased.

[0046] More preferably, the depth of the recess 41 is set to a depth that reaches from the surface of the coating 32 to one-third to two-thirds of the thickness of the coating 32. In this case, the number of times that the punch 11 can be used for cold forging is significantly increased. When durability of the punch 11 is required, the depth of the recess 41 is set to a depth that reaches from the surface of the coating 32 to two-fifths to three-fifths of the thickness of the coating 32. In this case, the number of times that the punch 11 can be used for cold forging is significantly increased, and seizure of the land 22 is clearly reduced.

[0047] 5A and 5B are diagrams showing other examples of the shape of the concaves and convexes arranged on the surface of the coating 32. For example, as shown in Fig. 5A, a plurality of concaves 61 are formed on the surface of the coating 32. The contours of the concaves 61 are elliptical on the surface of the coating 32. On the surface of the coating 32, the portions other than the concaves 61 are convex portions.

[0048] 5(B), a plurality of 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. On the surface of the coating 32, the portions other than the recesses 62 are protrusions.

[0049] The contour of the recesses on the surface of the coating 32 may also be egg-shaped or oval-shaped.

[0050] 5(C), a plurality of 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. On the surface of the coating 32, the portions other than the recesses 63 are convex portions.

[0051] The contour of the recesses on the surface of the coating 32 can also be a quadrilateral such as a rectangle, square, or trapezoid. Furthermore, the contour of the recesses on the surface of the coating 32 can also be a convex polygon such as a triangle, pentagon, or hexagon. Furthermore, the contour of the recesses on the surface of the coating 32 can also be a concave polygon such as a gear shape (cross-sectional shape in a cross section perpendicular to the rotation axis of the gear) or a star shape (star polygon).

[0052] Furthermore, it has been described that the contours of the recesses 41, 61, and 62 are circular, elliptical, and oval, respectively, on the surface of the land 22, and that the contours of the recesses can also be egg-shaped or oval. However, the contours of the protrusions 42 can also be circular, elliptical, oval, egg-shaped, or oval, respectively, on the surface of the land 22. In this case, the contours of the protrusions 42 can be formed into a predetermined shape by cutting the recesses so as to leave the protrusions 42. Similarly, it has been described that the contours of the recesses 63 are rounded rectangles on the surface of the land 22, and that the contours of the recesses can also be quadrilaterals such as rectangles, squares, and trapezoids; convex polygons such as triangles, pentagons, and hexagons; or concave polygons such as gear shapes and star shapes. However, the contours of the protrusions 42 can also be quadrilaterals, convex polygons, or concave polygons, respectively, on the surface of the land 22.

[0053] In this way, the recesses on the surface of the coating 32 can be formed in a shape surrounded by a single closed curve. Also, the recesses on the surface of the coating 32 can be formed in a shape surrounded by a polygon.

[0054] Furthermore, the convex portions on the surface of the coating 32 may be formed in a shape surrounded by a single closed curve, or in a shape surrounded by a polygon.

[0055] In this way, unevenness is formed on the surface of the coating 32 by repeating uneven shapes surrounded by a single closed curve or uneven shapes surrounded by a polygon on the surface of the coating 32.

[0056] That is, it can be said that unevenness is formed on the surface of the coating 32 by repeatedly arranging shapes that form concave and convex contours closed by curves or multiple straight lines on the surface of the coating 32. In other words, unevenness is formed on the surface of the coating 32 by arranging shapes that form concave and convex contours closed by curves or multiple straight lines on the surface of the coating 32.

[0057] Next, an example of a method for manufacturing the punch 11 will be described with reference to the flowchart in Fig. 6. In step S11, the land 22 is formed on the body 31 of the punch 11. For example, in step S11, the land 22 is formed on the body 31 of the punch 11 by cutting or powder metallurgy molding, heat treatment such as quenching or annealing, or polishing. In step S12, a coating 32 is formed on the land 22 by PVD. For example, in step S12, the coating 32 is formed on the surface of the land 22 by ion plating.

[0058] In step S13, unevenness is formed on the surface of the coating 32 by arranging shapes that form concaves and convexes with closed contours on the surface of the coating 32. For example, in step S13, recesses 41, recesses 61, or recesses 62 are repeatedly arranged on the surface of the coating 32, thereby forming unevenness on the surface of the coating 32. For example, in step S13, recesses 63 are repeatedly arranged on the surface of the coating 32, thereby forming unevenness on the surface of the coating 32. In this way, unevenness is formed on the surface of the coating 32 by arranging shapes that form concaves and convexes with a contour of a single closed curve or a polygon on the surface of the coating 32 in step S13. For example, unevenness is formed on the surface of the coating 32 by laser processing (laser removal processing) in step S13. In this way, unevenness is formed on the surface of the coating 32 by arranging shapes that form concaves and convexes with a contour that is closed by a curve or a plurality of straight lines on the surface of the coating 32 in step S13.

[0059] In this way, a land 22 is formed on the body 31 of the punch 11, a coating 32 is formed on the land 22 by PVD, and unevenness is formed on the surface of the coating 32 by arranging shapes that form uneven contours closed by curves or multiple straight lines on the surface of the coating 32.

[0060] Next, another example of a method for manufacturing the punch 11 will be described with reference to the flowchart of Fig. 7. In step 31, the land 22 is formed in the body 31 of the punch 11. The procedure of step 31 is similar to the procedure of step 11, and therefore a detailed description thereof will be omitted.

[0061] In step S32, unevenness is formed on the surface of the land 22 portion of the main body 31 by arranging shapes that form concaves and convexes with closed contours on the surface of the land 22 portion of the main body 31. For example, in step S32, recesses having a shape similar to any of the recesses 41, 61, or 62 are repeatedly arranged on the surface of the land 22 portion of the main body 31, thereby forming unevenness on the surface of the land 22 portion of the main body 31. For example, in step S32, recesses having a shape similar to the recess 63 are repeatedly arranged on the surface of the land 22 portion of the main body 31, thereby forming unevenness on the surface of the land 22 portion of the main body 31. In this way, unevenness is formed on the surface of the land 22 portion of the main body 31 by arranging shapes that form concaves and convexes with a contour of a single closed curve or a polygon on the surface of the land 22 portion of the main body 31 in step S32. For example, unevenness is formed on the surface of the land 22 portion of the main body 31 by laser processing (laser removal processing) in step S32. In this way, in step S32, unevenness is formed on the surface of the land 22 portion of the main body 31 by arranging shapes that form uneven contours closed by curves or multiple straight lines on the surface of the land 22 portion of the main body 31.

[0062] In step S33, the coating 32 is formed on the lands 22 by PVD. That is, in step S33, the coating 32 is formed by PVD on the surface of the part of the main body 31 that corresponds to the land 22. For example, in step S33, the coating 32 is formed by ion plating on the surface of the part of the main body 31 that corresponds to the land 22. More specifically, in step S33, the coating 32 having a certain thickness is formed by PVD on the surface of the part of the main body 31 that corresponds to the land 22, and the surface of the coating 32 has irregularities corresponding to the irregularities formed on the surface of the part of the main body 31 that corresponds to the irregularities formed on the surface of the part of the land 22.

[0063] In this way, a land 22 is formed on the body 31 of the punch 11, and by arranging a shape of irregularities with a closed contour formed by curves or multiple straight lines on the surface of the part of the land 22 on the body 31, irregularities are formed on the surface of the part of the land 22 on the body 31, and a coating 32 is formed by PVD on the part of the land 22 on the body 31 where the irregularities are formed.

[0064] 8 and 9 show the measurement results of the shape of the recesses 41 actually formed. FIG. 8 shows the shape of the actual unevenness formed on the surface of the coating 32. FIG. 9 shows the measurement results of the depth of the recesses 41 actually formed in the coating 32. The thickness of the coating 32 in FIGS. 8 and 9 is 4 μm. The recesses 41 in FIGS. 8 and 9 are formed by laser processing. The recesses 41 are cut while moving relative to the surface of the land 22, so they have a shape close to an ellipse or oval. The diameter of one recess 41 on the surface of the coating 32 was 48.410 μm. The depth of one recess 41 from the surface of the coating 32 reached 2.0702 μm. The distance between two recesses 41 on the surface of the coating 32 was approximately 100 μm to 120 μm.

[0065] As shown in FIG. 9, the surface of the protrusion 42 is formed to be smooth.

[0066] The number of times that the punch 11 having the recess 41 shown in Figures 8 and 9 formed thereon can be used for cold forging is about twice as many as the number of times that a punch having a coating of a constant thickness formed on its land can be used for cold forging. The number of times that a punch having a coating of a constant thickness formed on its land can be used for cold forging is about twice as many as the number of times that a punch having no coating formed on its land can be used for cold forging. Therefore, the number of times that a punch 11 having the recess 41 shown in Figures 8 and 9 formed thereon can be used for cold forging is about four times as many as the number of times that a punch having no coating formed on its land can be used for cold forging.

[0067] In this way, the durability of the punch can be improved more than by simply forming a coating.

[0068] It should be noted that, based on the results of measuring the number of times punch 11 can be used for cold forging, it is preferable that the diameter of one recess 41 on the surface of coating 32 is 20 μm to 100 μm.

[0069] Alternatively, the recessed portion may be formed by carving one or more grooves in a spiral shape in the land 22.

[0070] In this way, the coating 32 is formed on the land 22, and the surface of the coating 32 is arranged with an uneven shape having a closed contour made up of curves or multiple straight lines, thereby forming unevenness on the surface of the coating 32. Therefore, when pressure is applied during cold forging, the coating 32 near the unevenness is deformed with a smaller force, and a steady lubricated state is achieved with the coating 32 having a smaller deformation resistance, making it less likely to break.

[0071] In addition, a coating 32 is formed on the land 22, and an uneven shape with a closed contour made up of curves or multiple straight lines is arranged on the surface of the coating 32, thereby forming unevenness on the surface of the coating 32.Therefore, 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 over the entire surface of the land 22.As a result, even if the surface pressure increases, destruction of the boundary lubricant film is suppressed in the protruding parts of the surface, making adhesion less likely to occur.

[0072] As described above, the durability of the punch can be improved more than by simply forming a coating.

[0073] When the coating 32 is formed on the land 22 by PVD, the surface of the coating 32 may be made uneven by masking. Alternatively, the surface of the coating 32 may be made uneven by etching.

[0074] The punch 11 is used for forming or drilling by cold forging. The punch 11 is provided with a land 22. A coating 32 is formed on the land 22 by PVD. The unevenness is formed on the surface of the coating 32 by arranging uneven shapes with a closed contour formed by curves or multiple straight lines on the surface of the coating 32.

[0075] The contour of the uneven shape on the surface of the coating 32 can be a single closed curve or a polygon.

[0076] On the surface of the coating 32, irregularities can be formed that are one-third to two-thirds the thickness of the coating 32 and occupy an area of ​​10% to 40% of the surface area of ​​the coating 32.

[0077] The unevenness can be formed on the surface of the coating 32 by arranging uneven shapes in a spiral around the periphery of the land 22 .

[0078] The surface of the coating 32 can be provided with an arrangement of circular, elliptical, oval or oval contour shapes to form irregularities on the surface of the coating 32 .

[0079] The unevenness can be formed by arranging holes in the coating 32 in the shape of a circular, elliptical, oval or oval outline.

[0080] The diameter of the holes arranged in the coating 32 at the surface of the coating 32 can be 20 μm to 100 μm.

[0081] By arranging projections having a circular, elliptical, oval or oval outline on the coating 32, the unevenness can be formed.

[0082] The coating 32 may include a TiN film, a TiAlN film, a CrN film, a TiCN film, or a DLC (Diamond Like Carbon) film.

[0083] The coating 32 may be composed of multiple layers.

[0084] The punch 11 is manufactured by forming a land 22 on the body 31 of the punch 11, depositing a coating 32 on the land 22 by PVD, and arranging uneven shapes on the surface of the coating 32 that have a closed contour formed by curves or multiple straight lines, thereby forming unevenness on the surface of the coating.

[0085] In addition, the punch 11 is manufactured by forming a land 22 on the body 31 of the punch 11, arranging a shape that forms an unevenness with a closed contour formed by curves or multiple straight lines on the surface of the part of the land 22 on the body 31, thereby forming an unevenness on the surface of the part of the land 22 on the body 31, and depositing a coating 32 by PVD on the part of the land 22 on the body 31 where the unevenness is formed.

[0086] Furthermore, the embodiments of the present invention are not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present invention. [Explanation of symbols]

[0087] 11 punch, 21 tip, 22 land, 23 cutting edge, 24 shank, 25 head, 31 body, 32 coating, 41 recess, 42 protrusion, 61 to 63 recess

Claims

1. In a punch used for forming or drilling by cold forging, The land is coated with a film by PVD (Physical Vapor Deposition), the unevenness is formed on the surface of the coating by arranging uneven shapes having a closed contour formed by curves or a plurality of straight lines on the surface of the coating, the irregularities reach a depth of one-third to two-thirds of the thickness of the coating from the surface of the coating, The unevenness causes a depression of 15% to 30% (excluding 30%) of the area of ​​the land relative to the entire area of ​​the coating. punch.

2. 2. The punch according to claim 1, A punch in which the contour of the shape forming the irregularities on the surface of the coating is a single closed curve or a polygon.

3. 2. The punch according to claim 1, The uneven shape is arranged in a spiral around the land, thereby forming unevenness on the surface of the coating. punch.

4. 2. The punch according to claim 1, The shape of the contour of a circle, ellipse, oval, or round is arranged on the surface of the coating, thereby forming irregularities on the surface of the coating. punch.

5. In the punch according to claim 4, The punch has holes of the shape arranged in the coating to form projections and recesses.

6. In the punch according to claim 5, A punch in which the holes arranged in the coating have a diameter of 20 μm to 100 μm at the surface of the coating.

7. In the punch according to claim 4, The punch has projections of the above shape arranged on the coating, thereby forming projections and recesses.

8. 2. The punch according to claim 1, The punch, wherein the coating includes a TiN film, a TiAlN film, a CrN film, a TiCN film, or a DLC (Diamond Like Carbon) film.

9. In the punch according to claim 8, The coating is a punch made of a multi-layer film.

10. A method for manufacturing a punch used for forming or drilling by cold forging, forming a land on the body of the punch; A coating is formed on the land by PVD, forming projections and recesses on the surface of the coating by arranging shapes having contours closed by curves or a plurality of straight lines on the surface of the coating; the irregularities reach a depth of one-third to two-thirds of the thickness of the coating from the surface of the coating, The unevenness causes a depression of 15% to 30% (excluding 30%) of the area of ​​the land relative to the entire area of ​​the coating. Manufacturing method.

11. A method for manufacturing a punch used for forming or drilling by cold forging, forming a land on the body of the punch; forming projections and recesses on the surface of the land portion of the main body by arranging shapes having a contour closed by curves or a plurality of straight lines on the surface of the land portion of the main body; forming a coating by PVD on the land portion of the body having the irregularities formed thereon; the irregularities on the surface of the coating reach a depth of one-third to two-thirds of the thickness of the coating from the surface of the coating, The unevenness on the surface of the coating causes a depression of 15% to 30% (excluding 30%) of the area of ​​the land relative to the entire area of ​​the coating. Manufacturing method.

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