Press mold and method for manufacturing cylindrical component

Abstract

To provide a technique capable of manufacturing a cylindrical component open at both ends and high in shape quality from a one-end bottomed cylindrical workpiece having a non-circular bottom wall.SOLUTION: A press mold 10 comprises: a punch 11 that is for pressuring a bottom wall 91 so as to form a R shape of an outer edge corner 93 of a one-end bottomed cylindrical workpiece 90 similar to a sharp square shape and pushed into the inside of the cylindrical workpiece 90; a die 13 that has a workpiece reception hole 12 into which the cylindrical workpiece 90 is pushed by the punch 11; a counter punch 14 that holds and pressurizes the bottom wall 91 cooperatively with the punch 11 in the workpiece reception hole 12, and causes the thickness of the bottom wall 91 to flow to the outer edge corner 93 side; and a recess 15 formed in at least one of the pressurizing surfaces of the counter punch 14 and the punch 11, and used for receiving an excess thickness flowing due to pressurization.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a press die for pressing a bottom wall so as to make the R shape of the outer edge corner of a cylindrical workpiece with one end having a bottom approach a sharp corner shape, and a manufacturing method for manufacturing a cylindrical part with both ends open from a cylindrical workpiece with one end having a bottom.

Background Art

[0002] As a conventional manufacturing method for cylindrical parts, there is known a manufacturing method in which the bottom wall of a cylindrical workpiece with one end having a bottom is pressed to make the R shape of the outer edge corner of the cylindrical workpiece approach a sharp corner shape, and then the bottom wall is punched out to manufacture a cylindrical part with both ends open (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the conventional manufacturing method for cylindrical parts, when the bottom wall of the cylindrical workpiece is circular, the bottom wall material that is uniformly pressed over the entire outer edge corner of the cylindrical workpiece is supplied, and the shape quality of the cylindrical part after the bottom wall is punched out is good. However, when the bottom wall of the cylindrical workpiece is non-circular, a difference occurs between the portion where a large amount of material is supplied and the portion where a small amount of material is supplied at the outer edge corner, and the shape quality of the outer edge corner of the cylindrical workpiece with the bottom pressed decreases. For this reason, there is a problem that the occurrence rate of poor shape quality of the cylindrical part after the bottom wall is punched out becomes high.

[0005] Therefore, the present application discloses a technique that enables manufacturing of a cylindrical part with both ends open and high shape quality from a cylindrical workpiece with one end having a non-circular bottom wall.

Means for Solving the Problems

[0006] A first aspect of the invention of the present disclosure made to solve the above problems is a press die for pressing the bottom wall so as to bring the R shape of the outer edge corner where the outer surface of the non-circular bottom wall of a cylindrical workpiece with a bottom at one end intersects the outer side surface of the cylindrical workpiece closer to a sharp corner shape, including a punch that is pushed into the inside of the cylindrical workpiece, a die having a workpiece receiving hole into which the cylindrical workpiece is pushed by the punch, a counter punch that cooperates with the punch in the workpiece receiving hole to press the bottom wall therebetween and cause the material of the bottom wall to flow toward the outer edge corner side, and a recess formed on at least one of the pressing surfaces of the counter punch and the punch for receiving the excess material that flows due to the pressing.

[0007] Also, a second aspect of the invention of the present disclosure made to solve the above problems is a manufacturing method for manufacturing a cylindrical component with open ends from a cylindrical workpiece, including a pressing step in which the cylindrical workpiece is pushed into a workpiece receiving hole of a die by a punch, and the bottom wall is sandwiched between a counter punch and the punch and pressed to bring the R shape of the outer edge corner where the outer surface of the non-circular bottom wall of the cylindrical workpiece with a bottom at one end intersects the outer side surface of the cylindrical workpiece closer to a sharp corner shape, and a punching step in which the bottom wall is punched out from the cylindrical workpiece, wherein a recess for receiving the excess material that flows due to the pressing is formed on at least one of the pressing surfaces of the counter punch and the punch.

Advantages of the Invention

[0008] In the first and second aspects of the invention of the present disclosure, when the bottom wall of the cylindrical workpiece is pressed by the punch and the counter punch, the excess material among the material that flows due to the pressing is received in the recess of the punch or the counter punch. As a result, even if the bottom wall is non-circular, the difference in the supply amount of the material to the outer edge corner of the cylindrical workpiece is suppressed more than before, and the shape quality of the outer edge corner of the cylindrical workpiece becomes better than before. And the bottom wall of the cylindrical workpiece can be suitably punched out, and it becomes possible to manufacture a cylindrical component with open ends having a high shape quality from a cylindrical workpiece with a bottom at one end having a non-circular bottom wall.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0010] Referring to FIGS. 1 to 6, an embodiment of a pressing die 10 and a method for manufacturing a cylindrical part 95 according to the present disclosure will be described. The cylindrical part 95 of this embodiment is, as shown in FIG. 1C, for example, a cylindrical body with open ends extending in a shape where the four corners of a rectangular cross-section are rounded with R chamfers. The metal constituting the cylindrical part 95 is, for example, copper (including copper alloys), aluminum (including aluminum alloys), molybdenum (including molybdenum alloys), etc.

[0011] Further, when the outer peripheral length in the cross-sectional shape of the cylindrical part 95 is L1 and the wall thickness is t, the wall thickness-to-outer peripheral length ratio R1 (= t / L1), which is the ratio of the wall thickness t to the outer peripheral length L1, is 0.025 or more and 0.1 or less. More specifically, the long side and the short side of the rectangle, which is the cross-sectional shape of the cylindrical part 95, are 5 [mm] or less, the outer peripheral length L1 is 20 [mm] or less, and the wall thickness t of the cylindrical wall of the cylindrical workpiece is 0.5 [mm] or more. Here, the wall thickness-to-outer peripheral length ratio R1 of a general cylindrical part formed by press forming is 0.02 or less. The cylindrical part 95 of the present embodiment is a cylindrical part with a well-balanced wall thickness with respect to the overall shape, that is, a "thick-walled cylindrical part", compared to a general cylindrical part. Further, since the outer peripheral length L1 of the cross-sectional shape of the cylindrical part 95 is 20 [mm] or less, it is extremely small as a cylindrical part that is a press-formed product.

[0012] The cylindrical part 95 is manufactured by punching out the bottom wall 91 from a bottomed cylindrical workpiece 90 shown in Fig. 1A. The cylindrical workpiece 90 is manufactured, for example, by drawing a sheet metal into a bottomed cup shape and further drawing it a plurality of times or, if necessary, ironing it. Further, in order to perform the drawing and ironing smoothly, the outer edge corner 93 where the outer surface 91A of the bottom wall 91 and the outer side surface 92S of the side wall 92 of the cylindrical workpiece 90 intersect has an R-chamfered shape and has an arc surface 93R.

[0013] Here, the radius of curvature of the arc surface 93R is preferably large for performing the drawing and ironing suitably, but is preferably small for performing the punching process of punching out the bottom wall 91 from the cylindrical workpiece 90 suitably. Further, as described above, the cylindrical part 95 of the present embodiment has a larger wall thickness-to-outer peripheral length ratio R1 and is thicker than a general one, so the size of the arc surface 93R with respect to the overall shape is also larger than that of a general one. Due to these, before punching out the bottom wall 91 from the cylindrical workpiece 90, it is necessary to perform a pressurizing process of pressurizing the bottom wall 91 of the cylindrical workpiece 90 to make the R shape of the outer edge corner 93 of the cylindrical workpiece 90 approach a sharp corner shape (so-called pin corner shape), and the press die 10 shown in Fig. 2 is used for that pressurizing process.

[0014] In addition, the shape of the cylindrical workpiece 90 other than the bottom wall 91 and the outer edge corner 93 is the same as that of the cylindrical part 95 or, even if there are differences, it falls within the range of the dimensions and the range of the wall thickness - outer perimeter ratio R1 described for the cylindrical part 95 above, and the dimensions and the wall thickness - outer perimeter ratio R1 of the cylindrical workpiece 90 are of the same degree as those of the cylindrical part 95.

[0015] The press die 10 includes a punch 11, a die 13, and a counter punch 14 as shown in FIG. 2. The punch 11 is fixed to the ram of a press machine (not shown) and reciprocates, for example, in the vertical direction. The cross-sectional shape of at least the tip of the punch 11 forms a rectangle sized to fit exactly inside the cylindrical workpiece 90. Also, the tip surface of the punch 11 is a flat surface perpendicular to the moving direction of the punch 11, and the corners between the tip surface and the outer surface of the punch 11 are chamfered with an R.

[0016] Also, at the center of the tip surface of the punch 11, one end of a vent hole (not shown) is open. The vent hole extends along the center of the punch 11 from the tip to the base end of the punch 11, and the other end of the vent hole opens at the base end surface of the punch 11, or the vent hole bends laterally in the middle and opens at the side surface of the portion of the punch 11 that does not fit inside the cylindrical workpiece 90. Note that a configuration without a vent hole may also be adopted.

[0017] The die 13 is fixed to the die holder 40 of the press machine and has a workpiece receiving hole 12 into which the cylindrical workpiece 90 is pushed by the punch 11. The workpiece receiving hole 12 has a rectangular cross-section and the cylindrical workpiece 90 fits exactly inside it. Also, a through hole 41 is provided coaxially below the workpiece receiving hole 12 in the die holder 40.

[0018] The counter punch 14 is supported so as to be linearly movable in, for example, the work receiving hole 12 and the through hole 41, receives power from the same power source as the ram, and reciprocates in the vertical direction in synchronization with the punch 11. Then, the counter punch 14 cooperates with the punch 11 in the work receiving hole 12 to press the bottom wall 91 of the cylindrical work 90 with the bottom wall 91 sandwiched therebetween, and causes the material of the bottom wall 91 to flow toward the outer edge corner portion 93. Note that the counter punch 14 may be configured to receive power from a power source different from that of the ram. Further, the punch 11 and the counter punch 14 may be configured to reciprocate in the horizontal direction or the diagonal vertical direction.

[0019] The counter punch 14 has a rectangular cross-sectional shape at least at the tip portion, and has a size that fits exactly inside the work receiving hole 12. Then, as shown in FIG. 3, the tip surface 14S of the counter punch 14 is provided with a pressing portion 14H which is a flat surface orthogonal to the moving direction of the counter punch 14, and a concave portion 15 that is recessed from the pressing portion 14H. Further, the corner portion between the tip surface 14S and the outer surface of the counter punch 14 has an unpitched pin corner shape, or has a shape that is very slightly chamfered and is close to the pin corner shape.

[0020] The concave portion 15 has, for example, an elongated octagonal shape in which the four corners of a rectangle smaller than the outer shape of the tip surface 14S are cut linearly as shown in FIG. 4. Further, the area of the concave portion 15 with respect to the area of the tip surface 14S is, for example, 40% or more. Further, as shown in FIG. 3, the bottom surface 15X of the concave portion 15 forms a flat surface parallel to the tip surface 14S, and the side surface 15Y of the concave portion 15 is inclined so as to narrow toward the bottom surface 15X. One end of a gas vent hole (not shown) is opened at the center of the bottom surface 15X, and the other end of the gas vent hole is opened at the base end surface or the side surface of the counter punch 14 in the same manner as the gas vent hole of the punch 11 described above.

[0021] An example of a die 20 for necking or ironing a cylindrical workpiece 90 is shown in FIG. 5A immediately before performing the above-described pressing step. Also, an example of a press die 30 for performing a punching step after the pressing step is shown in FIGS. 6A and 6B. Since the punches 21, 31, the counter punches 24, 34, and the dies 23, 33 of these press dies 20, 30 have the same structure as known ones, the description of their structures is omitted. Also, in the following description, in order to distinguish the press dies 10, 20, 30, the press die 10 is appropriately referred to as the "pressing die 10", the press die 20 is referred to as the "forming die 20", and the press die 30 is referred to as the "punching die 30".

[0022] Next, a method for manufacturing the cylindrical component 95 will be described with reference to FIGS. 5A to 5C, 6A, and 6B. As shown in FIG. 5A, the cylindrical workpiece 90 is necked or ironed in the workpiece receiving hole 22 of the die 23 of the forming die 20, and after being pushed upward from the workpiece receiving hole 22 by the counter punch 24, it is set in the pressing die 10.

[0023] Specifically, the cylindrical workpiece 90 discharged from the forming die 20 is gripped laterally by a gripping mechanism (not shown) with the bottom wall 91 facing downward, and is disposed coaxially above the workpiece receiving hole 12 of the die 13. Then, the punch 11 descends and penetrates into the cylindrical workpiece 90, and the cylindrical workpiece 90 is pushed into the workpiece receiving hole 12 by the punch 11. Then, as shown in FIG. 5B, the bottom wall 91 of the cylindrical workpiece 90 is sandwiched and pressed by the counter punch 14 and the punch 11 waiting in the workpiece receiving hole 12.

[0024] Then, as shown in FIG. 5C, the portion of the bottom wall 91 that does not face the recess 15 is crushed by the pressing portion 14H of the counter punch 14 and the punch 11, and the material of the bottom wall 91 flows toward the outer edge corner portion 93 of the cylindrical workpiece 90. As a result, the outer edge corner portion 93 is formed into a pointed shape from the R shape. Further, the portion of the bottom wall 91 that faces the recess 15 is crushed by the punch 11 and the counter punch 14 around it and becomes thinner, then enters the recess 15, and a bulging protrusion 94 (see FIG. 1B) that protrudes from the entire bottom wall 91 is formed. Thereby, the excess material that would be excessive for bringing the outer edge corner portion 93 of the cylindrical workpiece 90 closer to a pointed corner shape is prevented from flowing toward the outer edge corner portion 93 side.

[0025] Here, since the bottom wall 91 of the cylindrical workpiece 90 of the present embodiment is non-circular, the ease of material flow toward the outer edge corner portion 93 is different. That is, the material that flows when the bottom wall 91 is pressed flows more easily to the portion with a larger radius of curvature than the portion with a smaller radius of curvature among the outer edges of the bottom wall 91. More specifically, since the bottom wall 91 of the cylindrical workpiece 90 is quadrilateral, the material flows more easily to the straight portion (range of S2 in FIG. 4) with an infinite radius of curvature than the corner portion (range of S1 in FIG. 4) of the quadrilateral.

[0026] On the other hand, as shown in FIG. 4, since the recess 15 forms an elongated octagon in which the four corners of a rectangle smaller than the rectangle of the outer edge shape of the bottom wall 91 are cut, the straight portion is closer to the opening edge of the recess 15 than the corner portion of the outer edge shape of the bottom wall 91. Thereby, while suppressing the supply of excessive material to the straight portion where the material of the outer edge shape of the bottom wall 91 easily flows, the material supplied to the corner portion where the material hardly flows is ensured, and the difference in the amount of material supplied due to the difference in the location of the outer edge corner portion of the bottom wall 91 can be suppressed more than before.

[0027] When the punch 11 rises beyond the bottom dead center together with the ram, the counter punch 14 also rises following it. Then, the cylindrical workpiece 90 is discharged from the pressing die 10 (specifically, the workpiece receiving hole 12), gripped by a gripping mechanism (not shown), and set in the punching die 30.

[0028] The setting of the cylindrical workpiece 90 into the punching die 30 is performed in the same manner as in the case of the pressing die 10. Then, as shown in FIG. 6A, the cylindrical workpiece 90 is pushed into the workpiece receiving hole 32 by the punch 31 of the punching die 30 and pressed against the counter punch 34. Here, the counter punch 34 of the punching die 30 has a rectangular tube shape having an inner surface that is substantially flush with or slightly smaller than the inner surface of the cylindrical workpiece 90. Further, the punch 31 has a rectangular column shape having an outer surface that is substantially flush with or slightly smaller than the inner surface of the cylindrical workpiece 90. Then, the tip surface of the counter punch 34 abuts against the outer edge portion of the lower surface of the cylindrical workpiece 90 including the flat surface formed in the above-described pressing step of the lower surface of the cylindrical workpiece 90. Then, as shown in FIG. 6B, the punch 31 descends to a position where it penetrates into the counter punch 34, and the bottom wall 91 is sheared and punched out from the side wall 92. Thereby, the cylindrical workpiece 90 having a bottom at one end becomes a cylindrical part 95 having both ends open. And, similar to the pressing die 10, also in the punching die 30, when the punch 31 exceeds the bottom dead center, it rises together with the counter punch 34, and the cylindrical workpiece 90 is discharged from the workpiece receiving hole 32. Thus, the manufacture of the cylindrical part 95 is completed.

[0029] As described above, according to the present embodiment, when the bottom wall 91 of the cylindrical workpiece 90 is pressed, the excess meat among the meat that flows due to the pressing is received in the recess 15 of the counter punch 14. Therefore, even if the bottom wall 91 is non-circular, the difference in the supply amount of the meat to the outer edge corner portion 93 of the cylindrical workpiece 90 is suppressed more than before. Moreover, in the recess 15, the opening edge of the recess 15 is closer to the place where the radius of curvature of the outer edge shape is larger among the outer edges of the bottom wall 91. Therefore, the difference in the supply amount of the meat to the outer edge corner portion 93 of the cylindrical workpiece 90 can be further suppressed more than before. As a result, the shape quality of the outer edge corner portion 93 of the cylindrical workpiece 90 becomes better than before. And, the bottom wall 91 of the cylindrical workpiece 90 can be suitably punched out, and it becomes possible to manufacture a cylindrical part having both ends open with high shape quality from the cylindrical workpiece 90 having a non-circular bottom wall 91 at one end.

[0030] In addition, the cylindrical workpiece 90 of the present embodiment has an extremely small outer peripheral length of 20 [mm] or less, and the arc surface 93R of the outer edge corner 93 is larger compared to the size of the entire cylindrical workpiece 90. In conventional press dies and manufacturing methods, defects in shape quality are likely to occur. However, by providing the counter punch 14 with the recess 15, a significant reduction in shape quality defects can be achieved.

[0031] [Other Embodiments] In the cylindrical workpiece 90 of the above embodiment, the outer peripheral length L1 was 20 [mm] or less and the wall thickness t was 0.5 [mm] or more. However, the size and wall thickness of the cylindrical workpiece 90 are not limited to this, and the cylindrical workpiece 90 may have any size and thickness.

[0032] The cylindrical workpiece 90 and the cylindrical component 95 of the above embodiment had a uniform cross-sectional shape throughout the axial direction. However, the cross-sectional shape may change midway. Specifically, one end side, which is the bottom wall 91 side, of the cylindrical workpiece 90 and the cylindrical component 95 may be polygonal, elliptical, or other non-circular shapes, and the other end side of the cylindrical workpiece 90 and the cylindrical component 95 may expand into a polygonal, elliptical, or other non-circular shape different from the one end side, or a circular shape. Also, the other end side of the cylindrical workpiece 90 and the cylindrical component 95 may expand with the same shape as the one end side.

[0033] In the above embodiment, the axial lengths of the cylindrical workpiece 90 and the cylindrical component 95 were substantially the same. However, for example, while punching out the bottom wall 91 at one end of the cylindrical workpiece 90 and cutting off the other end portion of the bottom wall 91 to manufacture the cylindrical component 95, the axial lengths of the cylindrical workpiece 90 and the cylindrical component 95 may be different.

[0034] The pressure die 10 of the above embodiment was only for pressing the bottom wall 91 of the cylindrical workpiece 90. However, in addition to the pressing, it may also be for necking or ironing the cylindrical workpiece 90.

[0035] In the pressure mold 10 of the above-described embodiment, the recess 15 corresponded to the rectangular bottom wall 91 of the cylindrical workpiece 90 and had an elongated octagonal shape with chamfered corners of the rectangle (see FIG. 4). However, if the straight portion is closer to the opening edge of the recess 15 than the corner portion of the rectangle, the recess 15 does not have to be octagonal. Specifically, as in the counter punch 14A shown in FIG. 7A, a configuration including an oval recess 15A corresponding to the rectangular bottom wall 91 may be employed, or as in the counter punch 14B shown in FIG. 7B, a configuration including an elliptical recess 15B corresponding to the rectangular bottom wall 91 may be employed.

[0036] The bottom wall 91 of the cylindrical workpiece 90 in the above-described embodiment was a rectangle having a long side and a short side, but it may be a square. In that case, a configuration including a circular recess 15 corresponding to the square bottom wall 91 as in the counter punch 14C shown in FIG. 7C may be employed, or a configuration including a regular octagonal recess 15D corresponding to the square bottom wall 91 as in the counter punch 14D shown in FIG. 7D may be employed.

[0037] Further, the bottom wall 91 of the cylindrical workpiece 90 is not limited to a quadrilateral and may be any non-circular shape. For example, it may be a polygon other than a quadrilateral such as a triangle, pentagon, hexagon, etc., or may be an oval, ellipse, or irregular shape. For example, when the bottom wall 91 of the cylindrical workpiece 90 is a regular hexagon, a configuration including a circular recess 15E as in the counter punch 14E shown in FIG. 7E may be employed.

[0038] In the above-described embodiment, the recess 15 was provided in the counter punch 14, but the recess 15 may be provided in the punch 11, or the recess 15 may be provided in both the counter punch 14 and the punch 11.

[0039] <Addendum> Hereinafter, the feature groups extracted from the above-described embodiment will be described while indicating effects and the like as necessary. In the following, for ease of understanding, the corresponding configurations in the above-described embodiment are appropriately shown in parentheses or the like, but these feature groups are not limited to the specific configurations shown in such parentheses or the like.

[0040] [Feature 1] A press die (10) for pressing the bottom wall (91) so that the R shape of the outer edge corner (93) where the outer surface of the non-circular bottom wall (91) of the cylindrical workpiece (90) with a bottom at one end intersects the outer side surface (92S) of the cylindrical workpiece (90) approaches a sharp angular shape, comprising: a punch (11) that is pushed into the inside of the cylindrical workpiece (90); a die (13) having a workpiece receiving hole (12) into which the cylindrical workpiece (90) is pushed by the punch (11); a counter punch (14) that cooperates with the punch (11) within the workpiece receiving hole (12) to press the bottom wall (91) therebetween and cause the material of the bottom wall (91) to flow toward the outer edge corner (93); and a recess (15) formed on at least one of the pressing surfaces of the counter punch (14) and the punch (11) for receiving the excess material that flows due to pressing.

[0041] [Feature 2] The bottom wall (91) is polygonal, the outer edges of the pressing surfaces of the counter punch (14) and the punch (11) are polygonal corresponding to the bottom wall (91), and the recess (15) is formed such that the straight portion (S2) of the outer edge of the counter punch (14) or the punch (11) is closer to the opening edge of the recess (15) than the corner portion (S1) of the polygon. The press die (10) according to Feature 1. [Feature 3] The polygon is a quadrilateral, and the recess (15) has a shape chamfering the corners of the quadrilateral. The press die (10) according to Feature 2.

[0042] [Feature 4] The outer peripheral length of the cylindrical workpiece (90) is 20 [mm] or less. The press die (10) according to any one of Features 1 to 3.

[0043] [Feature 5] The wall thickness - outer peripheral length ratio (R1), which can be obtained by dividing the outer peripheral length (L1) of the cylindrical workpiece (90) by the wall thickness (t) of the side wall, is 0.025 or more. The press die (10) according to any one of Features 1 to 4.

[0044] [Feature 6] The outer edges of the pressure surfaces of the counter punch (14) and the punch (11) are non-circular corresponding to the bottom wall (91), and for the non-circular outer edges of the counter punch (14) or the punch (11), the opening edge of the recess (15) is closer to the place where the radius of curvature of the outer edge shape is larger. The press die (10) according to any one of Features 1 to 5, in which the recess (15) is formed.

[0045] [Feature 7] In a manufacturing method for manufacturing a cylindrical part with both ends open from a cylindrical workpiece (90), in order to make the R shape of the outer edge corner (93) where the outer surface of the non-circular bottom wall (91) of the cylindrical workpiece (90) with a bottom at one end intersects the outer side surface (92S) of the cylindrical workpiece (90) approach a sharp corner shape, the cylindrical workpiece (90) is pushed into the workpiece receiving hole (12) of the die (13) by the punch (11), and the bottom wall (91) is sandwiched between the counter punch (14) and the punch (11) and pressurized in a pressurizing step, and a punching step of punching out the bottom wall (91) from the cylindrical workpiece (90) is performed. In the manufacturing method of the cylindrical part, a recess (15) for receiving the surplus material that flows by pressurization is formed on at least one of the pressure surfaces of the counter punch (14) and the punch (11).

[0046] [Feature 8] The bottom wall (91) is polygonal, the outer edges of the pressure surfaces of the counter punch (14) and the punch (11) are polygonal corresponding to the bottom wall (91), and the recess (15) is formed such that the straight part (S2) is closer to the opening edge of the recess (15) than the corner part (S1) of the polygon among the outer edges of the counter punch (14) or the punch (11). The manufacturing method of the cylindrical part according to Feature 7.

[0047] [Feature 9] The polygon is a quadrilateral, and the recess (15) has a shape chamfering the corners of the quadrilateral. The manufacturing method of the cylindrical part according to Feature 8.

[0048] [Feature 10] The manufacturing method of the cylindrical part according to any one of Features 7 to 9, wherein the outer peripheral length of the cylindrical workpiece (90) is 20 [mm] or less.

[0049] [Feature 11] The wall thickness - outer peripheral length ratio (R1) that can be obtained by excluding the wall thickness (t) of the side wall from the outer peripheral length (L1) of the cylindrical workpiece (90) is 0.025 or more. The manufacturing method of the cylindrical part according to any one of Features 7 to 10.

[0050] [Feature 12] The outer edges of the pressing surfaces of the counter punch (14) and the punch (11) are non - circular corresponding to the bottom wall (91), and for the non - circular outer edge of the counter punch (14) or the punch (11), the recess (15) is formed such that the opening edge of the recess (15) is closer to the place where the radius of curvature of the outer edge shape is larger. The manufacturing method of the cylindrical part according to any one of Features 7 to 11.

[0051] According to Features 1 and 7, when the bottom wall of the cylindrical workpiece is pressed by the punch and the counter punch, among the meat that flows due to the pressing, the surplus meat is received in the recess of the punch or the counter punch. As a result, even if the bottom wall is non - circular, the difference in the supply amount of meat to the outer edge corner of the cylindrical workpiece is suppressed more than before, and the shape quality of the outer edge corner of the cylindrical workpiece becomes better than before. And the bottom wall of the cylindrical workpiece can be punched out suitably, and it becomes possible to manufacture a cylindrical part with open ends having high shape quality from a one - end - bottomed cylindrical workpiece having a non - circular bottom wall.

[0052] Here, when the bottom wall of the cylindrical workpiece is non-circular, the material that is pressurized and flows on the bottom wall tends to flow more easily to the part with a larger radius of curvature of the outer edge shape compared to the part with a smaller radius of curvature among the outer edges of the bottom wall. More specifically, when the bottom wall of the cylindrical workpiece is square, the material flows more easily to the straight part where the radius of curvature is infinite compared to the corner part among the outer edges of the bottom wall. In view of this, in Features 2, 3, 6, 8, 9, and 12, the recesses are formed such that the opening edge of the recess is closer to the place where the radius of curvature of the outer edge shape of the bottom wall is larger. As a result, excessive supply of material to the part where the material flows easily is suppressed, and the material supplied to the part where the material flows difficultly is ensured. Thereby, the difference in the supply amount of the material to the outer corner part of the cylindrical workpiece can be further suppressed compared to the conventional case, the punching of the bottom wall can be performed more suitably, and it becomes possible to manufacture a cylindrical part with both ends open and high shape quality.

[0053] Also, for extremely small cylindrical workpieces with an outer peripheral length of 20 [mm] or less, such as those in Features 4 and 10, the R surface of the outer corner part becomes large compared to the size of the entire cylindrical workpiece, and in conventional press dies and manufacturing methods, defects in shape quality are likely to occur. However, by providing a recess in the counterpunch as in Features 1 and 7, a significant reduction in shape quality defects can be achieved.

[0054] In addition, although specific examples of the technology included in the claims are disclosed in this specification and the drawings, the technology described in the claims is not limited to these specific examples, and also includes those obtained by variously modifying and changing the specific examples, as well as those obtained by extracting a part from the specific examples alone.

Explanation of Reference Numerals

[0055] 10 Press die (pressurizing die) 11, 21, 31 Punch 12, 22, 32 Workpiece receiving hole 13, 23, 33 Die 14, 14A~14E, 24, 34 Counterpunch 15, 15A~15E Recess 90 Cylindrical workpiece 91 Bottom wall 93 Outer edge corner 95 Cylindrical part L1 Outer perimeter R1 Wall thickness to outer perimeter ratio S1 Corner part S2 Straight part t Wall thickness

Claims

1. A press die for pressing the bottom wall so that the R shape of the outer edge corner where the outer surface of the non-circular bottom wall of the cylindrical workpiece with a bottom at one end intersects the outer side surface of the cylindrical workpiece approaches a sharp corner shape, a punch that is pushed into the inside of the cylindrical workpiece, a die having a workpiece receiving hole into which the cylindrical workpiece is pushed by the punch, a counterpunch that cooperates with the punch in the workpiece receiving hole to press the bottom wall while sandwiching it, and causes the material of the bottom wall to flow toward the outer edge corner side, recesses formed on at least one of the pressing surfaces of the counterpunch and the punch for receiving the excess material that flows due to pressing, and a press die comprising the same.

2. The bottom wall is polygonal, the outer edges of the pressing surfaces of the counterpunch and the punch are polygonal corresponding to the bottom wall, The press die according to claim 1, wherein the recess is formed such that the straight portion of the outer edge of the counterpunch or the punch is closer to the opening edge of the recess than the corner portion of the polygon.

3. The polygon is a quadrilateral, The press die according to claim 2, wherein the recess has a shape chamfering the corners of the quadrilateral.

4. The press die according to claim 1, wherein the outer peripheral length of the cylindrical workpiece is 20 [mm] or less.

5. The press die according to claim 1, wherein the wall thickness / outer peripheral length ratio, which can be obtained by excluding the wall thickness of the side wall from the outer peripheral length of the cylindrical workpiece, is 0.025 or more.

6. The outer edges of the pressing surfaces of the counterpunch and the punch are non-circular corresponding to the bottom wall, The press die according to claim 1, wherein the recess is formed such that the opening edge of the recess is closer to a location where the radius of curvature of the outer edge shape is larger with respect to the non-circular outer edge of the counter punch or the punch.

7. In a manufacturing method for manufacturing a cylindrical part with both ends open from the cylindrical workpiece, in order to make the R shape of the outer edge corner where the outer surface of the non-circular bottom wall of the cylindrical workpiece with a bottom at one end intersects the outer surface of the cylindrical workpiece approach a sharp corner shape, the cylindrical workpiece is pushed into the workpiece receiving hole of the die by a punch, and a pressing step in which the bottom wall is sandwiched between the counter punch and the punch and pressurized, and a punching step in which the bottom wall is punched out from the cylindrical workpiece are performed. A method for manufacturing a cylindrical part, wherein at least one of the pressing surfaces of the counter punch and the punch is formed with a recess for receiving surplus material that flows by pressing.

8. The bottom wall is polygonal, The outer edges of the pressing surfaces of the counter punch and the punch are polygonal corresponding to the bottom wall, The method for manufacturing a cylindrical part according to claim 7, wherein the recess is formed such that the straight part of the outer edge of the counter punch or the punch is closer to the opening edge of the recess than the corner part of the polygon.

9. The polygon is a quadrilateral, The method for manufacturing a cylindrical part according to claim 8, wherein the recess has a shape chamfering the corner of the quadrilateral.

10. The method for manufacturing a cylindrical part according to claim 7, wherein the outer peripheral length of the cylindrical workpiece is 20 [mm] or less.

11. The method for manufacturing a cylindrical part according to claim 7, wherein the wall thickness / outer peripheral length ratio, which can be obtained by excluding the wall thickness of the side wall from the outer peripheral length of the cylindrical workpiece, is 0.025 or more.

12. The outer edges of the pressing surfaces of the counter punch and the punch are non-circular corresponding to the bottom wall, The method for manufacturing a cylindrical component according to claim 7, wherein the concave portion is formed such that the opening edge of the concave portion is closer to a location where the radius of curvature of the outer edge shape is larger with respect to the non-circular outer edge of the counter punch or the punch.

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