JP2006272458A - Shaft forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shaft forming method, more concretely, a method for forming a hollow shaft projecting from a flat part integrally with the flat part by subjecting a metal plate to forging where a stepped shaft is formed on a metal plate by forging. <P>SOLUTION: The method comprises: a preparation stage where a metal plate 10 is placed on a straight die 110 in which a hole 116 is formed; a first forging stage where a knockout 120 provided at the inside of the hole 116 in the straight die 110 is pushed into the hole 116 of the metal plate 10 by a straight punch 140 in a state of being confronted with the tip of the punch, and back pressure is applied to the metal plate 10, so as to roll the metal plate 10 to the side face of a shaft; a shaft inserting stage where an already formed first step shaft 14 is inserted into a stepped die 210 at which a small-diameter part is formed on the depth of the hole 216; and a stepping forging stage where, as the metal plate 10 inserted into the stepped hole 216 is further pushed into the small-diameter part by a stepped punch 240 having an outside diameter same as the inside diameter of the second step shaft 15 to be formed, in a state where the knockout 220 provided at the inside of the hole 216 is confronted with the tip of the stepped punch 240, back pressure is applied to the metal plate 10 by the knockout 220, thus the metal plate pushed against the tip of the stepped punch is rolled to the side face of the shaft. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a shaft forming method. More specifically, the present invention relates to a method for forming a hollow shaft that protrudes from a flat portion integrally with the flat portion by forging a metal plate.

The following Patent Document 1 describes a method of manufacturing a hollow shaft by pressing a metal plate. According to the description of Patent Document 1, firstly, a first step of half-punching a metal plate by press working, and a second step of pushing a punch into the half-punched region while pushing the half-punched region back to the half-punched region. A hollow shaft is formed in the metal plate by the manufacturing method including:
Japanese Patent No. 3475551

  However, since the method described in Patent Document 1 requires the first step of half-punching and the second step of rearward extrusion, the number of steps increases when manufacturing a multistage shaft, and the manufacturing cost increases. was there. In this method, the material forming the shaft is limited to the amount existing in the region to be processed at the time of processing. For this reason, if it is going to secure thickness in order to maintain the intensity | strength in the axial part of a product, the height of the axis | shaft which can be formed will be restrict | limited.

  In order to solve the above-described problem, the first embodiment of the present invention is a shaft forming method in which a metal plate is forged to form a multi-stage hollow shaft that protrudes from the metal plate and has a smaller diameter toward the tip. A preparation step of placing a metal plate to be processed on the upper surface of the hole of a die in which a hole having the same inner diameter as the base shaft outer diameter is formed, and a punch having the same outer diameter as the shaft inner diameter While pushing the metal plate supported on the upper surface of the hole into the hole, with the knockout provided inside the die hole facing the tip of the punch, the back pressure is applied to the metal plate by knockout. The initial forging process of rolling the metal plate pushed by the tip of the punch onto the side surface of the shaft, and the outer diameter of the shaft formed just before the shaft, and the shaft to be formed in the back Stepped with the same inner diameter as the outer diameter The step insertion die of the stepped die in which the hole is formed has a shaft insertion step of inserting the shaft already formed in the metal plate to be processed into the stepped hole, and an outer diameter equal to the inner diameter of the shaft formed immediately before. In addition, with a stepped punch having the same outer diameter as the inner diameter of the shaft to be formed at the tip, a metal plate inserted into the stepped hole is further pushed into the stepped hole and provided in advance in the stepped hole. Stepping the metal plate pushed by the tip of the stepped punch to the side of the shaft by applying back pressure to the metal plate with knockout with the knockout being opposed to the tip of the stepped punch A shaft forming method including a forging process is provided. This makes it possible to form a multi-stage shaft having a height that cannot be formed by only one forging process by repeating the stepped forging process a required number of times. In addition, since a single-stage shaft can be formed in a single process, the number of man-hours does not increase significantly even if a multi-stage shaft is formed.

  Further, according to one of the embodiments, the shaft forming method further includes a material insertion step of inserting the workpiece into the already formed shaft after the shaft insertion step and before the stepped forging step. In the forging process, there is provided a shaft forming method for rolling a metal plate and a workpiece on the side surface of the shaft. Thereby, since it can process while supplementing a material to a to-be-processed area | region, even if it forms a shaft in multiple steps, the intensity | strength of a shaft does not fall by the reduction in thickness.

  Further, according to one of the other embodiments, in the above-described shaft forming method, the workpiece is formed by punching out, and in the material insertion step, the shaft is formed by inserting the sag side of the workpiece into the tip end side of the shaft. A method is provided. As a result, the workpiece is brought into close contact with the inside of the tip of the shaft formed in the preceding forging process, and defects are less likely to occur in the stepped forging process.

  According to another embodiment, in the shaft forming method, in the stepped forging step, the volume of the space defined by the stepped die, the stepped punch, and the knockout is a metal plate and the workpiece. A shaft forming method is provided in which the volume of the workpiece is adjusted so as to be equal to the sum of the volumes of the workpiece regions. As a result, the reduction in wall thickness is compensated by the work material, and at the same time, the product can be manufactured with a minimum of necessary materials.

  Further, according to one of the other embodiments, in the shaft forming method, the length in the pushing direction of the same outer diameter as the shaft inner diameter to be formed in the stepped punch is equal to the shaft outer diameter to be formed from the stepped die. A method of forming an axis shorter than the length of the same inner diameter in the pushing direction is provided. Thereby, the strength reduction at the boundary between the shaft formed in the initial forging process and the shaft formed in the stepped forging process or between the shafts formed by the stepped forging process can be prevented.

  Further, according to one of the other embodiments, in the shaft forming method, a notch step of forming three or more linear notches formed radially from the center of the top surface of the shaft using a punch and a die, A plurality of sector-shaped section push-bending defined by cutting using a burring punch and a burring die to stand upright in the axial direction of the section, and a vertical process using a bending punch and a bending die. Bending the tip of the section radially with respect to the axis, and bending the section to form an upright part standing upright with respect to the top surface of the section and a horizontal part extending radially from the tip of the upright part. Can be provided. Thereby, the structure for mounting | wearing with another member further can be formed in the front-end | tip of the axis | shaft formed in the metal plate. Therefore, the member that prevents the member attached to the shaft from falling off can be directly attached to the shaft.

  In the shaft forming method, it is preferable that the tip of the horizontal portion is formed so as to be positioned inside a region defined by extending the side surface of the shaft in the axial direction. Thereby, when the shaft is inserted through the member to be mounted, the horizontal portion does not interfere with the member.

  Further, in the shaft forming method, the bending step further includes an intermediate bending step of bending the tip portion of the upstanding section to an intermediate angle of less than 90 °, and a final bending step of bending the tip portion to 90 ° to obtain a horizontal portion. Can be provided. Thereby, the processing amount in a single process is suppressed, and the limited material supplied from the top surface of the shaft can be bent without breaking. Accordingly, the horizontal portion can be reliably formed.

  Further, in the bending step of the shaft forming method, a part of the bending die comes into contact with the upright portion from the side to prevent deformation. As a result, the upright portion of the section is prevented from being irregularly deformed, and a substantially cylindrical upright portion is formed.

  Further, in the bending step of the shaft forming method, it is preferable to prevent deformation of the top surface by bringing a bending receiver into contact with the back surface of the top surface from the inside of the shaft. As a result, the top surface of the shaft is prevented from being deformed in the bending step, and an upright portion that can be smoothly mounted with other members is formed.

  Further, in the shaft forming method, the distance between the horizontal portion and the top surface is substantially equal to the thickness of the C-ring attached to the upright portion. As a result, the C-ring for preventing the member attached to the shaft from coming off can be attached without a gap. Therefore, there is no backlash in the member mounted on the shaft and its operation.

  Further, as a second embodiment of the present invention, a preparation step of placing a metal plate to be processed on the upper surface of a hole of a die in which a hole having the same inner diameter as the outer diameter of the base of the shaft is formed; While pushing the metal plate supported on the upper surface of the hole with the punch having the same outer diameter as the inner diameter of the shaft into the hole, the knockout provided in advance inside the hole of the die is opposed to the tip of the punch. By applying back pressure to the metal plate by knockout, the initial forging step of rolling the metal plate pushed by the tip of the punch onto the side surface of the shaft and the same outer diameter as the outer diameter of the shaft formed immediately before Insert the shaft already formed in the metal plate to be processed into the stepped hole of the stepped die that has a stepped hole with the same inner diameter as the outer diameter of the shaft to be formed in the back. Shaft insertion process to be performed and the shaft formed immediately before With the stepped punch having the same outer diameter as the inner diameter of the shaft to be formed at the tip, and further pushing the metal plate inserted into the stepped hole into the stepped hole, With the knockout provided in the inside of the tapped hole facing the tip of the stepped punch, the metal plate pushed by the tip of the stepped punch is pivoted by applying back pressure to the metal plate by knockout. A shaft product that is formed by a forging process including a stepped forging step that rolls to the side surface of the metal plate and that is formed by forging the metal plate and has a multi-stage hollow shaft that protrudes from the metal plate and has a smaller diameter toward the tip. Is provided. As a result, a lightweight shaft product in which a multistage shaft is integrally provided on a metal plate is supplied at a low price.

  Further, as one embodiment, the shaft product includes a punching process using a punch and a die to form three or more linear cuts formed radially from the center of the top surface of the shaft, and a burring punch and a burring die. A plurality of sector-shaped sections formed by cutting and bending, and a section that stands upright in the height direction of the shaft, and a section that stands upright in the axial direction using a bending punch and a bending die A bending step of bending the tip of the shaft radially with respect to the shaft, an upright portion standing upright with respect to the top surface of the shaft, and a horizontal portion extending radially from the tip of the upright portion; A shaft product further comprising Accordingly, it is possible to prevent a component attached to the shaft from falling off by attaching a fastener or the like.

  The above summary of the invention does not enumerate all the necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

  Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the scope of claims, and all combinations of features described in the embodiments are included. It is not necessarily essential for the solution of the invention.

  FIG. 1 is a diagram illustrating the structure of an initial forging device 100 used in the initial forging process in a state immediately before the initial forging process is performed. As shown in the figure, the initial forging device 100 includes a straight die 110 having a hole 116 having a constant diameter, a knockout 120 accommodated in the hole 116, and a pressing member 150 disposed above the straight die 110. And a straight punch 140 having a constant diameter penetrating the pressing member 150.

  The knockout 120 is supported by the biasing member 130 from below inside the hole 116. In the initial state, the top surface of the knockout 120 is slightly lower than the upper surface of the straight die 110, specifically, a position that is approximately a height corresponding to 1/3 of the thickness of the metal plate 10 to be processed. Waiting.

  On the other hand, the pressing member 150 has a through hole having the same diameter as the hole 116 of the straight die 110 and presses the metal plate 10 placed on the upper surface of the straight die 110 from above around the hole 116 of the straight die 110. Therefore, only the area of the metal plate 10 located above the hole 116 is deformed by processing. Further, the straight punch 140 is inserted through the through hole of the pressing member 150 and can press down the metal plate 10 from above.

  Here, the inner diameter of the hole 116 of the straight die 110 is the same as the outer diameter of the shaft to be formed. On the other hand, the outer diameter of the straight punch 140 is the same as the inner diameter of the shaft to be formed.

  In addition, the metal plate 10 used as a material in this embodiment is an electrogalvanized cold-rolled steel plate (SECC) having a thickness of 1.2 mm. The straight die 110, the knockout 120, and the straight punch 140 are all made of cemented carbide, and the holding member 150 is made of alloy tool steel (SKD). The outer diameter of the straight punch 140 was 7.1 mm, and the outer diameter of the knockout 120 was 7.4 mm. In the initial state, the biasing member 130 having such a length as to wait when the upper end of the knockout 120 is lowered by 0.4 mm from the upper surface of the straight die 110 is selected.

  Furthermore, the pressing surface 144 which is the lower end surface of the straight punch 140 is a dome-shaped shape that rises gently from the periphery toward the center, and is a curved surface having a curvature R300. The shoulder 142 of the pressing surface is also rounded with a curvature R0.5 over the entire circumference. Further, the back pressure surface 124 which is the upper end surface of the knockout 120 has an inverted dome shape complementary to the dome shape of the pressure surface 144. Further, the opening shoulder 112 of the hole 116 of the straight die 110 is also rounded with a curvature R0.2.

  With these shapes, extreme stress concentration does not occur in a specific part of the metal plate 10 to be processed, and smooth processing can be performed. Thereby, the durability of the initial forging device 100 is also improved.

  FIG. 2 is a diagram illustrating a state in which the straight punch 140 is lowered in the initial forging device 100 illustrated in FIG. 1. In addition, the same referential mark is attached | subjected to the same component as FIG. 1, and the overlapping description is abbreviate | omitted.

  As shown in the figure, the pressing surface 144 at the lower end of the straight punch 140 pushes the metal plate 10 into the hole 116 of the straight die 110. At this time, the metal plate 10 is initially pushed and deformed only by the straight punch 140, but eventually the back surface comes into contact with the back pressure surface 124 of the knockout 120. The knockout 120 is squeezed together with the metal plate 10 by the straight punch 140 to compress the urging member 130. For this reason, according to the spring constant of the urging member 130, the knockout 120 applies a back pressure to the metal plate 10 from below.

  In this way, the metal plate 10 sandwiched between the pressure surface 144 of the straight punch 140 and the back pressure surface 124 of the knockout 120 is rolled and pushed into the gap between the inner surface of the straight die 110 and the straight punch 140. Note that the metal plate 10 is not deformed in an area where the upper surface of the straight punch 140 is pressed by the pressing member 150. Further, the volume of the metal material forming the axis in the space defined by the inner surface of the straight die 110, the circumferential surface of the straight punch 140, and the back pressure surface 124 of the knockout 120 is an area where the straight punch 140 is projected perpendicularly to the metal plate 10. It is substantially equal to the volume of the existing metal plate 10.

  FIG. 3 is a view showing the first stage shaft 14 formed on the metal plate 10 through the initial forging process in its cross-sectional shape. As shown in the figure, the first stage shaft 14 is a hollow shaft formed integrally and continuously from the flat portion 12 of the metal plate 10. The front end surface 16 of the first stage shaft 14 is also formed continuously and integrally with the side surface of the first stage shaft 14.

In the present embodiment, the outer diameter of the first stage shaft 14 is constant at about 7.4 mm. The height of the first-stage shaft 14 was about 8mm in length _{L 1} from the flat portion 12 of the metal plate 10 to the distal end surface 16. Further, the thickness of the first stage shaft 14 was about 0.15 mm at the side surface portion and about 0.35 mm at the front end surface 16, and was substantially uniform.

  FIG. 4 is a cross-sectional view showing a material insertion process performed after the initial forging process together with a partial structure of a stepped forging apparatus 200 used in a stepped forging process described later. As shown in the figure, the stepped forging device 200 includes a stepped die 210 having a hole 216, a knockout 220 disposed inside the hole 216, and a pressing member 150 disposed above the stepped die 210. ing. The pressing member 150 used here is the same member as that used in the first forging device 100 shown in FIGS. 1 and 2, and penetrates equal to the inner diameter of the first stage shaft 14 formed in the metal plate 10. Has a hole.

  On the other hand, the hole 216 formed in the stepped die 210 has an inner diameter equal to that of the hole 116 of the straight die 110 in the vicinity of the upper end opening, while the stepped portion 218 is located at the same depth as the height of the first stage shaft 14. The inner diameter is smaller in the deeper range. Therefore, the outer diameter of the knockout 220 accommodated therein is also reduced. The knockout 220 is supported by the urging member 230 from below as in the first forging device 100.

  Such a stepped die 210 is loaded with the metal plate 10 on which the first stage shaft 14 is formed in the first forging process. As described above, the depth from the top surface of the stepped die 210 to the step portion 218 is equal to the height of the first stage shaft 14, and the inner diameter of the hole 216 from the opening to the step portion 218 is equal to the inner diameter of the hole 116 of the straight die 110. . Therefore, the first stage shaft 14 enters the inside of the hole 216 of the stepped die 210, and the flat portion 12 of the metal plate 10 is in close contact with the upper surface of the stepped die 210. Further, the closely contacted flat portion 12 is pressed from above by the pressing member 150.

  In the material insertion step, the workpiece 20 is inserted inside the tip surface 16 of the first stage shaft 14. The workpiece 20 is a disk-shaped material having substantially the same diameter as the inner diameter of the first stage shaft 14, and is placed horizontally on the inner surface of the distal end surface 16.

  In this embodiment, the inner diameter of the small diameter portion of the hole 216 of the stepped die 210 is 3 mm. Further, the biasing member 230 having such a length as to wait when the upper end of the knockout 220 is lowered by 0.4 mm from the stepped portion 218 is selected.

  Further, the back pressure surface 124 that is the upper end surface of the knockout 220 has a reverse dome shape complementary to the dome shape of the pressure surface at the tip of the stepped punch, which will be described later. In addition, the opening shoulder 212 of the hole 216 of the stepped die 210 was rounded with a curvature R0.2, and the small diameter opening shoulder was rounded with a curvature R0.2.

  FIG. 5 is a view showing the shape of the workpiece 20 inserted into the first stage shaft 14 in the material insertion step shown in FIG. As shown in the figure, the workpiece 20 is a disk-shaped member made by punching from the same material as the metal plate 10.

  Here, as is well known to those skilled in the art, the sagging surface 22 and the burr surface 24 are front and back in a member obtained by punching. That is, on the surface that is in contact with the die at the time of punching, a sagging surface 22 having a gentle peripheral edge is formed by plastic deformation of the material. On the other hand, a burr surface 24 having a rough peripheral edge due to brittle fracture of the material is formed on the surface that is in contact with the punch during punching.

  Here, according to a preferred embodiment, when the workpiece 20 is inserted into the first stage shaft 14 in the material insertion step shown in FIG. 4, the sagging surface having a gentle peripheral edge is the bottom surface of the first stage shaft 14. It is preferable to make the direction facing the surface. Thereby, when the workpiece 20 is rolled in a stepped forging process to be described later, the adhesion between the inner surface of the first stage shaft 14 and the workpiece 20 is improved, and defects are less likely to occur.

  FIG. 6 is a view showing a state in which a stepped punch 240 is mounted on the stepped forging device 200 shown in FIG. In addition, the same referential mark is attached | subjected to the same component as FIG. 4, and the overlapping description is abbreviate | omitted.

  As shown in the figure, the stepped punch 240 is integrally provided with a large-diameter portion 241 having the same outer diameter as that of the straight punch 140 and a smaller-diameter portion 243 having a smaller diameter at the tip (lower end) thereof. The surface of the large diameter portion 241 and the surface of the small diameter portion 243 are continuous via the step portion 248.

  In this embodiment, in the stepped punch 240, the outer diameter of the small diameter portion 243 is 2.7 mm, which is equal to the inner diameter of the second step shaft to be formed. The pressurizing surface 244 at the lower end of the stepped punch 240 has a dome shape that gently rises from the periphery toward the center with a curvature R20, and the shoulder portion 242 of the pressurizing surface 244 also has a curvature R0. 5 is rounded.

  FIG. 7 is a view showing a state in which the stepped punch 240 is lowered in the stepped forging device 200 shown in FIGS. 4 and 6. In addition, the same referential mark is attached | subjected to the same component as FIG. 4 and FIG. 6, and the overlapping description is abbreviate | omitted.

  As shown in the figure, when the stepped punch 240 is lowered, the small diameter portion 243 is lowered without touching the inside of the side surface of the first stage shaft 14, and eventually comes into contact with the tip surface of the first stage shaft 14 and is reduced. At this time, since the tip edge portion of the first stage shaft 14 is locked by the step portion 218, the pressure surface 244 at the tip of the stepped punch 240 simultaneously lowers the tip surface of the first stage shaft 14 and the workpiece 20 to form a step. It pushes into the small diameter part of the hole 216 of the attached die 210. At the same time, since the knockout 220 applies back pressure to the metal plate 10 from below, the metal plate 10 and the workpiece 20 sandwiched between the pressure surface 244 at the tip of the stepped punch 240 and the back pressure surface 224 of the knockout 220 are rolled, It is pushed out into the gap between the inner surface of the small diameter portion of the stepped die 210 and the small diameter portion 243 of the stepped punch 240.

  FIG. 8 is a cross-sectional view showing a cross-sectional shape of the metal plate 10 on which a stepped shaft is formed by the stepped forging process. As shown in the figure, after the stepped forging process, the metal plate 10 becomes a product integrally including a large-diameter first stage shaft 14 and a small-diameter second stage shaft 15. Here, as shown in the drawing, the thickness of the inner surface of the second step shaft 15 is supplemented by the workpiece 20 pushed out to the side surface by the stepped punch 240 and the knockout 220. Therefore, the second stage shaft 15 also has a strength comparable to the first stage shaft 14.

In the present embodiment, the height of the second stepped shaft 15 was 4mm is represented by a length L ₁ the length L ₂ by subtracting the first-stage shaft 14 from the length of the flat portion 12 to the tip. The outer diameter was 3 mm. Furthermore, on the front end surface 16 of the second stage shaft 15, the thickness of the metal plate 10 was 0.1 mm, and the thickness of the workpiece 20 was 0.3 mm. Furthermore, on the side surface of the second stage shaft 15, the thickness of the metal plate 10 was 0.05 mm, and the thickness of the workpiece 20 was 0.1 mm.

  Note that the volume of the metal plate 10 and the workpiece 20 processed into the second step shaft 15 by the small diameter portion 243 of the stepped punch 240 is such that the pressure surface 244 of the stepped punch 240 is inside the tip surface of the first step shaft 14. It is equal to the volume of the metal plate 10 and the workpiece 20 existing in the region projected perpendicularly to. This volume is defined by the inner surface of the small diameter portion of the stepped die 210, the outer surface of the small diameter portion 243 of the stepped punch 240, and the upper surface of the back pressure surface 224 of the knockout 220 with the stepped punch 240 being squeezed. It is equal to the volume of the created space. Therefore, by appropriately selecting the volume (mainly thickness) of the workpiece 20 to be inserted in the material insertion step, the stepped forging step can be carried out in an amount without excess or deficiency.

  8 shows that the thickness of the metal plate 10 is increased at the stepped portion 18. As can be seen from FIG. 7, the distance in the height direction between the stepped portion 248 of the lowered stepped punch 240 and the stepped portion 218 of the stepped die 210 is the same as that of the stepped punch 240 and the stepped die 210. It is a cross-sectional shape formed to be wider than the horizontal interval. Thereby, the strength of the stepped portion 18 that is the boundary between the first stage shaft 14 and the second stage shaft 15 is increased.

  FIG. 9 is a perspective view showing the shape of a stepped shaft product 99 obtained by processing the metal plate 10 by the stepped forging process. As shown in the figure, a first stage shaft 14 and a second stage shaft 15 coupled to the first stage shaft 14 via a step portion 18 are integrally formed so as to hang down from the original metal plate 10. . The first stage shaft 14 and the second stage shaft 15 are both cylindrical with smooth surfaces. Therefore, by using the relatively thin metal plate 10, in addition to simple bending and drilling, it is possible to form a shaft that can itself support other members.

  In this embodiment, for convenience of explanation, the metal plate 10 is drawn as being slightly wider than the first stage shaft 14, but by forming such a shaft on a blank of the larger metal plate 10, various kinds of plates can be obtained. A metal product having a function can be realized. Moreover, although the said Example demonstrated the case where the two-stage axis | shaft of the first stage axis | shaft 14 and the 2nd stage axis | shaft 15 was formed, a multistage axis | shaft with many stages can be formed by repeating a stepped forging process. In this case, the diameters of the stepped die 210 and the stepped punch 240 to be used are gradually reduced as the number of steps is increased.

  As is apparent from the above description, according to the present invention, a multistage shaft can be formed by repeating the forging process once per stage. Therefore, for example, on galvanized steel sheets, aluminum plated steel sheets, SUS430, SUS304, aluminum (A1050) or aluminum alloy (A5052, A5083, A6061, etc.) used as structural materials in home appliances, OA products, office equipment, etc. A desired axis can be formed.

  Furthermore, according to another embodiment, a flange that can attach a retaining member to a member attached to the second stage shaft 15 is formed at the tip of the second stage shaft 15 of the shaft product 99 formed as described above. it can. In the following description, members common to those in FIGS. 1 to 9 are denoted by common reference numerals, and redundant description is omitted.

  FIG. 10 is a diagram showing the shape of a punching die 810 used in the next step. As shown in the drawing, the punching die 810 is a solid metal lump 812 having a cubic shape as a whole, and has a through-hole 814 penetrating from the top surface to the bottom surface at the center thereof. The horizontal cross-sectional shape of the through hole 814 is a cross shape.

  On the other hand, FIG. 11 is a perspective view showing the shape of a punching punch 820 used in combination with the punching die 810 shown in FIG. The punching punch 820 includes a square columnar pressing portion 822 and a punching portion 824 having a cross-sectional shape complementary to the through hole 814 of the punching die 810. Here, the horizontal cross-sectional shape of the punched portion 824 has substantially the same shape and size as the through hole 814, leaving a gap suitable for punching. Therefore, when the punched portion 824 is inserted into the through hole 814, there is a gap suitable for punching between the punched portion 824 and the through hole 814. Further, the edge portion 826 of the end face of the punched portion 824 is finished with a sharp corner.

  When the punching die 810 and the punching punch 820 as described above are mounted on the molding apparatus, they are positioned relative to each other so that the punching portion 824 of the punching punch 820 smoothly penetrates into the through hole 814 of the punching die 810. . The shaft product 99 shown in FIG. 9 is set so that the top surface of the second stage shaft 15 contacts the surface of the punching die 810 mounted in this way. At this time, the shaft product 99 is positioned so that the center of the top surface of the second stage shaft 15 and the center of the through hole 814 of the punching die 810 coincide. Further, when the punching punch 820 is lowered in this state, a part of the top surface of the second stage shaft 15 is cut out in the same shape as the cross section of the punching portion 824 of the punching punch 820.

  FIG. 12 is a perspective view showing the shape of the shaft product 99 in which the notch 32 is formed by the punching process as described above. As shown in the figure, the top surface of the second stage shaft 15 is formed with notches 32 radially from the center thereof in the radial direction. In other words, four sector-shaped (fan-shaped) sections 34 are cut out on the top surface.

  FIG. 13 is a perspective view showing the shape of the burring die 310 used in the next startup process. As shown in the drawing, the burring die 310 is formed of a cubic metal lump 312 and has a through hole 314 having a cylindrical inner surface at the center thereof. The inner diameter of the through hole 314 is substantially equal to the outer diameter of the sector-shaped piece 14 formed at the tip of the second stage shaft 15.

  FIG. 14 is a perspective view showing the shape of a burring punch 320 used in combination with the burring die 310 shown in FIG. As shown in the figure, the burring punch 320 includes a cylindrical straight barrel portion 322 having a constant diameter, and a bullet-shaped tip portion 324 formed at one end of the straight barrel portion 322. Here, the outer diameter of the straight body portion 322 is substantially equal to the inner diameter of the sector-shaped section 14 formed at the tip of the second stage shaft 15.

  FIG. 15 is a cross-sectional view showing a state in which the shaft product 99 is processed by the forming apparatus 910 equipped with the burring die 310 and the burring punch 320 as described above. As shown in the figure, the second stage shaft 15 is set so that its top surface comes into contact with the upper surface of the burring die 310. The center of the top surface of the second stage shaft 15 and the center of the through hole 314 of the burring die 310 are set so as to coincide with each other. In this state, when the burring punch 320 is penetrated from the inside of the second stage shaft 15 toward the inside of the through hole 314, each piece 34 formed on the top surface in the previous step is inside the through hole 314. The second stage shaft 15 is bent in the height direction.

  FIG. 16 is a perspective view showing the shape of the shaft product 99 processed as described above. As shown in the figure, each of the sector-shaped segments 34 formed on the top surface of the second stage shaft 15 rises in the height direction of the second stage shaft 15 from the top surface. However, as can be seen from FIG. 15, a shoulder portion 36 is formed in the peripheral portion of the top surface, leaving a region having a certain width without being deformed.

  FIG. 17 is a perspective view showing the shape of the pre-bending die 410 used in the next step for the shaft product 99. As shown in the figure, the preliminary bending die 410 is formed by a pair of divided dies 411 and 412 each having a semicircular machining surface 418. When these divided dies 411 and 412 are joined while facing each other at the side end surface having the processing surface 418, a bending surface 418 inclined at 45 ° with respect to the upper surface and a small angle formed perpendicular to the upper surface are formed. A circular processed portion including the support surface 416 is formed. The inner diameter of the processed portion is substantially equal to the outer diameter of the plurality of pieces 34 rising on the top surface of the shaft product 99 shown in FIG. Further, below the processing surface 418, large support surfaces 414 and 415 having shapes complementary to the side surfaces of the first stage shaft 14 and the second stage shaft 15 of the shaft product 99 are formed.

  FIG. 18 is a perspective view showing the shape of the preliminary bending punch 420 used in combination with the preliminary bending die 410. As shown in the figure, the pre-bending punch 420 has a circular horizontal sectional shape as a whole, and has a cylindrical straight body portion 422 and an intrusion portion 424 having a smaller diameter than the straight body portion 422 formed at the tip thereof. And. On the end surface of the straight body portion 422 where the penetration portion 424 is formed, a step corresponding to the difference in diameter between the two is formed. This step is inclined by 45 ° with respect to the side surface of the straight body portion 422, and forms a processed surface 423 that contributes to bending processing described later. On the other hand, an inclined surface is also formed at the peripheral edge of the distal end of the penetration portion 424, which is a chamfered portion 425 formed so that the penetration portion 424 smoothly penetrates into the second stage shaft 15. Further, the penetration portion 424 has an outer diameter that can penetrate the inside of the section 34 rising from the top surface of the shaft product 99.

  FIG. 19 shows a preliminary bending receiver for preventing unnecessary deformation of the second stage shaft 15 when the preliminary bending process is performed using the preliminary bending die 410 and the preliminary bending punch 420 shown in FIGS. It is a perspective view which shows the shape of 430. FIG. As shown in the figure, the preliminary bending receiver 430 includes a cylindrical straight body 434 protruding from a cubic metal lump 432. Further, the front end surface 438 of the straight body portion 434 is horizontal, and a recessed portion 439 having an inner diameter complementary to the outer diameter of the penetration portion 424 of the preliminary bending punch 420 shown in FIG. Further, a chamfered portion 436 is formed at the peripheral edge of the upper end of the straight body portion 434 so that it can be smoothly inserted into the second stage shaft 15 as will be described later. Therefore, only the annular region sandwiched between the chamfered portion 436 and the recessed portion 439 forms a horizontal plane on the front end surface 438 of the straight body portion 434.

  20 is a cross-sectional view for explaining the operation of the molding apparatus 920 equipped with the preliminary bending die 410, the preliminary bending punch 420, and the preliminary bending receiver 430 shown in FIGS. As shown in the figure, the shaft product 99 is set in the molding device 920 with the second stage shaft 15 facing downward and the preliminary bending receiver 430 inserted therein. At this time, the straight body portion 434 of the preliminary bending receiver 430 is substantially in close contact with the inner surface of the second stage shaft 15. Further, the front end surface 438 of the straight body portion 434 is in contact with the back surface of the shoulder portion 36 of the second stage shaft 15. Further, the metal plate 10 portion of the shaft product 99 is also in close contact with the surface of the metal block 432 of the preliminary bending receiver 430. Therefore, the shaft product 99 will not be deformed toward the inside even when subjected to a pre-bending process as will be described later.

  Further, in the forming apparatus 920, the divided dies 411 and 412 that form the preliminary bending die 410 are disposed on the side of the second stage shaft 15 so as to face each other. Further, the pre-bending punch 420 is disposed from below the second stage shaft 15 so as to face the half-tsutsu support 430. At this time, the recessed portion 439 of the preliminary bending receiver 430 and the penetration portion 424 of the preliminary bending punch 420 are arranged on the same axis.

  FIG. 21 shows the molding apparatus 920 shown in FIG. 20 in which a pair of split dies 411 and 412 are brought close to each other and brought into contact with the second stage shaft 15 from the side. Indicates the contact state. At this time, the large support surfaces 414 and 415 of the divided dies 411 and 412 are in close contact with the side surfaces of the first stage shaft 14 and the second stage shaft 15. The small support surfaces 416 of the split dies 411 and 412 are in close contact with the vicinity of the root of the section 34 of the second stage shaft 15. However, at this stage, the shaft product 99 has not undergone substantial deformation and has not yet been subjected to preliminary bending.

  FIG. 22 is a cross-sectional view showing a state in which the pre-bending process is performed by raising the pre-bending punch 420 in the molding apparatus 920 shown in FIGS. 20 and 21. As shown in the figure, in the section 34 of the second stage shaft 15, the vicinity of the base is sandwiched between the small support surface 416 of the preliminary bending die 410 and the side surface of the penetration portion 424 of the preliminary bending punch 420, and the second stage shaft. It is held upright with respect to 15 top surfaces. On the other hand, the vicinity of the tip of the section 34 is pressed against the processing surface 418 of the preliminary bending die 410 by the processing surface 423 of the preliminary bending punch 420 and forms an angle of 45 ° with respect to the top surface of the second stage shaft 15. It is bent toward the outside of the second stage shaft 15 until it is made. As described above, the portion other than the vicinity of the tip of the section 34 of the shaft product 99 is sandwiched between the preliminary bending receiver 430 and the preliminary bending die 410. Therefore, even if an external force is applied by the preliminary bending process, the portion other than the tip of the section 34 is not deformed at all.

  FIG. 23 is a perspective view showing the outer shape of the shaft product 99 formed by the pre-bending process as described above. As shown in the figure, each of the segments 34 stands upright in the height direction of the second stage shaft 15 at the wide portion 35 near the base to the second stage shaft 15. On the other hand, the distal end portion 37 of the section 34 is expanded in a direction away from the center of the second stage shaft 15.

  FIG. 24 is a perspective view showing the shape of the finish bending die 510 used in the next step for the shaft product 99. As shown in the figure, the finish bending die 510 is formed by a pair of split dies 511 and 512 each having a semi-supporting small support surface 516. When these divided dies 511 and 512 are coupled with the side end surfaces having the small support surfaces 516 facing each other, a partial region of the upper surface adjacent to the small support surfaces 516 becomes the bending surface 518. The inner diameter of the small support surface 516 is substantially equal to the outer diameter of the plurality of pieces 34 rising on the top surface of the shaft product 99 shown in FIG. Large support surfaces 514 and 515 having shapes complementary to the side surfaces of the first stage shaft 14 and the second stage shaft 15 of the shaft product 99 are formed below the small support surface 516.

  FIG. 25 is a perspective view showing the shape of a finish bending punch 520 used in combination with the finish bending die 510. As shown in the figure, the finish bending punch 520 has a circular horizontal cross-sectional shape as a whole, a cylindrical straight body portion 522, and an intrusion portion 524 having a smaller diameter than the straight body portion 522 formed at the tip thereof. And. On the end surface of the straight body portion 522 on the side where the penetrating portion 524 is formed, a step corresponding to the difference in diameter between the two is formed. This level | step difference has comprised the process surface 523 which contributes to the bending process mentioned later. On the other hand, an inclined surface is also formed at the peripheral edge of the distal end of the penetration portion 524, which is a chamfered portion 525 formed so that the penetration portion 524 smoothly penetrates inside the second stage shaft 15. In addition, the penetration part 524 has an outer diameter that can penetrate into the inside of the section 34 rising from the top surface of the shaft product 99.

  FIG. 26 shows a tip bending receiver for preventing unnecessary deformation of the second stage shaft 15 when performing a finish bending process using the finish bending die 510 and the finish bending punch 520 shown in FIGS. It is a perspective view which shows the shape of 530. FIG. As shown in the figure, the finish bending receiver 530 includes a cylindrical straight body portion 534 protruding from a cubic metal lump 532. Further, the front end surface 538 of the straight body portion 534 is horizontal, and a recessed portion 539 having an inner diameter complementary to the outer diameter of the penetration portion 524 of the finish bending punch 520 shown in FIG. Further, a chamfered portion 536 is formed on the peripheral edge of the upper end of the straight body portion 534 so that it can be smoothly inserted into the second stage shaft 15 in finish bending described later. Therefore, only the annular region sandwiched between the chamfered portion 536 and the depressed portion 539 forms a horizontal plane on the front end surface 538 of the straight body portion 534.

  FIG. 27 is a cross-sectional view for explaining the operation of the forming apparatus 930 equipped with the finish bending die 510, the finish bending punch 520, and the finish bending receiver 530 shown in FIGS. As shown in the figure, the shaft product 99 is set in the molding device 930 with the second stage shaft 15 directed downward and the finish bending receiver 530 inserted therein. At this time, the straight body portion 534 of the finish bending receiver 530 is in close contact with the inner surface of the second stage shaft 15. Further, the front end surface 538 of the straight body portion 534 is in contact with the back surface of the shoulder portion 36 of the second stage shaft 15. Furthermore, the metal plate 10 portion of the shaft product 99 is also in close contact with the surface of the metal block 532 of the finish bending receiver 530. Therefore, the shaft product 99 will not be deformed toward the inner side even if it is subjected to finish bending as described later.

  Further, in the molding apparatus 930, the split dies 511 and 512 that form the finish bending die 510 are disposed on the side of the second stage shaft 15 so as to face each other. Further, the finish bending punch 520 is arranged to face the finish bending receiver 530 from below the second stage shaft 15. At this time, the depressed portion 539 of the finish bending receiver 530 and the penetration portion 524 of the finish bending punch 520 are arranged on the same axis.

  FIG. 28 shows the molding apparatus 930 shown in FIG. 27, in which a pair of split dies 511 and 512 are brought close to each other and brought into contact with the second stage shaft 15, and at the same time, the split dies 511 and 512 themselves are brought into contact with each other. Indicates the state. At this time, the large support surfaces 514 and 515 of the split dies 511 and 512 are substantially in close contact with the side surfaces of the first stage shaft 14 and the second stage shaft 15. Further, the small support surfaces 516 of the split dies 511 and 512 are in close contact with the vicinity of the root of the section 34 of the second stage shaft 15. However, at this stage, no substantial deformation has occurred in the shaft product 99, and the finish bending process has not yet been performed.

  FIG. 29 is a cross-sectional view showing a state where the finish bending punch 520 is raised and the finish bending process is performed in the molding apparatus 930 shown in FIGS. 27 and 28. As shown in the figure, in the section 34 of the second stage shaft 15, the vicinity of the root is sandwiched between the small support surface 516 of the finish bending die 510 and the side surface of the penetration portion 524 of the finish bending punch 520, and the second stage shaft. It is held upright with respect to 15 top surfaces. On the other hand, the vicinity of the tip of the section 34 is pressed against the processing surface 518 of the finishing bending die 510 by the processing surface 523 of the finishing bending punch 520 and forms an angle of 90 ° with respect to the top surface of the second stage shaft 15. It is bent toward the outside of the second stage shaft 15 until it is made. As described above, the portion other than the vicinity of the tip of the section 34 of the shaft product 99 is sandwiched between the finish bending receiver 530 and the finish bending die 510. Therefore, even if an external force is applied by the above-described finishing bending process, the portion other than the tip of the section 34 is not deformed at all.

  FIG. 30 is a perspective view showing the outer shape of the shaft product 99 formed by the finish bending process as described above. As shown in the figure, each of the segments 34 stands upright in the height direction of the second stage shaft 15 at the wide portion 35 near the base to the second stage shaft 15. On the other hand, the distal end portion 37 of the section 34 is expanded in a direction away from the center of the second stage shaft 15, and is expanded until it becomes parallel to the top surface to form a flange. Therefore, the tip portion 37 is obtained by bending the section 34 (FIG. 16) raised in the starting process by 90 °.

  In the shaft product 99 created as described above, the tip of the section 34 remains in the region within the diameter of the second stage shaft 15. Therefore, a part having a shaft hole having a shape complementary to the second stage shaft 15, for example, a gear, a cam, a lever, or the like can be inserted through the second stage shaft 15. In addition, after mounting a component having the same thickness as the height of the second stage shaft 15, a component mounted on the second stage shaft 15 by mounting a fastener such as a C clip or E clip on the wide portion 35 of the section 34. Can be prevented from falling off. Furthermore, the distance between the tip 37 of the section 34 and the shoulder 36 of the second stage shaft 15 is the same as the thickness of these fasteners, so that the parts mounted on the second stage shaft 15 can be free from shaft play. Can rotate. The C clip or E clip is made of an elastic material such as resin or metal, has the same inner diameter as the wide portion 35, has an outer diameter larger than the outer diameter of the second stage shaft 15, and part thereof It is a cut annular part. Moreover, since it can push in from the side with respect to the wide part 35 and it can mount | wear easily, components can be attached to the 2nd stage axis | shaft 15 by easy operation | work.

  In the above embodiment, the bending process of the section 34 is performed by dividing it into a preliminary bending process and a finishing bending process. However, if the workability and thickness of the material are sufficiently large, the preliminary bending process is omitted. The flange can also be formed by a single bending process.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

Sectional drawing of the initial forging apparatus 100 used at an initial forging process. Sectional drawing explaining operation | movement of the initial forging apparatus 100 in an initial forging process. Sectional drawing of the metal plate 10 after an initial forging process. Sectional drawing which shows a mode that the workpiece 20 was inserted in the stepped forging apparatus 200. FIG. The perspective view which shows the shape of the workpiece 20 inserted prior to a stepped forging process. Sectional drawing of the stepped forging apparatus 200 equipped with the stepped punch 240. FIG. Sectional drawing explaining operation | movement of the stepped forging apparatus 200 in a stepped forging process. Sectional drawing of the metal plate 10 after a stepped forging process. The perspective view of the metal plate 10 after a stepped forging process. The perspective view which shows the shape of the punching die 810 used in a punching process. The perspective view which shows the shape of the punching punch 820 used in a punching process. The perspective view which shows the shape of the shaft product 99 punched in the punching process. The perspective view which shows the shape of the burring die 310 used in a starting process. The perspective view which shows the shape of the burring punch 320 used in a starting process. The perspective view which shows the shape of the shaft product 99 which carried out the startup process in the startup process. The perspective view which shows the shape of the shaft product 99 which carried out the startup process in the startup process. The perspective view which shows the shape of the pre-bending die 410 used in a pre-bending process. The perspective view which shows the shape of the pre-bending punch 420 used in a pre-bending process. The perspective view which shows the shape of the preliminary | backup bending receiver 430 used in a preliminary | backup bending process. Sectional drawing which shows the layout of the shaping | molding apparatus 920 which implements a preliminary | backup bending process. Sectional drawing which shows the intermediate | middle operation | movement of the shaping | molding apparatus 920 which implements a pre-bending process. Sectional drawing which shows the last operation | movement of the shaping | molding apparatus 920 which implements a pre-bending process. The perspective view which shows the shape of the axial product 99 which carried out the pre-bending process in the pre-bending process. The perspective view which shows the shape of the finish bending die 510 used in a finish bending process. The perspective view which shows the shape of the finish bending punch 520 used in a finish bending process. The perspective view which shows the shape of the finish bending receiver 530 used in a finish bending process. Sectional drawing which shows the layout of the shaping | molding apparatus 930 which implements a finishing bending process. Sectional drawing which shows the intermediate | middle operation | movement of the shaping | molding apparatus 930 which implements a finishing bending process. Sectional drawing which shows the last operation | movement of the shaping | molding apparatus 930 which implements a finishing bending process. The perspective view which shows the shape of the shaft product 99 finished-bending in the finishing bending process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Metal plate, 12 Flat part, 14 First stage axis | shaft, 15 2nd stage axis | shaft, 16 Tip end surface, 18 Level difference part, 20 Work material, 22 Sagging surface, 24 Burr surface, 32 Notch part, 34 Section, 35 Wide part , 36 shoulder, 37 tip, 99 axis product, 100 initial forging device, 110 straight die, 112 opening shoulder, 116 hole, 120 knockout, 124 back pressure surface, 130 biasing member, 140 straight punch, 142 shoulder, 144 Pressurizing surface, 150 pressing member, 200 stepped forging device, 210 stepped die, 212 opening shoulder, 216 holes, 218 stepped portion, 220 knockout, 224 back pressure surface, 230 biasing member, 240 stepped punch, 241 large Diameter part, 243 Small diameter part, 242 Shoulder part, 244 Pressure surface, 248 Step part, 310 Burling die, 31 2 metal block, 314 through hole, 320 burring punch, 322 straight body, 324 tip, 410 pre-bending die, 411 split die, 412 split die, 414, 415 large support surface, 416 small support surface, 418 working surface, 420 Pre-bending punch, 422 Straight body part, 424 Penetration part, 425 Chamfer part, 423 Machining surface, 430 Pre-bending receiver, 432 Metal lump, 434 Straight body part, 436 Chamfer part, 438 Tip face, 439 Depression part, 510 Finish Bending die, 511 Division die, 512 Division die, 514, 515 Large support surface, 516 Small support surface, 518 Processing surface, 520 Finish bending punch, 522 Straight body portion, 523 Processing surface, 524 Penetration portion, 525 Chamfered portion, 530 Finished bending receiver, 532 metal block, 534 straight body part, 536 chamfered part, 538 Front end surface, 539 Depressed part, 810 Punching die, 812 Metal lump, 814 Through hole, 820 Punching punch, 822 Pressing part, 824 Punching part, 826 Edge part, 910 Forming apparatus, 920 Forming apparatus, 930 Forming apparatus

Claims (13)

By forging a metal plate, it protrudes from the metal plate, and is a shaft forming method for forming a hollow shaft with multiple stages having a smaller diameter toward the tip,
A preparatory step of placing the metal plate to be processed on the upper surface of the hole of the die in which the hole having the same inner diameter as the outer diameter of the base shaft is formed;
While pushing the metal plate supported on the upper surface of the hole into the hole with a punch having the same outer diameter as the inner diameter of the root shaft, a knockout provided in advance in the hole of the die An initial forging step of rolling the metal plate pressed against the tip of the punch to the side surface of the shaft by applying back pressure to the metal plate with the knockout while facing the tip of the punch,
The stepped die of the stepped die having the same outer diameter as that of the shaft formed immediately before and further having a stepped hole having the same inner diameter as the outer diameter of the shaft to be formed in the back. A shaft insertion step of inserting into the hole the shaft already formed in the metal plate to be processed;
The metal inserted into the stepped hole with a stepped punch having the same outer diameter as the inner diameter of the shaft formed immediately before and having the same outer diameter as the inner diameter of the shaft to be formed at the tip. While pushing the plate further into the stepped hole, a back pressure is applied to the metal plate with the knockout with a knockout provided in advance in the stepped hole facing the tip of the stepped punch. A step forming method comprising: a stepped forging step of rolling the metal plate pushed by the tip of the stepped punch onto the side surface of the shaft. After the initial forging step and before the stepped forging step, further includes a material insertion step of inserting a workpiece into the shaft already formed,
The shaft forming method according to claim 1, wherein in the stepped forging step, the metal plate and the workpiece are rolled onto a side surface of the shaft.   The shaft forming method according to claim 2, wherein the workpiece is formed by punching, and a sag side of the workpiece is inserted into a tip end side of the shaft in the material insertion step.   In the stepped forging step, the volume of the space defined by the stepped die, the stepped punch, and the knockout is equal to the sum of the volumes of the metal plate and the work area of the work material. The shaft forming method according to claim 2, wherein the volume of the workpiece is adjusted.   The length in the pushing direction of the same outer diameter as the inner diameter of the shaft to be formed in the stepped punch is shorter than the length in the pushing direction of the same inner diameter as the outer diameter of the shaft to be formed in the stepped die. The shaft forming method according to 1. A punching process using a punch and a die to form three or more linear cuts formed radially from the center of the top surface of the shaft;
Using a burring punch and a burring die, a plurality of sector-shaped section push-bending defined by the incision, and a rising process for standing the section in the height direction of the shaft;
Using a bending punch and a bending die, the tip of the section that stands upright in the axial direction is bent radially with respect to the axis, and the section stands upright with respect to the top surface, and the tip of the upright section The shaft forming method according to claim 1, further comprising a bending step of forming a horizontal portion extending radially from the horizontal portion.   The shaft forming method according to claim 6, wherein a tip portion of the horizontal portion is positioned inside a region defined by extending a side surface of the shaft in the axial direction.   The said bending process is further equipped with the intermediate | middle bending process which bends the front-end | tip part of the said upright part to the intermediate angle of less than 90 degrees, and the final bending process which bends the said front-end | tip part to 90 degrees and makes it a horizontal part. Shaft forming method.   The shaft forming method according to claim 6, wherein in the bending step, a part of the bending die abuts against the upright portion from the side to prevent deformation.   The shaft forming method according to claim 9, wherein in the bending step, a bending receiver is brought into contact with the back surface of the top surface from the inside of the shaft to prevent deformation of the top surface.   The shaft forming method according to claim 9, wherein a distance between the horizontal portion and the top surface is substantially equal to a thickness of a C-ring attached to the upright portion. A preparation step of placing the metal plate to be processed on the upper surface of the hole of the die in which the hole having the same inner diameter as the outer diameter of the base of the shaft is formed;
While pushing the metal plate supported on the upper surface of the hole into the hole with a punch having the same outer diameter as the inner diameter of the root shaft, a knockout provided in advance in the hole of the die An initial forging step of rolling the metal plate pressed against the tip of the punch to the side surface of the shaft by applying back pressure to the metal plate with the knockout while facing the tip of the punch,
The stepped die of the stepped die having the same outer diameter as that of the shaft formed immediately before and further having a stepped hole having the same inner diameter as the outer diameter of the shaft to be formed in the back. A shaft insertion step of inserting into the hole the shaft already formed in the metal plate to be processed;
The metal inserted into the stepped hole with a stepped punch having the same outer diameter as the inner diameter of the shaft formed immediately before and having the same outer diameter as the inner diameter of the shaft to be formed at the tip. While pushing the plate further into the stepped hole, a back pressure is applied to the metal plate with the knockout with a knockout provided in advance in the stepped hole facing the tip of the stepped punch. By forming, a stepped forging step of rolling the metal plate pushed to the tip of the stepped punch to the side surface of the shaft is formed by a shaft forming method,
A shaft product that is formed by forging a metal plate and has a multi-stage hollow shaft that protrudes from the metal plate and has a smaller diameter toward the tip. A punching process using a punch and a die to form three or more linear cuts formed radially from the center of the top surface of the shaft;
Using a burring punch and a burring die, a plurality of sector-shaped section push-bending defined by the incision, and a rising process for standing the section in the height direction of the shaft;
Using a bending punch and a bending die, and formed by a shaft forming method further comprising a bending step of bending a distal end portion of the section standing upright in the radial direction with respect to the shaft,
The shaft product according to claim 12, further comprising an upright portion that stands upright with respect to the top surface of the shaft, and a horizontal portion that extends radially from a tip of the upright portion.

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