JP5151315B2 - Method for producing hollow molded body - Google Patents

Description

  The present invention relates to a method for producing a hollow molded body mainly used for automobile component parts by forging.

Conventionally, hollow molded bodies used for automobile components, that is, having both end shaft portions and an outer bulging intermediate bulging portion, and a through hole is formed in the center portion of these both end shaft portions and the intermediate bulging portion. As a method for manufacturing a hollow molded body, for example, first, a solid material is forged cold, and both end portions are thin-walled portions having a large inner diameter, and an intermediate portion positioned between both end portions is less than the thin-walled portion. Form a primary molded body with a small inner diameter, and then cold-draw only the thin wall portions at both ends to form an intermediate bulge portion of the outer bulge in the intermediate portion, and both end portions Is formed so that the inner diameter of the inner portion is equal to the inner diameter of the intermediate portion.
No. 7-53792

  By the way, in the manufacturing method described above, only the thin wall portions at both ends of the hollow molded body are cold-drawn at a stretch and molded into a desired shape, so that the amount of processing at the time of plastic working It depends on the limit value. For this reason, there is a problem that a large facility is required or that it is difficult to manufacture a hollow molded body that requires a large amount of processing and accuracy.

  Therefore, the present invention compresses in the length direction an intermediate molded body having the same outer diameter that has a large-diameter hole at both ends and the subsequent small-diameter hole penetrates, and simultaneously expands the small-diameter hole. The large diameter hole is extended to near the center in the length direction of the intermediate part, and the intermediate part is bulged outwards, so that a large amount of processing can be easily obtained, and high-precision forging is achieved. An object is to provide a method for producing a hollow body that can be molded.

In order to solve the above problems, the present invention has both end shaft portions and a spherical intermediate bulge portion of the outer bulge, and a through-hole having the same diameter is formed at the center portion of the both end shaft portions and the intermediate bulge portion. As a method for producing a hollow molded body, a cylindrical solid material is first formed by forging, and a primary molded body having the same outer diameter having a solid intermediate portion and bottomed large-diameter holes at both ends. Next, forging is performed so that the small-diameter hole portion is continuous with the center of the bottom portion of each large-diameter hole portion of the primary molded body, and only the central portion in the length direction in the middle portion is solid and large at both end portions. A secondary molded body having the same outer diameter having a diameter hole portion and a subsequent small diameter hole portion is formed, and thereafter, only the central solid portion in the intermediate portion of the secondary molded body is punched and processed at both ends. Form a tertiary molded body with the same outer diameter that has a large-diameter hole in the part and the subsequent small-diameter hole penetrates, and then tertiary molding At the same time as compressing in the length direction, the small-diameter hole is expanded, and the large-diameter hole is extended to near the center in the length direction of the intermediate part and the intermediate part is bulged outward. And forming a quaternary molded body having a spherical intermediate bulging portion of the outer bulging in the intermediate portion and having a large-diameter hole in the shaft portion at both ends reaching the center in the length direction of the intermediate bulging portion. Thus, the small diameter surplus portion left in the center in the length direction of the intermediate bulging portion of the quaternary molded body is punched to form a through hole having the same diameter at the center of both end portions and the intermediate bulging portion. A final hollow molded body is formed.

According to the present invention, a cylindrical solid material is formed by forging to form a primary molded body having the same outer diameter with a solid middle portion and bottomed large-diameter holes at both ends, and then primary Forging molding so that the small-diameter hole portion is continuous with the center of the bottom of each large-diameter hole portion of the molded body, only the central portion in the length direction at the intermediate portion is solid, and has the large-diameter hole portions at both ends, and Subsequently, a secondary molded body having the same outer diameter with a small-diameter hole portion is formed, and thereafter, only the central solid portion in the intermediate portion of the secondary molded body is punched and large-diameter hole portions are formed at both ends. Since the third molded body having the same outer diameter through which the subsequent small-diameter hole portion passes is formed, the tertiary molded body can be forged with high accuracy. Further, at the same time as compressing the tertiary molded body in its length direction, while expanding the small diameter hole portion, the large diameter hole portion is extended to near the center in the length direction in the intermediate portion to bulge the intermediate portion outward. Forming a quaternary molded body having a large-diameter hole portion that is provided with a spherical intermediate bulge portion that is outwardly bulged at the intermediate portion and that has both end shaft portions near the center in the length direction of the intermediate bulge portion. Since it did in this way, while forming a quaternary molded object, while being able to obtain a big processing amount easily, it can forge-mold with high precision. After that, by punching the small diameter part left in the center in the length direction of the intermediate bulging portion of the quaternary molded body that has been forged with high precision, a large amount of processing can be easily performed in forming the quaternary molded body. It can be obtained and can be forged with high accuracy. In other words, when forming a spherical intermediate bulging part of the outer bulge in the intermediate part, it can be easily molded without giving a large burden to the mold with a small molding load. By punching out only a small small diameter portion projecting inward left in the middle in the length direction of the intermediate bulging portion of the next molded body, both end shaft portions are maintained in the state in which the accuracy of the quaternary molded body is maintained as it is. The final hollow molded body in which the central portion with the intermediate bulging portion is penetrated into the same diameter can be finished with high accuracy.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a method for producing a hollow molded body according to the present invention. First, as shown in FIG. 1, a solid metal round bar is cut into a predetermined length to form a cylindrical hollow material A.

  Next, the solid material A is continuously forged by a multistage forging machine under cold conditions.

  In the first stage of the forging machine, as shown in FIGS. 2 and 3, the solid material A is upset by the die 10 and the punch 11 to form the formed body B.

  In the second stage of the forging machine, as shown in FIGS. 4 and 5, large diameter holes C1 and C2 are formed on the central axis at both ends of the shaped body B by forging with a die 20 having a forming pin 20a and a punch 21. To form a cylindrical primary molded body C having the same outer diameter and having a large-diameter hole C1 and C2 with bottoms at both ends.

  In the third stage of the forging machine, as shown in FIGS. 6 and 7, a die 30 having a stepped molding pin 30a and a stepped punch 31 are provided at the center of the bottom of each large-diameter hole C1, C2 of the primary molded body C. Are formed so that the small-diameter holes D3 and D4 are continuous with each other, and only the central portion D5 in the longitudinal direction in the middle portion is solid, and the large-diameter holes D1 and D2 are provided at both ends and the small diameter following this. A secondary molded body D having the same outer diameter and having the holes D3 and D4 is formed.

  In the fourth stage of the forging machine, only the central solid part D5 in the intermediate part of the secondary molded body D is formed by the die 40 having the punching pin 40a and the cylindrical punch 41 as shown in FIGS. Punching is performed to form a tertiary molded body E having the same outer diameter having large-diameter holes E1 and E2 at both ends and through which the small-diameter holes E3 and E4 pass. The punching waste E5 punched by the punching pin 40a is discharged to the outside through a discharge passage 41a provided on the punch 51 side.

In the fifth stage of the forging machine, as shown in FIGS. 10 and 11, a die 50 having a molding part 50a and a molding pin 50b, and a cylindrical punch 51 including a cylindrical molding part 51a and a center punch 51b, At the same time as compressing the tertiary molded body E in the length direction, the large diameter holes E1 and E2 are extended to near the center in the length direction in the middle part while expanding the small diameter holes E3 and E4. Large-diameter hole portions F1 and F2 which are formed by forging to be bulged outward, have spherical intermediate bulging portions F3 which are outwardly bulging in the intermediate portions, and which are close to the center in the length direction of the intermediate bulging portion F3 at both end shaft portions. A quaternary molded body F having In this case, the small-diameter surplus portion F4 remains at the center in the length direction of the intermediate bulge portion F3.

  In the sixth stage (final stage) of the forging machine, as shown in FIGS. 12 and 13, the die 60 having the punching pin 60a and the cylindrical punch 61 are used in the intermediate bulging portion F3 of the quaternary molded body F. The small diameter part F4 remaining in the center in the length direction is punched and a through hole G4 having the same diameter or substantially the same diameter is formed at the center part of both end shaft parts G1, G2 and the intermediate bulge part G3. A hollow molded body G is formed. The punching waste G4 punched by the punching pin 60a is discharged to the outside through a discharge passage 61a provided on the punch 61 side.

As described above, a cylindrical solid material is formed by forging to form a primary molded body having the same outer diameter with a solid middle portion and bottomed large-diameter holes at both ends, and then primary molding. Forging is performed so that the small-diameter hole portion is continuous with the center of the bottom of each large-diameter hole portion of the body, and only the central portion in the longitudinal direction at the intermediate portion is solid, and the large-diameter hole portions are provided at both ends. After that, a secondary molded body having the same outer diameter with a small-diameter hole portion is formed, and then only the central solid portion in the intermediate portion of the secondary molded body is punched to have large-diameter hole portions at both ends. In addition, since the tertiary molded body having the same outer diameter through which the subsequent small-diameter hole passes is formed, the tertiary molded body can be forged with high accuracy. Further, at the same time as compressing the tertiary molded body in its length direction, while expanding the small diameter hole portion, the large diameter hole portion is extended to near the center in the length direction in the intermediate portion to bulge the intermediate portion outward. Forming a quaternary molded body having a large-diameter hole portion that is provided with a spherical intermediate bulge portion that is outwardly bulged at the intermediate portion and that has both end shaft portions near the center in the length direction of the intermediate bulge portion. Since it did in this way, while forming a quaternary molded object, while being able to obtain a big processing amount easily, it can forge-mold with high precision. After that, by punching the small diameter part left in the center in the length direction of the intermediate bulging portion of the quaternary molded body that has been forged with high precision, a large amount of processing can be easily performed in forming the quaternary molded body. It can be obtained and can be forged with high accuracy. In other words, when forming a spherical intermediate bulging part of the outer bulge in the intermediate part, it can be easily molded without giving a large burden to the mold with a small molding load. By punching out only a small small diameter portion projecting inward left in the middle in the length direction of the intermediate bulging portion of the next molded body, both end shaft portions are maintained in the state in which the accuracy of the quaternary molded body is maintained as it is. The final hollow molded body in which the central portion with the intermediate bulging portion is penetrated into the same diameter can be finished with high accuracy.

  It is a front view of the solid raw material used with the manufacturing method of this invention.   It is a front view of the molded object shape | molded by the 1st step | paragraph in the manufacturing method.   It is explanatory drawing of the forging state in the 1st step | paragraph.   It is a front view of the molded object shape | molded by the 2nd step | paragraph in the manufacturing method.   It is explanatory drawing of the forging state in the 2nd step | paragraph.   It is a front view of the molded object shape | molded by the 3rd step | paragraph in the manufacturing method.   It is explanatory drawing of the forging state in the 3rd step | paragraph.   It is a front view of the molded object shape | molded by the 4th step | paragraph in the manufacturing method.   It is explanatory drawing of the punching state in the 4th step | paragraph.   It is a front view of the molded object shape | molded by the 5th step | paragraph in the manufacturing method.   It is explanatory drawing of the forging state in the 5th step | paragraph.   It is a front view of the molded object shape | molded by the 6th step | paragraph in the manufacturing method.   It is explanatory drawing of the punching state in the 6th step | paragraph.

Explanation of symbols

A Solid material C Primary compact C1, C2 Large diameter hole D Secondary compact D1, D2 Large diameter hole D3, D4 Small diameter hole D5 Central solid part E Tertiary compact E1, E2 Large diameter hole E3 , E4 Small-diameter hole part F Quartz molded body F1, F2 Large-diameter hole part F3 Intermediate bulge part F4 Small-diameter surplus part G Final hollow molded body G1, G2 Both end shaft part G3 Intermediate bulge part G4 Through-hole

Claims (1)

As a method for producing a hollow molded body having both end shaft portions and an outer bulging spherical intermediate bulge portion, and having a through-hole having the same diameter at the center portion between the both end shaft portions and the intermediate bulge portion First, a cylindrical solid material is forged and formed to form a primary molded body having the same outer diameter with a solid middle portion and bottomed large-diameter holes at both ends. Forging is performed so that the small-diameter hole portion is continuous with the center of the bottom portion of each large-diameter hole portion. Forming a secondary molded body having the same outer diameter with a small-diameter hole, then punching only the central solid part in the intermediate part of the secondary molded body, and having large-diameter holes at both ends; and Form a tertiary molded body of the same outer diameter through which the subsequent small-diameter hole passes, and then compress the tertiary molded body in its length direction. Sometimes subjected to heading shaped to bulge the middle portion outward extending while enlarged the small-diameter hole portion large-diameter hole portion to the direction near the center in the length in the middle portion, the bulge outside middle portion spherical intermediate A quaternary molded body having a bulging portion and having a large-diameter hole at the both end shaft portions near the center in the length direction of the intermediate bulging portion is formed. A small-diameter surplus portion left in the center in the length direction of the protruding portion is punched to form a final hollow molded body in which through holes having the same diameter are formed at the center portions of both end portions and the intermediate bulging portion. A method for producing a hollow molded article, characterized in that it is configured as described above.

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