JPH08197177A - Formation of boss part of sheet metal blank - Google Patents

Abstract

PURPOSE: To increase the contact length of a cylindrical boss part and a revolving shaft by pressurizing a sheet metal blank formed with the cylindrical boss part which projects one way and forming the boss part in such a manner that the boss part projects to the other surface from the boss side end as well. CONSTITUTION: A lower mold 14 and upper mold 15 holding the sheet metal blank 10 therebetween are pressed by a press machine, by which a flat part 8 is pressurized from a sheet thickness direction. As a result, the material of the flat part 8 is fluidized toward the outer peripheral side, by which the outer peripheral part 10a is made thicker. The material of the boss part 6 is plastically fluidized in an arrow F direction by pressing of the upper molds 15, 15' and the lower mold 14 in such a manner that the axial length of the inner peripheral surface is made sufficiently long in the thickness increasing stage. The boss part 6 is thus so formed that its end 6A projects from the boss part end 8A of the other surface of the flat part 8. As a result, the boss part 6 is made longer by as much as the projection from the other surface of the sheet metal blank 10, by which the contact length with the revolving shaft to be fitted to the boss part 6 is made long and the rotation of a rotating body is stabilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a boss portion on a sheet metal material when manufacturing, for example, a poly V pulley or a crankshaft pulley.

[0002]

2. Description of the Related Art A sheet metal pulley shown in FIG. 11, that is, a sheet metal material 10 having a boss portion 6 and a flat portion 8 around the boss portion 6 is formed on the boss portion 6. A rotary shaft (not shown) is fitted.

However, in the sheet metal material 10 of FIG. 11, the inner peripheral surface of the one end of the boss 6 is an arcuate curved surface P because of the manufacturing technique. If the curved surface P remains as it is when the metal member 10 is formed on the sheet metal pulley, the outer peripheral surface of the rotating shaft fitted into the boss portion 6 and the inner peripheral surface of the boss portion 6 come into contact with each other. Since the length L1 is shortened, when the sheet metal pulley is used (rotated), a large tension from the belt causes the pulley to wobble (dance) with respect to the rotating shaft, and the pulley cannot be used.

Therefore, conventionally, at the stage of the sheet metal material 10, the inner diameter of the boss portion 6 is set to be smaller than the outer diameter of the rotating shaft, and it is later cut as shown by the broken line in FIG. The contact length was secured.

[0005]

However, if this is done, it will take time and effort for cutting, and the environment at the work site will deteriorate due to the generation of chips, so improvement is desired.

The present invention has been made under the above circumstances, and it is necessary to secure a sufficiently long contact length between the boss and the rotary shaft fitted in the boss without cutting the boss. An object of the present invention is to provide a method for forming a boss portion of a sheet metal material that can be performed.

[0007]

In order to achieve the above object, a method for forming a boss portion of a sheet metal material according to the present invention is to press a sheet metal material having a cylindrical boss portion protruding from one surface,
The boss portion is formed so as to also protrude from the end portion on the boss portion side of the other surface of the sheet metal material.

According to this method, the boss portion projecting from one surface of the sheet metal material becomes longer by the amount of projecting from the end surface of the other surface of the sheet metal material on the side of the boss portion. The length becomes longer.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS.

FIG. 1 shows a bending (drawing) step. In this bending step, as shown in FIG. 1 (A), a circular flat sheet metal material 1 is formed into a lower die 2 composed of a punch 2a and a punch holder 2b. After setting on top, this lower mold 2 and die 3a
By bringing the upper die 3 composed of the die holder 3b close to each other by a pressing machine, as shown in FIG. It is curved in a shape that bulges into an arcuate convex.
The curved shape at this time is the tip shape of the punch 2a of the lower mold 2 and the inlet tapered surface 3b1 of the die holder 3b of the upper mold 3.
Determined by the shape of.

Next, as shown in FIG. 2, with the material 1 curved as described above held in a dedicated perforating holder 4, a drilling tool 5 for a lathe or a drilling machine is used, and the top portion thereof is used. A hole 5A having a diameter of about 4 to 5 mm is formed in the hole.

Subsequently, a die different from the die used in the bending (drawing) step is used, and a substantially circular shape is formed on the inner surface of the protrusion 12c formed in the punch holder 12b of the lower die 12 in an annular shape. In a state in which the outer peripheral edge portion 1e of the material 1 curved in an arc shape is abutted to restrict the outward spread in the radial direction, FIG.
As shown in (A) and (B), punch 12 for burring
By bringing the lower die 12 and the upper die 13 having a1 close to each other, the peripheral portion 1c of the hole 5A is bent in the bulging direction of the material 1.

Subsequently, a bending (ironing) step for forming the cylindrical boss portion is performed. In this bending (ironing) step, as shown in FIGS. 4 (A) and 4 (B), the punch 12a dedicated to ironing is used to bring the upper die 13 and the lower die 12 close to each other, and The curved portion 1b between the portion 1e and the hole peripheral portion 1c that has been subjected to the burring process in the previous step is squeezed, and the curved portion 1b is pressed in a direction opposite to the bulging direction and bent into a concave shape. As a result, the flat portion 8 is formed, and the hole peripheral portion 1c is deformed along the outer peripheral surface of the punch 12a to form the cylindrical boss portion 6 in the central portion. Even during this bending process, material 1
The outer peripheral edge portion 1e of the lower die 12 is kept in contact with the inner surface of the protrusion 12c formed in the punch holder 12b of the lower die 12 so that the outward expansion in the radial direction is always restricted. The material does not escape to the outside in the radial direction at all, but escapes to the tubular boss portion 6 side, so that the wall thickness of the tubular boss portion 6 can be secured sufficiently large.

After the bending step as described above, FIG.
As shown in (A) and (B), punch 12a dedicated to finishing
2 and the die holder 13b2 are used to compress the end surface 6a of the tubular boss portion 6 from the axial direction, thereby performing a boss finishing step of finishing the tubular boss portion 6 to a predetermined protruding height.

Through the above steps, as shown in FIG. 6, a cylindrical boss portion 6 is formed at the center thereof, and a flat portion 8 is integrally formed between the boss portion 6 and the outer peripheral edge portion 1e. A sheet metal material 10 is obtained.

The sheet metal blank 10 of FIG. 6 is exactly the same as that described above with reference to FIG. Therefore, the present invention is applied to the process for increasing the height of the boss portion 6 of the sheet metal material 10. Then, the sheet metal material 10 having the boss portion 6 having an increased height is used as a material of a sheet metal poly V pulley, for example. Below, FIG.
The process from the sheet metal material 10 to the sheet metal poly V pulley will be described.

First, a step of thickening the outer peripheral wall portion for forming the poly-V groove is performed. In this thickening step, as shown in FIG. 7, the flat portion 8 of the sheet metal material 10 is removed by bringing the lower die 14 and the upper die 15 sandwiching the sheet metal material 10 close to each other through a press machine. Pressure is applied from the plate thickness direction. As a result, the material of the flat portion 8 flows to the outer peripheral side, and the outer peripheral portion 10a of the material 10 is thickened. At this time, the position of the boss portion 6 is substantially regulated, and only a part of the material of the flat portion 8 flows, and one surface of the flat portion 8 (the side from which the boss portion 6 projects) The height of protrusion of the boss portion 6 from the surface) and the wall thickness of the boss portion 6 hardly change. Then, in this thickening step, the upper molds 15 and 1 are arranged so that the axial length of the inner peripheral surface of the boss portion 6 becomes sufficiently long.
The material of the boss portion 6 is plastically flowed in the direction of the arrow F by pressing with 5'and the lower die 14, so that the one end portion 6A of the boss portion 6 projects from the boss portion side end portion 8A of the other surface of the flat portion 8. To be molded.

Next, the step of slitting the outer peripheral wall portion 10a thickened as described above is performed. In this slit forming step, as shown in FIG. 8, the flat portion 8 and the boss portion 6 of the sheet metal material 10 excluding the thick outer peripheral wall portion 10a are sandwiched between the inner rotating die 16 and the upper rotating die 17, and Rotating inner mold 1
The entire sheet metal material 10 is rotated by the rotation of 6 and the rotating upper die 17. Then, a V-shaped slit projection 18a formed on the outer peripheral surface of the rolling roller 18 is pressed against the central portion of the thick outer peripheral wall portion 10a of the rotating sheet metal blank 10 while rotating the rotary shaft. By cutting into the core side, the thick outer peripheral wall portion 10a is cut and formed into a V shape.

Subsequently, as shown in FIG. 9, while rotating the entire sheet metal material 10 by the rotation of the inner rotating mold 16 and the upper rotating mold 17, the V of the rotating sheet metal material 10 is rotated.
A wide outer peripheral wall portion 10b is roll-formed on the outer periphery of the sheet metal material 10 by pressing the outer peripheral wall portion 10a, which is cut in a circular shape, from the outside while rotating a rolling roller 19 for forming a wide outer peripheral wall. Shape. The slit forming step and the wide peripheral wall forming step may be performed at the same time using a common mold, or may be separately performed using different molds. Further, the molding is not limited to one molding, and the molding may be performed plural times.

Finally, a step of forming a poly V groove on the wide outer peripheral wall portion 10b formed as described above is performed. In this poly V groove forming step, as shown in FIG. 10, the flat portion 8 and the boss portion 6 of the sheet metal material 10 excluding the wide outer peripheral wall portion 10b are sandwiched between the inner rotating die 20 and the upper rotating die 21,
The entire sheet metal material 10 is rotated by the rotation of the inner rotating mold 20 and the upper rotating mold 21. Then, on the wide outer peripheral wall portion 10b of the rotating sheet metal material 10, an uneven forming portion 22a formed on the outer peripheral surface of the rolling roller 22 from the outside.
Is rotated and pressed into the rotary shaft core side to roll-form a poly V groove 11 formed of a plurality of V groove groups on the wide outer peripheral wall portion 10b. In addition, this poly V
The groove 11 may be formed by a single rolling, but the spare poly V
Material 1 that has undergone the groove forming process and this preliminary poly-V groove forming process
It is preferable that the poly V groove of 0 is further subjected to rolling, and a plurality of times (about 2 to 4 times) of rolling forming having a finishing step of finishing the depth and the pitch as required is performed.

In the above description, a method of forming a poly V pulley from a sheet metal material having a long boss portion 6 has been described, but the present invention may be applied to the formation of a V pulley having a single V groove. Alternatively, other types of pulleys can be molded from the sheet metal material.

[0022]

As described above, according to the method of forming the boss portion of the sheet metal material of the present invention, the sheet metal material having the cylindrical boss portion projecting from one surface is pressed, and the boss portion is removed from the sheet metal. Since the molding material is formed so as to project from the end portion on the boss portion side of the other surface of the material, the boss portion becomes longer as much as it projects from the other surface of the sheet metal material. Therefore, the contact length of the rotary shaft fitted into the boss portion becomes longer,
The pulley will not dance when rotating.

[Brief description of drawings]

1A and 1B are cross-sectional views of a main part for explaining a bending (drawing) step in a method for forming a sheet metal pulley of the present invention.

FIG. 2 is a cross-sectional view of a main part for explaining the same boring step.

3 (A) and 3 (B) are cross-sectional views of a main part for explaining the burring step of the same.

FIGS. 4A and 4B are cross-sectional views of a main part for explaining the bending (ironing) step in the same.

5 (A) and 5 (B) are cross-sectional views of a main part for explaining the boss part finishing step of the same.

FIG. 6 is a cross-sectional view of the sheet metal material after forming the above boss portion.

FIG. 7 is a half cross-sectional view of a main part for explaining the thickening step of the above.

FIG. 8 is a half cross-sectional view of an essential part for explaining the first rotational molding step of the above.

FIG. 9 is a half cross-sectional view of a main part for explaining the second rotational molding process of the above.

FIG. 10 is a half cross-sectional view of an essential part for explaining a third rotational molding (poly V groove molding) step of the above.

FIG. 11 is an explanatory diagram of a sheet metal material.

[Explanation of symbols]

 8 Flat part 6 Boss part 10 Sheet metal material 8A End part of flat part on boss part 6A One end of boss part 11 Poly V groove (V groove)

Claims (1)

[Claims] 1. A tubular boss portion pressurizes a sheet metal material having one surface protruding from one surface so that the boss portion is also protruded from an end portion on the boss portion of the other surface of the sheet metal material. A method for forming a boss portion of a sheet metal material, which comprises molding.