JPH04157253A - Manufacture of idle pulley with sheet metal back - Google Patents

Abstract

PURPOSE:To prolong the life of a pulley by driving a rising portion in the opposite direction to the rising direction to form a folded-back portion on the base of the rising portion. CONSTITUTION:The lower surface and outer peripheral surface of a sheet metal blank 10 are supported by a holding die 25 having a folded-back groove 24 and the upper surface side of the sheet metal black 10 is held by respective holding dies 26, 27. The upper end of a rising portion 23 is driven in the opposite direction to the rising direction, i.e., downward between the respective holding dies 26, 27 under such state by a driving die 28 moving downward to form a folded-back portion 29 corresponding to the shape of the folded-back groove 24 on the base 23a of the rising portion 23. Since the folded-back portion 29 is not formed by a squeezing operation, the folded-back portion 29 is not thinned to ensure the sufficient thickness, so that the strength of an idle pulley 1 is improved to prolong the life of the pulley.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing a sheet metal rear idler pulley in which a folded portion is formed during molding of a belt passing portion in order to prevent internal stress from remaining during molding. .

(Prior art) Conventionally, idle pulleys used in vehicles, etc. are generally formed by casting or forging, but when formed by casting, the weight becomes heavy, and it is difficult to form by forging. When doing so, cutting work or the like is required to ensure precision after forging, which poses a problem of increasing costs.

For this reason, a manufacturing method has been proposed in which a pulley is formed by pressing and roll forming a sheet metal (Japanese Patent Laid-Open No. 124042/1982).

This manufacturing method involves drawing and forming a sheet metal material to form the fitting part of the bearing, and then reverse drawing the outside of the fitting part to make the periphery of the sheet metal material stand up. , and then bend this rising portion in the opposite direction to the rising direction. Then, while pressing and rolling this rising portion from the outside, the base is bent, and a folded portion is formed at the base of this rising portion,
After that, the bearing is fitted into the fitting part. This results in
forming a pulley.

Here, the reason why a folded part is formed at the base of this rising part is to absorb the residual stress caused by drawing and bending in this manufacturing method, and this prevents eccentricity of the pulley. Prevents shortening of lifespan.

(Problem to be Solved by the Invention) As described above, in the conventional pulley manufacturing method, residual stress is absorbed by forming a folded part, but this folded part causes the roller to move from the outside to the inside. During the movement process of this roller, the bending action acting on the base of the rising part is large;
As a result, the sheet metal of the folded portion is extended, and a thin portion is formed in a portion thereof.

However, when a thin wall portion is formed at the folded portion, stress concentration occurs in this thin wall portion when the pulley is used, resulting in damage to the folded portion, which results in a shortened service life. It had become impossible to do so.

In view of the above-mentioned conventional problems, it is an object of the present invention to provide a sheet metal back idler pulley that is free from the formation of thin wall portions at the folded portions where belt tension is most applied, and has a long lifespan. The purpose of this invention is to provide a method for manufacturing the same.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention includes a fitting part forming process in which a fitting part of the bearing is formed by drawing the center of a sheet metal material; After the section forming step, the outer side of the fitting section is reverse drawn to raise the periphery of the sheet metal material, and the belt spanning section is formed in this rising section, and the belt spanning section is formed. After the forming step, a folded cotton forming step is performed in which the rising portion is nailed in a direction opposite to the rising direction to form a folded portion at the base of the rising portion, and after the folded cotton forming step, the bearing is attached to the fitting portion. The fitting bearing is characterized by having a fitting process.

(Function) According to the present invention, in the folded cotton forming step, the rising portion is nailed in the opposite direction to the rising direction to form the folded portion at the base of the rising portion, so that the folded portion is formed while being compressed, and the folded portion is formed while being compressed. Thin portions are less likely to be formed in the folded portion.

(Example) Figures 1 to 11 show an example of the method for manufacturing a sheet metal rear idler pulley according to the present invention. Figure 1 is a perspective view of the idler pulley, and Figure 2 is a perspective view of the idler pulley. FIG. 3 is an assembled perspective view.

This sheet metal back idler pulley 1 is composed of a pulley body 2, a ball bearing 3, and a bearing holding plate 4. The ball bearing 3 is press-fitted into the pulley body 2, and the press-fitted ball bearing 3, the bearing is riveted 48 by the holding plate 4.
is fixed inside the boob body 2.

FIGS. 3 to 11 are cross-sectional views showing the manufacturing process of the idle pulley, and FIGS. 3 and 4 show the process of forming the fitting portion of the bearing. That is, as shown in FIG. 3, the flat sheet metal material 10 except for the center portion is held between the upper and lower pressing dies 11 and 12, and the center of the sheet metal material 10 is bulged upward by the inner drawing die 13. A fitting portion 14 of the bearing is temporarily formed inside this bulged portion.

After this temporary forming, as shown in FIG.
5. Clamped by 16, inner drawing die 17 and outer drawing die 18
This sheet metal material 10 is narrowed down by
form.

FIG. 5 shows the belt-crossing forming process performed after the fitting part forming process. That is, while the upper and lower surfaces of the center of the sheet metal material 10 are pressed by the respective presser dies 19 and 20, the presser die 2 having a depression in a part of the lower surface on the peripheral side of the sheet metal material 10 is used.
1, and the presser die 21 is drawn from above by a drawing die 22a and from below by a drawing die 22b,
A rising portion 23 is formed. This rising portion 23 constitutes a belt spanning portion.

FIG. 6 shows a folding part forming process performed after this belt spanning part forming process. That is, the lower surface and outer circumferential surface of the sheet metal material 10 are supported by the presser die 25 having the folded grooves 24, and the upper surface side of the sheet metal material 10 is supported by each presser die 26.
27.

In this state, the upper end of the rising part 23 is struck in the opposite direction to the rising direction, that is, downward, by the striking die 28 moving downward between the presser dies 26 and 27, and the upper end of the rising part 23 is bent back to the base 23a of the rising part 23. A folded portion 29 corresponding to the shape of the groove 24 is formed.

Since this folded part 29 is not formed by drawing, the folded part 29 does not become thin.
Sufficient board thickness is ensured. This process also aligns the center of the idler pulley.

FIG. 7 and FIG. 8 show a belt spanning portion shaping step performed after the folded portion shaping step. That is, as shown in FIG. 7, the sheet metal material 10 is pressed from above and below by the presser dies 30.31, and the sheet metal material 10 is rotated by each of the pressers 30.31. The accuracy of the thickness of the belt crossing area is achieved by applying

After achieving this accuracy, as shown in Fig. 8, the sheet metal material 10
is again held between the upper and lower presser dies 33, 34, and the sheet metal material 10 is rotated, and the shearing roller 35 is applied to the rising portion 23 to shear the excess portion of the rising portion 23.

FIG. 9 shows the hole drilling process performed after the belt passing portion shaping process. That is, the upper and lower sides of the sheet metal material 10 are pressed by respective presser dies 36, 37, 38, and 39, and the sheet metal material 1 is
In the bearing No. 0, a hole 41 around the shaft is bored on the upper surface of the fitting part 14 by a shearing die 40, and a hole 41 for a rivet is made between the fitting part 14 and the rising part 23 by a shearing die 42. A hole 43 is drilled.

FIG. 10 shows the bearing fitting process which is carried out after this hole drilling process. That is, the sheet metal material 10 constructed as described above is inverted, the bearing presses the horizontal surface of the fitting part 14 with the holding die 44, and the ball bearing 3 is press-fitted into the fitting part 14 with the press-fitting die 45.

In order to prevent deformation of the sheet metal material 10 that occurs during this press-fitting, a presser die 46 is used to press the sheet metal material 10 from the outside.

FIG. 11 shows a bearing holding process performed after the bearing fitting process. That is, the hole 4a corresponds to the hole 43 for the rivet.
The annular bearing with a hole in it is connected to the holding plate 4, and the bearing is connected to the fitting part 14.
Attach the rivet 4 through the opening of each person 4a and 43.
Insert 8. After that, the upper and lower sides of this sheet metal material 10 are held down by respective presser dies 49°50.51, and the rivet driving die 52
By pressing while rotating, the head of the rivet 48 is crushed and the bearing is fixed to the holding plate 4, thereby fixing the ball bearing 3 in the fitting part 14.

(Effects of the Invention) As explained above, according to the present invention, in the folded part forming process, the raised part is hammered in the opposite direction to the rising direction to form the folded part at the base of the raised part. The sheet metal back idler pulley is formed while being compressed, and the thin walled portion is prevented from being formed as in the conventional case, which has the advantage of improving the strength of the sheet metal rear idler pulley and extending its life.

[Brief explanation of the drawing]

1 to 11 show an embodiment of the method for manufacturing a sheet metal rear idler pulley according to the present invention, FIG. 1 is a perspective view of the idler pulley, FIG. 2 is an assembled perspective view of the idler pulley, Figures 3 to 11 are cross-sectional views showing the idle pulley manufacturing process. Figure 3 is a tentative process diagram of the fitting part forming process for the bearing, and Figure 4 is the main process diagram of the bearing fitting part forming process. , Fig. 5 is a process diagram for forming the belt spanning part, Fig. 6 is a process diagram for forming the folded part, Fig. 7 is a process diagram for achieving accuracy in the belt passing part shaping process, and Fig. 8 is a diagram of the belt passing part shaping process. The trimming process diagram is shown in FIG. 9, the hole drilling process diagram is shown in FIG. 9, the bearing fitting process diagram is shown in FIG. 10, and the bearing pressing process diagram is shown in FIG. 11. In the diagram, 1...Idle pulley, 3...Ball bearing, 1
0...Sheet metal material, 14...Bearing is a fitting part, 23...
- Rising part, 23a...base, 29...folding part. Patent applicant Sanden Corporation

Claims (1)

[Claims] A bearing fitting part forming step in which the center of a sheet metal material is drawn to form a bearing fitting part, and after the bearing fitting part forming step, the outside of the fitting part is reverse drawn. a belt spanning part forming step in which the peripheral edge of the sheet metal material is made to stand up and a belt passing part is formed in this rising part; and after the belt passing part forming process, the rising part is formed in a direction opposite to the rising direction a folded part forming step of forming a folded part at the base of the rising portion; and a bearing fitting step of fitting the bearing to the fitting part after the folded part forming step. Manufacturing method of sheet metal back idler pulley.