JPH0557051B2 - - Google Patents

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) Idle pulleys conventionally used in vehicles, etc. are generally formed by casting or forging, but when formed by casting, the weight increases, and it is also difficult to form by forging. At the time, cutting work was required to ensure precision after forging, which led to an increase in cost.

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 forms 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 that acts on the base of the rising part is large, and this
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 something I couldn't do.

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 provides a bearing fitting part forming step in which a bearing fitting part is formed by drawing the center of a sheet metal material, and a bearing fitting part forming process. After the step, the outer side of the fitting part is reverse drawn to raise the peripheral edge of the sheet metal material, and a belt spanning part forming step is formed in which a belt spanning part is formed in this rising part, and the belt spanning part forming step is performed. After that, a folded portion 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 portion forming step, the bearing is fitted into the fitting portion. and a bearing fitting process.

(Function) According to the present invention, in the folded portion forming process, the raised portion is hammered in the opposite direction to the rising direction to form the folded portion at the base of the raised 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 rear idler pulley 1 is composed of a pulley body 2, a ball bearing 3, and a bearing holding plate 4. A ball bearing 3 is press-fitted into the pulley body 2, and the press-fitted ball bearing 3 is fixed within the pulley body 2 by the bearing presser plate 4 with rivets 48.

3 to 11 are cross-sectional views showing the idle pulley manufacturing process, and FIGS. 3 and 4 show the bearing fitting part forming process. That is, as shown in FIG. 3, the flat sheet metal material 10 except for the central 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 bearing fitting part 14 is temporarily formed inside this bulged part.

After this preliminary forming, as shown in FIG. This sheet metal material 10 is narrowed down to form the bearing fitting portion 14.

FIG. 5 shows a belt spanning part forming process performed after this bearing fitting part forming process. That is, the upper and lower surfaces of the center of the sheet metal material 10 are pressed by pressing dies 19 and 20.
At the same time, the sheet metal material 10 is supported by a presser die 21 having a recess in a part of the lower surface of the circumferential side of the sheet metal material 10, and is drawn toward the presser die 21 by a drawing die 22a from above and a drawing die 22b from below. form. 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 peripheral surface of the sheet metal material 10 are supported by the presser die 25 having the folded grooves 24, and the sheet metal material 1
The upper surface side of 0 is pressed by each of the presser dies 26 and 27.
In this state, the upper end of the rising part 23 is struck in the opposite direction to the rising direction, that is, in a downward direction, by the striking die 28 that moves downward between the presser dies 26 and 27, and is turned 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 the folded portion 29 is not formed by drawing, a sufficient plate thickness is ensured without the folded portion 29 becoming thin. Also,
This process aligns the center of the idle 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 press dies 30, 31,
31, the sheet metal material 10 is rotated, and a shaping roller 32 is applied to the outer surface of the rising portion 23 to ensure accuracy in the thickness of the belt-crossing portion.

After achieving this precision, 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 of the sheet metal material 10, so that the sheet metal material 10 is The excess portion of section 23 is sheared.

FIG. 9 shows the hole-drilling step performed after the belt-hanging portion shaping step. That is, the upper and lower sides of the sheet metal material 10 are held down by respective holding dies 36, 37, 38, and 39, and a hole 41 for the shaft is bored in the upper surface of the bearing fitting part 14 of the sheet metal material 10 by the shearing die 40, and, A hole 43 for a rivet is bored between the bearing fitting part 14 and the rising part 23 using a shear die 42.

FIG. 10 shows the bearing fitting process performed after this hole drilling process. That is, the sheet metal material 10 constructed as described above is inverted, the horizontal surface of the bearing fitting part 14 is pressed by the holding die 44, and the ball bearing 3 is press-fitted into the bearing fitting part 14 by 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 annular bearing holding plate 4 in which holes 4a are bored corresponding to the rivet holes 43 is attached to the opening of the bearing fitting part 14, and each hole 4 is
Insert the rivet 48 through a and 43. After that, the upper and lower parts of this sheet metal material 10 are held by the respective presser dies 49 and 5.
0 and 51, and by rotating and pressing the riveting die 52, the head of the rivet 48 is crushed and fixed to the bearing presser plate 4, thereby fixing the ball bearing 3 in the bearing 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, which prevents the problem of thin parts being formed as in the past, which improves the strength of the sheet metal rear idler pulley.
It has the advantage of long life.

[Brief explanation of drawings]

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, 3 to 11 are cross-sectional views showing the idle pulley manufacturing process, and FIG. 3 is a tentative process diagram of the bearing fitting part forming process.
Figure 4 is the main process diagram of the bearing fitting part forming process, Figure 5
Figure 6 is a diagram of the forming process of the belt running part, Figure 6 is a diagram of the folding part forming process, Figure 7 is a diagram of the process for achieving precision in the shaping process of the belt running part, and Figure 8 is a diagram of the trimming process of the shaping process of the belt running part. , Figure 9 is a diagram of the drilling process, Figure 10 is a diagram of the bearing fitting process, and Figure 11 is a diagram of the bearing fitting process.
The figure is a diagram of the bearing presser process. In the figure, 1...Idle pulley, 3...Ball bearing, 10...Sheet metal material, 14...Bearing fitting part,
23...Rising portion, 23a...Base, 29...
...Folding section.

Claims (1)

[Claims] 1. A bearing fitting part forming step in which a bearing fitting part is formed by drawing the center of a sheet metal material, and after the bearing fitting part forming process, the outside of the fitting part is reversed. a belt spanning part forming step in which the peripheral edge of the sheet metal material is made to stand up by squeezing 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 the opposite direction to the rising direction; A folded part forming step of forming a folded part at the base of the rising part by hammering in a direction, and a bearing fitting step of fitting the bearing to the fitting part after the folded part forming step. A manufacturing method for a sheet metal back idler pulley.