JPH0260405B2 - - Google Patents

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention is applicable to thin-walled metal materials such as the casing of the select lever (lever for operating the automatic transmission for parking, reverse, drive, etc.) of automatic transmission automobiles. The present invention relates to a method for forming a rectangular cylinder with rounded corners.

"Prior art" The casing of the select lever described above is
It is made of a thin metal material such as SUS301 (JIS symbol), has a hollow part in which the lever rod is built in, and has a rectangular cross section with four rounded corners. Both end edges of the cylindrical body are formed with protrusions and notches for attachment to a mating member.

The casing of the select lever characterized by the above shape uses a circular tube material having a circumferential length equal to the transverse outer circumference length of the rounded square cylinder after molding, and presses the outer periphery of the circular tube material to create a square shape with rounded corners. A molding method is employed in which the shape of the cylindrical body is changed from a cylindrical body to a rectangular cylinder with rounded corners.

"Problems to be Solved by the Invention" The conventional method for forming a rectangular cylinder with rounded corners is as follows:
Since it is characterized by a shape changing means by pressing the cylindrical body, it is not possible to insert a core metal of a size corresponding to the hollow part of the square cylinder with rounded corners to be formed into the hollow part of the cylindrical body and press it. Therefore, it is unavoidable that wrinkles, undulations, uneven surfaces, etc. will occur on the peripheral wall after molding, resulting in poor appearance and problems in molding quality that require a considerable dimensional tolerance. . When providing protrusions, notches, etc. on both end edges of the square cylinder with rounded corners, it is necessary to perform secondary processing on the square cylinder with rounded corners after forming, and form them individually. There is a problem with poor moldability.

It is an object of the present invention to provide a new molding method that overcomes the drawbacks of the above-mentioned conventional techniques.

``Means for Solving the Problems'' The forming method of the present invention that achieves the above-mentioned object is ``Means for forming corner circles of a thin metal material having four corners from the first corner to the fourth corner on the cross section. In forming the square cylinder, the expansion plate of the square cylinder with rounded corners is punched out from a plate material, and the left and right side edges of the expansion plate are joined to form a curved part that becomes the first corner. and then bending the expansion plate into a groove shape to form a second corner and a fourth corner adjacent to the first corner; A third corner is formed between the male and female molds by a mating mold, and two surfaces sandwiching the third corner are reversely curved to form a substantially rounded square cylinder. Then, the first corner is joined by the restoring reaction force of the reversely warped surface to form a rectangular cylinder with rounded corners.

"Operation" According to the above-described molding method of the present invention, a spread plate is punched out from a plate material to form a second corner and a fourth corner,
At the same time as the third corner is formed by the female and male molds, a reversely curved surface is provided, and by utilizing the restoring reaction force of the reversely curved surface, the side edges of the expansion plate are joined to form the first corner. There are no wrinkles, waves, or uneven surfaces, and rectangular cylinders with rounded corners can be formed with accurate dimensions.

"Example" Hereinafter, a detailed explanation will be given with reference to an example. With reference to FIGS. 1 and 2 showing one embodiment of the present invention, the figures are
Square cylinder with rounded corners and rectangular cross section of 16 mm x 22 mm made of SUS301 (JIS symbol) 0.5 mm thick stainless steel plate material 1
The method of molding the select lever of the automatic transmission automobile shown in FIG. 1E is shown. The molding procedure will be explained below.

- First, a development plate 2 in the developed shape of the rectangular cylinder 1 with rounded corners to be formed, as shown in Fig. 1E, is formed by punching from a plate material as shown in Fig. 1A, and at the same time as the punching process, Projections 3 and notches 4 to be formed at both end portions of a square cylinder 1 are formed by punching.

- Then, as shown in Fig. 1B, the left and right side edges 5A5B of the expansion plate 2 are pressed, and the side edges 5A5B
When joined, the first corner 6 of the rounded square cylinder 1
Each half of the curved portion 10 having a rounded shape is formed.

●Subsequently, as shown in FIG. 1C, the expansion plate 2 is bent into a groove shape by press working, and the second corner 7 and fourth corner 9 adjacent to the first corner 6 are rounded. Form.

●Next, as shown in FIG. Place the male die 11 between the press ram 13 and the press ram 13.
to form a rounded third corner 8 between the second corner 7 and the fourth corner 9, and the two surfaces sandwiching the third corner 8 form the third corner. Part 8
A reversely curved surface 15 is formed and recessed inward of the connecting line 14 connecting the vertices of the second corner 7, the third corner, and the fourth corner 9, and between the side edges 5A5B that will become the first corner. A substantially square cylinder 1' with rounded corners is formed in which a gap C remains.

After that, the press ram 13 is raised to remove the pressing force from the square cylinder 1' with rounded corners as shown in Fig. 2B, and the restoring reaction force of the reversely warped surface 15 creates a gap C as shown in Fig. 2B. is closed to form a first corner 6, and has a rounded corner rectangular cylinder 1 having a first corner 6, a second corner 7, a third corner 8, and a fourth corner 9 on its cross section.
to form. Then, the first corner portion 6 is welded.
In addition, the male die 11 is held at both ends that correspond to the outside of the expansion plate 2, and after the completion of forming the square cylinder 1 with rounded corners,
Pull it out to the side.

In the above forming method, the amount of warpage of the reversely warped surface 15 and the press-forming angle of the third corner 8 due to the pressure of the male die 11 are determined by the amount of plastic deformation due to the restoring reaction force of the reversely warped surface 15 and the amount of plastic deformation of the third corner 8 due to the pressure of the male die 11. The plastic restoring angle of the first corner 6 is quantitatively determined in advance in accordance with the unique circumstances of the rounded-corner rectangular cylinder 1 to be formed, and the first corner 6 is At the same time, the four right-angled corners 6, 7, 8, and 9 are made flat and parallel to each other to form a rectangular cylindrical body 1 with rounded corners.

On the other hand, the press ram 13 that presses the male die 11 is
Immediately before the above-mentioned restoring force acts, it is possible to avoid rising from the gap C between the side edges 5A and 5B,
It does not interfere with the proximity joining action of the side edges 5A5B.

According to the forming method of the above embodiment, after punching out the expansion plate 2 from the plate material and bending the second corner 7 and the fourth corner 9, at the same time as forming the third corner 8, A reversely curved surface 15 is formed on the clamping surface of the third corner 8, and the restoring force of the reversely curved surface 15 causes the expansion plate 2 to
Since the edges 5A and 5B are joined to form the first corner 6, there is no risk of "wrinkles", "undulations", etc. occurring in the molded peripheral wall portion causing the shape to collapse, and the molded peripheral wall has accurate dimensions and shape. A high quality rectangular cylinder 1 with rounded corners is molded.

Furthermore, since the protrusions 3 and the notches 4 formed on both ends of the rounded square cylinder 1 can be formed at the same time as the expansion plate 2 is punched, there is no need for conventional secondary processing, and the rounded square cylinder 1 can be processed. It has the advantage of significantly improving performance.

"Effects of the Invention" As explained above, the method for forming a rectangular cylinder with rounded corners according to the present invention has an excellent effect of significantly improving the molding quality and molding productivity of a rectangular cylinder with rounded corners.

[Brief explanation of the drawing]

Figure 1: Shows a method for forming a rectangular cylinder with rounded corners according to an embodiment of the present invention, A, B, C, and D are front views showing the forming procedure, and E is a perspective view showing the rectangular cylinder with rounded corners after molding. FIGS. 2A and 2B: Enlarged front views showing forming means for forming a substantially square cylinder with rounded corners into a square cylinder with rounded corners in the first illustrated embodiment. Main symbols: 1: Square cylinder with rounded corners, 1': Square cylinder with rounded corners, 2: Expandable plate, 3: Protrusion, 4: Notch, 5
A, 5B: side edge, 6: first corner, 7: second corner,
8: Third corner, 9: Fourth corner, 10: Curved part, 1
1: male type, 12: female type, 13: press ram, 1
4: Connection line between vertices, 15: Reverse warp surface.

Claims (1)

[Claims] 1. In forming a rectangular cylinder with rounded corners of thin metal material having four corners from the first corner to the fourth corner on the cross section, punching and forming a development plate of the rectangular cylinder with rounded corners, A curved portion is formed on the side edge by joining the left and right side edges of the expansion plate to form a first corner, and then the expansion plate is bent into a groove shape to be adjacent to the first corner. A second corner and a fourth corner are formed between the second corner and the fourth corner, and a third corner is formed between the second corner and the fourth corner by a mating mold of the male and female molds. The two faces sandwiching the third corner are reversely curved to form a substantially rounded rectangular cylinder, and then the first corner is joined by the restoring reaction force of the reversely curved surface to form a rounded corner. A method for forming a rectangular cylinder with rounded corners, characterized by forming a rectangular cylinder.