JPH0334409B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a panel flange forming method,
In particular, the present invention relates to a method of forming a flange on a panel while pushing a sectional die along the mold surface of a punch.

[Conventional technology]

Conventionally, for example, as shown in FIG. 5, there is a method of forming a flange 3 provided substantially perpendicularly to a waist portion 2 in an automobile door outer panel 1.
In this method, as shown in FIGS. 6 to 8, a panel (hereinafter referred to as "work W") that has been bent into a predetermined shape is formed using a press mold P.

This work W includes a draw process, a trimming process,
It is formed into a predetermined shape through a preliminary bending process.
Now, focusing on the forming part of the flange 3, the flange forming part 4 of the workpiece W is formed to be substantially flush with the waist part 2, as shown in FIG. 6, and this is due to the drawing process. The flange molded part 4a is molded, and in the trimming process, the wrinkle presser part 5 on the outside of the flange molded part 4a is cut (dotted chain line X in the figure).
This flange formed portion 4a is bent (in the Y direction in the figure) in a preliminary bending process.

Further, in the press die P, for example, as shown in FIG. The cam driver 13 of the upper holder 12
to press the sky cam 11 and push the sectional die 10 toward the punch 9.
In addition, the reference numeral 14 is a pad that is attached to the upper holder 12 via a spring 15 and presses and fixes the work W on the punch 9, the reference numeral 16 is a movable nest that is moved by an air cylinder 17, and the reference numerals 18 and 19 are the upper and lower holders 12. , 8 are the rams and bolsters respectively attached.

As shown in FIG. 8, this press die P bends and forms the flange 3 while aligning the flange forming portion 4 of the workpiece W along the die surface 9a of the punch 9 using the sectional die 10.

[Problem that the invention seeks to solve]

However, the conventional method has a problem in that the accuracy of the door outer panel 1 is low. This is because, as shown in FIG. 9, the flange 3 is positioned outward from the predetermined bending position Z due to spring back.

Therefore, the technical problem of the present invention is to set the flange 3 at a predetermined bending position even if spring back occurs.

[Means for solving problems]

A technical means for solving such problems is to provide a bending process in which a step part facing the die side is bent at the middle part of the flange forming part of the panel as a pre-process to the flange forming process using a die, During the flange forming step, the stepped portion is worked while being squeezed by the die.

〔Example〕

In the embodiment of the present invention, as shown in FIG. 1, in the draw process corresponding to FIG. 6 shown in the conventional example, a stepped portion 21 is simultaneously formed on the flange forming portion 20a ( (double-dashed line in the figure).
In this embodiment, the stepped portion 21 has a rising portion 22.
The dimension L1 is set to be smaller than the dimension L2 between DC (L1<L2 )are doing.

Therefore, according to the molding process using the press die P,
First, a bending process is performed between AB as in the conventional method. Next, the BD gap (rising portion 22) is pressed and bent toward the mold surface 9a of the punch 9 while being squeezed. In this case, as shown in FIG. 2, at the beginning of the advance of the sectional die 10, a resistance moment M1 occurs in the anti-bending direction at the inside line B, and as the sectional die 10 advances further, the edge edge C receives a resistance force F from the mold surface 9a, and a resistance moment M2 is generated at the outer line D in the direction opposite to bending. Therefore, the degree of straining between the BDs becomes large, and the rising portion 22 (between the BDs) becomes stretch-molded.

In addition, in this case, for the flange 3 of a predetermined width,
The dimension L2 between DC is set longer than the dimension L1 between BD (L1<L2), so that the edge C can easily come into contact with the mold surface 9a of the punch 9. Therefore,
Since the area between BD is subjected to the action of the resistance force F and the resistance moment M2 at an early stage of ironing by the sectional die 10, the efficiency is high.

Thereafter, the outer line D is stretched by the sectional die 10.

Fig. 4 shows the state of the flange 3 in an exaggerated manner.
Since the elongation is large on the outside, the rising part 2
2 (between BD) will try to bend in the bending direction (T direction in the figure), so it will resist springback and will be located outward from the predetermined bending position Z of flange 3. The situation is prevented.

Furthermore, since the space between DCs is relatively bent in the bending direction of the flange 3 during the drawing process,
During this time, the spring is generated mainly on the bending direction side, and this also prevents the flange 3 from shifting outward.

〔Effect of the invention〕

As explained above, according to the panel flange forming method according to the present invention, it is possible to stretch-form the step part in particular to give the opposite warp to counter spring back, so the flange can be formed into a predetermined shape. Can be set in a bent position.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the shape of a flange molded part according to an embodiment of the present invention together with its molding process, and FIGS. 2 and 3 show a molding process of a step part using a press die according to an embodiment of the present invention. 4 is a sectional view showing the state of a flange molded according to an embodiment of the present invention, and FIG. 5 is a partially cutaway perspective view showing an automobile door outer panel molded according to the present invention. , Fig. 6 is a sectional view showing a conventional flange forming part along with its forming process, Fig. 7 is a schematic diagram showing an example of a press die used for forming the flange, and Fig. 8 shows the state of the conventional flange forming process. The sectional view shown in FIG. 9 is a sectional view showing the state of a flange formed by a conventional method. W...Work (panel), P...Press mold, 3...Flange, 4, 20...Flange forming part, 21...Step part.

Claims (1)

[Claims] 1. In a forming method in which a flange is formed on a panel while pushing a die along the mold surface of a punch, as a pre-step of the flange forming process using the die,
A bending process is provided in the middle part of the flange forming part of the panel to bend and form a step part facing the die side,
A method for forming a flange on a panel, characterized in that during the flange forming step, the stepped portion is worked while being squeezed by the die.