JPH02280928A - Hemming method - Google Patents

Abstract

PURPOSE:To form an extremely thick end part having a hollow closed section structure with the minimum number of stages by wiring a bent line preventiously in the central part in the direction of a flange length of the position to make a hemmed flange part. CONSTITUTION:When an outer panel P1 is pressed by an insert punch 1 and a pad 2, the bent line (m) is wired previously at the position to make the hemmed flange part F. The hemmed flange part F is restricted between a prehemming die and a slide cam at a prehemming stages and bent from a bent line (m). The bent line (m) is a part which is locally small in thickness and easy to bend and the hemmed flange part F is bent smoothly from the bent line (m) and hemmed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a hemming method for edge-bending the edges of a panel-shaped workpiece, and more specifically, it relates to a hemming method for edge-bending the edges of a panel-shaped workpiece. The present invention relates to a method of forming an extremely thick end portion with a cross-sectional structure.

BACKGROUND OF THE INVENTION Panel parts such as automobile hoods or trunk lids are generally constructed by hemming an outer panel and an inner panel together. In such a hemming process, as shown in FIG. 11, the hemming flange F of the outer panel P is folded back until it becomes flat on the inner panel P side, and the outer panel P1 and the inner panel P are hemmed together. Although it is usual, instead of this structure, for example, as shown in FIG. 12, both panels P,
In order to ensure the face value dimension t relative to the plate thickness of , P, as large as possible, a very thick terminal part Q having a hollow closed cross-sectional structure is formed at the base of the hemming flange part F (for example, in Japanese Patent Laid-Open No. 60 (Refer to Publication No.-210327).

The hemming method for forming the extremely thick end portion Q is to form the outer panel P through a trimming process as shown in FIGS. 13(A), (B), (C), and (D).

A hemming flange part F is bent and formed on the end of the (first
3(A)), as a preliminary bending step, the base of the hemming flange portion F is preformed into a semicircular shape as shown in FIG. 13(B). Furthermore, in the brihemming process, Fig. 13 (C)
As shown in Fig. 13(D), the hemming flange part F is folded back to about 45 degrees, and at the same time, the terminal part Q approaches from a semicircular shape to a cylindrical shape. The tip of F is the inner panel P
By folding it back until it is seated on , the end portion Q is finished into a hollow cylindrical shape.

Problems to be Solved by the Invention In the hemming method for forming the extremely thick end portion Q as described above, the first hemming process is performed prior to the pre-hemming process.
Preliminary bending as shown in Figure 3 (B) is required, which increases the number of processing steps and increases costs.
In particular, in the above-mentioned hemming method, the shape of the terminal part Q is special compared to the general hemming process shown in FIG. Even so, it results in a significant increase in cost, which is undesirable.

The present invention has been made in view of the above points, and its purpose is to create an extremely thick end portion while requiring the same number of processing steps as the general hemming method shown in Fig. 11. An object of the present invention is to provide a hemming method that allows a shape to be obtained.

Means for Solving the Problems According to the present invention, as described above, an extremely thick end portion having a hollow closed cross-sectional structure is formed at the end portion of a panel-shaped workpiece by applying edge bending to the end portion of the workpiece. In the hemming process, there is a trimming process in which the workpiece is trimmed into a predetermined contour shape using a trim press die, and the edge of the workpiece that has undergone the trimming process is bent at almost right angles using a flange die to form a hemming flange. a flange bending step of forming a seating flange by bending the tip end of the flange obliquely in a direction opposite to the bending direction of the hemming flange, and a center in the flange height direction of the portion to become the hemming flange. a stamping step in which the hemming flange portion is locally stamped in the plate thickness direction to simultaneously form a folding line in the trim step or the flange bending step; a pre-hemming step in which the hemming flange portion is folded from the folding line using a pre-hemming press die; The method includes a hemming process in which the hemming flange portion is further folded back from the folding line using a hemming press die, and the seating flange portion is directly or indirectly seated on the base work.

Function: According to this method, the folding line that is to be an easy-to-bend part is trimmed or stamped at the same time as the flange bending process. The desired extremely thick end shape can be obtained with fewer machining steps.

Embodiment FIG. 1 is an explanatory diagram showing an embodiment of the present invention, and shows changes in the shape of an outer panel P as a workpiece.

The non-product area S attached to the outer panel P1 drawn in the previous process is trimmed from the trim line Q in the trim process shown in (A) and (B) in the same figure.
), the end of the outer panel P1 is bent at a substantially right angle to form the hemming flange F, and at the same time, the tip of the hemming flange F is bent over the outer panel P1.
The seating flange portion Fa is formed by bending the hemming flange portion F obliquely in a direction opposite to the bending direction of the hemming flange portion F relative to the hemming flange portion F. By the end of this flange bending process, a bending line m, which is an easy-to-bend part, is formed approximately at the center of the hemming flange part F.

In the pre-hemming process shown in FIG.
, is placed on top of the outer panel P, and the hemming flange portion F is folded back to about 45 degrees from the folding line m. Furthermore, in the hemming process following the pre-hemming process, the hemming flange F is further folded back to bring the seating flange Fa into close contact with the inner panel P, as shown in FIG. Extremely thick terminal part Q with hollow closed cross-section structure at the same time as hemming connection
, is formed.

Next, the details of each of the above steps will be explained step by step. For example, as shown in FIG.
1 is restrained by the pad 2, and the non-product area S (Fig. 1 (A
). Then, an acute-angled printing pressure bead 4 is formed on the side of the insert punch L, and the insert punch 1 and pad 2 are used to press the outer panel Pl.
When pressurizing, a folding line m is formed in advance by pressure on a portion that will become a hemming flange portion F in a later process.

As shown in FIG. 3, this folding line m preferably has a groove angle θ of about 90 degrees and a depth e of about one third of the plate thickness.

In the flange bending process, as shown in FIG. 4, the outer panel P1 placed on the flange-type insert punch 5 is pressurized and restrained by the pad 6, and the end of the outer panel P1 is flanged down at an almost right angle with a diamond. A hemming flange portion F is formed. At this time, by forming the inclined surfaces 5a and 7a on the insert punch 5 and the diamond, the tip of the hemming flange portion F is relatively bent in a direction opposite to the flange bending direction to form the seating flange portion Fa. Ru.

In addition, if the folding line m is not formed in the trimming process shown in FIG. In the process of folding, a folding line m can be formed in the same manner as above. That is, the impression forming of the folding line m is performed simultaneously in the trim step of FIG. 2 or the 7-lunge bending step of FIG. 4.

In the pre-hemming step following the seven-lunge bending step, pre-hemming is performed using a press die for pre-heming shown in FIGS. 5 and 6. In addition to the punch 11, the lower holder 10 of the press mold is provided with a drive cam 12 having an inclined cam 12a and a brimming die 13.

The hemming die 13 can swing (rotate) around a hinge bin 14, and has a cam follower roller 15 attached to its upper end. On the other hand, a drive cam 17 and a pad 18 are attached to the upper holder 16, and this pad 18 is connected to a base plate 20 which is elastically supported by the upper holder 16 via a pad retainer 19 and urethane rubber 40 so as to be movable up and down, and this base plate 20 and a slide cam 21 attached to the slide cam 20 so as to be movable in the horizontal direction. The slide cam 21 has an inclined cam surface 21
a is formed.

In this pre-hemming process, first the hemming flange part ■
? The inner panel P, on which the flange portion Fb (see FIGS. 1D and 1E) is formed in advance, is placed on the outer panel P1 on which the flange portion Fb (see FIGS. 1D and 1E) is formed, and positioned on the punch II. Then, when the upper holder 16 is lowered, the drive cam 1
2 and the inclined cam surfaces 12a and 21a of the slide cam 21 come into sliding contact with each other (point R1 in FIG. 6), and the slide cam 21 slides in the direction of the arrow a1 against the force of a return spring (not shown). Then, the inclined cam surface 21 of the slide cam 21
Immediately before a comes off the inclined cam surface 12a on the drive cam 12 side, the pressure surface 21b of the slide cam 21 comes into contact with the inner panel P (point R1 in FIG. 6), and thereafter the pressure surface 21b
is the inner panel P.

continue to be restrained under pressure.

When the upper holder 16 continues to descend, the inclined cam 17a on the drive cam 17 side comes into contact with the cam follower roller 15 of the pre-hemming die I3 (point R in Fig. e), and the pre-hemming die 13 is rotationally displaced in the direction of arrow b1. do. As a result, the hemming flange portion F is restrained between the hemming die 13 and the slide cam 21 and bent from the bending line m, as shown in FIG. 1(D). At this time, inner panel P! The flange portion Fb functions as a core metal to prevent the hemming flange portion F from bending from its base, and the bending line m is an easy-to-bend portion where the plate thickness is locally reduced. Therefore, the hemming flange part F
is smoothly bent from folding line m and pre-hemmed.

Note that S in FIG. 6 indicates the vertical stroke of the pad 18, S indicates the stroke of the slide cam 21, and S3 indicates the stroke of the bridging die 13, respectively.

Furthermore, the above pre-hemming process can be similarly performed using the pre-hemming press molds shown in FIGS. 7 and 8. In this press type, as the upper holder 16 is processed, the outer panel 21 is pressed by the pad 22, and after this, the inclined cam surfaces 23 and 24 come into sliding contact with each other, and the slide cam 25 slides in the a1 direction in the figure. After the slide cam 25 presses both panels P, , P, the pre-hemming die 27 is operated by the drive cam 26, and pre-hemming is performed in the same manner as above.

Note that S4 indicates the stroke of the pad 22, SS indicates the stroke of the slide cam 25, and SS indicates the stroke of the bridging die 27, respectively.

In the hemming process, hemming is performed using a hemming press mold shown in FIGS. 9 and 10.

A drive cam 31 is attached to the punch 30 that serves as the lower die, and a pad 35 is elastically supported on the upper holder 32 so as to be movable up and down via a pad retainer 33 and uretashi rubber 34. A cam 36 is attached so as to be slidable in the horizontal direction.

When the upper holder 32 is lowered after positioning the prehemmed outer panel P on the punch 30, the pad 35 first comes into contact with the outer panel P and restrains it at point R4 in FIG. ), hemming cam 3
The pressure surface 37 of No. 6 is the seating flange portion Fa (FIG. 1 CD),
(Refer to (E)) When the inclined cam surface 31a of the drive cam 31 and the hemming cam 36 becomes lower than the tip of the hemming cam 36 by h dimension
.

36a slide into contact with each other (point R3 in FIG. 10). As the upper holder 32 continues to descend, the hemming cam 36 gradually moves horizontally, so that the hemming flange portion F including the seating flange portion Fa is further inner than the folding line m (see FIGS. 1(D) and (E)). Panel P is folded back to the side.

Then, the sliding contact between the inclined cam surfaces 31a and 36a is removed, and the drive cam 31 is replaced as shown in FIG.
When the vertical surfaces of the hemming cams 36 come into sliding contact with each other, the entire hemming flange portion F is folded in until the seating flange portion Fa comes into close contact with the inner panel P, and the first
As shown in Figure (E), the outer panel P and the inner panel P.

At the same time as the outer panel P1 is hemmed together, the outer panel P1
A terminal portion Q having a very thick hollow closed cross-sectional structure is formed at the end portion of. In addition, 87 in FIG. 10 indicates the stroke of the pad 35, and SS indicates the stroke of the hemming cam 36, respectively.

Effects of the Invention As described above, according to the present invention, in the trimming process or the flange bending process, a folding line is pre-printed at the central part in the length direction of the flange at the part that is to become the hemming flange part, so that the trimming process can be easily performed. process, flange bending process,
It becomes possible to form an extremely thick end portion with a hollow closed cross-sectional structure using a minimum number of steps such as a pre-hemming step and a hemming step, thereby reducing processing costs.

[Brief explanation of drawings]

Figure 1 (A), (B), (C), (D),
(E) is an explanatory diagram showing the shape change of the outer panel as an example of the present invention, Fig. 2 is an explanatory diagram of the trim process, Fig. 3 is an enlarged view of the main part of Fig. 2, and Fig. 4 is flange bending. FIG. 5 is a process explanatory diagram of the pre-hemming process; FIG. 6 is a stroke diagram of FIG. 5; FIG. 7 is a process explanatory diagram showing another example of the pre-hemming process; The figure is number 7
Figure 9 is a stroke diagram, Figure 9 is a process explanatory diagram of the hemming process, Figure 10 is a stroke diagram of Figure 9, and Figure 11 is an explanation showing a hemmed connection state by the most common conventional hemming method. FIG. 12 is an explanatory view showing another hemming connection state, and FIGS. 13(A) and (B). (C) and (D) are process explanatory diagrams of the hemming process for obtaining the hemmed bonded state of FIG. 12. 13.27... Pre-hemming die, 36... Hemming cam, F... Hemming flange part, Fa... 1 seat flange part, m... Bending line, PI... Outer panel as work, PR... Inner panel, Ql...
Terminal section. Outside 3 people Low -～- LLE(L(L0 ■ Part 13 Figure 13 (A) Figure 13 (C)

Claims (1)

[Claims] (1) In a hemming method in which an extremely thick end portion with a hollow closed cross-sectional structure is formed at the end of a panel-shaped workpiece by edge bending, the workpiece is fixed in a predetermined manner using a trim press die. A trimming step in which the end of the workpiece that has undergone the trimming step is bent at almost right angles using a flange mold to form a hemming flange, and at the same time, the tip of the hemming flange is folded into the hemming flange. A flange bending step in which the seating flange is formed by bending diagonally in a direction opposite to the bending direction; and a flange bending step in which the central portion of the flange in the height direction of the portion that is to become the hemming flange is locally pressed in the plate thickness direction. a printing pressure step of simultaneously forming a folding line in the trim process or the flange bending process; a pre-hemming process of folding the hemming flange portion from the folding line with a pre-hemming press die; and a pre-hemming process of folding the hemming flange portion from the folding line with a hemming press die. A hemming process characterized by comprising the steps of further folding back and seating the seating flange directly or indirectly on a base work.