JPH0739954A - Press forming method provided with countermeasure for preventing wrinkle and wrinkle preventing mechanism - Google Patents

Abstract

PURPOSE:To provide a press forming method provided with the countermeasure for preventing wrinkles generating in the early stage of a press forming and the growth of the wrinkles thereafter, even though a material to be formed is a medium thick plate and to provided a wrinkle preventing mechanism therefor. CONSTITUTION:A U-shaped block 14, in which a recessed part 13 is formed so as to hold the end part 10a of the part where a shrink flange forming is performed on a material 10 to be formed, is arranged freely rotatably at the set position of the end 10a on the surface of a die 3' through an arm 15. Therefore the die is simply and easily combined, and the block 14 is rotated by a prescribed angle in accordance with the forming of the material 10 while holding the end part 10a, so that the generation of wrinkles is prevented; and at the prescribed angle, the block 14 is automatically away from the material 10 and is returned to the original position to be ready for the next operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a press-molding method and a wrinkle-preventing mechanism provided with measures for preventing the generation of wrinkles.

[0002]

2. Description of the Related Art Generally, a large press-formed product made of medium-thick plate,
For example, a single-action press is used because a blank holder cannot be used in press molding of side members, cross members, and reinforcements (reinforcing members) that form a frame of a truck. In this case, as shown in FIG. 8, it is necessary to asymmetrically mold the molded article 1 from the predetermined location “a”, and the dies 2, 3 formed and arranged according to the shape of the molded article and the die 2, After being placed on the pad 4 which moves up and down between 3 and pressed by press 5 as shown in FIG. 9 by the punch 5 which is also formed in conformity with the shape of the molded product, it becomes shrink molding near the point "a". In the molded product 1 ′, wrinkles 6 are generated around the point “a” (FIG. 1).
0). This wrinkle becomes larger as the degree of asymmetry increases, and not only the appearance quality of the press-formed product deteriorates, but also when the wrinkle is large, the part becomes unstable when the part is attached to this part, which is sometimes dangerous. . Further, the dies 2, 3 and the punch 5 near the point “A” where wrinkles are generated are severely worn, and it is necessary to frequently inspect, maintain and repair them. The wrinkle 6 in the shrink forming by the single-action press as described above is shown in the die 2 or 3 at the final stage of the press forming process, that is, when the punch 5 finishes pressing the article 1 between the dies 2 and 3. It is known to squeeze strongly with a cam or the like.

[0003]

However, the fact that the product 1 is a thin plate and its wrinkles are relatively small in the press molding because the product is strongly pressed and crushed by a cam or the like at the final stage of the press molding process as described above. Although it is effective if it occurs after the progress, if the molded product 1 is a medium-thickness plate and its wrinkles are generated and grown in the initial stage of press molding, the pressing force by the cam or the like is increased. Has no effect. The present invention has been devised as a problem to solve the above problems,
To provide a press-molding method and a mechanism for preventing wrinkle formation, in which measures are taken to prevent the generation of wrinkles occurring in the initial stage of press-molding and prevent the growth of wrinkles thereafter, even if the product to be molded is a medium-thickness plate. To aim.

[0004]

In order to achieve the above-mentioned object, the press-molding method of the present invention provided with a wrinkle-preventing measure is such that the vicinity of the end of the portion where the shrink-flange molding of the molded product is carried out,
At least in the initial stage of molding, it is characterized by pressing after being sandwiched by a U-shaped block, and the wrinkle prevention mechanism of the present invention is formed with a recessed portion so as to sandwich the portion of the molded product where the shrink flange molding is performed. It is characterized in that the U-shaped block is rotatably disposed at a set position of a portion of the die surface portion where shrink-flange molding is performed on the die surface portion via an arm.

[0005]

[Operation] When using a die having the wrinkle prevention mechanism having the above-mentioned structure to press-form a molded product that needs to be asymmetrically molded from the predetermined location, first, mold the molded product on two dies and pads. Then, the end of the portion of the product to be molded, which is to be subjected to the shrink flange formation, is inserted into the concave portion of the U-shaped block of the holding tool. When pressed with a punch in this state and press-formed, the left and right sides of the product to be molded tend to undergo contraction molding, but the holding tool also rises when the arm rotates with the end part sandwiched. Until the molded product is bent at a predetermined angle, the end portion is held in the concave portion of the U-shaped block, and wrinkles are prevented from being generated in the initial stage of press molding.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to FIGS. 1 to 7, in which the same reference numerals as in FIG. First, the molded product 10 molded according to the present invention is also shown in FIG.
As described below, it is necessary to mold asymmetrically with respect to the center in the axial direction from the predetermined location "a", and the die 2 formed and arranged according to the shape of the molded product as shown in FIG.
3'and the pad 4, which moves up and down between the dies 2 and 3 ', is pressed by a punch 5 formed in conformity with the shape of the molded product and press-formed (FIGS. 2 and 3). The die 3'is provided with gripping tools 11 and 12 for gripping at least the vicinity of the end of the portion where the shrinkage flange molding is performed near "a" at the initial stage of molding.

That is, as shown in detail in FIGS. 5 to 7, each of the holding tools 11, 12 has a U-shaped block 1 in which a concave portion 13 is formed so as to sandwich the end portion of the molded article 1 with an appropriate gap.
4 is fixed to one end of the arm 15 by welding or the like, with the recess 13 facing you, and is attached to the mounting bracket 17 through the elongated hole 15a formed in the other end of the arm 15 and the pin 16 passed through the hole. It is movably attached. Although the length of the U-shaped block 14 is finally determined by an experiment or the like, it is set to substantially cover the portion where the wrinkles occur. Further, in particular, the material of the U-shaped block 14 is a carbon steel material for machine structure having a hardness higher than that of the frame material (rolled steel plate for automobile structure), and a molded product (frame material).
The wrinkles at 10 are suppressed.
By using the above material, the thickness s of the upper side of the concave portion 13 of the U-shaped block 14 is made as thin as possible, and the clearance 1 for the U-shaped block 14 formed on the side surface of the die 3 ′ is formed.
It is also possible to make 8 small.

As shown in FIGS. 2 and 6, the holding tools 11 and 12 as described above are set on the die 3'with the end 10a of the pre-molded article 10 on the side where shrink flange molding is performed. In the position, the recess 19 into which the U-shaped block 14, the arm 15 and the fitting 17 are fitted so that the arm 15 of the holding tools 11, 12 is at a right angle to the left and right of the “a” point. , 20 are formed on the die 3 ', and the fittings 17 are fitted and fixed flush with the recesses 20 on the opposite side surfaces of the dies 2, 3', in which case the U-shaped block 14 is shown in FIG. As shown, the concave portion 13 is set so as to be on the surface of the die 3 ', and thus the wrinkle prevention mechanism of the present invention is constructed.

Die 3'having a wrinkle prevention mechanism of the above construction
When press-molding a molded product 10 that needs to be asymmetrically molded from a predetermined location "a", first, mount the molded product 10 on the dies 2, 3'and the pad 4, and As shown in FIG. 6, the end portion 10 a of the molded product 10 near the “a” on which shrink flange formation is performed is formed into the recess 13 of the U-shaped block 14 of the holding tools 11 and 12.
Slip into. When pressed by the punch 5 in this state and press-molded, the right and left sides of the molded product 10 stand up and tend to undergo contractive molding near the point "a". The arm 15 rotates around the pin 16 and stands up while the part 10a is sandwiched, and the molded product 10 is bent by a predetermined angle (the state of FIG. 2 or the phantom line of FIG. 6) until that time. The end portion 10a is restrained in the concave portion 13 of the U-shaped block 14, and the wrinkle which tends to be generated on the left and right of the "a" point is prevented in the initial stage of press molding. After that, the press molding proceeds, and as shown in FIG. 3, by the time the molding is almost completed, the U-shaped block 1 is cut from the end 10a of the article 10 to be molded.
4 is removed, and the holding tools 11 and 12 are returned to their original positions. Molded product 10 '
Is completed with almost no wrinkles at the point "a" as shown in FIG.

Although not shown, the holding tool 1
In 1 and 12, the arm 14 is divided into two, and the arms 14 are connected by a joint rotatable about the axis of the arm 15. The U-shaped block 14 sandwiches the end portion 10a of the molding target 10. Even if the block 14 is twisted when press-molded in a bent state, no trouble occurs.

[0011]

As described above, the press-molding method provided with the wrinkle-preventing measures of the present invention includes a U-shaped block for covering the vicinity of the end of the shrink-flange-molded portion of the molded product, at least at the initial stage of molding. Since it is characterized by press-forming after that, it is necessary to form a medium-thickness plate to be molded asymmetrically from a predetermined location. In the initial stage, it can be pinched by the U-shaped block to suppress its occurrence and suppress its growth, not only improving the appearance quality of the press-formed product, but also making the part unstable when it is attached to the predetermined location. And the wear of the die and punch at the wrinkle-occurring point is small as in the prior art, and therefore, frequent inspection, maintenance and repair thereof are not required. Further, the wrinkle prevention mechanism of the present invention comprises a U-shaped block in which a recess is formed so as to sandwich the portion of the molded product where the shrinkable flange molding is performed, and the shrinkable flange molding of the molded product on the die surface part is performed via the arm. It is characterized in that it is rotatably disposed at the set position of the portion to be performed, so that it can be easily and easily incorporated into the die, and the end portion on the side where compression molding of the article to be molded is first performed is the concave portion. Simply slipping in to prevent the formation of wrinkles by turning while keeping the edges close to the specified angle according to the molding of the product to be molded. It is possible to return to the original position and prepare for the next work, improving work efficiency.

[Brief description of drawings]

FIG. 1 is a perspective view showing a set state of a main part of a press machine equipped with a wrinkle prevention mechanism and a product to be molded in a press molding method of the present invention.

FIG. 2 is a press state (intermediate) of a main part of a press machine equipped with a wrinkle prevention mechanism and a product to be molded in the press molding method of the present invention.
Perspective view showing

FIG. 3 shows a pressed state of a main part of a press machine equipped with a wrinkle prevention mechanism and a molded product in the press molding method of the present invention (final).
Perspective view showing

FIG. 4 is a perspective view of a molded product produced by the press molding method of the present invention.

FIG. 5 is a perspective view of a holding tool in the wrinkle prevention mechanism of the present invention.

6 is a cross-sectional view taken along the line AA of FIG. 7, showing a set state of a main part of a press machine equipped with a wrinkle prevention mechanism and a product to be molded in the press molding method of the present invention.

FIG. 7 is a plan view showing a set state of a main part of a press machine equipped with a wrinkle prevention mechanism and a product to be molded in the press molding method of the present invention.

FIG. 8 is a perspective view showing a set state of a main part of a press machine and a molded product in a conventional press molding method.

FIG. 9 is a perspective view showing a main part of a press machine and a pressed state (intermediate) of a molded product in a conventional press molding method.

FIG. 10 is a perspective view of a molded product by a conventional press molding method. 1 molded product (conventional) 1'molded product (conventional) 2 die 3 die (conventional) 3'die 4 pad 5 punch 6 wrinkle 10 molded product 10a Shrinkage of molded product End part on the side where flange forming is performed 10 'Molded product 11 Clamping tool 12 Clamping tool 13 Recessed portion 14 U-shaped block 15 Arm 16 pin 17 Mounting bracket 18 Relief 19 Recessed portion 20 Recessed portion.

Claims (2)

[Claims] 1. A wrinkle-preventing press characterized by press-molding at least in the vicinity of an end portion of a product to be shrunk-flange-molded by a U-shaped block at least in the initial stage of molding. Molding method. 2. A U-shaped block having a recess formed so as to sandwich a portion of a molded product to be subjected to shrink flange forming, and a portion of the die surface portion to be subjected to shrink flange forming of the molded product via an arm. A wrinkle prevention mechanism characterized by being rotatably disposed at the set position of.