JPS6032898Y2 - Press mold for long items - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a press mold for forming a long object, particularly a long object curved not only in the width direction but also in the longitudinal direction.

A press mold as described above is required, for example, when molding a bumper for a vehicle.

However, this type of bottom shape is special and therefore poses a difficult problem.

In other words, both edges of the material remain free (unrestrained).
If molding is performed using this method, wrinkles will appear in the product.

Therefore, it has been conventional practice to use a wrinkle presser to bring the punch closer to the die while restraining both edges of the material, and it has been considered essential to do so.

However, in this case, a groove-like dent called a shock line occurs at the part where the corner of the die or punch first comes into contact, making the product defective.

Furthermore, in order to restrain both sides of the material, a material much larger than that required for the product is required, resulting in a decrease in material yield, and moreover, the central molded portion tends to be insufficient in thickness.

The present invention was made with the purpose of providing a press die that can satisfactorily eliminate the above-mentioned problems that occur during special molding, and the gist of the invention is to provide a press die with a ridge-like shape on the wrinkle pressing surface of the die. A leading block is provided between the die and the wrinkle pressing member, which has a protruding bead, and is capable of securing a gap greater than the thickness of the material between the tip end face of this bead and the wrinkle pressing member opposing it. It's what I did.

In this way, in the initial stage of forming, both edges of the material are curved into an appropriate cross-sectional shape and are held by the die and the wrinkle holding member, resulting in a semi-constrained state that is not completely constrained but not unconstrained. Since these conditions are distantly related, and the magnitude of this restraining force can be changed, the above-mentioned drawbacks that occur when fully restrained as well as the aforementioned drawbacks that occur when there is no restraint are eliminated.

Hereinafter, the present invention will be explained in more detail based on an embodiment in which a bumper for a vehicle is shaped as a bottom.

In FIG. 1, 1 is a die which also serves as an upper blank holder, 10 is a punch, and 20L and 20R are lower blank holders.

All of these have a longitudinal shape in a direction perpendicular to the plane of the drawing.

A concave surface 2 having a predetermined shape is formed at the center of the die 1 in the width direction (left and right direction in FIG. 1).

A pair of beads (projections) 3L and 3R having a trapezoidal cross section are protruded from both sides of the concave surface 2.

The lower surface of the die 1, including the beads 3L and 3R and the concave surface 2, is curved upward in the longitudinal direction.

The die 1 is fitted and fixed in a recess 7 of an upper die 6 which is provided to be movable up and down.

The punch 10 has a convex surface 1 having a shape corresponding to the concave surface 2 on the upper part.
1, and is fixed in the center of a recess 17 of a lower die 16 fixed on a bolster of the machine body.

Further, the lower blank holders 20L and 20R have cutouts 26L and 2 formed in their support members 25L and 25R.
6R and is provided facing both sides of the die 1 (upper blank holder), and R21L and 21R are formed in the inner upper corner in a shape corresponding to the beads 3L and 3R. has been done.

Lower blank holder 20L and 2OR and support member 2
5L and 25R are urged upward by springs or mechanical cushion pins (not shown), and are wrinkle pressing members 40L that work together with the die 1 to restrain both side edges of the material.
and 40R.

As shown in Figure 2, the bead 3L on the left in Figure 1
The height h is approximately 5 degrees, and the amount W of the difference between the inclined surfaces 7L is approximately 2rIr! It is n.

Also, between the lower surface 4L on the side of the bead 3L of the die 1 and the upper surface 22L of the lower blank holder 2OL, which is opposite to this, is fixed with the upper surface of the support member 25L.
Spacer (preceding block) 29 interposed between
A gap S determined by the height of L is secured.

This gap S can be changed by changing the height of the preceding block 29L, and here it is approximately 7 yrr.
It has been selected as m.

As a result, the corner of the bead 3L and the lower blank holder 20
The gap S' between the opposite corner of L is approximately 1.5 ribs.

This situation is caused by the beads 3R and R21R on the right in Figure 1.
The same applies to the preceding block 29R.

Next, Figure 3 shows the work of using this press mold to curve (shape) a long flat plate (material) with a thickness of 1.4 mm so that it is convex in the same direction in the width and length directions. I will explain while referring to it.

Upper die 6, die 1, lower blank holder 20L and 2
The material 30 is fed between the die 1 and the punch 10 with the 0R in the raised position.

After that, as the upper die 6 descends, the lower blank holder 20
L and 20R descend while maintaining a gap S (7 mm) between them and the die 1 by the preceding blocks 29L and 29R.

Lower blank holder 20L and 20R have punch convex surface 1
In the initial stage of forming, when the material 30 is slightly lower than the corner 13 of 1, the middle part of the material 30 is slightly bulged upward as shown in FIG. 21R, it is in a downwardly curved state.

That is, a moderate frictional force acts between both side edges of the material 30 and the beads 3L and 3R, resulting in a semi-restricted state.

Dice 1 and lower blank holders 20L and 20R
After further descending, the corner 1 is lowered as shown in the figure.
3 enters into the center of the die concave surface 2, the corner 13 and the corner 4 of the die concave surface 2 come to be strongly pressed against the material 30, but a shock line is generated at the part where the corner 4 is strongly pressed. There isn't.

This is because both side edges of the material 30 are in a semi-restricted state, and a large tensile force does not act on the portion of the material 30 between the bead 3L and the corner 13.

Dice 1 and lower blank holders 20L and 20R
continues to descend, and as shown in FIG.
As the material 30 approaches the corner 5 facing the die concave surface 2, both side edges of the material 30 slide inward (towards the middle).

The sliding resistance at this time is appropriately adjusted by selecting the dimensions of the beads 3L and 3R and the heights of the leading blocks 29L and 29R, so that a sufficient plate thickness is secured in the center part in the width direction. No wrinkles will occur.

Then, as shown in Figure d, the bottom of the material 30 is shaped into a predetermined cross-sectional shape.

In this state, most of the materials are dice 1 and punch 10.
The finished product is sandwiched between the two edges, and only the width necessary for trimming in the subsequent process remains on both edges.

In this way, as shown in FIG. 6, a product (bumper) 30' is obtained which is curved in the shape of a mountain in the thickness direction in the longitudinal direction and is also formed into a predetermined cross-sectional shape in the width direction.

The lower surface 4L of the die 1 and the lower blank holder 20L
The case has been described in which the gap S with the upper surface 22L is set to 7 mm, but this gap S is determined as follows.

In other words, since this gap S is determined by the heights of the preceding blocks 29L and 29R, a plurality of preceding blocks with different heights are prepared in advance, and trial shots are performed by replacing them one after another. The gap S in which both lines and wrinkles are least likely to occur was determined.

The incidence of shock lines and wrinkles when the gap S is changed in this manner is shown in FIGS. 4 and 5, respectively.

What is clear from FIG. 4 is that when the height h of the beads 3L and 3R is 5 mm, the above-mentioned gap S is within the range of 4 to 15 mm, especially when the height h is slightly larger than the height of the beads 3L and 3R. This means that there are fewer shock lines in the 10mm range.

On the other hand, according to FIG. 5, wrinkles occur when the gap S is 1o.
This does not occur when the temperature is below Nn, but after this the gap S
It gradually increases as it gets bigger.

This is a fully acceptable result since the smaller the gap S is, the closer the state is to a fully constrained state, and conversely, the larger the gap S is, the closer the state is to an unconstrained state.

The gap S is determined based not only on preventing the formation of the shock line described above but also on suppressing the generation of wrinkles, but if the gap S is about 15 degrees or less, wrinkles will not occur. Relatively few.

Therefore, it is desirable to select the gap S to be about 4 to 15 meters, and particularly preferably to about 6 to 10717 meters.

In this way, the forming that is the subject of this invention is a delicate process that can be said to be a bending process that includes elements of a drawing process, or a drawing process that is close to a bending process, and therefore it is difficult to analyze the occurrence of shock lines and wrinkles. However, by continuously changing the gap S in relation to the beads 3L and 3R, it was possible to realize the most ideal press mold.

It goes without saying that the height and width of the bead, the depth and width of the groove, etc. should be changed as appropriate depending on the shape of the punch and die and the thickness of the material.

Further, the shapes and dimensions of the left and right beads and the gap between them and the grooves may be made different.

In addition, as shown in FIG. 7, there is a product 60 that is curved in an inverted mountain shape in the thickness direction of the material in the longitudinal direction, and a product 60 that is curved in a mountain shape in the width direction of the material as shown in FIG. The press mold of the present invention can also be effectively used for molding the product 70.

As detailed above, according to the press mold according to the present invention,
It becomes possible to mold a long object that is curved not only in the width direction but also in the longitudinal direction with almost no shock lines or wrinkles, and the yield of material is improved compared to the conventional method.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view showing an embodiment of the present invention, Fig. 2 is an enlarged view of the section ◯ in Fig. 1, Fig. 3 a to d are explanatory diagrams of the operation of the embodiment shown in Fig. 4 and 5 are graphs showing the relationship between the size of the gap between the bead and the groove and the incidence of shock lines and wrinkles in the examples shown in FIGS. 1 and 2, respectively, and FIG. FIG. FIGS. 7 and 8 are perspective views showing examples of other products suitably formed by the press mold of the present invention. 1...Dice, 2...Concave, 3L, 3
R...Bead, 4L...Bottom surface of die,
6...Upper die, 10...Punch, 11.
...Convex surface, 16...Lower mold, 20L, 20
R...Lower blank holder, 21L. 21R...Groove, 22L...Top plank holder top surface, 25L, 25R...Support member,
29L, 29R...preceding block, 30...
...Material, 40L. 40R...Wrinkle pressing member.

Claims (1)

[Scope of utility model registration request] It is a molded product used for press-molding long objects curved not only in the width direction but also in the longitudinal direction, and has a bank-like bead protruding from the wrinkle pressing surface of the die, and the tip end surface of the bead. A press for a long object, characterized in that a leading block capable of securing a gap larger than the thickness of the material between the die and the wrinkle pressing member facing therebetween is disposed between the die and the wrinkle pressing member. Type.