JPS5897430A - Drawing forming method - Google Patents

Abstract

PURPOSE:To prevent wrinkles and stretch cracks generated by stretching, contraction or imbalance of stretching and contraction in performing bending in the direction of width and folding back bending in the longitudinal direction at the same place by forming a bulged part at that place beforehand. CONSTITUTION:In forming a product 1 by drawing, the material plate 25 on the lower blank holder 15 is grasped by wrinkle pressing faces 16, 18 by lowering of a die 12. Then, it strikes against a punch 11 by lowering of the holder 15 and is bent. At that time, the plate 25 is pushed up partially by a subpunch 20 which is pushed up by a spring 22, and a bulged part 26 is formed. The position covers the slant face 4 to the flat face 5 and corresponds finally to the position where bending in the longitudinal direction and transverse direction is performed. The position is a position where contact with the punch 11 takes place latest. With further lowering of the die 12, drawing makes progress and the ridigity of the plate 25 increases. The punch 20 is pushed down, and goes into the punch 11. Finally, the bulged part 26 is stretched and stretching and contraction occur in proper quantities. Consequently, wrinkles and stretch cracks do not take place and a product of required shape can be obtained.

Description

[Detailed description of the invention] Regarding this redundant molding method, bending in one direction of positive force and folding in the same direction of force perpendicular to this can be caused at the same tube place. The product that prays for, FL, is related to the pattern forming method of press-molding a product that has a four-sided box-shaped cross section (hereinafter referred to as a hat cross section) and a partially saddle-shaped convex shape (hereinafter simply referred to as a saddle shape). .

As shown in Figure 1, the method of drawing a partially saddle-shaped product with continuous hats Mn is to divide the saddle-shaped part into two on the left and right over medium heat, or There is a splitting method in which the part is divided into three separate parts and each divided piece is individually pressed and formed, or a method in which the first stage is used to reduce the bending diameter to a large diameter, and the second stage is used to narrow it down to the shape of the final product. ,
Conventionally, integrated methods such as Rurui (step drawing) and V (double action) fall forming method are known. However, in the above-mentioned division method, the number of molds is increased by 3 + 1, and 8! ! The manufacturing cost is increased, the number of parts increases, so the bath welding process increases, and the work space and equipment costs increase due to the increase in the welding process. l] There are many problems that cause the rise,
In addition, in the conventional integrated method described above, the material yield is reduced due to the use of a stepped drawing shape for the purpose of improving drawing formability, and wrinkles and elongation cracks are likely to occur, making it difficult to achieve the desired result. There were problems such as difficulty in obtaining products.

This invention was made in view of the above-mentioned circumstances, and an object thereof is to provide an MDK molding method that is an integral force type and can be molded without causing wrinkles or elongation cracks when using a single action press. The feature is that the product to be drawn is brought into contact with the lower die punch at the point where the bending in the width direction and the folding back bending in the longitudinal direction perpendicular to this are caused. to form a bulge before molding,
The above-mentioned bulging portion is also stretched when the above-mentioned ′ part is brought into contact with the lower die punch and molded, thereby preventing the occurrence of wrinkles or stretch cracks due to elongation or compression or an imbalance thereof. be.

That is, for example, when molding the entire shape of a product I7f in the shape shown in FIG. 2 is normally made into a gently curved shape, but since the wrinkle presser surface and the tie bang that the knife-shaped punch hits are different, the material is gathered from the early part to the late part, resulting in the diagonal line in Figure 2. Wrinkles occur in the areas indicated by . Therefore, in the present invention, a material (material plate) is placed in the vicinity of the area where wrinkles are likely to occur, in the area extending from the slope 4 following the top surface 3 of the saddle-shaped portion in FIG. A bulge is formed at the same time or slightly before the rolling and forming starts, and the bulge is eventually stretched to absorb wrinkles. In other words, by making the bulge function as an elongation allowance, elongation and compression on or near the inclined surface 4 and flat surface 5 at the final stage of molding are facilitated, thereby balancing elongation and compression and eliminating wrinkles. This prevents the occurrence of cracks and stretching cracks.

The present invention will be explained in more detail below, taking as an example the case where the product shown in FIG. 1 is drawn. First, to explain the mold to be used, Fig. 3 is a sectional view with half of the mold in the longitudinal direction omitted, and Fig. 4 shows the iV- iV
It is a vI side view along the line, and the upper surface of the lower mold punch 11 provided on the lower mold main body 10 is formed in the same shape as the product 1,
Further, the upper die 12 has a recess 13 having a shape corresponding to the upper surface of the lower punch 11, and has a lower a\! [Punch] It is constructed so that it can move up and down with respect to 1. A dichotomy (
A lower blank holder 15 pushed up by a lower blank holder 15 (not shown) is disposed, and its upper surface serves as a lower die wrinkle presser 16, and a tension bead 1 is placed on the lower die wrinkle presser surface 16.
7 is formed, and on the other hand, the outer peripheral part of the lower surface of the upper mold die 12 opposite to this lower mold wrinkle pressing surface 16 serves as an upper mold wrinkle pressing surface 18. A corresponding protrusion 19 is formed (5).

A sub-punch 20 is disposed as a pre-drawing member in a portion of the lower die punch 11 corresponding to a portion extending from the inclined surface 4 to the flat surface 5 of the product 1 so as to be able to protrude and retract. This sub-punch 20 has an upper end surface at an angle approximately equal to the wrinkle pressing surfaces located on both left and right sides (for example, 15° to 35°).
°), and is housed in a cavity 21 formed in the lower die punch 11, and is further pushed up by a spring 22 disposed on the lower surface side, and its shoulder engages with the upper surface of the cavity 21. This is said to be a configuration that prevents removal. Here, the elastic force of the spring 22 is 1/6 to 1/1 of the force required for normal drawing forming.
About 3 is preferable. Therefore, the sub-punch 20 is
When the upper die 12tl is being pulled upwards and while the rigidity of the product 1 being formed is weaker than the elastic force of the spring 22, its upper end surface touches the upper surface of the lower die punch 11, more specifically, the material plate. It protrudes from the top of the area where the timing of the hit is the latest.

(6) Note that the numeral '$23 in FIGS. 3 and 4 indicates a spring stopper bottle, and the numeral 24 in FIG. 4 indicates a slide plate on the lower blank holder 15.

Next, the present invention using the above mold will be explained in detail.

The material plate 25 placed on the lower blank holder 15 is rolled by the valley wrinkle pressing surface 16.18 by lowering the upper die 12. As it descends against the pressure, it hits the lower die punch 11 and is gradually bent. In that case, immediately after the start of bending, that is, at the initial stage of forming, the sub-punch 20 as a prewarming member protrudes from the upper surface of the lower die punch 11, and the elastic force of the spring 22 pushing up the sub-punch 20 causes the material plate 25 to Since the material plate 25 is stronger than the rigidity, the material plate 25 is partially relatively pushed up by the sub-punch 20 as shown by the dashed line in FIG. 3, and as a result, a bulge 26 is formed as shown in FIG.

As is clear from the arrangement position of the sub-punch 20, the position of this bulging portion 26 is from the inclined surface 4 to the flat surface 5 of the final product 1. Corresponding to the position where bending in the direction is performed, this is the position where touch tying to the lower die punch 11 is slowest.

However, at this stage, the material plate 25 is not particularly actively folded back in the longitudinal direction, and the material plate 25 is not particularly actively bent.
elongation occurs.

When the upper die 12 is lowered, the material plate 25 is further bent to proceed with the forming process, and as a result, the material plate 25 is further bent.
The rigidity of the spring 22 increases, and the reduction blade by the two-type die 12 acts, so that the sub-punch 20 finally hits the spring 22.
It is pushed down against the elastic force of and retreats into the lower die punch 11. In such a final stage of molding, the bulging portion 2
6, the bending in the width direction and the folding in the pitcher direction perpendicular to this proceed simultaneously, and elongation and compression occur in a complicated manner, but eventually the bulge 2
6 is stretched to the desired shape, so the bulge 26
Elongation and compression due to the shape change caused by stretching and resolving occur in just the right amount, and as a result, wrinkles and stretch cracks can be prevented from occurring. This phenomenon can be attributed to the fact that the wrinkles and elongation cracks were absorbed by the swelling U1 portion 26.

As described above, the method of the present invention is a method in which the portion that is hit by the lower FFI punch 11 at a later timing is stretch-molded in the early stage of molding, and the bulge portion 26 is formed there to prevent the occurrence of wrinkles and stretch cracks. Therefore, the mold used to carry out the method of the present invention should just be one that can form the above-mentioned bulge, and the pre-drawing member for this purpose is not limited to the sub-punch 20, but may be, for example, a lower part. The mold punch may be divided into a plurality of parts, and the divided pieces at the portions where the contact timing is normally delayed are made to protrude upward in advance, and this may be used as the above-mentioned pre-squeezing member. Furthermore, the means for pushing the pre-squeezing member upward is not limited to the spring 22, but mechanical means such as a cam may also be used. Furthermore, this invention is not limited to the case where a product l having the shape shown in FIG. It can be applied to the case of drawing and forming a product in which the lower die punch hits that part later than other parts.

As explained above, according to the drawing method of the present invention, the saddle shape can be folded in the same width direction and folded back in the longitudinal direction orthogonal thereto at the same location, and at the same location. When drawing a product whose shape is such that the timing at which it hits the lower die punch is later than at other parts, a bulging part is stretch-formed at the point where the timing at which it hits the lower die punch is delayed at the beginning of forming. Then, the bulge was stretched and resolved at the end of the molding stage, so the elongation and compression at that point was reduced to 9.
As a result, the elongation of the material is made uniform even in areas where conventional line forming is performed, and the occurrence of wrinkles can be effectively prevented.

(10)

[Brief explanation of the drawing]

Figure 1 is a perspective view showing an example of a saddle-shaped drawn product;
The figure is an enlarged view of part ■ in Figure 1 to show where wrinkles occur, Figure 3 is a sectional view showing half of the mold in the longitudinal direction used to carry out the method of the present invention, and Figure 4 is IV in Figure 3 with the upper die raised to the upper limit
A cross-sectional view taken along the line -W, and FIG. 5 is a perspective view showing a part of the intermediate product at the initial stage of drawing-forming. DESCRIPTION OF SYMBOLS 1...Product, 11...Lower die punch, 12...Upper die, 20...Sub punch (10 parts), 25...
...Material plate, 26...Bulging part. Applicant Toyota Motor Corporation Toyota Industries Corporation Representative Patent Attorney Yutaka 1) Takehisa (1 person) (11) Figures 1-3 and 4 1゜Figure 5/'

Claims (1)

[Claims] In order to create a slope-shaped fold in the same width direction and a double fold in the direction perpendicular to the fold at the same place, a thousand-piece member is used to form a garment. Timing of contact of the material plate with the lower punch Vc2) At the slow tube place, taking into account the protruding and retracting marks from the upper surface of the lower 752 punch, the material plate is bent and folded back. Form a bulge in the cylindrical part with the aperture member at the point where the part to be subjected to contact with the lower die punch, and then, while pressing down the pre-drawing member, press the material onto the upper surface of the 2-inch lower die of the sheet metal. Soft molding ε characterized in that the bulging portion is pressed and molded while being stretched and eliminated into the final shape using a lower die punch and an upper die.