JPH03264126A - Forming method and die for products with opening - Google Patents

Abstract

PURPOSE:To execute drawing without excessive working and to lead out the scrap from the die by leaving one part of the opening edge of the opening part from cutting, trimming, drawing while pulling the cut left part and leading out a product in a state attaching the scrap of the opening. CONSTITUTION:The blank W is set on the die and the upper die 2 descends. The blank W is roughly formed to the shape of press down die 1. The pad 10 is formed with the slits c. The cutting blade 8 of the upper die 2 is forced into the cutting blade 7 of the lower die 1 and trimming is executed along the trimming line d. In this time, the part of the recess lacked part 9 is left with cutting to make the cut left part e. The annular projecting part 6 presses the outer peripheral opening edge part (b) to the annular groove 5 and drawing is executed. In this case, the press forming is executed in the state of the reduced tearing resistance of the slits c. The upper die 2 is lifted, the blank W is led out together with the scrap f to the outside of die.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for molding a product having an opening with a drawn edge portion, and a mold for use in carrying out this method.

(Prior art) There are two methods for forming this type of product: one is to draw the rim of the blank using a forming die, and then punch out the opening using a trimming die. After punching, there is a method in which the rim portion is drawn using a molding die (see Japanese Patent Laid-Open No. 128229/1983).

In the former method, since the blank material is continuous inside the rim during drawing, the forming load increases and may cause cracks in the rim. In addition to a trimming die for trimming the outer periphery of the blank, it is necessary to provide a trimming die for punching out the opening before drawing, resulting in an increase in equipment costs.

(Problems to be Solved by the Invention) In order to solve the above-mentioned problems, a single mold including a lower mold and an upper mold, in which a blank holder supported by a cushion bind is disposed on the outer periphery, is used to punch out the opening and the opening. It is also conceivable to perform partial drawing. That is, an annular groove for drawing the mouth edge portion is formed on the upper surface of the lower mold, and an annular projection for drawing that is inserted into the annular groove is formed on the lower surface of the upper mold. A cutting edge extending over the entire circumference is formed on the inner circumferential wall of the annular protrusion, and by lowering the upper die, the outer circumference of the blank is first sandwiched and restrained between the upper die and the blank holder, and by subsequent lowering of the upper die, It is conceivable to insert the annular protrusion into the annular groove and first trim the rim shape of the opening in the blank using a cutting blade, that is, punch out the opening, and then draw the rim portion.

However, in this case, scraps from the punched opening remain on the convex portion of the inner periphery of the annular groove of the lower die, making it difficult to remove the scraps.

In view of the above points, the present invention enables the drawing process to be carried out while separating the edge portion of the opening from the blank material inside the opening, and also enables the scrap of the opening to be discharged out of the mold together with the blank. The purpose of this invention is to provide a molding method and a molding die.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a mold for forming a product having an opening with a drawing process applied to the mouth edge, and a blank holder supported by a cushion bin. A device comprising a lower mold and an upper mold disposed on the outer periphery, wherein the upper surface of the lower mold has an annular groove for drawing the mouth edge portion, and the lower surface of the upper mold has an annular groove inserted into the annular groove. A cutting edge for trimming the mouth edge shape of the opening is formed on the inner peripheral wall of the annular groove and the inner peripheral wall of the annular projection, and the cutting edge of the annular groove and the At least one of the cutting edges of the annular projection was removed from the annular groove and a portion of the annular projection in the circumferential direction.

(Function) When the upper die is lowered, the outer circumference of the blank is first caught and restrained between the upper die and the blank holder, and as the upper die continues to descend, the annular projection of the upper die is moved into the annular shape of the lower die. When inserted into the groove, the blank material is sandwiched between the cutting edge on the inner circumferential wall of the annular projection and the cutting edge on the inner circumferential wall of the annular groove, and is cut, while the blank material is cut at the cutout part of the cutting edge. Instead, the shape of the rim of the opening is trimmed on the blank, leaving a part of the rim uncut. Next, the rim part is pushed into the annular groove by the annular projection and drawn, but most of the rim part has been cut off from the inner blank material, and the rim part is drawn while pulling the uncut part of the rim. You can draw the edges without putting too much stress on them.

In addition, in order to reduce the molding load on the uncut portion and further improve the molding accuracy of the lip portion, during the trimming process,
It is desirable to form a slit in a portion of the blank located inside the uncut portion to reduce the tensile strength of the uncut portion.

In order to form such a slit, a pad that faces a convex part on the inner periphery of the annular groove of the lower mold is provided in a recess on the inner periphery of the annular projection formed on the upper mold, and is biased downwardly. A male blade is formed to be located inside the cutout part of the cutting blade and protrudes downward, and a female blade is formed in the convex part of the lower mold to form a slit in cooperation with the male blade. Good.

By the way, in the state where the edge portion is drawn as described above, the scrap at the opening is connected to the blank at the uncut portion, and after drawing, the blank can be discharged from the mold with the scrap attached. This scrap is removed by cutting off the uncut portion when trimming the outer periphery of the blank in a later process.

(Embodiment) In the illustrated embodiment, the present invention is applied to the molding of a product consisting of the upper half of a motorcycle fuel tank shown in FIG.
is formed, and its mouth edge is drawn into a stepped shape that is recessed downward.

The mold for this product is as shown in Figures 1 and 2.
A punch-shaped lower die (1), a die-shaped upper die (2),
It consists of a blank holder (3) supported by cushion bins (3a) arranged around the outer periphery of the lower mold (1), and an upper mold (1).
2) can be moved up and down along the guide post (4) installed upright on the base of the lower mold (1), and the blank holder (3)
After placing the blank W at its outer periphery, the upper mold (2
) and place the outer periphery of the blank W on the blank holder (
3) and the bead (2a), which is attached to the upper mold (2) and is sandwiched between the blank W and the upper mold (2), is bitten to restrain the outer circumference of the blank W, and in this state, the blank W is press-formed, At the same time, trimming of the opening a and drawing of the edge of the mouth were carried out.

This drawing process is performed by forming an annular groove (
5> and an annular protrusion (6>) formed on the lower surface of the upper die (2> to be inserted into the annular groove (5>).
Furthermore, cutting edges (7) and (8) are formed on the inner circumferential wall of the annular groove (5) and the inner circumferential wall of the annular protrusion <6> as shown in FIG. The shape can now be trimmed.

Further, as shown in FIG. 4, diagonal recesses (9) are formed at three locations around the inner peripheral wall of the annular groove <5>, and in the recesses (9) the cutting edge (7) Made to be deleted.

Furthermore, a recess (6a) on the inner circumference of the annular projection <6> of the upper mold <2>
), the lower mold (1> annular groove (5> inner circumferential convex part (5a)
A pad (IO) facing downward is provided with a spring (10a), and a female pad (IO) located inside the recessed part (9) is provided on the upper surface of the convex part (5a), as shown in FIG. A blade CIv is recessed, and two male blades (a) that cooperate with the female blade (11) are provided protruding from the lower surface of the pad 0■.

Next, the process of forming the blank W using the above-mentioned forming die will be explained. When the blank W is set in the mold and the upper mold (2) is lowered, the outer periphery of the blank W is first held between the blank holder (3> and the upper mold (2)) and is restrained. The blank W is pressed down and roughly formed into a shape that follows the lower mold (1), and then the pad 110 comes into contact with the part of the blank W that corresponds to the opening a of the product, and this part is connected to the pad (10) and the lower mold (1). 1) and the convex part (5a). At this time, the male blade 0 of the pad aO is inserted into the female blade ○ of the convex part (5a).
A slit c is formed in the blank W as shown in FIG. 5(a).

Next, the cutting edge (8) of the annular projection (6>) of the upper die (2) is inserted into the cutting edge (7) of the annular groove (5) of the lower die (1), and the blank W is inserted into the blank W as shown in FIG. As shown in b), a trimming process is performed along the trim line d corresponding to the shape of the rim of the opening a.At this time, the cutting edge (7) matches the recessed part (9) to be removed. The blank portion is left uncut, and the slit C is located inside the uncut portion e.

After that, the annular protrusion (6) pushes the outer periphery of the trim line d into the annular groove (5) and draws it. At this time, the uncut part e is pulled, but the slit C inside the uncut part e is torn as shown in FIG. In this way, the rim portion can be drawn with high accuracy over the entire circumference with a light load comparable to that in the case where the opening a is punched out in advance.

Also, at the same time as the drawing of the mouth edge portion, the entire blank W is sandwiched between the lower mold (1) and the upper mold (2) and press-formed,
Next, the upper mold (2) is raised and the plan W is discharged out of the mold. Here, since the scrap f in the opening a is connected to the lip portion via the uncut portion e, the scrap f is discharged out of the mold together with the blank W.

The discharged blank W is sent to a trimming process, where the outer periphery of the blank is trimmed using a laser or a trimming mold, and the uncut portion e is cut to remove the scrap f.

(Effects of the Invention) As is clear from the above description, according to the invention of claim 1.3, the shape of the rim of the opening is trimmed on the blank by leaving a part of the rim, and then the rim of the opening is trimmed. Since the part is drawn, the rim part can be drawn without forcing it, and the scrap at the opening can be taken out of the mold together with the blank, making it easy to punch out scraps inside the mold. This has the effect of eliminating problems such as the difficulty in discharging the resulting scrap.

Furthermore, according to the invention of claim 2.4, since the slit is formed inside the uncut portion of the mouth edge, the resistance to tension of the uncut portion during drawing of the mouth edge portion is reduced, and the uncut portion is This has the effect of reducing the molding load as much as possible and drawing the rim portion with high accuracy over the entire circumference.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a longitudinal sectional view of an example of the mold of the present invention, Fig. 2 is a plan view of the lower mold thereof, and Figs. 3 and 4 are respectively shown in Fig. 2. 5(a), 5(b), and 5(C) are diagrams explaining the molding process, and FIG. 6 is a perspective view of the product. It is. W...Blank a...Opening b...Edge part C...Slit e...Uncut part
f...Scrap (1>...Bottom mold)
(2)...Top mold (3>...Blank holder (3a>...Cushion bin (5>...Annular groove)
(5a>... Convex part (6)... Annular protrusion
(6a>...Concave part (7) (8)...Cut
Blade (9)...Concave cutout (cutting edge cutout) (10...Pad (11)...Female Blade (9)...Male Blade Figure 5 Same as above Honda Engineering Co., Ltd. Figure 1 2nd rlA III; 4rIA

Claims (1)

[Claims] 1. In a method for molding a product having an opening whose rim is drawn, the rim of the opening is attached to the blank set in a mold while the outer periphery of the blank is restrained. The shape is trimmed leaving a part of the rim uncut, then the rim of the opening is drawn while pulling the uncut part, and the drawn blank is placed outside the mold with the scrap of the opening still attached. A method for molding a product having an opening characterized by dispensing the product. 2. The method for molding a product having an opening according to claim 1, wherein, during the trimming process, a slit is formed in a portion located inside the uncut portion of the mouth edge. 3. In a mold for forming a product having an opening with a drawing process applied to the mouth edge, the lower mold has a blank holder supported by cushion pins arranged on the outer periphery, and an upper mold. An annular groove for drawing the mouth edge portion is formed on the upper surface of the mold, and an annular projection for drawing that is inserted into the annular groove is formed on the lower surface of the upper mold. A cutting edge for trimming the rim shape of the opening is formed on the inner peripheral wall of the protrusion, and at least one of the cutting edge of the annular groove and the annular protrusion is formed between the annular groove and the annular protrusion. A mold for forming a product having an opening characterized by being partially cut out in the circumferential direction. 4. A pad facing the convex part on the inner periphery of the annular groove of the lower mold is provided in the recessed part of the inner periphery of the annular projection of the upper mold, and is biased downward, and the lower surface of the pad is provided with the pad of the cutting edge. A male blade is formed that is located inside the cutout and projects downward, and a female blade that cooperates with the male blade to form a slit in the blank is formed on the convex part of the lower mold. A mold for forming a product having the opening according to claim 3.