JP2002113528A - Method and apparatus for drawing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a forming limit by prevent a crack due to concentration of tensile stress on a corner part of a body to be stretch-formed by a moving punch. SOLUTION: In a drawing method forming a bottomed cylindrical body 1, by using a field die 2 having an annular shoulder part and a die hole formed at an inner peripheral face of the annular shoulder part, and a moving punch 10 which can advance to and retreat from the die hole, and by advancing/ pressing the moving punch 10 into the die hole of the fixed die 2, forming is conducted while a material of the body to be worked brought into contact with the die face is positively supplied in a forming promoting direction by moving a moving die 5 of which the die face is brought into contact with a surface of the body to be worked before forming or in a process of forming, in linking to advancement of the moving punch 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a movable die and a fixed die having an annular shoulder and a die hole formed in the inner peripheral surface of the annular shoulder, and pushes the movable punch into the die hole of the fixed die. Accordingly, the present invention relates to a drawing method and apparatus for forming a bottomed cylindrical body.

[0002]

2. Description of the Related Art Conventionally, a simple cup-shaped bottomed cylindrical body having a bottom wall and an annular side wall rising from the outer peripheral edge of the bottom wall is formed from a flat plate, or a simple cup-shaped bottomed cylindrical body. In order to form a cup-shaped bottomed cylindrical body with a stepped cup-like shape by further forming a cup-shaped forming concave portion on the bottom wall of the base plate, draw forming using a fixed die and a movable punch is used.

For example, as shown in FIG. 8, a cup-shaped forming recess 90c is further formed on a bottom wall 90a of a workpiece W which is a simple cup-shaped bottomed cylindrical body having a bottom wall 90a and an annular side wall 90b. In the case of molding to form a stepped cup-shaped bottomed cylindrical body 90, a draw forming method and apparatus as shown in FIG. 8 are conventionally used.

[0004] This drawing apparatus comprises a fixed die 91,
A movable punch 92, a pad 93, and an ejector 94 are provided. The fixed die 91 includes a first side wall portion 91a abutting on the outer peripheral surface of the annular side wall 90b of the simple cup-shaped workpiece W before molding, and a bottom wall 90a of the simple cup-shaped workpiece W before molding. Horizontal portion 91b abutting on the outer peripheral edge of
An annular shoulder portion 91d forming a die hole 91c in which the movable punch 91 moves forward and backward; and a second side wall portion abutting on the outer peripheral surface of the annular side wall of the molding concave portion 90c in the bottomed cylindrical body 90 after molding. 91e. The movable punch 92 can move up and down with respect to a die hole 91c of the fixed die 91 by moving up and down. The pad 93 can be moved up and down, and by sandwiching the outer peripheral edge of the bottom wall 90a of the workpiece W between the pad 93 and the horizontal portion 91b of the fixed die 91, generation of wrinkles on the bottom wall 90a is prevented.

In the drawing apparatus, the movable punch 92 and the pad 93 are raised, and the ejector 94 is raised to the level of the horizontal portion 91c of the fixed die 91.
4, a simple cup-shaped workpiece W is set. Then, the pad 93 is lowered, and the bottom wall 90a of the workpiece W is
The outer peripheral edge of the pad 9 is fixed to the horizontal portion 91c of the fixed die 91.
3 at a predetermined pressure. At this time, the workpiece W
The inner peripheral surface of the annular side wall 90b contacts the outer peripheral surface of the pad 93, and the outer peripheral surface of the annular side wall 90b is
It is in contact with the inner peripheral surface of the first first side wall portion 91a. From this state, the movable punch 92 is lowered to move the movable punch 92 into the die hole 91c of the fixed die 91, and the movable punch 92 is pushed into the die hole 91c while the ejector 94 is lowered. Thereby, the bottom wall 9 of the workpiece W is
The center of the bottom wall 90a is inserted into the die hole 91c at the end of the movable punch 92 while the outer peripheral edge of the bottom wall 90a is held between the horizontal portion 91c and the pad 93 of the fixed die 91 and supported by the annular shoulder 91d. Then, the concave portion 90c is drawn and formed at the center of the bottom wall 90a of the workpiece W.
Then, after raising the movable punch 92 and the pad 93, the ejector 94 pushes out the molded bottomed cylindrical body 90 and removes it from the mold.

[0006]

However, in the conventional drawing method and apparatus as described above, the movable punch 92
The concave portion 9 which comes into contact with the corner portion of the workpiece W to be overhang-formed, ie, the tip shoulder portion 92a of the movable punch 92.
Crack 90e due to the concentration of tensile stress
This is problematic in that the problem is likely to occur.

The present invention has been made in view of the above circumstances, and can prevent cracks due to the concentration of tensile stress at the corners of a workpiece to be overhanged by a movable punch, thereby improving the molding limit. An object of the present invention is to provide a drawing method and apparatus.

[0008]

According to the present invention, there is provided a draw forming method comprising: a fixed die having an annular shoulder and a die hole formed in an inner peripheral surface of the annular shoulder; By using a movable punch capable of moving forward and backward, the movable punch is advanced and pushed into the die hole of the fixed die, thereby forming a bottomed cylindrical body. Before or during molding, by moving a movable mold whose own mold surface contacts the surface of the workpiece in accordance with the advance of the movable punch, the material of the workpiece that contacts the mold surface is moved. It is characterized in that molding is performed while positively supplying in the molding promotion direction.

A draw forming apparatus according to the present invention for solving the above-mentioned problems comprises a fixed die having an annular shoulder and a die hole formed in the inner peripheral surface of the annular shoulder, and a forward / backward movement into and out of the die hole. With the movable punch enabled, the mold surface of the workpiece comes into contact with the surface of the workpiece before or during molding, and the material of the workpiece in contact with the mold surface is positively promoted in the molding promotion direction. And a movable die that can be moved in accordance with the movement of the movable punch to supply the movable punch.

In the draw forming method and apparatus according to the present invention,
Before or during molding, the movable die whose own mold surface comes into contact with the surface of the workpiece is moved in accordance with the advance of the movable punch to form the material of the workpiece that comes into contact with the mold surface. Forming while actively supplying in the promotion direction. As described above, by actively supplying the material of the workpiece in the forming promotion direction, the material of the workpiece is also actively fed to the corners of the workpiece that is formed by the movable punch.
For this reason, the concentration of tensile stress is eased and the material shortage is eliminated at the corners of the workpiece to be overhanged by the movable punch. Therefore, it is possible to prevent cracks at the corners and improve the molding limit.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) As shown in FIG. 3, the present embodiment shown in FIGS. 1 to 4 has a simple structure having a bottom wall 1a and an annular side wall 1b integrally rising from the outer peripheral edge of the bottom wall 1a. By subjecting the workpiece W, which is a cup-shaped bottomed cylindrical body, to drawing, the cup-shaped recess 1c is formed in the bottom wall 1a.
Are further molded to form a stepped cup-shaped bottomed cylindrical body 1.

In the drawing apparatus according to the present embodiment, a fixed die 2 is placed on a fixed base 3. As shown in FIG. 4, the fixed die 2 has a horizontal portion 2a formed on the upper end surface and an annular shoulder 2b provided integrally with the inner peripheral edge of the horizontal portion 2a. A die hole 2d having a circular cross section is formed on the inner peripheral surface of the annular inner wall portion 2c provided integrally with the lower end of the annular shoulder portion 2b. The lower end of the annular inner wall portion 2c has a formed concave portion 1c formed by drawing.
A round step 2e abutting on the outer peripheral surface of the corner 1d is provided, and a shaft hole 2f having a circular cross section is provided at the inner peripheral edge of the round step 2e. An ejector 4 is slidably disposed in the shaft hole 2f of the fixed die 2.
The ejector 4 can be moved up and down in the die hole 2d and the shaft hole 2f by a driving means (a hydraulic cylinder or the like) not shown.

An annular concave step 2g is provided at the upper end on the outer peripheral side of the fixed die 2, and a substantially cylindrical first movable mold 5 having a center hole 5a having a circular cross section is provided in the annular concave step 2g. It is slidably disposed. The center hole 5 of the first movable die 5
a has an inner diameter substantially equal to the outer diameter of the annular side wall 1b of the workpiece W before molding. The lower end of the first movable die 5 is integrally provided with a regulating plate 5b that protrudes in the centrifugal direction from the outer peripheral surface of the first movable die 5. The first movable mold 5 is provided with a regulating plate 5
b is urged upward by a not-shown urging means (a hydraulic cylinder or the like) via a first knockout pin 6 which comes into contact with the lower surface of b, and a restricting portion of a stopper 7 disposed outside the first movable mold 5. By contacting the regulating plate 5b with 7a, the highest position of the first movable mold 5 is regulated.

As shown in FIG. 1, when the first movable mold 5 is at the highest position due to the contact between the regulating plate 5a and the regulating portion 7a of the stopper 7, the upper end of the first movable mold 5 has a fixed die. 2 is located above the upper end of the annular side wall 1b of the workpiece W before molding set to 2. Further, the inner peripheral surface of the center hole 5a of the first movable die 5 at the highest position contacts almost the entire outer peripheral surface of the annular side wall 1b of the workpiece W before molding set on the fixed die 2, and The inner peripheral surface of the center hole 5a of the first movable mold 5 at the lowest position contacts almost the entire outer peripheral surface of the annular side wall 1b of the formed workpiece W (the bottomed cylindrical body 1) (FIG. 2). reference).

A movable punch 10 and a killer block 11 are fixed to the movable table 8 via a holding plate 9, and the movable punch 10 and the killer block 11 are movable by a driving means (such as a hydraulic cylinder) (not shown). It can be moved up and down synchronously with the table 8. Movable punch 10
Has a molding outer peripheral surface 10a corresponding to the inner peripheral surface shape of the molding concave portion 1c to be molded in the workpiece W. Further, the killer block 11 comes into contact with the upper surface of the first movable mold 5 by descending, and lowers the first movable mold 5 against the urging force of the urging means.

A drive means (not shown) such as a hydraulic cylinder is provided on the movable base 8 via a second knockout pin 12.
Holds the pad 13 which can be moved up and down.
The pad 13 has a substantially cylindrical shape and descends to clamp the outer peripheral edge of the bottom wall 1a of the molded body W before and during molding with the horizontal portion 2a of the fixed die 2 at a predetermined pressure. Thus, generation of wrinkles at the outer peripheral edge of the bottom wall 1a is prevented. The outer peripheral surface of the pad 13 is in contact with the inner peripheral surface of the annular side wall 1b of the workpiece W before and during molding.

The driving means (not shown) for operating the ejector 4, the driving means (not shown) for operating the fixing table 8, and the driving means (not shown) for operating the pad 13 are all controlled by control means (not shown). ing.

According to the draw forming apparatus having the above configuration,
A stepped cup-shaped bottomed tubular body having a cup-shaped recessed portion 1c formed in a bottom wall 1b by subjecting a workpiece W, which is a simple cup-shaped bottomed tubular body, to a drawing process by the method described below. 1
Can be molded.

That is, as shown in FIG. 1, the movable table 8 is raised by the operation of the driving means (not shown), and the movable punch 10, the killer block 11, and the pad 13 are raised together with the movable table 8. In addition, the ejector 4 is raised by the operation of a driving unit (not shown) so that the upper end surface of the ejector 4 and the horizontal portion 2a of the fixed die 2 are at the same height. In addition, the first movable mold 5 is controlled by the urging force of the urging means (not shown) to control the regulating plate 5 b and the regulating portion 7 a of the stopper 7.
Is at the highest position where it contacts.

In this state, a workpiece W which is a simple cup-shaped bottomed cylindrical body having a bottom wall 1a and an annular side wall 1b is set on the horizontal portion 1a of the fixed die 2 and the ejector 4. Then, the pad 1 is actuated by the operation of a driving unit (not shown).
3, the outer peripheral edge of the bottom wall 1a of the workpiece W is clamped between the horizontal portion 1a of the fixed die 2 and the pad 13 (the state of FIG. 1). The horizontal portion 1a and the pad 13
Is maintained at a constant pressure during molding. During the molding, the inner peripheral surface of the annular side wall 1b of the workpiece W always contacts the outer peripheral surface of the pad 13, and the outer peripheral surface of the annular side wall 1b contacts the inner peripheral surface of the center hole 5a of the first movable die 5. In contact.

Then, the movable punch 10 and the killer block 11 together with the fixed base 8 are lowered synchronously by the operation of the driving means (not shown). As a result, the distal end surface of the movable punch 10 is moved from the state shown in FIG.
And the killer block 11 comes into contact with the first movable die 5 at about the same time. The movable punch 10 and the killer block 11 continue to descend, the movable punch 10 is moved into the die hole 2d of the fixed die 2, and the movable punch 10 is pushed into the die hole Sc while the ejector 4 is lowered. 1 Center hole 5 of movable mold 5
The movable die is pushed down by the killer block 11 against the urging force of the urging means (not shown) while the inner peripheral surface of a is slidingly contacting the outer peripheral surface of the annular side wall 1b of the workpiece W (the state of FIG. 2). Thus, while the outer peripheral edge of the bottom wall 1a of the workpiece W is sandwiched between the horizontal portion 2a and the pad 13 of the fixed die 2 and supported by the annular shoulder 2b, the central portion of the bottom wall 1a is movable. The tip of the workpiece 10 is pressed into the die hole 2d, and a forming recess 1c is formed by drawing in the center of the bottom wall 1a of the workpiece W.

Thereafter, the movable punch 10 and the killer block 1 together with the fixed base 8 are actuated by the operation of driving means (not shown).
1 and the pad 12 are raised, and the ejector 4
To remove the molded bottomed cylindrical body 1.

In the drawing method and apparatus according to this embodiment, the inner peripheral surface of the center hole 5a of the first movable die 5 is
During molding, the outer peripheral surface of the annular side wall 1b is always in contact with the outer peripheral surface of the first movable die 5 after the movable punch 10 starts molding the workpiece W in synchronization with the lowering of the movable punch 10.
The first movable die 5 descends while the inner peripheral surface of the workpiece and the outer peripheral surface of the annular side wall 1b of the workpiece W slide. For this reason, as shown schematically in the enlarged circle of the dotted line in FIG. 2, the interface between the outer peripheral surface of the annular side wall 1b of the workpiece W and the inner peripheral surface of the first movable die 5 has the annular side wall. A frictional resistance acts to supply the material 1b in the forming promotion direction (the direction of the forming recess 10c formed by the movable punch 10). Thus, the workpiece W can be formed while actively supplying the material of the workpiece W in contact with the inner peripheral surface of the first movable mold 5 in the forming promotion direction. Therefore, the material of the workpiece W is also positively fed into the corners 10d of the forming recesses 10c formed by overhanging the front shoulders of the movable punch 10. For this reason, the concentration of tensile stress is eased and the material shortage is eliminated at the corner 10d of the forming concave portion 10c formed by the overhang of the tip end of the movable punch 10. Therefore, it is possible to prevent cracks at the corners 10d and improve the molding limit.

In particular, in the present embodiment, the first movable mold 5 descends at the same speed as the movable punch 10 that has started molding by the killer block 11 that descends together with the movable punch 10. As the material of the annular side wall 1b of the workpiece W can be supplied in the molding promoting direction in accordance with the progress of the molding of the workpiece W, cracks in the corners 10d of the molding recess 10c can be more reliably prevented. As a result, the molding limit can be improved.

Since the killer block 11 for lowering the first movable die 5 and the movable punch 10 are both fixedly held by the movable base 8, the operation of only the movable base 8 by the driving means (not shown) is controlled by control means (not shown). By controlling the operation, the operations of the movable punch 10 and the killer block 11 can be controlled, which is advantageous in simplifying the apparatus.

Here, in this embodiment, the pad 1
It is also possible to use 3 as the movable type of the present invention.
That is, in the state before molding in FIG. 1, the pad 13 is raised by a predetermined amount from the state in FIG. Then, the workpiece W by the movable punch 10
In accordance with the progress of the molding, the drive means (not shown) is operated to lower the pad 13. Thereby, the workpiece W
The frictional resistance for supplying the material of the annular side wall 1b in the molding promoting direction also acts on the interface between the inner peripheral surface of the annular side wall 1b and the outer peripheral surface of the pad 13. Therefore, the pad 13 and the first movable mold 5 exert a frictional force on both the inner peripheral surface and the outer peripheral surface of the annular side wall 1b to actively supply the material of the annular side wall 1b in the direction of the molding recess 1c. It is possible to more reliably prevent cracks at the corners 10d of the molding recess 10c and improve the molding limit. At this time, the gap between the pad 13 and the first movable mold 5 is
b and the pad 13 and the first
If the movable mold 5 is lowered synchronously at the same speed, the material of the annular side wall 1b can be supplied in the molding promoting direction while the annular side wall 1b is sandwiched between the pad 13 and the first movable mold 5. . When the pad 13 is used as the movable mold of the present invention, the work W
The outer peripheral edge of the bottom wall 1a is sandwiched between the pad 13 and the horizontal portion 2a of the fixed die 2 to prevent wrinkles from occurring at the outer peripheral edge of the bottom wall 1a.

In this embodiment, the first movable die 5 and the fixed die 2 are integrated as in the conventional drawing device of FIG. 8, and only the pad 13 is moved by the movable die according to the drawing method of the present invention. Can also be used.

(Embodiment 2) This embodiment shown in FIG.
In the drawing apparatus according to the first embodiment, in addition to the first movable mold 5, a substantially cylindrical second die is also provided on the inner peripheral side of the fixed die 2.
A movable mold 14 is provided.

That is, in this drawing apparatus, an annular guide recess 2h extending from below the annular shoulder 2b of the fixed die 2 to the lower end of the fixed die 2 is provided.
c, a second movable mold 14 having a rounded step 2e and a shaft hole 2f is disposed in the guide recess 2h so as to be able to move up and down. Then, the second movable mold 14 is connected via the third knockout pin 15
It can be moved up and down by driving means (a hydraulic cylinder or the like) controlled by control means (not shown).

The other structure is the same as that of the first embodiment.

Therefore, this drawing apparatus has the following functions and effects in addition to the functions and effects described in the first embodiment.

That is, in the state before molding, as shown in the left half of FIG.
In the state where the movable die 14 is raised and the upper end surface of the second movable die 14 is in contact with the lower end surface of the annular shoulder 2b, the workpiece W is set and processed similarly to the first embodiment. The outer peripheral edge of the bottom wall 1a of the body W is fixed to the horizontal portion 1a of the fixed die 2.
And the pad 13.

Then, similarly to the first embodiment, the movable punch 10 and the killer block 11 are lowered synchronously with the fixed base 8. At this time, when the tip of the movable punch 10 pushes the center of the bottom wall 1a of the workpiece W into the die hole 2d of the fixed die 2, and the tip reaches the upper end of the second movable die 14. The second movable die 14 is lowered in accordance with the advance of the movable punch 10 by the operation of a driving means (not shown). In this way, the second movable mold 14 with which the surface of the workpiece W comes into contact during the molding is formed while being lowered in accordance with the advance of the movable punch 10, and a forming recess 1 c is formed in the center of the bottom wall 1 a of the workpiece W. Draw forming.

Thereafter, similarly to the first embodiment, the bottomed cylindrical body 1 after molding is removed from the mold.

As described above, in the present embodiment, the first movable mold 5 which is always in contact with the outer peripheral surface of the annular side wall 1b of the workpiece W during the molding is lowered, and the workpiece W in the molding process is lowered. Since the second movable mold 14 that contacts the outer peripheral surface of the molding recess 1c during the molding is lowered in accordance with the lowering of the movable punch 10, the molding is performed while lowering the outer peripheral surface of the molding recess 1c and the second movable mold 14 in the molding process. Also at the interface with the inner peripheral surface, a frictional resistance acts to supply the material of the molding concave portion 1c in the molding promoting direction, and thereby the material of the workpiece W that contacts the inner peripheral surface of the second movable mold 14 is reduced. Molding can be performed while positively supplying in the molding promoting direction. Therefore, the forming recess 10 formed by overhanging the front shoulder of the movable punch 10 is formed.
The material of the workpiece W is more positively fed into the corner 10d of c, and cracks in the corner 10d can be more reliably prevented, and the forming limit can be further improved.

In particular, in the present embodiment, the second molding die 14 that is in contact with the molding recess 1c of the workpiece W in the molding process, that is, the surface of the portion where molding by the movable punch 10 is in progress is moved. Therefore, the material of the portion can be more effectively supplied in the molding promotion direction.

Here, in this embodiment, the gap between the outer peripheral surface of the movable punch 10 and the inner peripheral surface of the second movable die 14 is made smaller than the thickness of the molding recess 1c in the molding process, and If the second movable mold 14 is lowered at the same speed, the material of the molding recess 1c is moved in the molding promotion direction while the molding recess 1c in the molding process is sandwiched between the movable punch 10 and the second movable mold 14. It can also be supplied.

(Embodiment 3) This embodiment shown in FIG.
In the drawing apparatus according to the first embodiment, the killer block 11 is provided with a compression force applying mechanism.

That is, in this drawing apparatus, an annular concave portion 11a which can be fitted to the upper end portion of the annular side wall 1b of the workpiece W set on the fixed die 2 is provided on the inner peripheral lower end surface of the killer block 11. Have been.

The other structure is the same as that of the first embodiment.

Therefore, this drawing apparatus has the following functions and effects in addition to the functions and effects described in the first embodiment.

That is, in this drawing apparatus, the movable punch 10 and the killer block 11 move down together with the fixed base 8 so that the killer block 11 comes into contact with the first movable mold 5 and at the same time, the annular concave portion 11a of the killer block 11 is The upper end of the annular side wall 1b of the workpiece W is fitted. For this reason, by continuing to descend the movable punch 10 and the killer block 11, the upper end surface of the annular side wall 1b of the workpiece W is pressed by the annular concave portion 11a and the material of the annular side wall 1b is pushed in the forming promotion direction. Can be drawn. Therefore, the material of the workpiece W is more positively fed into the corners 10d of the forming recesses 10c formed by overhanging the front shoulders of the movable punch 10, and the cracks in the corners 10d are more reliably prevented. It is possible to further improve the molding limit.

The annular recess 11 of the killer block 11
Since a compressive force is positively applied to the upper end surface of the workpiece W from a in the forming process, it is possible to push in an excessive amount of material more than the material volume required for drawing. For this reason,
At the same time as forming the stepped cup-shaped bottomed cylindrical body 1 by drawing and forming the forming recess 1c in the workpiece W, the bottomed cylindrical body 1 is formed.
, For example, the thickness of the bottom wall 1a and the annular side wall 1b can be partially increased.

In this embodiment, the annular concave portion 11a provided in the killer block 11 is employed as a compressive force applying mechanism for applying a compressive force to the end surface of the workpiece W. It is also possible to adopt a sleeve punch or the like provided separately from the killer block 11 so as to be able to descend according to the advance into the hole 2d.

(Embodiment 4) This embodiment shown in FIG.
In the drawing apparatus according to the first embodiment, a tapered portion 2i is provided instead of the horizontal portion 2a of the fixed die 2.

That is, in the draw forming apparatus, a tapered portion 2i having an inclined surface that is inclined downward toward the center, that is, in the forming promotion direction, is provided at the upper end of the fixed die 2. The lower end of the pad 13 is also a tapered portion surface 13i corresponding to the tapered portion 2i.

The other structure is the same as that of the first embodiment.

Therefore, in addition to the functions and effects described in the first embodiment, the draw forming apparatus has the following functions and effects.

That is, in this drawing apparatus, the workpiece is placed on the ejector 4 in a state where the ejector 4 is raised until the upper end surface of the ejector 4 is substantially flush with the upper end of the tapered portion 2i of the fixed die 2. Set W. Thereafter, drawing is performed in the same manner as in the first embodiment.

The pad 13 is formed by the movable pad 10, and after the bottom wall 1b of the workpiece W comes into contact with the tapered portion 2i of the fixed die 2, the bottom wall 1b is removed together with the tapered portion 2i. What is necessary is just to lower so that it may be clamped by a predetermined pressure. In addition, the bottomed cylindrical body 1 ′ formed in this embodiment.
Is a tapered flange 1 instead of the bottom wall 1a and the annular wall 1b of the bottomed cylindrical body 1 formed in the first embodiment.
e.

By providing the tapered portion 2i integrally with the annular shoulder portion 2b forming the die hole 2d, an inclined surface is formed at the material inflow portion guided to the die hole 2d. The material is transferred from the tapered portion 2i to the die hole 2d.
It can be easily pushed into the inside, and the deformation resistance and friction resistance of the material can be reduced. Therefore,
The material of the workpiece W is more positively fed into the corners 10d of the molding recesses 10c formed by overhanging the tip shoulders of the movable punch 10, and cracks at the corners 10d are more reliably prevented, and the molding limit is reduced. Can be further improved.

In each of the above embodiments, an example has been described in which the stepped cup-shaped bottomed cylindrical body 1 is formed from the simple cup-shaped workpiece W, but the present invention is not limited to this. Not something.

For example, it is a simple cup having a bottom wall and an annular side wall integrally rising from an outer peripheral edge of the bottom wall, and
From a workpiece W forming a shallow, large-diameter bottomed cylindrical body, a simple cup-shaped, deep, small-diameter bottomed cylindrical body, or a simple cup-shaped having a bottom wall and an annular side wall. Workpiece W
From the above, an inverted hat-shaped bottomed tubular body having a horizontal flange portion extending further in the centrifugal direction from the end face of the annular side wall, or a simple cup-shaped bottomed tubular body from a flat workpiece W is formed. The present invention can be applied to molding and the like. Specifically, in the draw forming method described in the first embodiment, the depth of the die hole 2d is increased to increase the amount of pressing by the movable punch 10, thereby forming a simple cup-shaped, deep and small diameter. A bottomed tubular body or an inverted hat-shaped bottomed tubular body can be formed. When a simple cup-shaped bottomed cylindrical body is formed from a flat workpiece W, the movable die 14 is formed on the inner peripheral side of the fixed die 2 as in the draw forming apparatus described in the second embodiment. And a flat plate-shaped workpiece W is set on the horizontal portion 2a of the fixed die 2, and the outer peripheral edge of the workpiece W is drawn and formed while being sandwiched between the horizontal portion 2a and the pad 13a.

(Supplementary Note) The present invention has the following preferred embodiments.

(1) In the draw forming method according to the first aspect or the draw forming apparatus according to the second aspect, it works between the mold surface of the movable mold and the surface of the workpiece contacting the mold surface. By the frictional resistance, the material of the workpiece contacting the mold surface is supplied in the forming promotion direction.

(2) In the draw forming method according to the first aspect or the draw forming apparatus according to the second aspect, a simple cup-shaped bottom having a bottom wall and an annular side wall integrally rising from an outer peripheral edge of the bottom wall. Forming a concave portion on the bottom wall of the cylindrical body by molding, wherein the movable die is disposed on an outer peripheral side of a fixed die and is in contact with an outer peripheral surface of the annular side wall. It has a cylindrical shape with a surface (inner peripheral surface).

(3) In the draw forming method according to the first aspect or the draw forming apparatus according to the second aspect, the workpiece is subjected to draw forming to form a forming recess, and the movable die is fixed. It has a mold surface (inner peripheral surface) which is arranged on the inner peripheral side of the die and is in contact with the outer peripheral surface of the molding concave part which is molded by the movable punch and is being molded.

(4) In the draw forming method according to the first aspect or the draw forming apparatus according to the second aspect, a simple cup-shaped bottom having a bottom wall and an annular side wall integrally rising from an outer peripheral edge of the bottom wall. Forming a concave portion on the bottom wall of the cylindrical body, wherein the movable mold has a mold surface (outer peripheral surface) in contact with an inner peripheral surface of the annular side wall; It is a pad capable of performing a wrinkle preventing function by sandwiching an outer peripheral edge of the bottom wall of the workpiece together with the fixed die.

[0060]

As described in detail above, according to the drawing method and the apparatus according to the present invention, it is possible to form the workpiece while positively supplying the material of the workpiece by the movable die in the forming promotion direction. Therefore, it is possible to prevent cracks due to the concentration of tensile stress at the corners of the workpiece to be stretched and formed by the movable punch, and to improve the forming limit.

Further, if the material of the workpiece is supplied in the molding promoting direction, the deformation resistance of the material can be reduced, so that the molding load is reduced and the life of the molding die is improved, and the cost is also reduced. This is advantageous.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state before forming according to a drawing method and an apparatus thereof according to a first embodiment.

FIG. 2 is a cross-sectional view showing a state after forming, according to the draw forming method and apparatus of Embodiment 1.

FIG. 3 is a cross-sectional view showing a workpiece before molding and a bottomed cylindrical body after molding according to the drawing method and apparatus of Embodiment 1.

FIG. 4 is a cross-sectional view showing a fixed die, a movable die, an ejector, and the like in a state before forming according to the draw forming method and apparatus of Embodiment 1.

FIG. 5 is a cross-sectional view showing a state before forming, and a right half showing a state after forming, according to the draw forming method and apparatus of Embodiment 2.

FIG. 6 is a cross-sectional view showing a state after forming according to a draw forming method and a drawing apparatus of Embodiment 3.

FIG. 7 is a cross-sectional view showing a state after forming according to a draw forming method and a drawing apparatus of Embodiment 4.

FIG. 8 is a cross-sectional view showing a state after forming according to a conventional drawing method and apparatus.

[Explanation of symbols]

W ... Workpiece 1 ... Bottom cylindrical body 1a ... Bottom wall 1b ... Annular side wall 1c ... Molding recess 1d ... Corner part 2 ... Fixed die 2a ... Horizontal part 2b ... Annular shoulder part 2d ... Die hole 4 ... Ejector 5 ... 1st movable type 10 ... movable punch 11 ... killer block 13 ... pad 14 ... 2nd movable type

Claims (2)

[Claims] 1. A fixed die having an annular shoulder portion and a die hole formed in an inner peripheral surface of the annular shoulder portion, and a movable punch movable forward and backward with respect to the die hole, In a draw forming method for forming a bottomed cylindrical body by advancing and pushing the movable punch into the die hole of the fixed die, a self-molding surface is formed on the surface of the workpiece before or during molding. By moving a movable mold in contact with the movable punch in accordance with the advance of the movable punch, molding is performed while positively supplying a material of the workpiece in contact with the mold surface in a molding promotion direction. Drawing method. 2. A fixed die having an annular shoulder and a die hole formed on an inner peripheral surface of the annular shoulder, a movable punch capable of moving forward and backward into the die hole, and Or, during the molding, the surface of the workpiece comes into contact with the surface of the workpiece, and the material of the workpiece in contact with the surface of the workpiece is positively supplied in the molding promotion direction in accordance with the advance of the movable punch. And a movable mold which is movable.