JPH0671634B2 - Drawing method of metal plate - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for drawing a metal plate by a press, and in particular, a circular metal plate is formed into a cylindrical container with a pair of punch dies without using a plate holder. The present invention relates to a drawing method.

Conventional technology and its problems As for the drawing process of a metal plate, basically, as shown in FIG.
Is set on a ring-shaped die 17 having a conical slope (a in the figure), the punch 16 is lowered from above, and narrowed down through a die shoulder 12 (b). FIG. 7C shows a state where the narrowing has been completed, and a semi-finished container 25 having the shape of the punch 3 is obtained. After the semi-finished product 25 is extracted from the punch 16, the opening 13 is cut and aligned at a predetermined height, and if necessary, a cutting process is performed with the outer diameter and the wall thickness as product dimensions to obtain a finished product.

However, the drawing process shown in FIG. 4 has two problems to be avoided. One is the fracture 14 of the semi-finished product 25 shown in Fig. 5a,
The other is the wrinkle 15 shown in FIG.

As a method of preventing the rupture 14, an outer diameter D ₀ and the upper limit to the ratio of the outer diameter D ₁ of the punch _{16 α (D 0 / D 1} ) of the blank 11 (typically about 2) is provided, and the narrowing easily For dice shoulder 12
This can be dealt with by increasing the roundness radius R of No. 1 and lubricating the die 17.

On the other hand, the largest factor affecting the wrinkles 15 is the ratio β (t ₀ / D ₀ ) of the plate thickness t _{0 of the} blank 11 and the blank outer diameter D ₀ , and the lower limit of β is usually 0.02. The blank thickness t ₀ is expected to be thinned by drawing, and it is usually sufficient to set 1.1 to 1.2 times the minimum thickness required for the product container.
Depending on the size of D _0, an unnecessarily thick blank must be used to prevent the above-mentioned wrinkles, and in the case of a thin product container, the yield will be significantly reduced.

The blanking method shown in FIG. 6 is applied to the blank size which causes wrinkles in the blanking using the punch 16 'and the die 17' shown in FIG. This method uses blank 11 '
On the die 17 ', lower the plate holder 18 and
Surface pressure is applied to 1 '(a in the same figure), and in that state, the punch 16' is lowered and narrowed down (b in the same figure) to obtain a semi-finished container 25 '(c in the same figure). In this method, the blank 11 'is the plate retainer 18
Since the drawing process is performed in a state of being constrained by, the wrinkles 15 as shown in FIG. 5 do not occur.

However, in the case of drawing using this plate retainer 18,
The reduction rate of the wall thickness of the semi-finished container 5 is larger than that of the method without using the plate retainer 9, the hot working requires a great deal of work, and the expensive double-action that can independently operate the punch 3 and the plate retainer 9. The mechanism requires a press mechanism.

That is, the decrease rate of the wall thickness becomes large because (a) the friction force by the plate retainer 18 is newly added, and (b) the bending angle θ '(90 degrees) at the die shoulder 12' is shown in FIG. Dice shoulder
Less than bending angle θ at 12, (C) Die shoulder 12 '
Shoulder radius R'to prevent wrinkling at the die
Because it must be smaller than the radius R of 12.

Further, the hot working requires a great deal of labor for the following reason. In the case of hot working, the heat of the blank 11 'is absorbed by the die 17' and the plate retainer 18 at the stage of Fig. 6a, causing the temperature to drop, and the deformation resistance accompanying narrowing increases, while the die 17 'plate Since the temperature drop in the central portion that does not contact the presser 18 is small, the increase in deformation resistance is small. As a result, the thickness of the central portion is significantly increased and the risk of breakage is increased.

As a countermeasure against this, a multi-step molding method is usually adopted in which the molding is interrupted midway, and the molding is continued after the reheating. For this reason, the number of man-hours required for hot working increases, which is uneconomical in terms of thermal energy.

Further, the double-acting press is necessary to use the plate retainer 9, and the equipment cost is high.

As a forming method using a double-acting press, there is known a method of forming a blank by covering it with a heat insulating material (for example, JP-A-54-131559) in order to solve the above-mentioned problems. The problem of the rate of thickness reduction cannot be solved.

OBJECT OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and a single-action press can be used to form a high-quality cylindrical container without wrinkles and breaks without using a plate retainer at a high yield. It is intended to propose a drawing method for a metal plate.

Configuration of the Invention A drawing method of a metal plate according to the present invention is a drawing method of forming a circular metal plate as a material into a cylindrical container with a pair of punch dies without using a plate retainer. It is sandwiched between two metal plate covers in close contact with each other, and the peripheral portions of the metal plate covers are welded and integrated directly or through a metal ring to form an assembly blank, and this assembly blank includes the entire thickness of the material metal plate. The thickness is 0.02 times or more the diameter of the metal plate cover, and the plate thickness of the metal plate cover on the side that contacts the punch is 0.01 times or more the diameter of the metal plate cover, and the assembly blank is hot or The gist is to perform the forming in the cold.

A method of sealing a raw metal plate with a metal cover and performing drawing is disclosed in, for example, JP-A-51-12374 and JP-A-52-120269. By filling with a fluid filler at
It is intended to prevent deterioration of the surface layer of the metal plate at high temperature due to oxidation, etc.The cover itself does not have the function of preventing wrinkles due to drawing processing, so it is necessary to form it using a plate retainer. .

Hereinafter, the method of the present invention will be described in detail.

FIG. 1 shows a sectional structure of an assembly blank according to the present invention. FIG. 1A shows a metal plate cover 2 on both sides of a raw metal plate 1.
1 and 2-2 shows an assembled blank that is sandwiched between 1 and 2-2 in a hermetically sealed state, and the outer edge portions of both metal plate covers are welded and integrated via the metal ring 3, and FIG. B is an assembled blank that is integrated without using the metal ring 3. The metal plate covers 2-1 ′ and 2-2 ′ having the recesses 4 capable of accommodating the material metal plate 1 are used to surround the material metal plate 1 with both metal plate covers. The outer edge portion of is welded and integrated.

In the assembly blanks 5 and 5 ′ shown in FIG. 1, the total thickness T including the plate thickness t ₀ of the raw metal plate 1 is 0.02 of the assembly blank diameter D.
The plate thickness t of the metal cover 2-1 on the side that contacts the punch during drawing is 0.01 times the assembly blank diameter D.
It satisfies the condition of being more than double.

Thus, the ratio of the total thickness T of the assembly blank to the diameter D (T /
D) 0.02 times or more, metal plate cover on the side that contacts the punch 2
The reason for limiting the ratio (t / D) of the plate thickness t and the diameter D of -1 to 0.01 or more will be described in detail below.

In the drawing of a metal plate, a portion of the metal plate blank having a diameter larger than the product outer diameter (die inner diameter) receives a compressive stress in the circumferential direction, and this compressive stress becomes maximum at the outer edge portion of the blank. In the drawing without using the wrinkle retainer, the metal plate blank itself must have a rigidity that does not buckle due to this compressive stress, and a plate thickness corresponding to the outer diameter of the blank is required.

In the present invention, the material metal plate 1 as shown in FIG.
Since the assembly blank 5 that covers both sides and the outer edge portion is used, the condition setting for preventing wrinkles in the drawing process becomes complicated.

That is, not only the part itself excluding the material metal plate 1 from the assembly blank 5 does not buckle, but also the material metal plate 1 must be restrained from buckling from both sides. In order to find a condition for preventing wrinkles, the present inventors repeated experiments on the structure and total thickness T of the assembly blank 5 and the required plate thickness of the metal plate cover at the upper and lower positions of the raw metal plate 1 I obtained the following knowledge.

The buckling phenomenon in which the entire thickness of the assembly blank undulates occurs from the peripheral edge portion like the single metal plate. As shown in FIG. 1, the peripheral edges of the metal plate covers are firmly welded and integrated directly or through a metal ring to make the total thickness T 0.02 times or more the diameter D of the assembly blank. It can be prevented.

Although the wrinkles on the periphery of the assembly blank can be prevented by the above measures, wrinkles as shown in FIG. 7 occur on the metal plate cover inside the periphery, that is, in the vicinity of the periphery of the raw metal plate. This is because a compressive stress in the circumferential direction is generated in the area inside the peripheral edge of the metal plate cover, and the peripheral edge of the stored metal plate causes the metal plate cover to wavy as it tries to buckle. It is due to such a force acting. The wrinkles of the metal plate cover occur on the metal plate cover on the punch side, which is a free surface without constraint by the mold, and do not occur on the metal plate cover on the side of the die pressed against the die. In order to prevent this wrinkle, the thickness t of 2-1 of the punch side metal plate cover immediately above the material metal plate 1 shown in FIG.
It should be 0.01 times or more. In terms of the ratio with D, the thickness may be smaller than the total thickness T because wrinkle generation is suppressed by the peripheral portion that does not buckle.

The materials of the metal plate covers 2-1, 2-2 and the metal ring 3 are not particularly limited, but inexpensive carbon steel can be used.

FIG. 2 shows the assembly blank of the present invention as a pair of punches 6.
And the state in which the die 7 is drawing without pressing the plate. At this time, the material metal plate 1 is pressed against the metal plate cover 2-2 by the metal plate cover 2-1 and wrinkles do not occur. In the case of hot working, the metal plate covers 2-1 and 2-2 have a role of suppressing the temperature decrease of the raw metal plate 1.

FIG. 3 shows a molded product which has been drawn by the method of the present invention, and FIG. 3a shows a molded product of the assembly blank 5'in which the metal plate covers 2-1 and 2-2 are welded using a metal ring. FIG. 2B shows a molded product of an assembly blank 5'in which a metal plate cover with a recess is used to surround a raw metal plate without using a metal ring. These molded products 35, 35 'are cut and separated from the cutting line 8 by gas cutting, plasma cutting, mechanical cutting, etc.,
Inner and outer metal plate covers 2-1, 2-2, 2-1 ', 2
You get the product by removing -2 '.

Examples Example 1 Duplex stainless steel plate (22% Cr, with a plate thickness of 10 mm and a diameter of 620 mm)
5.5% Ni, 3% Mo) with 10mm thickness, 670mm outer diameter, 625mm inner diameter
Inserted SS41 carbon steel ring of, the conditions shown in Table 1,
Weld the entire circumference of the SS41 metal plate cover with a plate thickness of 670 mm and the ring to form an assembly blank, and heat the blank.
It was heated to 1100 ° C., and punch-molded into a hemispherical bottom container having an outer diameter of 440 mm without using a punch die to hold a wrinkle. The results are shown in Table 2.

As shown in Table 2, under the conditions, wrinkles were formed on the punch-side cover inside the peripheral portion, and wrinkles were also formed on the duplex stainless steel product container. On the other hand, under the conditions, the wrinkle of the punch side cover was not seen, and it was possible to obtain a duplex stainless steel hemispherical container having a good shape and an outer diameter of 425 mm and a minimum wall thickness of 9 mm.

On the other hand, when the same product is formed from a single duplex stainless steel plate, a material with a plate thickness of 12.6 mm must be used from the viewpoint of preventing wrinkles, and the method of the present invention improves the yield by 26%. . Further, in order to prevent rupture due to a temperature decrease during forming, when forming a duplex stainless steel sheet alone, it was necessary to form twice including reheating, but in the method of the present invention, it is wrinkle formed once. A product without breakage was obtained.

Example 2 Titanium alloy plate (6% Al, 4% V) having a plate thickness of 2 mm and a diameter of 480 mm
With a diameter of 520 mm and a plate thickness of 7 mm and 8 mm SS41 disk concentric diameter 4
It is housed in a punch side cover with a recess of 85 mm and a depth of 2 mm processed, and a die side cover with a diameter of 520 mm and a plate thickness of 3 mm is welded to the entire outer circumference, and the blank shown in Table 3 is used as the assembly blank. It was heated to a temperature of 850 ° C., and was punch-molded into a hemispherical bottom container having an outer diameter of 324 mm without using a punch die to hold a wrinkle. The results are shown in Table 4.

As shown in Table 4, under the conditions, wrinkles were generated on the peripheral edge of the assembly blank, and wrinkles were also generated on the punch side cover inside the peripheral edge, and press molding was unsuccessful. On the other hand, no wrinkles were observed under the conditions and a titanium alloy hemispherical container having an outer diameter of 319 mm and a minimum wall thickness of 1.8 mm having a good shape could be obtained.

EFFECTS OF THE INVENTION As described above, according to the method of the present invention, it is possible to draw-mold a wrinkle-free cylindrical container with a pair of punch dies without using a plate retainer for preventing wrinkles. Even if the material metal plate is thin, it is possible to manufacture a cylindrical container with no wrinkles and breaks with a high yield, and it is possible to perform multiple times of molding and single-action press molding once without the need for heating. Therefore, the manufacturing cost can be reduced.

[Brief description of drawings]

1A and 1B are vertical sectional views showing an assembly blank according to the present invention, FIG. 2 is a vertical sectional view showing a state where the assembly blank is drawn, and FIG. 3A and FIG. A longitudinal sectional view showing the molded product after completion, FIGS. 4 a, b, c are longitudinal sectional views showing a basic drawing method of a metal plate, and FIG. 5 is a defective semi-finished product manufactured by the same drawing method. In the figure,
FIG. 6A is a perspective view showing a semi-finished product in which breakage has occurred, FIG. 6B is a perspective view showing a semi-finished product in which wrinkles have occurred, and FIG. FIG. 7 is a diagram showing a wrinkle occurrence situation. 1 …… Material Metal plate 2-1, 2-2 …… Metal plate cover 3 …… Metal ring 4 …… Concave 5,5 ′ …… Assembly blank 6 …… Punch 7 …… Die 8 …… Cutting line 14… … Break 15,15 ′ …… Wrinkle

Claims (1)

[Claims] 1. A drawing method in which a circular metal plate is used as a material and is formed into a cylindrical container by a pair of punch dies without using a plate retainer. In the drawing method, the material metal plate is closely attached with two metal plate covers. The metal plate cover is sandwiched, and the peripheral portions of the metal plate covers are welded and integrated directly or via a metal ring to form an assembly blank. This assembly blank has a total thickness including a plate thickness of a raw metal plate and a diameter of the metal plate cover. It has 0.02 times or more, and the plate thickness of the metal plate cover on the side that contacts the punch is 0.01 times or more the diameter of the metal plate cover, and the assembly blank is formed hot or cold. Method for drawing metal plate.