JPH0761443B2 - Dome-shaped die, manufacturing method thereof, and die material used in the method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dome-shaped die used at the tip of an extrusion type granulator for granulating a powdered raw material in a wet state, a method for producing the same, and a die material used for the method. .

[0002]

2. Description of the Related Art A die for an extrusion type granulator includes (1) a flat die having a large number of small holes in a flat plate, and (2) a spherical portion disclosed in Japanese Patent Laid-Open No. 215832/1992. A dome-shaped die with many small holes was used. The former flat die was created by cutting from a punching plate in which a large number of small holes were arranged, or was formed from a flat plate in which a large number of small holes were provided by drilling.

Further, the latter dome-shaped die is roughly classified into the following three methods. (1) A circular plate cut from a punching plate is formed into a dome shape by drawing. (2) A thin metal plate is cut into a circular shape, deep-drawn into a dome shape by press working, and then a large number of small holes are formed in the dome-shaped portion by a beam method or electric discharge machining. (3) A development view (see FIGS. 11 and 12) of a dome-shaped die created by the meridian method and the parallel method is cut from a punching plate and formed into a dome shape by press bending, and then each joint is welded and others. Weld by means.

[0004]

As a recent tendency, various granules extruded by a granulator are required to have a small particle diameter in order to improve drug efficacy and dispersibility. In order to adjust to this tendency, when trying to obtain small granules with a diameter of 1 mm or less using the flat die, the plate thickness of the flat die should be as thin as the size of the die hole due to technical problems in drilling. Since the strength of the flat die is extremely low, it becomes difficult to mass-produce small granules.

Moreover, the size of the flat die attached to the opening of the tip of the extrusion type granulator is the same as the area of the opening of the granulator and cannot be made larger than that. In mass production, it becomes impossible to improve the productivity of the granulated product.

Further, when the latter dome-shaped die is used, there are the following problems depending on the manufacturing method of the dome-shaped die.

(1) When a circular plate cut from a punching plate is deep-drawn, at the dome-shaped crown, the punching holes receive tensile forces of substantially the same magnitude in two radial directions orthogonal to each other. Will be slightly larger. However, at the periphery of the dome-shaped opening, the punching hole receives a tensile force in the radial direction of the circular plate and a compressive force in the circumferential direction, so the punching hole is stretched in the radial direction and contracted in the circumferential direction. To form an elliptical hole that is long in the radial direction (see FIG. 13). For this reason, in the formed dome-shaped die, not only the size and shape of the die holes differ depending on their positions, but also the pitch between adjacent die holes becomes non-uniform, and granules with a sharp particle size distribution are created. I can't.

(2) When a die hole is formed on a hemispherical surface formed by deep drawing by an electron beam method or electric discharge machining, it is necessary to open several thousand to tens of thousands of die holes required for one die. The time becomes very long, and the processing cost becomes extremely expensive. Moreover, in the electron beam method, the equipment used is expensive, the operation must be performed in a vacuum chamber, and the shape of the hole becomes worse when trying to open a small hole of 1 mmφ or less at a high processing speed. However, this manufacturing method cannot provide a dome-shaped die suitable for practical use at low cost.

(3) When making a dome-shaped die using a development drawing by the meridian method or the parallel method, the development drawing is complicated and it takes a lot of time to make it, and the holes of the punching plate are cut by the development line. Since some holes are closed during welding, the effective area of the die hole that can be used for granulation decreases, and the productivity during granulation decreases (see FIGS. 11 and 12). Moreover, in the meridian method, the joint end is focused on the crown of the die-molded product, which makes positioning difficult during press bending work, and heat from welding etc. is repeatedly applied to the crown of the die. The strength of the die is weakened by heat deterioration. Further, in the parallel method, the development line formed in the radial direction and the circumferential direction becomes long, which makes it difficult to align the joining line during press bending, and the dome-shaped die has uniform strength. Is damaged.

The present invention has been made in view of these circumstances. The die holes on the entire surface have substantially the same size and shape, the drilling process is inexpensive, and a strong die can be provided at a low cost, and the particle size can be reduced. It is an object of the present invention to provide a dome-shaped die capable of efficiently producing even small-sized granules, a manufacturing method thereof, and a die material used in the method.

[0011]

The present invention has been made to achieve the above-mentioned object. In the first invention, a circular plate having a thin thickness is formed on a central portion and an annular portion outside the central portion by a set radius. A circular hole that is smaller than the die hole but has almost the same size as the die hole by drawing is formed by chemical etching on each circumference of the concentric circles formed in the center of the circular plate. A circular plate with a large number of holes is formed on each circumference of a group of concentric circles formed in the annular part of the Is formed into a dome-shaped die by drawing. The dome shape is preferably a hemispherical surface, but it also includes other shapes close to a hemispherical surface, for example, a semi-elliptical spherical shape, a partial spherical surface such as a 2/5 spherical surface, and the like. .

Further, in the second invention, the circular plate is cut from a punching plate having an intermediate thickness of 1 mm or slightly thicker, and the periphery of the circular plate is cut on a circle having a set radius within the circular plate. Providing three or more isosceles triangular notches with vertices at equal intervals, the joining lines of the notches joined by press bending are welded by welding or other means, and a punching plate with notches is dome-shaped. It is formed in a die.

According to the third aspect of the invention, isosceles triangular notches having apexes on the circumference of a set radius in the circular plate from the peripheral portion of the thin circular plate are formed at equal intervals.
Provide more than one, provide a large number of die holes by chemical etching method in the area excluding the band-shaped part of a certain size from each notch line, and weld the notch part joined by press bending by welding or other means. A circular plate having a notch is formed in a dome-shaped die.

[0014]

In the first aspect of the present invention, the large number of holes formed in the central portion of the circular plate and the annular portion on the outer side of the circular plate are different in size and shape in consideration of the amount of stretching and contraction received by the drawing process. Since it is determined, the die holes of the dome-shaped die have almost the same size and shape. Moreover, since the circular plate is drilled by the chemical etching method, it is possible to drill holes of various shapes with different sizes.
It can be done efficiently with a low processing cost.

In the second invention, the circular plate cut from the punching plate having the intermediate thickness has an isosceles triangular notch having an apex on the circumference of the set radius in the circular plate. Since three or more are provided at equal intervals,
When forming the circular plate into a dome shape by press bending, it became easy to align the joining line with a short length, and each hole of the punching plate with a small amount of deformation due to tension or compression was formed into a dome shape as it was. It becomes the die hole of the die.

Further, in the third aspect of the invention, an isosceles triangular notch is provided in the thin circular plate in the same manner as described in the previous section, and each notch line excludes a band-like portion having a constant inner dimension. Since a large number of holes are provided in the cut area, even if a circular plate with a notch is formed into a dome shape and the joint line at the notch is welded by welding, etc., there will be no welding defects in the joint line after welding. There is no space that causes the problem. Therefore, sufficient strength is imparted to the thin dome-shaped die.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments according to the present invention will be described below method by method with reference to the drawings. (1) When applying a drawing process to a circular plate (see FIGS. 1 to 3) The circular plate 1 required for the size of a dome-shaped die to be made from a thin metal plate (for example, 1 mm or less) Disconnect. A required number of concentric circles are formed in the circular plate 1 at a set pitch, and a group of these concentric circles is divided by a radius R of a certain size into a central circle and an outer annular portion. The radius R that divides the circular plate 1 into two parts is determined such that the number of concentric circles included in this circle is, for example, about 40% of the total number of rows.

On each circumference included in the circle at the center of the circular plate 1, a circular hole for a die hole, which is smaller than the size of the die hole 2 but has substantially the same size as the die hole 2 when subjected to deep drawing. 3 are provided with a set pitch. In addition, on each circumference included in the annular portion of the circular plate 1, the dimension a in the circumferential direction is larger than the dimension b in the radial direction, and the elliptical shape for the die hole becomes substantially the same size as the die hole 2 by drawing. The holes 3a are formed with a set pitch. In this case, the radial dimension b
Is approximately the same size as the circular hole 3 in the central portion, and is gradually decreased as the radius of the concentric circle increases, and the circumferential dimension a is a quadratic curve from approximately the same size as the circular hole 3. Will be increased.

In forming the holes of the size, shape, and pitch for the die hole on the circular plate 1, factors such as the kind of metal material used, the press conditions, the plate thickness, and the dome size are taken into consideration. It is determined experimentally, and the drilling process for the circular plate 1 is performed using a chemical etching method. According to this drilling method, a large number of die holes 3 having slightly different sizes and shapes can be machined in a stable state with extremely high accuracy and at low cost. The circular plate 1 that has undergone the drilling process is formed into a dome-shaped die by press drawing.

Next, the size and shape of the die hole 2 when making a dome-shaped die by this manufacturing method will be described. Table 1 shows the specifications of the dome-shaped die having a diameter D = 106 mm. Here, the aperture ratio F is the surface area S of the hemisphere (= πD ² /
Area S _h (= π) of the number N of die holes of diameter d with respect to 2)
d ² N / 4), F = 50N (d /
D) ² %.

[0021]

[Table 1]

When making 70 rows of dome-shaped dies satisfying the die hole diameter d = 0.5 mm in Table 1, 70 rows of concentric circles are formed on the circular plate 1 with the center A as the center. The design of the etching holes in the circular plate 1 is such that the size b in the radial direction on each concentric circle is approximately constant at b≈0.3 mm, and the size a in the circumferential direction is more outward from the center A as shown in FIG. As shown in Fig. 3, the quadratic curve is increased from 0.3 to 0.7 mm (see the dotted line in Fig. 3).

Therefore, the etching holes formed on the circumference of the concentric circle group of the circular plate 1 are 41 with respect to the total number of rows of 70.
% Up to the 30th row is a circle with a diameter of about 0.3 mm, and in the outer concentric circles, the size a in the circumferential direction is larger than the size b in the radial direction and is an ellipse. Become.

When the circular plate 1 provided with holes of various shapes by the chemical etching method is formed into a dome-shaped die having a predetermined size by press deep drawing, almost all the die holes are circumferentially sized a'and radially. The size b'of each is almost equal as shown by the solid line in FIG. 3, the die holes are circular with a diameter d of about 0.5 mm, and all the die hole sizes are within d ± 10% and their pitch p is in the range of 1.1 to 1.2 mm. The die hole size was measured using a microscope with a scale.

FIG. 10 shows a diameter D = 106 obtained by press deep drawing from a punching plate having the specifications shown in Table 2.
It is a comparative example showing changes in the size a ′ in the circumferential direction and the size b ′ in the radial direction with respect to the concentric circles when a dome-shaped die of mm is manufactured. In this comparative example, the number of rows of concentric circles is three.
When the number of rows is 0 or more, the difference between the a'and b'begins to suddenly increase and becomes an ellipse which is long in the radial direction and maintains the relationship of b '>a'.

[0026]

[Table 2]

By comparing the embodiment of the present invention shown in FIG. 3 with the comparative example shown in FIG. 10, in the case of making a dome-shaped die by deep drawing, the embodiment of the present invention has substantially the same shape and size. It is possible to understand how good it is to form a die hole having a large thickness.

(2) A case where the punching plate is produced by applying an approximate development method (see FIGS. 4 to 6). FIG. 4 is cut from a punching plate having a thickness of 1 mm or slightly thicker. It is one example of an approximate development view. This development view is formed by the following procedure.
Select a punching plate in which the punching hole at the center of bending is about the same size as the die hole when stretched by press bending, and draw a circle of the size required to make a dome-shaped die on this plate . A circle with a radius R is drawn with the center A in common within this circle. The size of the radius R is empirically determined in consideration of the range in which the expansion is performed substantially evenly when the circular plate is subjected to a drawing process for making it into a hemispherical shape (at the 30th row of the concentric circles in FIG. The corresponding radius is almost equivalent to this). This method has a pore size of 0.5
Applicable to those with punching holes of ~ 5mm,
More preferably, it is used for 0.8 to 3 mm.

The trisecting line R _1, R _2, R from the center A to the center angle
Subtract ₃ . The intersection points of the trisecting lines R _{1 to} R ₃ and the circle having the radius R are defined as B _1, B _{2 and} B ₃ . When the annular portion on the outside of the radius R is cut along the trisecting lines R _{1 to} R ₃ and is bent to form a dome shape, one of the overlapping portions of the annular portions is cut off. When this excision is equally divided into both sides of the trisecting lines R _{1 to} R ₃ , notched lines 4 and 4 (B ₁ C ₁ , B ₁ C ₆ etc.) having an isosceles triangular shape are formed. . Cut along these notches 4 and 4.

When the developed view formed by the above-described procedure is formed into a dome shape by press bending, the cutout line B
_As shown in FIG. 6, ₁ C ₁ and B ₁ C ₆ are B ₁ ′ C ₁ ′,
B ₁ 'C _6' and is bonded, bonded respectively the other two pairs of cut-line. The center A of the circular plate 1a becomes a spherical top A ', and the inside X of the radius R becomes a curved surface X'close to the spherical top A'.
A dome-shaped die is formed by welding the joining lines of the three notches by welding or other means.

The cutout line 4 in the development view is obtained by calculation by the method of approximate development. However, since the drawing and overhanging actions are involved in addition to bending during press forming, the type of metal material, press conditions, plate thickness, dome It is determined by experiment in consideration of factors such as shape size. The number of notches provided in the circular plate 1a is not limited to three, but it is preferable that the number of notches be three or more in order to facilitate press bending.

When the dome-shaped die is manufactured by this method, since the cutout lines 4 are not formed in the circle having the radius R, the positioning of each cutout line 4 during the press bending process becomes easy. In addition, since each joining line welded by means such as welding has a shorter length and does not have a convergent portion as compared with the conventional expansion method (see FIGS. 11 and 12), the cost required for welding is high. It is possible to save the cost, reduce the number of die holes to be closed at the time of welding, reduce the die ineffective area, and prevent thermal deterioration.

Moreover, the radius R and each notch line 4 in the circular plate 1a, when subjected to press bending, are the range in which the radial and circumferential expansions are evenly performed and the amount of contraction in the circumferential direction. Therefore, the dome-shaped die made of the punching plate is given a sufficiently uniform shape, size and pitch for each die hole 2. Since the punching plate has a thickness of 1 mm or an intermediate thickness slightly larger than that, even if the punching hole is cut by the notch line 4, it is possible to prevent welding defects from occurring at the time of welding the joining line. And TIG
Sufficient strength can be given to the dome-shaped die by overlaying it by a welding method or the like.

(3) A case where a circular plate is produced by applying an approximate development method (see FIGS. 7 to 9). FIG. 7 is an example of an approximate development view cut from a thin plate having a thickness of 1 mm or less. Here is an example. The formation of the approximate developed view by this method is performed according to the above-mentioned procedure for the punching plate. A circular hole is drilled in the circular plate 1b by a chemical etching method, but the area for designing the die hole pattern is a strip shape of a joint margin δ formed inside along each of the cut lines 4 and 4. Limited to parts excluding parts. The joining margin δ is set to about 1 to 3 mm in order to make the die effective area as large as possible.

The dome-shaped die is formed by forming the dome-shaped circular plate 1b, which has been drilled, into a dome shape by press bending, and welding the contact surfaces of the joining lines by welding or other means.

When a dome-shaped die is produced by this method, it is possible to prevent welding defects due to voids in the joint line after welding due to the action of the joint margin δ. Sufficient strength can be imparted. Other functions and effects are almost the same as those described in the case of making from the punching plate.

Next, changes in the shape and size of the hole for the die hole when the dome-shaped die having the specifications shown in Table 3 are manufactured by this manufacturing method will be described.

[0038]

[Table 3]

In the development view used to make the dome-shaped die, the radius R = 20 of the region where no bond line is provided.
mm, the diameter d ₀ = 0.5 mm of the holes formed in the circular plate 1 b, and the holes of the circular plate 1 b are formed by the chemical etching method with a pitch p = 1.2 mm and an equilateral triangle arrangement. As the joint margin δ, δ = 2 mm is selected. In this case, the theoretical aperture ratio F
Is F = 90.7 (d / p) ² ≈15.7%, but since the holes cannot be actually formed in the band-shaped part with the joint margin δ = 2 mm, the effective die area is slightly more than 15.7%. Get smaller. The value of R is 20 to 60% of the radius of the dome-shaped die.
Can be selected from the range of, but preferably 20-40
It is good to choose from the range of%.

A dome-shaped die is obtained by forming the dome-shaped circular plate 1b having the above-described structure into a dome shape by press bending and then welding each joining line by welding or the like. The measurement results of the size a'in the circumferential direction and the size b'in the radial direction of the obtained die hole are as shown in FIG. From this measurement result, it is understood that all die hole sizes are within d ± 10% of the die hole diameter d. Therefore, by using the dome-shaped die manufactured by this method, it is possible to efficiently mass-produce granules having a uniform particle size ratio.

[0041]

Since the present invention is configured as described above, it has the following operational effects.

In the dome-shaped die according to claim 1, the dome-shaped die having die holes of substantially the same shape and size is produced by subjecting a thin circular plate to chemical etching and press drawing. As a result, high-quality granules with a uniform shape and size can be efficiently
It can be mass produced.

In the dome-shaped die according to the second aspect, the dome-shaped die having die holes of substantially the same shape and size is made of a circular plate cut from a punching plate having an intermediate thickness. It is possible to efficiently mass-produce high-quality granules with a uniform shape and size by using a dome-shaped die that does not require drilling.

In the dome-shaped die according to the third aspect, the dome-shaped die having die holes of substantially the same shape and size is provided with three or more isosceles triangular notches formed in a thin circular plate. Since a band-shaped part of a certain size is provided inside the wire, a hole for a die hole is formed inside the band-shaped part by a chemical etching method, and the band-shaped part of the joining line is welded after press bending, so that By using a dome-shaped die in which welding defects do not occur in the joining line, it is possible to efficiently mass-produce a high-quality granulated product having a uniform shape and size.

In the method for manufacturing a dome-shaped die according to claim 4, the die hole is formed in the set circle in the central portion of the thin circular plate and the annular portion on the outside thereof when the die hole is drawn. Since a circular hole or an elliptical hole that has almost the same shape and size as that of No. 1 is formed by the chemical etching method, when this manufacturing method is used, the granules have a precise die hole and a uniform shape and size. It is possible to inexpensively provide a dome-shaped die that is suitable for practical use and that can efficiently produce objects.

In the method for manufacturing a dome-shaped die according to claim 5, an isosceles triangular shape having vertices on a circumference of a radius set from a peripheral portion of a circular plate cut from a punching plate having an intermediate thickness. Since three or more notches are provided, it is not necessary to process the holes for the die holes when using this manufacturing method, and the alignment during press bending is easy, and the welded portion of the joining line is It is possible to inexpensively provide a dome-shaped die suitable for practical use in which welding defects do not occur.

In the method of manufacturing a dome-shaped die according to claim 6, three isosceles notches each having an apex on the circumference of a radius set from the peripheral portion of a thin circular plate are provided. Since the holes for die holes are formed by the chemical etching method on the inside of the fixed dimension formed along each cutout line and welded at the joint margin along the cutout line, this manufacturing According to the method, alignment during press bending is easy, welding defects do not occur in the welded portion of the joining line, and a dome-shaped die having a highly accurate die hole and suitable for practical use can be provided at low cost. .

In the die material used for manufacturing the dome-shaped die according to the seventh aspect, a thin circular plate is subjected to a drawing process in a set circle in the central part and an annular part outside thereof. When the die material is used, a large number of holes required for a dome-shaped die can be created because circular holes and oval holes that have almost the same shape and size as the die holes are formed by the chemical etching method. It can be provided with high accuracy and at low cost.

In the die material used for manufacturing the dome-shaped die according to claim 8, the circular plate is cut from a punching plate having an intermediate thickness, and between the peripheral portion and the circumference of the set radius. Since three or more isosceles-shaped notches are provided at equal intervals, this die material eliminates the need for many holes for die holes required for a dome-shaped die. , The positioning at the time of joining becomes easy.

In the die material used for manufacturing the dome-shaped die according to the ninth aspect, an isosceles triangular cut is provided between the peripheral portion of the thin circular plate and the circumference of the set radius. Since three or more notches are formed at equal intervals and the holes for die holes are provided inside the strips of constant width along each notch line by the chemical etching method, using this die material, In addition to being able to accurately and inexpensively make a large number of holes for die holes, positioning at the time of joining can be facilitated and welding defects can be prevented from occurring on the joining line.

[Brief description of drawings]

FIG. 1 is a drawing showing a change from a development view to a molded article of an embodiment made according to the present invention.

FIG. 2 is a drawing showing a test circular plate and a dome-shaped die for examining a change in size of a hole for a die hole.

FIG. 3 is a diagram for measuring the relationship between the number of concentric circles and the size of a hole for a die hole when a dome-shaped die is made from the circular plate shown in FIG.

FIG. 4 is a plan view of a circular plate having a cutout portion cut from a punching plate used in another embodiment of the present invention (a hole for a die hole is shown largely).

5 is a plan view showing formation of a cutout portion in the circular plate of FIG.

6 is a perspective view of a dome shaped die made from the circular plate of FIG.

FIG. 7 is a plan view of a circular plate in which a joint margin having a constant width is formed along a cutout line used in still another embodiment of the present invention.

8 is a perspective view of a dome-shaped die made by press bending and welding from the circular plate of FIG.

9 is a diagram showing a relationship between the number of concentric circles and the size of a hole for a die hole when the dome-shaped die shown in FIG. 8 is produced from the developed view shown in FIG. 7.

FIG. 10 is a diagram showing a change in size of a die hole with respect to the number of concentric circles in a conventional dome-shaped die formed by drawing a circular plate of a punching plate.

FIG. 11 is a drawing showing a part of a developed view in which the surface of a hemisphere is approximately developed by a conventional meridian method.

FIG. 12 is a drawing showing a developed view in which the surface of a hemisphere is approximately developed by a conventional parallel method.

FIG. 13 is a view showing deformation of a circular hole when circular holes of the same size formed in a central portion and a peripheral portion of a circular plate are formed into a dome shape by drawing.

[Explanation of symbols]

1,1a, 1b circular plate 2 die hole 3,3a hole for die hole 4 notch line a size of hole for die hole in the circumferential direction b size of hole for die hole in the radial direction a'diameter of hole for the die hole b ′ Radial size of die hole δ Joining margin of constant width formed along the notch line R Radius of the central part where the notch line is not formed

Claims (9)

[Claims] 1. A dome-shaped die in which a thin circular plate having a large number of small holes formed at each set position by a chemical etching method is formed into a dome shape by drawing, and the circular plate is set. A circle that is divided into a center part and an outer ring part by the radius that is formed, and is smaller than the die hole on the circumference of each of the concentric circles formed in the center part of the circular plate, but is approximately the same size as the die hole by drawing. Holes are provided at a set pitch, and on each circumference of the concentric circles formed in the annular part of the circular plate, the circumferential dimension is larger than the radial dimension, which is smaller than the die hole. A dome-shaped die characterized in that oblong holes of approximately the same size are provided at a set pitch. 2. A circular plate having a large number of small holes is provided with three or more notches in the radial direction at equal intervals, and the abutting portions of the notches formed into a dome shape by press bending are welded or other means. Is a dome-shaped die welded together by means of a circular plate cut from a punching plate with an intermediate thickness of 1 mm or slightly thicker, and each radial notch has a constant length along the periphery of the circular plate. A dome-shaped die having a base and isosceles triangular shape having vertices on the circumference of a radius set concentrically with a circular plate. 3. A circular plate in which three or more radial notches are formed at equal intervals is provided with a large number of small holes, and abutting portions of the notches formed into a dome shape by press bending are welded or otherwise. It is a dome-shaped die integrally welded by means, the circular plate is formed by a thin metal plate with a thickness of 1 mm or less, and each radial cutout has a base of a certain length along the periphery of the circular plate. , Is an isosceles triangle with vertices on the circumference of a circle set concentrically with the circular plate, and small holes in the circular plate are chemically etched in the area where strips of a certain size are removed from each cutout line. A dome-shaped die characterized by being provided by the law. 4. A thin circular plate is divided into a central portion and an outer annular portion by a set radius, and a die hole is formed on each circumference of a group of concentric circles formed in the central portion of the circular plate. Circular holes, which are small but have almost the same size as the die holes by the drawing process, are provided at a pitch set by the chemical etching method, and the circumferential dimension is set on each circumference of the concentric circles formed in the annular part of the circular plate. , Smaller than the die hole, larger than the radial dimension, and provided with elliptical holes that are almost the same size as the die hole by drawing, at the pitch set by the chemical etching method, and by drawing the circular plate with many small holes A method for manufacturing a dome-shaped die, which is characterized in that the dome-shaped die is formed. 5. A circular plate is cut from a punching plate having an intermediate thickness of 1 mm or slightly thicker, and the base has a constant length along the peripheral portion in the radial direction of the cut circular plate as a base of a set radius. Three or more isosceles notches with vertices on the circumference are provided at equal intervals, and a circular plate provided with a plurality of notches is transformed into a dome shape and the isosceles facing each other at the notches. And a contact line of each notch is welded by welding or other means. 6. A thin circular plate having a base of a fixed length along the periphery and three or more equilateral triangular notches having vertices on the circumference of a set radius at equal intervals. Form a number of small die holes in the inner area by a certain dimension along each notch line by chemical etching method at the set related positions, and transform the circular plate with the die holes into a dome shape. A method for manufacturing a dome-shaped die, characterized in that isosceles portions of the cutout portions are brought into contact with each other, and contact lines of the cutout portions are welded by welding or other means. 7. A thin circular plate is divided into a central portion and an outer annular portion by a set radius, and a die hole is formed on each circumference of a group of concentric circles formed in the central portion of the circular plate. Circular holes, which are small, but have approximately the same size as the die hole by the drawing process, are provided at a set pitch. A die material used in the manufacture of dome-shaped dies, which has an oval hole that is larger than the small radial dimension and is approximately the same size as the die hole by drawing. 8. The circular plate is cut from a punching plate having an intermediate thickness of 1 mm or slightly thicker, and is set in the radial direction of the circular plate with a constant length along the periphery of the circular plate as the base. A die material used for manufacturing a dome-shaped die, characterized in that three or more isosceles triangular notches having vertices on the circumference of a radius are provided at equal intervals. 9. The circular plate is formed of a thin metal plate, and in the radial direction of the circular plate, a constant length along the periphery of the circular plate is taken as the base, and the circular plate has a set radius. Three or more isosceles notches with vertices are provided at equal intervals, and along the notches formed on the circular plate, a large number of areas are removed by chemical etching in the area excluding the band-like portions of a certain size. A die material used for manufacturing a dome-shaped die, characterized in that the die holes are provided at set arrangement positions.