JP2001225116A - Burring method, and die therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a burring method small in the number of forming dies and forming steps, and sufficiently high in height of a collar, and the dies therefor. SOLUTION: In a drawing and punching step, a metal sheet 58 is drawn to form a cylindrical recess 70 with the gradient 72 toward a center 71 of a bottom surface, and the center 71 of the bottom surface of the cylindrical recess 70 is punched to make a hole. In a hole-expanding step, the hole in the metal sheet 58 made in the drawing and punching step is expanded to form a cylindrical collar 73 around the expanded hole.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burring method for a burred metal plate used for interior parts of microwave ovens, interior parts and exterior parts of other home electric appliances, and a mold therefor. is there.

[0002]

2. Description of the Related Art In general, a burring-processed metal plate used for an interior part of a microwave oven, an interior part and an exterior part of other home electric appliances is, as shown in a perspective view of FIG. A cylindrical hole 3 is formed in the center of the cylindrical collar 3, and the cylindrical collar 3 rises from the circular hole 2 and surrounds the cylindrical collar 3 with a flange 4. The molding process is a burring process shown in FIG. As shown in (a), (b), (c) and (d) of the forming process diagram of the metal plate, the metal plate 1 shown in the process (a) is provided with a cylindrical concave portion in the process (b). In the step (c), the center 6 of the bottom surface of the cylindrical recess 5 is punched out to make a circular hole 2, and in the step (d), the cylindrical recess 5 is straightened to form a circular hole 2. Expand the cylindrical collar 3 and wrap around the cylindrical collar 3. And it forms a di 4.

FIGS. 7, 8, and 9 are side sectional views of dies used in each forming step of a metal plate having the above-described burring process, and FIG. 7 shows a drawing die used in a drawing step. 7 is a drawing punch fixed to the upper die holder 8, 9 is hung from the upper die holder 8 by a suspension bolt 10, and is urged downward by an upper spring 11 attached to the upper die holder 8, Stripper through which punch 7 penetrates, 1
Reference numeral 2 is fixed to the lower die holder 13, and a drawing die into which the drawing punch 7 enters, and 14 is suspended from the lower die holder 13 by the suspension bolt 15 and attached upward by a lower spring 16 attached to the lower die holder 13. The drawing die 1
The pad 17, which slides up and down in the inside 2, is placed on the upper surface of the drawing die 12 and the pad 14, and the drawing punch 7 descends.
A metal plate formed by drawing with the drawing die 12 and having a cylindrical concave portion 18 formed therein.

FIG. 8 shows a punching die used in the punching process. Reference numeral 19 denotes a punching punch fixed to an upper die holder 20, and 21 is suspended from the upper die holder 20 by a suspension bolt 22 and attached to the upper die holder 20. The stripper 24, which is urged downward by the upper spring 23 and penetrates the punch 19, is fixed to the lower mold holder 25,
A die 27 into which the lower central portion 26 of the stripper 21 enters is provided below the inside of the die 24, and together with the lowered punch 19, the cylindrical recess 18 of the metal plate 17 formed in the drawing step of FIG. This is a punching die for punching the bottom center 28.

FIG. 9 shows a hole expanding die used in the hole expanding step, 29 is a hole expanding punch fixed to the upper die holder 30, 31 is suspended from the upper die holder 30 by a suspension bolt 32, and The stripper, which is urged downward by the upper spring 33 attached to the hole and through which the hole expanding punch 29 penetrates, is fixed to the lower mold holder 35,
The hole expanding die 36 into which the hole expanding punch 29 enters is hung from the lower mold holder 35 by a suspension bolt 37, and is urged upward by a lower spring 38 attached to the lower mold holder 35, thereby forming the hole expanding die 34. A pad 39 which slides up and down inside is a cylindrical collar formed by expanding the hole at the center 28 of the bottom surface of the cylindrical concave portion 18 of the metal plate 17 by the hole expanding punch 29 and the hole expanding die 34.

[0007] The left half of FIG. 7 shows an initial state of the drawing step in which a metal plate 17 to be subjected to burring is placed on the upper surfaces of the drawing die 12 and the pad 14, and the upper half of the right half is lowered by the upper die holder 8. With the flange of the metal plate 17 held between the stripper 9 and the drawing die 12, the drawing punch 7 enters the drawing die 12, and the drawing punch 7 and the drawing die 12
8 shows the end state of the drawing step of forming the cylindrical concave portion 18 in the metal plate 17. The left half of FIG. 8 shows the center of the bottom of the cylindrical concave portion 18 of the metal plate 17 formed in the drawing step of FIG. 28, the upper right die holder 20 is lowered on the right half, and the stripper 21 is held in a state where the flange of the metal plate 17 is sandwiched between the stripper 21 and the die 24.
Of the metal plate 17 enters the die 24.
The hole punching punch 19 fixed to the upper die holder 20 is further lowered to make contact with the bottom center 28 of the cylindrical concave portion 18 and the punching step of punching out the bottom center 28 of the cylindrical concave portion 18 of the metal plate 17 is completed. The left half of FIG. 9 shows a cylindrical concave portion 18 of the metal plate 17 formed in the drilling step of FIG.
In the state immediately before expanding the hole at the center 28 of the bottom surface, the upper half holder 30 is lowered on the right half, and the cylindrical concave portion 18 of the metal plate 17 formed with the hole expanding punch 29 and the hole expanding die 34. 2 shows the end state of the hole expanding step of forming the cylindrical collar 39 by expanding the bottom surface of the cylindrical collar 39 to expand the hole.

[0007]

However, in order to apply a burring process to a metal plate by using the above-mentioned conventional die, it is necessary to provide a die for forming a cylindrical concave portion in the metal plate and a cylindrical concave portion. The mold for the drilling process for drilling holes on the bottom surface of the mold and the mold for the hole expanding process for expanding the holes on the bottom surface of the mold need three separately, and the molding process also requires three processes based on each mold. Was.

[0008] In addition, there is a problem that the volume of the cylindrical concave portion of the metal plate after the drilling step is limited in order to sufficiently increase the height of the collar of the metal plate subjected to the burring process.

The present invention solves the above-mentioned problems, and provides a burring method capable of sufficiently increasing the height of a collar with a small number of molding dies and a small number of molding steps, and a mold therefor. It is intended to do so.

[0010]

In order to solve the above-mentioned problems, the present invention provides a method for forming a metal plate in a drawing hole forming step.
A drawing process for forming a concave portion having a slope formed toward the center of the bottom surface and a punching process for punching the center of the bottom surface of the concave portion are performed, and in a hole expanding step, a hole of the metal plate processed in the drawing hole forming step is expanded. This is a burring method for forming a collar around an enlarged hole. The number of molding dies is small, the number of molding steps is small, and the height of the collar can be made sufficiently high.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is characterized in that, in the step of forming a drawing hole, a drawing process for forming a recess having a slope formed toward the center of the bottom surface of the metal plate, and a bottom surface of the recess. In the hole expanding step, a hole is formed in the metal plate processed in the drawing hole forming step, and a collar is formed around the expanded hole in a burring method. Since the metal plate is formed with a concave portion having a slope formed toward the center of the bottom surface, the hole is formed around the widened hole when the hole is expanded in the hole expanding step after the hole is formed in the center of the bottom surface of the concave portion. This has the effect of increasing the material volume of the metal that becomes the collar.

According to a second aspect of the present invention, there is provided a drawing punch having a concave portion forming a gradient toward the center on the drawing bottom surface in the upper die holder, a center penetrating the drawing punch, and An aperture die in which the height of the aperture punching bottom is fixed in the recess of the aperture punching bottom of the aperture punch, and the lower die holder, into which the aperture bottom of the aperture punch fixed to the upper die holder enters. In the center of the drawing die, there is a shoulder portion adapted to the gradient of the drawing bottom surface of the drawing punch fixed to the upper die holder, and the punching bottom surface of the punching punch fixed to the upper die holder enters. The hole expanding punch fixed to the drawing die and the upper die holder, which is formed by fixing the punching die to be formed, and the hole expanding punch fixed to the upper die holder enters the lower die holder. 2. A die for use in the burring method according to claim 1, comprising a hole expanding die formed by fixing an expanding die, wherein a drawing punch of an upper die holder and a drawing die of a lower die holder in a drawing hole die. Performing a drawing step of forming a cylindrical concave portion in the metal plate by using a punch for punching the upper die holder and a punching die for the lower die holder to form a hole in the cylindrical concave portion of the metal plate formed in the drawing process. Performing the process, the slope of the drawing bottom of the drawing punch of the upper die holder, and the shoulder of the punching die of the lower die holder that fits the cylindrical concave portion of the metal plate formed in the drawing process at the center of the bottom. It is formed into a concave part that forms a gradient toward the surface, and has the effect of expanding the hole of the cylindrical concave part of the metal plate formed by the drawing hole die using the hole expanding punch and the hole expanding die in the hole expanding die. That.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment) FIG. 1 is a side sectional view showing an initial state of a drawing hole forming step of a drawing hole forming die constituting a burring die according to an embodiment of the present invention, and FIG. 2 is a drawing showing the same drawing hole forming step. FIG. 3 is a side sectional view showing an initial state and an end state of a hole expanding step of a hole expanding die constituting a burring die according to an embodiment of the present invention, and FIG. In FIG. 2, reference numeral 40 denotes a drawing punch fixed to an upper mold holder 41 and having a concave portion 44 forming a gradient 43 toward the center on the drawing bottom surface 42.
5 is a punch which is fixed to the drawing punch 40 through the center thereof and whose height of the drilling bottom surface 46 fits into the concave portion 44 of the drawing bottom surface 42 of the drawing punch 40;
A stripper 47 is suspended from the upper mold holder 41 by a suspension bolt 48 and is urged downward by an upper spring 49 attached to the upper mold holder 41, and the stripper penetrates the aperture punch 40. 50 is fixed to the lower mold holder 51. The drawing die, into which the drawing punch 40 fixed to the upper die holder 41 enters, is connected to the lower die holder 5 by a suspension bolt 53.
1, the pad is urged upward by a lower spring 54 attached to the lower die holder 51 and slides up and down in the drawing die 50. 55 is a lower die holder in the center of the drawing die 50. A punching punch 45 fixed to the upper die holder 41 and having a shoulder 56 adapted to the slope 43 of the drawing bottom surface 42 of the drawing punch 40 fixed to the upper die holder 41 and fixed to the upper die holder 41. A punching die into which the bottom surface 46 enters is shown by 57 in FIG.
Are the drawing die 50 and the pad 5 on the lower mold holder 51 side.
2 is a metal plate which is placed on the upper surface of the burring process, and 58 in FIG. 2 is a metal plate 57 in FIG.
Shows the shape after the drawing is performed.

In FIG. 3, reference numeral 59 denotes a hole expanding punch fixed to the upper die holder 60, and 61 denotes a hole extending from the upper die holder 60 by a suspension bolt 62, and a downward direction by an upper spring 63 attached to the upper die holder 60. A stripper which is urged and through which the hole expanding punch 59 penetrates, 64 is fixed to a lower die holder 65, a hole expanding die into which the hole expanding punch 59 enters, and 66 is a lower die holder 6 by a suspension bolt 67.
5 is a pad which is suspended upward from the hole expansion die 64 and is urged upward by a lower spring 68 attached to the lower die holder 65.

With the burring mold having the above-described structure,
In order to apply burring to the metal plate, the flat metal plate 57 of FIG. 4A in the forming process diagram of FIG. 4 is shown in a side sectional view of the initial state of the drawing hole forming process of the drawing hole forming die shown in FIG. As described above, the drawing die is placed on the drawing die 50 on the lower mold holder 51 side and the pad 52 on the lower die holder 51 side, and is clamped between the drawing die 50 and the stripper 47 on the upper die holder 41 side descending. As the mold holder 41 further descends, the drawing punch 40 of the upper mold holder 41 is moved to the position of the lower mold holder 51 as shown in the side sectional view of the drawing hole punching die shown in FIG. After entering the drawing die 50, at this time, the punching die 5 on the lower mold holder 51 side is formed.
The drawing punch 4 on the upper die holder 41 side where the height of 5 is lowered
Since the drawing bottom surface 42 is set to be higher than the bottom dead center by α, the flat metal plate 57 placed on the drawing die 50 and the pad 52 is combined with the action of the shoulder 56 of the punching die 55. The shape is drawn along the concave portion 44 forming the gradient 43 toward the center of the drawing bottom surface 42 of the drawing punch 40, and is formed around the flange 69 like a metal plate 58 in FIG. Is formed, and the bottom center 71 of the cylindrical recess 70 is raised by a slope 72.

At this time, since the bottom center 71 of the cylindrical concave portion 70 of the metal plate 58 is raised by the gradient 72, the bottom surface 46 of the punch 45 on the side of the upper die holder 41 which has been lowered. Height is squeezing punch 40
Even before the drawing process is completed, the center 71 of the bottom surface of the metal plate 58 by the punching bottom surface 46 of the punch 45 and the punching die 55 of the lower die holder 51 before the drawing process is completed. Drilling has been completed.

Next, as shown on the left side of the sectional side view of FIG. 3, the metal plate 58 of FIG. 3, the upper die holder 60 is lowered, and the flange 69 of the metal plate 58 is sandwiched between the stripper 61 and the hole expanding die 64, as shown on the right side of the sectional side view of FIG. By lowering the mold holder 60, the hole expanding punch 59 on the upper mold holder 60 side moves the lower mold holder 6.
5A, the cylindrical recess 70 having the remaining slope 72 is vertically extended on the bottom surface of the metal plate 58 to perform hole enlargement. As shown in FIG. 6
9 to form a cylindrical collar 73.

As described above, according to the drawing die of the present embodiment, the height of the punching die 55 on the lower die holder 51 side is reduced to the drawing punch 40 on the lower die holder 41 side. The height of the bottom surface 42 is set to be higher than the bottom dead center by α, and the shoulder 56 of the punching die 55 and the slope 43 of the drawing punch 40 toward the center of the drawing bottom surface 42 make the center of the bottom of the cylindrical concave portion 70 of the metal plate 58. Since the base 71 is raised by the slope 72, drawing and drilling can be performed in one drawing die, and drawing and drilling can be performed, as compared with the case where two separate dies are conventionally required. Is given,
When the remaining bottom surface of the slope 72 of the metal plate 58 having a hole formed in the center 71 of the bottom surface of the cylindrical recess 70 is vertically extended by a hole expanding mold, the bottom surface of the cylindrical recess 70 has no slope 72. Since the volume of the material of the metal plate 58 is larger than that of the flat case, the height of the cylindrical collar 73 around the flange 69 can be made sufficiently large.

[0020]

As described above, according to the burring method of the present invention and the mold thereof, the number of forming dies can be reduced because the drawing hole drilling step of the metal plate is performed in the same mold. Thus, the working steps can be shortened, and the effect of sufficiently increasing the height of the collar of the metal plate on which burring has been performed can be obtained.

[Brief description of the drawings]

FIG. 1 is a side sectional view of an initial state of a drawing hole forming step of a drawing hole forming die constituting a burring die according to an embodiment of the present invention.

FIG. 2 is a side cross-sectional view showing an end state of a drawing hole forming step of the drawing hole forming die constituting the burring processing die according to the embodiment of the present invention.

FIG. 3 is a side cross-sectional view showing an initial state and an end state of a hole expanding step of a hole expanding die constituting the burring die according to the embodiment of the present invention.

FIG. 4 is a molding process diagram of burring processing using a burring die according to the embodiment of the present invention.

FIG. 5 is a perspective view of a burring-processed metal plate.

FIG. 6 is a molding process diagram of a burring process using a conventional burring die.

FIG. 7 is a side sectional view of a drawing die constituting a conventional burring die.

FIG. 8 is a side sectional view of a punching die constituting a conventional burring die.

FIG. 9 is a side cross-sectional view of a hole expanding die that constitutes a conventional burring die.

[Explanation of symbols]

1, 17, 57, 58 Metal plate 2 Circular hole 3, 39, 73 Cylindrical collar 4, 69 Flange 5, 18, 70 Cylindrical recess 6, 28, 71 Bottom center 7, 40 Aperture punch 8, 20, 30 , 41, 60 Upper die holder 9, 21, 31, 47, 61 Stripper 10, 15, 22, 32, 37, 48, 53, 62, 6
7 Hanging bolts 11,23,33,49,63 Upper spring 12,50 Aperture die 13,25,35,51,65 Lower mold holder 14,36,52,66 Pad 16,38,54,68 Lower spring 19, 45 Drilling punch 24 Die 26 Lower central part 27,55 Drilling die 29,59 Drilling punch 34,64 Drilling die 42 Draw bottom 43,72 Slope 44 Recess 46 Drill bottom Bottom 56 Shoulder

Claims (2)

[Claims] In the drawing hole forming step, a drawing process for forming a concave portion having a slope formed toward the center of the bottom surface of the metal plate and a hole forming process for punching the center of the bottom surface of the concave portion are performed. A burring method in which a hole in the metal plate processed in the drawing hole forming step is expanded and a collar is formed around the expanded hole. 2. A drawing punch having a concave portion forming a gradient toward the center of a drawing bottom surface in an upper die holder, and a height of the drawing punch penetrating through the center of the drawing punch and having a drilling bottom surface. The punching die which fits in the concave part of the drawing bottom surface is fixed, the drawing die into which the drawing bottom of the drawing punch fixed to the upper die holder enters the lower die holder, and the inside of the center of the drawing die, It has a shoulder portion adapted to the gradient of the drawing bottom surface of the drawing punch fixed to the upper die holder, and is configured by fixing a punching die into which the drilling bottom surface of the punching punch fixed to the upper die holder enters. For squeezing hole mold and upper mold holder,
2. The burring method according to claim 1, comprising a hole-expansion die, wherein the hole-expansion punch is fixed, and a hole-expansion die, into which the hole-expansion punch fixed to the upper die holder enters, is fixed to the lower die holder. Mold used for