JP2001191123A - Bottomed part and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bottomed part free from the influence of a chamfered part of a corner part and its manufacturing method. SOLUTION: An annular recessed part 32 is arranged in the outer edge part of a bottom face 31Bb of a bottom part 31B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bottomed part and a method of manufacturing the same, and more particularly, to a bottomed part suitable for a metal case of an electret condenser microphone accommodating other parts therein and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, bottomed parts formed into a bottomed cylindrical shape have been used as parts of various kinds of products.

A product using such a bottomed component will be described with reference to a small electret condenser microphone (ECM) frequently used in mobile phones and the like.

FIG. 10 shows a main part of a conventional electret condenser microphone. This electret condenser microphone 1 has a face cloth 2, a metal case 3 as a bottomed part having a sound hole 3a, and an inside of the metal case 3. An annular membrane ring 4 for holding a vibrating membrane,
A flat disk-shaped vibrating membrane 5 made of an electret material having a metal layer formed on the surface of a polymer film by vapor deposition or the like;
Annular gap spacer 6, fixed electrode 7, concave insulator 8, IC 9 composed of FET, and printed circuit board 1
0. And the fixed electrode 7 and the IC 9
The IC 9 is electrically connected by the input lead 9a.
The printed circuit board 10 and the conductive circuit pattern (not shown) are electrically connected by output leads 9b. The fixed electrode 7, the insulator 8, the IC 9, and the printed circuit board 10 are inserted into the metal case 3 as one amplifier block, and are fixed by the caulked portion 3b of the metal case 3. A front air chamber 11 is formed by the internal space of the membrane ring 4, and a back air chamber 12 is formed by the concave internal space of the insulator 8.

In such an electret condenser microphone 1, a membrane ring 4, a diaphragm 5, a gap spacer 6, and an amplifier block are inserted and stored in this order inside a metal case 3 as a bottomed component. The right side, which is the free end of the cylindrical side wall 3A, is crimped inward to form a caulked portion 3b and fixed, and then the face cloth 1 is fixed to the outer surface of the bottom 3B of the metal case 3 to be manufactured. I have.

[0006] The metal case 3 as the bottomed part is shown in FIG.
As shown in the figure, the outer dimensions including the cylindrical side wall portion 3A and the bottom portion 3B are formed in a bottomed cylindrical shape having a diameter of about 6 mm, and a sound hole 3a is formed in the center of the bottom portion 3B. A through hole 3Ba penetrating in the thickness direction is formed.

As a method of manufacturing the metal case 3 as a bottomed part, as shown in FIG. 12, a metal material 17 is formed by using a punch 15 and a die 16 installed in a molding machine such as a press (not shown). The production method of plastically deforming into a cylindrical shape with a bottom by drawing processing has high production efficiency,
It is widely used because it can easily realize a low price. In general, a drawing die, a punching die, a punching die, and the like are installed in a press in order, and a material 17 such as a band-shaped hoop material or a long flat plate-shaped sketch material is drawn and formed by the drawing die. It is manufactured by continuously performing a processing step of forming a sound hole 3a with an opening die and separating the product from the material with a punching die.

Since the metal case 3 is manufactured by drawing, as shown in an exaggerated manner in FIG. 13, a corner 3Bc located at a connection portion between the cylindrical side wall 3A and the bottom 3Bb of the bottom 3B is formed. The shape of the chamfered portion 18 formed in a round shape of, for example, about 0.1 mm is indispensable, although it depends on the material and the thickness of the material 17 in order to prevent the occurrence of cracks which are said to be broken. The size of the chamfered portion 18 of the corner 3Bc of the metal case 3 is determined by the size (radius dimension) of the corner radius 15a formed on the periphery of the opposing surface of the punch 15 shown in FIG. ) And the magnitude of the springback after the material 17 is plastically deformed.

As a method of manufacturing the annular membrane ring 4 housed in contact with the bottom surface 3Bb of the metal case 3, as shown in FIG. 14, a punch for punching installed in a molding machine such as a press (not shown) is used. The manufacturing method in which a metal material is punched in a ring shape (annular shape) by a punching process of shearing a metal material using the punching die 20 and the die 21 can easily realize high production efficiency and low cost. Often used for reasons. In general, press
By installing one or more punching dies for punching the inner and outer diameters, and punching a material such as a strip hoop material made of metal or a long flat plate sketch material in an annular or single operation or multiple times Being manufactured.

Since the membrane ring 4 is manufactured by punching, as shown in an exaggerated manner in FIG. 15, the die side located on the downstream side of the punching punch 20 in the punching direction indicated by an arrow in FIG. (Burr) 4a is generated at the cut edge, and burr 4b is generated at the punch cut edge located on the upstream side in the punching direction. This return 4b
Is a cause of various inconveniences. Therefore, the burr 4b is suppressed by a precision shearing process such as a finishing punching method, a precision punching method, and a facing die shearing method, and as shown in FIG. A right-angled corner 4c is formed in the cut on the die side.

[0011]

By the way, in the electret condenser microphone 1, it is necessary to form the bottom surface 3Bb of the metal case 3 and the membrane ring 4 so as to make uniform surface contact. Is important in reducing the variation of

However, in the conventional metal case 3 described above, since the chamfered portion 18 of the corner 3Bc is formed in a round shape or the like, when the film ring 4 is inserted and fixed in the metal case 3, When the center of the membrane ring 4 is located at the center of the metal ring 3, and when the surface of the metal ring 3 on which the droop 4a is formed faces the bottom surface 3Bb of the metal ring 3, the bottom surface 3Bb of the metal case 3 17 can be easily obtained, and there is no problem.
As shown in FIG.
When the surface on which the right-angled corners 4c are formed faces each other and the center of the membrane ring 4 is greatly displaced from the center of the metal case 3, the right angle of the membrane ring 4 is The corner 4c contacts the bottom surface 3B of the metal case 3.
b, the film ring 4 is fixed in a state of being inclined or floating, and the surface ring 3 cannot be uniformly contacted with the bottom surface 3Bb of the metal case 3 and the sound pressure of each product is increased. However, there is a problem that the variation in the sensitivity is large.

In order to deal with such a problem, an identification mark may be provided on one of the front and back surfaces of the membrane ring 4 to control the direction in which the membrane ring 4 is inserted into the bottom surface 3Bb of the metal case 3. In order to efficiently control the front and back of the membrane ring 4 at the time of insertion, the front and back of the membrane ring 4 must be managed, and a dedicated device for identifying and aligning the front and back of the membrane ring 4 is required, and the manufacturing cost is reduced. To increase.

Therefore, regardless of the direction in which the membrane ring 4 is inserted into the bottom surface 3Bb of the metal case 3, uniform surface contact between the bottom surface 3Bb of the metal case 3 and the membrane ring 4 can be obtained easily and reliably, that is, There is a need for a metal case 3 that can prevent adverse effects due to the size of the chamfered portion 18 of the corner 3Bc, and a manufacturing method that can easily manufacture the metal case 3.

Further, not only in the metal case of the electret condenser microphone, but also in a product that needs to be housed so that another part is uniformly contacted with the bottom surface of the bottom inside the bottomed part, an adverse effect due to the corner chamfered part. There is a demand for a bottomed component and a method of manufacturing the same, which can prevent the occurrence of the problem.

The present invention has been made in view of the above points, and an object of the present invention is to provide a bottomed component capable of preventing an adverse effect of a chamfered corner and a method of manufacturing the same.

[0017]

In order to achieve the above-mentioned object, the feature of the bottomed part according to the first aspect of the present invention is that an annular concave portion is provided on the outer edge of the bottom surface of the bottom. is there. And by adopting such a configuration,
Since most of the chamfers at the corners connecting the cylindrical side wall and the annular recess can be located inside the annular recess,
Since the corner chamfer can be prevented from protruding from the bottom surface toward the inner space of the bottomed component, adverse effects due to the corner chamfer when other components are stored inside can be prevented.

A feature of the method for manufacturing a bottomed part of the present invention according to claim 2 of the present invention is that an annular projection protruding in the pressing direction is formed on the peripheral edge of the opposing surface of the punch in the pressing direction. The punch is pressed against the material and plastically deforms into a bottomed cylinder having a cylindrical side wall and a bottom having an annular recess at the outer edge of the bottom surface. When the punch is pressed against the material attached to the die, the material is narrowed into the hole of the die and becomes cylindrical with a bottom (cup shape), and the punch is pressed in the pressing direction. At the time of the most movement, the annular projection formed on the peripheral edge of the opposing surface in the pressing direction of the punch is plastically deformed so that the material is compressed in the thickness direction, forming an annular recess at the outer edge of the bottom surface of the bottom I do. That is, it is possible to easily form a bottomed component having the cylindrical side wall portion and the bottom portion and having the annular concave portion provided on the outer edge of the bottom surface of the bottom portion. In the annular recess formed by the annular projection of the punch, most of the corner radius formed on the peripheral edge of the opposing surface in the pressing direction of the punch can be located inside the annular recess. Therefore, most of the corner chamfers formed on the outer edge of the bottom surface of the bottom of the drawn bottomed part can be located inside the annular concave portion, so that most of the corner chamfers are located on the bottom surface. Can be prevented from protruding toward the inner space of the bottomed component, so that it is possible to prevent adverse effects due to the chamfered corners when other components are stored inside. Therefore, the bottomed part of the present invention described in claim 1 can be efficiently formed.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments shown in the drawings. The same or corresponding components as those of the above-described conventional device are denoted by the same reference numerals in the drawings.

FIG. 1 shows an embodiment of a bottomed part according to the present invention. FIG. 1 is a cross-sectional view showing the entire structure, and FIG. 2 is a partially enlarged view showing the vicinity of the outer edge of the bottom surface of the bottom. FIG. 3 is a cross-sectional view, and FIG. 3 is an explanatory view showing an example of a relationship between a corner and a direction in which a membrane ring is inserted.

The bottomed part of this embodiment is used for a metal case of an electret condenser microphone.

As shown in FIG. 1, the bottomed part 31 of the present embodiment has a cylindrical side wall 31A formed in a substantially cylindrical shape.
A bottom portion 31B extending from one end of the cylindrical side wall portion 31A toward the center in the thickness direction of the cylindrical side wall portion 31A, and has a bottomed cylindrical shape having an outer dimension of about 6 mm in diameter as a whole. Is formed. A through hole 31Ba is formed in the center of the bottom 21B in the plate thickness direction. The through hole 31Ba is a sound hole 3a when the electret condenser microphone 1 is used. Also,
At the outer edge of the bottom surface 31Bb of the bottom portion 31B, as shown in FIG.
Inside 2, a corner 31Bc connecting the cylindrical side wall 31A and the annular concave portion 32 is arranged.

The bottomed part 31 of the present embodiment is formed of, for example, aluminum having a thickness of about 0.3 mm, and the corner 31Bc is provided with, for example,
A round chamfer 33 is provided to prevent drawing cracks of about 00 μm.

The depth H of the annular recess 32 is, for example, about 20 to 30 μm. This annular recess 3
2, a chamfered portion 33 formed at a corner portion 31Bc connecting the cylindrical side wall portion 31A and the annular concave portion 32 is formed.
When the size of the chamfer of R is R, the relationship between R and H is H
= (1−cos θ) R. And θ
Of the bottom portion 31 formed by drawing by a manufacturing method to be described later.
This is preferable in that no distortion occurs in B or the like.
It should be noted that the value of θ may be determined as necessary according to the design concept such as the material and thickness of the material, and is particularly limited to the angle that becomes the value of the depth dimension H of the annular concave portion 32 of the present embodiment. Not something. Of course, if no distortion occurs in the bottom 31B or the like, the corner 31Bc
The configuration may be such that all of the chamfers are positioned. The allowable limit of the distortion of the bottom portion 31B when used in the electret condenser microphone 1 is as follows.
The flatness (flatness) of 1Bb is about 20 to 30 μm, and the depth H of the annular concave portion 31 may be determined so as to satisfy the allowable value of the flatness.

According to the bottomed part 31 of the present embodiment having such a configuration, the chamfered portion 33 of the corner portion 31Bc connecting the cylindrical side wall portion 31A and the annular concave portion 32 is formed inside the annular concave portion 32. Since the portion can be positioned inside the annular concave portion 32, the chamfered portion 33 of the corner portion 31Bc is
Since it can be prevented from protruding from 1Bb toward the inner space of the bottomed component 31, it is possible to prevent adverse effects due to the chamfered portion 33 of the corner 31Bc when other components are stored inside.

That is, as shown in FIG.
By providing 2, the membrane located in the direction substantially perpendicular to the insertion direction of the membrane ring 4 shown by the reference numeral A in FIG. 3 and indicated by the thick arrow in FIG. 3 among the chamfered portions 33 of the corners 31Bc. Since it is possible to prevent a portion where the ring 4 easily rides from protruding from the bottom surface 31Bb toward the inner space of the bottomed component 31, it is possible to prevent the corner 31Bc from being adversely affected by the chamfered portion 33. Specifically, the bottomed part 31
When inserting and fixing the membrane ring 4 to the barrel metal case,
The membrane ring 4 is fixed to the bottom surface 31Bb of the bottomed component 31 in an inclined or floating state, and uniform surface contact between the bottom surface 31Bb of the metal case serving as the bottomed component 31 and the membrane ring 4 can be obtained. Instead, the inconvenience that the variation in the sensitivity of the sound pressure for each product becomes large can be reduced to a level that causes no practical problem.

As shown in FIG. 3, among the chamfered portions 33 of the corners 31Bc, substantially parallel to the direction of insertion of the membrane ring 4 indicated by the symbol B in FIG. The part located in the direction serves as a guide when the membrane ring 4 falls toward the bottom surface 31Bb, so that there is no adverse effect.

Further, the cylindrical side wall 31 is provided in the annular recess 32.
A configuration in which a corner portion 31Bc located at a connection portion between A and the bottom surface 31Bb of the bottom portion 31b is located, specifically, an annular concave portion 32
May be configured such that all of the chamfered portions 33 of the corners 31Bc are located inside the inside. In this case, since the chamfered portion 33 of the corner portion 31Bc connecting the cylindrical side wall portion 31A and the annular concave portion 32 can be more reliably and easily located inside the annular concave portion 32, the drawing process described later is used. The chamfered portion 33 of the corner portion 31Bc is shifted from the bottom surface 31Bb to the bottomed part 3.
Since it can be more reliably prevented from protruding toward the inner space of No. 1, it is possible to more reliably prevent the adverse effect of the chamfered portion 33 of the corner 31Bc. However, as described above, it is important not to cause distortion in the bottom 31B and the like.

Next, a method of manufacturing the bottomed part of the present embodiment will be described.

FIG. 4 is a sectional view showing an essential part of an embodiment of a punch used in the method of manufacturing a bottomed part according to the present invention, FIG. 5 is an enlarged sectional view showing the vicinity of an annular projection, and FIG. FIG. 7 is an explanatory view showing a state in which the punch and the die are separated from each other in the method of manufacturing the bottom part, FIG. 7 is an explanatory view following FIG. 6 showing a state in which the punch is in contact with the material mounted on the die, and FIG. Explanatory diagram following FIG. 7 showing the progress of the aperture state,
FIG. 9 is an explanatory view following FIG. 8 showing a state in which the punch has reached the bottom dead center.

An outline of the method of manufacturing a bottomed part according to the present embodiment will be described.
A blanking die for forming the material 17 and a drawing die for narrowing the material 17 into a bottomed cylinder are installed in the processing order in this order, and the material 17 such as a band-shaped hoop material or a long flat plate-shaped sketch material is provided. An annular blank 17a using a punching die
Punching for forming the blank 17a
Is efficiently manufactured by successively performing a processing step of drawing in which the target is drawn into a bottomed cylindrical shape using a drawing die in this order. Since the punching process is the same as the conventional one, a detailed description thereof will be omitted, and only the drawing process, which is the gist of the present invention, will be described in detail below.

As shown in FIG. 4, the punch 3 of this embodiment
In FIG. 5, an annular protrusion 36 protruding in the pressing direction is formed at the peripheral edge of the opposing surface in the pressing direction indicated by the arrow in FIG. The annular projection 36 is provided in the annular recess 3 of the bottomed component 31 described above.
2 is formed by drawing, and as shown in an enlarged view in FIG.
Is formed, for example, in the order of 20 to 30 μm. Assuming that the size (radius) of the corner radius 35a, which is a chamfered portion formed on the periphery of the facing surface in the pressing direction of the punch 35, is CR, the height dimension HA of the annular projection 36 is CR, HA, Is HA = (1-cos θ) CR
Can be represented by The value of θ is preferably about 15 degrees to 60 degrees in the sense that when the material 17 is compressed, no distortion occurs in the bottom 31B or the like. It should be noted that the value of θ may be determined according to the necessity of a design concept such as the material and thickness of the material, and is particularly limited to an angle which becomes the value of the height dimension HA of the annular protrusion 36 of the present embodiment. It is not something to be done. Of course, when no distortion occurs in the bottom portion 31B or the like, the height H of the annular protrusion 36 is set.
A may be configured to be larger than the size CR of the corner radius 35a.

The height HA of the annular projection 36 is determined by taking into account the size of the springback after the blank 17a is plastically deformed, and taking into account the radius of the chamfer 33 of the corner 31Bc of the bottomed part 31. Is set to about 0.1 mm.

That is, the height dimension HA of the annular projection 36
Is formed to be substantially the same as or slightly smaller than the depth H of the annular concave portion 32 of the bottomed component 31, and the width dimension WA of the annular projection 36 is set equal to the width dimension W of the annular concave portion 32 of the bottomed component 31.
It is formed to be almost the same as or slightly smaller.

The configuration of the die 16 is the same as the conventional one, and the detailed description thereof is omitted.

The die 16 and the punch 35
In order to manufacture the bottomed component 31 as shown in FIG. 6, the punch 35 and the die 16 are separated from each other, and are arranged on a press (not shown) with their axes in the pressing direction aligned. I do. At this time, the wrinkle presser 38 is also a die 1.
6 and is arranged at a position separated from the same.

Next, in this state, the blank 17a is mounted on the die 16 and the wrinkle holder 38 is brought into contact with the surface of the blank 17 with a predetermined contact force, and then the punch 35 is operated toward the blank 17. Then, as shown in FIG. 7, the annular projection 36 formed on the peripheral edge of the opposing surface of the punch 35 in the pressing direction comes into contact with the blank 17a. And
When the punch 35 is further moved in this state, as shown in FIG. 8, the blank 17a is narrowed down into the hole of the die 16 and gradually plastically deforms into a bottomed cylindrical shape (cup shape).

Next, when the punch 35 reaches the bottom dead center where the punch 35 has moved the most in the pressing direction, as shown in FIG. 9, the blank 17 is formed into a bottomed tubular shape having a tubular side wall 31A and a bottom 31B. At the same time, the annular projection 36 formed on the periphery of the opposing surface of the punch 35 in the pressing direction is
Knockout 39 of a protruding device which also serves as a back-press of a finished product arranged so as to face punch 35 via 7a.
In cooperation with the above, the blank 17a is plastically deformed so as to be compressed in the thickness direction to form an annular concave portion 32 at the outer edge of the bottom surface 31Bb of the bottom portion 31B, thereby manufacturing the bottomed part 31 shown in FIGS. Is completed.

That is, by pressing the punch 35 against the blank 17a, the blank 17a is moved to the cylindrical side wall 31A.
And a bottom 31B having an annular recess 32 at the outer edge of the bottom surface 31Bb.

When the punch 35 and the wrinkle retainer 38 are separated from the die 16, the completed bottomed part 32 is discharged above the die 16 by the rise of the knockout 39.

In this embodiment, the blank 17a is used as the blank 17a, and the blank 17a is drawn in one process. A trimming type) is set as one set, and the drawing type is intermittently fed with a material 17 such as a band-shaped hoop material or a long flat plate-shaped sketch material to form a drawing. And a method of continuously executing a plurality of steps while feeding a material called a so-called snapping method in which the bottomed part 31 is separated from the material 17 by a punching die. In this case, it is important that the annular recess 32 be formed in the last step of the plurality of drawing steps. That is, when forming the bottomed component 31, the blank 17 is temporarily
Any method may be used, either from the raw material a or from the raw material 17 itself. However, a method of directly forming a bottomed part from the raw material 17 is preferable in terms of the highest production efficiency.

In this embodiment, an annular blank is used, but in this case, the through hole 32Ba is formed after forming a cylindrical intermediate product with a bottom using a disk-shaped blank. You may.

As described above, according to the method of manufacturing a bottomed part of the present embodiment, when the punch 35 is pressed against the blank 17 a mounted on the die 16, the blank 17 a
At the time when the punch 35 is moved most in the pressing direction,
The annular projection 36 formed on the peripheral edge of the opposing surface in the pressing direction of the punch 35 plastically deforms the blank 17a so as to compress the blank 17a in the thickness direction, thereby forming the annular recess 32 at the outer edge of the bottom surface 31Bb of the bottom 31B. .

That is, the cylindrical side wall 31A and the bottom 31B
And the bottomed part 31 having the annular recess 32 at the outer edge of the bottom surface 31Bb of the bottom 31b can be formed in one operation.

The annular recess 32 formed by the annular projection 36 of the punch 35 positions most of the corner radius 35 a formed on the peripheral edge of the opposing surface of the punch 35 in the pressing direction inside the annular recess 32. be able to. Therefore, the bottom surface 3 of the bottom part 31B of the drawn bottomed part 31
Chamfered portion 3 of corner 31Bc formed at outer edge of 1Bb
3 can be positioned inside the annular concave portion 32, so that most of the chamfered portion 33 of the corner portion 31Bc can be prevented from protruding from the bottom surface 31Bb toward the inner space of the bottomed component 31. It is possible to prevent the corner 31Bc from being adversely affected by the chamfer 33 when other components are stored inside.

The bottomed component and the method of manufacturing the same according to the present embodiment are not limited to the metal case of the electret condenser microphone, but may be used for all components that need to be housed so that other components are uniformly contacted inside. it can.

The present invention is not limited to the above embodiments, but can be variously modified as needed.

[0048]

As described above, according to the bottomed part of the present invention according to the first aspect, most of the chamfered portion at the corner connecting the cylindrical side wall portion and the annular concave portion is placed inside the annular concave portion. Because it can be located, it is possible to prevent the chamfer of the corner from protruding from the bottom toward the inside space of the bottomed part,
An extremely excellent effect is obtained such that an adverse effect due to a chamfered portion at a corner when other components are stored inside can be prevented.

Further, according to the method of manufacturing a bottomed part of the present invention according to claim 2, when a punch is pressed against a material mounted on a die, the material is narrowed into a hole of the die and has a cylindrical shape with a bottom. Cup-shaped), and at the time when the punch has moved the most in the pressing direction, the annular protrusion formed on the peripheral portion of the opposing surface in the pressing direction of the punch is plastically deformed so as to compress the material in the thickness direction. An annular recess is formed in the outer edge of the bottom surface of the bottom. That is, it is possible to easily form a bottomed component having the cylindrical side wall portion and the bottom portion and having the annular concave portion provided on the outer edge of the bottom surface of the bottom portion. In the annular recess formed by the annular projection of the punch, most of the corner radius formed on the peripheral edge of the opposing surface in the pressing direction of the punch can be located inside the annular recess. Therefore, most of the corner chamfers formed on the outer edge of the bottom surface of the bottom of the drawn bottomed part can be located inside the annular concave portion, so that most of the corner chamfers are located on the bottom surface. Therefore, it is possible to prevent the protruding portion from projecting toward the inner space of the bottomed component, thereby achieving an extremely excellent effect such as preventing an adverse effect due to a chamfered portion at a corner when other components are stored inside.
Therefore, the bottomed part of the present invention described in claim 1 can be efficiently formed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an overall configuration of an embodiment of a bottomed part according to the present invention.

FIG. 2 is a partially enlarged cross-sectional view showing the vicinity of an outer edge of a bottom surface of the bottom of the bottomed part of FIG.

FIG. 3 is an explanatory diagram illustrating an example of a relationship between a corner of the bottomed component of FIG. 1 and an insertion direction of a membrane ring.

FIG. 4 is a sectional view showing a main part of an embodiment of a punch used in the method for manufacturing a bottomed part according to the present invention.

FIG. 5 is an enlarged sectional view of the vicinity of an annular protrusion of the punch of FIG. 4;

FIG. 6 is an explanatory view showing a state in which the punch and the die are separated in the method for manufacturing a bottomed part according to the present invention.

FIG. 7 is an explanatory view following FIG. 6 and shows a state in which a punch is in contact with a blank mounted on a die in the method of manufacturing a bottomed part according to the present invention.

FIG. 8 is an explanatory view subsequent to FIG. 7 and shows the progress of the drawing state of the blank by the punch in the method for manufacturing a bottomed part according to the present invention.

FIG. 9 is an explanatory view following FIG. 8 showing a state in which the punch has reached the bottom dead center in the method for manufacturing a bottomed part according to the present invention.

FIG. 10 is a partially cutaway perspective view showing a main part of a conventional electret condenser microphone.

FIG. 11 is a sectional view showing a metal case as a bottomed component used in the electret condenser microphone of FIG. 10;

FIG. 12 is an explanatory view illustrating a method of manufacturing a metal case as a bottomed component used in the electret condenser microphone of FIG.

13 is an enlarged view showing a corner of a metal case manufactured by a method of manufacturing a metal case as a bottomed component used in the electret condenser microphone of FIG.

FIG. 14 is an explanatory view illustrating a method of manufacturing a membrane ring used in the electret condenser microphone of FIG.

FIG. 15 is an enlarged view showing, in an enlarged manner, a general outer peripheral portion of a membrane ring manufactured by the method for manufacturing a membrane ring used in the electret condenser microphone of FIG. 10;

FIG. 16 is an enlarged view showing, in an enlarged manner, a film ring manufactured by the method for manufacturing a film ring used in the electret condenser microphone of FIG.

FIG. 17 is an explanatory diagram illustrating a state where uniform surface contact between the bottom surface of the metal case and the membrane ring in the electret condenser microphone of FIG. 10 cannot be obtained.

[Explanation of symbols]

Reference Signs List 16 die 17 material 17a blank 31 bottomed part 31A cylindrical side wall 31B bottom 31Bb bottom 31Bc corner 32 annular recess 33 chamfer 35 punch 35a corner radius 36 annular protrusion H depth of annular recess 32 (circular recess 32) The width dimension R (of the chamfered portion 33) HA The height dimension (of the corner radius 35a of the punch 35) The width dimension WA (of the corner radius 35a of the punch 35) The size CR (of the corner radius 35a)

Claims (2)

[Claims] 1. A bottomed component having a bottomed cylindrical shape having a cylindrical side wall portion and a bottom portion and capable of storing other components therein, wherein an annular concave portion is provided at an outer edge of a bottom surface of the bottom portion. Features bottomed parts. 2. A method of manufacturing a bottomed component, wherein a material is mounted on a die, and a punch which is relatively movable with respect to the die is pressed against the material to draw and deform the material plastically. A bottom portion having an annular protrusion protruding in the pressing direction at a peripheral portion of the opposing surface in the pressing direction of the punch, pressing the punch against the material, and having an annular recess at an outer edge of the cylindrical side wall and the bottom surface; A method for manufacturing a bottomed part, wherein the part is plastically deformed into a bottomed cylindrical shape.