JP2003249413A - Method for manufacturing ceramic core - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain a method for manufacturing a ceramic core which has a complicated shape, a superior strength and electrical characteristic, and better productivity. <P>SOLUTION: The method for manufacturing the ceramic core, which has flanges at both ends of a winding core, includes a process that a female molding die which consist of through-holes fitted to a shape of at least a part of the core is formed from a flammable sheet, a process that ceramic paste or sheet is filled into the female molding die, and a process that a flammable sheet is burned down by baking the filled female molding die to obtain the sintered core. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ceramic score which mainly constitutes a choke coil used as an inductor.

[0002]

2. Description of the Related Art For example, as shown in FIG. 6 (b), a ceramic score 100 used as a core of a choke coil, a transformer or the like has a winding core portion 102 having a thin center and winding core portions 102 at both ends thereof. It has a thickened collar portion 101. The core portion 10 of the ceramic score 100
A coil is wound around 2 to form a choke coil or a transformer.

Such a ceramic score 100 has a shape in which a groove 103 is provided on the outer periphery of the flange 101 in order to draw out the lead wire of the coil wound around the winding core 102. Further, a recess 104 is formed on the side surface of the collar portion 101 in order to connect the extracted lead wire to the outside. And, the ceramic score 100 having such a shape
First, an appropriate organic binder is added to the ceramic raw material powder, and the mixture is put into a mold and press-molded to form a cylindrical solid powder compact 100a having grooves 103a on its peripheral surface as shown in FIG. 6 (a). It is produced by grinding and grinding the central part of the powder compact 100a.

FIG. 7 shows an example of an apparatus for grinding such a powder compact 100a to make a ceramic score 100. Grinding peripheral surface 2 of grinding wheel 1 rotating in the direction indicated by the arrow
The guide peripheral surface 5 of the cam roller 4 rotating in the direction indicated by the arrow and is arranged so as to face each other, and the blade plate 7 is arranged below the gap between the peripheral surfaces 2, 5. Also, grinding wheel 1
A pin-shaped core guide 3 is arranged laterally between the grinding peripheral surface 2 and the guide peripheral surface 5 of the cam roller 4. As shown in FIG. 7A, the powder compact 100a as shown in FIG. 6 has the grinding peripheral surface 2 of the grinding wheel 1 and the cam roller 4 facing each other.
Of the blade plate 7 that is obliquely formed and is rotatably supported by the upper end of the blade plate 7 that is obliquely formed. The axial position is restricted.

The grinding wheel 1 has a grinding portion formed of diamond powder or the like on its outer peripheral portion, and the outer peripheral surface of the grinding peripheral surface 2 can cylindrically grind the powder compact 100a. In addition, the guide peripheral surface 5 of the cam roller 4
Indicates that the distance from the center of rotation increases as the position advances from the 3 o'clock position in FIG.
The distance becomes maximum at the 1 o'clock position in FIG. Therefore, when the cam roller 4 rotates in the direction shown by the arrow from FIG. 7A to FIG. 7B, the guide peripheral surface 5 of the cam roller 4 causes the peripheral surface of the powder compact 100a to move toward the grinding wheel 1. It is pressed against the grinding peripheral surface 2 and ground. During this time,
Since the powder compact 100a is rotating, the central portion of the peripheral surface thereof is cylindrically ground by the grinding wheel 1 to process the ceramic score 100 as shown in FIG. The cutting depth of the grinding wheel 1 with respect to the powder compact 100a is determined by the minimum distance between the grinding peripheral surface 2 of the grinding wheel 1 and the guide peripheral surface 5 of the cam roller 4.

[0006]

A powder compact 10 as shown in FIG. 6 is formed by a conventional method and apparatus for processing a drum-shaped part.
0a, that is, the powder compact 1 having the groove 103a on the peripheral surface.
When 00a is processed, as shown in FIG.
The cross section of the winding core 102 of 00 is not a perfect circle,
The position corresponding to the groove 103 is raised as if it were raised.

In order to solve this problem, as shown in FIG. 9, when grinding the powder compact 100a with the grinding wheel 11, the guide peripheral surface 15 of the cam roller 14 having the step portion 16 moves the powder compact 100a. A method has been proposed in which only the central portion of the peripheral surface to be ground is pressed against the peripheral surface 12 of the grinding wheel 11 to thereby cylindrically grind the core portion 102 of the drum-shaped component 100 as a reference (Patent 317).
4696 gazette).

However, even with this method, the powder compact 100a
When the ratio of the groove 103a to the peripheral surface of the powder compact 100a is high, for example, when the powder compact 100a as shown in FIG. 10A, that is, the prismatic powder compact 100a is processed, the powder compact 100a is held by the blade plate 17. It was found that the drum-shaped component 100 as shown in FIG.

Further, according to this method, the ceramic score 100 as shown in FIG. 11, that is, the ceramic score 100 having a complicated shape in which the winding core portion 102 is displaced from the center of the collar portion 101 cannot be processed. .

Further, when a ceramic score is manufactured using the above-described method and apparatus for processing a drum-shaped component, the grinding wheel 1 is formed on the peripheral surface of the core portion 102 and the surface of the collar portion 101 on the core portion side.
It was found that grinding scratches and minute cracks occurred due to No. 1, and the strength and electric characteristics of the ceramic score deteriorated.

In order to solve these problems, FIG.
In the step of putting the raw material powder 24 into the mold 21 and obtaining the product shape by press molding as shown in FIG. 1, a ring-shaped insert 25 made of a combustible material is set in the mold 21, and the insert is formed by insert molding. A method has been proposed in which a molded body integrally including 25 is obtained, and the insert 25 is incinerated in a step of firing the insert molded body to obtain the drum-shaped component 100 from which the insert 25 is removed ( See JP-A-6-806).

However, according to this method, it is difficult to adjust the powder density inside the insert 25 corresponding to the winding core 102 and outside the insert 25 corresponding to the collar 101, and the product size cannot be controlled. . Further, since the powder density inside the insert 25 corresponding to the core portion 102 becomes low, the strength and electric characteristics are also deteriorated. Furthermore, this method requires a step of setting the insert 25 made of a combustible material once in the mold 21 in order to obtain one insert molded body, so that the production efficiency is poor and it is not suitable for mass production. Therefore, it is an object of the present invention to provide a method of manufacturing a ceramic score having a complicated shape and excellent strength and electrical characteristics by a simple manufacturing method.

[0013]

In order to achieve the above object, in the present invention, in a method for producing a ceramic score having flanges at both ends of a winding core, a flammable sheet has at least a part of the shape of the core. Forming a female mold for forming a through-hole that conforms to the above, a process of filling the female mold for molding with a ceramic paste or a ceramic sheet, and burning the combustible sheet to sinter the core. Is obtained. Then, in the present invention, the flammable sheet, a sheet having a molding female die consisting of a through hole matched with the winding core portion of the core, and a molding female die consisting of a through hole matched with the flange portion of the core. And a sheet having the same.

Further, in the present invention, the flammable sheet has a female molding die formed of a through hole matching the winding core portion of the core, and after filling the female molding die with a ceramic paste or a ceramic sheet. It is characterized in that a ceramic paste or a ceramic sheet is applied or laminated on the surface of a flammable sheet, cut into individual core shapes, and then fired.

In the method for producing a ceramic score according to the present invention, a flammable sheet is incinerated in the firing step of a molded product, and the product is completely removed to obtain a ceramic product.
Therefore, the flammable sheet functions like a mold and a mold core in general plastic molding, and easily realizes a complicated product shape that cannot be molded by simple press molding or grinding. can do.

In the method for manufacturing a ceramic score according to the present invention, since the post-processing such as grinding is unnecessary, the ceramic score body does not include grinding scratches and cracks caused by the post-processing, and the paste-like raw material is used. Since it is formed by molding, the density of the sintered body becomes uniform and high, and the strength and electrical characteristics are improved.

Further, in the method for manufacturing a ceramic score according to the present invention, since a large number of cores can be molded at the same time, the production efficiency is good and it is suitable for mass production.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below.

FIG. 1 shows an example of a method of manufacturing the ceramic score 100 according to this embodiment. Ceramic score 1
00 is a molding die 30 made of a flammable sheet.
Is formed by using. This molding die 30 is shown in FIG.
As shown in Fig. 1, two drum-shaped parts 1 to be formed
Combustible sheet 31 in which a through hole 31b is formed in the shape of the flange portion 00 of 00, and a through hole 31c is formed in the shape of the core portion 102 of the ceramic score 100 to be formed.
The flammable sheet 31 in which is formed is laminated as shown in FIG.

Any material may be used as the material of the combustible sheet 31 as long as it exhibits appropriate rigidity as a female mold for molding and is burned down by the heat of burning. For example, PVA that may be formed of paper or wood, but has high thermal decomposability
A sheet made of a material such as wax, WAX, or acrylic is preferable. The through holes 31b and 31c of the combustible sheet 31 are formed by punching with a punch or the like, or by pouring a combustible material into a mold having a rod-shaped protrusion. Further, in this embodiment, 3
Although the combustible sheets were laminated to form the female molding die 30, one combustible sheet 31 was used to fabricate the female molding die 30 to form the through hole 30a in the shape of the drum-shaped component 100. May be.

Next, as shown in FIG. 1C, the ceramic paste 33 is filled into the through hole 30a of the female molding die 30 by a method such as press-fitting or squeezing / coating and dried to form a molded body. In the present embodiment, after the flammable sheets 31 are stacked, the through holes 30a are filled with the ceramic paste 33. However, as shown in FIG. 2, the through holes 31b of the flammable sheets 31 of the collar portion 101 and the winding core portion 102 are formed. Three
After the ceramic paste 33 is filled in 1c, the flammable sheets 31 may be laminated to form the molded body 34.
Further, in the present embodiment, the through hole 31b of the combustible sheet 31,
Although 31c is filled with the ceramic paste 33, a ceramic sheet may be processed and filled instead.

Here, the material of the ceramic paste 33 is
Any paste may be used as long as it exhibits appropriate fluidity as a paste and maintains its shape by drying.
For example, ferrite, alumina, zirconia or the like may be used.

Next, as shown in FIG. 1 (d), the molded body 3
4 is fired in the firing furnace 200. Then, the drum-shaped component 100 is fired by this firing process, and the female molding die 30 made of a combustible sheet is burned off. As a result, as shown in FIG.
Is formed.

As described above, in the method for manufacturing the drum-shaped component 100 according to the present embodiment, the drum-shaped component 100 molded together with the female molding die 30 is the female molding die 30.
Is calcined in the state of containing. By this firing process, the female molding die 30 made of the flammable sheet 31 is burned off, and the drum-shaped component 100 is fired. Therefore, in this manufacturing method, the flammable sheet 31
By simply changing the shape of the through holes 31b and 31c and the stacking position, a complicated product shape such as a square brim can be easily formed. Further, according to this manufacturing method, since there is no need for post-processing such as grinding, grinding scratches / cracks due to post-processing do not occur in the core body, and since a paste-like ceramic raw material is used, Compared with powder press-molded products, the core body has a uniform and high density, improving strength and electrical properties.

Next, another embodiment of the present invention will be described.

FIG. 3 shows a drum-shaped component 1 according to this embodiment.
An example of the manufacturing method of 00 is shown. The drum-shaped component 100 is
It is formed by using the molding die 30 made of the flammable sheet 31. As shown in FIG. 3A, the molding die 30 is a drum-shaped component 100 to be formed.
It is made of a flammable sheet 31 in which a through hole 31c is formed in the shape of the winding core 102.

Next, as shown in FIG. 3 (b), the ceramic paste 33 is filled into the through hole 31c of the female molding die 30 by a method such as press fitting or squeezing / coating to form the winding core portion 102.

Next, as shown in FIG. 3C, the collar portion 101 is formed on the front and back of the molding female die 30 filled with the winding core portion 102.
The ceramic sheets 35 corresponding to
To form.

In this embodiment, the ceramic paste 3 corresponding to the winding core 102 is inserted into the through hole 31c of the molding die 30.
3, the ceramic sheets 35 corresponding to the collar portion 101 were laminated, but as shown in FIG.
The ceramic paste 33 corresponding to the core portion 102 may be filled in the through hole 31c of 0 and then the ceramic paste 33 corresponding to the collar portion 101 may be squeezed and applied.
Further, as shown in FIG. 5, the ceramic paste 33 corresponding to the collar portion 101 is squeezed and applied, and at the same time, the through hole 31c of the female molding die 30 is filled with the ceramic paste 33 corresponding to the winding core portion 102. Is also good. Further, in the present embodiment, the ceramic paste 33 is filled in the through hole 31c of the female molding die 30, but a ceramic sheet may be processed and filled instead.

Then, as shown in FIG.
6 is cut together with the molding die 30 to form a molded body 34. Here, in this embodiment, the laminated body 36 is formed into the female die 30 for molding.
Although the molded body 34 is formed by cutting together with the molded body 34, the molded body 34 may be formed by punching the laminated body 36 together with the molding die 30 with a punch or the like.

Next, as shown in FIG. 3 (e), the molded body 3
4 is fired in the firing furnace 200. Then, the drum-shaped component 100 is fired by this firing process, and the female molding die 30 made of the combustible sheet 31 is burned off. As a result, as shown in FIG. 3 (f), the drum-shaped component 1
00 is formed.

As described above, in the method of manufacturing the drum-shaped component 100 according to this embodiment, the drum-shaped component 100 formed together with the female molding die 30 is the female molding die 30.
Is calcined in the state of containing. By this firing process, the female molding die 30 made of the flammable sheet 31 is burned off, and the drum-shaped component 100 is fired. Therefore, in this manufacturing method, the flammable sheet 31
By simply changing the shape of the through hole 31c and the cutting position, a complicated product shape such as a square brim can be easily formed. Further, according to this manufacturing method, since there is no need for post-processing such as grinding, grinding scratches / cracks due to post-processing do not occur in the core body, and since a paste-like ceramic raw material is used, Compared with powder press-molded products, the density of the core body is even and high, and the strength and electrical characteristics are improved.

The pattern of the depressions 104 formed on the side surface of the collar as shown in FIG.
It can be easily formed by pressing a mold onto.

[0033]

EXAMPLE As an example of the present invention, a ceramic score having a shape shown in FIG. 10B was manufactured according to the procedure of FIGS.

A combustible sheet 31 made of polyethylene having a length and width of 200 mm and a thickness of 1 mm is made of polyethylene, and 10,000 through holes 31c having a diameter of 0.5 mm are formed in the shape of a core using a mold.

In the through-hole 31c, which resembles this winding core, Ni is
-Ceramic paste 33 using Zn-based ferrite as a main material is press-fitted.

10,000 pieces of □ 1 mm through-holes 31b are formed on the two flammable sheets 31 made of polyethylene having a length and width of □ 200 mm and a thickness of 0.5 mm and made of polyethylene. A ceramic paste 33 using Ni-Zn ferrite as a main raw material is press-fitted into the through hole 31b that is shaped like the flange. The three flammable sheets 31 in which the ceramic paste 33 is press-fitted into the through holes 31b and 31c are thermocompression-bonded and laminated to form a molded body 34.

The molded body 34 is fired in the firing furnace 200 to burn out the flammable sheet 31, and at the same time, 10,0
Obtain 100 ceramic scores of 100.

By the above procedure, the drum-shaped parts shown in FIG. 10 (b), which cannot be processed by the conventional manufacturing method, could be manufactured easily and in large quantities.

[0039]

As described above, according to the present invention, the flammable sheet is processed to form a female mold for molding, regardless of the cross section of the collar or the core, and the ceramic paste is formed. It is a very simple manufacturing process of injecting and removing the female mold for molding in the step of filling the molded body / laminated body with the above, and firing the molded body / laminated body, which can be realized by the conventional molding method. It is possible to easily realize mass production of a product having a complicated shape, a ceramic score body that does not include grinding scratches and cracks, and that has a uniform density and high density.

[Brief description of drawings]

1 (a) to 1 (e) are views for explaining a ceramic score manufacturing method of the present invention.

2A to 2C are views for explaining another embodiment of the present invention.

3A to 3F are views for explaining another embodiment of the present invention.

4A to 4C are diagrams for explaining another embodiment of the present invention.

5 (a) and 5 (b) are views for explaining another embodiment of the present invention.

FIG. 6A is a perspective view showing a powder molded product before being processed into a ceramic score, and FIG. 6B is a perspective view of the ceramic score.

7 (a) and 7 (b) are schematic side views showing a conventional ceramic score processing apparatus.

FIG. 8 is a vertical cross-sectional front view of a drum-shaped component processed by a conventional drum-shaped component processing apparatus.

FIG. 9 is an enlarged schematic side view of a main part of a drum-shaped component processing apparatus that makes a winding core circular according to a conventional example.

FIG. 10 is a perspective view of a drum-shaped component that cannot be processed by the conventional drum-shaped component processing apparatus.

FIG. 11 is a perspective view of a drum-shaped component that cannot be processed by the conventional drum-shaped component processing apparatus.

FIG. 12 is a state explanatory view of a drum-shaped component molding method by insert molding according to a conventional example.

[Explanation of symbols]

30 Mold for molding 31 flammable sheet 33 Ceramic paste 34 molded body 35 Ceramic Sheet 36 laminate 100 ceramic score 100a powder compact 101 Tsubabe 102 core 200 firing furnace

Claims (3)

[Claims] 1. A method of manufacturing a ceramic score having flanges on both ends of a winding core, the step of forming a molding female die having a through hole conforming to the shape of at least a part of the core in a flammable sheet, A method for producing a ceramic score, comprising: a step of filling a ceramic paste or a ceramic sheet in the molding die; and a step of burning the combustible sheet to obtain a sintered body of a core by firing the paste. 2. A sheet having a female mold for molding, wherein the flammable sheet has a through hole that matches the winding core portion of the core,
2. The method for producing a ceramic score according to claim 1, wherein the core is laminated with a sheet having a female molding die having a through hole that matches the flange portion of the core. 3. The flammable sheet has a female molding die formed of a through hole that matches the core of the core, and the flammable material is filled with a ceramic paste or a ceramic sheet and then flammable. 2. The method for producing a ceramic score according to claim 1, wherein a ceramic paste or a ceramic sheet is applied or laminated on the surface of the sheet, cut into individual core shapes, and then fired.