JPH0677712A - Manufacture of ceramic dielectric resonator - Google Patents

Abstract

PURPOSE:To prevent a resonance element from cracking or chipping when handled after its manufacture by beveling the end surface peripheral edge part of the resonance element in a staircase shape at the time of its formation by compression. CONSTITUTION:A core 5 having a necessary diameter is set in the center in a die 3. A necessary amount of ceramic powder is charged in the die 3, and compressed and compacted by upper and lower punches 4. Consequently, a compacted body which is formed in the staircase shape having two ridge parts 11 and 12 at both external peripheral edge parts A1 and A2 among compression- directional end surfaces while one end surface ridge part 11 is rounded as required and the other ridge part 12 is beveled in the fine-step staircase shape is obtained. Then this compacted body is sintered and caked and barrel machining is carried out to form one ridge part 12 into a necessary R surface simultaneously with deburring.

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 dielectric resonator used in a microwave filter.

[0002]

2. Description of the Related Art A microwave filter used for selecting a specific frequency by incorporating it into a device for communication or broadcasting in a microwave band, has a resonator made of a ceramic dielectric (hereinafter referred to as "resonator"). "Resonant element" indicates this) is generally used.

This resonator element is generally cylindrical (cylindrical (7th
(Shown in Fig. B), square cylinder) or columnar shape (cylindrical shape, prismatic shape (shown in Fig. 7B)), and the resonance frequency can be set to a required level by selecting the material (dielectric constant), shape and dimensions. Further, the surface is coated with an electrode material (conductive material) as necessary (hereinafter, those with electrode formation are referred to as a coated type, and those without an electrode are referred to as a non-coated type).

In such a resonance element, a predetermined ceramic powder is pressure-molded (press-molded), and then this molded product is fired to be solidified, and finally the burr that appears during pressing is processed by barrel processing. It is created.

[0005]

However, since this resonator element is inherently fragile in ceramics, it is difficult to carry out the manufacturing process as described above, particularly during barreling for final finishing, and further for subsequent transportation and assembly. Due to the impact in the process
At the corners, cracks S ₁ as shown in Fig. 7a and b
It is easy to cause chipping S ₂ . The occurrence of cracks and chips will cause the resonance frequency to go wrong, resulting in loss of value as a product.

Further, particularly when the electrode is formed and used, the following points pose a problem. That is, the electrode is formed by a method in which a conductive coating material (electrode material) such as Ag paste is applied by dipping and then baked and solidified. In this case, as shown in FIG. A ₁ , A
_It is difficult to attach the electrode material 2 to 2 (the quality of attachment of the electrode material is hereinafter referred to as "coverability"), and the coating thickness at that portion becomes extremely thin, which causes deterioration of the Q value of the resonator and is a problem. .

By the way, all of the above problems are problems at the corners of the resonance element, and it is necessary to round the corners (hereinafter referred to as "R chamfering"). It can be an effective measure. The R surface disperses and relaxes the stress generated by the impact force on the corner portion, and also provides an electrode forming surface at the corner portion to improve its coverage.

However, since the resonance element forms the basic shape by press molding as described above, sharp corners are inevitably formed. That is, regardless of the shape,
It is impossible to give the R surface shape to the peripheral portions of both end surfaces in the pressing direction at the pressing stage.
Here, press molding is performed in both cylindrical and columnar cases.
Since the axial direction is used as the pressing direction, the press direction end face peripheral portion is the axial end face peripheral portion indicated by reference symbol A in FIG. 7 described above, and the end face peripheral portion A is the R surface shape. Therefore, it is technically impossible to press-mold into Incidentally, in the case of a rectangular cylinder or a prism, a corner B (see FIG. 7B) is naturally formed on the peripheral surface side, but it is possible to give an R surface to this portion by adjusting the shape of the press die. Yes, no problem.

There is no method other than adding processing after press molding-sintering to attach the R surface to the peripheral edge portion A of the end surface, which is a problem. Then, it is necessary to spend a remarkably long time of, for example, 20 hours to provide a required R surface (curvature radius of 0.5 to 0.8 mm) effective for preventing chipping and cracking. The adoption of inefficient processing is practically impossible.

However, it is possible to perform chamfering C on the end face peripheral portion A of the resonance element by press molding as shown in FIG. 9, and the chamfered end face peripheral portion A is shown in FIG. It is known that cracks and chips are considerably prevented and the electrode material is easily attached.

However, when the chamfering C having the above-mentioned slope is applied to the peripheral edge portion A of the resonance element, the tenth
As shown in the figure, the working surface 4 ′ must have a mortar shape, and the peripheral edge tip portion 4 a must have a sharp-edged metal mold punch 4. Such a metal mold punch 4 is used for press molding. In the above, the pointed tip portion 4a of the working surface 4'has serious friction and damage and has a problem in durability.

The pointed tip portion 4a of the die punch is also used.
When the wear of the die advances as indicated by the broken line, the gap D between the tip portion 4a and the die 3 (or core) becomes large, and the raw material enters there, resulting in a very thick wall as shown in FIG. A large burr E is generated. Bali E like this
In many cases, it cannot be removed by ordinary barrel polishing, etc.
There was also a problem with its moldability.

The present invention has been made in order to solve such a problem, and in the press molding step, a crack or a crack is formed on the peripheral portion of the end face of the resonant element without impairing the durability or moldability of the die punch. An object is to provide a method capable of forming a chamfer effective for preventing chipping.

[0014]

According to the present invention, which achieves the above object, a ceramic powder filled in a die die 3 is press-formed from above and below with die punches 4 and 4, and then the article is fired to obtain a product. In the manufacturing process of the ceramic dielectric resonator to be finished as described above, the working surface 4 ′ of the die punches 4 and 4 is made into a mortar shape which is recessed inward, and the peripheral edge tip portion 4 a is flat. The gist is that a stepped chamfer having a minute step h having two ridges 1 ₁ and 1 ₂ is formed on the peripheral edge A of both end faces in the pressing direction.

As described above, there are two types of resonant elements, a cylindrical type and a columnar type, and can be classified into a coated type and an uncoated type depending on whether or not an electrode is formed. It can be applied to the manufacture of devices. Then, a stepped chamfer is formed on the peripheral portion of the axial end surface of the resonant element manufactured according to the present invention. That is, in the case of an uncoated type having a cylindrical shape as shown in FIG. 1, a stepped chamfer is formed on the outer peripheral edge portion A ₁ of the axial end surface 1a thereof, and the cylindrical shape shown in FIG.
In the case of the coating type in which the whole is covered with the electrode material 2 as shown in Fig. 2, both the inner and outer peripheral edge portions A ₁ and A _{2 of} both end surfaces in the axial direction are covered.
To be stepped chamfer is formed respectively, also uncoated type shown in FIG. 3 the apparatus having the columnar regardless of coating type shown in FIG. 4, the outer peripheral edge A ₁ of the axial end face in any case A stepped chamfer is formed.

[0016]

The function of the die punch 4 used for press molding is shown in FIG.
As shown in FIG. 4, since the working surface 4 ′ has a mortar shape and the peripheral edge tip portion 4 a has a flat shape, the working surface 4 ′ can be used like a die punch used for ordinary chamfered chamfering. The peripheral edge tip portion 4a of ′ is not easily worn or broken during press molding, and the abrasion of the peripheral edge tip portion 4a does not cause large burrs E. Therefore, the durability and moldability of the molding die can be significantly improved.

[0017]

EXAMPLE FIG. 5 shows a chamfered shape of a resonant element manufactured according to the present invention. As shown in the figure, this chamfering is performed by forming an obtuse angled surface 1 on the end surface (end surface in the pressing direction) 1a.
b is connected, and the stepped surface 1c is connected to this, forming a staircase shape connected to the peripheral surface (outer peripheral surface or inner peripheral surface) 1d, and two ridges 1 _{1 and} 1 ₂ are respectively the end surface 1a and the inclined surface. 1b and between the stepped surface 1c and the peripheral surface 1d.
The chamfer is formed in such a step-like shape in order to create the chamfer in the step of press molding, and imparts a required strength to the peripheral edge tip portion 4a of the working surface 4'of the die punches 4, 4, which will be described later. It depends.

In the stepped chamfer as shown in the figure, the step h between the _two ridges 1 ₁ and 12 is about 0.1 to 1 mm, and the angle θ between the end face 1a and the inclined face 1b is 110. It is preferable that the width B of the stepped surface 1c is about 0.05 to 0.5 mm at about 160 °.

Further, the two ridges 1 ₁ and 1 ₂ have 0.1 to 1
It is better to add a radius of about 0.3 mm. In this case, the R plane is press-molding of the end face-side edge portion 1 _1, it is sufficient to create at the same time as the formation of stepped shape itself, circumferential surface R side of the ridge portion 1 ₂ by barrel pressurized after firing, Bali It is good to make it at the same time as taking.

Hereinafter, the manufacturing method of the present invention will be described with reference to a cylindrical and covered resonance element shown in FIG.

First, press molding of ceramic powder is performed as shown in FIG.
Do it like i. That is, the pressing device uses a die die 3 having an inner shape corresponding to a required outer shape, and a core 5 having a required diameter is set at the center of the inside. The upper and lower mold punches 4 and 4 are cylindrical with a hole through which the core 5 is inserted, and the annular working surface 4'is like a mortar that is recessed inward and the tip ends of the inner and outer peripheral edges thereof. 4a ₁ and 4a
_{The one in which 2} is formed flat is used. The shape of the working surface 4'is basically made to correspond to the target stepped chamfered shape and size described in FIG. In addition, 0.1 mm is provided at the boundary between the bottom surface of the concave surface of the working surface 4'and the peripheral surface.
The degree R is attached.

Using such an apparatus, a required amount of ceramic powder is filled in the die die 3, and pressure molding is applied to the upper and lower die punches 4 and 4. As a result, both inner and outer peripheral edge portions A _1, A _{2 of the} end surface in the pressure direction are formed as shown in FIG.
Has a stepped shape with _two ridges 1 ₁ , 1 ₂ , one end face side ridge 1 ₁ has a required R, and the other peripheral face side ridge 1 ₂
Has no roundness (a burr S ₃ is generated here, but this burr S ₃ is very thin and can be easily removed by barreling or the like), so that a molded product having an intermediate chamfer is produced.

Then, the molded product is baked and solidified, and then barrel processed by a vibration mill or a rotary mill,
Towards the circumferentially side edge portions 1 ₂ as shown in FIG. Ha, simultaneously formed into a required R-surface with burr S ₃ removal. This barrel processing is
If the target radius R is about 0.3 mm or less, it is enough for two hours, and efficient work is possible.

When the resonance element as shown in FIG. 1 in which the inner peripheral edge portion A ₂ is not chamfered is press-molded, the working surface 4'of the die punches 4 and 4 described in FIG. 6A is modified. The inner wall of the mortar-shaped recess may be removed from the inner wall. When the columnar resonant element shown in FIGS. 3 and 4 is molded, a columnar or prismatic die punch having no hole for passing the core 5 in the center is used, and the working surface 4'is dented inward. It goes without saying that it may be bowl-shaped and the peripheral edge tip portion 4a may be flat.

In the case of manufacturing a resonance element of the electrode material 2 coating type, the molded product after the press molding is dipped in a conductive paint, the paint is dried and then baked.

[0026]

As described above, since the resonance element manufactured according to the present invention has stepped chamfers already formed on the peripheral edge of the end face at the stage of pressure molding, the subsequent manufacturing process and subsequent Not only can it effectively prevent cracks and chips from being generated at the handling stage due to impact, but especially in the case of a coating type, the coating thickness (electrode formation thickness) is small at the peripheral edge of the end face during electrode formation. It is possible to prevent this from happening and obtain a uniform coating. Moreover, compared with the case where the same effect is achieved by mere R chamfering, the number of man-hours and time required for manufacturing are remarkably reduced, and the die itself is made of metal as compared with the case where a normal mere chamfered chamfer is formed. Less wear and damage to the tip of the die punch,
Very little burr is generated, and its durability and formability are remarkably improved, and very efficient production can be realized.
Therefore, the present invention greatly contributes to improvement in manufacturing yield and reliability of this type of resonant element.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing an example of a resonant element manufactured according to the present invention.

FIG. 2 is a vertical sectional side view showing another example of the resonant element manufactured according to the present invention.

FIG. 3 is a vertical sectional side view showing another example of the resonant element manufactured according to the present invention.

FIG. 4 is a vertical sectional side view showing another example of a resonant element manufactured according to the present invention.

FIG. 5 is a partially enlarged explanatory view showing a preferred example of stepped chamfer formed according to the present invention.

6A to 6C are views for explaining the manufacturing process of the present invention.

FIG. 7A and FIG. 7B are perspective views showing the occurrence of cracks in the resonance element.

FIG. 8 is a vertical cross-sectional view showing a state of electrode formation in the coating type.

FIG. 9 is a perspective view illustrating a chamfered shape of a conventional resonance element.

FIG. 10 is a cross-sectional view of a main part for explaining a conventional die for punching a resonance element.

FIG. 11 is a cross-sectional view of a main part of a resonant element showing a burr.

FIG. 12 is a cross-sectional view of an essential part for explaining a resonance element molding die punch according to the present invention.

[Explanation of symbols]

1 _1, end face side ridge 1 ₂ peripheral face side ridge 1a end face 1b inclined face 1c stepped flat face 1d peripheral face A ₁ end face outer peripheral line portion A ₂ outer edge 2 electrode material 4 die punch 4 ′ working face 4a peripheral edge Tip

Claims (1)

[Claims] 1. A process for producing a ceramic dielectric resonator, wherein ceramic powder filled in a die die 3 is press-formed from above and below with die punches 4 and 4, and then the formed article is fired to obtain a finished product. The working surface 4'of the die punches 4, 4 is in the shape of a mortar that is recessed inward, and its peripheral edge tip portion 4a is formed.
Has a flat shape, and a stepped chamfer with a minute step h having two ridges 1 ₁ and 1 ₂ is formed on the peripheral edge A of both end surfaces in the pressing direction of the molded product. Method for manufacturing ceramic dielectric resonator.