JP2000071223A - Method for powder pressure molding, cylinder with collar manufactured thereby and case for electric component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily mold a cylinder with a bottom having a collar at the outer periphery by powder pressure molding. SOLUTION: The method for powder pressure molding using a mold having a mortar-like body 8 including a step on the inner periphery, a lower punch 6, a first upper punch 4 provided at a position corresponding to the step and a second upper punch 4 provided at its inside comprises the steps of charging powder in a space formed of the mortar-like body 8 and the punch 6, lowering the punch 4, pressurizing the vicinity of the step of the mortar-like body 8, and then pressurizing the punches 4, 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a case for an electric component such as a case for a thermostat, and to a powder pressing method for producing the case.

[0002]

2. Description of the Related Art Conventionally, a thermostat as shown in FIG. 6 has been used as a temperature control component for home electric appliances, OA equipment, automobiles and the like. The temperature control of the heater section of the coffee maker and the temperature control of the toner baking section of the copying machine are examples of its use.

The temperature control mechanism of the thermostat determines the amount of arc-shaped deformation caused by the temperature change of the bimetal 39 by using a sliding pin 40.
, The amount of deflection of the contact fitting 42 and the rivet 43
This is a safety component that uses an electric switch mechanism to determine whether or not the terminal electrode 44 is in contact with the terminal electrode 44 fixed at a predetermined temperature. When a predetermined temperature is reached, the flow of electricity is interrupted and the temperature is prevented from rising to an abnormally high temperature.

[0004] Case 4 used in this thermostat
1 is a bimetal 3 which is a mechanical part of the thermostat
9, a case for protecting the sliding pins 40 and the contact fittings 42 and holding the pin guides 45. The case has a bottomed cylindrical body for holding each component. Is a shape having a brim on the outer periphery. In addition, in order to maintain insulation, it is formed of ceramics.

Therefore, when a cylindrical body having a brim on the outer periphery on the opening side is formed by ceramic powder pressing, a conventional method of forming the cavity portion downward as shown in FIG. Was common. This molding method is the first
An upper punch 21, a first lower punch 22, a second lower punch 23,
In this method, the powder 25 filled in the mouse 24 is compressed by the first upper punch 21 to obtain a compact 26.

[0006] Further, a molded body 27 having a flange on the outer periphery and having a flange on the outer periphery is a bottomed cylindrical body shown in FIG. 4 (c) because it has a cavity 28 and a flange 29 on the outer periphery. In order to obtain the shape shown in FIG.
As shown in (b), the cutting margin 30 of the molded body 26 must be subjected to cutting or grinding after sintering.

[0007] However, the latter post-sintering grinding process is not practical because of its high processing cost. Moreover, in the former case for the thermostat subjected to the cutting process, the processing streaks of the cutting tool remained on the surface, and the surface roughness of the outer peripheral surface was 1.8 μm or more. Therefore, when delicate characters such as voltage and control temperature are printed on the surface, there is an inconvenience such as bleeding.

In order to form the shape shown in FIG. 4 (c), the upper punch is divided into two parts, a first upper punch, a second upper punch, a first lower punch, and a second lower punch. It is necessary to carry out molding with a mold composed of a punch and a mouse. In this case, the thickness of the first upper punch for forming the collar is the same as the above-mentioned cutting margin, and is extremely thin. Molding could not be performed because the strength of the mold was not maintained.

Further, it was not possible to simultaneously mold the compact having a shape having a further convex shape on the side opposite to the opening having the shape shown in FIG. In order to form such a shape, a separately formed convex shaped body had to be joined in the sintering process.

For example, in the case of manufacturing a molded body 31 having a shape as shown in FIG. 5E, first, as shown in FIG.
(A) The molded body 27 having the brim portion 29 formed as in (c) is manufactured. On the other hand, as shown in FIG.
Upper punch 32, first lower punch 33, second lower punch 34,
Powder 3 composed of a mold of the us 35 and filled in the us 35
6 is compressed by the first upper punch 32 to form a molded body 38 having a convex portion 37 as shown in FIG.
As shown in (e), both had to be combined in the sintering process.

[0011]

As described above, according to the conventional method, in order to obtain a sintered body of a bottomed cylindrical body having a brim on the outer periphery, at least three steps of powder pressing, cutting and firing are required. is necessary. Further, in order to obtain a sintered body having a convex shape on the surface opposite to the opening of the cylindrical body having a flange on the outer periphery, at least a molding step of two types of molded bodies, joining of the two molded bodies, and firing Four steps were required, and in order to obtain a sintered body having a brim, at least five steps were required due to additional cutting.

[0012] Therefore, the process is long and time-consuming, and furthermore requires a processing cost. Further, when a case for an electric component such as a case for a thermostat is produced by this method, processing streaks remain on the surface of the case, which is not suitable for printing delicate characters.

[0013]

According to the present invention, there is provided a mouse having a step on the inner periphery thereof, a lower punch, a first upper punch provided at a position corresponding to the step, and a second punch provided on the inside thereof. Using a mold composed of upper punches, the filled powder is first pressed down near the step of the mouse by lowering the first upper punch, and then the upper and lower punches are pressed to form a brim on the outer periphery. This is for molding a bottomed cylindrical molded body having the same.

Further, the present invention is characterized in that a case for an electric component is formed by molding and firing by the above method.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

As shown in FIG. 1 (b), a bottomed cylindrical body 1 obtained by the method of compacting ceramic powder according to the present invention and having a brim on the outer periphery has a cavity 2 and an outer periphery on the opening side thereof. Has a brim portion 3 provided for.

As shown in FIG. 1 (a), the method of forming the molded body 1 includes a first upper punch 4, a second upper punch 5, a first lower punch 6, and a brim portion for forming the cavity 2. 3 is formed by a mold of a usb 8 having a stepped portion 7 for forming the same. Then, in order to equalize the compression ratio between the cavity bottom and the wall, the second upper punch 5 is first inserted into the mouse 8 filled with the powder 9 to allow excess powder to escape from the mouse, and then the first upper punch 4 is inserted into the mouse. Insert and compress the powder in the mouse with both punches to form a compact 1
Can be obtained.

FIG. 3 shows the pressing step of the powder pressing in detail. First, as shown in FIG. 3A, a powder 9 is placed in a space formed by a mouse 8 having a step 7 on the inner periphery and a first lower punch 6.
And the second upper punch 5 is inserted into the mouse 8 to allow excess powder to escape from the mouse, and the first upper punch 4 and the second upper punch 5 are lowered. Then, as shown in FIG. 3B, the first upper punch 4 first presses the vicinity of the step portion 7 of the bulge serving as a brim. Then, as shown in FIG. While lowering the first upper punch 4 and the second upper punch 5 and pressurizing the whole, the whole is formed.

By molding in such a manner, a molded article 1 of a bottomed cylindrical body having a brim on the outer periphery without cutting.
Can be easily obtained.

In another embodiment, as shown in FIG. 2 (b), a molded body 10 having a convex shape on the surface opposite to the cavity portion in the ceramic powder press molding and further having a brim is also provided. It can be molded in the same manner.

As shown in FIG. 2A, the first upper punch 1
4. Second upper punch 1 for forming cavity 11
5. A die 19 having a first lower punch 16 and a second lower punch 17 for forming the projection 13 and a step 18 for forming the flange 12 is used. Then, in the same manner as above, the second upper punch 15 is first inserted into the mouse 19 filled with the powder 20 to make the compression ratio of the cavity bottom portion and the wall portion uniform, and extra powder is released from the mouse, and then the first upper punch 15 14 is inserted into a mouse, and the powder in the mouse is compressed by both punches to form a compact 10.
Can be obtained.

According to this method, a molded body having a convex shape on the surface opposite to the surface on which the cavity is formed can be easily formed.

Each of the molded bodies 1 and 10 is fired under predetermined conditions to form a thermostat case 41 as shown in FIG. At this time, the outer periphery of the case is a surface that has been baked, and is formed not by cutting but by a die, so that a smooth surface having a surface roughness (Ra) of 1.8 μm or less can be obtained. Therefore, even if printing is performed on this surface, bleeding hardly occurs.

The thermostat case can be made of various ceramics such as forsterite, mullite, cordierite, etc. in addition to steatite and alumina.

Further, it goes without saying that the present invention can be applied not only to the case for the thermostat but also to cases for other various electric parts.

[0026]

Here, as a working example of the present invention, a molded article 1 having a bottom and having a brim on the outer periphery was produced on a trial basis as shown in FIG. As for the size, outer diameter a15.0mm, lower diameter b14.4mm,
The cavity diameter c is 12.4 mm, the thickness d is 6.8 mm, the cavity depth e is 4.8 mm, and the flange thickness is f0.8 mm. This formed body had dimensional accuracy that was not significantly different from that of a formed body that had been formed by the conventional method shown in FIG. Further, in the example of the present invention, the processed line on the surface could be eliminated, and the surface roughness was 1.8 μm or less.

Next, as an embodiment of the present invention, a molded body 10 having a convex shape on the surface opposite to the surface on which the cavity portion was formed as shown in FIG. The size is outer diameter g15.0mm, lower diameter h14.4m.
m, cavity diameter i12.4mm, thickness j11.5m
m, cavity depth k4.8mm, collar thickness l0.8m
m, the interval between projections is 6.7 mm, and the height of projections is 1.6 mm. This formed body was formed by the conventional method shown in FIG. 5 and had dimensional accuracy that was not significantly different from the combined body of the formed body subjected to the cutting process and the formed body having the convex shape. Further, in the embodiment of the present invention, the processing line on the surface can be eliminated, and the surface roughness is 1.8 μm.
It was below.

[0028]

As described above, according to the present invention, a mouse having a step on the inner periphery, a lower punch, a first upper punch provided at a position corresponding to the step, and a first punch provided on the inside thereof. (2) Using a mold composed of an upper punch, fill the space formed by the above-mentioned mouse and lower punch with powder, first lower the first upper punch, pressurize the vicinity of the step of the mouse, and then press each upper and lower punch. By pressurizing, a bottomed cylindrical body having an outer peripheral brim portion can be easily formed.

Therefore, the manufacturing process can be shortened,
In addition, products can be supplied at low cost. In addition, by eliminating the cutting process, there is no processing streak on the surface, and the surface can be finished in a state suitable for printing delicate characters, which is extremely effective.

[Brief description of the drawings]

FIG. 1 (a) is a cross-sectional view of a mold used in the powder pressing method of the present invention, and FIG. 1 (b) is a cross-sectional view of a molded article obtained by (a).

FIG. 2 (a) is a cross-sectional view of a mold used in the powder pressing method of the present invention, and FIG. 2 (b) is a cross-sectional view of a molded article obtained by (a).

FIGS. 3 (a) to 3 (c) are cross-sectional views showing a pressing step of powder pressing of the present invention.

4 (a) is a cross-sectional view of a mold used in a conventional powder pressing method, FIG. 4 (b) is a cross-sectional view of a formed body obtained by (a), and FIG. It is sectional drawing of the state which carried out.

5 (a) and 5 (b) are cross-sectional views of a mold used in a conventional powder press molding method, and FIG. 5 (b) is a cross-sectional view of a mold having a convex shape used in a conventional powder press molding method. , (C) is a cross-sectional view of the formed body obtained by (a), (d) is a cross-sectional view of the formed body obtained by (b), and (e) is a cross-sectional view of a formed body obtained by joining two formed bodies. It is.

FIG. 6 is a structural diagram of a thermostat.

[Explanation of symbols]

 1, 10: molded body 2, 11: cavity 3, 12: brim 4, 14: first upper punch 5, 15: second upper punch 6, 16: first lower punch 17: second lower punch 7, 18: Step 8,19: Us 9,20: Powder 41: Case 42: Contact fitting 43: Rivet 44: Terminal electrode 45: Pin guide 46: Cap

Claims (3)

[Claims] 1. A mouse having a step on its inner periphery, a lower punch,
Using a mold comprising a first upper punch provided at a position corresponding to the step and a second upper punch provided inside thereof, powder is filled into a space formed by the above-mentioned mouse and lower punch, A step of inserting a punch into the mouse, then lowering the first upper punch to press the vicinity of the step of the mouse, and then pressing the upper and lower punches to form a cylindrical body having a flange on the outer periphery. Pressure molding method comprising: 2. A cylindrical body having a brim obtained by molding a ceramic raw material powder according to the method of claim 1 and then firing. 3. A case for an electrical component, comprising a flange on the outer periphery of an opening end of a bottomed cylindrical body made of ceramics, the outer peripheral surface of which is as-baked surface.