JP2002316308A - Method for forming hole of hot-pressed sintered body and manufacturing method for ceramic heater type glow plug - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a hole 106 in the end part of a hot-pressed sintered body 102B by a simple method and at a low cost. SOLUTION: A hole forming member 104 constituted of a high-melting metal material is buried in a hot press sintering material 102, in the direction of intersecting perpendicularly the axial direction P of a hot press and so that the end face of the member 104 accords with the end face of the sintering material 102. The high-melting metal being the material of the hole forming member 104 has a larger expansion coefficient than the sintering material 106 and a melting point higher by 1.3 times or more than a hot press temperature. When the sintered body 102B obtained by the hot press is subjected to ultrasonic cleaning in water, the hole forming member 104 comes off and the hole 106 is formed in the sintered body 102.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a hole at an end of a hot-press sintered body, and more particularly to a method for hot-pressing by embedding a hole-forming member in an inorganic material for hot-press sintering. Then, a hole forming method of a hot press sintered body for forming a hole by removing a hole forming member from the sintered body, and one electrode and an electrode of a heating element of a ceramic heater used for a ceramic heater type glow plug The present invention relates to a method for manufacturing a ceramic heater type glow plug, which includes a step of forming an electrode extraction metal fitting hole at an end of a ceramic heater to connect the extraction metal fitting.

[0002]

2. Description of the Related Art A hole forming member made of a high melting point metal is buried in a sintered material, a ceramic sintered body is formed by hot pressing, and then the hole forming member is removed by machining such as cutting or melting. Accordingly, a method of forming a hole in a sintered body has already been known (Japanese Patent Application Laid-Open No. 2000-2000).
No. 121055).

In the above publication, as a method for removing a hole forming member from a sintered body, hot pressing is performed by using Mo (molybdenum) as a material for the hole forming member and using silicon nitride or the like as a sintered material. A method is disclosed in which a ceramic sintered body is formed by performing the method, and the sintered body is immersed in a mixed solution of aqua regia and sulfuric acid for 24 hours to dissolve the Mo hole forming member and form a hole.

[0004]

The method of dissolving Mo or the like with aqua regia is an effective method that can easily form a hole even in a sintered material that is difficult to cut at low cost. However, this method has a problem in working environment because aqua regia is used as the acid. When the method of forming the holes by dissolving the hole forming member with aqua regia is applied to a ceramic heater of a glow plug, a heating element embedded in the ceramic heater, a lead of the heating element, or a ceramic. There is a problem that the heater itself may be damaged.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method for forming a hole in a hot-press sintered body that can easily form a hole in the hot-press sintered body at low cost. It is the purpose. It is another object of the present invention to provide a method of manufacturing a ceramic heater type glow plug in which a heating element, a lead, and the like of a ceramic heater formed by hot pressing are not likely to be damaged by melting with aqua regia.

[0006]

A method of manufacturing a ceramic heater type glow plug according to the present invention comprises the steps of: forming a hole forming member made of a high melting point metal in a hot press sintered material in a direction substantially perpendicular to the axis of the hot press. Embedding, after hot pressing, by removing the hole forming member, a method of forming a hole in the hot press sintered body, particularly,
The hole forming member has a larger linear expansion coefficient than the sintered material, and has a melting point of 1.10 with respect to the hot pressing temperature.
After selecting a material three times or more higher and performing the hot pressing, by applying vibration to the hot pressed sintered body, the hole forming member was removed to form a hole in the sintered body. Things.

According to a second aspect of the present invention, in the method for forming a hole in a hot-press sintered body according to the first aspect, ultrasonic vibration is applied to the hot-press sintered body after hot pressing. The hole forming member is removed by applying.

Further, according to a third aspect of the present invention, in the method of forming a hole in a hot-press sintered body according to the first aspect, the hot-pressed sintered body after hot pressing is subjected to ultrasonic cleaning. By performing this, the hole forming member is removed.

According to a fourth aspect of the present invention, in the method of forming a hole in a hot-pressed sintered body according to the third aspect, the hot-pressed sintered body after hot pressing is superposed in an acid. The hole forming member is removed by performing ultrasonic cleaning.

In the method according to any one of the first to fourth aspects of the present invention, a material having a higher linear expansion coefficient than the inorganic material for sintering and having a melting point 1.3 times or more higher than the hot pressing temperature. After forming the hole forming member in the sintered material and performing hot pressing, by performing ultrasonic cleaning and the like, the hole forming member is naturally dropped and removed,
Holes are formed in the hot pressed sintered body.

According to a fifth aspect of the present invention, there is provided a method for forming a hole in a hot-press sintered body according to any one of the first to fourth aspects, wherein the hole forming member has substantially the same diameter throughout. Characterized by a cylindrical shape.

According to a sixth aspect of the present invention, there is provided a method of forming a hole in a hot-press sintered body according to any one of the first to fourth aspects, wherein the hole forming member is embedded in the sintered material. Characterized in that it has a tapered shape whose diameter increases toward the outside.

According to a seventh aspect of the present invention, in the method for forming holes of a hot-press sintered body according to any one of the first to sixth aspects, the pressure release temperature in the hot press is set to a value lower than the hot press temperature. It is characterized in that it is set to 50% or more.

According to an eighth aspect of the present invention, in the method of forming a hole in a hot-press sintered body according to the fifth or sixth aspect, a mold release material is previously applied to the surface of the hole forming member. It is assumed that.

According to a ninth aspect of the present invention, there is provided a method for manufacturing a ceramic heater type glow plug, wherein an electrode extraction metal fitting mounting hole is formed on an end face opposite to a heat generating portion of the ceramic heater, and one end of the electrode extraction metal fitting is inserted into the mounting hole. Then, this electrode take-out fitting and one of the poles of the heating element of the ceramic heater are connected, especially at the end of the hot press sintered material, the linear expansion coefficient is larger than this material,
In addition, a hole forming member made of a material having a melting point of 1.3 times or more the temperature of the hot press is embedded in a direction substantially perpendicular to the axial direction of the hot press, and after hot pressing, vibration is applied to the sintered body. Then, the hole forming member is removed to form an electrode extraction fitting mounting hole at an end of the ceramic heater.

According to the ninth aspect of the present invention, the hole forming member embedded in the sintered body can be easily removed, and further, as in the case of dissolving with an acid such as aqua regia.
There is no risk of damaging the heating elements and leads embedded in the ceramic heater or the ceramic heater itself.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in the drawings. The method of the present invention is to form a hole forming member made of a high melting point metal in an inorganic material for hot press sintering,
The hole is formed in a hot press sintered body by embedding in a direction substantially perpendicular to the axis of the hot press and performing hot pressing, and then removing the hole forming member, thereby forming a hole in the hot press sintered body. This is a method in which a small-diameter hole into which a thin wire such as an electrode extraction metal fitting can be inserted is formed at an end of a sintered body formed by hot pressing, such as a ceramic heater used as a heating element.

FIGS. 1 to 4 show the steps of the method for forming the holes in the hot-pressed sintered body. Each of the steps of the method for forming the holes will be described sequentially with reference to these figures.

First, a powder 102 of an inorganic material for sintering such as silicon nitride is filled in cavities of upper and lower molding dies (not shown), and a substantially cylindrical hole made of a high melting point metal is interposed therebetween. Press forming is performed with the forming member 104 sandwiched (see FIG. 1) to obtain a molded product 102A of the sintered material (FIG. 2).
reference). The hole forming member 104 is embedded in the molded product 102A of the sintered material in a direction substantially perpendicular to a direction in which hot pressing is performed (a direction indicated by an arrow P in FIG. 2). End face 104 of hole forming member 104 in a buried state
a is a side surface 102Aa of a molded product 102A of the sintered material.
It is exposed to.

Then, hot pressing is performed on the molded product 102A of the sintered material in which the hole forming member 104 is embedded. 3A and 3B show a state after hot pressing the sintered material 102A in which the hole forming member 104 is embedded, that is, the hole forming member 1 in the hot pressed sintered body 102B.
04 shows the state where it was held.

FIG. 5 is a graph showing an example of the relationship between the temperature at the time of performing the hot pressing and the pressurization timing. The temperature rise / fall pattern is as follows. After reaching the maximum temperature (hot press temperature), the temperature is maintained for 60 minutes, and then the inside of the furnace is cooled. Hot pressing is performed at an appropriate time in the temperature pattern. In the figure, the temperature T1 is the hot press pressure start temperature, T is the hot press temperature, T2 is the hot press pressure release temperature, and the temperature changes from T1 to T and T
The hot press is performed for a period of time until cooling to 2.
Note that TH is a temperature of hot press temperature T × 50%, and the release of hot press pressure is performed at a temperature higher than TH.

After performing the hot pressing as described above,
The hole forming member 104 embedded in the hot-press sintered body 102B is removed by performing ultrasonic cleaning in water, and a hole 106 is formed in the sintered body 102B (FIG. 4).
(See (a) and (b)). As described above, conventionally, the hole forming member is removed by dissolving with an acid such as aqua regia after hot pressing, but in the present invention, the inorganic material 102 for hot press sintering and the hole forming member 104 are formed. By limiting the conditions such as the linear expansion coefficient of the high melting point metal material and the melting point of the hole forming member 104 with respect to the hot pressing temperature T to a certain range, after hot pressing, the ultrasonic cleaning is simply performed in water. The forming member 104 is a sintered body 102B
, And is naturally removed from the substrate, and the hole 106 can be formed as described above.

The inorganic material for sintering 102 and the hole forming member 1
The above-described conditions for the linear expansion coefficient of 04 and the melting point of the hole forming member 104 with respect to the hot press temperature T can be obtained by experiments described below, and the effects thereof have been confirmed.

In this experiment, four types of inorganic materials shown in FIG. 6 were used as the hot press sintering material 102, and a hole forming member 104 made of various metal materials described later was placed in each of the sintering materials 102. Each of them was embedded in a direction orthogonal to the axial direction P of the hot press, and hot press was performed. A first experiment using a cylindrical member having the same diameter over the entire length of the hole forming member 104, and a tapered shape of the hole forming member (see reference numeral 140 in FIG. 11 described later). Was carried out with the large diameter side being outside. Experimental results for the respective sintered materials 102 will be described sequentially.

In the first experiment, first, as (1), hot pressing was performed using silicon nitride as the sintering material 104. This sintered material 102 was obtained by mixing 4 wt% of alumina and 4 wt% of yttria as a sintering aid with silicon nitride powder, and wet-mixing followed by drying to obtain a raw material powder. Each of the hole forming members 104 formed of various refractory metal materials shown in FIG.
Were hot-pressed so as to be orthogonal to the hot-press axis P.

The hot pressing temperature T is almost 100% in the composition of the sintered material 102 mainly composed of silicon nitride.
The temperature was set to 1700 ° C. at which densification progressed, and nitrogen gas was used as an atmosphere. Pressing start temperature of hot press (T in FIG. 5)
1) and the pressure release temperature (T2 in FIG. 5) were set to 1400 ° C., which is about 80% of the hot press temperature T (see FIG. 6).

As the material of the hole forming member 104, six kinds of high melting point metals shown in FIG. 7 were used. The melting point (M) of each of these high melting point metal materials, the ratio (M / T) between these melting points (M) and the hot pressing temperature (T), and the coefficient of linear expansion (E
2) and the ratio (E2 / E) of the linear expansion coefficient (E2) of these to the linear expansion coefficient (E1) of silicon nitride as the sintered material 2
1) is as shown in the table of FIG. The coefficient of linear expansion (E1) of silicon nitride is 3.20E-06. The shape of the hole forming member 104 is the same diameter over the entire length, and the size is φ0.8 mm × 10 mm.

The sintered material 102 containing silicon nitride as a main component
Then, the hole forming members 104 made of six kinds of metal materials are respectively embedded therein, hot-pressed, and then subjected to underwater ultrasonic cleaning, so that the hole forming members 104
Whether or not holes were formed was determined based on whether or not the hole 2B exited. The results are shown in the last column of the table shown in FIG.
As a result of this experiment, all the hole forming members 104 made of tungsten, tantalum, and molybdenum escaped from the silicon nitride sintered body 102B to form the holes 106. On the other hand, in the case of the hole forming member 104 made of vanadium, chromium, or zirconium, none of the holes escaped from the sintered body 102B, and no holes 106 were formed. The melting points (M) of these three metals in which the holes 106 are not formed are not so high with respect to the hot pressing temperature (T) (the melting point (M) is almost 1.1 times the hot pressing temperature (T)). The points are common.

In the first experiment (2), hot pressing was performed using aluminum nitride as the sintering material 102. This sintered material 102 was mixed with aluminum nitride powder and 4 wt% of yttria as a sintering aid, wet-mixed and dried to obtain a raw material powder. A hole forming member 104 made of various metals shown in FIG. 8 was embedded in the sintered material 102 in a direction perpendicular to the hot press axis P, and hot pressing was performed. The hot pressing temperature (T) is set to
In the composition No. 02, the densification proceeds almost 100% 1
650 ° C., and the pressing start temperature (T1) and the pressing release temperature (T2) of the hot press are the hot press temperature (T)
The temperature was set to 1400 ° C., which is about 80% of the above (see FIG. 6). The coefficient of linear expansion (E1) of aluminum nitride is 4.00E-06. In addition, nitrogen gas was used as the atmosphere. The shape and dimensions of the hole forming member 104 were set to φ0.8 × 10 mm as in the case of the experiment (1) using silicon nitride.

The aluminum nitride having the above composition is used as the sintered material 102, the hole forming member 104 made of the above-mentioned six kinds of metal materials is embedded in the sintered material 102, hot-pressed, and then subjected to underwater ultrasonic cleaning. The hole forming member 10
Whether or not holes were formed was determined based on whether or not No. 4 escaped. The results are shown in the last column of the table shown in FIG. As a result of this experiment, part (4/10) of the tungsten hole forming member 104 escaped from the sintered body 102A and the hole 106 was formed.
Was formed, but the remaining (6/10) did not escape, and the hole 1
06 was not formed. In the case of tungsten, it is considered that the linear expansion coefficient (E2) was not so different from the linear expansion coefficient (E1) of aluminum nitride. Further, the hole forming members 104 made of tantalum or molybdenum all escaped from the sintered body 102B mainly made of aluminum nitride to form the holes 106. On the other hand, none of the hole-forming members 104 made of materials of panadium, chromium, and zirconium escaped from the sintered body 102B, and no holes 106 were formed. These three metals in which the holes 106 were not formed have a melting point (M) with respect to the hot pressing temperature (T).
In that the melting point (M) is about 1.1 to 1.2 times the hot pressing temperature (T).

Next, as a third experiment (3), hot pressing was performed using alumina as the sintered material 102.
In this experiment, hot pressing was performed by embedding hole forming members 104 made of various metals shown in FIG. 9 in a direction orthogonal to the hot press axis P in alumina powder. In this experiment, an experiment was also conducted on a hole forming member 104 made of titanium and pure iron in addition to the same six kinds of metals as in the case of silicon nitride (see FIG. 7) and the case of aluminum nitride (see FIG. 8). . The hot pressing temperature (T) depends on the sintering material 10
In the composition of No. 2, the densification proceeds almost 100% 13
The temperature was set to 00 ° C., and the pressure start temperature (T1) and the pressure release temperature (T2) of the hot press were set to 1000 ° C., which is about 80% of the hot press temperature (T). Argon was used as the atmosphere. The coefficient of linear expansion (E1) of alumina is
8.00E-06. The size of the hole forming member 104 is φ φ as in the cases of the experiments (1) and (2).
0.8 × 10 mm.

In this experiment (3), the hole forming member 104 made of all metal materials did not come out of the sintered body 102B by ultrasonic cleaning in water after hot pressing.
No hole 106 was formed at the end of the sintered body 102B.

As (4) of the first experiment, hot pressing was performed using zirconia as the sintered material 102. In this experiment, zirconia powder was applied to yttria 5.2.
% By weight, wet-mixed and dried to obtain a raw material powder. In the sintered material 102 mainly composed of zirconia,
Hot pressing was performed by embedding hole forming members 104 made of various metals shown in FIG. 10 in a direction orthogonal to the hot press axis P. Also in this experiment, the hole forming member 104 was formed of the same eight kinds of metals as in the experiment (3) using the alumina as the sintered material 102. The hot press temperature (T)
In the composition of the sintered material 102, the temperature is set to 1400 ° C. at which the densification proceeds almost 100%, and the pressing start temperature (T1) and the pressing release temperature (T2) of the hot press are about 80% of the hot press temperature (T). % Of 1100 ° C. In addition,
The linear expansion coefficient (E1) of zirconia is 9.20E-06.
It is. Argon was used as the atmosphere. The dimensions of the hole forming member 104 were φ0.8 × 10 mm as in the case of the experiment (1) using silicon nitride.

In this experiment (4), as shown in the rightmost column of FIG. 10, all the metal hole forming members 104 were subjected to ultrasonic cleaning in water after hot pressing.
2, the hole 106 was not formed at the end of the sintered body 102.

From the results (1) to (4) of the first experiment (see FIGS. 7 to 10), the linear expansion coefficient (E2) of each metal forming the hole forming member 104 is
When the linear expansion coefficient (E1) was smaller than 2, the hole 106 was not formed in the sintered body 102B. Further, even when the melting point (M) of each metal is less than 1.3 times the hot pressing temperature (T), all the holes 1 are formed in the sintered body 102B.
06 was not formed. Therefore, the linear expansion coefficient (E2) of the hole forming member 104 made of a high melting point metal is
02 is larger than the linear expansion coefficient (E1), and the melting point (M) of the hole forming member 104 is higher than the hot pressing temperature (T).
By selecting a material 1.3 times higher than
These experiments confirmed that when ultrasonic cleaning in water was performed after hot pressing, the hole forming member 104 fell off the sintered body 102B to form the hole 106.

Next, as a second experiment, the hole forming member 14 was used.
The same method as in the first experiment was carried out by changing the shape of 0 as shown in FIG. As shown in FIG. 11, the hole forming member 140 has a tapered shape, a total length of 10 mm, an outer diameter on the large diameter side of φ1.0 mm, and a 1/10 taper. The hole forming member 140 having this shape was embedded with the large-diameter side (the left end in FIG. 11) facing the outside of the sintered material 102, and hot pressing was performed. The kind of the high-melting point metal which is the material of the inorganic material 102 for sintering and the hole forming member 140 in the second experiment is the same as that of the first experiment.
02 is the same. The hole forming member 1
The four types of inorganic materials 10 for sintering shown in FIG.
With respect to 2, the experiments (1) to (4) were performed in the same manner as the first experiment.

The results of (1) to (4) of the second experiment are shown in FIGS. 12 to 15, respectively. The results of the second experiment were almost the same as the results of the first experiment,
In some cases, it was recognized that the removal of the hole forming member 140 tended to be easier compared to the results of the first experiment. It is considered that this is because the hole forming member 140 was provided with a draft, so that the hole forming member 140 was easily pulled out.

Next, as a third experiment, in order to examine whether or not the pressure release temperature (T2) of the hot press affects the ease with which the hole forming member 104 is removed, the hot press pressure is used. An experiment was performed in which the release temperature (T2) was changed.
In the third experiment, as shown in FIG. 16, the experiment was performed only on two kinds of inorganic materials 102 for sintering, that is, silicon nitride and aluminum nitride. The hot press temperature (T)
As in the first experiment, silicon nitride was 1700 ° C.
The temperature of aluminum nitride is 1650 ° C. The hot press pressure start temperature (T1) was set to 1400 ° C. in each case.

FIG. 17 (when the sintered material 102 is silicon nitride) and FIG.
(In the case where 02 is aluminum nitride), hot pressing was performed by embedding hole forming members 104 made of six kinds of high melting point metals shown in FIG.
The shape of the hole forming member 104 has the same diameter over the entire length as in the first experiment. With the above samples, the hot press unloading temperature (T2) was increased to 1400 ° C., 1700 ° C., 1000 ° C., and 850 ° C. as shown in FIGS.
And hot pressing was performed at five stages of 600 ° C.

In the third experiment, the ultrasonic cleaning was performed in water after the hot press was performed.
It was determined whether or not the hot press pressure release temperature (T2) had an effect on the removability of the hole forming member 104 based on whether or not the sample No. 4 escaped from the sintered body 102B. As a result, as shown in the rightmost columns of FIGS. 17 and 18, when the hot press pressure release temperature (T2) is 600 ° C., that is, when the hot press pressure release temperature (T) is significantly lower than １ ／ of the hot press temperature (T). Although the hole forming member 104 was hard to fall off, there was no difference in the removability of the hole forming member 104 unless the temperature was lower than 1/2 of the hot press temperature (T). Although good results are shown when the load is unloaded at the highest temperature (hot press temperature T), the pressure release temperature (T2) is somewhat lower in a case where the adhesion to the built-in member is a problem. Is more desirable. Therefore, it is considered that the pressure release temperature (T2) may be selected within a range of up to 1/2 of the hot press temperature (T).

Further, as a fourth experiment, the hole forming member 1
04 in which a release material has been applied in advance.
It was confirmed about the ease of getting out of 2B. In this experiment, the same silicon nitride and aluminum nitride as in the third experiment were used as the inorganic material 102 for sintering, and the hole forming member 1 was used.
No. 04 was manufactured from the high melting point metal shown in FIGS. A release material containing BN (boronite) powder as a main component is applied to the surface of the hole forming member 104 in advance. The hole forming member 104 to which the release material is applied and the hole forming member 104 whose surface is unprocessed are each made of the sintered material 1
02 was hot-pressed by embedding in a direction orthogonal to the hot-press axis P. Thereafter, ultrasonic cleaning was performed in water, and it was determined whether or not the hole forming member 104 came off.

The results are as shown in the rightmost columns of FIGS. 19 and 20. In some combinations, the effect that the hole forming member 104 is easily removed by applying the release material is obtained. Was. That is, in the case where the sintered material 102 is aluminum nitride and the hole forming member 104 is tungsten, if the surface of the hole forming member 104 is untreated, a part (6/10) of the sample did not escape, When the release agent was applied, all the hole forming members 104 came off, and holes 106 were formed at the end of the sintered body 102B.

As a result of the first to fourth experiments, as a basic requirement of the hole forming member 104, the linear expansion coefficient (E
2) Select a metal whose coefficient of thermal expansion (E1) is larger than that of the sintered material 102, and select a high melting point metal whose melting point (M) is 1.3 times or more higher than the hot press temperature (T). It was confirmed that it was necessary to do. The hole forming members 104 and 140 are manufactured from a high melting point metal satisfying the requirements, and the hole forming members 104 and 140 are
2 and embedded in a direction orthogonal to the axial direction P of the hot press, and when hot pressing is performed, the hole forming members 104 and 140 fall off due to ultrasonic cleaning in water after the hot pressing, and holes are formed in the sintered body 102B. 106 is formed.

The shape of the hole forming members 104 and 140 is as follows.
It is formed in a columnar shape or a tapered shape in which the diameter gradually increases toward the outside in a state of being embedded in the sintered material 102.
Although a size of 8 × 10 mm was used, it is preferable that the size be at least 20 times smaller than the diameter of the hole 106 to be formed.

As a requirement of the manufacturing process, the pressure release temperature (T2) of the hot press is set to a point of 50% or more with respect to the hot press temperature (T). By subjecting the sintered body 102B subjected to the hot pressing under the above conditions to ultrasonic cleaning in water, the hot pressed sintered body 102B
The hole forming members 104 and 140 surely escape from the end of B, and the holes 106 are formed after the hole forming members 104 and 140 escape. Further, it has been clarified that coating the surface of the hole forming members 104 and 140 with a release material facilitates the removal of the hole forming members 104 and 140.

In the above experimental results, silicon nitride or aluminum nitride was used as the inorganic material 102 for sintering ceramics, and three kinds of refractory metals such as tungsten, tantalum and molybdenum were used as the materials of the hole forming members 104 and 140. When selected and combined, the hole forming member 1
04 and 140 fall off and a hole 10 is formed in the end of the sintered body 102B.
No. 6 was formed, but these materials are not limited to only the above-mentioned combination, but have a coefficient of linear expansion larger than that of the sintered material and a melting point of 1.3 times the hot pressing temperature. It is considered that the same result can be obtained by combining the sintered material 102 and the materials of the hole forming members 104 and 140 that satisfy the condition of “higher material of the hole forming member”.

In the above embodiment, after the hot press sintered body 102B is obtained, the hole forming members 104 and 140 are removed by ultrasonic cleaning in water. The hole forming member 1 can be formed by simply applying vibration to the
04, 140 could be removed. Also, if ultrasonic cleaning is performed in an acid such as aqua regia, the sintered body 10 can be more effectively used.
The hole forming members 104 and 140 can be removed from 2B.

In the above-described embodiment, the hole forming method capable of forming the hole 106 at the end of the general hot press sintered body 102B with a simple method and at low cost has been described. Hot press sintered body 102
The hole forming method of B can be applied to a ceramic heater used as a heating element of a glow plug. Next, a case where the present invention is applied to such a ceramic heater type glow plug will be described.

FIG. 21 is a longitudinal sectional view showing a ceramics heater-type glow plug having a ceramics heater having a hole (electrode take-out fitting mounting hole) formed on an end face by the above-described method as a heating element. The configuration of this ceramic heater type glow plug (indicated by reference numeral 1 as a whole) will be briefly described. Housing 2 of this glow plug 1
Has a substantially cylindrical shape, and on the right end side of the internal hole 4,
A metal outer cylinder 8 to which a ceramic heater 6 is joined by brazing is inserted, and a part of the outer peripheral surface of the metal outer cylinder 8 is fixed to the housing 2 by press-fitting or brazing.

The ceramic heater 6 has a heating wire (heating element) 64 in which a high-melting point metal (for example, tungsten (W) or the like) is coiled and embedded in a ceramic insulator 62 constituting a main body thereof. The heat generating portion 6a protrudes outward from the distal end 8a of the metal outer cylinder 8, and an end surface 6b farther from the heat generating portion 6a is located inside the metal outer cylinder 8. are doing. In this embodiment, the heating element 6a is made of a high melting point metal. However, the heating element 6a may be a conductive ceramic or a sheet-shaped heating element, and a part of the conductive ceramic heating element is exposed from the insulating ceramic. Etc., ceramic heater 6
May be any as long as it is formed by combining insulating ceramics and an inorganic conductor as a heating element.

One end (lead on the positive electrode side) 64a of the coil-shaped heating wire 64 embedded in the ceramic heater 6 extends toward the end face 6b of the ceramic heater 6, and Is connected to one end 12a of the electrode take-out fitting 12. On the other hand, the other end (a negative electrode side lead) 64b is exposed on the outer surface of the ceramic insulator 62 inside the metal outer cylinder 8 and is electrically connected to the inner surface of the metal outer cylinder 8 by brazing. ing.

When the one end 12a of the electrode take-out fitting 12 is connected to the positive lead 64a of the ceramic heater 6, an electrode take-out fitting mounting hole 106 is formed in the end face 6b of the ceramic heater 6, and the electrode take-out fitting is formed. The side surface of the positive electrode lead 64a is exposed in the hole 106. The distal end portion 12a of the electrode take-out fitting 12 is inserted into the electrode take-out fitting mounting hole 106.
And brazing (for example, brazing with silver brazing material)
By doing so, the positive electrode side lead 64a of the ceramic heater 6 and the electrode take-out fitting 12 are electrically connected.

By performing the silver brazing as described above, the coil-shaped heating wire 6 embedded in the insulating ceramics 62 is formed.
An electrode take-out fitting 12 is connected to the positive electrode side lead 64a of the base 4 and a ceramic heater 6 having a metal outer cylinder 8 joined to an outer peripheral surface thereof is provided in a cylindrical housing 2 serving as a mount fitting to a cylinder head. , Inserted and fixed.

An end 12b opposite to the end 12a connected to the positive electrode lead 64a of the electrode take-out fitting 12 has:
One end 18a of the external connection terminal 18 is joined, and a screw portion 18b at the other end of the external connection terminal 18 projects outside from the large diameter portion 4c of the internal hole 4 of the housing 2.
The seal member 20 and the insulating bush 22 are fitted around the outer periphery of the screw portion 18b of the external connection terminal 18, and are inserted into the large diameter portion 4c. Further, a nut 24 is fastened and fixed to the fastening screw portion 18b of the external connection terminal 18 from outside.

The ceramic heater 6 provided in the glow plug 1 according to the above configuration has a hole (an electrode mounting bracket mounting hole) at the end located inside the metal outer cylinder 8 by the hole forming method. ) 106 is formed. When the mounting hole 106 is formed at the end of the ceramic heater 6, the upper and lower two inorganic materials 10 for sintering are formed as in FIG.
2, a heating wire 64 is arranged, and its positive lead 64
a is extended to the end opposite to the heating wire 64, the tip of the positive electrode lead 64 a is brought into contact with the hole forming member 104, and the end surface of the hole forming member 104 is
02 while being exposed on the end face. The direction of the hole forming member 104 is a direction orthogonal to the axial direction of the hot press.

The inorganic material 102 for sintering for forming the ceramic heater 6 and the high melting point metal material of the mounting hole forming member 104 are the same as those of the hole 10 obtained from the above-described experimental results.
6. A material which is easy to form is selected. That is, silicon nitride or aluminum nitride is selected as the sintering material 102, and tungsten, tantalum, molybdenum, or the like is selected as the high melting point metal as the material of the hole forming member 104.

The sintered material 102 and the hole forming member 10
4 is subjected to hot press pressure according to the hot press pattern shown in FIG. Thereafter, the hole forming member 104 falls off by performing ultrasonic cleaning in water, and the sintered body 102
An electrode extraction fitting mounting hole 106 is formed in B (ceramic heater 6). The end 12a of the electrode take-out fitting 12 is inserted into the mounting hole 106, and is brazed.
The end of the positive electrode side lead 64a and the end 12a of the electrode take-out fitting 12 are electrically connected.

In addition, in the combination of the above-mentioned materials, as shown in the above-mentioned experimental results, the electrode take-out fitting mounting holes 106 are surely formed by the ultrasonic cleaning after sintering. However, the present invention is not limited to only the above-mentioned materials. Needless to say, any combination may be used as long as the combination satisfies the condition of "a material for a hole forming member having a larger linear expansion coefficient than a sintered material and having a melting point 1.3 times or more higher than the hot pressing temperature".

[0059]

As described above, according to the present invention, a hole forming member made of a high melting point metal is buried in a hot press sintered material in a direction substantially perpendicular to the axis of the hot press.
After performing the hot pressing, by removing the hole forming member, in the method of forming a hole in the hot pressed sintered body, as the hole forming member, the linear expansion coefficient is larger than the sintered material, and, After selecting a material whose melting point is at least 1.3 times higher than the hot press temperature and performing the hot press, the hot press sintered body is vibrated to remove the hole forming member and fire. Since a hole is formed in the sintered body, the hole forming member embedded in the hot-press sintered body can be easily removed, and therefore, the hole can be formed easily and at low cost in the hot-press sintered body. can do. Further, it is advantageous in terms of working environment and cost as compared with the conventional method of removing the hole forming member of the high melting point metal by dissolving in aqua regia.

According to the ninth aspect of the present invention, an electrode extraction metal fitting mounting hole is formed on the end face opposite to the heat generating portion of the ceramic heater, and one end of the electrode extraction metal fitting is inserted into the mounting hole. In a method for manufacturing a ceramics heater type glow plug for connecting an electrode extraction metal fitting and one pole of a heating element of a ceramics heater, an end portion of a hot-press sintered material has a linear expansion coefficient larger than that of the material and a hot-press sintered material. A hole forming member made of a material having a melting point of 1.3 times or more with respect to the pressing temperature is embedded in a direction substantially perpendicular to the axial direction of the hot press, hot-pressed, and then the sintered body is vibrated by vibrating. By removing the hole forming member, by forming an electrode extraction metal fitting mounting hole at the end of the ceramic heater,
The hole forming member embedded in the hot press sintered body can be easily removed, and therefore, a mounting hole for connecting an electrode extraction metal fitting can be formed easily and at low cost at the end of the ceramic heater. This is advantageous in terms of working environment and cost as compared with the conventional method of removing the hole forming member of the high melting point metal by dissolving in aqua regia. Further, there is no possibility of damaging the heating element, the lead or the sintered body (ceramic heater) embedded therein.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first step of a method for forming holes in a hot-press sintered body according to one embodiment of the present invention.

FIG. 2 is a perspective view showing a second step of the hole forming method.

3A and 3B show a third step of the hole forming method, wherein FIG. 3A is a perspective view and FIG. 3B is a plan view.

FIG. 4 shows a fourth step of the hole forming method, wherein FIG. 4 (a) is a perspective view and FIG. 4 (b) is a plan view.

FIG. 5 is a graph showing a hot press pattern.

FIG. 6 is a table showing hot pressing conditions of the sintered materials used in the first and second experiments.

FIG. 7 is a table showing melting points and linear expansion coefficients of silicon nitride and a high melting point metal when silicon nitride is used as a sintered material in the first experiment, and the results of the experiment.

FIG. 8 is a table showing melting points and linear expansion coefficients of aluminum nitride and a high melting point metal and a result of the experiment in a case where aluminum nitride was used as a sintered material in the first experiment.

FIG. 9 is a table showing melting points and linear expansion coefficients of alumina and a high melting point metal and a result of the experiment when alumina was used as a sintered material in the first experiment.

FIG. 10 is a table showing the melting point and linear expansion coefficient of zirconia and a high melting point metal and the results of the experiment when zirconia was used as a sintered material in the first experiment.

FIG. 11 is a diagram showing a shape of a hole forming member used in a second experiment.

FIG. 12 is a table showing melting points and linear expansion coefficients of silicon nitride and a high melting point metal and a result of the experiment in a case where silicon nitride was used as a sintered material in the second experiment.

FIG. 13 is a table showing the melting point and linear expansion coefficient of aluminum nitride and a high melting point metal and the results of the experiment when aluminum nitride was used as a sintered material in the second experiment.

FIG. 14 is a table showing melting points and linear expansion coefficients of alumina and a high melting point metal and a result of the experiment in a case where alumina was used as a sintered material in the second experiment.

FIG. 15 is a table showing melting points and linear expansion coefficients of zirconia and a high-melting metal when zirconia is used as a sintered material in the second experiment, and the results of the experiment.

FIG. 16 is a table showing hot pressing conditions of a sintered material used in a third experiment.

FIG. 17 is a table showing melting points and linear expansion coefficients of silicon nitride and a high-melting metal and a result of the experiment when a third experiment was performed using silicon nitride as a sintered material.

FIG. 18 is a table showing melting points and linear expansion coefficients of aluminum nitride and a high melting point metal, and a result of the experiment, in a case where the third experiment was performed using aluminum nitride as a sintered material.

FIG. 19 is a table showing melting points and linear expansion coefficients of silicon nitride and a refractory metal when silicon nitride is used as a sintered material in a fourth experiment, and the results of the experiment.

FIG. 20 is a table showing melting points and linear expansion coefficients of aluminum nitride and a high melting point metal, and a result of the experiment, in the case where aluminum nitride was used as a sintered material in the fourth experiment.

FIG. 21 is a longitudinal sectional view showing an example of a ceramic heater type glow plug manufactured by the method according to claim 9.

[Explanation of symbols]

P Axial direction of hot press 6 Ceramic heater 6a Heating portion of ceramic heater 12 Electrode take-out fitting 12a Tip of electrode take-out fitting 64 Heating element (heating wire) 64a One pole of heating element of ceramic heater (positive electrode lead) 102 Sintered material 102B hot press sintered body 104 hole forming member 106 hole (electrode take-out fitting mounting hole)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // B22F 3/14 B28B 11/00 Z (72) Inventor Takashi Aota 3--13 Yayumicho, Higashimatsuyama-shi, Saitama No. 26 Bosch Automotive Systems Co., Ltd. Higashi-Matsuyama Plant (72) Inventor Shunji Miura 3-13-26 Yaumicho, Higashi Matsuyama City, Saitama Prefecture Co., Ltd. Bosch Automotive Systems Higashi-Matsuyama Plant (72) Inventor 3-13-26, Yayumicho, Ichigo Bosch Automotive Systems Higashimatsuyama Plant F-term (reference) 4G054 AA05 AB03 AB07 AB11 BB00 DA01 4G055 AA08 AB01 AC05 AC08 BA87 4K018 EA01 HA01 KA32 KA37

Claims (9)

[Claims] 1. A hole forming member made of a high melting point metal is buried in a hot press sintered material in a direction substantially perpendicular to the axis of the hot press, and after hot pressing, the hole forming member is removed. In the method of forming a hole in a hot-press sintered body, the hole-forming member has a linear expansion coefficient larger than that of the sintered material, and has a melting point of 1.10 with respect to the hot-press temperature.
After selecting a material three times or more higher and performing the hot pressing, by applying vibration to the hot pressed sintered body, the hole forming member is removed to form a hole in the sintered body. A method for forming holes in a hot pressed sintered body. 2. The method for forming holes in a hot-press sintered body according to claim 1, wherein the hole-forming member is removed by applying ultrasonic vibration to the hot-press sintered body after hot pressing. A method for forming holes in a hot-press sintered body, characterized in that: 3. The method for forming holes in a hot-press sintered body according to claim 1, wherein the hole-forming member is removed by performing ultrasonic cleaning on the hot-press sintered body after hot pressing. A method for forming holes in a hot-press sintered body, characterized in that: 4. The method of forming holes in a hot-press sintered body according to claim 3, wherein the hot-pressed sintered body after hot pressing is subjected to ultrasonic cleaning in an acid to thereby form the hole forming member. A method for forming a hole in a hot-pressed sintered body, characterized in that the hole is removed. 5. The method for forming a hole in a hot-press sintered body according to claim 1, wherein the hole forming member has a columnar shape having substantially the same diameter throughout. A method for forming holes in a hot pressed sintered body. 6. The method for forming a hole in a hot-press sintered body according to claim 1, wherein the hole-forming member has a taper whose diameter increases toward the outside of the buried sintered material. A method of forming a hole in a hot-press sintered body, characterized in that the hole has a shape. 7. The method for forming holes in a hot-press sintered body according to claim 1, wherein the pressure release temperature in the hot press is set to 50% or more of the hot press temperature. A method for forming holes in a hot pressed sintered body. 8. The method for forming a hole in a hot-press sintered body according to claim 5, wherein a release material is applied in advance to a surface of the hole-forming member. Hole forming method. 9. An electrode take-out fitting mounting hole is formed on the end face opposite to the heat-generating portion of the ceramic heater, and one end of the electrode take-out fitting is inserted into the mounting hole, and the electrode take-out fitting and the heating element of the ceramic heater are formed. In a method for manufacturing a ceramics heater type glow plug for connecting to one of the poles, the end of a hot-press sintered material has a larger linear expansion coefficient than this material and a melting point of 1.3 relative to the hot-press temperature. By embedding a hole forming member made of a material twice or more in a direction substantially perpendicular to the axial direction of the hot press, performing hot pressing, and then applying vibration to the sintered body to remove the hole forming member, A method for manufacturing a ceramic heater type glow plug, comprising: forming an electrode extraction metal fitting hole at an end of a ceramic heater.