JP6511315B2 - Method of manufacturing composite member and method of manufacturing glow plug - Google Patents

Description

  The present invention relates to a method of manufacturing a composite member in which a ceramic member is fitted into a metal member, and a method of manufacturing a glow plug.

  A glow plug provided with a ceramic heater is known as a type of glow plug. When manufacturing such a glow plug, generally, an operation of pressing a ceramic heater, which is a ceramic member, into a cylindrical or other metal member is performed. As described above, when pressing the ceramic member into the metal member, if the press-in load is set too high, the ceramic member may be damaged. In order to suppress the damage of the ceramic member during press-in, the press-in load is used. It is desirable to make it as low as possible. Therefore, conventionally, by applying a lubricant to at least one of the ceramic member and the metal member before press-fitting, the friction at the time of press-fitting is reduced, and the press-fitting load is reduced (for example, Patent Document 1) reference).

Patent No. 3176459 JP 2004-107768 A

  The lubricant reduces the press-in load at the time of press-in, but if a lubricant is present between the metal member and the ceramic member after the press-in, the bonding force between the two members joined by the press-in may be lost. Therefore, conventionally, heat treatment is performed after press-in to decompose and remove the lubricant. However, conventionally known lubricants generally have high thermal stability, and it has been difficult in some cases to sufficiently decompose and remove them by heat treatment. In particular, depending on the type of ceramic member used for press-fitting and the like, there is an upper limit to the temperature that can be adopted as the temperature of heat treatment, so it has been desired to sufficiently decompose and remove the lubricant while suppressing the heat treatment temperature. Moreover, since the conventionally known lubricants may have an insufficient effect of reducing the press-fit load, it has been desired to further reduce the press-fit load at the time of press-fit. Such a problem is not limited to the bonding between members including the ceramic heater constituting the glow plug, and is a problem common to press fitting a ceramic member into a metal member.

  The present invention has been made to solve the above-described problems, and can be realized as the following modes.

(1) According to one aspect of the present invention, there is provided a method of manufacturing a composite member in which a ceramic member is fitted into a metal member. In the method of manufacturing this composite member, a press-in step of press-fitting the ceramic member into the metal member; and prior to the press-in step, at least one of the metal member and the ceramic member, in the press-in step. An adhesion step of adhering a substance having an alkylene oxide group as a repeating unit in a region in which the metal member and the ceramic member are in contact with each other, wherein the number of repetition of the alkylene oxide group is 20 or more.
According to the method of manufacturing a composite member of this aspect, it is possible to reduce the press-fit load at the time of press-fitting the ceramic member into the metal member, and to suppress damage to the ceramic member at the time of press-fitting. Furthermore, if heat treatment is performed after the press-in process, the substance having the alkylene oxide group as the repeating unit can be easily decomposed and removed to enhance the bonding strength between the metal member and the ceramic member.

(2) According to another aspect of the present invention, there is provided a method of manufacturing a composite member in which a ceramic member is fitted into a metal member. In the method of manufacturing a composite member according to (1), the method of manufacturing a composite member includes the steps of: obtaining a composite member in which the ceramic member is press-fit into the metal member; And a heat treatment process.
According to the method of manufacturing a composite member of this aspect, it is possible to reduce the press-fit load at the time of press-fitting the ceramic member into the metal member, and to suppress damage to the ceramic member at the time of press-fitting. In addition, it becomes possible to decompose and remove a substance having an alkylene oxide group as a repeating unit attached to the surface of at least one of a metal member and a ceramic member by a heat treatment step, and bonding between the ceramic member and the metal member The power can be improved.

(3) According to still another aspect of the present invention, there is provided a method of manufacturing a glow plug, comprising: a ceramic heater; and a metal cylindrical member into which the ceramic heater is fitted. This manufacturing method manufactures a member in which the ceramic heater, which is the ceramic member, is fitted into the cylindrical member, which is the metal member, by the method for manufacturing a composite member according to (2) as the composite member. The heat treatment step is performed in a temperature range of 50 to 400 ° C .;
According to the glow plug manufacturing method of this aspect, it is possible to reduce the press-fit load at the time of press-fitting the ceramic heater into the cylindrical member, and to suppress the damage of the ceramic heater at the time of press-fitting. Further, a substance having an alkylene oxide group as a repeating unit attached to the surface of at least one of the cylindrical member and the ceramic heater is decomposed and removed by a heat treatment process to obtain the bonding strength between the ceramic heater and the cylindrical member. It is possible to improve. Furthermore, by performing the heat treatment step in a temperature range of 50 to 400 ° C., damage to the ceramic heater due to the heat treatment can be suppressed.

  The present invention can be realized in various forms other than the above, and, for example, a glow plug manufactured by using a method of manufacturing a composite member or a method of manufacturing a glow plug according to the present application. It is possible to realize in the form of a method or a bonding method of bonding a metal member and a ceramic member.

It is a cross-sectional schematic diagram showing the schematic structure of the glow plug as embodiment of this invention. It is a cross-sectional schematic diagram which expands and shows the front-end | tip part of a glow plug. It is a flowchart showing the manufacturing method of a glow plug. It is explanatory drawing showing step S100-S120 of FIG. It is an explanatory view showing the result of having measured press fit load about samples 1-8. It is explanatory drawing which shows the result of having measured the bonding force after heat processing.

A. Glow plug configuration:
FIG. 1 is a schematic cross-sectional view showing a schematic configuration of a glow plug 50 as an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing the tip of the glow plug 50 in an enlarged manner. The glow plug 50 of the present embodiment is attached to an internal combustion engine such as a diesel engine and functions as a heat source for assisting ignition at the start of the internal combustion engine. The glow plug 50 can also be used as another application, for example, in a diesel particulate filter (DPF) reactivating burner system.

  As shown in FIG. 1, the glow plug 50 includes, as main components, a metal shell 4, an outer cylinder 3, a heater element 1, a central shaft 6, a ring 14, and a metal lead portion 17. There is. In the present specification, the lower side in the direction of the axis O, which is the central axis of the glow plug 50 in FIG. 1, will be referred to as the “tip end side” of the glow plug 50 and the upper side as the “rear end side”.

  The metal shell 4 is a substantially cylindrical member extending along the axis O, and in the present embodiment, is formed of carbon steel. In the inside of the metal shell 4, an axial hole 41 penetrating the metal shell 4 along the axis O is formed. Further, a male screw portion 5 is formed on the outer peripheral surface of the metal shell 4. The glow plug 50 is fixed to the internal combustion engine by screwing the male screw portion 5 into a female screw formed in a plug mounting hole of a cylinder head (not shown) of the internal combustion engine.

  The outer cylinder 3 is a substantially cylindrical metal member extending along the axis O. In the inside of the outer cylinder 3, an axial hole 42 penetrating the outer cylinder 3 along the axis O is formed. The inner diameter of the axial hole 42 is formed to be equal to the outer diameter of the heater element 1 or slightly smaller than the outer diameter of the heater element 1, and the heater element 1 is fitted into the axial hole 42 by press fitting. The operation of pressing the heater element 1 into the outer cylinder 3 will be described in detail later. The rear end portion of the outer cylinder 3 is fitted into the front end portion of the axial hole 41 of the metal shell 4, and the front end portion of the metal shell 4 and the rear end portion of the outer cylinder 3 are welded.

  The heater element 1 is a ceramic heater, and is a substantially cylindrical member extending along the axis O. The heater element 1 is fitted in the axial hole 42 in the outer cylinder 3 at a mid portion thereof. In the heater element 1, a portion closer to the tip than the middle portion protrudes from the tip of the outer cylinder 3. A portion on the rear end side of the middle portion is accommodated in the axial hole 41 of the metal shell 4. The heater element 1 includes an insulating portion 13 and a conductive portion 11, and generates heat when power is supplied to the conductive portion 11.

  The insulating portion 13 is formed of an insulating ceramic. In the present embodiment, the insulating portion 13 is formed of silicon nitride. However, the insulating portion 13 is not limited to silicon nitride, and may be formed of, for example, another insulating ceramic such as alumina or sialon. The insulating portion 13 is a portion that forms the base of the heater element 1.

  The conductive portion 11 is embedded in the inside of the insulating portion 13 and has a U-shaped structure which extends in the direction of the axis O and is bent with the tip end at the top, and is made of conductive ceramic that generates heat by resistance. It is formed. In the present embodiment, the conductive portion 11 is formed of tungsten carbide (WC). However, the conductive portion 11 is not limited to tungsten carbide (WC), but may be formed of, for example, another conductive ceramic such as molybdenum disilicide or tungsten disilicide.

  One end of the U-shaped conductive portion 11 is exposed at the side surface of the heater element 1 to form a first potential side connection terminal (minus side connection terminal) 12b. Further, the other end of the conductive portion 11 is exposed on the side surface of the heater element 1, and the connection terminal (plus side connection terminal) 12a on the second potential side which has a higher potential than the one end described above. Form. The connection terminal 12b on the first potential side is exposed at the side surface of the heater element 1 at a position closer to the tip end than the connection terminal 12a on the second potential side. The first potential side connection terminal (negative side connection terminal) 12b of the conductive portion 11 is brought into contact with the inner wall of the shaft hole 42 by the heater element 1 being fitted into the shaft hole 42 in the outer cylinder 3, The part 11 and the outer cylinder 3 are electrically connected. In the present embodiment, the first potential side connection terminal 12 b and the second potential side connection terminal 12 a are formed of the same material as the other portions of the conductive portion 11, and a part of the conductive portion 11 is formed. It is formed as. However, the connection terminal 12 b on the first potential side and the connection terminal 12 a on the second potential side may be formed separately from other portions of the conductive portion 11.

  The central shaft 6 is a rod-like member having a shape extending along the axis O and formed of a conductive material. The center shaft 6 is disposed apart from the heater element 1 at a position on the rear end side of the heater element 1 in the axial hole 41 of the metal shell 4. The center shaft 6 can be formed of, for example, a metal material such as SUS430. The outer diameter of the central shaft 6 is smaller than the inner diameter of the axial hole 41 of the metal shell 4, and a gap is formed between the central shaft 6 and the inner wall of the axial hole 41 to electrically insulate both. .

  The ring 14 is a cylindrical member formed of a conductive material, and is assembled to the rear end portion of the heater element 1 inside the axial hole 41 of the metal shell 4. The rear end portion of the heater element 1 is fitted into the ring 14 so that the second potential side connection terminal (plus side connection terminal) 12a exposed on the side surface of the heater element 1 contacts the inner wall of the ring 14 and the conductive portion 11 and ring 14 are electrically connected. The ring 14 can be formed of, for example, a metal material such as SUS410 or SUS630.

  The metal lead portion 17 is formed of a bent metal piece extending in the direction of the axis O and is disposed in the axial hole 41 of the metal shell 4. The front end portion of the metal lead portion 17 is joined to the ring 14, and the rear end portion is joined to the center shaft 6. Thereby, the connection terminal (plus side connection terminal) 12 a on the second potential side of the conductive portion 11 of the heater element 1 is electrically connected to the center shaft 6 through the ring 14 and the metal lead portion 17. As a method of joining between the metal lead portion 17 and the ring 14 or the center shaft 6, for example, resistance welding or brazing can be adopted. Due to the bent shape of the metal lead portion 17, even if a heating / cooling cycle is added as the heater element 1 generates heat, the metal lead portion 17 expands the heater element 1 and the center shaft 6 at the bent portion. It can absorb / contract. As a result, it is possible to suppress the occurrence of problems such as contact failure, disconnection, and the like due to excessive stress being concentrated on the joint portion between the metal lead portion 17 and the ring 14 or the center shaft 6.

  As described above, inside the rear end portion of the metallic shell 4, the central shaft 6 for supplying power to the heater element 1 is disposed in an insulated state from the metallic shell 4. As shown in FIG. 1, in the present embodiment, the ceramic ring 31 is disposed between the rear end side outer peripheral surface of the center shaft 6 and the inner peripheral surface of the metal shell 4, and the glass filling layer 32 is formed on the rear side. The central shaft 6 is fixed. Further, the outer peripheral surface portion in contact with the glass filling layer 32 of the center shaft 6 is provided with unevenness by knurling or the like (in the figure, a shaded area). Furthermore, the rear end portion of the center shaft 6 extends to the rear of the metal shell 4, and the terminal metal fitting 7 is inserted into the extension portion via the insulating bush 8. The terminal fitting 7 is fixed to the outer peripheral surface of the middle shaft 6 in a conductive state by the caulking portion 9.

  In the glow plug 50 configured as described above, when power is supplied from the terminal fitting 7, power is transmitted to the conductive portion 11 through the center shaft 6, the metal lead portion 17, the ring 14 and the connection terminal 12a on the second potential side. The heater element 1 generates heat when supplied. At this time, the connection terminal 12b on the first potential side of the conductive portion 11 is grounded through the outer cylinder 3, the metal shell 4, and the cylinder head of the internal combustion engine.

B. How to make glow plugs:
FIG. 3 is a process chart showing a method of manufacturing the glow plug 50 of the first embodiment of the present invention. When manufacturing the glow plug 50, first, the front end of the heater element 1 is inserted from the rear end side to the front end side of the ring 14, and the heater element 1 is press-fit into the ring 14 (step S100). As a result, the positive side connection terminal 12 a of the conductive portion 11 contacts the inner wall of the ring 14, and the conductive portion 11 and the ring 14 are electrically connected.

  Thereafter, the heater element 1 is press-fit into the outer cylinder 3 from the rear end side of the shaft hole 42 in the outer cylinder 3, and the distal end of the heater element 1 is protruded from the front end of the outer cylinder 3 (step S110). Thereby, the negative side connection terminal 12b of the conductive portion 11 is in close contact with the inner wall surface of the shaft hole 42, and the conductive portion 11 and the outer cylinder 3 are electrically connected.

  Thereafter, the entire structure in which the heater element 1 is press-fit into the ring 14 and the outer cylinder 3 described above is heat-treated (step S120). The glow plug manufacturing method of the present embodiment is characterized by the above-described steps S100 to S120. That is, it is characterized in that in step S100 and step S110, a lubricant is used at the time of press-in, and in step S120, the lubricant is decomposed and removed by heat treatment. These press-in process and heat treatment process will be described in more detail later. In addition, the ring 14 and the outer cylinder 3 of this embodiment correspond to the "metal member" in the means to solve a subject, and the heater element 1 corresponds to a "ceramic member." Further, the member obtained by press-fitting the heater element 1 into the ring 14 in step S100 and the member obtained by press-fitting the heater element 1 into the outer cylinder 3 in step S110 are “composite” in the means for solving the problem. It corresponds to "member".

  Next, the rear end portion of the ring 14 and the front end portion of the metal lead portion 17 are joined, and the rear end portion of the metal lead portion 17 and the center shaft 6 are joined (step S130). Then, the middle shaft 6 is inserted into the axial hole 41 of the metal shell 4 (step S140), and the front end of the metal shell 4 is assembled to the rear end of the outer cylinder 3 (step S150). At this time, the outer cylinder 3 and the metal shell 4 may be joined, for example, by welding or brazing.

  Thereafter, the ceramic ring 31 and the glass filling layer 32 are disposed between the metal shell 4 and the rear end of the center shaft 6, and the terminal 7 is attached to the rear end of the center shaft 6 (step S160). Complete.

C. Injection and bonding process:
FIG. 4 is an explanatory view showing steps S100 to S120 of FIG. Steps (a) and (b) in FIG. 4 correspond to step S100 in FIG. 3 (hereinafter also referred to as a first press-in step), and steps (c) and (d) in FIG. Step S110 (hereinafter also referred to as a second press-in process). The step (d) of FIG. 4 corresponds to the heat treatment step of step S120 of FIG. Moreover, the (a) process and (c) process of FIG. 4 correspond to the "adhesion process" in the means to solve a subject.

  In the present embodiment, a lubricant is used in the first press-in process and the second press-in process. That is, in the first press-in process, a lubricant is applied to at least one of the surface of the heater element 1 and the inner wall surface of the ring 14 and in the region where the heater element 1 and the ring 14 contact in the first press-in process. Attach it. Also, in the second press-in step, at least one of the surface of the heater element 1 and the inner wall surface of the outer cylinder 3 (the surface of the shaft hole 42) A lubricant is attached to the area in contact with the cylinder 3. The lubricant is for reducing the friction at the time of press-in and for suppressing the press-in load. Therefore, when the lubricant is attached to the surface of the heater element 1, for example, the lubricant is attached from the tip of the heater element 1 to at least a position on the side surface of the heater element 1 where the ring 14 or the outer cylinder 3 is disposed. You should do it. FIG. 4 shows that the lubricant is applied to the entire side surface of the heater element 1 in any of the steps (a) and (c).

  Further, in this embodiment, the lubricant used in the press-in process is decomposed and removed by performing heat treatment after the first press-in process and after the second press-in process. As described above, the joining force between the heater element 1 and the ring 14 after the press-in and the joining force between the heater element and the outer cylinder 3 are enhanced by decomposing and removing the lubricant. In FIGS. 3 and 4, although the heat treatment process is performed after the first press-in process and the second press-in process, it is possible to perform the heat treatment process every time each press-in process is performed. It is also possible to press the heater element 1 into the ring 14 and the outer cylinder 3 and assemble the other components before performing the heat treatment step. However, if the heat treatment process is performed prior to the assembly of the other components, it is preferable because the bonding force between the ring 14 and the outer cylinder 3 and the heater element 1 can be secured when the other components are assembled. .

  In the present embodiment, a substance having a polyalkylene oxide group which is a long-chain hydrophilic group is used as the lubricant. More specifically, a substance having a repeating unit derived from an alkylene oxide (hereinafter, also referred to as an alkylene oxide group) and having a repeating number of alkylene oxide group of 20 or more is used. The polyalkylene oxide group may have one type of alkylene oxide group as a repeating unit alone, or may have a plurality of types of alkylene oxide groups as a repeating unit. When having a plurality of types of alkylene oxide groups as a repeating unit, the polyalkylene oxide group may be a block copolymer composed of two or more types of polyalkylene oxide groups, and is composed of two or more types of alkylene oxide groups It may be a random copolymer. In addition, the repeating number in the polyalkylene oxide group which a lubricating agent has can be calculated | required by the analysis using a mass spectrometry, for example.

  In the present embodiment, as described above, by using the lubricant having a polyalkylene oxide group in which the number of repeating alkylene oxide groups is 20 or more, the ring in the first press-in step and the second press-in step described above The friction between the outer cylinder 3 and the heater element 1 is reduced to reduce the press-fit load. By thus reducing the press-fit load, it is possible to suppress damage to the ceramic member caused by the press-fit load being too high. Generally, the viscosity of the substance having a polyalkylene oxide group is increased as the number of repetition of the alkylene oxide group is increased. Therefore, by increasing the viscosity of the lubricant by increasing the number of repeating alkylene oxide groups to 20 or more, the lubricant can be stably present as a film on the friction surface between the outer cylinder 3 and the heater element 1 at the time of press-fitting. It is considered that the effect of reducing the press-fit load is enhanced.

  Here, the viscosity of the lubricant generally increases as the molecular weight increases. Therefore, the viscosity of the lubricant increases as the carbon number of the alkylene oxide group used as the repeating unit in the lubricant increases and as the proportion of the alkylene oxide group having a large number of carbon atoms in the polyalkylene oxide group constituting the lubricant increases. The load reduction effect can be enhanced. In the present embodiment, even when the polyalkylene oxide group is formed of only repeating units derived from ethylene oxide which is an alkylene oxide having the smallest carbon number, the press-in load is reduced by setting the number of repetitions to 20 or more. The effect can be obtained sufficiently.

  In addition, when the viscosity of a lubricant is too high, the handling property of a lubricant will fall. Therefore, the number of repetitions of the alkylene oxide group in the polyalkylene oxide group constituting the lubricant is, for example, preferably 70 or less, more preferably 60 or less, and still more preferably 50 or less. In addition, the polyalkylene oxide group constituting the lubricant may be constituted, for example, by one or more alkylene oxide groups selected from alkylene oxide groups derived from ethylene oxide, propylene oxide, or butylene oxide. desirable.

  In this embodiment, since the lubricant having a hydrophilic group consisting of a polyalkylene oxide group is used as described above, the lubricant can be easily decomposed and removed by performing the heat treatment step after the press-in step. Therefore, the bonding force between the heater element 1 and the ring 14 and the bonding force between the heater element 1 and the outer cylinder 3 can be enhanced by performing the heat treatment step after the press-fitting step. It is considered that one of the reasons why the lubricant of the present embodiment can be easily thermally decomposed is that the bonding strength of the alkylene oxide bond (ether bond) possessed by the lubricant of the present embodiment is relatively weak. For example, conventionally known lubricants include waxes based on alkanes, but the alkylene oxide bond (ether bond) possessed by the lubricant according to the present embodiment has bonding strength compared to the intramolecular bond in the above-mentioned alkanes. weak. Therefore, it is considered that the lubricant of this embodiment can be easily decomposed and removed by the heat treatment process after the pressing process.

  The heat treatment step may be performed as long as the lubricant can be decomposed and removed to such an extent that a desired bonding strength can be obtained. As the temperature of the heat treatment step is increased, the lubricant (polyalkylene oxide group) is more easily decomposed and removed, and the bonding strength between the pressed-in ceramic member and the metal member can be enhanced.

  However, if the heat treatment temperature is too high, the ceramic member may be damaged during the heat treatment. For example, the heater element 1 of the present embodiment is composed of a plurality of portions made of different ceramic materials of the conductive portion 11 and the insulating portion 13. Therefore, when the heat treatment temperature is too high, the heater element 1 may be damaged (broken) due to the difference in thermal expansion coefficient between the conductive portion 11 and the insulating portion 13. From the viewpoint of suppressing such damage to the ceramic member, the temperature of the heat treatment step is preferably, for example, 500 ° C. or less, and more preferably 400 ° C. or less.

  In the present embodiment, on the surface of the heater element 1, the connection terminal 12b on the first potential side and the connection terminal 12a on the second potential side are exposed. If the temperature of the heat treatment is too high, the exposed portions of these connection terminals may be oxidized to increase the electrical resistance in the exposed portions. Therefore, in the method of manufacturing a glow plug including a ceramic heater as in the present embodiment, the temperature of the heat treatment step is preferably 350 ° C. or less, and more preferably 300 ° C. or less.

  The molecules constituting the lubricant according to the present embodiment may further have a hydrophobic group in addition to the polyalkylene oxide group which is a long-chain hydrophilic group. Even if the lubricant has a hydrophobic group portion in the molecule, it is mainly the above-mentioned hydrophilic group portion which is involved in the reduction of friction and press-in load between members, and this hydrophilic group portion is decomposed and removed by heat treatment For example, the bonding strength between the ceramic member and the metal member is enhanced. Therefore, the configuration of the hydrophobic group portion is not particularly limited. The hydrophobic group contained in the lubricant can be constituted, for example, by a higher alcohol, a fatty acid, an alkylphenol or the like. From the viewpoint of hardly affecting the performance of the entire lubricant, it is preferable that the hydrophobic group contained in the lubricant be, for example, an alkyl group which is a linear functional group.

  When the lubricant is constituted only by the hydrophilic group without having a hydrophobic group, the lubricant can be, for example, polyethylene glycol, polypropylene glycol or polyoxyethylene polyoxypropylene glycol.

  If the lubricant has a hydrophobic group with a hydrophilic group, the lubricant is a non-ionic surfactant. Examples of such a lubricant include polyoxyethylene alkyl ether, polyoxypropylene alkyl ether, polyoxyethylene polyoxypropylene alkyl ether, polyethylene glycol fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxypropylene glyceryl ether and the like. be able to.

  The lubricant may be a mixture containing a plurality of substances selected from among the substances having no hydrophobic group and the substances having a hydrophobic group described above.

  The lubricant may further contain an additive in addition to the above-described substance having a polyalkylene oxide group. As additives to be added to the lubricant, for example, organic substances such as alkanes, alcohols, ethers, esters and fatty acids can be used. Alternatively, at least one substance selected from lubricant additives of molybdenum (Mo), sulfur (S), and zinc (Zn) may be used. However, the additive used is preferably a substance that is decomposed in the heat treatment step.

  When a lubricant is attached to the surface of the ceramic member and / or the metal member in the step (a) or the step (c) of FIG. 4, for example, the lubricant described above is dissolved in a solvent such as water or an organic solvent It may be applied to the ceramic member and / or the metal member later. Alternatively, the lubricant may be attached to the ceramic member and / or the metal member after being heated, for example, to about 45 to 100 ° C. to soften or melt it.

  According to the glow plug manufacturing method of the present embodiment configured as described above, a material having an alkylene oxide group as a repeating unit, wherein the repeating number of the alkylene oxide group is 20 or more, a ceramic member, and It is attached to the surface of the metal member and / or pressed in. Thereby, a press-fit load can be reduced and damage to the ceramic member at the time of press-fit can be suppressed. In addition, by using the above-mentioned substance as a lubricant at the time of press-fitting, the lubricant can be easily decomposed and removed by performing the heat treatment step after the press-in, and the bonding strength between the ceramic member and the metal member can be enhanced. .

  In the case where the substance constituting the lubricant has a branched structure instead of a straight chain as in the polyoxypropylene glyceryl ether described above, in any branch of the branched structure, It is sufficient to satisfy the requirement that the number of repeating alkylene oxide groups is 20 or more. Thereby, the same effect of reducing the press-fit load and improving the bonding strength can be obtained.

  Further, in the present embodiment, although the lubricant having the polyalkylene oxide group is used in both the first press-in step and the second press-in step, the lubricant described in only one of the press-in steps is used. May be used.

D. Modification:
The present invention is not limited to the above embodiment, and can be carried out in various modes without departing from the scope of the invention. For example, the following modifications are possible.

Modification 1:
In the above-mentioned embodiment, although the lubricant described above having a polyalkylene oxide group was used for producing the glow plug, the lubricant may be applied to different applications. Even if it is other than the constituent member of the glow plug, the same effect as that of the embodiment can be obtained if it is applied to the case where the ceramic member is pressed into the metal member or the ceramic member is pressed into and bonded to the metal member.

・ Modified example 2:
When the press-in process is performed using the lubricant described in the embodiment, the shape of the metal member used for the press-in is, similarly to the ring 14 or the outer cylinder 3 of the embodiment, a tubular shape having a circular cross section. It may be a cylindrical shape having a C-shaped cross section in which a cut is partially formed in the axial direction. Further, instead of the metal member having the through hole, the ceramic member may be pressed into the recess by using a metal member having a recess extending in the insertion direction of the ceramic member.

  A substance having an alkylene oxide group as a repeating unit and using various substances having different numbers of repeating alkylene oxide groups as a lubricant, the heater element 1 is pressed into the outer cylinder 3 and the press-in load at the time of press-in is measured. As a lubricant, the effect of reducing the press-fit load was evaluated. Further, after the heater element 1 was press-fit into the outer cylinder 3, heat treatment was performed at various temperatures, and the bonding strength between the outer cylinder 3 and the heater element 1 after the heat treatment was evaluated.

<Sample used for press-fit load measurement>
In order to investigate the effect of press-in load reduction when used as a lubricant, eight lubricants of Samples 1 to 8 were used. Samples 1 to 7 have a hydrophilic group having an ethylene oxide group (EO group) as a repeating unit. The repeating number of ethylene oxide groups (hereinafter also referred to as the number of EO groups) in the hydrophilic group of each of these samples is 12 for sample 1, 20 for sample 2, 25 for sample 3, 30 for sample 4, and 41 for sample 5. , Sample 6 is 45 and sample 7 is 47.

  Samples 1 to 5 and Samples 7 and 8 each have a hydrophobic group consisting of an alkyl group. The carbon number (hereinafter also referred to as the number of C) of the alkyl group constituting the hydrophobic group of each sample is 12 for sample 1, 22 for sample 2, 12 for sample 3, 12 for sample 4, 22 for sample 5 and sample 7 is 12 and sample 8 is 22.

As mentioned above, Samples 1 to 5 and Sample 7 are polyoxyethylene alkyl ether which is a nonionic surfactant. Sample 6 is polyethylene glycol. Sample 8 is docosan (C ₂₂ H ₄₆ ), which is a kind of alkane.

<Press-fit load measurement>
The press-fit load when the heater element 1 was press-fit into the outer cylinder 3 using each sample as a lubricant was measured as follows. Each sample was heated or heated to 80 ° C. to soften or melt each material and used as a lubricant. Each lubricant was applied to the entire inner wall surface of the outer cylinder 3 (the surface of the axial hole 42) and the entire surface of the heater element 1. 30 outer cylinders 3 and 30 heater elements 1 were prepared for each sample, and the operation of pressing the heater element 1 into the outer cylinder 3 using each sample as a lubricant was performed 30 times for each sample (n = 30). The press-in operation was performed using an electropress at 25 ° C. ± 5 ° C. And the peak value (maximum load) of press-fit load was measured, the average value was calculated | required for every sample, and it was set as the press-fit load of each sample.

  FIG. 5 is an explanatory view showing the results of measuring the press-fit load of Samples 1 to 8 as described above. In FIG. 5, the value of the press-fit load of each sample is shown as a relative value when the value of the press-fit load in sample 1 is 100. As can be seen from FIG. 5, in the lubricant having an ethylene oxide group having the smallest molecular weight as an alkylene oxide group as a repeating unit, it was confirmed that the press-in load can be largely reduced by setting the number of repetitions to 20 or more. That is, Samples 2 to 7 in which the number of repeating ethylene oxide groups is 20 or more are Sample 1 in which the number of repeating ethylene oxide groups is less than 20, and Sample 8 in which the hydrophilic group having ethylene oxide groups as repeating units is not included. It showed a very small press-fit load as compared with. Thus, the effect that the press-in load can be reduced when the repeating number of the ethylene oxide group is 20 or more is the effect obtained regardless of whether the lubricant has a hydrophobic group or the type of the hydrophobic group. The That is, the sample 6 which does not have a hydrophobic group showed the same press-in load reduction effect as the samples 2-5 and the sample 7 which have a hydrophobic group with a hydrophilic group.

<Measurement of bonding force>
After the sample 4 described above was used as a lubricant and the heater element 1 was pressed into the outer cylinder 3, heat treatment was performed at various temperatures, and the bonding strength between the outer cylinder 3 and the heater element 1 after heat treatment was measured. The heat treatment was performed under the temperature conditions of 50 ° C., 100 ° C., 200 ° C., 300 ° C., 400 ° C. and 600 ° C., and the bonding strength after the heat treatment was compared with that without the heat treatment. Thirty outer cylinders 3 and 30 heater elements 1 were prepared for each heat treatment condition (n = 30), and sample 4 was used as a lubricant to press-fit heater element 1 into outer cylinder 3. The subsequent heat treatment was performed for 90 minutes at each temperature. When measuring the bonding force, the heater element 1 was pushed in the opposite direction to the press-in direction using an autograph while fixing the outer cylinder 3. Then, while the load at the time of pushing the heater element 1 was gradually increased, the load when the heater element 1 started to move with respect to the outer cylinder 3 was measured. The average value of the load in 30 samples prepared for each heat treatment condition was taken as the bonding strength under each heat treatment condition.

  FIG. 6 is an explanatory view showing the results of measurement of bonding strength with respect to sample 4 under different heat treatment conditions as described above. In FIG. 6, the value of bonding strength is shown for each heat processing temperature as a relative value when the bonding strength without heat treatment is 100. As can be seen from FIG. 6, it was confirmed that the bonding strength between the outer cylinder 3 and the heater element 1 can be greatly improved by heat treatment at 50 ° C. or higher after press-fitting. Moreover, it has been confirmed that the effect of enhancing the bonding strength by the heat treatment increases as the heat treatment temperature increases. When the heat treatment temperature was 600 ° C., the heater element 1 was broken at the time of the heat treatment, and the bonding strength could not be measured.

  The present invention is not limited to the above-described embodiments, examples, and modifications, and can be implemented with various configurations without departing from the scope of the invention. For example, technical features in the embodiments, examples, and modifications corresponding to the technical features in the respective forms described in the section of the summary of the invention can be provided to solve some or all of the problems described above, or In order to achieve part or all of the above-described effects, replacements or combinations can be made as appropriate. Also, if the technical features are not described as essential in the present specification, they can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 1 ... Heater element 3 ... Outer cylinder 4 ... Main metal fitting 5 ... Male screw part 6 ... Medium axis 7 ... Terminal metal fitting 8 ... Insulation bush 9 ... Crimping part 11 ... Conduction part 12a ... Positive side connection terminal 12b ... Negative side connection terminal 13 ... Insulating part 14 ... ring 17 ... metal lead part 31 ... ceramic ring 32 ... glass filling layer 41 ... axial hole 42 ... axial hole 50 ... glow plug

Claims (4)

A method of manufacturing a composite member in which a ceramic member is fitted into a metal member,
A press-fitting step of pressing the ceramic member into the metal member;
Prior to the press-fitting step, a material having an alkylene oxide group as a repeating unit in at least one of the surfaces of the metal member and the ceramic member and in the region where the metal member and the ceramic member are in contact in the press-fitting step An adhesion step of attaching a substance having a repeating number of alkylene oxide groups of 20 or more;
A heat treatment step of heat treating a composite member obtained by pressing the ceramic member into the metal member after the press-fitting step;
A method of manufacturing a composite member, comprising: A method of manufacturing a glow plug, comprising: a ceramic heater; and a metal tubular member into which the ceramic heater is fitted,
The method of manufacturing a composite member according to claim 1 , comprising the step of manufacturing, as the composite member, a member in which the ceramic heater as the ceramic member is fitted to the cylindrical member as the metal member.
The heat treatment step is performed in a temperature range of 50 to 400 ° C. A method for producing a glow plug. A glow plug comprising: a ceramic heater; and a metal tubular member into which the ceramic heater is fitted,
A glow plug obtained by joining the cylindrical member, which is the metal member, and the ceramic heater, which is the ceramic member, by the method of manufacturing a composite member according to claim 1 . A glow plug manufactured by the method of manufacturing a glow plug according to claim 2 .

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