JP6174971B2 - Glow plug manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a glow plug.

  Conventionally, as a method of manufacturing a glow plug, a ceramic heating element is fixed to a metal shell by inserting a rod-shaped heat generating element into a metal outer cylinder and butt-welding the outer cylinder to a plated metal shell. It is known to do.

  When the metal shell and the outer cylinder are butt welded, if the plating material of the metal shell is interposed in the welded portion (weld bead), the plating material is vaporized during welding, and pores (pores) are formed in the welded portion. In some cases, welding defects such as a decrease in joint strength, a decrease in corrosion resistance, and a deterioration in appearance may occur in the welded portion.

  As a technique for suppressing poor welding caused by a plating material, for example, a technique described in Patent Document 1 below is known. Patent Document 1 describes that a plating layer formed on a butt surface of a metal shell is peeled off by polishing prior to butt welding.

JP 2008-8607 A JP 2011-27303 A

  However, in the polishing and peeling of the plating layer described in Patent Document 1, not only the plating layer but also the carbon steel base material is polished due to excessive polishing or unevenness of polishing, resulting in a lack of thickness in the metal shell. There was a case. Damage to the metal shell, such as a lack of thickness, causes a positional shift of the heat generating element fixed to the metal shell, resulting in a problem that the yield rate of the glow plug product deteriorates.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms.

(1) According to an aspect of the present invention, a method for manufacturing a glow plug is provided. The method for manufacturing a glow plug is a method for manufacturing a glow plug including a first metal member and a second metal member joined to the first metal member, and (a) preparing the plated first metal member. And (b) irradiating the annular end surface of the plated first metal member with a laser to remove the plating layer formed on the annular end surface; and (c) removing the plating layer. And a welding step of welding the second metal member to the annular end surface. In the step (b), the laser irradiated by being relatively moved in the circumferential direction of the annular end surface is irradiated from the outer periphery of the annular end surface to the inner periphery of the annular end surface toward the inner periphery in the radial direction or The irradiation process of continuously irradiating from the inner periphery of the annular end surface toward the outer periphery of the annular end surface is performed N times (N is an integer of 2 or more). The first irradiation step of the step (b) is a step of irradiating each laser so that the surface of the annular end face is not exposed.
According to the manufacturing method of this embodiment, the laser does not reach the surface of the annular end face in the first irradiation step. Therefore, it is possible to prevent the annular end face from being damaged by the laser irradiation in the first irradiation step.

(2) In the method for manufacturing a glow plug according to the above aspect, the energy of all lasers applied to the annular end face in the Nth irradiation step of the step (b) is (N-1) th irradiation step. The energy may be smaller than the energy of the entire laser irradiated on the annular end face.
According to the manufacturing method of this aspect, since the energy of all lasers in the Nth irradiation process for exposing the annular end surface is small, the annular end surface exposed in the Nth irradiation process is damaged by being irradiated with the laser. Can be suppressed.

(3) In the method for manufacturing a glow plug according to the above aspect, the first metal member is a member formed with iron (Fe) as a main component; and the plating layer is formed with zinc (Zn) as a main component. It may be a layer.
Since the melting point of zinc is lower than the melting point of iron, according to the manufacturing method of this embodiment, it is possible to satisfactorily remove the plating layer with a laser while suppressing melting of the first metal member due to laser irradiation.

(4) In the method for manufacturing a glow plug according to the above aspect, the first metal member is a metal shell in which a male screw for attaching the glow plug to an internal combustion engine is formed on an outer peripheral surface; In addition, an outer cylinder in which the heating element is inserted and the heating element is fixed to the metal shell may be used.
According to the manufacturing method of this embodiment, the metal shell and the outer cylinder can be firmly welded.

  The present invention can also be realized in various forms other than the manufacturing method. For example, it can be realized in the form of a glow plug manufactured by the manufacturing method, a glow plug manufacturing apparatus, or the like.

It is explanatory drawing which shows the partial cross section of the glow plug attached to the internal combustion engine. It is explanatory drawing which expands and shows the cross section of the front-end | tip part of a metal shell. It is process drawing which shows the manufacturing process of a glow plug. It is explanatory drawing which shows typically a mode that a laser beam is irradiated to the cyclic | annular end surface of a metal shell, and a plating layer is removed. It is explanatory drawing which shows an example of the locus | trajectory which moves a laser relatively with respect to the cyclic | annular end surface of a metal shell. It is explanatory drawing which expands and shows the surface of the plating layer in the 1st irradiation process of a laser. It is explanatory drawing which shows the mode of the process of welding a metal shell and an outer cylinder.

Next, embodiments of the present invention will be described in the following order based on the embodiments.
A. Embodiment:
A1. Glow plug configuration:
A2. Glow plug manufacturing process:
B. Variations:

A. Embodiment:
A1. Glow plug configuration:
FIG. 1 is an explanatory view showing a partial cross section of a glow plug 10 attached to the internal combustion engine 5. The glow plug 10 is attached to the internal combustion engine 5 such as a diesel engine, and functions as a heat source that assists ignition when the internal combustion engine 5 is started. The glow plug 10 includes a power supply terminal 100, a middle shaft 200, an insulating member 300, an O (O) ring 400, a metal shell 500, a current-carrying ring 600, an outer cylinder 700, and a ceramic heating element 800. Yes. These members constituting the glow plug 10 are assembled along the central axis SC of the glow plug 10. In the present specification, the ceramic heating element 800 side of the glow plug 10 is referred to as “front end side”, and the power supply terminal 100 side is referred to as “rear end side”.

  The metal shell 500 is a cylindrical first metal member formed of a metal material. The metal shell 500 encloses the middle shaft 200, holds the ceramic heating element 800 via the outer cylinder 700 on the front end side, and holds the middle shaft 200 via the insulating member 300 on the rear end side. In the present embodiment, the base material of the metal shell 500 is formed of a metal material mainly composed of iron (Fe), and specifically corresponds to “S40C” defined in the Japanese Industrial Standard (JIS). It is made of carbon steel (SC material) for machine structure. However, the base material of the metal shell 500 is not limited to this, and any metal material having a composition that can withstand the use environment of the glow plug may be used. In the present embodiment, the surface of the base material of the metallic shell 500 is plated. Details of the plating material and the like will be described later.

  The metal shell 500 includes a shaft hole 510, a tool engaging portion 520, a first tubular portion 530, a male screw portion 540, a step portion 550, and a second tubular portion 560. In the present embodiment, the metal shell 500 is formed with a tool engaging portion 520, a first cylindrical portion 530, a step portion 550, and a second cylindrical portion 560 in this order from the rear end side, and the male screw portion 540. Is formed in the first tubular portion 530. In the present embodiment, the tool engagement portion 520 is formed on the rear end side with respect to the male screw portion 540. However, in other embodiments, the tool engaging portion 520 may be formed on the tip side of the male screw portion 540.

  The shaft hole 510 of the metal shell 500 is a through hole formed substantially along the central axis SC and has a larger diameter than the middle shaft 200. Inside the shaft hole 510, the middle shaft 200 is positioned, and a gap is formed between the shaft hole 510 and the middle shaft 200 to electrically insulate them. The tool engaging portion 520 of the metal shell 500 is a portion that fits into a tool (not shown) used for attaching and removing the glow plug 10 to the internal combustion engine 5.

  The 1st cylindrical part 530 of the metal shell 500 is a site | part in which the external thread part 540 was formed in the outer periphery. The male threaded portion 540 of the metal shell 500 is formed from the front end side to the rear end side of the first cylindrical portion 530 and is a portion that fits into the female screw formed in the internal combustion engine 5. The step portion 550 of the metal shell 500 is a portion that connects the first tubular portion 530 and the second tubular portion 560. The second cylindrical portion 560 of the metal shell 500 is a portion having an outer diameter smaller than that of the first cylindrical portion 530, and the ceramic heating element 800 is fixed to the distal end side via the outer cylinder 700. .

  The outer cylinder 700 is a cylindrical second metal member formed of a metal material. The outer cylinder 700 is butt welded to the distal end side of the second cylindrical portion 560 of the metal shell 500, and fixes the ceramic heating element 800 to the metal shell 500. In the present embodiment, the material of the outer cylinder 700 is stainless steel equivalent to “SUS430” defined in JIS. However, the material of the outer cylinder 700 is not limited to this, and any metal material that can withstand the usage environment of the glow plug may be used. In the present embodiment, the outer cylinder 700 is in an unplated state where plating is not applied.

  The outer cylinder 700 includes a shaft hole 710, a third cylindrical part 730, a stepped part 750, and a fourth cylindrical part 760. In the outer cylinder 700, a third cylindrical portion 730, a stepped portion 750, and a fourth cylindrical portion 760 are formed in order from the rear end side.

  The shaft hole 710 of the outer cylinder 700 is a through hole formed substantially along the central axis SC, and has a diameter that fits the ceramic heating element 800. The third cylindrical portion 730 of the outer cylinder 700 is a portion having an outer diameter that is substantially the same size as the second cylindrical portion 560 of the metal shell 500. The step portion 750 of the outer cylinder 700 is a portion that connects between the third cylindrical portion 730 and the fourth cylindrical portion 760. The fourth cylindrical part 760 of the outer cylinder 700 is a part having an outer diameter smaller than that of the third cylindrical part 730.

  The ceramic heating element 800 includes a ceramic base 810 formed of an insulating ceramic, and a heating element 820 embedded in the ceramic base 810 and generating heat when energized. In the present embodiment, the ceramic heating element 800 is formed in a cylindrical shape. In the present embodiment, the heating element 820 is a resistor formed of a conductive ceramic. However, in other embodiments, the heating element 820 may be a metal heating coil. Further, in the present embodiment, the heating element 820 includes a substantially U-shaped heating part bent with the tip end as a vertex inside the ceramic base 810 and a pair of leads connected to the ends of the heating part. Part. One lead portion is electrically connected to the energization ring 600, and the other lead portion is electrically connected to the outer cylinder 700.

  The power supply terminal 100 is a member formed of a conductive material, and is a terminal for receiving power supply from the outside of the glow plug 10. Since the power feeding terminal 100 is electrically connected to the ceramic heating element 800, the ceramic heating element 800 can receive power feeding from the outside via the power feeding terminal 100.

  The middle shaft 200 is a cylindrical member formed of a conductive material, and is assembled on the central axis SC in a state of being inserted into the shaft hole 510 of the metal shell 500, and the power supply terminal 100 and the ceramic heating element 800 are connected to each other. Electrical connection between them. In the present embodiment, power supply from the outside to the ceramic heating element 800 is performed via the power supply terminal 100. However, in other embodiments, the power feeding terminal 100 and the middle shaft 200 may be formed integrally, and power feeding from the outside may be performed directly on the middle shaft.

  The insulating member 300 is a cylindrical member formed of an insulating material, and a gap that electrically insulates the middle shaft 200 and the metallic shell 500 by positioning the middle shaft 200 inside the metallic shell 500. Form. In the present embodiment, the insulating member 300 positions the middle shaft 200 and is electrically insulated from each other by being interposed between the power supply terminal 100 and the metal shell 500.

  The O-ring 400 is an annular member made of an insulating elastic material, and seals the inside of the metallic shell 500 by being in close contact with the middle shaft 200, the insulating member 300, and the metallic shell 500.

  The energization ring 600 is a cylindrical member formed of a conductive material, and is assembled between the middle shaft 200 and the ceramic heating element 800 inside the shaft hole 510 of the metal shell 500. The ceramic heating element 800 is electrically connected.

  FIG. 2 is an explanatory view showing, in an enlarged manner, a cross section of the tip portion of the metal shell 500. As shown in FIG. 2, an annular end surface 564 is formed at the tip of the metal shell 500. A chamfered portion 566 is formed by cutting between the annular end surface 564 of the metal shell 500 and the outer peripheral side surface 562. A chamfered portion 567 is formed by cutting between the annular end surface 564 of the metal shell 500 and the shaft hole 510. A plating layer 505 is formed on the surface of the metal shell 500.

  As will be described later, in the manufacturing process of the glow plug 10, after the plating layer 505 is removed by irradiating the annular end surface 564 of the metallic shell 500 with the laser, the annular end surface 564 of the metallic shell 500 is attached to the rear end of the outer cylinder 700. Butt welding is performed with the ends in contact. The chamfered portions 566 and 567 of the metal shell 500 may be irradiated with laser to remove the plating layer 505 formed on the surfaces of the chamfered portions 566 and 567.

A2. Glow plug manufacturing process:
FIG. 3 is a process diagram showing the manufacturing process of the glow plug 10. In step S100, various members such as a metal shell 500 having a plating layer 505 formed on the surface and an outer cylinder 700 are prepared. In this embodiment, the plating layer 505 of the metal shell 500 is formed of a plating material containing zinc (Zn) as a main component, and specifically, a zinc-nickel alloy containing zinc (Zn) and nickel (Ni). Is formed. However, the plating layer 505 of the metal shell 500 is not limited to zinc-nickel alloy, and may be formed of a plating material having a composition that can withstand the use environment of the glow plug. The plating layer 505 of the metal shell 500 is preferably formed of a plating material having a melting point lower than that of the metal shell 500. This is because, if the melting point of the plating material is smaller than the melting point of the metal shell 500, only the plating layer 505 can be satisfactorily removed by the laser while suppressing the melting of the metal shell 500. For example, the plating layer 505 of the metal shell 500 is preferably formed of a plating material containing at least one of zinc (Zn), copper (Cu), and tin (Sn). In another embodiment, a chromate layer may be further formed on the plating layer 505 of the metal shell 500.

  In step S110, the plated layer 505 is removed by irradiating the annular end surface 564 of the metal shell 500 on which the plated layer 505 is formed with a laser. Details of the process of removing the plating layer 505 will be described later.

  In step S120, the metal shell 500 and the outer cylinder 700 are welded. In this embodiment, the outer cylinder 700 is welded to the annular end surface 564 of the metal shell 500 from which the plating layer 505 has been removed. Details of the process of welding the metal shell 500 and the outer cylinder 700 will be described later.

  In step S <b> 130, the remaining members are assembled to the metal shell 500 to complete the glow plug 10.

  FIG. 4 is an explanatory view schematically showing how the plated layer 505 is removed by irradiating the annular end surface 564 of the metal shell 500 with a laser. As shown in FIG. 4, in the step of removing the plating layer 505 (S <b> 110 in FIG. 3), the annular end surface 564 of the metal shell 500 is irradiated with the laser emitted from the laser irradiation device 90, thereby The plating layer 505 formed on 564 is removed. The energy of the laser emitted from the laser irradiation device 90 increases as it approaches the focal point FS. In this embodiment, the laser focus FS is adjusted so as to coincide with the surface of the plating layer 505.

  FIG. 5 is an explanatory diagram showing an example of a locus for moving the laser relative to the annular end surface 564 of the metal shell 500. The spot diameter at the laser focal point FS is smaller than the annular end surface 564 of the metal shell 500. Therefore, in this embodiment, the plating layer 505 is applied from the entire area of the annular end surface 564 of the metallic shell 500 by irradiating the annular end surface 564 of the metallic shell 500 while moving the laser relatively along the circular locus. Remove.

  Specifically, laser irradiation is started from the start point P1 of the annular end surface 564 of the metal shell 500, the laser is irradiated along the circular locus Tc1, and then along the circular locus Tc2 inside the circular locus Tc1. Irradiate laser continuously. The laser is continuously irradiated along the circular locus even to the region inside the circular locus Tc2. By irradiating the laser continuously along a plurality of circular trajectories in this way, the laser is irradiated to the entire area of the annular end surface 564 of the metal shell 500. In this embodiment, the interval between the circular trajectories is adjusted to a distance smaller than the spot diameter of the laser irradiated on the plating layer 505, so that there is no gap with respect to the entire area of the annular end surface 564 of the metal shell 500. Laser is irradiated, and the plating layer 505 is removed from the entire area of the annular end surface 564 of the metal shell 500.

  In FIG. 5, two circular trajectories are drawn, but in actuality, the number of circular trajectories for laser irradiation is about 60. Further, when removing the plating layer 505 of the chamfered portions 566 and 567 of the metal shell 500, the laser irradiation is started from the position of the chamfered portion 566, the laser is irradiated along the circular locus, and the position of the chamfered portion 567 is reached. The laser may be irradiated along the circular locus.

  In the present embodiment, the irradiation process of continuously irradiating a laser from the outer periphery to the inner periphery of the annular end surface 564 of the metal shell 500 along a plurality of circular trajectories (for example, about 60) is performed three times. By doing so, the plating layer 505 is removed from the annular end surface 564 of the metal shell 500.

  FIG. 6 is an explanatory view showing, in an enlarged manner, the surface of the plating layer 505 in the first laser irradiation step. FIG. 6 shows a plating material removed by laser irradiation, an evaporated plating material, and a bumped plating material. As shown in FIG. 6, in this embodiment, in the first irradiation process, the laser is irradiated so that the surface of the annular end surface 564 of the metal shell 500 is not exposed. In this way, since the laser does not reach the surface of the annular end surface 564 of the metal shell 500 in the first irradiation process, the annular end surface 564 of the metal shell 500 directly irradiates the laser in the first irradiation process. I do not receive it. For example, in the first irradiation step, if the energy density of the laser irradiated to the plating layer 505 is increased to the extent that the surface of the annular end surface 564 of the metal shell 500 is not exposed, the time required to remove the plating layer 505 is reduced. While being able to shorten, it can suppress that the cyclic | annular end surface 564 of the metal shell 500 receives the irradiation of a high energy density laser, and is damaged.

  Furthermore, in the present embodiment, the energy of the entire laser irradiated on the annular end surface 564 of the metal shell 500 in the third (last) irradiation step is irradiated on the annular end surface 564 of the metal shell 500 in the second irradiation step. Be less than the energy of the whole laser. The reason for this will be described. In at least the third (last) irradiation step, the laser reaches the annular end surface 564 of the metallic shell 500 and the base material of the metallic shell 500 is exposed, so that the annular end surface 564 of the metallic shell 500 is damaged from the laser. Easy to receive. Therefore, as in the present embodiment, if the energy of the entire laser irradiated to the annular end surface 564 of the metal shell 500 is reduced in the third (last) irradiation step, the annular end surface 564 of the metal shell 500 is damaged. Can be suppressed.

  In each laser irradiation step, the adjustment of the depth at which the plating layer 505 is removed, that is, the adjustment of the energy of all the laser beams irradiated to the annular end surface 564 of the metal shell 500, This can be done by adjusting the distance from the focal point of the plating layer 505, the relative speed between the laser and the plating layer 505, the number of circular trajectories, the overlapping width of adjacent circular trajectories, and the like. For example, in the present embodiment, the laser moving speed in the third (last) irradiation process is adjusted to about 1.5 to 3 times the laser moving speed in the first and second irradiation processes.

  FIG. 7 is an explanatory view showing a state of the process of welding the metal shell 500 and the outer cylinder 700 (S130 in FIG. 3). First, as shown in FIG. 7A, the metal shell 500 and the outer cylinder 700 are brought into contact with each other. Specifically, the annular end surface 564 of the metal shell 500 and the annular end surface 734 of the outer cylinder 700 are brought into contact with each other. In the present embodiment, prior to the step of bringing the metal shell 500 and the outer cylinder 700 into contact with each other, the ceramic heating element 800 is inserted into the shaft hole 710 of the outer cylinder 700, and the ceramic heating element. A central shaft 200 is connected to 800 through an energization ring 600.

  Next, as shown in FIG. 7B, the boundary between the annular end surface 564 of the metal shell 500 and the annular end surface 734 of the outer cylinder 700 is welded from the outer peripheral side. The arrow in FIG. 7B indicates a welding site. In the present embodiment, the metal shell 500 and the outer cylinder 700 are welded by laser welding. In this embodiment, the laser used for welding is a YAG laser. However, in other embodiments, the laser used for welding may be another laser such as a carbon dioxide gas laser. Further, in other embodiments, the metal shell 500 and the outer cylinder 700 may be welded by other welding methods such as electron beam welding or arc welding.

  As shown in FIG. 7C, when the welding is completed, the metallic shell 500 and the outer cylinder 700 are formed on the outer peripheral side of the boundary between the annular end surface 564 of the metallic shell 500 and the annular end surface 734 of the outer cylinder 700. The molten weld bead Pw is formed, and the metal shell 500 and the outer cylinder 700 are connected.

  Thus, according to the present embodiment, the plating layer 505 can be favorably removed while suppressing damage to the annular end surface 564 of the metal shell 500.

B. Variations:
The present invention is not limited to the above-described embodiments and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

・ Modification 1:
In the above-described embodiment, the laser irradiated by being relatively moved in the circumferential direction of the annular end surface 564 of the metal shell 500 is irradiated from the outer periphery of the annular end surface 564 to the inner periphery of the annular end surface 564 inward in the radial direction. The irradiation process of continuous irradiation is performed three times. On the other hand, in the modified example, the laser that is irradiated while being relatively moved in the circumferential direction of the annular end surface 564 of the metal shell 500 is irradiated from the inner periphery of the annular end surface 564 toward the radially outer side. You may perform the irradiation process irradiated continuously to the outer periphery of 564 3 times. Further, in a plurality of irradiation steps, the locus of the laser that moves from the inner periphery of the annular end surface 564 of the metal shell 500 to the outer periphery of the annular end surface 564 toward the radially outer side, and the inner surface of the annular end surface 564 of the metal shell 500 The locus of the laser that moves from the circumference to the outer circumference of the annular end face 564 toward the radially outer side may be mixed. The laser irradiation process may be performed twice or four times or more. Further, the laser may be fixed and the metallic shell 500 side may be moved. Further, the laser trajectory is not limited to the circular trajectory, and may be a trajectory along the annular end surface 564 of the metal shell 500.

Modification 2
In the above-described embodiment, the case where the plating layer 505 is removed from the metal shell 500 when the metal shell 500 and the outer cylinder 700 are butt-welded has been described. However, the present invention relates other metal members in the glow plug 10 to each other. In the case of welding, the present invention may be applied to the case where the plating layer is removed from the butt surface of at least one metal member. For example, the present invention may be applied to the case where the plating layer 505 is removed from the butt surface of the metal shell 500 when a metal terminal cover (not shown) is welded to the rear end side of the metal shell 500. When the metal shell 500 is composed of two members, the present invention may be applied to the case where the plating layer 505 is removed from the abutting surfaces of the two metal shells 500.

  The present invention can also be applied to the case where the plating layer is removed from the butt surface of the outer cylinder 700 when the outer cylinder 700 is formed with a plating layer.

・ Modification 3:
The present invention can also be applied to the manufacture of glow plugs having various structures. For example, the present invention can also be applied when manufacturing a glow plug incorporating various sensors such as a temperature sensor and a pressure sensor.

  The present invention is not limited to the above-described embodiments, embodiments, and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments, embodiments, and modifications corresponding to the technical features in each embodiment described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the above effects, replacement or combination can be performed as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 5 ... Internal combustion engine 10 ... Glow plug 90 ... Laser irradiation apparatus 100 ... Feeding terminal 200 ... Middle shaft 300 ... Insulating member 400 ... O-ring 500 ... Main metal fitting 505 ... Plating layer 510 ... Shaft hole 520 ... Tool engaging part 530 ... 1st Cylindrical part 540 ... male screw part 550 ... step part 560 ... second cylindrical part 562 ... outer peripheral side surface 564 ... annular end face 566 ... chamfered part 567 ... chamfered part 600 ... energizing ring 700 ... outer cylinder 710 ... shaft hole 730 ... third cylindrical part 734 ... annular end face 736 ... chamfered part 750 ... stepped part 760 ... fourth cylindrical part 800 ... ceramic heating element 810 ... ceramic substrate 820 ... heating element SC ... center axis Pw ... welded part P1 ... start Point Tc1 ... Circle locus Tc2 ... Circle locus FS ... Focus

Claims (4)

A method for manufacturing a glow plug comprising a first metal member and a second metal member joined to the first metal member,
(A) preparing the plated first metal member;
(B) irradiating the annular end surface of the plated first metal member with a laser to remove the plating layer formed on the annular end surface;
(C) a welding step of welding the second metal member to the annular end surface from which the plating layer has been removed;
In the step (b), the laser irradiated by being relatively moved in the circumferential direction of the annular end surface is irradiated from the outer periphery of the annular end surface to the inner periphery of the annular end surface toward the inner periphery in the radial direction or While performing the irradiation process of continuously irradiating from the inner periphery of the annular end surface to the outer periphery of the annular end surface radially outward, N is an integer of 2 or more,
The method of manufacturing a glow plug, wherein the first irradiation step of the step (b) is a step of irradiating each laser so that the surface of the annular end face is not exposed. A method of manufacturing a glow plug according to claim 1,
The energy of the entire laser irradiated on the annular end surface in the N-th irradiation step of the step (b) is the energy of the entire laser irradiated on the annular end surface in the (N-1) -th irradiation step. A method for manufacturing a glow plug, characterized by being smaller than A method of manufacturing a glow plug according to claim 1 or claim 2,
The first metal member is a member formed mainly of iron (Fe),
The method for manufacturing a glow plug, wherein the plating layer is a layer formed of zinc (Zn) as a main component. A method of manufacturing a glow plug according to any one of claims 1 to 3,
The first metal member is a metal shell in which a male screw for attaching the glow plug to the internal combustion engine is formed on the outer peripheral surface,
The method for manufacturing a glow plug, wherein the second metal member is an outer cylinder in which a heat generating element is inserted and the heat generating element is fixed to the metal shell.

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