JP2017195127A - Manufacturing method of spark plug - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a spark plug, which can stably manufactured an electrode with excellent durability.SOLUTION: An assembly structured by overlapping an electrode base material with a chip is formed, and is rotated at a rotation axis with a center axis. A laser beam is emitted from an emission port of a processing head of a continuous oscillation laser arranged on the center axis toward the assembly, and a reflection light of the laser beam is reflected by a rotation mirror arranged between the processing head and the assembly. The rotation mirror is rotated so as to be rotated inversely with the assembly around the center axis, and the reflection light is reflected by a reflection mirror and is irradiated to a processing point of the assembly. Since a relative rotation number of the rotation mirror to the assembly is 1000 or more in any one minute, a continuous melting part can be formed to a circumference of the assembly while suppressing the generation of a spatter or the like. Since the size of the melting part is prevented from being unevenly formed, the size of the melting part in an axial direction can be reduced.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for manufacturing a spark plug, and more particularly to a method for manufacturing a spark plug that can stably manufacture an electrode having excellent durability.

  A spark plug including a center electrode and a ground electrode in which an electrode base material and a tip containing a noble metal are joined by laser welding is known (for example, Patent Document 1). In Patent Document 1, welding of the electrode base material and the tip is performed by forming an assembly in which the electrode base material and the tip are overlapped, and then irradiating the entire circumference of the assembly with laser beams simultaneously from multiple points. .

JP 2003-68421 A

  However, in the conventional technique described above, the laser beam is irradiated from multiple points on the entire periphery of the assembly, so that a melted portion in which the chip and the electrode base material are melted is formed in a spot shape in the portion irradiated with the laser beam. The Since the size of the melted portion becomes non-uniform in the circumferential direction of the assembly, the dimension from the tip of the chip to the melted portion is reduced at a portion where the melted portion is large. Since the melted portion is inferior in spark resistance compared to the tip, the durability decreases when the dimension from the tip of the tip to the melted portion decreases. There is a problem that it is significantly reduced).

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a spark plug manufacturing method capable of stably manufacturing an electrode having excellent durability.

Means for Solving the Problems and Effects of the Invention

  In order to achieve this object, according to the spark plug manufacturing method of the first aspect, at least one of the center electrode and the ground electrode is joined by laser welding to the electrode base material and the tip containing the noble metal. An assembly in which the electrode base material and the chip are overlapped is formed by the assembly process, and the assembly is rotated about the center axis of the chip as the rotation axis by the rotation process.

  By the irradiation process, laser light is emitted from the exit of the processing head of the continuous wave laser disposed on the central axis toward the assembly, and the laser light is emitted by a rotating mirror disposed between the processing head and the assembly. Reflects reflected light. The rotating mirror is rotated around the central axis so as to be reverse to the assembly, and the reflected light is reflected by one or more reflecting mirrors to irradiate the processing point of the assembly. Since the relative rotational speed of the rotary mirror with respect to the assembly is 1000 rotations or more per minute, a continuous melting portion can be formed around the assembly while suppressing the occurrence of spatter and the like. Since the size of the melted portion can be prevented from becoming non-uniform and the size of the melted portion in the axial direction can be reduced, there is an effect that an electrode having excellent durability can be stably manufactured.

  According to the spark plug manufacturing method of the second aspect, the reflecting mirror rotates integrally with the rotating mirror. Therefore, even if the angle of the rotating mirror and the reflecting mirror with respect to the central axis is adjusted one by one at each point around the central axis and the position of the focus of the laser beam is not adjusted, the rotation of the rotating mirror with respect to the central axis is stopped. By adjusting the angles of the mirror and the reflecting mirror, the focal point of the laser beam can be aligned over the entire circumference of the assembly. Therefore, in addition to the effect of the first aspect, there is an effect that the work of aligning the focal point of the laser beam can be simplified.

  According to the spark plug manufacturing method of claim 3, the length of the beam axis from the exit port to the rotary mirror is less than or equal to ½ of the length of the beam axis from the exit port to the processing point. The length of the beam axis up to the machining point of the assembly can be secured. Since the shape and size of the assembly can be made difficult to be restricted due to restrictions such as the position where the reflecting mirror is disposed, in addition to the effects of claim 1 or 2, there are various effects regardless of the shape and size of the assembly. There is an effect that the assembly can be welded.

It is sectional drawing of the spark plug in one embodiment of this invention. It is a perspective view of the welding apparatus in 1st Embodiment. It is sectional drawing of a welding apparatus. (A) is a side view of the center electrode to which the tip is welded, (b) is a side view of the conventional center electrode, and (c) is a side view of the conventional center electrode. It is sectional drawing of the welding apparatus in 2nd Embodiment. It is sectional drawing of the welding apparatus in 3rd Embodiment.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view taken along a plane including the central axis O of a spark plug 10 according to an embodiment of the present invention. In FIG. 1, the lower side of the drawing is referred to as the front end side of the spark plug 10, and the upper side of the drawing is referred to as the rear end side of the spark plug 10. As shown in FIG. 1, the spark plug 10 includes a metal shell 20, a ground electrode 30, an insulator 40, a center electrode 50, a terminal metal 60, and a resistor 70.

  The metal shell 20 is a substantially cylindrical member fixed to a screw hole (not shown) of the internal combustion engine, and a through hole 21 penetrating along the central axis O is formed. The metal shell 20 is made of a conductive metal material (for example, low carbon steel). The metal shell 20 includes a seat portion 22 that protrudes in the shape of a bowl outward in the radial direction, and a screw portion 23 that is formed on the outer peripheral surface on the tip side of the seat portion 22.

  An annular gasket 24 is fitted between the seat portion 22 and the screw portion 23. The gasket 24 seals a gap between the metal shell 20 and the internal combustion engine (engine head) when the screw portion 23 is fitted in the screw hole of the internal combustion engine.

  The ground electrode 30 includes an electrode base material 31 made of metal (for example, made of a nickel base alloy) joined to the tip of the metal shell 20 and a chip 32 joined to the tip of the electrode base material 31. The electrode base material 31 is a rod-like member that is bent toward the central axis O so as to intersect the central axis O. The chip 32 is a plate-like member formed of a noble metal such as platinum, iridium, ruthenium, or rhodium or an alloy containing these as a main component, and is joined to a position that intersects the central axis O by laser welding.

  The insulator 40 is a substantially cylindrical member made of alumina or the like that is excellent in mechanical properties and insulation at high temperatures, and has a shaft hole 41 penetrating along the central axis O. The insulator 40 is inserted into the through hole 21 of the metal shell 20, and the metal shell 20 is fixed to the outer periphery. The insulator 40 has a front end and a rear end exposed from the through hole 21 of the metal shell 20.

  The shaft hole 41 includes a first hole portion 42 located on the leading end side of the insulator 40, a stepped portion 43 that is continuous with the rear end of the first hole portion 42 and expands toward the rear end side, and a rear portion of the stepped portion 43. And a second hole 44 located on the end side. The inner diameter of the second hole 44 is set larger than the inner diameter of the first hole 42.

  The center electrode 50 is a rod-like electrode in which a core material 53 having a thermal conductivity superior to that of the electrode base material 52 is embedded in an electrode base material 52 formed in a bottomed cylindrical shape. The core material 53 is made of copper or an alloy containing copper as a main component. Most of the electrode base material 52 is located in the first hole 42. The tip of the electrode base material 52 is exposed from the first hole 42, and the tip 54 is joined to the tip by laser welding. The chip 54 is a columnar member formed of a noble metal such as platinum, iridium, ruthenium, rhodium, or an alloy containing these as a main component, and faces the chip 32 of the ground electrode 30 through a spark gap.

  The terminal fitting 60 is a rod-like member to which a high voltage cable (not shown) is connected, and is formed of a conductive metal material (for example, low carbon steel). The distal end side of the terminal fitting 60 is disposed in the shaft hole 41 of the insulator 40.

  The resistor 70 is a member for suppressing radio noise generated during sparking, and is disposed in the second hole 44 between the terminal fitting 60 and the center electrode 50. Conductive seals 80 and 90 having conductivity are disposed between the resistor 70 and the center electrode 50 and between the resistor 70 and the terminal fitting 60, respectively. The conductive seal 80 is in contact with the resistor 70 and the center electrode 50, and the conductive seal 90 is in contact with the resistor 70 and the terminal fitting 60. As a result, the center electrode 50 and the terminal fitting 60 are electrically connected via the resistor 70 and the conductive seals 80 and 90.

  The spark plug 10 is manufactured by the following method, for example. First, the center electrode 50 is inserted from the second hole 44 of the insulator 40. The center electrode 50 has a tip 54 welded to the tip of an electrode base material 52. The center electrode 50 is disposed such that the rear end portion 51 is supported by the stepped portion 43 and the front end portion is exposed to the outside from the front end of the shaft hole 41.

  Next, the raw material powder of the conductive seal 80 is put through the second hole portion 44 and filled around the rear end portion 51 and the rear end side. The raw material powder of the conductive seal 80 filled in the second hole 44 is pre-compressed using a compression rod (not shown). The raw material powder of the resistor 70 is filled on the molded body of the raw material powder of the formed conductive seal 80. The raw material powder of the resistor 70 filled in the second hole 44 is pre-compressed using a compression rod (not shown). Next, the raw material powder of the conductive seal 90 is filled on the raw material powder of the resistor 70. The raw material powder of the conductive seal 90 filled in the second hole 44 is pre-compressed using a compression rod (not shown).

  Thereafter, the distal end portion 61 of the terminal fitting 60 is inserted from the rear end side of the shaft hole 41, and the terminal fitting 60 is disposed so that the distal end portion 61 contacts the raw material powder of the conductive seal 90. Next, for example, while heating to a temperature higher than the softening point of the glass component contained in each raw material powder, until the front end surface of the flange 62 provided on the rear end side of the terminal fitting 60 comes into contact with the rear end surface of the insulator 40 The terminal fitting 60 is press-fitted, and an axial load is applied to the raw material powder of the conductive seal 80, the resistor 70, and the conductive seal 90 by the tip 61 of the terminal fitting 60. As a result, each raw material powder is compressed and sintered, and the conductive seal 80, the resistor 70 and the conductive seal 90 are formed inside the insulator 40.

  Next, the metal shell 20 to which the ground electrode 30 is bonded in advance is assembled to the outer periphery of the insulator 40. Thereafter, the tip 32 is welded to the electrode base material 31 of the ground electrode 30, and the electrode base material 31 is bent so that the tip 32 of the ground electrode 30 faces the tip 54 of the center electrode 50 in the axial direction. Get.

  With reference to FIG.2 and FIG.3, the welding apparatus 100 which joins the chip | tips 32 and 54 to the electrode base materials 31 and 52 which comprise the ground electrode 30 and the center electrode 50 is demonstrated. FIG. 2 is a perspective view of the welding apparatus 100 according to the first embodiment, and FIG. 3 is a cross-sectional view of the welding apparatus 100 including the central axis O. In the present embodiment, a case where the tip 54 is laser welded to the electrode base material 52 constituting the center electrode 50 using the welding apparatus 100 will be described. 3, illustration of a part of the electrode base material 52 in the axial direction (the rear end 51 side) is omitted (the same applies to FIGS. 5 and 6).

  As shown in FIG. 2, the welding apparatus 100 includes a first tube portion 101 formed in a cylindrical shape, and a square tube-shaped second tube portion 102 connected to an end portion of the first tube portion 101. . The first cylindrical portion 101 includes a first opening 103 having a first end that is open, and is supported by an arm 108. The first cylinder portion 101 has a gear 109 fixed around the first end. The gear 109 meshes with a gear (not shown) driven by a first motor (not shown), and rotates the first cylinder part 101 and the second cylinder part 102 by driving the first motor (not shown).

  As shown in FIG. 3, the welding apparatus 100 is an apparatus that irradiates the machining point 56 of the assembly 55 with a laser beam 112 emitted from the emission port 111 of the machining head 110. The assembly 55 is obtained by superposing the electrode base material 52 and the tip 54, and a holding device (such as a chuck) prevents the tip 54 from separating from the electrode base material 52 or the position of the tip 54 from shifting during welding. The tip 54 and the electrode base material 52 are pressed in the direction of the central axis O by a not shown). The processing point 56 is set near the boundary between the electrode base material 52 and the tip 54. Note that a holding device (not shown) may not be used. In that case, the tip 54 is temporarily fixed to the electrode base material 52 in advance by resistance welding or the like.

  The processing head 110 is a device that condenses the laser beam 112 at the processing point 56, and includes a condensing system (not shown) such as a lens and a mirror, and is disposed on the central axis O. The processing head 110 receives a continuous wave laser from a laser oscillator (not shown), and emits laser light 112 of the continuous wave laser onto the central axis O from the emission port 111.

  In the first cylinder portion 101, the first opening 103 is opposed to the emission port 111 of the processing head 110, and the axis is disposed on the central axis O. The first cylinder portion 101 is rotatably supported by the arm 108 via a bearing 107. Since the first cylinder portion 101 is supported by the bearing 107, it can rotate smoothly with respect to the arm. The second tube portion 102 is connected to the second end of the first tube portion 101 opposite to the first end, and intersects the first tube portion 101 at an obtuse angle. The second cylinder portion 102 has a second opening portion 104 formed at the end portion that opens on a side surface facing the central axis O. The second cylindrical portion 102 has a rotating mirror 105 disposed at the boundary with the first cylindrical portion 101, and a reflecting mirror 106 disposed on the opposite side of the central axis O across the second opening 104.

  The rotary mirror 105 is a plate-like mirror that reflects the laser beam 112 emitted from the emission port 111 of the processing head 110 onto the central axis O in a direction different from the central axis O, and the mirror surface is oblique to the central axis O. It arrange | positions between the process head 110 and the assembly 55 so that it may cross. The rotating mirror 105 reflects the reflected light 113 of the laser light 112 toward the reflecting mirror 106. The reflecting mirror 106 is a plate-like mirror that reflects the reflected light 113 and irradiates the reflected light 113 toward the processing point 56 of the assembly 55, so that the mirror surface obliquely intersects a straight line parallel to the central axis O. The assembly 55 is disposed in a direction perpendicular to the axis. In the present embodiment, the first cylindrical portion 101 and the second cylindrical portion 102 rotate integrally, and the reflecting mirror 106 rotates integrally with the rotating mirror 105. The reflected light 113 is orthogonal to the central axis O at the processing point 56.

  The assembly 55 is rotated around the central axis O by a second motor (not shown). The rotation direction of the assembly 55 by the second motor (not shown) is opposite to the rotation directions of the first cylinder portion 101 and the second cylinder portion 102 by the first motor (not shown). By rotating the first cylinder part 101 and the second cylinder part 102 and the assembly 55 in the opposite directions, the relative rotational speed of the first cylinder part 101 and the second cylinder part 102 (rotating mirror 105) with respect to the assembly 55 is It is set to 1000 rpm or more.

  In the welding apparatus 100, the length of the beam axis of the laser beam 112 from the exit port 111 of the machining head 110 to the rotary mirror 105 is such that the laser beam 112 from the exit port 111 to the processing point 56 through the rotary mirror 105 and the reflecting mirror 106. And the length of the beam axis of the reflected light 113 is set to ½ or less. As a result, the length of the beam axis of the reflected light 113 from the rotary mirror 105 to the processing point 56 of the assembly 55 can be secured. Since a space for installing the assembly 55 can be secured, the shape, size, and the like of the assembly 55 can be hardly restricted due to restrictions on the position where the reflecting mirror 106 is disposed. Therefore, various assemblies 55 can be welded regardless of the shape and size of the assembly 55.

  Next, with reference to FIG.3 and FIG.4, the welding method of the chip | tip 54 using the welding apparatus 100 is demonstrated. 4A is a side view of the center electrode 50 (see FIG. 1) to which the tip 54 is welded, and FIGS. 4B and 4C are side views of the conventional center electrode. First, the tip 54 (see FIG. 3) and the electrode base material 52 are pressed in the direction of the central axis O by a holding device (not shown) such as a chuck (assembly process), and the assembly 55 is moved around the central axis O in this state. Rotate (rotation process). Similarly, the first cylinder portion 101 and the second cylinder portion 102 are rotated in the direction opposite to the rotation direction of the assembly 55 with the central axis O as the rotation axis.

  When the relative rotational speed of the first cylindrical portion 101 and the second cylindrical portion 102 (rotating mirror 105) with respect to the assembly 55 reaches 1000 rpm or more, the laser beam 112 is emitted from the emission port 111 of the processing head 110. Then, the reflected light 113 is irradiated to the processing point 56 of the assembly 55 (irradiation process). As long as the laser beam 112 is emitted from the emission port 111, it is sufficient that the machining point 56 takes at least one round around the chip 54.

  As a result, as shown in FIG. 4A, a melted portion 57 in which the tip 54 and the electrode base material 52 are melted is formed around the tip 54. Since the welding apparatus 100 irradiates the processing point 56 of the assembly 55 with laser light of a continuous wave laser, the continuous melting portion 57 of the assembly 55 is suppressed while suppressing spatter and the like that are likely to occur when using a pulsed laser. Can be formed around.

  Furthermore, since the relative rotational speed of the rotary mirror 105 with respect to the assembly 55 is 1000 rpm or more, the irradiation time of the laser beam to the assembly 55 can be remarkably shortened. As a result, it is possible to prevent the size (width) of the melting portion 57 from becoming uneven in the circumferential direction of the assembly 55 and to reduce (thinn) the size of the melting portion 57 in the axial direction. If the width of the melting part 57 can be reduced, the axial length L1 of the chip 54 (distance from the end surface of the chip 54 to the melting part 57) can be relatively increased. Since the tip 54 is more resistant to sparks than the melted portion 57, it is possible to stably produce the center electrode 50 having excellent durability by suppressing the occurrence of incompletely welded portions while ensuring the length L1 of the tip 54.

  On the other hand, when the relative rotation speed of the first cylinder portion 101 and the second cylinder portion 102 (rotating mirror 105) with respect to the assembly 55 is less than 1000 revolutions per minute, the laser beam 112 (continuous) is emitted from the emission port 111 of the processing head 110. When the oscillation laser is emitted, the irradiation time of the laser beam to the assembly 55 becomes long. Therefore, if the power is the same as the power of the laser beam 112 when the relative rotation speed is 1000 rotations per minute or more, The energy density at the processing point 56 is increased.

  As a result, as shown in FIG. 4B, the width of the melted portion 58 where the tip 54 and the electrode base material 52 are melted becomes wider than the width of the melted portion 57 (see FIG. 4A). When the width of the melting part 58 is increased, the axial length L2 of the chip 54 (the distance from the end surface of the chip 54 to the melting part 58) is relatively shortened. As a result, compared to the first embodiment, the volume of the chip 54 that can be consumed by the spark is reduced, so that the spark consumption is deteriorated.

  Further, when the laser beam 112 (pulsed laser) is emitted from the emission port 111 of the processing head 110, the center electrode 50 is more likely to be sputtered than when the continuous wave laser is used. Further, since the melted part 59 formed by irradiating the periphery of the chip 54 with the pulsed laser beam is overlapped, the width of the melted part 59 in the circumferential direction of the chip 54 as shown in FIG. Tends to be non-uniform. When the width of the melting part 59 becomes non-uniform, the length L3 in the axial direction of the chip 54 (the distance from the end surface of the chip 54 to the melting part 59) is relatively shortened in the wide part of the melting part 59. As a result, compared to the first embodiment, the volume of the chip 54 that can be consumed by the spark is reduced, so that the spark consumption is deteriorated.

  On the other hand, according to the present embodiment, since a continuous wave laser is used, it is possible to prevent the occurrence of sputtering and the like, and the irradiation time of the laser beam to the assembly 55 can be shortened. Can be small. As a result, the spark wear resistance by the chip 54 can be ensured, so that the center electrode 50 having excellent durability can be manufactured stably.

  In the welding apparatus 100, the reflecting mirror 106 rotates integrally with the rotating mirror 105. Therefore, the angles of the rotary mirror 105 and the reflecting mirror 106 with respect to the central axis O are adjusted one by one at each point around the central axis O so that the focal point of the laser beam 112 does not match the position of the processing point 56 of the assembly 55. Also good. If the rotation mirror 105 and the reflection mirror 106 are adjusted with respect to the center axis O while the rotation of the rotation mirror 105 is stopped, the focal point of the laser beam 112 is adjusted to the position of the processing point 56 of the assembly 55. This is because the focal point of the laser beam 112 can be aligned over the entire circumference of the line 54. Therefore, compared with the case where the reflecting mirror 106 does not rotate integrally with the rotating mirror 105, the work of aligning the focal point of the laser beam 112 can be simplified.

  Further, since the reflecting mirror 106 rotates integrally with the rotating mirror 105, the area of the mirror surface of the reflecting mirror can be reduced as compared with the case where the reflecting mirror is fixed without rotating and only the rotating mirror 105 is rotated. This is because when the reflecting mirror is fixed without being rotated, the reflecting mirror needs an annular mirror surface surrounding the central axis O. Therefore, according to this Embodiment, the cost which concerns on a reflective mirror can be reduced compared with the case where a reflective mirror is fixed without rotating.

  Here, the rotational speed of the assembly 55 and the rotating mirror 105 is such that the relative rotational speed of the rotating mirror 105 with respect to the assembly 55 is 1000 rpm or more, and the material and size of the chip 54 and the electrode base material 52. It is set appropriately according to When only the assembly 55 is rotated and the entire circumference of the assembly 55 is irradiated with the laser beam 112, as the number of rotations of the assembly 55 increases, the molten metal generated by the irradiation of the laser beam 112 is scattered or the molten portion 57 is It becomes easy to deform. However, according to the present embodiment, since both the assembly 55 and the rotary mirror 105 are rotated, the rotational speed of the assembly 55 can be relatively lowered. Therefore, scattering of molten metal and deformation of the molten part 57 can be suppressed.

  It is preferable to set the rotational speed of the rotary mirror 105 higher than the rotational speed of the assembly 55. This is because when the number of rotations of the assembly 55 increases, molten metal generated by the irradiation of the laser beam 112 may be scattered or the molten portion 57 may be deformed. Although depending on the material and size of the chip 54 and the electrode base material 52, the number of rotations of the assembly 55 is preferably 150 rpm.

  Further, the processing head 110 is fixed, the rotating mirror 105 that reflects the laser light 112 emitted from the emission port 111 of the processing head 110 is rotated, and the reflected light 113 is irradiated around the assembly 55 using the reflecting mirror 106. Therefore, the configuration of the welding apparatus 100 can be simplified as compared with the case where the machining head 110 is rotated. Since the machining head 110 is fixed at one point, the number of machining heads can be reduced as compared with the case where a plurality of machining heads are used and laser light is irradiated from multiple points.

  Since the mass of the first cylindrical portion 101 and the second cylindrical portion 102 to which the rotary mirror 105 and the reflecting mirror 106 are fixed can be made smaller than the mass of the processing head 110, the first cylindrical portion 101 and the first cylindrical portion 101 are connected via the gear 109. As the motor (not shown) for rotating the two cylinder portions 102, a motor having a relatively small output can be adopted. Since the mass of the 1st cylinder part 101 and the 2nd cylinder part 102 which rotate around the center axis | shaft O can be made small, the 1st cylinder part 101 and the 2nd cylinder part 102 can be made the maximum rotation speed (relative rotation speed 1000rpm in a comparatively short time. And the like can be stopped within a relatively short time after welding. As a result, it is possible to shorten the time from setting the assembly 55 to the welding apparatus 100 to completing the welding of the tip 54, so that productivity can be improved.

  Next, a second embodiment will be described with reference to FIG. In the first embodiment, the case where the reflecting mirror 106 is rotated integrally with the rotating mirror 105 has been described. In contrast, in the second embodiment, a case where the reflecting mirror 124 is fixed will be described. In addition, about the part same as the part demonstrated in 1st Embodiment, the same code | symbol is attached | subjected and the following description is abbreviate | omitted. FIG. 5 is a cross-sectional view of the welding apparatus 120 according to the second embodiment including the central axis O.

  As shown in FIG. 5, the welding apparatus 120 is an apparatus that irradiates the processing point 56 of the assembly 55 with a laser beam 112 emitted from the emission port 111 of the machining head 110. The first opening 103 formed at the first end of the first cylindrical portion 121 faces the emission port 111 of the processing head 110. The first cylindrical portion 121 has a support portion 122 that supports the rotary mirror 105 connected to the second end opposite to the first end. The 1st cylinder part 121 is formed with the 2nd opening part 123 opened to the side which faces the support part 122. As shown in FIG. The second opening 123 is an opening for irradiating the reflected light 113 to the reflecting mirror 124.

  The reflecting mirror 124 is an annular mirror that reflects the reflected light 113 and irradiates the reflected light 113 toward the processing point 56 of the assembly 55, and is disposed around the central axis O so as to surround the central axis O. ing. The reflecting mirror 124 is disposed outside the assembly 55 in the direction perpendicular to the axis so that the mirror surface obliquely intersects with a straight line parallel to the central axis O. The reflecting mirror 124 is set so that the inner diameter of the mirror surface gradually decreases as the distance from the processing head 110 in the direction of the central axis O increases. In the present embodiment, the reflecting mirror 124 is fixed around the central axis O by a fixing member (not shown).

  The assembly 55 is rotated about a central axis O as a rotation axis by a second motor (not shown). The rotation direction of the assembly 55 by the second motor (not shown) is opposite to the rotation direction of the first cylindrical portion 121 by the first motor (not shown). By rotating the first cylinder 121 and the assembly 55 in the opposite directions, the relative rotation speed of the first cylinder 121 (rotating mirror 105) with respect to the assembly 55 is set to 1000 rotations per minute or more.

  In the welding apparatus 120, the length of the beam axis of the laser beam 112 from the exit port 111 of the machining head 110 to the rotary mirror 105 is such that the laser beam 112 from the exit port 111 to the machining point 56 through the rotary mirror 105 and the reflecting mirror 124. And the length of the beam axis of the reflected light 113 is set to ½ or less. As a result, the same effect as the first embodiment can be realized.

  In order to weld the tip 54 using the welding apparatus 120, first, the assembly 55 is rotated around the central axis O, and the first tube portion is rotated about the central axis O in the direction opposite to the rotational direction of the assembly 55. 121 is rotated. When the relative rotational speed of the first cylindrical portion 121 (rotating mirror 105) with respect to the assembly 55 reaches 1000 rotations per minute or more, the laser beam 112 is emitted from the emission port 111 of the processing head 110 to process the assembly 55. The point 56 is irradiated with the reflected light 113.

  Thereby, the same effect as 1st Embodiment is realizable. Moreover, since the reflecting mirror 124 is fixed to the welding apparatus 120, the mass of the 1st cylinder part 121 rotated around the central axis O can be made smaller. As a result, the first cylinder 121 can be further raised to the maximum rotation speed (relative rotation speed 1000 rpm or more) in a short time, and can be stopped within a short time after welding.

  Next, a third embodiment will be described with reference to FIG. In the first embodiment and the second embodiment, the case where the reflecting mirrors 106 and 124 are formed by one mirror has been described. In contrast, in the third embodiment, a case where the reflecting mirror 135 is formed by two mirrors will be described. In addition, about the part same as the part demonstrated in 1st Embodiment, the same code | symbol is attached | subjected and the following description is abbreviate | omitted. FIG. 6 is a cross-sectional view of the welding apparatus 130 according to the third embodiment including the central axis O.

  As shown in FIG. 6, the welding apparatus 130 is an apparatus that irradiates the processing point 56 of the assembly 55 with a laser beam 112 emitted from the emission port 111 of the machining head 110. The first opening 103 formed at the first end of the first cylindrical portion 131 faces the emission port 111 of the processing head 110. The first cylindrical portion 131 has a support portion 132 that supports the rotary mirror 134 connected to the second end opposite to the first end. The first cylindrical portion 131 is formed with a second opening 133 that opens to a side surface facing the support portion 132. The second opening 133 is an opening for irradiating the reflecting mirror 135 with the reflected light 138.

  The reflecting mirror 135 is an annular mirror that reflects the reflected light 138 and irradiates the reflected light 138 toward the processing point 56 of the assembly 55, and includes a first mirror 136 that is arranged side by side in the direction of the central axis O, and A second mirror 137 is provided. The first mirror 136 and the second mirror 137 are arranged around the central axis O so as to surround the central axis O, and a mirror surface facing the central axis O obliquely intersects a straight line parallel to the central axis O. The first mirror 136 is set such that the inner diameter of the mirror surface gradually increases as it moves away from the processing head 110 in the direction of the central axis O. The second mirror 137 is set such that the inner diameter of the mirror surface gradually decreases as it moves away from the processing head 110 in the direction of the central axis O. In the present embodiment, the reflecting mirror 135 is fixed around the central axis O by a fixing member (not shown).

  The assembly 55 is rotated around the central axis O by a second motor (not shown). The rotation direction of the assembly 55 by the second motor (not shown) is opposite to the rotation direction of the first tube portion 131 by the first motor (not shown). By rotating the first tube portion 131 and the assembly 55 in the opposite directions, the relative rotation speed of the first tube portion 131 (rotating mirror 134) with respect to the assembly 55 is set to 1000 rotations per minute or more.

  In the welding apparatus 130, the length of the beam axis of the laser beam 112 from the exit port 111 of the machining head 110 to the rotary mirror 134 is such that the laser beam 112 from the exit port 111 to the machining point 56 through the rotary mirror 134 and the reflecting mirror 135. And ½ or less of the length of the beam axis of the reflected light 138. As a result, the same effect as the first embodiment can be realized.

  In order to weld the tip 54 using the welding apparatus 130, first, the assembly 55 is rotated around the central axis O, and the first tube portion is rotated about the central axis O in the direction opposite to the rotational direction of the assembly 55. 131 is rotated. When the relative rotational speed of the first cylindrical portion 131 (rotating mirror 134) with respect to the assembly 55 reaches 1000 rotations per minute or more, the laser beam 112 is emitted from the emission port 111 of the processing head 110 to process the assembly 55. The point 56 is irradiated with the reflected light 113. Thereby, the same effect as 2nd Embodiment is realizable.

  The present invention has been described above based on the embodiments. However, the present invention is not limited to the above embodiments, and various improvements and modifications can be made without departing from the spirit of the present invention. It can be easily guessed. For example, the shapes and dimensions of the electrode base material 52 and the chip 54 are examples and can be set as appropriate.

  In each of the above embodiments, the case where the tip 54 is welded to the electrode base material 52 constituting the center electrode 50 has been described, but the present invention is not necessarily limited thereto. When welding the tip 32 to the electrode base material 31 constituting the ground electrode 30, it is naturally possible to apply each of the above embodiments.

  Although the spark plug 10 in which the resistor 70 is built in the insulator 40 has been described in the above embodiment, the present invention is not necessarily limited thereto. Of course, the above-described embodiments can be applied to the manufacture of a spark plug that does not incorporate the resistor 70.

  In the first embodiment, the welding apparatus 100 in which the reflecting mirror 106 is configured by a single mirror has been described. However, the present invention is not necessarily limited thereto. Of course, it is possible to construct a reflecting mirror with two or more mirrors. Similarly, in the second embodiment, the welding apparatus 120 in which the reflecting mirror 124 is configured by one mirror will be described. In the third embodiment, the welding apparatus in which the reflecting mirror 135 is configured by two mirrors will be described. Although 130 has been described, the present invention is not necessarily limited thereto. Of course, it is possible to construct a reflecting mirror with three or more mirrors.

  In each of the above-described embodiments, the case where the reflected lights 113 and 138 are orthogonal to the central axis O at the processing point 56 of the assembly 55 has been described, but the present invention is not necessarily limited thereto. In accordance with the material, shape, size, and the like of the electrode base material 52 and the chip 54, the reflected light 113, 138 is formed so that the reflected light 113, 138 crosses the central axis O obliquely at the processing point 56 of the assembly 55. Of course, it is possible to irradiate the assembly 55. The focal positions of the reflected light 113 and 138 may be adjusted to the surface of the assembly 55 or may be adjusted to be deeper than the surface of the assembly 55.

  In each of the above embodiments, the case where the first cylindrical portions 101, 121, 131 of the welding apparatuses 100, 120, 130 are rotated by a gear train including the gear 109 has been described, but the present invention is not necessarily limited thereto. Of course, it is possible to transmit the power of an actuator such as a motor to the first tube portions 101, 121, 131 by rotating the first tube portions 101, 121, 131 by a transmission mechanism other than the gear train. Examples of other transmission mechanisms include a belt and a chain.

DESCRIPTION OF SYMBOLS 10 Spark plug 30 Ground electrode 31 Electrode base material 32 Tip 50 Center electrode 52 Electrode base material 54 Tip 55 Assembly 56 Processing point 105,134 Rotary mirror 106,124,135 Reflective mirror 110 Processing head 111 Output port 112 Laser beam 113, 138 Reflected light O Central axis

Claims (3)

At least one of the center electrode and the ground electrode is a method of manufacturing a spark plug in which an electrode base material and a tip containing a noble metal are joined by laser welding,
An assembly step of forming an assembly in which the electrode base material and the chip are superimposed;
A rotation step of rotating the assembly about the center axis of the chip as a rotation axis;
Laser light is emitted from the exit of the processing head of the continuous wave laser disposed on the central axis toward the assembly, and the laser light is output by a rotating mirror disposed between the processing head and the assembly. And an irradiation step of irradiating the processed point of the assembly by reflecting the reflected light by one or more reflecting mirrors,
In the irradiation step, the rotary mirror is rotated in the direction opposite to the rotation direction of the assembly with the central axis as a rotation axis, and the relative rotational speed of the rotary mirror with respect to the assembly is 1000 rpm or more. A method of manufacturing a spark plug characterized by the above.   The method of manufacturing a spark plug according to claim 1, wherein the reflecting mirror rotates integrally with the rotating mirror.   3. The length of the beam axis from the exit port to the rotary mirror is ½ or less of the length of the beam axis from the exit port to the processing point. 4. Spark plug manufacturing method.

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