JP2013222519A - Manufacturing method of spark plug and spark plug - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure accuracy of ignition part formation even when a center electrode measuring position and an ignition part processing position are different.SOLUTION: A manufacturing method of a spark plug includes: (a) a step of preparing a spark plug forming member; (b) a step of measuring a center electrode distal end position; and (c) a step of cutting the other end side of a ground electrode forming member. The step (b) includes: (b-1) a step of fixing the spark plug forming member to a holding jig and positioning it to a measurement device; and (b-2) a step of measuring a position for the positioned spark plug forming member. The step (c) includes: (c-1) a step of positioning the holding jig which maintains a fixed state of the spark plug forming member to a cutting device after the step (b); and (c-2) a step of cutting the ground electrode forming member at a cutting part determined on the basis of a result of the (b-2) step for the positioned spark plug forming member.

Description

  The present invention relates to a spark plug manufacturing method and a spark plug.

  Generally, the spark plug includes a center electrode and a ground electrode that is curved so that the end portion faces the center electrode, and the ignition portion is formed by the tip end of the center electrode and the end portion of the ground electrode. When the engine is driven, spark discharge is repeated at the ignition part of the spark plug. In order to ensure the performance of such a spark plug, it is required to accurately form the shape of the ignition portion. As one of the methods for forming the ignition portion with high accuracy, for example, the tip position of the center electrode is measured using an imaging device, and the distance between the tip position and the ground electrode is determined based on the measured tip position. There has been proposed a configuration for calculating a moving distance when the ground electrode is pressed and bent so as to be a target value (see, for example, Patent Document 1).

JP 2002-164149 A JP 2007-5063 A JP 2001-135456 A

  When forming the ignition part of a spark plug, the process which welds an electrode tip to the edge part vicinity of a ground electrode may be performed. In some cases, the ground electrode is cut into a desired length. Depending on the type of processing for forming these ignition parts, using a device common to the position measurement of the center electrode tip using an imaging device, for example, when performing electrode tip welding processing with spatter scattering It may be difficult to do. In such a case, it is necessary to measure the tip position of the center electrode and process it with different devices.

  Further, when forming the ignition part of the spark plug, the bending process for bending the ground electrode is performed together with the above-described electrode chip welding process and ground electrode cutting process. Normally, a plurality of types of processing steps are performed. When performing a plurality of types of processing steps as described above, it is usually difficult to perform the step of measuring the tip position of the center electrode of the spark plug to be processed and all the processing steps using a common apparatus. It is. Therefore, it is necessary to measure the tip position of the center electrode and each processing at different positions using different devices, or to individually measure the tip position of the center electrode in a processing device that performs individual processing. .

  Further, when forming a plurality of types of spark plugs, if a predetermined processing is performed under different processing conditions depending on the type of the spark plug, it is necessary to prepare a different processing apparatus for each processing condition. For example, when manufacturing a plurality of types of spark plugs having different electrode tip forms to be welded near the end of the ground electrode, it is necessary to prepare a welding apparatus that performs welding under different conditions for each type of electrode tip. is there. In such a case, if a single measuring device for measuring the tip position of the center electrode can be used in common for all the processing devices, the configuration of the entire spark plug manufacturing device can be simplified. desirable.

  However, if the measurement of the tip position of the center electrode and the processing for forming the ignition part are performed using different apparatuses, it is difficult to sufficiently secure the processing accuracy based on the result of the position measurement. Problems could arise. That is, when performing processing of the spark plug using a processing device provided separately from the position measurement device, a deviation occurs between the position measurement result and the determination at the time of processing based on the position measurement result, There was a possibility that the accuracy of the shape of the ignition part produced by processing would be insufficient.

  The present invention has been made to solve the above-described conventional problems, and the measuring device for measuring the tip position of the center electrode and the processing device for forming the ignition portion are different devices. The purpose is to ensure the accuracy of the formation of the ignition part.

  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 or application examples.

[Application Example 1]
(A) a center electrode, an insulator disposed on the outer periphery of the center electrode, a metal shell disposed on the outer periphery of the insulator, one end joined to the metal shell, and the other end of the center electrode A ground electrode forming member for forming the ground electrode and the center electrode, the insulator, and the metal shell, in order to manufacture a spark plug including a ground electrode disposed to face the ground electrode A step of preparing a spark plug forming member having one end thereof joined to the metal shell,
(B) measuring the position of the tip of the center electrode in the spark plug forming member;
(C) cutting the other end of the ground electrode forming member joined to the metal shell, and a spark plug manufacturing method comprising:
The step (b)
(B-1) The spark plug forming member is fixed to a holding jig for holding the spark plug forming member, and the holding jig is aligned with a measuring device for measuring the position. Process,
(B-2) The step of measuring the position of the spark plug forming member fixed to the holding jig aligned with the measuring device using the measuring device;
With
The step (c)
(C-1) After the step (b), the step of aligning the holding jig that maintains the state where the spark plug forming member is fixed with respect to a cutting device for performing the cutting;
(C-2) About the spark plug formation member fixed to the holding jig aligned with the cutting device using the cutting device, based on the result of the step (b-2) Cutting the ground electrode forming member at the determined cutting location;
A method of manufacturing a spark plug, comprising:

  According to the spark plug manufacturing method described in Application Example 1, the step of measuring the position of the tip of the center electrode while maintaining the state where the spark plug forming member is fixed to the holding jig, Cutting the other end. And each process is performed after aligning between the measuring device or cutting device which measures a position, and a holding jig. Therefore, when performing the cutting process based on the result measured by the measuring device, the cutting operation of the ground electrode forming member can be accurately performed at a desired position. Thereby, the precision of the ignition part formation in a spark plug is securable.

[Application Example 2]
The spark plug manufacturing method according to Application Example 1, wherein in the step (a), the plurality of spark plug forming members are prepared, and the plurality of spark plug forming members are used by using the plurality of holding jigs. The step (b) and the step (c) are sequentially performed for each of the above, and the step (c-2) is performed for each spark plug forming member fixed to each holding jig. ) Determining the cutting location based on the measurement result of the position performed in the step. According to the spark plug manufacturing method described in the application example 2, for each spark plug forming member, the cutting location is determined based on the position measurement result of the spark plug forming member, and thus the accuracy of the operation of cutting the ground electrode is determined. Can be increased.

[Application Example 3]
The spark plug manufacturing method according to Application Example 2, wherein the step (b) further includes (b-3) storing the position information obtained by measuring the position in association with the holding jig. The step (c) further includes (c-3) a step of identifying the holding jig prior to the cutting, and the step (c-2) is the step (c-3). A method for manufacturing a spark plug, characterized in that the cutting location is determined based on the position information stored in the step (b-3) in association with the identified holding jig. According to the method for manufacturing a spark plug described in Application Example 3, in order to determine the cutting location based on the position information stored in association with the identified holding jig, and storing the position information in association with the holding jig. The accuracy of the operation of cutting the ground electrode can be further increased.

[Application Example 4]
In the method for manufacturing a spark plug according to Application Example 1, in the step (c-2), when the cutting position of the ground electrode forming member is determined, the step (b-1) is performed on the measurement device. The positional relationship between the measuring device and the holding jig when the holding jig is aligned, and the holding jig is aligned with respect to the cutting device in the step (c-1). A method for manufacturing a spark plug, comprising: correcting the cutting location based on an inter-device positional shift representing a positional relationship between the cutting device and the holding jig. According to the spark plug manufacturing method described in the application example 4, the accuracy of the cutting operation of the ground electrode forming member can be further improved by correcting the cutting portion based on the positional deviation between the devices.

[Application Example 5]
The method for manufacturing a spark plug according to Application Example 1 or 4, further comprising (d) a step of welding an electrode tip to the other end of the ground electrode forming member after at least the step (b), The step (d) includes the step (d-1) of aligning the holding jig that maintains the state where the spark plug forming member is fixed with respect to a welding apparatus for welding the electrode tip; (D-2) About the spark plug formation member fixed to the holding jig aligned with the welding apparatus using the welding apparatus, based on the result of the step (b-2). And a step of welding the electrode tip at a welding location determined in this manner. According to the spark plug manufacturing method described in the application example 5, when performing the welding process based on the result measured by the measuring device, the electrode tip welding operation is accurately performed at a desired position, and the ignition portion is formed. Accuracy can be increased.

[Application Example 6]
The spark plug manufacturing method according to Application Example 5, wherein in the step (a), the plurality of spark plug forming members are prepared, and the plurality of spark plug forming members are used by using the plurality of holding jigs. The step (b), the step (c), and the step (d) are performed in a predetermined order, and the step (d-2) includes the spark plugs fixed to the holding jigs. A method for manufacturing a spark plug, characterized in that, for each forming member, the welding location is determined based on a measurement result of the position performed in the step (b-2). According to the spark plug manufacturing method described in the application example 6, for each spark plug forming member, the welding location is determined based on the position measurement result of the spark plug forming member, and thus the accuracy of the operation of welding the electrode tip is increased. Can be increased.

[Application Example 7]
The spark plug manufacturing method according to Application Example 6, wherein the step (b) further includes (b-3) storing the position information obtained by the measurement of the position in association with the holding jig. The step (d) further includes (d-3) a step of identifying the holding jig prior to welding of the electrode tip, and the step (d-2) includes the step (d-3). ) Determining the welding location based on the positional information stored in the step (b-3) in association with the holding jig identified in the step. According to the spark plug manufacturing method of the application example 7, the position information is stored in association with the holding jig, and the welding location is determined based on the stored position information in association with the identified holding jig. The accuracy of the operation of welding the tip can be further increased.

[Application Example 8]
In the method for manufacturing a spark plug according to Application Example 5, in the step (d-2), when the welding location of the electrode tip is determined, the step (b-1) is performed with respect to the measurement device. The positional relationship between the measuring device and the holding jig when the holding jig is aligned, and the position when the holding jig is aligned with respect to the welding device in the step (d-1). A method for manufacturing a spark plug, characterized in that the welding location is corrected based on an inter-device positional shift representing a positional relationship between a welding device and the holding jig. According to the spark plug manufacturing method described in the application example 8, the accuracy of the welding operation of the electrode tip can be further improved by correcting the welding location based on the displacement between the apparatuses.

[Application Example 9]
(A) a center electrode, an insulator disposed on the outer periphery of the center electrode, a metal shell disposed on the outer periphery of the insulator, one end joined to the metal shell, and the other end of the center electrode A ground electrode forming member for forming the ground electrode and the center electrode, the insulator, and the metal shell, in order to manufacture a spark plug including a ground electrode disposed to face the ground electrode A step of preparing a spark plug forming member having one end thereof joined to the metal shell,
(B) measuring the position of the tip of the center electrode in the spark plug forming member;
(D) a step of welding an electrode tip to the other end portion of the ground electrode forming member joined to the metal shell, and a spark plug manufacturing method comprising:
The step (b)
(B-1) The spark plug forming member is fixed to a holding jig for holding the spark plug forming member, and the holding jig is aligned with a measuring device for measuring the position. Process,
(B-2) The step of measuring the position of the spark plug forming member fixed to the holding jig aligned with the measuring device using the measuring device;
With
The step (d)
(D-1) After the step (b), the step of aligning the holding jig that maintains the state in which the spark plug forming member is fixed with respect to a welding apparatus for welding the electrode tip When,
(D-2) About the spark plug forming member fixed to the holding jig aligned with the welding apparatus using the welding apparatus, based on the result of the step (b-2). A step of welding the electrode tip at the determined welding location;
A method of manufacturing a spark plug, comprising:

  According to the spark plug manufacturing method described in the application example 9, the step of measuring the position of the front end portion of the center electrode while welding the electrode tip while maintaining the state where the spark plug forming member is fixed to the holding jig is performed. And a process. And each process is performed after aligning between the measuring device or welding apparatus which measures a position, and a holding jig. Therefore, when performing a welding process based on the result measured with the measuring device, the welding operation of the electrode tip can be performed with high accuracy at a desired position. Thereby, the precision of the ignition part formation in a spark plug is securable.

[Application Example 10]
The spark plug manufacturing method according to Application Example 9, wherein in the step (a), a plurality of the spark plug forming members are prepared, and the plurality of spark plug forming members are used by using the plurality of holding jigs. The step (b) and the step (d) are sequentially performed for each of the above, and the step (d-2) is performed for each spark plug forming member fixed to each holding jig. ) Determining the welding location based on the measurement result of the position performed in the step. According to the method for manufacturing a spark plug described in Application Example 10, for each spark plug forming member, the welding location is determined based on the position measurement result of the spark plug forming member. Can be increased.

[Application Example 11]
The spark plug manufacturing method according to Application Example 10, wherein the step (b) further includes (b-3) storing the position information obtained by measuring the position in association with the holding jig. The step (d) further includes (d-3) a step of identifying the holding jig prior to welding of the electrode tip, and the step (d-2) includes the step (d-3). ) Determining the welding location based on the positional information stored in the step (b-3) in association with the holding jig identified in the step. According to the manufacturing method of the spark plug described in Application Example 11, in order to store the position information in association with the holding jig and to determine the welding location based on the stored position information in association with the identified holding jig, The accuracy of the operation of welding the electrode tip can be further increased.

[Application Example 12]
In the method for manufacturing a spark plug according to application example 9, in the step (d-2), when the welding location of the electrode tip is determined, the step (b-1) The positional relationship between the measuring device and the holding jig when the holding jig is aligned, and the position when the holding jig is aligned with respect to the welding device in the step (d-1). A method for manufacturing a spark plug, characterized in that the welding location is corrected based on an inter-device positional shift representing a positional relationship between a welding device and the holding jig. According to the spark plug manufacturing method described in the application example 12, the accuracy of the welding operation of the electrode tip can be further improved by correcting the cut portion based on the displacement between the apparatuses.

[Application Example 13]
The method for manufacturing a spark plug according to Application Example 9 or 12, further comprising: (c) cutting the other end side of the ground electrode forming member after at least the step (b), c) step (c-1) aligning the holding jig for maintaining the state where the spark plug forming member is fixed to a cutting device for cutting the ground electrode forming member; (C-2) Based on the result of the step (b-2) for the spark plug forming member fixed to the holding jig aligned with the cutting device using the cutting device. And a step of cutting the ground electrode forming member at the cutting location determined in this manner. According to the spark plug manufacturing method described in Application Example 13, when the cutting process is performed based on the result measured by the measuring device, the ground electrode is cut at a desired position with high accuracy, and the ignition portion is formed. Accuracy can be increased.

[Application Example 14]
The spark plug manufacturing method according to Application Example 13, wherein in the step (a), the plurality of spark plug forming members are prepared, and the plurality of spark plug forming members are used by using the plurality of holding jigs. The step (b), the step (c), and the step (d) are performed in a predetermined order, and the step (c-2) includes the spark plugs fixed to the holding jigs. A method for manufacturing a spark plug, characterized in that, for each forming member, the cutting location is determined based on a measurement result of the position performed in the step (b-2). According to the spark plug manufacturing method described in the application example 14, for each spark plug forming member, the cutting location is determined based on the position measurement result of the spark plug forming member, and thus the accuracy of the operation of cutting the ground electrode is determined. Can be increased.

[Application Example 15]
The method for manufacturing a spark plug according to Application Example 14, wherein the step (b) further includes (b-3) storing the position information obtained by measuring the position in association with the holding jig. The step (c) further includes (c-3) a step of identifying the holding jig prior to the cutting, and the step (c-2) is the step (c-3). A method for manufacturing a spark plug, characterized in that the cutting location is determined based on the position information stored in the step (b-3) in association with the identified holding jig. According to the spark plug manufacturing method described in the application example 15, the position information is stored in association with the holding jig, and the cutting location is determined based on the position information stored in association with the identified holding jig. The accuracy of the operation of cutting the ground electrode can be further increased.

[Application Example 16]
In the method for manufacturing a spark plug according to application example 13, in the step (c-2), when the cutting position of the ground electrode forming member is determined, the step (b-1) The positional relationship between the measuring device and the holding jig when the holding jig is aligned, and the holding jig is aligned with respect to the cutting device in the step (c-1). A method for manufacturing a spark plug, comprising: correcting the cutting location based on an inter-device positional shift representing a positional relationship between the cutting device and the holding jig. According to the spark plug manufacturing method described in Application Example 16, the accuracy of the cutting operation of the ground electrode can be further improved by correcting the cutting portion based on the positional deviation between the devices.

[Application Example 17]
The spark plug manufacturing method according to any one of Application Examples 5 to 8 and Application Examples 13 to 16, wherein after the step of welding an electrode tip to the other end of the ground electrode forming member is performed, the ground electrode A method of manufacturing a spark plug, comprising performing a step of cutting the other end of the forming member. According to the spark plug manufacturing method described in Application Example 17, the molten state of the joint between the ground electrode and the electrode tip can be made uniform as compared with the case where the cutting step is performed before the welding step. It is possible to improve the durability near the joint.

[Application Example 18]
The spark plug manufacturing method according to any one of Application Examples 5 to 17, wherein the welding device is a device capable of providing a plurality of types of electrode tips, and is different from each other corresponding to the types of the electrode tips to be provided. In the step of aligning the holding jig to which the spark plug forming member is fixed with respect to the welding device, a plurality of welding device portions for welding the electrode tips under conditions are provided. A method for manufacturing a spark plug, characterized by aligning the holding jig with respect to the welding device portion corresponding to a type. According to the spark plug manufacturing method described in the application example 18, when manufacturing a plurality of types of spark plugs having different electrode tip configurations, it is possible to commonly use a device for measuring the position of the tip of the center electrode. it can. Therefore, the structure of the whole apparatus required in order to manufacture several types of spark plugs can be simplified.

[Application Example 19]
The spark plug manufacturing method according to any one of Application Examples 1 to 8 and Application Examples 13 to 17, and (e) after the step of cutting the other end side of the ground electrode forming member, A gap forming step of bending the ground electrode forming member, wherein the step (e) includes (e-1) the holding jig for maintaining the spark plug forming member fixed, and the ground electrode forming member. And (e-2) using the gap forming device, and fixing to the holding jig aligned with the gap forming device. A step of bending the spark plug forming member with a gap forming condition determined based on a result of the position measurement. Method of manufacturing a spark plug. According to the spark plug manufacturing method described in Application Example 19, in addition to the ground electrode cutting operation, in addition to the operation of cutting the ground electrode, the gap is further processed under the gap forming conditions set based on the measurement result of the measurement device. The forming operation can be performed with high accuracy.

[Application Example 20]
The spark plug manufacturing method according to any one of Application Examples 5 to 17, further comprising: (e) bending the ground electrode forming member after the step of welding the electrode tip to the other end of the ground electrode forming member. A step of forming a gap to be processed, wherein the step (e) includes (e-1) bending the ground electrode forming member with the holding jig that maintains the state in which the spark plug forming member is fixed. And (e-2) forming the spark plug fixed to the holding jig aligned with the gap forming device using the gap forming device. And a step of bending the member under a gap forming condition determined based on the result of the position measurement. Production method. According to the spark plug manufacturing method described in Application Example 20, in order to perform the bending process under the gap forming conditions set based on the result measured by the measuring device, in addition to the electrode tip welding operation, the gap The forming operation can be performed with high accuracy.

[Application Example 21]
The spark plug manufacturing method according to Application Example 19 or 20, wherein the gap forming device includes a support portion serving as a fulcrum when the ground electrode forming member is bent, and the formation of the ground electrode using the support portion as a fulcrum. A pressing portion that applies a pressing force for bending the member, and the gap formation condition includes a position of the support portion, and the step (e-2) uses the pressing portion to Prior to the step of pressing the ground electrode forming member, a method for manufacturing a spark plug, comprising a step of moving the support portion to a position determined based on the result of the position measurement. According to the spark plug manufacturing method described in Application Example 21, since the accuracy of arranging the support portion can be improved, the distance between the tip portion of the ground electrode and the tip portion of the center electrode is desired with high accuracy. The ignition part can be formed with the value of.

  The present invention can be realized in various forms other than those described above. For example, the present invention can be realized in the form of a spark plug manufactured by the spark plug manufacturing method of the present invention, a spark plug manufacturing apparatus, or the like. .

1 is a partial cross-sectional view of a spark plug 100. FIG. 3 is a flowchart showing an outline of a manufacturing process of the spark plug 100. It is a flowchart which shows the outline | summary of the formation process of an ignition part. It is explanatory drawing which expands and represents the shape of an ignition part. 2 is an explanatory diagram schematically showing a schematic configuration of an ignition part forming system 60. FIG. 3 is a perspective view schematically showing a schematic configuration of a holding jig 70. FIG. 4 is a plan view showing a state in which a spark plug forming member 110 is arranged on a holding jig 70. FIG. It is a schematic diagram showing operation | movement of the position measurement apparatus 63 at the time of performing a position measurement. It is explanatory drawing showing the image which the camera 86 images. It is explanatory drawing which shows the determination operation | movement of a welding position. It is explanatory drawing which shows the operation | movement of temporary bending. It is explanatory drawing which shows operation | movement of this bending process. 3 is a perspective view schematically showing a schematic configuration of a holding jig 170. FIG. It is explanatory drawing which shows an example of the screen which the imaging device of the position measuring device 63 images. It is explanatory drawing which represents the schematic structure of the ignition part formation system 160 typically. 2 is an explanatory diagram schematically showing a schematic configuration of an ignition part forming system 260. FIG.

A. Spark plug structure:
FIG. 1 is a partial sectional view of a spark plug 100 as a first embodiment of the present invention. As shown in FIG. 1, the spark plug 100 has an elongated shape that extends along the axis Ax. In FIG. 1, the right side of the axis Ax indicated by a one-dot broken line shows an external front view, and the left side of the axis Ax shows a cross-sectional view of the spark plug 100 cut along a cross section passing through the central axis of the spark plug 100. In the following description, the lower side in FIG. 1 along the axis Ax is referred to as the front end side, and the upper side in FIG. 1 is referred to as the rear end side. In the following description, a virtual axis corresponding to the axis Ax of the completed spark plug 100 is also referred to as an axis Ax for the spark plug being manufactured.

  The spark plug 100 includes an insulator 10, a center electrode 20, a ground electrode 30, a terminal fitting 40, and a metal shell 50. The rod-shaped center electrode 20 protruding from one end of the insulator 10 is electrically connected to a terminal fitting 40 provided at the other end of the insulator 10 through the inside of the insulator 10. The outer periphery of the center electrode 20 is held by the insulator 10, and the outer periphery of the insulator 10 is held by the metallic shell 50 at a position away from the terminal fitting 40. The ground electrode 30 electrically connected to the metal shell 50 forms a spark gap, which is a gap for generating a spark, between the tip of the center electrode 20. The spark plug 100 is attached to a mounting screw hole 201 provided in the engine head 200 of the internal combustion engine via a metal shell 50. When a high voltage of 20,000 to 30,000 volts is applied to the terminal fitting 40, a spark is generated in a spark gap formed between the center electrode 20 and the ground electrode 30.

  The insulator 10 is an insulator formed by firing a ceramic material such as alumina. The insulator 10 is a cylindrical member having a shaft hole 12 that accommodates the center electrode 20 and the terminal fitting 40 formed at the center. A central body 19 having a large outer diameter is formed at the axial center of the insulator 10. A rear end side body portion 18 that insulates between the terminal metal fitting 40 and the metal shell 50 is formed on the terminal metal fitting 40 side of the central body portion 19. A front end side body portion 17 having an outer diameter smaller than that of the rear end side body portion 18 is formed on the center electrode 20 side with respect to the central body portion 19, and a front end side body portion 17 is provided further ahead of the front end side body portion 17. A leg length portion 13 having a smaller outer diameter and a smaller outer diameter toward the center electrode 20 side is formed.

  The metal shell 50 is a cylindrical metal fitting that surrounds and holds a part extending from a part of the rear end side body portion 18 of the insulator 10 to the leg length portion 13, and is made of low carbon steel in this embodiment. The metal shell 50 includes a tool engaging portion 51, a mounting screw portion 52, and a seal portion 54. A tool (not shown) for attaching the spark plug 100 to the engine head 200 is fitted into the tool engaging portion 51 of the metal shell 50. The mounting screw portion 52 of the metal shell 50 has a thread that is screwed into the mounting screw hole 201 of the engine head 200. The seal portion 54 of the metal shell 50 is formed in a hook shape at the base of the mounting screw portion 52, and an annular gasket 5 formed by bending a plate is inserted between the seal portion 54 and the engine head 200. . The front end surface 57 of the metal shell 50 is formed in a circular shape having an opening at the center, and the center electrode 20 protrudes from the long leg portion 13 of the insulator 10 at the center.

  A thin caulking portion 53 is provided on the rear end side of the metal fitting 50 from the tool engaging portion 51. In addition, a thin compression deformation portion 58 is provided between the seal portion 54 and the tool engagement portion 51 as in the caulking portion 53. Between the inner peripheral surface of the metal shell 50 from the tool engagement portion 51 to the crimping portion 53 and the outer peripheral surface of the rear end side body portion 18 of the insulator 10, annular ring members 6 and 7 are interposed. Further, talc (talc) 9 powder is filled between the ring members 6 and 7. At the time of manufacturing the spark plug 100, a crimping process is performed in which the compression deforming portion 58 is compressed and deformed by pressing the crimping portion 53 inward so as to be bent inward. By performing the caulking process, the insulator 10 is pressed toward the front end side in the metal shell 50 through the ring members 6 and 7 and the talc 9. By this pressing, the talc 9 is compressed in the direction of the axis Ax, and the airtightness in the metal shell 50 is enhanced.

  In addition, on the inner periphery of the metal shell 50, the insulator positioned at the base end of the leg long portion 13 of the insulator 10 via the annular plate packing 8 is connected to the metal inner step portion 56 formed at the position of the mounting screw portion 52. The step portion 15 is pressed. The plate packing 8 is a member that maintains the airtightness between the metal shell 50 and the insulator 10 and prevents combustion gas from flowing out.

  The center electrode 20 is a rod-like member in which a core material 25 having better thermal conductivity than the electrode base material 21 is embedded in an electrode base material 21 formed in a bottomed cylindrical shape. In the present embodiment, the electrode base material 21 is made of a nickel alloy containing nickel as a main component, and the core member 25 is made of copper or an alloy containing copper as a main component. The center electrode 20 is inserted into the shaft hole 12 of the insulator 10 with the tip of the electrode base material 21 protruding from the shaft hole 12 of the insulator 10, and is electrically connected to the terminal fitting 40 via the ceramic resistor 3 and the seal body 4. Connected.

  The ground electrode 30 is made of a metal having high corrosion resistance, and a nickel alloy is used as an example. One end (base end) of the ground electrode 30 is welded to the distal end surface 57 of the metal shell 50. The other end (tip) side of the ground electrode 30 is bent in a direction intersecting the axis Ax, and the tip of the ground electrode 30 faces the tip surface of the center electrode 20 on the axis Ax.

  In the present embodiment, an electrode tip 32 is welded to the tip of the ground electrode 30, and this electrode tip 32 faces the tip of the center electrode 20 to form a spark gap. The electrode tip 32 is a noble metal tip formed mainly of a high melting point noble metal. The electrode tip 32 can be formed of, for example, platinum (Pt), iridium (Ir), ruthenium (Ru), rhodium (Rh), or an alloy thereof.

B. Spark plug manufacturing process:
FIG. 2 is a flowchart showing an outline of the manufacturing process of the spark plug 100 according to the embodiment of the present invention. When manufacturing the spark plug 100, first, members to be the metal shell 50, the insulator 10, the center electrode 20, and the ground electrode 30 are prepared (step S100). Here, as a member to be the ground electrode 30, a thin thin plate shape, that is, a rod-shaped member having a substantially rectangular cross section is prepared. In the following description, the rod-shaped member for forming the ground electrode 30 is referred to as a ground electrode forming member 31. Thereafter, the ground electrode forming member 31 is joined to the metal shell 50 (step S110), and the center electrode 20 and the insulator 10 are inserted and assembled to the metal shell 50 (step S120). In addition, as an assembling process of step S120, there are a method for assembling the center electrode 20 to the metal shell 50 and a method for assembling the center electrode 20 after the insulator 10 is assembled to the metal shell 50. However, any of these may be adopted. Thereafter, the above-described caulking process is performed on the metal shell 50 using a caulking tool (not shown) to fix the insulator 10 to the metal shell 50 (step S130). Then, the ground electrode forming member 31 is subjected to processing including bending to form an ignition portion for causing spark discharge when the engine is driven (step S140). The formation process of this ignition part will be described in detail later. In the following description, the member used for the formation process of the ignition part, that is, the center electrode 20, the insulator 10, and the metal shell 50 are provided, and one end of the ground electrode forming member 31 is joined to the metal shell 50. The member is referred to as a spark plug forming member 110. Thereafter, the spark plug 100 is completed by attaching the gasket 5 to the metal shell 50 (step S150). The manufacturing method shown in FIG. 2 is merely an example, and the spark plug can be manufactured by various methods different from this. For example, the process of step S110 for welding the ground electrode forming member 31 to the metal shell 50 may be performed after the caulking process of step S130.

  FIG. 3 is a flowchart showing an outline of the formation process of the ignition part, which is step S140 of FIG. When forming the ignition portion, first, the position of the tip portion of the center electrode 20 provided in the spark plug forming member 110 is measured, and position information relating to the position of the tip portion is acquired (step S200). And based on the positional information acquired by step S200, the electrode tip 32 is welded in the welding location set to the front-end | tip part of the ground electrode formation member 31 (step S210). Further, based on the position information acquired in step S200, the ground electrode forming member 31 is cut at the cutting location set at the tip of the ground electrode forming member 31 (step S220). Further, the cut ground electrode forming member 31 is bent at a predetermined position to form a bent ground electrode 30, and a spark gap is formed between the tip surface of the center electrode 20 (step S230). ) Complete the ignition section. In the following description, specific processing steps (steps S210 to S230) for forming the ignition portion after the position measurement step in step S200 are collectively referred to as processing steps, and each processing step A device that performs the above is also collectively referred to as a processing device.

  FIG. 4 is an explanatory diagram showing an enlarged view of the shape of the ignition part viewed from the side. When forming the ignition part, as shown in FIG. 4, the point A at the tip of the center electrode 20 is used as a reference. The point A is one point on the outer periphery of the tip surface of the center electrode 20 and is the point closest to the tip of the bent ground electrode 30. As shown in FIG. 4, the numerical value that defines the shape of the ignition part is a distance between the tip of the center electrode 20 and the tip of the electrode tip 32 attached to the ground electrode 30 (hereinafter also referred to as gap dimension) α. There is also a distance (hereinafter also referred to as a covering dimension) β between the point A and the tip of the ground electrode 30 in a direction perpendicular to the axis Ax direction.

  In the spark plug, if the gap dimension α is too small, the ignitability may be deteriorated. On the other hand, if the gap dimension α is too large, the required voltage for igniting the spark plug increases, and if the discharge voltage is increased in this way, the durability of the insulator 10 may be reduced. Also, if the cover dimension β is too small, the volume on the tip side of the ground electrode 30 is smaller than that of the electrode tip 32, so that the degree of temperature rise at the tip of the ground electrode 30 increases, and the ground electrode 30 and the electrode tip are increased. There is a possibility that the oxidation of the ground electrode 30 proceeds to the vicinity of the interface with the electrode 32 and the durability of the electrode tip 32 is lowered. On the other hand, if the cover dimension β is too large, the volume of the tip of the ground electrode 30 becomes large, so that the amount of heat absorbed by the ground electrode 30 increases and the possibility of misfire may increase. As described above, in order to ensure the performance of the spark plug, it can be said that it is extremely important to accurately form the shape of the ignition part defined by the gap dimension α and the cover dimension β.

C. Configuration of the ignition part forming system 60:
FIG. 5 is an explanatory diagram schematically showing a schematic configuration of the ignition part forming system 60. In FIG. 5, the outline of arrangement | positioning of each component which comprises the ignition part formation system 60 is shown by the top view. The ignition part formation system 60 is an apparatus for executing steps S200 to S220 in the formation process of the ignition part. The ignition part forming system 60 includes a turntable 61, a plurality of holding jigs 70 fixed to the turntable 61, a position measuring device 63 and a plurality of processing devices arranged at predetermined positions in the vicinity of the turntable 61, And a control unit 66 connected to be capable of exchanging signals with the position measuring device 63 and the plurality of processing devices. In this embodiment, a welding device 64 and a cutting device 65 are provided as the processing device.

  The turntable 61 is a conveying device for sequentially conveying the spark plug forming member 110 from the position measuring device 63 to the welding device 64 and the cutting device 65. The turntable 61 includes a circular disc portion 67 shown in FIG. 5 and a rotation shaft (not shown) attached to the central portion of the disc portion 67, and a rotation (not shown) for rotating the rotation shaft in a fixed direction. Mechanism. For example, a hydraulic cylinder or a motor can be used as the rotation mechanism. In FIG. 5, the rotation direction of the turntable 61 is indicated by an arrow.

  On the upper surface of the disk portion 67 (the surface shown in FIG. 5), eight holding jigs 70 are fixed at equal intervals in the vicinity of the outer periphery. When holding the spark plug forming member 110 sequentially from the position measuring device 63 to the welding device 64 and the cutting device 65 by the turntable 61, the holding jig 70 is placed at a predetermined position on the disk portion 67. This is a member for fixing 110. In the present embodiment, each holding jig 70 is formed in the same shape. The method of fixing the holding jig 70 to the disk portion 67 can be, for example, screwing, and the positional relationship between the disk portion 67 and the holding jig 70 is substantially effective when performing the step of forming the ignition portion. If it does not change to. In order to ensure the positional accuracy when the holding jig 70 is fixed on the disk part 67, for example, each holding jig 70 is provided with a convex engaging part for engaging with the disk part 67. At the same time, a concave engagement receiving part for engaging the holding jig 70 may be provided at a predetermined position on the upper surface of the disk part 67. And what is necessary is just to engage the said engaging part and engagement receiving part. In each holding jig 70, the spark plug forming member 110 is arranged such that the front end portion faces the outer peripheral side of the disc portion 67 of the turntable 61 and the rear end portion faces the center of the disc portion 67. A detailed configuration of the holding jig 70 will be described later.

  The position measuring device 63 measures the position of the tip of the center electrode 20 for each spark plug forming member 110 fixed to the holding jig 70 on the turntable 61, and acquires position information (step S200). Is a device for executing The welding device 64 is a device that executes a step (step S210) of welding the electrode tip 32 at a welding location set at the tip of the ground electrode forming member 31 based on the position information. The cutting device 65 is a device that executes a step (step S220) of cutting the ground electrode forming member 31 at a cutting location set at the tip of the ground electrode forming member 31 based on the position information. The operations executed in each of these devices will be described in detail later.

  The control unit 66 is configured as a logic circuit centered on a microcomputer, and executes a predetermined calculation in accordance with a control program, a ROM in which a control program and control data are stored in advance, and various data are temporarily stored. It includes a RAM for reading and writing, an input / output port for inputting and outputting various signals, and the like. The control unit 66 acquires and stores the position information obtained by the position measuring device 63 and outputs the acquired position information to the welding device 64 and the cutting device 65. Further, in the ignition part forming system 60, when performing predetermined processing using the position information and deriving information related to operations in the welding device 64 and the cutting device 65, at least a part of such processing is performed. The control unit 66 can perform this. The controller 66 may be provided separately from the position measuring device 63, the welding device 64, and the cutting device 65, or may be provided integrally with any one of the devices.

  The disk part 67 of the turntable 61 stops every 45 ° rotation. That is, each holding jig 70 fixed to the disk part 67 can take eight positions as the disk part 67 rotates. In FIG. 5, these positions are represented as position P (I) to position P (VIII). The position P (I) is a position for supplying the spark plug forming member 110 to be used for the firing portion forming process to the holding jig 70. The position P (II) is a position for fixing the supplied spark plug forming member 110 to the holding jig 70. The position P (III) is close to the position measuring device 63 and is a position for executing step S200. The position P (IV) is close to the welding device 64 and is a position for executing step S210. The position P (V) is close to the cutting device 65 and is a position for executing step S220. The position P (VI) is a position for releasing the fixation of the spark plug forming member 110 with respect to the holding jig 70. The position P (VII) is a position for collecting the spark plug forming member 110 from the holding jig 70. The operations at the positions P (I), P (II), P (VI), and P (VII) may be executed using a programmed machine, or may be executed by an operator.

  The disk portion 67 of the turntable 61 can be stopped accurately at each position, and the spark plug fixed to each holding jig 70 with respect to each of the position measuring device 63, the welding device 64, and the cutting device 65. The forming member 110 can be aligned with high accuracy. As a configuration for accurately stopping the disc portion 67 at each position, the following mechanism can be employed. For example, a detection mechanism that detects the relative rotation angle of the reference position provided in the disk portion 67, and a drive mechanism that rotates the turntable so that the rotation angle becomes the rotation angle when the reference position is aligned with a specific position. , Should be provided. Alternatively, each device is provided with an engaging portion (convex portion) for locking the disk portion 67, and the disk portion 67 corresponds to the fixing portion of at least one of the holding jigs 70. It is good also as providing the engagement receiving part (concave part) which can be engaged with a joint part. With such a configuration, each holding jig 70 is arranged such that when the disk portion 67 rotates, the engagement receiving portion engages with the engagement portion and has a predetermined positional relationship with respect to each device. It can be stopped. It is only necessary that alignment between each holding jig 70 fixed to the disk portion 67 and each device can be performed with sufficient accuracy.

D. Fixing the spark plug forming member 110:
FIG. 6 is a perspective view schematically showing a schematic configuration of the holding jig 70. The holding jig 70 includes a fixed portion 71, a stopper 72, and a pedestal portion 73. The fixing portion 71 is a member for fixing and holding the spark plug forming member 110. The stopper 72 is a member for determining the position of the spark plug forming member 110 in the axis Ax direction when the spark plug forming member 110 is fixed to the holding jig 70. The pedestal portion 73 is a plate-like member, and is fixed to the disk portion 67 on the lower surface, and the fixed portion 71 and the stopper 72 are attached to the upper surface.

  As shown in FIG. 6, the fixing | fixed part 71 is provided with the 1st fixing | fixed part 71a and the 2nd fixing | fixed part 71b, and the hinge 71c. The first fixing portion 71 a is fixed to the pedestal portion 73. The second fixing portion 71b is attached to the first fixing portion 71a via the hinge 71c so as to be rotatable about the hinge 71c. Hereinafter, the operation of moving the second fixing portion 71b so that the opposing surfaces of the first fixing portion 71a and the second fixing portion 71b are in contact with each other is referred to as “closing the fixing portion 71”. The operation of moving the second fixing portion 71b so that the portion 71b is separated is referred to as “opening the fixing portion 71”. Each of the first fixing portion 71a and the second fixing portion 71b is provided with a concave portion formed so as to be opposed to each other, and these concave portions are attached screws of the spark plug forming member 110 when the fixing portion 71 is closed. A space for fitting the portion 52 is formed. The fixing portion 71 is fixed by pressing the spark plug forming member 110 with the concave portion. In order to fix the second fixing portion 71b with the fixing portion 71 closed, a fastening jig (not shown) is used.

  FIG. 7 is a plan view showing a state in which the spark plug forming member 110 is arranged on the holding jig 70. In addition, in FIG. 7, description of the 2nd fixing | fixed part 71b and the hinge 71c is abbreviate | omitted. When the spark plug forming member 110 is fixed to the holding jig 70, the spark plug forming member 110 is placed on the first fixing portion 71a with the fixing portion 71 open. The front end surface 57 of the metal shell 50 of the member 110 is placed so as to abut on the side surface on the rear end side of the stopper 72. Thereby, the position of the spark plug forming member 110 in the holding jig 70 in the direction of the axis Ax can be defined with the front end surface 57 as a reference. At this time, the spark plug forming member 110 is disposed so as to fit into the already-described recess of the first fixing portion 71a. The operation of placing the spark plug forming member 110 on the holding jig 70 described above is performed at the position (I) described above.

  Further, at this time, the spark plug forming member 110 is oriented so that the ground electrode forming member 31 is closest to the pedestal portion 73, that is, the welding surface on which the electrode tip 32 of the ground electrode forming member 31 is welded is the upper surface. It is placed on the pedestal 73. When the spark plug forming member 110 is placed, for example, the ground electrode forming member 31 of the spark plug forming member 110 may be gently pressed from above, so that the spark plug forming member is oriented as described above. 110 can be rotated. Alternatively, when the spark plug forming member 110 is placed, the ground electrode forming member 31 may be subjected to image analysis, and the spark plug forming member 110 may be rotated based on the analysis result so as to be in the above-described direction.

  Thereafter, the fixing portion 71 is closed, and the fixing portion 71 is fixed in a closed state using a fixing jig (not shown). Thereby, the spark plug forming member 110 is fixed to the holding jig 70. The operation for adjusting the orientation of the spark plug forming member 110 on the holding jig 70 and the fixing operation described above are performed at the position P (II) described above.

E. Position measurement process:
FIG. 8 is a schematic diagram showing the operation of the position measuring device 63 when measuring the position of the tip of the center electrode 20 in the position measuring step of step S200. The position measuring device 63 has an arm 85 provided with a camera 86 at the tip. The camera 86 is an imaging device configured by, for example, a CCD camera. The arm 85 extends to a position where the tip end portion to which the camera 86 is attached overlaps with the vicinity of the outer periphery of the disk portion 67 in a top view. The arm 85 can reciprocate in the vertical direction, and moves downward in the vertical direction when the holding jig 70 is fixed at the position P (III). In FIG. 8, the state in which the tip of the arm 85 provided with the camera 86 moves downward in the vertical direction is indicated by an arrow. When the arm 85 moves downward in the vertical direction and stops at a predetermined position near the surface of the disk portion 67, the camera 86 is disposed at a predetermined imaging position and is stopped at the position P (III). A specific area near the tip of the plug forming member 110 can be imaged. Specifically, the camera 86 can image the region including the tip of the center electrode 20 and the ground electrode forming member 31 from the side surface. When imaging for position measurement is completed in the camera 86, the arm 85 moves upward in the vertical direction. That is, the camera 86 attached to the arm 85 moves to a position where it does not interfere with the subsequent rotational movement of the spark plug forming member 110.

  FIG. 9 is an explanatory diagram showing an image captured by the camera 86 stopped at the imaging position. The position measuring device 63 includes an image processing unit that analyzes the captured image and derives position information. In the position measuring device 63, the reference point O is set in advance within the range of the imaging area captured by the camera 86. Then, the image processing unit measures the position of the point A described above at the tip of the center electrode 20 with the reference point O as a reference.

  The position of the point A at the tip of the center electrode 20 can be specified as a three-dimensional coordinate with respect to the position measuring device 63. FIG. 5 shows an X axis, a Y axis, and a Z axis, which are coordinate axes for specifying a three-dimensional position at the position P (III). The X axis is parallel to the upper surface of the disk portion 67 and the axis Ax, and the Y axis is parallel to the upper surface of the disk portion 67 and perpendicular to the X axis. The Z axis is perpendicular to the upper surface of the disk portion 67. By analyzing the image captured by the camera 86, the two-dimensional coordinates in the XZ plane shown in FIG. 9 can be obtained using the preset reference point O as the position of the point A. In the present embodiment, when the holding jig 70 is fixed at the position P (III), the position of the spark plug forming member 110 fixed to the holding jig 70 in the Y-axis direction may be fixed to a fixed position. it can. Therefore, the three-dimensional coordinates of the point A with respect to the position measurement device 63 can be specified by performing image processing based on the captured image. In this embodiment, the coordinates (x, z) of the point A having the reference point O as the origin in the XZ plane are derived as position information.

  Moreover, in this embodiment, the number PN of 1-8 is attached | subjected to each predetermined location of each of the eight holding jigs 70 attached to the turntable 61. Then, the imaging range and the position of the number PN are set so that the number PN fits in the image captured by the camera 86. FIG. 9 shows a state in which the number PN is imaged together with the tip of the spark plug forming member 110. The image processing unit analyzes the image captured by the camera 86 to derive position information and identify the holding jig 70 to which the spark plug forming member 110 that is the position measurement target is fixed. The position measurement device 63 outputs jig identification information indicating which holding jig 70 is associated with the position information to the control unit 66 together with the position information. And the control part 66 memorize | stores the jig | tool identification information matched with position information with the acquired position information. The imaging device for imaging the number PN may be provided separately from the camera 86 for imaging the vicinity of the tip of the spark plug forming member 110.

  In order to identify the holding jig 70, a jig identification mark other than a number may be attached to each holding jig 70. It suffices that the position measuring device 63 is readable and can identify each holding jig 70. Alternatively, each holding jig 70 may be identified without attaching a special jig identification mark to the holding jig 70. For example, the position measuring device 63 may count the number of times the position measurement operation is performed (incremented each time the operation is performed), and use the counted number as jig identification information. In this case, when the count number reaches 8, a process of returning the count number to 0 (resetting) may be performed.

  Further, the image processing unit may be provided in the control unit 66 instead of the position measurement device 63. In this case, the captured image data may be output as position information from the position measurement device 63 to the control unit 66.

F. Welding process:
FIG. 10 is an explanatory diagram illustrating an example of an operation in which the welding device 64 determines the welding location D where the electrode tip 32 is to be welded in the welding process of step S210 of FIG. The welding point D is the tip of the ground electrode forming member 31 from the intersection E between the straight line extending in the direction perpendicular to the axis Ax direction from the tip surface of the center electrode 20 to the ground electrode forming member 31 and the ground electrode forming member 31. This is a point separated by a predetermined distance F to the side. When determining the welding location D, first, an imaginary line IL that forms a predetermined angle θ from the tip surface of the center electrode 20 is extended from the point A toward the ground electrode forming member 31. The angle θ can be set to 45 °, for example. Then, a point B that is an intersection of the virtual line IL and the surface of the ground electrode forming member 31 is obtained. Thereafter, a point separated from the point B by a distance C toward the tip end side of the ground electrode forming member 31 is set as a welding location D. Here, the distance C is a value set in advance according to the type of the spark plug 100 to be manufactured (for example, the shape of the ground electrode 30 and the electrode tip 32 to be formed).

  The welding apparatus 64 includes a welding location derivation processing unit that performs arithmetic processing for deriving the welding location D as shown in FIG. In step S <b> 210, the elution site derivation processing unit acquires the position information that is the coordinates of the point A and the jig identification information from the control unit 66 in association with each other. Further, prior to the operation of setting the welding location D, the welding device 64 identifies the holding jig 70 that fixes the spark plug forming member 110 to be welded in the same manner as the position measuring device 63. Specifically, the welding device 64 includes an imaging device and an image processing device similar to the position measurement device 63 for identifying the number PN given to the pedestal portion 73, and the holding jig is determined based on the image analysis result. 70 is identified. However, the welding device 64 does not perform image analysis for measuring the position of the tip of the center electrode 20. Then, the welding location derivation processing unit derives the welding location D based on the position information associated with the jig identification information representing the identified holding jig 70.

  In such a welding device 64, the reference point O (the origin of coordinates for recognizing the position of the point A) shown in FIG. 9 is shared with the position measuring device 63. Specifically, a holding jig 70 having a predetermined origin (reference point O) for measuring the position in the position measuring device 63 and a predetermined origin for determining the welding location D in the welding device 64. The relative positional relationship with respect to is predetermined. Since the positional relationship between the spark plug forming member 110 and the holding jig 70, between the holding jig 70 and the disk part 67, and between the disk part 67 stopped at a predetermined position and each device is fixed with high accuracy, The relative positional relationship described above can be determined in advance. Therefore, even if the welding device 64 does not have a configuration for position measurement, the position information acquired by the position measurement device 63 can be used to accurately recognize the position of the point A. As a result, the welding location D can be determined with high accuracy, and the electrode tip 32 can be accurately welded to the desired location.

  In the welding apparatus 64, the electrode tip 32 is mounted on the welding location D set on the ground electrode forming member 31, and the electrode tip 32 is welded by, for example, resistance welding, laser welding, or a combination thereof. In resistance welding, after the electrode tip 32 is placed on the welding location D on the ground electrode forming member 31, the electrode tip 32 is held by the welding electrode, and a current is passed between the welding electrode and the ground electrode forming member 31. Perform using heat generated by contact resistance. In the case of performing laser welding, after the electrode tip 32 is placed at the welding location D on the ground electrode forming member 31, the end face of the electrode tip 32 is pressed with a pin (not shown) having a diameter smaller than that of the electrode tip 32. However, laser irradiation is performed on the interface between the ground electrode forming member 31 and the electrode tip 32.

  As shown in FIG. 10, in the welding apparatus 64, the welding location D is set as the coordinate in the XZ plane similar to FIG. In FIG. 5, the X axis, the Y axis, and the Z axis are shown at the position P (IV) as well as at the position P (III). Here, in the present embodiment, the position of the ground electrode forming member 31 in the Y-axis direction and the Z-axis direction is substantially constant even if the spark plug forming member 110 to be welded is sequentially replaced at the position P (IV). It becomes. The welding device 64 conveys the electrode tip 32 and places the electrode tip 32 on the ground electrode forming member 31 from above the holding jig 70 in the vertical direction, and grounds the electrode tip 32. A welding portion (not shown) welded to the electrode forming member 31. These conveyance / mounting part and welding part can be moved in the X-axis direction along the axis Ax, whereby the electrode tip 32 can be provided on the determined welding location D. In this embodiment, when the welding location D is determined as coordinates on the XZ plane, the transport / placement portion and the welding portion are driven using the X coordinate of the welding location D as a command value. Even when the relative position of the origin determined in advance by the position measuring device 63 and the origin determined in advance by the welding device 64 with respect to the holding jig 70 is determined in advance, Due to the molding accuracy of the turntable 60, a deviation may occur for each holding jig 70. In the present embodiment, it is assumed that such a deviation can be ignored, but a configuration for correcting the deviation will be described in a second embodiment to be described later.

  The welding location derivation processing unit may be provided in the control unit 66 instead of the welding device 64. In this case, the welding apparatus 64 may acquire information representing the position of the welding location D set by the control unit 66 from the control unit 66 instead of the positional information and jig identification information associated with each other. .

G. Cutting process:
As described above, the cutting process in step S220 is performed by the cutting device 65 at the position P (V). The cutting device 65 cuts the ground electrode forming member 31 at a cutting point set by a method similar to the method for setting the welding point D described with reference to FIG. However, the cutting location is a predetermined distance that is longer than the distance C from the point B that is the intersection of the imaginary line IL and the ground electrode forming member 31 to the tip side of the ground electrode forming member 31. It is set as a point separated by a distance. The distance between the point B and the cut portion is set in advance based on the size of the gap dimension α determined according to the type of the spark plug 100 to be manufactured.

  Here, the cutting device 65 includes a cutting point derivation processing unit that performs the above-described calculation processing for deriving the cutting point based on the position information acquired from the control unit 66. In step S <b> 220, the cutting location derivation processing unit acquires the position information that is the coordinates of the point A and the jig identification information from the control unit 66 in association with each other. Further, the cutting device 65 identifies the holding jig 70 that fixes the spark plug forming member 110 to be welded in the same manner as the welding device 64 prior to the operation of setting the cutting location. Then, the cutting location derivation processing unit derives the cutting location based on the positional information associated with the jig identification information representing the identified holding jig 70.

  In such a cutting device 65, the reference point O (the origin of coordinates for recognizing the position of the point A) is shared with the position measuring device 63 in the same manner as the welding device 64. . That is, the relative positional relationship between the predetermined origin for measuring the position in the position measuring device 63 and the predetermined origin for determining the cutting location in the cutting device 65 with respect to the holding jig 70 is determined in advance. It has been decided. Therefore, even if the cutting device 65 does not have a configuration for position measurement, the position information acquired by the position measurement device 63 can be used to accurately recognize the position of the point A. As a result, the cutting location can be determined with high accuracy, and the ground electrode forming member 31 can be accurately cut at the desired location.

  In the cutting device 65, similarly to the case where the welding location D is determined, the cutting location is set as coordinates in the XZ plane. FIG. 5 shows the X axis, the Y axis, and the Z axis at the position P (V). In the present embodiment, at the position P (V), similarly to the position P (IV), even if the spark plug forming member 110 to be cut is sequentially replaced, the ground electrode forming member in the Y-axis direction and the Z-axis direction. The position 31 is substantially constant. The cutting device 65 includes a cutting unit (not shown) including a cutter for cutting the ground electrode forming member 31. This cutting part is movable in the X-axis direction along the axis Ax, and thereby the ground electrode forming member 31 can be cut at the determined cutting location. In this embodiment, when a cutting location is determined as coordinates on the XZ plane, the cutting portion is driven using the X coordinate of the cutting location as a command value.

  Note that the cutting location derivation processing unit may be provided in the control unit 66 instead of the cutting device 65. In this case, the cutting device 65 may acquire information representing the position of the cutting point set by the control unit 66 from the control unit 66 instead of the positional information and jig identification information associated with each other.

  As described above, after the cutting process of step S220 is performed at the position P (V), the spark plug forming member 110 is moved to the position P (VI) by the rotation of the turntable 61, and the fixing portion 71 is moved. be opened. Thereafter, the spark plug forming member 110 further moves to the position P (VII), is recovered from the turntable 61, and is used for the gap forming step in step S230.

H. Gap formation process:
Hereinafter, an outline of the gap forming step will be described. The gap forming step is a step for bending the ground electrode forming member 31 to form the ground electrode 30, and includes a provisional bending step and a main bending step. The provisional bending step is a step of bending the rod-shaped ground electrode forming member 31 to some extent so that the distance between the electrode tip 32 and the tip of the electrode tip 32 is larger than the desired gap dimension α. This is a process for determining the position of the curved portion of the ground electrode 30. The main bending step is a step of further bending the ground electrode forming member 31 after the temporary bending so that the gap dimension α becomes a desired value.

  FIG. 11 is an explanatory view showing the operation of the temporary bending step. 11, the X axis, the Y axis, and the Z axis are shown so that the relative orientation with respect to the spark plug forming member 110 is the same as that in FIG. The temporary bending apparatus that performs the temporary bending step includes a support unit 80 and a roller 81, a support unit driving unit and a roller driving unit (not shown) for driving each of the support unit 80 and the roller 81, and a support unit driving unit. And a first drive control unit (not shown) for controlling the drive amount of the roller drive unit. The support portion 80 is a rod-shaped member that is arranged in the vicinity of the rod-shaped ground electrode forming member 31 before temporary bending so that the direction perpendicular to the longitudinal direction of the ground electrode forming member 31 (Z-axis direction) is the longitudinal direction. Yes, and defines the position of the curved portion formed in the ground electrode 30. The support unit 80 can be moved by the support unit driving unit, and can be arranged at an arbitrary position near the ground electrode forming member 31 and near the center electrode 20. The roller 81 functions as a pressing portion that applies a pressing force for bending. When a pressing force is applied using the roller 81, the ground electrode forming member 31 is bent with the support portion 80 as a fulcrum.

  FIG. 11A shows a state in which the support portion 80 is disposed for temporary bending. The arrangement position of the support portion 80 in the temporary bending step is a position for obtaining a desired gap dimension α by curving the ground electrode forming member 31, and the position of the above-described point A that is the tip of the center electrode 20. Is determined in advance as a reference and stored in the first drive control unit. The temporary bending device further includes an imaging device and an image processing unit, similar to the position measuring device 63, and the position of the point A can be identified for the spark plug forming member 110 to be processed set in the temporary bending device. It has become. The first drive control unit drives the support unit drive unit based on the position of the identified point A and the stored coordinates with reference to the point A, and arranges the support unit 80 at a predetermined position. .

  FIG. 11B shows an operation of bending the ground electrode forming member 31 using the roller 81 in the temporary bending process. By moving the roller 81 in the Z-axis direction, the ground electrode forming member 31 can be bent with the support portion 80 as a fulcrum. In the provisional bending step, the range in which the roller 81 is moved may be always the same, but the position in the X-axis direction when the roller 81 is moved may be finely adjusted according to the arrangement location of the support portion 80. . The support portion 80 may have a shape other than a rod shape, and may be any shape that can serve as a fulcrum when the ground electrode forming member 31 is bent.

  FIG. 12 is an explanatory diagram showing the operation of the main bending process. 12, the X axis, the Y axis, and the Z axis are shown so that the relative orientation with respect to the spark plug forming member 110 is the same as that in FIG. The main bending apparatus that performs the main bending process includes a press head 82, a press head drive unit (not shown) for driving the press head 82, and a second drive control unit that controls the drive amount of the press head drive unit. (Not shown). The pressing head 82 is a member that can move in a direction parallel to the axis Ax (X-axis direction), and moves from the front end side to the rear end side of the spark plug forming member 110, whereby a temporary bending step. The ground electrode forming member 31 curved to a certain extent can be further pressed and bent. In this bending step, the pressing head 82 moves to a position separated from the tip surface of the center electrode 20 by a distance G and presses the ground electrode forming member 31. This distance G is a value for obtaining a desired gap dimension α, and is determined in advance with reference to the position of the point A, which is the tip of the center electrode 20, and is stored in the second drive control unit. ing. The bending apparatus further includes an imaging device and an image processing unit as in the position measuring apparatus 63, and the position of the point A can be identified for the spark plug forming member 110 to be processed set in the bending apparatus. It has become. Based on the position of the identified point A and the distance G stored with reference to the point A, the second drive control unit drives the pressing head driving unit to move the pressing head 82 to a predetermined position. Thus, the bent ground electrode 30 is completed.

  By performing the gap forming step as described above, the support portion 80 is accurately placed at the position of the point A to perform a temporary bending step, and the pressing head 82 is moved to the point A with high accuracy to perform the main bending. A process can be performed. As a result, if the electrode tip 32 is accurately welded to a predetermined position of the ground electrode forming member 31, an ignition portion having a desired gap dimension α can be formed with high accuracy.

  According to the manufacturing method of the spark plug 100 of the present embodiment configured as described above, the position of the tip portion of the center electrode 20 is measured while maintaining the state where the spark plug forming member 110 is fixed to the holding jig 70. A step of welding the electrode tip 32, and a step of cutting the end portion of the ground electrode forming member 31. And each process is performed after aligning between the position measuring device 63, the welding device 64, or the cutting device 65, and the holding jig 70. FIG. Therefore, when performing the welding process and the cutting process based on the results measured by the position measuring device 63, the welding operation of the electrode tip 32 and the cutting operation of the ground electrode forming member 31 can be accurately performed at a desired position. it can. Thereby, even if the position measuring device 63, the welding device 64, and the cutting device 65 are separately provided at different positions, it is possible to ensure the accuracy of the ignition portion formation. That is, since the electrode tip 32 can be arranged with high accuracy, the accuracy of the gap dimension α in the ignition portion can be improved. Further, since the ground electrode forming member 31 can be accurately cut at a desired position, the accuracy of the covering dimension β in the ignition portion can be improved. Further, by using the position information acquired by the position measuring device 63 in common by the welding device 64 and the cutting device 65, the system configuration for forming the ignition portion can be simplified.

  Here, the main cause of the variation that occurs when recognizing the position of the tip portion of the center electrode 20 in each step is, for example, the variation associated with the operation of attaching / detaching the spark plug forming member 110 to / from each device. . In addition, variations that occur during assembly of the spark plug forming member 110, specifically, the positional relationship between the metal shell 50 and the insulator 10 and the positional relationship between the insulator 10 and the center electrode 20 are different. The variation of the protrusion amount of the center electrode 20 from 50 is mentioned. According to the present embodiment, since the fixed state is maintained after the spark plug forming member 110 is fixed to the holding jig 70 prior to the position measurement, the spark plug forming member 110 is attached to and detached from each device. It is possible to suppress the variation caused by. Further, each device relatively recognizes the position of the tip portion of the center electrode 20 based on a reference point that is shared among the devices, so that the influence of variations caused when the spark plug forming member 110 is assembled is affected. Can be suppressed.

  In the present embodiment, the position information is generated, stored, and acquired in association with the jig identification information. Therefore, the welding device 64 and the cutting device 65 can use the position information measured by the position measuring device 63 for the spark plug forming member 110 to be processed, so that the accuracy of welding or cutting processing can be improved. it can.

  Furthermore, in this embodiment, when performing a welding process and a cutting process, the welding process is performed previously. Therefore, as compared with the case where the cutting process is performed before the welding process, the length on the tip side of the ground electrode forming member 31 on the tip side (volume on the tip side of the weld spot D) is ensured to be larger. be able to. If the length on the tip side is shorter than the welding location D, the spread of heat to the tip side of the ground electrode forming member 31 is suppressed during welding, and the tip side becomes hot, and the electrode tip 32 and the ground electrode are formed. The molten state of the joint between the member 31 and the distal end side and the proximal end side may be uneven. Thus, when the molten state of the joint part of the electrode tip 32 becomes non-uniform, when the ignition part repeats thermal expansion and contraction as the spark plug 100 is used, it is caused by a difference in thermal expansion coefficient or the like. The durability in the vicinity of the joint may be reduced. In the present embodiment, since the length on the tip side can be secured longer than the welding location D in the ground electrode forming member 31 during the melting step, the joint portion of the electrode tip 32 can be formed more uniformly. Thus, durability near the joint can be improved.

I. Second embodiment:
In the first embodiment, the reference point O (the origin of coordinates for recognizing the position of the point A) is shared between the position measuring device 63 and each processing device. That is, the relative positional relationship between the predetermined origin for measuring the position in the position measuring device 63 and the predetermined origin for determining the processing location in each processing apparatus with respect to the holding jig 70 is determined in advance. It has been decided. Actually, however, there is an error in the shape of each holding jig 70 and the shape of the joint portion of the disk portion 67 with each holding jig 70. Therefore, for each holding jig 70, an error may occur in the relative positional relationship between the position measuring device 63 and the relative positional relationship between each processing device. In other words, the relative positional relationship between the predetermined origin for measuring the position in the position measuring device 63 and the predetermined origin for determining the processing location in each processing apparatus with respect to the holding jig 70 is held. There is a possibility that each jig 70 is displaced. Therefore, it is good also as calculating | requiring the positional offset amount which arises between apparatuses for every holding jig 70 previously, and correct | amending the welding location D and a cutting location based on the calculated positional offset amount. Such a configuration and the second embodiment will be described below.

  In order to obtain the displacement amount for each holding jig 70, for example, a large number of spark plug forming members 110 are prepared in advance for each holding jig 70, and steps S200 to S220 are executed. And about each spark plug formation member 110 which the welding process and the cutting process were complete | finished, the welding position of the electrode tip 32 and the cutting position of the ground electrode formation member 31 are measured, and the average value of deviation | shift between target positions is calculated | required. . What is necessary is just to set the correction value which can eliminate the shift | offset | difference in each process based on the average value of the said shift | offset | requirement regarding each process about each holding jig 70. In the welding process or the cutting process, the position of the origin (reference point O) may be corrected using the correction value, and the welding location D or the cutting location may be set.

  With such a configuration, it is possible to correct misalignment between each holding jig 70 and each device. Therefore, regardless of which holding jig 70 is used, welding of the electrode tip 32 and the ground electrode forming member 31 are performed. The accuracy of performing the cutting operation at a desired position can be further increased.

J. et al. Third embodiment:
In the processing apparatuses of the first and second embodiments, based on the relative positional relationship between the origin determined in advance by the position measuring device 63 and the origin determined in advance by each processing apparatus with respect to the holding jig 70, Although the position of the point A is recognized, a different configuration may be used. For example, a reference point O is given on each holding jig 70, and the position of the reference point O on the holding jig 70 is identified in each of the position measuring device 63, the welding device 64, and the cutting device 65. Also good. Such a configuration will be described below as a third embodiment.

  FIG. 13 is a perspective view schematically showing a schematic configuration of the holding jig 170 used in the third embodiment. The holding jig 170 has the same configuration as that of the holding jig 70 of the first embodiment, and further includes a position identification portion 75 with a position identification mark 74 on the surface of the pedestal portion 73. In FIG. 13, the same reference numerals are assigned to portions common to the holding jig 70, and detailed description thereof is omitted.

  The position identification part 75 has a substantially cubic structure provided so as to protrude vertically from the upper surface of the substantially cubic base part 73 of the holding jig 170. The position identification unit 75 is parallel to the side H in the vicinity of one side H of the two sides that are substantially parallel to the axis Ax direction of the spark plug forming member 110 among the four sides that constitute the upper surface of the pedestal 73. Provided (see FIG. 13). More specifically, when the spark plug forming member 110 is fixed on the pedestal portion 73, it is provided in the vicinity of a region where a portion corresponding to the ignition portion is disposed. In the position identification unit 75, a position identification mark 74 is provided on a surface I that is parallel to the side H and is separated from the side H.

  In the present embodiment, in addition to the position measuring device 63, the welding device 64 and the cutting device 65 also include an imaging device and an image processing unit. Each of these imaging devices has a side H of the four sides constituting the upper surface of the pedestal 73 when the holding jig 170 stops at positions P (III), P (IV), or P (V). An area including the tip of the center electrode 20, the ground electrode forming member 31, and the position identification mark 74 is imaged in the direction facing the surface I of the position identifying portion 75 from the side J facing the surface.

  FIG. 14 is an explanatory diagram illustrating an example of a screen imaged by the imaging device included in the position measurement device 63. In FIG. 14, only the front end portion of the spark plug forming member 110 and the position identification mark 74 are shown, and the description of the other components is omitted. On the screen imaged by the imaging device, a position identification mark 74 is arranged in the vicinity of the tip of the center electrode 20. As shown in FIG. 14, the position identification mark 74 is composed of two orthogonal line segments. The image processing unit included in the position measurement device 63 of the present embodiment constitutes a position identification mark 74 in addition to the point A at the tip of the center electrode 20 when analyzing an image in the vicinity of the ignition unit imaged by the imaging device. The position of the intersection K of the two line segments is identified. Then, as in the first embodiment, the coordinates of the point A are derived two-dimensionally with the intersection K as the reference point O, and output as position information.

  Similarly to the position measuring device 63, the welding device 64 and the cutting device 65 also identify the position of the intersection point K by the imaging device and the image processing unit. However, the welding device 64 and the cutting device 65 do not identify the position of the point A. In the welding device 64 and the cutting device 65, the position information derived by the position measuring device 63 is acquired, the position of the point A is recognized based on the identified position of the intersection K and the position information, and the welding process or the cutting process is performed. Run.

  In the third embodiment described above, the position of the point A in each of the position measuring device 63, the welding device 64, and the cutting device 65 is based on the intersection K of the position identification mark 74 fixed to the surface of the holding jig 170. Recognize Therefore, even if a shake occurs in the alignment between the holding jig 170 and each device, the position of the point A is set as a relative position with respect to the intersection K based on the position information derived by the position measuring device 63. It becomes possible to recognize correctly, and the precision which sets the welding location D and a cutting location can be improved. Moreover, according to this embodiment, in the welding apparatus 64 and the cutting apparatus 65, since the object of an image process is only the intersection K, the increase in the processing burden in an image processing part can be suppressed. The shape of the position identification unit 75 and the position identification mark 74 can be variously modified. The position identification mark 74 may be used as a reference point for identifying the position of the point A.

K. Fourth embodiment:
In the first to third embodiments, a specific type of spark plug is manufactured using the ignition unit forming system 60, but a different configuration may be used. Hereinafter, an embodiment in which a plurality of types of spark plugs having different configurations of the ignition portion, specifically, the electrode tips, are manufactured using a common ignition portion forming system will be described as a fourth embodiment.

  FIG. 15 is an explanatory view schematically showing a schematic configuration of the ignition part forming system 160 of the fourth embodiment in the same manner as FIG. In the following description, the same reference numerals are assigned to portions common to the first embodiment, and detailed description is omitted. In the ignition part forming system 160 of the present embodiment, the welding apparatus 64 includes a first welding apparatus part 68 and a second welding apparatus part 69. The first welding device portion 68 is disposed at the position P (IV), and the second welding device portion 69 is disposed at the position P (V). A cutting device 65 similar to that of the first embodiment is disposed at the position P (VI). In the present embodiment, the position P (V (VII) is a position for releasing the fixation of the spark plug forming member 110 with respect to the holding jig 70, and the position P (VIII) is from above the holding jig 70. It is a position for collecting the spark plug forming member 110.

  The first welding device portion 68 and the second welding device portion 69 differ in the types of electrode tips that can be provided on the ground electrode forming member 31. For example, the 1st welding apparatus part 68 can be used as the apparatus which welds an electrode tip by resistance welding. The second welding device section 69 temporarily fixes a welding tip having a shape different from that of the first welding device section 68 by resistance welding under a condition different from that of the first welding device section 68, and then It can be set as the apparatus to weld. The number of types of electrode tips that can be formed using the ignition part forming system 160, that is, the number of welding device parts included in the ignition part forming system 160 may be three or more.

  In the present embodiment, the holding jig 70 to be used is predetermined according to the type of the spark plug 100 to be manufactured. And the 1st and 2nd welding apparatus parts identify the holding jig 70 stopped at the position corresponding to the welding apparatus part and aligned with the welding apparatus part, and in the welding apparatus part It is determined whether or not the welding process should be executed. At this time, only when it is determined that the welding process should be performed, the first and second welding apparatus sections perform the welding process on the spark plug forming member 110 that is stopped and aligned at the corresponding position. To do. In addition, the control part which performs the said determination in the 1st and 2nd welding apparatus part may be provided in each welding apparatus part, and may be provided in the control part 66.

  With such a configuration, the position measuring device 63 and the cutting device 65 can be used in common by using the ignition part forming system 160 when manufacturing a plurality of types of spark plugs having different electrode tip configurations. it can. Therefore, the structure of the whole apparatus required in order to manufacture several types of spark plugs can be simplified.

  In the above-described fourth embodiment, whether or not to perform the welding process in the welding apparatus unit is determined based on the identification result of the holding jig 70 in each welding apparatus unit. good. For example, when a predetermined number of spark plugs of a specific type are manufactured together, the operator may input the type of spark plug to be manufactured to the control unit 66 every time the type of spark plug to be manufactured is changed. Good. Then, the control unit 66 outputs position information and jig identification information only to the welding apparatus part to be used, and for the welding apparatus part not to be used, a welding process for the aligned spark plug forming member. What is necessary is just to output the pause signal which does not perform. Alternatively, the number and order of spark plugs to be manufactured are programmed in advance in the control unit 66, and position information and jig identification information or a pause signal are transmitted from the control unit 66 according to the programmed contents. May be output.

  When the types of spark plugs are different, the gap dimension α may be different in addition to the configuration of the electrode tip or instead of the configuration of the electrode tip. When the gap dimension α is different, the distance C shown in FIG. 10 that is referred to when the welding location D is determined in the welding apparatus becomes a different value. In such a case, for example, in the welding apparatus or the control unit 66 that performs the welding process, the value of the distance C is changed based on the jig identification information, and the setting of the welding location D is performed using the changed value of the distance C. Should be done.

  In the above-described configuration, instead of the configuration in which the distance C used for setting the welding location D is changed based on the jig identification information, information regarding the distance C may be attached to each holding jig 70. . That is, a holding jig to be used for each type of spark plug is determined, and in each holding jig, information on the distance C corresponding to the type of spark plug to be manufactured (parameter changed for each type of spark plug) Just add information. As a method of attaching information relating to the parameters, for example, a barcode including the information is attached to the holding jig 70, and each welding apparatus may be provided with a barcode reading device. Alternatively, in each holding jig 70, for example, a memory for storing information by magnetic means may be attached, and in the position measuring device 63, parameter information corresponding to the identified jig may be written in the memory. In this case, in the welding apparatus that performs the welding process, the memory reading means may be provided to read the parameter information from the memory.

  When the welding location D is determined based on the distance C that varies depending on the type of the spark plug, the setting of the cutting location in the cutting device may be changed in the same manner as the setting change of the welding location D described above.

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

L1. Modification 1:
In the first to fourth embodiments, the position measuring device 63 identifies the holding jig 70 and associates the position information with the jig identification information to improve the processing accuracy in each processing apparatus. The jig identification information may not be used. For example, after the position information is acquired by the position measuring device 63, the acquired position information may be sequentially output to each processing device, and the output position information may be sequentially stored in each processing device. And in each processing apparatus, the processing position (welding location D and cutting location) about the spark plug forming member 110 that is stopped and aligned at the position corresponding to the processing device using the oldest stored position information. ) And processing is performed at the calculated position. After the processing, the oldest information may be deleted. By repeating such an operation, the same effect as that of the first embodiment can be obtained without identifying the holding jig 70.

L2. Modification 2:
In the first to fourth embodiments, the holding jig 70 is shared in the position measurement process, the welding process, and the cutting process, and the turntable 61 that is a common transport device is used. However, different configurations may be used. For example, only the position measurement process and the welding process, or only the position measurement process and the cutting process may share the holding jig 70, and the position information acquired in the position measurement process may be used in the subsequent processes. If at least one of the machining steps shares a holding jig with the position measurement process and aligns the holding jig with the measuring device and the machining device, the processing accuracy is increased and ignition occurs. The accuracy of part formation can be improved

L3. Modification 3:
In addition to the welding process and the cutting process, in the gap forming process, the holding jig 70 is shared, and the spark plug forming member 110 is fixed to the holding jig 70 and measured by the position measuring device 63. You may use the position information. Hereinafter, such a configuration will be described as a third modification.

  FIG. 16 is an explanatory diagram showing a schematic configuration of the ignition part forming system 260 of the modification 3 in the same manner as FIG. In the following description, the same reference numerals are assigned to portions common to the first embodiment, and detailed description is omitted. Eight holding jigs 70 can be attached to the turntable 61, and each holding jig 70 can take the position P (I) to the position P (VII). In the present modification, the holding jig 70 is fixed to the disk portion 67 at the position P (I). Then, the spark plug forming member 110 is supplied to the holding jig 70 at the position P (II), and the supplied spark plug forming member 110 is fixed to the holding jig 70 at the position P (III). Is done. At position P (IV), a position measuring step by the position measuring device 63 is performed, at position P (V), a welding step by the welding device 64 is performed, and at position P (VI), a cutting step by the cutting device 65 is performed. Done. At position P (VII), the holding jig 70 to which the spark plug forming member 110 is fixed is removed from the disk portion 67. In the present embodiment, the length in the axis Ax direction of the pedestal portion 73 of the holding portion 70 is formed shorter than in the first to fourth embodiments. Specifically, most of the ground electrode forming member 31 has a shape that protrudes from the pedestal portion 73 in the direction of the axis Ax. This is because the gap forming step can be performed without any trouble on the spark plug forming member 110 that maintains the state fixed to the holding jig 70.

  In the third modified example, the state where the spark plug forming member 110 is fixed to the holding jig 70 is continuously maintained from the position measuring step, and the holding jig is fixed to the gap forming device (temporary bending device and main bending device). 70 is aligned and the spark plug forming member 110 is supplied to the gap forming step. In the present embodiment, a relative positional relationship between a predetermined origin for measuring the position in the position measuring device 63 and a predetermined origin for forming a gap in the gap forming device with respect to the holding jig 70 is as follows. It is decided in advance. Therefore, by positioning the holding jig 70 with respect to the gap forming device, the gap forming step can be executed using the position information obtained in the position measuring step. Specifically, it is possible to accurately recognize the position of the point A on the spark plug forming member 110 using the position information, and based on the recognized position of the point A, the support unit 80 is desired in the temporary bending step. It can be arranged at the position. In the final bending process, the pressing head 82 can be moved by a desired distance. Note that, as in the third embodiment, the holding jig 70 is provided with a position identification unit 75 with a position identification mark 74 and recognizes the position of the point A on the basis of the position of the position identification mark 74. In this case, the accuracy of the gap forming process can be further improved.

  In FIG. 16, instead of fixing the spark plug forming member 110 to the holding jig 70 after fixing the holding jig 70 to the disk portion 67, the holding jig 70 to which the spark plug forming member 110 is fixed in advance is used. It is good also as attaching to the disk part 67. FIG. Further, in the gap forming process, the holding jig 70 is fixed to the disk portion 67 using the common transfer device (turn table 61), similarly to the position measuring process, the welding process, and the cutting process. It is good to do.

  Further, when the gap forming process is performed while maintaining the state where the spark plug forming member 110 is fixed to the holding jig 70, and positional information is also used in the gap forming process, in the gap forming process, the positional deviation between the devices You may perform the process which correct | amends. That is, the positional deviation amount for each holding jig 70 generated in the relative positional relationship between the predetermined origin in the position measuring device 63 and the predetermined origin in the gap forming device with respect to the holding jig 70 is obtained in advance. Just keep it. Then, the position of the origin set in advance by the gap forming device may be corrected based on the amount of positional deviation that occurs between the devices. In order to obtain the positional deviation amount for each holding jig 70, for example, a large number of spark plug forming members 110 that have been subjected to a welding process and a cutting process with high accuracy are prepared in advance for each holding jig 70, and the gap forming process is performed. Run. And about each spark plug 100 which the gap formation process (temporary bending process and this bending process) was complete | finished, gap dimension (alpha) is measured and the average value of deviation | shift between target values is calculated | required. What is necessary is just to let the average value of the said shift | offset | difference calculated | required regarding each process about each holding jig 70 as a correction value in the gap formation process for every holding jig 70. That is, in the gap forming step, the position of the origin of the gap forming device is corrected using the correction value, and the position where the support unit 80 is disposed and the value of the distance G related to the movement of the pressing head 82 may be set.

L4. Modification 4:
The order of the steps shown in FIG. 3 can be variously modified. For example, instead of performing the welding process (step S210) prior to the cutting process (step S220), the cutting process may be performed first. Further, the step of cutting the ground electrode forming member 31 may be performed after the gap forming step (step of bending the ground electrode forming member 31). The state in which the spark plug forming member 110 is fixed to the holding jig 70 is maintained from the position measurement process to the subsequent machining process, and the holding jig of the origin determined by the position measuring device 63 and the origin determined by the processing apparatus is maintained. The relative positional relationship with respect to 70 may be determined in advance. Thereby, using the position information derived by the position measuring device 63, it is possible to ensure the processing accuracy in the subsequent processing step.

L5. Modification 5:
As a transfer device for transferring the spark plug forming member 110 fixed to the holding jig 70 from the position measuring device 63 to another processing device by fixing the holding jig 70, a transfer device other than the turntable 61 is used. May be used. For example, the position measuring device 63 and the processing device are arranged on a straight line, and the holding jig 70 is attached to a transport device including a pedestal that performs a linear motion so that the spark plug forming member 110 can be transported sequentially to these devices. It is good also as fixing. It is only necessary that the holding jig 70 can be fixed and the fixed holding jig 70 can be positioned with sufficient accuracy between the position measuring device 63 and another processing device.

  Further, if the position measuring device 63 and each processing device and the holding jig 70 are aligned with sufficient accuracy, the transport from the position measuring device 63 to each processing device is transported by the turntable 61 or the like. It is good also as conveying manually, without using an apparatus. Also, instead of using a plurality of holding jigs 70, a single holding jig 70 may be used. Also in this case, if the position measurement step and the subsequent processing step are performed while maintaining the state where the spark plug forming member 110 is fixed to the holding jig 70, the measurement result in the position measurement step is used to perform the subsequent steps. By performing the processing step, the same effect of improving the accuracy of the ignition part formation can be obtained.

L6. Modification 6:
In the first to fourth embodiments, the position measurement process is executed for each spark plug forming member 110, and the position information obtained for the spark plug forming member 110 in the process of processing each spark plug forming member 110. However, a different configuration may be used. For example, the individual holding jigs 70 are formed in a uniform shape with sufficient accuracy, and the individual spark plug forming members 110 are held and fixed so that their relative positions with respect to the holding jig 70 are sufficiently uniform. In the case of fixing to the tool 70, the position measuring step may be performed only for one spark plug forming member 110. Then, the obtained position information may be used in the processing steps for the spark plug forming member 110 and all other spark plug forming members that have performed the position measurement. Even in such a configuration, the state in which the spark plug forming member 110 is fixed to the holding jig 70 is maintained, and the displacement of the spark plug forming member 110 during each processing step is suppressed. Therefore, an effect of increasing the accuracy of forming the ignition part is obtained.

DESCRIPTION OF SYMBOLS 3 ... Ceramic resistance 4 ... Sealing body 5 ... Gasket 6, 7 ... Ring member 8 ... Plate packing 9 ... Talc 10 ... Insulator 12 ... Shaft hole 13 ... Leg long part 15 ... Insulator step part 17 ... Tip side trunk | drum 18 ... Rear End side body part 19 ... Central body part 20 ... Center electrode 21 ... Electrode base material 25 ... Core material 30 ... Ground electrode 31 ... Ground electrode forming member 32 ... Electrode tip 40 ... Terminal metal fitting 50 ... Main metal fitting 51 ... Tool engagement part 52 ... Mounting screw part 53 ... Clamping part 54 ... Seal part 56 ... Metal inner step part 57 ... Front end surface 58 ... Compression deformation part 60,260 ... Ignition part forming system 61 ... Turntable 63 ... Position measuring device 64 ... Welding device DESCRIPTION OF SYMBOLS 65 ... Cutting device 66 ... Control part 67 ... Disk part 68 ... 1st welding apparatus part 69 ... 2nd welding apparatus part 70,170 ... Holding jig 71 ... Fixing part 71a ... 1st fixing part 71b ... 2nd fixing Part DESCRIPTION OF SYMBOLS 1c ... Hinge 72 ... Stopper 73 ... Base part 74 ... Position identification mark 75 ... Position identification part 80 ... Support part 81 ... Roller 82 ... Pressing head 100 ... Spark plug 110 ... Spark plug formation member 160 ... Ignition part formation system 200 ... Engine Head 201 ... Mounting screw hole

Claims (22)

(A) a center electrode, an insulator disposed on the outer periphery of the center electrode, a metal shell disposed on the outer periphery of the insulator, one end joined to the metal shell, and the other end of the center electrode A ground electrode forming member for forming the ground electrode and the center electrode, the insulator, and the metal shell, in order to manufacture a spark plug including a ground electrode disposed to face the ground electrode A step of preparing a spark plug forming member having one end thereof joined to the metal shell,
(B) measuring the position of the tip of the center electrode in the spark plug forming member;
(C) cutting the other end of the ground electrode forming member joined to the metal shell, and a spark plug manufacturing method comprising:
The step (b)
(B-1) The spark plug forming member is fixed to a holding jig for holding the spark plug forming member, and the holding jig is aligned with a measuring device for measuring the position. Process,
(B-2) The step of measuring the position of the spark plug forming member fixed to the holding jig aligned with the measuring device using the measuring device;
With
The step (c)
(C-1) After the step (b), the step of aligning the holding jig that maintains the state where the spark plug forming member is fixed with respect to a cutting device for performing the cutting;
(C-2) About the spark plug formation member fixed to the holding jig aligned with the cutting device using the cutting device, based on the result of the step (b-2) Cutting the ground electrode forming member at the determined cutting location;
A method of manufacturing a spark plug, comprising: It is a manufacturing method of the spark plug of Claim 1, Comprising:
In the step (a), a plurality of the spark plug forming members are prepared, and the step (b) and the step (c) are performed for each of the plurality of spark plug forming members using the plurality of holding jigs. In order,
In the step (c-2), for each of the spark plug forming members fixed to each holding jig, based on the measurement result of the position performed in the step (b-2), the cutting location A method for manufacturing a spark plug, characterized in that: A method for producing a spark plug according to claim 2,
The step (b) further includes
(B-3) comprising a step of storing position information obtained by measuring the position in association with the holding jig;
The step (c) further includes:
(C-3) comprising a step of identifying the holding jig prior to the cutting,
In the step (c-2), the cutting location is determined based on the position information stored in the step (b-3) in association with the holding jig identified in the step (c-3). A method for manufacturing a spark plug. It is a manufacturing method of the spark plug of Claim 1, Comprising:
In the step (c-2), when the cutting position of the ground electrode forming member is determined, the measurement when the holding jig is aligned with the measuring device in the step (b-1). A positional relationship between the apparatus and the holding jig, and a positional relationship between the cutting apparatus and the holding jig when the holding jig is aligned with the cutting apparatus in the step (c-1). A method for manufacturing a spark plug, comprising: correcting the cut portion based on a positional deviation between devices representing a deviation between the two. The method of manufacturing a spark plug according to claim 1 or 4, further comprising:
(D) comprising a step of welding an electrode tip to the other end of the ground electrode forming member after at least the step (b);
The step (d)
(D-1) aligning the holding jig that maintains the state where the spark plug forming member is fixed with respect to a welding apparatus for welding the electrode tip;
(D-2) About the spark plug forming member fixed to the holding jig aligned with the welding apparatus using the welding apparatus, based on the result of the step (b-2). A step of welding the electrode tip at the determined welding location;
A method of manufacturing a spark plug, comprising: It is a manufacturing method of the spark plug according to claim 5,
In the step (a), a plurality of the spark plug forming members are prepared, and the step (b) and the step (c) are performed for each of the plurality of spark plug forming members using the plurality of holding jigs. And (d) steps are performed in a predetermined order,
In the step (d-2), for each of the spark plug forming members fixed to each holding jig, the welding location is determined based on the measurement result of the position performed in the step (b-2). A method for manufacturing a spark plug, characterized in that: It is a manufacturing method of the spark plug of Claim 6, Comprising:
The step (b) further includes
(B-3) comprising a step of storing position information obtained by measuring the position in association with the holding jig;
The step (d) further includes
(D-3) comprising the step of identifying the holding jig prior to welding of the electrode tip,
In the step (d-2), the welding location is determined based on the position information stored in the step (b-3) in association with the holding jig identified in the step (d-3). A method for manufacturing a spark plug. It is a manufacturing method of the spark plug according to claim 5,
In the step (d-2), when the welding location of the electrode tip is determined, the measurement device when the holding jig is aligned with the measurement device in the step (b-1) The positional relationship between the holding jig and the positional relationship between the welding apparatus and the holding jig when the holding jig is aligned with respect to the welding apparatus in the step (d-1). A method for manufacturing a spark plug, characterized in that the welding point is corrected on the basis of a positional shift between devices representing a shift between the two. (A) a center electrode, an insulator disposed on the outer periphery of the center electrode, a metal shell disposed on the outer periphery of the insulator, one end joined to the metal shell, and the other end of the center electrode A ground electrode forming member for forming the ground electrode and the center electrode, the insulator, and the metal shell, in order to manufacture a spark plug including a ground electrode disposed to face the ground electrode A step of preparing a spark plug forming member having one end thereof joined to the metal shell,
(B) measuring the position of the tip of the center electrode in the spark plug forming member;
(D) a step of welding an electrode tip to the other end portion of the ground electrode forming member joined to the metal shell, and a spark plug manufacturing method comprising:
The step (b)
(B-1) The spark plug forming member is fixed to a holding jig for holding the spark plug forming member, and the holding jig is aligned with a measuring device for measuring the position. Process,
(B-2) The step of measuring the position of the spark plug forming member fixed to the holding jig aligned with the measuring device using the measuring device;
With
The step (d)
(D-1) After the step (b), the step of aligning the holding jig that maintains the state in which the spark plug forming member is fixed with respect to a welding apparatus for welding the electrode tip When,
(D-2) About the spark plug forming member fixed to the holding jig aligned with the welding apparatus using the welding apparatus, based on the result of the step (b-2). A step of welding the electrode tip at the determined welding location;
A method of manufacturing a spark plug, comprising: A spark plug manufacturing method according to claim 9,
In the step (a), a plurality of the spark plug forming members are prepared, and the step (b) and the step (d) are performed for each of the plurality of spark plug forming members using the plurality of holding jigs. In order,
In the step (d-2), for each of the spark plug forming members fixed to each holding jig, the welding location is determined based on the measurement result of the position performed in the step (b-2). A method for manufacturing a spark plug, characterized in that: It is a manufacturing method of the spark plug according to claim 10,
The step (b) further includes
(B-3) comprising a step of storing position information obtained by measuring the position in association with the holding jig;
The step (d) further includes
(D-3) comprising the step of identifying the holding jig prior to welding of the electrode tip,
In the step (d-2), the welding location is determined based on the position information stored in the step (b-3) in association with the holding jig identified in the step (d-3). A method for manufacturing a spark plug. A spark plug manufacturing method according to claim 9,
In the step (d-2), when the welding location of the electrode tip is determined, the measurement device when the holding jig is aligned with the measurement device in the step (b-1) The positional relationship between the holding jig and the positional relationship between the welding apparatus and the holding jig when the holding jig is aligned with respect to the welding apparatus in the step (d-1). A method for manufacturing a spark plug, characterized in that the welding point is corrected on the basis of a positional shift between devices representing a shift between the two. The method for manufacturing a spark plug according to claim 9 or 12, further comprising:
(C) including a step of cutting the other end side of the ground electrode forming member after at least the step (b);
The step (c)
(C-1) aligning the holding jig that maintains the state in which the spark plug forming member is fixed with respect to a cutting device for cutting the ground electrode forming member;
(C-2) About the spark plug formation member fixed to the holding jig aligned with the cutting device using the cutting device, based on the result of the step (b-2) Cutting the ground electrode forming member at the determined cutting location;
A method of manufacturing a spark plug, comprising: It is a manufacturing method of the spark plug according to claim 13,
In the step (a), a plurality of the spark plug forming members are prepared, and the step (b) and the step (c) are performed for each of the plurality of spark plug forming members using the plurality of holding jigs. And (d) steps are performed in a predetermined order,
In the step (c-2), for each of the spark plug forming members fixed to each holding jig, based on the measurement result of the position performed in the step (b-2), the cutting location A method for manufacturing a spark plug, characterized in that: A method for producing a spark plug according to claim 14,
The step (b) further includes
(B-3) comprising a step of storing position information obtained by measuring the position in association with the holding jig;
The step (c) further includes:
(C-3) comprising a step of identifying the holding jig prior to the cutting,
In the step (c-2), the cutting location is determined based on the position information stored in the step (b-3) in association with the holding jig identified in the step (c-3). A method for manufacturing a spark plug. It is a manufacturing method of the spark plug according to claim 13,
In the step (c-2), when the cutting position of the ground electrode forming member is determined, the measurement when the holding jig is aligned with the measuring device in the step (b-1). A positional relationship between the apparatus and the holding jig, and a positional relationship between the cutting apparatus and the holding jig when the holding jig is aligned with the cutting apparatus in the step (c-1). A method for manufacturing a spark plug, comprising: correcting the cut portion based on a positional deviation between devices representing a deviation between the two. A spark plug manufacturing method according to any one of claims 5 to 8 and claims 13 to 16,
A method of manufacturing a spark plug, comprising: performing a step of cutting the other end portion of the ground electrode forming member after performing a step of welding an electrode tip to the other end portion of the ground electrode forming member. A method for manufacturing a spark plug according to any one of claims 5 to 17,
The welding device is a device capable of providing a plurality of types of electrode tips, and includes a plurality of welding device portions that perform welding of the electrode tips under different conditions corresponding to the types of the electrode tips to be provided. ,
In the step of aligning the holding jig to which the spark plug forming member is fixed with respect to the welding apparatus, the holding jig is aligned with respect to the welding apparatus portion corresponding to the type of electrode tip to be provided. A method for manufacturing a spark plug. A spark plug manufacturing method according to any one of claims 1 to 8 and claims 13 to 17, further comprising:
(E) after the step of cutting the other end side of the ground electrode forming member, comprising a gap forming step of bending the ground electrode forming member,
The step (e)
(E-1) aligning the holding jig that maintains the state in which the spark plug forming member is fixed with respect to a gap forming device for bending the ground electrode forming member;
(E-2) The spark plug forming member fixed to the holding jig aligned with the gap forming device using the gap forming device is determined based on the position measurement result. A step of performing the bending process under the gap forming conditions,
A method for producing a spark plug, comprising: A spark plug manufacturing method according to any one of claims 5 to 17, further comprising:
(E) comprising a gap forming step of bending the ground electrode forming member after the step of welding the electrode tip to the other end of the ground electrode forming member;
The step (e)
(E-1) aligning the holding jig that maintains the state in which the spark plug forming member is fixed with respect to a gap forming device for bending the ground electrode forming member;
(E-2) The spark plug forming member fixed to the holding jig aligned with the gap forming device using the gap forming device is determined based on the position measurement result. A step of performing the bending process under the gap forming conditions,
A method for producing a spark plug, comprising: A method for producing a spark plug according to claim 19 or 20,
The gap forming device includes a support portion that serves as a fulcrum when the ground electrode forming member is bent, and a pressing portion that applies a pressing force for bending the ground electrode forming member with the support portion as a fulcrum. With
The gap formation condition includes a position of the support part,
The step (e-2) is a step of moving the support portion to a position determined based on the result of the position measurement prior to the step of pressing the ground electrode forming member using the pressing portion. A method for manufacturing a spark plug.   A spark plug manufactured by the method for manufacturing a spark plug according to any one of claims 1 to 21.

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