DE102015100511A1 - Method for producing a metal housing, method for producing a spark plug, and apparatus for producing a metal housing - Google Patents

Abstract

A method of manufacturing a metal casing (50) for use in a spark plug having a straight ground electrode, comprising: an attaching step of covering a ground electrode (30) with a heat shrinkable member (90) such that the ground electrode (30) of FIG its proximal end portion (33) is covered to its distal end portion (35); a heat-shrinking step in which the heat-shrinkable member is shrunk gradually from the side at the proximal end portion (33) to the side at the distal end portion (35) by heating the heat-shrinkable member (90) by means of a heat source after the attaching step; and a plating step in which a surface of the metal shell (50) is coated after the heat-shrinking step.

Description

Technical area

 The present invention relates to a technique for producing a spark plug.

State of the art

A metal case used for a spark plug is generally formed of an iron-based material such as carbon steel, and a zinc plating layer may be formed on the surface of the metal case to prevent its corrosion. If a plating layer is formed not only on the metal case but also on a ground electrode mounted on the metal case, various problems arise. For example, when a noble metal tip is welded to the ground electrode, a weld defect may occur. When the ground electrode is bent, the plating layer may peel off, and a detached portion of the plating layer then comes into contact with the center electrode, resulting in a failure to generate a spark discharge. There is known a technique which solves these problems by preventing the formation of the plating layer on the ground electrode (for example, Patent Document 1). According to this technique, the ground electrode is covered by a rubber tube or the like to prevent the ground electrode from coming in contact with a plating solution.

Patent document

• Patent Document 1: Japanese Patent Laid-Open (kokai) No. 2001-68250

Brief description of the invention

In general, a rubber tube or the like which can be heat-shrunk is used; that is, a heat-shrinkable element is used. The ground electrode is covered by the heat-shrinkable member, and the heat-shrinkable member is caused to shrink, thereby preventing contact between the ground electrode and a plating solution. However, when the heat-shrinkable member is caused to shrink, a gap may be generated between the heat-shrinkable member and the ground electrode, or the heat-shrinkable member may not uniformly shrink in the circumferential direction. In such a case, when a plating layer is formed on the metal shell, the ground electrode comes into contact with the plating solution, which may cause a plating layer to be formed in a large area of the ground electrode.

• (1) Nach einer Art der vorliegenden Erfindung wird ein Verfahren zur Herstellung eines Metallgehäuses, der bei einer Zündkerze verwendet wird und eine gerade verlaufende Masseelektrode aufweist, bereitgestellt. Das Verfahren umfasst einen Anbringungsschritt, um die Masseelektrode so durch ein wärmeschrumpfbares Element abzudecken, dass die Masseelektrode von ihrem proximalen Endabschnitt bis zu ihrem distalen Endabschnitt bedeckt ist; einen Wärmeschrumpfungsschritt, um das wärmeschrumpfbare Element nach dem Anbringungsschritt durch Erhitzen des wärmeschrumpfbaren Elements mittels einer Wärmequelle schrittweise von einer Seite an dem proximalen Endabschnitt zu einer Seite an dem distalen Endabschnitt schrumpfen zu lassen; und einen Plattierungsschritt, um eine Oberfläche des Metallgehäuses nach dem Wärmeschrumpfungsschritt zu überziehen. Nach dieser Art wird das wärmeschrumpfbare Element schrittweise von der Seite an dem proximalen Ende zu der Seite an dem distalen Ende zum Schrumpfen gebracht, wodurch ein Teil des wärmeschrumpfbaren Elements an der Seite des proximalen Endes in einen engen Kontakt mit der Masseelektrode gelangt, bevor ein Teil des wärmeschrumpfbaren Elements an der Seite des distalen Endes in einen engen Kontakt mit der Masseelektrode gelangt. Daher kann der Bereich, in dem ein Teil der Masseelektrode an der Seite an dem proximalen Endabschnitt (der Seite des proximalen Endabschnitts) nicht durch das wärmeschrumpfbare Element abgedeckt ist, (der Bereich, in dem die Masseelektrode frei liegt) auf einen bestimmten Bereich beschränkt werden.
• (2) Bei dem Verfahren zur Herstellung eines Metallgehäuses der oben beschriebenen Art kann der Wärmeschrumpfungsschritt einen Schritt umfassen, um das wärmeschrumpfbare Element durch direktes Aufbringen eines heißen Gases, das aus einer als Wärmequelle dienenden Düse geblasen wird, auf das wärmeschrumpfbare Element zu erhitzen, und das wärmeschrumpfbare Element durch Reflektieren des heißen Gases, das aus der Düse geblasen wurde, mittels einer Reflexionsplatte, die an einer Position, welche der Düse in Bezug auf die Masseelektrode gegenüberliegt, angeordnet ist, und Aufbringen des reflektierten heißen Gases auf das wärmeschrumpfbare Element zu erhitzen. Gemäß dieser Art wird das heiße Gas durch die Reflexionsplatte reflektiert und das reflektierte, heiße Gas wird auf das wärmeschrumpfbare Element aufgebracht, wodurch das wärmeschrumpfbare Element in der Umfangsrichtung über seinen gesamten Umfang hinweg gleichmäßiger wärmegeschrumpft werden kann.
• (3) Bei dem Verfahren zur Herstellung eines Metallgehäuses der oben beschriebenen Art kann der Wärmeschrumpfungsschritt durchgeführt werden, indem das Metallgehäuse so bewegt wird, dass das Metallgehäuse der Reihe nach an verschiedenen Arbeitspositionen angeordnet wird, und ein Teil des wärmeschrumpfbaren Elements, der durch die Wärmequelle erhitzt wird, mit jeder Bewegung des Metallgehäuses zu einer anderen der Arbeitspositionen um ein bestimmtes Ausmaß von der Seite an dem proximalen Endabschnitt zu der Seite an dem distalen Endabschnitt (der Seite des distalen Endabschnitts) bewegt wird. Nach dieser Art kann die Zeit, die nötig ist, um das wärmeschrumpfbare Element an jeder der verschiedenen Arbeitspositionen zu schrumpfen, verglichen mit dem Fall, in dem das wärmeschrumpfbare Element an einer einzelnen Arbeitsposition geschrumpft wird, verkürzt werden. Daher kann die Zeit, die nötig ist, um dem Wärmeschrumpfungsschritt an einer einzelnen Arbeitsposition durchzuführen, verkürzt werden, wodurch die Leistungsfähigkeit der Herstellung des Metallgehäuses gesteigert werden kann.
• (4) Bei dem Verfahren zur Herstellung eines Metallgehäuses der oben beschriebenen Art können mehrere Wärmequellen bereitgestellt und an unterschiedlichen Positionen fixiert sein. Nach dieser Art sind die Wärmequellen fixiert. Daher kann durch jede Wärmequelle ein bestimmter Bereich des wärmeschrumpfbaren Elements fehlerfrei wärmegeschrumpft werden.
• (5) Bei dem Verfahren zur Herstellung eines Metallgehäuses der oben beschriebenen Art kann das wärmeschrumpfbare Element eine Öffnung aufweisen, die sich in einem Zustand, in dem das wärmeschrumpfbare Element die Masseelektrode bedeckt, an der Seite an dem distalen Endabschnitt befindet; und der Wärmeschrumpfungsschritt kann einen Schritt umfassen, bei dem ein Gas, das innerhalb des wärmeschrumpfbaren Elements vorhanden ist, durch die Öffnung abgegeben wird. Nach dieser Art wird ein Gas davon abgehalten, von der Seite an dem proximalen Endabschnitt nach außerhalb des wärmeschrumpfbaren Elements zu entweichen. Daher ist es möglich, noch verlässlicher zu verursachen, dass ein Teil des wärmeschrumpfbaren Elements an der Seite an dem proximalen Endabschnitt in einen engen Kontakt mit der Masseelektrode gelangt, bevor ein Teil des wärmeschrumpfbaren Elements an der Seite an dem distalen Endabschnitt in einen engen Kontakt mit der Masseelektrode gelangt. Das heißt, da das Schrumpfen des wärmeschrumpfbaren Elements stabil durchgeführt wird, ist es möglich, den Bereich, in dem ein Teil der Masseelektrode an der Seite an dem proximalen Endabschnitt nicht durch das wärmeschrumpfbare Element abgedeckt ist (den Bereich, in dem die Masseelektrode frei liegt), noch genauer auf einen bestimmten Bereich zu beschränken. Da das Gas nach außerhalb des wärmeschrumpfbaren Elements abgegeben wird, kann außerdem der Grad des engen Kontakts zwischen dem wärmeschrumpfbaren Element und der Masseelektrode erhöht werden.
• (6) Das Verfahren zur Herstellung eines Metallgehäuses nach der oben beschriebenen Art kann ferner einen Kühlschritt umfassen, der zwischen dem Wärmeschrumpfungsschritt und dem Plattierungsschritt durchgeführt wird, um ein Kühlgas auf wenigstens das wärmeschrumpfbare Element, das an der Masseelektrode des Metallgehäuses angebracht ist, aufzubringen. Im Allgemeinen wird der Plattierungsschritt an einem Ort durchgeführt, der sich von dem Ort der Durchführung des Wärmeschrumpfungsschritts unterscheidet. Daher muss das Metallgehäuse zwischen diesen Orten bewegt werden. Nach dieser Art ist zwischen dem Wärmeschrumpfungsschritt und dem Plattierungsschritt der Kühlschritt bereitgestellt. Daher kann die Aushärtung des wärmeschrumpfbaren Elements durch den Kühlschritt beschleunigt werden, bevor das Metallgehäuse bewegt wird, um den Plattierungsschritt durchzuführen. Als Ergebnis ist es möglich, die Wahrscheinlichkeit einer Positionsverschiebung des wärmeschrumpfbaren Elements, die in einer Situation, in der sich die Stellung des Metallgehäuses zum Beispiel bei seiner Bewegung verändert, oder in einer Situation, in der eine externe Kraft auf das Metallgehäuse wirkt, auftritt, zu verringern. Das heißt, da das Schrumpfen des wärmeschrumpfbaren Elements aufgrund der Bereitstellung des Kühlschritts stabil durchgeführt wird, kann der Bereich, in dem ein Teil der Masseelektrode an der Seite an dem proximalen Endabschnitt nicht von dem wärmeschrumpfbaren Element bedeckt ist (der Bereich, in dem die Masseelektrode frei liegt), mit einer noch höheren Genauigkeit auf einen bestimmten Bereich beschränkt werden. Außerdem kann durch das Kühlen des erhitzten wärmeschrumpfbaren Elements mittels des Kühlschritts die Aushärtung des wärmeschrumpfbaren Elements, das durch den Wärmeschrumpfungsschritt erhitzt wurde, beschleunigt werden. Als Ergebnis kann die Wahrscheinlichkeit eines Bruchs des wärmeschrumpfbaren Elements verringert werden.
• (7) Bei dem Verfahren zur Herstellung eines Metallgehäuses der oben beschriebenen Art kann der Kühlschritt durchgeführt werden, indem das Metallgehäuse so bewegt wird, dass das Metallgehäuse der Reihe nach an verschiedenen Arbeitspositionen angeordnet wird, und das Kühlgas mit jeder Bewegung des Metallgehäuses zu einer anderen der Arbeitspositionen auf das Metallgehäuse aufgebracht wird. Nach dieser Art kann die Zeit, die nötig ist, um das Metallgehäuse an jeder der verschiedenen Arbeitspositionen zu kühlen, verglichen mit dem Fall, in dem das Metallgehäuse an einer einzelnen Arbeitsposition gekühlt wird, verkürzt werden. Daher kann die Zeit, die nötig ist, um den Kühlschritt an einer einzelnen Arbeitsposition durchzuführen, verkürzt werden, wodurch die Leistungsfähigkeit der Herstellung des Metallgehäuses gesteigert werden kann.
• (8) Bei dem Verfahren zur Herstellung eines Metallgehäuses der oben beschriebenen Art kann das Kühlgas aus mehreren Düsen geblasen werden. Nach dieser Art wird das Kühlgas aus mehreren Düsen geblasen. Daher ist es möglich, die Wahrscheinlichkeit einer ungleichmäßigen Kühlung von Elementen, die gekühlt werden sollen, wie etwa des wärmeschrumpfbaren Elements, zu verringern.
• (9) Bei dem Verfahren zur Herstellung eines Metallgehäuses der oben beschriebenen Art kann der Wärmeschrumpfungsschritt in einem Zustand durchgeführt werden, in dem das Metallgehäuse durch ein Halteelement gehalten wird; und der Kühlschritt kann einen Schritt des Aufbringens des Kühlgases auf das Halteelement und das Metallgehäuse umfassen, womit die Masseelektrode verbunden ist,. Nach dieser Art kann das Kühlen des Metallgehäuses und des Halteelements beschleunigt werden. Daher ist es möglich, eine Verschlechterung des Metallgehäuses und des Halteelements zu beschränken, die verursacht wird, indem diese einer Hochtemperaturumgebung ausgesetzt werden.
• (10) Nach einer anderen Art der vorliegenden Erfindung wird ein Verfahren zur Herstellung einer Zündkerze bereitgestellt. Das Verfahren umfasst einen Mittelelektrodenanordnungsschritt, wobei eine Mittelelektrode in einer axialen Öffnung eines Isolators angeordnet wird, einen Mantelherstellungsschritt, wobei das Metallgehäuse unter Verwendung des Metallgehäuseherstellungsverfahrens nach dem oben beschriebenen Verfahren hergestellt wird, einen Isolatoranordnungsschritt, wobei der Isolator im Inneren des Metallgehäuses angeordnet wird, und einen Biegeschritt, wobei die Masseelektrode so gebogen wird, dass die Mittelelektrode und der vordere Endabschnitt der Masseelektrode zueinander gewandt sind. Nach dieser Art kann der Spalt zwischen dem wärmeschrumpfbaren Element und dem proximalen Endabschnitt so beschränkt werden, dass er in einen vorherbestimmten Bereich fällt. Daher ist es möglich, eine Zündkerze herzustellen, bei der der Bereich der Plattierung, der auf die Masseelektrode aufgebracht ist, beschränkt ist.
• (11) Nach einer anderen Art der vorliegenden Erfindung wird eine Vorrichtung zur Herstellung eines Metallgehäuses, der bei einer Zündkerze verwendet wird und eine gerade verlaufende Masseelektrode aufweist, bereitgestellt. Die Vorrichtung umfasst Anbringungsmittel, um die Masseelektrode durch ein wärmeschrumpfbares Element so abzudecken, dass die Masseelektrode von ihrem proximalen Endabschnitt zu ihrem distalen Endabschnitt bedeckt ist; und Wärmeschrumpfungsmittel, um das wärmeschrumpfbare Element durch Erhitzen des wärmeschrumpfbaren Elements mittels einer Wärmequelle schrittweise von einer Seite an dem proximalen Endabschnitt zu einer Seite an dem distalen Endabschnitt schrumpfen zu lassen. Nach dieser Art wird ein heißes Gas durch die Reflexionsplatte reflektiert und das reflektierte heiße Gas auf das wärmeschrumpfbare Element aufgebracht, wodurch das wärmeschrumpfbare Element in der Umfangsrichtung über seinen gesamten Umfang hinweg gleichmäßiger wärmegeschrumpft werden kann. Nach dieser Art kann der Spalt zwischen dem wärmeschrumpfbaren Element und dem proximalen Endabschnitt durch das wärmeschrumpfbare Element so beschränkt werden, dass er in einen vorherbestimmten Bereich fällt.

The present invention has been made to solve the above-described problems, and can be carried out in the following manners or embodiments.

• (1) According to one mode of the present invention, there is provided a method of manufacturing a metal case used in a spark plug and having a straight earth electrode. The method includes an attaching step of covering the ground electrode with a heat-shrinkable member such that the ground electrode is covered from its proximal end portion to its distal end portion; a heat-shrinking step of shrinking the heat-shrinkable member after the attaching step by heating the heat-shrinkable member by a heat source stepwise from a side at the proximal end portion to a side at the distal end portion; and a plating step of coating a surface of the metal shell after the heat-shrinking step. According to this manner, the heat-shrinkable member is gradually shrinked from the side at the proximal end to the side at the distal end, whereby a part of the heat-shrinkable member at the proximal end side comes into close contact with the ground electrode before a part of the heat-shrinkable member on the side of the distal end comes into close contact with the ground electrode. Therefore, the area where a part of the ground electrode on the side at the proximal end portion (the proximal end portion side) is not covered by the heat-shrinkable member (the area where the ground electrode is exposed) can be restricted to a certain range ,
• (2) In the method of manufacturing a metal shell of the type described above, the heat-shrinking step may include a step of heating the heat-shrinkable member by directly applying a hot gas blown from a nozzle serving as a heat source to the heat-shrinkable member the heat-shrinkable member is heated by reflecting the hot gas blown from the nozzle by means of a reflection plate disposed at a position facing the nozzle with respect to the ground electrode and applying the reflected hot gas to the heat-shrinkable member , According to this type, the hot gas is reflected by the reflection plate, and the reflected hot gas is applied to the heat-shrinkable element applied, whereby the heat-shrinkable element in the circumferential direction can be uniformly heat-shrunk over its entire circumference.
• (3) In the method of manufacturing a metal shell of the type described above, the heat-shrinking step can be performed by moving the metal shell so that the metal shell is sequentially placed at different working positions, and a part of the heat-shrinkable member by the heat source is heated, with each movement of the metal housing to another of the working positions is moved by a certain extent from the side at the proximal end portion to the side at the distal end portion (the side of the distal end portion). According to this manner, the time required to shrink the heat-shrinkable member at each of the various working positions can be shortened as compared with the case where the heat-shrinkable member is shrunk at a single working position. Therefore, the time required to perform the heat-shrinking step at a single working position can be shortened, whereby the performance of manufacturing the metal shell can be increased.
• (4) In the method of manufacturing a metal shell of the type described above, a plurality of heat sources may be provided and fixed at different positions. After this type, the heat sources are fixed. Therefore, each heat source can heat-shrink a certain portion of the heat-shrinkable member without fail.
• (5) In the method of manufacturing a metal shell of the type described above, the heat-shrinkable member may have an opening located on the side at the distal end portion in a state where the heat-shrinkable member covers the ground electrode; and the heat-shrinking step may include a step of discharging a gas existing inside the heat-shrinkable member through the opening. According to this manner, a gas is prevented from escaping from the side at the proximal end portion to the outside of the heat-shrinkable member. Therefore, it is possible to even more reliably cause a part of the heat-shrinkable member on the proximal end portion side to come into close contact with the ground electrode before a part of the heat-shrinkable member on the side at the distal end portion is in close contact the ground electrode passes. That is, since the shrinkage of the heat-shrinkable member is stably performed, it is possible to cover the area where a part of the ground electrode on the side at the proximal end portion is not covered by the heat-shrinkable member (the area where the ground electrode is exposed ), to restrict even more to a specific area. In addition, since the gas is discharged outside the heat-shrinkable member, the degree of close contact between the heat-shrinkable member and the ground electrode can be increased.
• (6) The method of manufacturing a metal shell of the type described above may further comprise a cooling step performed between the heat-shrinking step and the plating step to apply a cooling gas to at least the heat-shrinkable member attached to the ground electrode of the metal shell. In general, the plating step is performed at a location different from the location of performing the heat-shrinking step. Therefore, the metal housing must be moved between these locations. According to this manner, between the heat-shrinking step and the plating step, the cooling step is provided. Therefore, the curing of the heat-shrinkable member can be accelerated by the cooling step before the metal housing is moved to perform the plating step. As a result, it is possible to occur the likelihood of a positional shift of the heat-shrinkable member that changes in a situation where the position of the metal shell changes as it moves, or in a situation where an external force acts on the metal shell, to reduce. That is, since the shrinkage of the heat-shrinkable member is stably performed due to the provision of the cooling step, the portion where a part of the ground electrode on the side at the proximal end portion is not covered by the heat-shrinkable member (the portion where the ground electrode is free), with even greater accuracy limited to a particular range. In addition, by cooling the heated heat-shrinkable member by means of the cooling step, the curing of the heat-shrinkable member heated by the heat-shrinking step can be accelerated. As a result, the probability of breakage of the heat-shrinkable member can be reduced.
• (7) In the method of manufacturing a metal shell of the type described above, the cooling step may be performed by moving the metal shell so that the metal shell is sequentially placed at different working positions and the cooling gas moves to each other with each movement of the metal shell the working positions is applied to the metal housing. According to this manner, the time required to cool the metal shell at each of the various working positions can be shortened as compared with the case where the metal shell is cooled at a single working position. Therefore, the time required to perform the cooling step at a single working position can be shortened, whereby the performance of manufacturing the metal case can be increased.
• (8) In the method of manufacturing a metal shell of the type described above, the cooling gas may be blown from a plurality of nozzles. After this way, the cooling gas is blown out of several nozzles. Therefore, it is possible to reduce the likelihood of uneven cooling of elements to be cooled, such as the heat-shrinkable element.
• (9) In the method of manufacturing a metal shell of the type described above, the heat-shrinking step may be performed in a state where the metal shell is held by a retaining member; and the cooling step may include a step of applying the cooling gas to the support member and the metal shell to which the ground electrode is connected. In this way, the cooling of the metal housing and the holding member can be accelerated. Therefore, it is possible to restrain deterioration of the metal case and the holding member caused by subjecting them to a high-temperature environment.
• (10) According to another mode of the present invention, a method of manufacturing a spark plug is provided. The method comprises a center electrode arranging step, wherein a center electrode is disposed in an axial opening of an insulator, a cladding manufacturing step, wherein the metal shell is manufactured by using the metal shell manufacturing method according to the above-described method, an insulator arranging step, wherein the insulator is disposed inside the metal shell, and a bending step, wherein the ground electrode is bent so that the center electrode and the front end portion of the ground electrode face each other. According to this manner, the gap between the heat-shrinkable member and the proximal end portion can be restricted to fall within a predetermined range. Therefore, it is possible to manufacture a spark plug in which the area of plating applied to the ground electrode is limited.
• (11) According to another mode of the present invention, there is provided an apparatus for manufacturing a metal case used in a spark plug and having a straight earth electrode. The apparatus includes attachment means for covering the ground electrode with a heat-shrinkable member such that the ground electrode is covered by its proximal end portion to its distal end portion; and heat-shrinkage means for shrinking the heat-shrinkable member by heating the heat-shrinkable member by a heat source gradually from one side at the proximal end portion to a side at the distal end portion. According to this manner, a hot gas is reflected by the reflection plate and the reflected hot gas is applied to the heat-shrinkable element, whereby the heat-shrinkable element can be more uniformly heat shrunk in the circumferential direction over its entire circumference. According to this manner, the gap between the heat-shrinkable member and the proximal end portion can be restricted by the heat-shrinkable member to fall within a predetermined range.

 The present invention can be embodied in various ways. For example, the present invention may be embodied in the manner of a method of manufacturing a metal housing, such as a method of manufacturing a spark plug, and a device for manufacturing a metal housing. In addition, the present invention may be embodied in the manner of a program for executing the metal shell manufacturing method or the spark plug manufacturing method, such as a metal shell or a spark plug manufactured using these manufacturing methods, and an ignition system including such a spark plug ,

Brief description of the drawings

1 Fig. 16 is a partially sectional view showing a spark plug according to an embodiment of the present invention.

2 Fig. 10 is a flowchart showing a method of manufacturing the spark plug.

3 Fig. 10 is a flowchart showing the details of a metal shell manufacturing step.

4 Figure 11 illustrates views used to describe a heat-shrinking step.

5 Fig. 13 is a view used to describe the details of a cooling step.

6 Fig. 13 is a view used to describe a heat-shrinking step which is a comparative example.

7 Fig. 13 is a view used to describe a metal case manufacturing apparatus used in a second embodiment.

8th Fig. 13 is a view used to describe the details of the heat-shrinking step.

Ways of carrying out the invention

A. First Embodiment and Comparative Example

1 is a partially sectioned view showing a spark plug 100 according to an embodiment of the present invention. Now it is in 1 a direction (also referred to as the "axis direction") CLD along the axis line CL of the spark plug 100 the vertical direction. In addition, in 1 the bottom side of the sheet of the drawing as the front side FS of the spark plug 100 and the upper side of the sheet are referred to as the back side BS of the spark plug.

As in 1 shown includes the spark plug 100 an insulator 10 , a metal case 50 , a center electrode 20 , a metallic clamp element 40 and a ground electrode 30 ,

The insulator 10 is formed by firing alumina or the like. The insulator 10 is a tubular member with an axial opening 12 extending in the axial direction CLD. The insulator 10 is so around the center electrode 20 provided around that insulator 10 the center electrode 20 in the axial opening 12 holds. The insulator 10 has a flange portion 19 which has the largest diameter and CLD in the axial direction approximately in the middle of the insulator 10 is formed. In addition, the insulator points 10 a rear fuselage section 18 on, in relation to the flange section 19 at the back BS (the upper side in 1 ) is formed. In addition, the insulator points 10 a front fuselage section 17 on, in relation to the flange section 19 is formed on the front side FS and has an outer diameter smaller than that of the rear fuselage section 18 is. Furthermore, the insulator has 10 a leg section 13 on that in relation to the front fuselage section 17 is formed on the front side FS and has an outer diameter smaller than that of the front fuselage section 17 is. The outer diameter of the leg section 13 decreases to its front end. If the spark plug 100 on a motor head 600 an internal combustion engine is mounted, is the leg portion 13 free to a combustion chamber. In the axial direction CLD is seen between the leg portion 13 and the front fuselage section 17 a step section 15 educated.

The metal case 50 is a cylindrical tubular metal member formed of low carbon steel. On the surface of the metal housing 50 For example, a plating layer such as a zinc plating layer or a nickel plating layer is formed. The metal case 50 is used to the spark plug 100 on the engine head 600 to fix the internal combustion engine. The metal case 50 is around the insulator 10 provided around and holds the insulator 10 , In particular, a section of the insulator 10 which is part of the rear hull section 18 , the flange section 19 , the front fuselage section 17 and the leg portion 13 corresponds, from the metal case 50 surround.

The metal case 50 has a tool engaging portion 51 and a mounting screw portion 52 on. The tool engaging section 51 is a portion with which a spark plug wrench (not shown) is engaged. The attachment screw section 52 of the metal housing 50 is a section with a screw thread and comes with a mounting screw hole 601 of the engine head 600 , which is provided at the upper portion of the internal combustion engine, brought into a threaded engagement.

Between the tool engaging section 51 and the attachment screw portion 52 of the metal housing 50 is a flange-shaped sealing portion 54 educated. Between the attachment screw section 52 and the sealing portion 54 is an annular seal 5 , which is formed by folding a plate member used. The seal 5 is pressed and deformed when the spark plug 100 on the engine head 600 is attached. As a result of deformation of the gasket 5 will be between the spark plug 100 and the engine head 600 made a seal, whereby a leakage of a gas from the interior of the engine through the Anschraungsschrauböffnung 601 is prevented.

The metal case 50 has a crimping section 53 in relation to the tool engaging portion 51 is provided at the back BS. Between the outer peripheral surface of the rear fuselage section 18 of the insulator 10 and a portion of the inner peripheral surface of the metal shell 50 which portion extends from the tool engaging portion 51 to the crimping section 53 extends, are circular ring elements 6 and 7 inserted. Between the two ring elements 6 . 7 is talcum powder 9 filled. When the crimping is performed, the crimping section 53 to turn inwards, becomes the insulator 10 in the metal case 50 over the ring elements 6 . 7 and the talk 9 pressed to the front FS. As a result, the step section becomes 15 of the insulator 10 through a step section 56 attached to the inner circumference of the metal housing 50 is formed, held, and become the metal case 50 and the insulator 10 united together. The gas tightness between the metal housing 50 and the insulator 10 through an annular sheet metal gasket 8th between the step section 15 of the insulator 10 and the step section 56 of the metal housing 50 is inserted, whereby leakage of combustion gas is prevented.

The center electrode 20 is a rod-shaped member extending in the axial direction CLD. The center electrode 20 is made of nickel or an alloy containing nickel as a main component. A front electrode end section 21 the center electrode 20 , which is located on the front FS, towers over the insulator 10 outward. The center electrode 20 extends in the axial opening 12 to the rear and is by sealing elements 4 and a ceramic resistor 3 electrically to the metallic terminal element 40 connected. A high voltage cable (not shown) is connected through a plug cap (not shown) to the metallic clamp member 40 connected, and to the metallic terminal element 40 a high voltage is applied.

A proximal end section 33 the earth electrode 30 is at the front end 57 of the metal housing 50 attached, and its distal end portion 35 is located at a location corresponding to the front electrode end portion 21 the center electrode 20 is turned. The ground electrode 30 is made of nickel or an alloy containing nickel as a main component. The ground electrode 30 is an element having a generally rectangular cross section when perpendicular to a direction of the ground electrode 30 is cut. The ground electrode 30 is at a position between the proximal end portion 33 and the distal end portion 35 bent. As a result, between the front electrode end portion 21 and the distal end portion 35 formed a spark gap for generating a spark discharge. A precious metal point 31 is with a surface of the distal end portion 35 connected, this surface to the front electrode end portion 21 is turned. The precious metal tip 31 is made of, for example, platinum (Pt), an alloy containing platinum as its main component, iridium (Ir), or an alloy containing iridium as a main component.

2 FIG. 10 is a flowchart illustrating a method of manufacturing the spark plug. FIG 100 shows. The method of manufacturing the spark plug 100 includes various steps, from a center electrode arranging step (step S10) to a bending step (step S50). First, the center electrode arranging step of the method of manufacturing the spark plug 100 performed (step S10). The center electrode arranging step includes a step in which the center electrode 20 in the axial opening 12 of the insulator 10 is arranged. The center electrode arranging step also includes a step in which the center electrode 20 in a part of the axial opening 12 is arranged on the front side FS, the material of the sealing elements 4 in the axial opening 12 is filled, the ceramic resistance 3 in the axial opening 12 is filled, then the metallic clamp element 40 in a part of the axial opening 12 is arranged on the back side BS, and these elements 3 . 4 . 20 and 40 in the insulator 10 can be incorporated by performing a heating / sealing operation at a high temperature.

Next, a metal shell manufacturing step is performed (step S20). The metal case manufacturing step is a step of manufacturing the metal case 50 , on which the ground electrode 30 is appropriate. The details of this step will be described later. Specifically, the order of steps S10 and S20 is not limited to the above order, and step S20 may be performed before step S10.

Next, an isolator arranging step is performed (step S30). The insulator arranging step includes a step in which the insulator 10 after the above-mentioned steps S10 and S20 in the metal case 50 is arranged. In particular, the talk 9 and the ring elements 6 . 7 ( 1 ) in the space between the inner peripheral surface of the metal case 50 and the outer peripheral surface of the insulator 10 arranged and becomes the crimping section 53 of the metal housing 50 bent inwards by crimping. As a result, the insulator 10 through the metal case 50 held.

Next, as in 2 a noble metal tip attachment step is performed (step S40). The noble metal tip attaching step includes a step in which the noble metal tip 31 with the distal end portion 35 is connected. After step S40, the bending step is performed (step S50). The bending step comprises a step in which the ground electrode 30 which is straight, to the center electrode 20 is bent. As a result of the bending step, the distal end portion 35 as in 1 shown disposed at a position at which the distal end portion 35 in the axis direction CLD to the front electrode end portion 21 is turned.

3 Fig. 10 is a flowchart showing the details of the metal shell manufacturing step (step S20). In the metal case manufacturing step, first, a step of manufacturing a base member with an electrode attached is performed (step S22). The electrode-attached base member manufacturing step includes a step in which the straight ground electrode 30 by welding to the metal housing 50 is attached. In addition, the step of manufacturing the electrode-mounted-base member (step S22) includes a step in which after attaching the ground electrode 30 by welding to the metal housing 50 Welding sags are eliminated, and a step in which the attachment screw section 52 on the outer peripheral surface of the metal housing 50 is formed (screw rolling step). The metal case 50 with the ground electrode 30 which is produced by step S22 is also referred to as a base element W.

After step S22, a step of attaching the heat-shrinkable member is performed (step S24). The attaching step is a step in which the entire ground electrode 30 from the proximal end portion 33 to the distal end portion 35 , by a heat-shrinkable element 90 is covered. The step of covering the ground electrode 30 through the heat-shrinkable element 90 Can be done by a manual worker or by using an attachment agent 97 ( 3 ) for holding the heat-shrinkable element 90 and covering the ground electrode 30 through the heat-shrinkable element 90 be carried out automatically.

The heat-shrinkable element 90 used in the present embodiment shrinks to a pre-stored shape when the heat-shrinkable tube 90 is heated. The above-mentioned step S24 is performed by the heat-shrinkable tube 90 is arranged so that the heat-shrinkable tube 90 the entire circumference of the ground electrode 30 over the entire length of the proximal end portion 33 to the distal end portion 35 surrounds. At one end of the heat-shrinkable tube 90 at its front FS is an opening 94 educated. The heat-shrinkable tube 90 is longer than the ground electrode by a certain amount 30 or, in the axial direction CLD of the ground electrode 30 measured, bigger.

After the above-described step S24, a heat-shrinking step is performed (step S26). The heat-shrinking step is a step in which the heat-shrinkable tube 90 is heated by using a heat source (a heat-shrinking agent) to the heat-shrinkable tube 90 thereby shrink. Shrinking the heat shrinkable tube 90 proceeds from the side at the proximal end portion 33 to the side at the distal end portion 35 Ahead. As a result of shrinkage of the heat-shrinkable tube 90 enters the heat-shrinkable tube 90 in close contact with the ground electrode 30 ,

4 is a set of views used to describe the details of the heat shrinking step. As in 4 That is, a heat source used in the heat-shrinking step is a nozzle 92 , A hot gas gets out of the nozzle 92 to the heat-shrinkable tube 90 blown. The nozzle 92 is disposed on a side which is a side surface of the ground electrode 30 equivalent. There is also a reflection plate 99 arranged at a position determined so that the reflection plate 99 via the ground electrode arranged therebetween 30 to the nozzle 92 is turned. The reflection plate 99 For example, it is made of a metal such as stainless steel. When the heat-shrinking step is performed, the position of the base member W is through a chuck 102 , which is made of a metal, fixed. In the present embodiment, the position of the base member W is due to holding the seal portion 54 of the base member W through the chuck 102 fixed.

The nozzle 92 moves from the side at the proximal end portion 33 along the direction (the axis direction) CLD, in which the ground electrode 30 extends to the side at the distal end portion 35 , In a state where the nozzle 92 is stopped for a certain time, a hot gas is applied to the heat-shrinkable tube 90 applied. In particular, the nozzle becomes 92 sequentially at a first to third operating position whose position differs in the axial direction CLD stopped and the hot gas from the stopped nozzle 92 blown and then onto the heat-shrinkable tube 90 applied.

When the hot gas comes out of the nozzle 92 being blown at the first operating position becomes a part of the heat-shrinkable tube 90 near the proximal end portion 33 heated and shrunk. After operating at the first operating position, the nozzle is moved to the second operating position, which is relative to the first operating position on the side of the distal end portion 35 located. When the hot gas comes out of the nozzle 92 being blown at the second operating position becomes an intermediate portion of the heat-shrinkable tube 90 between the proximal end portion 33 and the distal end portion 35 heated and shrunk. After operating at the second operating position, the nozzle is moved to the third operating position, which is related to to the second operating position on the side of the distal end portion 35 located. When the hot gas comes out of the nozzle 92 , which is blown at the third operating position, becomes a part of the heat-shrinkable tube 90 near the distal end portion 35 heated and shrunk. As a result, by applying the hot gas from the nozzle 92 at the first to third operating position to the heat-shrinkable tube 90 shrinks the entire heat-shrinkable tube and thus ends the heat-shrinking step.

In addition, as a result of the shrinkage of the heat-shrinkable tube, it escapes 90 a gas (air) through the opening 94 to the outside, inside the heat-shrinkable tube 90 is available. Therefore, it is possible to prevent the gas between the heat-shrinkable tube 90 and the ground electrode 30 remains, and the degree of adhesion between the heat-shrinkable tube 90 and the ground electrode 30 to increase. The opening 94 is at the end of the heat-shrinkable tube 90 formed on the front FS ( 3 and 4 ). Because this design prevents the gas (the air) from the side at the proximal end portion 33 to the outside of the heat-shrinkable tube 90 escapes, it is possible to use a part of the heat-shrinkable tube 90 at the side at the proximal end portion 33 even more reliable in close contact with the ground electrode 30 before reaching any part of the heat-shrinkable tube 90 on the side of the distal end portion into close contact with the ground electrode 30 arrives. Because the shrinking of the heat-shrinkable tube 90 is performed stably, it is possible in particular, the area in which a part of the ground electrode 30 at the side at the proximal end portion 33 not through the heat-shrinkable tube 90 is covered (the area in which the ground electrode 30 is free) to restrict even more precisely to a specific area.

As described above, the heat-shrinkable tube 90 in the heat-shrinking step, stepwise from the side at the proximal end portion 33 to the side at the distal end portion 35 shrunk, causing the heat-shrinkable tube 90 gradually from the side at the proximal end portion 33 to the side at the distal end portion 35 shrinking. As a result, the heat-shrinkable tube comes 90 first with a part of the ground electrode 30 at the side of the proximal end portion 33 in a close contact. Therefore, it is possible to prevent the heat-shrinkable tube 90 during the course of shrinkage of the heat-shrinkable tube 90 to the side at the distal end portion 35 is pulled, with a shrunken portion serves as the starting point of the pulling action. Therefore, the area where part of the ground electrode 30 at the side at the proximal end portion 33 not through the heat-shrinkable tube 90 is covered (the area in which the ground electrode 30 is free), limited to a specific area. In particular, the length (in the axial direction CLD) of the part of the ground electrode 30 that does not pass through the heat-shrinkable tube 90 covered (the gap diameter) are kept within a certain range. As a result, it is possible to use the area where the ground electrode 30 in a plating step (step S29 of FIG 2 ), which will be described later, is limited.

At each of the first to third operating positions, shrinkage of the heat-shrinkable tube occurs 90 as a result of the heating of the heat-shrinkable tube 90 held by the hot gas coming out of the nozzle 92 blown and directly onto the heat-shrinkable tube 90 is applied. Further, the shrinkage of the heat-shrinkable tube takes place 90 at any one of the first to third operating positions also as a result of the heating of the heat-shrinkable tube 90 held by the hot gas coming out of the nozzle 92 blown through the reflection plate 99 reflected and on the heat-shrinkable tube 90 is applied. As a result, the heat-shrinkable tube 90 be shrunk more uniformly in the circumferential direction over its entire circumference.

In particular, in the embodiment described above, the nozzle becomes 92 from the side at the proximal end portion 33 to the side at the distal end portion 35 emotional. However, there may be multiple nozzles 92 firmly at different positions in the direction (the axis direction) CLD, in which the ground electrode 30 extends, be arranged. For example, in the case of the present embodiment, there are three nozzles 92 at the first to third operating positions, in 4 are shown provided. Switching the nozzles 92 operated at the first to third operating positions in turn, so that they blow out a hot gas. By firmly providing the nozzles 92 can the hot gas coming out of each nozzle 92 blown with certainty on a specific area of the heat-shrinkable tube 90 be applied. As a result, the heat-shrinkable tube 90 from the side at the proximal end portion 33 to the side at the distal end portion 35 be gradually shrunk more reliably.

As in 3 2, after the above-described step S26, a cooling step is performed (step S28). The cooling step is a step in which a cooling gas is applied to at least the heat-shrinkable tube 90 caused by the heat-shrinking step on the metal housing 50 attached ground electrode 30 was applied, is applied. The cooling step is performed until the temperatures of the base member W and the chuck 102 reach a certain temperature (eg 40 ° C) or less. In the present embodiment, air at normal temperature (eg, 20 ° C) is used as the cooling gas. In particular, the cooling gas is not limited to normal temperature air, but may be air having a lower temperature than the normal temperature or other than air.

5 is used to describe the details of the cooling step. As in 5 the position of the base element W is also shown in the cooling step by the chuck 102 fixed in the heat-shrinking step. In the cooling step, the cooling gas is made up of a plurality (in the present embodiment 10 ) Nozzles 96 blown. Five nozzles 96 are disposed on a side which is a side surface of the ground electrode 30 corresponds, (the first side surface side), and the remaining five nozzles 96 are arranged on one side, that of the other side surface of the ground electrode 30 which is opposite to the one side surface (the second side surface side). The five nozzles 96 which are arranged on the first side surface side or the second side surface side, differ in the direction (the axis direction) CLD in which the ground electrode 30 extends, in terms of position.

In the cooling step, the cooling gas becomes out of the plural nozzles 96 blown and on the base element W and the chuck 102 applied. As a result, the heat-shrinkable tube heated by the heat-shrinking step becomes 90 cooled, whereby the curing of the heat-shrinkable tube 90 can be accelerated. Therefore, the likelihood of breakage of the heat shrinkable tube 90 be reduced. And there is the cooling of the base element W and the chuck 102 When heated by the heat-shrinking step, can be accelerated, it is possible to deteriorate the base member W and the chuck 102 that is caused because they are exposed to a high temperature environment. Because the base element W and the chuck 102 through the cooling gas coming from the several nozzles 96 is blown, it is also possible, the probability that the base element W and the chuck 102 be cooled unevenly, reduce.

As in 3 2, after the above-described step S28, a plating step is performed (step S29). The plating step is a step in which a Ni plating layer and / or a zinc plating layer and / or a chromate layer is formed on the surface of the base member W. In the present embodiment, after the formation of a zinc coating layer on the surface of the base member W, a chromate layer is formed on the zinc coating layer. The plating layer is formed, for example, by dipping the base member W into a plating solution and causing a current flow between an anode portion and a cathode portion. After completion of the plating step, the heat-shrinkable tube becomes 90 at the ground electrode 30 liable, removed.

As described above, in the present embodiment, in the heat-shrinking step, the heat-shrinkable tube becomes 90 gradually from the side at the proximal end portion 33 to the side at the distal end portion 35 shrunk. This allows the area where part of the ground electrode 30 at the side at the proximal end portion 33 not through the heat-shrinkable tube 90 is limited to a specific area. As a result, the plating layer is prevented from being adhered to the surface of the ground electrode 30 whereby problems arising as a result of the formation of the plating layer on the ground electrode 30 occur (eg a welding defect between the ground electrode 30 and the precious metal tip 31 ) can be mitigated. Since a place where the heat-shrinking step (step S26 of FIG 3 ), and a place where the plating step (step S29 of FIG 3 ), differ from each other, the base element W must be moved. However, since the cooling step is provided between the heat-shrinking step and the plating step, curing of the heat-shrinkable tube can be performed 90 be accelerated by the cooling step before the base member W is moved to the place where the plating step is performed. As a result, it is possible to determine the likelihood of, for example, a positional shift of the heat-shrinkable tube 90 that occurs in a situation where the posture of the base member W changes, for example, as it moves, or in a situation where an external force acts on the base member W. That is, because the shrinkage of the heat-shrinkable tube 90 due to the provision of the cooling step is performed stably, the area in which a part of the ground electrode 30 at the side at the proximal end portion 33 not from the heat-shrinkable tube 90 is covered (the area where the ground electrode 30 is free), with even greater accuracy limited to a particular range.

6 FIG. 13 is a view used to describe a heat-shrinking step which is a comparative example. FIG. At the in 6 The comparative example shown becomes the heat-shrinkable tube 90 heat shrunk by the heat shrinkable tube 90 from the beginning by blowing a hot gas from the nozzles 92 is heated completely. In this case, in some cases, a part Ps of the heat-shrinkable tube 90 between the proximal end portion 33 and the distal end portion 35 the earth electrode 30 shrink first. In such a case, the tube is drawn to the part Ps, the part Ps serving as the starting point of the pulling action. As a result, a part CH of the ground electrode becomes 30 at the side at the proximal end portion 33 that does not pass through the heat-shrinkable tube 90 is covered (an exposed section CH) larger. As a result, a region in which the plating step becomes a plating layer at the ground electrode 30 is formed, larger, and may have problems such as a welding defect between the ground electrode 30 and the precious metal tip 31 occur. In addition, as the exposed portion CH becomes larger, the area of a surface of the ground electrode becomes larger 30 at which the plating layer is formed larger. As a result, the plating layer may peel off when the ground electrode 30 in the bending step (step S50 of FIG 2 ), which is a subsequent step, is bent. If the plating layer peels off, a detached part of the plating layer may be connected to the center electrode 20 come in contact, which leads to a fault in terms of stable spark generation.

B. Second Embodiment:

7 is a view that is used to make a device 80 for the production of the metal housing 50 to be used in the second embodiment. The manufacturing device 80 is used to determine the steps S24 to S28 ( 3 ) of the metal shell manufacturing step (step S20 in FIG 2 and 3 ) in the first embodiment. The second embodiment is different from the first embodiment in the point that another manufacturing apparatus is used in the metal housing manufacturing step. Because other points (eg the structure of the spark plug 100 ) are identical to the first embodiment, the same structural components are denoted by the same reference numerals, and their description will be omitted.

The manufacturing device 80 has a round table 82 on which the base element W is placed. The chuck 102 ( 4 ) is at each working position P1 to P16 on the table 82 provided. The working positions P1 to P16 are substantially constantly spaced along the circumferential direction of the table 82 arranged. When the table is 82 As indicated by an arrow Ra turns counterclockwise, this is on the table 82 arranged base element W transported.

At the working position P1, the base member W manufactured by the electrode-attached base member (step S22) is supplied to the manufacturing apparatus 80 delivered. In particular, the base member W is replaced by the chuck 102 at the table 82 , which is located at the working position P1, fixed.

At the working positions P2 to P7, the attaching step (step S24 of FIG 3 ) carried out. In particular, the ground electrode moved to the working positions P2 to P7 becomes 30 of the base member W through the heat-shrinkable tube 90 covered. In particular, it is sufficient if the ground electrode 30 at least one of the working positions P2 to P7 through the heat-shrinkable tube 90 is covered.

At the working positions P8 to P10, the heat-shrinking step (step S26 of FIG 3 ) carried out. In particular, at the working position P8, the step performed at the first operating position of 4 is carried out; at the working position P9, that step is carried out at the second operating position of 4 is carried out; and at the working position P10, that step is carried out at the third operating position of 4 is carried out. At the working positions P8 to P10 is a surrounding element 84 provided. The surrounding element 84 forms such a tunnel that the working positions P8 to P10 are inside the tunnel. The base element W moves inside the surrounding element 84 ,

8th FIG. 13 is a view used to describe the heat-shrinking step performed at the working positions P8 to P10. In 8th The base member W moves from the depth to the front of the sheet. In a range from the working position P8 to the working position P10 is the surrounding element 84 on the table 82 arranged. The surrounding element 84 formed into a tunnel-like shape covers the vicinity of the base member W. The nozzles 92 , which are arranged at the working positions P8 to P10, are stationary and have different heights from the table 82 on. In particular, the nozzles are 92 arranged so that the distance from the table 82 in the order of the nozzle 92 at working position P8, the nozzle 92 at the working position P9, and the nozzle 92 increases at the working position P10. In addition, as in the case of the first embodiment, at each of the working positions P8 to P10 is a reflection plate 99 arranged at a position that of the nozzle 92 with respect to the ground electrode 30 opposite.

As a result of the hot gas coming out of the nozzle 92 who are at work position P8 is blown, becomes part of the heat-shrinkable tube 90 near the proximal end portion 33 heated and shrunk. After operating at the working position P8, the base member W moves to the working position P9. As a result of the hot gas coming out of the nozzle 92 , which is blown at the working position P9, becomes an intermediate portion of the heat-shrinkable tube 90 between the proximal end portion 33 and the distal end portion 35 heated and shrunk. After operating at the working position P9, the base member W moves to the working position P10. As a result of the hot gas coming out of the nozzle 92 , which is blown at the working position P10, becomes a part of the heat-shrinkable tube 90 near the distal end portion 35 heated and shrunk.

As described above, the heat-shrinking step becomes the manufacturing apparatus 80 according to the second embodiment, by moving the base member W so as to be arranged sequentially at the different working positions P8 to P10, and by moving it through the nozzles 92 (Heat source) from the side of the proximal end portion 33 to the side at the distal end portion 35 heated portion of the base member W by a certain extent to another of the working positions P8 to P10. Therefore, in addition to the effect of the first embodiment, the following effect can be obtained. In particular, the time it takes to heat shrinkable tube 90 shrink at each of the different working positions, compared with the case where the heat-shrinkable tube 90 is shrunk to a single working position, shortened. For example, in the case where the heat-shrinkable tube is 90 at each of the working positions P8 to P10 approximately 3 It takes about 9 seconds to heat the entire heat-shrinkable tube 90 (from the side at the proximal end portion 33 to the side at the distal end portion 35 ) shrink when the entire heat-shrinkable tube 90 is heated at a single working position. Therefore, in the case where the heat-shrinkable tube, the base member W may 90 shrunk to a single working position, moving only at intervals of about 9 seconds. Therefore, the performance of manufacturing the metal housing decreases 50 from. In contrast, in the case where the heat-shrinking step is divided into substeps and the substeps are performed at the working positions P8 to P10, respectively, the base member W can be moved at intervals of about 3 seconds. Therefore, the performance of the production of the metal housing 50 be increased.

Referring again to 7 the steps following the heat-shrinking step will be described. At the working positions P11 and P12, the cooling step (step S28 of FIG 3 ) carried out. In particular, at the working positions P11 and P12, the cooling air from the plurality in 5 shown nozzles 92 blown, whereby the base element W and the chuck 102 be cooled. For example, the cooling is performed at each of the working positions P11 and P12 for about 3 seconds.

As described above, the cooling step in the manufacturing apparatus 80 of the second embodiment, by moving the base member W so as to be arranged sequentially at the different working positions P11 and P12, and the cooling gas with each movement of the base member W to another one of the working positions P11 and P12 on the metal case 50 is applied. Therefore, the time needed for cooling the metal case 50 is needed at each of the different working positions, compared to the case where the metal housing 50 cooled at a single working position, be shortened. For example, it suffices in the case in which an approximately 6 Cooling is necessary for about 3 seconds to perform cooling at each of the working positions P11 and P12. Therefore, the performance of the production of the metal housing 50 be increased.

As in 7 9, the base member W which has undergone the cooling step is shown at the working positions P13 to P16 of the manufacturing apparatus 80 ejected (ejection step). In the ejecting step, a checking step of determining the size of the gap between the heat-shrinkable tube 90 and the ground electrode 30 falls within a certain range, be performed before the base member W from the chuck of the manufacturing device 80 Will get removed. By the in 3 The plating step shown, a plating layer is formed on the ejected base member W.

C. Modifications

C-1. First modification:

In the embodiment described above, a heat-shrinkable tube is used as the heat-shrinkable member. However, the heat-shrinkable member is not limited to this, and other members that shrink when heated may be used. In addition, the heat source is the nozzle 92 blowing out a hot gas. But the heat source is not on the nozzle 92 limited, and there may be other elements that heat the heat-shrinkable element can be used. For example, a heating wire or the like may be used as a heat source.

C-2. Second modification:

In the embodiments described above, the cooling step is performed using a plurality of nozzles 96 which supplies the cooling gas to the base element W and the chuck 102 ( 5 ) blowing. However, the cooling step can be done using only a single nozzle 96 , or by arranging several nozzles 96 on only one side of the ground electrode 30 be performed. In addition, the cooling gas from at least one nozzle 96 to the base element W and the chuck 102 be blown while the nozzle 96 is moved, or every time the nozzle 96 is moved.

In addition, the cooling step may be performed so that the cooling gas does not affect other elements than the heat-shrinkable element 90 is blown as long as the cooling as a result of the blowing of the cooling gas on the heat-shrinkable element 90 is accelerated.

C-3. Third modification:

In the above-described embodiments, in the heat-shrinking step, the reflection plate becomes 99 ( 4 ) used. It may, however, be on the reflection plate 99 be waived. In particular, the heat-shrinkable element 90 by directly heating the heat-shrinkable element 90 shrunk using a heat source.

C-4. Fourth modification:

In the embodiment described above, the manufacturing apparatus moves 80 the base member W in the circumferential direction. However, the moving direction is not limited to this, and the base member W can be fixed to a straight table and be moved straight.

C-5. Fifth modification

In the embodiments described above, the spark plug 100 the precious metal tip 31 ( 1 ) on; it may, however, point to the precious metal tip 31 be waived. In addition, the method includes manufacturing the spark plug 100 the noble metal tip attachment step (step S40 of FIG 2 ); however, this step can be dispensed with.

In addition, the heat-shrinkable element has 90 the opening 94 ( 4 ) for the delivery of the gas; it may, however, affect the opening 94 be waived.

 The present invention is not limited to the above-described embodiments and modifications, and may be embodied in various forms without departing from the scope of the invention. For example, in the embodiments and modifications that correspond to the technical features of the types discussed in the "Summary of the Invention" section, the technical features may be freely combined or replaced with other features to partially or partially obviate the problems described above In its entirety or in order to partially or completely render the effects described above. In addition, a technical feature (s) may be omitted, provided that the technical feature (s) is not described as an essential feature (described as essential features).

LIST OF REFERENCE NUMBERS

3

 ceramic resistor

4

 sealing element

5

 poetry

6

 ring element

8th

 sheet metal seal

9

 talc

10

 insulator

12

 axial opening

13

 leg portion

15

 step portion

17

 front hull section

18

 rear fuselage section

19

 flange

20

 center electrode

21

 front electrode end section

30

 ground electrode

31

 noble metal tip

33

 proximal end portion

35

 distal end portion

40

 metallic clamp element

50

 metal housing

51

 Tool engagement portion

52

 Anbringungsschraubabschnitt

53

 crimp

54

 sealing section

56

 step portion

57

 front end

80

 making device

82

 table

84

 surrounding element

90

 heat-shrinkable tube (heat-shrinkable element)

92

 jet

94

 opening

96

 jet

97

 attachment means

99

 reflecting plate

100

 spark plug

102

 chuck

600

 motor head

601

 opening

CL

 axis line

CLD

 axis direction

W

 base element

CH

 exposed section

FS

 front

BS

 back

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• JP 2001-68250 [0003]

Claims (11)

Method for producing a metal housing ( 50 ) in a spark plug ( 100 ) is used and a straight ground electrode ( 30 ) comprising: - an attaching step (S24) for covering the ground electrode (S24) 30 ) with a heat-shrinkable element ( 90 ), so that the ground electrode ( 30 ) from its proximal end portion ( 33 ) to its distal end portion ( 35 ) is covered; A heat-shrinking step (S26), after the attaching step (S24), for gradually shrinking the heat-shrinkable element (FIG. 90 ) from one side at the proximal end portion (FIG. 33 ) to a side at the distal end portion (FIG. 35 ) by heating the heat-shrinkable element ( 90 ) by means of a heat source ( 92 ); and a plating step (S29), after the heat-shrinking step (S26), for plating a surface of the metal shell (S29) 50 ). Method for producing a metal housing ( 50 ) according to claim 1, wherein the heat-shrinking step (S26) comprises a step of - in which the heat-shrinkable element ( 90 ) is heated by direct application of a hot gas, which consists of a heat source ( 92 ) serving nozzle ( 92 ) is blown, - in which the heat-shrinkable element ( 90 ) by reflecting the out of the nozzle ( 92 ), hot gases by means of a reflection plate ( 99 ) attached to one of the nozzles ( 92 ) with respect to the ground electrode ( 30 is disposed opposite position, is heated, and - in which the reflected, hot gas on the heat-shrinkable element ( 90 ) is applied. Method for producing a metal housing ( 50 ) according to claim 1 or 2, wherein said heat-shrinking step (S26) is performed by moving said metal case (W) so that said metal case (W) is sequentially arranged at different working positions (P8 to P10), and a part of heat-shrinkable element ( 90 ) caused by the heat source ( 92 ) with each movement of the metal housing (W) to another of the working positions (P8 to P10) to a certain extent from the side of the proximal end portion ( 33 ) to the side of the distal end portion (FIG. 35 ) is moved. Method for producing a metal housing ( 50 ) according to one of claims 1 to 3, wherein a plurality of heat sources ( 92 ) and fixed at different positions. Method for producing a metal housing ( 50 ) according to any one of claims 1 to 4, wherein - the heat-shrinkable element ( 90 ) an opening ( 94 ) in a state in which the heat-shrinkable element ( 90 ) the ground electrode ( 30 ), at the side of the distal end portion (FIG. 35 ), and - said heat-shrinking step (S26) comprises a step of injecting a gas inside said heat-shrinkable member (S26) 90 ) is present through the opening ( 94 ) is delivered. Method for producing a metal housing ( 50 ) according to any one of claims 1 to 5, further comprising a cooling step (S28) performed between the heat-shrinking step (S26) and the plating step (S29) to apply a cooling gas to at least the heat-shrinkable member (S28). 90 ) connected to the ground electrode ( 30 ) of the metal housing (W) is mounted. Method for producing a metal housing ( 50 ) according to claim 6, wherein the cooling step (S28) is performed by moving the metal shell (W) so that the metal shell (W) is sequentially placed at different working positions (P11, P12), and the cooling gas is when the metal case (W) moves to another of the working positions (P11, P12), is applied to the metal case (W). Method for producing a metal housing ( 50 ) according to claim 6 or 7, wherein the cooling gas from a plurality of nozzles ( 96 ) is blown. Method for producing a metal housing ( 50 ) according to any one of claims 6 to 8, wherein - the heat-shrinking step (S26) is performed in a state where the metal case (W) is held by a holding member (S) 102 ), and - the cooling step (S28) comprises a step in which the cooling gas is applied to the holding member (12) 102 ) and the metal housing ( 50 ), whereby the ground electrode ( 30 ) is applied. Method for producing a spark plug ( 100 ) comprising: a center electrode arranging step (S10) for arranging a center electrode in an axial opening of an insulator; A case manufacturing step (S20) for manufacturing the metal case (FIG. 50 ) using a metal shell manufacturing method according to any one of claims 1 to 9; An insulator arranging step (S30) for disposing the insulator inside the metal shell (S30) 50 ); and a bending step (S40) for bending the ground electrode (S40) 30 ), so that the center electrode ( 20 ) and the front end portion ( 35 ) of the ground electrode ( 30 ) are facing each other. Device for producing a metal housing ( 50 ) for use in a spark plug ( 100 ) with a straight ground electrode ( 30 ), comprising: - attachment means ( 97 ) to the ground electrode ( 30 ) by a heat-shrinkable element ( 90 ) so that the ground electrode ( 30 ) from its proximal end portion ( 33 ) to its distal end portion ( 35 ) is covered; and heat shrinking means ( 92 ) to the heat-shrinkable element ( 90 ) by heating the heat-shrinkable element ( 90 ) by means of a heat source ( 92 ) progressively from one side to the proximal end portion (FIG. 33 ) to a side at the distal end portion (FIG. 35 ) to shrink.

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