JP4342289B2 - Method for manufacturing spark plug metal shell and method for manufacturing spark plug - Google Patents

Description

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

  A spark plug, which is an ignition execution means of an ignition device for an internal combustion engine, has a large-diameter hole and a medium-diameter hole that is smaller in diameter than the large-diameter hole from the proximal end side to the distal end side through the axial center of the cylindrical member And a flange-shaped intermediate cylindrical portion that is formed by connecting a small-diameter hole that is smaller in diameter than the medium-diameter hole and projects radially outward of the cylindrical member; And a cylindrical metal shell for a spark plug having a distal end side cylindrical portion positioned on the base end side and a proximal end side cylindrical portion positioned on the proximal end side with respect to the intermediate cylindrical portion. The tip side means the spark discharge part side of the spark plug assembled with the spark plug metal shell.

Therefore, the metal shell is manufactured by using a metal solid round bar cut to a predetermined length as a starting material and appropriately combining extrusion molding, punching molding, or the like by cold forging (Patent Document 1). reference).
Japanese Unexamined Patent Publication No. 7-16669 (page 2)

In recent years, the area occupied by the intake and exhaust valves in the combustion chamber has increased with the increase in output of internal combustion engines used in automobiles and the like. Therefore, it is necessary to reduce the size of the spark plug for igniting the air-fuel mixture. In addition, the temperature in the combustion chamber tends to rise, and it is necessary to sufficiently dissipate the heat (heat extraction) of the electrode part in order to ensure the long life of the spark plug even under severe usage conditions. is there. Therefore, an attempt has been made to improve the heat dissipation performance of the spark plug by further lengthening the distal end side cylindrical portion of the metal shell (so-called long reach). In such a demand for downsizing and long reach, the multi-stage holes (large diameter hole, medium diameter hole, small diameter hole) of the metal shell must be thin and long. However, in the manufacturing method as in Patent Document 1, There is a risk that the jig will have a short service life, such as a load on the punch required for drilling, and that it may be difficult to process a multistage hole straight.
The present invention has been made in view of such problems, and provides a method for manufacturing a metal shell for a spark plug and a method for manufacturing a spark plug, which have a long tool life, and are highly accurate and low cost. Objective.

In order to achieve the above object, the present invention provides a large-diameter hole, a medium-diameter hole that is smaller in diameter than the large-diameter hole, and a medium-diameter hole that penetrates the axial center of the cylindrical member from the proximal end side toward the distal end side. A flange-shaped intermediate cylindrical portion that is formed by connecting a small-diameter hole that is smaller in diameter than the diameter hole and projects radially outward of the cylindrical member, and a distal end that is located on the distal end side of the intermediate cylindrical portion A method of manufacturing a metal shell for a spark plug, comprising: a side tubular portion; and a proximal end tubular portion located on a proximal end side from the intermediate tubular portion,
Starting with metal pipe material,
After processing the pipe material to a predetermined length in the first step ,
In the second step, by extruding the distal end side of the pipe material, the distal end side cylindrical portion smaller in diameter than the pipe material is formed,
In the third step, by extruding the proximal end side, the shaft hole of the pipe material is expanded to form the large-diameter hole,
In the fourth step, by extruding the base end side, forming the base end side cylindrical portion smaller in diameter than the pipe material, and forming the intermediate cylindrical portion,
In the fifth step, a spark plug manufacturing method in which the proximal end side is extruded to increase the diameter of the shaft hole of the pipe material to form the medium diameter hole and to form the small diameter hole. I will provide a.

According to a second aspect of the present invention, there is provided a large-diameter hole, a medium-diameter hole that is smaller in diameter than the large-diameter hole from the proximal end side toward the distal end side through the axial center of the cylindrical member, A flange-shaped intermediate cylindrical portion that is formed by connecting a small-diameter hole that is smaller in diameter than the diameter hole and projects radially outward of the cylindrical member, and a distal end that is located on the distal end side of the intermediate cylindrical portion A method of manufacturing a metal shell for a spark plug, comprising: a side tubular portion; and a proximal end tubular portion located on a proximal end side from the intermediate tubular portion,
Starting with metal pipe material,
After processing the pipe material to a predetermined length in the first step,
In the second step, by extruding the distal end side of the pipe material, the distal end side cylindrical portion smaller in diameter than the pipe material is formed,
In the third step, by extruding the proximal end side, the shaft hole of the pipe material is expanded to form the large-diameter hole,
In the fourth step, by extruding the base end side, the shaft hole of the pipe material is expanded to form the medium diameter hole, and the small diameter hole is formed,
In the fifth step, the base for the spark plug is formed by extruding the base end side to form the base end side cylindrical portion having a diameter smaller than that of the pipe material and forming the intermediate cylindrical portion. A method for manufacturing a metal fitting is provided.

According to a third aspect of the present invention, there is provided a spark plug metal shell wherein the inner diameter of the pipe material as a starting material is set to be not less than the diameter of the small diameter hole and not more than the diameter of the large diameter hole.

Further, as described in claim 4, the outer diameter of the starting material serving as the pipe material, the distal-side tubular portion of larger than the diameter, claims 1 to 3 as a diameter or less of a said intermediate tubular portion A spark plug metal shell according to any one of the above is provided.

Further, as described in claim 5 , the spark plug metal shell having a length L from the end surface of the intermediate cylindrical portion of the final shape to the distal end surface of the front end side cylindrical portion exceeding 19 mm is to be manufactured. A method for manufacturing a spark plug metal shell according to any one of 1 to 4 is provided.

Further, as described in claim 6, any one of claims 1 to 5 final shaped tip diameter D of the distal tubular portion is to manufacture the target metal shell for a spark plug is less than 10.5mm The manufacturing method of the metal shell for spark plugs described in 1. is provided.

In addition, as described in claim 7 , an insulator in which a center electrode and a terminal metal fitting are assembled to a spark plug metal shell manufactured by the method described in any one of claims 1 to 6 is provided on a base end side. A spark plug manufacturing method is provided in which one end of a ground electrode is joined to the tip of the spark plug metal shell, and the other end of the ground electrode is opposed to the center electrode.

According to the manufacturing method of the first or second aspect , since the pipe material is used as the starting material, there is no need to drill the multi-stage hole of the metal shell, and therefore there is no possibility of damaging the punch. Furthermore, it becomes possible to process a multistage hole straight, and a small and long reach spark plug metal shell can be manufactured with high accuracy and at low cost.

In addition, as described in claim 3, when the inner diameter of the pipe material, which is a starting material, is not less than the diameter of the small diameter hole and not more than the diameter of the large diameter hole, the large diameter hole, the medium diameter hole, and the small diameter The processing amount for forming the hole is reduced, the life of the processing jig is extended, and the molding can be performed with low cost and high accuracy. Furthermore, it is more preferable to make the inner diameter of the pipe material as a starting material coincide with the diameter of any one of the large diameter hole, the medium diameter hole, and the small diameter hole. Thereby, since it is not necessary to process each matched part, the lifetime of a jig | tool becomes further longer and it can shape | mold with low cost and high precision. In order to make the inner diameter of the pipe material coincide with any of the large-diameter hole, the medium-diameter hole, and the small-diameter hole, the inner diameter of the pipe material is preferably set to a reference dimension of either diameter, The inner diameter of the pipe material may be adjusted within the dimensional tolerance of the diameter.

Further, as described in claim 4, when the outer diameter of the pipe material which is a starting material is set to be equal to or larger than the diameter of the distal cylindrical portion and not larger than the diameter of the intermediate cylindrical portion, the distal cylindrical shape The amount of processing for forming the portion, the intermediate cylindrical portion, and the rear end side cylindrical portion is reduced, the life of the processing jig is increased, and the molding can be performed with low cost and high accuracy. Furthermore, it is more preferable that the outer diameter of the pipe material as the starting material is matched with the diameter of any of the front end side cylindrical portion, the intermediate cylindrical portion, and the rear end side cylindrical portion. Thereby, since it is not necessary to process each matched part, the lifetime of a jig | tool becomes further longer and it can shape | mold with low cost and high precision. In addition, to make the outer diameter of the pipe material coincide with the diameter of any one of the front end side cylindrical portion, the intermediate cylindrical portion, and the rear end side cylindrical portion, the inner diameter of the pipe material is defined as a reference dimension of any diameter. However, the outer diameter of the pipe material may be adjusted within the dimensional tolerance of each diameter.

Further, according to the manufacturing method as set forth in claim 5 , the metal shell for a spark plug such that the length L from the end surface of the intermediate cylindrical portion of the final shape to the front end surface of the front end side cylindrical portion exceeds 19 mm. (Generally referred to as long reach), however, the multi-step holes can be easily processed straight, and the life of the jig can be extended.

Further, according to the manufacturing method as set forth in claim 6 , even a spark plug metal shell (generally referred to as a small size) whose final shape has a distal end diameter D of the distal end side cylindrical portion of less than 10.5 mm. The multi-step holes can be easily processed straight and the life of the jig can be extended. The tip diameter D of the tip-side cylindrical portion refers to the outer diameter of the tip excluding the chamfered portion formed at the tip corner of the metal shell. Therefore, the present invention can be applied to a so-called screwless plug in which a mounting screw is not formed on the outer surface of the metal shell.

  Embodiments of the present invention will be described below with reference to the drawings. 1A (a) to (d) and FIGS. 1B (a) to (d) are cross-sectional views showing the manufacturing process of the intermediate for the metal shell, and FIG. 2 (a) is a perspective view of the pipe material in a half cross-section. FIG. 2 (b) is a perspective view of the metal shell intermediate body in a half section, and FIG. 3 is a front view of the spark plug in a half section.

[Spark plug structure]
As shown in FIG. 3, the spark plug 1 is made of a metal cylindrical metal shell 2, a cylindrical insulator 3 provided in a shaft hole that penetrates the axis of the metal shell 2, and the insulator 3. A center electrode 4 provided in the shaft hole 3H on the front end side of the metal shell 2 and a ground electrode 5 disposed so that one end is fixed to the front end surface of the metal shell 2 and the other end faces the front end portion of the center electrode 4. is doing.

  The metal shell 2 is substantially cylindrical, and has an intermediate cylindrical portion 21 that protrudes outward, and a distal-end-side cylindrical portion 22 that is located on the distal end side of the intermediate cylindrical portion 21 and has a smaller diameter than the intermediate cylindrical portion 21. And a proximal-side tubular portion 23 located on the rear end side of the intermediate tubular portion 21. A male screw 6 for screwing the spark plug 1 to the cylinder head or the like is formed on the outer periphery of the distal end side cylindrical portion 22, and a chamfered portion 6 x is formed on the outer peripheral edge of the distal end side cylindrical portion 22. Has been. The proximal-side cylindrical portion 23 includes a tool engaging portion 231 having a hexagonal cross section in the radial direction for engaging a tool such as a spanner when the spark plug 1 is attached to a cylinder head or the like, and a tool engaging portion 231. A crimping portion 232 for caulking and fixing the insulator 3 to the metal shell 2 and a groove portion 233 positioned on the distal end side of the tool engaging portion 231 are provided on the proximal end side. The multi-stage hole 8 of the metal shell 2 has a large diameter hole 8L from the proximal end toward the distal end side, a medium diameter hole 8M having a diameter smaller than that of the large diameter hole 8L, and a small diameter having a diameter smaller than that of the medium diameter hole 8M. The holes 8S are formed continuously. In FIG. 3, reference numeral 40 is a known gasket fitted on the proximal end side of the distal end side cylindrical portion 22. In the metal shell 2 of the present invention, the length L from the end surface of the intermediate cylindrical portion 21 to the distal end surface of the distal cylindrical portion 22 is 25 mm, and the distal end diameter D of the distal cylindrical portion 22 is 10.1 mm. It has become.

  On the other hand, the insulator 3 is made of alumina ceramic, and as described above, the shaft hole 3H is provided along the central axis. A center electrode 4 is fixed to the distal end side of the shaft hole 3H, and a terminal fitting 7 for guiding a high voltage to the center electrode 4 is fixed to the proximal end side. A resistor 9 is disposed between the center electrode 4 and the terminal fitting 7 in the shaft hole 3H. Both ends of the resistor 9 are electrically connected to the center electrode 4 and the terminal fitting 7 by the conductive glass seal layers 10 and 10 respectively, and the central electrode 4 and the resistor are connected by the conductive glass seal layer 10. 9 and the terminal fitting 7 are hermetically sealed with the shaft hole 3H of the insulator 3. The insulator 3 is positioned on the base end side of the protruding portion 31 and the protruding portion 31 that is protruded in the radial direction so as to engage with the large-diameter hole 8 </ b> L when assembled to the metallic shell 2. A base end portion 32 having a diameter smaller than that of the large-diameter hole 8L, an intermediate barrel portion 33 that is positioned on the distal end side of the projecting portion 31 and engages with the medium-diameter hole 8M when assembled to the metal shell 2. The leg portion 34 is located on the tip side from the portion 33 and forms a gap with the small-diameter hole 8S when assembled.

[Manufacturing method of metal shell]
A method of manufacturing the metal shell 2 will be described with reference to FIGS. 1A (a) to 1A (d). First, a pipe material P shown in FIG. 2A is prepared as a starting material. This pipe material P is made of low carbon steel (S10C, S17C, S25C, S45C) or SVS430 suitable for cold forging. And the outer diameter of the intermediate cylindrical portion 21 is the same as the outer diameter of the intermediate cylindrical portion 21, and a long object is cut into a predetermined length. The outer diameter and inner diameter of the pipe material P are most efficient when they meet the above conditions from the beginning. However, the outer diameter and inner diameter may be adjusted and used in the pretreatment.

  Next, the pipe material P is set in a cold forging machine, and a pin 11 having a thickness that fits the shaft hole 80 of the pipe material P is passed through the shaft hole 80 as shown in FIG. The pipe material P is put, and the front end side cylindrical portion 22 is formed by extrusion molding by cold forging. At this time, the tip of the pin 11 is supported in a kick-out sleeve 13 (which may be integrated with the die 12). Further, the portion above the distal cylindrical portion 22 is maintained at the initial diameter of the pipe material P, that is, the same diameter as the intermediate cylindrical portion 21.

  Next, as shown in FIG. 1A (b), the pinned punch 14 is passed through the shaft hole 80, and the upper portion of the shaft hole 80 is expanded by extrusion molding by cold forging to form a large-diameter hole 8L of the multistage hole 8. At this time, the tip of the pinned punch 14 is supported by being inserted into a kickout sleeve 15 (which may be integrated with the die 16). Even at this stage, the portion above the distal cylindrical portion 22 remains the same diameter as the intermediate cylindrical portion 21.

  Next, as shown in FIG. 1A (c), the mandrel 17 is passed through the upper portion of the shaft hole 80, and the proximal-side cylindrical portion 23 is formed by extrusion molding by cold forging. Although the base end side cylindrical part 23 of embodiment is a hexagon bolt form as shown in FIG.2 (b), it is not necessary to limit to such a hexagon bolt form, BI-HEX etc. in other forms other than that Of course it is good.

  In addition, although the front end side cylindrical part 22 and the base end side cylindrical part 23 were completed by the process so far, the intermediate | middle cylindrical part 21 pinched | interposed between them is also naturally completed by these both being completed. ing.

  Next, as shown in FIG. 1A (d), the pinned punch 18 is passed through the shaft hole 80, and the medium-diameter hole 8M of the multistage hole 8 is formed by extrusion molding by cold forging. At this time, the tip of the pin-equipped punch 18 is supported in a kick-out sleeve 19 (which may be integrated with the die 20). The large-diameter hole 8L and the medium-diameter hole 8M are completed through the steps up to here, and the small-diameter hole 8S is naturally completed by the completion of both.

  In addition, in the manufacturing method by FIG. 1A (a)-(d), the process of FIG. 1A (c) and FIG. 1A (d) is interchangeable. Such a manufacturing method is shown in FIGS. 1B (a) to 1 (d). For the explanation based on FIGS. 1B (a) to (d), (c) and (c) in FIGS. The description of d) is omitted because it may be replaced.

  Through the cold forging process shown in FIGS. 1A (a) to (d) or FIGS. 1B (a) to (d), a metal shell intermediate 200 as shown in FIG. 2 (b) is completed. Then, the male screw 6 and the chamfered portion 6x are formed on the distal end side cylindrical portion 22 of the metal shell intermediate body 200, and the proximal end of the proximal end side cylindrical portion 23 is cut into a round crown shape and a caulking portion 232 is formed. And the tip end side are also cut to form the groove portion 233, and the tool engaging portion 231 is also finished by performing necessary cutting to complete the metal shell 2. In addition, the external thread 6 is engraved on the distal end side cylindrical portion 22, or the caulking portion 232 is formed at the proximal end of the proximal end side cylindrical portion 23 and the groove portion 233 is formed at the distal end of the proximal end side cylindrical portion 23. The processing means for doing so is not particularly limited.

  Then, as shown in FIG. 3, the insulator 3 containing the center electrode 4 is fitted into the multistage hole 8 inside the metal shell 2 manufactured by the cold forging process and the cutting process as described above. The fastening portion 232 is crimped inward. Then, the protruding portion 31 of the insulator 3 is locked by the caulking portion 232 of the metal shell 2 via the ring 100 and the ceramic filling powder 101 and is formed between the medium diameter hole 8M and the small diameter hole 8S. The boundary portion and the step portion formed between the intermediate body portion 33 and the leg portion 34 of the insulator 3 are engaged with each other. Thereby, the spark plug 1 is manufactured by assembling the insulator 3 and the like in the metal shell 2.

  As mentioned above, although embodiment of this invention was described, of course, this invention is not limited to the said embodiment. For example, as shown in FIG. 4, the lower half of the small-diameter hole 8S of the multi-stage hole 8 may be expanded to an area of about the medium-diameter hole 8M. The processing for that is a step of inserting a punch from below the shaft hole 80 and extruding by cold forging in the middle of or after the step of FIG. 1A (a) to (d) or FIG. 1B (a) to (d). Add it. Moreover, although embodiment by this invention performed the process by cold forging, it is not restricted to this, You may make it perform by the process by a well-known press machine.

  The metal shell 2 that can be manufactured by the manufacturing method of the present invention has a wide variety of sizes, but the manufacturing method of the present invention has a final shape that is the end side from the end surface of the intermediate cylindrical portion 21 as in the present embodiment. The metal shell 2 in which the length L (see FIG. 3) to the distal end surface of the cylindrical portion 22 exceeds 19 mm, or the metal shell 2 in which the distal end diameter D (see FIG. 3) of the distal cylindrical portion 22 is less than 10.5 mm. It is most useful when it is a manufacturing target. The spark plug 1 corresponding to the metal shell 2 having this shape is classified into a small type or a long reach type, but the metal shell 2 having the above shape is a multistage hole in a conventional manufacturing method using a metal solid round bar as a starting material. This is because mass production with stable quality is difficult, for example, it is difficult to center 8 or the life of the jig is short.

(A)-(d) is sectional drawing which shows the manufacturing process of the intermediate body for metal shells. (A)-(d) is sectional drawing which shows the manufacturing process of the intermediate body for metal shells. (A) is the perspective view which made the pipe material the half cross section, (b) is the perspective view which made the intermediate body for metal fittings the half cross section. It is the front view which made the spark plug a half section. It is a perspective view which shows another form and which made the intermediate body for metal shells the half cross section.

DESCRIPTION OF SYMBOLS 1 ... Spark plug 2 ... Main metal fitting 21 ... Intermediate | middle cylindrical part 22 ... Front end side cylindrical part 23 ... Base end side cylindrical part 200 ... Intermediate | middle body 231 ... Tool engaging part 232 ... Clamping part 233 ... Groove part DESCRIPTION OF SYMBOLS 3 ... Insulator 31 ... Protrusion part 32 ... Base end part 33 ... Intermediate | middle trunk | drum 34 ... Leg part 3H ... Shaft hole 4 ... Center electrode 6 ... Male screw 8 ... Multistage hole 8L ... Large diameter hole 8M ... Medium diameter hole 8S ... Small diameter Hole 9 ... Resistor 10 ... Glass seal layer 11 ... Pin 17 ... Mandrel P ... Pipe material

Claims (7)

A large-diameter hole, a medium-diameter hole that is smaller in diameter than the large-diameter hole, and a small-diameter hole that is smaller in diameter than the medium-diameter hole from the proximal end side toward the distal end side through the axial center of the cylindrical member A flange-shaped intermediate cylindrical portion that is formed in a row and protrudes radially outward of the cylindrical member, a distal-end-side cylindrical portion that is located on the distal-end side of the intermediate-cylindrical portion, and the intermediate-cylindrical portion A base-end-side tubular portion located on the base end side, and a manufacturing method of a spark plug metal shell,
Starting with metal pipe material,
After processing the pipe material to a predetermined length in the first step ,
In the second step, by extruding the distal end side of the pipe material, the distal end side cylindrical portion smaller in diameter than the pipe material is formed,
In the third step, by extruding the proximal end side, the shaft hole of the pipe material is expanded to form the large-diameter hole,
In the fourth step, by extruding the base end side, forming the base end side cylindrical portion smaller in diameter than the pipe material, and forming the intermediate cylindrical portion,
In the fifth step, the shaft end of the pipe member is expanded to form the medium diameter hole and the small diameter hole is formed by extruding the proximal end side. A method for producing a spark plug metal shell. A large-diameter hole, a medium-diameter hole that is smaller in diameter than the large-diameter hole, and a small-diameter hole that is smaller in diameter than the medium-diameter hole from the proximal end side toward the distal end side through the axial center of the cylindrical member A flange-shaped intermediate cylindrical portion that is formed in a row and protrudes radially outward of the cylindrical member, a distal-end-side cylindrical portion that is located on the distal-end side of the intermediate-cylindrical portion, and the intermediate-cylindrical portion A base-end-side tubular portion located on the base end side, and a manufacturing method of a spark plug metal shell,
Starting with metal pipe material,
After processing the pipe material to a predetermined length in the first step ,
In the second step, by extruding the distal end side of the pipe material, the distal end side cylindrical portion smaller in diameter than the pipe material is formed,
In the third step, by extruding the proximal end side, the shaft hole of the pipe material is expanded to form the large-diameter hole,
In the fourth step, by extruding the base end side, the shaft hole of the pipe material is expanded to form the medium diameter hole, and the small diameter hole is formed,
In the fifth step, the proximal end side cylindrical portion having a diameter smaller than that of the pipe material is formed by extruding the proximal end side, and the intermediate tubular portion is formed. A method of manufacturing a metal shell for a spark plug. The method for manufacturing a metal shell for a spark plug according to claim 1 or 2 , wherein an inner diameter of the pipe material as the starting material is set to be not less than the diameter of the small-diameter hole and not more than the diameter of the large-diameter hole. The outer diameter of the starting material serving as the pipe material, the distal-side tubular portion on the diameter or, according to any one of claims 1 to 3, characterized in that the diameter or less of a said intermediate tubular portion A method for producing a spark plug metal shell. From the end surface of the intermediate cylindrical portion of the final shape of the tip end side tubular portion to the distal end surface length L of any one of claims 1 to 4, producing target metal shell for a spark plug exceeds 19mm A method for producing a spark plug metal shell. The spark plug metal shell manufacturing method according to any one of claims 1 to 5 , wherein the metal shell for a spark plug whose final shape is a tip side tubular portion having a tip diameter D of less than 10.5 mm is a manufacturing object. . An insulator in which a center electrode and a terminal fitting are assembled to a spark plug metal shell manufactured by the method according to any one of claims 1 to 6 is assembled from the base end side, and a tip end of the spark plug metal shell A spark plug manufacturing method, wherein one end of a ground electrode is joined to the ground electrode, and the other end of the ground electrode is opposed to the center electrode.

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