EP2337172B1 - Procede de fabrication de bougie d'allumage et dispositif de fabrication de bougie d'allumage - Google Patents

Procede de fabrication de bougie d'allumage et dispositif de fabrication de bougie d'allumage Download PDF

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Publication number
EP2337172B1
EP2337172B1 EP09818919.4A EP09818919A EP2337172B1 EP 2337172 B1 EP2337172 B1 EP 2337172B1 EP 09818919 A EP09818919 A EP 09818919A EP 2337172 B1 EP2337172 B1 EP 2337172B1
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EP
European Patent Office
Prior art keywords
ground electrode
end portion
spark plug
center electrode
electrode
Prior art date
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EP09818919.4A
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German (de)
English (en)
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EP2337172A1 (fr
EP2337172A4 (fr
Inventor
Keisuke Kure
Masahiro Enuma
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Niterra Co Ltd
Original Assignee
NGK Spark Plug Co Ltd
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Publication date
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Publication of EP2337172A1 publication Critical patent/EP2337172A1/fr
Publication of EP2337172A4 publication Critical patent/EP2337172A4/fr
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Publication of EP2337172B1 publication Critical patent/EP2337172B1/fr
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T21/00—Apparatus or processes specially adapted for the manufacture or maintenance of spark gaps or sparking plugs
    • H01T21/02—Apparatus or processes specially adapted for the manufacture or maintenance of spark gaps or sparking plugs of sparking plugs
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T13/00—Sparking plugs
    • H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
    • H01T13/32—Sparking plugs characterised by features of the electrodes or insulation characterised by features of the earthed electrode
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T21/00—Apparatus or processes specially adapted for the manufacture or maintenance of spark gaps or sparking plugs
    • H01T21/06—Adjustment of spark gaps
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T23/00—Apparatus for generating ions to be introduced into non-enclosed gases, e.g. into the atmosphere

Definitions

  • the present invention relates to a technique for manufacturing a spark plug used for an internal combustion engine, and more particularly to a method and apparatus for manufacturing a spark plug characterized by bending work performed on the ground electrode of the spark plug.
  • a spark plug used for an internal combustion engine such as an automotive engine includes, for example, a center electrode extending in an axial direction, an insulator which surrounds the center electrode, a tubular metallic shell fitted onto the insulator, and a ground electrode having a proximal end portion joined to a front end portion of the metallic shell.
  • the ground electrode is bent and disposed such that a distal end portion of the ground electrode faces a front end portion of the center electrode, whereby a spark discharge gap is formed between the front end portion of the center electrode and the distal end portion of the ground electrode.
  • the spark discharge gap is formed as follows. A metallic shell, to which a ground electrode having a straight-bar-like shape has been joined, and an insulator having a center electrode provided therein are assembled together. Subsequently, the straight-bar-like ground electrode is bent toward the center electrode.
  • a bending spacer is disposed to face a front end surface of the center electrode.
  • the ground electrode is pressed against the bending spacer, to thereby perform pre-bending.
  • the bending spacer is removed, and the ground electrode is bent, by use of a bending punch having a flat butting surface, to a position where a spark discharge gap of a predetermined size is formed (see, for example, Patent Document 1).
  • US 2005/039332 A1 discloses a provisional bending process of a spark plug during which the earth electrode which is straight and substantially in parallel with an axial line of the center electrode is bent in the direction of the central electrode.
  • two searchers individually facing the tip of the center electrode are provided between the center electrode and the earth electrode. Then, a bending punch is driven to press an end surface of the earth electrode down to the searchers in the direction of the center electrode.
  • JP 2005243260 A discloses a bending process during which the earth electrode is bent toward the center electrode while a spacer is provider between both electrodes.
  • Patent Document 1 Japanese Patent No. 3389121
  • the ground electrode In the lateral-discharge-type or inclined-discharge-type spark plug, the ground electrode must be bent at a position closer to the proximal end side (the side toward the metallic shell).
  • a limit arises on moving the bending spacer closer to the proximal end side due to the presence of the center electrode, and therefore, the technique encounters difficulty in bending of the ground electrode at a position closer to the proximal end side.
  • the size of the spark discharge gap may vary with a variation in position of the front end portion of the center electrode, which variation may arise depending on the state of assembly of the metallic shell and the insulator.
  • the above-described problem occurs not only in lateral-discharge-type and inclined-discharge-type spark plugs, but also in longitudinal-discharge-type spark plugs in which spark discharge occurs along the axial direction.
  • the present invention has been accomplished in view of the foregoing, and its object is to provide a method and apparatus for manufacturing a spark plug which can bend a ground electrode at a position closer to the proximal end thereof even after a metallic shell and an insulator are assembled together.
  • the present invention suggests a spark plug manufacturing method according to claim 1 and a spark plug manufacturing apparatus according to claim 11.
  • the dependent claims relate to advantageous features and embodiments of the invention.
  • a noble metal tip formed of a noble metal alloy may be joined to the front end portion of the center electrode and the distal end portion of the ground electrode.
  • the noble metal tips partially constitute the center electrode and the ground electrode, respectively.
  • a spark plug manufacturing method is characterized in that, in the above-mentioned configuration 1, the bending means is a roller which is configured to be movable in relation to the ground electrode along a direction approximately perpendicular to the axis and which is supported for free rotation, and an outer circumferential surface of the roller is pressed against a side surface of the ground electrode opposite the center electrode so as to perform the bending work on the ground electrode.
  • the bending means is a roller which is configured to be movable in relation to the ground electrode along a direction approximately perpendicular to the axis and which is supported for free rotation, and an outer circumferential surface of the roller is pressed against a side surface of the ground electrode opposite the center electrode so as to perform the bending work on the ground electrode.
  • a spark plug manufacturing method is characterized in that, in the above-mentioned configurations , the deformation prevention means is configured such that the curved surface forming means and the inward deformation prevention means are united together.
  • a spark plug manufacturing method is characterized in that, in the above-mentioned configurations , the inward deformation prevention means and the outward deformation prevention means are disposed to face each other via the proximal end portion of the ground electrode.
  • a spark plug manufacturing method according to the present configuration is characterized in that, in the above-mentioned configurations , the spacing between the inward deformation prevention means and the outward deformation prevention means can be changed.
  • a spark plug manufacturing method is characterized in that, in any of the above-mentioned configurations 1 to 5, the curved surface forming means is disposed such that the center of curvature of the curved surface portion is located on the proximal end side of a plane including a front end surface of the center electrode with respect to the direction of the axis.
  • a spark plug manufacturing method is characterized in that, in any of the above-mentioned configurations 1 to 6, the bending process includes a gap adjustment step performed after the bending step so as to adjust a size of the spark discharge gap along a direction perpendicular to the axis by use of gap adjustment means capable of moving the distal end portion of the ground electrode in relation to the center electrode along a direction approximately perpendicular to the axis.
  • a spark plug manufacturing method is characterized in that, in the above-mentioned configuration 7, the gap adjustment means includes gap enlargement means which is disposed between a side portion of the center electrode and the proximal end portion of the ground electrode so as to relatively move the distal end portion of the ground electrode in a direction away from the center electrode, to thereby expand a size of the spark discharge gap along a direction perpendicular to the axis, wherein the gap enlargement means is disposed on a front end side of a plane including a front end surface of the insulator with respect to the direction of the axis.
  • a spark plug manufacturing method is characterized in that, in the above-mentioned configuration 7 or 8, in the gap adjustment step, restriction means is used to restrict at least relative movement of the distal end portion of the ground electrode in relation to the center electrode toward the front end side with respect to the direction of the axis.
  • a spark plug manufacturing method is characterized in that, in any of the above-mentioned configurations 1 to 9, the spark plug is configured such that a shortest distance between the center electrode and the ground electrode is formed between a front end edge portion or side surface portion of the center electrode and the distal end portion of the ground electrode.
  • Configuration 11 A spark plug manufacturing apparatus according to claim 11.
  • a spark plug manufacturing apparatus is characterized in that, in the above-mentioned configuration 11, the bending means is a roller which is supported for free rotation and which can move toward and away from the ground electrode along a direction approximately perpendicular to the axis.
  • a spark plug manufacturing apparatus is characterized in that, in the above-mentioned configuration 11 or 12, the deformation prevention means is configured such that the curved surface forming means and the inward deformation prevention means are united together.
  • a spark plug manufacturing apparatus is characterized in that, in the above-mentioned configuration 11 to 13, the inward deformation prevention means and the outward deformation prevention means are disposed to face each other during use via the proximal end portion of the ground electrode.
  • a spark plug manufacturing apparatus is characterized in that, in the above-mentioned configuration 11 to 14, the spacing between the inward deformation prevention means and the outward deformation prevention means can be changed.
  • a spark plug manufacturing apparatus is characterized in that, in any of the above-mentioned configurations 11 to 15, the curved surface forming means can be disposed such that during use the center of curvature of the curved surface portion is located on the proximal end side of a plane including a front end surface of the center electrode with respect to the direction of the axis.
  • a spark plug manufacturing apparatus is characterized in that, in any of the above-mentioned configurations 11 to 16, the bending apparatus further comprises gap adjustment means capable of moving the distal end portion of the ground electrode in relation to the center electrode along a direction approximately perpendicular to the axis, wherein the gap adjustment means adjusts a size of the spark discharge gap along a direction perpendicular to the axis.
  • a spark plug manufacturing apparatus is characterized in that, in the above-mentioned configuration 17, the gap adjustment means includes gap enlargement means which is disposed between a side portion of the center electrode and the proximal end portion of the ground electrode during use so as to relatively move the distal end portion of the ground electrode in a direction away from the center electrode, to thereby expand a size of the spark discharge gap along a direction perpendicular to the axis, wherein the gap enlargement means is disposed on a front end side of a plane including a front end surface of the insulator with respect to the direction of the axis.
  • a spark plug manufacturing apparatus is characterized in that, in the above-mentioned configuration 17 or 18, the gap adjustment means comprises restriction means for restricting at least relative movement of the distal end portion of the ground electrode in relation to the center electrode toward the front end side with respect to the direction of the axis.
  • a spark plug manufacturing apparatus is characterized in that, in any of the above-mentioned configurations 11 to 19, the spark plug is configured such that during use a shortest distance between the center electrode and the ground electrode is formed between a front end edge portion or side surface portion of the center electrode and the distal end portion of the ground electrode.
  • the curved surface forming means is disposed between the proximal end portion of the ground electrode and a side portion of the center electrode. That is, the curved surface portion, which serves as a reference for a bending position of the ground electrode, is disposed at a position closer to the proximal end of the ground electrode (position closer to the metallic shell) without being hindered by the center electrode. Therefore, even in a state in which the metallic shell and the insulator have been assembled together, the ground electrode can be bent relatively easily on the side toward the proximal end portion thereof. Furthermore, supporting the ground electrode by the deformation prevention means prevents leaning of the ground electrode toward the center electrode and swelling of the ground electrode toward the direction opposite the center electrode more reliably.
  • a bending punch or the like having an inclined surface for butting against the ground electrode can be used as the bending means for pressing the ground electrode against the curved surface portion.
  • the ground electrode since the ground electrode is bent while rubbing against the bending punch, the ground electrode may be scratched.
  • a method of obliquely pressing the ground electrode from the front end side with respect to the direction of the axis, and gradually changing the pressing direction in accordance with the degree of bending of the ground electrode may become complex.
  • the bending means is constituted by a roller which is movable in relation to the ground electrode along a direction approximately perpendicular to the axis and which is supported for free rotation. Therefore, the ground electrode can be pressed against the curved surface portion more reliably without changing the pressing direction of the ground electrode. Moreover, since the roller is supported for free rotation, there can be suppressed, to a possible extent, occurrence of a state in which the ground electrode bends while rubbing against the roller, whereby formation of scratches on the ground electrode can be prevented more reliably.
  • a film formed of diamond-like carbon may be provided on the outer circumferential surface of the roller and the bearing portion thereof so as to reduce the frictional coefficients thereof.
  • the inward deformation prevention means prevents deformation of the ground electrode toward the center electrode.
  • the curved surface forming means and the inward deformation prevention means which are disposed between the ground electrode and the center electrode, etc. in the bending step are united. Therefore, the apparatus can be prevented from becoming complex.
  • the deformation prevention means includes both the inward deformation prevention means and the outward deformation prevention means, deformation of the ground electrode in the bending step can be prevented more reliably.
  • the ground electrode can be supported more reliably, whereby deformation of the ground electrode in the bending step can be prevented more reliably.
  • the method of the present invention can cope with ground electrodes having different widths, and can prevent deformation of the ground electrode more reliably.
  • the curved surface forming means is disposed such that the center of curvature of the curved surface portion is located on the proximal end side of a plane including a front end surface of the center electrode with respect to the direction of the axis. Accordingly, the ground electrode can be bent at a position closer to the proximal end, and, in particular, lateral-discharge-type or inclined-discharge-type spark plugs can be manufactured relatively easily.
  • the size of the gap adjustment means along a direction perpendicular to the axis can be adjusted by the gap adjustment means. Therefore, the spark discharge gap can be formed more accurately.
  • the space formed between the ground electrode and the insulator is relatively small. Therefore, in the case where the gap enlargement means for relatively moving the ground electrode in a direction away from the center electrode is disposed in that space, the gap enlargement means restricts relative movement of the ground electrode toward the center electrode, and adjustment of the size of the spark discharge gap may become relatively difficult.
  • the gap enlargement means is disposed frontward of a plane containing the front end surface of the insulator with respect to the direction of the axis. That is, the gap enlargement means is disposed in a relatively large space between the center electrode and the ground electrode. Accordingly, the relative movement of the ground electrode toward the center electrode is not restricted by the gap enlargement means, whereby the size of the spark discharge gap can be adjusted more easily and more accurately.
  • the relative height of the distal end portion of the ground electrode in relation to the center electrode along the direction of the axis, the height having been adjusted in the bending step; i.e., the size of the spark discharge gap along the direction of the axis may deviate.
  • the restriction means restricts at least relative movement of the distal end portion of the ground electrode in relation to the center electrode toward the axially front end side.
  • the technical idea of the above-mentioned configuration 1 may be realized in the form of a spark plug manufacturing apparatus. In this case, an action and an effect basically the same as those of the above-mentioned configuration 1 can be attained.
  • FIG. 1 is a partially sectioned front view showing a spark plug 1.
  • the spark plug 1 is depicted in such a manner that the direction of an axis CL1 of the spark plug 1 coincides with the vertical direction in FIG. 1 .
  • the lower side of FIG. 1 will be referred to as the front end side of the spark plug 1
  • the upper side of FIG. 1 will be referred to as the rear end side of the spark plug 1.
  • the spark plug 1 is composed of a tubular ceramic insulator 2 serving as an insulator, a tubular metallic shell 3 which holds the ceramic insulator 2, etc.
  • the ceramic insulator 2 is formed from alumina or the like through firing.
  • the ceramic insulator 2 includes a rear-end-side trunk portion 10 formed on the rear end side; a larger diameter portion 11 projecting radially outward on the front end side of the rear-end-side trunk portion 10; and an intermediate trunk portion 12 formed on the front end side of the larger diameter portion 11 and having a diameter smaller than that of the larger diameter portion 11.
  • the ceramic insulator 2 further includes a leg portion 13 formed on the front end side of the intermediate trunk portion 12 and tapered off toward the front end side with respect to the direction of the axis CL1.
  • the larger diameter portion 11, the intermediate trunk portion 12, and the greater part of the leg portion 13 are accommodated within the metallic shell 3.
  • a tapered step portion 14 is formed at a connection portion between the leg portion 13 and the intermediate trunk portion 12. The ceramic insulator 2 is engaged with the metallic shell 3 at the step portion 14.
  • the ceramic insulator 2 has an axial hole 4 which penetrates the ceramic insulator 2 along the axis CL1.
  • a center electrode 5 is inserted into and fixed to a front end portion of the axial hole 4.
  • the center electrode 5 assumes a rod-like shape (cylindrical columnar shape) as a whole.
  • a flat front end portion of the center electrode 5 projects from the front end of the ceramic insulator 2.
  • the center electrode 5 is composed of an inner layer 5A formed of copper or a copper alloy, and an outer layer 5B formed of a nickel alloy whose predominant component is nickel (Ni).
  • a cylindrical columnar noble metal portion 31 formed of a noble metal alloy e.g., an iridium alloy
  • the noble metal portion 31 is provided through formation of a fused portion 41 by means of laser welding or the like performed along the periphery of the interface between the outer layer 5B and the noble metal portion 31 (see FIG. 2 , etc.).
  • a terminal electrode 6 is fixedly inserted into a rear end portion of the axial hole 4 such that the terminal electrode 6 projects from the rear end of the ceramic insulator 2.
  • a cylindrical columnar resistor 7 is disposed in the axial hole 4 between the center electrode 5 and the terminal electrode 6. Opposite ends of the resistor 7 are electrically connected to the center electrode 5 and the terminal electrode 6, respectively, via electrically conductive glass seal layers 8 and 9.
  • the metallic shell 3 is formed of metal such as low carbon steel and has a tubular shape.
  • a thread portion (external thread portion) 15 for mounting the spark plug 1 onto an engine head is formed on the outer circumferential surface thereof.
  • a seat portion 16 is formed on the outer circumferential surface located on the rear end side of the thread portion 15, and a ring-shaped gasket 18 is fitted into a thread neck portion 17 at the rear end of the thread portion 15.
  • a tool engagement portion 19 and a crimped portion 20 are provided at the rear end of the metallic shell 3.
  • the tool engagement portion 19 has a hexagonal cross section, and a tool, such as a wrench, is engaged with the tool engagement portion 19 when the metallic shell 3 is mounted to the engine head.
  • the crimped portion 20 holds the ceramic insulator 2 at the rear end portion.
  • a tapered step portion 21 with which the ceramic insulator 2 is engaged is provided on the inner circumferential surface of the metallic shell 3.
  • the ceramic insulator 2 is inserted into the metallic shell 3 from its rear end side toward the front end side.
  • a rear-end-side opening portion of the metallic shell 3 is crimped radially inward; i.e., the above-mentioned crimped portion 20 is formed, whereby the ceramic insulator 2 is fixed.
  • an annular plate packing 22 is interposed between the step portion 14 of the ceramic insulator 2 and the step portion 21 of the metallic shell 3.
  • annular ring members 23 and 24 are interposed between the metallic shell 3 and the ceramic insulator 2, and powder of talc 25 is charged into the space between the ring members 23 and 24. That is, the metallic shell 3 holds the ceramic insulator 2 via the plate packing 22, the ring members 23 and 24, and the talc 25.
  • a ground electrode 27 which is bent at an intermediate portion thereof toward the center electrode 5 is joined to a front end face of a front end portion 26 of the metallic shell 3.
  • the ground electrode 27 has a noble metal tip 32 provided on an inner surface of a distal end portion thereof, and a front end edge portion of the noble metal tip 32 faces a front end edge portion of the noble metal portion 31.
  • the shortest distance between the center electrode 5 (the noble metal portion 31) and the ground electrode 27 (the noble metal tip 32) is formed between the front end edge portion of the noble metal portion 31 and the front end edge portion of the noble metal tip 32, whereby a spark discharge gap 33, in which spark discharge occurs obliquely in relation to the axis CL1, is formed between the front end portion of the center electrode 5 and the distal end portion of the ground electrode 27.
  • spark discharge occurs generally along the axial direction. That is, the size of the spark discharge gap means a distance between the two electrodes as measured along the axial direction.
  • spark plug 1 since spark discharge occurs obliquely as described above, as shown in FIG.
  • the size of the spark discharge gap 33 is determined by a distance Gx between the two electrodes 5 and 27 as measured along a direction perpendicular to the axis CL1, and a distance Gy between the two electrodes 5 and 27 as measured along the axis CL1. Therefore, in order to set the spark discharge gap 33 to a predetermined size, not only the distance Gy, but also the distance Gx must be adjusted accurately when the ground electrode 27 is bent toward the center electrode 5.
  • a bending apparatus 51 which is the feature of the present invention and can adjust both the distances Gy and Gx.
  • the bending apparatus 51 is used in a process of manufacturing the spark plug 1 in order to bend the ground electrode 27 toward the center electrode 5, and set the size of the spark discharge gap 33 to a predetermined size.
  • the bending apparatus 51 includes a pre-bending apparatus 61, a main bending apparatus 71, and a gap adjustment apparatus 81.
  • the spark plug 1 is held by holding means (not shown) such that its front end portion is directed upward and the axis CL1 extends vertically, and is conveyed, by transport means such as a conveyer (not shown), to the pre-bending apparatus 61, the main bending apparatus 71, and the gap adjustment apparatus 81 in this sequence (indicated by arrows in FIG. 3 ).
  • each of the apparatuses 61, 71, and 81 has a positioning apparatus (not shown) for positioning the ground electrode 27 in a predetermined circumferential position.
  • the spark plug 1 is disposed on each of the apparatuses 61, 71, and 81 in a state in which the ground electrode 27 is positioned in the predetermined circumferential position by the positioning apparatus.
  • the pre-bending apparatus 61 pre-bends the ground electrode 27 of the spark plug 1 in an unbent state (straight bar like shape) (see FIG. 4 ) at a position corresponding to a bend portion (intermediate portion) of the ground electrode 27. That is, the pre-bending apparatus 61 performs pre-bending work on the ground electrode 27.
  • the pre-bending apparatus 61 includes first deformation prevention means 62 for preventing leaning of the ground electrode 27 toward the center electrode 5 and swelling of the ground electrode 27 toward the side opposite the center electrode 5; and a roller 63 serving as first bending means for bending the ground electrode 27.
  • the first deformation prevention means 62 includes first inward deformation prevention means 62A and first outward deformation prevention means 62B, each assuming the form of a bar and extending along the width direction of the ground electrode 27.
  • the first inward deformation prevention means 62A and the first outward deformation prevention means 62B are configured to be movable toward and away from the spark plug 1.
  • the first inward deformation prevention means 62A is disposed between the proximal end portion of the ground electrode 27 and a side portion of the center electrode 5, and the first outward deformation prevention means 62B is disposed such that it comes into contact with the outer surface of the proximal end portion of the ground electrode 27.
  • the deformation prevention means 62A and 62B have flat planar portions 64A and 64B, respectively.
  • the deformation prevention means 62A and 62B are disposed such that the planar portions 64A and 64B face each other and come into surface contact with the proximal end portion of the ground electrode 27.
  • the deformation prevention means 62A and 62B are supported at their proximal end portions by unillustrated coupling portions in a state in which the spacing between the two means can be changed.
  • the first inward deformation prevention means 62A has a triangular cross section at at least a portion thereof which comes into contact with the ground electrode 27.
  • a curved surface portion 65 is provided at a corner portion which connects the planar portion 64A and a side surface located at the upper side of a back surface of the planar portion 64A.
  • the curved surface portion 65 is a portion against which the inner surface of the ground electrode 27 is pressed when the ground electrode 27 is pre-bent by the roller 63, and has a shape corresponding to a bent shape of the ground electrode 27.
  • the first inward deformation prevention means 62A is configured such that means for forming a rough bent shape (curved shape) of the ground electrode 27 and means for preventing leaning of the ground electrode 27 toward the center electrode 5 are united together.
  • the curved surface portion 65 is disposed such that, when the pre-bending work is performed on the ground electrode 27, the center of curvature CC of the curved surface portion 65 is located on the proximal end side of a plane PL1 containing the front end surface of the center electrode 5 (the noble metal portion 31), with respect to the direction of the axis CL1.
  • the roller 63 has an outer circumferential surface of a predetermined width (e.g., 3 mm), and is supported for free rotation.
  • the roller 63 is configured such that it can be moved horizontally (in directions indicated by arrows in FIG. 5 ) by unillustrated moving means.
  • the roller 63 can move toward and press a side surface of the ground electrode 27 opposite the center electrode 5.
  • a film (not shown) formed of diamond-like carbon (DLC) is formed on a portion of the outer circumferential surface of the roller 63, which portion comes into contact with ground electrode 27, and a bearing portion of the roller 63.
  • the frictional coefficient of the surface of the film is 0.2 or less.
  • the main bending apparatus 71 bends the pre-bent ground electrode 27 at an approximately right angle (performs main bending work), and adjusts the relative height of the distal end portion of the ground electrode 27 (the noble metal tip 32), with respect to the direction of the axis CL1, in relation to the front end portion of the center electrode 5 (the noble metal portion 31).
  • the main bending apparatus 71 includes pressing means 72 serving as second bending means, and second deformation prevention means 73 for preventing deformation of the ground electrode 27.
  • the pressing means 72 is configured to be movable along the vertical direction, and performs the main bending work on the ground electrode 27 by pressing down the distal end portion of the ground electrode 27 toward the center electrode 5.
  • a lower surface portion 72A of the pressing means 72 which comes into contact with the ground electrode 27 at the time of the main bending work, is formed flat, and a film (not shown) formed of DLC is formed on the surface of the lower surface portion 72A. Therefore, the frictional coefficient of the lower surface portion 72A is relatively small.
  • the second deformation prevention means 73 includes second inward deformation prevention means 73A and second outward deformation prevention means 73B, each assuming the form of a bar and extending along the width direction of the ground electrode 27.
  • the second inward deformation prevention means 73A and the second outward deformation prevention means 73B are configured to be movable toward and away from the spark plug 1.
  • the second inward deformation prevention means 73A is disposed between the ground electrode 27 and the center electrode 5 or the like such that the second inward deformation prevention means 73A comes into contact with the inner surface of the proximal end portion of the ground electrode 27, and the second outward deformation prevention means 73B is disposed to come into contact with the outer surface of the proximal end portion of the ground electrode 27.
  • the deformation prevention means 73A and 73B have flat planar portions 74A and 74B. When the main bending work is performed, the planar portions 74A and 74B are disposed to come into surface contract with the proximal end portion of the ground electrode 27.
  • the deformation prevention means 73A and 73B are supported at their proximal end portions by unillustrated coupling portions in a state in which the spacing between the two means can be changed.
  • the main bending apparatus 71 further includes first illumination means (not shown) for projecting a predetermined light beam so as to illuminate a front end portion of the spark plug 1 (at least a front end portion of the center electrode 5 and a distal end portion of the ground electrode 27) with light; and first image capturing means (not shown) for capturing an image of the front end portion of the spark plug 1 irradiated with light.
  • the main bending apparatus 71 also includes control means (not shown) for acquiring the size of the gap between the two electrodes 5 and 27 (the noble metal portion 31 and the noble metal tip 32) from data representing the image captured by the first image capturing means, for calculating, on the basis of the size of the gap, an amount of pressing by the pressing means 72 (corresponding to an amount obtained through addition of an amount of springback to a deviation to be described later), and for controlling the pressing means 72 on the basis of the pressing amount.
  • control means for acquiring the size of the gap between the two electrodes 5 and 27 (the noble metal portion 31 and the noble metal tip 32) from data representing the image captured by the first image capturing means, for calculating, on the basis of the size of the gap, an amount of pressing by the pressing means 72 (corresponding to an amount obtained through addition of an amount of springback to a deviation to be described later), and for controlling the pressing means 72 on the basis of the pressing amount.
  • the control means calculates a deviation of the acquired size of the gap between the electrodes 5 and 27, as measured along the vertical direction, from a designed size of the spark discharge gap 33 along the direction of the axis CL1. Then, the main bending work is performed on the ground electrode 27 by means of causing the pressing means 72 to press downward the distal end portion of the ground electrode 27 by an amount obtained by adding the amount of springback to the deviation.
  • the spark discharge gap 33 is formed such that the relative height of the distal end portion (the noble metal tip 32) of the ground electrode 27 in relation to the front end portion of the center electrode 5 (the noble metal portion 31) becomes approximately equal to a designed relative height of the distal end portion of the ground electrode 27 in relation to the front end portion of the center electrode 5. That is, the spark discharge gap 33 is formed such that the distance Gy of the spark discharge gap 33 between the electrodes 5 and 27 as measured along the direction of the axis CL1 becomes equal to a designed distance Gy.
  • the gap adjustment apparatus 81 adjusts the distance Gx of the spark discharge gap 33, as measured along a direction perpendicular to the axis CL1, while maintaining the distance Gy of the spark discharge gap 33 along the axis CL1 adjusted by the main bending apparatus 71.
  • the gap adjustment apparatus 81 includes second image capturing means 82, gap adjustment means 83, restriction means 84, image processing means 85, and second illumination means (not shown) for projecting a predetermined light beam toward the front end portion of the spark plug 1.
  • the second image capturing means 82 captures an image of the front end portion of the spark plug 1 irradiated with light emitted from the second illumination means, and outputs data of the captured image to the image processing means 85.
  • the gap adjustment means 83 is composed of arms 83A and 83B, each assuming the form of a bar, extending along the width direction of the ground electrode 27, and having a rectangular cross section; and a coupling portion 83C which supports the arms 83A and 83B in a state in which they can move in horizontal directions (directions indicated by arrows in FIG. 7 ) (notably, the arm 83A corresponds to the gap enlargement means).
  • the gap adjustment means 83 is configured to be movable toward and away from the conveyed spark plug 1. When the above-mentioned distance Gx is adjusted, the two arms 83A and 83B approach the spark plug 1 and hold the ground electrode 27 therebetween. By means of moving the two arms 83A and 83B horizontally, the distance Gx can be adjusted.
  • the arm 83A is made thinner than the arm 83B, and the arm 83A is disposed on the front end side of a plane PL2 including the front end surface of the ceramic insulator 2, with respect to the direction of the axis CL1. That is, the arm 83A is disposed in a relatively large space between the center electrode 5 and the ground electrode 27.
  • the restriction means 84 is controlled by the image processing means 85, and has a flat lower surface portion 84A. A film (not shown) of DLC is formed on the lower surface portion 84A.
  • the restriction means 84 is configured to be movable along the vertical direction. When the distance Gx is adjusted, the lower surface portion 84A is immovably disposed at a position at which the lower surface portion 84A comes in contact with the distal end portion of the ground electrode 27. Thus, at the time of adjustment of the distance Gx by the gap adjustment means 83, relative movement (along the direction of the axis CL1) of the distal end portion of the ground electrode 27 in relation to the center electrode 5 can be restricted, whereby the distance Gy formed by the main bending apparatus 71 can be maintained.
  • the image processing means 85 controls operations of the gap adjustment means 83 and the restriction means 84 on the basis of the data of the image captured by the second image capturing means 82. More specifically, the image processing means 85 moves the two arms 83A and 83B horizontally by an amount which is obtained through addition of an amount of springback to a deviation of the distance (along the horizontal direction) between the distal end portion of the ground electrode 27 and the front end portion of the center electrode 5, obtained from the image data, in relation to the designed distance Gx of the spark discharge gap 33 along the direction perpendicular to the axis CL1.
  • the gap adjustment means 83 and the restriction means 84 are withdrawn from the spark plug 1
  • the image of the spark plug 1 is again captured by the image capturing means 82
  • the distances Gx and Gy of the spark discharge gap 33 are checked so as to determine whether or not the distances Gx and Gy are equal to the designed distances.
  • the work for bending the ground electrode 27 is completed.
  • the distance Gx is adjusted again by the gap adjustment means 83, and the distance Gy is adjusted again by the restriction means 84. That is, the restriction means 84 in the present embodiment not only can restrict the relative movement of the distal end portion of the ground electrode 27 toward the front end side with respect to the direction of the axis CL1, in relation to the center electrode 5, but also can adjust the distance Gy by pressing the distal end portion of the ground electrode 27 toward the center electrode 5.
  • the spark plug 1 whose ground electrode 27 has been positioned is conveyed to the pre-bending apparatus 61 by the above-described transport means.
  • the first deformation prevention means 62 then approaches the spark plug 1, and supports the proximal end portion of the ground electrode 27. Subsequently, the roller 63 moves toward the ground electrode 27 so as to press the ground electrode 27 against the curved surface portion 65, whereby pre-bending work is performed on the ground electrode 27. After that, the first deformation prevention means 62 and the roller 63 retreat from the spark plug 1.
  • the spark plug 1 having undergone the pre-bending work is conveyed to the main bending apparatus 71 by the transport means. Subsequently, an image of the front end portion of the spark plug 1 irradiated with light from the first illumination means is captured by the first image capturing means, and a pressing amount is calculated by the control means on the basis of data representing the captured image.
  • the second deformation prevention means 73 approaches the spark plug 1, and supports the proximal end portion of the ground electrode 27. The distal end portion of the ground electrode 27 is pressed by the pressing means 72 by the calculated pressing amount, whereby main bending work is performed on the ground electrode 27.
  • the ground electrode 27 is bent at an approximately right angle, and the distance Gy of the spark discharge gap 33 along the direction of the axis CL1 is formed.
  • the pressing means 72 and the second deformation prevention means 73 retreat from the spark plug 1.
  • the spark plug 1 having undergone the main-bending work is conveyed to the gap adjustment apparatus 81 by the transport means. Subsequently, an image of the front end portion of the spark plug 1 irradiated with light from the second illumination means is captured by the second image capturing means 82. Subsequently, on the basis of data representing the image captured by the second image capturing means 82, the gap adjustment means 83 and the restriction means 84 are disposed at predetermined positions by the image processing mean 84. Subsequently, the distance Gx is adjusted by the gap adjustment means 83, while the distance Gy is maintained by the restriction means 84.
  • the gap adjustment means 83 and the restriction means 84 retreat from the spark plug 1, and the second image capturing means 82 again captures the image of the front end portion of the spark plug 1.
  • the distances Gx and Gy are adjusted again by the gap adjustment means 83 and the restriction means 84 on the basis of data representing the re-captured image.
  • the spark discharge gap 33 is formed to have a predetermined size (approximately equal to the designed size), whereby bending of the ground electrode 27 is completed.
  • the curved surface portion 65 As described above, according to the present embodiment, at the time of (pre-) bending work, means for forming a curved surface (the curved surface portion 65) is disposed between the proximal end portion of the ground electrode 27 and a side portion of the center electrode 5. That is, the curved surface portion 65, which serves as a reference for a bending position of the ground electrode 27, can be disposed at a position closer to the proximal end (position closer to the metallic shell 3) without being hindered by the center electrode 5. Therefore, even in a state in which the metallic shell 3 and the ceramic insulator 2 have been assembled together, the ground electrode 27 can be bent relatively easily on the side toward the proximal end portion thereof. Furthermore, supporting the ground electrode 27 by the first deformation prevention means 62 more reliably prevents leaning of the ground electrode 27 toward the center electrode 5 and swelling of the ground electrode 27 toward the direction opposite the center electrode 5.
  • the relative height of the distal end portion of the ground electrode 27 in relation to the front end portion of the enter electrode 5 along the direction of the axis CL1 is adjusted on the basis of the actual position of the front end portion of the enter electrode 5.
  • the size of the spark discharge gap 33 as measured along the direction of the axis CL1 can be adjusted more accurately.
  • supporting the ground electrode 27 by the second deformation prevention means 73 more reliably prevents leaning and swelling of the ground electrode 27.
  • the size of the spark discharge gap 33 as measured along the direction perpendicular to the axis CL1 can be adjusted by the gap adjustment apparatus 81. That is, in the main bending apparatus 71, the size of the spark discharge gap 33 as measured along the direction of the axis CL1 can be set to a predetermined size, and, in the gap adjustment apparatus 81, the size of the spark discharge gap 33 as measured along the direction perpendicular to the axis CL1 can be adjusted. Therefore, the spark discharge gap 33 can be formed accurately.
  • the first bending means is the roller 63, which can move relative to the ground electrode 27 along a direction approximately perpendicular to the axis CL1 and is supported for free rotation. Therefore, the ground electrode 27 can be pressed against the curved surface portion 65 more reliably, without changing the pressing direction of the ground electrode 27. Moreover, since the roller 63 is supported for free rotation, there can be suppressed, to a possible extent, occurrence of a state in which the ground electrode 27 bends while rubbing against the roller 63, whereby formation of scratches on the ground electrode 27 can be prevented more reliably.
  • a film formed of DLC is provided on the outer circumferential surface of the roller 63 and the bearing portion thereof.
  • the curved surface portion 65 and the first inward deformation prevention means 62A to be disposed between the ground electrode 27 and the center electrode 5, etc. are united together. Therefore, the apparatus can be prevented from becoming complex.
  • the curved surface portion 65 is disposed such that the center of curvature CC of the curved surface portion 65 is located on the proximal end side of the plane PL1 containing the front end surface of the center electrode 5, with respect to the direction of the axis CL1. Accordingly, the ground electrode 27 can be bent at a position closer to the proximal end, whereby lateral-discharge-type or inclined-discharge-type spark plugs can be manufactured relatively easily.
  • the arm 83A is disposed frontward of a plane containing the front end surface of the ceramic insulator 2 with respect to the direction of the axis CL1. That is, the arm 83A is disposed in a relatively large space between the center electrode 5 and the ground electrode 27. Accordingly, the relative movement of the ground electrode 27 toward the center electrode 5 is not restricted by the presence of the arm 83A, whereby the size of the spark discharge gap 33 can be adjusted more easily and more accurately.
  • the restriction means 84 restricts at least the relative movement of the distal end portion of the ground electrode 27 in relation to the center electrode 5 toward the front end side with respect to the direction of the axis CL1. As a result, there can be prevented a deviation of the distance Gy of the spark discharge gap 33 along the direction of the axis CL1, whereby the size of the spark discharge gap 33 can be adjusted more accurately.
  • the present invention is not limited to the details of the above-described embodiment, and may be practiced as follows. Needless to say, other application examples and medications which are not exemplified bellow are also possible.

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Claims (20)

  1. Procédé de fabrication d'une bougie d'allumage destiné à la fabrication d'une bougie d'allumage (1) comprenant :
    une électrode centrale en forme de tige (5) s'étendant dans le sens d'un axe (CL1) ;
    un isolateur tubulaire approximativement cylindrique (2) présentant un trou axial (4) s'étendant dans le sens de l'axe (CL1), l'électrode centrale (5) étant prévue à une partie d'extrémité avant du trou axial (4) ;
    une enveloppe métallique tubulaire approximativement cylindrique (3) entourant l'isolateur (2) ; et
    une électrode de masse (27) dont la partie d'extrémité proximale est jointe à l'enveloppe métallique (3), et qui est fléchie au niveau de sa partie intermédiaire afin de former un espace de décharge d'étincelle (33) entre une partie d'extrémité distale de l'électrode de masse (27) et une partie d'extrémité avant de l'électrode centrale (5),
    le procédé comprenant un procédé de flexion pour fléchir une électrode de masse non fléchie (27) vers l'axe (CL1) dans un état sous lequel l'enveloppe métallique (3) avec l'électrode de masse non fléchie (27) jointe à celle-ci et l'isolateur (2) dans lequel l'électrode centrale (5) est prévue sont assemblés ensemble, où
    le procédé de flexion comprend une étape de flexion comprenant
    la mise en place d'un moyen de formation d'une surface incurvée présentant une partie de surface incurvée (65) correspondant à une forme fléchie de l'électrode de masse (27) entre une partie latérale de l'électrode centrale (5) et la partie d'extrémité proximale de l'électrode de masse (27),
    soutenant l'électrode de masse (27) sur une partie latérale de la partie d'extrémité proximale localisée sur le côté vers l'électrode centrale (5) par un moyen de prévention de déformation vers l'intérieur (62A) d'un moyen de prévention de déformation (62) afin d'empêcher la déformation de la partie d'extrémité proximale de l'électrode de masse (27) vers l'électrode centrale (5),
    soutenant l'électrode de masse (27) sur une partie latérale de la partie d'extrémité proximale opposée à l'électrode centrale (5) par un moyen de prévention de déformation vers l'extérieur (62B) d'un moyen de prévention de déformation (62) afin d'empêcher la déformation de la partie d'extrémité proximale de l'électrode de masse (27) vers un côté opposé à l'électrode centrale (5),
    la compression de l'électrode de masse (27) contre la partie de surface incurvée (65) depuis le côté opposé à l'électrode centrale (5) en utilisant un moyen de flexion (63), moyennant quoi le travail de flexion est exécuté sur l'électrode de masse (27).
  2. Procédé de fabrication d'une bougie d'allumage selon la revendication 1, le moyen de flexion (63) étant un rouleau qui est configuré pour être mobile par rapport à l'électrode de masse (27) le long d'un sens approximativement perpendiculaire à l'axe (CL1) et qui est supporté par rotation libre, et une surface circonférentielle externe du rouleau (63) est pressée contre une surface latérale de l'électrode de masse (27) opposée à l'électrode centrale (5) afin d'exécuter le travail de flexion sur l'électrode de masse (27).
  3. Procédé de fabrication d'une bougie d'allumage selon l'une quelconque des revendications précédentes, dans lequel le moyen de prévention de déformation (62) est configuré de sorte que le moyen de formation de surface incurvée (65) et le moyen de prévention de déformation vers l'intérieur (62A) soient réunis.
  4. Procédé de fabrication d'une bougie d'allumage selon l'une quelconque des revendications précédentes, dans lequel le moyen de prévention de déformation vers l'intérieur (62A) et le moyen de prévention de déformation vers l'extérieur (62B) sont disposés pour se faire face l'un à l'autre via la partie d'extrémité proximale de l'électrode de masse (27).
  5. Procédé de fabrication d'une bougie d'allumage selon l'une quelconque des revendications précédentes, dans lequel l'espace entre le moyen de prévention de déformation vers l'intérieur (62A) et le moyen de prévention de déformation vers l'extérieur (62B) peut être modifié.
  6. Procédé de fabrication d'une bougie d'allumage selon l'une quelconque des revendications 1 à 5, dans lequel le moyen de formation de surface incurvée est disposé de sorte que le centre de courbure de la partie de surface incurvée (65) soit localisé sur le côté d'extrémité proximale d'un plan comprenant une surface d'extrémité avant de l'électrode centrale (5) par rapport au sens de l'axe (CL1).
  7. Procédé de fabrication d'une bougie d'allumage selon l'une quelconque des revendications 1 à 6, dans lequel le procédé de flexion comprend une étape d'ajustement d'espace exécutée après l'étape de flexion afin d'ajuster une taille de l'espace de décharge d'étincelle (33) le long d'un sens perpendiculaire à l'axe (CL1) en utilisant un moyen d'ajustement d'espace (81) capable de déplacer la partie d'extrémité distale de l'électrode de masse (27) en relation avec l'électrode centrale (5) le long d'un sens approximativement perpendiculaire à l'axe (CL1).
  8. Procédé de fabrication d'une bougie d'allumage selon la revendication 7, dans lequel le moyen d'ajustement d'espace (81) comprend un moyen d'élargissement d'espace (83A) qui est disposé entre une partie latérale de l'électrode centrale (5) et la partie d'extrémité proximale de l'électrode de masse (27) afin de relativement déplacer la partie d'extrémité distale de l'électrode de masse (27) dans un sens opposé à l'électrode centrale (5), pour étendre de là une taille de l'espace de décharge d'étincelle (33) le long d'un sens perpendiculaire à l'axe (CL1),
    où le moyen d'élargissement d'espace (83A) est disposé sur un côté d'extrémité avant d'un plan comprenant une surface d'extrémité avant de l'isolateur (2) par rapport au sens de l'axe (CL1).
  9. Procédé de fabrication d'une bougie d'allumage selon la revendication 7 ou 8, dans lequel, dans l'étape d'ajustement d'espace, un moyen de restriction (84) est utilisé pour restreindre au moins le mouvement relatif de la partie d'extrémité distale de l'électrode de masse (27) par rapport à l'électrode centrale (5) vers le côté d'extrémité avant par rapport au sens de l'axe (CL1).
  10. Procédé de fabrication d'une bougie d'allumage selon l'une quelconque des revendications 1 à 9, dans lequel la bougie d'allumage (1) est configurée afin qu'une distance plus courte entre l'électrode centrale (5) et l'électrode de masse (27) soit formée entre une partie de bord d'extrémité avant ou une partie de surface latérale de l'électrode centrale (5) et la partie d'extrémité distale de l'électrode de masse (27).
  11. Appareil de fabrication d'une bougie d'allumage utilisé pour la fabrication d'une bougie d'allumage (1) comprenant :
    une électrode centrale type tige (5) s'étendant dans le sens d'un axe (CL1) ;
    un isolateur tubulaire approximativement cylindrique (2) ayant un trou axial (4) s'étendant dans le sens de l'axe (CL1), l'électrode centrale (5) étant prévue au niveau d'une partie d'extrémité avant du trou axial (4) ;
    une enveloppe métallique tubulaire approximativement cylindrique (3) entourant l'isolateur (2) ; et
    une électrode de masse (27) dont la partie d'extrémité proximale est jointe à l'enveloppe métallique (3), et qui est fléchie au niveau d'une partie intermédiaire de celle-ci afin de former un espace de décharge d'étincelle (33) entre une partie d'extrémité distale de l'électrode de masse (27) et une partie d'extrémité avant de l'électrode centrale (5),
    l'appareil comprenant un appareil de flexion (51(61)) pour fléchir une électrode de masse en forme de barre droite (27) vers l'axe (CL1) dans un état dans lequel l'enveloppe métallique (3) avec l'électrode de masse en forme de barre droite (27) jointe à celle-ci et l'isolateur (2) dans lequel l'électrode centrale (5) est prévue sont assemblés ensemble, où
    l'appareil de flexion (51(61)) comprend :
    un moyen de formation de surface incurvée qui présente une partie de surface incurvée (65) correspondant à une forme fléchie de l'électrode de masse (27) et qui est disposé entre une partie latérale de l'électrode centrale (5) et la partie d'extrémité proximale de l'électrode de masse (27) ;
    un moyen de prévention de déformation (62) incluant un moyen de prévention de déformation vers l'intérieur (62A) qui est disposé entre une partie latérale de l'électrode centrale (5) et la partie d'extrémité proximale de l'électrode de masse (27) durant l'utilisation afin de soutenir une partie latérale de la partie d'extrémité proximale de l'électrode de masse (27) localisée sur le côté vers l'électrode centrale (5) pour empêcher la déformation de la partie d'extrémité proximale de l'électrode de masse (27) vers l'électrode centrale (5) ;
    le moyen de prévention de déformation (62) comprenant en outre un moyen de prévention de déformation vers l'extérieur (62B) qui est disposé sur un côté de l'électrode de masse (27) opposé à l'électrode centrale (5) durant l'utilisation afin de soutenir une partie latérale de la partie d'extrémité proximale de l'électrode de masse (27) opposée à l'électrode centrale (5) pour empêcher la déformation de la partie d'extrémité proximale de l'électrode de masse (27) vers un côté opposé à l'électrode centrale (5) ; et
    un moyen de flexion (63) pour comprimer l'électrode de masse (27) contre la partie de surface incurvée (65) du moyen de formation de surface incurvée depuis un côté opposé à l'électrode centrale (5).
  12. Appareil de fabrication d'une bougie d'allumage selon la revendication 11, dans lequel le moyen de flexion (63) est un rouleau qui est soutenu par rotation libre et qui peut se déplacer vers et à l'opposé de l'électrode de masse (27) le long d'un sens approximativement perpendiculaire à l'axe (CL1).
  13. Appareil de fabrication d'une bougie d'allumage selon l'une quelconque des revendications 11 et 12, dans lequel le moyen de prévention de déformation (62) est configuré afin que le moyen de formation de surface incurvée (65) et le moyen de prévention de déformation vers l'intérieur (62A) soient réunis.
  14. Appareil de fabrication d'une bougie d'allumage selon l'une quelconque des revendications 11 à 13, dans lequel le moyen de prévention de déformation vers l'intérieur (62A) et le moyen de prévention de déformation vers l'extérieur (62B) sont disposés pour se faire face l'un à l'autre durant l'utilisation via la partie d'extrémité proximale de l'électrode de masse (27).
  15. Appareil de fabrication d'une bougie d'allumage selon l'une quelconque des revendications 11 à 14, dans lequel l'espace entre le moyen de prévention de déformation vers l'intérieur (62A) et le moyen de prévention de déformation vers l'extérieur (62B) peut être changé.
  16. Appareil de fabrication d'une bougie d'allumage selon l'une quelconque des revendications 11 à 15, dans lequel le moyen de formation de surface incurvée peut être disposé de sorte que durant l'utilisation le centre de courbure de la partie de surface incurvée (65) soit localisé sur le côté d'extrémité proximale d'un plan comprenant une surface d'extrémité avant de l'électrode centrale (5) par rapport au sens de l'axe (CL1).
  17. Appareil de fabrication d'une bougie d'allumage selon l'une quelconque des revendications 11 à 16, dans lequel l'appareil de flexion (51) comprend en outre un moyen d'ajustement d'espace (81) capable de déplacer la partie d'extrémité distale de l'électrode de masse (27) par rapport à l'électrode centrale (5) le long d'un sens approximativement perpendiculaire à l'axe (CL1), où le moyen d'ajustement d'espace (81) ajuste une taille de l'espace de décharge d'étincelle (33) le long d'un sens perpendiculaire à l'axe (CL1).
  18. Appareil de fabrication d'une bougie d'allumage selon la revendication 17, dans lequel le moyen d'ajustement d'espace (81) comprend un moyen d'élargissement d'espace (83A) qui est disposé entre une partie latérale de l'électrode centrale (5) et la partie d'extrémité proximale de l'électrode de masse (27) durant l'utilisation afin de relativement déplacer la partie d'extrémité distale de l'électrode de masse (27) dans un sens éloigné de l'électrode centrale (5) afin d'étendre de là une taille de l'espace de décharge d'étincelle (33) le long d'un sens perpendiculaire à l'axe (CL1),
    où le moyen d'élargissement d'espace (83A) est disposé sur un côté d'extrémité avant d'un plan comprenant une surface d'extrémité avant de l'isolateur (2) par rapport au sens de l'axe (CL1).
  19. Appareil de fabrication d'une bougie d'allumage selon la revendication 17 ou 18, dans lequel le moyen d'ajustement d'espace (81) comprend un moyen de restriction (84) pour restreindre au moins le mouvement relatif de la partie d'extrémité distale de l'électrode de masse (27) par rapport à l'électrode centrale (5) vers le côté d'extrémité avant par rapport au sens de l'axe (CL1).
  20. Appareil de fabrication d'une bougie d'allumage selon l'une quelconque des revendications 11 à 19, dans lequel la bougie d'allumage (1) est configurée de sorte que durant l'utilisation une distance plus courte entre l'électrode centrale (5) et l'électrode de masse (27) soit formée entre une partie de bord d'extrémité avant ou une partie de surface latérale de l'électrode centrale (5) et la partie d'extrémité distale de l'électrode de masse (27).
EP09818919.4A 2008-10-06 2009-09-24 Procede de fabrication de bougie d'allumage et dispositif de fabrication de bougie d'allumage Not-in-force EP2337172B1 (fr)

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JP2008260047A JP5134486B2 (ja) 2008-10-06 2008-10-06 スパークプラグの製造方法及びスパークプラグの製造装置
PCT/JP2009/004795 WO2010041379A1 (fr) 2008-10-06 2009-09-24 Procédé de fabrication de bougie d'allumage et dispositif de fabrication de bougie d'allumage

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EP2337172A1 (fr) 2011-06-22
JP2010092669A (ja) 2010-04-22
CN102160247A (zh) 2011-08-17
JP5134486B2 (ja) 2013-01-30
CN102160247B (zh) 2013-07-31
WO2010041379A1 (fr) 2010-04-15
EP2337172A4 (fr) 2013-11-13

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