JP4723237B2 - Spark plug welding apparatus, spark plug manufacturing apparatus, method for welding noble metal tip to unbent spark plug, and spark plug manufacturing method - Google Patents

Description

  The present invention relates to a spark plug welding apparatus for welding a cylindrical noble metal tip to an outer electrode that performs a spark discharge with a center electrode, and a spark plug manufacturing apparatus using the spark plug welding apparatus. The present invention also relates to a method for welding a noble metal tip to an unbent spark plug and a method for manufacturing a spark plug including the same.

As a spark plug, one obtained by welding a cylindrical noble metal tip to an outer electrode is known for improving durability.
Further, as a welding apparatus for welding the noble metal tip to the outer electrode, for example, for an unbent spark plug in which the outer electrode is in a state before being bent, out of the noble metal tips arranged at the planned welding portion on the inner surface of the outer electrode. The center of the joining end surface that contacts the inner surface of the outer electrode is made to coincide with the rotation axis. And what rotates the whole unbent spark plug and welds a noble metal tip to an outer electrode by irradiating the peripheral edge of the joint end face of the noble metal tip from an oblique direction intersecting the rotation axis is known. .

JP 2001-135456 A

However, in this type of spark plug welding device, before welding, the outer electrode and the noble metal tip are imaged using a camera having an imaging optical axis that is coaxial with the laser optical axis provided in the laser irradiation device, and the image Based on the above, the noble metal tip (unbent spark plug) is moved so that the center of the joining end face coincides with the rotation axis. For this reason, the noble metal tip is imaged from an oblique direction with respect to its axis, and it is difficult to align the rotation axis and the center of the joining end surface of the noble metal tip.
Therefore, in a state where the alignment is not yet completed, the spark plug is once rotated, and the movement of the noble metal tip (periphery of the joint end face) is confirmed with a camera, and the moving direction of the noble metal tip (unbent spark plug) And the amount of movement is calculated. Then, based on the calculation result, the unbent spark plug is moved, and for further confirmation, the unbend spark plug is rotated again to determine whether the motion of the imaged noble metal tip is correct. .
If the position of the noble metal tape is not appropriate at this time, the movement and the rotation of the spark plug are repeated again.
Thus, in order to align the noble metal tip (unbent spark plug), it is necessary to rotate the spark plug at least twice, which increases the number of steps in the welding process and increases the cost.

  The present invention has been made in view of such a problem, and provides a spark plug welding apparatus capable of efficiently welding a noble metal tip to an outer electrode, and a spark plug manufacturing apparatus using the spark plug welding apparatus. It is an object of the present invention to provide a method for welding a noble metal tip to a good unbent spark plug and a method for manufacturing a spark plug including the same.

The first solution is a center electrode, a metal shell that surrounds the center electrode in an annular shape, and an outer electrode that has one end fixed to the front end surface of the metal shell, at least after the bending process that is performed later Is an unbent spark plug having an outer electrode including a flat inner surface facing the center electrode, and a cylindrical noble metal tip is joined to a portion to be welded on the flat inner surface of the outer electrode. A spark plug welding device for welding in a state in which an end face is in contact with the flat inner surface, the imaging means having an imaging optical axis, and taking a picture, and the flat inner surface of the outer electrode is the imaging device. The fixing means for fixing the unbent spark plug to itself and the fixing means can be moved in a plane direction parallel to the flat inner surface of the outer electrode while being orthogonal to the optical axis and facing the imaging means side. age A plane direction moving means, and a rotation means having a rotation axis parallel to the imaging optical axis, and the fixing means and the plane direction movement means being rotatable about the rotation axis; A laser irradiation apparatus that emits laser light, wherein a laser optical axis of the laser light obliquely intersects the imaging optical axis, the unbent spark plug is fixed by the fixing means, and the unbent together with the fixing means The spark plug is moved by the plane direction moving means, and the noble metal tip disposed in a state where the joining end face is in contact with the planned welding portion of the flat inner surface, the center of the joining end face is used as the rotation axis. When matched, the laser optical axis coincides with any part of the peripheral edge of the joining end surface of the noble metal tip. In this state, the rotating means and the plane direction moving means and the fixing means Both of the laser irradiation devices are arranged so that laser light is irradiated over the entire periphery of the joint end surface of the noble metal tip when the unbent spark plug is rotated around the rotation axis. The imaging means is a spark plug welding device that images at least the noble metal tip and its periphery in the state where the center of the joint end surface of the noble metal tip is aligned with the rotation axis.

Since this welding apparatus has the above-described configuration, the unbent spark plug is fixed, the position of the noble metal tip arranged at the planned welding portion is confirmed by the imaging means, and the center of the joining end face of the noble metal tip is When moved in the plane direction so as to coincide with the rotation axis, the laser optical axis coincides with any one of the peripheral edges of the joining end surface of the noble metal tip. Therefore, by irradiating the laser beam while rotating the spark plug around the rotation axis by the rotation means, the peripheral edge of the joining end surface of the noble metal tip is spread over the entire circumference of the outer electrode by the laser beam. It can be welded to the flat inner surface.
Thus, if this welding device is used, it is not necessary to rotate the unbent spark plug and check the position of the noble metal tip, and the positioning of the unbent spark plug is easy and can be done in a short time. Time required for welding can be shortened, work efficiency can be improved, and cost can be reduced.

  Further, when the unbent spark plug is rotated around the rotation axis, the laser beam is irradiated on the entire periphery of the joint end surface of the noble metal tip without hitting the center electrode and the metal shell. As shown, a laser irradiation device is arranged. Therefore, the joint end surface of the noble metal tip can be welded to the outer electrode uniformly and reliably over the entire circumference.

Furthermore, it is preferable that the laser irradiation apparatus is arranged so that the laser optical axis intersects the rotation axis. In this case, since the laser beam is irradiated from the direction orthogonal to the tangent to the joint end surface of the noble metal tip, the energy of the laser beam is injected toward the inner side in the radial direction of the noble metal tip, and welding is performed. Since it is performed to a deeper part toward the inner side in the radial direction, appropriate welding can be performed efficiently.

  The unbent spark plug refers to a spark plug in an unfinished state that becomes a spark plug that is externally completed by bending the outer electrode after the unbent spark plug is completed. Further, the flat inner surface of the outer electrode may occupy the entire inner surface of the outer electrode in the unbent spark plug or may be a part thereof.

  Furthermore, the spark plug welding device may be a spark plug welding device in which the imaging optical axis and the rotation axis are coaxial.

In this welding apparatus, the imaging optical axis and the rotation axis are coaxial. In this way, when the joint end surface of the noble metal tip is a surface orthogonal to the axis of the noble metal tip, the center of the tip surface opposite to the joint end surface of the imaged noble metal tip is the imaging light. If it is moved in the plane direction by the plane direction moving means so as to be located at the center of the axis, the center of the joining end face of the noble metal tip coincides with the rotation axis (and hence also the imaging optical axis). Therefore, alignment can be further facilitated.
Also, when welding precious metal tips with different height dimensions, if the alignment is performed by moving the noble metal tip in the plane direction so that the center of the tip surface of the precious metal tip coincides with the imaging optical axis, Regardless of the direction dimension, highly accurate alignment is possible.

  Further, in any of the above spark plug welding apparatuses, the fixing means may be a spark plug welding apparatus which is a fixing means for holding the outer electrode and fixing the unbent spark plug. .

  In this welding apparatus, the outer electrode of the unbent spark plug is held and the unbent spark plug is fixed to perform welding. For this reason, since a very close portion of the planned welding portion is held, it is arranged in the planned welding portion and here as compared to the case where other portions (for example, the metal shell) of the unbent spark plug are held and fixed. The variation in the position of the precious metal tip thus made can be reduced. For this reason, since the distance which moves an unbent spark plug to a plane direction for position alignment can be made small, position alignment can be completed in a short time, and welding of an unbend spark plug can be performed efficiently.

  Further, in the spark plug welding apparatus according to any one of the above, the fixing means applies at least a part of a portion of the flat inner side surface of the outer electrode excluding the planned welding portion and its peripheral edge. It is preferable that the outer electrode of the unbent spark plug is in contact with the spark plug welding device including a rotation axis direction reference surface for positioning in the rotation axis direction along the axis of the rotation axis.

When the unbent spark plug is fixed, if the flat inner surface of the outer electrode or the position of the noble metal tip in the rotational axis direction is shifted, the irradiation position of the laser beam is relatively shifted, and appropriate welding cannot be performed. There is a fear.
On the other hand, in this welding apparatus, since the fixing means includes the rotational axis direction reference surface, a part of the flat inner surface of the outer electrode of the unbent spark plug is brought into contact with the rotational axis direction reference surface. Thus, the positioning of the flat inner surface in the rotation axis direction can be performed. Therefore, according to this apparatus, since the position shift of the flat inner surface in the rotation axis direction does not occur, the noble metal tip can be appropriately welded to the flat inner surface.

  Further, in the spark plug welding apparatus according to any one of the above, the fixing means abuts the front end surface of the outer electrode, and the axis of the center electrode with respect to the outer electrode of the unbent spark plug. And a spark plug welding device including a reference surface in the central axis direction for positioning in the central axis direction.

Similar to the above, in the fixed unbent spark plug, if the flat inner surface of the outer electrode or the position of the central axis direction of the noble metal tip is shifted, the irradiation position of the laser beam is relatively shifted, and the appropriate There is a risk that proper welding cannot be performed.
On the other hand, in this welding apparatus, since the fixing means includes the central axial direction reference surface, the center of the distal end surface can be obtained by bringing the distal end surface of the outer electrode of the unbent spark plug into contact with the central axial reference surface. The electrode can be positioned in the axial direction. Therefore, according to this apparatus, the flat inner side surface of the outer electrode and the noble metal tip are not displaced in the central axis direction, so that the noble metal tip can be appropriately welded to the flat inner side surface.

  Another solution is that a center electrode, a metal shell that surrounds the center electrode in an annular shape, and one end of the metal shell is fixed to the front end surface of the metal shell, and the inner surface of the center electrode faces the front end surface of the center electrode. A cylindrical noble metal tip is welded to a position facing the center electrode on the inner side surface of the outer electrode, and a space between the noble metal tip and the center electrode. An apparatus for manufacturing a spark plug in which a spark discharge gap is formed, and the spark plug manufacturing apparatus including the spark plug welding apparatus according to any one of the above.

  This spark plug manufacturing apparatus includes the spark plug welding apparatus described above. For this reason, when welding the noble metal tip to the outer electrode, positioning of the unbent spark plug is easy and can be completed in a short time, so that the time required for the welding process can be shortened. Accordingly, the spark plug manufacturing apparatus has high manufacturing efficiency.

Another solution is a center electrode, a metal shell that surrounds the center electrode in an annular shape, and an outer electrode having one end fixed to the front end surface of the metal shell, and at least after the bending process described above An unbent spark plug having an outer electrode including a flat inner flat surface facing the center electrode side, of which the circular inner surface of the outer electrode perpendicular to the axis of the noble metal tip is welded to a portion to be welded. A method of welding a noble metal tip to an unbent spark plug, in which a columnar noble metal tip is welded to the flat inner surface in a state where the joining end face is in contact with the flat inner surface, and the unbent spark plug is fixed. And an imaging means having an imaging optical axis orthogonal to the flat inner surface of the outer electrode, and the precious metal chip disposed on the planned welding portion of the flat inner surface. And moving the unbent spark plug in a plane direction parallel to the flat inner surface so that the image of the noble metal tip is located at a predetermined position on the imaging screen; While rotating the unbent spark plug around a rotation axis that is orthogonal to the inner surface and passes through the center of the joining end face of the noble metal tip, laser light is emitted to any part of the joining end face of the noble metal tip. Irradiating an optical axis so as to obliquely intersect the imaging optical axis, and welding the noble metal tip to the flat inner surface over the entire periphery of the joint end surface of the noble metal tip. This is a method for welding a noble metal tip to an unbent spark plug.

In the method for welding a noble metal tip to an unbent spark plug according to the present invention, the nobend spark tip is fixed and the noble metal tip arranged at the planned welding portion by an imaging means having an imaging optical axis perpendicular to the flat inner surface of the outer electrode. Image. For this reason, unlike the conventional case where the noble metal tip has an imaging optical axis that is oblique with respect to its axis, that is, the imaging means that obliquely intersects the flat inner surface, the tip of the noble metal tip is opposite to the joint end face. The image is taken from the surface side.
Therefore, it is easy to calculate the moving direction and the moving amount when the unbent spark plug is moved in the plane direction so that the image of the noble metal tip is located at a predetermined position on the imaging screen. Further, it is not necessary to rotate the unbent spark plug for position confirmation. After this movement, the periphery of the joint end surface of the noble metal tip is irradiated by irradiating laser light to any part of the joint end surface of the noble metal tip while rotating the unbent spark plug around the pivot shaft. The entire inner circumference can be welded to the flat inner surface of the outer electrode by laser light.
Thus, according to this method, alignment of the unbent spark plug is easy and can be completed in a short time, so that the time required for the welding process can be shortened and work efficiency can be improved.

  As for the relationship between the imaging optical axis and the rotation axis, the distance from the flat inner surface to the imaging means is 10 in relation to the distance between the imaging optical axis and the rotation axis parallel to the imaging optical axis. It is preferable to set a sufficiently large value that is twice or more. Since the imaging means can face the front end surface of the noble metal tip, or can face almost the same as when the noble metal tip is imaged by an imaging means having an imaging optical axis that coincides with its axis, the amount of movement, etc. This is because the calculation is easy.

Further, in the method for welding a noble metal tip to the unbent spark plug, the imaging optical axis and the rotation axis are coaxial, and in the parallel movement step, the center of the image of the tip surface of the noble metal tip It is preferable to use a method for welding a noble metal tip to an unbent spark plug, in which the unbend spark plug is moved so as to coincide with the image position corresponding to the imaging optical axis.

In this method of welding the noble metal tip to the unbent spark plug, the imaging optical axis and the rotation axis are further coaxial. For this reason, if the unbent spark plug is moved in the plane direction by the plane direction moving means so that the center of the image of the tip surface of the imaged noble metal tip is located at the center of the imaging optical axis, the noble metal tip is joined. Since the center of the end face coincides with the rotation axis (and therefore also the imaging optical axis), it is easier to align the unbent spark plug.
Also, when welding precious metal tips with different height dimensions, according to this welding method, alignment is performed by moving the front end surface of the precious metal tip in the plane direction so as to coincide with the imaging optical axis. For example, high-precision alignment can be performed regardless of the height dimension of the noble metal tip.

  Furthermore, in the method for welding a noble metal tip to the unbent spark plug according to any of the above, in the fixing step, the outer electrode is held and the unbent spark plug for fixing the unbent spark plug is fixed. It is preferable to use a precious metal tip welding method.

  In this method of welding a noble metal tip to an unbent spark plug, the outer electrode of the unbent spark plug is held, the unbent spark plug is fixed, and welding is performed. For this reason, since a very close portion of the planned welding portion is held, compared to the case where the unbent spark plug is held and fixed to another portion (for example, a metal shell), it is arranged in the welding planned portion or here. The variation in the position of the noble metal tip is reduced. Therefore, since the distance moved in the plane direction for alignment of the unbent spark plug can be reduced, the alignment can be completed in a short time, and the unbent spark plug can be efficiently welded.

  Furthermore, in the method for welding a noble metal tip to the unbent spark plug according to any one of the above, the fixing step includes the axis of the rotation shaft about the flat inner surface of the outer electrode with respect to the unbent spark plug. The position of the noble metal tip on the unbent spark plug that fixes the position in the rotation axis direction along the reference axis position to the rotation axis direction reference position is good.

In this method of welding the noble metal tip to the unbent spark plug, in the fixing step, the rotation axis direction of the flat inner surface of the outer electrode of the unbend spark plug is fixed to the reference position in the rotation axis direction and welding is performed. . For this reason, it is possible to weld the unbent spark plug with high accuracy without causing a shift in the position in the rotational axis direction of the flat inner surface of the outer electrode of the unbent spark plug.
As a method for fixing the position of the flat inner side surface of the outer electrode in the rotation axis direction reference position to the rotation axis direction reference position, specifically, for example, the rotation axis direction reference arranged at the rotation axis direction reference position. A method of fixing an unbent spark plug in a state where the flat inner side surface of the outer electrode is in contact with the surface is mentioned.

  Furthermore, in the method for welding a noble metal tip to the unbent spark plug according to any one of the above, the fixing step is performed along the axis of the center electrode with respect to the tip surface of the outer electrode with respect to the unbent spark plug. The position in the central axis direction may be a method for welding a noble metal tip to an unbent spark plug that is fixed at a reference position in the central axis direction.

In this method of welding the noble metal tip to the unbent spark plug, in the fixing step, the center axis direction of the tip surface of the outer electrode of the unbent spark plug is fixed to the reference position in the center axis direction, and welding is performed. For this reason, it is possible to weld the unbent spark plug with high accuracy without causing a shift in the position in the central axis direction of the tip surface of the outer electrode of the unbent spark plug.
In addition, as a method of fixing the position in the central axis direction of the tip surface of the outer electrode to the central axis direction reference position, for example, specifically, on the central axis direction reference plane disposed at the central axis direction reference position, There is a method of fixing the unbent spark plug in a state where the tip surface of the electrode is in contact.

  Further, the center electrode, a metal shell that surrounds the center electrode in an annular shape, and one end of the metal shell is fixed to the front end surface of the metal shell, and the inner surface of the center electrode is bent to face the inner surface. A cylindrical noble metal tip is welded to a position of the inner side surface of the outer electrode facing the center electrode, and a spark discharge gap is formed between the noble metal tip and the center electrode. It is preferable that the spark plug manufacturing apparatus includes a method for welding a noble metal tip to an unbent spark plug described in any of the above.

  In this spark plug manufacturing method, the spark plug is manufactured using the spark plug welding apparatus. For this reason, when welding the noble metal tip to the outer electrode, it is easy to align the unbent spark plug and it can be completed in a short time. Therefore, the overall manufacturing time of the spark plug can be shortened and the manufacturing efficiency can be improved. be able to.

  A spark plug welding apparatus, a spark plug manufacturing apparatus, a spark plug welding method, and a spark plug manufacturing method according to an embodiment of the present invention will be described with reference to FIGS.

  First, the spark plug 10 will be described. As shown in FIG. 1, the spark plug 10 includes a center electrode 11, a metal shell 12 that annularly surrounds the center electrode 11, and an insulator 16 that is interposed between the center electrode 11 and the metal shell 12 to insulate them. . Among these, the center electrode 11 is formed by welding a noble metal tip 11P to the tip (lower end in FIG. 1) of the center electrode body 11B. Further, the front end surface 12S of the metal shell 12 is provided with an outer electrode 13 that is fixed to one end of the metal shell 12 and bent so that the inner side surface 14 of the center electrode 11 faces the front end surface. A cylindrical noble metal tip 15 is welded to the inner side surface 14 of the outer electrode 13 facing the center electrode 11 at a position facing the center electrode 11. The noble metal tip 15 and the noble metal tip 11P of the center electrode 11 are welded. Between the two, a spark discharge gap G is formed.

    Next, an unbent spark plug 10B that is a target of welding in this embodiment will be described. The unbent spark plug 10B is an unbent outer electrode 13B (hereinafter simply referred to as the outer electrode 13B) before the outer electrode 13 of the spark plug 10 is bent and formed, as indicated by a broken line in FIG. is there. One end of the outer electrode 13B is fixed to the distal end surface 12S of the metal shell 12. Of the outer electrode 13B, the flat inner side surface 14B facing the center electrode 11 side after the subsequent bending process is formed by bending the outer electrode 13B into the outer electrode 13 after the unbent spark plug 10B is completed. The inner surface 1 faces the center electrode 11. And the columnar noble metal tip 15 is welded to the planned welding portion 14BW facing the center electrode 11 in the outer electrode 13 after the bending forming in the flat inner side surface 14B. The noble metal tip 15 is temporarily fixed to the planned welding portion 14BW by resistance welding before welding.

Further, an unbent spark plug welding apparatus (hereinafter also simply referred to as a welding apparatus) 20 of this embodiment will be described. FIG. 2 is an explanatory view showing a state in which the unbent spark plug 10B is set in the welding apparatus 20. FIG.
This welding apparatus 20 has an imaging optical axis 22AX that extends in the vertical direction (vertical direction in FIG. 2), a video camera 22 that captures a video image, and a laser optical axis 26AX, and laser emission for laser welding. The unit 26 includes a welding base 21 that holds and rotates the unbent spark plug 10B.

  The welding table 21 holds a fixing jig 23 for fixing and holding the unbent spark plug 10B, and an XY that can hold the fixing jig 23 and move in a direction orthogonal to the imaging optical axis 22AX (hereinafter referred to as a plane direction). A stage 24 is included. Further, the welding table 21 has a rotation shaft 25AX that is coaxial with the imaging optical axis 22AX, and includes a rotation table 25 that holds the fixing jig 23 and the XY stage 24 rotatably around the rotation shaft 25AX. .

Among these, the fixing jig 23 includes an upper surface plate 31 and a pusher 32 shown in FIGS. 3 and 4.
The upper surface plate 31 is located on the uppermost surface of the fixing jig 23 and has a substantially rectangular shape in a plan view and a substantially flat plate shape. This upper surface plate 31 has a tapered hole 31P that increases in diameter toward the upper surface 31J near the plug-side end surface 31G (near the right end in FIG. 3A), which is one side end surface thereof, and an upper surface on the bottom portion. A cylindrical cylindrical hole 31C having a thickness about half the thickness of the plate 31 is provided.

  Further, on the back surface 31K side of the cylindrical hole 31C, a first slit 31S having a width SW1 (see FIG. 4B) slightly larger than the width GW (see FIG. 3A) of the outer electrode 13B is provided. It is formed so as to reach the back surface 31K and the plug-side end surface 31G. Further, a slide having a width SW2 narrower than the width SW1 of the first slit 31S and narrower than the width GW of the outer electrode 13B is provided between the cylindrical hole 31C and the tapered hole 31P and the plug-side end surface 31G. A split second slit 31R (see FIG. 4B) is formed. Therefore, each width has a relationship of SW1> GW> SW2.

  An end surface of a step portion formed between the first slit 31S and the second slit 31R is a flat first reference surface 31T orthogonal to the rotation shaft 25AX. Further, in the first slit 31S, the end surface opposite to the plug-side end surface 31G is a flat second reference surface 31U.

As will be described later, the outer electrode 13B of the unbent spark plug 10B is set on the fixing jig 23. At this time, the first reference surface 31T is brought into contact with the flat inner side surface 14B so that the flat inner side surface 14B and the unbent spark plug 10B including the flat inner side surface 14B are in the rotation axis direction DR ( It is used for positioning in the vertical direction in FIG.
Further, the second reference surface 31U is brought into contact with the distal end surface 18S of the outer electrode 13B, and the distal end surface 18S and the unbent spark plug 10B including the distal end surface 18S are center axial direction DP along the central axis PAX (FIG. 5 ( a) Used for positioning in the horizontal direction.
Further, as shown in FIG. 5A, the chamfered portion 31M makes the center electrode 11 and the insulator 16 of the unbent spark plug 10B come into contact with the upper surface plate 31 when the front end surface 18S of the outer electrode 13B is brought into contact. The plug side end face 31G is chamfered so as not to be damaged.

  The pusher 32 disposed on the back surface 31K side of the upper surface plate 31 has a cross-section and an inverted T shape (see FIGS. 3C and 5B), and has a main body portion 32B and a main body portion 32B. A pressing portion 32P protruding toward the upper surface plate 31 side. The pressing portion 32P has a width slightly smaller than the width SW1 of the first slit 31S of the upper surface plate 31. For this reason, this press part 32P can be inserted in a 1st slit from the press surface 32PT side which is the top face.

The pusher 32 can be moved in the rotation axis direction DR (vertical direction in FIG. 3C) by a known drive mechanism (not shown). Accordingly, as shown in FIG. 5B, the unbent spark plug 10B is fixed to the fixing jig 23 by pressing the outer electrode 13B inserted into the first slit 31S toward the first reference surface 31T with the pressing surface 32PT. Can be fixed to.

  Further, the XY stage 24 includes two single-axis direction tables arranged orthogonal to each other, that is, an X-axis table 24X movable in the X-axis direction TX and a Y-axis table 24Y movable in the Y-axis direction. The fixing jig 23 to be placed can be moved in a plane direction TP (a direction along a plane orthogonal to the paper surface in FIG. 2) orthogonal to the rotation shaft 25AX. The X-axis table 24X and the Y-axis table 24Y can move an object mounted on each table in the X-axis direction TX or the Y-axis direction TY by known worm gear drive mechanisms 24XM and 24YM using a worm gear and a motor. it can.

  Further, the rotation table 25 is mounted on a rotation table base 25B, a rotation unit 25C which is mounted on the upper surface of the rotation table base 25B and can be rotated around the rotation shaft 25AX, and the rotation unit 25C. And a rotating plate 25D mounted and coupled to each other. This rotation table 25 is rotated around a rotation axis 25AX by a known motor driving device (not shown) by a rotation unit 25C, a rotation plate 25D, an XY stage 24 and a fixing jig 23 mounted on the rotation unit 25C. Can be made.

On the other hand, the video camera 22 is arranged such that its optical axis (imaging optical axis) 22AX is coaxial with the rotation axis 25AX. For this reason, when the unbent spark plug 10B is set on the fixing jig 23, the outer electrode 13B and the tip surface 15S of the noble metal tip 15 can be imaged.
The rectangular image 40 (see FIG. 6) captured by the video camera 22 has an image center 41 (vertical and horizontal centers) corresponding to the position of the imaging optical axis 22AX.
Further, in the image 40 shown in FIG. 6, the direction (left-right direction) of the X-axis 42 corresponds to the X-axis direction TX (left-right direction in FIG. 2) in FIG. The (vertical direction) corresponds to the Y-axis direction TY in FIG. 2 (the direction perpendicular to the paper surface in FIG. 2).
The focal point of the video camera 22 is adjusted to the position of the upper surface 31J or the first reference surface 31T of the upper surface plate 31 (or is automatically focused).

  The laser emitting unit 26 is a YAG laser that emits laser light along the laser optical axis 26AX, and the laser optical axis 26AX includes an imaging optical axis 22AX of the video camera 22 and a rotary shaft 25AX of the rotary table 25. They are arranged to intersect at an intersection angle θ. More specifically, as shown in FIGS. 5B and 7, the outer electrode 13 </ b> B of the unbent spark plug 10 </ b> B is fixed with a fixing jig 23. Next, in the XY stage 24, the center 15RC of the joint end surface 15R (the lower surface in FIG. 7) of the noble metal tip 15 placed on the planned welding portion 14BW of the flat inner side surface 14B is set to the imaging optical axis 22AX and the rotation axis 25AX. Match. At this time, the laser optical axis 26AX coincides with a part of the peripheral edge 15RP (the right end in FIG. 7) of the joining end surface 15R of the noble metal tip 15 and intersects the rotation axis 25AX at an intersection CR with an intersection angle θ. In addition, a laser emission unit 26 is arranged.

For this reason, when the rotating table 25 is rotated in the above-described state and the unbent spark plug 10B is rotated around the rotation shaft 25AX by one rotation, the portion corresponding to the laser optical axis 26AX is the noble metal tip. This extends over the entire circumference of the peripheral edge 15RP of the 15 joining end faces 15R.
Further, in this example, the imaging optical axis 22AX, the rotation axis 25AX, and the laser optical axis 26AX are positioned in the same plane, and therefore, of the peripheral edge 15RP of the noble metal tip 15, coincide with the laser optical axis 26AX. The laser emission unit 26 is arranged so that the tangent line of the joining end surface 15R in the portion and the laser optical axis 26AX are orthogonal to each other.

Next, a spark plug manufacturing apparatus 60 including the welding apparatus 20 of the present embodiment, a method for welding a noble metal tip to an unbent spark plug using the welding apparatus 20, and a spark plug manufacturing method will be described.
As shown in FIG. 8, the spark plug manufacturing apparatus 60 has an unbent spark plug manufacturing apparatus 61 that manufactures the unbent spark plug 10B by welding the outer electrode 13B to the distal end surface 12S of the metal shell 12, and the welding described above. It comprises an apparatus 20 and an outer electrode bending apparatus 62 for bending the outer electrode 13.
Therefore, the noble metal tip 15 is welded by the welding device 20 to the unbent spark plug 10B manufactured by the unbent spark plug manufacturing device 61 in the spark plug manufacturing device 60 of the present embodiment.

First, the unbent spark plug 10 </ b> B is fixed with the fixing jig 23. Here, as shown in FIGS. 3A, 3 </ b> B, 3 </ b> C, 5 </ b> A and 5 </ b> B, the outer electrode 13 </ b> B of the unbent spark plug 10 </ b> B has a flat inner side surface 14 </ b> B whose video camera 22 has a flat inner side surface 14 </ b> B. In the first slit 31S of the upper surface plate 31, and the front end surface 18S of the outer electrode 13B is brought into contact with the second reference surface 31U. Further, the pusher 32 is raised, and the pressing portion 32P is inserted into the first slit 31S, the flat outer surface 17B of the outer electrode 13B is pressed by the pressing surface 32PT, and the outer electrode 13B is held by contact.
As a result, the unbent spark plug 10B is fixedly held by the fixing jig 23.
In the present embodiment, in fixing the unbent spark plug 10B in this way, the outer electrode 13B near the noble metal tip 15 and the planned welding portion 14BW is held and fixed, so the planned welding portion 14BW and the noble metal when fixed are fixed. The position variation of the chip 15 can be reduced.

  Next, as shown in FIG. 6, the unbent spark plug 10 </ b> B, specifically, the outer electrode 13 </ b> B and the noble metal tip 15 are aligned using an image 40 taken by the video camera 22. Specifically, the center 44C of the chip tip image 44 corresponding to the tip surface 15S of the noble metal tip 15 captured by the video camera 22 is made to coincide with the image center 41 corresponding to the imaging optical axis 22AX. For this purpose, the X-axis table 24X and the Y-axis table 24Y of the XY stage 24 on which the fixing jig 23 is mounted are moved. Then, the imaging optical axis 22AX and the rotation axis 25AX pass through the center 15SC of the tip surface 15S of the noble metal tip 15. Further, the noble metal tip 15 has a cylindrical shape, and the joining end face 15R and the tip axis 15AX are orthogonal to each other. For this reason, after all, the chip axis 15AX coincides with the imaging optical axis 22AX and the rotation axis 25AX, and these also pass through the center 15RC of the joining end face 15R. Further, as described above, when the noble metal tip 15 is arranged in this state, the laser optical axis 26AX of the laser emitting unit 26 is arranged so as to coincide with a part of the peripheral edge 15RP of the joining end face 15R.

  Therefore, when the laser beam is irradiated from the laser emission unit 26 while rotating the rotation table 25 around the rotation axis 25AX, the laser beam is irradiated over the entire circumference of the joining end surface 15R of the noble metal tip 15. Thus, the noble metal tip 15 is welded to the flat inner side surface 14B of the outer electrode 13B of the unbent spark plug 10B.

  The crossing angle θ between the laser optical axis 26AX, the imaging optical axis 22AX, and the rotation axis 25AX is such that when the unbent spark plug 10B is rotated by the rotation table 25, the laser beam is the metal shell 12 or It is preferable to set the angle so as not to hit the center electrode 11. This is because welding can be performed uniformly over the entire circumference of the peripheral edge 15RP of the joining end face 15R. Further, the focal point of the laser light is adjusted so as to coincide with or be positioned in the vicinity of the peripheral edge 15RP of the joint end face 15R.

In the present embodiment, an unbent spark plug is used such that the center 44C of the tip end image 44 coincides with the image center 41 using an image 40 taken by the video camera 22 having the imaging optical axis 22AX coaxial with the rotation axis 25AX. Align 10B. Thereby, the center 15RC of the joining end surface 15R of the noble metal tip 15 can be made to coincide with the rotation shaft 25AX of the rotation table 25. For this reason, since the alignment of the unbent spark plug 10B is easy and can be completed in a short time, the time required for the welding process can be shortened, man-hours can be reduced, and work efficiency can be improved.

  Further, when welding the noble metal tip 15 having a different height direction dimension, the unbent spark plug 10B is flattened by the XY stage 24 so that the center 15SC of the tip surface 15S of the noble metal tip 15 coincides with the imaging optical axis 22AX. If the alignment is performed by moving in the direction, there is an advantage that the alignment can be performed with high accuracy regardless of the dimension in the height direction of the noble metal tip 15.

Further, the laser emission unit 26 is arranged so that the laser optical axis 26AX intersects the rotation axis 25AX. Accordingly, since the laser beam is applied to the joining end surface 15R of the noble metal tip 15 from the direction orthogonal to the tangent line, the energy of the laser beam is injected toward the inner side in the radial direction of the noble metal tip 15, and welding is performed. Since it is performed to the deeper part which goes to 15 radial inner side, appropriate welding can be performed efficiently.

  In the present embodiment, the upper surface plate 31 of the fixing jig 23 includes the first reference surface 31T. Therefore, the flat inner side surface 14B can be positioned in the rotational axis direction DR by bringing a part of the flat inner side surface 14B of the outer electrode 13B of the unbent spark plug 10B into contact with the first reference surface 31T. Accordingly, there is no position shift in the rotation axis direction DR, and appropriate welding can be performed.

  Similarly, in the present embodiment, the upper surface plate 31 of the fixing jig 23 includes the second reference surface 31U. For this reason, the front end surface 18S of the outer electrode 13B is brought into contact with the second reference surface 31U, whereby the front end surface 18S can be positioned in the central axis direction DP. Accordingly, the flat inner side surface 14B of the outer electrode 13B and the noble metal tip 15 are not displaced in the central axis direction DP, so that appropriate welding can be performed.

  Now, as shown in FIG. 8, the outer electrode 13 </ b> B of the unbent spark plug 10 </ b> B to which the noble metal tip 15 is welded is bent by a known outer electrode bending forming device 62. Thus, the time required for welding can be shortened, and the spark plug 10 (see FIG. 1) having the outer electrode 13 can be efficiently manufactured.

While the present invention has been described with reference to the embodiments, it is needless to say that the present invention is not limited to the above-described embodiments, and can be appropriately modified and operated without departing from the gist thereof.
For example, in the embodiment, the imaging optical axis 22AX of the video camera 22 and the rotary shaft 25AX of the rotary table 25 are installed so as to be coaxial, but the video camera 22 and the rotary table are arranged so that they are parallel to each other. 25 may be installed. However, it is particularly preferable to install it so as to be coaxial.
Further, in the embodiment, the noble metal tip 15 is temporarily fixed to the welding portion 14BW of the unbent outer electrode 13B by resistance welding in advance, but after the outer electrode 13B (unbending spark plug 10B) is fixed, welding is scheduled. The noble metal tip 15 may be placed on the portion 14BW. Even in that case, the position adjustment of the noble metal tip 15 may be performed as described above.
Furthermore, in the embodiment, the center 44C of the tip end image 44 corresponding to the tip end surface 15S of the noble metal tip 15 imaged by the video camera is obtained, and this center 44C is made to coincide with the image center 41 corresponding to the imaging optical axis 22AX. Thus, the position of the noble metal tip 15 was adjusted. However, as shown in FIG. 6, the position of the noble metal tip 15 may be adjusted so that the tip end image 44 is disposed in the region 70 (see FIG. 6) provided in advance on the imaging optical axis 22AX. .

It is explanatory drawing which shows an example of the spark plug manufactured with the welding apparatus of this invention. It is explanatory drawing which shows the state which set the unbent spark plug to the unbent spark plug welding apparatus concerning an Example. It is explanatory drawing of an upper surface plate and a pusher among the fixing jigs of the unbent spark plug welding apparatus concerning an Example, (a) is a top view, (b) is AA arrow sectional drawing, (c) is BB arrow FIG. FIG. 4 is an enlarged view of a main part of the top plate shown in FIG. 3, (a) is an enlarged view of the main part of FIG. 3 (b), and (b) is an enlarged view of the main part of FIG. It is explanatory drawing which shows a mode when an unbent spark plug is set to the fixing jig of the unbent spark plug welding apparatus concerning an Example, (a) is a figure corresponding to Fig.4 (a), (b). These are figures corresponding to FIG.4 (b). It is explanatory drawing which shows the mode of the image which imaged the noble metal chip | tip with the video camera of the unbent spark plug welding apparatus concerning an Example, and its position alignment. In the state where the unbent spark plug is set on the fixing jig of the unbent spark plug welding apparatus according to the embodiment and the alignment is performed, the imaging optical axis, the rotation axis, the laser optical axis, and the tip axis of the noble metal tip It is explanatory drawing which shows a relationship. It is explanatory drawing of the spark plug manufacturing apparatus concerning an Example.

10 spark plug 10B unbent spark plug 11 center electrode PAX (center electrode) center axis DP center axis direction 12 metal shell 13 outer electrode 13B (unbent) outer electrode 14 inner side surface 14B flat inner side surface 14BW (out of flat inner side surface) , Noble metal tip) planned welding portion 15 noble metal tip 17B flat outer surface 18S tip surface (of unbent outer electrode) 20 unbent spark plug welding device 21 welding table 22 video camera (imaging means)
22AX Imaging optical axis 23 Fixing jig (fixing means)
24 XY stage (plane direction moving means)
25 Rotating table (rotating means)
25AX rotation axis DR rotation axis direction 26 laser emission unit (laser irradiation device)
26AX Laser optical axis 31 Upper surface plate 31T First reference plane (rotation axis direction reference plane)
31U 2nd reference plane (center axis direction reference plane)
32 Pusher 40 Image 41 Image center 44 Tip tip image (Precious metal tip image)
44C Center 60 (tip image) Spark plug manufacturing device

Claims (12)

A center electrode, a metal shell that surrounds the center electrode in an annular shape, and an outer electrode having one end thereof fixed to the front end surface of the metal shell, facing at least the center electrode side after the subsequent bending process, An unbent spark plug having an outer electrode including a flat inner flat surface, and a columnar noble metal tip against the flat inner surface of the flat inner surface of the outer electrode on a portion to be welded. A spark plug welding device for welding in a state of contact,
An imaging means having an imaging optical axis and taking an image;
With the flat inner side surface of the outer electrode orthogonal to the imaging optical axis and facing the imaging means side, a fixing means for fixing the unbent spark plug to itself and the fixing means are connected to the outer electrode. A plane direction moving means capable of moving in a plane direction parallel to the flat inner surface;
A rotation means having a rotation axis parallel to the imaging optical axis, and capable of rotating the fixing means and the planar direction movement means around the rotation axis;
A laser irradiation device that emits laser light,
The laser optical axis of the laser beam obliquely intersects the imaging optical axis,
The unbent spark plug is fixed by the fixing means, the unbent spark plug is moved by the plane direction moving means together with the fixing means, and the joining end face is in contact with the planned welding portion of the flat inner surface. When the center of the joining end face is made to coincide with the rotation axis, the laser optical axis coincides with any part of the peripheral edge of the joining end face of the noble metal tip,
In this state, when the unbent spark plug is rotated around the rotation axis together with the planar direction moving means and the fixing means by the rotation means, the peripheral edge of the joining end surface of the noble metal tip is rotated. A laser irradiation device configured to be irradiated with laser light over the entire circumference, wherein the imaging unit is at least in the state where the center of the joint end surface of the noble metal tip is aligned with the rotation axis. Spark plug welding device for imaging precious metal tip and its periphery. The spark plug welding device according to claim 1,
A spark plug welding apparatus in which the imaging optical axis and the rotation axis are coaxial. A spark plug welding apparatus according to claim 1 or 2,
The fixing means includes
A spark plug welding device which is a fixing means for holding the outer electrode and fixing the unbent spark plug. The spark plug welding device according to any one of claims 1 to 3,
The fixing means includes
Of the flat inner side surface of the outer electrode, at least a part of the portion to be welded and a portion excluding the periphery thereof are brought into contact with each other, and the outer electrode of the unbent spark plug is rotated along the axis of the rotating shaft. A spark plug welding device including a rotational axis direction reference surface for positioning in a moving axis direction. In the spark plug welding apparatus according to any one of claims 1 to 4,
The fixing means includes
A spark plug welding apparatus including a central axial reference surface that positions a distal end surface of the outer electrode in contact with the outer electrode of the unbent spark plug in a central axial direction along an axis of the central electrode. The center electrode, a metal shell that surrounds the center electrode in an annular shape, and one end of the metal shell is fixed to the tip surface of the metal shell, and is bent so that the inner surface of the metal core faces the tip surface of the center electrode. An outer electrode, and a cylindrical noble metal tip is welded to the inner surface of the outer electrode facing the center electrode, and a spark discharge gap is formed between the noble metal tip and the center electrode. A spark plug manufacturing apparatus comprising:
A spark plug manufacturing apparatus including the spark plug welding apparatus according to any one of claims 1 to 5. A center electrode, a metal shell that surrounds the center electrode in an annular shape, and an outer electrode having one end thereof fixed to the front end surface of the metal shell, facing at least the center electrode side after the subsequent bending process, An unbent spark plug including an outer electrode including a flat inner flat surface, and a columnar noble metal tip on the portion to be welded of the flat inner surface of the outer electrode perpendicular to the axis of the noble metal tip. A welding method of precious metal tips to an unbent spark plug, in which a joining end face is welded to the flat inner surface in a state of being in contact with the flat inner surface,
A fixing step for fixing the unbent spark plug;
With the imaging means having an imaging optical axis orthogonal to the flat inner surface of the outer electrode, the noble metal tip disposed on the planned welding portion of the flat inner surface is imaged, and the image of the noble metal chip is displayed on the imaging screen. A plane direction moving step of moving the unbent spark plug in a plane direction parallel to the flat inner surface so as to be positioned at a predetermined position;
While rotating the unbent spark plug around a rotation axis that is orthogonal to the flat inner surface and passes through the center of the joining end face of the noble metal tip , laser light is applied to any part of the joining end face of the noble metal tip. And welding the noble metal tip to the flat inner surface over the entire periphery of the joint end face of the noble metal tip; , A method for welding a noble metal tip to an unbent spark plug. A method for welding a noble metal tip to an unbent spark plug according to claim 7,
The imaging optical axis and the rotation axis are coaxial,
In the parallel movement step, the unbent spark plug is moved so that the center of the image of the tip surface of the noble metal tip coincides with the image position corresponding to the imaging optical axis.
How to weld precious metal tips to unbent spark plugs. A method of welding a noble metal tip to an unbent spark plug according to claim 7 or claim 8,
In the fixing step,
A method of welding a noble metal tip to an unbent spark plug for holding the outer electrode and fixing the unbend spark plug. A method for welding a noble metal tip to an unbent spark plug according to any one of claims 7 to 9,
The fixing step includes
With respect to the unbent spark plug, the noble metal tip is attached to the unbent spark plug for fixing the position in the rotation axis direction along the axis of the rotation axis on the flat inner surface of the outer electrode to the reference position in the rotation axis direction. Welding method. A method for welding a noble metal tip to an unbent spark plug according to any one of claims 7 to 10,
The fixing step includes
A method of welding a noble metal tip to an unbent spark plug, wherein the position of the tip end surface of the outer electrode with respect to the center axis direction along the axis of the center electrode is fixed to a reference position in the center axis direction. The center electrode, a metal shell that surrounds the center electrode in an annular shape, and one end of the metal shell is fixed to the tip surface of the metal shell, and is bent so that the inner surface of the metal core faces the tip surface of the center electrode. An outer electrode, and a cylindrical noble metal tip is welded to the inner surface of the outer electrode facing the center electrode, and a spark discharge gap is formed between the noble metal tip and the center electrode. A spark plug manufacturing apparatus comprising:
The manufacturing method of a spark plug including the welding method of the noble metal tip to the unbent spark plug of any one of Claims 7-11.

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