Electric lamp or space discharge component or device manufacturi – Process – Spark plug or spark gap making
Reexamination Certificate
2001-12-11
2003-12-09
Ramsey, Kenneth J. (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
Spark plug or spark gap making
C219S091200, C219S086240
Reexamination Certificate
active
06659826
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a spark plug which has two electrodes (i.e., center electrode and ground electrode) opposed to form a predetermined gap and a noble metal tip welded to at least one of these electrodes.
FIGS. 4A and 4B
show a conventional welding method for a spark plug. First, as shown in
FIG. 4A
, a tip
103
a
is inserted into a hole of a guide jig
110
. The guide jig
110
is used to locate the tip
103
a
to a predetermined position on a plug electrode
103
(such as a ground electrode or a center electrode). Then, the guide jig
110
is removed upward to leave the tip
103
a
standing upright on the electrode
103
. Then, electric or resistance welding is performed to fix the tip
103
a
to the plug electrode
103
under a condition that tip
103
a
is depressed by a welding electrode
120
(refer to FIG.
4
B).
According to this conventional welding method, the guide jig may touch the tip
103
a
standing upright on the electrode
103
when the guide jig is raised upward. Thus, the tip
103
a
may move or slide on the electrode.
If the hole of guide jig
110
is enlarged to solve this problem, it will deteriorate the accuracy in positioning the tip
103
a
on the plug electrode
103
. In other words, the distance (i.e., discharge gap) between the electrodes will become inaccurate and accordingly the properties of the spark plug will be worsened.
SUMMARY OF THE INVENTION
To solve the above problems, the present invention has an object to provide a manufacturing method for a spark plug capable of accurately positioning a tip on a plug electrode before welding the tip to this electrode.
In order to accomplish the above and other related objects, the present invention provides a first method for manufacturing a spark plug having two electrodes opposed to cause a spark discharge and a noble metal tip welded to at least one of these plug electrodes. A first process of the first manufacturing method is performed to clamp the tip by first and second guides of a guide jig approaching to each other in a direction normal to an axial direction of the tip and to locate the tip to a predetermined position on a plug electrode. A second process of the first manufacturing method, succeeding the first process, is performed to depress the tip by a welding electrode under a condition that the tip is held by the guide jig, in which a thickness of the guide jig is smaller than a clearance between the welding electrode and the plug electrode. A third process of the first manufacturing method, succeeding the second process, is performed to remove the first and second guides of the guide jig from the tip in the direction normal to the axial direction of the tip. A fourth process of the first manufacturing method, succeeding the third process, is performed to weld the tip to the plug electrode by supplying electric power to the welding electrode.
According to the first manufacturing method, the first and second guides of the guide jig shift in the direction normal to the axial direction of the tip. This movement surely prevents the guide jig (i.e., either the first guide or the second guide) from touching and moving the tip when the guide jig departs from the tip.
Thus, the first manufacturing method assures an excellent welding operation performed under the condition that the tip is accurately positioned on the plug electrode. The first manufacturing method makes it possible to reduce a manufacturing error of the discharge gap formed between the opposed electrodes.
Furthermore, according to the first manufacturing method, the first and second guides of the guide jig depart from the tip under the condition that a pressing force of the welding electrode is applied on the tip. This surely prevents the tip from being moved by the guide jig (i.e., either the first guide or the second guide). The manufacturing error of the discharge gap can be further reduced.
The present invention provides a second method for manufacturing a spark plug having two electrodes opposed to cause a spark discharge and a noble metal tip welded to at least one of these plug electrodes. A first process of the second manufacturing method is performed to clamp the tip by first and second guides of a guide jig approaching to each other in a direction normal to an axial direction of the tip and to locate the tip to a predetermined position on a plug electrode. A second process of the second manufacturing method, succeeding the first process, is performed to remove the first and second guides of the guide jig from the tip in the direction normal to the axial direction of the tip. A third process of the second manufacturing method, succeeding the second process, is performed to depress the tip by a welding electrode. A fourth process of the second manufacturing method, succeeding the third process, is performed to weld the tip to the plug electrode by supplying electric power to the welding electrode.
According to the second manufacturing method, the first and second guides of the guide jig shift in the direction normal to the axial direction of the tip. This movement surely prevents the guide jig (i.e., either the first guide or the second guide) from touching and moving the tip when the guide jig departs from the tip.
Thus, the second manufacturing method assures an excellent welding operation performed under the condition that the tip is accurately positioned on the plug electrode. The second manufacturing method makes it possible to reduce a manufacturing error of the discharge gap formed between the opposed electrodes.
According to a preferable embodiment of the second manufacturing method, a height of the guide jig is lower than a height of the tip positioned on the plug electrode, when the guide jig is placed on the plug electrode to clamp the tip.
It is also preferable that at least one of the first and second guides of the guide jig has a triangular or comparable notch for guiding the tip. This makes it possible to automatically center the tip to a predetermined position on the plug electrode when the guide jig clamps the tip.
REFERENCES:
patent: 3993787 (1976-11-01), Nakabayashi et al.
patent: 4765786 (1988-08-01), Krogh
patent: 5154873 (1992-10-01), Sato et al.
patent: 5333542 (1994-08-01), Lewis et al.
patent: 5808266 (1998-09-01), Cecil
patent: 06-45049 (1994-02-01), None
Denso Corporation
Nixon & Vanderhye P.C.
Ramsey Kenneth J.
LandOfFree
Manufacturing method for a spark plug does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Manufacturing method for a spark plug, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Manufacturing method for a spark plug will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3127113