KR20090123055A - Welding method of electrode tip made from noble tip in spark plug - Google Patents

Abstract

PURPOSE: A method for welding a noble metal electrode tip of a spark plug is provided to suppress humping by filling a welding reinforcing material to a gap between an electrode and a noble metal electrode tip. CONSTITUTION: A spark plug includes a central electrode(3), an insulator, a fitting, and a ground electrode. The insulator surrounds the central electrode. The fitting surrounds the insulator. One end of the ground electrode is contacted with the fitting. The other end of the ground electrode is faced with the central electrode. A noble metal electrode tip(31) is formed in the central electrode and the ground electrode. A welding reinforcing material is inserted around the noble metal electrode tip. The welding reinforcing material and the noble metal electrode tip are primarily welded in the central electrode. The noble metal electrode tip and the electrode are secondarily welded by irradiating a beam to the welding reinforcing material.

Description

Welding method of spark plug noble metal electrode tip {WELDING METHOD OF ELECTRODE TIP MADE FROM NOBLE TIP IN SPARK PLUG}

The present invention relates to a method for manufacturing a spark plug for an internal combustion engine, and more particularly, to a method for welding a precious metal electrode tip to an electrode of a spark plug for an internal combustion engine.

In general, a spark plug is a device mounted on a cylinder head of an internal combustion engine to ignite an electric flame on a gas mixture of fuel and air supplied into a combustion chamber.

The spark plug is provided with a housing mounted to the cylinder head of the engine, and is disposed to pass through the center of the housing and wrapped in an insulator, protruded from an end of the housing, and one end of which is connected to the ignition coil so that a high voltage current is provided. It is composed of a center electrode is guided, and a ground electrode fixed to one side of the housing and disposed with a predetermined gap with the center electrode.

The center electrode and the ground electrode are generally composed of a copper compound having excellent thermal conductivity or nickel of high purity.

The insulator is wrapped around the outer circumferential surface of the center electrode in order to prevent high voltage from being emitted to portions other than generating sparks, and is formed of a ceramic material having excellent heat resistance insulation and the like.

In order to maintain durability and heat resistance and wear resistance while maintaining high ignition continuously under a high pressure and high temperature environment, a center electrode tip formed of expensive precious metal is fused by welding, and the ground electrode The ground electrode tip, which is formed of an expensive precious metal, is also welded to the end of the electrode.

1A to 1C are flowcharts illustrating a method of mounting an electrode tip on an electrode according to the related art.

Looking at the method for mounting the electrode tip to the electrode according to the prior art, first, as shown in Figure 1a, put the electrode tip 120 of the ball shape on the surface of the electrode 110 and the first spot (spot) welding Conduct. Then, the contact surface of the electrode tip 120 and the electrode 110 of the ball shape is fused while the junction of the electrode tip 120 and the electrode 110 is fused.

In this state, as illustrated in FIG. 1B, the pressing portion 130 having a flat plate shape is pressed down on the upper surface of the electrode tip 120. Then, the upper surface of the electrode tip 120 is molded into a flat shape.

As shown in FIG. 1C, secondary spot welding is performed to fix the gap between the electrode tip 120 and the electrode 110.

However, when the electrode tip is mounted by the electrode tip mounting method according to the related art as described above, as shown in the cross-sectional view of FIG. 2A and the cross-sectional photograph of FIG. 2B, both edges of the electrode tip 120 may not be fused. There is a problem that the lifting portion 140 is generated.

In addition, a humping phenomenon occurs in which bubbles are generated at the welded site due to the insufficient amount of molten melted by welding.

Further, since the melting point of the noble metal tip is much higher than the melting point of the material used as the electrode, the electrode portion is oxidized during welding, which causes the humping phenomenon.

As such, when the edge of the electrode tip is not fused, a phenomenon occurs in which the electrode tip is separated from the electrode during use, and a problem in that spark generation performance is deteriorated.

The present invention has been made to solve the above problems, to provide a spark plug noble metal electrode tip welding method that can improve the ignition performance of the spark plug by preventing the occurrence of humps in the welding portion between the ear tip and the electrode. It is done.

The present invention to solve the above problems, in the spark plug noble metal electrode tip welding method, the step of fitting a welding reinforcing material around the noble metal electrode tip; A second welding step of welding the noble metal electrode tip and the electrode by irradiating a beam to the welding reinforcing material; It provides a spark plug noble metal electrode tip welding method comprising a.

Here, before the second welding step, the step of first welding the welding reinforcing material and one end of the precious metal electrode tip to the electrode; preferably further comprises a.

In the primary welding step, it is effective to press the welding reinforcing material and the precious metal electrode tip toward the electrode.

In addition, when pressing the welding reinforcing material and the precious metal electrode tip toward the electrode, it is preferable to press the outer periphery of the welding reinforcing material, simultaneously pressing toward the precious metal electrode tip.

In addition, the precious metal electrode tip is formed in a columnar shape, the welding reinforcing material is effectively formed in a ring shape to be fitted to the precious metal electrode tip.

Meanwhile, as another embodiment of the present invention, fixing a welding reinforcing material between the noble metal electrode tip and the electrode to which the noble metal electrode tip is fixed; Disclosed is a spark plug precious metal electrode tip welding method comprising a; secondary welding step of welding the noble metal electrode tip and the electrode by irradiating a beam to the welding reinforcing material.

The fixing of the welding reinforcing material may include performing primary welding to fix the welding reinforcing material to the upper surface of the electrode by electric resistance welding.

In addition, in the primary welding step, it is effective to press the welding reinforcing material to the electric resistance welding.

And, it is preferable that the area of the welding reinforcing material is wider than the area of the precious metal electrode tip in contact with.

In addition, the welding reinforcing material is preferably a melting point between the precious metal electrode tip and the electrode.

Here, in the primary welding step, it is preferable to use the electric resistance welding method.

In addition, it is effective to use a laser beam in the secondary welding step.

According to the problem solving means of the present invention as described above it can be expected a variety of effects including the following matters. However, the present invention is not achieved by exerting all of the following effects.

First, in the case of beam welding, the welding reinforcing material is melted to melt and fill the gap between the precious metal electrode tip and the electrode, thereby suppressing the occurrence of humping such as bubbles.

In addition, since the amount of the noble metal electrode tip is reduced, as a result, a small size of the noble metal electrode tip can be used, thereby reducing the cost.

And, since the melting point of the welding reinforcing material is located between the precious metal electrode tip and the electrode, it is possible to prevent the generation of bubbles due to over-melting, and to increase the bonding force.

In addition, by further providing a primary welding step, not only the secondary welding can be facilitated, but also bubbles generated between the precious metal electrode tip and the electrode and the welding reinforcing material are removed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

However, in describing the present invention, a detailed description of known functions or configurations will be omitted in order not to disturb the gist of the present invention.

3 is a partially broken cross-sectional view showing one end of the spark plug manufactured by using the electrode tip welding method of the first embodiment of the present invention.

As shown in FIG. 3, the spark plug includes a center electrode 3, an insulator 2 disposed outside the center electrode 3, a metal fitting 1 disposed outside the insulator 2, and one end. The other end includes a ground electrode 4 connected to the silver bracket 1 and opposite the center electrode 3. Precious metal electrode tips 31 and 32 are formed at positions facing the center electrode 3 and the ground electrode 4.

4 is an enlarged cross-sectional view of a portion of the center electrode and the ground electrode of FIG. 3.

As shown in Fig. 4, the main body 3a of the center electrode 3 is tapered at its end, and its end face is formed flat. The precious metal electrode tip 31 is formed in a rod shape and disposed on a flat end face, and a laser joining, electron beam joining, resistance joining or other suitable joining technique is applied to the outer surface of the joining surface to form a joining line W, As a result, the electrode tip 31 is firmly fixed to the end surface of the center electrode 3. The opposite electrode tip 32 is disposed on the ground electrode 4, and the junction line W is similarly formed on the outer surface of the joint surface, whereby the electrode tip 32 is firmly fixed to the ground electrode 4.

Depending on the situation, one of the two opposing electrode tips 31 and 32 may be omitted. In such a case, a spark discharge gap is formed between one of the electrode tips 31, 32 and the ground electrode 4 (or the center electrode 3).

5 to 7 are front views showing step by step a welding method of a spark plug precious metal electrode tip according to a first embodiment of the present invention.

The welding method of the spark plug precious metal electrode tip according to the embodiment of the present invention includes the step of inserting the welding reinforcing material 8 around the precious metal electrode tip 31, the welding reinforcing material 8 and the precious metal electrode tip 31. Primary welding of one end of the electrode to the electrode 3 (Fig. 6), and a second welding step (Fig. 7) to irradiate and weld the beam to the welding reinforcing material (8).

In one embodiment of the present invention, the welding of the noble metal electrode tip to the center electrode is illustrated, but is not necessarily limited thereto, and it is obvious that the same may be applied to the method of welding the noble metal electrode tip to the ground electrode.

The noble metal refers to a metal whose chemical ionization energy is much larger than that of hydrogen, and which is not oxidized by an acid and an oxidizing agent, and includes gold, platinum, ruthenium, rhodium, osmium and iridium. The precious metal electrode tip 31 may use various kinds of precious metals such as iridium (Ir) and platinum (Pt), and are formed in a pillar shape as shown in FIG. 9. However, it is not limited to the cylinder as shown in FIG. 9, and may be formed of various pillars such as a square pillar, a triangular pillar, and the like as needed.

As shown in FIG. 8, the welding reinforcing material 8 is formed in a ring shape to be fitted to the precious metal electrode tip. That is, when the precious metal electrode tip 31 is formed in a cylindrical shape, the welding reinforcing material 8 is preferably formed in a circular ring shape, and when the precious metal electrode tip 31 is formed in a polygonal column shape, welding is performed accordingly. The reinforcing material is preferably formed in a polygonal ring shape. This is to eliminate the gap between the welding reinforcing material (8) and the precious metal electrode tip (31).

As such, by arranging the welding reinforcing material 8 around the noble metal electrode tip 31, the welding reinforcing material 8 is melted when performing beam welding as shown in FIG. 7, and the gap between the noble metal electrode tip 31 and the electrode. Since it melt | dissolves and fills, it can suppress generation | occurrence | production of humping, such as a bubble. In addition, since the amount of melting the precious metal electrode tip 31 is reduced, as a result, since the small precious metal electrode tip 31 can be used, there is an advantage that the cost can be reduced.

In addition, the welding reinforcement 8 preferably has a melting point between the precious metal electrode tip and the electrode. This prevents any of the electrodes 3 or the precious metal electrode tips 31 from being excessively melted or not melted at all at a temperature at which the welding reinforcement 8 can be melted a lot. If either is excessively melted, bubbles may be generated due to oxidation, and if not melted at all, problems may occur in bonding.

In the first welding step (FIG. 6), it is preferable to press the welding reinforcing material 8 and the noble metal electrode tip 32 toward the electrode. That is, it is preferable to weld, pressing in the direction of the arrow 10 in FIG. This can minimize the bubbles that can occur between the welding reinforcing material 8 and the electrode 3 and between the precious metal electrode tip 32 and the electrode (3).

In addition, when pressing the welding reinforcing material 8 and the noble metal electrode tip 32 toward the electrode 3, it is preferable to press the outer periphery of the welding reinforcing material 8 and simultaneously press the welding reinforcing material 8 toward the precious metal electrode tip 32. That is, it is preferable to weld, pressing the welding reinforcing material 8 in the direction of the arrow 11 in FIG. Due to this, it is possible to minimize the bubbles that can occur between the welding reinforcing material (8) and the precious metal electrode tip (32). In the first welding step, the electric resistance welding method is used. This has the advantage that the cost can be lower than other welding methods.

As described above, the welding reinforcing material 8 and the precious metal electrode tip 32 can be pressed toward the electrode 5, and the welding reinforcing material 8 can be pressed toward the precious metal electrode tip 32. Pressing tool 9 is presented.

The pressurization tool 9 has a first pressing surface 91 capable of pressing the end of the precious metal electrode tip 32 to press the electrode 5 and the welding reinforcing material 8 to the electrode 5 and the precious metal electrode tip. A second pressing inclined surface 92 capable of simultaneously pressing toward 32 is provided. In addition, when the edge 82 of the weld reinforcing material 8 is partially molded, a third pressing surface 93 capable of pressing the end surface 83 of the welding reinforcing material 8 is provided.

Therefore, the pressing tool 9 can press the welding reinforcing material 8 and the precious metal electrode tip 32 toward the electrode 5, and press the welding reinforcing material 8 toward the precious metal electrode tip 32. .

In the first welding step, the welding reinforcing material 8 and the precious metal electrode tip 32 is fixed to the electrode 3, thereby making it easier to perform the second welding welding with a beam, and the first welding step In the welding reinforcement (8) and the precious metal electrode tip 32 and the air bubbles that may occur between the electrode 3 can be removed in advance to further improve the quality of the welding. However, the first welding step is not necessarily required, and only the second welding step may partially achieve the object of the present invention.

In the second welding step, as shown in FIG. 7, the welding is completed by irradiating the primary welded welding reinforcement 8 with the laser beam.

As described above, in the present invention, the welding reinforcing material 8 is disposed around the precious metal electrode tip 31 so that the welding reinforcing material 8 is melted in the case of beam welding, and thus the gap between the precious metal electrode tip 31 and the electrode. Since it melt | dissolves and fills, it can suppress generation | occurrence | production of humping, such as a bubble. In addition, since the amount of melting the precious metal electrode tip 31 is reduced, as a result, since the small precious metal electrode tip 31 can be used, there is an advantage that the cost can be reduced.

10 to 13 are views showing step by step a spark plug noble metal electrode tip welding method of a second embodiment of the present invention.

As shown in these figures, the spark plug precious metal electrode tip welding method of the second embodiment fixes the welding reinforcement 81 between the precious metal electrode tip 311 and the electrode 3 to which the precious metal electrode tip 311 is fixed. 10 to 12, and a second welding step (FIG. 13) of welding the noble metal electrode tip and the electrode by irradiating a beam to the welding reinforcing material 81.

Fixing the welding reinforcing material (Figs. 10 to 12), the first welding to fix the welding reinforcing material to the upper surface of the electrode by electrical resistance welding, in particular, in the first welding step, the welding It is preferable to crimp the reinforcing material 81 to perform electrical resistance welding. That is, electric resistance welding is performed while pressing the spherical welding reinforcing material 81 toward the electrode 3 as shown in FIG. Therefore, bubbles or the like can be prevented from occurring between the welding reinforcing material 81 and the electrode 3. At this time, the area of the crimped welding reinforcing material 81 is larger than the area of the noble metal electrode tip 311 in contact with each other may increase the secondary welding efficiency. That is, as shown in FIG. 12, the outer circumference of the welding reinforcing material 81 protrudes laterally than the precious metal electrode tip 311, so that the laser beam is directly irradiated during the second welding. As a result, not only the welding reinforcing material 81 can be melted better, but the precious metal electrode tip 311 can be prevented from being excessively melted.

In addition, it is preferable that the welding reinforcement 81 has a melting point between the precious metal electrode tip and the electrode. This prevents any of the electrodes 3 or the precious metal electrode tips 311 from excessively melting at a temperature at which the welding reinforcing material 81 can be melted a lot or not melting at all. If one is excessively melted, bubbles may be generated due to oxidation, and if not melted at all, problems may occur in bonding.

The secondary welding step (Fig. 13) is performed by using the laser beam as in the first embodiment.

The second embodiment differs from the first embodiment in that the weld reinforcement 81 is positioned between the electrode 3 and the precious metal tip 311. This has the advantage that the spherical welding reinforcing material 81 is more melted into the electrode to increase the weldability.

Although the preferred embodiments of the present invention have been described above by way of example, the scope of the present invention is not limited to these specific embodiments, and may be appropriately changed within the scope described in the claims.

1a to 1c is a process flowchart showing a method for mounting an electrode tip on an electrode according to the prior art

2A and 2B are cross-sectional and cross-sectional photographs of electrode tips and electrodes welded according to the prior art.

3 is a partially broken cross-sectional view showing one end of a spark plug manufactured using the electrode tip welding method of the first embodiment of the present invention.

4 is an enlarged cross-sectional view of a portion of the center electrode and the ground electrode of FIG. 3;

5 to 9 show step by step the electrode tip welding method of the first embodiment of the present invention,

5 is a front view showing a step of inserting a welding reinforcing material around the precious metal electrode tip.

6 is a front view showing the primary welding step

7 is a front view showing a step of secondary welding

8 is a perspective view of the welding reinforcing material of FIG.

9 is a perspective view of a precious metal electrode tip

10 to 13 is a step-by-step view showing the electrode tip welding method of a second embodiment of the present invention

** Description of the symbols for the main parts of the drawings **

31, 311: Precious Metal Electrode Tip

8, 81: welding reinforcement

3: electrode

Claims (13)

In the spark plug welding method of precious metal electrode tip, Fitting a welding reinforcement around the precious metal electrode tip; A second welding step of welding the noble metal electrode tip and the electrode by irradiating a beam to the welding reinforcing material; Spark plug noble metal electrode tip welding method comprising a. The method of claim 1, Prior to the second welding step, First welding the welding reinforcing material and one end of the noble metal electrode tip to an electrode; Spark plug noble metal electrode tip welding method characterized in that it further comprises. The method of claim 2, In the first welding step, the welding reinforcing material and the noble metal electrode tip is pressed spark electrode characterized in that the electrode tip welding method. The method of claim 3, wherein When pressing the welding reinforcing material and the precious metal electrode tip toward the electrode, by pressing the outer periphery of the welding reinforcing material, the sparking plug precious metal electrode tip welding method, characterized in that simultaneously pressing toward the precious metal electrode tip. The method of claim 1, The precious metal electrode tip is formed in a columnar shape, The welding reinforcing material is spark plug noble metal electrode tip welding method, characterized in that formed in a ring shape to be fitted to the precious metal electrode tip. In the spark plug welding method of precious metal electrode tip, Fixing a welding reinforcing material between the precious metal electrode tip and the electrode to which the precious metal electrode tip is fixed; A second welding step of welding the noble metal electrode tip and the electrode by irradiating a beam to the welding reinforcing material; Spark plug noble metal electrode tip welding method comprising a. The method of claim 6, Fixing the welding reinforcing material, Primary welding fixing the welding reinforcing material to the upper surface of the electrode by electric resistance welding; Spark plug precious metal electrode tip welding method comprising a. The method of claim 7, wherein In the first welding step, The welding method of the spark plug precious metal electrode tip, characterized in that the electric resistance welding by pressing the welding reinforcing material. The method of claim 6, Spark welding plug precious metal electrode tip welding method characterized in that the area of the welding reinforcing material is larger than the area of the precious metal electrode tip in contact with. The method according to any one of claims 1 to 9, The welding reinforcing material spark melting plug precious metal electrode tip welding method, characterized in that the melting point between the electrode and the electrode. The method of claim 2, Spark welding plug precious metal electrode tip welding method, characterized in that for the first welding step using an electrical resistance welding method. The method according to any one of claims 1 to 9, Spark welding plug precious metal electrode tip welding method, characterized in that for the second welding step using a laser beam. The spark plug manufactured by using the spark plug precious metal electrode tip welding method of any one of Claims 1-9.

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