KR100250137B1 - Method for electric welding - Google Patents

Abstract

According to the present invention, in an electric resistance welding method for welding a welded object in which grooves are inaccessible to electrode members, an inserter member that can be inserted into the grooves is formed of a predetermined material, and By forming an electrode member, each of which is in contact with one of the weldments and the inserter member, from a predetermined material, the contact surface between the welded objects is maintained at or above the melting temperature during the energization of the welding current, while the electrode and the welded object The contact surface between or between the electrode and the insert member is maintained below the melting temperature of the material. The electric resistance welding method according to the present invention has an advantage of enabling the welding of a welded object having a shape in which the electrode is difficult to access effectively.

Description

Electric resistance welding method

The present invention relates to an electric resistance welding method, and more particularly, to an electric resistance welding method to which an inserter is applied.

In general, electric resistance welding refers to a welding method in which a contact part is heated and melted at a high temperature by energizing a current in a state in which two metals to be joined are brought into contact with each other, and a joint is applied by applying a mechanical pressure to the contact part. Electric resistance welding includes electric spot welding and electric seam welding. Electric spot welding is to join a metal by heating the to-be-welded object with the heat source using the joule heat which arises by concentrating a large electric current in a to-be-welded object, and simultaneously apply a large pressing force. Electric spot welding is applied to the welding of the outer shell and aggregate of automobiles, and is widely used for welding aluminum alloys and stainless steels such as aircraft doors, engine exhaust ducts and combustion tubes.

On the other hand, electric seam welding is a kind of electric resistance welding which melt-presses a to-be-bonded object partially using electric contact resistance heat, and performs spot welding continuously. It is used for welding of steel pipes, etc., and it is applied to welding of automobile body. In aircrafts, tanks of aluminum alloy plates, stainless steel pipes for jet gases, and other types of jet engines are widely used for welding heat resistant alloys such as combustion chambers and exhaust pipes, and stainless steels.

According to the prior art, there may be a case where proper electric resistance welding cannot be performed depending on the shape of the object to be welded. For example, when attempting to weld a disk-shaped material having deep grooves requiring deep watertightness and airtightness by the electric resistance welding method at the grooved position, the most effective method is to connect the electrode to the inside of the groove. Insert and weld directly. However, when the diameter of the welding electrode formed in the shape of a disc is larger than the diameter of the groove, the electrode cannot be inserted into the groove, and therefore, welding in the direct groove is impossible. Therefore, welding is inevitably made by a separate method, which is achieved by, for example, stitch welding by continuous spot welding. However, when welding is performed through such a suboptimal method, welding must be performed at more points in order to achieve the same welding strength, and thus work tends to be more complicated.

The present invention has been made in order to achieve the above problems, an object of the present invention is to provide an electric resistance welding method that can effectively weld the welded object having a shape that the electrode is inaccessible.

It is another object of the present invention to provide an electric resistance welding method capable of welding a welded object having a deep groove by using an inserter.

1 is an explanatory diagram illustrating an electric resistance welding method according to the present invention.

2 is a graph of resistance and temperature for each contact surface of FIG.

* Explanation of symbols for main parts of the drawings

11,12 welded object 13,14 electrode

15: inserter 16: nugget

In order to achieve the above object, according to the present invention, in the electrical resistance welding method for welding a welded object formed with a groove in which the electrode member is inaccessible, an inserter member which can be inserted into the groove is predetermined. By forming a material and forming an electrode member in contact with each of the welded members and the inserter member with a predetermined material, the contact surface between the welded objects is maintained at or above the melting temperature when the welding current is energized. On the other hand, an electrical resistance melting point method is provided, wherein the contact surface between the electrode and the welded object or between the electrode and the insert member is kept below the melting temperature of the material.

According to another feature of the invention, the insert member is an alloy consisting of 99% copper (Cu) and 1% cadmium (Cd).

According to another feature of the invention, the electrode member is an alloy consisting of 99.2% copper (Cu) and 0.8% chromium (Cr), or 98.5% copper (Cu), 1.0% nickel (Ni) and 0.5 It is an alloy composed of% beryllium (Be).

According to another feature of the invention, the electrode member is an alloy consisting of 98.5% copper (Cu), 1.0% nickel (Ni) and 0.5% beryllium (Be).

According to another feature of the present invention, cooling by cooling water is performed in parallel to maintain contact surfaces other than the contact surfaces between the welded objects below the melting temperature of the material.

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

1 is an explanatory diagram showing that welding is performed by the electric resistance welding method according to the present invention. The electric resistance welding of the present invention is particularly for welding a welded object having a deep groove in which the electrode is difficult to access.

Referring to the drawings, the upper and lower to-be-welded objects 11 and 12 to which mutual welding is to be performed are arranged to keep in contact with each other. One of the objects 11 and 12 to be welded has a deep groove 12a formed therein, and an inserter 15 is inserted into the groove 12a. The inserter 15 is manufactured to have an appropriate shape so as to correspond to the shape of the groove 12a. The electrodes 13 and 14 are in contact with the upper welded object 11 and the inserter 15, respectively.

The current applied by the electrodes 13 and 14 is energized through the welded objects 11 and 12 and the inserter 15. In order for the welded objects 11 and 12 to be welded to each other, the electric resistance heat generated at the contact surface between the welded objects 11 and 12 must rise above the melting temperature of the welded object. Reference numeral 16 denotes a nugget portion formed by melting the welded objects 11 and 12 by electric resistance heat. On the contrary, the heat of electrical resistance generated by the other contact surface, for example, the contact surface between the welded object 12 and the inserter 15 or the contact surface between the welded object 11 and 12 and the electrodes 13 and 14 may be a material of interest. It should not be raised above its melting temperature.

2 is a graph showing the temperature generated by the electrical resistance at each contact surface. In FIG. 2, the line denoted by I 'corresponds to the line denoted by I in FIG. 1, and similarly, the line denoted by II' in FIG. 2 corresponds to the line denoted by II in FIG. 1, and III 'in FIG. The line denoted by 에 corresponds to the line denoted by III in FIG. 1, and the line denoted by IV ′ in FIG. 2 corresponds to the line denoted by IV in FIG. That is, the resistance for each portion indicated by the dotted line in FIG. 1 is shown on the vertical line in FIG. 2, and the temperature for each resistance is shown on the horizontal line.

Referring to FIG. 2, the temperature generated by the electrical resistance R2 occurring at the contact surface between the welded objects 11 and 12 is higher than the melting temperature T of the material, whereas the electrode 13 and the blood To the electrical resistance R1 between the weldment 11, the electrical resistance R3 between the welded object 12 and the inserter 15, and the electrical resistance R4 between the inserter 15 and the electrode 14. The temperature generated by this is lower than the melting temperature T. In this way, the electric resistance welding using the inserter 15 raises the temperature generated by the electric resistance at the contact surface of the welded object to be higher than the melting temperature of the material, while maintaining the contact temperature below the melting temperature of the material. It becomes possible.

Typically, the calorific value by the electrical resistance can be expressed by the formula Q = 0.24 I ² R t, where Q is the calorific value, I is the current, R is the electrical resistance, and t is the energization time. In applying this formula, since the current I and the energization time t are set under the same conditions, it is possible to control the amount of heat generated at each contact surface by setting the electrical resistance R appropriately.

According to the present invention, a specific material is selected in order to keep the electrical resistances R1, R3, R4 at each contact surface below the melting temperature. In one embodiment of the present invention, it is preferable that the material of the insert 15 is an alloy composed of 99% copper (Cu) and 1% cadmium (Cd). The materials of the electrodes 13 and 14 are also alloys of 99.2% copper (Cu) and 0.8% chromium (Cr), or 98.5% copper (Cu), 1.0% nickel (Ni) and 0.5% It is preferable that it is an alloy consisting of beryllium (Be).

On the other hand, it is possible to keep the temperature at each contact surface below the melting temperature of the material, in parallel with the appropriate selection of the material and appropriate cooling. Such cooling may be accomplished through various methods in the art. For example, cooling using a water bath may be performed, which is a method of performing electric resistance welding while the entire welded object is immersed in a water bath containing cooling water. Another cooling method is spray cooling, which is a method of applying coolant sprayed from a nozzle to a portion to be cooled. In addition, various cooling methods can be applied, and which cooling method is selected depending on the working conditions.

The electric resistance welding method according to the present invention has an advantage of enabling the welding of a welded object having a shape in which the electrode is difficult to access effectively. In particular, there is an advantage in that a direct welding at a predetermined position is possible by applying an appropriate insert and an electrode made of a specific material to the welded object having a deep groove, and at the same time appropriate cooling.

Although the present invention has been described with reference to one embodiment shown in the accompanying drawings, this is merely exemplary, and those skilled in the art may realize various modifications and other equivalent embodiments therefrom. I can understand. Therefore, the true scope of protection of the present invention should be defined only by the appended claims.

Claims (4)

Forming an insert member made of a predetermined material into which the electrode member can be inserted into a groove of the first to-be-welded inaccessible; Forming an electrode member in contact with the second to-be-welded object to be welded with the first to-be-welded material, and an electrode member respectively in contact with the inserter member with another predetermined material; Raising the contact surface temperature of the first and second to-be-welded materials above the melting temperature of the to-be-welded material by energizing the electrode members; And simultaneously with energizing the current, cooling the portions other than the contact surfaces between the welded objects by putting them in a water bath or spraying cooling water to maintain them below the melting temperature of the welded material. Electric resistance welding method. The method of claim 1 wherein the inserter member is an alloy consisting of 99% copper (Cu) and 1% cadmium (Cd). The electric resistance welding method according to claim 1, wherein the electrode member is an alloy made of 99.2% copper (Cu) and 0.8% chromium (Cr). The method of claim 1, wherein the electrode member is an alloy composed of 98.5% copper (Cu), 1.0% nickel (Ni), and 0.5% beryllium (Be).

Images