JPH11179564A - Welding equipment and welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a welding equipment and method which prevent temperature from lowering in a weld zone through the ejecting of shielding gases and which is free from degradation in the quality of the weld zone in the induction welding using shielding gas. SOLUTION: This welding equipment is provided with a power unit 1 for welding, induction heating coil 2 connected to this power unit 1, shielding gas supply source 3, shielding gas ejecting nozzle 5 connecting to the shielding gas supply source 3 which is provided to face the weld zone of an object to be welded 4, 4 surrounded with the induction heating coil 2, and a heating device 7a of shielding gases which are supplied from the shielding gas supply source 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus and a method for welding an object to be welded by induction heating.

[0002]

2. Description of the Related Art Induction welding is widely used for joining steel pipes, reinforcing bars, and the like. However, the quality of a joint (welded) portion is deteriorated due to oxides generated by oxygen in the atmosphere during welding. Sometimes.

In order to prevent the oxidation of the joint of the workpiece, an attempt has been made to shield the joint with an inert gas such as argon gas at the time of welding.

This is, for example, a structure as shown in FIG. 4. In FIG. 4, 1 is a welding power supply, 2 is an induction heating coil connected to the power supply 1, 3 is a shield gas supply source such as an argon gas cylinder, Reference numerals 4 and 4 denote welded objects such as steel pipes with their end faces abutting each other. Also,
Reference numeral 5 denotes an injection nozzle whose tip is directed to the vicinity of the joined part where the workpieces 4 and 4 are joined, and reference numeral 6 denotes a gas supply pipe such as a hose connecting the shield gas supply source 3 and the injection nozzle 5.

In such a configuration, the welding operation is performed by supplying argon gas from the shielding gas supply source 3 to the supply pipe 6.
Is supplied to the induction heating coil 2 while blowing argon gas from the injection nozzle 5 to the vicinity of the portion to be welded including the portion to be welded, and the portions to be welded are melted and bonded to each other.

[0006] As described above, the degree of oxidation can be reduced by covering the portion to be joined with the shielding gas during welding.

[0007]

However, as described above, when the parts to be welded are shielded in a shielding gas atmosphere during welding, the parts to be welded are cooled by the shielding gas to lower the temperature, and a predetermined bonding strength is obtained. However, there is a problem that the quality of the joint is adversely affected.

[0008] This means that the greater the amount of the shielding gas sprayed, the more the oxidation of the joint can be prevented. However, the greater the amount of the shielding gas sprayed, the cooler the part to be joined, the lower the temperature, and the predetermined joint strength. There is a vicious cycle that additional heating is required to obtain But,
When the welding temperature is increased, there is a problem that the amount of the shielding gas to be sprayed must be further increased in order to prevent oxidation.

The present invention has been made in view of the above circumstances, and in induction heating welding using a shielding gas, it is possible to prevent a decrease in temperature of a portion to be welded (welded) due to spraying of a shielding gas, and to improve the quality of a welded portion. It is an object of the present invention to provide a welding device and a welding method that are not likely to lower.

[0010]

According to a first aspect of the present invention, there is provided a welding apparatus including a welding power supply, an induction heating coil connected to the power supply, a shielding gas supply source, and the induction heating coil. A shield gas injection nozzle connected to the shield gas supply source provided facing a portion to be joined of the workpiece to be surrounded; and a heating device for a shield gas supplied from the shield gas supply source. It is characterized by the following.

By spraying the high-temperature shielding gas, it is possible to suppress a decrease in the temperature of the portion to be joined heated by the induction heating coil, so that the strength of the joint (weld) is not reduced and oxidation occurs at the joint (weld). Can be prevented. In addition, when the argon gas is heated, the gas is thermally expanded, and the amount of the gas used is reduced and the cost is reduced if the pressure is the same as compared with the use at room temperature.

It is preferable that a plurality of spray nozzles be provided so that the shield gas uniformly covers the portions to be joined (welded).

Further, the shield gas heating device may be provided at one place and distributed to each injection nozzle after heating.
Further, the shielding gas may be an inert gas such as argon or helium, or a gas such as nitrogen or carbon dioxide.

[0014] A welding apparatus according to a second aspect of the present invention is characterized in that the heating apparatus for the shielding gas is a resistance heating heater, an induction heating coil or an adiabatic compression apparatus.

The above-described resistance heating heater, induction heating coil or adiabatic compression device can be easily provided in the gas supply pipe.

A welding method according to a third aspect of the present invention is characterized in that welding is performed while injecting a high-temperature shielding gas onto a portion to be welded of a workpiece surrounded by an induction heating coil connected to a welding power supply device. And

According to the first aspect of the present invention, the same operation as described above is achieved.

The welding method according to a fourth aspect of the present invention is characterized in that the shielding gas is heated by a resistance heater, an induction heating coil or an adiabatic compression device provided in a gas supply path.

According to the second aspect of the present invention, the same operation as described above is achieved.

[0020]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of an induction heating welding apparatus.

In FIG. 1, reference numeral 1 denotes a welding power supply device having a high-frequency oscillator, 2 denotes an induction heating coil connected to the power supply device 1, 3 denotes a supply source of a shielding gas, for example, an argon gas cylinder, and 4 and 4 denote steel pipes and reinforcing bars. The welded parts, whose end faces are butted with each other, are located in the coil 2 surrounded by the induction heating coil 2.

Reference numerals 5 and 5 denote a plurality of wires, here 2.
The injection nozzles 6 are gas supply pipes formed of a hose or the like connecting the shield gas supply source 3 forming the supply path of the shield gas and the injection nozzles 5, 5. A tubular electric heater that generates resistance heat by energizing the gas supply pipe 6 with a gas heating device provided in the foreground;
Numerals 8 and 8 are power supply lines to the electric heater.

In such a construction, in the welding operation, argon gas is supplied from the shielding gas supply source 3 to the injection nozzle 5 through the gas supply pipe 6 and the power supply lines 8, 8 are energized to turn on the electric heaters 7a, 7a. Heat. By the electric heaters 7a, 7a, a high-temperature argon gas is blown from the injection nozzle 5 to the vicinity of the portion to be joined including the portion to be joined,
By energizing the induction heating coil 2, the portions to be welded are melted and joined by fusion.

At this time, when a high frequency current having a frequency higher than the commercial frequency of 50 Hz or 60 Hz is used as the welding current, the larger the current, the closer to the surface of the workpiece and the closer to the coil due to the skin effect and proximity effect. That is, the end face of the portion to be joined and the periphery thereof are rapidly heated. In the vicinity of the melted joint, there is a high-temperature argon gas atmosphere in which a high-temperature argon gas is blown, so that a decrease in the temperature of the joint due to the blowing of the argon gas can be suppressed. Also, the spraying of the high-temperature argon gas may be stopped when the joining of the parts to be joined is completed and the temperature reaches a temperature at which no oxidation occurs, or the temperature of the joining part may be decreased in a short time by lowering the argon gas from a high temperature to a normal temperature. You may do so.

Therefore, according to this embodiment, by blowing the high-temperature argon gas, it is possible to suppress a decrease in the temperature of the portion to be joined heated by the induction heating coil 2 and to prevent a decrease in the strength of the joining (welding) portion. Oxidation can be prevented from occurring at the welded portion. In addition, heating the argon gas causes the gas to thermally expand, so that if the pressure is the same as compared with the use at room temperature, the amount of use is reduced and the cost is reduced.

FIGS. 2 (a) and 2 (b) show another embodiment of the apparatus for heating a shielding gas according to the present invention. In FIG. The reference numerals are attached and the description is omitted.

In the gas heating apparatus shown in FIG. 2A, a part of the shielding gas supply pipes 6, 6 is formed by a steel pipe 8, and induction heating coils 7b, 7b are arranged on the outer circumference of the steel pipe 8. By supplying power to the induction heating coils 7b, 7b, the argon gas sent from the shielding gas supply source 3 and passing through the steel pipe 8 is heated.

The gas heating device shown in FIG.
Adiabatic compressors 7c, 7c that utilize the action of increasing the temperature of the gas when compressed gas are compressed in the middle of the shield gas supply pipes 6, 6 are used to convert the argon gas sent from the shield gas supply source 3 into an adiabatic compressor. 7c, heating by passing through 7c.

The heating device shown in FIGS. 2A and 2B has the same operation and effect as the above embodiment.

The present invention is not limited to the above embodiment. For example, it is preferable that the spray nozzles for spraying the shielding gas are provided not only at two places but also at two or more places so as to cover portions to be joined (welded) evenly.

The shield gas heating device is not provided for each injection nozzle, but is provided in one place, and after heating the gas,
You may make it distribute to each injection nozzle.

The shielding gas may be an inert gas such as argon or helium, or a gas such as nitrogen or carbon dioxide.

Further, in the above-described embodiment, the case where a steel pipe or the like is connected as a welding member has been described. You can do it.

[0034]

According to the first and second aspects of the present invention, the quality of the joint (weld) portion is prevented from being reduced, and the quality of the joint (weld) portion is prevented from being oxidized. This has the advantage that a welding device that can reduce the consumption of shielding gas can be provided.

According to the third and fourth aspects of the present invention, the quality of the joint (weld) portion is prevented from being reduced while preventing the occurrence of oxidation at the joint (weld) portion. There is an advantage that a welding method with reduced consumption of shielding gas and reduced cost can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an induction heating welding apparatus according to the present invention.

FIGS. 2 (a) and 2 (b) are schematic structural views showing another embodiment of the shielding gas heating apparatus of the present invention.

FIG. 3 is a schematic configuration diagram showing a conventional induction heating welding apparatus.

[Description of Signs] 1: Power supply device for welding 2: Induction heating coil 3: Supply source of shielding gas (Argon gas cylinder) 4: Workpiece 5: Injection nozzle 6: Gas supply pipe 7a: Gas heating device (electric heater) 7b: Gas heating device (induction heating coil) 7c: Gas heating device (adiabatic compression device)

Claims (4)

[Claims] 1. A welding power supply, an induction heating coil connected to the power supply, a shield gas supply source, and the shield gas provided facing a portion to be welded of a workpiece surrounded by the induction heating coil. A welding apparatus comprising: a shield gas injection nozzle connected to a supply source; and a heating device for a shield gas supplied from the shield gas supply source. 2. The welding apparatus according to claim 1, wherein the heating device for the shield gas is a resistance heating heater, an induction heating coil, or an adiabatic compression device. 3. A welding method characterized by welding while injecting a high-temperature shielding gas to a portion to be welded of a workpiece surrounded by an induction heating coil connected to a welding power supply device. 4. The welding method according to claim 3, wherein the shielding gas is heated by a resistance heater, an induction heating coil, or an adiabatic compression device provided in a gas supply path.