JPH0219750B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The stud welding method of the present invention is applicable to welding studs made of bolts or the like for fixing another structure or equipment to an underwater structure or for attaching corrosion protection. It is used for.

Conventional technology and its problems When welding studs to underwater structures, a small portable stud welding gun used on land is placed in a waterproof case, and air is pumped into the waterproof case from land to prevent water from entering. It is known that stud welding is performed in this state. According to this method, there is a problem that if a diver makes a mistake in operating the stud welding gun or turns the stud welding gun upward, water may enter the gun, making it unusable or causing a dangerous electrical leakage.

Therefore, an outer cylinder is watertightly attached to the tip of the stud welding gun, a ferrule holder and a ferrule are attached to the open end of the outer cylinder surrounding the stud, and gas is pressurized into the outer cylinder from land. An underwater stud welding gun was developed in which water is ejected from the gap between the stud and the ferrule, removes water directly under the stud, and is released into the water from the open end of the outer cylinder through a sponge in the form of bubbles. Invited to public notice. According to the underwater stud welding gun disclosed in this publication, water near the welding area is removed using gas pumped from land and the area is kept dry. While this has the advantage of reducing the risk of water intrusion due to incorrect operation, it also requires air hoses in addition to electrical wires for welding, control, and grounding, which makes work much more inconvenient and increases pressure. Since a gas supply source is required, the disadvantage is that the on-shore equipment becomes larger. Furthermore, during work, gas passes through the sponge that surrounds the tip of the outer cylinder and is released into the water in the form of fine bubbles, which obstruct visibility and make it difficult to check the status of the welding area. Surrounded by ferrules,
Since the ferrule holder, outer cylinder, and sponge are arranged concentrically in this order, it is unavoidable that the tip end has a large diameter, and therefore it is impossible to weld studs at narrow intervals smaller than the radius. Furthermore, if air is used as a gas, the partial pressure of oxygen will increase at high water depths, so it is necessary to use an inert gas, and while the stud welding gun is underwater, inert gas must be constantly pumped, so a large amount of inert gas must be used. It is also uneconomical as it consumes gas.

Purpose of the invention The present invention eliminates water near the welding part without pumping gas from land to perform welding.
To provide a stud welding method which eliminates the inconvenience of installing a pressure gas generation source on land and bringing an air hose of the same length as the electric wire to a stud welding gun, and which does not involve the drawbacks of the above-mentioned prior art. It is an object.

Structure of the Invention In order to solve the above-mentioned problems of the prior art, the underwater stud welding method according to the present invention surrounds the tip of the stud bitten by a stud welding gun with a heat-resistant elastic water sealing member, so that the welded portion can be sealed. A gas generating agent is applied to the stud, a water sealing member is brought into contact with the base metal, and an arc is generated between the stud and the base metal by the welding current. First, gas is generated from the gas generating agent using the arc heat, and the tip of the stud is heated. It was constructed by discharging surrounding water to the outside of the water seal member by gas pressure, and then welding the stud to the base material with the water removed.

Embodiment FIG. 1 schematically shows an example of a device for carrying out the invention.

The stud welding gun 1 has a cover 5 surrounding a chuck 4 and a stud S fixed to a piston rod 3 protruding from the tip of a gun body 2, and a cylinder body 6 made of a transparent insulating material, which are made watertight in order. A water seal member 7 made of a heat-resistant elastic material such as heat-resistant rubber is attached to the tip of the cylindrical body 6 in a watertight manner by means of an attachment cover 8. The arc shield 10 is fitted and fixed in the recess 9 at the center of the tip of the water seal member 7, and the stud S penetrates the water seal member 7 in a watertight manner with a packing material 11 such as an O-ring. The tip protrudes inside.

Although not shown in the drawing, the gun body 2 includes a piston at the base end of the piston rod 3, a stud pressure spring acting on the piston, and a stud S that separates the tip of the stud S from the surface of the base material W when welding current is applied. It has a built-in solenoid, start switch, etc. When the trigger 12 is pulled, the start switch is activated and the solenoid is energized, at the same time a welding current flows between the stud S and the base metal W, generating an arc, and a certain period of time elapses. Later, when the current supply is stopped, the solenoid is demagnetized and the stud pressurizing spring pushes the stud S against the base material W, and welding is performed using molten metal generated by arc heat and resistance heat.

Welding machine 1 including welding current power supply device and control device
3 is installed on land, and welding, grounding, and control wires 14, 15, and 16 extend from the welding machine 13.

The above welding operation is the same as normal stud welding, or without the water seal member 7, there is no difference from a stud welding gun used on land.

The feature of the present invention is that the gas generating agent 17 is attached to the welded part surrounded by the water sealing member 7, and the gas generating agent 17 is thermally decomposed by arc heat to generate gas and remove the water around the tip of the stud. The point is that gas pressure is used to discharge the water out of the water sealing member and welding is performed in an atmosphere in which water is not present.

That is, a gas generating agent 17 made of a substance that generates an inert gas such as carbon dioxide gas at a relatively low temperature, such as sodium bicarbonate, is kneaded with a binder or wrapped in a waterproof film and made insoluble in water, is applied to the tip surface of the stud S. This stud S is inserted into the water sealing member 7 so as to be engaged with the chuck 4, and the tip thereof is made to protrude slightly from the front end surface of the water sealing member 7. Separately, in order to ensure the reliability of welding, a flux 18 that does not decompose into water or melt, for example in the form of a colloid, is applied to the portion of the base material W to be welded (FIG. 2).

Next, when the stud welding gun 1 is pressed perpendicularly to the base metal W, the stud S is pushed in and the water seal member 7 is compressed and comes into close contact with the surface of the base metal W, and the arc shield 10, the stud S, and the base metal W are A narrow enclosed chamber space 19 is formed. (Figure 3). When the stud S is pulled away from the base metal W at the same time as the welding current is applied, an arc is generated, and the gas generating agent 17 is first thermally decomposed by the arc heat to generate gas explosively, and the gas pressure causes the stud S to separate from the base metal W. The water in the sealed space 19 is then discharged from the gap between the water seal member 7 and the base material W to the outside of the water seal member 7 as shown by the arrow 20 (fourth
figure). Next, the tip of the stud S and the surface of the base material W are melted by arc heat and resistance heat, and the molten metal 21
Since the sealed space 19 is maintained at a high pressure by arc heat, molten metal heat, etc., water intrusion is prevented. When the current supply is stopped after a certain period of time has elapsed, the stud S is pressed against the base material W, and welding is performed by the molten metal 21 (fifth
figure).

The gas generating agent 17 may be attached to the surface of the base material W, but it may also be attached to the arc shield 10 or the water seal member 11 when a substance with a low decomposition temperature is used.

Furthermore, without once separating the stud S from the base material W and generating an arc, the stud S is moved to the third position.
The present invention is also applicable to a stud welding method in which an arc is generated while the stud is fixed at the set position shown in the figure.

Effects of the Invention According to the present invention, the tip of the stud is surrounded by a water sealing member so that a sealed space is formed when it comes into contact with the submerged base material, and the gas generating agent attached to the welding part is heated by the welding arc. Since the stud is first pyrolyzed using heat to generate gas and drain the water in the closed space, then welds the stud to the base material, there is no need for an air hose, so there is no loss of freedom of work, and it is easy to use on land equipment. In addition, gas is not released to the outside until the stud is set in place and the welding current is applied, so there is no obstruction to the view due to air bubbles, and it is possible to confirm that the stud has been accurately placed at the welding location. This allows for reliable welding. Since the water seal member is heat-resistant and elastic, it not only withstands welding heat and adheres well to the surface of the base metal, but also allows gas pressure to easily form a gap for water to drain, allowing water to be completely removed. This allows for strong welding.

Furthermore, according to the present invention, by generating an inert gas, it is possible to stably generate an arc even in places with high water depths, and reliable welding can be expected.In addition, since gas is generated only during welding, it is also economical. It is excellent. Furthermore, the diameter of the water sealing member surrounding the tip of the stud can be reduced because it is sufficient to create a narrow sealed space necessary for welding, making it possible to weld the studs at narrow intervals.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of an apparatus for implementing the present invention, and FIGS. 2, 3, 4, and 5 are longitudinal sectional views illustrating a welding process. S... stud, W... base metal, 1... stud welding gun, 4... chuck, 6... cylinder body, 7... water sealing member, 13... welding machine, 17... gas generating agent,
19... Closed space, 21... Molten metal.

Claims (1)

[Claims] 1. Surround the tip of the stud that is bitten by a stud welding gun with a heat-resistant elastic water sealing member, apply a gas generating agent to the welding part, and bring the water sealing member into contact with the base metal to create a space between the stud and the base metal. An arc is generated by the welding current, gas is first generated from the gas generating agent using the arc heat, water around the stud tip is discharged outside the water seal member by gas pressure, and then the water is removed. An underwater stud welding method characterized by welding a stud to a base metal.