JPS6333959B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Object of the Invention) The present invention relates to a method of manufacturing a flux-cored wire for automatic and semi-automatic welding.

(Prior Art) Generally, a flux-cored wire for welding is a composite of a steel strip formed into a certain cross-sectional shape and filled with powdery flux consisting of a deoxidizing element, a slag-forming agent, etc. This welding wire is used in a wide range of applications, from mild steel to low-alloy and high-alloy steel welding.

The conventional manufacturing method for flux-cored wire is to form a thin steel plate strip into a U shape, and then uniformly fill it with powder-like welding flux whose composition has been adjusted to a specified level.
The wire is drawn after being formed into a predetermined cross-sectional shape. Wires produced in this way have various drawbacks.

In other words, when a flux-cored wire is manufactured or made into a product, the joints tend to open, which hinders wire manufacturing. When substances penetrate into the flux and are used for welding, they may increase the diffusible hydrogen in the weld metal or promote oxidation of the metal strip surface on the inner surface of the wire, increasing oxygen in the weld metal.
Degrades the mechanical performance of the deposited metal. In addition, in the case of solid wire for welding, copper plating is applied to the surface of the wire for the purpose of preventing rust and improving conductivity during welding, but the flux-cored wire for welding mentioned above does not have this plating. Processing cannot be applied. The reason for this is that copper plating is a wet method in which the object to be plated (wire) is immersed in a plating bath to apply plating, which causes the inconvenience that the plating liquid may seep into the wire through the seams. be.

As a method to overcome this drawback, it has been proposed to weld and join the joints of the cladding tubes in parallel with the filling of flux. For example, JP-A-54-109040
According to the publication, a steel strip is formed into an open groove, and flux powder is dropped and supplied into the groove to an extent that is not enough to enter the pipe during the next pipe making welding, and then the edges of the groove are closed together and the longitudinal A method is shown for manufacturing a sealed tube with welded directional connections by continuously forming the tube and reducing the size of the tube so as to tightly pack the flux powder inside the tube. In this method, the flux is configured so that it occupies only a part of the pipe rather than the entire pipe during welding, because if the welding position and flux position are too close, they will have a negative effect on each other. This is to prevent excessive heat from reaching the flux. In other words, when welding the edge of a groove in a steel strip, the heat generated by welding changes the flux composition,
Or there is a risk of making it inappropriate.
Another reason is that the flux swirls around due to the magnetic field present due to welding and can adhere to the contact surface of the groove edge, weakening the weld. This problem can also be solved by the above manufacturing method. It was not recognized that the problem had been solved sufficiently, and welds and flux were forced to have a negative effect on each other. Further, according to the above manufacturing method, since the amount of flux supplied is limited, the flux filling rate of the product is inevitably limited to a low level, which is also a disadvantage. Furthermore, in the tube size reduction process after welding, the entire tube is filled with flux, the air inside the tube is removed, and the flux is tightly packed to prevent the flux from moving in the tube's longitudinal direction, but at this time, variations in the flux filling rate tend to occur. There is a problem.

(Objective of the Invention) The present invention is to solve all of the above conventional problems, that is, to provide a welding flux that does not open the wire seam during manufacturing or in the product, and that can be subjected to plating treatment such as copper plating. One of the objects is to provide a method for manufacturing a cored wire, and an important object is to provide a method for manufacturing a flux-cored wire for welding with good production efficiency and good product quality. do.

(Structure of the Invention) The gist of the present invention to achieve this object is to place a hollow steel pipe at a flux filling position with an angle of repose greater than the angle of repose of the flux, and to inject flux into the steel pipe through the upper end hole of the steel pipe. A flux-filled steel pipe is made by repeating the operation of dropping flux into the hollow steel pipe, welding the steel pipe and a new hollow steel pipe, and repeating the process of dropping flux into the hollow steel pipe again and filling it. Making,
The purpose is to reduce the diameter of the flux-filled steel pipe to a desired diameter.

The contents of the present invention will be explained in detail below based on specific examples.

FIG. 1a is a sectional view showing a specific example of the process of filling flux into a hollow steel pipe. At the flux filling position, a straight steel pipe 1 of fixed length is fixed with a plurality of fixing jigs 2 and stands vertically as shown in the figure. The tip of a flux supply pipe 5, which is connected to a small-capacity flux hopper 3 that receives the incoming flux powder, and is equipped with a flux flow rate adjustment valve 4 is inserted. The lower end of the steel pipe 1 is plugged with a vinyl hose 7 whose one side is closed with a clip 6 and is stopped with a fixture 8 to prevent the flux supplied from the upper end hole of the steel pipe 1 from spilling out. Further, the steel pipe 1 is vibrated by one or more vibrators 9 at the same time as the flux is introduced from the flux hopper 3, so that the steel pipe 1 is filled with flux 10 at a uniform sediment density.

In this way, the flux in the flux hopper 3 is dropped and supplied into the steel pipe via the flux supply pipe 5, but as the supply filling progresses, the upper surface of the flux 10 in the steel pipe 1 and the steel When the distance l from the upper end of the pipe reaches a predetermined length, the flux flow rate regulating valve 4 is closed to stop the supply of flux. This distance l is determined by the fact that when welding together the upper end of a steel pipe that has been filled with flux and the lower end of a new hollow steel pipe (Fig. 2b), the welding work and the filled flux (top surface) have an adverse effect on each other. The distance of the upper surface of the flux 10 is preferably at least as long as the inner diameter of the steel pipe, preferably several times the inner diameter. Feedback is provided to the flux flow rate adjustment valve 4, and a predetermined distance l is provided from the upper end of the steel pipe.
The flux supply is stopped when the distance reaches the distance.

When the flux has been filled into the steel pipe 1, as shown in FIG. After that, a new hollow steel pipe 1' is placed at the flux filling position, and the upper end of the flux-filled steel pipe 1 and the lower end of the hollow steel pipe 1' are welded together, for example, by TIG welding. Transfer of the steel pipe 1 is carried out by releasing the fixation using the fixing jig 2, and transferring the steel pipe 1 while being held by transfer rollers (not shown).After the transfer, the steel pipe 1 is fixed again using the fixing jig 12, and then transported in an upright position to the fixing jig at the flux filling position. It is welded and joined to the new hollow steel pipe fixed in step 2. During this time, the flux supply device 3,
4 and 5 are lifted upward and in a standby state as shown in the figure. FIG. 2b is an enlarged view of the joint between the steel pipes 1 and 1', and 14 indicates the weld. After the steel pipes 1 and 1' have been joined in this way, the flux supply devices 3, 4, and 5 are lowered again, the flux supply pipe 5 is inserted into the upper end hole of the steel pipe 1', and the flux flow rate adjustment valve 4 is opened. , vibrator 9
Turn it ON to vibrate the steel pipe 1', start supplying flux falling, and fill the steel pipe 1' with flux in the same way as in the case of the steel pipe 1. Thereafter, this operation is repeated until the desired weight is achieved to produce a flux-filled steel pipe.

The flux-filled steel pipe thus obtained is then reduced in diameter to a desired diameter using a drawing die, roll rolling, or the like. During this process, annealing, plating, etc. are performed as necessary to obtain a flux-cored wire for welding as a product.

In the plating process, copper plating is mainly applied to the steel pipe for the purpose of preventing rust on the surface and improving conductivity during welding, but this point is similar to solid wire for welding, and conventional wire with seams is As mentioned above, plating cannot be performed. In addition, plating processing is not limited to copper plating, but also other
Single metal plating with Mn, Zn, Ti, Al, Ni, Cr, Sn, Sn+Cu alloy plating, double plating with Ni+Cr, etc. may be applied as long as the properties of the weld metal are not impaired. Needless to say.

In the present invention, the steel pipe to be used for flux filling may be either a welded pipe such as an electric resistance welded pipe in which a steel strip is formed into a cylindrical shape and the joints are welded, or a seamless pipe that does not have a welded joint. , to be selected depending on the situation. The length of the pipe is, for example, 5 to 20 m.

In addition, mutual welding of steel pipes is done by butt resistance welding,
There are various methods such as TIG welding, but if the back bead of the weld part protrudes too much on the inner surface of the pipe, it will hinder the supply and filling of flux, so it is preferable to perform TIG welding in which the bead does not protrude too much.

In addition, in the above specific example, the steel pipe is erected vertically,
In other words, the angle of inclination of the steel pipe is 90° (maximum value of the angle of inclination)
An example of supplying and filling flux was shown as
In the present invention, it is necessary to maintain the steel pipe at an angle that is equal to or higher than the angle of repose at which the flux falls from the steel pipe under its own weight. Further, although powdered flux was used as the flux supplied and filled into the steel pipe, pelleted flux may also be used. This pellet-like flux is made by dry mixing flux raw materials in a predetermined ratio, adding a binder such as water glass, mixing for an appropriate time in a fret mill, extruding it through a nozzle hole with a press, shaping it, and drying it. get it.

Further, in the above-described specific example, the steel pipes filled with flux are wound around the bobbin, but the invention is not limited to this, and the pipes may be coiled and laminated using a coiler.

(Example) A flux-cored wire for CO ₂ gas arc welding was manufactured based on the specific example of the present invention shown in FIGS. 1 and 2.

Steel pipe: outer diameter 25.4mm, wall thickness 5.0mm, pipe length 5.5
m Filling flux: Main ingredients are rutile, Si-Mn, and iron powder.

Joining of steel pipes: 20 steel pipes were joined using TIG welding to create a flux-filled steel pipe with a total length of 110 m. Distance l = 30 mm Product wire: Wire diameter 1.6 mm, surface copper plating As a result, production efficiency was good, and the quality of the flux-cored wire for welding obtained was good. That is, when welding was performed using this product wire, both the wire feedability and welding workability were good, the amount of diffusible hydrogen in the weld metal was low, and the mechanical properties were extremely good.

(Effects of the Invention) The effects of the flux-cored wire for welding of the present invention are summarized as follows.

Since the welding of the same steel pipe can be carried out at a sufficient distance from the filling flux, the welding operation and the flux do not adversely affect each other.

Since the outer diameter and wall thickness of the pipe during flux filling and, in the case of pelletized flux, the amount of flux supplied can be arbitrarily selected, a wider range of filling rate designs can be made than in conventional manufacturing methods. Moreover, there is no variation in the filling rate.

Since the filling of flux into the steel pipe and the joining of the steel pipes are carried out separately, each can be carried out in the optimum conditions without interfering with each other, resulting in extremely efficient and high productivity.

Since there are no openings in the longitudinal direction of the steel pipe, the internal flux does not deteriorate during manufacturing or due to factors such as moisture or lubricant entering from the outside of the product, and product quality as designed can always be obtained. It is also possible to perform plating or other surface treatments on the wire surface.

[Brief explanation of the drawing]

FIG. 1a is a sectional view showing a specific example of the flux filling process in the present invention, and FIG. 1b is a partial view showing a state in which the filling has progressed. FIG. 2a is an explanatory view showing a step of joining the steel pipes together following the flux filling step, and FIG. 2b is a partially enlarged view thereof. 1, 1'... Steel pipe, 2, 12... Fixing jig,
3...Flux hopper, 4...Valve, 5...
... Flux supply pipe, 6 ... Clip, 7 ... Vinyl hose, 8 ... Fixture, 9 ... Vibrator, 1
0...Flux, 11...Top surface detection device, 13
... Winding bobbin, 14 ... Welding part.

Claims (1)

[Claims] 1. Place a hollow steel pipe at a flux filling position by tilting it above the angle of repose of the flux, fill the steel pipe with flux by dropping it from the upper end hole of the steel pipe, and then connect the steel pipe and a new hollow steel pipe. A flux-filled steel pipe is made by repeating the operation of welding and joining the hollow steel pipe and then dropping and filling the hollow steel pipe with flux several times, and reducing the diameter of the flux-filled steel pipe to a desired diameter. A method for manufacturing flux-cored wire for welding.