JPS59191591A - Production of flux-cored wire for welding - Google Patents

Abstract

PURPOSE:To permit easy flux packing and to obtain a flux-cored wire contg. less moisture and gas by packing the flux in a steel pipe, and subjecting the steel pipe to hot rolling then to cold drawing thereby forming the steel pipe into a wire having a prescribed diameter. CONSTITUTION:A flux-packed steel pipe 1 is preliminarily heated in a soaking furnace and thereafter the steel pipe is reduced to a considerably smaller diameter by a hot rolling stage. After venting parts 3, 3 at both ends of the flux- packed steel pipe are cut off, the steel pipe is subjected to cold drawing and a surface treatment such as plating to manufacture a flux-cored wire for welding having a prescribed diameter. Since the flux-cored steel pipe is exposed to a high temp. in the hot rolling stage as mentioned above, the moisture in the flux is inevitably driven off to the outside and the process for producing said wire is simplified without requiring particularly a stage for removing moisture in order to remove the diffusible hydrogen in the weld metal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a seamless welding flank wire.

Flux-cored wire for welding is a wire with a composite structure in which a metal-sheathed steel pipe is filled with granular flux consisting of a deoxidizing agent, a slag forming agent, etc., and can be used for welding a wide range of materials, from mild steel to low-alloy steel, high-temperature alloy steel, etc. It is used for many purposes.

Conventional methods for manufacturing flux-cored wires for welding can be roughly divided into two methods. One method is to form a thin steel strip into a U-shape, and then weld it in the form of powder particles after predetermined composition adjustment. There is a method in which the wire is uniformly filled with flux, formed into a predetermined cross-sectional shape, and then wire-drawn. Although this method is a manufacturing method commonly used at present, the flux-cored wire manufactured by this method has various drawbacks because it has seams. ′? I- In other words, the joint is easy to open, and moisture on the outer surface of the wire or organic substances such as lubricants used during the manufacturing process can enter the flux in the outer steel pipe through the opening. When welding using a wire, the mechanical performance of the weld zone deteriorates due to increased diffusible hydrogen in the weld metal, or oxidation of the inner skin wall of the wire to increase oxygen in the weld metal. Also, since it has seams, it cannot be plated and therefore has poor rust resistance.

Other methods overcome the shortcomings of the above methods, such as welding the joints of the copper strips after filling with flux, or
Another method is to fill the steel pipe with flux. The method of welding the joints of copper strips has the drawback of poor productivity and increased cost. Also, among the methods of filling steel pipes with flux, the method of filling each straight pipe one by one has a limit on the amount of filling per unit, making it difficult to produce on a corporate basis.

In other words, if the length of the steel pipe exceeds l'QIni, it becomes extremely difficult to transport the steel pipe and complicate the flux filling device. As a way to solve this problem, for example,
The technique described in Japanese Patent No. 937 is known. In this method, a long steel pipe is coiled and flux is transported and filled into the pipe through the open part of the pipe using vibration. This method does make the filling unit larger, but the process of filling the slender steel pipe with flux takes a long time, and there are differences in specific gravity and particle size between each type of flux. This back mixing phenomenon occurs and segregation occurs in the filled flux, making it difficult to satisfy the product quality of the flux-cored wire.To solve this problem, (after preparing the flux in advance, granulation with a binder such as water glass) However, according to this method, the 7lacs tends to absorb moisture, so it is necessary to incorporate a moisture removal step in which the 7lux is heated in a heating furnace at around 500°C for 1 hour or more after filling.However, by granulation, Although flux segregation is eliminated to some extent, it is not satisfactory.

The first purpose of the present invention is to simplify flux filling (rubbing), and the second purpose is to create a flux filling with no joints, less segregation of 7 lux, less moisture and gas content, and low cost. is to provide the wire.

In order to achieve the above object, the present invention has a steel pipe (
Filled with pellet-shaped flux, this steel pipe is hot rolled and stretched, and then cold wire drawn to form a wire of a predetermined diameter. That is, in the present invention, a flux-filled steel pipe is used as a starting material, which is a large-diameter steel pipe filled with flux whose composition has been adjusted in advance, and this is hot-rolled (the cross section is reduced to a thick width), and then cold-drawn. By doing so, we aim to improve the quality of flux-cored wires for product welding by completely removing moisture in the flux, preventing segregation of the filling flux in the wire, and performing surface treatments such as plating, as well as shortening manufacturing time and streamlining the manufacturing process. Achieve simplification and cost reduction.

In the present invention, the pellet-like flux refers to the following (0 or (ri).

■ After dry mixing the flux raw materials in a constant ratio of /9i, a binder (for example, water glass) is applied with a male blade.
The mixture is wet-mixed for an appropriate time using a fret mill or the like, and then extruded from a nozzle using a press to form a pellet-shaped 7-lux mass. This pellet-shaped 7 lux lump (
It is preferable that the shape of the pellet (hereinafter referred to as a pellet) is cylindrical to match the cross-sectional shape of the pipe, and the diameter of the cylinder is within a range of about 05 to 9 times the inner diameter of the pipe, so that it can be filled with the desired filling role in advance. The length of the cylinder is determined based on the strength of the pellet itself and the insertion method, and the appropriate length is within the range of 2 to 5 times the diameter of the pellet. The pellet feeding process (requires strength that does not break during rolling) and brittleness that does not break easily during the subsequent rolling process.The strength of such pellets depends on the proportion of binder and drying. Adjust by degree.

■ Predetermined ratio [After dry mixing the blended flux raw material IA, pack it into a bag to obtain a pellet-like flux. In this case, the material of the bag should be selected so that it does not adversely affect the quality of the flux-cored wire for welding.

The method for inserting the pellet-shaped flux into the steel pipe is as follows: (1) Forcibly inserting the pellet-shaped flux into the steel pipe using a pellet-shaped flux punching device. (2) Method of inserting the pellet-shaped flux into the steel pipe. There are methods such as inserting the pellet-shaped flux by sliding it into the steel pipe by tilting the flux at an angle higher than the angle of repose of the flux, and a more precise method may be adopted depending on the situation.

In the present invention, the range of the outer diameter of the steel pipe is preferably D≧50.The reason is that if D<50 mm, the filling unit becomes too small, which improves work simplification, efficiency, and product quality. This is because it is disadvantageous in terms of equalization, etc. The upper limit of the diameter of the steel pipe is preferably about 200 mm from the point of view of hot rolling equipment capacity.

Also, the ratio t/D of the steel pipe outer diameter and the pipe wall thickness t is O1≦t/1)
≦03 is good. The reason for this is that if t/D is less than O,1, the strength of the cold wire drawing ζ trowel will be insufficient and wire breakage will easily occur during wire drawing, which tends to impede productivity.
This is because when winding the wire onto a spool as a product in the final step G, breakage is likely to occur due to insufficient strength.

On the other hand, when t/f) exceeds 03, the flux filling rate (flux weight/wire weight x 100%) decreases, and there is a tendency for the deoxidizer, slag forming agent, etc. in the flux required for slack-cored wire for welding to be insufficient. This is because there is Note that the flux filling rate is, for example, about 9 to 15%.

The diameter of the flux-filled steel pipe after hot rolling, that is, the finished diameter of hot rolling, is not particularly limited, but is approximately 5 to 20 mm, considering the current general-purpose hot rolling equipment and the cold wire drawing process in the subsequent process.
The appropriate area is within the throat.

Note that flux-filled steel pipes are subjected to hot rolling and exposed to high temperatures, but it is necessary to take into account the composition of the flux filled in the steel pipes so that the quality does not change due to this high-temperature heating. However, there are cases where it is unavoidable to fill the flux with a low melting point as a welding flux, so the hot rolling temperature is slightly lower than the hot rolling temperature from a normal steel ingot, taking into consideration the deterioration of the flux. It is desirable to keep the temperature low. For example, the hot rolling temperature is 750 to 900°C.

In a preferred embodiment of the present invention, a gas vent is formed at one or both ends of the slack-filled steel pipe, which is used when the flux-filled steel pipe is heated to a high temperature in a soaking furnace or hot rolling process. In order to efficiently discharge gas that is generated inside the pipe and expands due to the thermal expansion of the residual air inside the steel pipe and the vaporization of the moisture attached to the flux into the steel pipe without causing the flux to flow out. In addition, during hot rolling, the flux filled with the gas may also leak from the gas venting part and damage the rolling rolls, etc., so a tab part is provided in the gas venting part to prevent the leakage flux from dissipating. It is desirable to provide one.

Hereinafter, the present invention will be explained more specifically with reference to the drawings.

Figure 1(a) is a diagram showing a specific example of a flux-filled steel pipe that is a starting material for hot rolling. In the figure, 1 is a steel pipe, 2 is a pellet filled in the steel pipe, and Squeeze both ends by swaging, etc.
A gas venting portion 3 is formed by providing a gas venting hole 5.

This gas venting part serves to prevent flux from flowing out during rolling, and also to discharge gases such as thermally expanded air and water vapor from the gas venting hole. 4 is a gas venting seal, which has a waste venting hole 5 (
I will set this up. The material for the gas vent seal 4 is preferably a thin steel plate with a large number of gas vent holes, such as steel wool or crow wool.

FIG. 1(b) is a sectional view taken along line A-A in FIG. 1(a),
A cylindrical pellet 2 is shown inserted into a steel pipe 1. In this case, depending on the steel pipe dimensions and desired flux filling rate, if the diameter of the cylindrical pellet is smaller than the inner radius of the steel pipe, there is a possibility that the pellets will be inserted overlapping each other, resulting in a donut-like (hollow cylindrical) shape. Beret (
It is desirable that the outside diameter of the pellet be greater than the inside radius of the steel pipe.

Figure 2 shows both ends of the flux-filled steel pipe shown in Figure 1.
It is a figure which showed the example which provided the tab 7 for leakage flux dissipation prevention. The material of the tab is preferably the same as that of the steel pipe 1, and the shape is either cylindrical with the same diameter as the steel pipe 1 as shown in the figure, or the end is made into a truncated cone with a smaller diameter. A rolling roll (preferably a shape that is easy to fit into).By providing this tab 7, if flux leaks from the gas vent hole 5, the flux will remain inside the tab and will not dissipate. 7
There is no need to install this tab, especially if there is no leakage of Lux or the amount of leakage is very small and does not cause any problems.
, 6 is a welding part that connects the tab part and the steel pipe.

FIG. 3(a) is a sectional view showing another example of a flux-filled steel pipe, and FIG. 3(b) is a BB@ sectional view of FIG. 3(a). In this example, the gas venting part 3' is a steel pipe 1 with a stopper 8 having a plurality of (four in the illustrated example) gas venting holes 5'.
It is formed by welding and stranding. The material of the stopper 8 is preferably the same as that of the steel pipe 1. 4' is a gas venting seal, and 7' is a tab for preventing dissipation of leakage 111, which has a truncated conical shape with a smaller diameter toward the end t.

In the present invention, starting from a flux-filled steel pipe constructed as above, it is heated in a soaking furnace in advance, and the diameter of the steel pipe is reduced to a large width in a hot rolling process. 20mm
Use flux-filled steel pipes of approximately the same diameter. Next (after cutting off the gas vent part at both ends of this flux-filled steel pipe,
Surface treatment such as plating is performed (7. Jtsu ``Cut a flux-cored wire for welding with a certain wire diameter.'')

In the present invention, flux-filled steel pipes have a high temperature during the hot rolling process. In order to remove the moisture in the flux, it is inevitable that the moisture in the flux will be discharged to the outside.
It is said that the manufacturing process can be simplified without any need for further processing.

(Example) Fig. 1 (Carbon dioxide gas welding I based on the manufacturing method of the present invention described above using the flux-filled 'Af4' ft shown in FIG. 1)
II flux-cored wire was manufactured. Table 1 shows the manufacturing conditions.

Table 1 Note 1) D = outer diameter of steel pipe, t: pipe wall thickness Note 2) After dry mixing the flux raw materials, water glass and sulfur were added and wet-mixed, which was formed into a cylindrical shape and dried. In addition, d: pellet diameter, t = length of pellet. In the wire thus manufactured, the moisture in the filling flux was almost completely removed, and it was confirmed that there was no segregation of flux. Also, there was no copper on the surface of the wire. Since the plating is coated, it has good rust resistance.

When molten N was applied using this wire, both the four-filter wire feedability and liquid resistance were good, and the weld metal diffusion and 1
The amount of hydrogen and oxygen was low, and the mechanical properties were extremely good.

As described above, the present invention makes it possible to obtain a flux-cored wire for welding with good quality, and also to shorten the manufacturing time and simplify the manufacturing process. The value is extremely high.

[Brief explanation of the drawing]

Figure 1(a), Figure 2 and Figure 3(a) are respectively
A longitudinal cross-sectional view of a flux-filled steel pipe used for carrying out the present invention,
Fig. 1(b) is a cross-section Ffii diagram taken along line A-A in Fig. 1(a),
No. 31'9(b) is B-BH cross section 6 of No. 313(a). 1: Steel pipe, 2: Flux, 3, 3' slotted part,
4.4': seal, 5.5': gas vent hole, 6: bath contact part, 7.7': tab, 8: stopper.

Claims (1)

[Claims] A method for manufacturing a flux-cored wire for welding, which comprises filling a steel pipe with flux in the form of a pellet, hot rolling the steel pipe, and then cold drawing and rubbing the wire to a predetermined diameter.