JPS6018295A - Production of powder-containing welding wire - Google Patents

Abstract

PURPOSE:To produce a powder-contg. welding wire having good quality in a short time by forming steel strip into a tubular shape by electric resistance welding and feeding filling powder pneumatically into said tube by using a hollow impedor. CONSTITUTION:A steel strip 1 supplied from an un-coiler 5 is formed into a U shape by forming rolls 2, 2', 3, 3' and after the edges of the strip 1 are heated by the current of a work coil 10, the strip is pressed and joined to a tubular shape by squeeze rolls 4, 4'. A hollow impeder 6 is inserted into the blank pipe formed to the tubular shape in front of the work coil 10 and the powder 8 in a hopper 7 is filled by the compressed air from a compressor 9 via the impeder 6 into the blank pipe. The weld zone of the blank pipe is preferably cooled with water or air. The impeder 6 is made into a double construction with a ferromagnetic material 11 and an insulator 12 to obviate the presence of a magnetic field on the inside surface of the impeder 6 so that the conveyance of the powder 8 by the gas is made easy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a powder-cored welding wire in which the edges of steel strips are joined.

The general method for manufacturing powder-filled welding wire is to form a steel band into a U-shape, fill it with powder, roll form it into a predetermined cross-sectional shape, and then wire-draw it. In this method, since the edges of the steel strip are not joined, the edges of the steel strip tend to open, and moisture or lubricants used during manufacturing may penetrate into the powder through the openings.1-1 In addition to degrading the powder, it also has poor rust resistance because it cannot be plated or treated.

On the other hand, there is a method of filling a steel pipe with powder to solve the drawbacks of the above manufacturing method, but in this manufacturing method, the powder is transported and filled into a long and thin steel pipe using vibration, so
The filling time becomes very long and the powder filling equipment becomes complicated and large-scale.

Furthermore, a method is known in which the edges of the steel strip are welded after forming the steel strip into a fU shape and filling it with powder. In this manufacturing method, however, the powder is filled in the internal cross section during pipe manufacturing. For filling, the powder is swirled around it by the magnetic field present;
Adheres to the edges of the steel strip. As a result, defects such as inclusions or blowholes occur in the welded part, and the quality of the welded part deteriorates, making it difficult to obtain a predetermined diameter by pressing after welding.

In addition, as a means to solve the above problem, a method has been disclosed in Japanese Patent Publication in which the powder is filled to cover 70 to 85% of the internal cross section during pipe manufacturing, and the powder is filled inside the pipe by wire drawing. In this manufacturing method, which is known from Japanese Patent No. 54-109040, since the deformability of the steel strip and the powder differ, the powder may not be present inside the tube after wire drawing.

The present invention eliminates the drawbacks of the conventional means and makes it possible to manufacture a powder-filled welding wire.The edges of the steel strip can be joined, the powder filling device is simple and small-scale, and the production time is reduced. The purpose of the present invention is to provide a method for manufacturing a powder-filled welding wire that can be shortened and productivity can be increased.

That is, the present invention is characterized in that a steel strip is formed into an open groove, the edges of the groove are fully electrical resistance welded to produce a tube, and the filling powder is pneumatically fed into the tube using a hollow invider. This is a method of manufacturing a powder-filled welding wire.

The present invention will be explained in detail below based on the drawings.

FIG. 1 is an explanatory diagram of the manufacturing method according to the present invention, FIG. 2 is a schematic diagram showing the process of forming a steel strip and electric resistance welding, and FIG. An example using high frequency induction welding is shown as an example of one embodiment of resistance welding.

As seen in these figures, the steel strip 1 is fed from the uncoiler 5 and rolled by forming rolls 2.2' and 3.3'.
The edges of the steel strip 1 are formed into a shape and a heating current is induced by the work coil 1o installed just before the squeeze rolls 4, 4', and then the squeeze rolls 4, 4' are pressed. Joined. At this time, a part of the current induced on the outer surface of the U-shaped steel strip 1 flows back through the inner surface and becomes a reactive current. For this reason, in conventional means, a solid rod-shaped impeder made of a ferromagnetic material such as a ferrite core, which is a magnetic oxide, is usually used to reduce reactive current by increasing the impedance on the inner surface side. used by inserting it inside.

In the present invention, a hollow impeder 6 is used, and the powder 8 is pneumatically fed through the hollow part of the impeder into the raw steel which is formed into a tubular shape by welding.

In this case, the gas used may be any gas as long as it does not easily react with the powder and steel strip, and it is ideal to use an inert gas such as Ar, He, or N2, but it is not practical. It is sufficient to use air. That is, the powder 8 placed in the hopper 7 is transferred to the squeeze roll 4 from between the work coils 100 installed just before the forming rolls 3, 3' and the squeeze rolls 4, 4' using compressed air from the compressor 9. , 4', and is filled into the tube-made steel strip 1 through the hollow impeder 6 inserted into the tube-made steel strip 1.

If oxidation of the powder 8 due to the heat of the welding part becomes a problem,
It is preferable that the welded part be water or air cooled. In the case of water cooling, the cooling water also enters the inner surface of the U-shaped steel strip 1, so if it comes into contact with the filled powder 8, it may cause deterioration, but in the case of the present invention, the powder Since the cooling water is pushed out of the steel strip 1 by the wind pressure of the gas used to convey the powder 8, it does not reach the position of the filled powder 8.

The gas used to convey the powder 8 may be either cold air or hot air, and the powder 8 may be in the form of powder or granulated with a binder such as water glass. When the powder 8 passes through the hollow impeder 6, if the impeder 6 is made only of ferromagnetic material, a magnetic field exists on the inner surface of the impeder 6, so the powder 8 swirls around it. At the same time, it may adhere to the inner surface of the impeder 6, making it difficult to transport the powder 8 by air.

In order to solve the above drawbacks, as shown in FIG. 4, which is a schematic cross-sectional view of the impeder 6, the impeder 6 has a double structure of a ferromagnetic material 11 and an insulating material 12, so that the inner surface of the impeder 6 is Since no magnetic field exists, the powder 8 can be easily transported by gas.

By using such means, the powder 8 can be filled at the same time as the tube is manufactured, and the production time can be significantly shortened compared to the manufacturing method in which the powder 8 is conveyed and filled into a long and thin steel pipe using vibration. At the same time, the powder filling device becomes simple and small-scale. In addition, if the steel strip 1 made into a tube by the SUF-F-F-ROLL 4, 4' and filled with the powder 8 is to be made into a smaller diameter if necessary, a predetermined diameter can be obtained by wire drawing. Before the wire drawing process is completed, sizing may be performed to achieve 9 dimensional accuracy, and the outer convex portion of the welded portion does not need to be cut, but it is preferable that it be cut.

The effects of the present invention will be illustrated in more detail with reference to Examples below.

Powder-filled welding wires were manufactured based on the manufacturing conditions shown in Table 1. Wire wires 1 to 6 manufactured by the manufacturing method of the present invention can be filled with powder in a short time, can be processed up to φ1.6 without breaking wires and openings in welded parts, and have improved wire feeding and welding workability. Both are extremely good, and
Since moisture did not enter the filled powder, the amount of diffusible hydrogen in the weld metal could be significantly reduced, and the mechanical properties of the weld metal were good.

Further, A7 to A8 in Table 1 are comparative examples with the conventional method. flat 7
is a manufacturing method of powder-filled welding wire by roll forming in which the edges of the steel strip are not joined, and since plating cannot be performed, the wire surface rusts, poor wire feedability, and moisture and lubrication occur from the edge of the steel strip. The amount of diffusible hydrogen in the weld metal increased due to the intrusion of the agent. A8 is a method for manufacturing a powder input welding wire in which a steel pipe is filled with powder, and the powder filling time is extremely long.

As described above, according to the present invention, it is possible to obtain a powder-cored welding wire of good quality, and it is possible to shorten the manufacturing time, so it is clear that the present invention has great industrial value.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the manufacturing method of the present invention, Fig. 2 is a schematic diagram showing the forming and electric resistance welding process of the steel strip, Fig. 3 is a schematic diagram showing the plane of the powder-filled part, and Fig. 4 The figure is a schematic cross-sectional view of the invider.

Claims (1)

[Claims] 1. A steel strip is formed into an open groove, the edges of the groove are electrically resistance welded to produce a tube, and a hollow invider is used to pneumatically feed the filling powder into the tube. A method for manufacturing a powder-filled welding wire, characterized by: 2. The method for manufacturing a powder-filled welding wire according to claim 1, wherein the hollow impeder has a double structure of a ferromagnetic material and an insulating material.