JPS6340696A - Flux cored wire for welding - Google Patents

Abstract

PURPOSE:To prevent the projection of an unmelted flux and the generation of a welding defect by building-in the insertion hoop of a separate body to wrap the inner inclusion flux of a double type flux cored wire. CONSTITUTION:A separate insertion hoop 9 in a circular sectional shape is built-in at the inner side of a double flux cored wire and the inner side circular part is formed so as to surround an inner inclusion flux 5 by attaining to the hoop overlapped in two sheets without fail. As a result, the outer inclusion flux 4 and inner inclusion flux are completely separated. When the welding is performed by using this wire, the projection of the unmelted flux of the outer and inner inclusion fluxes becomes difficult to cause, a welding worker can weld extremely easily and a welding defect becomes difficult to cause.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an improved dual flux-cored welding wire.

[Conventional technology]

Various types of flux-cored wires for welding have been proposed so far, and the cross-sectional shapes of the wires are shown in No. 6.
There is something like the picture.

Figure 6 (a) shows a wire with no seams, and the filling flux 2 has excellent moisture absorption resistance, but there are restrictions on the length of the pipe into which the flux can be inserted, and flux filling is done in batches. In addition, it is necessary to pre-treat the flux before insertion to prevent the mixed flux from separating and segregating due to the vibrations applied to the pipe to make the flux filling in the pipe more uniform and increase its density. In order to draw wire to a finished diameter of 2 mmφ or less, an annealing process is required during the wire drawing, which reduces production costs, and the raw material that thermally decomposes at this annealing temperature is used as flux. However, there are also limitations to the welding methods to which the wire shown in FIG. 6(a) can be applied.

On the other hand, flux-cored wires other than (a) in Fig. 6 (b)
~(D is a band-shaped hoop l wrapped with flux 2.4.5 and formed, and is generally also called a crimping wire. In terms of manufacturing, these crimping wires are similar to the wire (a) above. It is advantageous because there is no 1.

The various types of crimp wires shown in (b) to (j) each have their own characteristics and are used depending on the situation, but according to a recent detailed study by the present inventors, the cross-sectional Shape (2-shaped flux-cored wire with built-in outer flux 4 and inner flux 5 like D)
Japanese Patent Publication No. 44-2336) has the best properties during welding and in welding total bending. In particular, it is recognized that flux-cored wires are advantageous for use in so-called unencapsulated arc welding, which allows welding in the atmosphere without the need for an external supply of arc encapsulating gas or solvent during welding. It has been reached.

The double type flux-cored wire having the cross section (j) in FIG. 6 uses a hoop having a thinner plate thickness than the wires shown in FIG. 6 (b), (C), (f), and (h). Finished wire diameter
It can be used for different purposes, but generally for wires with a diameter of 2 mm to 1.6 mm, the plate thickness is 0.15 mm to 0.25 m.
m is used.

Such double-type flux-cored wires have conventionally been manufactured by a process as shown in FIG. That is, first, as shown in FIG. 7(a), the hoop 1 is bent to form the outer flux filling body 21, which encloses the outer flux 4 and has an elongated rectangular cross section. In this case both edges 7.8 of hoop l
Fold the hoop L so that they overlap sufficiently. Next, as shown in FIG. 7(b), this outer flux filling body 21 is bent into a U-shape to form a U-shaped gutter-shaped filling body 22,
The embedded flux 5 is charged inside it, and then as shown in Fig. 7 (
As shown in C), the outer flux filling body 21 is formed into a circular shape to form a circular filling body 23. This wire having the shape shown in FIG. 7(C) is drawn to obtain a double type flux-cored wire of a predetermined thickness.

[Problem that the invention seeks to solve]

The problems of the flux-cored wire having the double cross-sectional shape will be explained with reference to FIG.

A double flux cored wire is such that the part of the hoop surrounding the included flux 5 has an overlap of the ends 7.8 of the hoop l. It is preferable to form this overlapping part as uniformly as possible around the entire circumference of the inner flux, but this is not always easy, and the inner flux 5 is often surrounded by a single part and a double part of the hoop. .

In particular, when the filling amount of the embedded flux 5 is large, the edge portion 7.8 of the hoop surrounding the embedded flux 5 has a larger cross-sectional area, so there is less overlap, and the edge portion 7.8 of the hoop surrounding the embedded flux 5 becomes smaller. A part with one sheet and a part with two overlapping sheets are formed.

As a result, the following problems arise.

(1) When welding wires, arcs tend to occur from steel hoops, and near the edge 7.8 above, two hoops overlap, but when welding a single hoop, the non-overlapping part of the hoops As shown in FIG. 5(b), an unmelted flux protrusion 30 of the inner and outer envelope flux is generated. Figure 5 (
b) shows the situation during welding of the AA cross section in FIG.

Therefore, there is a problem in that welding performance is impaired and the operator has to set the voltage to a high level, causing weld defects.

(2) Also, since there is little overlap between the two edge parts 7 and 8 of the hoop that surrounds the inner flux, the outer flux penetrates into the inner flux and the original characteristics of the double flux-cored wire are not utilized, resulting in welding. This results in a loss of workability.

An object of the present invention is to provide a double flux-cored wire that can solve the problems (1) and (2).

[Means for solving problems]

The present invention consists of a new technical means that improves the above-mentioned conventional double flux-cored spooling wire, and is characterized by incorporating a separate insertion hoop for enclosing the inner flux.

[Function] The present invention incorporates another insertion hoop 9 with a circular cross-section, so that the inner circular part surrounding the inner flux always has two overlapping hoops, and the outer flux and the inner flux It became possible to completely separate the two. As a result, when performing welding using the product wire, as shown in FIG. 5(a), unlike FIG. 5(b), the unmelted flux of the outer and inner flux protrudes. Welding workers can weld very easily, and welding defects are less likely to occur.

The wire of the present invention can be manufactured by the following manufacturing method. That is, as shown in FIG. 2(a), another hoop is inserted into the upper part of the outer flux filling body with a rectangular cross section, and the
It can be manufactured by forming into a U-shape as shown in FIG. 2(b), then forming in the same manner as before, and then performing circular tightening forming as shown in FIG. 2(c).

〔Example〕

A double flux-cored wire (Example) having the cross-sectional shape shown in FIG. 1 was manufactured. For comparison, a double flux-cored wire (comparative example) having the conventional cross-sectional shape shown in FIG. 3 was manufactured. Its manufacturing specifications are as follows.

Example Comparative example Hoop thickness 0.20 mm 0.20
m Hoop width 22mm 22mm insertion hoop Q, zQmm Unfinished - Rewire wire diameter 2.0 mm mφ 2. Om
mφ flux inclusion ↓ is outer flux 16% 16% inner flux 14% 14% cross-sectional shape Figure 1
After multi-layer welding of the example and comparative example shown in FIG. 1-1 to a steel plate having the groove shape shown in FIG.
Table 1 shows the results of transmission photographs taken using the X-ray transmission test method according to the following.

The welding conditions are as follows.

Welding current: 250Amp Arc voltage: 19-26vo it welding speed
: 25 cm/min wire extension:
25mm Polarity: DC-wire plus (base metal minus) As is clear from Table 1, in the comparative example, the arc voltage was 24
-25 volts is good, whereas in the examples it is good over a wide range of 20-25 volts.

In addition, the state of the wire tip during welding is shown in Figure 5 (
In the comparative example (b), when the arc voltage is below the lower limit, the protruding parts where the flux is not melted come into contact with the base metal, which tends to cause defects, and the arc voltage is lower than the lower limit. Above the upper limit of , nitrogen in the atmosphere becomes excessively entrained, resulting in frequent blowholes and, in severe cases, bits.

Unreleased IJI is applied to the production of wire for self-shielded arc welding, but it goes without saying that it is used for encapsulated welding in which the welded part is encapsulated in an inert gas such as carbon dioxide or argon gas, or in the welded part with a solvent. Needless to say, the same effect can be exerted on flux-cored wire for automatic submerged arc welding.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a molded body according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing the manufacturing process of a wire according to the present invention, and FIG. 3 is a conventional two-set flux-cored wire structure. Nili cross section,
Figure 4 is the cross-sectional shape of the groove, Figure 5 is a cross-sectional view of the tip of the wire during welding, Figure 6 is a cross-sectional view of a conventional flux-cored wire, and Figure 7 is the manufacturing process of a conventional double type flux-cored wire. FIG. l... Hoop 2.4.5... Flux 6... Seam portion 7.8... Hoop edge portion 9... Insertion hoop 21... Outer flux filling body 22... U-shape Gutter-like filling body 23... circular filling body

Claims (1)

[Scope of Claims] 1. A flux-cored wire for welding, which is a double-type flux-cored crimp wire, characterized in that a separate insertion hoop for enclosing the inner flux is incorporated.