JP2898116B2 - Manufacturing method of flux cored wire for welding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a flux-cored wire for welding, and more particularly to a method for manufacturing a flux-cored wire using a steel pipe, in which the flux filling ratio (the ratio of the flux weight to the wire weight) is small and the quality is low. And a method for producing an excellent flux cored wire for welding.

[0002]

2. Description of the Related Art A flux-cored wire for welding is composed of various flux components (slag agent, deoxidizer, iron powder, iron powder) in a metal sheath.
And is rapidly developing as a material for gas shielded arc welding mainly in Japan. This is because, together with the high welding property of the flux-cored wire, the effect of the filled flux, arc stability, reduction of spatter generation, good slag peeling property,
This is because welding workability such as good bead shape and appearance is excellent.

The conventional method of manufacturing a flux-cored wire can be roughly classified into two types, and the cross-sectional structure of the wire is different as shown in FIGS. 1 (a) and 1 (b). In FIG. 1, reference numeral 1 denotes a metal shell, 2 denotes a flux, and 3 denotes a joint of the metal shell. (A): forming a relatively small-sized strip 1 into a groove, supplying a flux 2 to the groove, abutting both edges of the groove by molding, and then reducing the diameter to a predetermined size to manufacture. And has a seam 3 at the wire cross section. On the other hand, (b) is manufactured by filling the steel pipe 1 prepared in advance with the flux 2 and then reducing the diameter, and there is no seam joint of the metal sheath in the wire cross section. As the influence on the welding performance due to such a difference in the cross-sectional structure of the wire, the wire harness is smaller in the case where there is no joint 3 of the metal outer skin (b), so that the robot welding, shipbuilding, steel frame, bridge, etc. When applied to high-speed fillet welding, which has a high usage ratio in fields such as, the deflection of the target position of the wire tip during welding is small,
A stable bead can be formed. Further, the sectional structure is (b)
Can be subjected to intermediate annealing for the purpose of dehydrogenation treatment to remove the moisture of the flux raw material after the filling of the flux, so that the amount of hydrogen in the wire total can be reduced and the crack resistance is also improved. .

However, when a wire having a cross-sectional structure (b) is manufactured by, for example, the method disclosed in Japanese Patent Publication No. Sho 60-43239, a flux is sequentially supplied from a steel end by applying vibration. The problem is that the filling time becomes longer and the productivity is inferior due to the method of filling by flux, and the variation of the flux filling property that the fluctuation of the flux filling rate in the longitudinal direction of the wire becomes considerably large depending on the type of flux and deteriorates the quality. There's a problem. In order to solve these problems, the same publication discloses a method for giving vibration, a method for the type of vibration, and connecting pipes for air release to both ends of a steel pipe.
It has been shown that the above can be improved. On the other hand, as an improvement from the flux to be filled, conventionally, the flux is granulated to an appropriate particle size with water glass or the like, and then filled, or the flux raw material is sieved and only the coarse particle portion is used. Are known to be advantageous.

[0005]

However, in an actual operation in which a large amount is continuously produced, the presence of a certain amount of fine powder is inevitable even in the case of a granulated flux. Although the use of a non-granulated flux in which various raw materials are mixed and mixed without being granulated is advantageous in terms of cost due to the omission of the granulation step, it is extremely difficult to fill due to poor flux flowability. Therefore, since it is necessary to limit the length of the steel pipe to be used to be very short, it has not been practically used until now. Further, in order to secure the granulating property or fluidity of both the granulated flux and the non-granulated flux, restrictions on the types of usable flux raw materials are not preferable from the viewpoint of improving welding performance.

Accordingly, the present invention relates to a flux for manufacturing a flux-cored wire having a cross-sectional structure having no seams of a metal outer skin as shown in FIG. To provide a flux cored wire for welding that aims to improve productivity by shortening the flux filling time, which is a problem of the filling process, and has a small variation in the flux filling rate in the wire longitudinal direction and is excellent in quality as a welding wire. The purpose is to:

[0007]

According to the present invention, a steel pipe wound body is fixedly mounted on a vibrating table, and a flux is supplied and filled in the steel pipe by applying vibration, and then the diameter is reduced to a predetermined wire diameter. In the method for producing a flux-cored wire for welding,
The flux is filled in the steel pipe while being heated to the above temperature. In a preferred embodiment of the present invention, the filling port side end of the steel pipe winding or the entire steel pipe winding is also heated.

[0008]

[Function] By heating the flux, the moisture of the flux escapes, the fluidity of the flux increases, the flux flows into the steel pipe smoothly, the flux filling speed increases, and the filling rate in the steel pipe varies. Is reduced. This effect can be obtained by heating the flux to 50 ° C. or higher. It should be particularly noted that non-granulated flux, which could hardly be filled in the past, can now be filled, and practical production of a non-granulated flux requiring a small number of manufacturing steps has become possible.

Hereinafter, the present invention will be described specifically. FIG.
FIG. 1 shows an outline of one flux filling apparatus for carrying out the present invention. In FIG. 2, a wound body 6 of a steel pipe 5 wound around a bobbin 4 is fixedly mounted on a vibrating table 7, and an end 8 of the steel pipe 5 on the filling port side is bent upward to reduce heat resistance. It is connected to a hopper 10 containing the flux 2 via a transparent flexible tube 9. A pair of vibration motors 11, 11 ′ is attached to the vibration table 7, and the winding body 6 of the steel pipe 5 is mounted on the vibration table 7.
The spiral vibration about the winding center axis A is given, and by this vibration, the flux is conveyed inside the steel pipe 5, and the steel pipe 5 reaches the end portion 12 of the steel pipe 5.
Is filled over the entire length. In order to facilitate the replacement of the air with the flux in the steel pipe 5 and to smoothly fill the flux, a pipe 1 for air release is provided at both ends of the steel pipe 5.
3, 13 'are connected.

Further, since the present invention allows the flux to be filled smoothly and at a relatively high speed, the heating heater 1 is used.
4, 14 ', 14 "are mounted around the hopper 10, the charging port side end 8 of the steel pipe 5, and the steel pipe winding 6, respectively.

First, the present inventors have proposed an outer diameter made of mild steel.
Using a steel pipe 5 having a diameter of 6 mm, a wall thickness of 2.2 mm and a length of about 200 m, the effect of the type of flux on the filling property was investigated in detail. As a result, when the proportion of fine powder having a particle size of 150 μm or less exceeds 20% (% by weight) in the granulated flux, the required filling time sharply increases, and in the non-granulated flux in which the raw material is not sieved, almost no filling can be performed. It was impossible. In the case of a flux having a large amount of moisture absorption, the filling property was significantly deteriorated. Next, the steel pipe after flux filling was cut out into fixed lengths, and the change in the flux filling rate in the length direction of the steel pipe was investigated. I understood. Therefore, for the purpose of investigating the cause, the present inventors used a transparent tube wound body having substantially the same size as the cross section of the steel tube, and observed the state of flux flowing in the tube. As a result, it was recognized that when trying to fill a flux with poor filling properties, the clogging of the pipe due to the flux occurred. In particular, the end (14 ') on the filling port side bent upward for connection to the hopper 10.
Flux) fills in order from the end of the tube, or, rarely, from the end (12) of the tube, but this blockage is likely to occur near the filling front.

FIG. 3 schematically shows the closing of the steel pipe 1 by the flux. FIG. 3A shows a blockage 15 of the end (14 ') on the filling port side due to the flux. In this case, it is impossible to carry the flux smoothly toward the end of the steel pipe. FIG. 4B shows a steel pipe 1.
5 shows a case where a blockage 15 due to the flux occurs near the front where the flux fills. In this case, since the filling is completed while leaving the portion 16 where the amount of flux filling is extremely small, the variation of the flux filling rate in the length direction of the steel pipe 1 becomes large, sometimes leading to the generation of a portion where the flux is not filled. . The closed state due to the flux occurs instantaneously even in the case of the flux whose filling property is improved by the present invention. However, the clogging is not strong as in the case of the conventional granulated flux containing a large amount of fine powder or non-granulated flux, and the flux is immediately collapsed by the applied vibration to resume the flow of the flux. If the frequency of occurrence of the blockage is high, the filling time becomes longer.

As is apparent from the above investigation results, in order to smoothly fill the flux 2 containing a large amount of fine powder into the steel pipe 1 by the vibration filling method, a long-term blockage due to the flux inside the pipe is required. As a result of various investigations from the viewpoint that it is not caused, or that measures are required to quickly collapse even if blockage occurs, the heated and hot state of the flux should be sequentially supplied and filled into the inner part of the steel pipe. Was found to be extremely effective. That is, the cause of the blockage that is tightly tightened in the steel pipe and hardly collapses is due to powder characteristics such as cohesiveness and hygroscopicity of the fine powder, but for example, a mixture of fine powder such as non-granulated flux. However, by heating to a hot state, the bonding force between the particles is weakened, and the cohesiveness can be extremely reduced. This tendency is a phenomenon that is seen as a remarkable effect as the powder becomes finer, and effectively works to prevent the generation of blockage due to the in-pipe flux that inhibits the above-mentioned filling property and to promote the collapse of the retained flux. On the other hand, moisture absorption during filling, which causes blockage, particularly from the atmosphere, which is a problem in a humid season, is extremely small when the flux is heated to an atmospheric temperature or higher. Moisture absorption is avoided and seasonal fluctuations in moisture absorption are reduced. That is, the variation of the flux filling efficiency due to the season is reduced. Further, filling the steel pipe with the hot flux is based on the fact that the flow of air (air-back) which is replaced by the flux and is mainly sent toward the filling port side is heated with the progress of the filling of the flux, so-called fluffy. Since the flux in the closed state is more suitable and smoother, this works in synergy with the above-described blocking prevention effect and also effectively works to shorten the filling time.

In the present invention, the heating of the flux may be performed in a drying furnace such as a stationary furnace before filling, or may be performed while the flux is being stored in the flux hopper 10. The point is to fill the steel pipe with the heated and hot flux, which can prevent the clogging occurring at the steel pipe filling port side end 8 which is particularly problematic. In a preferred embodiment, further, in order to thoroughly prevent the clogging at the steel pipe filling port side end 8 where the clogging is likely to occur, heating of the steel pipe filling port side end 8 is also used in combination,
In addition, to ensure thorough prevention of clogging at the filling front,
The heating of the entire winding body 6 of the steel pipe 5 is also used. According to this, even when a very long steel pipe is used, the high flowability of the flux in the hot state is maintained up to the end of the steel pipe,
The effect of the present invention is further enhanced. It is within the scope of the present invention to heat the steel pipe 5 without directly heating the flux, and to fill the flux while heating it to a predetermined temperature or higher through the steel pipe wall.

Next, the heating temperature of the flux must be 50 ° C. or higher. FIG. 4 shows the relationship between the heating temperature of the flux and the generation state of the closed state in the pipe. The test method was as follows: using a filling device shown in FIG. 2 on a wound body of a heat-resistant transparent tube (outside diameter 12 mmφ, wall thickness 2 mm, length about 50 m),
The granulated flux and the non-granulated flux having the particle size distribution and the flux material mixing ratio shown in Tables 1 and 2 were filled, and the state of clogging caused by the flux in the pipe one hour after the start of filling was observed. As is clear from FIG. 4, the heating temperature of the flux varies depending on the proportion of the fine powder. However, even when the flux is granulated and contains 20% or more of fine powder of 150 μm or less, if the temperature is 50 ° C. or more, clogging occurs in the pipe. Instead, a predetermined amount of flux can be filled. As the upper limit of the heating temperature of the flux, if the temperature is too high, the burning and decomposition of the flux components, oxidation of deoxidizers, alloying agents, iron powder, etc. will occur, impairing the welding performance, and increase in heating cost and work In terms of safety, the temperature should be kept below 400 ° C. Further, when heating the wound body 6 of the steel pipe 5 at the same time, the heating temperature of the wound body 6 must be 50 ° C. or more so that the temperature of the flux does not become 50 ° C. or less. The upper limit is preferably 400 ° C. or lower for the same reason as described above.

Although the present invention has greatly improved the filling property by filling the flux in a hot state as described above, the effect is that the amount of attached moisture is 1.0% or less (% by weight, heating temperature 105%). It is larger when a flux (measured by the gravimetric method at ° C.) is used. Therefore, the amount of water initially attached before entering the filling port of the steel pipe 5 is 1.0
% Of the flux is preferably controlled so as to be less than or equal to%. Hereinafter, the effects of the present invention will be described in more detail with reference to examples.

[0017]

EXAMPLE (1) About 500 kg of a mild steel pipe having an outer diameter of 12.0 mmφ and a thickness of 2.0 mm was wound around a bobbin having an inner diameter of 580 mm in a line, and the apparatus shown in FIG. The granulated flux F1 having a mixing ratio of the flux raw materials was filled. The vibration conditions given were as follows: the vibration angle of the vibrating table 7 (the part on which the winding body was placed) was 20 to 45 °, the frequency was 1500 rpm, and the vertical component of the vibration width was 2.5 mm. Table 3 collectively shows the results of the filling and the results of the welding workability test by the present invention example and the conventional method. Test No. Nos. 1 and 2 are examples of the present invention. The filling time is greatly reduced as compared with Comparative Example 3 and the variation in the filling rate is further reduced.
It can be seen that the value (value of V) is also small. The wires subjected to the welding workability test shown in Table 3 were:
After filling with flux, reduce the diameter (650mm x 4h at 3.2mmφ)
(intermediate annealing for holding r) was performed), and the diameter was 1.2 mmφ.

Example (2) Outer diameter 11.0mmφ, wall thickness 2.2mm
About 300 kg of a mild steel pipe were wound around a bobbin having an inner diameter of 580 mm, and filled with a non-granulated flux F2 having a particle size distribution and a mixing ratio of a flux raw material shown in Tables 1 and 2 by an apparatus shown in FIG. The given vibration conditions are the same as in the above-described embodiment (1). Table 4 shows the state of flux filling and the results of filling, and the results of a welding workability test of a wire that was reduced in diameter after filling (intermediate annealing at 650 ° C. for 4 hours at 3.2 mmφ) and finished to 1.4 mmφ. In Table 4, Test No. 4,
No. Reference numeral 5 indicates an example of the present invention, in which a non-granulated flux can be filled, the variation in the filling rate is small, and there is no problem in welding workability. On the other hand, N
o. 6 and no. No. 7 could not be filled because the flux was heated to a hot state and was not filled. In particular, no. Regarding No. 6, although the initial amount of water adhering to the flux has been reduced by drying before filling, no improvement in the filling property is recognized because the filling was carried out after cooling as conventionally performed.

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

[Table 3]

[0022]

[Table 4]

The technique of the present invention, in which the flux is heated and filled into a steel pipe in a hot state, can be quickly and frequently filled with the flux into a pipe made of stainless steel or various metal alloys. It can also be applied to the production of flux cored wires for welding. In addition, we observed the production of flux cored wire for welding performed using a strip steel, and confirmed that the present invention brings about an effect also in preventing the variation of the flux filling rate which is a problem especially in the case of non-granulated flux. I have.

[0024]

As described above, according to the present invention, a flux which becomes a problem when manufacturing a flux-cored wire for welding, which is characterized by having no seam in the wire cross section and excellent in various welding performances, by the vibration filling method. The productivity of the filling step is improved, and the filling of a non-granulated flux containing a large amount of fine powder, which has been extremely difficult in the past, becomes practically possible, and the variation in the filling rate is extremely small. Therefore, a high quality flux cored wire for welding can be provided with high productivity.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a flux-cored wire;
FIG. 1 (a) shows a molded steel strip, and FIG.
Indicates a reduced steel pipe.

FIG. 2 is a side view schematically showing a flux filling device embodying the present invention, and a part thereof is shown in section.

FIG. 3 is an enlarged longitudinal sectional view showing a state of flux flowing in a steel pipe at the time of conventional flux filling, in which (a) of FIG. 3 shows a filling port side end of the steel pipe, and (b) of FIG. Show body part.

FIG. 4 is a graph showing the relationship between the heating temperature of the flux and the generation of blockage in the steel pipe, and also shows the flux heating position and the temperature measurement position. 1: Metal skin 2: Flux 3:
Seam of metal skin 4: Bobbin 5: Steel pipe 6:
Wound body of steel pipe 7: Shaking table 8: Filling port side end of steel pipe 9:
Flexible tube 10: Hopper 11,1
1 ': Vibration motor 12: End of steel pipe 13,1
3 ': Air vent pipe 14, 14', 14 ": Heating heater 15: Blockage generated in steel pipe 16: Insufficient amount of flux filling in steel pipe

Continuation of the front page (56) References JP-A-58-154496 (JP, A) JP-A-59-61597 (JP, A) JP-A-63-140799 (JP, A) (58) Fields investigated (Int) .Cl. ⁶ , DB name) B21D 35/40

Claims (2)

(57) [Claims] 1. A method for manufacturing a flux-cored wire for welding, which comprises placing a rolled body of a steel pipe fixedly on a vibrating table, applying vibration to supply and fill a flux into the steel pipe, and reducing the diameter to a predetermined wire diameter. 3. The method for producing a flux-cored wire for welding according to claim 1, wherein the flux heated to a temperature of 50 ° C. or higher is filled. 2. The method for producing a flux cored wire for welding according to claim 1, wherein the filling end of the steel pipe winding body or the entire steel pipe winding body is heated to a temperature of 50 ° C. or higher. .