JPH08300186A - Backing strip for one-side welding - Google Patents

Abstract

PURPOSE: To provide a backing strip for one-side welding which extremely little produces smells and smoke during welding, makes it possible to obtain good penetration beads, is excellent in productivity and has a simple structure. CONSTITUTION: A flux having a compsn. contg. one kind selected from a group consisting of SiO2 , MgO, ZrO2 and Al2 O3 at >=50% of the total weight of the solid flux or contg. >=2 kinds selected from this group at >=70% of the total weight of the solid flux is used. The backing strip is formed by molding this flux by a powdery or granular binder of an inorg. system consisting of particles of a particle diameter of <105μm at >=70% of the total weight of the binder and particles of a particle diameter of >=210μm at <10%. Glass fibers in the form of cloth or mat having a thickness of 1.0 to 3.0mm may be arranged on the upper layer of this backing strip for one-side welding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-sided welding technique, and particularly to reduce odor and smoke generated from a backing material during welding,
The present invention relates to a backing material for simple one-sided welding, which significantly improves the welding work environment.

[0002]

2. Description of the Related Art The one-sided welding method is a highly efficient welding method which can secure 100% penetration by welding from only one side without inverting the steel sheet. Therefore, single-sided welding is applied to welding of many structures such as shipbuilding and bridges. In particular,
The one-sided welding method using a simple backing material enables one-sided welding of welded joints in the field where the backing device cannot be brought in.
Contributes to the reduction of welding man-hours.

However, the solid flux generally used in the production of conventional simple backing materials uses an organic binder as a binder for the flux particles required for forming the flux, and the welding is performed. When the binder is exposed to high temperatures, it decomposes and decomposes, producing a strong odor and a large amount of smoke. In particular, when welding is performed in a narrow space, there is a problem that the working environment of welding is deteriorated.

Therefore, in order to improve the problems of the prior art, for example, a backing material has been developed in which an inorganic binder such as water glass is used to knead a flux, and the flux is kneaded, molded and dried. ing.

[0005]

However, the backing material in which the flux is kneaded using the inorganic binder such as water glass has complicated wet-kneading, molding and drying operations, which is a backing material. However, there is a problem in that the production cost becomes extremely high as a result.

The present invention has been made in view of the above problems, in which the generation of odor and smoke during welding is extremely small,
An object of the present invention is to provide a backing material for single-sided welding, which can obtain a good back bead and has excellent productivity and a simple structure.

[0007]

The backing material for single-sided welding according to the present invention comprises one selected from the group consisting of SiO ₂ , MgO, ZrO ₂ and Al ₂ O _{3 in} an amount of 5% of the total solid flux.
A flux having a composition containing 0% or more, or two or more kinds selected from the above group in a total amount of 70% or more of the total weight of the solid flux is used. 70% or more, particle size 210μ
It is characterized in that the particles of m or more are formed by less than 10% of inorganic powder or granular binder.

The thickness of the upper layer of the backing material is 1.0 to 3.
You may arrange 0 mm cloth-like or matte-like glass fiber.

[0009]

The present inventors have obtained the following findings as a result of repeating various experimental studies in order to solve the above-mentioned problems of the prior art. Solid flux component As a flux component, in order to directly receive high temperature arc heat and secure a stable back bead, it is important that it is a high melting point raw material and that it does not adversely affect the weld metal. Is SiO ₂ , MgO, ZrO ₂ or Al
It is necessary that ₂ O ₃ is the main component.

Therefore, the composition of the flux is Si
One type selected from the group consisting of O ₂ , MgO, ZrO ₂ and Al ₂ O _{3 is} contained in an amount of 50% or more based on the total weight of the solid flux, or two or more types selected from the group are contained in the total amount of the solid flux. It is necessary to contain 70% or more of the weight. If any of the above four components is less than 50% by weight, no matter how much the components other than the above four components are adjusted, the melting of the solid flux becomes unstable, and a sound and stable back bead is obtained. I can't. Also, 50% by weight for only one type
Even without the above, if the sum of two or more of the above four components is 70% or more based on the total weight of the solid flux, one of the components has a fire resistance equivalent to that of the flux of 50% by weight or more, A good back bead is obtained. But this is 70
If it is less than%, a sufficient refractory degree cannot be obtained even if other components are adjusted, and the melting of the solid flux becomes unstable and a stable back bead cannot be obtained.

[0011] As binding agent between binders flux particles, it is impossible to prevent malodor and smoke generated in the target is one of the welding of the present invention as described above in the organic binder. Further, the greatest object of the present invention is to improve productivity, which is a drawback of conventional inorganic binders. This requires the use of powder and / or granular binders. For example, as a conventionally used inorganic binder, there is water glass as a typical one, but the work of kneading, molding and drying after quantitatively adding this to the flux is complicated and the productivity is low. There is a problem in terms. However, the powdery or granular binder is easily mixed uniformly with the flux, and the flux mixed with the binder is also easily formed into a certain shape and size. As the inorganic binder of powder or granules, such as low-melting glass and sodium silicate, those having the property of binding between flux particles by softening or solidifying by heating at a constant temperature. is there. The type is not particularly limited as long as it has such a property. However, a binder having a particle size of less than 105 μm is less than 70%, or a binder having a particle size of 210 μm or more is 10% or more, the flux cannot be uniformly mixed, and the binding force between flux particles is weak. As a result, moldability, fragility of the solidified flux, and non-uniformity of composition occur, thus deteriorating the quality of the back bead. Therefore, it is necessary that the particle size of the binder is 70% or more for particles having a particle size of less than 105 μm and less than 10% for particles having a particle size of 210 μm or more.

Glass fiber The object of the present invention can be achieved by satisfying the above-mentioned constitutional requirements, but for the purpose of further expanding the application as a backing material, that is, the groove back side of the welded material to which the backing material is attached. Misunderstanding,
Alternatively, a mat-shaped glass fiber is arranged on the upper layer of the backing material so that it can be applied to a welded joint having some irregularities in the welding line direction. In the case of a welded joint having misalignments or irregularities, the adhesion between the backing material and the welded joint is impaired, and a sound back bead cannot be secured. In the case of considering the application to such a welded joint, it is preferable to dispose a cloth-like or mat-like glass fiber having a certain degree of flexibility and shrinkability on the upper layer of the solid flux. The glass fiber is not particularly limited, but the components are SiO ₂ : 50 to 75% by weight, Al ₂ O ₃ : 5
When the content of -25 wt% and CaO: 10-30 wt% is used, a back bead having gloss and no slag seizure can be obtained.

However, the thickness is an important factor for the stability of the back bead, and if the thickness is less than 1.0 mm, it is possible to secure the adhesion with the steel plate to the above-mentioned welded joint even if it is flexible. However, flash will occur on the back bead, and burn-through will occur. On the other hand, when the thickness exceeds 3 mm, the back bead height is high and unstable even if a solid flux having a high degree of fire resistance is used for the lower layer.

[0014]

EXAMPLES Next, examples of the present invention will be described in comparison with comparative examples.

Using the steel plates shown in Table 1, the wires shown in Table 2 and the table flux shown in Table 3, welding was performed under the groove shape and welding conditions shown in Table 4. Table 5 shows the solid flux composition, and Table 6 shows the glass fiber content, binder type and binder particle size. Table 7 shows the welding test results.

Example No. 1 satisfying the requirements of the present invention.
Example Nos. 1 to 9 and welded joints having a gap of 1.5 mm on the groove backside of the material to be welded were welded only with solid flux. No. 10 was slightly poor in the familiarity and shape of the back bead, but Example No. 10 in which glass fiber was placed in the upper layer and welded In Nos. 11 to 12, good welding results were obtained. On the other hand, Comparative Example No. In No. 13, a good back bead was not obtained because the component of the solid flux was improper. Comparative Example No. 14 is a comparative example No. Thirteen
The result was similar to. Comparative Example No. In No. 15, since many binder particles were coarse, the flux adherence was unstable and the appearance and shape of the back bead were not good. Comparative Example No. No. 16 was a bead with less foul odor and fumes during welding, but due to the liquid binder,
It took time to mix the flux powder uniformly, and molding took a long time. Comparative Example No. In No. 17, a good back bead was obtained, but a strong malodor and a large amount of fumes were generated during welding.

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

[Table 3] Others are _{CO 2, B 2 O 3,} Fe-Si, Fe-Mn or the like.

[0020]

[Table 4]

[0021]

[Table 5]

[0022]

[Table 6] * 1.5 mm misalignment on the back side of the grooved steel plate

[0023]

[Table 7] However, in Examples 10 to 12, there is a gap of 1.5 mm on the back side of the grooved steel plate.

[0024]

As described above, according to the present invention, the flux containing the predetermined solid flux is used, and the inorganic powder or the granular material having the predetermined particle size is used as the binder. It is possible to obtain a backing material for single-sided welding, which has very little generation of odor and smoke, and which can provide a good back bead and which is also excellent in productivity.

Claims (2)

[Claims] 1. SiO ₂ , MgO, ZrO ₂ and Al ₂ O ₃
1% selected from the group consisting of 50% or more of the total weight of solid flux, or 2 selected from the group
A flux having a composition containing 70% or more by weight of the total amount of the solid flux of the seeds or more is used.
70% by weight or more of the total weight of the binder and particles having a particle diameter of 21
A backing material for one-sided welding, characterized in that particles of 0 μm or more are formed by less than 10% of an inorganic powder or a granular binder. 2. The backing material for one-sided welding according to claim 1, wherein a glass fiber having a thickness of 1.0 to 3.0 mm, which is in the form of cloth or mat, is arranged on the upper layer thereof.