JPS6127199A - Backing material for one side welding - Google Patents

Abstract

PURPOSE:To obtain a back bead having no defect even in case of a stepped joint by constituting a backing material of two upper and lower layers, providing a projecting part on both sides or one side of the upper face of a fireproofing layer of the lower layer, and placing an inorganic fiber layer so as to cover the projecting part. CONSTITUTION:This backing material for one-side welding consists of the upper layer consisting of an inorganic fiber layer 2, and a solid fireproofing material layer formed by providing projecting parts 1a, 1b on both sides of the surface of a solid fireproofing material 3, or providing a projecting part 1c on one side of the upper face of the solid fireproofing material 3. The inorganic fiber layer 2 is placed on the solid fireproofing material layer so as to cover the projecting parts 1a, 1b or 1c. In this way, a recessed part formed by the upper face of the solid fireproofing material and the projecting part is packed suitably with an inorganic fiber, and an excellent back bead is formed thereby.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to the improvement of a backing material used for single-sided welding of steel. This invention relates to a backing material for single-sided welding that can obtain an excellent back bead without defects even in a joint with a step.

[Prior art]

Various high-efficiency welding methods have been studied in the construction of steel structures such as ships, offshore structures, and bridges, and single-sided welding is an extremely useful method because it allows a joint to be completed by simply welding steel from one side. It has been widely used as.

Single-sided welding involves pressing a backing material to form a back bead on the back side of the material to be welded and welding from the front side. There are two methods: one uses a device, and the other is a simple backing method, in which a lightweight and portable backing material is attached to the back side of the workpiece using adhesive tape, a magnetic clamp, or a special jig.

The present invention relates to a backing material used in a simple packing method.

As a backing material used in the simple backing method and consisting of two upper and lower layers: an inorganic fiber layer and a refractory material layer, a metal material with grooves 2 to 5 m deep is used as described in Japanese Patent Publication No. 45-5133. Or a bulk specific gravity of 0.05 on a refractory channel member.
~0.31-/art3 felt placed,-
Special Publication No. 49-21025, Jitoku No. 50-11768
Japanese Utility Model Publication No. 50-42841 discloses a backing material in which an inorganic fiber layer is placed on a refractory material layer, and a flat gap is provided between the two to form a back bead.

However, in the backing method of Japanese Patent Publication No. 45-5133, the inorganic fiber layer is fitted into the groove and does not cover the protrusion, and the bulk specific gravity of the inorganic fiber layer is small, making it difficult to adjust the shape of the back bead. It is difficult to form the necessary slag and it is difficult to obtain a smooth back bead with good conformability.

Also, Special Publication No. 49-21025, Actual Publication No. 1176-1973
In the backing material disclosed in No. 8, Utility Model Publication No. 50-42841, a satisfactory back bead can be obtained in a normal groove due to the presence of an inorganic fiber layer and voids. however,
The purpose of the gap in the backing material disclosed in the above publication is to stabilize the back bead, and the gap is narrow to match the width of the back bead. In this case, the adhesion of the backing material is insufficient and problems such as casting cracks and hot water leakage tend to occur.

[Problem that the invention seeks to solve]

The present invention stabilizes the height of the back bead in single-sided welding of steel, and also improves the adhesion of the backing material to the back surface of the welded material even in joints with steps. The purpose is to obtain an excellent back bead without problems such as burn-through.

[Means to solve the problem]

That is, the present invention advantageously solves the above-mentioned problems.The gist of the present invention is to provide a backing material consisting of two layers: an upper layer made of an inorganic fiber layer and a lower layer made of a solid refractory material layer. A single-sided welding backing characterized in that a protrusion is provided on both sides or one side of the upper surface of the lower solid refractory material layer, and an inorganic fiber layer is placed on the solid refractory material layer so as to cover the protrusion. This is the material in question.

Hereinafter, the backing material of the present invention will be explained in detail using the configuration examples shown in FIGS. 1(a) and 1(b).

That is, the upper layer consisting of the inorganic fiber layer 2 and the solid refractory material 3 are provided with protrusions 1a and lb on both sides of the surface as shown in FIG. is covered with a single-sided welding backing material made of a solid refractory layer provided on one side of the upper surface of the solid refractory material 3. In this case, the inorganic fiber layer is placed on the solid refractory material layer so as to cover the protrusion.

If the inorganic fiber layer has some flexibility, the first
As shown in the figure, the backing material is in contact with the solid refractory material near its center. In addition, in some cases, the inorganic fiber layer has little flexibility, and even if there is a gap between it and the solid refractory material layer, when it is attached to the material to be welded, it will not be able to withstand the pressure from a mounting jig such as a magnetic clamp. The inorganic fiber layer is pressed and voids disappear. That is, in the backing material of the present invention, the recess formed by the upper surface of the solid refractory material and the protrusion is suitably filled with inorganic fibers, thereby forming an excellent backing bead.

Although the protrusions are normally continuous in the longitudinal direction, there is no particular problem as long as they are discontinuous and the length of the intermittent parts is short.

By the way, the reason why the inorganic fiber layer is used as the upper layer is because the inorganic fibers are first melted by arc heat and become slag, which has a shaping effect on the ae bead and is effective in producing a smooth back bead shape with good conformability. Furthermore, inorganic fibers inherently have cushioning properties, and are easily compressed by slight pressure to provide good adhesion to the material to be welded, resulting in welding without defects such as casting seams or water leaks. Because it can be done.

Next, a solid refractory material is used as the lower layer because if only the inorganic fiber layer is used as a backing material, it lacks fire resistance and cannot support the molten pool and burns through. This is to control the temperature at a constant level. moreover,
In the present invention, protrusions are provided on both sides or one side of the upper surface of the refractory material. As shown in Fig. 2, this ensures a sufficiently good back pead even when the thicknesses of the welded materials 4-1 and 4-2 are different, or when a level difference occurs on the back side during the tacking process of the welded materials. It is meant to be obtained. Normally, such a step difference is controlled to a maximum of about 2.0 m, but if a normal backing material is used for such a step joint, problems such as casting cracks and hot water leakage will occur. That is, Fig. 3 (,) shows a situation in which a conventional backing material is set in a step joint as shown in Fig. 2. In the conventional backing material, the solid refractory material 3 does not have a protruding part. , unless the bottom of the groove protruding from the step hits the center of the backing material and great pressure is not applied to the backing material,
A gap 5 open to the outside is created between the materials to be welded 4-1, 4-2 and the inorganic fiber layer 2, from which the molten metal protrudes or flows out, resulting in a casting failure or a melt leakage accident.

On the other hand, the situation in which the backing material according to the present invention is set in a step joint is shown in Figs. 3(b) and 3(e).
Figure (b) shows a case in which there are protrusions on both sides, and figure (C) shows a case in which there are protrusions on one side. Note that the arrow 6 in the figure indicates the pressure force exerted by a mounting jig such as a magnetic clamp.

First, in Fig. 3(b), the protrusions 1a and lb on both sides create a recess on the solid refractory material, and the protrusion due to the step can bite into the backing material by that much. Figure 3 (
Good adhesion can be obtained without the formation of open gaps as in a). Also, there is a protrusion 1c on one side of the solid refractory material.
As shown in FIG. 3(c) when the backing material of the present invention is provided, excellent adhesion can be obtained by setting the side with the protrusion on the lower side of the step. According to the method, a good back bead can be obtained in the case of a step joint, but it goes without saying that a good back bead can also be obtained in a normal groove without a step. Figure 4(a)
, (b) shows how the backing material of the present invention is set in a groove with no steps. If the height of the protruding portion of the solid refractory material is appropriate, the inorganic fiber layer will be pressed against the back surface of the material to be welded by the pressing force 6 and will be in sufficient contact with the back surface of the material to be welded. In this case, due to the presence of the protrusion,
The major advantage is that the pressure on the constant plate is not applied to the inorganic fiber layer, and a suitable pressure can be maintained to form a stable back bead. By the way, as the above-mentioned inorganic fiber layer, 5in2. MgO, CaO, A12031
ZrO21N & 201 to 20 r Fe2O2r B2
Any layered inorganic fiber containing one or more metal oxides such as O3 can be used, but glass fiber is usually used.

Moreover, the composition of the solid refractory material is 5in2. TiO2, Ano2
The main component is one or more highly refractory oxides having a melting point of 1500° C. or higher, such as 03°ZrO2+ CaOr MgOr BaO. Also, this includes CaF2
Other welding material components with low melting points, such as p-NaF, can also be added as long as the fire resistance does not deteriorate. Usually, the above components are in the form of powder or granules, and in order to mold them into a solid material, they can be molded using a thermosetting resin such as phenol resin, or an inorganic adhesive such as water glass or silica sol, or they can be molded by high-temperature sintering. It may also be made into a ceramic molded product.

By the way, in the backing material of the present invention in which a solid refractory material having a protrusion as described above and an inorganic fiber layer are combined, the height of the protrusion and the apparent density of the inorganic fiber layer are extremely important.

In other words, if the height of the protrusion of the solid refractory material is low, it will not be effective in improving the adhesion in the step joint, and if it is too high, the back bead support effect of the solid refractory material will not be effective and the height of the back bead will be reduced. It cannot be held properly, and the adhesion of the inorganic fiber layer deteriorates due to the gaps on the refractory material created by the protrusions. On the other hand, when the apparent density of the inorganic fiber layer is small, the inorganic fiber layer's adhesion, silicone properties, and flexibility are sufficiently satisfactory, and its adhesion to the material to be welded is excellent. However, if the apparent density is too small, the volume decreases greatly during melting, the amount of slag produced is insufficient, and the bead shape becomes convex and excessively large. On the other hand, if the apparent density is too large, the inorganic fiber layer will lack adhesiveness and silicone properties, and will be difficult to melt, resulting in easy casting cracks and unstable bead shapes.

Note that the apparent density is determined by measuring the thickness, width, and length of the layered inorganic fiber according to JISR3420, and then measuring the weight of the inorganic fiber using the following formula.

Incidentally, the apparent density of the inorganic fibers can be changed by the molding method, the yarn density when weaving as a cloth, or the weaving method (plain weave, twill weave).

Table 1 shows the results of a study on the appropriate height of the protrusion using the backing material of the present invention shown in FIGS. 1(a) and 1(b). The solid refractory material in this case was formed by adding 2 parts of phenol resin to silica sand (the phenol resin was dissolved in ethyl alcohol, a predetermined amount was added to the silica sand, and the mixture was stirred) and then heated and molded.

The shape of the solid refractory material is a through hole as shown in Fig. 7(a) and (b), and h in the figure is the height of the protrusion, which is O~5, O
The width of the protruding part is 5+m+.

The width y of the solid refractory material is 50w1 and the thickness 2 is 8mm.

In addition, the main components of the inorganic fiber layer are 5IO265%, Na
0 consisting of zO15'/', ZrO217%, and others;
The one with a thickness of 35 mm is made by sewing together multiple pieces of lasteve.
The apparent density was 0.90-1.131-/am3. The number of glass stages is changed according to the height of the protrusion, and the thickness is about 1. Otan
I tried to make it bigger.

The above solid refractory material and inorganic fiber layer are used in the examples described below, and the normal groove shown in Fig. 6 (,) and Fig. 6 (b)
A study was conducted on a groove with a step (two-tone) as shown in the figure.

One-sided submerged arc welding was carried out using 50H'l' steel with plate thicknesses of 25 and 27 m, and using the welding conditions and welding materials shown in Tables 4 and 5 in Examples described later. The observation results of the appearance of the back bead are as shown in Table 1.If the height of the protruding part of the solid refractory material is less than 0.5cm or more than 4.5cm, it may cause leakage, cast cracking or Problems such as bead size and convex shape arise. Therefore, it is most preferable that the height of the protrusion is 1.0 to 4.0 mm.

Next, Table 2 shows the results of examining the influence of the apparent density of the inorganic fiber layer on the appearance of the back bead. The welding materials, welding conditions, and other details used in the experiment were the same as those in Table 1, but in this case, the height of the protrusion of the solid refractory material was constant (1, 5, etc.), and multiple pieces were sewn together. Glass stages with different densities were used. The components are the same as the glass fibers in Table 1. As shown in Table 2, the apparent density of the inorganic fiber layer is small (0.60
), even if it is large (1,62), it cannot be satisfied, and in the end, it is most preferable to have a density of only 0.70 to 1.501-/3.

Note that if the thickness of the inorganic fiber layer is thinner than the height of the protruding part of the solid refractory material, the adhesion to the welded material is likely to be impaired, so it is preferable to appropriately determine the thickness within a thicker range. ~
5.0 m is suitable.

When the backing material of the present invention is actually used, if it is lined with a fire-resistant reinforcing plate such as an asbestos board from the back side of the solid refractory material, it will be easier to set it on the material to be welded.

By the way, as the backing material of the present invention, Fig. 1(a), (
In b), the cross-sectional shape of the protruding portion is shown as being rectangular, but in the present invention, the protruding portion does not have to be particularly rectangular, and may be round or triangular.

FIG. 5 shows an example of a backing material of the present invention other than that shown in FIG. 1. (c) and (d) have a triangular cross-sectional shape of the protrusion, (e) and (f) have a round shape, and (g)
, (h) is one in which the material of the protrusion is different from the solid refractory material, for example, steel, refractory material, etc., or the protrusion may also be made of inorganic fiber. In this case, the protrusion has cushilon properties, resulting in improved adhesion. (
In i) and (j), the solid refractory material has grooves in the bead forming part, which further stabilizes the back bead build-up. (k) and (-/-) are cases where the solid refractory material has grooves and the width of the lower part of the inorganic fiber layer is narrowed so that it is tucked inside the protrusion. .

〔Example〕

The effects of the present invention are clear from Tables 1 and 2, but
The following tests were conducted to confirm the effects of the present invention. First, 10 types of backing materials of the present invention were created. The manufacturing procedure and shape and dimensions of the solid refractory material and inorganic fiber are shown in Table 3 and FIG. 7. This was set in joints with two types of groove shapes as shown in Figures 6(a) and (b), and 20 types of single-sided salamage were applied using the welding conditions and welding materials shown in Tables 4 and 5. Arc welding was performed.

After welding, the shape of the back bead was observed, and due to the effects of the present invention, excellent back beads were obtained in all cases.

〔Effect of the invention〕

The backing material of the present invention does not have a normal groove, but even when applied to a groove with a step on the back side of the material to be welded, it has an excellent backing without problems such as casting cracks or hot water leakage. It is possible to obtain beads.

[Brief explanation of drawings]

Figures 1 (a) and (b) are front views showing the cross-sectional shape of the backing material of the present invention, Figure 2 is a front view showing the cross-section of a groove with steps, and Figure 3 (,) is a front view showing the cross-sectional shape of the backing material of the present invention. Figure 3 (b)
. (C) is a front view showing the situation in which the backing material of the present invention is set in a groove having a step, and Fig. 4 (, ), (b)
Figure 5 is a front view showing the backing material of the present invention set in a normal groove, Figure 5 (e), (d), (e).
, (f), (g), (h). (i), (j), (k), ω) are shown in Figure 1 <-)
, (b) is a front view showing an example of the cross section of the backing material of the present invention other than FIG. 6 (a), (b) is a front view showing the groove shape used in the example, and FIG. , (b) is a diagram showing a row of cross-sectional shapes of the solid refractory of the backing material of the present invention. 2: Inorganic fiber layer 3: Solid refractory material 4: Material to be welded 5: Gap 6: Crimping force Figure 1 (a) Cb> Figure 2 Figure 3 B-111 Pressure j Figure 4 (It) O----ffJ Figure 5 (C) (d) (e) (f) (K) (b') H-g-111

Claims (1)

[Claims] A backing material consisting of two layers, an upper layer consisting of an inorganic fiber layer and a lower layer consisting of a solid refractory material layer, which has protrusions on both sides or one side of the upper surface of the lower solid refractory layer, and A backing material for single-sided welding characterized by having an inorganic fiber layer placed on a solid refractory material layer so as to cover the protrusion.