JPH11239895A - Backing strip having central marker for welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a backing strip having a central marker for welding which has a water repelling coating layer on its surface by forming a central mark with recessed and projected shapes without using any ink. SOLUTION: In a backing strip plural numbers of which are successively lined up in the longitudinal direction of a groove in the rear side of a butt welding groove and which is used in welding under water or in the atmosphere containing moisture, a linear groove 4 (or a linear projection) which extends in the longitudinal direction along the central line of the width of the surface is provided as a central marker in the plate surface side of a square plate-like ceramic substrate 2, and moreover the backing strip having a central marker for welding is coated by a coating layer capable of holding an air film at the time of sinking under water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to marine structures such as oil production facilities, cargo handling facilities, storage facilities, offshore airports, marine storage bases, bridges, buried tunnels, wave power / tidal current / temperature difference power generation facilities, and marine ranches. Used for offshore joining, underwater repair and maintenance, etc., it is a marker that shows the center line that is used as a reference when it is applied to the ceramic backing material with water repellency, especially when it is continuously arranged in the longitudinal direction of the welding groove. The present invention relates to a provided backing material with a center marker for welding provided.

[0002]

2. Description of the Related Art A commercially available welding backing material having a center marker is, for example, a ceramic FBB-3T (made by Kobe Steel) used for land welding. Backing material F
BB-3T has a size of approximately 30 mm square × 9 mm thick, and has a center marker (center line) marked with ink at the center of the width of the surface. When attaching a plurality of the backing materials to the back surface of the groove, the backing materials are arranged such that the center marker of the ink is aligned at the center of the groove. In addition, since this kind of backing material is a short material, there is flexibility with respect to the difference in welding groove.

On the other hand, a ceramic and water-repellent welding backing material used for welding in water or in an atmosphere containing moisture has been proposed in Japanese Patent Application No. Hei 9-148986. Since this water-repellent backing material has low surface energy, the center line cannot be marked with conventional ink.

[0004]

As described above, the backing material FBB-3T is provided with a center marker by ink, but the welding backing material having a water repellent coating layer does not accept ink. Therefore, there is a problem that a center marker cannot be provided.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a center mark formed in a concave and convex shape without using ink, and has a surface coated with a water-repellent coating layer. It is intended to provide an attached backing material.

[0006]

In order to achieve the above object, a backing material with a center marker for welding according to the present invention is provided, for example, on a back side of a butt welding groove, and a plurality of the backing materials are continuously arranged in the longitudinal direction of the welding groove. A backing material to be used side by side, wherein a linear groove or a linear protrusion extending in the longitudinal direction at the center of the width of this surface is formed on the surface of the square plate-shaped ceramic substrate facing the back side of the welding groove. Is configured as
Further, it is coated and covered with a coating layer capable of retaining an air film when submerged in water.

The coating treatment applied to the backing material with a center marker for welding is performed by (1) coating a ceramic substrate with a slurry in which hydrophobic particles and a resin are mixed and dispersed in a solvent, or 2) The treatment is performed by treating the ceramic substrate with a surface treating agent having a hydrophobic group to bind the hydrophobic group to the surface of the ceramic substrate.

Hereinafter, a method of forming a coating layer capable of retaining an air film when immersed in water and its operation will be described. It has been found that two conditions are required to maintain the air film. One is the water repellency of the material, and the other is a fine uneven structure on the surface for retaining the air film. The water repellency of the former is desirably 90 degrees or more in terms of the contact angle with water. If it is less than 90 degrees, the air film cannot be maintained for a long time. The fine irregularities on the latter surface are spaces necessary for retaining air in water. Because of the unevenness, when immersed in water, it is possible to hold air in this portion and hold an air film on the surface. It has the function of preventing direct contact between the material and water.

[0009] The shape of the fine irregularities on the surface may be a projection or a depression having a triangular, hemispherical or irregular cross section arranged continuously or irregularly. As for the size of the unevenness, the interval between the concave portions or the interval between the convex portions (hereinafter simply referred to as the interval between the uneven portions) is preferably 2 nm to 200 μm.
More preferably, it is 20 nm to 50 μm. 20n
m or less, the size of the space that can hold air is small, and the volume of the air film in water is reduced.
If it is not less than μm, the interval between the irregularities is widened, and the retention of air in water is deteriorated.

The height of the unevenness is preferably 20 nm or more.
Below this, there is a problem that the holding performance of the air film is poor.
The upper limit is not particularly limited with respect to the formation of the air film, but is in a range where the work is not difficult to perform at the time of welding and the dimensional accuracy does not deteriorate. 1 mm or less is preferable.

As a specific coating method, there is a method in which a coating liquid which has been adjusted in advance so that the above-mentioned water repellency and an uneven structure for retaining an air layer are formed after curing is applied to a backing material. Available.

The coating liquid comprises a slurry in which hydrophobic particles and a resin are mixed and dispersed in a solvent. As the hydrophobic particles, particles obtained by treating the surface of an inorganic oxide particle with a surface treating agent having a hydrophobic group or polytetrafluoroethylene particles of an organic material can be used. Since the particles constitute a concavo-convex structure for holding an air film, the average particle size is preferably 2 nm to 200 μm. More preferably, the thickness is 20 nm to 50 μm. If it is less than 20 nm, the size of the space that can hold air is small, and the volume of the air film in water will be small. If it is more than 200 μm, the interval between the irregularities will be wide, and the retention of air in water will be poor. is there. The type of inorganic oxide particles to be treated is
Examples thereof include silica, alumina, titanium oxide, and iron oxide.

As a coating method, for example, a slurry-like water-repellent agent obtained by mixing and dispersing hydrophobic inorganic oxide particles and / or polytetrafluoroethylene particles as a hydrophobic organic substance and a resin in a solvent is used. A method of coating a ceramic powder on the surface of a molded substrate, or a method of coating the substrate surface with a so-called silane compound such as alkoxysilane, chlorosilane, or silazane having a hydrophobic group, dimethylpolysiloxane, or titanate having a hydrophobic group. A method of treating with a coupling agent and a liquid of an aluminum-based coupling agent to bond a hydrophobic group to the substrate surface is used.

The hydrophobic inorganic oxide particles used in the above coating include silica, alumina, titanium oxide,
Particles of iron oxide or the like are used, and at least one kind of particles obtained by treating the particles with a surface treatment agent having a hydrophobic group is used. In particular, among inorganic oxide particles, porous particles are preferable. As disclosed by the present applicant in Japanese Patent Application Laid-Open No. 7-17476 as a method of forming an air film on a submerged surface of a structure and a film structure of the submerged surface, the particle surface is porous. Exhibits an excellent air retention function in water.

The surface treating agent having a hydrophobic group includes silane, chlorosilane, and the like having an alkyl group or a fluorine-substituted hydrophobic group.
So-called silane compounds of silazane, dimethylpolysiloxane, titanate coupling agents having an alkyl group, and aluminum-based coupling agents are used.

As the silane compound having an alkyl group,
Those having a methyl group, for example, methylmethoxysilane CH ₃ Si (OCH ₃ ) ₃ , dimethyldimethoxysilane (CH
₃ ) ₂ Si (OCH ₃ ) ₂ , trimethylmethoxysilane (CH ₃ )
₃ Si (OCH ₃ ), methyl triethoxysilane CH ₃ Si
(OC ₂ H ₅ ) ₃ , dimethyldiethoxysilane (CH ₃ ) ₂ Si
(OC ₂ H ₅ ) ₂ , trimethylethoxysilane (CH ₃ ) ₃ Si
(OC ₂ H ₅ ) and hexamethyldisilazane. In addition, as a silane compound having an alkyl group, a compound having an ethyl group may be ethyltrimethoxysilane C ₂ H ₅ S.
i (OCH ₃ ) ₃ , diethyldimethoxysilane (C ₂ H ₅ ) ₂ S
i (OCH ₃ ) ₂ , triethylmethoxysilane (C ₂ H ₅ ) ₃ S
i (OCH ₃ ), ethyltriethoxysilane C ₂ H ₅ Si (O
C ₂ H ₅ ) ₃ , diethyldiethoxysilane (C ₂ H ₅ ) ₂ Si (O
C ₂ H ₅ ) ₂ , triethylethoxysilane (C ₂ H ₅ ) ₃ Si (O
C ₂ H ₅ ). Further, as a silane compound having an alkyl group, one having a propyl group, such as propyltrimethoxysilane C ₃ H ₇ Si (OCH ₃ ) ₃ , dipropyldimethoxysilane (C ₃ H ₇ ) ₂ Si (OCH ₃ ) ₂ , propyl silane _{(C 3 H 7) 3 Si} (OCH 3), triethoxysilane _{C 3 H 7 Si (OC 2} H 5) 3, dipropyl silane _{(C 3 H 7) 2 Si} (OC 2 H ₅ ) ₂ , and tripropylethoxysilane (C ₃ H ₇ ) ₃ Si (OC ₂ H ₅ ).

As long-chain alkylsilanes, there are n-octadecyltrimethoxysilane, n-dodecyltriethoxysilane and the like.

The above-described alkoxysilane having 1 to 3 alkyl groups having 1 to 20 carbon atoms can be used alone or as a mixture of a plurality of chlorosilanes or silazanes.

Examples of the silane compound having a fluorine-substituted hydrophobic group include perfluorooctylethyltriethoxysilane CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₂ Si (OC ₂ H ₅ ) ₃ and perfluoroisopropylethyl triethoxy silane (CF ₃ ) ₂ C
In addition to F (CH ₂ ) ₂ Si (OC ₂ H ₅ ) _{3 and the} like, perfluoromethylethyltrimethoxysilane, perfluorobutylethyltrimethoxysilane, perfluorooctylethyltrimethoxysilane, perfluorooctylethylmethyldimethoxysilane And alkoxysilane having a perfluoroalkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms.

As the titanate coupling agent, isopropyl triisostearoyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate,
Examples thereof include tetraisopropyl bis (dioctyl phosphite) titanate and tetraoctyl bis (ditridecyl phosphite) titanate.

Examples of the aluminum-based coupling agent include acetoalkoxyaluminum diisopropylate.

The backing material with the center marker for welding that has been subjected to the above treatment has a property of being completely or almost not wetted by water. When submerged in water, it has the property of forming a thin film of air on the surface. This air film can be confirmed by being reflected in silver when exposed to light.

Here, the property that the coating layer formed by each of the above surface treatment agents can retain an air film when immersed in water will be described with reference to FIG. As shown in FIG. 4, a coating layer 2 is formed on a part of the surface.
When the flat plate 20 (plate made of metal, ceramic, synthetic resin, or the like) formed with No. 1 is put into the water 23 from the air, the air contacting the surface of the coating layer 21 is brought into the water while being held, and An air film 22 is formed on the surface.
Then, for example, when a small amount of air is sent to the air film 22 through the thin tube 24, the air is taken into the air film 22 and the film 22 expands as shown by a dotted line. Thus, the coating layer 21 has a thin air film 2 on the surface in water.
2 and has a unique property that air supplied from outside is taken into the air film 22.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A backing material with a center marker for welding according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a backing material with a center marker for welding according to the first embodiment (hereinafter, a backing material with a center marker for welding is sometimes simply referred to as a backing material). This backing material 1 is provided with a wide groove 3 having a dish-shaped cross section and extending in the longitudinal direction of the substrate 2 on the surface of the substrate 2 having a size of about 30 mm × 9 mm.
And a thin groove 4 at the center of the groove 3 as a center marker.
Is provided. The backing material 1 is made of ceramics and has been subjected to a water-repellent treatment, and a coating layer capable of holding an air film when immersed in water is formed on the surface thereof. Note that holes may be linearly arranged as center markers instead of the narrow grooves 4.

FIG. 2 is a view showing a backing material with a center marker for welding according to a second embodiment. This backing material 5 is provided with a linear projection 6 as a center marker in place of the thin groove 4 in the backing material 1, and is otherwise the same as the backing material 1.

FIG. 3 shows a plurality of backing materials 1 (or 5).
FIG. 3 is a view showing a state in which the underwater welding is performed by arranging and attaching in a longitudinal direction of a welding line to the back surface of a groove 11 formed between the welding members 10 and 10. The plurality of backing materials 1 (or 5)
The center marker 4 is arranged by hand so as to coincide with the center of the welding groove 3. Then, the plurality of backing materials 1 (or 5) are fixed to the welding members 10, 10 with an adhesive or double-sided adhesive tape applied to the surface thereof. A magnet can be used instead of such adhesion. Alternatively, the backing material 1 (or 5) may be fixed to the welding members 10 and 10 from the back of the backing material 1 (or 5), for example, by applying a band-like fixing tool and bonding or using a magnet. Good.

Here, as an example of the underwater welding method using the backing material of the present invention, a water curtain type wet underwater welding method will be briefly described. The water curtain type wet underwater welding method is performed using a gas metal arc welding method. In principle, the outer nozzle constituting the welding torch 12 has a double cylindrical structure,
Water is sprayed from a gap between the inner and outer cylinders to form a trumpet-shaped water curtain 13 on the welding groove 11, and a shielding gas is flown from the inner cylinder to form a cavity 14 inside the water curtain 13, and inside the cavity 14, The welding wire 15 is supplied, and the welding wire 1 is supplied.
In this method, an arc is generated between the welding groove 5 and the welding groove 11 to perform welding. Since the backing material of the present invention has a coating layer capable of retaining an air film when submerged in water, the backing material has a property of being completely or almost not wetted by water. Then, when submerged in water, the air in contact with the air is brought in and a thin air film is formed on the surface. This air film can be confirmed by being reflected in silver when exposed to light. In the cavity, water is completely eliminated by the shielding gas and becomes water-free, and stable welding can be performed. Note that the backing material of the present invention can be used for welding on land, for example, in the rain.

[0028]

According to the present invention, the backing material with the center marker for welding is constituted by providing a linear groove or a linear projection or a linearly arranged hole as a center marker on the surface side of the ceramic substrate. In addition, there is an effect that a center marker can be provided even on a backing material that cannot have a center mark with ink because of having a water-repellent coating layer.

[Brief description of the drawings]

FIG. 1 is a diagram showing a shape of a backing material with a center marker for welding according to a first embodiment of the present invention.

FIG. 2 is a view showing a shape of a backing material with a center marker for welding according to the first embodiment of the present invention.

FIG. 3 is a view showing a state in which a backing material with a center marker for welding according to the present invention is arranged behind a welding groove;

FIG. 4 is a diagram illustrating a coating layer that holds an air film on the surface in water.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Backing material with center marker for welding 2 Substrate 3 Wide dish-shaped groove 4 Center marker (narrow groove) 5 Backing material with center marker for welding 6 Center marker (linear projection)

Claims (3)

[Claims] 1. A backing material for a welding groove, wherein a linear groove, a linear protrusion, or a hole arranged in a line at the center of the width of the backing material on a surface facing the back side of the welding groove is a center marker. A backing material with a center marker for welding, wherein the backing material is covered with a coating layer capable of holding an air film when submerged in water. 2. The backing material with a center marker for welding according to claim 1, wherein the coating treatment is performed by coating a slurry in which hydrophobic particles and a resin are mixed and dispersed in a solvent. 3. The coating treatment is performed by treating a ceramic substrate with a surface treating agent having a hydrophobic group to bond the hydrophobic group to the surface of the ceramic substrate.
Backing material with center marker for welding as described.