JPH11309586A - Joining method of metal tube and metal cylindrical joint used in its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for joining metal tubes whose joining surfaces are not opened toward the outside in the radial direction and into the joining surface of which an inserting material is surely filled at the time of being joined and a metal cylindrical joint, when the metal tubes are joined by liquid phase diffusion bonding. SOLUTION: In a method for joining a metal tube to another metal tube by arranging an inserting material 6 in a butting part between the metal tube and another metal tube and by melting and solidifying the inserting material 6, a metal cylindrical joint 4a is arranged in the butting part between the metal tube and another metal tube so as to stride over the butting part, and the inserting material 6 is arranged between the inside periphery of the metal cylindrical joint 4a and the outside periphery of the metal tubes in the abutting part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal pipe joining method and a metal cylindrical joint in which an insert material is arranged at a butt portion of a metal pipe, and the metal pipe and the metal pipe are subjected to liquid phase diffusion joining.

[0002]

2. Description of the Related Art Conventionally, various welding methods have been generally applied as a joining method for metal pipes. In recent years, application of liquid phase diffusion joining in place of welding has been studied. In this liquid phase diffusion bonding, by placing an insert material having a lower melting point than the material to be bonded between the materials to be bonded and applying pressure, the joint is heated to a temperature just above the liquidus line of the insert material, This is a joining method for melting and isothermally solidifying the insert material, and has a joining strength equivalent to that of the material to be joined. In this liquid phase diffusion bonding method, a thin amorphous alloy foil is generally used as the insert material, so that the bonding surface is filled with the molten insert material so that the bonding surface is interposed through the insert material until the bonding is completed. It is important that they are brought into contact with no gap. If the joining surfaces are brought as close as possible via the insert material, more ideal joining will be performed, and the joining strength will be strong. However, if there is a gap between the joining surfaces during joining, the molten insert material will not be filled between the joining surfaces, and some will be unjoined, resulting in a lower strength than the material to be joined. It breaks at the joint where the joining was performed.

[0003] As a method of realizing a strong joining by joining a metal pipe by liquid phase diffusion joining so that the joining is not broken at the joining portion during the tensile test but is broken at the material to be joined, there is a method disclosed in U.S. Pat.
No. 3 discloses a method in which end joining surfaces of two metal pipes to be joined are processed into an inlay type so as to be fitted, and an insert material is inserted therebetween to join them.

[0004]

However, when the joining is performed by the method disclosed in Japanese Patent Application Laid-Open No. 4-75773, before the heating, the two steel pipes 1 to be joined are fitted together to form the outer end face 31a before heating, as shown in FIG. , 31b, inner end face 32a,
32b, and the outer peripheral surface 33 and the inner peripheral surface 34 maintain a gap 35 corresponding to the thickness of the insert material 6. However, when the joint is pressurized and heated in order to perform liquid phase diffusion bonding, a high temperature state is obtained. Pressing force is applied to the metal pipe by the pressure, and as shown in FIG. 5, the end joining surface is deformed radially outward due to the pressing force and thermal expansion, and the outer end surface, the inner end surface, the outer peripheral surface and the inner joint surface are deformed. A gap 3 between the peripheral surfaces that is larger than the thickness of the insert material
6a, 36b, and 36c are generated, and the melted insert material is not filled in the gap, an unbonded portion is generated, and the bonding strength is reduced. The present invention solves such a problem, and a joining method of a metal pipe and a metal cylindrical joint, in which a joining surface does not open outward in a radial direction at the time of joining by a simple method and an insert material can be reliably filled into the joining surface. The purpose is to provide.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method for joining metal pipes by using liquid phase diffusion joining and a metal cylindrical joint, the gist of which is as follows. (1) In a method in which an insert material is arranged at a butt portion between a metal tube and a metal tube, and the insert material is melted and solidified to join the metal tube and the metal tube, A method for joining metal pipes, comprising: arranging a metal cylindrical joint so as to straddle the butt portion; and arranging an insert material between an inner peripheral surface of the metal cylindrical joint and an outer peripheral surface of the metal tube at the butt portion.

(2) The method for joining metal tubes according to the above (1), wherein liquid phase diffusion joining is used as the joining method.

(3) The method for joining metal tubes according to the above (1) or (2), wherein a metal cylindrical joint having a smaller coefficient of thermal expansion than the metal tube is used.

(4) The method for joining metal pipes according to the above (1), (2) or (3), wherein an insert material is previously attached to at least one of a metal cylindrical joint or a metal pipe. .

(5) A metal cylindrical joint whose inner diameter is slightly larger than the outer diameter of the end of the metal pipe to be joined, wherein an insert material is attached to an inner peripheral surface of the joint. ), (2), (3) or (4).

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a simple method for performing liquid phase diffusion bonding of a metal tube, but the bonding surface does not open radially outward and the insert material is securely bonded to the bonding surface. In order to fill the joint, an outer peripheral surface of the end portion of the metal pipe is joined to the joint using a metal cylindrical joint (hereinafter, simply referred to as “joint”). The term “insert material” here refers to an amorphous alloy foil, a powder, a plated material, or the like when performing liquid phase diffusion bonding.

The present invention will be described below with reference to the drawings.
FIG. 1A is a cross-sectional view schematically showing a joining method when a steel pipe is used as a metal pipe. In FIG. 1, the steel pipe 1a
The end face 2 is machined perpendicular to the tube axis. This steel pipe 1a
Steel pipe 1 for joining a joint 4a having an inner diameter larger by the thickness of the insert material to be inserted than the end outer peripheral surface 3 of the steel pipe 1
a into the outer peripheral surface 3 of the steel pipe 1a, insert the outer peripheral surface 3 of the other end of the steel pipe 1a into the joint, and fit the outer peripheral surface 3 into the steel pipe;
The outer peripheral surface 3 of the other end of the steel pipe 1a is inserted into a joint, and the end faces 2 of the steel pipes are butted against each other.

At this time, an insert material 6 is inserted between the end outer peripheral surface 3 and the joint inner peripheral surface 5. In this state, when a predetermined pressing force is applied to both sides of the steel pipe 1a and heating is performed to a predetermined temperature, only the insert material is melted, and the insert melted between the end outer peripheral surface 3 of the steel pipe and the joint inner peripheral surface 5 is melted. The material is filled and liquid phase diffusion bonding occurs. Further, since the joint 4a is on the outer peripheral surface 3 of the steel pipe 1a, even if the end joint surface is deformed radially outward due to the pressing force and thermal expansion at the time of joining,
The joint suppresses the deformation and the gap can be filled with the insert material.In addition, the deformation makes the joint close to the joint, so the gap between the outer peripheral surface of the joining end and the inner peripheral surface of the joint becomes smaller, A strong bond results. Therefore, even when a tensile test is performed, the joint does not break.

In the present invention, as shown in FIG. 1 (b), an insert material can be inserted between the butted and opposed steel pipe end faces 2 and joined. In this case, the bonding area for the liquid phase diffusion bonding increases, and the bonding strength can be further improved.

The joint used in the present invention is made of a material having a strength equal to or higher than the strength of the metal pipe, and has a slightly larger inner diameter with respect to the outer peripheral surface of the end of the metal pipe so as to have a gap between the metal pipe and an insert material. The material and structure are not particularly limited, but the gap between the joint and the metal pipe is preferably 1 mm or less.

In the present invention, it is desirable to use a joint having a coefficient of thermal expansion smaller than that of the metal tube.
This is because the deformation due to the thermal expansion of the joint becomes smaller than the thermal expansion of the metal pipe, so that the deformation that the metal pipe opens radially outward during joining can be further suppressed.

The joint is preferably installed symmetrically on both sides with respect to the joint, and the metal pipe and the joint are preferably parallel to each other from the viewpoint of suppressing deformation due to the pressing force during joining.

In the present invention, in addition to the example shown in FIG.
The method is also included as shown in FIGS. 2 and 3 are cross-sectional views schematically showing a joining method when a steel pipe is used as a metal pipe. In FIG. 2, a joint 4b having an inner diameter smaller than the outer diameter of the steel pipe 1b to be joined and larger than the inner diameter of the steel pipe 1b, and end faces 2a and 2b of the steel pipe 1b are perpendicular to the pipe axis, and are inserted from the inner diameter of the joint 4b. A steel pipe 1b processed to be smaller by the thickness of the material is used. By performing such processing, the length of the outer peripheral surface 3 of the end portion of the steel pipe when butted against each other can be constant, so that stable joining quality can be obtained.

In FIG. 3, the outer diameter of the steel pipe 1c to be joined and the outer diameter of the joint 4c are equal, and the outer diameter of the end outer peripheral surface 3 of the steel pipe 1c is equal to the thickness corresponding to the thickness of the joint 4c and the insert material. The steel pipe 1c and the joint 4c, which are processed to be smaller by the thickness of the steel pipe 1c, are used. This is effective when a projecting portion is not allowed in the outer diameter of the steel pipe.

The examples shown in FIGS. 2 and 3 can also be joined by inserting an insert material between the opposed steel pipe end faces 2a and 2b.

According to the present invention, since a joint is used,
Aligning easily by inserting and butting the end joint surfaces of the steel pipes to be joined while using the inner peripheral surface of the joint as a guide surface (correcting misalignment, steps, and misalignment of the axis) (Hereinafter referred to as "alignment"), the alignment is simpler than in the conventional steel pipe butt work at the time of on-site work, and the joining time is shortened and the cost is reduced. Further, by using at least one of the steel pipe or the joint to which the insert material is attached in advance, the work of inserting the insert material at the joining site or forgetting to insert the insert material is eliminated, so that the joining time can be reduced, the joining quality can be stabilized, and the like.

[0021]

EXAMPLES The steel pipes were joined by liquid phase diffusion bonding according to the method of the present invention. The steel pipe is STK4 specified in JIS G3444.
00, outer diameter 264.4 mm, inner diameter 228.8 mm, wall thickness 1
7.8 mm. As shown in FIG. 6, the joint between the two steel pipes 1d was processed such that the end faces 2a and 2b of the steel pipes were perpendicular to the pipe axis, and the outer diameter of the steel pipe 1d was equal to the outer diameter of the joint. Fitting 4
d is the same material as the steel pipe 1d to be joined and has an outer diameter of 264.4 mm,
The inner diameter was 246.8 mm, the wall thickness was 8.8 mm, the length was 10 mm, and the gap between the outer peripheral surface 3 of the steel pipe end and the inner peripheral surface 5 of the joint was 0.1 mm. Insert material is Fe-9wt% S
An amorphous alloy foil having a composition of i-1.5 wt% B was used. This insert material 6 was pasted on the inner peripheral surface 5 of the joint 4d using a resin that gasifies before the insert material melts. Further, ring-shaped inserts 6a, 6b along the end surface shape were also attached to the end surfaces 2a, 2b of the steel pipe 1d. In each case, the thickness of the insert material is about 0.1 mm.

After inserting this joint 4d into one steel pipe,
The remaining steel pipe 1d was inserted, and the end faces 2a and 2b of the steel pipe were butted against each other. At this time, since the joint 4b acted as a guide, the centering could be easily performed. 5MP in this state
The pressure of a was applied, and the joint was heated by high-frequency induction heating.
The heating rate during heating was 5 ° C./sec. After reaching 1200 ° C., the temperature was held for 5 minutes, and the power was turned off to cool.

For comparison, liquid phase diffusion bonding was performed on a steel pipe processed into an inlay type shown in FIG. In the comparative example, the same steel pipe as the example of the present invention was used, the length of the outer peripheral surface 33 and the inner peripheral surface 34 was 10 mm, the thickness of the outer end surface 31a was 8.8 mm, and the gap between the outer peripheral surface and the inner peripheral surface was 0.1 mm. Processed to become. The thickness of the insert material used was 0.1 mm as in the case of the present invention, and the joining conditions were similar to those of the present invention, heated to 1200 ° C. at a pressure of 5 MPa, held for 5 minutes, and then cooled.

After cooling, a tensile test piece having the joint substantially at the center was sampled and subjected to a tensile test. As a result, in the examples of the present invention, the base material was broken for all the test pieces. On the other hand, in the comparative examples, all the test pieces were broken from the joined portions, and some unjoined portions were formed.

[0025]

According to the present invention, when the metal pipes are joined by the liquid phase diffusion joining of the present invention, a joined portion having a reliable joining and high strength can be obtained. In addition, since the centering action is performed at the time of joining the steel pipes, the work efficiency can be improved in the butt joint on site. Further, if at least one of the joint or the metal pipe to which the insert material is pasted is used, the insert material is not handled on site, and the joining operation is further facilitated.

[Brief description of the drawings]

FIG. 1A is a schematic view (side sectional view) showing an example of the present invention.
It is. (B) It is the schematic diagram (side sectional drawing) which shows another example of this invention.

FIG. 2 is a schematic view (side sectional view) showing another example of the present invention.
It is.

FIG. 3 is a schematic view (side sectional view) showing another example of the present invention.
It is.

FIG. 4 is a schematic view (side sectional view) showing a comparative example of the present invention.

FIG. 5 is a schematic view showing a modification of the comparative example of the present invention.

FIG. 6 is a schematic view showing an embodiment of the present invention.

[Explanation of symbols]

 1, 1a, 1b, 1c, 1d ... steel pipe 2, 2a, 2b ... end surface 3 ... end outer peripheral surface 4a, 4b, 4c, 4d ... joint 5 ... inner peripheral surface 6, 6a, 6b ... insert material 31a, 31b ... Outer end surfaces 32a, 32b ... Inner end surface 33 ... Outer peripheral surface 34 ... Inner peripheral surface 35 ... Gap 36a, 36b, 36c ... Gap at the time of joining

Claims (5)

[Claims] 1. A method for joining a metal tube to a metal tube by disposing an insert material at a butt portion between the metal tube and the metal tube and melting and solidifying the insert material. A metal cylindrical joint is disposed so as to straddle the butt portion, and an insert material is disposed between an inner peripheral surface of the metal cylindrical joint and an outer peripheral surface of the metal tube at the butt portion. Method. 2. The method according to claim 1, wherein liquid phase diffusion bonding is used as the bonding method. 3. The method for joining metal tubes according to claim 1, wherein a metal cylindrical joint having a smaller coefficient of thermal expansion than the metal tube is used. 4. The method for joining metal pipes according to claim 1, wherein at least one of a metal cylindrical joint and a metal pipe is pasted with an insert material. 5. A metal cylindrical joint whose inner diameter is slightly larger than the outer diameter of an end portion of a metal pipe to be joined, wherein an insert material is attached to an inner peripheral surface of the joint. A metal cylindrical joint used in the method according to 2, 3, or 4.