JPS6297784A - Butt joining method for pipe - Google Patents

Abstract

PURPOSE:To increase a joining strength and work efficiency by abutting two pipes to be joined by pinching an inserting material, by pinching them respectively with a pair of combined clamp mechanism and by joining with diffusion by heating the vicinity of the pipe joining part. CONSTITUTION:A pipe A, B is respectively pinched by a pair of clamp mechanism a, b which is combined via a linking body 1 by abutting the pipe end in the state of pinching an inserting material 3 between two pieces of pipes A, B to be joined. The vicinity of the pipe joining part 5 is then heated by the heating device 4 composed of a high frequency coil, etc. In this case, an amorphous metallic foil, etc. are used for the inserting material 3 and the joining part 5 is shielded via a shielding cover 19 and taken to be in vacuum state or protecting gas atmosphere. The heating device is miniaturized, the work on-site is facilitated and the joining part 5 is subjected to diffused junction. Consequently the joining strength and work efficiency can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a pipe butt joining method by diffusion joining, and more particularly to a simple and reliable joining method suitable for construction sites such as construction sites.

(Conventional technology) Recently, the disparity in lifespan between buildings and auxiliary equipment has become a problem.

For this reason, research and development is underway on new techniques that take advantage of the durable and strong characteristics of stainless steel when selecting piping materials. For butt joining of stainless steel pipes, surface welding using a tubular elder is well known, and the currently popular welding machines in Japan include the automatic tube pipe welding machine manufactured by AstroArc in the United States, and the T manufactured by Arc Machine.
There are automatic G-tube pipe welding machines, but the disadvantage of all of them is that they are expensive. In the United States, this method is mainly used only for welding piping for equipment that requires severe conditions such as space development, aircraft, nuclear power generation, and coast guard high-speed boats, and is of excessive quality as a welding technology for architectural piping. ,
This is an excessive price.

On the other hand, a diffusion bonding method is known as a method of bonding hot superalloys such as high-temperature gas turbine blades having complicated inner holes. There are two types of diffusion bonding methods: one in which insert material is sandwiched between the parts to be joined and one in which insert material is not sandwiched.The former method requires less pressure and requires less time to join due to the insertion of insert material. Because of these advantages, the above-mentioned stainless steel pipe can be applied as an architectural piping technique.

(Problems to be solved by the invention) However, the conventional method of butt joining pipes by diffusion joining,
After placing an insert material such as an amorphous ribbon in the part to be joined, a constant-load processing device applies pressure while heating it, which requires a large-scale pressurizing device, making it difficult to use on-site for construction piping, etc. Not suitable for

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for butt-joining pipes by secondary diffusion bonding, which is simple and suitable for on-site use and does not require a pressurizing device.

In addition, as a conventional method of butt joining pipes by diffusion joining, for example, the first stage is 3 kQf7. A two-stage pressurization method is known in which the insert material is pressurized at 1 kq and then re-pressurized at 1 kq at the liquidus temperature of the insert material as a second step, but the uninvented butt joining method can be used without a pressurizing device. This enables strict and preferable pressure control comparable to two-stage pressurization.

(Means for Solving the Problems) The gist of the present invention will be described with reference to the principle diagrams in FIGS. 1 and 2. Two butted pipes to be joined (3) (B) e,
Nine pairs of clamp mechanisms (a) connected by a connecting body (1)
(b), and in this state, the tubes to be joined (
A) (B) is heated near the abutting part (5) with a heating device (4)
This method of butt-joining tubes is characterized by diffusion-joining by heating the pipes.

Insert material (3) to be inserted between the pipes to be joined (A) and CB) to shorten diffusion bonding time is to avoid the risk of leaving oxides etc. in the joint in order to ensure the strength and quality of the joint. It is preferable to use a non-crystalline metal foil.

The method of fixing the insert material (3) is to use a pipe to be joined (CA)
■Method of fixing by sandwiching or insert material (5)
There is a method of fixing the pipe to the joint surface of the pipe end using spora) ffl contact in advance.

The bonding atmosphere is preferably a vacuum atmosphere with a protective gas such as argon, nitrogen, helium, or hydrogen.

In FIG. 1, 0O is a companion shield cover that maintains the joint (5) in these atmospheres.

, the mutual diffusion time between the insert material (3) and the pipe to be joined (CA) depends largely on the thickness of the insert material (3). It can be completed within 1 time, which is equivalent to the 3 to 5 minutes required by the T-G welding method, etc., and at the time of completion, the alloy layer of the insert material (3) does not remain on the joint surface in order to ensure the strength of the joint. In order to achieve this, it is preferable that the thickness be 70 μm or less.

Although any type of heating device (4) may be used, a device using a high-frequency coil as shown in the figure is small in scale and is one of the devices particularly recommended for on-site use.

The clamping means for the pipes to be welded will be explained in detail later in the specific example section.

(Function) In the butt joining method of the present invention, if the vicinity of the butt part (5) of the clamped pipes to be joined <A) (B) is heated, for example, as shown by the broken line in Figure 2g, Stress due to axial thermal expansion of the joint tubes (A) and CB) is generated at the butt joint surfaces. This stress eliminates gaps caused by surface roughness of the joint surfaces. After that, this stress is relieved by softening due to heating of the butt part (5), and a constant pressure is maintained during pressurization, and the insert material (3)
is dissolved and the pipe to be joined (3) ■ is diffusion-joined. This pressing pattern is none other than the above-mentioned two-stage pressing, which eliminates the shadow of the surface roughness of the gap between the bonding surfaces and provides good adhesion.

By adjusting the clamping force of the tube to be joined (A) (a), and by adding some innovation to the clamping mechanism, it is also possible to actively adjust the pressure over a wide range.

An example of introducing diffusion bonding to join metal pipes is the manufacture of clad steel pipes by diffusion bonding.

For example, as described in Japanese Patent Application Laid-Open No. 59-159284, an insert metal is interposed between the inner tube and the outer tube, and then the outer tube is heated by thermal expansion in the radial direction of the inner tube. This method is similar to the butt joining method of the present invention in that a pressure device is not used. However, the manufacturing of clad steel pipes utilizes the thermal expansion in the radial direction of the inner tube, which is not only fundamentally different from the uninvented butt joint method that utilizes thermal expansion in the axial direction of the tube. Since the difference in thermal expansion between the tube and outer tube is used, there are restrictions on material selection.
Moreover, active pressure management is possible, but it does not have the versatility of the uninvented butt joining method.

(Specific Example) Next, the apparatus used in the butt joining method of the present invention will be explained along with its usage procedure.

Figure 3 shows one of the devices; a) Figure is a front view;
(b) The figure shows a side view. In this device, clamp mechanisms (a) and (b) at both ends of the connecting body (1) clamp the pipe ends GA) and CB) using the bolts (9) and pins αυ. A load cell (8) for measuring the force applied in the axial direction is provided at the center of the connecting body (1).

In order to carry out the uninvented butt joining method using this device, the insert material (3) is fully inserted between the pipe ends of the pipes to be joined (8) (to), and the clamping mechanisms (a) (b) are in the next state. ) and tighten (9) with a torque wrench. If you adjust the tightening torque of the torque wrench to a large value, it will be a complete clamp that does not allow axial movement, and if you adjust the tightening torque to a weaker value, the clamp will be strong enough to allow the pipe to move in the axial direction. can give.

After installation, the abutted portions are heated and joined by a heating coil or the like, but the axial stress generated in the joined portions at this time differs depending on whether the above-mentioned complete clamp is used or not.

Figure 4 shows the tendency of the heating temperature of the joint to change with elapsed time in the case of complete clamping, using the heating curve (6).
The axial stress generated in the joint portion is shown by a curve (7a). According to the figure, pressure stress is generated at the joint due to thermal expansion in the tube axis direction at the same time as heating starts. This stress has the function of flattening the gaps between the surface roughness of the joint surfaces. This pressurizing stress due to thermal expansion in the tube axis direction is relaxed by the softening of the material when the heating temperature is maintained, and a constant pressurizing stress is maintained during the heating and holding period. Next, when the heating temperature is lowered, the material begins to shrink during the cooling process, and the pressurized stress becomes tensile stress. Since this tensile stress is about 10 times the strength of the joint, it does not adversely affect the joint.

In this complete clamp method, the pressurized stress curve due to thermal expansion (
The temperature increase pattern 7a) has an effect comparable to that of the conventional two-stage pressurization method, and has good adhesion without being affected by gaps or surface roughness of the bonded surfaces, and also has a constant load of the conventional method. Similar to the pressure method, it is possible to obtain joints with small plastic deformation.

FIG. 6 shows the relationship between temperature and pressure when the clamp of the material to be joined CA) (B) is adjusted to a degree that allows movement in the axial direction. The heating curve (6) is the same as that for the complete clamp (FIG. 4), but the pressure stress curve (7b) is different. In other words, in the case of complete clamping, the pressure stress and
If a relatively large tensile stress occurs when the temperature falls, but the clamping is not complete, the above pressure stress and tensile stress can be arbitrarily reduced by adjusting the clamping force of the welded material (A)@. As a result, it is possible to suppress the joint bulge (FIG. 5) to within 1% of the joint cross-sectional area.

The material clamp that allows the axial movement of the pipe is the pipe to be joined (A).
[F]) This may be done with the clamping machine G4M3->(b) on both sides, or it may be done with the clamping mechanism (a) or (to) on one side (in this case, the other side is a complete clamping mechanism). Become). When material movement is allowed by the clamp mechanisms (a) and (b) on both sides, the "looseness" required to allow movement of the pipes to be joined (3) (g)) is divided between the left and right sides.

Figure 7 shows another example of the device;
b) The figure is a sectional view taken along line A-A. This device basically has a structure in which the clamping mechanism (a) ('b) at the end of the connecting body (1) is tightened with a port)OQ and a nut αυ, but in particular, improvements have been made to the port μ)00. Figure (C) shows the bolt a (], an enlarged opening of the nut OG, and Figure (C) shows the BB cross section of the port trunk.

In this device example, the material clamping mechanism ('b) can be made into a complete clamp or a clamp that allows axial movement by adjusting the tightening force of the bolt 00 and nut OG, and the bolt Qq, The tightening force of the nut α is adjusted while being measured with a strain gauge 02 attached to the bolt trunk.

FIG. 8 shows still another example of the device, ((a) is a front view, and (b) is a cross section along line C-C'. In this device, one side of the clamp mechanism ('b) is attached to the inlay 0 ) allows movement along the connecting body (1). (14) is a fixed piece fixed to one side of the connecting body (1) with a pole H etc., which prevents the clamp machine groove ('b) from moving to the outside of the connecting body (1) and toward the inside thereof. Allow movement only. Tightening screw 07
) in the beam lamp mechanism) to the connecting body (1) is adjusted by its tightening force. According to this device, the compressive stress due to thermal expansion during heating is the same as in the case of a complete clamp, but the tensile stress due to contraction during cooling becomes zero when the inlay is sliding, and the inlay is completely closed. When has a coefficient of friction, the tensile stress during cooling is reduced according to that value.

(Example) Example 1 below describes whether the bonding performance by the non-inventive method is sufficient. This was confirmed by a comparative test between Example 2, Example 8, Example 4 and the conventional method.

Table 1 shows the chemical composition of the pipes to be joined used in the test.

Table 2 shows the chemical components of the insert material (amorphous material) used in the test. In the same table, MBF-15, MBF-
80, MBF-75, and MBF-80 are commercially available products.

Prototypes 1 to 6 are manufactured by Ido Chemical Co., Ltd. under the trade name Ashi, and prototypes 1 to 6 are produced by ultra-quenching the molten metal using a material with the chemical components shown in the table.
The following was specially produced as an amorphous ribbon with a thickness of ~60 Pm for the purpose of practicing the invention.

In the conventional method, the pipes to be welded and the insert material are used, and the vicinity of the part to be welded is heated and welded while applying pressure from the outside with a constant load device. Heating temperature is 1040-1200°
C1 heating time is 5 minutes, pressure stress is 1.0 kgf/, i
And so.

On the other hand, in Embodiment 1, the clamp mechanism (a
) (to) The tightening port is tightened with a torque wrench to completely clamp the material, and the vicinity of the front joint is heated to obtain a pressure curve as shown in FIG. 4.

Embodiment 2 is a clamp mechanism (al(b) at both ends of the connecting body).
) by adjusting the tightening force of the tightening bolt (free clamp) to allow movement in the axial direction.
This is the case when a pressurized stress curve like No. 6 □□□ is obtained.

The material of all the tubes to be joined was SUS 804, and the heating method for the tube joint was a combination of a high frequency heating coil and an argon gas shield.

Table 8 shows the results of these comparative tests. The joint performance was measured by taking samples from the pipe joints and calculating 7'c22.2 / X 1 t (y
The tensile strength obtained by subjecting the test piece of m) to a room temperature tensile test #
f/-), elongation (%), and drawing shear (%).

As is clear from Table 3, in Examples 1 and 2 using the method of the present invention, the pressure stress was 8 to 8 when the temperature was increased.
12kg roux, 1.0-1.5 #f/l when heated and held
lI was obtained, and a value that was almost the same as the pressure stress of 1.0 # ru when using a constant load pressurizing device in the conventional method was obtained, and the bulge at the joint was also as small as in the conventional method. , the plastic deformation rate (increase in the ratio of the cross-sectional area of the bulge to the cross-sectional area of the tube base material) at the joint of the pipe can be kept to a small value within 1%.

In both Example 1 and Example 2 of the method of the present invention, the tensile strength was 55 to 59 in the same room temperature tensile test as the conventional method, and the elongation was 40.
~55%, and the aperture of 54 to 46% could be guaranteed.

Table 4 shows other comparative samples, and the bonding base materials are SUS 304.5US304L and 5US316.5.
Four steel types of US316L were used, and the insert material was prototype 6 (Table 2), which was punched out to fit the cross-sectional shape of the joint surface.90 In Example 3, the vicinity of the pipe joint was heated in a fully clamped state, and the insert material shown in Figure 4 was used. When the pressure stress curve was obtained, in Example 4, the vicinity of the pipe joint was heated with a clamp (free clamp) shape that allowed movement in the axial direction, and the pressure stress curve as shown in Fig. 6 was obtained. This is the case. The conventional method was the same as in Table 8.

As shown in Table 4, for Examples 3 and 4 of the non-inventive method, the pressurizing stress of the non-inventive method was 8 to 12 #sea when the temperature was raised, and 1.0 to 1.5 kgf/ when the temperature was maintained. gJ was obtained, and a value almost unchanged from the conventional method's pressurized stress of 1.0"f/7 was obtained, and in the room temperature tensile test that shows the bonding performance, the tensile strength was 56 to 59 k'if/ d, elongation is 4
They were in the ranges of 5 to 50% and υ of 46 to 50%, respectively.

That is, the uninvented method (Example 3, Example 4) could guarantee the same excellent bonding performance as the conventional method.

Furthermore, the base material to be joined as the material to which the invention is applied is 5US304.
．． 5US304L, SUS 816.5US816L
Materials with a high linear expansion coefficient (usually θ ~ 650°), including austenitic stainless steel, are not limited to
llXl0-' or higher in C), any of them can be applied.

(Effects of the Invention) As is clear from the above description, the present invention has a simple structure and uses an easily operated clamp machine groove to easily obtain a joint with a strong joint hole and a small joint bulge. The effect on improving the construction efficiency for on-site construction of architectural piping etc. is large at 4'JA.

[Brief explanation of drawings]

1 and 2 are schematic side views explaining the invention in detail, FIG. 3 shows one example of the device of the invention, (a) is a front view, (b) is a side view, Figure 4 is a diagram illustrating the pressurizing stress when the joint material is completely compressed, Figure 5 is a diagram explaining the bulge of the pipe joint, and Figure 6 is a diagram illustrating the pressure stress when the joint material is completely compressed. Figure 7 shows another example of the device, and Figure 7 is a front view.
B) Figure is A-A sectional view, (C) Figure is an enlarged view of the bolt and nut, B) Figure is B-B sectional view, Figure 8 shows another example of the device, and Figure A is the front view and stem. ) is a sectional view taken along line C-C. 1: Connecting body, a, b: Clamp mechanism, 8: Insert material, A, B: End of pipe to be joined, 4: Heating coil, 5: Butt part, 6: Heating temperature curve, 7a, 71): Pressure stress Curve, 8: Load cell, 9: Fixed port/&), lO: Tightening bolt, ll: Bin, 12: Strain gauge, 18: Coating, 14: Fixed piece, 15: Nut, 17: Tightening screw, 18
: Inlay, 19: Shield cover, 20: Bolt.

Claims (1)

[Claims] (1) A pair of clamp mechanisms (a) that connect two pipes (A) and (B) to be joined with their ends butted together with the insert material (3) held together by the connecting body (1). (b), and in this state, the pipes (A) and (B) to be joined are diffusion-joined by heating the vicinity of their butt portions (5).