JPH0732194A - Method for butt joining metallic tube and bar and deice therefor - Google Patents

Abstract

PURPOSE:To provide a method and device for joining by which butting precision of joining surface is improved when a metallic tube and bar are butt joined and excellent quality is obtained. CONSTITUTION:Using a holding and fixing device 2 provided with a device by which three or more fulcrums are pressed joining materials 1A and 1B are butt held, then, a part rear of joining part is heated to 400 to 1250 deg.C by heating devices 4A and 4B. Thus, the joining materials are easily deformed by heating and butt contact precision of joined surface is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to heat-welding or brazing of pipes and rods made of metal, especially iron and alloys containing iron.
In butt joining such as liquid phase diffusion joining, the present invention relates to improvement of butt dimension accuracy of joining surfaces.

[0002]

2. Description of the Related Art Butt joining of steel pipes or reinforcing bars is performed by welding or screws. However, against the background of improvement in quality and efficiency, and lack of welding technicians, heating and pressure welding, brazing, liquid phase diffusion bonding, etc. have been proposed. For example, liquid phase diffusion bonding is described in “Sumitomo Metals” Vol. 43 (1991), no. 7
As reported in, insert a brazing material between the joint surfaces,
It is said that this is a method of heating and pressing and joining, which requires no skilled technique and enables high quality joining in a short time.
Also, gas pressure welding for heating and pressing the joint surface with gas (for example, Maruzen, Welding Handbook Revised 3rd Edition (1982) 6
(Page 09) can also be joined in a short time.

However, in these methods, it is necessary that the joint surfaces are in contact with each other with high accuracy as compared with welding and joining by screws. For example, if there is a misalignment of the joint surface called misalignment 8 shown in FIG. 2A, the joint area is reduced, and the quality is deteriorated due to insufficient strength or the like. Further, when the gap between the joining surfaces, which is called the gap 7 shown in FIG. 2B, is large, the brazing material is not sufficiently filled in the case of liquid phase diffusion joining, and the heating is nonuniform and excessively heated in the case of gas pressure welding. There is a problem that parts melt down. For this reason, various holders have been devised and used for butt-joining pipes or rods.

As shown in the perspective view of FIG. 3, a jig for holding and pressing the bonding material which is generally used for brazing is to fix the bonding material by passing the bonding materials 1A and 1B through a plurality of guide shafts 10A and 10B. A holding jig 9 is provided to hold the bonding material. Further, a pressing device 3 that moves along the guide shaft 10B is provided to press the bonding materials together. Most of the pressing devices 3 use pneumatic pressure or hydraulic pressure. Further, there is also a device having a function interlocking with the joint heating device 11 and capable of automatically pressing after the joint is heated to a predetermined temperature. As the heating of the joint, high (medium) frequency heating or the like is also used for liquid phase diffusion bonding or the like, and of course gas heating is gas heating in the case of gas pressure welding.

[0005]

Such a current bonding material holding and pressing device can smoothly and fairly accurately press a bonding material having a short length and a light weight. But,
Since many pipes or rods are usually long and have a warp or a bend, or the center of gravity is at the rear, it is not possible to secure sufficient contact accuracy of the joint surface applicable to pressure welding or liquid phase diffusion welding. In particular, the thicker the pipe and rod, the more difficult it is to ensure high contact accuracy, which is an obstacle to the practical application of new technologies for liquid phase diffusion welding and gas pressure welding.

In order to simply and butt-join tubes and rods with high quality, it is necessary to prepare a joint surface with high contact accuracy. Then, this invention aims at providing the method of simply obtaining the high contact precision of a butt joint surface.

[0007]

DISCLOSURE OF THE INVENTION The present invention is to solve the above problems, and in butt joining of metal pipes or rods, the joining materials are butt-held to each other while pressing the joining materials at three or more fulcrums. After that, by heating a part of one or both of the joining materials at the rear of the joining portion to 400 ° C. or more and 1250 ° C. or less, the butt joining is performed while improving the butt contact accuracy of the joining materials. ,
This is a butt-joining method for rods. To achieve this, 3
At one or more fulcrums, a joining material holding and fixing device that has a device that presses the joining materials independently by one or more of pneumatic, hydraulic, electric cylinder, spring, and bolts / nuts, and one or both Butt welding of metal pipes, characterized in that it has a heating device at the rear of the joining part for the joining material of No. 1, and at least one joining part heating device of heating pressure welding, brazing joining, liquid phase diffusion joining. It is a device.

[0008]

According to the present invention, when butt-joining is performed, a part of the jointing material is provided with a portion which is easily deformed, and the strain is absorbed there to obtain a high contact precision of the joint surface. FIG. 1 is a perspective view showing an example of the method and apparatus of the present invention. For butt joining of pipes or rods, it is necessary to butt the joining surfaces of the joining materials 1A, 1B with high precision, but the pipes or rods are usually long, and the pipes or rods themselves are bent or the installation location is bent. Matching without gaps is difficult. Therefore, the joining material is held and fixed by the holding and fixing device 2 having a pressing device (3A, 3B, and 3C in FIG. 1) that presses three or more fulcrums on the circumference of the pipe or rod with air pressure, hydraulic pressure, or the like. Then, a heating device (both 4A and 4B in FIG. 1) behind the joint is provided at a certain position behind one or both of the joints, and 400 ° C.
After heating to 1250 ° C. or less, the bonding material is pressed by the pressing devices 3A, 3B, and 3C of the holding and fixing device 2. After this,
Alternatively, at the same time as the heating of the rear portion of the joint portion, the joint portion is heated to a temperature according to the type of metal and the welding method by the joint portion heating device 5, and pressure welding or liquid phase diffusion joining is performed, whereby excellent joining can be performed.

In order to press the fulcrum of the pressing device in a well-balanced manner, it is necessary to control at least three pressing points independently. In FIG. 1, the number is 3A, 3B, and 3C, but it is preferable to increase the number depending on the size of the bonding material.
The pressing device preferably uses pneumatic pressure, hydraulic pressure (hydraulic pressure), an electric cylinder, or the like because a function of automatically pressing can be easily added by heating while being pressurized. Further, a spring or the like may be used, but the size of the joining material that can be applied is limited due to the size of the spring, the deformability, and the like. Also, although some labor is required, it is possible to tighten with bolts and nuts.

Further, the heating devices 4A and 4B at the rear of the joining portion are easy to work at a position 20 to 200 cm from the joining portion, depending on the size of the joining material. It is preferable because it can be integrated with. As for the heating method, gas heating or high frequency (medium frequency) heating is easy (in FIG. 1, 4A shows a gas heating apparatus and 4B shows a high frequency heating apparatus). The heating temperature is preferably a high temperature within the range where the material of the bonding material does not deteriorate, and is 400 ° C or higher 12
It is 50 ° C or lower. At temperatures lower than 400 ° C, sufficient deformation is still difficult. On the other hand, if the temperature exceeds 1250 ° C, the quality of the bonding material is greatly changed, or the oxidation is large, which is not preferable. Further, it is preferable to heat the entire circumference, but it is also possible to heat at a part of the position that requires the most deformation. That is, FIG.
In the case where there is a gap as shown in (b), the upper side of the drawing is heated so that it is easily stretched and deformed, so that it is possible to abut with high accuracy without moving the entire bonding material. Further, even in case of misalignment, the portion is softened by heating, and the distortion is absorbed there, so that the butt precision can be improved.

As described above, the heating at the rear of the joint may be the heating of only one tube or rod. Even if one side is fixed, if the other side is easily deformed, the butt contact accuracy of the joint surfaces can be improved. Further, it is not necessary that both heating methods are the same, and it is possible to combine one with high frequency heating and the other with gas heating.

The application of the present invention can be sufficiently exerted in a pipe or bar mainly composed of iron such as a steel pipe, a reinforcing bar or a stainless pipe. Further, it is highly effective for thick ones having a diameter exceeding 40 mm. Steel pipes or copper pipes having a small diameter are light or easily deformed, so that the butt contact accuracy can be improved without heating, and thus the effect is small.

The present invention can be applied not only to brazing joining, liquid phase diffusion joining and gas pressure joining, but also to butt joining such as flash butt welding. Flash butt welding is a method in which an arc is generated between the joining materials, the joining surfaces are melted, and this is pressed and joined, but in order to stably generate the arc, the joining materials are held at regular intervals and After melting, it is necessary to press uniformly. By applying the present invention to this, it becomes possible to hold the bonding materials at a constant interval and press them uniformly. That is, by providing a fixed interval and holding the bonding material and heating the rear part of the bonding part,
Deformation becomes easier, and it becomes easier to ensure the uniformity of the spacing between the bonding materials, and the rigidity of the bonding material also decreases when pressing,
This is because it can be easily pressed.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to FIGS. FIG. 1 shows an example of the present invention for liquid phase diffusion bonding of steel pipes. The joining materials 1A and 1B are butt-held by the joining material holding and fixing device 2 having hydraulic pressing devices 3A, 3B and 3C on three fulcrums 6A, 6B and 6C, respectively. At this time, a Ni-based brazing material is previously installed between the joint surfaces. Then, a part of the rear of the joint was heated to about 700 ° C. by a heating device 4B behind the joint by high frequency and a heating device 4A behind the joint by gas. The heating facilitated the deformation of this part, and the joint surfaces could be butted with high precision. Then, the joint surface was heated to 1250 ° C. by the joint heating device 5 using high frequency and joined. Then, a tensile test was carried out with the tube as it was. The joint was sound and ruptured at a position apart from the joint.

FIG. 3 shows a tubing and butt braze joint of the tubes of the comparative example. The difference from the example of the invention was that the rear of the joint was not heated and the pressing was performed at one place. The kind of the bonding material or the brazing material, the heating temperature, the pressing force, etc. were the same as those of the invention examples.
After joining, a tensile test was carried out in the same manner as the invention example. As a result, when the fractured surface was broken at the joint portion and the fractured surface was observed, about 10% of the entire fractured surface was observed where the brazing material was not uniformly dispersed. The results of these examples are summarized in Table 1.

[0016]

[Table 1]

[0017]

In butt joints such as gas pressure welding or liquid phase diffusion welding of steel pipes or rebars, the butt contact accuracy of the joint surface is important for improving the quality of the joint. In particular, the larger the diameter, the lower the butt accuracy and the fact that uniform heating cannot be performed, resulting in a deterioration in quality. Therefore, by using the present invention, it is possible to easily improve the butt contact accuracy and improve the quality of the joint portion.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a butt joining method and device according to the present invention.

2A and 2B are diagrams showing the concept of misalignment and gap in butt joining, where FIG. 2A is a misalignment and FIG. 2B is a gap.

FIG. 3 is a perspective view showing a conventional butt joining method.

[Explanation of symbols]

 1A, 1B Joining material 2 Holding and fixing device 3, 3A, 3B, 3C Pressing device 4A, 4B Heating device behind the joining part 5 Joining part heating device 6 Support point 7 Gap 8 Difference

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B23K 20/00 340

Claims (2)

[Claims] 1. In butt joining of metal pipes or rods, the joining materials are butt-held to each other while pressing the joining materials against each other at three or more fulcrums, and then a portion of one or both of the joining materials at the rear part of the joining portion is 400 A butt-joining method for metal pipes and rods, characterized in that butt-joining is performed while heating at a temperature of not less than 1 ° C and not more than 1250 ° C while improving the butt-contact accuracy of the joining material. 2. At three or more fulcrums, pneumatic pressure, hydraulic pressure,
A joining material holding and fixing device having a device that presses the joining materials independently by one or more of an electric cylinder, a spring, a bolt and a nut, and a heating device behind the joining portion for one or both joining materials, A butt-joining device for metal pipes and rods, which comprises one or more types of heating devices for joining portions, which are one of heating pressure welding, brazing joining, and liquid phase diffusion joining.