Electric heating – Inductive heating – Metal working
Reexamination Certificate
1999-08-24
2001-07-17
Hoang, Tu Ba (Department: 3742)
Electric heating
Inductive heating
Metal working
C219S612000, C219S614000, C219S633000, C219S643000, C228S044500
Reexamination Certificate
active
06262403
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a diffusion bonding method and a diffusion bonding apparatus. To be more specific, it relates to a diffusion bonding method and a diffusion bonding apparatus which do not require intricate work to adjust both materials to be bonded when setting them in the diffusion bonding apparatus.
BACKGROUND ART
A diffusion bonding method has been known as one of the methods for bonding metallic materials. When bonding metals by this method, because the surface roughness of materials to be bonded significantly affects the joint efficiency, the ends of the materials are generally cut or ground to achieve a desired roughness before the materials are set in the diffusion bonding apparatus for diffusion bonding.
In this general procedure, materials to be bonded are set in a diffusion bonding apparatus without adjusting the ends of the materials to face parallel to each other, assuming that a proper contact is obtained at the ends of the material to be bonded by creep caused by pressure and heat applied thereto prior to bonding.
However, a study made by the inventors of the present invention has discovered that when bonding tubes or pipes by this generally employed method of diffusion bonding, joint efficiency drops because some parts may not contact each other under a desired pressure depending on a certain degree of parallel of materials to be bonded.
Therefore, when bonding tubes or pipes through this generally employed diffusion bonding method, it is essential to adjust the ends of the materials to be bonded to face parallel to each other before setting the materials in a diffusion bonding apparatus. However, because most pieces of tube or pipe to be bonded are long, the adjustment is troublesome and time-consuming.
However, most products manufactured by diffusion bonding are relatively small, and it is impossible to employ a prior art diffusion bonding apparatus in the manufacture of extensively long pieces such as oil-well pipes which extend several kilometers.
Therefore, the arrival of a diffusion bonding apparatus suitable to the manufacture of extensively long pieces is much awaited by manufacturers of extensively long pipes such as oil-well pipes.
Another problem of a prior art diffusion bonding apparatus is that when bonding metallic materials by the prior art diffusion bonding apparatus, a difference may occur in the joint of the two materials as shown in
FIG. 46
(
a
) . Marks T
1
and T
2
in
FIG. 46
represent materials which are bonded.
Subsequently, when a difference occurs, it remarkably weakens the strength, especially the fatigue strength, of the joint. Consequently, when such a difference occurs, it is usually corrected by forming a taper a and b at the joint, as shown in
FIG. 46
(
b
), by applying cutting or grinding finishing thereto.
However, correction in such a way may lead to a drop in the work efficiency at diffusion bonding since the correction work is troublesome, because the work is carried out for a materials which becomes much longer after being bonded.
Furthermore, induction heating has usually used a heating coil c as shown in
FIG. 47
in which the material T to be heated is inserted, heated and then pulled out.
However, when heating an extensively long piece such as a pipe, insertion and extraction of the material T in and out of the heating coil c takes much time because of its long length, thus impairing the productivity.
Furthermore, in diffusion bonding, it is the conventionally employed method that a bonding part j is covered with a gas jacket d as shown in
FIG. 48
in order to prevent the oxidation of the bonding part j. Because of a gap created between the gas jacket d and materials T and T, inert gas (herein after called shielding gas) is supplied to the gas jacket d from a nozzle e to prevent air from going into the gas jacket d, and the bonding part j is bonded while being shielded. In other words, with the shielding gas leaking out of the gap between the gas jacket d and the materials T and T, air is prevented from going into the gas jacket d while materials are being bonded. In
FIG. 48
, the mark c represents a high frequency heating coil.
However, when the materials are bonded while letting the shielding gas go out in the above manner, it creates a flow of gas inside the gas jacket d cooling the circumference of the bonding part j. As a result, the bonding part is not sufficiently heated causing unsatisfactory quality and strength in joints.
The present invention is made to resolve the above-mentioned disadvantages of the prior arts.
Namely, it is an object of the present invention to provide a diffusion bonding method and a diffusion bonding apparatus that will facilitate the setting of the materials in a diffusion bonding apparatus when bonding long pieces of tubes or pipes.
It is another object of the present invention to provide a diffusion bonding apparatus which is applied to manufacture of extensively long pipes such as oil-well pipes which extend several kilometers.
It is another object of the present invention to provide a method and an apparatus for adjusting position of materials to be bonded by diffusion bonding so that a difference in the joint is prevented.
It is another object of the present invention to provide a heating coil to heat speedily an extensively long piece such as a pipe.
It is another object of the present invention to provide a shielding device and the shielding method for a bonding part in diffusion bonding which do not cause the degradation in quality and strength in joints.
SUMMARY OF THE INVENTION
The first aspect of the present invention is a diffusion bonding method which comprises a step of adjusting the ends of materials to be bonded before bonding after they are set in a diffusion bonding apparatus.
In the diffusion bonding method under of the first aspect of the present invention, the ends of the materials to be bonded are finished to face parallel to each other as desired at the time of the above-mentioned adjustment.
The second aspect of the present invention is a diffusion bonding apparatus which comprises a finishing means to finish the ends of the materials so that they face parallel to each other in the diffusion bonding apparatus.
To be specific, the diffusion bonding apparatus of the second aspect of the present invention comprises a finishing means comprising a machining means which is symmetrically placed between two materials to be bonded, a first driving mechanism to move said machining means forward and backward for the materials to be bonded and a second driving mechanism to move said first driving mechanism sideways; or a first driving mechanism to move said machining means sideways and a second driving mechanism to move the first driving mechanism forward and backward for the materials to be bonded; a bed; a fixed clamp and a mobile clamp which are placed on the bed facing to each other; and a driving means to move said mobile clamp.
Since the first and second aspects of the present invention is comprised in the above way, upon completion of finishing the ends of the materials, the ends of the materials to be bonded can face parallel to each other as desired. Consequently, there will be no need to adjust the ends of the materials in order for them to face parallel to each other when setting the materials in the diffusion bonding apparatus, facilitating an easy and quick setting of the materials in the diffusion bonding apparatus.
The third aspect of the present invention is a diffusion bonding apparatus comprising a material feeding section and a material discharge section installed in that order, through which material to be bonded are fed from upstream side and bonded materials are discharged toward downstream side wherein said material feeding section has a mechanism to move the material to be bonded to a place where its end is bonded with the other, and to pressurize the bonding part of the materials; and said material discharging section has a mechanism to clamp the material to be bonded. Here, a material to be bonded is fed and d
Shimizu Takao
Suzuki Hiroaki
Tsuchiya Masaki
Arent Fox Kintner & Plotkin & Kahn, PLLC
Daido Tokushuko Kabushiki Kaisha
Hoang Tu Ba
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