JP2013160246A - Method and apparatus for brazing pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for brazing a pipe which neither requires a nitrogen gas, an antioxidant, and an antioxidant joint nor decreases a strength of the pipe and to provide an apparatus as well.SOLUTION: A large diameter processed end 101c of a first copper pipe 101 is fitted into a first engaging portion 10b formed on a brazing apparatus 1 and one end in an axial direction of a second copper pipe 102 is fitted into a second engaging portion 10c, a predetermined gap S is formed between an end face 101b of the large diameter processed end 101c and an end face 102b of one end in the axial direction of the second copper pipe 102, an exhaust gas G from an outside burner 20 flows in the gap S via a gas flow path 5c, the exhaust gas G is further introduced into the respective copper pipes 101 and 102, one end in the axial direction of the second copper pipe 102 is fitted into the inner circumferential surface 101d of the large diameter processed end 101c to separate from the copper pipes 101 and 102, portions in which the large diameter processed end 101c and one end of the second copper pipe 102 are fitted are brazed, and the copper pipe 101 and copper pipe 102 are connected.

Description

  The present invention relates to a brazing method and apparatus for piping that does not require nitrogen gas, secondary materials such as antioxidants and antioxidant joints, and does not reduce the strength of the piping.

  Conventionally, as a method for brazing a copper pipe, a technique using nitrogen substitution, an antioxidant, and an antioxidant joint is known. Brazing is a kind of welding that is a method of joining metals, by melting an alloy having a melting point lower than the member to be joined (base material) and using it as a kind of adhesive, without melting the base material, A plurality of metal members are joined.

  FIG. 7 shows an example of a conventional brazing method. FIG. 7A shows a state before the copper tube 101 and the copper tube 102 are brazed. At one end in the axial direction of the copper tube 101, a large-diameter processed end 101c bulging outward in the radial direction is formed. The large-diameter processed end 101c is formed by enlarging the axial end of the copper tube 101 with respect to the outer surface 101a with a dedicated tool. The large-diameter processed end portion 101c is formed with an inner peripheral surface 101d into which one end portion in the axial direction of the copper tube 102 can be fitted. The outer surface 102a of the copper tube 102 can be fitted into the inner peripheral surface 101d. The copper tube 102 is inserted from the end surface 101b side of the copper tube 101, and is inserted into the large-diameter processed end portion 101c until the axial end surface 102b contacts the deep end of the large-diameter processed end portion 101c.

  FIG. 7B shows a state where the copper tube 101 and the copper tube 102 are brazed. In this state, the insertion portion between the copper tube 101 and the copper tube 102 is heated by the flame B from the burner 20, and the brazing material 21 is supplied to the insertion portion. As a result, the molten brazing material spreads over the joining surface, and the copper tube 101 and the copper tube 102 are joined.

  Conventionally, a pipe connection method is known as a prior art related to brazing (see, for example, Patent Document 1). The pipe connection method disclosed in Patent Document 1 is a technique for brazing after introducing exhaust gas from a burner into two pipes to be connected.

Japanese Patent No. 4317568

  However, brazing using the above-described nitrogen substitution, antioxidant, and antioxidant joint has the following problems. Brazing using nitrogen substitution increases the amount of work associated with the movement and installation of the nitrogen cylinder and complicates safety management and the like. In addition, the amount of nitrogen consumed due to repeated discharge and filling of nitrogen gas increases, and the brazing cost increases. Brazing using an antioxidant has a problem that the preheating time of the piping changes depending on the ambient temperature, and the vaporization state of the antioxidant changes accordingly, and an oxide film is formed. Furthermore, the effect of the antioxidant varies depending on the diameter of the pipe, and there is a problem that it is difficult to manage the brazing operation. In addition, brazing using an antioxidant joint uses exhaust gas, and the amount of work is small. However, since the work is performed by adding a joint, the number of brazing points increases, resulting in an increase in the amount of work. There is.

  In the pipe connection method of Patent Document 1 described above, it is necessary to close the exhaust gas introduction hole by brazing. Further, since a hole for introducing exhaust gas has to be formed, there is a problem that the strength of the pipe is lowered.

  Accordingly, an object of the present invention is to provide a method and an apparatus for brazing a pipe that does not require nitrogen gas, secondary materials such as an antioxidant and an antioxidant joint, and does not reduce the strength of the pipe.

  In order to achieve the above object, the invention described in claim 1 is characterized in that one end of the second pipe in the axial direction is provided on the inner peripheral surface of the large-diameter machining end formed at one end of the first pipe in the axial direction. And a brazing method for a pipe for brazing the fitting portion between the first pipe and the second pipe, wherein the first fitting part formed in the brazing device is the first fitting part. The large-diameter machining end of the pipe is fitted, and one end of the second pipe in the axial direction is fitted into a second fitting part formed in the brazing device, and the large-diameter machining end of the large-diameter machining end is A first step of forming a predetermined gap between an end surface and an end surface of one end portion in the axial direction of the second pipe, and an external burner through a gas flow path formed in the brazing device. Exhaust gas is allowed to flow into the gap, and the exhaust gas of the burner that has flowed into the gap is A second step of introducing into the pipe, a third step of fitting one end portion in the axial direction of the second pipe into the inner peripheral surface of the large-diameter machining end portion, and the brazing device as the first step. A fourth step of separating from the pipe and the second pipe, and fitting of the large-diameter machining end and one end of the second pipe in a state where the brazing device is detached from the pipes; A pipe brazing method comprising: a fifth step of brazing a portion to connect the first pipe and the second pipe.

  According to this invention, the exhaust gas from the external burner is passed through the gas flow path of the brazing device, and the end surface of the large-diameter machining end of the first pipe and the end face of the axial end of the second pipe It is possible to introduce the exhaust gas of the burner into each pipe without providing a hole for introducing the exhaust gas in the pipe.

  According to a second aspect of the present invention, the axial end of the second pipe is fitted into the inner peripheral surface of the large-diameter processed end formed at the axial end of the first pipe, and the first pipe A pipe brazing device for brazing the fitting part between one pipe and the second pipe, wherein the first fitting part is capable of fitting the large-diameter processed end of the first pipe. A holding portion having a first fitting portion, a second fitting portion formed in the holding portion, into which one end portion of the second pipe in the axial direction can be fitted, and the holding portion, the fitting portion being fitted into the first fitting portion. A first stopper for restricting movement of the first pipe in the axial direction by contact with the end surface of the large-diameter processed end, and the second fitting. Movement of the second pipe in the axial direction by contact with the end face of one end in the axial direction of the second pipe fitted into the part Between the end surface of the large-diameter machining end of the first pipe and the end face of the one end of the second pipe in the axial direction in a state in which the movement in the axial direction is restricted by the first stopper A pipe brazing comprising: a second stopper for forming a predetermined gap in the gas passage; and a gas flow path formed on the holding portion side for allowing exhaust gas from an external burner to flow into the gap. Device.

  According to a third aspect of the present invention, in the pipe brazing device according to the second aspect, the gas flow path is held on the holding portion side so as to be movable in a direction perpendicular to the axial direction of the second pipe. The second stopper is formed in the second stopper.

  According to a fourth aspect of the present invention, in the pipe brazing device according to the second or third aspect, the holding portion is formed so as to be divided in the circumferential direction, and each divided holding portion has a connecting means. It is characterized by being connectable via.

  According to the first and second aspects of the present invention, the exhaust gas from the external burner is passed between the end surface of the large-diameter machining end of the first pipe and the end face of the one end in the axial direction of the second pipe. Since the exhaust gas of the burner that has flowed into the gap is introduced into each pipe, it is not necessary to provide a hole for introducing the exhaust gas into the pipe as in the prior art. . Thereby, the 1st piping and the 2nd piping can be joined, without reducing the intensity of piping. In addition, since the air inside the first pipe and the second pipe can be replaced with the exhaust gas of the burner, secondary materials such as conventional nitrogen gas, antioxidants, and antioxidant joints can be used. This is not necessary, and the brazing cost can be reduced.

  According to the third aspect of the present invention, since the gas flow path is formed in the second stopper, the gap forming operation and the exhaust gas inflow preparation operation can be performed at the same time. Work efficiency can be increased.

  According to the fourth aspect of the present invention, since the holding portion is formed so as to be divided in the circumferential direction, the holding portion can be easily attached and detached from the first pipe and the second pipe, and the workability of brazing is improved. Can be increased.

It is process drawing which shows the procedure of the brazing method of piping concerning Embodiment 1 of this invention. FIG. 5 is a cross-sectional view illustrating a state where the second stopper is raised in the pipe brazing apparatus according to the first embodiment of the present invention. It is sectional drawing which shows the state which lowered | hung the 2nd stopper in the brazing apparatus of the piping of FIG. It is a perspective view which shows the whole piping brazing apparatus of FIG. It is a piping brazing apparatus concerning Embodiment 2 of this invention, and is sectional drawing which shows the state which raised the 2nd stopper. It is sectional drawing which shows the state which lowered | hung the 2nd stopper in the brazing apparatus of piping of FIG. It is process drawing which shows the procedure of the brazing method of the piping in the past.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
1 to 4 show Embodiment 1 of the present invention, and particularly show a case where it is applied to brazing a copper pipe as a pipe. As shown in FIG. 1A, the first copper tube 101 and the second copper tube 102 are both made of a copper alloy and have the same diameter. At one end in the axial direction of the first copper tube 101, a large-diameter processed end 101c bulging outward in the radial direction is formed. The large-diameter processed end 101c is formed by enlarging the axial end of the first copper tube 101 with respect to the outer surface 101a with a dedicated tool (not shown). An inner peripheral surface 101d into which one end of the second copper tube 102 in the axial direction can be fitted is formed inside the large-diameter processed end 101c. The outer surface 102a of the second copper tube 102 can be fitted into the inner peripheral surface 101d of the large-diameter processed end 101c. As will be described later, when the first copper tube 101 and the second copper tube 102 are brazed, the second copper tube 102 is fitted from the end surface 101b side of the first copper tube 101, and the shaft The end face 102b in the direction is fitted into the large-diameter machining end 101c until it comes into contact with the back end of the large-diameter machining end 101c.

  2 to 4 show the brazing device 1 for connecting the first copper tube 101 and the second copper tube 102. As shown in FIG. 4, the brazing device 1 has a holding portion 2 formed in a substantially cylindrical shape. The holding part 2 is made of metal, is divided into two in the circumferential direction, and includes a first holding part 3a and a second holding part 3b made of a metal member. One end in the circumferential direction of the first holding part 3a and the second holding part 3b is connected via a hinge (hinge) 7 as connecting means. A lock portion 8 is provided at the other end of the first holding portion 3a and the second holding portion 3b. The lock unit 8 closely contacts the circumferential end of the first holding unit 3a and the circumferential end of the second holding unit 3b at the time of locking, and the first holding unit 3a and the second holding unit at the time of unlocking. It may be anything as long as it has a function of connecting 3b with the hinge 7 so as to be expandable, and may be a band, for example. In a state where the lock portion 8 is unlocked, the first holding portion 3a and the second holding portion 3b are opened around the hinge 7, and are attached to the first copper tube 101 and the second copper tube 102. And withdrawal is possible.

  The holding portion 2 is formed with a fitting hole 10 into which the first copper tube 101 and the second copper tube 102 can be fitted. Here, the insertion means that the two members are fitted with almost no gap. The insertion hole 10 includes an outer insertion portion 10a, a first insertion portion 10b, and a second insertion portion 10c. The outer insertion portion 10a is located at one end of the insertion hole 10 in the axial direction, and a portion of the first copper tube 101 other than the large-diameter processed end portion 101c of the outer peripheral surface 101a can be inserted. The first fitting portion 10b is continuous with the outer fitting portion 10a, and the large-diameter processed end portion 101c of the first copper tube 101 can be fitted therein. The 2nd insertion part 10c is continued with the 1st insertion part 10b, and the one end part of the axial direction of the 2nd copper pipe 102 can be inserted.

  The holding portion 2 is formed with a first stopper 10d that restricts the axial movement of the first pipe 101 fitted into the first fitting portion 10b. 10 d of 1st stoppers are formed using the level | step difference surface of the 1st insertion part 10b and the 2nd insertion part 10c. That is, since the inner diameter of the second insertion portion 10c is smaller than the inner diameter of the first insertion portion 10b, there is a step surface between the first insertion portion 10b and the second insertion portion 10c. It is formed. Thereby, the end surface 101 of the large-diameter processed end portion 101c abuts on the first stopper 10d formed of a stepped surface located between the first insertion portion 10b and the second insertion portion 10c, and the first pipe The movement of 101 in the axial direction is restricted.

  As shown in FIG. 4, a stopper holding portion 4 is provided on the outer surface of the second holding portion 3 b in the holding portion 2. The stopper holding part 4 is formed in a quadrangular prism shape and extends in a direction orthogonal to the axis of the insertion hole 10. One end of the stopper holding part 4 is joined to the first holding part 3b by welding. A second stopper 5 is provided on the stopper holding portion 4 and the second holding portion 3b so as to be movable (slidable) in the vertical direction. One end portion 5b of the second stopper 5 can project into the insertion hole 10 from the inner surface of the second insertion portion 10c. The second stopper 5 protrudes from the inner surface of the second insertion portion 10c into the insertion hole 10, and the outer edge of the outer surface 5a on the first insertion portion side is in the same position as the position of the first stopper 10d. Is set to The outer edge may slightly recede from the stopper 10d toward the second copper tube 102 side.

  A locking plate 6 that restricts the axial movement of the second stopper 5 is attached to the outer surface 5 a of the second stopper 5. The locking plate 6 is located outside the holding portion 2 and can come into contact with the end portion of the stopper holding portion 4. As shown in FIG. 3, the second stopper 5 has one end portion 5 b from the inner surface of the second insertion portion 10 c in the insertion portion 10 in a state where the locking plate 6 is in contact with the end portion of the stopper holding portion 4. To protrude. In this state, the second stopper 5 is in contact with the end surface 102b of the one end portion in the axial direction of the second copper tube 102 fitted in the second fitting portion 10c, whereby the shaft of the second copper tube 102 is The movement of the direction is regulated.

  As shown in FIGS. 1 and 3, the end surface 101b of the large-diameter processed end portion 101c of the first copper tube 101 is in contact with the first stopper 10d, and the end surface of one end portion in the axial direction of the second copper tube 102 In a state where 102b is in contact with the outer surface 5a of the second stopper 5, there is a predetermined gap between the end surface 101b of the large-diameter processed end portion 101c and the end surface 102b of one end portion in the axial direction of the second copper tube 102. A gap S is formed. The gap S has a function of introducing the exhaust gas G of the burner 20 into the copper tubes 101 and 102, as will be described later. This gap S can be changed by changing the outer diameter D of the second stopper 5.

  The second stopper 5 is made of, for example, a steel pipe. In the second stopper 5, a gas flow path 5 c that communicates one end portion and the other end portion in the axial direction is formed. The gas flow path 5c has a function of causing the exhaust gas G from the burner 20 disposed outside the holding unit 2 to flow into the gap S as shown in FIG. That is, in the first embodiment, the exhaust gas G from the burner 20 flows into the gap S through the gas flow path 5c in the second stopper 5, and the exhaust gas G that has flowed into the gap S is respectively The first copper tube 101 and the second copper tube 102 are introduced.

  Next, a copper tube brazing method and operation using the brazing apparatus 1 shown in FIGS. 2 and 3 will be described.

  As shown to Fig.1 (a), the 1st copper tube 101 and the 2nd copper tube 102 are first arrange | positioned facing each other. In this state, the other end of the first copper tube 101 and the other end of the second copper tube 102 are closed by a plug (not shown) having a predetermined hole. Thereby, the exhaust gas G is introduced into the first copper tube 101 and the second copper tube 102 while suppressing the introduction of outside air into the first copper tube 101 and the second copper tube 102. It can be introduced. Next, the lock portion 8 in the holding portion 2 of the brazing device 1 shown in FIG. 4 is released, and the surface where the first holding portion 3a and the second holding portion 3b are in contact with each other is expanded with the hinge 7 as the center. The split type holding unit 2 is opened. In this state, the holding portion 2 is attached to the first copper tube 101 and the second copper tube 102, and the lock portion 8 is locked by closing the first holding portion 3a and the second holding portion 3b.

  FIG. 1B shows a state in which the holding unit 2 is mounted on the first copper tube 101 and the second copper tube 102. In this state, the large-diameter processed end portion 101c of the first copper tube 101 is fitted into the first fitting portion 10b of the holding portion 2, and the large-diameter processed end of the first copper tube 101 is in the state. The outer surface 101a excluding the part 101c is in a state of being fitted into the outer fitting part 10a of the holding part 2. In this state, the end surface 101b of the large-diameter processed end portion 101c of the first copper tube 101 comes into contact with the first stopper 10d, and the movement of the first copper tube 101 in the axial direction is restricted. In this state, the second stopper 5 is retracted outward from the inner surface of the second insertion portion 10c as shown in FIG.

  FIG. 1C shows a state in which the second stopper 5 is moved in the direction of the arrow F1 as shown in FIG. 1B, and the second stopper 5 is projected from the inner surface of the second fitting portion 10c. ing. As shown in FIGS. 1C and 3, in this state, when the second copper tube 102 is moved to the arrow F <b> 2, the end surface 102 b at one end portion in the axial direction of the second copper tube 102 becomes the second Abutting on the outer surface 5a of the stopper 5, the movement of the second copper tube 102 in the axial direction is restricted. In this state, a gap S having a predetermined length in the axial direction is formed between the end surface 101b of the large-diameter processed end portion 101c and the end surface 102b of one end portion of the second copper tube 102 in the axial direction.

  Next, as shown in FIG. 1D, the exhaust gas G from the external burner 20 is caused to flow into the gap S through the gas flow path 5 c in the second stopper 5 with the gap S formed. . That is, by directing the tip of the flame B of the burner 20 toward the upstream end of the gas flow path 5c in the second stopper 5, the exhaust gas G from the burner 20 smoothly enters the gas flow path 5c, It moves toward the gap S. The exhaust gas G flowing into the gap S is introduced into the first copper pipe 101 and the second copper pipe 102. That is, the axial ends of the first copper tube 101 and the second copper tube 102 are hardly blocked by the first stopper 10d and the second stopper 5, and have a sufficient opening area. Therefore, the exhaust gas G that has flowed into the gap S quickly diverts to the left and right and is smoothly introduced into the first copper tube 101 and the second copper tube 102. In this state, since the air in the first copper tube 101 and the second copper tube 102 can be replaced with the exhaust gas G of the burner, the nitrogen gas and the antioxidant are used as in the conventional brazing operation. No auxiliary materials such as antioxidation joints are required

  FIG. 1E shows a state in which the second stopper 5 is retracted. In this state, by moving the second stopper 5 in the direction of arrow F3, the second stopper 5 moves backward from the inner surface of the second fitting portion 10c, and the second copper tube 102 moves in the axial direction (first 1 movement toward the copper tube 101 side). Next, as shown in FIG. 1 (f), the second copper tube 102 is pressed in the direction of arrow F4, and one end in the axial direction of the second copper tube 102 is pressed against the inner peripheral surface 101d of the large-diameter processed end 101c. Insert the part. As a result, the end surface 102b at one end in the axial direction of the second copper tube 102 enters the inner peripheral surface 101d from the end surface 101b of the large-diameter processed end 101c of the first copper tube 101, and the inner peripheral surface 101d Abuts the end. In this state, the outer surface 102a of the second copper tube 102 is fitted into the inner peripheral surface 101d of the large-diameter processed end portion 101c, and the brazing operation can be prepared.

  Next, when the second copper tube 102 is inserted into the inner peripheral surface 101d of the large-diameter processed end 101c, the brazing device 1 is detached from the first copper tube 101 and the second copper tube 102. That is, when the lock portion 8 of the holding portion 2 is released, the holding portion 2 is opened via the hinge 7, and the brazing device 1 from the first copper tube 101 and the second copper tube 102. Can be removed.

  FIG. 1G shows that after the brazing device 1 is detached from the copper tubes 101 and 102, the fitting portion between the large-diameter processed end portion 101c and one end portion in the axial direction of the second copper tube 102 is brazed. It shows the state to do. In this state, the insertion portion is heated by the flame B from the burner 20, and the brazing material 21 is supplied to the insertion portion. As a result, the molten brazing material reaches the joint surface, and the connection between the first copper tube 101 and the second copper tube 102 is performed.

  As described above, the exhaust gas G from the external burner 20 is interposed between the end surface 101b of the large-diameter processed end portion 101c of the first copper tube 101 and the end surface 102b of one end portion of the second copper tube 102 in the axial direction. Since the exhaust gas G of the burner 20 that has flowed into the formed gap S is introduced into the copper pipes 101 and 102, the exhaust gas is introduced into a pipe as in the prior art. There is no need to provide a hole. Thereby, the 1st copper pipe 101 and the 2nd copper pipe 102 can be connected, without reducing the intensity | strength of a copper pipe. In addition, since the air inside the first copper tube 101 and the second copper tube 102 can be replaced with the exhaust gas G of the burner 20, a nitrogen gas, an antioxidant, and an antioxidant as in the conventional nitrogen replacement are used. A secondary material such as a joint is not required, and the cost of the brazing operation can be reduced.

  Further, since the gas flow path 5c is formed in the second stopper 5, the formation work of the gap S and the inflow preparation work of the exhaust gas G can be performed at the same time, thereby improving the brazing work efficiency. Can do. Further, since the holding portion 2 is formed so as to be divided in the circumferential direction, the holding portion 2 can be easily attached to and detached from the first copper tube 101 and the second copper tube 102, and the brazing workability can be improved. it can.

(Embodiment 2)
5 and 6 show Embodiment 2 of the present invention. The difference between the second embodiment and the first embodiment is only the structure of the holding unit 2, and the other parts conform to the first embodiment. Therefore, the same reference numerals as those of the first embodiment are given to the conforming parts. The description of the conforming part is omitted.

  As shown in FIGS. 5 and 6, in the first embodiment, the holding portion 2 is structured to be divided in the circumferential direction, but in the second embodiment, the holding portion 2 has an integral structure. The holding part 2 has the 1st insertion part 10b and the 2nd insertion part 10c, and the outer side insertion part 10a employ | adopted in Embodiment 1 is not formed. That is, in Embodiment 2, it is possible to attach the holding unit 2 to the first copper tube 101 and the second copper tube 102 without dividing the holding unit 2 in the circumferential direction.

  In Embodiment 2 configured as described above, the first copper tube 101 can be fitted into the first fitting portion 10b from one side of the holding portion 2, and similarly, the first copper tube 101 can be fitted from the other side of the holding portion 2. Two copper tubes 102 can be fitted into the second fitting portion 10c. Therefore, the gap S can be formed without making the holding portion 2 into a divided structure, and the brazing device 1 can be simplified. Then, after the second copper tube 102 is fitted into the inner peripheral surface 101d of the large-diameter processed end 101c, when the brazing device 1 is removed, the brazing device 1 is moved to the second copper tube 102 side. What is necessary is just to move to a part. In addition, even if it is a case where the holding | maintenance part 2 is made into a divided structure like Embodiment 1, it is good also as a structure which does not form the outer insertion part 10a.

  The embodiment of the present invention has been described in detail above, but the specific configuration is not limited to the above-described embodiment, and even if there is a design change or the like without departing from the gist of the present invention, It is included in this invention. For example, in this embodiment, the present invention is applied to the connection between copper tubes, but the piping is not limited to a copper tube, and can be applied to the connection of a piping made of a material other than a copper alloy. Moreover, although the holding | maintenance part 2 was comprised from the metal member, as long as it is a material which has heat resistance, it is good also as a structure which uses members, such as a ceramic.

  Further, as described above, the large-diameter processed end 101c is formed by expanding the end of the copper tube in the axial direction with a dedicated tool. However, the diameter is not limited to the case where the end is expanded in advance. It may be done. Further, for example, the present invention can be applied even when a joint including an elbow or a branch pipe is connected.

DESCRIPTION OF SYMBOLS 1 Brazing apparatus 2 Holding part 3a 1st holding part (holding part)
3b Second holding part (holding part)
4 stopper holding portion 5 second stopper 5c gas flow path 6 locking plate 10 fitting hole 10a outer fitting portion 10b first fitting portion 10c second fitting portion 10d first stopper 20 burner 21 brazing material 101 first Copper pipe (first pipe)
102 First copper pipe (second pipe)
S Gap G Exhaust gas

Claims (4)

One end of the second pipe in the axial direction is fitted into the inner peripheral surface of the large-diameter processed end formed at one end in the axial direction of the first pipe, and the first pipe and the second pipe A pipe brazing method for brazing the fitting portion.
The large-diameter processed end portion of the first pipe is fitted into a first fitting portion formed in the brazing device, and the second pipe is inserted into a second fitting portion formed in the brazing device. A first step of inserting one end portion in the axial direction and forming a predetermined gap between an end surface of the large-diameter processed end portion and an end surface of the one end portion in the axial direction of the second pipe;
A second step of introducing exhaust gas from an external burner into the gap through a gas flow path formed in the brazing device, and introducing the exhaust gas of the burner that has flowed into the gap into the pipes; When,
A third step of fitting one end of the second pipe in the axial direction on the inner peripheral surface of the large-diameter end;
A fourth step of separating the brazing device from the first pipe and the second pipe;
In a state where the brazing device is detached from each of the pipes, the fitting portion between the large-diameter processed end and the one end of the second pipe is brazed, and the first pipe and the second pipe A fifth step of connecting
A method for brazing a pipe, characterized by comprising: One end of the second pipe in the axial direction is fitted into the inner peripheral surface of the large-diameter processed end formed at one end in the axial direction of the first pipe, and the first pipe and the second pipe A brazing device for piping for brazing the fitting portion with
A holding portion having a first fitting portion into which the large-diameter machining end of the first pipe can be fitted;
A second fitting portion formed in the holding portion and capable of fitting one end portion in the axial direction of the second pipe;
A first stopper that is provided in the holding portion and regulates the movement of the first pipe in the axial direction by contact with an end surface of the large-diameter machining end portion fitted in the first insertion portion;
The movement of the second pipe in the axial direction is made possible by contact with the end face of one end in the axial direction of the second pipe that is movably provided on the holding part side and is fitted in the second fitting part. Between the end surface of the large-diameter machining end of the first pipe and the end face of the one end of the second pipe in the axial direction in a state in which the movement in the axial direction is restricted by the first stopper A second stopper for forming a predetermined gap in
A gas flow path that is formed on the holding portion side and allows exhaust gas from an external burner to flow into the gap;
A brazing device for piping, comprising:   The said gas flow path is formed in the said 2nd stopper hold | maintained at the said holding | maintenance part side so that a movement in the direction orthogonal to the axial direction of a said 2nd piping is possible. The piping brazing device described.   The pipe brazing device according to claim 2 or 3, wherein the holding portion is formed so as to be divided in a circumferential direction, and each divided holding portion can be connected via a connecting means. .

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