JP6959399B2 - How to join pipes - Google Patents

Description

The present invention relates to a method of joining pipes used in air conditioners and the like by brazing.

For example, when installing air conditioning equipment, the work of installing outdoor units and indoor units at desired locations in a building and joining pipes between each of these units is performed. Various methods are known for joining pipes, and among them, brazing joining has been widely used in the past because of its advantages such as being easily carried out on site as needed. In this brazing joining, for example, of the two pipes to be joined, a diameter-expanded portion is provided at the end of one pipe, the end of the other pipe is inserted into the expanded diameter portion, and the brazing material is melted. It is done by pouring it into the joint.

By the way, in the case of joining by brazing, since the brazing material is heated and melted, the end portion of the pipe and the vicinity of the joining end are exposed to a considerably high heat. Therefore, if brazing is performed in the state where air is present inside the pipe, an oxide film is formed on the inner surface of the pipe. When this oxide film is peeled off, it causes clogging of piping and contamination, which causes an adverse effect on air conditioning equipment.

Therefore, conventionally, when joining by brazing, a method of introducing an inert gas such as nitrogen into the pipe to prevent oxidation of the inner surface of the pipe has been performed. In this method, pipes are joined to each other, a nitrogen pipe is joined to the end of the pipe, the nitrogen gas pressure is adjusted to about 0.02 MPa immediately before the start of brazing, and nitrogen gas is flowed from one direction to the entire pipe system. This is done by brazing the joint while checking and adjusting the pressure at the end of the pipe on the opposite side. Further, after the brazing is completed, the joint portion is cooled with a wet towel or the like to prevent reoxidation due to residual heat, and after the cooling is completed, the nitrogen gas is stopped.

Further, a method of introducing the combustion exhaust gas of the burner into the inside of the pipe instead of nitrogen or the like has also been proposed (see Patent Documents 1 and 2). For example, Patent Document 1 discloses a pipe joining component that joins two pipes and a method of forming an opening at an end of the pipe and introducing exhaust gas into the pipe from there to braze. Further, Patent Document 2 discloses a method of forming a gap between the end faces of two copper pipes and introducing exhaust gas into the pipe through the gap to braze.

Japanese Patent No. 4317568 Japanese Unexamined Patent Publication No. 2013-160246

However, if nitrogen gas is continuously flowed from immediately before the start of brazing to the completion (cooling), a large amount of nitrogen gas is consumed, which is uneconomical. In addition, it is necessary to check the end of the pipe for pressure adjustment, and there is a problem that it takes time and effort to move, join, and adjust the pressure of the nitrogen cylinder.

On the other hand, by using the combustion exhaust gas as in Patent Documents 1 and 2, it is possible to reduce the economic burden. However, in the method of forming an opening as in Patent Document 1 and introducing exhaust gas into the pipe from there, the opening is exposed to the outside after brazing, and this opening is closed by a brazing material. , The problem of strength remains as compared with the case where the opening is not formed. Further, by using the brazing device disclosed in Patent Document 2, it is possible to braze and join the pipes without providing an opening in the pipes, but the device of Patent Document 2 is used repeatedly, so that the durability is improved. It becomes a problem. In particular, when the method of introducing the exhaust gas of the burner is adopted, such a problem becomes even greater because the device (particularly, the second stopper 5 shown in Patent Document 2 and the like) is heated.

An object of the present invention is to provide a method for brazing by locally injecting a non-oxidizing gas only into a heated portion by a simple method while solving the problem of insufficient strength due to opening.

According to the present invention for solving the above problems, the ends of two pipes are brazed to each other and joined to each other by using an oxygen cylinder, an acetylene gas cylinder, and a non-oxidizing gas cylinder at the end of one pipe. When inserting and brazing the end of the other pipe, a diameter-expanded portion is provided at the end of the one pipe, and the end of the other pipe is inserted into the expanded diameter. An opening is provided at the tip of the pipe, the tip of the other pipe is inserted into the enlarged diameter portion up to the first position where the opening is exposed, the non-oxidizing gas cylinder is opened, and the other pipe is opened. With the tip portion inserted to the first position, the non-oxidizing gas is injected into the inside of the two pipes through the opening, and the non-oxidizing gas is injected into the vicinity of the enlarged diameter portion of the one pipe and the said. The vicinity of the tip of the other pipe is locally filled, and the tip of the other pipe is inserted to a second position where the opening is covered by the enlarged diameter portion, and the oxygen cylinder and the acetylene gas cylinder are inserted. Is opened, and the non-oxidizing gas locally fills the vicinity of the enlarged diameter portion of the one pipe and the vicinity of the tip portion of the other pipe, and the opening is covered with the enlarged diameter portion. Therefore, a pipe joining method is provided , which comprises brazing and joining the ends of the two pipes.
In addition, it is a method of brazing and joining the ends of two pipes, and when the end of the other pipe is inserted into the enlarged diameter portion provided at the end of one pipe and brazed. , An opening is provided at the end of the other pipe at a position where it is inserted into the enlarged diameter portion, and the other pipe is used up to a position before the opening is still inserted into the enlarged diameter portion. With the end inserted into the enlarged diameter portion, non-oxidizing gas is injected into the inside of the two pipes from the opening, and the other pipe is reached to a position where the opening is inserted into the enlarged diameter portion. Provided is a pipe joining method, characterized in that the end portion of the pipe is inserted into the enlarged diameter portion and the ends of the two pipes are brazed and joined to each other.

Since the position of the opening for injecting non-oxidizing gas into the pipe is in the expanded diameter portion during brazing, the opening is not exposed to the outside after brazing, and the problem of strength is solved. NS.

The distance from the tip end surface of the other pipe to the edge portion of the opening on the tip end surface side is such that the end portion of the other pipe is extended to a position before the opening is still inserted into the enlarged diameter portion. When the non-oxidizing gas is injected into the inside of the two pipes from the opening in the state of being inserted into the enlarged diameter portion, the injected non-oxidizing gas may be set to a distance that does not leak to the outside. .. In that case, the distance from the tip end surface of the other pipe to the edge portion of the opening on the tip end surface side is, for example, 1.5 mm or more. Further, the opening may be inserted to a position deeper than the position where the wax enters the enlarged diameter portion when brazed, and the ends of the two pipes may be brazed and joined. In that case, for example, the opening may be inserted to the depth of more than half of the enlarged diameter portion, and the ends of the two pipes may be brazed to each other for joining.

Since the opening is not exposed to the outside after brazing, the problem of strength is solved and the pipes can be firmly joined to each other. Further, the non-oxidizing gas need only be injected near the ends of the two pipes, and the non-oxidizing gas can be locally injected in a short time. Further, pressure adjustment is not required, and non-oxidizing gas can be injected only with a small nitrogen gas cylinder, which is economical.

It is explanatory drawing of one pipe. It is explanatory drawing of the other pipe. It is a front view of the other pipe. It is explanatory drawing of the state to braze. It is explanatory drawing of the state in which the end of the other pipe is inserted into the diameter-expanded portion of one pipe until the position before the opening is inserted into the diameter-expanded portion. It is explanatory drawing of the state in which the end portion of the other pipe is inserted into the diameter-expanded portion of one pipe, and the ends of the two pipes are brazed to each other until the opening is inserted into the diameter-expanded portion. It is explanatory drawing of the embodiment which attaches a joining member to the end of one pipe and provides a diameter-expanded portion, (1) is a state before attaching a joining member, and (2) is a state after attaching a joining member. Is shown.

Hereinafter, an example of the embodiment of the present invention will be described with reference to the drawings. In the present specification and the drawings, elements having substantially the same functional configuration are designated by the same reference numerals, so that duplicate description will be omitted.

The pipe joining method according to the embodiment of the present invention includes an end portion 1a of one pipe 1 shown in FIG. 1 (left end portion in FIG. 1) and an end portion 2a of the other pipe 2 shown in FIG. 2 (in FIG. 2). This is a method of joining the right end) by brazing. Both the one pipe 1 and the other pipe 2 are cylindrical hollow pipes having both ends open, and are made of a pipe material such as a copper pipe for a refrigerant pipe. The ends 1a and 2a of the pipes 1 and 2 refer to each other portion provided for joining the pipes 1 and 2, for example, when the pipe diameter (outer diameter) is 12.7 mm, the pipes 1 and 2 have a diameter of 12.7 mm. It is a part up to about 9 mm from the tip surface. In this case, the tip surface of the pipes 1 and 2 is the end surface on the side where the pipes 1 and 2 are joined, and in the case of the pipe 1 shown in the figure, the left end surface (the left end surface of the enlarged diameter portion 10) is the tip surface of the pipe 1. It is a surface, and in the case of the illustrated pipe 2, the right end surface is the tip surface of the pipe 2.

The end portion 1a of one of the pipes 1 is provided with a diameter-expanded portion 10 from the tip surface to a range of length L. The diameter-expanded portion 10 can be provided in the vicinity of the end portion 1a of one of the pipes 1 by a known method such as bulge processing or using a commercially available pipe expander. Strictly speaking, the length L of the enlarged diameter portion 10 is not the length that appears on the outer peripheral surface of the enlarged diameter portion 10, but the length on the inner peripheral surface (inner wall) side of the enlarged diameter portion 10, and will be described later. Is equal to the length L of the end 2a of the other pipe 2 inserted into the diameter-expanded portion 10 (see FIG. 6).

The end 2a of the other pipe 2 is inserted into the enlarged diameter portion 10 of the end 1a of the one pipe 1 up to the position of length L and brazed. The end 2a of the other pipe 2 is provided with an opening 11 at a position where it is inserted into the enlarged diameter portion 10. The opening 11 is bored on the peripheral surface of the pipe 2 at an axis line of 90 ° from the central axis of the openings at both ends of the pipe material. That is, the opening 11 is provided at a position (position on the tip surface side) before the length L from the tip surface of the other pipe 2. The inner diameter of the enlarged diameter portion 10 and the outer diameter of the end portion 2a of the other pipe 2 are provided with a difference of about 0.1 mm, whereby a gap is formed when the diameter is inserted, so that the melted wax penetrates. I am trying to do it.

Here, in the embodiment of the present invention, the distance M from the tip surface of the other pipe 2 to the edge portion of the opening 11 on the tip surface side is 1.5 mm or more, and to the edge portion far from the tip surface. Distance (M + d) is set to less than half of the length L. Further, the opening 11 has a circular shape with a diameter d = 1.5 mm.

As shown in FIG. 4, by supporting one of these pipes 1 and the other pipe 2 with an appropriate support tool 15, one pipe 1 and the other pipe 2 are arranged in series, and the end portion 1a is arranged. And the end 2a are butted against each other, and the end 2a of the other pipe 2 is inserted into the enlarged diameter portion 10 of the end 1a of one pipe 1 to perform the brazing operation. In order to perform this work, for example, a nozzle 20, an oxygen cylinder 21, an acetylene gas cylinder 22, and a nitrogen gas cylinder 23 that supply each gas to the nozzle 20 are used. The procedure for joining will be described below in order.

First, as shown in FIG. 5, the end portion 2a of the other pipe 2 is inserted into the enlarged diameter portion 10 of the end portion 1a of one pipe 1. Here, the end 2a of the other pipe 2 is inserted into the diameter-expanded portion 10 until the opening 11 is still inserted into the diameter-expanded portion 10, and the opening 11 goes out of the diameter-expanded portion 10. It temporarily stops in the state of being. In this case, since the distance M from the tip end surface of the other pipe 2 to the edge portion of the opening 11 on the tip end surface side is set to 1.5 mm or more, the end portion 2a of the other pipe 2 is set to the pipe 1. Even if the opening 11 is inserted into the enlarged diameter portion 10 to a distance of 1.5 mm from the tip surface, it is possible to ensure that the opening 11 is outside the enlarged diameter portion 10. If it is inserted more than this, the opening 11 is hidden by the enlarged diameter portion 10 (if it is inserted 3 mm or more, the entire opening 11 is hidden), and nitrogen gas cannot be injected by the nozzle 20 described later.

Then, the nitrogen gas cylinder 23 is opened, nitrogen gas is blown out from the nozzle 20, nitrogen gas is injected into the pipes 1 and 2 from the opening 11, and the vicinity of the end 1a of one pipe 1 and the end of the other pipe 2 are injected. Fill the vicinity of 2a with nitrogen gas. In this way, the inside of the pipes 1 and 2 is made into a non-oxidizing atmosphere. In this case, if the end 2a of the other pipe 2 is inserted into the enlarged diameter portion 10 from the tip surface of the pipe 1 to a distance of 1.5 mm, the nitrogen gas injected into the pipes 1 and 2 will be discharged to the outside. Almost no leakage. Further, if the diameter d of the opening 11 is 1.5 mm, nitrogen gas can be smoothly injected into the pipes 1 and 2 from the opening 11. A nozzle 20 that matches the diameter of the opening 11 is used, but if the diameter d of the opening 11 is less than 1.5 mm, it becomes necessary to use a nozzle 20 having a small diameter, so gas is injected. The resistance when doing it becomes large.

Next, as shown in FIG. 6, the end 2a of the other pipe 2 is promptly inserted to the innermost part of the enlarged diameter portion 10 of the end 1a of the one pipe 1. Alternatively, the enlarged diameter portion 10 side may be pushed toward the end portion 2a side. As a result, the portion of the end portion 2a of the other pipe 2 from the end surface to the position of the length L is inserted into the diameter-expanded portion 10, and the opening 11 is inserted into the inside of the diameter-expanded portion 10. .. In this case, since the distance (M + d) from the tip surface of the other pipe 2 to the edge on the far side from the tip surface of the opening 11 is less than half of the length L, the opening 11 is inserted. , It is possible to carry out to the back side by more than half of the diameter-expanded portion 10.

Then, the oxygen cylinder 21 and the acetylene gas cylinder 22 are opened, and the oxygen gas and the acetylene gas ejected from the nozzle 20 are burned. As a result, the end 1a of one pipe 1 and the end 2a of the other pipe 2 are heated, and at the same time, the brazing material 25 is melted and poured into the joint portion, so that the end 1a of one pipe 1 and the other pipe 2 are heated. The end 2a of 2 is joined by brazing.

After the joining is completed, for example, a wet towel or the like is applied to cool the joined portion to room temperature to prevent reoxidation due to residual heat. In this way, the joining of the end portion 1a of the pipe 1 and the end portion 2a of the other pipe 2 is completed.

According to this embodiment, since the opening 11 is not exposed to the outside after brazing, the problem of strength is solved, and the ends of the pipes 1 and 2 can be firmly joined to each other. Further, nitrogen gas as a non-oxidizing gas may be injected only in the vicinity of the ends of the two pipes 1 and 2, and the nitrogen gas can be injected locally in a short time. If the opening 11 is extremely close to the tip surface of the end 1a of one of the pipes 1, there may be a problem in strength (such as distortion when the pipe end is hit), or when brazing. Since the vicinity of the opening 11 may be distorted when exposed to a high temperature, it is desirable that the opening 11 is provided at a certain distance from the tip surface of the pipe 1. If the distance M from the tip end surface of the other pipe 2 to the edge portion on the tip end surface side of the opening 11 is 1.5 mm or more, the problem of such distortion generation is solved. Further, after brazing, it is desirable that the opening 11 is hidden as far as possible in the enlarged diameter portion 10. At the time of brazing, the brazing penetrates to about one-half to one-half of the enlarged diameter portion 10, so if the opening 11 penetrates deeper than this, the presence or absence of the opening 11 determines the joint strength. It is considered that it does not affect. That is, it is desirable that the distance (M + d) from the tip surface of the other pipe 2 to the edge portion on the far side from the tip surface of the opening 11 is halved or less of the length L.

The length L of the enlarged diameter portion 10 provided at the end 1a of one of the pipes 1 varies depending on the pipe diameter of the pipe, but the shallowest of the commercially available pipes is about 8 mm. If the distance (M + d / 2) from the tip surface of the other pipe 2 to the center of the opening 11 is 3 mm and the diameter d of the opening 11 is 1.5 mm, the opening of the other pipe 2 is set regardless of the pipe diameter. By performing the opening work without changing the above distance and diameter settings in the device provided with the portion 11, the distance from the tip surface of the other pipe 2 to the edge portion of the opening 11 on the tip surface side is 1.5 mm or more. Then, the opening 11 can be inserted to the back side by more than half of the length L of the enlarged diameter portion 10.

Although the embodiments of the present invention have been illustrated and described above, the present invention is not limited to such examples. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the technical idea described in the claims, and of course, the technical scope of the present invention also includes them. It is understood that it belongs to.

For example, the non-oxidizing gas injected into the pipe is not limited to nitrogen gas, but includes combustion gas, argon and the like. Further, as shown in FIG. 5, when inserting the end portion 2a of the other pipe 2 into the enlarged diameter portion 10 of the end portion 1a of one pipe 1, the tip of the nozzle 20 is inserted into the opening 11 in advance. You can leave it. Then, the nozzle 20 serves as a stopper, and the opening 11 can be stopped at a position before being inserted into the enlarged diameter portion 10.

Further, in the embodiment, an example in which the diameter-expanded portion 10 is provided at the end portion 1a of one of the pipes 1 by bulge processing or the like has been described, but as shown in FIG. 7 (1), the tubular joining member 10 'Is prepared separately, and as shown in FIG. 7 (2), this joining member 10'may be attached to the end portion 1a of one of the pipes 1 to provide the enlarged diameter portion 10.

Further, the support 15 shown in FIG. 4 shows a mode in which the two pipes 1 and 2 are suspended by the support 15 from above, but for example, the following mode may be used. Prepare a plurality of pedestals having recesses formed in advance on the upper surface according to the curvature of the outer circumferences of the pipes 1 and 2. This recess is formed at the same height position on each stand so that the two pipes 1 and 2 related to the joint can be set horizontally at the same height position. The recess may have a V-shaped cross section. Alternatively, if the installation height of the pipes 1 and 2 is at a height position suitable for the work, one pipe 1 is fixed in the main installation, and the other pipe 2 is aligned with the one pipe 1 in the axis of one of the pipes 1. It may be temporarily supported at a distance from the tip surface of the pipe 1. When the pipes 1 and 2 are vertical pipes, the lower pipe (one pipe 1) is fixed in the main installation, and then the other pipe 2 is suspended directly above the pipe 1 to obtain non-oxidizing gas. After the introduction of, it may be dropped by its own weight and then brazed.

The present invention can be applied to, for example, the construction of piping for air conditioning equipment.

1 One pipe 1a End 2 The other pipe 2a End 10 Enlarged part 11 Opening 15 Support 20 Nozzle 21 Oxygen cylinder 22 Acetylene gas cylinder 23 Nitrogen gas cylinder 25 Wax material

Claims (1)

It is a method of brazing and joining the ends of two pipes.
Using oxygen cylinders, acetylene gas cylinders, and non-oxidizing gas cylinders,
When inserting and brazing the end of the other pipe into the end of one pipe,
A diameter-expanded portion is provided at the end of the one pipe.
An opening is provided at the end of the other pipe, which is inserted into the enlarged diameter portion.
The tip of the other pipe is inserted into the enlarged diameter portion to the first position where the opening is exposed.
With the non-oxidizing gas cylinder opened and the tip of the other pipe inserted to the first position, the non-oxidizing gas is injected into the two pipes through the opening.
The non-oxidizing gas is locally filled in the vicinity of the enlarged diameter portion of the one pipe and the vicinity of the tip portion of the other pipe.
The tip of the other pipe is inserted to a second position where the opening is covered by the enlarged diameter portion.
The oxygen cylinder and the acetylene gas cylinder are opened, and the non-oxidizing gas locally fills the vicinity of the enlarged diameter portion of the one pipe and the vicinity of the tip portion of the other pipe, and the opening is expanded. A pipe joining method, characterized in that the ends of the two pipes are brazed to each other while being covered with a diameter portion.

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