JP2000266428A - Three-way branch pipe and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize brazing without using any part fixing jig by providing a U-bend bored pipe provided with a stretching part having a tapered joint hole on the side face at the bend, and a nose-type pipe having an end part pushed into the joint hole and brazed thereat. SOLUTION: Components of a saddle type three-way branch pipe, i.e., a U-bend bored pipe 1 and a nose-type pipe 2, are formed. A joint is secured without using any securing jig by pushing the nose-type pipe 2 into a tapered joint hole at the stretching part 1a of the U-bend bored pipe 1. A ring brazing material of bronze alloy produced by adding about 10 wt.% of tin to copper is then mounted on the stretching part 1a and brazing is carried out in a denatured gas atmosphere. Since overlap joint is employed by inserting the beveled end face of the nose-type pipe 2 into the tapered joint hole 1b, highly reliable joint is attained when brazing is carried out in a furnace and since a high melting point brazing material is employed, it does not melt during reheat and an enclosed joint can be retained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid branch part such as a refrigerant branch pipe used in a fin tube type heat exchanger, and more particularly to a three-way branch pipe in which three fluid pipes are joined and a method of manufacturing the same. Things.

[0002]

2. Description of the Related Art In a fin tube type heat exchanger, thin fins made of aluminum or the like are stacked with a gap serving as a flow path of a fluid such as air, and refrigerant is introduced into a plurality of pipes penetrating the stacked fins. By passing
The fluid is cooled or heated. For example, it is manufactured by inserting a hairpin type pipe penetrating the copper-laminated fins into aluminum fins in a skewered shape, and brazing and joining U-shaped bends alternately to the end face side of the copper pipe. In the brazing of the U-shaped bend, a ring-shaped brazing material (hereinafter, referred to as BCUP2), which is a joining material obtained by alloying about 7% by weight of phosphorus with copper, for example, is placed on a joint overlapping portion of the pipe. In general, a method of joining by heating with a torch or the like from both sides of a row of U-shaped bends is used.

FIG. 7 shows a conventional refrigerant diverter disclosed in, for example, Japanese Patent Application Laid-Open No. 7-174438, in which two or more rows of hairpin type pipes are arranged in a heat exchanger to improve cooling efficiency and improve the shape of the heat exchanger. It is adopted for making it suitable, and is composed of a straight pipe 12 and a split pipe section 13 for splitting the refrigerant in a right angle direction.

[0004] In the arrangement in which hairpin type pipes are arranged side by side in a U-shaped bend arranged in two or more rows, a saddle type three-way branch pipe in which a pipe branched to a bent portion of a U-shaped pipe is joined to a refrigerant branch is generally used. used. The saddle-type three-way branch pipe has a simple structure and can be easily installed with a small area.

FIG. 8 is a perspective view when a saddle-type three-way branch pipe is incorporated in a heat exchanger, FIG. 9 is an assembly view of a conventional general-purpose saddle-type three-way branch pipe, and FIG. FIG. 9B is a side view, and FIG. 9C is a top view. In FIG. 8, 3 is a saddle-type three-way branch pipe, 4 is a U-shaped bend, 5 is a brazing filler metal for a U-shaped bend, 6 is a brazing filler metal for a saddle-type three-way branch pipe, and 7 is a fin ( Aluminum). Brazing material 5
Is equivalent to BCUP2, and brazing material 6 is equivalent to BCUP4.

In FIG. 9, reference numeral 10 denotes a U-bend perforated tube having a joint hole, 11 denotes a nasal tube, and 11a denotes a flange portion.
The general-purpose saddle-type three-way branch pipe 3 is formed by fitting a copper nose-shaped pipe 11 having a flanged end face to a bent-side joint hole of a copper U-bend perforated pipe 8 and using a torch heating or high-frequency induction heating to form a BCUP2 or the like. Using a rod-shaped brazing material, performing a soldering by pouring the melted brazing material into the joining surface, or placing a paste-like high melting point brazing material such as bronze near the joining surface,
Heating in a heating furnace whose atmosphere has been adjusted with a propane-denatured gas or hydrogen to melt the wax and join it by furnace brazing, or enclose oil or molten lead in a thick-walled tube placed in a mold It has been manufactured by bulging integrated molding, which is formed by applying hydrostatic pressure to plastically deform the product.

[0007]

The saddle type three-way branch pipe 3 manufactured by brazing by torch heating or high-frequency induction heating is used to heat the brazed joint into a heat exchanger in a later process.
Since the brazing material at the branch portion is re-melted, defects caused by the re-melting must be repaired. In order to prevent re-melting, when the heat exchanger is brazed, the melting point is lower than that of a general brazing material such as BCUP2. For example, about 5% by weight of silver and about 6.3% by weight of scale are alloyed to copper. BCUP
It was necessary to use an expensive brazing material containing silver, such as 3.

In the brazing by the torch or high-frequency induction heating at the time of manufacturing the saddle type three-way branch pipe 3, since the brazing is performed by heating the pole in the atmosphere, the melting point of copper as a base material is about 1 °.
BCU that melts at about 200 ° C lower than 085 ° C
A high melting point brazing material of P2 or more, such as BCUP1 in which about 5% by weight of scale is alloyed with copper, has a high risk of dissolving the base material, and has a flux effect exhibited by burning scale. However, it was not easy to apply, for example, the product yield was reduced due to the small size.

In the case of manufacturing by brazing in a furnace using a high melting point brazing material, the joint portion of the saddle type three-way branch pipe 3 is provided with a flange formed in a hole formed on the side of the bent portion of the U-shaped bend 4. Since the nose-shaped tube 11 having undergone the 11a processing is attached in a different form, an inexpensive general-purpose ring wax cannot be used, and a paste brazing material that can cope with the irregular shape has been used. Paste brazing material is used by dispersing a metal powder brazing material with controlled particle size in a hydrocarbon solvent or the like and applying it to the vicinity of the joint, so it is significantly more expensive than a bar-shaped or ring-shaped brazing material. There was a problem.

Furthermore, when a belt-type heating furnace is used, there is a high risk that the joint between the U-shaped bend perforated tube 10 and the nose-shaped tube 11 will be displaced by vibration or the like. A jig for fixing each of the nasal tubes 11 was required. Since the jig is repeatedly heated between a furnace temperature of 1000 ° C. or higher and a room temperature at which the product is taken out, it is used as a consumable item, and has been one of the factors for increasing the joining cost.

In addition, since there is no joint in the bulge forming integral molding for plastically deforming a thick-walled pipe by hydraulic pressure or molten lead, etc., the sealing performance of a fluid flowing in the pipe, for example, a refrigerant, is high. In addition, the processing cost is high due to the complicated mold structure, and when using molten lead, there is a concern about the danger at the time of work and the adverse effect on the surrounding environment. Further, since the molded product is also thick, when the U-bend 4 of the heat exchanger in the subsequent process is brazed, the heat capacity cannot be balanced with the U-bend 4, so that even if a low melting point brazing material is used, There were problems such as the inability to join.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and in particular, a thin saddle-type three-way branch having a small heat capacity and capable of being simultaneously joined at the time of brazing U-bends in the production of a heat exchanger in a later step. In a method of manufacturing a saddle-type three-way branch pipe by brazing in a furnace to manufacture a pipe, an inexpensive ring wax can be manufactured without using a component fixing jig and without using an expensive paste brazing material. An object of the present invention is to provide a usable joint shape, a three-way branch tube that can be easily brazed, and a method for manufacturing the same.

[0013]

A three-way branch pipe according to the present invention comprises a U-bend perforated pipe provided with an overhang having a tapered joint hole on the side surface of a bent portion, and an end portion pushed into the joint hole. A brazed nasal tube.

Further, the inside diameter of the bottom of the joint hole is the same as the inside diameter of the nasal tube.

Further, the end of the nasal tube is chamfered along the joint hole.

The overhanging portion projects from a brazing portion with the end of the nasal tube.

Further, the method of manufacturing a three-way branch pipe is characterized in that a nose-shaped pipe end is pushed into a tapered joint hole of a projecting portion provided on a side surface of a bent portion of a U-bend perforated pipe, and the joint hole is connected to the nose. The nose tube is fixed by an overlapping portion of a mold tube, and a brazing material is placed on an end of the overlapping portion and brazed in a furnace.

Further, the tapered joint hole is formed by preparing a drilled hole on the side surface of the bent portion of the U-bend perforated pipe, and then raising the edge of the prepared hole outward with a raising tool to form the raised portion. Further, it is formed by pressing a V-shaped punch against the inside of the rising portion.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view of a saddle-type three-way branch pipe showing this embodiment, FIG. 2 is a plan view and a side view of a U-bend perforated pipe of the saddle-type three-way branch pipe, and FIG. FIG. 4 is a cross-sectional view of a junction tube before brazing of a junction, and FIG.
FIG. 5 is a manufacturing process diagram of a saddle-type three-way branch pipe, and FIG. 6 is an explanatory diagram of a method of forming a joint hole.

The saddle type three-way branch pipe is used by being arranged side by side with the U-shaped bend 4 of the heat exchanger as shown in FIG. 8 of the conventional example, and can be used compactly with a small area. It is used when branching a refrigerant flow path in a heat exchanger in which a mold bend is arranged. The configuration of the saddle type three-way branch pipe according to the present embodiment will be described with reference to FIGS. 2 (a) is a plan view of a perforated U-bend tube, FIG. 2 (b) is a side view, FIG. 3 (a) is a plan view of a nasal tube, and FIG. 3 (b) is a side view. In the figure, 1 is a U-bend perforated tube having a joint hole, 1a is an overhang,
1b is a tapered joint hole, 2 is a nasal tube brazed to the joint hole 1a of the U-bend perforated tube 1, and 8 is a brazing material.

The inner diameter d1 at the bottom of the joint hole 1b is the same as the inner diameter d2 of the nasal tube, and the end of the nasal tube 2 is chamfered along the joint hole 1b. Further, the overhang portion 1a protrudes from a brazing portion with the end of the nasal tube 2, so that the brazing easily accumulates.

Next, a method of manufacturing a saddle type three-way branch pipe will be described with reference to FIGS.
This will be described with reference to FIG. First, as an outline of the manufacturing process, as shown in FIGS. 2 and 3, a U-bend perforated tube 1 and a nasal tube 2 are formed in a process 1. On the side surface of the bent portion of the U-bend perforated tube 1, an overhang portion 1a having a tapered joining hole 1b is formed.
In the next step 2, the end of the nose-shaped pipe portion 2 is fitted into the tapered joint hole 1b of the overhang portion 1a provided on the side surface of the bent portion of the U-bend perforated tube 1 as shown in FIG. Then, brazing in a furnace is performed using the ring brazing 8.

Next, each step will be described. Step 1
In the part forming process of (1), the U-bend perforated tube 1 is prepared by bending a copper tube into a U-bend shape (S-1), and then drilling a pilot hole (S-).
2) Insert a jig with a variable outer diameter from the outside of the copper tube into the pilot hole,
After the insertion, the jig is opened and pulled out, so that the overhang portion 1a is set up as shown in FIG. 6A (S-3), and thereafter, FIG. 6B.
As shown in (4), the inner diameter punch 9 is pressed from the inner diameter side of the overhang portion 1a to form the joining hole 1b into a tapered shape (S-4).
At this time, the hole diameter d1 at the bottom of the joint hole 1b is the nasal tube inner diameter d2.
Diameter equivalent to

It is preferable that the overhang portion 1a overhangs at least three times the thickness of the copper tube. The overhang portion 1a may be prepared by inserting a prepared T-shaped T-drill and pulling it up while turning, or by drilling a prepared hole in the copper tube and piercing it from the inner diameter side with a punch or the like. May be bent into a U-bend shape.

Next, the nasal tube 2 is formed by bending a copper tube (S-tube).
5), cut to a certain size (S-6). Then, the cut surface is chamfered so as to match the joining hole (S-7). Although this chamfering process may be omitted, the cut surface is chamfered in order to minimize the circumferential clearance of the joint with the U-bend perforated pipe 1 in the circumferential direction and to prevent the solder from sagging. It is desirable. In a processing method capable of obtaining a clean cut surface such as spin cut, operations such as chamfering can be omitted.

Next, in the second brazing step, first, U
Tapered joint hole 1b of overhang 1a of bend perforated tube 1
The end of the nose-shaped tube 2 is pushed into the nose-shaped tube 2, and the elastic force of the flared portion 1 a is applied to the overlapping portion of the nose-shaped tube 2 and the joint hole 1 b of the nose-shaped tube 2, thereby fixing the nose-shaped tube 2 (S -8). And U
A ring wax is placed on the overhang portion 1a of the bend perforated tube 1 (S
-9), brazing in a furnace (S-10).

In the furnace brazing, for example, a bronze ring wax obtained by alloying about 10% by weight of tin with copper as a brazing material is used as a brazing filler metal, for example, in a modified gas atmosphere furnace at about 1050 ° C. for about 10 minutes. Perform brazing in the furnace.
At this time, by using a high melting point brazing material, re-melting can be prevented at the time of joining to a heat exchanger in a later step, but the liquidus temperature of the bronze brazing material mentioned as an example is about 102 ° C.
Since the melting point of copper is very close to 1080 ° C., such as 0 ° C., it is necessary to check the temperature of the brazing furnace sufficiently for each furnace.

In particular, depending on the accuracy of the furnace temperature control, there may be cases where the copper component as the base material is melted or, conversely, the wax is not melted at all. Further, if the brazing time is too short, the brazing does not flow sufficiently. If the brazing time is too long, so-called erosion occurs in which the copper pipe as the base material flows to the brazing side, and the thickness may be reduced near the brazing or a hole may be formed. In addition, the brazing material is exemplified by a bronze brazing material having a relatively wide melting range and capable of coping with a large gap. Cu-Si-Sn
, Cu-Zn-based, Cu-Mn-Ni-based brazing materials can also be used.

Although these brazing materials are generally used for wires and are inexpensively distributed, the brazing paste is very expensive, and the joining shape of the present invention makes it possible to use general-purpose and inexpensive brazing materials. Alternatively, a ring material can be used.

As described above, since the joining hole 1b of the U-bend perforated tube 1 is formed in a tapered shape, by pressing the nose-shaped tube into the joining hole, the joint between the two is fixed by the elastic force of the overhang. Therefore, it is not necessary to use a separate fixing jig when brazing in the furnace, and brazing can be facilitated. Further, a pool portion of the molten wax can be formed in the brazing step, a sufficient joining area can be secured even with a small overhang, and it is possible to suppress the dripping of the inner diameter side. In addition, since the hole diameter at the bottom of the joint hole 1b is made equal to the inner diameter of the nasal tube, the position for fitting the nasal tube is constant, and positioning can be performed without a fixing jig.
Joining can be performed without reducing the inner diameter area of the joining portion, and pressure loss of the fluid flowing in the pipe can be reduced.
Further, an inexpensive ring wax can be used without using an expensive paste brazing material.

[0031]

EXAMPLES Next, specific examples implemented based on this embodiment will be described. In this embodiment, the U-bend perforated pipe 1 and the nose-shaped pipe 2 which are components of the saddle type three-way branch pipe are used.
Was molded to the dimensions shown in FIGS. Then, the nose-shaped tube 2 is pushed into the tapered joint hole 1b of the projecting portion 1a of the U-bend perforated tube 1 so that the joint is fixed without using a special joint fixing jig, and the brazing material is formed. Was mounted on the overhang portion 1a with a bronze ring wax obtained by alloying about 10% by weight of tin with copper and brazed in a modified gas atmosphere furnace. In the brazing of the heat exchanger, a ring wax equivalent to BCUP2 is inserted into the brazing material 5 of the U-shaped bend 4 shown in FIG. A low ring wax equivalent to BCUP4 having a low alloying composition of about 6% by weight of silver on copper and about 7% by weight of scale was used.

Table 1 shows the structure, manufacturing method and test contents of the saddle-type three-way branch pipe. The evaluation test was conducted when the saddle-type three-way branch pipe of this embodiment was assembled into a heat exchanger as shown in FIG. 8 together with that of a comparative example described later, and joined by a belt-type automatic brazing device using a gas oxygen burner. And the presence or absence of a defect leading to leakage of refrigerant or the like was evaluated by an underwater leak test.

[0033]

[Table 1]

[0034]

Comparative Example In Comparative Example 1, as shown in Table 1, a saddle type three-way branch pipe was manufactured by integral molding of a molten lead bulge. It is extremely difficult to form a thin-walled pipe by the forming method that applies a large plastic deformation, and the thickness of the molded product of the saddle-type three-way branch pipe is limited to about 0.5 mm, and further thinning is impossible. Was.

In Comparative Example 2, as shown in Table 1, a U-bend perforated tube 1 was not provided with a tapered protrusion or a joint hole, and a nose-shaped tube having a flanged end face was pressed against the U-bend perforated tube 1. Was manufactured by pouring the brazing material into the joining gap.

Next, the evaluation results will be described. In the embodiment, the saddle-type three-way branch pipe 3 and the U-shaped bend 4 can be simultaneously brazed, and the saddle-type three-way branch pipe 3 branch junction does not cause re-melting and a leak failure occurs. Did not. Since the saddle-type three-way branch pipe 3 of the embodiment can be manufactured with a thin-walled pipe, the heat capacity can be reduced, and the temperature difference between the saddle-type three-way branch pipe 3 and the U-shaped bend 4 that is simultaneously joined in brazing at the time of manufacturing the heat exchanger can be reduced. By combining them properly, simultaneous brazing was made possible. Further, the branch joint is provided with a nose-shaped tube 2 in the tapered joint hole 1b.
Because of the lap joining with the chamfered end face inserted, the joining reliability in brazing in the furnace is high, and since a high melting point brazing material is used, there is no melting when reheating,
The hermeticity of the joint remained. In addition, at the time of brazing in a furnace, simple manufacturing was realized, such as the use of an inexpensive ring preform material instead of an expensive paste wax and the elimination of a component fixing jig.

The branch part of the saddle type three-way branch pipe 3 is U-shaped.
The inside diameter of the bottom of the joint hole of the bend perforated tube 1 is made the same as the inside diameter of the nasal tube 2, and the joint is further overlapped by pressing the chamfered end of the nasal tube 2 into the tapered joint hole 1 b. Therefore, it can be manufactured without wax drooping to the inner diameter side, and when a heat exchanger using a saddle type three-way branch pipe is put into practical use, the pressure loss of the fluid flowing in the pipe is small and a high efficiency heat exchanger Can be manufactured.

In Comparative Example 1, when the bulge-integrated molded product was brazed by an automatic heat brazing device, the heat capacity balance between the U-shaped bend 4 and the U-shaped bend 4 which was brazed at the same time because of the thick wall was not obtained. Even if a brazing material equivalent to BCUP4, which melts at a lower temperature than the brazing material equivalent to BCUP2 attached to No. 4, a sufficient molten state could not be obtained, resulting in insufficient bonding. In addition, when the thermal power was increased to such an extent that the brazing of the saddle-type three-way branch pipe 3 was sufficiently melted, the U-shaped bend main body was melted, resulting in a problem.

Comparative Example 2 is a saddle-type three-way branch pipe 3 whose branch portion is braced with a product equivalent to BCUP2, and can be simultaneously bonded to the heat exchanger with the U-shaped bend 4. Melted again, resulting in leak failure. Although almost the same brazing material equivalent to BCUP2 is used at the junction of the branch pipe of the saddle type three-way branch pipe 3 and the junction at the time of assembling the heat exchanger, the brazing material once melted has a melting temperature due to the characteristics of the brazing material. Because of the rise, it may not re-melt depending on the second stage heating state. However, in the heat exchanger assembly brazing, it is necessary to complete the brazing in a short time, and because of the relatively large overheating, a portion of the brazing material that melts and flows out and does not reach the seal occurs, and as a result, It is considered that leak failure occurred frequently.

The present invention is not limited to the saddle-type three-way branch pipe shown in the embodiment of the invention described above, but can be used, for example, as a general-purpose water pipe branch part. Various modifications can be made without departing from the scope of the present invention.

[0041]

As described above, according to the present invention, there is provided a U-shape in which a projecting portion having a tapered joining hole is provided on the side surface of a bent portion.
Since a bend perforated pipe and a nose-shaped pipe whose end is pressed into the joint hole and brazed are provided, brazing can be performed without using a component fixing jig, and furthermore, an inexpensive ring pipe is used. Since the reshaping brazing material has a joining shape that can be used, and a brazing layer can be formed when the brazing material is melted, highly reliable brazing can be facilitated.

Since the inside diameter of the bottom of the joint hole is the same as the inside diameter of the nasal tube, the position where the nasal tube is fitted at the time of the brazing of the joint becomes constant, and there is no component fixing jig. In addition, a three-way branch pipe can be obtained which can be positioned without reducing the inner diameter area of the bonding portion and reduce the pressure loss of the fluid flowing in the pipe.

Since the end of the nasal tube is chamfered along the joint hole, the clearance at the joint is minimized uniformly in the circumferential direction. A branch pipe can be obtained.

Further, since the overhanging portion protrudes from the brazing portion with the end of the nasal tube, it is possible to form a brazing pool when the brazing material is melted, thereby facilitating reliable brazing. be able to.

Further, the method for manufacturing a three-way branch pipe is as follows. A nose-shaped pipe end is pushed into a tapered joint hole of a projecting portion provided on a side surface of a bent portion of a U-bend perforated pipe. The nose tube is fixed by the overlapping portion of the mold tube, and the brazing material is placed on the end of the overlapping portion and brazed in the furnace, so that simple brazing can be performed without using a jig. .

The tapered joint hole is formed by preparing a hole in the side surface of the bent portion of the U-bend perforated pipe, and then raising the edge of the prepared hole outward with a rising tool to form the rising portion. Furthermore, since the V-shaped punch is pressed against the inside of the rising portion and formed, a projecting portion having a tapered joining hole can be easily formed.

[Brief description of the drawings]

FIG. 1 is a perspective view of a saddle type three-way branch pipe showing an embodiment according to the present invention.

FIG. 2 is a plan view and a side view of a U-bend perforated pipe of a saddle type three-way branch pipe.

FIG. 3 is a plan view and a side view of a nose-shaped tube of a saddle-type three-way branch tube.

FIG. 4 is a cross-sectional view of a saddle type three-way branch pipe before brazing a joint portion.

FIG. 5 is a manufacturing process diagram of a saddle-type three-way branch pipe showing an embodiment according to the present invention.

FIG. 6 is an explanatory view of a method of forming a joint hole of a U-bend perforated pipe of a saddle type three-way branch pipe.

FIG. 7 is a perspective view of a conventional branch pipe.

FIG. 8 is a schematic view showing the incorporation of a saddle-type three-way branch pipe into a heat exchanger.

FIG. 9 is a schematic view of a conventional saddle-type three-way branch pipe.

[Explanation of symbols]

1 U-bend perforated pipe, 1a overhang, 1b joint hole, 2
Nose tube, 3 saddle type three-way branch tube, 4 U-bend.

Claims (6)

[Claims] 1. A U-bend perforated tube provided with an overhang having a tapered joint hole on a side surface of a bent portion, and a nose-shaped tube whose end is pressed into the joint hole and brazed. A three-way branch pipe. 2. The three-way branch pipe according to claim 1, wherein the inner diameter of the bottom of the joint hole is the same as the inner diameter of the nasal pipe. 3. The three-way branch pipe according to claim 1, wherein the end of the nasal pipe is chamfered along the joint hole. 4. An overhang portion according to claim 1, wherein the overhang portion protrudes from a brazing portion with the end of the nasal tube.
The three-way branch pipe according to any one of the above. 5. A nose-shaped pipe end is pushed into a tapered joint hole of a protruding part provided on a side surface of a bent part of a U-bend perforated pipe, and said joint hole and said nose-shaped pipe are overlapped by said overlapping part. A method for manufacturing a three-way branch pipe, comprising fixing a nose-shaped pipe, placing a brazing material on an end of the overlapping portion, and brazing in a furnace. 6. A tapered joint hole is prepared by preparing a prepared hole in a side surface of a bent portion of a U-bend perforated pipe, and then raising an edge of the prepared hole outward with a raising tool to form a raised portion. 6. The method for manufacturing a three-way branch pipe according to claim 5, wherein a V-shaped punch is pressed against the inside of the rising portion.