JP4435008B2 - Method for manufacturing twisted tube heat exchanger - Google Patents

Description

  The present invention relates to a torsion tube heat exchanger, and more particularly, to a method for manufacturing a heat exchanger in which a refrigerant pipe is wound around an outer periphery of a water pipe serving as a core pipe.

  Conventionally, a torsion tube type heat exchanger in which a refrigerant pipe is wound around an outer periphery of a water pipe serving as a core pipe is known. In such a case, the water pipe and the refrigerant pipe are usually made of a copper alloy having a high thermal conductivity, and these are joined by brazing or soldering in a furnace (for example, Patent Document 1).

  Moreover, in such a thing, in order to adhere | attach the water piping used as a core pipe, and the refrigerant | coolant pipe wound around it, it expands by applying a hydraulic pressure to the inside of the water pipe used as a core pipe, or a core pipe The water pipe is expanded through a dice for expansion into the water pipe, which relatively increases the tightening force of the refrigerant pipe so that the refrigerant pipe bites into and adheres to the outer peripheral surface of the water pipe. Is also known (see, for example, Patent Document 2).

  In addition, a core pipe and a refrigerant pipe are joined by pulling a core pipe and a refrigerant pipe wound around the core pipe into a molten solder tank and then pulling them up (for example, patents). Reference 3).

  Also known is one in which molten solder is sprayed and applied to one pipe for heat exchange, and the other pipe is superimposed on the two pipes so that these two pipes are joined so that heat exchange is possible (for example, (See Patent Document 4).

JP 2002-228370 A JP 2004-93057 A JP 2002-130881 A JP 2003-154448 A

  However, in the case of joining the water pipe and the refrigerant pipe in the furnace by brazing or soldering, it is necessary to put a brazing material between the refrigerant pipe and the water pipe in advance, and in the furnace brazing process In order to suppress high-temperature oxidation of water pipes and refrigerant pipes, brazing in an inert or reducing atmosphere is necessary, and expensive brazing equipment is required.

In addition, in the case of a mechanical joining method in which a water pipe serving as a core pipe is expanded by applying a hydraulic pressure (for example, hydraulic pressure) to the inside, the water pipe and a refrigerant pipe wound around the water pipe are in close contact with each other. The shape deformation of the water pipe at the time of pipe expansion is affected by the refrigerant pipe wound around the outer periphery, and the thickness of the pipe is partially uneven, which may cause a decrease in pressure resistance during actual use.
In addition, in the case of a mechanical joining method in which the water pipe and the refrigerant pipe wound around the water pipe are in close contact with each other by expanding the pipe through the expansion die into the core water pipe, the inside of the water pipe is damaged when the pipe is expanded. There were difficulties that caused corrosion such as pitting corrosion or erosion during actual operation.

  In addition, when soldering, for example, wire solder is used, it is necessary to wrap the solder between the pipes in advance in the same way as the brazing material. Therefore, there is a possibility that the solder wettability may decrease, the thermal conductivity performance may decrease due to the solder oxide remaining in the joint, and the appearance design may deteriorate due to the adhesion of the oxide. When using molten solder by spraying, it is difficult to evenly supply an appropriate amount of solder due to uneven soldering or excessive solder adhesion, which increases the heat transfer area between pipes. There was a difficulty of becoming an obstacle.

  The present invention has been made to solve the above-described problems, and can significantly increase the effective contact area, and can ensure both low-cost joining technology and reliability during actual use by simplifying the process. An object of the present invention is to provide a method for manufacturing a twisted tube heat exchanger.

  In the method for manufacturing a twisted tube heat exchanger according to the present invention, a refrigerant pipe is wound around a water pipe having a plurality of spiral grooves on the outer periphery along the spiral groove, and then the water pipe and the refrigerant pipe are connected. A method of manufacturing a torsion tube heat exchanger to be tightly bonded, the step of immersing the water pipe and the refrigerant pipe after winding the refrigerant pipe in the molten solder tank for a certain period of time, and the water pipe and the refrigerant pipe from the molten solder tank. The process of blowing molten solder to the water pipes and refrigerant pipes in the atmosphere while pulling up, and the water pipes and refrigerant pipes to which the molten solder has been blown further pulled up, and hot air is blown to these water pipes and refrigerant pipes to cause excess melting And a step of removing the solder.

  According to the manufacturing method of the twisted tube heat exchanger of the present invention, the unevenness of the solder is prevented by immersing the water pipe and the refrigerant pipe after winding the refrigerant pipe in the molten solder tank for a certain period of time. At that time, even if the solder oxide may adhere to the joint portion, the solder oxide attached to the joint portion can be washed away by spraying the molten solder in the atmosphere and replaced with the molten solder by spraying. Therefore, it is possible to avoid the occurrence of problems such as a decrease in solder wetting and a decrease in heat conduction performance due to solder oxide remaining in the joint. In addition, after the molten solder is sprayed, hot air is sprayed onto the water pipe and the refrigerant pipe to remove excess molten solder, so that even if the molten solder is biased by spraying, adhesion of excess solder is prevented. As a result, an appropriate amount of solder is evenly supplied, so that wetting of the solder between the water pipe and the refrigerant pipe is improved, which leads to expansion of the heat transfer area between the pipes, and heat transfer efficiency is improved. .

Embodiment 1 FIG.
The present invention will be described below with reference to illustrated embodiments.
FIG. 1 is a schematic diagram showing an apparatus used in a method for manufacturing a torsion tube heat exchanger according to Embodiment 1 of the present invention, and FIG. 2 shows a method for manufacturing a torsion tube heat exchanger according to this embodiment. FIG. 3 is a cross-sectional view of an essential part of the torsion tube heat exchanger manufactured by the manufacturing method of the present embodiment cut along the tube axis of the water pipe.

  As shown in FIG. 3, the torsion tube heat exchanger 1 according to this embodiment is a torsion tube having a plurality of spiral grooves 2a on its outer periphery, that is, a water pipe 2, and is wound around the water pipe 2 along the spiral groove 2a. The refrigerant pipes 3a, 3b, 3c are configured.

  As shown in FIG. 1, an apparatus for joining the water pipe 2 and the refrigerant pipe 3 wound around the water pipe 2 is installed in the outer part of the solder tank 4 and the solder tank 4, and the solder in the solder tank (hereinafter, melted). A heater 6 that indirectly heats 5), a lifting device (not shown) that lifts and lowers the torsion tube heat exchanger 1 so as to be immersed in the solder bath, and a jet pump installed in the solder bath The molten solder 5 fed from the jet pumps 7a and 7b and the jet pumps 7a and 7b is blown in the air toward the water pipe 2 and the refrigerant pipe 3, that is, the torsion pipe heat exchanger 1 pulled up from the solder tank by the lifting device. The hot air 9 is blown to the jet nozzles 8a and 8b (or to be poured) and the twisted tube heat exchanger 1 which is disposed at a higher position than the jet nozzles 8a and 8b and is blown up by the lifting device when the molten solder is blown. , More Hot air blow nozzles (hereinafter simply referred to as nozzles) 10a, 10b for removing the molten solder and dropping them into the solder bath 4, and the solder oxide formed on the surface of the immersion bath are installed on the side of the solder bath 4 so as to be removable. And a guide 11.

  Next, the manufacturing method of the twisted tube heat exchanger of this embodiment is demonstrated, referring FIG. 3 based on FIG.1 and FIG.2. Here, the refrigerant pipe 3 is wound around the water pipe 2 along the spiral groove 2a in advance, and the water pipe 2 around which the refrigerant pipe 3 is wound is bent to a predetermined dimension to be a twisted pipe heat exchanger 1. It is assumed that it is formed. First, as a pretreatment, as shown in FIG. 2, a flux (oxide film removing agent) is dip coated on the twisted tube heat exchanger 1, and then preheating is performed for solvent removal of the flux and activation of the flux. The above is the preprocessing. Thereafter, the solder bonding process shown in the middle stage of FIG. 1 and FIG. 2 is followed.

  In the soldering process, first, the water pipe 2 and the refrigerant pipe 3, that is, the torsion pipe type heat exchanger 1 after winding the refrigerant pipe are immersed in the molten solder tank 4 for a certain period of time. Next, the jet pumps 7a and 7b are started to start the ejection of the molten solder from the jet nozzles 8a and 8b, and then the torsion tube heat exchanger 1 is pulled up from the molten solder tank 4 by the lifting device, and the torsion tube type Molten solder 5 is sprayed on the water pipe 2 and the refrigerant pipe 3 of the heat exchanger 1 in the atmosphere. As the solder material used in the above immersion process and spraying process, here, lead-free solder having a small environmental impact is used, and a small amount of P (phosphorus) and Ge (germanium) are added as additive elements to suppress oxide generation. The one having the composition described above was used.

  When the torsion tube heat exchanger 1 rising while the molten solder 5 is sprayed from the jet nozzles 8a and 8b in the atmosphere is pulled up to a predetermined position, hot air 9 is then ejected from the nozzles 10a and 10b, and after the molten solder is sprayed The twisted tube heat exchanger 1 is blown with hot air to remove excess molten solder and drop it into the solder bath 4 for recovery, and the water pipe 2 and the refrigerant pipe 3 are joined by soldering.

  Thus, in the manufacturing method of the torsion tube type heat exchanger of this embodiment, since the water pipe 2 and the refrigerant pipe 3 after the refrigerant pipe winding are immersed in the molten solder tank 4 for a certain period of time, the solder is not biased. Is prevented. At that time, even if the solder oxide adheres to the joint portion, the solder oxide attached to the joint portion can be washed away by spraying the molten solder 5 in the air, and can be replaced with the molten solder by spraying. It is possible to avoid the occurrence of problems such as a decrease in solder wetting and a decrease in heat conduction performance due to solder oxide remaining in the joint. In addition, after the molten solder 5 is sprayed, hot air is continuously sprayed onto the water pipe 2 and the refrigerant pipe 3 to remove excess molten solder. Therefore, the molten solder 5 is biased in the atmosphere. However, the adhesion of excess solder is prevented by blowing hot air immediately after that. As a result, an appropriate amount of solder is evenly supplied, so that the solder wettability between the water pipe 2 and the refrigerant pipe 3 is improved, which leads to the expansion of the heat transfer area between the pipes, and the heat transfer efficiency is improved. Improves the appearance of the design.

  By the way, the above-mentioned pretreatment for applying a flux for the purpose of removing the oxide film is performed in order to simplify the subsequent soldering process of the water pipe 2 and the refrigerant pipe 3 and eliminate the need for expensive equipment. However, in this embodiment, the guide 11 capable of removing the solder oxide formed on the surface of the immersion bath is provided on the side surface of the molten solder bath 4, and the subsequent solder coating process is a two-step process (immersion treatment → air Even if the solder oxide may adhere to the joint due to the immersion treatment, it is washed away by the molten solder spraying treatment in the air and replaced with the molten solder by spraying. Therefore, the pretreatment is not necessarily required.

  Moreover, in this embodiment, since the indirect heating system which installs the heater 6 in the outer periphery of the solder tank 4 is employ | adopted, the uniformization of the temperature in a solder tank and the lifetime improvement of the heater 6 can be made compatible.

Embodiment 2. FIG.
Figure 4 is a process diagram showing the manufacturing process of the torsion tube type heat exchanger according to the second implementation, in the drawing, the embodiment 1, the same parts of the embodiment described above are given the same reference numerals.

  As shown in FIG. 4, the manufacturing method of the torsion tube heat exchanger of this embodiment is such that after the refrigerant pipe 3A is wound around the spiral groove 2a on the outer periphery of the water pipe 2 (FIG. 4 (a)), the refrigerant pipe 3A is wound around the refrigerant pipe 3A. By injecting a high-pressure liquid (for example, refrigerating machine oil), expanding the refrigerant pipe 3A to improve the adhesion with the water pipe 2, and increasing the contact area between the pipes, the heat transfer effect is improved, and at the same time, FIG. The refrigerant pipe 3B expanded as shown in (b) and the water pipe 2 are mechanically joined.

  In the manufacturing method of the torsion tube heat exchanger of the present embodiment, a high-pressure liquid is injected into the refrigerant pipe 3A wound around the water pipe 2 that is a core pipe, and the pipe is expanded to be connected to the water pipe 2. Since the adhesiveness is improved, there is no damage in the water pipe 2 as in the case of expanding the pipe by injecting a high-pressure liquid into the conventional water pipe 2 side, and the deformation of the pipe is small. Improves reliability such as corrosion and pressure resistance during actual use.

  In addition, by using refrigerating machine oil as the injection liquid used for the liquid pressure expansion of the refrigerant pipe 3A, the problem of contamination to the refrigerant pipe does not occur, and the reliability during actual use is improved.

  Incidentally, the required pressure strength can be ensured by providing an expansion allowance in advance so that the thickness of the refrigerant pipe after expansion is 0.5 mm to 0.8 mm.

It is a schematic diagram which shows the apparatus used for the manufacturing method of the twisted tube heat exchanger which concerns on Embodiment 1 of this invention. It is process drawing including the pre-process which shows the manufacturing method of the twisted tube heat exchanger which concerns on Embodiment 1 of this invention. It is principal part sectional drawing which cut | disconnects and shows the torsion pipe | tube type heat exchanger manufactured with the manufacturing method which concerns on Embodiment 1 of this invention along the pipe axis of water piping. Method of manufacturing a torsional tubular heat exchanger according to the second implementation is a process diagram showing a.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Twisted tube type heat exchanger, 2 Water piping, 2a Spiral groove, 3 Refrigerant tube, 3A Refrigerant tube before liquid pressure expansion processing, 3B Refrigerant tube after liquid pressure expansion processing, 4 Solder tank, 5 Molten solder, 7a, 7b jet pump, 8a, 8b jet nozzle, 9 hot air, 10a, 10b hot air blow nozzle, 11 guide.

Claims (2)

A method of manufacturing a torsion tube heat exchanger in which a refrigerant pipe is wound around a water pipe provided with a plurality of spiral grooves on the outer periphery along the spiral groove, and then the water pipe and the refrigerant pipe are tightly joined. ,
A step of immersing the water pipe and the refrigerant pipe after winding the refrigerant pipe in a molten solder bath for a certain period of time;
A step of blowing molten solder in the atmosphere to the water pipe and the refrigerant pipe while pulling up the water pipe and the refrigerant pipe from the molten solder tank;
A step of removing excess molten solder by blowing hot air to the water pipe and the refrigerant pipe while further raising the water pipe and the refrigerant pipe to which the molten solder has been sprayed;
The manufacturing method of the twisted tube type heat exchanger characterized by having.   2. The method of manufacturing a torsion tube heat exchanger according to claim 1, wherein a flux is preliminarily applied to the water pipe and the refrigerant pipe immersed in the molten solder bath.

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