KR20090133005A - Apparatus and composite for flux coating of the heat exchanger tube - Google Patents

Abstract

PURPOSE: A flux coating method, a device thereof, and a coating composition are provided to coat the top and the bottom surfaces uniformly with one process, and to reduce the consumption amount of flux. CONSTITUTION: A flux coating method of a tube for a heat exchanger includes the following steps of: forming a mixture by mixing liquid solvent, flux, and a binder consisting of high polymeric resin; producing the metal alloy powder including the metal; transferring the mixture form a roller on a side to the roller on the other side; rotating the rollers to an opposite direction; and coating the surface of the tube with the mixture by contacting the tube(12) with a second roller.

Description

Flux coating method and apparatus and coating composition of tubes for heat exchanger {APPARATUS AND COMPOSITE FOR FLUX COATING OF THE HEAT EXCHANGER TUBE}

The present invention relates to a flux coating method and apparatus for tubes for heat exchangers.

The present invention relates to a flux coating method for tubes for heat exchangers. Heat exchanger tube is a product used in heat exchangers of automobiles and is mainly made of aluminum and refers to a device for transferring heat from a high temperature fluid to a low temperature fluid through a heat transfer wall.

Tubes generally used in heat exchangers of automobiles are called PFC (Parallel Flow Condense) tubes and are manufactured by extruding aluminum wire into a tube shape. To this end, aluminum is used as a raw material for the heat exchanger tube to remove foreign substances, and then extruded to produce a tube having a plurality of passages through which refrigerant flows. The heat exchanger is also manufactured by stacking the tubes thus prepared and adhering to the number of tubes pierced by the header.

However, the bonding between the tube and the header is performed by melting the bonding material coated on the tube or the header in a heating furnace. Conventionally, a solution of a solvent and flux (FLUX) is applied to the outside of the tube for such contact.

 However, when the coating is sprayed, the absolute amount of flux used increases, as well as the thickness of the coating film varies depending on the location due to the difficulty in controlling the thickness of the coated coating film.

To solve this problem, Japanese Patent Application Laid-Open No. 7-100635 applies a liquid paste mixed with a braze alloy powder and a flux to the surface of a part to be joined to dry it. However, in the case of using such a liquid paste, a separate drying process is performed. In many cases, defects occurred due to poor connection between parts.

Republic of Korea Patent Publication No. 10-2008-0025915 is to generate static electricity on the surface of the heat exchanger tube by the rotating friction of the electrostatic generating roller and flux powder is attached to the surface of the tube by the static electricity to form a coating film, but the first and second The coating film is divided and the thickness of the coating film is controlled by the thickness adjusting roller. However, since the patent uses a spray injection method, there is a lot of loss due to the injection and when the high-speed transfer is performed for a fast coating, there is a separate process for adjusting the spray injection amount and a configuration for generating static electricity is required. There was a downside.

An object of the present invention is to provide a flux coating method and apparatus capable of coating the upper and lower surfaces in one process while reducing the consumption of flux as devised to overcome the disadvantages described above.

In order to achieve the above object, there is shown a flux coating method of a tube for a heat exchanger and a coating composition and a flux coating apparatus, wherein the flux coating method is a powder form including a solvent in a liquid state and a metal serving as a material of the heat exchanger. Forming a mixture of a flux made of a metal alloy and a binder made of a high polymer resin;

Providing the mixture from one of the pair of rollers (first roller) rotated in opposite directions in contact with each other and transferring the mixture to the other roller (second roller); contacting the tube with the second roller; Coating the mixture on the surface of the tube by passing it through; It may include.

After the coating step may further include a drying step of vaporizing the solvent by exposing the tube to a temperature of 100 degrees to 200 degrees Celsius.

The tube is made of aluminum and the flux may be an alloy of aluminum and metal selected from any one of Zn and Si.

The ratio of the metal to be alloyed in the aluminum alloy may be 5 to 12 parts by weight based on 100 parts by weight of aluminum.

The flux may be 5 to 30 parts by weight based on the total weight.

The phase binder may be characterized in that 1 to 5 parts by weight based on the total weight.

 The binder may be PVA, acrylic, urethane.

 Blowing compressed air into the inside of the tube while transporting the tube; detecting a portion of the air leaking from the tube; marking the tube by dipping the detected portion into the tube It may further comprise the step.

In addition, the coating composition used for the tube for the exchanger, 65 to 94 parts by weight of the total weight of the liquid solvent and an alloy in the form of a powder of a metal and aluminum selected from any one of Zn, Si, 5 to a total weight It may include 1 to 5 parts by weight based on the total weight of the binder consisting of 30 parts by weight of the alloy in the form of powder, PVA resin in a liquid, solid state.

In addition, the flux coating device of the tube for the heat exchanger, a roller portion consisting of a pair of rollers which rotate in opposite directions in contact with each other, the lower end of one (first roller) is locked in the reservoir containing the coating composition and the other The roller (second roller) may be in contact with the first roller on one side and in contact with the tube for the heat exchanger conveyed toward the second roller on the other side; may comprise a roller.

 A compressor for blowing compressed air into the heat exchanger tube; A detection unit for detecting a break point from which the compressed air exits; A marking unit for pressing and displaying the detected break point.

A direction change roller for changing up and down the tube exiting the roller portion;

It may further include another roller for applying a coating composition on the upper surface of the tube is changed up and down.

 The surface of the second roller may be formed wrinkles in the longitudinal direction.

The invention as described above has the effect of providing a tube for a heat exchanger capable of adhering as necessary with a small amount of flux.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. 1 shows an example of a heat exchanger used in a motor vehicle. In the heat exchanger, the header 11 forms a hollow rod shape by welding a sheet of aluminum to form a sheet and makes grooves for coupling tubes to one surface.

Tube 12 is formed by extrusion as described above and is coupled to the groove formed in the header. The pin 13 is made of aluminum sheets to form a corrugation and is coupled between the tube and the tube, and the support 14 is installed at the upper and lower ends.

Each component used in the heat exchanger may be flux coated for the blazing joint. In the heat exchanger configuration, when the tube 12 is flux coated, the parts other than the header are less required to be coated.

Figure 2 shows a tube coated on both sides in accordance with the present invention. The inner core of the tube has a melting point of 630 degrees Celsius to 660 degrees Celsius, and the outer flux coating layer 22 has a melting point of 577 degrees Celsius to 610 degrees Celsius (when using a SI-based flux). If the blazing is performed at a temperature of about 605 degrees, the flux of the coating layer is melted while the core part remains intact to bond the tube and the header.

The slurry flux used here consists of a solvent, a flux powder, and a binder (solid, liquid).

The solvent may be water or an alcoholic liquid or a mixture of two or more of them, and the flux powder may be an alloy containing zinc or silicon-based metal or a mixture of the two, and the binder may be a polymer resin. It may be a solid polyvinyl alcohol (PVA).

The solvent may be included 65 to 94 parts by weight based on the total weight and the flux powder 5 to 30 parts by weight relative to the total weight of the remainder is composed of a binder may include 1 to 5 parts by weight relative to the total weight.

In this case, when the composition ratio of the binder is 1 part by weight or less, the viscosity of the flux is low, and the adhesion to the tube is lowered, and the ability to bond the flux to the tube is reduced. When the binder ratio is 5 or more, the manufacturing cost increases and the viscosity is too high. It becomes difficult and wear of related equipment occurs easily.

The flux powder may be an alloy containing zinc or silicon. If the metal used in the tube is aluminum, it may be an alloy of Zn-Al or Si-Al type and 5 to 12 parts by weight of Zn, Si. Based on the total weight of aluminum. It may be an alloy included. When the amount of the added metal of the alloy is less than 5 parts by weight, the melting point difference with the base metal is not very small, and if the weight of 12 parts by weight in many cases, the difference in melting point with the base metal is too much.

When the amount of flux powder is 5 parts by weight or less based on the total weight, the effect of coating the base metal is reduced, and the blazing bonding is less likely to occur. When the amount of the flux powder exceeds 30 parts by weight, excessive melting may occur and deformation may occur. Bring it.

The flux is used in the form of a slurry in which the flux powder and the binder are melted in the solvent, and the flux is coated on a tube or a fin at room temperature, dried, and then the solvent is vaporized and the binder is cured to fix the flux to the surface of the base material. In addition, during the brazing process, the flux begins to melt before the base material, but the binder is vaporized and flew before the flux melts, and the flux coating layer melts to adhere the base material and the base material. In addition, the composition of the solvent, the flux powder, and the binder is an optimal composition for coating using a roller.

Fig. 3 shows a roller configuration for flux coating, which drives two rollers 33 and 35 which rotate in opposite directions and has a reservoir for storing a slurry coating flux coating liquid at the lower end of one roller. As the roller 35 rotates, the flux coating liquid is buried on the surface of the roller and the coating liquid is transferred to the surface of the second roller 33 which rotates in the opposite direction and passes between the second roller and the third roller 32. The flux coating solution is applied to the surface of the substrate 31).

When the base tube is transferred using a roller, the direction of the base material can be easily reversed, so that both the upper and lower surfaces can be easily coated in one process. To this end, the roller assembly as shown in FIG. 3 is continuously installed, but the rollers are configured to change the direction of the base material so as to coat both the upper and lower surfaces.

This roll coating has less flux consumption than spray coating, and it is easy to interlock the feed speed of the base material and the roller speed, and even coating at high speed is possible.

Most preferably, 20 parts by weight of the flux of the silicon alloy, 5 parts by weight of the binder, and 75 parts by weight of the solvent are used to make a slurry. On the other hand, the spray coating should use at least 30 to 50 parts by weight of flux, and therefore, the binder should be mixed up to 5 to 10 parts by weight. Therefore, it is difficult to spray due to the relatively small amount of solvent. There are frequent drawbacks. However, the present invention can be applied with only about half of the flux powder compared to such a spray coating, and even double-sided coating becomes possible.

Various kinds of materials such as urethane and acryl can be used as the binder, but in case of using PVA, the binder is more suitable for flux than other binders and adheres well to the surface of the base material.

After the flux coating, the base material is dried at 100 to 200 degrees Celsius to free solvent and enter the brazing joint.

In addition, in the case of coating on the surface of the base material when there is a defect in the tube, such as the base material is conventionally marked on the surface of the base material, but when the base material is coated by the flux, these marking marks were often invisible. To prevent this, place the detector in front of or behind the roller body so that if a defective part occurs, you can immediately check the coating even if it is coated by putting out a gear mark that presses the part. If you put the detector in front of the roller body, the part is coated. You can prevent this from happening. To this end, the compressed air is blown into the inside of the tube to check whether the compressed air is leaking out, so that the marking can be made on the leaking out place.

4 shows a process for producing a tube from an aluminum source, including a flux coating. After washing aluminum raw material, it extrudes to make a tube shape, and after extrusion, it can be cooled quickly to maintain an extruded shape. The aluminum tube thus formed is subjected to flux coating using a roller, and the products such as headers are assembled together and then blown. The heat exchanger completes one heat exchanger.

Fig. 5 shows another embodiment of the second roller 33. The second roller can be wrinkled in the longitudinal direction on its surface in order to apply the flux under uniform conditions. Longitudinal folds allow the flux to be applied to the surface of the tube so that it has more flux on the surface so that it can be applied to the tube surface.

1 shows a heat exchanger made in accordance with the present invention.

Figure 2 shows the configuration of a heat exchanger tube made in accordance with the present invention.

3 shows a roller section for coating a heat exchanger tube according to the invention.

4 is a flow chart illustrating a process of manufacturing a heat exchanger tube in accordance with the present invention.

Claims (12)

Flux coating method of tubes for heat exchangers, Forming and providing a mixture of a solvent in a liquid state, a flux made of a metal alloy in the form of a powder containing a metal as a material of the heat exchanger, and a binder made of a high polymer resin; Providing the mixture from one of the pair of rollers (first roller) rotating in opposite directions in contact with each other and transferring the mixture to the other roller (second roller); Coating the mixture on the surface of the tube by passing the tube in contact with the second roller; Flux coating method of the tube for heat exchangers, including The method of claim 1, further comprising a drying step of vaporizing the solvent by exposing the tube to a temperature of 100 to 200 degrees Celsius after the coating step. The method of claim 1, wherein the tube is made of aluminum and the flux is an alloy of aluminum and a metal selected from any one of Zn and Si. According to claim 13. The ratio of the alloyed metal in the aluminum alloy is 5 to 12 parts by weight based on 100 parts by weight of aluminum, the flux coating method of the tube for heat exchanger. The method of claim 1, wherein the flux is 5 to 30 parts by weight based on the total weight, the flux coating method of the tube for heat exchanger. The method of claim 1, wherein the binder is 1 to 5 parts by weight based on the total weight, the flux coating method of the tube for heat exchangers. The flux coating method of a tube for heat exchanger according to claim 1, wherein the binder is any one of PVA, acryl, and urethane. The method of claim 1, further comprising: blowing compressed air into the tube while the tube is transported; Detecting a portion of the air leaking out of the tube; The method of flux coating of the tube for heat exchanger, further comprising the step of marking the tube to the detected portion. Coating composition used for the tube for heat exchanger, 65 to 94 parts by weight of the liquid solvent and An alloy in the form of a powder of a metal and aluminum selected from any one of Zn, Si, and 5 to 30 parts by weight of an alloy in the form of powder  Coating composition used for the tube for heat exchangers containing 1-5 weight part with respect to the total weight of the binder which consists of PVA resin in any state of a liquid and a solid state. Flux coating device of heat exchanger tube, A roller portion consisting of a pair of rollers which are in contact with each other and rotate in opposite directions, wherein a lower end of one (first roller) is immersed in a reservoir containing a coating composition and the other roller (second roller) is formed on one side of the roller. A roller part in contact with the first roller and in contact with the tube for the heat exchanger which is transferred toward the second roller on the other side; Flux coating apparatus for tubes for heat exchangers, including The compressor of claim 10, further comprising: a compressor for blowing compressed air into the heat exchanger tube; A detector for detecting a break point at which the compressed air comes out; A flux coating device for a tube for heat exchanger, further comprising a marking unit for pressing and displaying the detected breaking point. The method of claim 10, wherein the roller portion exited A direction change roller for changing up and down of the tube; Flux coating device of the heat exchanger tube further comprises a further roller portion for applying a coating composition on the upper surface of the tube is changed up and down 11. The flux coating apparatus of a tube for heat exchanger according to claim 10, wherein the surface of the second roller has wrinkles in a longitudinal direction.

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