JPH08229671A - Brazing residual flux removing method - Google Patents

Abstract

PURPOSE: To perfectly remove flux remained in a brazed product. CONSTITUTION: The product brazed with use of a borax-boracic acid flux for brazing filler metal or solder is bathed in 80-85 deg.C alkali degreasing warm bath for >=10min. In successively executing plating to a brazed product, it is bathed in alkali degreasing warm bath at this temp. for >=15min, by eliminating alkali degreasing process in plating pretreatment process, plating is executed. The higher warm bath temp. is, the higher effect in flux removing alkali degreasing warm cleaning has, but in the case of >=85 deg.C, a cleaning component in warm alkali degreasing warm bath is evaporated, 80-85 deg.C is taken as practical range, the time required for flux removing under this temp. condition is good enough by 10min, in the case it serves alkali degreasing of pretreatment of plating as well, it is set to >=15min in order to improve surface quality of plated product.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing flux remaining in a product after brazing.

[0002]

2. Description of the Related Art Brazing has been known for a long time as a method of joining metal parts together.
A brazing flux is used to dissolve or peel off the base material and oxides on the surface of the molten brazing material. Flux for brazing is roughly classified into soft brazing and hard brazing,
For soft solders, rosin, zinc chloride,
Borax is used for hard brazing.

FIG. 2 shows an example of hard brazing, and FIG. 3 shows a work process for brazing the pipe 2 to the metal part 1 and a part of the subsequent plating process. First, the pipe 2 is set on the joint part of the metal component 1 using a welding jig, and flux is applied to the brazing part 3 in # 1. In this work, borax or / and boric acid dissolved in water is applied with a brush. In # 2, a brazing filler metal such as silver brazing filler or brass brazing filler is melted with a gas burner to braze the brazing portion 3. After the brazing material has hardened, the brazing portion is visually inspected.

The brazed product that has been inspected is put into a wire mesh bucket and placed in a hot water bath at # 3.
Wash in hot water temperature of -60 ° C for 5 minutes or more, and pull the bucket out of the bath to remove the brazed product. This completes the normal brazing process, but when plating this brazed product, transport the brazed product to the plating factory, perform # 4 alkali degreasing as a pretreatment process for plating, and then wash with water. , Pickle and then plate.

In Japanese Patent Application Laid-Open No. 57-209772, a metal brazing plate is attached to one surface of a plate-shaped metal material with a flux and rolled to a desired thickness, which is embossed to form a pattern piece. There is described a simple metal brazing method in which a pattern piece is placed on a base material, heated and brazed, put in vinegar, and boiled to dissolve excess flux to remove stains.

[0006]

The brazing flux is somewhat corrosive in nature, and its removal is important as the final step of brazing.
In brazing of pipes and the like that require watertightness and oiltightness, insufficient removal of residual flux may cause an accident such as oil leakage. In addition, borax-boric acid-based flux for hard solder cannot be removed sufficiently by a mechanical removal method such as a normal wire brush or sandpaper because the residual flux becomes glassy, and plating is performed in a later step. In this case, the plating is poor and the surface quality is poor. In particular, when the flux buried in the brazing material in the brazing part cannot be removed and engine parts are used,
When the engine is operated, the flux embedded in the brazing filler metal will melt out, leading to an oil leak.

Therefore, by improving the hot water washing process shown in # 3 of FIG. 3, as shown in FIG. 4, the inspected brazing product W is put into a wire mesh bucket 6 and the bucket is washed in a hot water bath. Although it was immersed in hot water temperature 5 of 60 ° C. of No. 4 and rocked up and down 125 times in 5 minutes, flux removal was still insufficient. Further, in the hot water washing step shown in # 3 of FIG. 3, when hot water washing was performed at a temperature of 81 ° C. or higher for 30 minutes, 90% of the flux could be removed, but it was still insufficient and it took time. The number of man-hours increases by passing.

The method disclosed in Japanese Patent Laid-Open No. 57-209772 mentioned above is such that the brazed product is put in vinegar and boiled to dissolve excess flux to remove stains. There is no description of specific temperature and time, and the degree of flux removal is not disclosed.

According to the present invention, it is possible to remove nearly 100% of the flux remaining in the brazed product, prevent product defects due to the residual flux, and, when plating the brazed product, pretreatment of the plating process. In the alkaline degreasing process required as a product, it is possible to double as a hot water washing process for residual flux removal, and when viewed as a series of brazing-plating processes, a brazing residual flux removal method that can shorten the process It is intended to provide.

[0010]

According to the present invention, a product brazed with a hard solder and a borax-boric acid-based flux for hard solder is used in an alkaline degreased water at 80 to 85 ° C for 10 days.
This is a brazing residual flux removal method in which it is rinsed with hot water for more than one minute. When the brazed product is subsequently subjected to a plating treatment, it is rinsed in alkaline degreased hot water at the above temperature for 15 minutes or more, thereby omitting the hot water washing step in the conventional plating pretreatment step and performing the plating.

[0011]

In the alkaline degreasing hot water washing, the higher the hot water temperature is, the more effective the flux is. However, since the washing components in the alkaline degreasing hot water evaporate at a temperature of 85 ° C. or higher, it is practically 80 to 80%.
The temperature is set to 85 ° C, and the time required for flux removal under the above temperature conditions is 10 minutes, but if it also serves as alkaline degreasing for the pretreatment of plating, it will take 15 minutes or more to improve the surface quality of the plated product. And

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention and shows a part of a brazing process and a subsequent plating process. In FIG. 1, the process until the product after brazing is put into the bucket is basically the same as the conventional work process shown in FIG. 3, but a supplementary explanation will be given. In the flux application of # 1, borax or / and boric acid dissolved in water was applied with a brush, and in the brazing step of # 2, borax or / and boric acid was further dissolved in methyl alcohol (trimethyl ester). (Boric acid) is vaporized together with the gas burner and sprayed so that the flux penetrates deeply into the brazing surface.

The # 3 alkaline degreasing hot water washing in FIG. 1 is shown as a step of continuously plating the brazed product. However, in the case of a non-plated product, as the final step of the brazing step, the next shower water washing is performed. You can stop with. As an alkaline degreasing agent, 60 g of caustic soda as a main component, and a powder obtained by adding a chelating agent, a surfactant and an alkali builder as an additive to 60 g of the powder were dissolved in 1 liter of water (Japan Surface Treatment Chemical Co., Ltd.). Made by Clean Eight #
Using 8), wash with hot water at 81 to 83 ° C. for a standard time of 15 minutes.

Regarding a product requiring airtightness in which a pipe is brazed to a metal part, an oil leak or water leak accident of 0.03% occurs annually in the product manufactured by the conventional process shown in FIG. 3, but by the process of the present invention. No such accident has occurred in the product. In addition, when viewed as a whole of a series of brazing process-plating process, the conventional # 3 hot water washing process and # 4 alkali degreasing process shown in FIG.
Since it will also be used in the alkaline degreasing hot water washing step of 3,
The process could be omitted, and the plated product had good adhesion and good gloss.

Regarding the # 3 alkaline degreasing hot water washing of FIG. 1, when the hot water temperature was gradually raised from the conventional temperature of 60 ° C. and the effect of flux removal was confirmed, it was found that the higher the temperature, the better the effect. Since the cleaning components in the alkaline degreased water evaporate when the temperature is 85 ° C or higher, 81 to 83 ° C is most suitable for stable use, and 80 to 8 ° C is preferable.
There is no practical problem even in the range of 5 ° C. The time required for flux removal under the above temperature conditions is 10 minutes, but when it also serves as alkaline degreasing for the pretreatment of plating, it is preferably 15 minutes or more to improve the surface quality of the plated product. Become.

[0016]

According to the present invention, it is possible to remove almost 100% of the flux remaining in the brazed product and prevent product defects due to the residual flux. In addition, when the brazing product is continuously plated, it is possible to combine hot water washing with the alkaline degreasing process required as a pretreatment of the plating process, and the process can be shortened as a whole series of brazing-plating process. It is possible to obtain good surface quality of plated products.

[Brief description of drawings]

FIG. 1 is a process drawing of an embodiment of the present invention.

FIG. 2 is a plan view showing an example of a brazed product.

FIG. 3 is a cross-sectional view of a hot water washing device.

FIG. 4 is a diagram showing a part of a conventional brazing process and plating process.

[Explanation of symbols]

1 Metal parts 2 Pipe 3 Brazing part 4
Hot water tank 6 wire mesh bucket

Claims (2)

[Claims] 1. A brazing residue characterized in that a product brazed with a borax-boric acid-based flux for hard brazing and hard brazing is washed with alkaline degreased water at 80 to 85 ° C. for 10 minutes or more. Flux removal method. 2. A hard solder and a product brazed with a borax-boric acid-based flux for hard solder are rinsed in alkaline degreased hot water at 80 to 85 ° C. for 15 minutes or more, and subsequently plated on the product. The brazing residual flux removing method according to claim 1, wherein when performing the treatment, the hot water washing step is omitted because it is performed in the alkaline degreasing step which is a pre-plating step also as the hot water washing step after brazing.