JPS59197598A - Coating method for in-furnace soldering - Google Patents

Abstract

PURPOSE:To perform in-furnace coating soldering excellent in paint adhesiveness in good efficiency, by a method wherein a steel material is soldered in a high temp. furnace while the soldered material is heat treated to enhance the strength thereof and electrodeposition coating is succeedingly performed. CONSTITUTION:A steel material to be soldered is charged into the work charging chamber 2 of a soldering furnace 1 and transferred through a preheating chamber 2 by an endless conveyor 6 running in said chamber 2. After the steel material is preheated by the heater 302 in the preheating chamber 2, the preheated steel material is transferred through a heating chamber 4 and heated to 800-1,200 deg.C by a heater 402 to be subjected to soldering treatment. In order to enhance tensile strength lowered by this heat treatment, the heated steel material is cooled to 400-560 deg.C at once in a cooling chamber 5 by gas while the cooled steel material is charged into the cooling liquid 701 in a heat treatment chamber 7 and quenched to enhance tensile strength. Succeedingly, the steel material is drawn up from the heat treatment tank 7 by a conveyor 703 and, after drying by self-holding heat, passed through the aqueous paint 804 in the electrodeposition tank 803 of a painting apparatus 8 by a conveyor 9 to be subjected to electrodeposition coating while the paint is baked to the steel material in a baking chamber 805.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating method for furnace brazing of mild steel and alloy steel.

Furnace brazing of mild steel and alloy steel materials involves brazing the steel material in the furnace at 800%
℃ to 1200℃ and then left to cool down to room temperature in a furnace.However, in this conventional brazing treatment, the steel material before heat treatment, that is, the raw material. It had the disadvantage that its own tensile strength etc. deteriorated.

Therefore, in order to improve the above-mentioned shortcomings, we have developed a method to reduce the tensile strength by cooling alloy steel materials, etc., which have been heated to about 00°C to 560°C, and then rapidly cooling them from this temperature range. Japanese Patent Application No. 55-26597 (Japanese Unexamined Patent Publication No. 56-1233) describes a heat treatment method that improves the strength etc.
No. 22).

If heat treatment is performed after the above furnace brazing, the tensile strength etc. can be improved as described above, but on the other hand, the surface of the steel material will become rough due to rapid cooling, and if this surface is painted, surface irregularities may occur. Because of the large amount of paint, spraying requires a very thick coating to be formed by spraying, the painting process has to be done in multiple steps, which increases the number of steps, and a large amount of paint is required. It is disadvantageous.

The present invention has been made in view of the above.

The object of the present invention is to actively utilize the roughening of the surface of the steel material during quenching to achieve efficient and excellent coating film strength.
It is an object of the present invention to provide a coating method for furnace brazing that is excellent in paint economy, efficient, rational, and highly productive.

In order to achieve the above object, the present invention is to reduce the temperature of a steel material that has undergone brazing heat treatment to the heat treatment temperature, immerse it in a liquid bath to perform heat treatment, and then apply electrodeposition coating to the surface. shall be.

Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Although alloy steel will be described as an example of the present invention, mild steel can also be heat treated by setting the heat treatment temperature to the material.

As alloy steel, for example, Mn07~20qb,...COO
2 to 05%, the balance being Fe, and such an alloy steel is brazed in a furnace.

In brazing, a brazing material such as copper brazing or silver brazing material is interposed in the form of a paste between the joints of steel materials, and the brazing material is put into a heating furnace and heated at 800°C to 1200°C depending on the brazing material in a non-oxidizing atmosphere gas. ℃
Heat to melt the wax material and print it out.

The workpiece that has been subjected to brazing heat treatment at 800°C to 1200°C is forcedly cooled or allowed to cool to a heat treatment temperature of 4 in the example.
The temperature is lowered to 00° C. to 560° C., and from this temperature range, the workpiece is put into a treatment liquid provided downstream of the furnace and heat-treated.

Although water or the like is used as a treatment liquid, a chemical conversion treatment liquid suitable for pre-painting treatment is used in consideration of painting in the post-process, and a chemical conversion treatment liquid mainly containing MnP is used. It is preferable to input the workpiece, immerse it, and perform the chemical conversion film forming treatment at the same time as the heat treatment of the brazed workpiece.

If this chemical conversion treatment liquid is heated and maintained at 90°C to 98°C in its initial state, the treatment liquid will be kept warm by the heat retained by the workpiece, and no liquid heating device is required.

In this way, a chemical conversion coating treatment is performed as a pre-painting treatment at the same time as heat treatment, and when the workpiece is transported to the painting process after the treatment, the moisture on the workpiece surface is evaporated due to latent heat, and a drying process is not required, and the chemical conversion coating is formed. It will be formed on the work surface.

By the way, as mentioned above, the furnace brazing temperature is 800℃~1.
The workpiece is heated to 200°C, and this heating burns off deposits such as oils and fats on the surface of the workpiece, and the surface of the workpiece is purified in the waxing process, eliminating the degreasing process and allowing heat treatment and chemical conversion treatment to be performed.

As a result of the heat treatment described above, the surface of the workpiece becomes rough, and countless small depressions are formed on the surface, and the surface area of the workpiece becomes substantially thicker due to the roughening of the depressions.

The above workpiece is transported to an electrodeposition coating tank, and the workpiece is immersed in the tank to perform electrodeposition coating. In this case, as mentioned above, the surface of the workpiece is roughened by heat treatment, has a large surface area, has good electrical conductivity, and has a large coating area, so electrodeposition efficiency is high.
Effective electrodeposition coating can be performed, and the resulting electrodeposition coating has excellent rust prevention properties and can be used as a moss removing product. If a more aesthetic appearance is required, spray painting can be applied to the surface of the electrodeposited film.In this case, the rough surface during heat treatment is made smooth by the 6-coat film, so the spray painting process is shortened. You can finish it beautifully in a short amount of time.

In the above embodiments, the heat treatment was performed in a chemical conversion treatment tank, but instead of cooling, the heat treatment may be performed by rapidly cooling with water. In this case,
Rapid cooling with water can significantly shorten the cooling zone after furnace brazing. In this case, the workpiece may be drained and dried using the latent heat of the workpiece, then electrodeposited to perform a pre-coating and base coating, and then sprayed.

As described above, effective electrodeposition coating can be performed by utilizing the surface roughened by the heat treatment and rapid cooling after furnace brazing.

A specific apparatus for carrying out the above method will be explained with reference to the accompanying drawings.

The furnace 1 includes, from upstream, a workpiece input chamber 2, a preheating furnace 3 continuous to this, a heating furnace 4 continuous to this, and a furnace cooling chamber 5 continuous to this. A conveyor 6 is provided that communicates each of these areas, and the conveyor 6 has driving wheels 601 and guide wheels 6.
An endless conveyor driven by 02 etc. is adopted.

The workpiece input chamber 2 is equipped with a shutter 202 downstream of an inlet section 201 to partition a waiting chamber 203 downstream from the outside, and an exhaust section 204 for discharging waste heat gas from the inlet section 201 to the outside.
and a discharge section 204 for discharging exhaust heat gas to the outside from an inlet section 201, a workpiece is introduced into the most upstream part of the conveyor 6 from the inlet section 201, and the workpiece is conveyed to a waiting room 203. A shutter 205 is provided between the standby chamber 203 and the upstream part of the preheating furnace 3, and heaters 302 are buried in the ceiling and floor of the furnace body 301 of the preheating furnace 3. A conduit 303 for introducing a converted gas such as ammonia gas or propane into the furnace is installed to maintain the inside of the furnace in a non-oxidizing atmosphere. The shutter 205 is opened and the conveyor 6 transports the workpiece from the standby chamber 203 into the furnace, the workpiece is transported into the furnace 3, and the workpiece is preheated within the furnace 3.

Furnace body 401 of heating furnace 4 adjacent to furnace 3 (l-j:
Heaters 402 are embedded in the ceiling and floor, and the above gas is introduced into the furnace through a conduit 403 in the ceiling.

The workpiece preheated in the preheating furnace is transferred to the heating furnace 4, where it is heated to 800°C to 1200°C and subjected to furnace waxing.

A cooling pipe 502 is provided on the ceiling of the furnace body 501 of the furnace cold chamber 5 provided adjacent to the heating furnace 4, and the conveyor 6
The brazed workpiece sent from the heating furnace 4 is cooled, and the temperature of the workpiece, for example, the aforementioned alloy steel, is lowered to 400°C to 560°C by forced cooling using a cooling fan or the like. A shutter 503 is provided at the downstream portion of the furnace cold chamber 5.

A discharge chamber 504 facing the most downstream part of the conveyor 6 is defined on the downstream side of the furnace cold chamber 5 divided by the shutter 503, and the discharge chamber 504 has an exhaust gas discharge section 505 on the ceiling and is erected. A heat treatment tank 7 partitioned by partition walls 506 is provided directly connected to the discharge chamber 504. A part of the ceiling of the discharge chamber 504 is extended downward diagonally to the downstream side so that the lower end of the extension part 507 enters into the level of the liquid 701 stored in the tank γ, and a guide is provided on the upstream side of the tank 7. A plate 702 is provided, and a conveyor 703 is provided extending from below the plate 702 to the downstream side.
04 inside the liquid 701, and the downstream part 706 faces the outside through the inclined intermediate part γ05.

The liquid in the above heat treatment tank 7 yen is water or a chemical conversion treatment liquid, into which the workpiece whose temperature has been lowered in the furnace cooling chamber 5 to the heat treatment temperature is placed and immersed.
Rapidly cool and heat treat. The workpiece is carried outside by a conveyor 703.

A coating device 8 is continuously provided downstream of the tank 7, and a conveyor 7
The downstream part 706 of 03 faces the defined drying chamber 801, and the work is dried in the drying chamber 801 by its latent heat, and the waste heat discharged from the discharge part 505 is transferred to the drying chamber 801 through piping. It may be supplied internally.

Dry? A hanging chamber 802 is provided adjacent to the hanging chamber 801, the upstream part 901 of the hanging conveyor 9 is set on the ceiling of this chamber, and an electrodeposition tank 803 is connected to the downstream of the hanging chamber 802. A water-based paint 804 is stored in the tank 803 , an intermediate portion 902 of the conveyor 9 faces above the tank 803 , and a downstream portion 7 of the conveyor 703 faces the intermediate portion 902 of the conveyor 9 .
The work on 06 is hung on the upstream part 901 of the hanging conveyor 9 in the hanging chamber 802, and is conveyed in the direction of the tank 80.3.
Keeping the workpiece at one pole and the paint 804 at the other hardness,
The workpiece is immersed in the paint 804 and electrocoated, and as described above, the surface of the workpiece is roughened by the heat treatment9, allowing efficient painting.

A baking chamber 805 is provided downstream of the toner tank 803, in which the downstream part 903 of the conveyor 9 is dimensioned, and after electrodeposition, the baking chamber 805 is
The + workpiece is transported to the baking chamber 805 and baked.

Details of the above: According to the present invention, furnace brazing,
Since the heat treatment is performed continuously and the roughened work surface obtained by the heat treatment is actively used for electrodeposition coating, it is possible to perform coating with high efficiency and excellent paint economy. A rational integrated production line of coating, heat treatment, and painting can be obtained, which is advantageous in terms of productivity, equipment, etc.

[Brief explanation of the drawing]

The drawings are explanatory diagrams showing an example of an apparatus for implementing the present invention. In the drawing, 1 is a wax housing, 4 is a heating furnace, 5 is a furnace cold room, 7 is a processing tank, and 803 is an electrodeposition tank. Patent applicant Honda Motor Co., Ltd.

Claims (1)

[Claims] Steel materials that have been subjected to brazing heat treatment in a furnace with a non-oxidizing atmosphere are cooled down to the heat treatment temperature, then immersed in a treatment tank containing water or the like for heat treatment, and then electrodeposition coating is applied to the surface of the heat treated steel materials. A coating method for furnace brazing, which is characterized by: