JPS594510B2 - Surface treatment method and surface treatment equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface treatment method useful for surface treatment such as phosphate treatment, which is mainly used for pre-painting treatment of automobile bodies, etc., for rust prevention, and to the surface treatment method. It concerns the equipment used.

20 Conventionally, most of this type of treatment has been carried out by bringing a phosphoric acid treatment solution (hereinafter referred to as treatment solution) into contact with the surface of the object to be treated. There are two methods for bringing the treatment liquid into contact: one is to spray the treatment liquid onto the surface of the object to be treated, and the other is to immerse the object to be treated in the treatment liquid.

The former treatment method is used, for example, when the object to be treated has a complex shape such as an automobile body, there are many parts where the treatment liquid is difficult to spread around, especially box-shaped parts such as fenders, doors, members, etc. hardly ever comes into contact with the inner surface. Therefore, it is not possible to prevent areas that are insufficiently surface-treated or areas that have not been surface-treated at all from remaining. In the latter treatment method, compared to the former treatment method, the treatment liquid penetrates into the inner surface of the box-shaped area, so it is less likely that insufficiently treated areas or untreated areas will remain. In the process of immersing objects, liquid level marks may remain and become stepped. often do not contact the surface uniformly.

The object of the present invention is to improve the above-mentioned drawbacks of the prior art and to uniformly perform surface treatment.

Therefore, the gist of the present invention is to provide the processing liquid with a flow opposite to the moving direction of the processing object when the object to be processed is immersed in the processing liquid.

The present invention will be explained with reference to an embodiment shown in the drawings.

This embodiment relates to a zinc phosphate film treatment as a pretreatment for painting an object to be treated, such as an automobile body. In the zinc phosphate film treatment, the object to be treated is first degreased with trichlorethylene, alkaline solution, etc., then washed with water, and then brought into contact with an aqueous titanium phosphate solution to form nuclei of phosphate film crystals on the surface of the object to be treated. The workpiece 1 that has been subjected to such surface treatment is moved while being suspended from the conveyor 2, and is immersed in the treatment liquid 4 from the left end of the dipping tank 3 in FIG. In the front part of the immersion tank 3, the processing liquid is injected onto the object 1 from one or both of the risers 5A and 5B, one of which exits from the processing liquid 4 and the other of which is submerged in the processing liquid 4. The riser 5A is set within 30 seconds before the object 1 is immersed in the processing liquid 4, and the riser 5B is set within 30 seconds after the object 1 is immersed in the processing liquid 4. Attach multiple injection nozzles to the riser in a direction perpendicular to the length direction and parallel to the liquid surface.
The pressure of the processing liquid injected from the injection nozzle toward the object to be processed is 0.409/c! as the pressure received on the surface of the object to be processed! l or more, preferably 1.09/o! il or more. It is desirable that the treatment liquid be injected from the risers 5A and 5B onto the object 1 to be treated, at least from either one. If the processing liquid is not sprayed at the front stage, traces of the liquid level may remain and the object to be processed 1 may be exposed to the processing liquid 4.
Contact with the mist, vapor, etc. of the treatment liquid 4 in the air before immersion in the treatment liquid 4 may cause problems such as the formation of a bluish iron phosphate film on some parts. Also. The pressure received by the sprayed treatment liquid on the surface of the workpiece. If it is less than 0.4g/(:!l), it is not preferable because the non-uniform flow of the treatment liquid will cause uneven spraying on the film and unevenness in the flow of the liquid level.Especially when the surface of the object to be treated is poorly wetted, the riser 5A The reason why the riser 5A is positioned within 30 seconds before the immersion of the workpiece 1 is because the workpiece 1 is injected into the air for at least 30 seconds after the process liquid is jetted onto the workpiece r. If so, the zinc phosphate crystals formed on the surface of the workpiece 1 are bulky HOpe.
It becomes a mixed crystal of it and PhOsphOphylite, and has low corrosion resistance, but within 30 seconds, the zinc phosphate crystals become a minute Ph
The crystal is mainly composed of OsphOphylite, and the corrosion resistance is improved by about 1.5 times compared to the former case. Also riser 5
The reason why the position B was set within 30 seconds after the immersion of the object 1 to be treated is because
If the wettability is poor due to residual oil etc. on the surface of the workpiece, or if the workpiece comes into contact with mist vapor etc. of the workpiece 1 or treatment liquid 4 in the air before being immersed, the surface may become bluish due to chemical changes. , If the receiving pressure due to the liquid injection onto the treated object is at least 30 seconds after immersion when rust has just started, the PhOsphO will be uniform and good.
It becomes a crystal mainly composed of phylite. If immediately after soaking 3
If no processing liquid is sprayed during 0 seconds, the received pressure is 0.
019/0171 or less, and if the treatment liquid is not sprayed at all towards the object to be treated, it is also 0.19/d.
As a result, uniform film crystals cannot be obtained. The workpiece 1 immersed in the treatment liquid 4 from the front part of the immersion tank 3 is transferred toward the rear stage, and during this time zinc phosphate crystals grow to cover the entire surface of the workpiece 1. time is 60
~300 seconds.

An overflow section 3A is provided at the front end of the immersion tank 3, and the processing liquid 4 overflows from the overflow section 3A into a receiving tank 6 and is stored there. A shielding plate 6A is provided at the upper part of the receiving tank 6 to prevent the mist and vapor of the processing liquid 4 from coming into contact with the object 1 to be processed. The processing liquid 4 stored in the receiving tank 6 is heated to a predetermined temperature by a pump 8 from a reflux path 7 via a heat exchanger 9 having a heat medium path 9A, or after heat exchange. The water is returned to the risers 5A, 5B and the riser 10 located at the bottom of the soaking tank 3 from the bypass path 7B that passes through the vessel 9. Thus, the treatment liquid 4 in the immersion tank 3
is given a flow opposite to the moving direction of the object 1 to be processed, so that the processing liquid 4 is brought into uniform contact with the object 1 to be processed. It is desirable to set the relative speed between the object 1 and the treatment liquid 4 to about 3 to 8 m/min from the viewpoint of uniformity of the concentration of the treatment liquid, uniformity of the zinc phosphate film, and economical aspects. Here, the reason why the relative speed was set to 3 m/11 or more was to make the processing liquid concentration and temperature uniform.
This is to make the phosphate film uniform, and the speed is 3m/min.
In the following cases, the uniformity of the treatment liquid concentration is particularly lacking, and the amount of liquid in the vicinity of the surface to be treated is small, so that only a non-uniform film can be obtained. In addition, the reason for setting the speed to 8 m/min or less is that if the relative velocity is increased more than this, the resulting phosphate film will contain a little more HOpeit and have poor corrosion resistance, and it may be necessary to reflux the processing solution. This is because the amount of energy that is not available is undesirable from an economic point of view.

A riser 11 is provided at the latter stage of the immersion tank 3, and a treatment liquid is supplied through a path 7A branched from the reflux path 7, and the treatment liquid is sprayed from the riser 11 to wash off the sludge adhering to the object to be treated 1. and heat recovery.

Next, the object 1 to be treated is washed with water by the washing riser 12 to wash away residual sludge, and the object 1 is cooled and prevented from drying by recovering heat. The main component of the zinc phosphate film formed on the surface of the object to be treated 1 is fine PhOsphO-Phylite, which has excellent corrosion resistance, and the zinc phosphate film is uniform regardless of the shape or location of the object to be treated. generate. As described above, when the object to be treated is immersed in the treatment liquid, the treatment liquid is sprayed onto the object to be treated immediately before and/or immediately after, so liquid surface marks remain and undesirable secondary surface treatment is caused. Since the processing liquid is supplied with a flow opposite to the moving direction of the processed object, the processing liquid comes into contact with the surface of the processed object regardless of the shape or part of the processed object, resulting in uniform surface treatment. Since the processing liquid is injected onto the processing object immediately after the processing object is taken out from the processing liquid, sludge removal from the processing object and heat recovery can be performed efficiently.

[Brief explanation of the drawing]

The figure shows one embodiment of the present invention, and FIG. 1 is a system diagram showing a surface treatment method using the surface treatment apparatus according to the present invention. In the figure, 1...Product to be treated, 3...Immersion tank, 3A...Overflow part, 6...Receiving tank, 7
...reflux route.

Claims (1)

[Scope of Claims] 1. In a continuous immersion phosphate treatment method in which the object to be treated is immersed in the phosphate treatment solution while being moved, within 30 seconds immediately before the object to be treated is immersed in the phosphate treatment solution; /Or within 30 seconds immediately after, spray the phosphate treatment liquid toward the object to be treated so that the pressure of the phosphate treatment liquid on the object to be treated becomes 0.4 g/cm^2 or more. When moving an object while immersing it in the phosphate treatment liquid, the flow of the treatment liquid is applied so that the relative velocity of the flow opposite to the moving direction of the object is 3 to 8 m/cm. Processing method. 2. A dipping tank filled with a phosphate treatment solution, and an injection riser extending from the phosphate treatment solution on both sides of the tank and parallel to the surface of the phosphate treatment solution at the front stage of the dipping tank, and/or A phosphate treatment system in which a plurality of injection nozzles are installed on the riser so that the phosphate treatment solution can be sprayed toward the object to be treated in a direction perpendicular to the length of the riser and parallel to the liquid surface. A liquid injection device, an overflow part provided at the front end of the immersion tank, a receiving tank for receiving the phosphate treatment solution overflowing from the overflow part, and a immersion tank for transferring the phosphate treatment solution from the reception tank. A phosphoric acid treatment device consisting of a reflux path for refluxing the phosphoric acid.