JPS6317911B2 - - Google Patents

Description

[Detailed Description of the Invention] Steel strips after cold rolling are usually passed through an electrolytic cleaning line (hereinafter referred to as electrolytic cleaning line) in order to completely remove the rolling oil adhering to the surface and prevent the formation of carbides in the next annealing process. ). As shown in FIG. 1, the electrolysis line is chemically degreased in an alkaline degreasing bath 2, mechanically degreased in a brushing device 3, electrochemically degreased in an electrolytic bath 4, followed by hot water washing in a hot water bath 5, and then a dryer 6. It consists of drying.

Generally, since cold rolling requires intense plastic working, rolling oil with good lubricity is used.
The steel strip wound into a coil after cold rolling is
The temperature has risen to around 100℃, and due to a thermochemical reaction between the rolling oil remaining between the steel strips and the steel base, black or purple iron oxide, known as oil burn-in, forms spots along the entire length of the steel strips. Easy to generate. Although this oil burning is reduced by the reduction effect of annealing, it still remains, making it unsuitable for applications with severe surface textures.

The conventional oil seizure prevention method is as follows.

(b) Strengthen rolling oil management to prevent rolling oil deterioration.

(b) Change the rolling working conditions in order to lower the steel strip temperature.

(c) In order to remove the rolling oil remaining between the steel strips, the drainage of the rolling oil will be strengthened.

(d) In order to quickly stop the formation of oil burning caused by the reaction between rolling oil and the steel base, the electrolytic line setup time will be shortened.

Although the above measures were taken, there were limits to measures (a), (b), (c), and (d) during on-site work, and it was not possible to completely prevent oil seizure. In order to remove the oil build-up that occurred, conventionally a polishing line equipped with a Scotchi brush was used to polish the steel strip surface several microns to remove the oil build-up, but in order to completely remove it, the line speed was increased to 10 to 20 m. / minute, reducing work efficiency and causing a large amount of oil-scorched coils, often resulting in missed product delivery deadlines, causing a great deal of inconvenience to users. Furthermore, there remains the problem that the removal efficiency of oil stains decreases due to uneven polishing due to brush wear, and the development of a new oil stain removal method to replace the above-mentioned polishing method has been awaited.

The present invention was made to eliminate the drawbacks of the prior art, and its gist is a method of removing oil scorching using an acid solution immediately before an alkaline degreasing tank in an electrolytic line after rolling. This will be explained in detail below. Previous knowledge in the field has been that oil stains can be chemically decomposed and removed with acid, but the general view is that after removal, the residual acid causes corrosion and that it is out of the question to apply it to actual production lines. It was hot.

The present invention compensates for the above-mentioned drawbacks by applying an acid solution immediately before the electrolytic line alkaline degreasing tank to remove oil stains, and neutralizing the remaining acid solution with an alkaline solution to eliminate the effects of the acid. The purpose is to obtain a stable steel strip without oil seizure.

The configuration of the present invention will be explained based on examples.

FIG. 2A shows an acid solution application method using a pair of rubber pinch rolls, in which the steel strip 1 is pinched between rubber rolls 8a and 8b just before the alkaline degreasing tank 2, and the acid in the storage tank 10 is The liquid 9 is sprayed with a spray 12 via a pump 11 onto the front surface 1a of the steel strip 1 on the entrance side of the upper rubber roll 8a, and the acid liquid 9 is also introduced onto the circumferential surface of the lower rubber roll 8b in the storage tank 10. By bringing it to the side and applying it to the back surface 1b of the steel strip, the acid solution attached to the steel strip continuously removes the oil buildup through a chemical reaction just before entering the alkaline degreasing tank 2, and then removes any remaining oil. The acid solution is completely removed by a neutralization reaction with the alkaline solution in the alkaline degreasing tank 10, and thereafter degreasing is completed by normal electrolytic cleaning. Examples are shown below.

Example: The sample material is carbon tool steel, SK5, with dimensions 1.0 x 950 mm.
×Coil. The acid solution is phosphoric acid with a concentration of 50%. The rubber material is neoprene. Spray is 20/min and line speed is 200m/min. Oil burn-off time is 0.5 seconds. The oil stain removal rate is 100%, and there are no traces of oil stains on the electrolyzed surface. There was no effect on the alkaline solution, and the alkaline concentration did not change at all. Furthermore, spray 12
The spraying position may be applied directly to the roll, or may be applied to both the steel strip surface and the roll.

As another example, FIG. 2B shows an example in which the steel strip 1 is pressed between a pair of pads 13a and 13b to which a nonwoven fabric is attached, and the acid solution 9 is sprayed onto the steel strip 1 using sprays 12a and 12b to remove oil burning. The oil burn removal rate is 100%, the same as in the case of rubber rolls, and other working conditions remain unchanged.

The equipment used is all made of acid-resistant materials, and does not degrade the working environment due to fumes, etc.
The type and concentration of acid were selected taking into consideration the effect on the degreasing solution and alkaline degreasing solution, as well as ensuring that the line speed would not decrease.

Because the present invention has the above-mentioned configuration, it can be installed on an existing line with limited space with a minimum amount of investment, and by adopting the method of the present invention, oil seizure can be completely eliminated, improving quality and speed. It has become possible to make a great contribution to the school's progress. Furthermore, by using the present invention, surface defects such as rust and temper color on the surface of the steel strip can be completely removed, so the present invention can be used in a wide range of applications and has tremendous effects.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the entire electrolytic cleaning line. FIG. 2A shows one embodiment of the invention, and FIG. 2B shows another embodiment of the invention. 1... Cold rolled steel strip, 2... Alkali degreasing tank, 3... Brush device, 4... Electrolytic bath, 5... Hot water, 6... Dryer, 7... Welding machine, 8... Rubber roll, 8a... Upper rubber roll, 8b... Lower rubber roll, 9... Acid liquid, 10... Storage tank, 11...
Pump, 12...Spray, 12a...Upper spray, 12b...Lower spray, 13a...Upper pad, 13b...Lower pad.

Claims (1)

[Scope of Claims] 1. A method for removing oil scorching from a steel strip, which comprises applying an acid solution to the steel strip immediately before entering an alkaline degreasing tank when cleaning the cold rolled steel strip in an electrolytic cleaning line. 2 The method of applying the acid solution is to install a pair of rubber pinch rolls just before the alkaline degreasing tank and pinch the steel strip.
A patent claim in which the acid solution in the storage tank is sprayed onto the front surface of the steel strip on the entrance side of the upper rubber roll, and is also brought to the entrance side along with the circumferential surface of the lower rubber roll and applied to the back surface of the steel strip. The method described in item 1.