JPH01273607A - Method and device for processing hot rolled alloy steel strip - Google Patents

Abstract

PURPOSE:To increase a descaling efficiency and to improve the quality of the steel strip surface by grinding by the grinding rolls of different abrasive grain count levels in two stages between the mechanical processing stage and pickling process stage of the line inside of a hot rolled alloy steel trip. CONSTITUTION:Distorsion is given to the scale of the surface of hot rolled alloy steel strip 1 by the mechanical processors 4, 5 of a tension leveller, shot blasting, etc., first and the removal of a scale is facilitated by generating a crack and peeling off on the scale thereof. Grinding is executed then up to the metal base just under the scale of the hot rolled alloy steel strip 1 by using a 1st grinding roll 6a whose abrasive grain count is in the range of No. 46-100 at the beginning. In succession the dressing of the grinding face is executed by using a 2nd grinding roll 7a whose abrasive grain count is in the range of No. 80-400 and of the abrasive grain count smaller than or equal to the abrasive grain count of the 1st grinding roll 6a. Thereafter, the operation of pickling treatment is continuously performed in one line. As a result, the cost reduction due to the quality improvement of the surface, the drastic contraction of the pickling treatment stage, the service life extension of pickling liquid, etc., is enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is directed to the surface treatment of a hot-rolled alloy steel strip, which is mainly composed of Ni and/or Cr and Fa, such as stainless steel or 42% nickel steel, and which is hot-rolled. When removing scale generated during hot rolling and surface flaws generated during hot rolling, it is possible to improve the quality of the surface of the hot rolled alloy steel strip, significantly reduce the pickling process, and reduce costs by extending the life of the pickling solution. The present invention relates to a method and apparatus for processing hot-rolled alloy steel strip.

[Conventional technology]

In the manufacturing process of hot-rolled alloy steel strips such as stainless steel strips, scale (w) is formed on the surface layer of the steel strip by hot rolling, etc.
Since iron oxide (i-band layer) and surface flaws occur, a process is required to remove these and finish the surface. Various methods have been implemented and proposed to date. Among these methods, the representative method that has been practiced for a long time is to apply mechanical processing such as scale breaker and shot blasting to the steel strip to cause cracks and peeling of the scale, and then to use hydrochloric acid or sulfuric acid. In this method, descaling treatment is carried out using a pickling treatment tank such as a mixed acid of nitric acid and hydrofluoric acid, and then surface flaws on the surface layer of the steel strip are removed by polishing using a polishing machine that is usually installed on a separate line.

However, in such a conventional method, since it is necessary to pass the plate through two lines, which are separately arranged, an annealing pickling line and a polishing line, there is a problem in that productivity is extremely low. In the annealing and pickling line, most of the scale is removed by pickling treatment, which is extremely inefficient and requires large-scale pickling equipment, as well as the resulting large amount of There have been various problems in terms of cost and labor saving in terms of waste pickling solution treatment. In addition, in polishing lines for removing surface defects, the mainstream method is to polish the surface of the steel strip with a rotating endless belt, but this method has a short belt life, requires high polishing costs, and requires frequent belt polishing. There were problems such as poor workability due to the need for replacement and low productivity (polishing speed).

[Problem to be solved by the invention]

Therefore, in order to increase the scale removal efficiency and improve the surface quality of the steel strip, the present applicant installed a plurality of pickling treatments after a mechanical treatment device consisting of a scale breaker 4' as shown in Fig. 2. We proposed an apparatus for removing scale from stainless steel strips, which includes tanks 8' and 8', and a grinding device between the pickling tanks 8' and 8'' to mainly remove metal residues, smut, etc. (Refer to Japanese Unexamined Patent Publication No. 59-41482).

However, although the scale removal device proposed in JP-A-59-41482 improves the quality of the surface of the copper strip to some extent, there is a limit, and the scale removal device proposed in JP-A No. 59-41482 has a limit. Since most of the removal is done by pickling, it is necessary to install multiple large-scale pickling tanks, which requires expensive equipment costs and a large amount of pickling solution and its waste liquid treatment. There was a problem that management required a large amount of cost. In addition, since the grinding equipment installed between the pickling tanks does not actively remove surface flaws from the steel strip, the copper strip passed through the annealing pickling line is passed through the polishing line. There was a problem that it had to be done.

Therefore, the present invention solves the problems in the conventional method and reduces the burden of pickling treatment in removing scale and surface flaws from hot-rolled alloy steel strips. It is an object of the present invention to provide a method and apparatus for processing hot-rolled alloy steel strips, which can significantly reduce surface flaws generated on the surface of the steel strip, and can also remove surface flaws, etc. generated on the surface of the steel strip, with high productivity and at low cost. do.

[Means to solve the problem]

In order to solve the above problems, the present inventors conducted various studies and found that between the mechanical treatment process and the pickling treatment process in the hot-rolled alloy steel strip line, the surface of the copper strip was coated with abrasive grains within a predetermined range. Grinding is carried out using a grinding roll with a grinding roll having a grain count finer than or equal to the abrasive grain count of the grinding roll used for this grinding. By grinding and removing not only the metal base directly below the scale, you can obtain a high quality product with excellent surface condition without leaving any grinding marks, and it is also possible to process steel strips in one line. They investigated what was possible and completed the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method and apparatus for processing a hot rolled alloy steel strip according to the present invention will be described in detail below based on one drawing.

FIG. 1 is a schematic explanatory diagram showing one embodiment of the apparatus of the present invention for carrying out the method of the present invention.

In the drawing, 1 is a hot-rolled mainly Ni and/or C
2 is an annealing furnace; 3 is a cooling device for rapidly cooling the hot rolled alloy steel strip 1 heated by the annealing furnace 2; 4 is a hot rolled steel strip cooled by the cooling device 3; A mechanical processing machine 5 such as a tension leveler applies bending and tension processing to the alloy steel strip 1 to impart strain to the scale on the surface of the steel strip and cause cracks and peeling of the scale. This is a mechanical processing machine such as shot blasting which further causes cracks and peeling in the scale of the hot rolled alloy steel strip 1. 6 is, for example, a backup roll 6b and a first roller having an abrasive grain count in the range of #46 to #100.
The first grinding device is a first grinding device which is paired with a grinding roll 6a and grinds both the front and back surfaces of the hot rolled alloy steel strip 1 processed by the mechanical processing machine 5, and the first grinding roll 6a is used to grind nylon thread as a specific example. It consists of a brush containing abrasive grains and molded into a roll, or a grinding wheel molded into a roll. 7, for example, each pair is formed by a backup roll 7b and a second grinding roll 7a whose abrasive grain count is in the range of #80 to #400 and whose abrasive grain count is finer than or equal to that of the first grinding roll 6a. A second grinding device further grinds both the front and back surfaces of the hot-rolled alloy steel strip 1 ground by the first grinding device 6, and the second grinding roll 7a
They are also made of a brush-like product made of nylon thread containing abrasive grains and molded into a roll, or a grinding wheel molded into a roll. Reference numeral 8 denotes a pickling treatment tank into which a pickling solution such as hydrochloric acid, sulfuric acid, or a mixed acid of nitric acid and hydrofluoric acid is poured to pickle the hot-rolled alloy steel strip 1 which has been ground on both front and back surfaces by the second grinding device 7. , 9 is a brush cleaning device for cleaning and removing metal residues, smut, etc. attached to the surface of the hot rolled alloy steel strip 1 that has been pickled in the pickling treatment tank 8; 10 is a brush cleaning device 9 that cleans the hot rolled alloy steel strip 1; This is a tension reel for winding up a hot rolled alloy steel strip 1.

In such a treatment process for hot-rolled alloy steel strip, hot-rolled hot-rolled alloy steel strip 1 is passed through an annealing furnace 2 and a cooling device 3.
After passing through this process, first, a mechanical treatment machine 4 applies strain to the scale on the surface layer, causing cracks and peeling of the scale. In the sixth stage, the scale is further cracked and peeled off by the next mechanical processing machine 5.

The first grinding roll 6 a of the first grinding device 6 grinds not only the scale but also the metal substrate on both the front and back sides of the hot rolled alloy steel strip 1 , and then the second grinding roll 7 of the second grinding device 7 .
In step a, some of the metal substrates on both the front and back surfaces are ground, and the ground surfaces are smoothed. After that, the ground surface is dissolved in a pickling treatment tank 8 to smooth and blur the surface, and finally metal residues, generally called smut, adhering to the surface of the copper strip are removed by a brush cleaning device 9.
It is cleaned, removed, finished, and wound onto the tension reel 9.

As mentioned above, in the process, it is important to grind the hot-rolled alloy steel strip 1 in two stages with a grinding roll, and the first stage of grinding is performed using the first grinding roll with abrasive grains in the range of #46 to #100. Grind with 6a, and in the second stage of grinding, the abrasive grain count is #8.
Grinding is carried out using the second grinding roll 7a which has an abrasive grain count in the range of 0 to 400 and which is finer than or equal to the abrasive grain count of the first grinding roll 6a used for the first stage grinding. This is because if the abrasive grain count of the first grinding roll 6a is coarser than #46, rough grinding marks will be formed on the ground surface. This is because grinding marks remain on the surface, making it impossible to obtain an excellent surface.On the other hand, if the abrasive grain count is finer than #100, the metal substrate immediately below the scale cannot be sufficiently ground. Also the second
If the abrasive grain count of the grinding roll 7a is coarser than #80, even if the pickling treatment is carried out in the next step, grinding marks will remain on the surface after the pickling treatment, and the result will be the opposite of smoothing, resulting in an excellent surface. On the other hand, if the abrasive grain count is finer than #400, sufficient leveling will not be achieved. Furthermore, even if the abrasive grain count is within the above range, in the second stage grinding, the second grinding roll 7a has a finer abrasive grain count than the abrasive grain count of the first grinding roll 6a used in the first stage grinding. If this is used, grinding marks remain on the surface, making it impossible to obtain a good surface.

In addition, in the above-mentioned grinding process, in order to remove not only the scale on the surface layer of the front and back surfaces of the hot rolled alloy steel strip 1 but also the surface flaws, the backup roll 6b and the abrasive grain count are set to # as shown in FIG. It is more desirable to install two or more pairs of first grinding rolls 6a in the range of 46 to 100, and to repeat the grinding by the first grinding device 6 two or more times. That is, if the process is repeated two or more times, the amount of grinding of the hot-rolled alloy steel strip 1 will be significantly improved, and a superior product with a uniform surface texture with no or very slight surface flaws will be obtained. The speed is also increased, and the objectives of the present invention can be achieved more reliably.

[For production]

As described above, in the present invention, first, the scales on the surface of the hot-rolled alloy steel strip 1 are strained by mechanical processing machines 4 and 5 such as tension levelers and shot blasters to cause cracks and peeling in the scales. The removal becomes easy, and then the hot-rolled alloy iron m-band 1 is removed in two stages by grinding rolls 6a and 7a with different abrasive grain counts.
The metal substrate is ground with consideration given to removing not only the surface scale but also surface flaws.In particular, since most of the scale is removed by the second grinding device 7, the load in the pickling process in the next process is extremely light. Downsizing of treatment tank 8.

This makes it possible to extend the life of the pickling solution and to reduce the cost of the pickling solution waste treatment equipment and waste solution management costs. In addition, in the second stage of grinding, the metal base is slightly ground and the ground surface is smoothed, and the ground surface is further dissolved by pickling treatment to smooth and blur the surface. This results in a very smooth, uniform, and high-quality product.

〔Example〕

5US430 and 5US304 according to the process shown in Figure 1.
A hot-rolled alloy steel strip is passed through the steel strip at the line speed shown in the table, subjected to mechanical treatment using a scale breaker and shot blasting, then ground using the grinding roll shown in the table, and then processed with the pickling solution shown in the table. The descale state 2 surface roughness and surface grinding amount were investigated for the examples in which the pickling treatment was performed.

In addition, the surface roughness and surface grinding amount of the descaled state 9 was also investigated for a comparative example in which no grinding using a grinding roll was performed in the process under the same conditions as above.

In this table, the descaling state was evaluated based on the following criteria.

A: No descaling residue B: No scale residue was observed visually, but scale residue was observed under a 10x magnifying glass.

C: Scale residue is visually observed.

In addition, the amount of surface grinding is the amount of grinding per one side of the metal (g/rn
').

The results are shown in the table. As is clear from this table, the evaluation characteristics of each example according to the present invention are all good, and in particular, the surface grinding amount of the one subjected to the grinding process twice by the first grinding device is extremely excellent. I understand. As a result, although not particularly shown in the table, a high quality steel strip with almost no surface flaws was obtained.

On the other hand, in the case of each comparative example, not only are there problems of increased consumption of pickling solution and increased pickling solution management, but as is clear from the table, the descaling state is incomplete and the surface is rough. The product was rough and could not be called a good product.

Margins below [Effects of the Invention] As detailed above, according to the method and apparatus for processing hot rolled alloy steel strip according to the present invention, various effects as listed below can be obtained, and the industrial value thereof is There is something very big.

■ The hot-rolled alloy steel strip is ground in two stages before the pickling treatment, grinding not only the scale but also the metal base, resulting in an excellent, uniform and smooth alloy steel strip with almost no surface flaws.

■ At the pickling stage, most of the scale has already been removed by two-stage grinding, so the pickling process can be significantly reduced and the life of the pickling solution is extended, reducing the cost of the pickling solution and the It becomes possible to significantly reduce costs such as equipment costs and pollution prevention management costs required for waste acid treatment of washing liquid.

■ Since the grinding process is performed using grinding rolls, it can easily accommodate higher line speeds and improve productivity.

■ Unlike conventional methods and equipment, hot-rolled alloy steel strips do not need to be passed through two lines, an annealing pickling line and a polishing line, and can be processed in one line, which greatly streamlines the processing process and saves labor. This makes it possible to improve productivity, and requires less installation space and lower equipment costs.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing one embodiment of the apparatus of the present invention for carrying out the method of the present invention, and FIG. 2 is a schematic explanatory diagram of a conventional descaling apparatus. 1... Hot rolled alloy steel strip 2... Annealing furnace 3... Cooling device 4... Mechanical processing machine 4'... Scale breaker 5... Mechanical processing machine 6 ...First grinding device 6a...First grinding roll 6b...Backup roll 7...Second grinding device 7a...Second grinding roll 7b...Backup roll 8 .8', 8'... Pickling treatment tank 9... Brush cleaning device 10... Tension reel Patent attorney Tadayuki Noma,

Claims (1)

[Claims] 1. A hot rolled alloy steel strip is mechanically treated to cause cracks and peeling in the scale of the hot rolled alloy steel strip, and then first grinding with an abrasive grain size in the range of #46 to #100 is performed. The hot-rolled alloy steel strip is ground to the base metal just below the scale using a roll, and then an abrasive with an abrasive grain number in the range of #80 to #400 and finer than or equal to the abrasive grain number of the first grinding roll is used. A method for processing a hot-rolled alloy steel strip, characterized in that the operations of smoothing the ground surface using a second grinding roll with a grain size and then treating it with an acid solution are performed continuously in one line. 2. The method for treating a hot-rolled alloy steel strip according to claim 1, wherein the first grinding roll is used to repeat the grinding process two or more times to grind the hot-rolled alloy steel strip down to the metal substrate directly below the scale. 3. A mechanical treatment machine that causes cracks and peeling in the scale of the hot rolled alloy steel strip, and a first grinding roll with an abrasive grain count in the range of #46 to 100 are used to grind both the front and back surfaces of the hot rolled alloy steel strip. 1 Grinding device and abrasive grain count #80~40
A second grinding device that grinds both the front and back surfaces of a hot rolled alloy steel strip using a second grinding roll with a range of 0.0 and an acid solution treatment tank are arranged in series in one line. Processing equipment for rolled alloy steel strip. 4 The first grinding device is provided with two or more pairs each of a backup roll and a first grinding roll having an abrasive grain count in the range of #46 to #100 for grinding both the front and back surfaces of the hot rolled alloy steel strip. 4. The hot rolled alloy steel strip processing apparatus according to claim 3.