JPS5852722B2 - Sheet rolling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to the rolling of sheet metal billets, and more particularly to a method for producing sheet products of aluminum alloys, stainless steel, and other metals having mirror or matte finishes.

A method for producing rolled sheet products in which both sides of a seed billet are processed to have a mirror or matte finish is widely known.

This processing is typically accomplished by directing a jet of mass onto the surface of a sheet metal billet, followed by chemical treatment and rolling.

For example, a sheet metal billet is transferred from a hot rolling mill to a shot blasting machine where the surface of the billet is
Exposure to blasting of metal shot with particle size between.

This shot contains particles with sharp angles, which partially remove scale from the billet surface.

The billet is then chemically treated in an alkaline bath, washed, then etched in an acidic bath, washed again, and dried.

The thus treated billet is sent to a rolling mill.

Rolling is carried out in one pass or in multiple passes 7, in which case the billet is heat treated and the scale removed from its surface after each pass.

For this purpose, this billet was shot blasted as described above,
Subjected to chemical treatment in alkaline and acid baths and drying treatment.

During the final pass, the billet is passivated in a nitric acid solution.

This cold rolled product is then processed in a temper mill and then cut into sheets.

Each sheet is processed using a grinder and polisher.

As a result, the rolled sheet of stainless steel has a mirror finish.

The use of the above method involves considerable expense as it requires a large amount of floor space for auxiliary equipment and significant amounts of chemicals and water.

Furthermore, this method is time consuming and requires skilled personnel who must work in contact with hazardous media.

Furthermore, the method under consideration has the disadvantage that etching the sheet metal billet in an acid solution results in pitting that cannot be removed by further processing.

Under-etching or over-etching the surface of a cold rolled strip is another source of surface defects.

However, the most significant drawback of this method is that it requires repeated, laborious and labor-intensive grinding and polishing operations using special-purpose machinery, and these operations often require multiple It is useless because of the surface scratches caused by the etching operation.

Methods for producing bright shiny sheets of aluminum alloys are generally known.

This sheet is normally used for surface finishing purposes.

This method is carried out using oil in a cold rolling mill.

The quality of this sheet depends primarily on the quality of the original hot rolled strip.

This is the reason why this method does not always give good results.

On the other hand, if pure oil is used, there is always a risk of fire, which accounts for the fact that the cost of fire extinguishing means is as high as 15% of the overall cold rolling mill cost. Moreover, even these highly complex fire prevention measures do not always eliminate fires.

The use of oil-in-water refrigerants minimizes the risk of fire, but tends to increase the amount of waste.

The latter method of producing aluminum alloy sheets described above does not allow the production of cold-rolled sheets with a matte surface to which a paint coating can later be applied.

Matte surfaces are commonly created on finished articles. Typically, such operations are performed in metal processing equipment using a variety of techniques, including fabricating articles with microspheres.

Microspheres are to be understood as hard solid spheres with a diameter in the order of microns.

The use of microspheres requires suitable machinery, which also requires a certain amount of floor space and manpower.

This known method of producing sheets with a glittering luster requires the use of acids and alkalis to clean the surface of the billet and results in air and water contamination.

As the production of rolled sheet articles increases, there is a need for rolling methods that are more economical and less hazardous from a pollution standpoint than current methods.

Such a process must also be capable of producing sheet products with a polished surface on a cold rolling mill.

Finally, such a method can ensure higher productivity and
It must also be possible to carry out the process in such a way that the quality of the finished product is not significantly dependent on the surface quality of the original hot-rolled billet.

The main purpose of the present invention is to etch and grind rolled products,
The object of the invention is to provide a method for producing rolled sheet products which eliminates the need for polishing operations and equipment therefor and is therefore more economical than conventional methods used for the same purpose.

An equally important object of the present invention is to simplify the manufacturing process of sheet rolled products by reducing the number of operations required to impart a mirror or matte finish to stainless steel and aluminum alloy rolled products. It is in.

Other important objects of the present invention are to improve the quality of rolled products of aluminum alloys, to reduce defects in the process carried out with the use of oil-in-water coolants, and to make the quality of rolled products less similar to that of billets. The goal is to avoid becoming dependent on it.

A further object of the invention is to make it possible to produce rolled products with mirror and matte finishes in one rolling mill, thereby reducing the floor space required for the equipment.

The foregoing and other objects of the present invention are to subject a sheet metal billet to a number of reverse rolling operations in a rolling mill, each of which rolling operations involves rolling the sheet metal billet in a number of stands of the rolling mill. etching, grinding, or polishing the surface of the resulting rolled sheet metal product by applying a cooling emulsion to the sheet metal billet prior to each rolling step in each rolling stand. each application of a cooling emulsion to a hot sheet metal billet prior to each rolling step and at each rolling stand in each reverse rolling operation in a method of providing mirror and matte finishes without glass, aluminum oxide, zirconium oxide,
impinging on the surface of the hot sheet metal billet a jet of gas containing hard solid spheres of 40 to 200 microns in diameter of a material harder than the sheet metal to be processed, selected from the group consisting of chromium-nickel alloys and ice; applying a jet of gas containing the hard solid spheres to the roll surface before applying the cooling emulsion to the surface, and after each such treatment; This is achieved by a method characterized in that the billet is rolled on a stand of a rolling mill, thereby giving its surface the desired finish.

According to the present invention, by using hard solid spheres called microspheres, scale can be removed from the surface of rolled sheet products more effectively than by using shots according to conventional methods.

Furthermore, the microspheres also help eliminate mechanical defects such as scratches.

According to the method of the invention, it is possible to optimally distribute the coolant onto the fine reliefs produced on the billet surface.

By using hard solid spheres having the above-mentioned particle size, a billet surface with a fine roughness sufficient to achieve a mirror finish can be obtained only by subsequent rolling.

The provision of hard solid spheres by jets of gas is technically the most convenient, and this method makes it possible to process both sides of the sheet metal billet before each reverse rolling operation.

In the present invention, the materials of the hard solid spheres are limited to glass, aluminum oxide, zirconium oxide, chromium-nickel alloy, and ice because, unlike many materials commonly used to clean the billet surface, This is because it has been confirmed that these substances do not scratch the surfaces on which they act.

Microspheres made of glass allow rolled sheet products with sufficiently high surface quality to be obtained.

The reason for limiting the diameter of these solid spheres to 40 to 200 microns is that if solid spheres with a diameter larger than 200 microns are used, the desired surface finish will not be achieved. If a solid sphere of small diameter is used, the weight of the sphere is insufficient;
This is because the necessary processing efficiency cannot be secured.

The hard spheres made of aluminum oxide, zirconium oxide and chromium-nickel alloy are characterized by high mechanical strength and do not require any recovery process for the ice microspheres.

Various hard spheres of different chemical composition may be used together or sequentially.

The simultaneous use of various hard solid spheres of different materials makes it possible to produce bulk mixtures of defined mechanical properties, taking into account the overall cost of the bulk mixture.

When using various microspheres made of different materials in sequence, the hardest one, such as a chromium-nickel alloy,
Alternatively, use the cheapest material first, such as aluminum oxide or ice, and then use glass microspheres in the second stage of processing.

Preferably, the weight concentration of hard solid spheres directed to the surface of the rolled sheet billet, ie the ratio of the weight of the spheres to the weight of the carrier, should be between 0.05 and 0.5.

Such quantities of hard solid spheres are sufficient to effectively process billets made from metals of varying hardness.

The lower limit of the weight concentration factor mentioned above is sufficient for aluminum alloys, while its upper limit is for processing stainless steel billets.

It is desirable to aim the hard solid sphere at the surface of the sheet metal billet at a speed of 20-300 m/sec. This speed range is determined by the surface quality of the billet, the adhesion of scale to the metal and the mechanical defects present on the billet surface. It will be done.

Speeds near the lower end of the speed range described above are for processing aluminum alloy billets, and higher speed levels are for stainless steel billets with severe surface defects.

The action of the hard solid spheres on the billet surface may be in an intermittent manner.

Intermittent feeding of microspheres is the most effective method to clean billets with severe surface defects and strong scale adhesion.

It is advisable to direct the hard solid spheres onto the billet surface at the latest before the billet reaches the second stand of the rolling mill.

By doing so, a mirror finish can be applied to the rolled stainless steel sheet.

When rolling is carried out while polishing operations are carried out sequentially in the first and subsequent respective stands of the rolling mill, the quality of the billet surface is progressively improved.

Care must also be taken to carry out the rolling in such a way that the micro-relief of the billet surface is optimal on the stand and the distribution of the rolling lubricant in the deformation zone is uniform.

The microspheres used to process the billet before it enters the first stand of the rolling mill may be coarser than the microspheres used to process the billet before it passes through the other stands. preferable.

This helps ensure optimal rolling conditions according to the rolling rate in each stand of the rolling mill and improves the performance of the rolling mill.

A jet of hard solid spheres is directed onto the roll surface before the emulsion is delivered to the roll surface.

This allows the roll surface to be kept in good condition and prevents aluminum from adhering to the roll while the sheet of aluminum alloy is being rolled.

A jet of hard solid spheres can be directed onto at least one side of the mirror finished sheet product.

This allows one rolling mill to produce both mirror-finished and matte-finished articles.

It is expedient to transport the hard solid spheres by a jet of gas cooled to a temperature of -50°C to -2000G and to cool the billet in this way.

By doing so, the mechanical properties of certain grades of steel can be improved while producing mirror finished products.

A jet of hard solid spheres may be applied to the surface of the aluminum alloy billet.

This method is an economical way to produce aluminum alloy sheet products with high surface quality that is largely independent of the quality of the original billet.

It is advantageous to use a jet of hard solid spheres to act on the surface of a stainless steel billet.

By doing so, etching, grinding, and polishing operations can be eliminated from the process of processing a stainless steel sheet billet.

The method of the invention can best be applied to the production of rolled products of the type widely used in the aircraft industry, radio engineering, nuclear reactors, and the refrigeration and food industries.

Other objects and advantages of the invention will be further illustrated by the following examples.

The following examples illustrate preferred embodiments of the method for producing rolled sheet products with mirror and/or matte finishes in accordance with the present invention.

Example 1 A hot rolled coil of chrome-nickel steel was placed in a 4-stand reverse cold rolling mill.

Before entering the deformation zone of the first stand, both sides of this sheet were processed with hard solid spheres called hard microspheres.

In this case, hard particles made of chromium-nickel alloy were used.

This microscopic body had a diameter of 150 microns, and the microscopic body was accelerated to a speed of 1.20 m/sec.

The hard microbodies were intermittently supplied in a pulsed manner at a rate of 10 pulses/sec.

The rolling speed was 3 m/sec. The weight concentration of hard solid particles in the compressed air stream was 0.2.

This jet of solid particles was directed onto the roll surface of the first stand of the rolling mill before the emulsion was applied to the roll surface.

In this case as well, hard solid particles having a diameter of 150 microns were used and were continuously supplied at a rate of 60 rrL/sec.

The weight concentration of hard solid particles in the compressed air stream directed towards the surface of this roll was 0.1.

In order to exclude hard solid particles from entering the deformation zone, a stream of compressed air was continuously blown onto the surface of the processing roll.

The hard solid particles were oriented at a 60' angle to the processing roll surface.

The rolling reduction in the first stand was 15.7%.

Furthermore, in the fourth stand, hard solid particles were applied to the processed surfaces of the billet and roll.

This was done before the billet reached the deformation zone.

The hard solid particles in this case were made of glass and had a diameter of 80 microns.

The weight concentration of this microscopic body in the compressed air stream was 0.4.

Accelerate this microbody to a speed of 60 m/sec, and
Aimed at the processing surface of the roll at an angle of °.

The rolling ratio in the fourth stand was 5.6%.

In all stands, the hard solid microspheres were oriented at a 700 angle to the sheet surface.

The sheet from the last stand had a mirror surface and was transported for cutting and packaging.

A jet of hard solid particles was applied to the rolled sheet in order to give it a matte finish.

The processing conditions in this case were similar to those when the sheet was about to enter the fourth stand.

Example 2 A hot rolled coil of aluminum alloy was placed in a cold rolling mill.

Before the sheet enters the deformation zone of its first stand,
Both sides of it were fabricated with hard solid microscopic bodies made of glass.

This microscopic body has a diameter of 100 microns, and it is 80 m long.
It accelerated to a speed of /sec.

Further, the rolling speed was 1 m/sec.

The weight concentration of hard solid particles in the compressed air stream was 0.3.

In the first stand, a jet of hard solid particles was directed toward the work surface.

This operation was performed before feeding the emulsion to the roll.

The material and particle size of the hard solid particles and processing conditions in this case are similar to those when the sheet is about to enter the first stand.

The microbodies were oriented at a 600 angle to the surface of the roll.

The rolling reduction in the first stand was 22%.

Next, the glass particles were again applied to the processed surfaces of the sheet and roll.

This operation was performed before the sheet entered the deformation zone of the second stand.

The diameter of the glass particles in this case was 70 microns.

The weight concentration of microbodies in the compressed air stream was 0.4 and their velocity was 45 m/sec.

This jet of hard solid particles was directed at a 15° angle to the work surface of the roll.

The rolling ratio in the second stand was 9%.

In both stands, hold the hard solid microbody at 70°.
toward the surface of the sheet at an angle of .

As a result, the sheet surface was polished.

Although both of the above embodiments relate to sheets of aluminum alloys and stainless steel, the method of the present invention can be applied to mirror-finish rolled sheets of many other materials such as titanium, copper, and various grades of carbon steel. For this purpose, hard solid microbodies with a diameter of 40 to 200 microns are used.

The mechanical strength and cost of hard solid microbodies vary and depend on the nature of the material to be processed and the surface finish requirements.

Hard solid particles can be aluminum oxide, chromium-nickel alloys, zirconium oxide, glass, and even ice.

The carbon steel sheet is preferably processed with ice or aluminum oxide particles plus harder particles of chromium-nickel alloy.

The use of inexpensive materials reduces processing costs.

Carbon steel sheet products are rolled at higher speeds than products made of conventional materials, so the speed of the hard solid particles is 2
It is advisable to increase Q m/sec to 300 m/sec.

To improve the mechanical properties of certain grades of steel, rolling is carried out at subzero temperatures of -50°C to -200°C.

To achieve such a mirror finish on steel, compressed air, nitrogen, or other gases should also be cooled to temperatures between -50'C and -200C.

In this way, the operation of adjusting the fine relief for rolling, the cleaning of the sheet surface and the partial cooling of the sheet can be combined.

When rolling thin sheets (less than one inch thick), this cooling is complete.

The quality of the finish is improved by tempering the rolled sheet product in a temper mill.

The sheets to be processed in the temper mill have a matte finish, which comes from the cold rolling mill after being worked with a jet of hard solid particles as they leave the last stand of the rolling mill. be.

The sheet may be suitably processed with hard solid particles in a temper mill prior to the tempering operation.

In this case it is advisable to use microbodies with a diameter of 40 to 80 microns.

The method of the invention was tested on the rolling of 6,2 square sheets of aluminum alloy in a taper mill.

The sheet itself was manufactured using a hot rolling mill.

Before the sheet entered the stand of the rolling mill, it was processed with a jet of glass particles having a diameter of 60 microns.

The weight concentration of microparticles in the compressed air stream was 0.4.

The speed of directing the microscopic bodies toward the sheet surface is 70 m/sec
Met.

Rolling was carried out in two passes at a rolling reduction of 11% and using 3% oil-in-water coolant.

As a result, the aluminum sheet had a mirror finish.

This method did not use pure oil, which reduced the cost of rolling.

Claims (1)

Claims: 1. Subjecting a sheet metal billet to multiple reverse rolling operations in a rolling mill, each rolling operation comprising rolling the sheet metal billet in multiple stands of the rolling mill, and each without etching, grinding, or polishing the surface of the resulting rolled sheet metal product by applying a cooling emulsion to the sheet metal billet prior to each rolling step in a rolling stand of In a method for providing mirror and matte finishes, the glass, aluminum oxide, etc. , zirconium oxide, chromium-nickel alloy, and ice, the diameter of the material is 4, which is harder than the sheet metal to be processed.
applying a gas jet containing hard solid spheres of 0 to 200 microns to the surface of a hot sheet metal billet; applying the gas jet containing hard solid spheres before applying the cooling emulsion to the roll surface; applying it to the roll surface, and after each such treatment, the billet after being treated as described above is rolled on a stand of a rolling mill, thereby giving the surface the desired finish. How to do it. 2. The method according to claim 1, in which hard solid spheres of different chemical compositions are used together. 3. A method according to claim 1, in which hard solid spheres of different chemical compositions are sequentially used. 4. The method according to claim 1, wherein the hard solid sphere is applied to the surface of the sheet metal billet at a speed of 20 to 300 m/sec. 5 The weight concentration of the hard solid spheres in the carrier gas, calculated as parts by weight of spheres per part by weight of gas.
05 to 0.5. 6. The method according to claim 1, wherein a hard solid sphere is used to process at least one surface of a rolled sheet to give it a mirror finish. T -50 to -20 for gas containing hard solid spheres
2. A method as claimed in claim 1, including cooling to a temperature of 0 DEG C., thereby cooling the sheet metal billet and treating its surface in the meantime.