The method of processing rolls

 

The invention relates to rolling production, in particular to the preparation of the working surface of the rolls of rolling mills before rolling, and can find application in various engineering industries. Carry out the installation with the contact roll and brush with metal bristles. Their longitudinal axis is placed in the same plane. Enter into contact with the periphery of the bristle brush with a heated bar of the coating material. Put a durable coating on the roller by rotation of the brush and roll and their reciprocal movement along the longitudinal axis. Wear resistant coating is applied from a polymeric antifriction material with simultaneous hardening of the surface layer of the roll of plastic deformation at specific pressure of the bar of the coating material on the peripheral surface of the bristle brush, equal to 0,2-0,3 N/mm2specific pressure peripheral surface of the pile of brush on the surface of the roll equal to 30-70 N/mm2and the axial speed of movement of the brush relative to the roll, which is determined by the dependence of VOC=K1VY(HY/RIn)K2where VOC- axial moving speed of the brush, m/s; VY- peripheral speed and 2.52-2,56 respectively. As a wear resistant coating applied Teflon. Before applying the wear-resistant coating on the surface of the roll pre-applied coating of a copper-containing alloy. As a result of this processing ensures longer service life of the rolls by reducing wear and reduce the number of cracks and chips on the working surface of the roll. 3 C.p. f-crystals, 1 Il.

The invention relates to rolling production, in particular to the rolls of rolling mills and the preparation of their work surface before rolling.

A known method of manufacturing rolls, including the application for the procurement of wear-resistant coatings, subsequent plastic deformation of the screw rolling with a reduction of 30-50% per pass and machining (A. C. the USSR 876222, CL 21 In 27/00, 1982).

The amount of compression in the known method allows to obtain a strong adhesion of the coating to the substrate. However, when plastic deformation on the free surface of the workpiece, as a rule, there is a zone where there are tensile stresses, which with the lack of ductility of the material can cause cracks and destruction. As wear-resistant materials are characterized by high hardness, reduced plastically rolls at the specified method is limited, that reduces their lifespan. In addition, more difficult machining the deformed workpiece with a wear resistant hard coating.

There is also known a method of manufacture of rolls, comprising the application to the workpiece wear resistant coating and a layer of well-processed cutting plastic steel, subsequent plastic deformation for hardening wear resistant coating and machining, consisting in the removal of a layer of steel (A. C. 995930, CL 21 In 27/00, 1983).

In the process of plastic deformation of the layer of plastic pressed steel and comes from under hardening tool, resulting in the deformation area tensile stresses that cause cracking and chipping in hard, wear-resistant coating, characterized by greater hardness and limited ductility.

Uneven hardening wear resistant coating results in operation of the roll to the uneven distribution of specific pressures and in particular its wear - loss of strength and indentation resistant coating into the body of the roll. In addition, mechanical processing takes a significant portion of time of time processing use the log of the claimed invention is a method of processing rolls, implemented a known device for coating (A. C. 1497276, CL 23 With 26/00, 1989). The known method includes setting with the possibility of contact of the roller and brushes with their longitudinal axes in the same plane, an introduction to contact the periphery of the bristle brush with a set of heated bars of the coating material arranged in series one behind the other along the axis of the brush, the movement of the bar relative to the axis of the brush with the magnitude of the contact zone and the efforts of the pressing of the bar toward the periphery of the bristle brush, the coating on the outer surface of the roll by rotating the brush and roll and their reciprocal movement along the longitudinal axis.

Signs nearest analogue, coinciding with the essential features of the claimed invention: installation contact roll and brush with their longitudinal axes in the same plane, an introduction to contact the periphery of the bristle brush bar (with heated) of the coating material, the coating on the roller by rotation of the brush and roll and their reciprocal movement along the longitudinal axis.

Applied wear-resistant coatings are not anti-friction because are designed to compensate for the wear of the roll profile and depending on its value voteshare or reduce wear. Application of wear-resistant material involves the application of cutting fluid coolant with a high fat content, which leads to the appearance of the defect "snuff" on the surface of the rolled strips during annealing and reducing their quality. The increase in fat content from 0.5 to 1.0 to 1.7-2.0%, it is necessary to reduce the friction coefficient f= 0.1 to 0.15 up to f=0,08-0,009, thus reducing the percentage of chipping and peeling rolls of cold rolling up to 5-7% and reduced defect "forward", however, increased fat leads to defects "snuff" on the strip surface during annealing and reducing their quality.

In a known way by a tool for applying coating is a brush with metal bristles, which during the rotation and contact with the surface of the roll has a striking impact. This can cause hardening of the surface layers of the roll, which in turn increases the wear resistance of the working surface. However, the hardening is possible only under certain technological processing modes with a metal brush (the rotation speed of the brush, the specific pressure of the peripheral surface of the bristle brush on the surface of the roll, and so on), otherwise either not achieved the desired procne method of applying a multilayer coating of wear-resistant materials cannot be implemented directly in the rolling process due to oxidation damage of the coating layers, which is possible by increasing the temperature or roll or coating material, which is caused by adhesion of the applied layer.

The objective of the proposed method of processing rolls is to increase the service life of the rolls and improving the quality of hire through the use of wear resistant coating of anti-friction material and regulation of technological parameters of its application to the working surface of the roll.

The problem is solved in that in the method of processing rolls, including the installation of a contact roller and brush set with their longitudinal axes in the same plane, an introduction to contact the periphery of the bristle brush with a heated bar of the coating material, applying a wear resistant coating on the roller by rotation of the brush and roll and their reciprocal movement along the longitudinal axis, according to the invention a wear-resistant coating is applied from a polymeric antifriction material with simultaneous hardening of the surface layer of the roll of plastic deformation at specific pressure of the bar of the coating material on the peripheral surface of the bristle brush, equal to 0,2-0,3 N/mm2specific pressure peripheral surface of the pile of brush on the surface of the roller R is sub>OC=K1VY(HY/RIn)K2where VOS- axial moving speed of the brush, m/s; VY- circumferential speed of the brush, m/s; HY- the width of the brush, mm; RInthe roll radius, mm; K1, K2 are empirical coefficients equal to 30-50 and 2.52-2,56, respectively.

Before applying the wear-resistant coating on the surface of the roll pre-applied coating of a copper-containing alloy. Appropriate application of wear-resistant coatings can be made simultaneously with the rolling process.

Hardening of the surface layers of the roll and the coating is performed under certain conditions. Thus, the specific pressure of the bar of the coating material on the peripheral surface of the brush is equal to 0,2-0,3 N/mm, and when the pressure of the bar is less than 0.2 N/mm2is insufficient removal of the PTFE, and the surface has areas without coverage, at the same time when the pressure of the bar more than 0.3 N/mm2there is an intensive reading and overuse of PTFE without changing the thickness of the coating. In turn, the specific pressure of the peripheral surface of the brush on the surface of the roll is in the range of 30-70 N/mm2moreover , when processing with grabocka with pressure above 70 N/mm2there is increased wear of the working surface of the brush, as a result of impaired stability of the processing surface of the roll.

The pile of metal brush is a tool, which when it strikes the surface of the roll is a superficial plastic deformation of the surface layers. Increasing the hardness of the roll surface depends on the number of strikes had on each point of the treated surface of the roll. Experiments have shown that the number of strokes should be in the range of 30-50. This number of beats in the processing rolls with hardened surface is provided at the axial movement of the brush relative to the roll, while respecting the proposed dependency, when the circumferential speed of the brushY=30-50 m/c, the width of the brush HY=30-50 mm

Application of PTFE over a copper-containing alloy can reduce the friction coefficient to the level of the liquid friction (f=0.01 to 0.05), prolongs the service life of the rolls and reduces the fat content of the coolant, which eliminates the defect of "snuff".

Drawing on a solid surface layer of the rolling roll copper-containing alloy, such as brass, thickness, corresponding to the roughness parameters of the surface is tin. This is because when the shock of many fibers of the brush, the ends of which there is a coating material, there is a "healing" of microscopic cracks, which are usually the source of birth defects on the working surface during rolling.

Use brushes with metal pile as a tool for coating and simultaneous hardening of the roll surface by plastic deformation allows to minimize the processing time of the roll surface and to perform processing in the rolling process, increasing the productivity of the rolling process in General.

The invention is illustrated in the drawing, which schematically shows a method of processing rolls.

The method of processing rolls is as follows.

Mill roll 1 and brush 2 with metal wire cloth 3 sets with their longitudinal axes in the same plane and enter into contact. Rolling Valka 1, on the surface of which is coated 4, gives the rotation n1. The brush 2 gives the rotation n2. To the periphery of the pile 3 rotating brushes 2 press the bar 5 of the antifriction polymeric material. The particles of the coating material with the bar 5 pile 3 brushes 2 the LCA 1 rotary brush 2 is shock her hairs 3, on the ends of which is heated material of the bar 5. When the coating material of the bar 5 with bristles 3 of the brush 2 is carried on the surface of the roll 1, forming the coating 4. Application of wear-resistant coatings are simultaneously hardening the surface layer of the roll 1 by plastic deformation at specific pressure bar 5 on the peripheral surface of the pile 3 brushes 2, equal to 0,2-0,3 N/mm2specific pressure peripheral surface of the pile 3 brushes 2 on the surface of the roll 1 is 30-70 N/mm2and the axial velocity of the brush 2 relative to the roll 1, which is determined by the dependence of VOC=K1VY(HY/RIn)K2where VOS- axial moving speed of the brush, m/s; VY- circumferential speed of the brush, m/s;
HY- the width of the brush, mm;
RInthe roll radius, mm;
K1, K2 are empirical coefficients equal to 30-50 and 2.52-2,56, respectively.

During processing the surface of the mill roll 1 simultaneously cleaned of oxides, heated, providing adhesion adhesion juvenile surface of the mill roll 1 with particles of the coating material 5. In addition, the coating material fills all microcredito coating material is PTFE with low friction coefficient f= 0,01-0,05 reduces the wear of the rolls and allows the coolant with a low fat content. Before applying anti-friction wear-resistant coatings on the surface of the roll pre-applied coating of a copper-containing alloy. As wear of the surface layer of the latter can be restored in the rolling process.

Example 1.

On the laboratory mill 80/150180, which is a model of industrial cold rolling mill 1450 scale modeling 1:8, as workers used rolls of steel grade H diameter of 80 mm, the Hardness of their working surfaces after hardening by high-frequency currents, tempering and grinding is HRC 55-65. The mill was produced by rolling the strip with a thickness of 0.4-1.5 mm, a width of 40-50 mm of different grades of steels withof 0.2up to 300 MPa at a speed of 2 m/s and lubrication oil TMS-6 (TU 38.101826-85).

The wear of the rolls causes the peals longitudinal dark stripes (defect "forward"). To reduce the intensity of wear and eliminate this defect was used application of anti-friction coatings on the surfaces of the rolls.

For this purpose, the working surface of the upper roller was applied wear-resistant coating of polymeric antifriction material and the working surface of the lower roll arrabal coating on the peripheral surface of the bristle brush, 0.25 N/mm, specific pressure peripheral surface of the pile of brush on the surface of the roll equal to 50 N/mm2, brush diameter DS=870 mm, when the rotation speed of its n=1100 rpm, the diameter of the pile (d=0.25 mm, the density of the packing pile=0.2, a pile of brush was made of steel grade 70. As the coating material was applied Teflon brand 4. Given the high mijalkovi pressure, has formed a coating thickness of 1.5 to 2.5 μm.

Rolling in a single pass was subjected to a strip of steel SP width 100 mm with a thickness of 1.0 mm to a final strip thickness of 0.7 mm at a rolling speed of 1.0 m/s After rolling 3,0 tons of bands was control of the working surfaces of the rolls.

On the working surface of the upper work roll wear is not detected, and the floor has been completely preserved. At the same time, the radial wear of the working surface of the lower roll, processed according to the traditional technology, was 0.01 mm

The second positive result of the experiment was the absence of the stripe defect "forward" side of the roll with a coating of polymeric antifriction material, while the side treated by traditional technology bottom roll it appeared after procutie rolls with a diameter of 500 mm, made of steel CHMP, the hardness 90-100 HRC. The mill was produced by rolling strips of mild steel, of a width 730 mm and thickness of 0.4 mm Main types of defects in rolled strips connected with the occurrence of delaminations on the working surfaces of the rolls, leading to the formation of defect "forward" on the strip surface. In addition, the use of coolant greasy leads to the appearance of the defect "snuff" when the annealing of the strip.

Within two months on the surface of the work rolls of the fifth stand inflicted two-layer brass-fluoropolymer coating and the first layer was applied brass brand 63, and the second fluoroplastic-4.

After rolling 420 tons of bands 7300.4 mm of steel 08 KP evaluated the results presented in the table.

Experimental results confirm that the proposed method allows you to:
1. To increase the service life of the rolls by reducing wear and reduce the number of cracks and chips on the working surface of the roll resulting from the use of coating materials having a low coefficient of friction.

2. To improve product quality by reducing the fat content of the coolant during rolling.

3. To improve the performance of the rolling process transactions coatings in the rolling process.


Claims

1. The method of processing rolls, including the installation of a contact roll and brush with metal pile with their longitudinal axes in the same plane, an introduction to contact the periphery of the bristle brush with a heated bar of the coating material, applying a wear resistant coating on the roller by rotation of the brush and roll and their reciprocal movement along the longitudinal axis, wherein the wear resistant coating is applied from a polymeric antifriction material with simultaneous hardening of the surface layer of the roll of plastic deformation at specific pressure of the bar of the coating material on the peripheral surface of the bristle brush, equal to 0,2-0,3 N/mm2specific pressure peripheral surface of the pile of brush on the surface of the roll equal to 30-70 N/mm2and the axial speed of movement of the brush relative to the roll, as defined by dependency

VOS=K1·Vy·(Hy/Rin)K2,

where Voc- axial moving speed of the brush, m/s;

Vy- circumferential speed of the brush, m/s;

Hy- the width of the brush, mm;

Rinthe roll radius, mm;

K1, K2 are empirical coefficients equal (30-50) and (2,52-2,56) according to the>/p>3. The method according to p. 1, characterized in that before applying the wear-resistant coating on the surface of the roll pre-applied coating of a copper-containing alloy.

4. The method according to p. 1, characterized in that the application of wear-resistant coatings carried out simultaneously with the rolling process.

 

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