Application And Development of High- speed Steel Roll

The application of cast high-speed steel roll in steel rolling production began in 1988, when it was used on a hot strip mill in Japan. Subsequently, the United States and Europe began to introduce the technology of casting high-speed steel rolls. The cast high-speed steel roll was initially used in the front section of the finishing mill of the hot strip mill to replace the high chromium cast iron roll. Later, the cast high-speed steel roll was also used in the finishing and roughing sections, wire rod, bar and cold-rolled strip mills, and satisfactory results were obtained.

The cast high-speed steel composite roll produced by Nippon Steel Corporation with CPC method has high wear resistance. After using the cast high-speed steel rolling rod, the steel passing per millimeter is significantly increased, the number of roll changes is significantly reduced, and the roll grinding amount is reduced. The main reason is that high-speed steel rolls contain high hardness carbides such as MC and M6C. In addition, the matrix structure of high-speed steel rolling rod is composed of stable and high hardness martensite and good hardenability and hardenability, which makes the hardness drop of high-speed steel roll significantly smaller than that of other rolls. These characteristics can ensure that the roll has good wear resistance during the whole working period.

In order to improve the production efficiency of the steel tube mill and reduce the roll consumption, the use of high-speed steel rolls in the steel tube mill is also quite successful. High-speed steel rolls have excellent wear resistance and resistance to surface orange peel defects. Their service life is 6-10 times longer than that of traditional rolls, and there is no steel sticking. Since the trial use of cast high-speed steel rolls in 1993, the Canadian Dofasco company has continuously increased the proportion of use. At present, cast high-speed steel rolls have been used on F2, F3, and F4 racks. After using the high-speed steel roll, the roll consumption is significantly reduced, and the rolling mill operation rate is significantly improved. The average steel passing capacity of F4 stand is increased from 360 t /h in june1992 to 490 t/h in november1994, and the strip surface quality is improved by 20%.

The semi-high speed steel composite roll produced by Hitachi has also achieved good results in rolling mills. Compared with the conventional forged steel roll containing 5.0%cr and 10.0%cr, the semi-high speed steel roll has less wear and a shallow fatigue layer, so the roll consumption is significantly reduced. For the production of the same amount of cold-rolled strip, the roll consumption is only 21% of that of 5.0%cr steel. Recently, the 2050 hot rolling mill of the Vanderbijlpark plant in South Africa used the new hss7 high-speed steel roll developed by Marichal ketin company in Belgium. The steel rolling volume per mm was increased to 12000t, while the ordinary high chromium cast iron roll was only 5000 t. After using high-speed steel rolls, the surface quality of the hot-rolled strip is greatly improved, and the problem of strip quality degradation caused by the iron oxide scale is reduced by 2/3. Using high-speed steel rolls has good economic benefits.

Baosteel 2050 hot strip roughing mill adopts semi high-speed steel roll, which has excellent hot crack resistance and wears resistance, and its service life is more than twice that of the original high chromium cast iron roll; When used in the front stand of finish rolling, its wear resistance is three times that of high chromium cast iron roll, and effectively overcomes the defect of spot strip. It can roll high surface quality strips, prolong the roll change cycle, and improve the production rate of the mill. The high-speed steel roll has been used in the front section of rough rolling and finish rolling of 158opc mill, and it also has good results. Hansteel uses high-speed steel rolls for F2, F3 stands and sometimes F1 stands of CSP production line. It mainly rolls SS400, SPHC, spa2h and other steel grades. The corresponding thickness ranges are 1.8-6 mm and 1 5-3 mm,3-6 mm。 According to the statistics, the millimeter rolling volume is 10500 T, 7800 T and 8200 t respectively, and the average millimeter rolling volume reaches 8900 T, which is 2-3 times that of ordinary high chromium iron rolls. The surface quality of the products is significantly improved; The roll can be used continuously for 2-3 times in each cycle. The roll grinding can be reduced by 1.6 times and the grinding loss can be reduced by 0.4 mm. Under normal conditions, the consumption of each roll can be reduced by about 25 RNM.

The general iron and Steel Research Institute selects high-carbon high-speed steel as the working layer, alloy nodular cast iron as the roll center, and the centrifugal casting method is used to manufacture high-speed steel composite rolling rod, which has the characteristics of high working layer hardness and uniform roll body hardness. The comprehensive life of the rolling mill for the hot-rolled narrow strip is 10.5 times longer than that of the high-alloy cast iron roll. Although the hardness (HRC 65) and wear resistance of the high-speed steel roll ring are not as good as that of the cemented carbide roll ring, the heat cracking resistance is much better than that of the cemented carbide roll ring. Its single groove rolling capacity can reach about 6500 T, which is nearly 1 time higher than that of the cemented carbide roll ring. The total rolling capacity of a pair of high-speed steel roll rings and a pair of cemented carbide roll rings is roughly the same. The benefit of replacing the cemented carbide roll ring with a high-speed steel roll ring is very obvious. In addition, due to the high rolling volume of the single groove of a high-speed steel roll ring, the time of roll change and groove change can be reduced and the operation rate can be improved; The weight of a single piece is much lower than that of cemented carbide roller ring, which can reduce the labor intensity of workers; The refitting of the roll ring only needs to be processed on an ordinary lathe, which reduces the processing cost.

However, when using the high-speed steel roll, it should be noted that the high-speed steel roll is easy to form a temperature difference on the roll due to its poor heat dissipation, so as to reduce the service life of the roll. It is necessary to strengthen the cooling capacity of the roll and keep the roll surface temperature below 50 ℃. In addition, high-speed steel has low toughness and accident resistance. It is suitable for hot rolling mills with stable equipment conditions. In case of any abnormality during the rolling mill operation, it is necessary to stop the mill for inspection at any time to avoid serious roll breakage accidents. When using a high-speed steel roll, because the working roll has high hardness, the relative support roll also needs to be changed from the original cast steel to forged steel.

The grinding properties of high-speed steel are quite different from those of traditional rolls. The equipment, grinding materials and management of the roll grinding workshop should be improved in order to give full play to the special properties of high-speed steel rolls. In addition, it is also important to work to find the cracks in the use of high-speed steel rolls as early as possible and prevent crack propagation. As the compressive residual stress of high-speed steel roll is larger than that of ordinary roll, cracks are not easy to be found. It is necessary to carry out online eddy current flaw detection, ultrasonic flaw detection or magnetic particle flaw detection on the roll that has been removed from the rack on-site, and timely repair and clean the cracks found.

As a professional rolling mill manufacturer with 26 years of experience, we can supply rebar rolling mills, wire rod rolling mills, roughing rolling mills, intermediate rolling mills, finished rolling mills, short stress rolling mills, strip steel rolling mills, hot rolling mill, cold rolling mill, continuous casting machine, continuous caster, electric arc furnace, submerged arc furnace, ladle refining furnace, blast furnace, induction furnace, flying shear, cold shear, chopping shear, gripping shear, cooling bed, pinch roll, rebar tying machine, mill roll, Cardan shaft, and related spare parts. 

If interested, please mail at marketing2@hanrm.com or kerrirollingmill@gmail.com.

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Roller FAQs

What Is Universal Rolling Mill?

The universal rolling mill is composed of a pair of horizontal rolls and a pair of vertical rolls. The axis of the four rolls is in a plane. The horizontal rolls are the driving rolls and the vertical rolls are the driven rolls (some rolling mill vertical rolls can also be driven). It can process the rolled pieces on four sides, and the two-high horizontal rolling mill is used as the auxiliary stand (edge ​​rolling machine).

Universal rolling mills are mainly used to roll various types of steel, such as H-beam, rail, I-beam, channel steel, steel sheet pile, U-beam, L-beam, unequal angle steel and other types of steel, because it is suitable for many Variety of steel rolling, hence the name "universal rolling mill".

Features of Universal Rolling Mill

1. The complex section shape composed of four rollers can compress all components of the section at the same time, the deformation of the rolled piece is uniform, the speed difference around the section is small, and the internal stress of the rolled piece is small.

2. Rolls with a smaller diameter can be used (because there is no need to slot on the rolls) to roll products with higher legs and wider waists, and the inner sides of the legs can be made without slope. This is difficult to achieve on an ordinary two-high rolling mill.

3. The reduction of the leg and waist of the rolling piece can be adjusted separately, which simplifies the adjustment of the rolling mill during rolling.

4. The rolling precision is high, the roll wear is less, and the energy consumption is reduced.

According to the structure of the universal rolling mill, there are four main types: closed-end, UD (Universal-Duo) prestressed/short-stressed, SC (Schloemann-Siemag compact stand) connecting plate three-type and compact rolling mill.

The Development History of Universal Rolling Mill

1. The world's first universal rolling mill was built in the Arbed factory in Luxembourg in 1902, but the I-beam with a wider flange was rolled at that time, and the inner side still had a slope.

2. In 1914, the German Payin Company adopted the Green rolling method (a side rolling mill and a universal rolling mill are used together) to build the Payin H-shaped steel plant; the rolling of the rails adopts the traditional two-roll pass method.

3. In 1973, the French Vendell-Sidelor Company developed a new process for rolling steel rails on a four-high rolling mill and obtained a patent. Japan, Brazil, and the United States have followed suit and introduced them.

4. In 1998, Maanshan Iron & Steel rolled out China's first H-beam with a universal rolling mill imported from abroad.

5. Localized import and export: Since then, Laiwu Steel, Rizhao, Jinxi and other steel mills have successively introduced foreign universal rolling mills. By 2007, the number of universal rolling mills in China has shown a rapid increase, and most of the equipment has been imported at high prices from abroad. Among them, in 2003, the 300H section steel production line designed and manufactured by Tianjin Zhongzhong Science and Technology Engineering Co., Ltd. was put into operation, marking the official launch of China's self-developed universal rolling mill. Since then, the universal rolling mills of Dalian Zhengda, Tangshan Shengda, Anshan Zizhu (Anshan No. 3 Rolling), and Anshan Baode, designed and manufactured by Tianjin Zhongzhong, have been put into operation one after another.

If you are interested in our rolling mill machine, please mail at marketing2@hanrm.com.

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300,000 Ton TPY Re-bar Production Line

General Description

1. Design for a Re-bar production line with 300,000MT annual capacity.

2. Finished product size: TMT Re-bar φ10mm—φ38mm, Rolling speed:12-16m/ s.

3. Type of steel: plain steel, carbon constructional quality steel, low-alloy steel, tray screw thread steel, and so on.

4. Raw material: Billet 150mm×150mm×6000mm continuous casting.

5. The Re-bar Production Line Capacity: About 1000MT per 20 hours/day (About 50MT per Hour), 6000 hours/year.

Product scheme

Finished Product: φ10mm~φ38mm TMT Re-bar

Product	Specification（mm）	Type of steel	Annual output（T）
Re-bar	Φ10~φ38	TMT500	300,000
Total			300,000

Brief description of the process

The qualified billet was transported to rolling plant by roller bed, and was heated by the pusher-type furnace to 1050 ~ 1150 ℃, pushed out by discharging machine. Then the billet was fed to roughing rolling millφ550 group by furnace delivery table, after roll 5 passes, cutting by 1# flying shear, then enter into intermediate rolling mill group φ420 mm×8, after sheared by 2# flying shear, then enter into the φ320 mm intermediate mill group(6 stands), after water treatment，enter into conveyor roller bed, and then sheared by dividing shear, enter into rolling piece conveyor roller bed, then enter into cooling bed, cutting by cut-to-length shear, then banded, then delivery or enter into storage. The production process is as follows:

The Composition of rolling mills

The whole production line will be equipped with 20 rolling passes all together, among which, φ550mm 41 rougher mill is the shuttle rolling type mill, and after taking off ends and the semi-finished materials will enter other 20 intermediate(φ420mm×6+φ320mm×6 +φ285×4) finishing rolling mills, which are all the continuous rolling type (DC controlled).

Supply goods scope for Main rolling area

No	Equipment Name	Quantity	W (T)	Remarks
1	φ550 Horizontal rough mill group (2-Hi)	6 groups	300	The complete equipment of the rougher area
2	φ450 Horizontal pre-stressed rolling mill	3groups	150	（neutral gear surface)
3	φ320 Horizontal pre-stressed rolling mill	3 groups	120.7	（neutral gear surface)
4	φ285 2H2V finishing mill group	1 group	44
5	Pneumatic Loop	4 sets	2	Betweenφ320 Horizontal pre-stressed rolling mill andφ285 finishing mill
6	1#cropping shear (cut head)	1 set	3
7	2#Rotary flying shear	1 set	15	（hard gear surface)
8	Divided Shearing	1 set	12	（hard gear surface)
9	Water cooling system after finishing mill (36m)	1 set	12	1 segments water-cooled(with slow cooling according to the drawings)

If you are interested in the 300,000 Ton TPY Re-bar production line, please mail at marketing2@hanrm.com.

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Common Accidents on the Site of High-speed Steel Rolling and Measures (4)

15. What are the reasons for stacking steel between the stands of the finishing mill?

(1) The rolling guide sticks the steel;

(2) The guide wheel does not turn or the bearing burns out;

(3) The rolled piece split;

(4) The guide or the roll ring is installed incorrectly;

(5) The roll gap is not set properly or the incoming material size is not reasonable;

(6) The guide is not fastened.

16. What are the reasons for the poor wire loop of the laying head outlet?

(1) The tension between the rolling mills is too large;

(2) the alignment deviation of the water cooling section, the nozzle duct wear and corrosion cause the rolling operation to be unstable;

(3) The clamping force of the pinch roller is not appropriate due to the wear of the pinch roller ring or the failure of the cylinder link mechanism;

(4) The deviation of the bending line of the spinning tube, the spinning tube is seriously worn, and the spinning tube is sticky connected, the unbalance of the spinning tube causes the loop formation difference;

(5) Improper speed configuration of the finishing mill, pinch roll, and laying head, serious speed fluctuation of the rolling mill, causing the rolling speed to be faster or slower, resulting in uneven coil size;

(6) When the temperature of the rolled piece is high, the coil is too soft, and the coil falls on the receiving platform, and it will become an ellipse or a random circle.

17. What are the common types of damage to rolling guides in finish rolling? What are the causes? How to prevent it?

1) The guide roller bearing is broken, so the guide roller cannot rotate;

2) The guide roller is short of oil, and the bearing is locked;

3) The guide roller lacks water, causing the guide roller to not rotate or burst;

4) The guide roller shaft is broken;

5) The guide roller moves, the screw of the pin is loose;

6) The guide arm is loose.

Solutions:

1) Strictly control the size of the red billet, ensure the same size as the guide, and prevent the thickness of the material from impacting the guide roller.

2) Prevent misalignment of the roll ring, prevent twisting of the rolled piece, and the rolling guide is damaged. The bottom surface of the roll ring needs to be aligned with copper skin.

3) To prevent the roll ring from moving, due to the roll ring movement, the torsion moment is generated in the rolled piece.

4) The guide guard must be aligned to prevent excessive force on one side of the guide roller.

5) Strictly control the installation quality of the rolling guide, prevent the guide roller from moving, the guide guard arm is loose, and the cap screw is tight.

6) Strictly check whether the oil pipes and water pipes are working properly.

18. What common accidents will occur during the production of 27 high-speed roll rings with misaligned holes? How to solve it?

1) The serious slope of finished product;

2) The rolled parts are twisted, are unstable in the water-cooled channel, and are easy to get out of the waste box;

3) Due to the torsion of the rolled parts, the finished guides are easy to damage, resulting in the quality accident;

4) The guide is not easy to align.

Solution: Add copper skin to the bottom of the roller ring.

19. How to deal with the sudden stoppage of the high-speed wire mill?

1) Immediately start flying shearing machine #1, #2, and #3;

2) Emergency stop finishing and pre-finishing;

3) Notify the dispatch room to find the reason;

4) After stopping, ask an operator to the finishing mill to check the condition inside the machine;

5) Roller ring was all replaced or slowly cooled, it is strictly prohibited to cool the roller ring with water.

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Repair Method and Operation Process of Rolling Mill Roll

During the operation of the rolling mill, the roll is easy to be damaged. In order to repair the roll body timely and effectively, it is necessary to judge and analyze from the determination of service life, the identification of crack depth, turning crack and other aspects, so that the rolling mill can return to normal.

Because there is no good method to detect the crack depth of the rolling mill roll, the length of service life can only be judged and determined according to the experience, the type of rolling mill, the type of alloy produced and the roughness of the roll surface. According to the theory, the correct service life should be before the crack depth reaches 3 mm, beyond which the roller surface should be grinded, otherwise it is easy to cause the roller sleeve to burst.

In general, if the crack on the rolling mill roll is open, its depth is deeper than tortoise crack or other microcracks, and the crack width is also larger. Therefore, the longest circumferential crack and the widest crack on the roll surface must be found out correspondingly. Through these cracks, the minimum cutting amount can be determined, and the magnetic particle inspection can be used for crack areas.

In order to ensure the safety, the turning depth of the rolling mill roll needs to add 0.5mm to the crack depth in general, and the roughness of the roll surface after turning shall not be less than 6.3; the surface roughness of the roll surface after grinding shall reach 0.8, which can be compared with the standard block or measured with the roughness detector.


When the defects of the rolling mill roll are turned, magnetic particle inspection shall still be carried out to ensure that all micro-cracks have been eliminated. If there are still micro-cracks, turning is still required. It should be noted that every time the repair is made, the record should be made and kept for the daily backup.

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How to Adjust the Roll Gap?

Adjusting roll hole shape and controlling plate shape are mainly based on rolled products. The rolls are supported and held in a fixed position in the rolling mill. Roller bearings have a large workload and vary widely, so a small coefficient of friction is required.

After determining the products rolled by the rolling mill, the line speed of the rolling mill can be basically confirmed. The hardness of the raw material is measurable. The rolling stock of the rolling mill is determined by changing the plastic deformation size.

How to configure the rolls according to the hole process? Generally, the newly installed rolling mill has a running-in process. During the running-in process, the rolls are run at no load, and the running speed is 50%, 65%, 75%, and 85% in stages. Different rolling mills have different materials and specifications for rolls according to different rolling products.

For example, the continuous casting machine and rolling mill has a daily output of 100 tons and a rolling speed of 15-25 m / s. Rough rolling efficiency accounts for 30% -40%, intermediate rolling efficiency accounts for 50% -60%, and rough rolling efficiency reaches 95%. After the rolling mill is installed, the large and small teeth of the reducer and gearbox need to mesh, the rolling speed is too fast, and the torque is enhanced. After the rolling mill runs normally for 30 consecutive days, stop the rolling mill to check the meshing of the large and small gears. When everything is normal, the rolling speed can be increased.

Under normal circumstances, there is no need to adjust the rolling speed. In the rolling mill, the rolls are constantly worn during operation. In order to maintain the stable operation of the rolling mill when the rolls are under controllable rolling requirements, the rolls must be repaired in time. In severe cases, the rolls need to be replaced.

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Solution to High Temperature of Rolling Mill

In summer, we should pay special attention to the safe operation of the rolling mill in the high-temperature natural environment, improve its maintenance and repair, because the temperature rise is more likely to cause small problems of the rolling mill. First of all, the cooling circulating water of rolling mill roll can not be less, the average temperature is high, and the cooling circulating water volatilizes too fast, which should be added frequently. And check the body of water in time, and if the water body smells smelly, it is necessary to dismantle and replace the cooling circulating water, throw away the sewage, replace the saponification liquid again, and add the water that must be accounted for.

If the rolling mill works for a long time, it will also cause the temperature of the motor to rise, so you have to touch the bearing end cover shell of the motor by hand to see if the temperature is too high. If the temperature is high, it needs to be shut down to reduce the temperature of the motor before it works without overload.

The cycloid reducer is used in the rolling mill, and the installation method is inverted. In high temperature, the temperature rise will occur, which makes the viscosity of the lubricating grease lower and lower, and it will flow into the bearing end cover, resulting in the lack of lubricating grease in the cycloid reducer, leading to the temperature rise of the reducer, and the more severe one will burn the reducer. Therefore, it is necessary to often check whether there is a lack of grease in the reducer to ensure the normal operation of the reducer.

In summer, it is also necessary to check the route of household electrical appliances of rolling mills. The rise of average temperature will accelerate the embrittlement of the route, which is easy to cause short-circuit fault. However, the actual operating staff of the rolling mill shall wear rubber gloves during safe operation, and the temperature of spiral gear after cold rolling is too high, which will burn their hands.

In addition, the roll of the rolling mill shall be cleaned. At the end of daily work and after standby, the roll must be removed. Clean the roller surface with a clean towel and wipe off the air oxide skin adhered on the surface, so as to improve the service life of the roller.

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