The roll is a tool that plastically deforms the (rolled) metal and is an important consumable component that determines the efficiency of the mill and the quality of the rolled material. Roller is an important part of the rolling mill of a rolling mill. It uses the pressure generated when one or a group of rolls rolls to roll the steel. It is mainly subjected to static and dynamic loads during rolling, wear and temperature changes.
First, how are the rolls classified?
The roll is a tool that plastically deforms the (rolled) metal and is an important consumable component that determines the efficiency of the mill and the quality of the rolled material. Roller is an important part of the rolling mill of a rolling mill. It uses the pressure generated when one or a group of rolls rolls to roll the steel. It is mainly subjected to static and dynamic loads during rolling, wear and temperature changes.
There are many types of rolls, and the commonly used roll materials are classified into cast steel rolls, cast iron rolls and forged rolls. The cast steel roll and the cast iron roll belong to the casting roll, all of which are cast and formed, but the cast material is different.
Casting roll: It refers to the type of roll produced by the production method of directly casting molten steel or molten iron.
Forging Roll: It is a processing method that uses a forging machine to apply pressure to a metal blank to produce plastic deformation to obtain a roll with certain mechanical properties, a certain shape and size forgings.
Second, what machines are used for rolls?
Different hardness of the roll body depends on the hardness of the roll body, and the occasions used are also different: (1) The hardness of the roll body is about HRC30-40, used in the roughing mill of the embryonic machine, large-sized steel mill, etc.; (2) The hardness of the roll body is about HRC60 -85, for rough, medium, medium and small section mills. Roughing mills and four-high mills support rolls; (3) roll body hardness of about HRC85-100, for cold rolling mills.
Third, the various materials of the roll processing process is what?
(1) Cast iron roll processing technology: smelting - casting - softening - roughing - heat treatment (increase hardness) - finishing - flaw detection - finished products.
(2) The processing technology of cast steel rolls: Take the alloy cast steel rolls as an example: smelting - casting - roughing - heat treatment - finishing - testing, testing, testing - finished products.
(3) Processing technology of forged steel rolls: Take the work rolls of cold rolling mills as an example: Selected raw materials → EBT preliminary refining → LF refining → Vacuum degassing → Casting → Electroslag remelting → Forging → Spheroidizing annealing → Roughing → Conditioning (quenching + high temperature tempering) → semi-finishing → flaw detection → preheating → double frequency quenching → cold treatment → low temperature tempering → finishing → hardness, ultrasonic and metallography → packaging and shipping.
Fourth, the problem often occurs when processing rolls?
At present, in order to obtain the working efficiency of the rolling mill and reduce the consumption of the rolls, the roll mills often use high-hardness rolls, and it is precisely because of the increased hardness of the rolls that it is difficult for the machinery factories to process the rolls. Large enterprises use CNC machine tools to increase the hardness of the roller, but small companies still use ordinary lathes to process the rollers. In the process, there are often problems such as large machine vibration, difficulty in turning, poor surface finish, etc., affecting processing efficiency and processing quality.
Fifth, how to choose a tool to process high hardness roll?
With continuous research in the tool industry, carbide tools, ceramic tools and cubic boron nitride tools (CBN tools) have been introduced. The following is a brief introduction based on the order of R&D.
For the processing of high hardness roller, carbide tools are used first. Because the hardness of the roller body is generally above HRC45, especially for some alloy cast iron/cast steel, the hardness can reach above HSD90 and the hard alloy can not be processed at all. Afterwards, ceramic cutters were introduced. The machining performance of ceramic cutters is higher than that of cemented carbide cutters in all aspects, but the only drawback is brittleness, and some large rolls are castings. It is inevitable that casting defects (such as hard spots, clamps) will appear. Sand, pores, etc.), encountered the above problems easily chipped, the processing effect is not good. After continuous research and development by the tool industry, Cubic Boron Nitride (CBN) tools have been developed. The hardness is higher than that of carbide tools and ceramic tools. Although it is brittle, it is more resistant to impact than ceramic tools. However, processing high-hardness rolls is still not satisfactory. Afterwards, the non-metallic binder CBN-K1 grades and BN-S20 grades developed by Valin Superhard have increased the toughness compared to traditional CBN tools, which has improved the efficiency of processing high hardness rolls.
Valin superhard non-metallic binder CBN tool BN-K1 is suitable for the processing of high hardness cast iron rolls, non-metallic binder cubic boron nitride tool BN-S20 grade is suitable for high hardness cast steel/forged steel rolls Processing. It not only has high hardness and good wear resistance, but also solves the problem of non-abrasion or chipping of the tool that occurs when high hardness rolls are processed by hard alloy cutting tools and ceramic cutting tools. When a casting defect is encountered, the tool is processed normally without severe wear or chipping. The following is the cutting data table for the BN-K1 and BN-S20 grades of Valin superhard non-metallic binder cubic boron nitride tools.
Valin BN-K1 BN-K1 and BN-S20 grade processing materials and cutting parameters for non-metallic binders
Roll quality directly affects the mill's working efficiency, rolling product quality and output, roll consumption and so on. And the roll as an important consumable part in the rolling process, in the normal rolling process, will be destroyed for many reasons. In particular, the working environment of hot rolling rolls is even worse. The main failure modes of the rollers include cracks, spalling, and breakage (as shown in the figure below). Any failure mode will affect the service life of the roller.
At present, in general iron and steel enterprises, when the roll needs to be repaired due to wear, the roll type is often corrected by turning or grinding. This method has little significance for increasing the life of the roller, but is a remedy. In general, the higher the hardness, the better the abrasion resistance. However, when the hardness and wear resistance of the roller are increased, the toughness will be reduced. In the specific use, the required hardness value shall be determined according to the performance requirements of the specific roller. Roll surface repair and enhanced heat treatment techniques are used to increase the surface hardness of the rolls and reduce the amount of wear that the rolls use, also known as surfacing repair. Most of the surfacing rolls are worn rolls that are worn out and cannot be used. Submerged arc welding of rollers is a common method.
VII. What should you watch out for when surfacing rolls?
(1) Before the welding, the fatigue layer or defects on the surface of the roll body must be removed, especially the crack must be completely removed;
(2) During surfacing, in order to prevent the occurrence of cracks, the roll roll body must be processed to be preheated. The preheating temperature is determined according to the roll roll and the surfacing material.
(3) The key to the success of the welding process in welding is to obtain an ideal surfacing layer that must take into account certain variable factors such as: welding voltage, welding speed, roll speed, roll heat preservation, welding current, welding material, etc. For some roller cores with high carbon and alloying elements, in order to prevent cracks in the brittle zone, in addition to certain preheating measures, low-carbon low-alloy transition layers are used for pre-surfacing transition layers.
(4) Slow cooling and turning after roll surfacing. In order to reduce the cracks caused by the volume stress caused by the surface and internal cooling speeds, the cooling rate must be controlled. Finally, the surfacing welding rolls were turned to restore the original size and finish. And the performance of the surfacing roll: 1) The service life of the roll after surfacing is generally more than doubled; 2) The cost per ton of steel is greatly reduced, and the production effect is improved; 3) The roll after surfacing has a good Crack resistance, wear resistance, cold and hot fatigue resistance.
8. How to turn the roll to its original size and finish after surfacing?
After surfacing, the hardness of the roll body increases, and the roll body is not regular. Therefore, it is difficult to turn the roll body. After processing the surfacing roll, you can select the BN-K1 and BN-S20 brands. The BN-K1 grade is mainly used in high hardness cast iron rolls, and the BN-S20 grade is used in high hardness cast steel/forged steel rolls. For specific cutting parameters, please refer to Valin's Superhard Non-metallic Adhesive Cubic Boron Nitride Tool BN-K1 Table of cutting parameters for grades and BN-S20 grades (form in Question 5).
First, how are the rolls classified?
The roll is a tool that plastically deforms the (rolled) metal and is an important consumable component that determines the efficiency of the mill and the quality of the rolled material. Roller is an important part of the rolling mill of a rolling mill. It uses the pressure generated when one or a group of rolls rolls to roll the steel. It is mainly subjected to static and dynamic loads during rolling, wear and temperature changes.
There are many types of rolls, and the commonly used roll materials are classified into cast steel rolls, cast iron rolls and forged rolls. The cast steel roll and the cast iron roll belong to the casting roll, all of which are cast and formed, but the cast material is different.
Casting roll: It refers to the type of roll produced by the production method of directly casting molten steel or molten iron.
Forging Roll: It is a processing method that uses a forging machine to apply pressure to a metal blank to produce plastic deformation to obtain a roll with certain mechanical properties, a certain shape and size forgings.
Second, what machines are used for rolls?
Different hardness of the roll body depends on the hardness of the roll body, and the occasions used are also different: (1) The hardness of the roll body is about HRC30-40, used in the roughing mill of the embryonic machine, large-sized steel mill, etc.; (2) The hardness of the roll body is about HRC60 -85, for rough, medium, medium and small section mills. Roughing mills and four-high mills support rolls; (3) roll body hardness of about HRC85-100, for cold rolling mills.
Third, the various materials of the roll processing process is what?
(1) Cast iron roll processing technology: smelting - casting - softening - roughing - heat treatment (increase hardness) - finishing - flaw detection - finished products.
(2) The processing technology of cast steel rolls: Take the alloy cast steel rolls as an example: smelting - casting - roughing - heat treatment - finishing - testing, testing, testing - finished products.
(3) Processing technology of forged steel rolls: Take the work rolls of cold rolling mills as an example: Selected raw materials → EBT preliminary refining → LF refining → Vacuum degassing → Casting → Electroslag remelting → Forging → Spheroidizing annealing → Roughing → Conditioning (quenching + high temperature tempering) → semi-finishing → flaw detection → preheating → double frequency quenching → cold treatment → low temperature tempering → finishing → hardness, ultrasonic and metallography → packaging and shipping.
Fourth, the problem often occurs when processing rolls?
At present, in order to obtain the working efficiency of the rolling mill and reduce the consumption of the rolls, the roll mills often use high-hardness rolls, and it is precisely because of the increased hardness of the rolls that it is difficult for the machinery factories to process the rolls. Large enterprises use CNC machine tools to increase the hardness of the roller, but small companies still use ordinary lathes to process the rollers. In the process, there are often problems such as large machine vibration, difficulty in turning, poor surface finish, etc., affecting processing efficiency and processing quality.
Fifth, how to choose a tool to process high hardness roll?
With continuous research in the tool industry, carbide tools, ceramic tools and cubic boron nitride tools (CBN tools) have been introduced. The following is a brief introduction based on the order of R&D.
For the processing of high hardness roller, carbide tools are used first. Because the hardness of the roller body is generally above HRC45, especially for some alloy cast iron/cast steel, the hardness can reach above HSD90 and the hard alloy can not be processed at all. Afterwards, ceramic cutters were introduced. The machining performance of ceramic cutters is higher than that of cemented carbide cutters in all aspects, but the only drawback is brittleness, and some large rolls are castings. It is inevitable that casting defects (such as hard spots, clamps) will appear. Sand, pores, etc.), encountered the above problems easily chipped, the processing effect is not good. After continuous research and development by the tool industry, Cubic Boron Nitride (CBN) tools have been developed. The hardness is higher than that of carbide tools and ceramic tools. Although it is brittle, it is more resistant to impact than ceramic tools. However, processing high-hardness rolls is still not satisfactory. Afterwards, the non-metallic binder CBN-K1 grades and BN-S20 grades developed by Valin Superhard have increased the toughness compared to traditional CBN tools, which has improved the efficiency of processing high hardness rolls.
Valin superhard non-metallic binder CBN tool BN-K1 is suitable for the processing of high hardness cast iron rolls, non-metallic binder cubic boron nitride tool BN-S20 grade is suitable for high hardness cast steel/forged steel rolls Processing. It not only has high hardness and good wear resistance, but also solves the problem of non-abrasion or chipping of the tool that occurs when high hardness rolls are processed by hard alloy cutting tools and ceramic cutting tools. When a casting defect is encountered, the tool is processed normally without severe wear or chipping. The following is the cutting data table for the BN-K1 and BN-S20 grades of Valin superhard non-metallic binder cubic boron nitride tools.
Valin BN-K1 BN-K1 and BN-S20 grade processing materials and cutting parameters for non-metallic binders
Processing material
Recommended cutting parameters and CBN tool number
Cutting speed
Vc(m/min)
Knife depth ap (mm)
Feed rate
Fr(mm/r)
Common CBN tool grades
Cast iron roller (hardness:HRC35-68)
35-120 (Roughing)
1-10
0.15-0.7
BN-K1
60-180 (finishing)
≤1
0.05-0.35
Cast steel roll
(Hardness: ≥ 45HRC)
50-150 (Rough)
1-10
0.15-0.7
BN-S20
60-250 (finishing)
≤1
0.05-0.35
6. The long working time of the roller leads to failure. How can the roll after failure be repaired?
Roll quality directly affects the mill's working efficiency, rolling product quality and output, roll consumption and so on. And the roll as an important consumable part in the rolling process, in the normal rolling process, will be destroyed for many reasons. In particular, the working environment of hot rolling rolls is even worse. The main failure modes of the rollers include cracks, spalling, and breakage (as shown in the figure below). Any failure mode will affect the service life of the roller.
At present, in general iron and steel enterprises, when the roll needs to be repaired due to wear, the roll type is often corrected by turning or grinding. This method has little significance for increasing the life of the roller, but is a remedy. In general, the higher the hardness, the better the abrasion resistance. However, when the hardness and wear resistance of the roller are increased, the toughness will be reduced. In the specific use, the required hardness value shall be determined according to the performance requirements of the specific roller. Roll surface repair and enhanced heat treatment techniques are used to increase the surface hardness of the rolls and reduce the amount of wear that the rolls use, also known as surfacing repair. Most of the surfacing rolls are worn rolls that are worn out and cannot be used. Submerged arc welding of rollers is a common method.
VII. What should you watch out for when surfacing rolls?
(1) Before the welding, the fatigue layer or defects on the surface of the roll body must be removed, especially the crack must be completely removed;
(2) During surfacing, in order to prevent the occurrence of cracks, the roll roll body must be processed to be preheated. The preheating temperature is determined according to the roll roll and the surfacing material.
(3) The key to the success of the welding process in welding is to obtain an ideal surfacing layer that must take into account certain variable factors such as: welding voltage, welding speed, roll speed, roll heat preservation, welding current, welding material, etc. For some roller cores with high carbon and alloying elements, in order to prevent cracks in the brittle zone, in addition to certain preheating measures, low-carbon low-alloy transition layers are used for pre-surfacing transition layers.
(4) Slow cooling and turning after roll surfacing. In order to reduce the cracks caused by the volume stress caused by the surface and internal cooling speeds, the cooling rate must be controlled. Finally, the surfacing welding rolls were turned to restore the original size and finish. And the performance of the surfacing roll: 1) The service life of the roll after surfacing is generally more than doubled; 2) The cost per ton of steel is greatly reduced, and the production effect is improved; 3) The roll after surfacing has a good Crack resistance, wear resistance, cold and hot fatigue resistance.
8. How to turn the roll to its original size and finish after surfacing?
After surfacing, the hardness of the roll body increases, and the roll body is not regular. Therefore, it is difficult to turn the roll body. After processing the surfacing roll, you can select the BN-K1 and BN-S20 brands. The BN-K1 grade is mainly used in high hardness cast iron rolls, and the BN-S20 grade is used in high hardness cast steel/forged steel rolls. For specific cutting parameters, please refer to Valin's Superhard Non-metallic Adhesive Cubic Boron Nitride Tool BN-K1 Table of cutting parameters for grades and BN-S20 grades (form in Question 5).
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