ROCHO INDUCTION Provide rolls continuous hardening technology
Date: May 27th, 2022
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ROCHO INDUCTION offers coreless rolls induction heating quenching processes and roll quenching machines with high load capacity (workpiece weight up to several tens of tons, workpiece length up to 6 metres), continuous quenching and segmented continuous quenching, mainly used for the surface quenching of heavy rolls and long thick shaft parts. The machine has manual-automatic operation and is suitable for the production of single and batch parts. The hardening machine is simple to operate, fully functional, reasonably structured and easy to install and commission.
Metallurgical rolls are the main parts of metal rolling equipment, which are used as a special tool to make the metal plastic deformation, rolling out a variety of rolling products. Due to the special service conditions of the rolls, the high consumption and the quality and cost of the rolled material, the performance of the rolls is highly demanding. This has led to the formation of a separate industry for roll manufacture, with many roll manufacturers continuously carrying out in-depth research into the materials, manufacturing processes and performance of rolls to meet the various demands of use.
Roll is different from the general structural parts, working conditions are complex and diverse, rolling process roll body to withstand high stress, mainly bending stress and friction, etc., the main drive roll also subject to huge torque. The surface of the roll body is subjected to friction, abrasion, impact, contact stress and fatigue caused by the excitation of cold and heat for a long time, so, in addition to the conventional mechanical properties, various rolling mills have a series of special requirements for the use of rolls, which are different from other products.
1, Fracture resistance
The ability of the roll body and roll neck to withstand working stress without transverse fracture. For the specific conditions of use, the main thing is that they should have sufficient strength and toughness and be free from manufacturing defects that could lead to fracture.
2, Wear resistance
The ability of the roll body to resist weight loss or size reduction during the rolling process. It should be noted that the wear resistance of the roll in the hot state and in the cold state is not necessarily equivalent to the abrasion resistance, a roll in the cold state using the relative wear resistance is not equal to the relative wear resistance in the hot state, and vice versa. The wear mechanism of work rolls is of various types, including rolling friction, sliding friction caused by the plastic transformation of the rolling material and abrasive wear caused by oxide skin.
3, Antistrip performance
The ability of the roll to act under contact stress for a long time without producing the phenomenon of the roll body falling off the block.
4, Resistance to thermal cracking
Hot rolling rolls are subjected to thermal fatigue from the rolling material and the coolant's radical cooling and heating, and the ability to resist this effect without producing mesh cracking or making the mesh cracking shallow.
5, Thermal shock resistance
Work rolls in the bite into the hot billet when the roll surface local rapid heating or in the case of steel and other accidents due to friction so that the roll surface violent heating, resistance to this thermal shock and does not produce cracks and spalling ability called thermal shock resistance, is an important sign to measure the performance of work rolls.
In addition, there are roughness resistance, bite into sex, etc. For a specific mill of specific rolls, its performance requirements will focus on, and sometimes require a combination of several properties.
ROCHO INDUCTION adopts a coreless inductor heating and quenching process, which can increase the depth of the hardened layer of the roll quenching, the roll in use in a much improved state of force, increasing the number of times the roll is resharpened when it wears, and the life of the roll is extended by 50% to 80%. 1, Roll material
The use of good quenching and permeability of the roll steel is essential. Choose 8CrMoV, 9Cr, 9Cr2, 9CrV or better than 86CrMoV7 quenching permeability DZ801, DZ811 series steel.
2, Preheating and heating
No core induction heating than the power is small, usually using no core high inductor heating quenching rolls preferably by the furnace as a whole preheating, its preheating temperature should be the pursuit of hardening layer depth as the target decision, should also be based on the roll size, inductor power, whether internal and external cooling and whether it is quenched after cold treatment as the target decision, preheating temperature is usually ≥ 500 ~ 560 ℃ for good. Roll heating temperature appropriate to increase 30-45 ℃ and austenitizing time of 8-15min to increase the depth of the hardened layer of roll quenching.
3, Spray water quenching
No core high inductor induction heating quenching rolls, because the heating depth is deep, must use a large amount of water spray quenching, if necessary, also need to use the central hole for a large amount of internal and external cooling, in order to obtain high hard, ultra-deep, the best stress state of quality rolls. The use of large spray holes, large water volume, low water pressure, multi-level steady state of the new water jet, and add air adiabatic expansion of cooling devices.
4, Heating and quenching subsidiary devices and temperature measuring instruments
To use a coreless high inductor on the roll heating and quenching must have the appropriate ancillary devices, including 1) voltage regulator to ensure the adjustment of voltage power and voltage stability. 2) to ensure that there is enough water spray quenching system and low water pressure, large water jets. In addition, as with all induction heating, rolls in induction heating quenching should be accurate temperature measurement instruments, optical pyrometer temperature measurement error is too large, you can choose the United States IRCON infrared thermometer or domestic high-precision induction heating infrared thermometer, SMT furnace temperature tracking protocol.
5, Cold treatment
To get high hardness, super deep quality rolls, by no core high induction heating quenching large must be cold treatment, to have the ability to carry out -120 ℃ cold treatment, in order to adjust the amount of residual austenite rolls due to quenching, to ensure that the rolls have high hard, deeper quenching and hardening layer and the best stress state.
Roll quenching machine configuration and performance.
1, Roll quenching machine tool adopts double-frequency transformer moving mode
2, Roll quenching machine tool motion control using stepper motor drive ball screw drive. Two transformers using the same CNC signal control, to ensure that the two transformers move synchronously. The relative position of the two transformers is adjustable up and down. Speed is infinitely adjustable and stroke positioning is precise. Enhanced CNC system for lathes, easy and intuitive Chinese operating interface, stable and reliable operation, strong resistance to dry flexing. The system can store various workpiece heat treatment process parameters, with large storage capacity.
3, The equipment motion vice adopts standard linear guide rail, equipped with manual lubrication to ensure good lubrication.
4, The bed of the roll quenching machine is a steel structure.
5, The upper top clamping stroke is adjusted by a cycloid reducer driving a trapezoidal screw drive to achieve. By the relay line to achieve the motor forward and reverse rotation to achieve the upper top lift to change the clamping length. The upper top shaft is equipped with a No.3 Morse hole, so that different shapes of top can be exchanged at will.
6, The rotation of the lower centre, i.e. the rotation of the workpiece, is controlled by an asynchronous motor driven by a frequency converter and driven by a synchronous belt. The lower top shaft is equipped with a chuck.
7, The quenching transformer table is a two-dimensional adjustable working platform. The table can be adjusted in the horizontal plane, the adjustment range is 100X100mm, the adjustment mechanism adopts standard linear shaft and linear bearing by trapezoidal screw through the hand wheel adjustment, easy to adjust flexible adjustment accuracy. The counterweight is pulled by a chain, which is safe and reliable and has a long service life.
Roll quenching machine tool can match with medium frequency power supply and ultra audio power supply. The control system adopts PLC, the workpiece rotation and movement adopts frequency conversion speed regulation, the speed can be steplessly adjusted. The quenching process of the rolls is completed with two sets of frequency induction heating equipment, one of which is used for the preheating of the rolls and the other for the quenching of the rolls with medium frequency power, the power is determined by the diameter of the rolls.
ROCHO INDUCTION specialized in high quality induction quenching machines: vertical CNC quenching machines, horizontal automatic quenching machines, multi-station disc CNC quenching machines, customized automatic quenching machines and complete sets of induction quenching equipment. 18 years of specialising in induction quenching, we understand the quenching process better, contact us for the latest solutions.
