A kind of induction heating method of high magnetic induction grain-oriented silicon steel
Technical field
The invention belongs to steel rolling technical field of heating, relate to a kind of induction heating method of high magnetic induction grain-oriented silicon steel.
Background technology
In order to improve the production efficiency of high magnetic induction grain-oriented silicon steel, keep the stability of batch production, the hot rolling link of many steel mills is devoted to the rolling route of development research low-temperature heat-high temperature rolling always.Wherein, the most superior with electromagnetic induction furnace induction heating technique, the principle of electromagnetic induction heating furnace based on electromagnetic induction, by slab tumbling conveyer, will lie in a horizontal plane in the traversing rear toroidal coil that vertically packs induction heater into of on roller-way 1000 ℃ above intermediate slab upsets, coil is passed to HF oscillation electric current, make slab body in oscillating magnetic field, produce eddy current and carry out secondary induction heating.The plurality of advantages such as it relies on that non-environmental-pollution, iron loss are little, homogeneous heating, heating rate are fast, can meet the harsh requirement to intermediate blank temperature under various rolling conditions.
At present, in world wide, being applied to the industrial electromagnetic induction heating furnace equipment overwhelming majority provides by Japan is complete, the control techniques of slab in induction heating process adopts constant voltage temperature open loop control mode mostly, and heating curve is controlled single, can not adjust flexibly; In heat-processed,, there is abnormal disturbances in the pyrometer value of feedback unstable working condition for temperature detection; Board briquette control accuracy is not high, and temperature oscillation trend appears in soaking zone, and target temperature deviation is between 5 ℃-10 ℃.More than control the adjustment optimization that defect is unfavorable for orientation silicon steel process parameter, after heating of plate blank, end properties stability is not high, can not guarantee the temperature technical requirements after roughing, cannot meet in batches the requirement of getting the raw materials ready of downstream cold rolling process.
Summary of the invention
Technical problem to be solved by this invention is to provide the induction heating method of the high magnetic induction grain-oriented silicon steel of a kind of high stability and high-temperature precision.
For solving the problems of the technologies described above, the invention provides a kind of induction heating method of high magnetic induction grain-oriented silicon steel, comprise the steps:
Steps A is put into induction heater by the slab of high magnetic induction grain-oriented silicon steel and is heated, and initial heating section adopts invertor to set basic voltage, carries out constant voltage and is rapidly heated, and heat-up time, after heating finishes, the temperature of described slab was 1320 ℃ no longer than 25min;
The temperature rise rate of step B described slab under different voltage according to described invertor, sets up temperature rise curve and contravarianter voltage given curve;
Step C sets the temperature of described slab, adopt described invertor to set initial voltage, according to temperature rise curve described in step B and contravarianter voltage given curve, adopt closed loop thermal controller to carry out closed loop intensification, be no more than 11min heat-up time, after intensification finishes, the temperature of described slab is 1360 ℃;
Step D sets the temperature of described slab, adopt described invertor to set initial voltage, according to temperature rise curve described in step B and contravarianter voltage given curve, with described closed loop thermal controller, carry out closed loop soaking, the soaking temperature of described slab is 1360 ℃, and the samming time is 20-45min.
Further, put into before described process furnace heating in described steps A, the board briquette of described high magnetic induction grain-oriented silicon steel is not less than 900 ℃.
Further, the described basic voltage in described steps A is 2300V.
Further, the described initial voltage in described step C is 2000V, and the described initial voltage in described step D is 1500V.
Further, in described step C and described step D, with radiation pyrometer, feed back the temperature of described slab, when deviation appears in the temperature of described feedback slab and the board briquette of described setting, usage ratio integral regulator is adjusted the output voltage of described invertor.
Further, in described step C and described step D, also comprise the temperature of described feedback slab is carried out to filtering process, comprise the steps:
With time variant voltage temperature regulator, the temperature of described radiation pyrometer feedback slab is distributed to array according to sampling order, the temperature-averaging value of getting in every 1 second of radiation pyrometer described in one in described process furnace is unitary sampling value, go extreme value to process the described unitary sampling value in adjacent 10 seconds of described radiation pyrometer, reject maximum value and minimum value in described unitary sampling value, remaining 8 described unitary sampling values are carried out to weight allocation, unitary sampling value stack described in each after described weight allocation is obtained to the real time temperature of described slab.
Further, described step D also comprises following concrete soaking method:
Step D1 sets the temperature of described slab, the temperature of described slab is 1360 ℃, adopt described invertor to set initial voltage, described initial voltage is 1500V, according to temperature rise curve described in step B and contravarianter voltage given curve, with described closed loop thermal controller, carry out closed loop soaking, the samming time is 5min:
Step D2 sets the temperature of described slab, the temperature of described slab is 1360 ℃, adopt described invertor to set initial voltage, described initial voltage is 1300V, according to temperature rise curve described in step B and contravarianter voltage given curve, with described closed loop thermal controller, carry out closed loop soaking, the samming time is 15min:
Step D3 sets the temperature of described slab, the temperature of described slab is 1360 ℃, adopt described invertor to set initial voltage, described initial voltage is 1100V, according to temperature rise curve described in step B and contravarianter voltage given curve, with described closed loop thermal controller, carry out closed loop soaking, the samming time is 0-5min.
Further, the interior oxygen level of described process furnace burner hearth is lower than 1000PPM.
Further, in described process furnace burner hearth, positive pressure differential is 3Pa.
Further, the atmosphere in described process furnace burner hearth is N
2.
The induction heating method of high magnetic induction grain-oriented silicon steel provided by the invention, efficiently solve the not high problem of control accuracy under control disturbance problem that the pyrometer temperature anomaly fluctuation that occurs in heat-processed causes and temperature open loop control mode, the method does not increase investment and production cost, simply, suitability is strong, and it is remarkable to control effect, has guaranteed that the batch of suitability for industrialized production is stablized heats, hot continuous rolling high magnetic induction grain-oriented silicon steel is produced and had obvious performance boost effect.
Accompanying drawing explanation
The slab heating temperature of a kind of high magnetic induction grain-oriented silicon steel that Fig. 1 provides for prior art and contravarianter voltage contrast schematic diagram;
The slab heating temperature of the high magnetic induction grain-oriented silicon steel that Fig. 2 provides for the embodiment of the present invention and contravarianter voltage contrast schematic diagram;
1, initial heating zone, 2, secondary temperature rise section, 3, soaking zone, 4, Temperature Feedback curve.
Embodiment
The induction heating method of a kind of high magnetic induction grain-oriented silicon steel that the embodiment of the present invention provides, comprises the steps, design parameter is in Table 1:
Each heating steps design parameter table of table 1
The slab that steps A is Q01G, the specification high magnetic induction grain-oriented silicon steel that is 200*1130 by the trade mark is put into induction heater and is heated, and adopts invertor to set basic voltage, and wherein, in the present embodiment, basic voltage is 2300V.Then carry out constant voltage and be rapidly heated, heat-up time, heating finished 1320 ℃ of rear board briquettes no longer than 25min, and wherein, slab charging temperature is controlled at more than 900 ℃, kept, below the interior oxygen level 1000PPM of burner hearth, keeping N in burner hearth
2environment positive pressure differential 3Pa, such object is to guarantee that A section heating finishes allly to enter stove slab and possess identical initial heating condition afterwards, for next stage time variant voltage temperature closed loop control the heating basis that provides stable;
The temperature rise rate of step B slab under different voltage according to invertor, sets up the variation relation of board briquette and contravarianter voltage, sets temperature rise curve and contravarianter voltage given curve.
Step C sets the temperature of slab, adopt invertor to set initial voltage, initial voltage is 2000V, according to temperature rise curve in step B and contravarianter voltage given curve, with closed loop thermal controller, carry out closed loop intensification, be no more than 11min heat-up time, after intensification finishes, the temperature-stable of slab is at 1360 ℃;
Step D sets the temperature of slab, adopts invertor to set initial voltage, and initial voltage is 1500V, according to temperature rise curve in step B and contravarianter voltage given curve, with closed loop thermal controller, carry out closed loop soaking, the soaking temperature of slab is 1360 ℃, and the samming time is 20-45min.Wherein, step D can also comprise following concrete soaking method:
Step D1 sets the temperature of slab, and the temperature of slab is 1360 ℃, adopts invertor to set initial voltage, initial voltage is 1500V, according to temperature rise curve in step B and contravarianter voltage given curve, with closed loop thermal controller, carry out closed loop soaking, the samming time is 5min:
Step D2 sets the temperature of slab, and the temperature of slab is 1360 ℃, adopts invertor to set initial voltage, initial voltage is 1300V, according to temperature rise curve in step B and contravarianter voltage given curve, with closed loop thermal controller, carry out closed loop soaking, the samming time is 15min:
Step D3 sets the temperature of slab, and the temperature of slab is 1360 ℃, adopts invertor to set initial voltage, initial voltage is 1100V, according to temperature rise curve in step B and contravarianter voltage given curve, with closed loop thermal controller, carry out closed loop soaking, the samming time is 0-5min.
Time variant voltage temperature closed loop in induction heating process is controlled must reach two objects: the one, and the heating of plate blank speed that gains freedom adjustable, adapts to the adjustment that different process requires; Another is exactly the precision that guarantees temperature objectives value, must introduce temperature closed loop and control.
For guaranteeing that oriented silicon steel is at the induction high stability of heating process in the stove and the high accuracy of slab heating curve, the heating curve that obtains high-performance heats during temperature open loop in early stage is controlled carries out mathematical regression, the temperature rise rate of slab under the different voltage of corresponding invertor, described point obtains the function corresponding relation between slab temperature rise and contravarianter voltage, when design time variant voltage temperature closed loop control techniques, step B section according to the temperature rise curve of design in advance carry out given, contravarianter voltage is given also according to the regression function of described temperature-voltage, carries out given.In the time of need to adjusting the heating curve in certain stage, as long as adjust the funtcional relationship corresponding to temperature-voltage of respective stage, so just realize time variant voltage temperature and controlled, guaranteed the flexible adjustment of heating of plate blank speed.
Because the working of a furnace changes, the equal factor of the disturbance of board briquette feedback or different slab characteristic occurs that described slab actual feedback temperature can not stablize while following described temperature rise curve, temperature with radiation pyrometer feedback slab, when there is deviation in the feedback temperature of slab and the board briquette of setting, the deviation of time variant voltage temperature closed loop controller lock slab design temperature and feedback temperature, PI(proportional integral is used in design) the setter processing of rectifying a deviation, compensating gain using pi regulator output valve as invertor setting voltage output valve, invertor setting voltage output valve is carried out to online trace to be adjusted, eliminate warm temperature deviation, realize the Dynamic Regulating Process of board briquette, all the time guarantee the closed-loop control of board briquette, and the target value of accurately hitting described slab temperature rise curve, finally realize time variant voltage temperature closed loop control techniques.
In the control of time variant voltage temperature closed loop, another one difficult point is exactly how to guarantee temperature actual feedback accurate, steady.For board briquette, the variation of temperature should be slowly stably, and temperature parameter is steady, more favourable to control process.And in actual heat-processed, in sequence of control, use radiation pyrometer as unique value of feedback of temperature detection, highly sensitive due to radiation pyrometer, the factor such as unstable of atmosphere in burner hearth, the temperature fluctuation amplitude of actual feedback is in 7~8 ℃ of left and right (referring to Fig. 1), the input of time variant voltage temperature regulator is caused to great interference, if the accommodation coefficient of gain of time variant voltage temperature regulator responds too fast words, directly have influence on the accurate control of time variant voltage temperature regulator, cause the vibration of setting voltage gain compensation, the failure that finally causes temperature closed loop to be controlled.The fluctuating factor of filter radiation pyrometer is most important to realizing temperature closed loop control process to greatest extent, and technical way is exactly the filter effect that strengthens Temperature Feedback.Specific practice is: the temperature of first with described time variant voltage temperature regulator, radiation pyrometer being fed back to slab is according to temperature sampling order assignment array; with on 04 13rd, 2012 09:21, divide 3# high temperature to count example; the temperature-averaging value of getting in every 1 second of 3# pyrometer in process furnace is unitary sampling value, by (1355.08 ℃ of the unitary sampling values in adjacent 10 seconds of pyrometer; 1355.86 ℃; 1358.2 ℃; 1357.42 ℃; 1356.64 ℃; 1353.13 ℃; 1358.2 ℃; 1353.52 ℃; 1353.91 ℃; 1360.16 ℃) go extreme value to process, (1360.16 ℃ of the maximum value in rejecting unitary sampling value and minimum value; 1353.13 ℃), by (1355.08 ℃ of remaining 8 unitary sampling values; 1355.86 ℃; 1358.2 ℃; 1357.42 ℃; 1356.64 ℃; 1358.2 ℃; 1353.52 ℃; 1353.91 ℃) carry out weight allocation, weight coefficient is successively distributed as (0.05 according to sampling; 0.05; 0.1; 0.2; 0.25; 0.2; 0.1; 0.05), each unitary sampling value and weight coefficient are taken advantage of to (67.754 ℃ of the weight calculation values that obtain; 67.793 ℃; 135.82 ℃; 271.484 ℃; 339.16 ℃; 271.64 ℃; 135.352 ℃; 67.696 ℃) superposeing obtains the real time temperature value of feedback (1356.70 ℃) of slab.Apply after this temperature filtering process, the temperature fluctuation range of controlling for temperature closed loop in whole heat-processed can be controlled in 2 ℃, has significantly strengthened the control effect (referring to Fig. 2) of proportional and integral controller.
As can be seen from comparison with Figure 1 and Figure 2, after the invention process, contravarianter voltage is set and have been realized temperature closed loop regulatory function, voltage change steadily, there is production decline law; By pyrometer temperature filtering algorithm, pyrometer Temperature Feedback value fluctuation range is optimized in 2 ℃ by 7~8 ℃ of left and right before.
The present invention moves the batch production of having carried out high magnetic induction grain-oriented silicon steel Q01G on the electromagnetic induction furnace of steel 1580 hot continuous rolling production lines at Shoudu Iron and Steel Co, production batch 19 is taken turns, 5000 tons of production quantities, heating of plate blank process stabilization, temperature are controlled accurately, finish to gauge product has excellent magnetic characteristics, and in heat-processed, slab temperature rise is stablized, and temperature rise curve repeatability is high, board briquette is stable, obviously fluctuation of nothing, given level and smooth, the dead-beat of soaking stage voltage; Slab bulk temperature after heating is even, any surface finish, and iron scale secondary growing amount is few, and indices reaches the cold rolling demand of getting the raw materials ready.
It should be noted last that, above embodiment is only unrestricted in order to technical scheme of the present invention to be described, although the present invention is had been described in detail with reference to example, those of ordinary skill in the art is to be understood that, can modify or be equal to replacement technical scheme of the present invention, and not departing from the spirit and scope of technical solution of the present invention, it all should be encompassed in the middle of claim scope of the present invention.