CN109885803B - Temperature/power calculation method for double-frequency quenching machining transition process - Google Patents
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Abstract
A temperature/power calculation method for a transition process of double-frequency quenching machining comprises the following steps: the first step is as follows: establishing a quenching expression, and deducing a relational expression of the quenching electric power and the temperature of the roller according to the specific heat relational expression; the second step is that: establishing a heating roller temperature/power mathematical model, and a third step: trial quenching, wherein the total efficiency eta is obtained, and the fourth step is as follows: and obtaining a quenching temperature/power model. The design can establish a temperature/power model for roller quenching, improve the quenching efficiency of the roller and improve the reliability and consistency of the quality of quenched finished products.
Description
Technical Field
The invention relates to a temperature/power calculation method for a transition process of double-frequency quenching processing, which is particularly suitable for obtaining and optimizing a roller quenching process and reducing the trial quenching times of process optimization.
Background
The double-frequency quenching processing technology is used for quenching processing of the double-frequency quenching machine tool on the roller, and the surface hardness of the processed roller is effectively improved, so that the service life of rolled steel by the roller is effectively prolonged. The roller double-frequency quenching and heating comprises two steps: firstly heating by a 50HZ power frequency power supply, then heating by a 250HZ medium frequency power supply, and then spraying cold water on the roller to rapidly cool and quench the roller so as to obtain the expected hardness of the surface of the roller.
For the quenching of the roller, the traditional method is to obtain a temperature model of the quenching processing transition process according to the experience of a technologist and repeated experiments. The traditional method comprises the following steps: the technologist makes a plurality of experimental schemes (such as serial numbers 1-5) according to the empirical data and carries out 5 times of quenching experiments. The contents comprise the outlet temperature of the power frequency coil, the outlet temperature of the intermediate frequency coil, the descending speed of the roller, the preheating temperature and the cooling speed. And selecting a group of temperature processing parameters from the hardness detection of the quenching roller as the quenching process parameters of the roller with the steel specification.
The roll quenching induction heating process is completed in a mode of gradually increasing power. The specific method is that the coil outlet temperature is used as a final temperature target, and the target value of the coil outlet temperature is realized through the gradual increase of multi-stage (such as 6-stage) power.
The invention patent with Chinese patent publication No. CN105063285A and publication date of 2015, 11 and 18 discloses a roll induction quenching process method, which is carried out according to the following steps: 1, preheating a roller to be quenched, wherein the preheating temperature is 220-250 ℃, and the preheating and heat preservation time is 6-12h;2, hoisting the preheated roller to be quenched into a quenching inductor, and clamping in place to ensure that the two axial ends of the roller to be quenched extend out of the quenching inductor by 25-40mm respectively; 3, starting a roller rotating mechanism and heating electrically, and quickly heating the roller body to 900-960 ℃ and preserving heat; and 4, quickly hanging the heated and heat-insulated roller into a spray quenching water tank to carry out spray quenching and cooling on the roller body, thus finishing the induction quenching process. Although this invention enables roll quenching to be achieved, it still suffers from the following drawbacks:
the invention only aims at the processing method of a roller with a specific model, and parameters are obtained by adjusting according to the experience of a technologist and a plurality of tests, so the time consumption is long, the test cost is high!
Disclosure of Invention
The invention aims to solve the problems of more times of quenching trial, high cost of acquiring parameters and long production period in the prior art, and provides a temperature power calculation method for a transition process of double-frequency quenching, which has less times of quenching trial and reduces cost.
In order to achieve the above purpose, the technical solution of the invention is as follows:
a temperature/power calculation method for a double-frequency quenching machining transition process comprises the following steps:
the first step is as follows: establishing a quenching expression, and deducing a relational expression of the quenching electric power and the temperature of the roller according to the specific heat relational expression:
c = Δ Q/m Δ T (formula 1)
In the formula: Δ Q is the amount of heat absorbed or released, in units: j or w.s, m is mass, unit: kg, C is the specific heat, unit: J/Kg. DEG K or w.s/Kg. DEG.C.DELTA.T is the unit temperature of change in units of: at a temperature of,
obtained from (formula 1):
Δ Q = C × m Δ T (formula 2)
Or Δ T = Δ Q/m × C (formula 3)
(formula 2) represents: the mass of the substance is m, the temperature difference is delta T, and the absorbed heat is delta Q, namely work delta Q is applied to the substance;
(formula 3) represents: after applying work Δ Q to a mass m, there is Wen Sheng T, where work is the power P times the heating time T, i.e.:
Δ Q = P × t units: w.s or kw.s (formula 4)
Substituting (formula 4) into (formula 3) to obtain:
Δ T = Ptt/mC (formula 5)
Considering that the electrothermal conversion efficiency and the actual heating mass due to the skin effect are smaller than the corresponding geometric mass, (equation 5) is modified as:
ΔT＝η 1 *η 2 * P × t/ζ × m × C = η × P × t/m × C (formula 6)
In the formula: eta 1 < 1 is the electrical efficiency, η 2 The thermal efficiency is less than 1, zeta = upsilon/rho less than 1 is a heating volume coefficient, upsilon is an actual heating volume, rho is a corresponding geometric volume, and eta = eta is 1 *η 2 ζ is the total efficiency;
the second step is that: establishing a heating roller temperature/power mathematical model:
taking the temperature rise process as an example, (formula 6) is a relational expression of Wen Sheng T and electric power P, the total efficiency eta is an unknown quantity, eta is obtained through tests or according to a production record curve, and after eta is obtained, the temperature rise delta T can be obtained from the electric power P according to (formula 6), or the electric power P to be provided can be obtained according to the required temperature rise delta T;
the mathematical model derivation process of the roller temperature/power comprises the following steps:
for roll heating, the heating time t of (equation 6) is the quotient of the roll heating coil height H and the roll lowering speed V, i.e.:
t = H/V (formula 7)
M in (equation 6) is the geometric mass of the heated portion of the roll, i.e.:
m = ρ × b (formula 8)
In the formula: b is the specific gravity of the steel; ρ is the geometric volume of the heated roll, according to the diameter D1 of the roll and the heating coil
The width H, then:
ρ＝π*D 1 2 * H/4 (formula 9)
Substituting (formula 9) into (formula 8), and substituting (formula 6) together with (formula 7) to obtain:
ΔT＝η4P/C*b*V*π*D 1 2 (formula 10)
The unit of the above formula power P is watt, however, the unit of the heating roll electric power P is kilowatt, so the above formula should be modified as follows:
ΔT＝η4P×10 3 /C*b*V*π*D 1 2 (formula 11)
(equation 11) is a mathematical model of the temperature difference and power of the heating roller, and the parameters need to be input: electric power P, unit: kw, descent speed V, unit: cm/s, steel specific heat C, unit: w.s/Kg. DEG C, steel specific gravity b, unit: kg/cm 3 Roll diameter D1, unit: cm, preheating temperature T 0 The unit is: cm, total efficiency η;
from (equation 11), the power required for heating the roll surface by Δ T:
P＝ΔT*C*b*V*π*D 1 2 /η*4*10 3 (formula 12)
Inputting the parameters to be input (formula 11), namely calculating the temperature difference delta T and the surface temperature of the roller:
T＝ΔT+T 0 (formula 13)
The third step: and (3) trial quenching, and obtaining the total efficiency eta:
measuring the physical parameters of the roller, making a trial quenching processing process table by a quenching technologist according to experience, and performing trial quenching on the roller according to the trial quenching processing process table, wherein the trial quenching step comprises the following steps: first, the roll is heated to a preheating temperature T 0 Then, according to the trial quenching processing process table, the output power of the coil is adjusted in multiple stages in unit time, the roller is quenched, the change curve of the surface temperature T of the roller and the change curve of the power P are recorded in real time, and the surface temperature of the roller corresponding to the change power P in unit time is obtained according to the actual measurement curveThe change of the degree T, and the temperature difference delta T = T-T of the roller surface is calculated by the formula (13) 0 Substituting Δ T into (equation 11) results in the total efficiency η:
η＝C*b*V*π*D 1 2 (T-T 0 )/4P×10 3 (formula 14)
The surface temperature T and the preheating temperature T of the roller 0 Introducing (formula 14) into total quenching power P, coil descending speed V, specific heat C of steel, specific gravity b of steel and roll diameter D1 to obtain a calculated value of total efficiency eta;
the fourth step: obtaining a quenching temperature/power model:
and (5) substituting the calculated value of the total efficiency eta obtained in the third step into (formula 12) to obtain a quenching temperature/power model of the roller of the model.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention relates to a temperature/power calculation method for a double-frequency quenching processing transition process, which can establish a temperature/power model aiming at different types of rollers so as to conveniently realize accurate quenching of the rollers. In the traditional method, a temperature/power model of a quenching processing transition process is obtained by the experience of a technologist and repeated experiments, and the process needs to be repeated for quenching the same roller for multiple times so as to obtain a roller quenching model. It takes long time, consumes a large amount of energy, and the quenching quality is determined by the experience of technologists. The design only needs one to two times of trial quenching to obtain the heating efficiency of the roller with a certain type, so that the temperature/power model of the same type of roller is obtained, the trial quenching times are reduced, the quenching efficiency of the roller is improved, and the quenching cost is reduced. Therefore, the method can establish a temperature/power model for roll quenching, and improves the quenching efficiency of the roll.
2. Compared with the traditional method for obtaining the temperature model of the quenching machining transition process according to the experience of a technologist and repeated experiments, the temperature/power calculation method of the double-frequency quenching machining transition process is provided. The invention has independence and stability, saves time and cost, has no embarrassment of quenching empirical data (quenching model) because of the difference of the experience of technologists and the change of quenching raw materials, and ensures the reliability and consistency of quenching quality. Therefore, the quenching finished product of the method has reliable quality and good consistency.
Drawings
FIG. 1 is a schematic drawing of the quenching process of the present invention.
In the figure: the quenching device comprises a roller 1, a main quenching section 11, a first transition section 12, a second transition section 13, a 50HZ power frequency coil 2 and a 250HZ intermediate frequency coil 3.
Detailed Description
The invention is described in further detail below with reference to the figures and the detailed description of the invention.
Referring to fig. 1, a temperature/power calculation method for a transition process of double-frequency quenching processing includes the following steps:
the first step is as follows: establishing a quenching expression, and deducing a relational expression of the quenching electric power and the temperature of the roller according to the specific heat relational expression:
c = Δ Q/m Δ T (formula 1)
In the formula: Δ Q is the amount of heat absorbed or released, in units: j or w.s, m is mass, unit: kg, C is the specific heat, unit: J/Kg. DEG K or w.s/Kg. DEG.C.DELTA.T is the unit temperature of change in units of: DEG C,
obtainable from (formula 1):
Δ Q = C m Δ T (formula 2)
Or Δ T = Δ Q/m × C (formula 3)
(formula 2) represents: the mass of the substance is m, the temperature difference is delta T, the absorbed heat is delta Q, and the work delta Q is applied to the substance;
(formula 3) represents: after applying work Δ Q to a mass m, there is Wen Sheng T, where work is the power P times the heating time T, i.e.:
Δ Q = P × t units: w.s or kw.s (formula 4)
Substituting (formula 4) into (formula 3) to obtain:
Δ T = Ptt/mC (formula 5)
Considering that the electrothermal conversion efficiency and the actual heating mass due to the skin effect are smaller than the corresponding geometric mass, (equation 5) is modified as:
ΔT＝η 1 *η 2 * P × t/ζ × m × C = η × P × t/m × C (formula 6)
In the formula: eta 1 < 1 is the electrical efficiency, η 2 The thermal efficiency is less than 1, zeta = upsilon/rho less than 1 is a heating volume coefficient, upsilon is an actual heating volume, rho is a corresponding geometric volume, and eta = eta is 1 *η 2 ζ is the total efficiency;
the second step is that: establishing a heating roller temperature/power mathematical model:
taking the temperature rise process as an example, (formula 6) is a relational expression of Wen Sheng T and electric power P, the total efficiency eta is an unknown quantity, eta is obtained through tests or according to a production record curve, and after eta is obtained, the temperature rise delta T can be obtained from the electric power P according to (formula 6), or the electric power P to be provided can be obtained according to the required temperature rise delta T;
the mathematical model derivation process of the roller temperature/power comprises the following steps:
for roll heating, the heating time t of (equation 6) is the quotient of the roll heating coil height H and the roll lowering speed V, i.e.:
t = H/V (formula 7)
M in (equation 6) is the geometric mass of the heated portion of the roll, i.e.:
m = ρ × b (formula 8)
In the formula: b is the specific gravity of the steel; ρ is the geometric volume of the heated roll, according to the diameter D1 of the roll and the heating coil
The width H, then:
ρ＝π*D 1 2 * H/4 (formula 9)
Substituting (formula 9) into (formula 8), and substituting (formula 6) together with (formula 7) to obtain:
ΔT＝η4P/C*b*V*π*D 1 2 (formula 10)
The unit of the above formula power P is watt, however, the unit of the heating roll electric power P is kilowatt, so the above formula should be modified as follows:
ΔT＝η4P×10 3 /C*b*V*π*D 1 2 (formula 11)
(equation 11) is a mathematical model of the heating roll temperature difference/power, and the input parameters are required: electric power P, unit: kw, descent speed V, unit: cm/s, steel specific heat C, unit: w.s/Kg. DEG C, steel specific gravity b, unit: kg/cm 3 Roll diameter D1, unit: cm, preheating temperature T 0 The unit is: cm, total efficiency η;
from (equation 11), the power required for heating the roll surface by Δ T:
P＝ΔT*C*b*V*π*D 1 2 /η*4*10 3 (formula 12)
Inputting the parameters to be input (formula 11), namely calculating the temperature difference delta T and the surface temperature of the roller:
T＝ΔT+T 0 (formula 13)
The third step: and (3) trial quenching, and obtaining the total efficiency eta:
measuring the physical parameters of the roller, making a trial quenching processing process table by a quenching technologist according to experience, and performing trial quenching on the roller according to the trial quenching processing process table, wherein the trial quenching step comprises the following steps: first, the roll is heated to a preheating temperature T 0 Then, according to a trial quenching process table, the output power of the coil is adjusted in multiple stages in unit time, the roll is quenched, a change curve of the surface temperature T of the roll and a change curve of the power P are recorded in real time, the change condition of the change power P corresponding to the surface temperature T of the roll in unit time is obtained according to an actual measurement curve, and the surface temperature difference delta T = T-T of the roll is calculated by the formula 13 0 Substituting Δ T into (equation 11) results in the total efficiency η:
η＝C*b*V*π*D 1 2 (T-T 0 )/4P×10 3 (formula 14)
The surface temperature T and the preheating temperature T of the roller 0 Introducing (formula 14) into total quenching power P, coil descending speed V, specific heat C of steel, specific gravity b of steel and roll diameter D1 to obtain a calculated value of total efficiency eta;
the fourth step: obtaining a quenching temperature/power model:
and (5) substituting the calculated value of the total efficiency eta obtained in the third step into (formula 12) to obtain a quenching temperature/power model of the roller of the model.
The principle of the invention is illustrated as follows:
based on a heat capacity theory, the invention establishes a relational expression between double-frequency quenching electric power P and roller temperature difference delta T, and theoretically determines a quenching processing transition process temperature/power model. Provides a theoretical basis for the supply of quenching energy (electric quantity) of cylindrical steel (rollers) with different materials and specifications.
The traditional quenching process has the following difficulties: referring to fig. 1, in the drawing, a roller descends at a constant speed V, and the process requires that the roller neck of the roller is heated up by a 50HZ power frequency coil 2 and a 250HZ intermediate frequency coil 3, and then the temperature of the roller body reaches the steady-state temperature required by quenching, and the process is called a transition process. Meanwhile, due to the requirement on the hardness of the soft strip of the roller, a certain requirement is also imposed on the temperature rise curve of the roller neck 13 of the roller. In the transient transition process, the temperature change of the soft strip of the roller and the surface temperature of the roller body of the roller both meet the ideal temperature curve of the quenching processing of the roller. In order to realize the quenching temperature processing curve, technologists formulate a quenching process processing table corresponding to the temperature/power of the roller according to experience, perform trial quenching, further adjust the quenching process processing table according to the detection result of the quenching quality of the roller, and perform secondary trial quenching until satisfactory quenching quality is obtained. The method has the disadvantages that different technologists can give different quenching process processing tables, the quenching processing process of the corresponding roller is lack of uniqueness, the quenching quality is not easy to guarantee, and multiple quenching test tests are needed to obtain the corresponding relation of temperature and power. The method is characterized in that 1-2 times of quenching tests are carried out according to a quenching temperature curve and a temperature/power calculation model in a double-frequency quenching transition process, and after a temperature efficiency eta coefficient is determined, a relational expression of quenching electric power and temperature of a roller (change in material and physical dimension) of a certain type can be obtained. Compared with the traditional method, the method greatly reduces the test times, improves the production efficiency, reduces the roller loss and improves the product processing quality.
Example 1:
a temperature/power calculation method for a transition process of double-frequency quenching machining is characterized by comprising the following steps: the calculation method comprises the following steps:
the first step is as follows: establishing a quenching expression, and deducing a relational expression of the quenching electric power and the temperature of the roller according to the specific heat relational expression:
c = Δ Q/m Δ T (formula 1)
In the formula: Δ Q is the amount of heat absorbed or released, in units: j or w.s, m is mass, unit: kg, C is the specific heat, unit: J/Kg. DEG K or w.s/Kg. DEG.C.DELTA.T is the unit temperature of change in units of: DEG C,
obtainable from (formula 1):
Δ Q = C m Δ T (formula 2)
Or Δ T = Δ Q/m × C (formula 3)
(formula 2) represents: the mass of the substance is m, the temperature difference is delta T, the absorbed heat is delta Q, and the work delta Q is applied to the substance;
(formula 3) represents: after applying work Δ Q to a mass m, there is a temperature difference Δ T, where work is power P multiplied by heating time T, i.e.:
Δ Q = P × t units: w.s or kw.s (formula 4)
Substituting (formula 4) into (formula 3) to obtain:
Δ T = Ptt/mC (formula 5)
Considering that the electrothermal conversion efficiency and the actual heating mass due to the skin effect are smaller than the corresponding geometric mass, (equation 5) is modified as:
ΔT＝η 1 *η 2 * P × t/ζ × m × C = η × P × t/m × C (formula 6)
In the formula: eta 1 < 1 is the electrical efficiency, η 2 The thermal efficiency is less than 1, zeta = upsilon/rho less than 1 is a heating volume coefficient, upsilon is an actual heating volume, rho is a corresponding geometric volume, and eta = eta is 1 *η 2 ζ is the total efficiency;
the second step is that: establishing a mathematical model of the temperature/power of the heating roller:
taking the temperature rise process as an example, (formula 6) is a relational expression of the temperature difference Δ T and the electric power P, the total efficiency η is an unknown quantity, η is calculated through a test or according to a production record curve, and after η is obtained, the temperature difference Δ T can be calculated from the electric power P according to (formula 6), or the electric power P to be supplied can be calculated according to the required temperature difference Δ T;
roll temperature/power mathematical model derivation process:
for roll heating, the heating time t of (equation 6) is the quotient of the roll heating coil height H and the roll lowering speed V, i.e.:
t = H/V (formula 7)
M in (equation 6) is the geometric mass of the heated portion of the roll, i.e.:
m = ρ × b (formula 8)
In the formula: b is the specific gravity of the steel; ρ is the geometric volume of the heated roll, according to the diameter D1 of the roll and the heating coil
The width H, then:
ρ＝π*D 1 2 * H/4 (formula 9)
Substituting (equation 9) into (equation 8), and then substituting (equation 6) together with (equation 7) to obtain:
ΔT＝η4P/C*b*V*π*D 1 2 (formula 10)
The unit of the above formula power P is watt, however, the unit of the heating roll electric power P is kilowatt, so the above formula should be modified as follows:
ΔT＝η4P×10 3 /C*b*V*π*D 1 2 (formula 11)
(equation 11) is a mathematical model of heating roll temperature/power, and requires input parameters: electric power P, unit: kw, descent speed V, unit: cm/s, steel specific heat C, unit: w.s/Kg. DEG C, steel specific gravity b, unit: kg/cm 3 Roll diameter D1, unit: cm, preheating temperature T 0 The unit: cm, total efficiency η;
from (equation 11), the power required for heating the roll surface by Δ T:
P＝ΔT*C*b*V*π*D 1 2 /η*4*10 3 (formula 12)
Inputting the parameters to be input (formula 11), namely calculating the temperature difference delta T and the surface temperature of the roller:
T＝ΔT+T 0 (formula 13)
The third step: and (3) trial quenching, and obtaining the total efficiency eta:
measuring the physical parameters of the roller, making a trial quenching processing process table according to experience by a quenching technologist,and then carrying out trial quenching on the roller according to a trial quenching processing process table, wherein the trial quenching steps are as follows: first, the roll is heated to a preheating temperature T 0 Then, according to a trial quenching process table, the output power of the coil is adjusted in multiple stages in unit time, the roll is quenched, a change curve of the surface temperature T of the roll and a change curve of the power P are recorded in real time, the change condition of the change power P corresponding to the surface temperature T of the roll in unit time is obtained according to an actual measurement curve, and the surface temperature difference delta T = T-T of the roll is calculated by the formula 13 0 Substituting Δ T into (equation 11) results in the total efficiency η:
η＝C*b*V*π*D 1 2 (T-T 0 )/4P×10 3 (formula 14)
The surface temperature T and the preheating temperature T of the roller 0 Introducing (formula 14) into the quenching total power P, the coil descending speed V, the specific heat C of the steel, the specific gravity b of the steel and the diameter D1 of the roller to obtain a calculated value of the total efficiency eta;
the fourth step: obtaining a quenching temperature/power model:
and (5) substituting the calculated value of the total efficiency eta obtained in the third step into (formula 12) to obtain a quenching temperature/power model of the roller of the model.
Example 2:
example 2 is substantially the same as example 1 except that:
the third step: and (3) trial quenching, and obtaining the total efficiency eta:
measuring the physical parameters of the roller, the length of the roller: l =170cm, roll diameter: d 1 =61cm,50hz power frequency coil inner diameter: d 2 Inner diameter of intermediate frequency coil of =63cm, 250hz: d 3 =65.6cm, heating coil width: h 1 ＝H 2 = H =16.5cm, distance between heating coils: h 3 Steel specific gravity =4 cm: b =7.8 × 10 －3 kg/cm 3 Roll lowering speed: v =0.07cm/s, specific heat of roll: c =450w.s/kg. ℃, preheating temperature of roll: t is 0 ＝300℃，
A quenching technologist formulates a trial quenching processing process table according to experience, and then performs trial quenching on the roller according to the trial quenching processing process table, wherein the trial quenching steps are as follows:first, the roll is heated to a preheating temperature T 0 And =300 ℃, then, according to a trial quenching processing process table, performing multi-stage adjustment on the output power of the coil in unit time, quenching the roller, recording a change curve of the surface temperature T of the roller and a change curve of the power P in real time, and obtaining the change condition of the change power P corresponding to the surface temperature T of the roller in unit time according to an actual measurement curve: power frequency heating electric power: p =554kw, measured temperature of roll surface: t =875 ℃, and the roll surface temperature difference Δ T = T-T is calculated from (equation 13) 0 Substituting Δ T into (equation 11) results in the total efficiency η:
η＝C*b*V*π*D 1 2 (T-T 0 )/4P×10 3 (formula 14)
The surface temperature T =875 ℃ of the roller and the preheating temperature T 0 =300 ℃, total quenching power P =554kw, coil descending speed V =0.07cm/s, specific heat C =450w.s/kg DEG, specific gravity b =7.8 × 10 －3 kg/cm 3 Diameter D of roll 1 =61cm into (equation 14), resulting in an overall efficiency η =0.745;
the fourth step: obtaining a quenching temperature/power model:
substituting the calculated value of the total efficiency eta =0.745 obtained in the third step into (equation 12), and obtaining the quenching temperature rise model of the roller of the model.
Table one: actual measurement and calculation results of heating roller
Claims (1)
1. A temperature/power calculation method for a double-frequency quenching machining transition process comprises the following steps:
the first step is as follows: establishing a quenching expression, and deducing a relational expression of the quenching electric power and the temperature of the roller according to the specific heat relational expression:
c = Δ Q/m Δ T (formula 1)
In the formula: Δ Q is the amount of heat absorbed or released, in units: j or w.s, m is mass, unit: kg, C is the specific heat, unit: J/Kg. DEG K or w.s/Kg. DEG.C.DELTA.T is the unit temperature of change in units of: at a temperature of,
obtainable from (formula 1):
Δ Q = C × m Δ T (formula 2)
Or Δ T = Δ Q/m × C (formula 3)
(formula 2) represents: the mass of the substance is m, the temperature difference is delta T, and the absorbed heat is delta Q, namely work delta Q is applied to the substance;
(formula 3) represents: after applying work Δ Q to a mass m, there is Wen Sheng T, where work is the power P times the heating time T, i.e.:
Δ Q = P × t units: w.s or kw.s (formula 4)
Substituting (formula 4) into (formula 3) to obtain:
Δ T = Ptt/mC (formula 5)
Considering that the electrothermal conversion efficiency and the actual heating mass due to the skin effect are smaller than the corresponding geometric mass, (equation 5) is modified as:
ΔT＝η 1 *η 2 * P × t/ζ × m × C = η × P × t/m × C (formula 6)
In the formula: eta 1 < 1 is the electrical efficiency, η 2 The thermal efficiency is less than 1, zeta = upsilon/rho less than 1 is a heating volume coefficient, upsilon is an actual heating volume, rho is a corresponding geometric volume, and eta = eta is 1 *η 2 ζ is the total efficiency;
the second step is that: establishing a heating roller temperature/power mathematical model:
taking the temperature rise process as an example, the (formula 6) is a relational expression of Wen Sheng T and electric power P, the total efficiency eta is an unknown quantity, eta is obtained through tests or according to a production recording curve, and after eta is obtained, the temperature rise delta T can be obtained from the electric power P according to the (formula 6), or the electric power P to be provided can be obtained according to the required temperature rise delta T;
the mathematical model derivation process of the roller temperature/power comprises the following steps:
for roll heating, the heating time t of (equation 6) is the quotient of the roll heating coil height H and the roll lowering speed V, i.e.:
t = H/V (formula 7)
M in (equation 6) is the geometric mass of the heated portion of the roll, i.e.:
m = ρ £ b (formula 8)
In the formula: b is the specific gravity of the steel; ρ is the geometric volume of the heating roll, and is obtained from the roll diameter D1 and the heating coil width H:
ρ＝π*D 1 2 * H/4 (formula 9)
Substituting (formula 9) into (formula 8), and substituting (formula 6) together with (formula 7) to obtain:
ΔT＝η4P/C*b*V*π*D 1 2 (formula 10)
The unit of the above formula power P is watt, however, the unit of the heating roll electric power P is kilowatt, so the above formula should be modified as follows:
ΔT＝η4P×10 3 /C*b*V*π*D 1 2 (formula 11)
(equation 11) is a mathematical model of the temperature difference and power of the heating roller, and the parameters need to be input: electric power P, unit: kw, descent speed V, unit: cm/s, steel specific heat C, unit: w.s/Kg. DEG C, steel specific gravity b, unit: kg/cm 3 Roll diameter D1, unit: cm, preheating temperature T 0 The unit: cm, total efficiency η;
from (equation 11), the power required for heating the roll surface by Δ T:
P＝ΔT*C*b*V*π*D 1 2 /η*4*10 3 (formula 12)
Inputting the parameters to be input (formula 11), namely calculating the temperature difference delta T and the surface temperature of the roller:
T＝ΔT+T 0 (formula 13)
The third step: and (3) trial quenching, and obtaining the total efficiency eta:
measuring the physical parameters of the roller, making a trial quenching processing process table by a quenching technologist according to experience, and performing trial quenching on the roller according to the trial quenching processing process table, wherein the trial quenching step comprises the following steps: first, the roll is heated to a preheating temperature T 0 Then, according to the trial quenching process table, the output power of the coil is adjusted in multiple stages in unit time, the roll is quenched, the change curve of the roll surface temperature T and the change curve of the power P are recorded in real time, the change condition of the change power P corresponding to the roll surface temperature T in unit time is obtained according to the actual measurement curve, and the roll surface temperature difference delta is calculated by the equation (13)T＝T-T 0 Substituting Δ T into (equation 11) results in the total efficiency η:
η＝C*b*V*π*D 1 2 (T-T 0 )/4P×10 3 (formula 14)
The surface temperature T and the preheating temperature T of the roller 0 Introducing (formula 14) into total quenching power P, coil descending speed V, specific heat C of steel, specific gravity b of steel and roll diameter D1 to obtain a calculated value of total efficiency eta;
the fourth step: obtaining a quenching temperature/power model:
and (5) substituting the calculated value of the total efficiency eta obtained in the third step into (formula 12) to obtain a quenching temperature/power model of the roller of the model.
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| CN101215627A (en) * | 2007-12-27 | 2008-07-09 | 武汉宝德机电有限责任公司 | Intermediate frequency through hardening method for small diameter roller |
| CN103069357A (en) * | 2010-06-07 | 2013-04-24 | 杰森·A·苏利万 | Systems and methods form providing a dynamically modular processing unit |
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