Induction heated roll apparatus

Abstract

The present invention for eliminating a need for a temperature detecting element adapted to measure the temperature of a roll main body provides an induction heated roll apparatus including: a roll main body; a magnetic flux generating mechanism including an iron core and a winding; and a power supply circuit provided with a control element adapted to control AC current or AC voltage. The apparatus calculates the temperature of the roll main body using an AC current value obtained by an AC current detecting part, an AC voltage value obtained by an AC voltage detecting part, a power factor obtained by a power factor detecting part, a winding resistance value of the winding, and an excitation resistance obtained from characteristics of a relationship between a magnetic flux density and an excitation resistance of a magnetic circuit including the iron core and the roll main body as parameters.

Claims

1. An induction heated roll apparatus comprising: a roll main body that is rotatably supported; a magnetic flux generating mechanism that is provided inside the roll main body and includes an iron core and a winding wound around the iron core; and a power supply circuit that is connected to the winding and provided with a controller that controls AC current or AC voltage, the induction heated roll apparatus lacking a temperature detecting element for measuring a temperature of the roll main body, and the induction heated roll apparatus further comprising: a roll temperature calculation data storage that stores magnetic flux density-excitation resistance relationship data indicating a relationship between magnetic flux density generated by the magnetic flux generating mechanism and an excitation resistance of a magnetic circuit configured to include the iron core and the roll main body; a processor; and a memory storing instructions that, when executed by the processor, cause the processor to execute a roll temperature calculator that calculates the temperature of the roll main body with use of, as parameters, an AC current value obtained by an AC current detector that detects the AC current flowing through the winding, an AC voltage value obtained by an AC voltage detector that detects AC voltage applied to the winding, a power factor obtained by a power factor detector that detects the power factor of an induction heated roll including the roll main body and the magnetic flux generating mechanism, a winding resistance value of the winding, and an excitation resistance value obtained from the magnetic flux density-excitation resistance relationship data and a characteristic of the relationship between magnetic flux density generated by the magnetic flux generating mechanism and the excitation resistance of the magnetic circuit configured to include the iron core and the roll main body.

2. The induction heated roll apparatus according to claim 1, wherein the roll temperature calculator calculates the temperature of the roll main body by using a resistance value of the roll main body and a relative permeability of the roll main body, wherein the resistance value of the roll main body is calculated using, as parameters, the AC current value obtained by the AC current detector, the AC voltage value obtained by the AC voltage detector, the power factor obtained by the power factor detector, the winding resistance value, and the excitation resistance value obtained from the characteristic of the relationship between the magnetic flux density and the excitation resistance of the magnetic circuit.

3. The induction heated roll apparatus according to claim 1, comprising: a winding temperature detector that detects a temperature of the winding; and a resistance value calculator, included in the memory and executable by the processor, that calculates the winding resistance value from the temperature of the winding, the temperature being obtained by the winding temperature detector, wherein the roll temperature calculator calculates the temperature of the roll main body with use of the winding resistance value obtained by the resistance value calculator.

4. The induction heated roll apparatus according to claim 1, comprising: a DC voltage applicator that controls a DC power supply to intermittently apply DC voltage to the winding; and a resistance value calculator, included in the memory and executable by the processor, that calculates the winding resistance value from the DC voltage applied by the DC voltage applicator and DC current flowing through the winding when applying the DC voltage, wherein the roll temperature calculator calculates the temperature of the roll main body with use of the winding resistance value obtained by the resistance value calculator.

5. The induction heated roll apparatus according to claim 1, wherein given that a temperature difference between an inner surface temperature and a surface temperature of the roll main body is [ C.], the roll temperature calculator corrects the temperature of the roll main body with use of the temperature difference obtained from
=kP/[2/{ln(d.sub.2/d.sub.1)/}] (where d.sub.1 is an inside diameter [m] of the roll main body, d.sub.2 is an outside diameter [m] of the roll main body, is a thermal conductivity [W/m.Math. C.] of the roll main body at average temperature, P is a thermal flow rate [W/m], and k is a correction factor).

6. The induction heated roll apparatus according to claim 5, wherein inside a lateral circumferential wall of the roll main body, jacket chambers in which a gas-liquid two-phase heating medium is included are formed, and given that a cross-sectional area of the roll main body is S, a sum of cross-sectional areas of the jacket chambers is S.sub.j, a thickness of the roll main body is t, and a variable indicating a ratio of a reduction of a function of the jacket chambers is , wherein the reduction is caused by a reduction in pressure of the heating medium along with a reduction in temperature, the roll temperature calculator corrects the temperature of the roll main body with use of the temperature difference obtained on an assumption that the inside diameter d.sub.1 of the roll main body is substituted by d.sub.j1=d.sub.1+t{1(1S.sub.j/S)}, and the outside diameter d.sub.2 of the roll main body is substituted by d.sub.j2=d.sub.2t{1(1S.sub.j/S)}.

7. The induction heated roll apparatus according to claim 1, wherein the controller uses a semiconductor to control a conduction angle of current or voltage, the induction heated roll apparatus further comprising: an impedance calculator that calculates an impedance with use of: the AC current value obtained by the AC current detector, the AC voltage value obtained by the AC voltage detector, and the power factor obtained by the power factor detector; and an impedance corrector that, with use of the conduction angle controlled by the controller, corrects the impedance obtained by the impedance calculator, wherein the roll temperature calculator calculates the temperature of the roll main body with use of corrected impedance resulting from the correction by the impedance corrector.

8. The induction heated roll apparatus according to claim 1, wherein the roll temperature calculator calculates an inner surface temperature of the roll main body, in addition to calculating a surface temperature calculation value of the roll main body in a steady state from the inner surface temperature, and calculates a surface temperature of the roll main body during a transient period, on a premise that the surface temperature of the roll main body reaches the surface temperature calculation value after a time period T given by T=kwcc/(2) [h] (where w is a specific gravity [kg/m.sup.3] of a material of the roll main body, c is a specific heat [kcal/kg.Math. C.] of the material of the roll main body, t is a thickness [m] of the roll main body, is a thermal conductivity [kcal/m.Math.h.Math. C.] of the material of the roll main body, and k is a correction factor obtained from a measured value).

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a diagram schematically illustrating a configuration of an induction heated roll apparatus according to the present embodiment;

(2) FIG. 2 is a functional configuration diagram of a control device in the same embodiment;

(3) FIG. 3 is a diagram illustrating a temperature calculation flow in the same embodiment;

(4) FIG. 4 is a diagram illustrating an equivalent circuit of a single phase induction heated roll (single phase roll);

(5) FIG. 5 is a characteristics graph illustrating a relationship between magnetic flux density and relative permeability of carbon steel (S45C);

(6) FIG. 6 is a characteristics graph illustrating a relationship between temperature and thermal conductivity of carbon steel (S45C);

(7) FIG. 7 is a characteristics graph illustrating a relationship between magnetic flux density and excitation resistance of a magnetic circuit configured to include a roll main body made of carbon steel (S45C) and an iron core formed from a grain-oriented silicon steel sheet;

(8) FIG. 8 is a diagram illustrating temperature change characteristics of the roll main body during a temperature rise transient period;

(9) FIG. 9 is a diagram illustrating temperature change characteristics of the roll main body during a temperature fall transient period;

(10) FIG. 10 is a diagram schematically illustrating a configuration of an induction heated roll apparatus according to a variation; and

(11) FIG. 11 is a functional configuration diagram of a control device in the same variation.

DESCRIPTION OF EMBODIMENTS

(12) In the following paragraphs, one embodiment of an induction heated roll apparatus according to the present invention is described with reference to the drawings.

(13) As illustrated in FIG. 1, an induction heated roll apparatus 100 according to the present embodiment includes: a roll main body 2 that is rotatably supported; a magnetic flux generating mechanism 3 that is provided inside the roll main body 2 and includes an iron core 31 and a winding 32 wound around the iron core 31; and a power supply circuit 5 that is connected to the winding 32 and provided with a control element 4 adapted to control AC current or AC voltage.

(14) Inside the lateral circumferential walls of the roll main body 2, multiple jacket chambers 2S in which a gas-liquid two-phase heating medium is included are formed in a circumferential direction at regular intervals. Also, the control element 4 in the present embodiment uses a semiconductor to control the conduction angle of the AC current or the AC voltage, and specifically, is a thyristor.

(15) Further, a control device 6 adapted to control the induction heated roll apparatus 100 of the present embodiment has a surface temperature calculating function that calculates the temperature of the roll main body 2 using a value of the AC current flowing through the winding 32, a value of the AC voltage applied to the winding 32, a power factor of an induction heated roll 200 including the roll main body 2 and the magnetic flux generating mechanism 3, a winding resistance value of the winding 32, and an excitation resistance value of a magnetic circuit configured to include the iron core 31 and the roll main body 2 as parameters.

(16) Specifically, the control device 6 is a dedicated or general-purpose computer including a CPU, an internal memory, an A/D converter, a D/A converter, an input/output interface, and the like. Also, the CPU and peripheral devices operate according to a predetermined program stored in the internal memory, and thereby as illustrated in FIG. 2, the control device 6 fulfills functions as an impedance calculation part 61, an impedance correction part 62, a roll temperature calculation data storage part 63, a roll temperature calculation part 64, a roll temperature control part 65, and the like.

(17) In the following, the respective parts are described with reference to a temperature calculation flowchart in FIG. 3 together with FIG. 2.

(18) The impedance calculation part 61 calculates the impedance (roll impedance) Z.sub.1 (=Vcos /I=r.sub.comb) of the induction heated roll 200 from the AC current value obtained by an AC current detecting part 7 adapted to detect the AC current I flowing through the winding 32, the AC voltage value obtained by an AC voltage detecting part 8 adapted to detect the AC voltage V applied to the winding 32, and the power factor obtained by a power factor detecting part 10 ((1) in FIG. 3).

(19) Further, the impedance calculation part 61 calculates the resistance of the roll main body (roll main body resistance) r.sub.2 from the impedance r.sub.comb, the winding resistance r.sub.1 obtained from winding temperature .sub.c[ C.] obtained by a temperature detecting part 9 adapted to detect the temperature of the winding 32, and the excitation resistance r.sub.0 obtained from characteristics of the preliminarily measured relationship between magnetic flux density and magnetic resistance of the magnetic circuit (see FIG. 7) ((2) in FIG. 3). In addition, the temperature detecting part 9 is embedded in the winding 32.

(20) Specifically, the impedance calculation part 61 calculates the winding resistance r.sub.1 using the following expressions, and then calculates the resistance r.sub.2 of the roll main body.
r.sub.1=kL/100S[]
k=2.1(234.5+.sub.c)/309.5

(21) Here, L is the wire length [m], S is the wire cross-sectional area [mm.sup.2], and .sub.c is the winding temperature [ C.].

(22) Also, the impedance calculation part 61 converts the resistance r.sub.2 of the roll main body to a secondary side conversion value as viewed from the roll main body side. Given that the secondary side conversion resistance of the roll main body having a unit of is R.sub.2, and the number of turns of the winding is N, the relationship among them is given by the following expression.
R.sub.2=(r.sub.2/N.sup.2)10.sup.6

(23) The impedance correction part 62 corrects the secondary side conversion resistance R.sub.2 of the roll main body using the conduction angle (phase angle of the control element (thyristor) 4 ((3) in FIG. 3).

(24) Specifically, the impedance correction part 62 corrects the impedance R.sub.2 using the following expression.
R.sub.2=aR.sub.x

(25) Given that C=V/V.sub.in,
a=a.sub.nC.sup.n+a.sub.n1C.sup.n1+a.sub.n2C.sup.n2+, . . . ,+a.sub.2C.sup.2+a.sub.1C+a.sub.0.

(26) Here, a.sub.n is a factor that is determined for each induction heated roll apparatus and based on measured values, and a.sub.0 is a constant.

(27) Also, R.sub.X is the impedance before the correction, V.sub.in is the receiving voltage of the thyristor, and V is the output voltage of the thyristor.

(28) The roll temperature calculation data storage part 63 stores pieces of roll temperature calculation data necessary to calculate the temperature of a heat generating part (inner surface temperature) of the roll main body 2. Specifically, the pieces of roll temperature calculation data include (a) magnetic flux density-excitation resistance relationship data indicating the relationship between the magnetic flux density and the excitation resistance of the magnetic circuit in the induction heated roll (see FIG. 7), (b) magnetic flux density-relative permeability relationship data indicating the relationship between magnetic flux density and relative permeability measured for each material (see FIG. 5), and other data.

(29) The roll temperature calculation part 64 calculates the inner surface temperature of the roll main body 2 using the corrected impedance resulting from the correction by the impedance correction part 62 and the pieces of roll temperature calculation data stored in the roll temperature calculation data storage part 63 ((4) in FIG. 3).

(30) Specifically, the roll temperature calculation part 64 calculates the inner surface temperature S of the roll main body 2 using the following expression.

(31) $S = .Math. ({2 {5.03}^{2} R_{2} 1_{S} + {()}^{2} s f} - [{2 {5.03}^{2} R_{2} 1_{S} + {()}^{2} s f}^{2} - 4 {5.03}^{4} {(R_{2} 1_{S})}^{2}]) / {2 {(5.03)}^{2}} - 14.3 .Math. / (2.86 10^{- 2}) [C]$

(32) When doing this, the roll temperature calculation part 64 calculates R.sub.2 in the above expression for the inner surface temperature .sub.S using the following expressions.
r.sub.2=r.sub.0(r.sub.1r.sub.comb)/(r.sub.combr.sub.1r.sub.0)
R.sub.2=(r.sub.2/N.sup.2)10.sup.6

(33) Here, the combined resistance r.sub.comb is given by r.sub.comb=(V/I)cos , and therefore the inner surface temperature .sub.S can be calculated from the AC voltage value obtained by the AC voltage detecting part 8, AC current value obtained by the AC current detecting part 7, the power factor obtained by the power factor detecting part 10, the winding resistance value obtained by the resistance detecting part or the winding resistance value obtained from the winding temperature obtained by the temperature detecting part 9, and the excitation resistance value obtained from the characteristics of the relationship between the magnetic flux density and the excitation resistance of the magnetic circuit.

(34) The excitation resistance r.sub.0 can be obtained from the magnetic flux density-excitation resistance relationship data indicating the relationship between the magnetic flux density Bm and the excitation resistance r.sub.0 of the magnetic circuit in the induction heated roll 200 illustrated in FIG. 7. Specifically, the magnetic density Bm of the roll main body 2 is calculated using the following expression, and from the obtained magnetic flux density Bm and the magnetic flux density-excitation resistance relationship data, the excitation resistance r.sub.0 is obtained.
Bm=Vm10.sup.8/(4.44fNSm)[G]

(35) Here, Vm is a voltage value [V] obtained by a vector calculation in which voltage drops caused by the reactance l.sub.1 of the winding 32 and the resistance r.sub.1 of the winding 32 are subtracted from the input AC voltage V. f is a frequency [Hz], N is the number of turns of the winding 32, and Sm is the magnetic path cross-sectional area [cm.sup.2] of the iron core.

(36) The resistance r.sub.1 of the winding 32 is determined by the material, length, and cross-sectional area of a wire forming the winding 32, and the temperature of the winding, and, for example, in the case where the material of the wire is copper, can be calculated using the following expressions.
r.sub.1=kL/100Sc[]
k=2.1(234.5+.sub.c)/309.5

(37) Here, L is the length [m] of the wire, Sc is the cross-sectional area [mm.sup.2] of the wire, and .sub.c is the winding temperature [ C.].

(38) By obtaining the combined resistance r.sub.comb, excitation resistance r.sub.0, and winding resistance r.sub.1 using the expressions described above, the resistance r.sub.2 of the roll main body 2 can be calculated, and R.sub.2, which is the secondary side conversion resistance as viewed from the roll main body side and has a unit of , can be further calculated.

(39) Also, the roll temperature calculation part 64 obtains relative permeability s from the relative permeability-magnetic flux density relationship data indicating the relationship between the relative permeability and the magnetic flux density illustrated in FIG. 5, and the magnetic flux density of the roll main body 2 (value determined by specifications).

(40) Further, the roll temperature calculation part 64 substitutes the resistance R.sub.2 of the roll main body 2 and the relative permeability s obtained as described above into the expression above to calculate the inner surface temperature .sub.S of the roll main body 2.

(41) Specifically, given that the temperature difference between the inner surface temperature .sub.S and surface temperature (outer surface temperature) of the roll main body 2 is [ C.], the roll temperature calculation part 64 corrects the inner surface temperature .sub.S to calculate the surface temperature using the temperature difference obtained from the following expression ((5) in FIG. 3).
=kP/[2/{ ln(d.sub.2/d.sub.1)/}]

(42) Here, d.sub.1 is the inside diameter [m] of the roll main body 2, d.sub.2 is the outside diameter [m] of the roll main body 2, is the thermal conductivity [W/m.Math. C.] of the roll main body 2 at average temperature, and P is a thermal flow rate [W/m], which has here a value obtained by dividing a calorific value [W] of the inner surface of the roll main body 2 by a calorific inner surface length [m] (equal to the winding width). Also, k is a correction factor calculated from actual measured values. In addition, to obtain the thermal flow rate [W/m], the roll temperature calculation part 64 uses an electric power value obtained by calculation from the respective measured values by the current detecting part 7, voltage detecting part 8, and power factor detecting part 10. That is, given that electric power of the induction heated roll is P, P=IVcos , and a value obtained by subtracting coil electric power P.sub.C and iron loss P.sub.f from the roll electric power P is electric power P.sub.S of the roll main body.

(43) Here, the coil electric power P.sub.C is given by P.sub.C=r.sub.1(kI).sup.2 (k is an augmentation factor corresponding to eddy current generated in the wire, and has a value determined by the shapes of the winding and the wire. In the case of an examined roll, k=1.2), and the iron loss P.sub.f is given by P.sub.f={(Vm/r.sub.0).sup.2}r.sub.0/2=Vm.sup.2/(2r.sub.0). In the calculation of the iron loss P.sub.f, the square of the excitation current is multiplied by the excitation resistance, which is then multiplied by because the calculation is performed considering iron loss in the iron core of the magnetic flux generating mechanism and iron loss in the roll main body fifty-fifty.

(44) That is, the electric power P.sub.S of the roll main body is given by the following expression.
P.sub.S=PP.sub.CP.sub.f=IVcos r.sub.1(kI).sup.2Vm.sup.2/(2r.sub.0)

(45) In addition, the roll temperature calculation part 64 calculates the outer surface temperature of the roll main body 2 in consideration of a reduction in thickness due to the jacket chambers 2S formed in the roll main body 2.

(46) Specifically, on the assumption that the inside diameter d.sub.1 of the roll main body 2 is substituted by a virtual inside diameter d.sub.j1 (=d.sub.1+t{1(1S.sub.j/S)}) taking into account the reduction in thickness, and the outside diameter d.sub.2 of the roll main body 2 is substituted by a virtual outside diameter d.sub.j2 (=d.sub.2t{1(1S.sub.j/S)}) taking into account the reduction in thickness, where S is the cross-sectional area of the roll main body 2, S.sub.j is the sum of cross-sectional areas of the jacket chambers 2S, and t is the thickness of the roll main body 2, the roll temperature calculation part 6 calculates the outer surface temperature of the roll main body 2 using the temperature difference obtained from the above expression for the temperature difference .

(47) On the basis of the outer surface temperature of the roll main body 2 obtained by the roll temperature calculation part 64 in the above manner, the roll temperature control part 65 controls the control element 4 of the power supply circuit so as to make the outer surface temperature of the roll main body 2 equal to a predetermined setting temperature.

(48) The induction heated roll apparatus 100 of the present embodiment configured as described has the roll temperature calculation part 64 that calculates the temperature of the roll main body 2 using the value of the AC current flowing through the winding 32, the value of the AC voltage applied to the winding 32, the power factor of the induction heated roll 200, the winding resistance value of the winding 32, and the excitation resistance value of the magnetic circuit configured to include the iron core 31 and the roll main body 2 as parameters, and can therefore calculate the temperature of the roll main body 2 without providing the roll main body 2 with a temperature detecting element.

(49) Also, since the impedance obtained by the impedance calculation part 61 is corrected by the impedance correction part 62 using the conduction angle of the thyristor 4, the temperature of the roll main body 2 can be accurately calculated.

(50) Further, since the roll temperature calculation part 64 calculates the surface temperature using the temperature difference between the inner surface temperature and the surface temperature of the roll main body 2, the surface temperature of the roll main body 2 can be accurately calculated. Also, a time lag in reaching temperature during a transient period such as a temperature rise or fall period is also calculated and corrected by the roll temperature calculation part 64, and therefore the surface temperature of the roll main body 2 can be accurately calculated.

(51) Note that the present invention is not limited to the above-described embodiment.

(52) For example, the induction heated roll of the above-described embodiment may be a so-called double-sided support induction heated roll in which both end parts of a roll main body in an axial direction are rotatably supported, or a so-called single-sided support induction heated roll in which the bottom part of a bottom-equipped tubular roll main body is connected with a rotary shaft and rotatably supported.

(53) Further, the above-described embodiment is configured such that the temperature detecting part 9 adapted to detect the temperature of the winding 32 is embedded in the winding 32; however, the present invention may be configured as follows.

(54) That is, as illustrated in FIGS. 10 and 11, the control device 6 may be configured to perform a temperature detecting operation that periodically detects the temperature of the winding 32 during heating operation for inductively heating the roll main body 2 to treat a heated object. More specifically, the control device 6 fulfills functions as a DC voltage application part 66 and a resistance value calculation part 67.

(55) The DC voltage application part 66 is one that controls a DC power supply 12 electrically connected to the winding 32 to intermittently apply DC voltage to the winding 32. Specifically, the DC voltage application part 66 is one that applies a constant DC voltage to the winding 32 for an application time of several seconds or less with a regular period of several seconds to several tens of minutes.

(56) Note that within the application time for which the DC voltage application part 66 applies the DC voltage to the winding 32, the roll temperature control part 65 of the control device 6 controls the control element 4 to interrupt or minimize the AC current or the AC voltage. In other words, the roll temperature control part 65 is one that, in order to make the temperature of the roll main body 2 equal to a predetermined setting temperature, controls the control element 4 provided for the power supply circuit 5 to control the AC voltage or the AC current.

(57) The resistance value calculation part 67 is one that calculates the winding resistance value of the winding 32 from the DC voltage applied by the DC voltage application part 66 and DC current flowing through the winding when applying the DC voltage to the winding 32. Specifically, the resistance value calculation part 67 calculates the winding resistance value of the winding 32 from the DC voltage preliminarily inputted from the DC power supply 12 and the DC current obtained by a DC current detecting part 13 provided in a DC circuit configured to include the winding 32 and the DC power supply 12.

(58) As described above, since at the time of applying the DC voltage to detect the DC current, the AC current or the AC voltage is interrupted or minimized, the effect of the AC current (AC component) can be suppressed to easily detect the DC current (DC component), and therefore the resistance value can be accurately calculated.

(59) Needless to say, the present invention is not limited to any of the above-described embodiments, but can be variously modified without departing from the scope thereof. Also, needless to say, in the case where an error occurs between an actual measured value and a calculated value in each calculation step, a correction factor calculated from actual measured values is used to make a correction.

REFERENCE CHARACTER LIST

(60) 100: Induction heated roll apparatus 200: Induction heated roll 2: Roll main body 2S: Jacket chamber 3: Magnetic flux generating mechanism 32: Winding 4: Control element 5: Power supply circuit 6: Control device 61: Impedance calculation part 62: Impedance correction part 63: Roll temperature calculation data storage part 64: Roll temperature calculation part 7: Current detecting part 8: Voltage detecting part 9: Temperature detecting part 10: Power factor detecting part

Induction heated roll apparatus

Assignee

Inventors

Cpc classification

Classification Explorer

Y02P70/10

GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

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H05B6/36

ELECTRICITY

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D21G1/028

TEXTILES; PAPER

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H05B6/145

ELECTRICITY

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H05B6/06

ELECTRICITY

International classification

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H05B6/14

ELECTRICITY

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D21G1/02

TEXTILES; PAPER

Classification Explorer

H05B6/36

ELECTRICITY

Classification Explorer

H05B6/06

ELECTRICITY

Abstract

Claims

Description