Induction-heated roller apparatus

Abstract

The present invention intends to eliminate the need for a temperature detecting element adapted to measure the temperature of a roll main body in an induction-heated roller apparatus, and includes an impedance calculation part that calculates the impedance of a winding, a relational data storage part that stores relational data indicating the relationship between the impedance of the winding and the temperature of the roll main body, and a roll temperature calculation part that calculates the temperature of the roll main body from the impedance obtained by the impedance calculation part and the relational data stored in the relational data storage part.

Claims

1. An induction-heated roller 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; a power supply circuit that is connected to the winding of the magnetic flux generating mechanism and provided with a control element configured to control AC current or AC voltage; and a control device operatively coupled to: an AC current detector configured to detect AC current flowing through the winding of the magnetic flux generating mechanism to obtain an AC current value, an AC voltage detector configured to detect AC voltage applied to the winding to obtain an AC voltage value, a power factor detector configured to detect a power factor of the roll main body and the magnetic flux generating mechanism, a power supply voltage detector configured to detect power supply voltage of the power supply circuit, and a power detector configured to detect a power capacity of the roll main body, wherein the control device comprises: a relational data storage storing relational data indicating a relationship between an impedance of the winding and an inner surface temperature of the roll main body, and a processor executing an impedance calculation part, a roll temperature calculation part, and an impedance correction part, wherein the impedance calculation part calculates impedance of the winding from the AC current value obtained by the AC current detector and the AC voltage value obtained by the AC voltage detector; the roll temperature calculation part calculates the inner surface temperature of the roll main body from the impedance obtained by the impedance calculation part and the relational data stored in the relational data storage; given that a temperature difference between the inner surface temperature and an outer surface temperature of the roll main body is , the roll temperature calculation part corrects the inner surface temperature of the roll main body and calculates the outer surface 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 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 calculated based on the power factor detected by the power factor detector and the power capacity detected by the power detector); and the impedance correction part, based on a power supply voltage value obtained by the power supply voltage detector configured to detect power supply voltage of the power supply circuit, corrects the impedance obtained by the impedance calculation part; wherein the roll temperature calculation part calculates the inner surface temperature of the roll main body from corrected impedance and the relational data, without providing the roll main body with a temperature detecting element, the corrected impedance resulting from the correction by the impedance correction part.

2. The induction-heated roller apparatus according to claim 1, 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 in function of the jacket chambers is , the reduction being caused by a reduction in pressure of the heating medium along with a reduction in temperature, and the roll temperature calculation part calculates the outer surface 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)}.

3. The induction-heated roller apparatus according to claim 1, wherein the control element controls a conduction angle of current or voltage with a semiconductor; the impedance correction part, further based on the conduction angle controlled by the control element, corrects the impedance obtained by the impedance calculation part.

4. The induction-heated roller apparatus according to claim 1, wherein based on a winding temperature obtained by a temperature detector configured to detect the temperature of the winding, the impedance correction part corrects the impedance obtained by the impedance calculation part.

5. The induction-heated roller apparatus according to claim 1, wherein the processor further executes a DC voltage application part that controls a DC power supply to intermittently apply DC voltage to the winding; the processor further executes a resistance value calculation part that calculates a winding resistance value from the DC voltage applied by the DC voltage application part and DC current flowing through the winding when the DC voltage is applied; and based on the winding resistance value obtained by the resistance value calculation part, the impedance correction part corrects the impedance obtained by the impedance calculation part.

6. The induction-heated roller apparatus according to claim 1, wherein the roll temperature calculation part corrects the outer surface temperature of the roll main body with use of: power factor relational data indicating a relationship between the power factor of the induction-heated roller and a power factor of a reference induction-heated roller.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a diagram schematically illustrating a configuration of an induction-heated roller 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 characteristics graph illustrating the relationship between temperature and thermal conductivity of carbon steel (S45C);

(5) FIG. 5 is a diagram illustrating an equivalent circuit of a single-phase induction-heated roller (single-phase roller);

(6) FIG. 6 is a characteristics graph illustrating the relationship between the surface temperature of a roll main body and AC voltage/AC current;

(7) FIG. 7 is a characteristics graph illustrating the relationship between the magnetic flux density and relative permeability of carbon steel (S45C); and

(8) FIG. 8 is a characteristics graph illustrating the relationship between the magnetic flux density and exciting resistance of a magnetic circuit configured to include a roll main body made of carbon steel (S45C) and an iron core made of a grain-oriented silicon steel sheet.

DESCRIPTION OF EMBODIMENTS

(9) In the following, one embodiment of an induction-heated roller apparatus according to the present invention is described with reference to the drawings.

(10) As illustrated in FIG. 1, an induction-heated roller 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 also provided with a control element 4 adapted to control current or voltage.

(11) Inside the lateral circumferential wall of the roll main body 2, multiple jacket chambers 2S in which a gas-liquid two-phase heating medium is included are formed at regular intervals in a circumferential direction. In addition, 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, a thyristor.

(12) Further, a control device 6 adapted to control the induction-heated roller apparatus 100 of the present embodiment has a surface temperature calculating function that calculates the surface temperature of the roll main body 2 from the impedance of the winding 32.

(13) 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 relational data storage part 63, a roll temperature calculation part 64, and the like.

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

(15) The impedance calculation part 61 calculates the impedance Z.sub.1 (=V/I) of the winding 32 from an AC current value obtained by an AC current detecting part 7 adapted to detect AC current I flowing through the winding 32 and an AC voltage value obtained by an AC voltage detecting part 8 adapted to detect AC voltage V applied to the winding 32 ((1) in FIG. 3).

(16) The impedance correction part 62 corrects the impedance Z.sub.1, which is obtained by the impedance calculation part 61, on the basis of the difference between a power supply voltage at which relational data was prepared at the time of production shipment and a power supply voltage used by a user (the difference in power supply voltage between the two) ((2) in FIG. 3).

(17) Also, the impedance correction part 62 corrects the impedance Z.sub.1 on the basis of the conduction angle (phase angle) of the control element (thyristor) 4 ((3) in FIG. 3).

(18) Specifically, the impedance correction part 62 corrects the impedance Z.sub.1 according to the following expression:
Z.sub.2=aZ.sub.1
Here, given 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.

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

(20) Also, Z.sub.1 is the impedance before the correction, V.sub.in the receiving voltage of the thyristor, and V the output voltage of the thyristor.

(21) Further, in the case where the power supply voltage suddenly changes when the induction-heated roller apparatus 100 is in operation, the magnetic flux density of a magnetic circuit also suddenly changes to change the current penetration depth of the roll main body. As a result, the impedance changes; however, a change in temperature of the roll main body requires a considerable time lag. For this reason, the impedance correction part 62 in the present embodiment corrects Z.sub.2, which resulted from the correction based on the conduction angle, on the basis of a power supply voltage value E obtained by a power supply voltage detecting part 9 adapted to detect the power supply voltage of the power supply circuit 5 ((4) in FIG. 3).

(22) Specifically, the impedance correction part 62 corrects the impedance Z.sub.2 according to the following expression:
Z.sub.3={1a(EV.sub.in).sup.b}Z.sub.2

(23) Here, E is the rated power supply voltage, V.sub.in the control element input voltage, Z.sub.2 the impedance before the correction, and a and b roll-based constants. This correction is continually made at separated time intervals.

(24) Still further, the impedance correction part 62 corrects the impedance Z.sub.3, which resulted from the correction based on the conduction angle and the power supply voltage E, on the basis of winding temperature .sub.c [ C.] obtained by a temperature detecting part 10 adapted to detect the temperature of the winding 32 ((5) in FIG. 3). In addition, the temperature detecting part 10 is embedded in the winding 32.

(25) Specifically, the impedance correction part 62 calculates the resistance r.sub.1 of the winding 32 to correct the impedance Z.sub.3 according to the following expressions.
r.sub.1=kL/100S[]
k=2.1(234.5+.sub.c)/309.5

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

(27) The relational data storage part 63 stores relational data indicating the relationship between the impedance of the winding 32 and the temperature of the roll main body 2 (V/I- characteristics approximate expression). Specifically, the relational data is data indicating the relationship between the impedance of the winding 32 and the inner surface temperature of the roll main body 2. Also, the impedance of the winding 32 was obtained by, as described above, when preliminarily obtaining the relational data, correcting the impedance, which was obtained on the basis of the AC current value obtained by the current detecting part 7 and the AC voltage value obtained by the voltage detecting part 8, on the basis of the conduction angle, power supply voltage, and winding temperature ((1) to (5) in FIG. 3). In addition, the relational data was obtained using a reference induction-heated roller apparatus. Further, the relational data storage part 63 may be set in a predetermined area of the internal memory, or set in a predetermined area of an external memory attached outside the control device 6.

(28) The roll temperature calculation part 64 calculates the inner surface temperature of the roll main body 2 with use of: the corrected impedance resulting from the correction by the impedance correction part 62; and the relational data stored in the relational data storage part 63 ((6) in FIG. 3).

(29) Specifically, given that the temperature difference between the inner surface temperature and surface temperature (outer surface temperature) of the roll main body 2 is [ C.], the roll temperature calculation part 64 calculates an accurate surface temperature by correcting the inner surface temperature using the temperature difference obtained from the following expression ((7) in FIG. 3).
=kP/[2/{ln(d.sub.2/d.sub.1)/}]

(30) Here, d.sub.1 is the inside diameter [m] of the roll main body, d.sub.2 the outside diameter [m] of the roll main body, the thermal conductivity [W/m.Math. C.] of the roll main body at an average temperature, and P 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 by a calorific inner surface length [m] (equal to a 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 a power detecting part 11.

(31) Further, the roll temperature calculation part 64 calculates the outer surface temperature of the roll main body 2 while taking into account a reduction in thickness due to the jacket chambers 2S formed in the roll main body 2.

(32) 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 the sum of cross-sectional areas of the jacket chambers 2S, and t the thickness of the roll main body 2, the roll temperature calculation part 64 calculates the outer surface temperature of the roll main body 2 using the temperature difference obtained from the above expression for the temperature difference .

(33) Further, the roll temperature calculation part 64 corrects an instrumental error of an induction-heated roller as a temperature detection target (detection target roller) with respect to an induction-heated roller as a reference (reference roller). Specifically, the roll temperature calculation part 64 corrects the outer surface temperature of the roll main body 2 using power factor relational data indicating the relationship between a power factor cos .sub.x obtained by a power factor detecting part 12 adapted to detect the power factor of the detection target roller and a power factor cos .sub.r of the reference roller ((8) in FIG. 3).

(34) More specifically, given that a temperature rise value of the reference roller (the difference between the temperature of the roll main body and an ambient temperature) is .sub.r [ C.], the ambient temperature in a V/I-0 characteristics approximate expression for the reference roller is .sub.a [ C.], a temperature rise value of the detection target roller is .sub.x [ C.], the power factor of the reference roller is cos .sub.r, and the power factor of the detection target roller is cos .sub.x, the roll temperature calculation part 64 calculates the surface temperature of the roll main body of the detection target roller using .sub.x [ C.] obtained by the following expression.

(35) $\begin{array}{c}{}_x={}_x+{}_a\\ =\left\{\left(\cos {}_x-\cos {}_r\right)\text{/}\cos {}_r\left(1-\cos {}_x\right)+1\right\}{}_r+{}_a\end{array}$

(36) The induction-heated roller 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 from the impedance obtained by the impedance calculation part 61 and the relational data indicating the relationship between the impedance of the winding 32 and the temperature of the roll main body 2, and can therefore calculate the temperature of the roll main body 2 by calculating the impedance of the winding 32 without providing the roll main body 2 with a temperature detecting element.

(37) Also, 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 power supply voltage E of the power supply circuit 5, and the temperature of the winding 32, and consequently the temperature of the roll main body 2 can be calculated with accuracy.

(38) Further, the roll temperature calculation part 64 calculates the surface temperature on the basis of the temperature difference between the inner surface temperature and surface temperature of the roll main body 2, as well as correcting the instrumental error of the induction-heated roller device as a temperature detecting target with respect to the reference roller, and can therefore calculate the surface temperature of the roll main body 2 with accuracy.

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

(40) For example, the above-described embodiment is configured such that the impedance correction part uses the temperature of the winding 32 to correct the impedance; however, the present invention may be configured such that the roll temperature calculation part 64 uses the temperature of the winding 32 to correct the temperature of the roll main body calculated from the impedance and the relational data. In this case, a correction value t is given by, for example, m.sub.c+n (where m and n are factors calculated from actual measured values).

(41) Also, the above-described embodiment is adapted to, with reference to the approximate expression representing the predetermined relationship between the inner surface temperature of the roll main body and the impedance, correct the approximate expression to obtain the surface temperature of the roll main body. However, the present invention may be adapted to, with reference to an approximate expression representing the predetermined relationship between the surface temperature of the roll main body or the temperature inside the lateral wall of the roll main body and the impedance, on the basis of the effect of various conditions for the induction-heated roller apparatus and a variation in each of the conditions on the surface temperature, correct the approximate expression to obtain the surface temperature of the roll main body. For example, to obtain the approximate expression representing the predetermined relationship between the surface temperature of the roll main body and the impedance, it is possible to externally measure the surface temperature of the roll main body using a radiation pyrometer. Also, to correct the approximate expression, the same corrections as those in (2) to (4) and (8) in FIG. 3 in the embodiment may be made.

(42) Further, the induction-heated roller of the above-described embodiment may be a so-called double-sided support induction-heated roller 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 roller in which the tubular roll main body is connected to a rotary shaft and is supported on one end of the roll only, while the unsupported end of the roll is capped.

(43) 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 SIGNS LIST

(44) 100: Induction-heated roller device 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: Relational data storage part 64: Roll temperature calculation part 7: AC current detecting part 8: AC voltage detecting part 9: Power supply voltage detecting part 10: Temperature detecting part 11: Power detecting part 12: Power factor detecting part