Induction heated roll apparatus

Abstract

The present invention is one that intends to reduce the number of working processes necessary to provide a secondary conductor on the inner circumferential surface of a roll main body, and an induction heated roll apparatus including: a roll main body that is rotatably supported; and an induction heating mechanism that is provided inside the roll main body and has an induction coil for allowing the roll main body to inductively generate heat. In addition, on the inner circumferential surface of the roll main body, the secondary conductor is formed by build-up welding.

Claims

1. An induction heated roll apparatus comprising: a roll main body that is rotatably supported; and an induction heating mechanism that is provided inside the roll main body and has an induction coil for allowing the roll main body to inductively generate heat, and allowing the roll main body to inductively generate heat by applying alternating current (AC) voltage having a commercial frequency to the induction coil, wherein on an inner circumferential surface of the roll main body, a secondary conductor is formed by build-up welding, the secondary conductor is made of copper or copper alloy, a surface of the secondary conductor is not subjected to a planarization process using removal machining, and within a thickness of the roll main body, a jacket chamber in which a vapor-liquid two-phase heating medium enclosed via decompression sealing is formed, so as to adjust an uneven surface temperature of the roll main body caused by the secondary conductor; wherein the secondary conductor is one of a cylindrical shape that is continuously formed from a first end part to a second end part of the roll main body in an axis direction; wherein the surface of the secondary conductor is subjected to a rust-proofing process; wherein an electrical characteristic of the induction heated roll apparatus is adjusted by a weight of the secondary conductor.

2. The induction heated roll apparatus according to claim 1, wherein a thickness of the secondary conductor changes along an axis direction of the roll main body.

3. The induction heated roll apparatus according to claim 1, wherein the secondary conductor is annularly formed, spaced at intervals on the inner circumferential surface of the roll main body.

4. The induction heated roll apparatus according to claim 1, wherein the secondary conductor is spirally formed, spaced at intervals on the inner circumferential surface of the roll main body.

Description

BRIEF DESCRIPTION OF DRAWINGS

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

(2) FIG. 2 is a cross-sectional view schematically illustrating a formation pattern of a secondary conductor according to the same embodiment;

(3) FIG. 3 is a schematic diagram illustrating a method for forming the secondary conductor according to the same embodiment;

(4) FIG. 4 is an equivalent electrical circuit diagram of the induction heated roll apparatus;

(5) FIG. 5 is a diagram illustrating the relationship between an increase in the amount of oxide and elapsed time at each content percentage of aluminum in aluminum bronze;

(6) FIG. 6 is a diagram illustrating the relationship between an increase in the amount of oxide and temperature at each content percentage of aluminum in aluminum bronze;

(7) FIG. 7 is a cross-sectional view schematically illustrating a formation pattern of a secondary conductor according to a variation; and

(8) FIG. 8 is a cross-sectional view schematically illustrating a formation pattern of a secondary conductor according to another variation.

DESCRIPTION OF EMBODIMENTS

(9) In the following, one embodiment of the induction heated roll apparatus according to the present invention will be described with reference to the drawings.

(10) An induction heated roll apparatus 100 according to the present invention is one used in some processes such as a continuous heat treatment process for continuous materials such as a sheet material, web material, or wire (thread) material formed of, for example, plastic film, paper, cloth, nonwoven fabric, synthetic fiber, or metal foil.

1. Apparatus Configuration

(11) Specifically, as illustrated in FIG. 1, this apparatus includes a rotatably supported and hollow cylindrical roll main body 2, and an induction heating mechanism 3 provided inside the roll main body 2.

(12) At both end parts of the roll main body 2, hollow drive shafts 21 are provided, and the drive shafts 21 are rotatably supported by a machine base 9 via bearings 8 such as rolling bearings. In addition, the drive shafts 21 respectively have flanges 211 connected to the axial direction end surfaces of the roll main body 2 (see FIG. 2). The roll main body 2 including the drive shafts 21 is formed of a magnetic material such as carbon steel. Further, the roll main body 2 is configured to be rotated by a drive force externally given by a rotary drive mechanism (not illustrated) such as a motor. Also, in a side circumferential wall 201 as a thick wall part of the roll main body 2 in the present embodiment, jacket chambers 2A in which a vapor-liquid two-phase heating medium is enclosed under reduced pressure are formed. In the side circumferential wall 201, the multiple jacket chambers 2A extend in a longer direction (in a rotation axis direction) and are formed at regular intervals in a circumferential direction.

(13) The induction heating mechanism 3 includes a cylindrical iron core 31 formed in a cylindrical shape and an induction coil 32 wound on the outer circumferential surface of the cylindrical iron core 31.

(14) At both end parts of the cylindrical iron core 31, support shafts 33 are provided, and the support shafts 33 are respectively inserted into the drive shafts 21, and rotatably supported by the drive shafts 21 via bearings 10 such as rolling bearings. In doing so, the induction heating mechanism 3 is held in a resting state with respect to the machine base 9 (fixation side) inside the roll main body 2 being rotating.

(15) Also, the induction coil 32 is connected with an external lead L1, and the external lead L1 is connected with a power supply device 5 for applying AC voltage having a commercial frequency (50 Hz or 60 Hz). The power supply device 5 includes a power supply part 51 that supplies AC power to the induction heating mechanism 3 and a temperature control part 52 that controls the power supply part 51 to control the temperature of the roll main body 2. The temperature control part 52 is a dedicated or general-purpose computer having a processor (e.g., a central processing unit (CPU)), internal memory, input/output interfaces, an analog-to-digital (AD) converter, and the like, and on the basis of a set temperature signal inputted by a user, controls the power supply part 51 to control the surface temperature of the roll main body 2 so that the surface temperature becomes equal to a set temperature. In addition, the temperature control part 52 may be configured to include an analog circuit.

(16) In such an induction heating mechanism 3, when the AC voltage is applied to the induction coil 32, alternating magnetic flux is generated, and the alternating magnetic flux passes through the side circumferential wall 201 of the roll main body 2. This passage causes an induction current in the roll main body 2, and the induction current allows the roll main body 2 to generate Joule heat. Also, the jacket chambers 2A equalize the temperature distribution of the side circumferential wall 201 of the roll main body 2 in the rotation axis direction.

(17) In addition, on the inner circumferential surface of the roll main body 2 in the present embodiment, a secondary conductor 4 is formed by build-up welding. The material (build-up material) of the secondary conductor 4 is aluminum bronze (an alloy of aluminum and copper). The aluminum bronze in the present embodiment is one containing 6% or more of aluminum.

(18) Specifically, the secondary conductor 4 is formed on an inner circumferential surface 201a of the roll main body 2 over the entire circumferential direction, and also continuously formed along the rotation axis direction of the roll main body 2.

(19) Here, the secondary conductor 4 is spirally formed, and continuously formed with mutually adjacent welded parts being in contact with each other. That is, the secondary conductor 4 is continuously formed over the entire winding width of the induction coil 32 in the rotation axis direction of the roll main body 2. In other words, the secondary conductor 4 is of a cylindrical shape that is formed along the rotation axis direction of the roll main body 2. Also, on the surface of the secondary conductor 4 made of aluminum bronze configured as described above, a protective oxide coating film is formed. The protective oxide coating film allows the secondary conductor 4 to have a rust-proofing function.

(20) Next, an example of build-up welding work for forming the secondary conductor 4 on the inner circumferential surface 201a of the roll main body 2 will be described with reference to FIG. 3.

(21) The roll main body 2 is fitted to rotating equipment 11 for rotating the roll main body 2. By inserting a welding torch 12 into the roll main body 2 in this state, and while rotating the roll main body 2 by the rotating equipment 11, relatively moving the welding torch 12 in the rotation axis direction with respect to the roll main body 2, the spiral secondary conductor 4 is formed on the inner circumferential surface 201a of the roll main body 2. In this build-up welding, by appropriately setting pre-welding process conditions such as pre-heating of the roll main body 2, welding conditions such as the size and material of a welding wire, torch angle, torch position, voltage, current, rotation speed of the roll main body 2, and moving speed (drawing pitch) of the welding torch 12, and post-welding process conditions such as post-heating of the roll main body 2, various secondary conductors 4 can be formed.

(22) Since on the surface of the secondary conductor 4 formed in this manner, the protective oxide film is formed, it is not necessary to perform a plating process for rust prevention, and therefore in the present embodiment, the plating process is not performed.

(23) Also, since the jacket chambers 2A are formed in the side circumferential wall 201 of the roll main body 2, even when uneven heat generation occurs due to the uneven thickness of the aluminum bronze, the surface temperature of the roll main body 2 is adjusted to an equalized temperature by the temperature equalizing action of the jacket chambers 2A. For this reason, in the present embodiment, machining for equalizing the thickness of the secondary conductor 4 is not necessary. That is, a planarization process using removal machining for removing convex parts is not performed on the surface of the secondary conductor 4.

(24) In the induction heated roll apparatus 100, a settable temperature by the temperature control part 52 is 500° C. or less. That is, the induction heated roll apparatus 100 is configured so that a user cannot set a temperature higher than 500° C. This is because, in the case of aluminum bronze containing 6% or more of aluminum, oxidation at 500° C. or less is extremely slight, but at temperatures higher than 500° C., an increase in weight due to oxidation becomes problematic.

(25) Next, the results of a power factor test on the induction heated roll apparatus 100 will be described. The roll main body 2 used in this test has a diameter of 237 mm, a face length of 400 mm, and a thickness of 22 mm. Also, 30 jacket chambers 2A each having a diameter of 10 mm and a length of 380 mm are arranged in the center of the thickness 22 mm of the roll main body 2 at regular intervals. The width of the secondary conductor 4 in the axis direction is 380 mm. Electrical specifications are that an input is single-phase, 60 Hz, 220 V, and capacity with no secondary conductor is 5 kW.

(26) Table 1 below lists power factors respectively in the cases of no build-up, copper build-up welding (build-up thickness of 0.5 mm, 1.0 mm, 1.5 mm) and 8%-aluminum-containing aluminum bronze build-up welding (build-up thickness of 1.5 mm, 3.0 mm). In addition, the build-up thickness (mm) indicates an average value in the axis direction.

(27) TABLE-US-00001 TABLE 1 Build-up thickness Power factor Build-up metal type (mm) (%) None 0 70.2 Copper 0.5 87.4 Copper 1.0 89.7 Copper 1.5 91.2 Aluminum bronze containing 8% of 1.5 83.5 aluminum Aluminum bronze containing 8% of 3.0 88.4 aluminum

(28) As can be seen from Table 1, by performing build-up welding of aluminum bronze to form the secondary conductor 4 and adjusting the build-up thickness of aluminum bronze containing 8% of aluminum to 1.5 mm or more, as compared with the case of no build-up welding, the power factor is improved, and achieves a target power factor (80%) or more. Also, it is conceivable that even in the case of aluminum bronze containing 6% of aluminum, the same effects can be obtained. Further, the build-up thickness leading to the target power factor (80%) or more can be calculated using an equivalent circuit diagram in the induction heating at a commercial frequency.

2. Effects of Present Embodiment

(29) In the induction heated roll apparatus 100 configured as described above, since the secondary conductor 4 is formed by build-up welding, a tube body forming process and a tube body fitting process in the conventional case can be omitted. Also, a thin protective oxide coating film is formed on the surface of aluminum bronze, and therefore aluminum bronze is characterized by preventing oxidation at high temperatures and consequently resistant to corrosion. Also, by using aluminum bronze for the secondary conductor 4, a rust-proofing process such as a plating process can be omitted. As a result, the number of working processes necessary to provide the secondary conductor 4 on the inner circumferential surface 201a of the roll main body 2 can be reduced. Further, build-up welding is only required, and therefore work to fit the secondary conductor 4 on the inner circumferential surface of the roll main body 2 can be facilitated. Still further, since the secondary conductor 4 is formed by build-up welding, the roll main body 2 and the secondary conductor 4 are integrated and therefore also applicable to high speed rotation, and there is no loosening due to the difference in thermal expansion coefficient between the roll main body 2 and the secondary conductor 4, thus making it possible to also suppress a reduction in thermal conductivity between the roll main body 2 and the secondary conductor 4.

3. Variations of Present Invention

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

(31) The material of the secondary conductor in the above-described embodiment may be copper or copper alloy. The copper alloy may be, for example, a non-magnetic copper alloy having high corrosion resistance, and it is conceivable to use aluminum bronze (an alloy of aluminum and copper), white copper (cupronickel, an alloy of copper and nickel), German silver (nickel silver; an alloy of copper, zinc, and nickel), red copper (an alloy of copper and gold), gunmetal (an alloy of copper and tin), or a combination thereof. Also, the surface of the secondary conductor 4 is subjected to a rust-proofing process. As the rust-proofing process, for example, a plating process such as nickel plating, an evaporation process such as aluminum evaporation or the like is conceivable. The rust-proofing process is performed after the secondary conductor 4 has been formed in the same manner as that in the above-described embodiment.

(32) Also, as in the above-described embodiment, since the jacket chambers 2A are formed in the side circumferential wall 201 of the roll main body 2, even when uneven heat generation occurs due to the uneven thickness of the copper or copper alloy, the surface temperature of the roll main body 2 is adjusted to an equalized temperature by the temperature equalizing action of the jacket chambers 2A. For this reason, in the present embodiment, machining for equalizing the thickness of the secondary conductor 4 is not necessary. That is, a planarization process using removal machining for removing convex parts is not performed on the surface of the secondary conductor 4.

(33) Next, the results of a power factor test on the induction heated roll apparatus 100 will be described. The roll main body 2 used in this test has a diameter of 237 mm, a face length of 400 mm, and a thickness of 22 mm. Also, 30 jacket chambers 2A each having a diameter of 10 mm and a length of 380 mm are arranged in the center of the thickness 22 mm of the roll main body at regular intervals. The width of the secondary conductor 4 in the axis direction is 380 mm. The electrical specifications are that the input is single-phase, 60 Hz, 220 V, and capacity with no secondary conductor is 5 kW.

(34) Table 2 below lists power factors respectively in the cases of no build-up, and copper build-up welding (build-up thickness of 0.5 mm, 1.0 mm, 1.5 mm). In addition, the build-up thickness (mm) indicates an average value in the axis direction.

(35) TABLE-US-00002 TABLE 2 Build-up metal type Build-up thickness (mm) Power factor (%) None 0 70.2 Copper 0.5 87.4 Copper 1.0 89.7 Copper 1.5 91.2

(36) As can be seen from Table 2, by performing build-up welding of copper to form the secondary conductor 4, as compared with the case of no build-up welding, the power factor is improved, and achieves a target power factor (80%) or more. Also, the build-up thickness leading to the target power factor (80%) or more can be calculated using an equivalent circuit diagram in the induction heating at a commercial frequency.

(37) In the induction heated roll apparatus 100, a settable temperature by the temperature control part 52 is 500° C. or less. That is, the induction heated roll apparatus 100 is configured so that a user cannot set a temperature higher than 500° C. The settable temperature is determined depending on the type of the rust-proofing process to be performed on the surface of the secondary conductor 4. For example, when the rust-proofing process is nickel plating, the settable temperature is 400° C. or less, and when the rust-proofing process is aluminum evaporation, the settable temperature is 500° C. or less.

(38) Even in the induction heated roll apparatus 100 configured as described above, since the secondary conductor 4 is formed by build-up welding, the tube body forming process and the tube body fitting process in the conventional case can be omitted. As a result, the number of working processes necessary to provide the secondary conductor 4 on the inner circumferential surface 201a of the roll main body 2 can be reduced. Also, build-up welding is only required, and therefore work to fit the secondary conductor 4 on the inner circumferential surface 201a of the roll main body 2 can be facilitated. Further, since the secondary conductor 4 is formed by build-up welding, the roll main body 2 and the secondary conductor 4 are integrated and therefore also applicable to high speed rotation, and there is no loosening due to the difference in thermal expansion coefficient between the roll main body 2 and the secondary conductor 4, thus making it possible to also suppress a reduction in thermal conductivity between the roll main body 2 and the secondary conductor 4 as well.

(39) Also, as long as within the thickness of the roll main body 2, the jacket chambers 2A in which a vapor-liquid two-phase heating medium is enclosed under reduced pressure are formed, even when uneven heat generation occurs due to the uneven thickness of copper or copper alloy, the surface temperature of the roll main body 2 is adjusted to an equalized temperature by the temperature equalizing action of the jacket chambers 2A. For this reason, machining for equalizing the thickness of the secondary conductor 4 is not necessary. That is, it is not necessary to perform a planarization process using removal machining on the surface of the secondary conductor 4. As a result, the number of working processes to be performed on the secondary conductor 4 can be reduced, and also since the secondary conductor 4 is not removed, unnecessary material can be eliminated.

(40) The secondary conductor 4 may be one whose thickness is adjusted along the rotation axis direction of the roll main body 2. That is, the thickness of the secondary conductor 4 may be changed along the rotation axis direction of the roll main body 2. This configuration makes it possible to partially increase or decrease the calorific value of the roll main body 2.

(41) Also, the secondary conductor in the above-described embodiment is formed using aluminum bronze, but may be formed using white copper, German silver, red copper, gunmetal, or a combination thereof. These are non-magnetic copper alloys having high corrosion resistance, and the same effects as aluminum bronze can be obtained.

(42) Further, the secondary conductor is annularly formed on the inner circumferential surface of the roll main body. However, multiple secondary conductors may be continuously formed in the rotation axis direction of the roll main body.

(43) In addition, multiple secondary conductors may be intermittently formed in the rotation axis direction of the roll main body. For example, as illustrated in FIG. 7, secondary conductors 4 may be annularly formed at intervals on the inner circumferential surface 201a of the roll main body 2, or as illustrated in FIG. 8, may be spirally formed at intervals on the inner circumferential surface 201a of the roll main body 2. By forming secondary conductors 4 at intervals as described above, as compared with continuous formation work, formation work can be facilitated. Also, the secondary conductor 4 can be continuously formed by spiral formation as illustrated in FIG. 8.

(44) Further, the electrical characteristics of the induction heated roll apparatus can be adjusted by the weight of the secondary conductor. For example, as long as the specifications of respective roll main bodies are the same, by equalizing the weights of secondary conductors to be worked, power factors and electrical capacities are also equalized, and work management is extremely easy. The following table lists electrical characteristics when the weights of secondary conductors are equalized, from which it turns out that as long as the weights of the secondary conductors are the same, the electrical characteristics are substantially the same. In addition, in the following table, the dimensions of a roll main body are a diameter of 300 mm, an inside diameter of 280 mm, and a face length of 189 mm, and the secondary conductors are made of pure copper, and the weights thereof are approximately 800 g. Although the following table provides a list when pure copper was used for the secondary conductors, the same holds true for the use of aluminum bronze.

(45) TABLE-US-00003 TABLE 3 Secondary conductor Voltage Power factor shape (V) Current (A) Capacity (kW) (%) None 418.0 74.5 14.1 45.2 Annular 419.7 86.7 21.7 59.6 Spiral 420.3 87.3 22.3 60.7 Entire surface 419.5 86.8 22.1 60.8

(46) Besides, it goes without saying that the present invention is not limited to the above-described embodiment, but can be variously modified without departing from the scope thereof.

LIST OF REFERENCE CHARACTERS

(47) 100: Induction heated roll apparatus 2: Roll main body 201a: Inner circumferential surface 3: Induction heating mechanism 32: Induction coil 4: Secondary conductor