JPH11114907A - Hot press heating method and heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating method of a hot press capable of heating a plate-shaped object to be heated with a simple device with good thermal efficiency. SOLUTION: Under the influence of an induction coil 4, a laminate 3 formed by alternately laminating one sheet of a material to be heated 1 and a metal plate 2 so that a plate-like object 1 to be heated is sandwiched between metal plates 2 is formed. An AC current is applied to the induction coil 4 to generate an eddy current in each of the plurality of metal plates 2 constituting the laminated body 3, thereby causing each of the metal plates 2 to generate heat. Thus, the material to be heated 1 is heated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and apparatus for heating a hot press. More specifically, a hot press that heat-presses and bonds multiple sheets of wood, such as wood, plywood, laminated boards, laminated wood veneers, etc., or heat-presses and bonds sheet materials to the surface of these boards. And a heating device.

[0002]

2. Description of the Related Art In a conventional hot press, as shown in FIG. 4, a hot plate 51 through which steam is passed is used so that a plate material 1 to be heated is sandwiched between the hot plates 51 one by one. To
The object to be heated 1 and the hot platen 51 are alternately stacked in 5 to 10 stages,
The pressure table 54 and the pressure slide 5 via the heat insulating materials 52 and 53
It is set between 5. Pressure table 54 and pressure slide 5
5 is supported by a pressing frame 56 so that the pressing surface is kept parallel. The pressing slide 55 is provided with a pressing cylinder 57 and, as shown in FIG. 5, a returning cylinder 58.

[0003] The thickness T2 of the hot platen 51 is about 50 mm. Inside the hot platen 51, as shown in Fig. 6, a passage 60 for passing steam as a heating medium is provided. The passages have through holes 61 and 62 having a diameter of about 20 to 30 mm.
Are provided vertically and horizontally, and a steam passage is formed by the stopper 65. The steam entered from the inlet 63 is guided in the direction of the arrow, and the outlet 64
It has become more spillable.

As shown in FIG. 7, the hot platen 51 thus formed has a discharge port 64 and a fill port 63 in order from a lowermost platen 51a to an uppermost platen 51b. The lowermost inlet 63a is connected to an external boiler, and the upper outlet 64b is connected to an external steam collector.

[0005]

However, as described above, the production of a hot plate is very troublesome and has a problem of high cost. In addition, there is also a problem that the drain tends to accumulate particularly on the lowermost platen, and a temperature difference is likely to be generated between the upper platen and the lower platen. Originally, a heating device using a heat medium such as steam has a low thermal efficiency, and only about 10 to 20% of the calorific value of steam is used.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a heating method and a heating apparatus for a hot press which can heat a plate-shaped object to be heated efficiently with a simple apparatus. To provide.

[0007]

According to a first aspect of the present invention, there is provided a laminated body in which a single heated material and a metal plate are alternately laminated such that a plate-like heated object is sandwiched between metal plates. Is placed under the influence of the induction coil, and an alternating current is applied to the induction coil to generate an eddy current in each of the plurality of metal plates constituting the laminate, thereby causing each metal plate to generate heat. The object to be heated is heated by a metal plate. Since it is not necessary to form a hole through which a heat medium such as steam passes as in the related art, and no troublesome processing is required, cost reduction can be achieved. The metal plate can be made thin. As a result, the press height can be reduced and the cost can be reduced. Higher thermal efficiency and lower maintenance costs compared to heating with a heat medium.

According to a second aspect of the present invention, in addition to the method of the first aspect, the induction coil is arranged so as to generate an eddy current at least near an end in a direction orthogonal to a laminating direction of the metal plates. The heat generated near the end is conducted to the inside and the entire surface of the metal plate is heated. When the induction coil is disposed on the outer periphery of the laminate, the magnetic field tends to concentrate on the end of the metal plate, and the end generates heat efficiently. The metal plate is a substance that easily conducts heat, and as soon as the temperature near the end becomes high, the whole becomes high in temperature.

According to a third aspect of the present invention, in addition to the first or second aspect, the metal plate has magnetism. Since the magnetic material increases the magnetic field and increases the eddy current, the calorific value increases. Here, the magnetic material generally indicates a metal having magnetism such as iron, and an ordinary steel plate which is a ferromagnetic material without adjusting the components is preferable from the viewpoint of strength and cost.

[0010] The invention according to claim 4 is the invention according to claims 1 to 3.
In addition to the invention described in any one of the above, the frequency of the alternating current supplied to the induction coil is 1 KHz or less. By setting the frequency to a low frequency of 1 KHz or less, the metal plates at the uppermost stage and the lowermost stage in the stacking direction,
The temperature difference with the central metal plate disappears. That is, as the frequency increases, the heating tends to concentrate on the upper and lower ends in the stacking direction. Therefore, by applying a low-frequency magnetic field, the magnetic field can be sufficiently applied to each metal plate. , Can be made uniform.

[0011] The invention according to claim 5 is the invention according to claims 1 to 4.
In addition to the invention described in any one of the above, the frequency is 20H
z or less. Even in the same metal plate, a temperature difference may occur between the vicinity of the end and the center. In that case, by further lowering the frequency to 20 Hz or less,
The temperature can be raised so as not to cause an in-plane temperature difference. However, if the frequency is too low, the heating efficiency decreases, so that it takes time to heat. In the present invention, it is preferable to determine an optimum frequency at which heating is performed at a uniform temperature so as not to reduce the time required to reach a predetermined temperature, in consideration of the two factors of uniformity and heating efficiency.

The invention according to claim 6 is the invention according to claims 1 to 5
In addition to the invention described in any one of the above, heating is performed while changing the frequency of an alternating current supplied to the induction coil. By changing the frequency, the magnitude of the amount of generated heat can be controlled, and heating can be performed quickly without causing a temperature difference.

According to a seventh aspect of the present invention, there is provided a hot-heating apparatus which performs electromagnetic induction heating on a laminated body in which a single object to be heated and a metal plate are alternately stacked such that a plate-shaped object to be heated is sandwiched between metal plates. A heating device for a press, comprising: (a) a pressurizing table on which the laminate is placed, a pressurizing slide that moves up and down above the pressurizing table, and a pressurizing device that supports a driving device of the pressurizing slide. A frame; (b) an induction coil for applying a magnetic field to the laminate so as to generate heat by generating an eddy current in the metal plate by a magnetic field; and (c) applying an AC current to the induction coil. Power supply means for generating a magnetic field is provided. Since it is not necessary to form a hole through which a heat medium such as steam passes as in the related art, and no troublesome processing is required, cost reduction can be achieved. The metal plate can be made thin. As a result, the press height can be reduced and the cost can be reduced. Higher thermal efficiency and lower maintenance costs compared to heating with a heat medium.

According to an eighth aspect of the present invention, in addition to the seventh aspect of the present invention, the distance between the pressure slide and the uppermost metal plate or between the pressure table and the lowermost metal plate is reduced. A heat insulating material is provided between them. If the heat generated from the metal plate is transmitted from the pressure slide or the pressure table to the main body of the heating device, the heat efficiency is deteriorated. Insulation prevents this.

According to a ninth aspect of the present invention, in addition to the seventh or eighth aspect, a plate having a slit or a dividing portion for suppressing generation of an eddy current is provided at an uppermost metal plate or at a lowermost stage. A support plate is provided between the support plate and a metal plate. The support plate has a function of adjusting the thickness so that the center of the stacked body 3 in the height direction is located at the center of the induction coil 4, and is for guiding the magnetic flux to the stacked body 3. Further, by using the hot plate (steam or electrothermal heating) for the support plate 6, it is possible to suppress the radiation of the upper and lower portions. By providing a slit or a dividing portion in a divided body formed of a conductive material, eddy current generated in the divided body can be reduced.

[0016]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic explanatory view of a heating device for a hot press of the present invention.

In FIG. 1, a heating apparatus according to the present invention is provided on a metal plate 2 for sandwiching a plurality of objects to be heated one by one, and on an outer periphery of a laminate 3 composed of the object to be heated 1 and the metal plate 2. An induction coil 4 is provided. The press table 54, the press slide 55, the press frame 56, the press cylinder 57, and the return cylinder 58 (see FIG. 5), which are mechanisms for pressurizing, are the same as those in the related art, and show the related art. The same reference numerals as in FIGS. 4 and 5 are used. In the present invention, as a heating mechanism, electromagnetic induction heating is performed using the metal plate 2 and the induction coil 4.

The material to be heated 1 is plate-shaped, and its both surfaces and the metal plate 2 can be in close contact with each other. The material to be heated 1 is pressed and molded and adhered at a high temperature. For example, wood such as laminated wood, plywood, a laminated plate obtained by laminating a plurality of plate materials, or a material in which a sheet material for makeup or the like is adhered to the surface thereof is used.

The metal plate 2 is a square flat plate, has a length and width slightly larger than the object 1 to be heated, and has a size capable of completely covering two surfaces orthogonal to the lamination direction of the object 1 to be heated. Further, it is made of a conductive material, and when placed in an environment where the magnetic flux changes, an eddy current is generated inside and heat is generated. Further, if the metal plate 2 in the path of the magnetic flux has magnetism, the magnetic field can be strengthened, the generated eddy current increases, and the amount of heat generated increases. Therefore,
It is preferably a magnetic material such as iron or ordinary steel plate. Note that the metal plate 2 may be circular, elliptical, or polygonal.

The metal plate 2 is alternately stacked with the object 1 to be heated so as to be in contact with both surfaces of the object 1. The dividing plate 5 and the support plate are provided below the lowermost metal plate 2a. 6. The heat insulating material 7 is arranged in this order and placed on the press table 54. Similarly, above the uppermost metal plate 2b, a dividing plate 5, a support plate 6, and a heat insulating material 7 are arranged in this order, and a pressing slide 5
5. The metal plate 2 is a flat plate having a simple shape, and the thickness T1 of the metal plate 2 is about 25 mm, which is very thin compared to the hot platen 51 shown in FIG. Therefore, many objects to be heated 1 can be stacked and the apparatus can be simplified.

An induction coil 4 is spirally wound around the outer periphery of a laminate 3 composed of a metal plate 2 and an object 1 to be heated, and a low-frequency AC generator 8 is connected to the induction coil 4. 4 is energized. The low-frequency AC generator 8 is formed of, for example, an inverter device, and can generate an AC having an arbitrary frequency of 1 KHz or less. The induction coil 4 is preferably disposed between the lowermost and uppermost metal plates 2a, 2b and as close as possible to the end of each metal plate 2. The magnetic flux formed by the induction coil 4 passes under the uppermost metal plate 2b, penetrates near the end of each metal plate 2 as indicated by a dotted line, and passes through the lowermost metal plate 2b.
A loop is formed to cover the upper side of a. Then, an eddy current is generated near the end of each metal plate 2. Due to the I ² R loss due to the eddy current, heat is generated in the vicinity of the end of the metal plate 2, and the heat is conducted inward by heat conduction to heat the entire metal plate 2.

As shown in FIG. 1, it is preferable to use a hollow conductive wire for the coil 9 constituting the induction coil 4, and a cooling medium is introduced into the hollow 9 a inside to cool the induction coil 4. . The planar shape of the induction coil 4 only needs to be large enough to dispose the laminate 3 in the internal space, and may be appropriately selected such as a square, a circle, or an ellipse. The cooling medium may be a liquid such as water or a gas such as nitrogen gas.

The support plate 6 is provided on the uppermost or lowermost metal plate 2a, 2b with the divided plate 5 interposed therebetween.
The support plate 6 has a function of adjusting the thickness so that the center of the laminate 3 in the height direction is located at the center of the induction coil 4, and is for guiding the magnetic flux to the laminate 3. is there. Further, by providing a heating plate that generates heat by passing steam into the inside of the support plate 6 or incorporating a heating wire therein, heat radiation in the upper and lower portions can be suppressed.

The dividing plate 5 prevents the eddy current generated in the body of the metal plates 2a and 2b from being transmitted to the support plate 6 and becomes large. As shown, it is divided at the center 5a and has a slit 5b. The size of the slit 5b may be formed deeper than the center as shown by a broken line.

The heat insulating material 7 prevents heat of the laminate 3 and the support plate 6 from being conducted to the entire pressurizing device. In addition to polyimide, Teflon, and other resins having good durability against high temperature and high pressure, It is preferably formed from a material such as ceramic.

Next, a method of heating the material to be heated 1 by hot pressing will be described with reference to FIG.

The metal plate 2 is a good heat conductor, and
The material to be heated 1 in contact with both surfaces is an insulating material and has good heat insulating properties. Therefore, the material to be heated 1 does not directly generate heat, and the heat generated in the vicinity of the end of the metal plate 2 does not dissipate to the material to be heated 1 and immediately goes to the central portion as shown by the arrow. Thus, the state is substantially equivalent to that the entire metal plate 2 generates heat. Next, heat conduction is gradually performed from the entire metal plate 2 thus heated toward the material to be heated 1 as indicated by an arrow. Since such heat conduction occurs in each of the metal plates 2, the entire laminate 3 is uniformly heated from the inside.

On the other hand, if the frequency of the AC from the AC generator 8 is too high, heat is generated only at the ends A and B of the metal plates 2a and 2b at the uppermost and lowermost stages in the stacking direction of the metal plates 2. It has been found that a temperature gradient occurs in the stacking direction. In order to generate heat in the vicinity of the end of each metal plate 2, it is necessary to set a low frequency of 1 kHz or less.

Further, even at a low frequency of 1 kHz or less,
A temperature gradient may occur in a direction perpendicular to the laminating direction inside the metal plate. In that case, if the frequency is further reduced, the metal plate 2 in this direction (the direction orthogonal to the laminating direction)
, The penetration depth (skin depth) of the magnetic flux increases. For this reason, the radial distribution of Joule heat induced in the metal plate becomes broader by lowering the frequency, so that the in-plane temperature difference becomes smaller. Therefore, in the present invention, it is preferable to set the low frequency to 20 Hz or less. On the other hand, if the temperature is lowered too much, the efficiency of heating deteriorates. Therefore, it is preferable to determine the frequency in consideration of uniformity and efficiency. For example, the frequency is preferably about 1 Hz or more. Further, it is also preferable to heat while changing the frequency.

In the above-described embodiment, the induction coil wound spirally along the outer periphery of the laminated body 1 is exemplified. However, the induction coil wound around the outer periphery of the laminated body 1 is divided into several parts. It may be one that is attached. Further, an induction coil may be wound around a concave iron core, and the laminate may be arranged under the influence of the magnetic flux of the concave iron core. In short, it is sufficient that magnetic flux penetrates into each of the internal plates constituting the laminated body 1 and preferably generates heat at the radial ends of the internal plates.

[0031]

As described above, according to the first to third aspects of the present invention, the object to be heated is sandwiched between the flat metal plates, and the metal plates are arranged under the influence of the induction coil to generate an eddy current. It is a method of heating the material to be heated by causing the metal plate to generate heat,
Since the metal plate having a simple shape and the thickness may be small, the cost of the apparatus can be reduced, and the thermal efficiency is good, so that the maintenance cost can be reduced.

According to the present invention, the frequency of the alternating current supplied to the induction coil is set to a low frequency of 1 kHz or less, or a lower frequency of 20 Hz or less, so that the temperature difference in the stacking direction of the stacked body is reduced. That is, the temperature difference between the uppermost or lowermost metal plate and the central metal plate can be eliminated. Further, it is possible to eliminate a temperature difference in a direction orthogonal to the laminating direction of the metal plates, that is, a temperature difference between the vicinity of the end and the center of one metal plate in the body.

According to the seventh to ninth aspects of the present invention, the object to be heated is sandwiched between the flat metal plates, and the metal plates are arranged under the influence of the induction coil, thereby generating an eddy current and causing the metal plates to generate heat. This is a device for heating a material to be heated, and a metal plate having a simple shape and a small thickness may be used, so that the cost of the device can be reduced, and the thermal efficiency is good, so that the maintenance cost can be reduced. Also,
Insulation prevents the laminate from directly contacting the heating device, which prevents heating of the heating device and increases heating efficiency.
Further, a support plate is provided via a plate (divided plate) having a dividing portion between the heat insulating material and the metal plate, and eddy current generated in the support plate is suppressed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of one embodiment of a heating device for a hot press of the present invention.

FIG. 2 is a diagram illustrating an example of a planar shape of a split plate of FIG. 1;

FIG. 3 is a view showing another example of the planar shape of the split plate of FIG. 1;

FIG. 4 is an explanatory view of a heating device of a conventional hot press.

FIG. 5 is a plan view of FIG. 4;

FIG. 6 is a structural sectional view of a hot plate of a conventional hot press.

FIG. 7 is a structural explanatory view of a state where the hot plates of FIG. 4 are stacked.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heated material 2 Metal plate 3 Laminated body 4 Induction coil 5 Split plate 6 Support plate 7 Insulation material 8 Low frequency alternating current generator

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Yoshinori Kurokawa 2-3-1, Shinhama, Arai-machi, Takasago City, Hyogo Prefecture Inside Kobe Steel, Ltd. Takasago Works (72) Inventor Hirohiko Fukumoto 1-chome, Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture No.5 Kobe Steel, Ltd.Kobe Research Institute (72) Inventor Toshiya Miyake 1-5-5 Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture Kobe Steel Co., Ltd.Kobe Research Institute

Claims (9)

[Claims] 1. A laminate formed by alternately laminating a material to be heated and a metal plate such that a plate-shaped object to be heated is sandwiched between metal plates is arranged under the influence of an induction coil. And generating an eddy current in each of the plurality of metal plates constituting the laminate by heating the metal plates to generate heat, and heating the material to be heated by the raised metal plates. Hot press heating method. 2. The induction coil is disposed so as to generate an eddy current at least near an end of the metal plate in a direction orthogonal to the laminating direction, and heat generated near the end is conducted to the inside to conduct heat. The heating method of a hot press according to claim 1, wherein the entire surface is heated. 3. The hot press heating method according to claim 1, wherein the metal plate has magnetism. 4. The hot press heating method according to claim 1, wherein the frequency of the alternating current applied to the induction coil is 1 KHz or less. 5. The heating method for a hot press according to claim 1, wherein the frequency is 20 Hz or less. 6. The hot press heating method according to claim 1, wherein the heating is performed while changing a frequency of an alternating current supplied to the induction coil. 7. A hot press heating apparatus for performing electromagnetic induction heating on a laminated body in which a single object to be heated and a metal plate are alternately stacked such that a plate-like object to be heated is sandwiched between metal plates. (A) a press table on which the stacked body is placed, a press slide above and below the press table, which moves up and down, and a press frame for supporting a driving device of the press slide; An induction coil for applying a magnetic field to the laminate so that an eddy current is generated by the magnetic field with respect to the metal plate to generate heat.
(C) A heating device for a hot press, comprising: a power supply for generating a magnetic field by supplying an alternating current to the induction coil. 8. The hot press heating according to claim 7, wherein a heat insulating material is provided between the pressure slide and the uppermost metal plate or between the pressure table and the lowermost metal plate. apparatus. 9. A supporting plate provided between the uppermost metal plate and the lowermost metal plate with a plate having a slit or a dividing portion for suppressing the generation of eddy current. A heating device for the hot press as described.