JPS58135594A - Induction heating method and device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an apparatus for dielectrically heating a liquid conductive material having a relatively high dielectric constant. The invention relates in particular to a device suitable for dielectrically heating blanks of building material.

i) [Description of the prior art] Apparatuses of this type are used, for example, for drying sheet-like materials or fiberboards, or for curing the binders contained therein. For this reason, the capacitor plate of this type of device faces the object to be heated, and the object to be heated is heated to a desired temperature in a high-frequency electric field generated between the capacitor plates by a high-frequency generator. There is.

However, this method has the disadvantage that unavoidable losses of various magnitudes occur depending on the properties of the object to be heated, and that the supply of energy cannot be controlled. For example, it is necessary to match the capacitance of the generator's oscillation circuit to the output of the generator so that it resonates as much as possible, but if the object to be heated has a lot of moisture, this matching must be done with great care. And it's not easy.

This point must be taken into consideration especially when the object to be heated is a conductive liquid and has a relatively high dielectric constant. Consideration must be taken, for example, when the purpose is to produce building materials, in particular blanks of building blocks for walls, in molds configured to receive a pourable raw material mixture. This raw material mixture consists of a thermosetting binder, e.g. cement with suitable accelerators, air bubbles, water, sand and other additives, which binder is based on calcium silicate. It is used to make lightweight building blocks or building blocks made of foamed concrete or heavy clay materials.

The purpose of this type of production method is to produce a raw material mixture containing a large amount of air bubbles as well as a large amount of water in order to minimize the bulk density of the blank.

The water content is 50 to keep the bulk density below 0.2 g/cn.
It can be included up to % by weight or even more.

Under these conditions, confining the raw mixture by a capacitor plate forming part of the mold has the disadvantage of not only causing high heat losses but also supplying heat in an uncontrolled and non-uniform manner. Ta.

[Purpose of the invention]

The present invention overcomes the above-mentioned drawbacks, and is capable of minimizing heat loss and uniformly supplying energy to a heated object, which has a relatively high dielectric constant. An object of the present invention is to provide a dielectric heating method and an apparatus therefor that can uniformly and quickly heat an object to be heated, even if the object has a high moisture content and occupies a relatively large volume.

[Features of the invention]

The present invention includes a high frequency generator and two capacitor plates connected to the high frequency generator, and a heated body made of a liquid conductive material having a relatively high dielectric constant is placed between the two capacitor plates. In the interposed dielectric heating device, a multilayer capacitor is formed by the two capacitor plates and a wall made of an electrically insulating material having a relatively low dielectric constant, which is provided parallel to and close to the inner surface of each of these capacitor plates. The heated body is disposed between the two walls, and an air gap is provided between the wall and the capacitor plate, and the width of the air gap is such that the capacitance of the multilayer capacitor is It is adjusted to match the maximum output of the generator and is characterized by rapid and uniform dielectric heating of the liquid conductive material.

[Explanation based on examples]

Embodiments of the present invention will be described below based on the drawings.

The figure is a longitudinal cross-sectional structural view of an apparatus according to an embodiment of the present invention.

In the figure, the mold IO is arranged on a transportable machine frame 11. In this example, the mold 10 is constructed of plastic and can be transported in a sealed manner. Note that a filling mechanism for the mold 10, a mechanism for taking out the product after molding, and a transfer mechanism for transferring the taken out product to a transportation means are omitted from the figure.

Two capacitor plates 12 are disposed parallel to and adjacent to the opposing side walls 10a of the mold IO. These capacitor plates 12 are provided over the entire surface of the side wall 10a, and in particular, the area of the capacitor plates 12 is larger than the area of the side wall 10a so that the output density of the capacitor plates 12 is as uniform as possible. The two capacitor plates 12 are connected to a high frequency generator 13. Also, these capacitor plates 1
2 is attached on the machine frame 11 by a support 15 via an insulating material 14 so as to be close to the side wall 10a.

The capacitor plate 12 is mounted slightly apart from the side wall 10a, and an air gap 16 is formed between the capacitor plate 12 and the side wall 10a. By adjusting the width of this air gap 16, the capacitance of the multilayer capacitor can be matched to the generator output. This multilayer capacitor includes a capacitor plate 12, an air gap 16, a side wall 1
0a, and the raw material mixture that makes up the blank, the contents of type IO. By adjusting the width of this air gap 16, the oscillation circuit of the high frequency generator 13 oscillates at a resonant frequency. In order to further achieve optimum high-frequency matching, a shunt capacitor 21 can be connected in parallel to this multilayer capacitor. This shunt capacitor 21 is
Additional capacitor plates can be formed by providing one spatial area of the capacitor plate 12.

Although the composition of the raw material mixture may change depending on the conditions,
For example, adjusting the composition of the blank to change its bulk density will change the capacitance of the multilayer capacitor as well. Even in such a case, a device can be provided to adjust the width of one or both air gaps 16 in order to optimally match its capacitance to the generator output. Which equipment is as shown?
A support 15 for moving one capacitor plate 12 via an insulating material 14 is slidably provided on a guide 18 . This strut 15 is connected in this example to a worm gear drive mechanism 19 and is driven manually and/or by a stamping motor 20 in order to adjust the width of the air gap 16.

Adjustment of the width of the air gap 16 depending on conditions is also performed automatically by the stamping motor 20 via an automatic control loop (not shown) to continuously match the generator output.

To make a building material blank with a dielectric heating device of such a configuration, an injectable raw material containing a thermosetting binder, preferably a hydraulic binder, plus a large amount of water and air bubbles, sand and other additives is used. After filling the mold 10 with the mixture as the object to be heated 17, a high frequency voltage is applied to the capacitor plate 12 from the high frequency generator 13. At this time, a multilayer capacitor is formed by the capacitor plate 12, the air gap 16, the side wall 10a, and the raw material mixture that is the contents of the mold 10. This many 1
- the capacitance of the capacitor is adjusted via the worm gear drive mechanism 19 by means of a stepper motor, with the width of the air gap 16 being adjusted to match the maximum output of the generator 13;

By adjusting the width of this air gap 16, the oscillation circuit of the high frequency generator 13 oscillates at the resonant frequency, but further optimal frequency matching is achieved by the shunt capacitor 21 connected in parallel to this multilayer capacitor. . The heated object 17 placed between the capacitor plates 12 has a dielectric constant generated by a high-frequency electric field, which causes the imaginary part of the complex permittivity of the heated object to be reduced.
Resistance heating generates heat depending on the temperature. Here, the wall 10a has a dielectric constant lower than that of the heated body, and in particular its loss angle and its
Since the product of the dielectric constant and the dielectric constant of is spent efficiently.

After the object to be heated 17 is heated, the liquid conductive material is cured, a blank of the cured building material is taken out by a take-out mechanism (not shown), and is transferred to a transportation means for the next process by a transfer mechanism.

[Explanation of application examples]

In the above example, the mold 10 is a mold box that can be lifted from the substrate, but a mold forming a channel can also be used instead of this mold box. In this channel, a continuous strand consisting of the raw material mixture is transported, and in the area between the capacitor plates this strand is heated and hardened. Once the cured strand is removed from this channel, it is separated into individual blanks. The advantage of this channel-shaped mold is that the heating takes place more slowly and over a longer distance, without adversely affecting the period.

Moreover, the multilayer capacitor of the dielectric heating device according to the invention can also be used for other purposes than the production of building material blanks, where there is a requirement to heat liquid or wet materials.

〔Effect of the invention〕

As described above, according to the present invention, even if the object to be heated is conductive and has a relatively high dielectric constant, a wall with a low dielectric constant is disposed between two capacitor plates, and the capacitor The width of the air gap between the board and the wall can be adjusted,
By forming a multilayer capacitor with this capacitor plate and air gear, the output of the high frequency generator is used to heat the heated object extremely efficiently, and true dielectric heating can be performed, minimizing heat loss. , which has an excellent effect of being able to perform uniform and rapid heating.

When implementing the invention industrially, it is also possible to operate at reduced frequencies, simplifying the implementation of the technique.

Further selection of the generator output will result in a higher dielectric strength and a more effective dielectric heating device.

[Brief explanation of the drawing]

The figure is a longitudinal cross-sectional structural view of a device according to an embodiment of the present invention. lO...Type, 11...Machine frame, 12...Capacitor plate, 13...High frequency generator, 14...Insulating material, 15
... Strut, I6... Air gear tube, 17... Heated object, 18... Guide, 19... Worm gear drive mechanism, 20... Stamping motor. Agent Patent Attorney Nao Ide Filial Procedures Amendment February 21, 1980 Commissioner of the Patent Office Kazuo Wakasugi 1981 Patent Application No. 013616 2 Title of Invention Dielectric Heating Method and Apparatus 3 Amendment Relationship with the case of a person who makes a patent application Patent applicant 7, subject of amendment 8, contents of amendment are supplemented as shown in the attached documents. 9. List of attached documents

Claims (1)

[Claims] (1) Comprising a high frequency generator (13) and two capacitor plates (12) connected to the high frequency generator (13), two capacitor plates (I2) marked F. In a dielectric heating device in which a heated body (17) made of a liquid conductive material having a relatively high dielectric constant is interposed between the two capacitor plates (12) and the two capacitor plates (12), A multilayer capacitor is formed by walls (10a) made of an electrically insulating material having a relatively low dielectric constant, which are provided in parallel and close to each inner surface, and the heated body (17) is connected to the two walls (10a). ), and an air gap (16) is provided between the wall (10a) and the capacitor plate (12), and the width of this air gap (16) is such that the capacitance of the multilayer capacitor is A dielectric heating device, characterized in that it is adjusted to match the maximum output of the generator (13). (2) A patent claim characterized in that the wall (10a) is made of an electrically insulating material whose product of its loss angle and its dielectric constant is smaller than the product of its loss angle and its dielectric constant of the liquid conductive material. The dielectric heating device according to item [11]. (3) The dielectric heating device according to claim 11 or (2), wherein the wall (10a) is made of plastic. (4) The capacitor plate (12) is made of plastic. The dielectric heating device according to any one of claims (1) to (3), characterized in that the dielectric heating device is mounted so that the distance to the capacitor plate (10a) can be adjusted. (5) The capacitor plate (12) and the wall (10a) is adapted to be adjustable by means of an automatic control loop to match the output of the high frequency generator. Heating device. (61 walls < 10a) is a dielectric device according to any one of claims 11 to 5, which is a part of a mold (10) for molding the object to be heated (17). Heating device. (7) A shunt capacitor in parallel with the capacitor plate 2) so that the high frequency to the heated object (17) is optimally matched. (
21) The dielectric heating device according to any one of Items 11 to 469, characterized in that: (8) At least one of the capacitor plates (12) is
The dielectric heating device according to any one of claims 11 to (7), characterized in that the area is significantly larger than the area of the wall (10a). (9) The heated object (17) is made of water. , a thermosetting binder, preferably a hydraulic binder, air bubbles and other suitable constituents, the injectable raw material mixture being molded into a mold (10) to form a building material, in particular a blank for a wall building block. Claim No. (11) characterized in that
The dielectric heating device according to any one of Items to Items (8). C1l Between two walls (10a) made of an electrically insulating material having a relatively low dielectric constant, parallel to and close to each inner surface of two capacitor plates (12) connected to a high frequency generator (13). An air gap (16) is provided between the wall (10a) and the capacitor plate (12), and an air gap (16) is interposed between the wall (10a) and the capacitor plate (12). (16) width by two capacitor plates (12
) and two walls (10a), the capacitance of the multilayer capacitor is adjusted to match the maximum output of the high frequency generator (13), and the dielectric heating method dielectrically heats the heated object (17).