JPS6163562A - High frequency continuous drying device for ceramic sheet - 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 Industrial Application) The present invention relates to a high-frequency continuous drying device for ceramic sheets that continuously dries green ceramic sheets using high-frequency waves.

(Prior art) Ceramic substrates, which are used in a variety of electronic components, are generally manufactured by extruding a green ceramic sheet from a mold of a molding machine, drying it and punching it into a predetermined shape, and then firing it in a firing furnace. has been done.

Conventionally, drying devices for drying raw ceramic sheets that are continuously extruded from molds of molding machines dry them by irradiating hot air, infrared rays, or far infrared rays to the raw ceramic sheets that are continuously conveyed by belts, etc. generally known.

By the way, in a drying device that uses hot air or infrared rays, a difference in moisture content occurs between the inside and the surface of the ceramic green sheet depending on the thickness of the green ceramic sheet and the conditions of the pond, causing warpage and cracks in the dry sheet.

This kind of warping and rr! In order to obtain a uniform dry sheet without cracks, it is necessary to slow down the drying speed of the green ceramic sheet, but slowing down the drying speed increases the drying time and requires the drying equipment in proportion to this drying time. There was a problem in that the process became long and the production efficiency of ceramic substrates decreased.

In a drying device that uses far infrared rays, when a raw ceramic sheet is continuously dried at a high speed, the initial drying is slow, so the raw ceramic sheet is easily deformed by tensile force, and the sheet width of the dried sheet is There was a problem in that variations occurred in thickness.

By the way, in recent years, drying equipment that uses high frequency waves or microwaves that can uniformly heat the material to be dried in a relatively short period of time has been put into practical use for drying wood, etc., and this type of drying equipment is also used for drying raw ceramic sheets. The use of drying equipment such as

Therefore, this type of drying equipment is for batch processing, and cannot be applied to continuous drying of ceramic raw sheets that are continuously extruded from the mold of a molding machine. Ta.

(Object of the Invention) The present invention has been made in view of the problem described in item 1 in drying green ceramic sheets. It is an object of the present invention to provide a high-frequency continuous drying device for ceramic sheets, which allows dry sheets having a moisture content to be obtained.

(Structure of the Invention) For this reason, the present invention has a shape of a high-frequency electrode placed at the bottom of a belt that continuously runs with a raw ceramic sheet placed thereon so that the high-frequency electric field at the center in the width direction of the raw ceramic sheet is at the edge. It is characterized by having a shape that makes it stronger than the high frequency electric field of. In other words, the present invention supplies high-frequency waves from a high-frequency oscillator to each high-frequency electrode placed at regular intervals in the conveying direction on the lower surface of a belt conveying a raw ceramic sheet, and utilizes dielectric heating caused by the high-frequency waves. According to the present invention, when drying a green ceramic sheet, the shape of the high-frequency electrode is devised to avoid concentration of high-frequency energy on the edge of the green ceramic sheet. Ceramic sheets can be uniformly and continuously dried using high frequency.

(Example) Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows the overall configuration of an embodiment of the high-frequency continuous drying apparatus for ceramic sheets according to the present invention.

The above-mentioned high frequency continuous drying device consists of a tunnel-shaped upper drying chamber 1. It is a three-stage drying chamber in which a middle drying chamber 2 and a lower drying chamber 3 are arranged on a base 4. Inside the upper drying chamber 1, from the outside of the population 1a to the outside of the outlet 1b, there is provided an upper belt 6 for placing a green ceramic sheet 5 thereon and transporting the green ceramic sheet 5. This upper belt 6 is connected to a roller 8 rotatably supported by a support 7a outside the population 1a of the upper drying chamber 1.
a and a roller 8b rotatably supported by a support 7b outside the outlet 1b of the upper drying chamber 1. On the upper belt 6, a raw ceramic sheet 5 extruded from a mold of a molding machine (not shown) is mounted on a roller rotatably supported by a support 7c outside the entrance ILI of the upper drying chamber 1. It is conveyed by a bell) 6a stretched between the second roller 8a and the second roller 8a.

Similarly, the inside of the middle drying chamber 2 is accessed from the outside of the inlet 2a located below the outlet 1b of the upper drying chamber 1.
The raw ceramic sheet 5 fed from the upper drying chamber 1 to the outside of the outlet 21+ located at the lower part of the inlet 1a of
A middle belt 9 is provided for conveying. The middle belt 9 is attached to the support 1 outside the entrance 2a of the middle drying chamber 2.
It is stretched between a roller lla rotatably supported by a roller 0a and a roller 1111 rotatably supported by a support 10b outside the outlet 2b of the middle drying chamber 2.

Also, inside the lower drying chamber 3, there is an outlet 2 of the middle drying chamber 2.
A lower belt 12 for conveying the green ceramic sheet 5 fed from the middle drying chamber 2 is provided from the outside of the inlet 3a located at the bottom of the drying chamber 2 to the outlet 3b. This lower belt 12 includes a roller 14a rotatably supported by a support 13a outside the entrance 3a of the lower drying chamber 3;
Outside the outlet 3b of the lower drying chamber 3, it is stretched between a roller 14 and the like supported by a support 13 [1 so as to be rotatable.

The above-mentioned upper belt 6, middle belt 9 and lower belt 12
At the bottom of , there is an arrow ^ as shown in the front view and plan view in Fig. 2(,) and Fig. 2(1)), respectively.

In the running direction of the upper belt 61, the lower belt 12, and the middle belt 9, indicated by and l\:, a rod-shaped positive (plus) high-frequency electrode 15 and a rod-shaped negative (
(minus) high frequency electrodes 16 are arranged alternately.

The following electrodes are used for some of the high frequency electrodes 15 and 16.

For example, as shown in FIG.
C is located at a position where the distance to the tips 15a and 16a is larger than 1/2 of the middle movement of the ceramic raw sheet 5, and the diameter is larger than the pond part (<ll1l).
It has a large diameter part]7.

Both sides 17a and 171 of the large diameter portion 17 are covered with insulators 18a and 18b such as Teflon.

As shown in FIG. 4, the high-frequency electrodes 15 and 16 are arranged with their respective large diameter portions 17 aligned, and the rear end 15b of the high-frequency electrode 15 and the rear end 1 of the high-frequency electrode 16 are aligned.
6b are pulled out from each side and each side of the upper belt 6°, the middle belt 9, and the lower belt 12 (see Fig. 2).
(see b)) and are respectively connected to a positive (plus) side output terminal and a negative (minus) side output terminal of a high frequency oscillator (not shown). The large diameter portions 17 of the high frequency electrodes 15 and 16 are all in contact with the lower surfaces of the upper belt 6, middle belt 9, and lower belt 12.

Upper drying room 1. Both the middle drying chamber 2 and the lower drying chamber 3 are shielded to prevent radio wave leakage.

In the high-frequency continuous drying apparatus having the above-mentioned configuration, the green ceramic sheet 5 continuously extruded from the molded gold (not shown) is heated to
In the upper drying chamber 1, the green ceramic sheet 5 is supplied onto the upper belt 6 by a and fed into the upper drying chamber 1 by a high frequency electrode 15, 16 placed in contact with the lower surface of the upper belt G. It passes through a generated high-frequency electric field and is dried by dielectric heating. The green ceramic sheet 5 enters the upper drying chamber 1 from the beginning 1a and passes through the high-frequency electric field until it exits from the outlet 1b, so that the green ceramic sheet 5 is continuously dried during this period.

The raw ceramic sheet 5 that has come out of the outlet 11+ of the upper drying chamber 1 is fed onto the middle belt 9, transferred to the middle drying chamber 2, and placed in the rl drying chamber 2, where it is continuously heated in the same manner as above. After being dried, the outlet 2b of the middle drying chamber 2
is supplied onto the lower belt 12.

The green ceramic sheet 5 is placed in the lower drying chamber 3 and is dried by passing through a high frequency electric field in the same manner as described above.
)2 is sent out from the outlet 31) of the drying chamber 3 as a drying sheet 5a.

In the high frequency continuous drying apparatus shown in FIG. 1, the large diameter portions 17 of the high frequency electrodes 15 and 16 shown in FIG.
and 171J, which is closer to the raw ceramic sheet 5, and the high-frequency electric field is concentrated at the 1° center in the lateral direction of the raw ceramic sheet 5, and on the contrary, the high-frequency electric field is dispersed at both ends of the raw ceramic sheet 5. . This accelerates the drying of the center of the width of the green ceramic sheet 5, where drying tends to be delayed even by dielectric heating by high frequency, and the green ceramic sheet 5 can be dried more uniformly.

As shown in FIG. 5, the high-frequency electrodes 15 and 16 include an electrode rod 21 made of a metal material such as aluminum having a constant diameter, and a distance from the tip 213 of the electrode rod 21 to the tip 213 of the green ceramic sheet 5 to 1 w1. It is also possible to use one that is bent or bent at a large position so that the distance to the raw ceramic sheet 5 is minimized, and the outside is insulated with insulation O (oil 22). Toru.

In addition, as shown in FIG. 6, a rod-shaped TL pole frame rod 23 insulating 11 molded with fat 24 is used as the positive (plus) high frequency electrode 15, and a negative (minus) high frequency electrode 1 is used.
6, the one described in FIG. 3 can be used.

Next, specific examples of the present invention will be described.

[Example 11] In the high frequency continuous drying apparatus shown in FIG. 1, the upper belt 6,
The total length of the part where the high frequency electrodes 15.16 are arranged at the lower part of the middle belt 9 and the lower belt 12 is 4.7 meters, and the entrance Ia of the upper drying chamber 1 and the entrance 2 of the middle drying chamber 2 are 4.7 meters long.
a, and 1 m from the entrance 3a of the lower drying chamber 3 and 21II
The high frequency electrodes 15 and 1G in the range between 1 and 2 were replaced with those explained in FIG. This high frequency electrode 15
The effective length of the large diameter portion 17 is 80b+m and 12 mm, respectively, and the diameter of both sides is 7 mm. 41) MHz high frequency, remaining 3
A high frequency of 0 MHz was applied. Barium titanate is used as the raw ceramic sheet 5, and the sheet thickness (')
, 40+a+o, belt speed 12+/min. As a result, a ceramic dry sheet without waviness was obtained. Furthermore, the moisture content was 4.5% at the center of the sheet and 4.8% at the edge of the sheet, with almost no difference in moisture content. There was almost no variation in sheet thickness.

[Example 21 Using the same high-frequency continuous drying device as in FIG. The positive high frequency electrode 15 in the range used in the first embodiment was replaced with a positive one.

Drying was carried out under the same high frequency conditions and sheet conditions as in Example 1. As a result, a dry sheet (Sa) without waviness was obtained, and the moisture content was 5% at the center of the sheet and 4.7% at the edge of the sheet, with a small difference in moisture content. Even after continuous drying, no change in moisture content or sheet thickness was observed.

[Example 31 Under the same conditions as Example 1, high frequency electrodes 15 and 1
Use the one in Figure 5 as 6, and use the ceramic raw sheet 5
Drying was carried out at a thickness of O, 50 mm, and a belt speed of 10+++/min. As a result, a dry sheet without waviness was obtained. Also, the moisture content in the center of the sheet is 4.8.
%, and 465% at the sheet edge, with almost no difference in moisture content.

The diameter of the high frequency electrode 15 and the 1G electrode rod 21 is 10
mmφ, the length of the shortest distance to the ceramic raw sheet 5 is 8 (hua), and the distance between the tip end 21a and the rear end 211+ of the electrode rod 21 and the ceramic raw sheet 5 is 7IIIO.

F Comparative Example 1 Under the same conditions as Example 1, high frequency electrodes 15 and 1
Drying was carried out using a rod-shaped electrode similar to the high-frequency electrode 15 shown in FIG. 6 as G. As a result, undulations were observed at the edge of the sheet and did not disappear. The moisture content was 6.5% at the center of the sheet and 3.0% at the edges, indicating that the edges of the sheet were drying.

The present invention is not limited to the three-stage type explained in FIG. 1, but can also be applied to a one-stage type or an arbitrary number of stages.

It should be noted that the high frequency of the high frequency continuous drying device H in the present invention includes the microwave region.

(Effects of the Invention) As is clear from the detailed description above, the present invention has the following effects:
When the green ceramic sheet conveyed by a belt is continuously dried by dielectric heating using high frequency waves, the high frequency electric field is concentrated at the center of the green ceramic sheet in the width direction, so that the green ceramic sheet is dried in the width direction as well as at both ends. Drying is promoted from the center, and a good dry sheet with stable dryness, good dimensional accuracy, strong sheet strength, and no sheet breakage or bending can be obtained.

Further, according to the present invention, it is possible to continuously dry a green ceramic sheet by high-frequency heating, and the productivity of ceramic substrates used in various electronic components can be greatly improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the entire high-frequency continuous drying apparatus for ceramic sheets according to the present invention, FIG.
Figure (b) is a front view and a plan view showing the arrangement of the high-frequency electrodes with respect to the belt of the high-frequency continuous drying apparatus for ceramic sheets shown in Figure 1, respectively. A cross-sectional view of one electric power unit, Figure 4 is the third
Figure 5 is a cross-sectional view of a modification of the high-frequency electrode shown in Figure 3, and Figure 6 is an explanatory diagram of a modification of the high-frequency electrode arrangement. 5...Ceramic green sheet, 5a...Drying sheet, 6...Upper belt, 9...Middle belt,
12...Lower belt, Is, 1f3...High frequency electrode, 17...Large diameter ML 18.19...
・Part 11, 21.23...Electro stick. Patent Applicant Mura Co., Ltd.('rI Kabesakusho Representative Patent Attorney Aoyama Bohaka 2 people 3rd cause 4th cause 5th cause 6th figure)

Claims (1)

[Claims] (1) A high-frequency continuous drying device for ceramic sheets that continuously dries a green ceramic sheet placed on a continuously running belt by passing it through a high-frequency electric field, the device being arranged on the lower surface of the belt and The high-frequency electrodes arranged at approximately constant intervals in the running direction have a shape such that the high-frequency electric field at the center in the width direction of the green ceramic sheet is stronger than the high-frequency electric field at the ends. Features: High-frequency continuous drying equipment for ceramic sheets.