JPS63153335A - Microwave oven - Google Patents

Abstract

PURPOSE:To prevent noise from occurring, improve the wear resistance in oil and water, and improve the heat resistance and anti-compressibility by firing a roller made by compression-molding teflon PFA resin with glass fibers added to it. CONSTITUTION:Microwaves are supplied by a magnetron oscillator 10 through a waveguide 9. Hot air is supplied in such a manner that air heated in a heater chamber 12 is drawn from its center and delivered out of its periphery by a turbo fan 13, which is then supplied through punching ventilation holes 11 in the rear of the cooking chamber 7. A sheathed heater 14 is disposed around the turbo fan 13 in the heater chamber 12, while a motor 15 drives the fan 13. A metallic turn-table 2 is supported by rollers 1, and a magnet 3 is fixedly attached thereto. The metallic turn-table 2 is rotated by the mutual attraction with a magnet 6 fixedly attached to the table 5. The anti-compressible rollers 1 are made of glass fibers 50% and teflon PFA resin 50%, and is firing-treated for 30 minutes at 300 deg.C after being press-molded. Owing to said rollers, operating noise can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a high-frequency heating device, particularly to a roller supporting a rotating tray.

Conventional technology In FIG. 4, the roller 1 of the conventional high-frequency heating device is
In order to withstand the load applied to the rotating tray (hereinafter referred to as the rotating table) and achieve smooth rotation, special hard ceramic materials such as alumina and Rulon (trade name of Toyo Bearing Co., Ltd.: Rockwell hardness 123°) are used. I was using it.

For example, a device using a magnetic drive type in which a magnet 3 is attached to a metal rotary table 2 may be exposed to abnormally high temperatures even during high-frequency heating. That is, in order to prevent the magnet 3 from being overheated by high frequency waves, a metal magnet case 4 is provided in explosive contact with the rotating table 2, which is also made of metal, and the distance 1 from a to b in the figure substantially corresponds to the high frequency wave in the heating chamber. Since the dimension (approximately 30 m) is close to % of the wavelength of , the electric field in the section a becomes strong, and as a result, a large surface current flows on the surface of the rotary table 2 in the section a, causing overheating. Therefore, the temperature of the roller 1 becomes high even during high-frequency heating.

This means that even when the oven function is provided recently, an electric heating device is provided near the roller 1, so the roller 1 is similarly exposed to high temperatures during oven heating.

On the other hand, in the case of FIG.
The system is such that the 0-rotation driving force is combined by the mutual attractive force of the magnets 3 and 6 to transmit the driving force. Therefore, in addition to the weight of the saucer and heated object placed on the rotary table 2 (which may exceed S&S), the magnetic attraction force is added, so a considerably large compressive load is applied. It will be done.

Therefore, the material of the row 21 needed to be able to maintain its hardness even at high temperatures.

Furthermore, in the case of Fig. 4, since the compressive force on the roller 1 is applied from above and below, the amount of deformation of the roller 1 is doubled, and the amount of change ΔP in the height dimension P of the roller 1 is If it becomes 0.318, the situation is such that rotation will be defective.

Therefore, in order to withstand long-term use, it is necessary to have good compression creep resistance.

However, heat resistance, high hardness and compression creep resistance alone are insufficient.
Not enough. That is, the electric field distribution inside the heating chamber of high-frequency heating has standing waves. In particular, in the case of a turntable system, the electric field distribution in the radial direction cannot be eliminated. As described in FIG. 4, when overheating occurs in one section, this phenomenon is aggravated and the non-uniformity of the temperature rise is accelerated.

At this time, due to a difference in thermal expansion, the rotary table 2 causes deformation such as waving, and the angle P between the rotary table 2 and the bottom surface 17 of the heating chamber shown in the figure varies depending on the position on the circumference. Gaps are formed intermittently between the roller 1 and the roller 1, which has a large hardness, and various vibrations occur during rotation, which causes a collision noise with the roller 1.

The generation of this sound is further doubled when dirt and food particles accumulate on the bottom surface 17 of the heating chamber.

For this reason, conventionally, during high-frequency heating, the roller 1 generates abnormal noise, and since the vibration energy is large, the abnormal noise may be surprising.

Therefore, it absorbs this abnormal sound, withstands high loads at high temperatures,
There was an urgent need to develop a roller that would not undergo compression deformation for a long period of time.

Problems to be Solved by the Invention The present invention provides a high-frequency heating device having a structure that is suitable for preventing abnormal sounds from being generated during use.

Moreover, the rotating table 2 is interposed between the rotating table 2 and the bottom surface 17 of the heating chamber.
A roller ring drive method in which the roller ring rotates at zero rotation speed can reduce the rotational torque to a small extent, but is extremely vulnerable to rotational failures due to roller deformation. For this reason, one of the objectives is to provide a roller that is less resistant to compressive deformation at high temperatures.

In addition, one of the other purposes is to start the process after a long-term load has been applied to a part (start at a scheduled time, or start when switching from open heating to high-frequency heating). It is possible to prevent rotation defects due to roller deformation. The object of the present invention is to provide a roller having good compression creep resistance.

Means for Solving the Problems In order to achieve the above object, the present invention focuses on the generally known Teflon PF resin, adds glass fiber to this Teflon PF resin, and sinters a compression molded roller. As a result, a Teflon roller made of a fluororesin with good compression resistance was obtained.

Function The roller supporting the rotary table of the present invention has extremely low hardness to prevent the generation of normal noise, has excellent abrasion resistance in oil and water, and is heat resistant even at high temperatures.
This resin has excellent compression resistance.

Example Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 show a first embodiment in which the compression-resistant fluororesin of the present invention is employed in a high-frequency heating device equipped with a hot air circulation type electric heating device.

The heating chamber 7 has a door 8 for taking food in and out, and high frequency power is supplied from a magnetron oscillator 10 through a waveguide 9. The hot air is passed through the punched ventilation hole 1 at the rear of the heating chamber 7.
1, air heated in an electric heating chamber 12 is taken in from the center by a turbo fan 13 and sent from the periphery. A sheathed heater 14 is arranged around a turbo fan 13 in the electric heating chamber 12, and the fan 13 is driven by a motor 15.

The bottom surface 17 of the heating chamber 7 is a concave surface so that the saucer 16 can be easily taken in and out, and a metal rotary table 2 is mounted on the concave ridge.
is being stolen. A metal rotary table 2 is supported by rollers 1 and has magnets 3 fixed thereto.

The metal rotary table 2 is rotationally driven by mutual attraction with a magnet 6 fixed to the table 6. The table 6 is pivotally supported outside the bottom surface 1 of the heating chamber, and is driven by a motor 18.

FIG. 2 shows a second example of a high-frequency heating device with an electric heating device in which an electric heater 19 is installed in the heating chamber T and a roller 1 is interposed between the bottom surface 17 of the heating chamber 7 and a metal saucer 2o. An example is shown. Door 8. The waveguide 9 and magnetron 10 have the same configuration as above.

The metal saucer 20 has a connecting portion 22 with a drive shaft 21 in the center thereof, and is rotationally driven by a motor 23 provided outside the bottom surface 17 of the heating chamber 7 . The roller ring 24 is the rotating saucer 2
It rotates while being positioned in the center by a claw 25 provided at the center. The heater 19 is located in the upper part of the heating chamber 7 (some heaters are located in both the lower and upper parts, but in FIG. 2, only the upper part is shown).

) and has the ability to raise the temperature inside the heating chamber 7 to about 260°C.

For this reason, the metal rotary table 2 directly receives radiant heat from the heater 19, so that the temperature rises to approximately 280°C.

Below, Teflon roller 1 made of compression-resistant fluororesin of the present invention
We report on the performance test results.

Current Teflon materials include TFK and RFP.

Three types of fluororesins (tetrafluoroethylene,

Among these, PF resin has a molecular structure in which 10-R,r (perfluoroalkoxy group) is replaced with fluorine and y in part of the C chain, and has a melting point of 3.
1Q''C2 At a continuous use temperature of 260'C, it has better thermal properties at 30°C and 60'C compared to FICP (copolymer of tetrafluoroethylene and hexafluoroethylene) resin, respectively. Moreover, as shown in Table A below, it has better compression creep properties than TFR resin.

It can be seen that the resin has extremely good permanent deformation.

Load: 910A at 23°C 140, 150°C-1
ooky/cd table B FFF 'Theacrn' TFK resin -c-c-c-c-11
I I FFF FFF l 111 FFF 'Teflon' PF human resin -c-c-c-c+111 FOF f This compression-resistant roller 1 is made of glass fiber esO%.

Teflon fluororesin 5 ozb (average particle size Too~900
μffi, having a bulk specific gravity of 700 to 760 g/ll, for example, Ho5taflon TFM manufactured by DuPont, 19
Introduced in 1972, it is a melt-flowable resin with good moldability. ), which was press-molded and then fired at approximately 300°C for 30 minutes.

When we checked for abnormal noises during operation with this prototype roller, there were no problems at all.

Even better, if there are food particles or dirt on the bottom 17, use Teflon(tetra)yethylene.

The sliding surface of the roller 1 after each of the above tests was extremely smooth and glossy because it was absorbed between the soft tissues of the DuPont Company.

The sliding surface of the current Rulon product (made by Toyo Bearing, filled with 26 to 30 pieces of glass fiber with a resin mainly composed of polyphenylene sulfide) has an uneven surface due to cement powder falling off. was noticeable, and solid matter such as dregs remained attached to the surface, making abnormal noise extremely likely to occur.

Roller 1 is made of pure Teflon and is wear resistant.

Since mechanical properties such as compression resistance are insufficient, fillers such as glass fiber are added to significantly improve these mechanical properties, but adding fillers such as glass causes voids inside the roller. ) occurs. The occurrence of these voids is largely due to the molding conditions, and the more voids there are, the lower the compression creep resistance becomes, leading to cracking during use. The present invention uses a method of firing the roller after compression molding, melts the fluororesin to improve fluidity, eliminates voids, and reduces the glass fiber content to 26% compared to conventional roller materials. By dramatically improving the mechanical properties of the roller, which was considered to be the limit, to 6 degrees, a roller with the desired mechanical properties was achieved.

The overall evaluation of each of these tests is shown in Table C below.

(Hereinafter referred to as Shimokin White) invention effect The effects of the present invention can be summarized as follows.

(1) The Rockwell hardness of the roller, which was about 120, decreased to less than 80 and was extremely small, so no abnormal noise was generated.

This is thought to be because the Teflon fluororesin (Rockwell hardness: 18), which is made of glass fibers, absorbs vibrations and prevents abnormal noise from occurring.

(Takumi) A roller with excellent compression resistance and compression creep resistance at high temperatures was obtained.

This takes advantage of the fact that Teflon fluororesin is a soft material, but when filled with glass fiber, it produces very little bulk (porosity) and is resistant to deformation under compressive loads. 9. A method of uniformly baking at approximately 300°C after press forming. This was achieved by increasing the glass fiber filling rate to nearly 60%.

As shown in Figure 6, conventional rollers made of ceramic wax have stable compression resistance up to high temperatures (load of 11k).
The roller does not deform and rotates smoothly even when weight is placed on it. ) is excellent.

However, food scraps, oil, and soybean oil are left behind during cooking.

The rollers will be deteriorated by absorbing oil and liquid from the bottom surface 17.

For example, when the above-mentioned Rulon is used in this state for a long period of time and is repeatedly subjected to thermal stress due to high temperatures, the material changes, and parts of the rollers become chipped and the surface becomes rough. Since the roller is confined between the rotary table and the bottom of the heating chamber and rotates with some sliding, surface wear is further accelerated and the roller diameter is reduced. As a result, the pitch P shown in FIG. 4 becomes smaller, and the distance between the magnet 3 of the rotary table 2 and the bottom surface 17, which was kept constant by the rollers, becomes smaller, the magnetic attraction force increases, and the electric field strength also increases. As a result, the temperature of the magnet 3 and metal rotary table 2 rises, resulting in a compressive force.

It is accelerated by the high temperature, and eventually the bottom surface 17 and the magnet 3 rub against each other, and the magnet 3 becomes unable to rotate.

In particular, this roller rotates while crushing food waste and riding on it, which results in abnormal noise.

On the other hand, both the prototype product and the product of the present invention have resins with extremely soft hardness, and as shown in Figure 6, although their compression resistance is slightly inferior to the conventional product depending on the temperature, there is no problem in practical use. It has become a thing. In other words, even if the prototype is under consideration, if it is used at temperatures below 150"C, the load it can be placed on will be fine up to skg.Furthermore, the safety margin for use of the present invention is based on the prototype under consideration. In comparison, by firing after press forming, bulk formation is suppressed,
It has improved hardness, and compression resistance at high temperatures is 7K.
As a result of this improvement, the roller of the present invention does not generate abnormal noise and can maintain smooth rotation even when a small amount of food has fallen. .

It also has excellent abrasion resistance in oil and water, and is heat resistant.

It also has excellent compression resistance and compression creep resistance.

(3) Conventionally, as shown in FIG. 1, a system was adopted in which the radiant heat of the heater 2o was received by the saucer 10, and care was taken to prevent the radiant heat from reaching the rollers.

However, according to the present invention, in a high-frequency heating device having an electric heating device such as a heater in the upper part of the heating chamber as shown in FIG.
The structure of the saucer can be simplified and inexpensive, such as by allowing the use of a saucer (structure in which the and the saucer 1o are integrated).

Furthermore, since the heat resistance has been improved even when the electric heating device is brought close to the roller, there is no problem, so the roller of the present invention can also be used in high frequency heating devices that have an electric heating device on the bottom of the heating chamber. It has become possible to use it, and its open performance has improved.

(4) Even at high temperatures, a roller with extremely good compression resistance was obtained, making it possible to use a roller ring type magnetically coupled driving force type with light driving force in a high-frequency heating device with an electric heating device, as well as heating We were able to create a structure in which the drive shaft does not penetrate through the bottom of the chamber, creating a highly user-friendly high-frequency heating device.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a high-frequency heating device with an electric heating device, which is an embodiment of the present invention, and FIG. 2 is a side sectional view of a high-frequency heating device with an electric heating device, which is another embodiment of the present invention. ,
FIG. 3 is an external perspective view showing the roller ring part of the device;
FIG. 4 is a side sectional view of the main part of the conventional example, and FIG. 5 is a diagram illustrating the safety range of use of the conventional product and the product of the present invention based on the load and the temperature inside the open refrigerator. 1...roller, 2...turntable, 7...
... Heating chamber, 17 ... Heating chamber bottom, 24.
...Rolling. Name of agent: Patent attorney Toshio Nakao, 1st person, 2nd person
Figure 3 Figure 4

Claims (1)

[Claims] It has a heating chamber that accommodates an object to be heated, a heating source that heats the object to be heated in the heating chamber, a rotary table that rotatably supports the object to be heated in the heating chamber, and a drive means that rotationally drives the rotary table. and a high-frequency heating device in which a compression-molded roller, at least one of which is provided between a metal rotary table and a bottom surface of the heating chamber and rotatably supports the rotary table, is made of a heat-resistant fluororesin subjected to firing treatment.