JPS606431Y2 - Firing furnace for porcelain teeth - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a firing furnace used when forming a porcelain tooth by baking a dental porcelain material onto a dental crown base metal material.

Conventionally, a firing furnace shown in FIG. 1 has been used for forming porcelain teeth.

The firing furnace 21 shown in FIG. 1 has a cylindrical furnace body 2 with one end closed and the other end facing downward.
2, a porcelain tooth holder 23 located at the lower end opening of the furnace body 22, and a mechanism for moving the porcelain tooth holder 23 up and down, and a heater 24 is wound and buried along the inner surface of the peripheral wall of the furnace body 22. A temperature sensing element 25 such as a thermocouple is passed through the upper end closing wall of the furnace body 22, and its tip is connected to the furnace body 22.
It was designed to be faced within.

However, in this firing furnace 21, when a plurality of units are placed on the porcelain tooth holder 23 and these units are fired, the distance between each unit and the heater 24 becomes uneven, so the temperature of each unit becomes uneven. This may cause uneven baking.

Furthermore, when firing the bridge, the temperature of each part of the bridge becomes non-uniform, which sometimes results in uneven firing.

Furthermore, dental porcelain is generally fired by repeating the coating process and heating process two or more times, but since the temperature of the porcelain becomes quite low during the coating process, after the coating process is finished,
When the porcelain tooth holder 23 is raised and positioned at the lower end opening of the furnace body 22 to heat the porcelain tooth, the temperature difference between the temperature of the porcelain tooth and the temperature detected by the temperature detection element 25 increases. , firing defects may occur.

The purpose of this invention is to provide a firing furnace for porcelain teeth that can solve the above problems all at once.

Hereinafter, embodiments of this invention will be described with reference to the drawings.

In FIG. 2, the porcelain firing furnace 1 according to this invention includes a cylindrical furnace body 2 whose upper end is closed and whose lower end is open.
It consists of a porcelain tooth holder 3 which is positioned at the lower end opening of the furnace body 2 and is movable up and down.

A heater 4 is embedded in the inner surface of the upper end closing wall 2a of the furnace body 2.

Further, a temperature sensing element 5 such as a thermocouple is passed through the upper end closing wall 2a of the furnace body 2 from above, and the tip thereof is inserted into the upper end of the closing wall 2a of the furnace body 2.
This temperature sensing element 5 detects the temperature near the closing wall 2a inside the furnace body 2.

The upper surface of the porcelain tooth holder 3 is a porcelain tooth placement surface 3a, and a heater 6 is embedded in this placement surface 3a.

This porcelain tooth arrangement surface 3a faces into the furnace body 2 and faces the inner surface of the upper end closing wall 2a of the furnace body 2.

Further, a heat equalizing plate 7 made of an opaque quartz plate or the like is placed on the porcelain tooth placement surface 3a, and a porcelain tooth support 8 having a protrusion 8a provided on the upper surface is further placed on this heat equalizing plate 7. , the porcelain tooth S to be fired is placed over the protrusion 8a of the support 8.

The shape of the support 8 can be changed as appropriate depending on the shape of the porcelain tooth S, that is, whether it is premature death or a bridge.

The heat equalizing plate 7 has the property of equalizing the temperature of a portion immediately above the heater wires and a portion corresponding to the portion above between the heater wires.

Further, a lid plate 9 larger than the lower end opening of the furnace body 2 is attached to the lower surface of the porcelain tooth holder 3.

A gasket 10 is attached to the upper peripheral edge of the cover plate 9, and when the porcelain tooth holder 3 is positioned at the lower end opening of the furnace body 2, that is, in the raised position of the porcelain tooth holder 3, the gasket 10 is attached to the upper peripheral edge of the lid plate 9. The lid plate 9 contacts the lower peripheral edge of the furnace body 2 and keeps the inside of the furnace body 2 airtight.

Further, the porcelain tooth holder 3 is lowered and raised from the lower end opening of the furnace body 2 to the original position shown in FIG. In other words, it returns to the raised position.

Furthermore, a temperature sensing element 12 such as a thermocouple is connected to the cylinder 11.
It penetrates through the cover plate 9 and is inserted into the upper and lower through holes 13 made in the center of the porcelain tooth holder 3, and its tip is positioned slightly below the porcelain tooth placement surface 3a. The temperature near the arrangement surface 3a is detected by the sensing element 12.

However, when controlling the two heaters 4 and 6 at a constant power ratio, the lower temperature sensing element 12 is not necessary.
The upper temperature sensing element 5 alone is sufficient.

The temperature of the heater 4 provided in the furnace body 2 and the heater 6 provided in the porcelain tooth holder 3 is controlled separately.

A method of baking a dental porcelain made of crystallized glass onto a cast crown made of a baking alloy using such a baking furnace 1 is as follows.

First, the temperature detected by the temperature detection elements 5 and 12 is 60
A current is passed through both heaters 4 and 6 so that the temperature is 0 to 800°C.

Then, the porcelain tooth S to be fired, which is made by applying porcelain material mixed with water to the cast crown, is vibrated to condense the porcelain material, and the porcelain tooth holder 3 is lowered to support the plurality of porcelain teeth S to be fired. After it is fitted onto the protrusion 8a of the tool 8, it is left to stand for a predetermined period of time to evaporate the moisture in the applied porcelain (pre-drying step).

Next, the holding table 3 is raised and positioned at the lower end opening of the furnace body 2, the inside of the furnace body 2 is made airtight with the cover plate 9, and the pressure inside the furnace body 2 is reduced to 60~60℃ using a vacuum pump (as shown). 7
Reduce the pressure to about 6 mmHg.

Then, the porcelain tooth S to be fired is heated by both heaters 4.6 at a rate of 30 to 50 degrees Celsius per minute until the temperatures detected by the temperature detection elements 5 and 12 are respectively 950 to 1100 degrees Celsius (firing process).

In the heating process, the temperature detected by the lower temperature detection element 12 and the temperature detected by the upper temperature detection element 5 are controlled separately by the computer, temperature control device, etc. of both heaters 4 and 6. When properly adjusted, each porcelain tooth S to be fired is heated with a uniform temperature distribution.

After the firing process is completed, the vacuum state in the furnace body 2 is released and the holding table 3 is lowered.

The holding table 3 may be lowered immediately after the vacuum state is released, or
Alternatively, it may be held in the raised position for a required period of time after the vacuum state is released, and then lowered.

After lowering the holding table 3, the temperature was lowered so that the temperatures detected by the temperature detection elements 5 and 12 were respectively 600 to 800°C, and the porcelain tooth S to be fired was lowered from the holding table 3 and cooled. After that, apply porcelain again.

At this time, both heaters 4 are adjusted so that the temperature detected by the same temperature detection element 5゜12 is 600 to 800℃.
, 6 are controlled.

After completing the second coating operation, the above pre-drying step and baking step are repeated.

Firing of the porcelain tooth S to be fired is completed by repeating such a series of steps a required number of times.

The above example shows the case where porcelain made of crystallized glass is baked onto a cast crown made of a baking alloy, but the device based on this invention can also be used when baking other ceramics onto a cast crown. be done.

In this case, conditions such as drying temperature, heating temperature, heating rate, etc. are changed as appropriate in consideration of the type of metal, the type of porcelain, etc.

In the above embodiment, the furnace body 2 and the porcelain tooth holder 3 are arranged vertically, but they may be arranged laterally.

Further, in the above embodiment, the furnace body 2 and the porcelain tooth holder 3 are moved away from each other by moving the porcelain tooth holder 3 up and down, but the furnace body 2 may be moved up and down. You may move your hips or both up and down, respectively.

As described above, the porcelain tooth firing furnace 1 according to this invention includes a cylindrical furnace body 2 with one end closed, and a wall 2a that closes one end of the furnace body 2 and is located at the opening at the other end of the furnace body 2. A porcelain tooth holder 3 having a porcelain tooth placement surface 3a facing the inner surface, and at least one of the furnace body 2 and the porcelain tooth holder 3 are separated from the other and returned to their original positions. Since the heaters 4 and 6 are provided only on the inner surface of the closing wall 2a and the porcelain tooth arrangement surface 3a of the furnace body 2, the temperature of which can be controlled separately, can be fired. The distance between all porcelain teeth and the upper heater 4 or lower heater 6 in the case of firing, and the distance between each part of the porcelain tooth and the upper heater 4 or the lower heater 6 in the case of firing a bridge-shaped porcelain tooth are uniform, and both In this case, the temperature distribution of the porcelain tooth becomes even.

Therefore, it is possible to prevent uneven heating from occurring on the porcelain tooth.

In addition, since the heater 6 is provided on the porcelain tooth placement surface 3a of the porcelain tooth holder 3, even during the work of applying dental porcelain to the metal that is the base of the porcelain tooth, the heater 6 is activated by the porcelain tooth placement surface 3a.
It becomes possible to heat the vicinity to a required temperature.

Therefore, since the porcelain tooth can be heated to the required temperature in the subsequent pre-drying process, it is possible to accurately and quickly heat the porcelain tooth to the firing temperature in the heating process after the pre-drying process, which prevents uneven firing of the porcelain tooth. This can be prevented from occurring.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view showing a conventional firing furnace, and FIG. 2 is a vertical cross-sectional view showing an embodiment of this invention. 1... Firing furnace for porcelain teeth, 2... Furnace body,
2a...Closing wall, 3...Porcelain tooth holder,
3a...Porcelain tooth placement surface, 4,6...Heater.

Claims (1)

[Scope of utility model registration request] A porcelain tooth holder comprising a cylindrical furnace body 2 with one end closed, and a porcelain tooth placement surface 3a positioned at the opening at the other end of the furnace body 2 and facing the inner surface of the one end closing wall 2a of the furnace body 2. 3 and
It consists of a mechanism that separates at least one of the furnace body 2 and the porcelain tooth holder 3 from the other and returns it to its original position, and the inner surface of the closing wall 2a and the porcelain tooth placement surface 3a of the furnace body 2 A firing furnace for porcelain teeth that is equipped with heaters 4 and 6 whose temperature can be controlled separately.