JPH051020B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention is directed to a dental firing furnace for firing small components such as dentures to be fired in a vacuum or in the atmosphere.

<Prior Art> Conventional firing furnaces of this type include those shown in FIGS. 5 and 6. This firing furnace has a base 1
It consists of a firing table 2 provided at a fixed position above, and a furnace body 3 provided above the firing table 2 so as to be movable up and down. The firing table 2 is a table on which a porcelain tooth or a denture (hereinafter referred to as a porcelain tooth) such as an original cast body to become a porcelain tooth is placed. The furnace body 3 has an internal space 4 that opens downward, and has a built-in heater (not shown) that raises the temperature of the internal space 4.
The lower edge of the stage 5 is in close contact with the edge of the stage 5 on which the baking table 2 is placed, via a seal rubber 6, so that it is shut off from the outside air and the interior is kept airtight. In addition, apart from the one shown in the figure, the furnace body is installed in a fixed position, and the firing table is moved up and down, so that when the firing table is raised, the periphery of the stage comes into close contact with the lower edge of the furnace body through the seal rubber. There are also structures that maintain airtightness.

Although detailed explanations are omitted, such firing furnaces perform extremely labor-intensive firing processes such as disk-scanning, firing of metal conditioners, firing of opaque porcelain, firing of crown-colored porcelain, and glazing. . The firing process is a complex process that involves maintaining the material at a specified temperature for a specified period of time, slowly cooling it after heating, and pre-drying. For this purpose, although not shown, a control unit is provided, and the operation of the electric heater in the furnace body 3, the raising and lowering of the furnace body 3, the supply and exhaust of the interior space 4, etc. are performed according to a predetermined program inputted. One firing process is automatically performed, from placing the object on the firing table, firing it, and taking it out. Normally, a program allows you to enter a number of settings and select and use them for each firing.

An example of a series of steps until the completion of porcelain tooth firing is as follows.

(1) Call up the necessary programs that have been set and inputted in advance, place the porcelain tooth 7 coated with porcelain on the firing table 2, and turn on the start switch.

(2) The furnace body 3 is lowered to a drying position determined at an appropriate position above the baking table 2.

(3) Adjust the internal temperature of the furnace body to an appropriate temperature (generally 600
~700°C) and dry for 1 to several minutes. At this time, the temperature of the porcelain tooth 7 on the firing table 2 becomes 150 to 200°C.

(4) Next, a drying process is performed in which the furnace body 3 is gradually lowered while maintaining the temperature of the internal space 4 at 600 to 700°C, usually over a period of several minutes.

(5) After the furnace body has completely cooled down, the temperature of the internal space 4 is increased at a rate of 30 to 100 degrees Celsius per minute, and the temperature of the porcelain tooth is heated to a temperature range of 950 to 1100 degrees Celsius over several minutes. .

(6) While heating the porcelain tooth in 5 above or at 950-1100℃
When the temperature range reaches , the internal space 4 kept in an airtight state is reduced to a vacuum of -55 to -76 cmHg (gauge pressure) by a vacuum pump. 8 in the figure is an exhaust port. Note that in some cases, it may not be evacuated. The porcelain tooth 7 is heated for 2 to 10 minutes in this vacuum state or in the atmosphere. This heating is essentially baking.

(7) Next, the furnace body 3 is raised rapidly, the porcelain tooth is taken out from the firing table, placed on another porcelain coating work table, and porcelain is applied again to the porcelain tooth. During this time, the furnace body 3 is at the highest position, and the firing table 2 is heated.

(8) After firing in step 6 and before step 7, depending on the type of porcelain material and firing method, a step of slowly cooling the porcelain tooth may be inserted. In that case, while maintaining the temperature of the internal space 4 at 500 to 700℃,
Once the furnace body 3 is raised to its highest position and the porcelain teeth on the firing table are exposed to the atmosphere, the furnace body 3 is lowered again to close completely and reach a predetermined temperature (generally 500
~700℃) and then gradually cooled.

(9) After step 7 above, the input means calls up a preset and input program, and the same process as described above is usually repeated several times to complete the firing of the porcelain tooth.

Depending on the type of porcelain tooth or the difference in firing method, step (7) may be omitted in steps (1) to (9), and the furnace body 3 may be raised after steps (6) and (8) for firing. In some cases, it may be completed only once.

5 and 6, 9 is a viewing window, 10 is a column, 11 is a guide rail, 12 is a tray, and 13 is a
is cushion rubber.

<Problems to be Solved by the Invention> The conventional firing furnace described above, which is composed of one firing table and one corresponding furnace body, has the following problems.

When it comes to the composition of dental porcelain, it is common knowledge that it should be quickly cooled down to room temperature after firing. This is a necessary consideration to avoid leaving large distortions due to expansion and contraction between the two. However, in conventional dental firing furnaces, when taking out the fired product from the furnace body after the dental porcelain has been fired,
The furnace body is fully opened directly above the firing table, and the residual heat from the furnace body is applied to the fired products and the firing table directly below the furnace body, so radiant heat cannot be avoided as it is. Therefore, the fired product had to be manually transferred from the firing table to another work space immediately after the furnace body and firing table were opened.

In addition, dental porcelain build-up products are in a wet state in the unfired state, and as a step before firing,
Gradual drying was carried out on a firing table using the radiant heat of the furnace, but the firing table needed to be sufficiently cooled to prevent the built-up product from bursting due to sudden heating. That is, the firing table is in a high temperature state immediately after taking out the fired product. It takes time to cool it down, and there is an inconvenience that the next fired product cannot be dried immediately after the previous firing is completed.

<Means for Solving the Problems> The means of the present invention includes a plurality of firing tables on which objects to be fired are placed, and a furnace body opened downward and formed in a size that can cover any of the firing tables. and a state in which any one of the plurality of firing tables provided for one or both of the plurality of firing tables and the furnace body is selected and located directly below the furnace body, and the selected one firing table. It is characterized by comprising a moving device configured to be able to change the state in which the furnace body covers the furnace body.

<Function> The basic firing cycle of the dental firing furnace equipped with the above means is roughly as follows. That is,
An object to be fired is placed on one of the firing tables, and the firing table is moved by a moving device so that it is positioned directly below the furnace body. In order to move on to the actual firing process after the drying and preheating steps, the furnace body and firing table are appropriately moved by a moving device in a direction toward each other, so that the furnace body covers the firing table. Between this drying and preheating step and the firing step, the object to be fired next is placed on another firing table and kept in a standby state. When the firing of the material to be fired on the firing table covered with the furnace body is completed, the firing table and the furnace body are moved vertically away from each other by a moving device, and the firing table in a standby state is moved away from the furnace by the moving device. The firing table, on which the fired products are placed, is moved to a position away from directly under the furnace body. In this state, the object to be fired on the firing table located directly below the furnace body is dried and preheated by the radiant heat of the furnace body, and the object to be fired on the firing table located outside the furnace body is The fired product is cooled at room temperature without receiving radiant heat from the furnace body. Therefore, the fired product should be cooled immediately as it is, and replaced with another fired product at an appropriate time after cooling to room temperature, or if the same fired product is to be coated with porcelain and refired, it should be replaced. Apply it and leave it on standby. During this time, the material to be fired on the component table located directly below the furnace body is dried and preheated, and is then substantially fired.

In such a firing cycle, the handling of the objects to be fired can be automated, except for the work of placing the objects on standby on the firing table and the work of taking out the cooled fired products from the firing table. In addition, this manual work requires time.

<Example> A first example will be described using FIGS. 1 to 4. In the figure, 20a and 20b are baking tables, 21
2 is a furnace body, and 22 is a moving device.

The two firing tables 20a and 20b are of the same size and are placed at fixed positions on the base 24 with an interval between them. Baking table 20a, 20
Each of stages b is similar to the second firing stage in the conventional firing furnace shown in FIGS. 5 and 6, and stage 25
a, 25b. In the figure, 26 is a seal rubber, 27 is a cushion rubber, 28 is a tray,
29a and 29b are porcelain teeth to be fired.

The furnace body 21 is formed in a size that can cover one of the firing tables 20a and 20b, and is open downward, and is similar to the conventional furnace body 3 described above.
In the figure, 30 is an internal space of the furnace body 21, 31 is a quick exhaust port, and 32 is a bundle of hoses, electric wires, etc.

In this embodiment, the moving device 22 is composed of an elevating moving device 33 and a horizontal moving device 34. The lifting device 33 moves the furnace body 21 up and down, and supports the furnace body 21 on the pillar 35 so as to move up and down along a guide rail 36 provided on a pillar 35 that stands up from the base 24. A feed screw provided on the furnace body 21 is screwed into a nut provided on the furnace body 21 side, and the feed screw is rotationally driven by an electric motor. The horizontal movement device 34 horizontally moves the support 35 provided at the lower part of the support 35 together with the furnace body 21. A guide for guiding the support 35 in the horizontal direction is provided on the base 24, and the guide and A feed screw is provided in parallel on the base 24, and a nut screwed onto the feed screw is coupled to a column 35, and the feed screw is rotationally driven by an electric motor. In the figure, 37 is a bellows provided as a dustproof cover.

In addition, although not shown, the control unit is located on the base 2.
4, and the base 2 serves as its operating section.
Numeric keypad, power switch,
A display device is provided, and in addition to controlling the temperature, air supply/exhaust, and the operating time of each part in accordance with the inputted program as in the past, the operation of the moving device 22 and the operating time are also controlled. It's becoming more and more beautiful.

In the dental firing furnace configured in this way, several programs for a series of steps are set and input in advance, and the necessary ones are called up and used. For example, the operation is as follows.

(a) When the porcelain tooth 20a coated with porcelain is placed on the firing table 20a and the program is specified and started from the state shown in FIG.
The porcelain tooth 29a is lowered by the furnace body 21, and the porcelain tooth 29a is heated by the heater in the furnace body 21, and the steps of preheating, drying, and firing are performed. During this time, the height position of the furnace body 21 is sequentially changed by controlling the lifting device 33 according to the program. Until the firing of the porcelain tooth 29a is completed, the operator places the porcelain tooth 29b coated with porcelain material on the firing table 20b and leaves it in a standby state, and also specifies a necessary program for the porcelain tooth 29b.

(b) When the firing of the porcelain tooth 29a is completed, the furnace body 21 is raised to the top by the lifting device 33, and then the furnace body 21 is moved together with the pillar 35 by the horizontal movement device to be directly above the firing table 20b. To position. Then, the furnace body 21 descends according to the program and fires the porcelain tooth 29b. The road body 21 is the baking table 20b
By moving upward, the porcelain tooth 29a is attached to the furnace body 2.
1, and is quickly cooled to room temperature. While the porcelain tooth 13 is being fired, the firing table 20a is placed in a standby state and a program necessary for firing is specified.

(c) When the firing of the porcelain tooth 29b is completed, the furnace body 21 moves to the firing table 20a side, and the object to be fired thereon is fired in accordance with the designated program.

In the first embodiment, there are two firing tables, but as the case may be, three or more firing tables may be provided and a furnace body may be appropriately combined with each of them for firing.

Further, in the first embodiment, the moving device was configured so that the furnace body moved up and down and moved horizontally, but the furnace body moved up and down in a fixed position and each firing table moved horizontally together with one base. The horizontal movement is not limited to being along a straight line, but may be a configuration in which the device rotates on a horizontal plane. For example, by rotating one base supporting the firing table, the firing table below the furnace body can be replaced. Further, the furnace body may be fixed in a fixed position so that the base can also move up and down. Furthermore, both the firing table and the furnace body may be able to move up and down as well as horizontally.

<Effects of the Invention> Since the dental firing furnace of the present invention uses one furnace body in combination with each of a plurality of firing tables using a moving device, it is possible to use a firing table that is not used in combination with the furnace body. The object to be fired next can be placed on the standby, and after completion of firing on one firing table, firing can be started on another firing table. Therefore, the firing platform supporting the fired product is immediately removed from directly below the furnace body, and the fired product can be cooled effectively without the operator having to operate the fired product immediately after completion of firing. Therefore, the efficiency of firing is greatly improved, and the time when the worker takes out the fired product from the firing table and replaces it with another object to be fired can be more flexible, allowing him to concentrate on other porcelain coating work, etc. It's also effective. This has the great effect of automating the continuous operation from the completion of firing of the object to be fired to the start of the next firing, which was conventionally performed by an operator.

[Brief explanation of the drawing]

Fig. 1 is a front view of an embodiment of the invention, Fig. 2 is a plan view of the embodiment, Fig. 3 is a right side view of the embodiment, Fig. 4 is a rear view of the embodiment, and Fig. 5. 6 is a front view showing an example of a conventional dental firing furnace, and FIG. 6 is a right side view of the same conventional example. 20a, 20... Baking table, 21... Furnace body, 22
...Movement device, 29a, 29b...Object to be fired (porcelain tooth).

Claims (1)

[Claims] 1. A plurality of firing tables on which objects to be fired are placed, a furnace body that opens downward and is formed in a size that can cover any of the firing tables, and one or both of the plurality of firing tables and the furnace body. It is configured such that any one of the plurality of firing tables provided for the furnace can be selected and moved between a state where it is located directly under the furnace body and a state where the selected one firing table is covered by the furnace body. A dental firing furnace characterized by comprising a moving device.