Dental furnace as well as method for operating a dental furnace

Abstract

A dental furnace having closed or closeable firing chamber (12), which is surrounded by thermal insulation (20) and which comprises at least one inlet terminal (22) and at least one outlet terminal (24). Via said two terminals, a gas, especially air, may be passed through the firing chamber (12) and/or may be discharged from the firing chamber (12), wherein a vacuum source (44) is provided, which is in direct or indirect communication with the outlet terminal (24) and via which the outlet terminal (24) may be set under vacuum pressure. At the outlet terminal (24), an especially T-shaped or Y-shaped connector (26) is attached. The connector (26) comprises two entrance ports (32, 24) and an exit (40), wherein the exit (40) is in communication with the vacuum source (44) and a first entrance port is in communication with the firing chamber (12), and especially is flange-mounted at the outlet terminal (24) thereof, and a second entrance port (34) is in communication with ambient air.

Claims

1. A dental furnace comprising a closed or closable firing chamber, which is surrounded by thermal insulation, at least one inlet terminal and at least one outlet terminal, through both of which a gas is passed through the firing chamber and/or us evacuated through the firing chamber, a vacuum source in direct or indirect communication with the at least one outlet terminal and by which the at least one outlet terminal is depressurized, wherein at the at least one outlet terminal a T-shaped or Y-shaped connecter is directly attached, wherein the connector comprises two entrance ports and one exit wherein the exit is in communication which the vacuum source, and a first entrance port is in communication with the firing chamber and a second entrance port is in communication with the ambient air.

2. The dental furnace according to claim 1, wherein the gas comprises air and the first entrance port is flange-mounted to the at least one outlet terminal.

3. The dental furnace according to claim 1, wherein the second entrance port of the connector is connected to a first air line having a flow resistor.

4. The dental furnace according to claim 3, wherein the flow resistor comprises a valve.

5. The dental furnace according to claim 1, wherein the at least one inlet terminal and the at least one outlet terminal are arranged opposite to each other on the firing chamber of the dental furnace, such that at least one part of the firing chamber extends there between.

6. The dental furnace according to claim 3, wherein the at least one inlet terminal is connected to a second air line which comprises a valve and/or a filter.

7. The dental furnace according to claim 3, wherein a suction line extends between the connector and the vacuum source, enabling heat exchange between the ambient air of the first air line and the aspirated air passing through the suction line due to the material used for the suction line.

8. The dental furnace according to claim 7, wherein the suction line comprises a heat exchanger, which is also connected to the first air line of the entrance port of the dental furnace.

9. The dental furnace according to claim 8, wherein the heat exchanger is provided with a bypass line located on the suction line, which bypass line is provided with a switching valve.

10. The dental furnace according to claim 1, wherein the connector is fabricated of a thermally conductive material, and wherein the connector near the second entrance port is provided with a connecting piece predetermined length.

11. The dental furnace according to claim 10, wherein the thermally conductive material comprises metal, and wherein the predetermined length equals 10 cm in length.

12. The dental furnace according to claim 10, wherein the connector comprises cooling ribs.

13. The dental furnace according to claim 1, wherein the fresh air line supplying fresh air to the second entrance port of the connector, is connected to external heat sources of the dental furnace and wherein the fresh air supplied cooling air to the external heat sources for cooling and evacuation of hot air.

14. The dental furnace according to claim 13, wherein the external heat sources of the dental furnace comprise power electronics.

15. The dental furnace according to claim 1, wherein at least two inlet terminals for supplying fresh air to the firing chamber are provided, which are arranged spaced apart from each other and are located opposite of the at least one outlet terminal.

16. A method for operating a dental furnace, the method comprising providing the dental furnace wherein the dental furnace comprises a closed or closable firing chamber, which is surrounded by a thermal insulation, at least one inlet terminal and at least one outlet terminal, through both of which a gas is passed through the firing chamber and/or is discharged through the firing chamber, a vacuum source in direct or indirect communication with the outlet terminal and by which the outlet terminal is depressurized, wherein at the at least one outlet terminal a T-shaped or Y-shaped connector is directly attached, wherein the connector comprises two entrance ports, and a first entrance is in communication with the firing chamber and a second entrance port is in communication with ambient air, evacuating gas from the firing chamber using vacuum pressure via the at least one outlet terminal prior to starting the heat treatment process, performing the heat treatment process in an evacuated state, and supplying the firing chamber with ambient air at a predetermined temperature via an inlet terminal.

17. The method according to claim 16, comprising starting from a predetermined temperature during cool down or at any other point of time during the heat treatment process, continuously aspirating ambient air through the firing chamber by intervention of the vacuum source.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other embodiments of the invention will now be described in more detail with reference to the attached drawing, which show embodiments of the invention.

(2) FIG. 1 shows a schematic assembly of different lines and circuit elements of a dental furnace according to the invention.

(3) FIG. 2 shows a schematic assembly of different lines and circuit elements of a dental furnace according to the invention.

(4) FIG. 3a shows schematically a longitudinal section of a T-shaped connector according to the invention.

(5) FIG. 3b shows schematically a longitudinal section of a Y-shaped connector according to the invention.

(6) FIG. 4 shows a schematic assembly of different lines and circuit elements of a dental furnace according to the invention.

(7) FIG. 5 shows a schematic assembly of different lines and circuit elements of a dental furnace according to the invention.

DETAILED DESCRIPTION

(8) The dental furnace 10 schematically represented in the FIG. 1 comprises a firing chamber or a firing cavity 12, which is formed in a furnace head 14. The furnace head 14 closes at a separation plane 16 opposite a furnace bottom part 18.

(9) In a manner known per se, the furnace head 14 comprises heating elements, annularly extending around the essentially cylindrical firing chamber 12. Both the furnace head 14 and the furnace bottom part 18 are provided with thermal insulating material 20, which for example may be formed as a fireclay, and is open-pored, so that it allows passing there through.

(10) According to the invention, the dental furnace 10 is provided with an inlet terminal 22 for supplying ambient air, which may also be referred to as fresh air, as well as an outlet terminal 24, at which a connector 26 is attached.

(11) The connector 26 is directly flange-mounted to the housing wall 30 of the furnace head 14. It comprises an entrance port 32, which is in flow communication with the thermal open pore insulating material 20. Moreover, it comprises a second entrance port 34, which is in communication with ambient air via a first air line 36.

(12) Furthermore, the connector 26 comprises an exit 40, which is in flow communication with a suction line 42.

(13) In the represented working example both the first air line 36 and the suction line 42 extend in the region of the furnace head 14 and from there extends downwards, i.e. towards the region of the furnace bottom part 18, and eventually extends laterally apart therefrom.

(14) The suction line 42 extends towards a vacuum source 44, which preferably is formed as a suction pump 44, and the exhaust air thereof is preferably passed below the space, where the dental furnace is located.

(15) The inlet terminal 22 is in communication with a second air line 46.

(16) The first air line 36 is provided with a bypass valve 48, which is in communication with a filter and/or sound absorber 50 with the ambient air.

(17) Similarly, the second air line 46 is provided with a second valve 54, which is in communication with a second filter and/or sound absorber 56 with the ambient air.

(18) In the working example represented, a vacuum pressure sensor 60 is provided, which, via a branch line 62, is in communication with the interior of the dental furnace 10. In this way, the existing vacuum pressure in the firing chamber 12 is allowed to be acquired and is used for controlling both valves 48 and 54 and the suction pump 44.

(19) For performing a heat treatment process, in the working example represented herein, the bypass valve 48 and the second valve 54 are initially closed and the suction pump 44 is turned on.

(20) Alternatively, the second valve 54 for a short time may be maintained in the opened position, to safely remove any residual gases of the last heat treatment process.

(21) Following this, the heat treatment process is started, in which the heater not represented herein for the firing chamber 12 is turned on. This is done under vacuum pressure, and the vacuum pressure will be maintained following operation of the suction pump 44 during that time, so that any small leakages will not reduce the vacuum pressure.

(22) If the temperature for the next section of the heat treatment process is to be lowered, the suction pump 44 will be turned on and the valve 54 will be opened. In this way, the firing chamber 12 is flushed with fresh air and it is possible to provide rapid cool down, if required. The suction pump 44 may also be turned on to be timed, if cool down is to be less rapid.

(23) In any case, this method is more advantageous than to open the firing chamber at the separation line 16, after otherwise cool air has always been supplied abruptly.

(24) In a modified method, the bypass valve 48 is also opened, at least partially, during operation of the suction pump 44. In this way, the level of the vacuum pressures, which is measured by the vacuum pressure sensor 60, is allowed to be controlled.

(25) In another modified embodiment, shown in FIG. 4, the suction line 42 and the second air line 46 are positioned to be close to each other and to provide a heat exchanger 72 there between. In this way, hot furnace air exiting the exit 44 is allowed to be thermally recycled and to be fed into the air line 46, which is especially favorable during heating up.

(26) The heat exchanger, if required, may also be provided with an additional bypass line at the entrance side and/or at the exit side, which in turn may comprise a valve. By the valve, the respective side of the heat exchanger will quasi be closed, so that the heat exchange effect will be omitted, as it is especially beneficially during cool down and supply of cold fresh air.

(27) The dental furnace according to the invention may also be formed as a sintering furnace. According to the invention, the exhaust air generated therein may excellently be dissipated with the suction pump 44 according to the invention and the associated valves.

(28) According to FIG. 2, two inlet terminals 22, 23 for supplying fresh air to the firing chamber 12 are provided. They are arranged spaced apart from each other and are located opposite of two outlet terminals 24, 25 which are joined at the connector 26.

(29) In addition, the suction line 42 comprises a heat exchanger 70 which is also connected to the air line 36 of the entrance port 34 of the dental furnace 10.

(30) According to FIG. 3a and FIG. 3b, a T-shaped or Y-shaped connector 26 is provided.

(31) It comprises an entrance port 32 which is in flow communication with the thermal open pore insulating material 20. Moreover, the connector 26 comprises a second entrance port 34 which is in communication with ambient air via a first air line 36.

(32) Furthermore, the connector 26 comprises an exit 40 which is in flow communication with a suction line 42.

(33) According to FIG. 5, the heat exchanger 70 is provided with a bypass line 88, which is provided with a switching valve 90 between the bypass line 88 and the heat exchanger 70. The connector 26 has an enlarged surface 80 having cooling ribs 82 A fresh air line 36 supplies fresh air to the second entrance port 34 of the connector 26 and is connected to an external heat source 84. The fresh air supplies cooling air to the external heat source 84. The external heat sources 84 of the dental furnace 10 comprise power electronics 86.

(34) Although the present invention has been described in connection with preferred embodiments thereof, it will be appreciated by those skilled in the art that additions, deletions, modifications, and substitutions not specifically described may be made without departing from the spirit and scope of the invention as defined in the appended claims.