A thermocouple for vacuum furnace capable of preventing contamination of the thermocouple wire

Abstract

The invention discloses a thermocouple for a vacuum furnace capable of preventing contamination of a thermocouple wire, belonging to the technical field of thermocouples. The thermocouple comprises a corundum insulating tube, a junction box is fixedly installed on the top of the corundum insulating tube, a thermocouple wire is fixedly installed on the bottom of the junction box, the bottom of the thermocouple wire extends to the inner cavity of the corundum insulating tube, and a quartz tube is sleeved on the outside of the corundum insulating tube. The invention adds a molybdenum tube to a tungsten-rhenium thermocouple, prolongs the service life of the thermocouple by 50% at a high temperature section of 1300°C, manufactures an armored thermocouple, and prolongs the service life of the thermocouple when used in a non-vacuum environment, and stabilizes the temperature measurement accuracy. When the thermocouple is used in a vacuum furnace containing hydrogen atmosphere, argon is injected into the gas-filled space, so that the tungsten-rhenium thermocouple wire is better protected, the measurement accuracy is improved, and the service life is prolonged. By using the device, the problem of contamination of the thermocouple wire of the tungsten-rhenium thermocouple at 1000°C-1300°C in a vacuum high temperature environment is solved to a certain extent.

Description

Technical Field

[0001] The invention relates to the technical field of thermocouples, in particular to a thermocouple for a vacuum furnace which can prevent contamination of a thermocouple wire. Background Art

[0002] Thermocouple is a commonly used temperature measuring element in temperature measuring instruments. It directly measures temperature and converts temperature signals into thermoelectric potential signals, which are then converted into the temperature of the measured medium through electrical instruments (secondary instruments). The appearance of various thermocouples is often very different due to needs, but their basic structure is roughly the same. They are usually composed of main parts such as hot electrodes, insulating sleeve protection tubes and junction boxes. They are usually used in conjunction with display instruments, recording instruments and electronic regulators. There are three existing technologies for industrial S-type, B-type platinum-rhodium, and tungsten-rhenium thermocouples: first, rare earth elements are added to the thermocouple wire to extend the service life of the thermocouple; second, coating is applied to the S-type, B-type platinum-rhodium, and thermocouple wires; third, the tungsten-rhenium thermocouple protection tube uses a high-temperature resistant alloy tube such as a molybdenum tube, a high-temperature alloy tube, etc.

[0003] The above-mentioned thermocouples have a protective function to a certain extent, but they do not play a protective role in a vacuum environment. The S-type, B-type platinum-rhodium, and tungsten-rhenium thermocouple wires are easily contaminated, which affects the service life and temperature measurement accuracy. Therefore, we need to propose a vacuum furnace thermocouple that can prevent wire contamination. Summary of the invention

[0004] The object of the present invention is to provide a thermocouple for a vacuum furnace which can prevent contamination of the thermocouple wire and has the advantages of extended service life and stable temperature measurement accuracy, so as to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides a thermocouple for a vacuum furnace that can prevent contamination of the thermocouple wire, comprising a corundum insulating tube, a junction box is fixedly installed on the top of the corundum insulating tube, a thermocouple wire is fixedly installed on the bottom of the junction box, the bottom of the thermocouple wire extends to the inner cavity of the corundum insulating tube, a quartz tube is sleeved on the outside of the corundum insulating tube, the top of the quartz tube and the bottom of the junction box are fixedly installed, the quartz tube is arranged in double layers, and an inflation space is formed between the two layers of the quartz tubes, the inner cavity of the inflation space is filled with argon, a molybdenum tube is sleeved on the outside of the quartz tube, the top of the molybdenum tube and the bottom of the junction box are fixedly installed, the inner cavity of the junction box is threadedly connected with a head, and an inflation component is arranged inside the head.

[0006] Preferably, the inflation component comprises a fixing seat embedded in the surface of the head, and an inflation airway is opened inside the fixing seat.

[0007] Preferably, an air valve is fixedly mounted on the top of the fixing seat, and the bottom of the air valve is communicated with the top of the inflation airway.

[0008] Preferably, the air valve is a screw-on air valve, and a protective cover is threadedly connected to the top of the air valve.

[0009] Preferably, ventilation grooves are equidistantly formed at the bottom of the junction box, the tops of the ventilation grooves are communicated with the air charging airway, and the bottoms of the ventilation grooves are communicated with the air charging space.

[0010] Preferably, a sealing ring is fixedly mounted on the bottom of the sealing head, a sealing groove matched with the sealing ring is provided at the bottom of the inner cavity of the junction box, and the surface of the sealing ring is in contact with the inner wall of the sealing groove.

[0011] Preferably, the thermocouple wire is composed of a group of positive electrode thermocouple wire and negative electrode thermocouple wire, and one end of the positive electrode thermocouple wire and one end of the negative electrode thermocouple wire are welded together.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] The present invention adds a molybdenum tube to the tungsten-rhenium thermocouple, prolongs the service life of the thermocouple in the high temperature section of 1300°C by 50%, manufactures an armored thermocouple, and prolongs the service life of the thermocouple when used in a non-vacuum environment. When the thermocouple is used in a vacuum furnace containing hydrogen atmosphere, argon is injected into the gas-filled space, thereby better protecting the tungsten-rhenium thermocouple wire, improving the measurement accuracy, and prolonging the service life. Through the use of the device, the problem of wire contamination of the tungsten-rhenium thermocouple at 1000°C-1300°C in a vacuum high temperature environment is solved to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural schematic diagram of the present invention;

[0015] Figure 2 It is a partial front cross-sectional schematic diagram of the structure of the present invention;

[0016] Figure 3 It is a schematic diagram of the structure inside the connecting socket of the present invention;

[0017] Figure 4 It is a structural schematic diagram of the ventilation groove of the present invention;

[0018] Figure 5 For the present invention Figure 3 Enlarged view of point A in the middle.

[0019] In the figure: 1. Corundum insulating tube; 2. Junction box; 3. Thermocouple wire; 4. Quartz tube; 5. Inflatable space; 6. Molybdenum tube; 7. Head; 8. Fixed seat; 9. Inflatable airway; 10. Valve mouth; 11. Protective cover; 12. Vent groove; 13. Sealing ring. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] See also Figure 1-5 The present invention provides a thermocouple for a vacuum furnace that can prevent contamination of thermocouple wires, comprising a corundum insulating tube 1, a junction box 2 is fixedly installed on the top of the corundum insulating tube 1, a thermocouple wire 3 is fixedly installed on the bottom of the junction box 2, the thermocouple wire 3 is composed of a group of positive pole thermocouple wires and negative pole thermocouple wires, and one end of the positive pole thermocouple wire and one end of the negative pole thermocouple wire are welded together, the bottom of the thermocouple wire 3 extends to the inner cavity of the corundum insulating tube 1, the outer part of the corundum insulating tube 1 is sleeved with a quartz tube 4, the top of the quartz tube 4 is connected to the junction box 2 is fixedly installed at the bottom, the quartz tube 4 is arranged in double layers, and an air-filled space 5 is formed between the two layers of quartz tubes 4. The inner cavity of the air-filled space 5 is filled with argon gas. The outer part of the quartz tube 4 is sleeved with a molybdenum tube 6. The top of the molybdenum tube 6 is fixedly installed with the bottom of the junction box 2. The inner cavity of the junction box 2 is threadedly connected with a head 7. A sealing ring 13 is fixedly installed at the bottom of the head 7. A sealing groove adapted to the sealing ring 13 is opened at the bottom of the inner cavity of the junction box 2, and the surface of the sealing ring 13 is in contact with the inner wall of the sealing groove.

[0022] By setting the two layers of quartz tube 4, in the vacuum furnace containing hydrogen atmosphere, the rhenium thermocouple is easy to oxidize at high temperature. When in use, it is necessary to fill the gas-filled space 5 with argon, which better protects the tungsten-rhenium thermocouple wire, improves the measurement accuracy, and prolongs the service life. By setting the molybdenum tube 6, the service life in the high temperature section 1300°C is extended by 50%, and the armored thermocouple is manufactured and used in a non-vacuum environment. Its service life is extended and the temperature measurement accuracy is stable. The purity of the molybdenum tube 6 disclosed in this embodiment is greater than or equal to 9 9.95%, the surface is processed by polishing and lathing process, and has the characteristics of high melting point, high strength, long life and good high temperature resistance. The purity of the corundum insulation tube 1 is high: Al2O3>99%, good chemical corrosion resistance, good temperature resistance, long-term use at 1600℃, short-term use at 1800℃, good resistance to rapid cooling and heating, not easy to burst, high density of grouting molding, suitable for thermocouples used in vacuum furnaces, and the connection between the head 7 and the junction box 2 can be sealed by the use of the sealing ring 13 and the sealing groove;

[0023] The quartz tube 4 disclosed in this embodiment is a special industrial technical glass made of silicon dioxide, which is a very good basic material. Quartz glass has a series of excellent physical and chemical properties: good high temperature resistance and corrosion resistance, and has the advantages of good thermal stability, good light transmittance and good electrical insulation. Due to the above excellent physical and chemical properties, quartz glass is widely used in various fields such as electric light sources, semiconductors, optical communications, military industry, metallurgy, building materials, chemistry, machinery, electricity, and environmental protection;

[0024] The temperature measurement error of S-type, B-type platinum-rhodium, and tungsten-rhenium thermocouple wires is large and the accuracy is reduced after being contaminated. The main reason is that the thermocouple is in a vacuum environment. When the temperature of the production process of S-type, B-type platinum-rhodium, and tungsten-rhenium thermocouple rises to 1000°C-1300°C, the wire is easily contaminated. It is normal to use at 0-900°C. The thermocouple disclosed in this embodiment can solve the problem that the thermocouple wire is easily contaminated under high temperature conditions to a certain extent;

[0025] An inflatable component is provided inside the sealing head 7, and the inflatable component includes a fixing seat 8 embedded in the surface of the sealing head 7, an inflatable airway 9 is provided inside the fixing seat 8, a valve 10 is fixedly installed on the top of the fixing seat 8, the bottom of the valve 10 is communicated with the top of the inflatable airway 9, the valve 10 is a screw-on valve, and a protective cover 11 is threadedly connected to the top of the valve 10, and ventilation grooves 12 are equidistantly provided at the bottom of the junction box 2, the top of the ventilation grooves 12 is communicated with the inflatable airway 9, and the bottom of the ventilation grooves 12 is communicated with the inflatable space 5;

[0026] Through the setting of the valve mouth 10, the valve mouth 10 is used to inflate the inflation space 5. When the user uses a thermocouple for a vacuum furnace containing hydrogen, the user can use an external inflation pump to inject argon into the interior of the inflation airway 9 through the valve mouth 10. After the argon enters the inflation airway 9, it enters the inflation space 5 through the ventilation groove 12 and is injected into the argon, which can better protect the tungsten-rhenium thermocouple wire, improve the measurement accuracy, and extend the service life. In this embodiment, the valve mouth 10 is an independent valve body device. When opened, it allows argon to enter the interior of the inflation space 5, and then automatically closes and seals to store hydrogen and generate air pressure to prevent argon from escaping the inflation space 5. Through the setting of the protective cover 11, the valve mouth 10 can be protected to prevent the valve mouth 10 from being blocked and unable to achieve normal inflation function.

[0027] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A thermocouple for a vacuum furnace capable of preventing contamination of thermocouple wires, comprising a corundum insulating tube (1), a junction box (2) being fixedly mounted on the top of the corundum insulating tube (1), a thermocouple wire (3) being fixedly mounted on the bottom of the junction box (2), the bottom of the thermocouple wire (3) extending to the inner cavity of the corundum insulating tube (1), characterized in that: The outer part of the corundum insulating tube (1) is sleeved with a quartz tube (4), the top of the quartz tube (4) is fixedly mounted on the bottom of the junction box (2), the quartz tube (4) is arranged in a double layer, and an air-filled space (5) is formed between the two layers of the quartz tube (4), the inner cavity of the air-filled space (5) is filled with argon gas, the outer part of the quartz tube (4) is sleeved with a molybdenum tube (6), the top of the molybdenum tube (6) is fixedly mounted on the bottom of the junction box (2), and the inner cavity of the junction box (2) is threadedly connected to the outer part of the quartz tube (4). A sealing head (7) is provided, wherein an inflation component is provided inside the sealing head (7); the inflation component comprises a fixing seat (8) embedded in the surface of the sealing head (7), wherein an inflation airway (9) is provided inside the fixing seat (8); an air valve (10) is fixedly mounted on the top of the fixing seat (8), wherein the bottom of the air valve (10) is connected to the top of the inflation airway (9); the air valve (10) is a screw-on air valve, wherein a protective sleeve (11) is threadedly connected to the top of the air valve (10); The bottom of the junction box (2) is provided with ventilation grooves (12) at equal intervals, the top of the ventilation groove (12) is connected to the inflation airway (9), and the bottom of the ventilation groove (12) is connected to the inflation space (5).

2. A thermocouple for vacuum furnace capable of preventing wire contamination according to claim 1, characterized in that: A sealing ring (13) is fixedly mounted on the bottom of the sealing head (7), and a sealing groove adapted to the sealing ring (13) is provided at the bottom of the inner cavity of the junction box (2), and the surface of the sealing ring (13) is in contact with the inner wall of the sealing groove.

3. A thermocouple for vacuum furnace capable of preventing wire contamination according to claim 1, characterized in that: The thermocouple wire (3) is composed of a group of positive pole thermocouple wires and negative pole thermocouple wires, and one end of the positive pole thermocouple wire and one end of the negative pole thermocouple wire are welded together.

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