JP4060737B2 - Reduction furnace - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reduction furnace for heat-treating a long wire of refractory metal, a thin plate material or a foil-like material having a narrow width.
[0002]
[Prior art]
Conventionally, as a method of reducing the surface of a long wire of refractory metal such as molybdenum (Mo) or a thin and thin plate or foil-like material (hereinafter referred to as a workpiece), a furnace temperature of about 1000 ° C., hydrogen A heat treatment method using a gas atmosphere is employed. A batch furnace is used as the type of furnace.
[0003]
FIG. 6 is a view schematically showing a batch type reduction furnace according to the prior art. Referring to FIG. 6, in the batch type reduction furnace 100, a long linear Mo heater 104 is provided around the muffle 107 and is housed in the furnace body 101. Further, a thermocouple 103 for detecting the temperature in the furnace 101 is provided on the upper surface of the furnace body 101, and doors 108a and 108b are provided at the inlets and outlets of the work pieces at both ends. In the furnace body 101, the atmosphere necessary for reducing the Mo workpiece 102 and the atmosphere inside and outside the muffle 107 are all hydrogen gas in order to prevent oxidation of the Mo heater 104 at the reduction temperature. 110. Therefore, the doors 108a and 108b are provided at the entrance and the exit for the workpiece 102 so that the hydrogen gas 110 and the air in the furnace body 101 are not mixed and explode.
[0004]
In addition, the gas is released as indicated by reference numeral 105 in order to release the gas after the reaction. As indicated by an arrow 111, a pilot flame 106 is installed to ignite hydrogen when the work 102 is loaded and unloaded and the doors 108a and 108b are opened.
[0005]
[Problems to be solved by the invention]
However, in the conventional batch type reduction furnace described above, the atmosphere 110 of the reduction furnace 100 uses hydrogen gas. Therefore, when a workpiece is inserted and removed for the purpose of avoiding a hydrogen explosion, that is, when the doors 108a and 108b are opened. It is necessary to burn hydrogen gas at the inlet or outlet of the reduction furnace 100.
[0006]
However, since the workpiece 102 passes through the site where the hydrogen gas is burned, a quality problem occurs that the surface is oxidized.
[0007]
In addition, the workpiece 102 is usually delivered to the heat treatment process while being wound on a drum or the like. However, since the batch furnace has a limited space in the furnace, when the workpiece 102 is large, that is, the long workpiece 102 is It is necessary to cut according to the space in the furnace 100. That is, the batch type reduction furnace 100 has a problem that the long workpiece 102 cannot be heat-treated as it is.
[0008]
For this reason, when the division of the workpiece 102 is not permitted and a long product is desired, there is a problem that a large batch furnace has to be manufactured. As a result, there is a problem that the manufacturing cost is disadvantageous. .
[0009]
Also, whereas, in the temperature conditions mentioned above, Mo made of heat - but to use the data, Ru all out of the muffle 107 in order to prevent oxidation of the heater must be hydrogen atmosphere Oh.
[0010]
On the other hand, since hydrogen has a lower heat insulation effect than air, many heat insulation materials must be used. As a result, there is a problem that the size of the furnace body becomes large and the cost required for the building is also expensive. .
[0011]
Therefore, one technical problem of the present invention is that a long workpiece can be continuously reduced in a hydrogen gas atmosphere, and the workpiece can be safely opened in an open state without burning hydrogen gas at the furnace inlet and outlet. It is an object of the present invention to provide a reduction furnace having a structure that can insert and take out.
[0012]
Another technical problem of the present invention is to provide a reduction furnace having a furnace structure having a small furnace body size and a low construction cost.
[0013]
[Means for Solving the Problems]
According to the present invention, a furnace capable of performing heat treatment without oxidizing the surface of a long workpiece made of a long wire of a refractory metal, a narrow and thin plate, and a foil-like material, the furnace of the furnace Inside the body, a heater is wound around the outer surface, and an inner muffle whose both ends are open so that a workpiece to be heat-treated can pass therethrough, and an atmosphere for protecting the heater so as to protect the heater. A double-structured muffle having an outer muffle whose outer cross section is larger and shorter than the inner muffle cross section provided on the outside and closed at both ends by an inner muffle outer surface and mortar ; and at both ends of the furnace body and of the inner muffle a plurality of inert gas curtain mechanism comprising a plurality of curtain holes on the lower surface of the tube having an inlet and an outlet portion of the workpiece that is provided on the extension, the inert Gasuka Provided above the ten mechanisms, reducing furnace, characterized in that it comprises a plurality of discharge burner ports to burn atmosphere of hydrogen in the inner muffle is obtained.
[0014]
Further, according to the present invention, in the reduction furnace, the inside of the double structure muffle and the inside of the protective tube for supplying hydrogen gas to the double structure muffle from outside the furnace body is a hydrogen atmosphere, A reduction furnace characterized in that the heat insulating material in the space excluding the double structure muffle and the protective tube in the inside has a nitrogen atmosphere is obtained.
[0016]
Further, according to the present invention, the in any one of the reduction furnace, muffle of the double structure, the outer and Uchima Waffles hydrogen gas in the space of the through the outer Ma Waffles from outside of the furnace body a plurality of protective tubes for supplying, said Ma Waffles reducing furnace, characterized in that it comprises a plurality of through-vent for supplying the hydrogen gas to the internal is obtained.
[0017]
According to the present invention, in the reduction furnace, the nitrogen curtain mechanism is provided with a plurality of curtain holes on the lower surface of the tube.
[0018]
According to the present invention, in any one of the above reduction furnaces, a reduction furnace is obtained in which the inert gas is nitrogen.
[0019]
Moreover, according to this invention, the said reduction furnace WHEREIN: The said flame vent is provided with two or more on the upper surface of the said tube, The reduction furnace characterized by the above-mentioned is obtained.
[0020]
Specifically, in the reduction furnace of the present invention, the furnace inlet and outlet are opened with a curtain structure of nitrogen gas so that the furnace can be opened without burning hydrogen at the inlet and outlet of the furnace. To.
[0021]
Further, the hydrogen gas for atmosphere flowing from the inside of the furnace to the inlet or the outlet of the furnace is provided with a separate combustion port.
[0022]
Moreover, in order to be able to use the heater made from Mo and to obtain the high heat insulation effect, the muffle in a furnace is made into a double structure. In this double structure, the inside and outside of the inner muffle (workpiece and heater made of Mo) have a hydrogen atmosphere, the outer surface of the outer muffle and the space of the furnace body are filled with a heat insulating material, and the heat insulating material filled portion is filled with nitrogen. The structure is an atmosphere.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0024]
FIG. 1 is a cross-sectional view as seen from the upper surface in a substantially central portion of the furnace body of the reduction furnace according to the embodiment of the present invention, and FIG.
[0025]
Referring to FIGS. 1 and 2, the reduction furnace 10 includes a furnace body 1. At both ends of the furnace body 1, work entrances 6 and 7 are provided, and on the side surface of the furnace body 1, a heater terminal box 11 and a nitrogen gas inlet 16 are provided.
[0026]
The furnace body 1 inside, our Ri is accommodated muffle having a double structure of the inner muffle 3 and the outer muffle 2, the muffle is supported through the bricks 22 bearing on the bottom of the inside of the furnace body 1 Yes. A heat insulating material 15 is filled around the outer muffle 2 in the furnace body 1.
[0027]
In the embodiment of the present invention, the muffle has a double structure, and a high alumina inner muffle 3 having a small diameter and a long diameter is provided in a high alumina outer muffle 2. Both ends of the outer muffle 2 are closed with high alumina mortar.
[0028]
Three holes are opened in the outer muffle 2 so that both ends of the heater 4 and the thermocouple 13 can pass therethrough, and protective tubes 9, 9, 14 are respectively inserted.
[0029]
The protective tube 14 for the thermocouple 13 at the center in the length direction of the furnace body 1 is packed with a heat insulating material 12 to block the inside of the muffle from the heater terminal box 11.
[0030]
A heater 4 is wound around the outer surface of the inner muffle 3. A vent hole 5 for introducing gas into the muffle is provided at a position avoiding the heater 4.
[0031]
At the work entrances 6 and 7, a nitrogen gas inlet and chamber 19, a curtain hole 8, and a flame outlet 18 are provided, respectively. A flame amount adjustment valve may be provided at the tip of each flame outlet 18.
[0032]
The heater terminal box 11, a hydrogen gas inlet 21 for introducing hydrogen gas.
[0033]
FIG. 3 is a diagram showing an outline of the flow of hydrogen gas inside the furnace body of the reduction furnace of FIGS. 1 and 2.
[0034]
Referring to FIG. 3, in the furnace body 1, hydrogen gas is introduced from the heater terminal box 11 through the inlets 9 and 9, but the protective tube 14 of the thermocouple 13 is packed with a heat insulating material 12. Therefore, gas does not pass.
[0035]
Accordingly, hydrogen gas passes only through the protective tube 9 of the heater 4 as indicated by an arrow 31 and enters between the high alumina outer muffle 2 and the high alumina inner muffle 3 as indicated by an arrow 32.
[0036]
Hydrogen gas is introduced into the muffle from the vent hole 5 at the center of the inner muffle 2 as indicated by an arrow 33. The hydrogen gas that has entered the muffle through the vent hole 5 flows toward the work entrances 6 and 7 as indicated by arrows 34. Arrows 35 and 36 indicate the loading and unloading directions of the workpieces at the workpiece entrances 6 and 7, respectively.
[0037]
FIG. 4 is a diagram showing the gas flow at the inlet of the reduction furnace 10, and the gas flow at the outlet of the reduction furnace 10 is the same as that at the inlet. FIG. 5 is a diagram showing the gas flow in the entire furnace of the reduction furnace 10 of FIGS. 1 and 2. Referring to FIGS. 4 and 5, nitrogen gas is introduced into the chamber 19 as indicated by an arrow 39, and is formed with a plurality of circumferential intervals from the chamber 19 as indicated by an arrow 40. Nitrogen gas is released from the curtain hole 8 into the furnace as indicated by an arrow 41. Here, in the embodiment of the present invention, the chamber 19 is a box-shaped one having a U-shaped cross section, the top surface of the tip is closed, and a nozzle for introducing nitrogen gas at the bottom. Call. The curtain mechanism refers to a mechanism for forming a planar gas shielding film by blowing nitrogen gas into the tube from each hole of the curtain hole 8, and the gas shielding film is called a curtain.
[0038]
As shown by the arrow 34, the hydrogen gas flowing from the inner muffle 3 mixes with the nitrogen gas released from the curtain hole 8, and due to the difference in specific gravity, the hydrogen gas is released as shown by the arrow 37. The flame is released toward the flame outlet 18 as indicated by reference numeral 38 and does not flow to the workpiece inlet 6. At this time, a part of the nitrogen gas is not mixed with hydrogen and flows toward the inlet 6 and the outlet 7 as indicated by arrows 44.
[0039]
Further , regarding the positions of the flame outlets 18 arranged in the inlet side and outlet side tubes 17 of the reduction furnace 10, the distance from the end surface of the inlet 6 or the outlet 7 to the center position of the flame outlet 18 is particularly strictly defined. What is necessary is just to arrange | position to the furnace body direction side slightly from the end surface of each opening | mouth. The reason is that leakage of hydrogen gas in the inlet or outlet direction can be prevented by increasing the flow rate of the nitrogen gas for curtain supplied from the chamber 19 disposed below the flame outlet 18.
[0040]
With respect to the position of the flame outlet 18 disposed at a position far from the mouth end face of the inlet side and outlet side tube 17 of the reduction furnace 10, the distance from the end face of the inlet 6 or outlet 7 to the center position of the flame outlet 18. is the as described, but the present invention is defined particularly strictly, it is sufficient slightly spaced apart and Hoenn port 18 of the end face. The reason is that by arranging two or more flame outlets 18 and chambers 19 in each tube 17, hydrogen gas can be reliably guided to the flame outlet 18 and burned, and the inlet 6 and the outlet 6. This is because leakage of hydrogen gas can be prevented. Arrows 42 and 43 indicate the loading and discharging directions of the workpiece at the workpiece inlet 6 and the outlet 7, respectively.
[0041]
Further, as shown in FIG. 5, nitrogen gas is introduced from the nitrogen gas inlet 16 provided in the furnace body 1 and flows toward the workpiece inlets 6 and 7 together with the hydrogen gas from the inner muffle 3.
[0042]
Next, the effect by use of the reduction furnace by embodiment of this invention is demonstrated.
[0043]
A uniform discoloration was seen on the surface of the wire-like workpiece after passing through the furnace, and it was fully reduced. Further, in this example, a wire made of Mo having a maximum diameter of φ10 mm could be passed without contacting the muffle.
[0044]
In addition, the curtain nitrogen flow rate is set to 5 [L / min] and 10 [L / min] at both the entrance and exit, heater terminal box: hydrogen flow rate 6 [L / min], furnace body nitrogen flow rate 5 [L / min] The hydrogen concentration at the inlet and outlet of the furnace with an inner diameter of 16.7 mm was below the measuring limit of the instrument (less than 0.5% LEL), and there was no risk of explosion.
[0045]
The heater power at the furnace treatment temperature was about 4 kW, which could be reduced to 65% or less as compared to the calculated value of about 6.5 kW when the entire furnace was in a hydrogen atmosphere. Moreover, the small and high heat insulation effect was acquired, and the outer wall temperature was able to be 120 degrees C or less by actual value. The outer wall temperature is 200 ° C. or more when the inside of the furnace has the same dimensions and a hydrogen atmosphere. Compared to that, it was about 60%.
[0046]
In addition, since the heat insulation in the furnace could be reduced to about ½ compared to the furnace having a hydrogen atmosphere in the furnace, the size of the apparatus could be made compact with a height of 1200 mm × width of 1000 mm × depth of 600 mm.
[0047]
In addition, since the unit price of hydrogen gas is about twice that of nitrogen gas, the running cost can be reduced to 85% in terms of flow rate compared to the case where hydrogen gas is introduced into the furnace body.
[0048]
In the embodiment of the present invention described above, fibrous ceramic fibers are used as the heat insulating material, but general heat insulating bricks may be used.
[0049]
【The invention's effect】
As described above, according to the present invention, since the furnace port structure can continuously reduce the workpiece without oxidizing it, a reduction furnace with extremely high production efficiency can be provided.
[0050]
Furthermore, according to the present invention, since the heat insulation method uses nitrogen gas and a heat insulating material, the amount of heat insulating material used can be reduced. Therefore, according to this invention, since it is the compact furnace body structure which does not take space, the reduction furnace which is easy to industrialize can be provided.
[0051]
Further, according to the present invention, before and after the process, i.e. feeding the workpiece in continuous manner to the reduction furnace Dantsu, and the device can be taken out continuously with a can structure be connected to the furnace production It is possible to provide a reduction furnace capable of enhancing the properties.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view as seen from the upper surface of a substantially central portion of a furnace body of a reduction furnace according to an embodiment of the present invention.
2 is a cross-sectional view seen from the side of the reduction furnace of FIG.
FIG. 3 is a diagram schematically showing the flow of hydrogen gas inside the furnace body of the reduction furnace of FIGS. 1 and 2;
FIG. 4 is a diagram showing the flow of nitrogen and hydrogen gas at the inlet and outlet of the reduction furnace 10 and the direction in which the workpiece is charged.
FIG. 5 is a diagram showing a gas flow in the entire furnace of the reduction furnace 10 of FIGS. 1 and 2;
FIG. 6 is a view schematically showing a batch type reduction furnace according to the prior art.
[Explanation of symbols]
1 Furnace 2 Outer muffle 3 Inner muffle 4 Heater 5 Ventilation holes 6, 7 Entrance / exit (entrance, exit)
8 Curtain holes 9 and 14 Protective tube 10 Reduction furnace 11 Heater terminal box 12 Heat insulation material 13 Thermocouple 15 Heat insulation material 16 Nitrogen gas introduction port 17 Tube 18 Flame discharge port 19 Chamber 22 Support brick 100 Batch type reduction furnace 101 Furnace body 102 Work 103 Thermocouple 104 Heater 105 Flame release 106 Pilot flame 107 Muffle 108a, 108b Door 110 Hydrogen gas

Claims (3)

A furnace capable of heat-treating a surface of a long workpiece made of a long wire of a refractory metal, a thin and thin plate material, and a foil-like material without being oxidized , inside the furnace body of the furnace
An inner muffle whose both ends are open so that a heater can be wound around the outer surface and a workpiece to be heat-treated can pass therethrough;
A double structure having an outer muffle having a larger cross section than the inner muffle cross section provided at the outer side of the inner muffle and having both ends closed with mortar and having a shorter cross section so as to have an atmosphere for protecting the heater. Muffle,
A plurality of inert gas curtain mechanisms having a plurality of curtain holes on the lower surface of a tube having an inlet portion and an outlet portion of a workpiece provided at both ends of the furnace body and on an extension line of the inner muffle ;
A reduction furnace comprising: a plurality of flame outlets provided at an upper portion of the inert gas curtain mechanism and configured to burn atmospheric hydrogen in the inner muffle . 2. The reduction furnace according to claim 1, wherein a hydrogen atmosphere is provided in the double-structured muffle and in a protective tube for supplying hydrogen gas from outside the furnace body to the double-structured muffle, and the inside of the furnace body includes the hydrogen atmosphere. A reduction furnace characterized by having a heat insulating structure in which a heat insulating material in a space excluding the double structure muffle and the protective tube has a nitrogen atmosphere . In the reduction furnace according to claim 1 or 2, the muffle of the double structure, the furnace body out of the plurality of supplying hydrogen gas to the space portion of the outer and Uchima Waffles through said outer Ma Waffles of a protective tube, the reducing furnace said Ma Waffles is characterized in that it comprises a plurality of through-vent for supplying the hydrogen gas to the internal.

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