Quartz rod vacuumizing drawing smelting furnace

Abstract

The invention provides a quartz rod vacuumizing drawing smelting furnace, and relates to the technical field of quartz processing, the quartz rod vacuumizing drawing smelting furnace comprises a furnace body, a crucible, a heater, a contraction furnace mouth and an air cooling shaping discharge pipe, the crucible is located in the furnace body, the heater is located outside the crucible, and the air cooling shaping discharge pipe comprises an air pressure pipe connected with the contraction furnace mouth and a guide pipe connected to the lower end of the air pressure pipe; a gap is formed between the lower end of the crucible and the mounting plane of the shrinkage furnace mouth, a gap communicated with the inner cavity of the furnace body is formed between the outer wall of the crucible and the inner wall of the heater, an air exhaust hole communicated with the outside is formed in the furnace body, the upper end of the quartz tube located in the crucible is sealed, and the inner cavity of the quartz tube and the inner cavity of the furnace body are both in a negative pressure state; the air pressure of the wind pressure pipe inner cavity is lower than that of the furnace body inner cavity. The method has the advantages of better finished product quality and the like.

Description

Technical Field

[0001] This invention relates to the field of quartz processing technology, and in particular to a vacuum drawing furnace for quartz rods. Background Technology

[0002] Quartz glass fiber refers to a special type of glass fiber with a silica content of over 99.9% and a filament diameter of 1-15µm. It is made by refining and processing pure natural crystal into molten quartz glass rods and drawing them. During the drawing process, heating methods include oxyhydrogen flame and plasma methods, and appropriate sizing agents are applied depending on the application. Quartz fiber products can be expanded to include direct untwisted rovings, twisted yarns (including single and ply yarns), fiber cloths, fiber sleeves, chopped strands, fiber cotton, fiber felts, and fiber bricks. Quartz fiber has high heat resistance, can be used for extended periods below 1050℃, and can withstand instantaneous high temperatures up to 1700℃. Furthermore, due to its excellent electrical insulation properties, its dielectric constant and dielectric loss coefficient are the best among all mineral fibers. Therefore, quartz glass fiber has wide applications in aerospace, military, semiconductor, high-temperature insulation, and high-temperature filtration.

[0003] Quartz rods are solid quartz tubes formed by melting and cooling quartz sand. They can have a diameter of 2-150mm and a length of 2-2000mm. The most common manufacturing method is to directly draw them out through a continuous melting furnace. After the quartz sand is melted at high temperature, it is drawn out into a solid quartz rod through a specific device (controlling the outer diameter and flow rate). Quartz yarn is used to draw quartz rods to make quartz rods.

[0004] When drawing small-diameter quartz rods from quartz tubes, the quartz tubes are placed inside a graphite crucible in a furnace. The quartz tubes are heated by the resistance heating of the graphite crucible until they reach their softening temperature. Then, the material is drawn to produce quartz rods of various specifications. The quality of the quartz rods directly affects the quality of the quartz yarn. Defects in quartz rods are divided into impurity defects and processing defects. Impurity defects come from metallic impurities, mineral impurities, and gas-liquid impurities. Processing defects come from external defects such as gas lines and bubbles caused by the contact between the quartz blank and the graphite crucible during the heating process. Among these defects, metallic and mineral defects can be reduced through raw material treatment, while gas-liquid defects and external defects caused by the processing process need to be repaired during processing.

[0005] Quartz rods used for processing quartz yarn need to be inspected to remove those with crystallization defects caused by gas bubbles and gas-liquid defects, so as to avoid them causing physical defects in the quartz yarn during the drawing process.

[0006] Currently, there is a method of using negative pressure inside the quartz rod to remove the vacuum from the quartz tube during hot melting. However, this method is suitable for thin-walled quartz tubes. The outer tube surface of thick-walled quartz tubes cannot effectively remove air bubbles and gas lines, or disperse gas and liquid impurities. Moreover, vacuum inside the quartz tube will cause some gas and liquid impurities on the outer wall to move inward. Although this will not affect the outer tube of the drawn quartz rod, it will create a hidden defect. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention proposes a quartz rod drawing furnace that can effectively remove gas-liquid defects.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: a vacuum drawing furnace for quartz rods, characterized in that it includes a furnace body, a crucible, a heater, a shrinking furnace opening, and an air-cooled shaping discharge pipe. The crucible is located inside the furnace body, and the heater is located outside the crucible. The air-cooled shaping discharge pipe includes an air pressure pipe connected to the shrinking furnace opening and a guide pipe connected to the lower end of the air pressure pipe. There is a gap between the lower end of the crucible and the mounting plane of the shrinking furnace opening. There is a gap between the outer wall of the crucible and the inner wall of the heater, which communicates with the inner cavity of the furnace body. The furnace body is provided with an air extraction hole communicating with the outside. The upper end of the quartz tube located inside the crucible is sealed. Both the inner cavity of the quartz tube and the inner cavity of the furnace body are under negative pressure. The air pressure inside the air pressure pipe is lower than the air pressure inside the furnace body.

[0009] Furthermore, a windshield with an opening at the top is provided inside the guide tube, and an air inlet pipe and an air outlet pipe are provided on the guide tube, with the inlet of the air inlet pipe and the outlet of the air outlet pipe both located outside the windshield.

[0010] This solution simultaneously evacuates the inner cavity of the quartz rod and the outer cavity of the furnace body. In addition, a negative pressure lower than the gas pressure inside the furnace body is set in the guide tube. This allows the quartz tube to be subjected to negative pressure from both the inside and outside during the melting and softening process. This can remove bubbles formed by gas impurities and bubbles formed by liquid impurities from multiple directions, reducing the residue of gas and liquid impurities and the outer contour defects of the drawn quartz rod.

[0011] In addition, due to the presence of the long guide tube, the quartz rod can almost seal the guide tube after being pulled out. This allows the negative pressure formed inside the guide tube, which is lower than the air pressure inside the furnace cavity, to "pneumatically pull" the softened quartz material at the shrinkage furnace opening. This pulling not only increases the extrusion pressure between the softened quartz material and the shrinkage mold at the shrinkage furnace opening, allowing the outer contour defects to be repaired by physical extrusion, but also buffers the pulling force of the quartz tube due to the pneumatic pulling. This can increase the non-mechanical pulling force of the quartz rod while reducing the mechanical pulling force of the quartz rod during discharge. This is a way to optimize the discharge pulling force control and reduce the risks of quartz rod discharge pulling. Attached Figure Description

[0012] Figure 1 A furnace for drawing quartz rods under vacuum.

[0013] Legend: 1. Furnace body; 2. Crucible; 3. Heater; 4. Shrink furnace opening; 5. Air pressure pipe; 6. Guide pipe; 7. Exhaust port; 8. Wind shield; 9. Air inlet pipe; 10. Air outlet pipe. Detailed Implementation

[0014] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0015] like Figure 1 As shown, the furnace includes a furnace body 1, a graphite crucible 2, a heater 3, a shrink furnace opening 4, and an air-cooled shaping discharge pipe. The crucible 2 is located inside the furnace body 1, and the heater 3 is located outside the crucible 2. There is a gap between the lower end of the crucible 2 and the mounting plane of the shrink furnace opening 4, meaning that the lower end of the crucible 2 is not sealed, allowing the quartz tube near the shrink furnace opening 4 to be unobstructed by the crucible 2. There is a gap between the outer wall of the crucible 2 and the inner wall of the heater 3, connecting to the inner cavity of the furnace body 1. The cavity is connected to the periphery of the contraction position of the quartz tube. A clamp is set on the top of the crucible 2 to seal the inner cavity of the quartz tube. The clamp is equipped with a vent hole that communicates with the outside. Vacuum treatment is performed on the inner cavity of the quartz tube through the vent hole. Vacuum treatment is also performed on the inner cavity of the furnace body 1 through the vent hole 7. This allows the quartz tube to soften at the contraction position, thus enabling air bubbles to escape through negative pressure both inside and outside the quartz tube. In contrast, the traditional method only allows negative pressure to escape inside the quartz tube. In addition, a greater negative pressure is set in the air pressure pipe 5, so that the inner cavity of the furnace body 1 is in a positive pressure state relative to the inner cavity of the air pressure pipe 5. This can put the softened quartz material in a "suction and pull" state. A wind baffle 8 is set in the air pressure pipe 5, and a pressure limiting valve is set at the extension pipe connected to the air inlet pipe 9 to achieve a negative pressure state in the air pressure pipe 5, and the air inlet is an inert gas.

[0016] Preferably, in order to achieve a better seal between the guide tube 6 and the quartz rod, the length of the guide tube 6 can be extended, and a pipe for conveying the lubricating medium inside the guide tube 6 can be installed in the middle of the guide tube 6, so as to minimize the amount of gas introduced into the air pressure pipe 5 from the outlet of the guide tube 6, thereby affecting the negative pressure and introducing contaminants.

[0017] This solution involves setting multiple gas pressures, the specific values ​​of which depend on a comprehensive consideration of various factors, including not only the furnace body 1, the specifications and drawing diameter ratio of the quartz rod and quartz tube, but also the material of the quartz tube, etc. It can be adapted according to needs and adjustments, and providing numerical values ​​is not of reference value.

[0018] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A vacuum drawing furnace for quartz rods, characterized in that, The furnace includes a furnace body (1), a crucible (2), a heater (3), a shrink furnace opening (4), and an air-cooled shaping discharge pipe. The crucible (2) is located inside the furnace body (1), and the heater (3) is located outside the crucible (2). The air-cooled shaping discharge pipe includes an air pressure pipe (5) connected to the shrink furnace opening (4) and a guide pipe (6) connected to the lower end of the air pressure pipe (5). There is a gap between the lower end of the crucible (2) and the mounting plane of the shrink furnace opening (4). There is a gap between the outer wall of the crucible (2) and the inner wall of the heater (3) that connects to the inner cavity of the furnace body (1). The furnace body (1) is provided with an air extraction hole (7) that connects to the outside. The upper end of the quartz tube located inside the crucible (2) is sealed. The inner cavity of the quartz tube and the inner cavity of the furnace body (1) are both under negative pressure. The air pressure in the inner cavity of the air pressure pipe (5) is lower than the air pressure in the inner cavity of the furnace body (1).

2. The quartz rod vacuum drawing furnace according to claim 1, characterized in that, The guide tube (6) is provided with a windshield (8) with an opening at the top. The guide tube (6) is provided with an air inlet pipe (9) and an air outlet pipe (10). The inlet of the air inlet pipe (9) and the outlet of the air outlet pipe (10) are both located outside the windshield (8).

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