Quartz tube induction furnace tube drawing equipment and graphite heating body thereof

Abstract

The utility model provides quartz tube induction furnace tube drawing equipment and a graphite heating body thereof. The graphite heating body is of a cylindrical structure, a strip-shaped notch is formed in the side wall of the graphite heating body, the notch penetrates through the side wall of the graphite heating body, the width of the notch is 0.5 mm-1 mm, and the height of the notch is 50 mm-85 mm. According to the graphite heating body of the quartz tube induction furnace tube drawing equipment, the strip-shaped notches are formed in the side wall of the graphite heating body, so that vortex radiant heat of an induction coil is cut off, the precision of drawing a quartz liner tube can be improved, and distortion of ovality and curvature of the quartz liner tube can be avoided.

Description

Technical Field

[0001] This utility model relates to the technical field of tube drawing equipment for quartz tube induction furnaces, and in particular to a tube drawing device for quartz tube induction furnaces and its graphite heating element. Background Technology

[0002] Pure quartz liners and quartz tubes have been widely used in the fabrication of optical fiber preforms. Pure quartz liners with dimensional and precision requirements are usually formed by high-temperature melting and stretching of quartz tube blanks. CN101679098A discloses a vertical drawing method in which the quartz glass cylinder and the drawn liner product rotate relative to each other on the longitudinal axis during the drawing process, a process called "torsion". This torsional operation makes the circumferential temperature distribution in the furnace uniform, compensates for the thermal asymmetry of the furnace heating zone, and thus improves the drawing quality of pure quartz liners, enabling the production of high-precision products.

[0003] However, in order to achieve the rotation of the quartz glass cylinder or liner product in the tensile axis, this method requires a complex feeding machinery system or mechanical traction system, which increases the cost and difficulty of industrialization. Utility Model Content

[0004] The main purpose of this invention is to provide a quartz tube induction furnace tube drawing device and its graphite heating element, which aims to improve the eddy current effect of the induction coil, thereby improving the accuracy of drawing quartz liner tubes.

[0005] To achieve the above objectives, this utility model provides a graphite heating element for a quartz tube induction furnace tube drawing device. The graphite heating element has a cylindrical structure, and a strip-shaped slit is provided on the side wall of the graphite heating element. The slit penetrates the side wall of the graphite heating element, and the width of the slit is 0.5mm~1mm, and the height of the slit is 50mm~85mm.

[0006] Preferably, the graphite heating element is provided with at least a middle cut group and a bottom cut group along its axial direction. Both the middle cut group and the bottom cut group include multiple cuts evenly arranged in the circular direction of the graphite heating element, wherein the bottom of the cut of the bottom cut group is located on the bottom end face of the graphite heating element.

[0007] This utility model also proposes a quartz tube induction furnace tube pulling device, including the above-mentioned graphite heating element, and also including a feeding mechanism, a furnace body and a traction mechanism arranged in sequence. The graphite heating element is installed inside the furnace body, and the graphite heating element is covered with a heat insulation felt and an induction coil in sequence.

[0008] Preferably, the induction coil is flat-wound, and a ceramic rod is fixed to the side of the induction coil. A support foot is fixed to the side of the ceramic rod to abut against the inner wall of the furnace body.

[0009] Preferably, the induction coil is provided with a plurality of ceramic rods in the circumferential direction, and the top and bottom ends of the ceramic rods are fixed with support feet.

[0010] Preferably, the induction coil has a hollow rectangular cross-section, internal cooling water, and an organic silicon insulating coating on its surface. The ratio of the width of the induction coil to the inter-turn spacing is set to 0.85~0.95.

[0011] Preferably, the furnace body comprises an upper furnace flange, a lower furnace flange, an outer furnace shell, and an inner furnace shell welded together. The graphite heating element and the induction coil are located between the outer furnace shell and the inner furnace shell. Both the outer furnace shell and the inner furnace shell are provided with spiral guide vanes. The support foot at the bottom of the ceramic rod is fastened to the upper part of the lower furnace flange with bolts.

[0012] Preferably, the graphite heating element is positioned and installed above the graphite insulation cylinder via a stop, and a graphite guide ring is fitted on the upper part of the graphite heating element.

[0013] Preferably, the graphite insulation cylinder is installed on the installation platform, the installation platform is provided with a cooling water channel, the bottom of the installation platform is provided with a graphite sealing plate that can be moved left and right to open and close, and diameter measuring instruments are provided on both sides of the installation platform.

[0014] Preferably, it also includes a water-air ring assembly and a furnace cover plate, both of which are fastened to the top opening of the furnace body by bolts.

[0015] The quartz tube induction furnace tube drawing equipment proposed in this utility model has the following beneficial effects:

[0016] 1. By opening strip-shaped slits on the side wall of the graphite heating element, the vortex radiation heat of the induction coil is cut off, which not only improves and enhances the accuracy of drawing quartz liner tubes, but also avoids distortion of the ellipticity and curvature of the quartz liner tubes.

[0017] 2. This quartz tube induction furnace tube drawing equipment does not require a rotating mechanism to achieve relative rotation of the liner tubes on the longitudinal axis. Compared with the improvement of existing technologies, this equipment is simpler to improve, has lower modification costs, and has a stable and reliable structure.

[0018] 3. This quartz tube induction furnace tube drawing equipment has the advantages of low modification cost, low modification difficulty, and simple and easy-to-implement structure. Attached Figure Description

[0019] Figure 1 This is a cross-sectional structural schematic diagram of the quartz tube induction furnace tube drawing equipment of this utility model;

[0020] Figure 2 This is a cross-sectional structural schematic diagram of the graphite heating element in the quartz tube induction furnace tube drawing equipment of this utility model;

[0021] Figure 3 This is a schematic diagram of the structure of the induction coil in the quartz tube induction furnace tube drawing equipment of this utility model;

[0022] Figure 4 This is a schematic diagram of the furnace body in the quartz tube induction furnace tube drawing equipment of this utility model.

[0023] In the diagram, 1-feeding mechanism, 2-quartz tube, 3-quartz ring, 4-water-air ring assembly, 5-graphite guide ring, 6-furnace cover plate, 7-furnace body, 8-induction coil, 9-infrared thermometer, 10-lower flange of furnace body, 11-insulation felt, 12-graphite heating element, 13-graphite insulation cylinder, 14-installation platform, 15-diameter gauge, 16-graphite sealing plate, 17-guide wheel, 18-traction wheel, 19-rubber O-ring, 20-ceramic rod, 21-support foot, 22-upper flange of furnace body, 23-outer furnace shell, 24-inner furnace shell, 25-spiral guide vane.

[0024] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0025] It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0026] It should be noted that in the description of this utility model, the terms "lateral," "longitudinal," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used solely for the convenience of describing this utility model and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0027] This utility model proposes a tube drawing device for a quartz tube induction furnace.

[0028] Reference Figures 1 to 3 In this preferred embodiment, a quartz tube induction furnace tube drawing device includes a graphite heating element 12, a feeding mechanism 1, a furnace body 7, and a traction mechanism arranged sequentially. The graphite heating element 12 is installed inside the furnace body 7. The graphite heating element 12 has a cylindrical structure, and a strip-shaped slit is formed on its side wall, penetrating the side wall of the graphite heating element 12. The width of the slit is 0.5mm to 1mm, and the height of the slit is 50mm to 85mm. An insulation felt 11 and an induction coil 8 are sequentially fitted around the graphite heating element 12.

[0029] The slit width is 0.5mm~1mm and the slit height is 50mm~85mm. The slit size is set in this way to take into account both the convenience of processing and the heating effect. If the slit size is too large, the heat generated by the induction coil will be lost, and if it is too small, it will not have a blocking effect (refer to the idea of ​​severing the ligature).

[0030] The feeding mechanism 1 is fixed to the tower and driven by a screw or other type of mechanism to achieve vertical movement. The traction mechanism includes a guide wheel 17 and a traction wheel 18, both of which are arranged directly below the furnace opening. Their center sections are coplanar with the center of the furnace body 7. The traction wheel 18 is driven to rotate by a motor. The quartz tube 2 softens into a cone shape in the high-temperature zone. After the cone tip melts and falls off, the furnace door at the lower opening is closed, and the traction wheel 18 clamps the thinned quartz tube to begin the stretching and elongation process.

[0031] Furthermore, referring to Figure 2 The graphite heating element 12 has at least a middle cut group and a bottom cut group along its axial direction. Both the middle cut group and the bottom cut group include multiple cuts evenly arranged in a circular direction on the graphite heating element 12. The bottom of the cuts in the bottom cut group is located on the bottom end face of the graphite heating element 12 (that is, the cuts in the bottom cut group penetrate its bottom end face). The figure illustrates this by taking an example where both the middle cut group and the bottom cut group include four cuts. The even distribution of multiple cuts is to prevent the heat zone from being disturbed by the cuts. The cuts also mainly cut off the eddy currents in the induction coil.

[0032] In this embodiment, the induction coil 8 is flat-wound to provide a uniform temperature field. A ceramic rod 20 is fixed to the side of the induction coil 8, and a support foot 21 is fixed to the side of the ceramic rod 20 to abut against the inner wall of the furnace body 7, thereby facilitating the improvement of the installation accuracy of the induction coil 8 inside the furnace.

[0033] Furthermore, multiple ceramic rods 20 are arranged around the circumference of the induction coil 8, and support feet 21 are fixed at the top and bottom of the ceramic rods 20.

[0034] In this embodiment, the induction coil 8 has a hollow rectangular cross-section, with cooling water flowing inside, and an organosilicon insulating coating on its surface. The ratio of the width of the induction coil 8 to the inter-turn spacing is set to 0.85~0.95, thereby significantly improving the insulation coefficient and preventing gas discharge breakdown inside the furnace.

[0035] Specifically, refer to Figure 4The furnace body 7 comprises an upper flange 22, a lower flange 10, an outer furnace shell 23, and an inner furnace shell 24, all welded together. Both the outer and inner furnace shells 23 and 24 are equipped with spiral guide vanes 25. The support feet 21 at the bottom of the ceramic rod 20 are bolted to the upper part of the lower flange 10. The spiral guide vanes 25 utilize forced convection of process cooling water to enhance cooling. An infrared thermometer 9 is installed on one side of the furnace body 7 for online monitoring of the furnace temperature. The support feet 21 at the bottom of the ceramic rod 20 are bolted to the upper part of the lower flange 10, ensuring that the axis of the induction coil 8 is coaxial with the centerline of the furnace body 7.

[0036] The graphite heating element 12 is positioned above the graphite insulation cylinder 13 via a stop (providing a stress-relieving annealing temperature zone for the formed pipe). A graphite guide ring 5 is fitted on the upper part of the graphite heating element 12 (to allow the graphite heating element 12 to extend along the axis after thermal expansion without deviating from the center of the furnace body 7). The graphite insulation cylinder 13 is mounted on the installation platform 14, which is equipped with a cooling water channel. A graphite sealing plate 16 that can move left and right is installed at the bottom of the installation platform 14 (to prevent air from entering the furnace due to the chimney effect caused by an excessively large gap at the lower furnace opening, resulting in high-temperature oxidation of the graphite heating element 12). Diameter gauges 15 are installed on both sides of the installation platform 14. The diameter gauges 15 are used for online real-time monitoring of the outer diameter of the target pipe and provide feedback to adjust the traction speed and the output power of the intermediate frequency power supply (to regulate the temperature of the heating element).

[0037] The water-gas ring assembly 4 and the furnace cover plate 6 are bolted together and secured to the top opening of the furnace body 7. Each mounting surface of the water-gas ring assembly 4 and the furnace cover plate 6 is equipped with a rubber O-ring 19 to achieve a seal and prevent air from entering the graphite oxide heating element 12 inside the furnace. The water-gas ring assembly 4 has a planar narrow gap and a conical narrow gap. The first protective gas (such as argon or nitrogen) enters the furnace through the planar narrow gap, forming a gas seal to prevent external air from entering the furnace. The second protective gas enters the furnace through the conical narrow gap, maintaining positive pressure inside the furnace, forming an inert atmosphere, and transferring heat through convection.

[0038] The mounting platform 14 is fixed to the tower, and the furnace body 7 is fastened to the mounting platform 14 with bolts. The material feeding mechanism, the furnace body 7, and the mounting platform 14 are concentric.

[0039] Quartz tube 2 (or solid glass rod) is fixed to feeding mechanism 1, which can move up and down. Quartz tube 2 is fed into the middle position of furnace body 7 by feeding mechanism 1. Quartz ring 3 is nested on water-air ring assembly 4 and is used for centering and aligning quartz tube 2 (or solid glass rod).

[0040] The quartz tube induction furnace tube drawing equipment is used to draw pure quartz hollow sleeves into pure quartz liner tubes. The drawn pure silicon quartz tubes have an ellipticity of <0.05mm, a wall thickness of <0.08mm, and a curvature of <0.2mm / m. The detailed parameters of the liner tubes ABC are shown in Table 1 (sleeve A is made into liner A, sleeve B is made into liner B, and sleeve C is made into liner C).

[0041] Table 1 Detailed parameters of the liner

[0042]

[0043] As can be seen from the table above, the quartz tube induction drawing equipment achieves high precision in terms of wall deviation, out-of-roundness, and curvature. Conventional equipment, on the other hand, produces tubes with wall deviation exceeding 0.08mm, ellipticity exceeding 0.05mm, and curvature exceeding 0.3mm / m, making it difficult to guarantee high-precision geometry, especially for thick-walled liner tubes, where existing equipment struggles to ensure ellipticity and curvature accuracy.

[0044] The technical solution for stretching and elongating the quartz tube 2 of this invention is as follows: The furnace body 7 is fixed on the tower or installation platform 14, and the quartz tube 2 is fixed on the feeding mechanism 1. The feeding mechanism 1 feeds the quartz tube into the heating zone inside the furnace body 7. The feeding mechanism 1 can move up and down along the guide rail of the tower body. The feeding speed is determined by the diameter of the parent material, the diameter of the target tube, and the traction speed. A protective gas is introduced into the furnace to prevent the graphite heating element 12 from oxidizing. The intermediate frequency power supply outputs heating power. After the induction coil 8 is loaded with alternating current, an alternating magnetic field is generated. Due to electromagnetic induction, the graphite heating element 12 generates an induced current (eddy current) on its surface, which in turn generates Joule heat. The quartz tube 2 is heated, melted, and softened through thermal radiation and heat transfer by the protective gas convection. After the furnace temperature reaches the set target temperature (1800℃~2300℃), the quartz tube 2 softens into a cone shape in the high-temperature zone. After the cone tip melts and falls off, the furnace door at the lower opening is closed, and the traction wheel 18 clamps the thinned quartz tube to begin the stretching and elongation process. During the stretching process, the laser diameter gauge 15 monitors the outer diameter of the target pipe in real time online and provides feedback to adjust the traction speed and the output power of the intermediate frequency power supply (to regulate the temperature of the heating element). After stretching to the required length, the pipe is cut to obtain the target tube.

[0045] The quartz tube induction furnace tube drawing equipment proposed in this embodiment has the following beneficial effects:

[0046] 1. By opening strip-shaped cuts on the side wall of the graphite heating element 12, the vortex radiation heat of the induction coil 8 is cut off, which can not only improve and enhance the accuracy of drawing the quartz liner, but also avoid distortion of the ellipticity and curvature of the quartz liner.

[0047] 2. This quartz tube induction furnace tube drawing equipment does not require a rotating mechanism to achieve relative rotation of the liner tubes on the longitudinal axis. Compared with the improvement of existing technologies, this equipment is simpler to improve, has lower modification costs, and has a stable and reliable structure.

[0048] 3. This quartz tube induction furnace tube drawing equipment has the advantages of low modification cost, low modification difficulty, and simple and easy-to-implement structure.

[0049] This utility model also proposes a graphite heating element 12 for a quartz tube induction furnace tube drawing device.

[0050] Reference Figure 1 and Figure 2 In this preferred embodiment, a graphite heating element 12 of a quartz tube induction furnace tube drawing device is provided. The graphite heating element 12 has a cylindrical structure. A strip-shaped cut is provided on the side wall of the graphite heating element 12. The cut penetrates the side wall of the graphite heating element 12. The width of the cut is 0.5mm~1mm and the height of the cut is 50mm~85mm.

[0051] Furthermore, the graphite heating element 12 is provided with at least a middle cut group and a bottom cut group in the axial direction. Both the middle cut group and the bottom cut group include multiple cuts evenly arranged in the circular direction of the graphite heating element 12, wherein the bottom of the cut of the bottom cut group is located on the bottom end face of the graphite heating element 12.

[0052] The above are merely preferred embodiments of this utility model and do not limit the patent scope of this utility model. Any equivalent structural transformations made based on the description and drawings of this utility model, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. A graphite heater for a quartz-tube induction furnace tube-pulling apparatus, characterized by comprising: The graphite heating element has a cylindrical structure, and a strip-shaped cut is opened on the side wall of the graphite heating element. The cut penetrates the side wall of the graphite heating element, and the width of the cut is 0.5mm~1mm and the height of the cut is 50mm~85mm.

2. The graphite susceptor of the quartz-tube induction furnace puller apparatus according to claim 1, wherein The graphite heating element is provided with at least a middle cut group and a bottom cut group along its axial direction. Both the middle cut group and the bottom cut group include multiple cuts evenly arranged in the circular direction of the graphite heating element, wherein the bottom of the cut of the bottom cut group is located on the bottom end face of the graphite heating element.

3. A quartz tube induction furnace tube drawing apparatus characterized by comprising: The system includes the graphite heating element as described in any one of claims 1 or 2, and further includes a feeding mechanism, a furnace body, and a traction mechanism arranged in sequence, wherein the graphite heating element is installed inside the furnace body, and an insulation felt and an induction coil are sequentially wrapped around the graphite heating element.

4. The quartz tube inductive furnace tube pulling apparatus as claimed in claim 3, wherein The induction coil is flat-wound, and a ceramic rod is fixed to the side of the induction coil. A support foot is fixed to the side of the ceramic rod to abut against the inner wall of the furnace body.

5. The quartz tube inductive furnace tube pulling apparatus as claimed in claim 4, wherein The induction coil has multiple ceramic rods arranged around its circumference, and the top and bottom of each ceramic rod are fixed with support feet.

6. The quartz tube inductive furnace tube pulling apparatus as claimed in claim 4, wherein The induction coil has a hollow rectangular cross-section, is cooled by internal cooling water, and has an organic silicon insulating coating on its surface. The ratio of the width of the induction coil to the inter-turn spacing is set to 0.85~0.

95.

7. The quartz tube inductive furnace tube pulling apparatus as claimed in claim 4, wherein The furnace body comprises an upper flange, a lower flange, an outer furnace shell, and an inner furnace shell, all welded together. The graphite heating element and the induction coil are located between the outer and inner furnace shells. Both the outer and inner furnace shells are equipped with spiral guide vanes. The support feet at the bottom of the ceramic rod are bolted to the upper part of the lower flange of the furnace body.

8. The quartz tube inductive furnace tube pulling apparatus as claimed in claim 4, wherein The graphite heating element is positioned and installed above the graphite insulation cylinder via a stop, and a graphite guide ring is fitted on the upper part of the graphite heating element.

9. The quartz tube inductive furnace tube pulling apparatus as claimed in claim 8, wherein The graphite insulation cylinder is installed on the installation platform, which is equipped with a cooling water channel. A graphite sealing plate that can be moved left and right to open and close is installed at the bottom of the installation platform, and diameter measuring instruments are installed on both sides of the installation platform.

10. The quartz tube inductive furnace tube pulling apparatus as claimed in claim 4, wherein It also includes a water-air ring assembly and a furnace cover plate, both of which are bolted to the top opening of the furnace body.

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