Graphite piece of induction furnace and air intake and exhaust method

Abstract

The invention relates to the field of optical fiber cable equipment, and discloses an induction furnace graphite piece and an air intake and exhaust method which are used for optical wand wire drawing. The induction furnace graphite piece comprises a light bar, an upper cover plate, an upper gas plate, an upper water jacket, an upper flange, a furnace body, an induction coil, a quartz bottom plate, a lower cover plate, a transition plate, an extension pipe, an upper gas guide ring, a lower gas guide ring, a central pipe, a bottom support, a lower guide pipe and a lining. An upper exhaust structure is designed, air is fed through a mass flow meter MF1, a mass flow meter MF2 and a mass flow meter MF3, air is exhausted through a mass flow meter MF4, the amount of ash in a furnace body brought out from an outlet in the bottom of an extension pipe along an optical fiber is reduced, the ash is exhausted from an upper opening, and therefore the section rate is increased; a pump, buffer tank and fan structure is built, the upper limit and the lower limit of the buffer tank are controlled, and air intake and exhaust balance in the furnace body is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical fiber cable equipment, in particular to a graphite piece of an induction furnace and an air inlet and exhaust method. BACKGROUND

[0002] Optical fiber is obtained by melting optical rods, and the optical rods are heated by a drawing furnace. At present, most of the drawing furnaces of optical fiber manufacturers use induction furnaces. The working principle of the induction furnace, as the core equipment for optical fiber drawing, is to generate an alternating magnetic field through a coil to generate eddy current heating in the graphite piece, so as to heat the optical rod to a molten state and then draw the optical rod. The induction furnace mainly consists of a metal furnace body, a graphite piece, a coil and the like. The air inlet and exhaust system of the induction furnace is generally designed as "up-in and down-out", that is, the gas is introduced from the top of the furnace body, passes through the high-temperature area of the graphite piece and is then discharged from the bottom of the fiber outlet. In theory, it is expected to form an air flow from top to bottom, carry away impurities and maintain the inert atmosphere in the furnace.

[0003] However, the following problems exist in the actual production and application at present: 1. The fiber outlet is easy to carry out ash, affecting the cleanliness of the clean room, causing fiber breakage and affecting the section rate. 2. Even if an ash collector is designed and installed at the lower port, the effect is not ideal. SUMMARY

[0004] In view of the above problems, the present application provides an induction furnace graphite piece and an air inlet and exhaust method, which can increase the section rate of the induction furnace. The specific technical scheme is as follows: An induction furnace graphite piece, comprising an optical rod, a coil, a quartz bottom plate, a filter element, a pump, a buffer tank, a fan, argon, a differential pressure gauge, a mass flow meter, and further comprising a metal furnace body structure, a graphite piece structure, and an air inlet and exhaust system. The optical rod is inserted into the inner side of the graphite piece structure, the coil is installed on the quartz bottom plate, the buffer tank controls the upper and lower limits of the pressure in the tank through the fan, and the differential pressure gauge is installed on the air hole of the upper air plate. The buffer tank controls the upper and lower limits of the pressure in the tank through the fan to keep the internal pressure of the furnace body balanced. The differential pressure gauge is installed on the air hole of the upper air plate to adjust the flow setting of the mass flow meter and maintain the micro-positive pressure in the furnace. The air inlet and exhaust system is an upper exhaust structure, comprising a cavity A, a cavity B and a cavity C. The cavity A and the cavity C are gas inlet cavities, and the cavity B is a gas exhaust cavity.

[0005] The metal furnace body structure is made of SUS304 material and comprises an upper cover plate, an upper air plate, an upper water jacket, an upper flange, a furnace body, a lower cover plate, a transition plate and an extension pipe. The components are connected through positioning steps and are equipped with sealing rings and are fixed by bolts.

[0006] Each component of the metal furnace body structure is provided with a water cavity and is supplied with cooling water. The depth of the water cavity of the lower cover plate is greater than or equal to 20 mm to prevent deformation.

[0007] The upper air plate is processed with three horizontal 6mm holes, which are distributed at 90 degrees interval, two of which are symmetrically used for air inlet, and the other one is used for installing differential pressure gauge. The upper water jacket is processed with two horizontal 10mm holes, which are symmetrically distributed, and used for air outlet. The lower cover plate is processed with four horizontal 6mm holes, which are uniformly distributed in the circumference, and used for air inlet. The fiber outlet at the bottom of the extension pipe is a trumpet mouth, and is processed with two obliquely upward 6mm holes, which are used for air inlet. The inner wall of the upper end of the extension pipe is processed with a stepped hole, the depth of which is 300-400mm, and used for installing the graphite lining. The stepped hole of the upper air plate is processed with a bevel, which is used for installing the upper air guide ring, and ensures the concentricity.

[0008] The graphite parts include upper air guide ring, lower air guide ring, center pipe, bottom support, lower guide pipe and lining. The bottom support is installed on the lower cover plate, and the contact surface is ≤3mm, which prevents the local deformation of the lower cover plate caused by heating. The center pipe is positioned and installed in the bottom support through the stepped hole. The lower air guide ring is embedded and installed in the inner wall of the center pipe, and the upper end is installed on the positioning stepped hole of the upper water jacket, and the gap between the lower air guide ring and the bottom surface of the upper air plate is 3-4mm after installation. The upper air guide ring and the upper air plate are embedded and installed through the bevel, which ensures the concentricity, and the gap between the outer wall of the upper air guide ring and the outer wall of the upper air plate is 1mm, which prevents the upper air guide ring from being broken after thermal expansion. After installation, the gap between the upper air guide ring and the bottom of the upper cover plate is 1-1.5mm, and the gap between the upper air guide ring and the lower air guide ring is 4mm. The lower guide pipe is installed on the positioning stepped hole of the lower cover plate, and is fixed at the bottom through the transition plate. The lower guide pipe is processed with six 4mm holes, which are used for air inlet. The lining is installed on the stepped hole of the inner wall of the extension pipe, which is used for heat preservation and reduces the fluctuation of bare fiber.

[0009] The mass flow meters are provided with four, which are mass flow meter MF1, mass flow meter MF2, mass flow meter MF3 and mass flow meter MF4. The air is inhaled through the mass flow meter MF1, mass flow meter MF2 and mass flow meter MF3, and is exhausted through the mass flow meter MF4. The cavity A is formed between the upper air guide ring and the upper air plate, the cavity B is formed between the lower air guide ring and the upper water jacket, and the cavity C is formed between the lower guide pipe and the lower cover plate.

[0010] A method for air inlet and outlet of graphite parts of an induction furnace, characterized in that it comprises the following steps: Step one: the cavity A is formed between the upper air guide ring and the upper air plate, argon gas enters the cavity A through the two symmetric air inlets of the mass flow meter MF1 and the upper air plate, and then enters the inside of the furnace body through the 1mm gap; Step two: the cavity C is formed between the lower guide pipe and the lower cover plate, argon gas enters the cavity C through the air inlets of the mass flow meter MF2 and the lower cover plate, and then enters the inside of the furnace body uniformly through the holes on the lower guide pipe, argon gas passes through the mass flow meter MF3, and then enters the inside of the furnace body uniformly through the obliquely upward air inlets at the bottom of the extension pipe; Step two: the cavity B is formed between the lower gas ring and the upper water jacket, the internal exhaust of the furnace body enters the cavity B uniformly through the gap between the upper gas ring and the lower gas ring, and then passes through the exhaust hole on the upper water jacket, the filter core, the mass flow meter MF4, the pump and the buffer tank respectively.

[0011] Compared with the closest prior art, the technical scheme provided by the application has the following beneficial effects: 1. The exhaust structure is designed on the air intake and exhaust system, the amount of ash in the internal furnace body taken out from the bottom outlet of the extension pipe along the optical fiber is reduced, the ash is discharged from the upper outlet, and therefore the marking rate is improved; cavity A, cavity B and cavity C are arranged, so that the air intake and exhaust in the furnace are uniform. 2. The graphite piece of the induction furnace is built in the structure of pump+buffer tank+fan, the upper and lower limits of the buffer tank are controlled, and the air intake and exhaust balance in the internal furnace body is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 It is a general structure diagram of the graphite piece of the induction furnace.

[0013] Figure 2 It is a local view of cavity A and B.

[0014] Figure 3 It is a local view of cavity C.

[0015] 1, optical rod, 2, upper cover plate, 3, upper air plate, 4, upper water jacket, 5, upper flange, 6, furnace body, 7, coil, 8, quartz bottom plate, 9, lower cover plate, 10, transition plate, 11, extension pipe, 12, upper gas ring, 13, lower gas ring, 14, center, 15, bottom support, 16, lower guide pipe, 17, inner lining, 18, mass flow meter MF1, 19, mass flow meter MF2, 20, mass flow meter MF3, 21, mass flow meter MF4, 22, filter core, 23, pump, 24, buffer tank, 25, fan, 26, argon, 27, differential pressure table. DETAILED DESCRIPTION

[0016] The technical scheme in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0017] As shown in the drawings, Figure 1 ​The metal furnace body is sequentially provided with an upper cover plate 2, an upper air plate 3, an upper water jacket 4, an upper flange 5, a furnace body 6, a lower cover plate 9, a transition plate 10 and an extension pipe 11 from top to bottom. The components are installed in a concentric manner through positioning steps. The components are processed with water cavities and are provided with cooling water. The depth of the water cavity of the lower cover plate is greater than or equal to 20 mm to prevent deformation.

[0018] The upper air plate 3 is processed with three horizontal 6 mm holes which are distributed at an interval of 90 degrees. Two of the holes are symmetrically used for air inlet, and the other hole is used for installing a differential pressure gauge. The upper water jacket 4 is processed with two horizontal 10 mm holes which are symmetrically distributed and used for air outlet. The lower cover plate 9 is processed with four horizontal 6 mm holes which are uniformly distributed in a circle and used for air inlet. The bottom fiber outlet of the extension pipe 11 is a horn mouth and is processed with two obliquely upward 6 mm holes which are used for air inlet. The inner wall of the upper end of the extension pipe 11 is processed with a stepped hole with a depth of 300-400 mm which is used for installing a graphite inner liner 17. The upper air plate 4 is processed with a bevel at the stepped position which is used for installing an upper air guide ring 12 to ensure concentricity.

[0019] The graphite components include the upper air guide ring 12, a lower air guide ring 13, a center pipe 14, a bottom support 15, a lower guide pipe 16 and the inner liner 17. The bottom support 15 is installed on the lower cover plate 9 and has a contact surface of less than or equal to 3 mm to prevent local deformation of the lower cover plate 9 due to heat. The center pipe 14 is installed in the bottom support 15 through a stepped positioning. The lower air guide ring 13 is embeddedly installed in the inner wall of the center pipe 14 and is installed on the positioning step of the upper water jacket 4. After installation, the gap between the lower air guide ring 13 and the bottom surface of the upper air plate 3 is 3-4 mm. The upper air guide ring 12 and the upper air plate 3 are embeddedly installed through a bevel to ensure concentricity. The gap between the outer wall of the upper air guide ring 12 and the outer wall of the upper air plate 3 is 1 mm to prevent the upper air guide ring 12 from being broken due to thermal expansion. After installation, the gap between the upper air guide ring 12 and the bottom of the upper cover plate 4 is 1-1.5 mm, and the gap between the upper air guide ring 12 and the lower air guide ring 13 is 4 mm. The lower guide pipe 16 is installed on the positioning step of the lower cover plate 9 and is fixed through the transition plate 10. The lower guide pipe 16 is processed with six 4 mm holes which are used for air inlet. The inner liner 17 is installed on the step of the inner wall of the extension pipe 11 and is used for heat preservation and reducing the fluctuation of bare fiber.

[0020] The quartz bottom plate 8 is installed inside the furnace body 6. The coil 7 is installed on the quartz bottom plate 8 and outside the center pipe 14. The optical rod 1 is inserted into the inner side of the graphite components. The optical rod 1, the graphite components, the coil 7 and the metal furnace body are kept concentric through installation and adjustment.

[0021] wherein Figure 1 , Figure 2 and Figure 3As shown, the cavity A is formed between the upper gas guide ring 12 and the upper gas plate 3, the argon gas 26 enters the cavity A through the mass flow meter MF1 18 and the two symmetrical gas inlets of the upper gas plate 3, and then evenly enters the inside of the furnace body 6 through the 1mm gap. The cavity B is formed between the lower gas guide ring 13 and the upper water jacket 4, the exhaust gas in the furnace enters the cavity B evenly through the gap between the upper gas guide ring 12 and the lower gas guide ring 13, and then passes through the filter core 22, the mass flow meter MF4 21, the pump 23 and the buffer tank 24 through the exhaust holes of the upper water jacket 4 in sequence. The buffer tank 24 controls the upper and lower limits of the pressure in the tank through the fan 25, so as to keep the pressure in the furnace body 6 balanced. The cavity C is formed between the lower guide pipe 16 and the lower cover plate 9, the argon gas 26 enters the cavity C through the mass flow meter MF2 19 and the gas inlet of the lower cover plate 9, and then evenly enters the inside of the furnace body 6 through the holes on the lower guide pipe 16. The argon gas 26 enters the inside of the furnace body 6 evenly through the inclined upward gas inlet hole at the bottom of the extension pipe through the mass flow meter MF3 20. The differential pressure gauge 27 is installed on the gas hole of the upper gas plate 3, which is used to adjust the flow settings of the mass flow meters MF1 18, MF2 19, MF3 20 and MF4 21, so as to keep the micro positive pressure in the furnace 6.

[0022] The above examples are only used to illustrate the technical solutions of the present application, but not to limit it. Although the present application has been described in detail with reference to the above examples, the ordinary skilled in the art can still modify or equivalently replace the specific embodiments of the present application without departing from the spirit and scope of the present application. Any modification or equivalent replacement without departing from the spirit and scope of the present application is within the protection scope of the claims of the application.

Claims

1. A graphite component for an induction furnace, comprising a light rod (1), a coil (7), a quartz base plate (8), a filter element (22), a pump (23), a buffer tank (24), a fan (25), an argon gas generator (26), a differential pressure gauge (27), and a mass flow meter, characterized in that: It also includes a metal furnace body structure, a graphite component structure, and an air intake and exhaust system; the light rod (1) is inserted into the inside of the graphite component structure, the coil (7) is installed on the quartz base plate (8), the buffer tank (24) controls the upper and lower limits of the tank pressure through the fan (25), and the differential pressure gauge (27) is installed on the air hole of the upper air plate (3); the air intake and exhaust system is an upper exhaust structure, including cavity A, cavity B, and cavity C, cavity A and cavity C are air intake chambers, and cavity B is an exhaust chamber.

2. The graphite component for an induction furnace according to claim 1, characterized in that: The metal furnace body structure includes, from top to bottom, an upper cover plate (2), an upper gas plate (3), an upper water jacket (4), an upper flange (5), a furnace body (6), a lower cover plate (9), a transition plate (10), and an extension pipe (11). Each component is fixed together by a positioning step and a sealing ring bolt.

3. The graphite component for an induction furnace according to claim 2, characterized in that: Each component of the metal furnace body structure is machined with a water cavity, through which cooling water is supplied, and the water cavity depth of the lower cover plate (9) is ≥20mm.

4. The graphite component for an induction furnace according to claim 2, characterized in that: The upper air plate (3) has three horizontal 6mm holes, which are distributed at 90-degree intervals, two of which are symmetrical. The upper air plate (3) has a bevel at the step. The upper water jacket (4) has two horizontal 10mm holes, which are symmetrically distributed. The lower cover plate (9) has four horizontal 6mm holes, which are evenly distributed around the circumference. The bottom fiber outlet of the extension tube (11) is a flared mouth, and two 6mm holes are machined upwards. The upper inner wall of the extension tube (11) has a stepped hole with a depth of 300-400mm, which is used to install the inner lining (17).

5. The graphite component for an induction furnace according to claim 1, characterized in that: The graphite component structure includes an upper air guide ring (12), a lower air guide ring (13), a central tube (14), a base (15), a lower guide tube (16), and an inner liner (17). The upper air guide ring (12) and the upper air plate (3) are installed by bevel embedding. The lower air guide ring (13) is embedded in the inner wall of the central tube (14). The base (15) is installed on the lower cover plate (9). The central tube (14) is positioned and installed on the base (15) by a step. The lower guide tube (16) is installed on the positioning step of the lower cover plate (9). The inner liner (17) is installed on the step on the inner wall of the extension tube (11).

6. The graphite component of an induction furnace according to claim 5, characterized in that: The upper air guide ring (12) and the upper air plate (3) are installed by bevel embedding to ensure concentricity. The gap between the outer wall of the upper air guide ring (12) and the upper air plate (3) is 1mm, the gap between the upper air guide ring (12) and the bottom of the upper cover plate (2) is 1-1.5mm, and the gap between the upper air guide ring (13) and the lower air guide ring (13) is 4mm. The upper end of the lower air guide ring (13) abuts against the positioning step of the upper water jacket (4), and the gap between the lower air plate (3) and the bottom surface is 3-4mm. The contact surface between the bottom support (15) and the lower cover plate (9) is ≤3mm. The lower guide tube (16) is installed on the positioning step of the lower cover plate (9). The bottom of the lower guide tube (16) is fixed by the transition plate (10). The tube body of the lower guide tube (16) has 6 holes of 4mm.

7. The graphite component for an induction furnace according to claim 1, characterized in that: The buffer tank controls the upper and lower limits of the internal pressure through a blower to maintain the pressure balance inside the furnace; the differential pressure gauge is installed on the air hole of the upper air plate to adjust the flow setting of the mass flow meter and maintain a slight positive pressure inside the furnace.

8. The graphite component of an induction furnace according to claim 1, characterized in that: The mass flow meter is provided with four units, namely mass flow meter MF1 (18), mass flow meter MF2 (19), mass flow meter MF3 (20), and mass flow meter MF4 (21). Air is introduced through mass flow meter MF1 (18), mass flow meter MF2 (19), and mass flow meter MF3 (20), and exhaust is produced through mass flow meter MF4 (21). The upper air guide ring (12) and the upper air plate (3) form a cavity A, the lower air guide ring (13) and the upper water jacket (4) form a cavity B, and the lower guide pipe (16) and the lower cover plate (9) form a cavity C.

9. A method for air intake and exhaust of a graphite component in an induction furnace as described in claim 8, characterized in that, Includes the following steps: Step 1: Cavity A is formed between the upper gas guide ring (12) and the upper gas plate (3). Argon gas (26) enters cavity A through the mass flow meter MF1 (18) and the two symmetrical gas inlets of the upper gas plate (3), and then enters the furnace body (6) through a 1mm gap. Step 2: A cavity C is formed between the lower guide tube (16) and the lower cover plate (9). Argon gas (26) enters the cavity C through the mass flow meter MF2 (19) and the air inlet of the lower cover plate (9), and then enters the furnace body (6) evenly through the hole on the lower guide tube (16). Argon gas (26) enters the furnace body (6) evenly through the mass flow meter MF3 (20) and then through the upward-sloping air inlet at the bottom of the extension tube (11). Step 2: A cavity B is formed between the lower air guide ring (13) and the upper water jacket (4). The exhaust gas inside the furnace body (6) enters the cavity B evenly through the gap between the upper air guide ring (12) and the lower air guide ring (13), and then passes through the exhaust hole on the upper water jacket (4) through the filter element (22), mass flow meter MF4 (21), pump (23), and buffer tank (24).

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