Optical fiber preform displacement detection and adjustment system based on electromagnetic induction

Abstract

The invention discloses an optical fiber preform displacement detection and adjustment system based on electromagnetic induction, which relates to the technical field of optical fiber manufacturing and comprises an electromagnetic driving unit, an electromagnetic sensing unit, an electromagnetic detection unit and a main control system, the electromagnetic driving units are symmetrically arranged on the horizontal plane of the upper end of the sealing device, distributed in the circumferential direction and concentric with a furnace opening of the wire drawing furnace, and each electromagnetic driving unit comprises an outer-layer magnet, an inner-layer magnet, a cooling block, a roller and a sliding rail. The electromagnetic sensing unit comprises a magnet, an electromagnetic shielding tube and a uniform magnetic field unit; and the other end of the electromagnetic detection unit is connected with the master control system. According to the invention, under the high-temperature working condition, the concentric state of the preform at the wire drawing furnace mouth can be detected in situ, small-amplitude uniform adjustment is carried out after automatic correction, the wire diameter fluctuation and strength scrap of glass fibers are reduced, the quality and qualified rate of optical fibers are improved, personnel intervention is not needed, the timeliness of displacement adjustment and the operable space of centering are guaranteed, and the production efficiency is improved. And practical production and application are facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of optical fiber manufacturing, and in particular to a system for detecting and adjusting the displacement of an optical fiber preform rod at a furnace mouth of a drawing furnace. Background Art

[0002] The optical fiber preform is melted at high temperature in a graphite drawing furnace filled with an inert atmosphere and drawn into an optical glass fiber. In order to ensure the size and structure of the melt-drawn optical glass fiber are stable, it is necessary to establish a stable drawing furnace thermal field filled with an inert atmosphere and ensure that the preform is evenly heated in the drawing furnace. At present, technicians in this field focus on the sealing and concentricity of the preform at the drawing furnace mouth, which is the key and difficulty of drawing control.

[0003] In order to improve production efficiency and reduce the cost of preform outsourcing, large-sized preforms are more favored by manufacturers. Now the mainstream large-sized preforms prefer the outside vapor deposition (OVD) outsourcing process. However, due to its process characteristics, the larger the size of the OVD outsourcing preform, the greater the fluctuation of its rod diameter, which leads to greater challenges for the preform at the furnace mouth. During the drawing process, the temperature in the furnace is about 2000℃. When oxygen enters, the graphite parts are easily oxidized with it, resulting in burning and the decline of optical fiber quality.

[0004] At present, technicians in this field have proposed a variety of furnace mouth sealing solutions. For example, reference patent CN103269990B and patent CN216711931U respectively introduce that the sealing auxiliary parts such as the spring components and extrusion air rings mentioned in the setting structure are used to strengthen the sealing of the preform rod at the furnace mouth; for the sealing control of the preform rod at the furnace mouth, the sealing devices introduced in reference patent CN216711931U and patent application CN106219963A both include a diameter gauge device, which is installed above the sealing assembly to monitor the changes in the outer diameter of the preform rod and guide the furnace mouth sealing device to adjust the sealing state.

[0005] The sealing innovations mentioned in the above patent application, such as using springs, extruded air rings or implementing dynamic sealing based on preset rod diameter measurements, can solve the problem of gap filling at the drawing furnace mouth, but these strategies are all uniform filling along the circumference of the preform rod, based on the premise that the preform rod continues to maintain a good vertical concentric state in the drawing furnace. Usually in actual drawing production, with the fluctuation of rod diameter and the change of the center of gravity of the preform rod, the concentricity of the preform rod and the furnace mouth will change dynamically. At present, when drawing, each optical fiber factory adjusts the concentricity of the preform rod at the furnace mouth, mostly relying on the operator to observe the offset state of the preform rod at the furnace mouth, and implement the preform rod centering based on their experience. Moreover, the centering action is often relatively lagging, and it is difficult to detect and adjust in real time; and as the drawing process proceeds, the difficulty of centering adjustment will become increasingly greater. Summary of the invention

[0006] The embodiment of the present invention provides an optical fiber preform displacement detection and adjustment system based on electromagnetic induction, which can not only realize non-contact high-temperature sensing, but also make the centering action faster and the operating space larger, so as to realize timely and effective adjustment of the vertical concentricity of the preform and the drawing furnace.

[0007] The present invention provides an optical fiber preform displacement detection and adjustment system based on electromagnetic induction, comprising: an electromagnetic driving unit, an electromagnetic sensing unit, an electromagnetic detection unit and a main control system;

[0008] The electromagnetic drive units are symmetrically arranged in sequence on the upper horizontal plane of the sealing device, distributed along the circumference of the sealing device, and concentric with the furnace opening of the wire drawing furnace;

[0009] The electromagnetic driving unit is used to transmit the force generated by the deviation to the electromagnetic sensing unit when the concentricity of the optical fiber preform is deviated during its travel;

[0010] The electromagnetic sensing unit is used to generate a changing magnetic flux under the force transmitted by the electromagnetic driving unit;

[0011] The electromagnetic detection unit is used to detect the changing magnetic flux and send an electromagnetic signal to the main control system;

[0012] The main control system is used to calculate the magnetic flux change value according to the electromagnetic signal, convert the magnetic flux change value into a current signal and send it to the electromagnetic driving unit, so that the electromagnetic driving unit pushes the optical fiber preform rod to return to the initial point.

[0013] In some examples, the electromagnetic drive unit includes: an outer magnet, an inner magnet, a cooling block, a roller, and a slide rail;

[0014] The outer magnet is arranged on the horizontal plane of the upper end of the sealing device, and the slide rail is arranged on the horizontal plane of the upper end of the sealing device. In the radial direction formed by the outer magnet and the center of the drawing furnace mouth, the cooling block is arranged on the slide rail, and can realize free reciprocating motion on the slide rail under the action of external force. The inner magnet and the outer magnet face each other but have the same magnetic properties. The inner magnet is connected to the side of the cooling block facing away from the center of the drawing furnace mouth. The roller is installed on the side of the cooling block facing the center of the drawing furnace mouth, inserted from one end to the other end, and horizontally penetrates the cooling block. The outer magnet can drive the inner magnet, linking the cooling block and the roller to move toward each other at the same time.

[0015] In some examples, the electromagnetic sensing unit includes: a magnet, an electromagnetic shielding tube, and a uniform magnetic field unit;

[0016] One side of the magnet is opposite to the front side of the inner magnet, but has the same magnetic properties; the other side of the magnet is located in the uniform magnetic field unit and is concentric with the axis of the electromagnetic shielding tube. The magnet and the uniform magnetic field unit are both installed in the electromagnetic shielding tube, and the inner magnet can drive the magnets to move toward each other in the uniform magnetic field unit.

[0017] In some instances, one end of the electromagnetic detection unit is connected to the uniform magnetic field unit, and the other end is connected to the main control system. The electromagnetic detection unit detects changes in electromagnetic signals within the uniform magnetic field unit and transmits the detected electromagnetic signals to the main control system.

[0018] In some instances, the main control system receives the electromagnetic signal transmitted by the electromagnetic detection unit, adjusts the current acting on the outer magnet in real time, and then achieves the distance offset between the outer magnet and the inner magnet by changing the magnetic field strength of the outer magnet, and links the cooling block to act on the roller to adjust the vertical and concentric state of the optical fiber preform rod in the furnace mouth plane.

[0019] In some examples, the sealing device is installed above a furnace opening of a wire drawing furnace.

[0020] In some examples, the outer magnet is a fixed structure.

[0021] In some examples, the inner magnet is directly connected to the cooling block, or the inner magnet is embedded in the cooling block, or the inner magnet is wrapped by the cooling block.

[0022] In some instances, the main control system is also used to set an initial point position, wherein the optical fiber preform is placed in a vertical and stable equilibrium state concentric with the electromagnetic drive unit, and the magnetic flux acting on the uniform magnetic field unit and the current information on the outer magnet are used as the initial point position of the electromagnetic drive unit.

[0023] In some instances, the main control system is also used to adjust the current acting on the outer magnet in real time, thereby achieving a spacing offset between the outer magnet and the inner magnet by changing the magnetic field strength of the outer magnet, and linking the cooling block to act on the roller to evenly push the optical fiber preform rod back to the initial position with a small amplitude.

[0024] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0025] The preform displacement detection and adjustment system and method provided by the present invention are based on non-contact electromagnetic sensing. Through the construction of a multi-layer electromagnetic induction drive unit, not only can the concentricity of the preform and the furnace mouth of the wire drawing furnace be detected in situ, but also when the preform is tilted at the furnace mouth, the system can detect and automatically center the preform to ensure that the preform is vertical and concentric with the furnace mouth of the wire drawing furnace. In addition, this system and method do not require human intervention, improve the timeliness and operability of displacement adjustment, and are conducive to actual production applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 It is a schematic diagram of a displacement detection and adjustment system for an optical fiber preform at a drawing furnace mouth provided by an embodiment of the present invention;

[0028] Figure 2 is a semi-sectional schematic diagram of an electromagnetic drive assembly provided by an embodiment of the present invention;

[0029] Among them, 1 is the outer magnet, 2 is the inner magnet, 3 is the cooling block, 4 is the roller, 5 is the slide rail, 6 is the magnet, 7 is the electromagnetic shielding tube, 8 is the uniform magnetic field unit, 9 is the electromagnetic detection unit, 10 is the main control system, 11 is the rod hanging mechanism, 12 is the optical fiber preform rod, 13 is the sealing device, and 14 is the drawing furnace. DETAILED DESCRIPTION

[0030] 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 those skilled in the art without creative work are within the scope of protection of the present invention.

[0031] In the following description, specific embodiments of the present invention will be described with reference to steps and symbols performed by one or more computers, unless otherwise specified. Therefore, these steps and operations will be mentioned several times as being performed by a computer, and computer execution referred to herein includes operations by a computer processing unit of electronic signals representing data in a structured form. This operation converts the data or maintains it at a location in the computer's memory system, which can be reconfigured or otherwise change the operation of the computer in a manner familiar to testers in the field. The data structure maintained by the data is a physical location in the memory, which has specific characteristics defined by the data format. However, the principles of the present invention are described in the above text, which does not represent a limitation, and testers in the field will understand that the following various steps and operations can also be implemented in hardware.

[0032] The term "module" or "unit" used herein can be regarded as a software object executed on the computing system. The different components, modules, engines and services in this article can be regarded as implementation objects on the computing system. The apparatus and method in this article are preferably implemented in software, but can also be implemented in hardware, all within the scope of protection of the present invention.

[0033] Those skilled in the art will appreciate that, unless expressly stated otherwise, the singular forms "a", "an", "" and "the" used herein may also include the plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other elements, or there may be intermediate elements. In addition, "connected" or "coupled" as used herein may include wireless connections or wireless couplings. The term "and / or" as used herein includes all or any unit and all combinations of one or more associated listed items.

[0034] In the first embodiment of the present invention, in order to solve the problem of concentricity deviation of the preform in the wire drawing furnace in the prior art, a non-contact high temperature resistant sensing displacement detection and adjustment system is provided, comprising:

[0035] At least one layer of electromagnetic drive units is coaxial with the upper port of the drawing furnace, and several groups of electromagnetic drive units are symmetrically and evenly distributed in the circumferential direction; the electromagnetic drive unit includes an outer magnet 1, an inner magnet 2, a cooling block 3, a roller 4 and a slide rail 5. The outer magnet 1 is arranged on the upper horizontal plane of the sealing device 13 and is a fixed structure. The slide rail 5 is arranged on the upper horizontal plane of the sealing device 13, in the radial direction formed by the outer magnet 1 and the center of the drawing furnace mouth. The cooling block 3 is arranged on the slide rail 5 and can realize free reciprocating motion on its track under the action of external force. The inner magnet 2 and the outer magnet 1 face each other but have the same magnetic properties. The inner magnet 2 is connected to the side of the cooling block 3 that is away from the center of the drawing furnace mouth. It can be directly connected to the cooling block 3, or embedded in or wrapped, all of which are suitable for the present invention. During normal production, the inner magnet 2 is not affected by high temperature, and the magnetism of the inner magnet 2 remains stable; the roller 4 is installed on the side of the cooling block 3 facing the center of the drawing furnace mouth, inserted from one end to the other end, and horizontally penetrates the cooling block 3. During the movement of the optical fiber preform 12, the roller 4 can realize self-rotation along its central axis. The high-temperature resistant rigid materials involved in the prior art, such as SiC, SiO2 and N4Si3, are all suitable for the present invention;

[0036] An electromagnetic sensing unit, the electromagnetic sensing unit includes a magnet 6, an electromagnetic shielding tube 7 and a uniform magnetic field unit 8. One side of the magnet 6 is opposite to the front side of the inner magnet 2, but has the same magnetic properties; the other side is located in the uniform magnetic field unit 8, and is concentric with the axis of the electromagnetic shielding tube 7, and can freely reciprocate inside it. When the inner magnet 2 deviates in the direction away from the center of the drawing furnace mouth, the repulsive force between the magnet 6 and the inner magnet 2 changes, driving the magnet 6 to move toward the other end of the electromagnetic shielding tube 7, that is, the length of the magnet 6 in the uniform magnetic field unit 8 changes;

[0037] One side of the electromagnetic detection unit 9 is connected to the electromagnetic sensor unit, and the other side is connected to the main control system 10. The electromagnetic detection unit 9 detects the change of the electromagnetic signal in the uniform magnetic field unit 8, and transmits the detected signal to the main control system 10. The main control system 10 receives the signal transmitted by the electromagnetic detection unit 9, adjusts the current acting on the outer magnet 1 in real time, and then realizes the spacing offset between the outer magnet 1 and the inner magnet 2 by changing the magnetic field strength of the outer magnet 1, and links the cooling block 3 to act on the roller 4 to adjust the vertical and concentric state of the preform in the furnace mouth plane.

[0038] In the second embodiment of the present invention, referring to Figure 1The embodiment of the present invention provides an optical fiber preform displacement detection and adjustment system based on electromagnetic induction. In the embodiment, a plurality of groups of electromagnetic drive units are circumferentially symmetrically distributed on the upper horizontal plane of a sealing device 13 concentric with the furnace mouth of a drawing furnace 12. The tail end of the optical fiber preform 12 is installed on a rod hanging mechanism 11. Starting from the cone head, it passes through an annular area composed of a plurality of electromagnetic drive units from bottom to top. The sealing device 13 enters the drawing furnace 14 and stops after traveling a preset distance. The main control system 10 is turned on. The relative position of the electromagnetic drive unit and the preform 12 is preset on the upper end surface of the furnace mouth, so that the preform is in a vertical and stable equilibrium state concentric with the electromagnetic drive unit. At this time, the magnetic flux acting on the uniform magnetic field unit 8 and the current information on the outer magnet 1 are used as the initial point position of the electromagnetic drive unit and are preset in the main control system 10.

[0039] After the wire drawing starts, the preform rod 12 gradually enters the wire drawing furnace 14 at a preset speed. When the real-time rod diameter at the furnace mouth changes, the concentricity of the preform rod 12 in the annular area formed by the electromagnetic drive unit is offset. When the corresponding roller 4 in the offset direction receives the force generated by the continuous offset of the preform rod 12, it is transmitted to the cooling block 3, driving the inner magnet 2 to move away from the center of the wire drawing furnace mouth. The distance between the magnet 6 and the inner magnet 2 is shortened, and the mutual repulsion force is enhanced. The driving magnet 6 begins to move from the initial point to the other end of the electromagnetic shielding tube 7, that is, the induction area of ​​the magnet 6 in the uniform magnetic field module 8 becomes larger, and the magnetic flux in the uniform magnetic field module 8 begins to change. The electromagnetic detection unit 9 detects the fluctuating magnetic flux and sends an electromagnetic signal to the main control system 10 to calculate and display the magnetic flux change value. Subsequently, the main control system 10 converts it into a current signal, and continuously adjusts the current intensity injected into the outer magnet 1 according to the preset amplitude. The magnetic field intensity of the outer magnet 1 changes, and the repulsive force increases at this time, so that the original relative displacement between the outer magnet 1 and the inner magnet 2 changes, thereby driving the inner magnet 2 to move in the direction close to the center of the furnace mouth of the drawing furnace 14. The continuously generated force is applied to the cooling block 3, and the linkage roller 4 moves, pushing the preform 12 back to the initial point position with a small amplitude and uniformity, completing the real-time detection and adjustment of its displacement change. As the preform gradually enters the drawing furnace, the outer diameter and offset state at the furnace mouth change, and the main control system dynamically controls the process of displacement detection and adjustment in real time until the effective part of the preform completely enters the drawing furnace 14.

[0040] The embodiment of the present invention provides an electromagnetic induction-based optical fiber preform displacement detection and adjustment system. It can simply and reliably adjust the relative displacement between the optical fiber preform and the furnace mouth of the drawing furnace through electromagnetic control, and effectively improve the vertical and concentric state of the optical fiber preform at the furnace mouth of the drawing furnace. The system includes an electromagnetic drive unit, an electromagnetic sensor unit, an electromagnetic detection unit and a main control system. Figure 2As shown, the electromagnetic drive unit is symmetrically arranged on the upper horizontal plane of the sealing device 13 in sequence, distributed along its circumference, and concentric with the furnace mouth of the wire drawing furnace. The sealing device 13 is installed above the furnace mouth of the wire drawing furnace 14. The electromagnetic drive unit includes an outer magnet 1, an inner magnet 2, a cooling block 3, a roller 4 and a slide rail 5. The outer magnet 1 is arranged on the upper horizontal plane of the sealing device 13, is a fixed structure, and is connected to the main control system 10. The slide rail 5 is arranged on the upper horizontal plane of the sealing device 13, in the radial direction formed by the outer magnet 1 and the center of the drawing furnace mouth. The cooling block 3 is installed on the slide rail 5 and can reciprocate when driven by external force. The inner magnet 2 is connected to the side of the cooling block 3 facing away from the center of the furnace mouth. The roller 4 is horizontally built into the side of the cooling block 3 facing the center of the furnace mouth. The outer magnet 1 can drive the inner magnet 2, and the linkage cooling block 3 and the roller 4 move toward each other at the same time. The electromagnetic sensing unit includes a magnet 6, an electromagnetic shielding tube 7 and a uniform magnetic field unit 8. One end of the magnet 6 is placed in the uniform magnetic field unit 8, and the other end is opposite to the inner magnet 2, but has the same magnetic properties. The magnet 6 and the uniform magnetic field unit 8 are both installed in the electromagnetic shielding tube 7, and the inner magnet 2 can drive the magnet 6 to move toward each other in the uniform magnetic field unit 8. One end of the electromagnetic detection unit 9 is connected to the uniform magnetic field unit 8, and the other end is connected to the main control system 10. The displacement detection and adjustment system and method provided by the system can detect the concentric state of the preform rod at the drawing furnace mouth in situ under high-temperature working conditions, and make small and uniform adjustments after automatic calibration, thereby reducing the wire diameter fluctuation and strength scrapping of the glass fiber, and improving the quality and qualified rate of the optical fiber; in addition, the system does not require human intervention, ensures the timeliness of displacement adjustment and the operable space for centering, and is conducive to actual production applications.

[0041] The above is a detailed introduction to an optical fiber preform displacement detection and adjustment system based on electromagnetic induction provided by an embodiment of the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. An optical fiber preform displacement detection and adjustment system based on electromagnetic induction, characterized in that: include: Electromagnetic drive unit, electromagnetic sensor unit, electromagnetic detection unit and main control system; The electromagnetic drive units are symmetrically arranged in sequence on the upper horizontal plane of the sealing device, distributed along the circumference of the sealing device, and concentric with the furnace opening of the wire drawing furnace; The electromagnetic driving unit is used to transmit the force generated by the deviation to the electromagnetic sensing unit when the concentricity of the optical fiber preform is deviated during its travel; The electromagnetic sensing unit is used to generate a changing magnetic flux under the force transmitted by the electromagnetic driving unit; The electromagnetic detection unit is used to detect the changing magnetic flux and send an electromagnetic signal to the main control system; The main control system is used to calculate the magnetic flux change value according to the electromagnetic signal, convert the magnetic flux change value into a current signal and send it to the electromagnetic driving unit, so that the electromagnetic driving unit pushes the optical fiber preform rod to return to the initial point.

2. The system according to claim 1, characterized in that The electromagnetic drive unit comprises: an outer magnet, an inner magnet, a cooling block, a roller and a slide rail; The outer magnet is arranged on the horizontal plane of the upper end of the sealing device, and the slide rail is arranged on the horizontal plane of the upper end of the sealing device. In the radial direction formed by the outer magnet and the center of the drawing furnace mouth, the cooling block is arranged on the slide rail, and can realize free reciprocating motion on the slide rail under the action of external force. The inner magnet and the outer magnet face each other but have the same magnetic properties. The inner magnet is connected to the side of the cooling block facing away from the center of the drawing furnace mouth. The roller is installed on the side of the cooling block facing the center of the drawing furnace mouth, inserted from one end to the other end, and horizontally penetrates the cooling block. The outer magnet can drive the inner magnet, linking the cooling block and the roller to move toward each other at the same time.

3. The system according to claim 2, characterized in that The electromagnetic sensing unit comprises: a magnet, an electromagnetic shielding tube and a uniform magnetic field unit; One side of the magnet is opposite to the front side of the inner magnet, but has the same magnetic properties; the other side of the magnet is located in the uniform magnetic field unit and is concentric with the axis of the electromagnetic shielding tube. The magnet and the uniform magnetic field unit are both installed in the electromagnetic shielding tube, and the inner magnet can drive the magnets to move toward each other in the uniform magnetic field unit.

4. The system according to claim 3, characterized in that One end of the electromagnetic detection unit is connected to the uniform magnetic field unit, and the other end is connected to the main control system. The electromagnetic detection unit detects the change of the electromagnetic signal in the uniform magnetic field unit and transmits the detected electromagnetic signal to the main control system.

5. The system according to claim 4, characterized in that The main control system receives the electromagnetic signal transmitted by the electromagnetic detection unit, adjusts the current acting on the outer magnet in real time, and then realizes the spacing offset between the outer magnet and the inner magnet by changing the magnetic field strength of the outer magnet, and links the cooling block to act on the roller to adjust the vertical and concentric state of the optical fiber preform rod in the furnace mouth plane.

6. The system according to claim 1, characterized in that The sealing device is installed above the furnace opening of the wire drawing furnace.

7. The system according to claim 2, characterized in that The outer magnet is a fixed structure.

8. The system according to claim 7, characterized in that The inner layer magnet is directly connected to the cooling block, or the inner layer magnet is embedded in the cooling block, or the inner layer magnet is wrapped by the cooling block.

9. The system according to any one of claims 2 to 8, characterized in that: The main control system is also used to set the initial point position, wherein the optical fiber preform is placed in a vertical and stable equilibrium state concentric with the electromagnetic drive unit. At this time, the magnetic flux acting on the uniform magnetic field unit and the current information on the outer magnet are used as the initial point position of the electromagnetic drive unit.

10. The system according to claim 9, characterized in that The main control system is also used to adjust the current acting on the outer magnet in real time, thereby changing the magnetic field strength of the outer magnet to achieve the distance offset between the outer magnet and the inner magnet, and linking the cooling block to act on the roller to push the optical fiber preform rod back to the initial point evenly with a small amplitude.

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