Optical Fiber Preform Concentricity Adjustment Component and Adjustment Method

Abstract

Fiber preform concentricity adjustment assembly and adjustment method, which relate to the technical field of fiber preform processing and are used to solve the concentricity problem between the fiber preform and the fixture. It includes a detection unit and an adjustment unit. The detection unit includes a support mechanism, a base, a conversion mechanism, and a follower mechanism arranged in sequence from bottom to top. There are two groups of fixed conductive posts on the base. There are contact pieces on the fixed conductive posts. There is a resistor, a power supply, and a current sensor between the symmetric fixed conductive posts. The conversion mechanism includes swing rods, movable conductive posts, and a first connecting rod. The swing rods are two cross - arranged ones. The movable conductive posts are located at the lower ends of the swing rods, and the two movable conductive posts are electrically connected. The follower mechanism includes a follower rod and a guide block. The upper end of the follower rod has a follower wheel. The movable conductive posts, fixed conductive posts, contact pieces, resistor, power supply, and current sensor form an electric current loop. The adjustment unit includes a crank - rocker mechanism and a flexible knocking rod. The present invention can accurately and quickly adjust the concentricity of the fiber preform.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber preform processing, and specifically to a concentricity adjustment assembly and adjustment method for an optical fiber preform. Background Art

[0002] An optical fiber preform is a raw material for manufacturing optical fibers. Before wire drawing, handles need to be welded to both ends of the optical fiber preform to facilitate clamping of the optical fiber preform. When welding the handles, first, one end of the optical fiber preform is clamped by the three-jaw chuck of the welding equipment. As Figure 1 shown, a gasket 12 is placed between the jaw 11 of the three-jaw chuck 1 and one end of the optical fiber preform to prevent the optical fiber preform from being damaged. After the optical fiber preform is clamped on the three-jaw chuck 1, the optical fiber preform may be in a concentric state 2 with the three-jaw chuck 1, or may be in an eccentric state 21 with the three-jaw chuck 1. After the optical fiber preform is clamped, first, the concentricity of the optical fiber preform is detected. After detecting the eccentricity problem of the optical fiber preform, the existing adjustment method is as follows: Workers tap the other end of the optical fiber preform with their fists to adjust and correct the eccentricity, and then the concentricity is detected again; if it is found that the optical fiber preform is still eccentric, continue to tap with fists until the optical fiber preform is concentric with the three-jaw chuck. Under the above concentricity adjustment method of the optical fiber preform, the tapping force of the worker's fist on the optical fiber preform is limited, and the adjustment process needs to be carried out multiple times to achieve concentricity, and the operation levels of different workers are different. Summary of the Invention

[0003] The purpose of the present invention is to provide a concentricity adjustment assembly and adjustment method for an optical fiber preform, which are used to solve the problems of low efficiency and uneven concentricity after adjustment in the existing concentricity adjustment method between an optical fiber preform and a fixture.

[0004] The technical solution adopted by the present invention to solve its technical problems is: an optical fiber preform concentricity adjustment assembly, including a detection unit and an adjustment unit. The detection unit includes a support mechanism, a base, a conversion mechanism, and a follower mechanism arranged in sequence from bottom to top. The fixed part of the support mechanism is fixedly connected to the welding equipment foundation or the ground, and the movable part of the support mechanism is fixedly connected to the base. The support mechanism drives the base to move up and down. There are two groups of fixed conductive columns on the base, and a contact piece is fixed on the fixed conductive column. The two groups of fixed conductive columns are symmetrically arranged, and there is a resistor, a power supply, and a current sensor between the two symmetric fixed conductive columns. The resistance values between the symmetrically arranged two fixed conductive columns are different. The conversion mechanism includes a swing rod, a movable conductive column, and a first connecting rod. The swing rods are two cross - arranged ones, and the upper ends of the two swing rods are hinged. The movable conductive column is located at the lower end of the swing rod, and the movable conductive columns on the two swing rods are electrically connected. The follower mechanism includes a follower rod and a guide block. The follower rod is slidably connected to the guide block in the vertical direction. The upper end of the follower rod has a follower wheel for contacting the bottom of the optical fiber preform. The first connecting rod is located between the lower end of the follower rod and the upper end of the swing rod. When the follower rod moves up and down, it drives the swing rod to swing through the first connecting rod, so that the movable conductive column at the lower end of the swing rod contacts or separates from the contact piece. When the movable conductive column contacts the contact piece, the movable conductive column, the fixed conductive column, the contact piece, the resistor, the power supply, and the current sensor form a current loop. The current sensor is signal - connected to the PLC controller.

[0005] The adjustment unit includes a crank - rocker mechanism and a flexible knocking rod. The base of the crank - rocker mechanism is fixedly connected to the welding equipment, and the rocker of the crank - rocker mechanism is fixedly connected to the knocking rod. The PLC controller controls the action of the crank - rocker mechanism.

[0006] Further, the fixed part of the support mechanism is a support seat, and the movable part of the support mechanism includes two groups of support rods. The two support rods in the same group are cross - arranged and hinged. The upper ends of the support rods are hinged with a base ear plate, and the base ear plate is slidably connected to the base. There is a driving module in the support seat for driving the lower ends of the two support rods in the same group to approach or move away from each other.

[0007] Further, the driving module includes a motor fixed in the support seat, a gear located at the output end of the motor, and racks arranged on both sides of the gear and meshing with the gear. The racks are slidably arranged in the support seat, and there are rack ear plates on the racks. The lower ends of the support rods are hinged to the corresponding rack ear plates.

[0008] Further, there is a support plate in the support seat, and the racks are slidably arranged on the upper surface of the support plate.

[0009] Further, the top of the base has a guide rail, and there are two symmetrically arranged arc-shaped grooves on the guide rail. The lower end of the swing rod has a slider, and the slider is slidably arranged in the corresponding arc-shaped groove.

[0010] Further, the two groups of fixed conductive columns correspond to the two arc-shaped grooves one by one. The fixed conductive columns in the same group are arranged at equal intervals along the arc where the corresponding arc-shaped groove is located, and the fixed conductive columns in the same group are connected in parallel; along the direction of the arc where the arc-shaped groove is located, the resistance value of the resistor connected to the fixed conductive columns in the same group gradually increases, and the resistance value of the resistor connected to the fixed conductive column closest to the symmetry point is the largest.

[0011] Further, the side wall of the movable conductive column has mounting ear plates, and there is an elastic arc-shaped conductive sheet between the two mounting ear plates.

[0012] Further, the upper end of the follower rod has a wheel frame, and the follower wheel is rotatably installed on the wheel frame.

[0013] Further, there is a pair of fixed rods between the guide block and the base to realize the relative fixation of the guide block and the base.

[0014] The present invention also provides a method for adjusting the concentricity of an optical fiber preform, including the following steps:

[0015] One end of the optical fiber preform is placed on the three-jaw chuck of the welding equipment;

[0016] The support mechanism is used to drive the follower mechanism to move upward until the follower wheel contacts the bottom of the optical fiber preform;

[0017] The optical fiber preform is driven to rotate. During the first rotation of the optical fiber preform, if the optical fiber preform is eccentric relative to the three-jaw chuck, the current loop is connected and the current sensor detects a set of different magnitudes of current; if the optical fiber preform is concentric with the three-jaw chuck or has a small eccentricity, the current loop remains disconnected and the current sensor does not detect current;

[0018] During the second rotation of the optical fiber preform, when the sensor detects the maximum current in step (2) again, the PLC controller sends a signal to the adjustment unit, and the adjustment unit acts to make the knocking rod knock the other end of the optical fiber preform. The knocking point of the knocking rod and the optical fiber preform is the contact point of the follower wheel and the optical fiber preform when the maximum current is detected by the current sensor;

[0019] During the third rotation of the optical fiber preform, if the current loop continues to be disconnected and the current sensor does not detect current, it indicates that the optical fiber preform and the three-jaw chuck are already concentric; if the current loop continues to be connected and the current sensor continues to detect a set of different magnitudes of current, and the detected maximum current is less than the maximum current detected in step (3), the optical fiber preform continues to rotate;

[0020] During the fourth rotation of the optical fiber preform, when the current sensor detects the maximum current in step (5) again, the PLC controller sends a signal to the adjustment unit, and the adjustment unit acts to drive the knocking rod to knock the other end of the optical fiber preform again. The force of knocking the optical fiber preform again is less than the previous knocking force; until the current sensor detects no current.

[0021] The beneficial effects of the present invention are as follows: By detecting the concentricity of the optical fiber preform, the eccentricity of the optical fiber preform is measured, and according to the eccentricity, the adjustment unit is driven to knock the optical fiber preform to a corresponding degree; the eccentricity of the optical fiber preform is sensed by the displacement of the follower rod, and the displacement amount of the follower rod is converted into the magnitude of the current. The conversion between the physical quantity and the digital quantity is convenient for the PLC to automatically identify, and it is also convenient to adjust the action time of the adjustment unit according to the magnitude of the detected value. Different action times of the adjustment unit result in different knocking forces on the optical fiber preform, and thus corresponding adjustments are made according to the magnitude of the eccentricity, shortening the adjustment time of the optical fiber preform. Description of the Drawings

[0022] Figure 1 Schematic diagram of the concentricity and eccentricity of the optical fiber preform clamped on the three-jaw chuck;

[0023] Figure 2 Front view of the present invention;

[0024] Figure 3 Front view of the detection unit;

[0025] Figure 4 Cross-sectional view of the follower mechanism;

[0026] Figure 5 Structural diagram of the conversion mechanism;

[0027] Figure 6 Internal structural diagram of the support mechanism;

[0028] Figure 7 Top view assembly drawing of the pallet, rack and gear;

[0029] Figure 8 Top view of the gear rotating to drive the rack to move on the pallet;

[0030] Figure 9 Side view of the swing rod;

[0031] Figure 10 Schematic diagram of the displacement of the swing rod when the ear plate of the follower rod moves upward;

[0032] Figure 11 For Figure 10 Local enlarged view of part A in;

[0033] Figure 12 Schematic diagram of the working state of the present invention;

[0034] In the figure: 1 three-jaw chuck, 11 chuck jaw, 12 gasket, 2 concentric state, 21 eccentric state, 3 welding equipment foundation or ground, 4 support base, 41 pallet, 42 chute, 43 rack, 44 gear, 45 motor, 46 rack ear plate, 47 support rod, 48 first hinge shaft, 5 base, 51 base ear plate, 52 limit block, 53 mounting surface, 54 guide rail, 55 fixed conductive post, 56 contact piece, 57 arc groove, 6 follower rod, 61 wheel carrier, 62 follower wheel, 63 guide block, 64 sheath, 65 spring, 66 limit plate, 67 follower rod ear plate, 68 fixed rod, 69 mounting rod, 7 swing rod, 71 second hinge shaft, 72 first connecting rod, 73 slider, 74 movable conductive post, 75 mounting ear plate, 76 conductive sheet, 77 wire, 78 resistor, 79 power supply, 791 current sensor, 8 base, 81 crank, 82 rocker, 83 second connecting rod, 84 knocking rod seat, 85 knocking rod, 86 driving wheel, 9 optical fiber preform. Embodiment

[0035] As Figure 1 shown, when welding the handle, first, one end of the optical fiber preform is clamped by the three-jaw chuck 1 of the welding equipment, and a gasket 12 is placed between the chuck jaw 11 of the three-jaw chuck 1 and one end of the optical fiber preform to prevent the optical fiber preform from being damaged. After the optical fiber preform is clamped on the three-jaw chuck 1, the optical fiber preform may be in a concentric state 2 with the three-jaw chuck 1 or in an eccentric state 21 with the three-jaw chuck 1.

[0036] As Figures 2 to 12 shown, the present invention includes a detection unit and an adjustment unit. The present invention will be described in detail below with reference to the accompanying drawings.

[0037] As Figure 2 shown, the concentricity adjustment assembly of the optical fiber preform includes a detection unit and an adjustment unit. The detection unit includes a support mechanism, a base 5, a conversion mechanism, and a follower mechanism arranged in sequence from bottom to top. As Figure 3 shown, the fixed part of the support mechanism is fixedly connected to the welding equipment foundation or the ground 3, and the movable part of the support mechanism is fixedly connected to the base 5. The support mechanism drives the base 5 to move up and down. As Figure 6 shown, the fixed part of the support mechanism is the support base 4. The support base 4 is a hollow structure with an open top. The movable part of the support mechanism includes two groups of support rods 47. The two support rods 47 in the same group are arranged crosswise and are hinge-connected through the first hinge shaft 48. The upper ends of the support rods 47 are hinge-connected to the base ear plate 51. The base ear plate 51 is slidably connected to the base 5. The support base 4 has a driving module for driving the lower ends of the two support rods 47 in the same group to approach or separate from each other. As Figure 6 、 Figure 7As shown in the figure, the driving module includes a motor 45 fixed in the support base 4, a gear 44 located at the output end of the motor 45, and racks 43 disposed on both sides of the gear 44 and meshing with the gear 44. The racks 43 are slidably arranged in the support base 4. There are rack ear plates 46 on the racks 43, and the lower end of the support rod 47 is hinged to the corresponding rack ear plate 46. For ease of installation, as Figure 6 shown, the support base 4 has a horizontally arranged support plate 41, and the upper surface of the support plate 41 has a chute 42. The bottom of the rack 43 is provided with a slider slidably connected to the chute 42. The gear 44 is located between the two racks 43. As Figure 8 shown, when the gear 43 rotates, the two racks 43 move synchronously and the moving directions are always opposite (towards each other or away from each other). When the two racks 43 approach each other, the rack ear plates 46 approach each other, and thus the angle between the two support rods 47 decreases, and the base 5 moves upward. On the contrary, when the two racks 43 move away from each other, the rack ear plates 46 move away from each other, and thus the angle between the two support rods 47 increases, and the base 5 moves downward. To limit the base ear plate 51, as Figure 6 shown, there are two limit blocks 52 provided at the bottom of the base 5, and the base ear plate 51 is located between the two limit blocks 52. After the base ear plate 51 contacts the limit blocks 52, the separation of the base 5 from the support rod 47 can be avoided.

[0038] As Figure 3 shown, the base 5 has two groups of fixed conductive posts 55, and conductive elastic contacts 56 are fixed on the fixed conductive posts 55. As Figure 5 shown, the two groups of fixed conductive posts 55 are symmetrically arranged, and there is a resistor 78, a power supply 79, and a current sensor 791 between the two symmetric fixed conductive posts 55. The resistances 78 between the symmetrically arranged two fixed conductive posts 55 are different. The conversion mechanism includes swing rods 7, movable conductive posts 74, and a first connecting rod 72. The swing rods 7 are two cross - arranged ones. The upper ends of the two swing rods 7 are hinged by a second hinge shaft 71. The movable conductive posts 74 are located at the lower ends of the swing rods 7, and the movable conductive posts 74 on the two swing rods 7 are electrically connected. For ease of installation of the fixed conductive posts 55 and maintaining the sliding stability of the lower ends of the swing rods 7, as Figure 6 shown, the top of the base 5 has an arc - shaped mounting surface 53, and an arc - shaped guide rail 54 is fixed on the mounting surface 53. The guide rail 54 has two symmetrically arranged arc - shaped grooves 57. As Figure 9As shown, the lower end of the swing rod 7 has a slider 73, and the slider 73 is slidably arranged in the corresponding arc groove 57. Two groups of fixed conductive columns 55 correspond to the two arc grooves 57 one by one. The fixed conductive columns 55 in the same group are arranged at equal intervals along the arc where the corresponding arc groove 57 is located, and the fixed conductive columns 55 in the same group are connected in parallel. The fixed conductive column 55 is connected in series with the resistor 78 through a wire 77, and the resistors 78 connected to different fixed conductive columns 55 are also connected in parallel. Along the arc direction of the arc groove 57, the resistance value of the resistor 78 connected to the fixed conductive column 55 in the same group gradually increases, and the resistance value of the resistor 78 connected to the fixed conductive column 55 closest to the symmetry point is the largest. The smaller the included angle between the lower ends of the two swing rods 7, the larger the resistance value of the resistor 78 connected to the fixed conductive column 55 connected to the movable conductive column 74 on the swing rod 7; the larger the included angle between the lower ends of the two swing rods 7, the smaller the resistance value of the resistor 78 connected to the fixed conductive column 55 connected to the movable conductive column 74 on the swing rod 7. To realize the electrical connection between the movable conductive columns 74, as Figure 5 shown, the side wall of the movable conductive column 74 has mounting ear plates 75, and there is an elastic arc-shaped conductive sheet 76 between the two mounting ear plates 75.

[0039] As Figure 4 shown, the follower mechanism includes a follower rod 6 and a guide block 63. The follower rod 6 is slidably connected to the guide block 63 in the vertical direction. The upper end of the follower rod 6 has a wheel frame 61, and a follower wheel 62 for contacting the bottom of the optical fiber preform is arranged on the wheel frame. The first connecting rod 72 is located between the lower end of the follower rod 6 and the upper end of the swing rod 7, and one end of the first connecting rod 72 is hinged to the lower end of the follower rod 6, and the other end of the first connecting rod 72 is hinged to the upper end of the swing rod 7. As Figure 10 shown, when the follower rod 6 moves up and down, it drives the swing rod 7 to swing through the first connecting rod 72, so that the movable conductive column 74 at the lower end of the swing rod 7 contacts or separates from the contact piece 56. When the movable conductive column 74 contacts the contact piece 56, the movable conductive column 74, the fixed conductive column 55, the contact piece 56, the resistor 78, the power supply 79 and the current sensor 791 form a current loop, and the current sensor 791 is signal-connected to the PLC controller. The current sensor 791 is used to detect the current in the current loop. When the movable conductive column 74 starts to contact the contact piece 56, the current loop is turned on. As the swing rod 7 continues to swing and the movable conductive column 74 presses the contact piece 56, as Figure 11 shown, the contact piece 56 bends. At this time, the current loop is still in the on state until the movable conductive column 74 separates from the contact piece 56. Therefore, during the bending process of the contact piece 56, the movable conductive column 74 and the contact piece 56 maintain contact for a certain period of time, and during this process, the current loop remains connected. The resistor 78, the power supply 79, and the current sensor 791 are located in the base.

[0040] To realize the relative fixed connection between the guide block 63 and the base 5, as Figure 3As shown, there is a pair of fixed rods 68 between the guide block 63 and the guide rail 54 on the base 5 to achieve the relative fixation between the guide block 63 and the base 5. The fixed rod 68 is an arc-shaped rod. The upper end of the fixed rod 68 is fixedly connected to the side wall of the guide block 63, and the lower end of the fixed rod 68 is fixedly connected to the side wall of the guide rail 54. To install the second hinge shaft 71, as Figure 3 shown, there is an installation rod 69 between the two fixed rods 68, and the second hinge shaft 71 is fixedly connected to the installation rod 69. To facilitate the assembly of the lower end of the follower rod 6 and the first connecting rod 72, as Figure 4 shown, a follower rod ear plate 67 is provided at the bottom of the follower rod 6. As Figure 5 shown, the follower rod 6 is hingedly connected to the first connecting rod 72 through the follower rod ear plate 67. To limit the position between the follower rod 6 and the guide block 63, the lower end of the follower rod 6 has a limiting plate 66. A spring 65 is provided between the guide block 63 and the wheel carrier 61. Under the action of the spring 65, the distance between the follower wheel 62 and the guide block 63 is the largest, and the included angle between the lower ends of the two swing rods 7 is the smallest. To protect the spring 65, a telescopic sheath 64 is provided between the guide block 63 and the wheel carrier 61 outside the spring 65.

[0041] As Figure 2 shown, the adjustment unit includes a crank-rocker mechanism and a flexible knocking rod 85. The crank-rocker mechanism includes a base 8, a crank 81, a rocker 82, and a second connecting rod 83. The base 8 is fixedly connected to the welding equipment. The rocker 83 of the crank-rocker mechanism is fixedly connected to the knocking rod seat 84 of the knocking rod 85. The crank 81 is fixedly connected to the driving wheel 86. The driving wheel 86 rotates under the drive of the driving motor, and then drives the crank 81 to rotate, and then drives the reciprocating swing of the rocker 82. As Figure 12 shown, when the rocker 82 swings toward the side close to the optical fiber preform and reaches the maximum stroke, the knocking rod 85 contacts the end of the optical fiber preform 9 to perform knocking, thereby correcting the eccentricity of the optical fiber preform. The PLC controller controls the action of the crank-rocker mechanism. When it is necessary to correct the eccentricity of the optical fiber preform, the PLC controller sends a signal to the driving motor of the crank-rocker mechanism, causing the crank of the crank-rocker mechanism to rotate one week. The shorter the time for the crank 81 of the crank-rocker mechanism to rotate one week, the greater the knocking force of the knocking rod 85 on the optical fiber preform 9; the longer the time for the crank 81 of the crank-rocker mechanism to rotate one week, the smaller the knocking force of the knocking rod 85 on the optical fiber preform 9.

[0042] The present invention also provides a method for adjusting the concentricity of an optical fiber preform, including the following steps:

[0043] (1) Fix one end of the optical fiber preform on the three-jaw chuck of the welding equipment;

[0044] (2) Drive the follower mechanism to move upward through the support mechanism until the follower wheel contacts the bottom of the optical fiber preform;

[0045] (3) Drive the optical fiber preform to rotate. During the first rotation of the optical fiber preform, if the optical fiber preform is eccentric relative to the three-jaw chuck, the current circuit is connected and the current sensor detects a set of currents of different magnitudes; if the optical fiber preform is concentric with the three-jaw chuck or has a small eccentricity, the current circuit remains disconnected and the current sensor detects no current.

[0046] (4) During the second rotation of the optical fiber preform, when the sensor detects the maximum current in step (2) again, the PLC controller sends a signal to the adjustment unit, and the adjustment unit acts to make the knocking rod knock on the other end of the optical fiber preform. The knocking point between the knocking rod and the optical fiber preform is the contact point between the follower wheel and the optical fiber preform when the current sensor detects the maximum current.

[0047] (5) During the third rotation of the optical fiber preform, if the current circuit continues to be disconnected and the current sensor detects no current, it indicates that the optical fiber preform and the three-jaw chuck are already concentric; if the current circuit continues to be connected and the current sensor continues to detect a set of currents of different magnitudes, and the detected maximum current is less than the maximum current detected in step (3), the optical fiber preform continues to rotate.

[0048] (6) During the fourth rotation of the optical fiber preform, when the current sensor detects the maximum current in step (5) again, the PLC controller sends a signal to the adjustment unit, and the adjustment unit acts to drive the knocking rod to knock on the other end of the optical fiber preform again. The force of knocking on the optical fiber preform again is less than the previous knocking force; until the current sensor detects no current.

[0049] The present invention detects the concentricity of the optical fiber preform, measures the eccentricity of the optical fiber preform, and drives the adjustment unit to knock on the optical fiber preform to a corresponding degree according to the eccentricity; senses the eccentricity of the optical fiber preform through the displacement of the follower rod, and converts the magnitude of the displacement of the follower rod into the magnitude of the current. The conversion between physical quantity and digital quantity is convenient for automatic identification by the PLC, and is also convenient for adjusting the action time of the adjustment unit according to the detected numerical value. Different action times of the adjustment unit result in different knocking forces on the optical fiber preform, and thus corresponding adjustments are made according to the magnitude of the eccentricity, shortening the adjustment time of the optical fiber preform.

Claims

1. Optical fiber preform concentricity adjustment assembly, characterized in that, It includes a detection unit and an adjustment unit. The detection unit includes a support mechanism, a base, a conversion mechanism, and a follower mechanism arranged in sequence from bottom to top. The fixed part of the support mechanism is fixedly connected to the welding equipment foundation or the ground, the movable part of the support mechanism is fixedly connected to the base, and the support mechanism drives the base to move up and down. There are two groups of fixed conductive columns on the base, and a contact piece is fixed on the fixed conductive column. The two groups of fixed conductive columns are symmetrically arranged, and there is a resistor, a power supply, and a current sensor between the two symmetric fixed conductive columns. The resistance values between the symmetrically arranged two fixed conductive columns are different. The conversion mechanism includes a swing rod, a movable conductive column, and a first connecting rod. The swing rod is composed of two cross - arranged rods, and the upper ends of the two swing rods are hinged. The movable conductive column is located at the lower end of the swing rod, and the movable conductive columns on the two swing rods are electrically connected. The follower mechanism includes a follower rod and a guide block. The follower rod is slidably connected to the guide block in the vertical direction. The upper end of the follower rod has a follower wheel for contacting the bottom of the optical fiber preform. The first connecting rod is located between the lower end of the follower rod and the upper end of the swing rod. When the follower rod moves up and down, it drives the swing rod to swing through the first connecting rod, so that the movable conductive column at the lower end of the swing rod contacts or separates from the contact piece. When the movable conductive column contacts the contact piece, the movable conductive column, the fixed conductive column, the contact piece, the resistor, the power supply, and the current sensor form a current loop, and the current sensor is signal - connected to the PLC controller. The adjustment unit includes a crank - rocker mechanism and a flexible knocking rod. The base of the crank - rocker mechanism is fixedly connected to the welding equipment, and the rocker of the crank - rocker mechanism is fixedly connected to the knocking rod. The PLC controller controls the action of the crank - rocker mechanism.

2. The concentricity adjustment assembly for an optical fiber preform according to claim 1, wherein, The fixed part of the support mechanism is a support seat, and the movable part of the support mechanism includes two groups of support rods. The two support rods in the same group are cross - arranged and hinged. The upper ends of the support rods are hinged with a base ear plate, and the base ear plate is slidably connected to the base. There is a driving module in the support seat that drives the lower ends of the two support rods in the same group to approach or move away from each other.

3. The concentricity adjustment assembly for an optical fiber preform according to claim 2, wherein The driving module includes a motor fixed in the support seat, a gear at the output end of the motor, and racks arranged on both sides of the gear and meshing with the gear. The racks are slidably arranged in the support seat, and there are rack ear plates on the racks. The lower ends of the support rods are hinged to the corresponding rack ear plates.

4. The concentricity adjustment assembly for an optical fiber preform according to claim 3, wherein, There is a support plate in the support seat, and the rack is slidably arranged on the upper surface of the support plate.

5. The concentricity adjustment assembly for an optical fiber preform according to claim 1, characterized in that, There are guide rails on the top of the base, and there are two symmetrically arranged arc - shaped grooves on the guide rails. The lower ends of the swing rods have sliders, and the sliders are slidably arranged in the corresponding arc - shaped grooves.

6. The concentricity adjustment assembly for an optical fiber preform according to claim 5, characterized in that, The two groups of fixed conductive columns correspond to the two arc - shaped grooves one by one. The fixed conductive columns in the same group are arranged at equal intervals along the arc where the corresponding arc - shaped groove is located, and the fixed conductive columns in the same group are connected in parallel. Along the direction of the arc where the arc - shaped groove is located, the resistance value of the resistor connected to the fixed conductive columns in the same group gradually increases, and the resistance value of the resistor connected to the fixed conductive column closest to the symmetric point is the largest.

7. The concentricity adjustment assembly for an optical fiber preform according to claim 1, wherein, The side wall of the movable conductive post is provided with mounting ear plates, and an elastic arc-shaped conductive sheet is arranged between the two mounting ear plates.

8. The concentricity adjustment assembly for an optical fiber preform according to claim 1, wherein The upper end of the follower rod is provided with a wheel frame, and the follower wheel is rotatably mounted on the wheel frame.

9. The concentricity adjustment assembly for an optical fiber preform according to claim 1, characterized in that A pair of fixing rods are arranged between the guide block and the base to realize the relative fixation of the guide block and the base.

10. The adjustment method of the concentricity adjustment assembly of the optical fiber preform according to any one of claims 1 to 9, characterized in that, It includes the following steps: (1) Fix one end of the optical fiber preform on the three-jaw chuck of the welding equipment; (2) Drive the follower mechanism to move upward through the support mechanism until the follower wheel contacts the bottom of the optical fiber preform; (3) Drive the optical fiber preform to rotate. During the first rotation of the optical fiber preform, if the optical fiber preform is eccentric relative to the three-jaw chuck, the current circuit is connected and the current sensor detects a set of currents with different magnitudes; if the optical fiber preform is concentric with the three-jaw chuck or has a small eccentricity, the current circuit remains disconnected and the current sensor detects no current; (4) During the second rotation of the optical fiber preform, when the sensor detects the maximum current in step (2) again, the PLC controller sends a signal to the adjustment unit, and the adjustment unit acts to make the knocking rod knock the other end of the optical fiber preform. The knocking point between the knocking rod and the optical fiber preform is the contact point between the follower wheel and the optical fiber preform when the current sensor detects the maximum current; (5) During the third rotation of the optical fiber preform, if the current circuit continues to be disconnected and the current sensor detects no current, it indicates that the optical fiber preform and the three-jaw chuck are already concentric; if the current circuit continues to be connected and the current sensor continues to detect a set of currents with different magnitudes, and the detected maximum current is less than the maximum current detected in step (3), the optical fiber preform continues to rotate; (6) During the fourth rotation of the optical fiber preform, when the current sensor detects the maximum current in step (5) again, the PLC controller sends a signal to the adjustment unit, and the adjustment unit acts to drive the knocking rod to knock the other end of the optical fiber preform again. The force of knocking the optical fiber preform again is less than the previous knocking force; until the current sensor detects no current.

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