A controllable fiber-pulling device and method with joule heat heating and double servo synchronous guide rail linkage

Abstract

The application provides a controllable pulling and tapering device and method with joule heating and double-servo synchronous guide rail linkage. The device peripherally heats a sample with a ring-shaped joule heating body, obtains the temperature of the heating area through non-contact temperature measurement, and adjusts in a closed loop to stabilize the temperature in the softening window; replaces mechanical pulling with left and right two sets of electric displacement execution mechanisms with displacement feedback to realize programmable control and real-time feedback of stretching. The main controller coordinates the linkage of the heat source and the motion mechanism, responds to the actual temperature and the pre-stretching displacement to trigger the double-servo guide rail to enter the corresponding motion stage, synchronously collects temperature, electric parameter, displacement and speed data, realizes formula and timing data tracing, improves the controllability, reproducibility and tracing ability of pulling, and is suitable for the preparation of nanometer pipettes, micro-nano optical fibers and other devices.

Description

Technical Field

[0001] This invention relates to the field of precision machining technology for micro and nano devices, specifically to a controllable tapered device and drawing method that combines Joule heating with dual servo synchronous guide rails. Background Technology

[0002] Tapering technology involves locally heating and applying axial stretching to samples such as capillaries, glass tubes, or optical fibers. This softens the central portion of the sample, forming a micro / nano-scale tapered structure or a fractured nanopore structure. It is a fundamental process for fabricating nanopipettes, solid-state quartz nanopores, micro / nano-fiber devices, fiber optic probes, and single-molecule detection devices. The tip morphology, taper angle, and aperture size of the drawn product are directly affected by the thermal field stability, stretching execution accuracy, and process parameter control. Therefore, the coordinated control of the heating method and the stretching execution mechanism is the core factor determining the quality of the drawn product.

[0003] In the existing technology, the heating methods of tapered devices mainly include the following: (1) Flame heating, which uses alcohol lamps, hydrogen-oxygen flames or butane flames to locally heat the sample. Its structure is simple, but the flame size, airflow fluctuations, environmental disturbances and differences in operator actions can lead to unstable thermal field, and there are problems of flame turbulence and convection disturbance; (2) Metal heating wire / furnace wire heating, which uses resistance wire to generate Joule heat, and the temperature rises faster, but the heating wire is prone to oxidation, deformation or local hot spot drift, and the thermal field morphology changes with the use time; (3) Electric heating bar / electric heating furnace heating, which uses specially designed electric heating bars or furnace cavities to heat optical fibers, etc. By adjusting the power supply voltage to control the temperature, a relatively stable tapered waist diameter can be obtained, but its heating structure is mostly bar (4) Laser heating, represented by commercial laser pullers, uses lasers to heat samples locally. It has the advantages of concentrated energy and high degree of programmability, but it has problems such as high optical path cost and sensitivity to glass diameter, wall thickness, material absorption rate and beam position. Large-diameter or thin-walled samples are prone to uneven circumferential heating. (5) Joule heating ring heating uses graphite rings or carbon rings as Joule heat sources to form a circumferential surrounding local thermal field in the middle of the sample. It is combined with heating chamber, water cooling unit, inert gas protection unit and pull structure on both sides to achieve pulling. This method can achieve high-temperature local heating in an inert atmosphere and can replace some laser pulling methods.

[0004] Regarding the tensioning actuator, existing tapered devices mainly adopt a mechanical traction structure, such as using a traction arm, spring plate, pulley, knob, counterweight, or spring to achieve synchronous tensioning on both sides. This type of solution has a simple structure, and the tensioning action on both sides can be kept synchronous through a mechanical structure. However, its pulling process mainly relies on preset tension, elastic elements, or mechanical traction mechanisms. It is inconvenient to finely set the displacement, speed, acceleration, and disconnection stage of the left and right clamping ends in a multi-stage program throughout the entire pulling process, and it is also difficult to provide real-time feedback and record of the entire process motion data in the form of servo axes.

[0005] For example, patent CN119221095A discloses an apparatus and method for drawing inorganic crystals and amorphous materials using a graphite heater. It employs a graphite ring heater, a heating chamber, a water-cooling unit, an inert gas flow unit, and sliding clamping units on both sides to achieve glass or quartz capillary drawing, which can be considered the closest prior art to this invention. This solution can already complete programmed drawing using parameters such as calorific value, soft pulling force, displacement, speed, and heating time, and corresponding mass-produced products already exist. However, this type of Joule hot drawing solution has the following shortcomings in practical applications: First, the controllability of displacement and feedback recording during the stretching process needs improvement. Existing solutions employ sliding clamping units or mechanical pulling structures. The displacement, velocity, acceleration, and disconnection phases of the left and right clamping ends throughout the pulling process cannot be precisely set in a multi-stage program, nor can the motion data be fed back and recorded in real-time via servo axes. This limits the degree of freedom and data traceability for situations requiring changes to the stretching speed curve, setting displacement termination conditions, recording motion data throughout the process, or adapting to different sample sizes. Second, the linkage between temperature control and actual motion execution is insufficient. Existing solutions primarily use calorific value, soft tensile force, and heating stop conditions as the main control variables, with limited closed-loop feedback of the actual heating temperature, multi-stage displacement / velocity curves, and comprehensive expression of left and right axis motion data. This makes it difficult to accurately trigger the stretching timing based on the actual softening state of the sample, easily leading to sample brittle fracture, collapse, or morphological fluctuations due to inappropriate start timing. Third, the process data traceability capability is insufficient. For samples such as nanopipettes, nanopore precursors, or micro / nano optical fibers, the final tip morphology is closely related to the actual temperature, current, voltage, left and right stretching speeds, left and right positions, and disconnection phases. If the system lacks multi-channel synchronous recording, it is difficult to trace the cause of failed samples, and the process formulation is also difficult to reproduce stably; fourth, the control structure has limited scalability. Traditional closed or mechanical traction solutions are inconvenient to connect to custom host computer state machines, motion control cards, encoder feedback and experimental data recording modules, which is not conducive to the subsequent establishment of parameter libraries for different sample specifications and process iteration optimization.

[0006] Therefore, it is necessary to provide a controllable tapered device and method that links a Joule heating module with a precision electric displacement actuator, so as to further improve the programmability of the stretching action, the linkage between temperature and motion, and the full-process data traceability capability while retaining the advantages of Joule heating ring heating. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a controllable tapering device and method that integrates Joule heating with dual servo synchronous guide rails. The device uses a ring-shaped Joule heating element to circumferentially heat the sample. Temperature in the heating zone is acquired through non-contact temperature measurement and controlled in a closed loop to stabilize the temperature within the softening window. Two sets of electrically driven displacement actuators with displacement feedback replace mechanical pulling, enabling programmable control and real-time feedback of the stretching process. The main controller coordinates the linkage between the heat source and the motion mechanism, determining the sample softening state based on the actual temperature and pre-stretch displacement response under low tension. Once the set softening conditions are met, the device switches to the breaking stage, simultaneously collecting temperature, electrical parameters, displacement, and velocity data. This allows for traceability of formulation and time-series data, improving the controllability, reproducibility, and traceability of the stretching process. It is suitable for the fabrication of devices such as nanopipettes and micro / nano optical fibers.

[0008] On one hand, the present invention provides a controllable tapered device that links Joule heating with dual servo synchronous guide rails, including a Joule heating module and a dual servo electrode guide rail module; the dual servo electrode guide rail module operates according to the actual temperature feedback of the Joule heating module.

[0009] The Joule heating module is responsible for circumferentially heating the sample using annular heating elements such as carbon rings / graphite rings; the dual servo electrode guide rail module is responsible for clamping the sample's two side tube sections and performing precise axial stretching using two sets of servo motor guide rails. Physically, the two modules correspond to the heat source and the actuator, respectively.

[0010] Traditional tapered devices typically follow an open-loop logic of "heating → waiting for a fixed time → stretching," while the two modules of this invention have a real-time closed-loop control relationship—that is, the start, operation, and even stop of the dual servo guide rails are not triggered by a preset delay, but rather by the actual temperature data measured by the Joule heating module as the control input condition.

[0011] The Joule heating module includes a carbon ring heating element, a DC adjustable power supply, an infrared temperature probe, and a heat source controller. The infrared temperature probe non-contactly acquires the temperature of the carbon ring / heating zone, and the heat source controller / main controller determines whether the sample has entered the softening window. Only when the actual temperature reaches the set threshold (and is usually confirmed by pre-stretch displacement response) is the dual servo guide rail triggered to enter the corresponding motion stage, and the motion parameters are coordinated according to the temperature state throughout the stretching process. This achieves deep coupling between thermal state limitation and mechanical motion, avoiding the problems of breakage before softening or overheating collapse. In other words, real-time temperature closed-loop feedback serves as the motion control basis for the precision stretching actuator, transforming heating and stretching from step-by-step execution into conditional linkage.

[0012] Furthermore, the Joule heating module includes a carbon ring heating element, a DC adjustable power supply, an infrared temperature probe, and a heat source controller. The carbon ring heating element is used to form a circumferentially enveloping local thermal field in the middle of the sample. The infrared temperature probe is used to non-contactly measure the actual temperature of the carbon ring heating element or the heating area. The heat source controller is used to adjust the output of the DC adjustable power supply according to the feedback signal of the infrared temperature probe so that the heating temperature is stabilized within a set softening window.

[0013] The carbon ring heating element has a ring structure, with the sample (such as a capillary or optical fiber) passing through its center. When the carbon ring is energized and heated, it forms a 360° localized high-temperature zone around the sample, heating only a small section of the sample rather than the entire sample. This "circumferential enclosure" ensures uniform heating, a concentrated thermal field, high energy utilization, and controllable softening zone location.

[0014] Traditional contact temperature measurement (such as thermocouples directly contacting the carbon ring) has three problems: difficult installation and unreliable contact at high temperatures; it alters the local temperature field of the carbon ring, affecting heating uniformity; and it has a slow response, making it difficult to reflect the true temperature of the carbon ring in real time. Therefore, an infrared temperature probe is used to infer the temperature by receiving the infrared radiation emitted by the carbon ring. This method is non-contact, non-interfering, and has a fast response, making it more suitable for real-time monitoring of high-temperature, small-sized heating elements.

[0015] Setting a softening window refers to the specific temperature range required for a sample material (such as borosilicate glass, quartz, etc.) to change from a rigid to a stretchable state. Different materials have different heating windows. For example, for borosilicate glass capillaries, the target temperature range of approximately 760-840℃ can be used to explore the parameters, while for quartz capillaries, the target temperature range of approximately 1700-1800℃ can be used to explore the parameters.

[0016] Maintaining stability within the softening window means that the process is not a one-time heating up, but rather that throughout the entire stretching process, the heat source controller continuously fine-tunes the power output based on infrared feedback to counteract temperature fluctuations caused by heat dissipation and stretching deformation, ensuring that the carbon ring temperature remains within the target softening window.

[0017] Furthermore, the dual servo motor guide rail module includes two sets of servo motors (left and right), a linear guide rail, an encoder, and a motion control card; the two sets of servo motors respectively drive the left and right slides to move axially along the linear guide rail, and the encoder is used to provide real-time feedback on the position and speed of the left and right axes.

[0018] The module comprises two completely independent and symmetrical servo drive systems, mounted on either side of the annular Joule heating element. Each system corresponds to a slide, on which clamps are mounted to hold the left and right ends of the sample, respectively. This symmetrical layout is the physical basis for achieving synchronous reverse stretching—both sides move in opposite directions simultaneously, keeping the softened region in the middle of the sample at the center of the thermal field.

[0019] A servo motor is the power source. After receiving an electrical signal, it precisely outputs speed and torque. Through a transmission mechanism such as a ball screw or synchronous belt, it drives a slide table to move on a linear guide. The slide table is rigidly connected to the fixture, thereby achieving precise axial displacement of the sample end. Compared with the purely mechanical structures commonly used in existing technologies, such as "traction arm + spring plate + pulley," the advantages of a servo motor are:

[0020] Programmable: Speed, acceleration, and displacement can all be set via software;

[0021] Reversible: It can both stretch and retract, making it convenient for pre-stretching and testing;

[0022] Controllable torque: The upper limit of the output torque can be set to achieve pre-tensioning or force limiting protection.

[0023] The linear guide provides high-precision linear motion guidance for the slide table, ensuring that the slide table can only move along the sample axis (i.e., the pulling direction) without lateral offset or torsion. This ensures that the movement trajectories of the left and right clamps are strictly coaxial, and the sample is subjected to symmetrical force along the axis during the stretching process, avoiding conical deviation caused by mechanical clearance or inaccurate guidance.

[0024] An encoder is a position / speed sensor mounted on a servo motor or slide. It measures and provides feedback on the position and speed of the slide in real time. These feedback signals are used for two purposes: firstly, closed-loop control (the motion control card adjusts the motor output in real time based on the deviation between the actual position and the target position), and secondly, data recording (the displacement and speed data of the entire process are stored in a file to achieve process traceability).

[0025] The motion control card is the nerve center of the module. It is responsible for receiving instructions from the host computer (main controller), converting the instructions into pulse signals or analog voltages that the servo motor can recognize, reading encoder feedback, realizing synchronous control of the left and right axes (such as electronic gear function), coordinating the motion relationship between the left and right servo systems, and ensuring that both sides move in opposite directions with the same speed and the same displacement.

[0026] The precision stretching execution system, which is a precision stretching system with servo motors arranged symmetrically on the left and right sides driving the slide table to move precisely along the linear guide rail, and with the position and speed fed back in real time by the encoder, and the motion control card unified and coordinated, upgrades the passive traction of the traditional tapered cone that relies on springs and weights to a programmable, feedback-enabled, and recordable active servo control, providing a precise and controllable mechanical basis for temperature linkage with the Joule heating module.

[0027] Furthermore, the Joule heating module also includes a thermocouple, which is used to detect the ambient temperature and safety status of the heating chamber and serves as a temperature control compensation parameter.

[0028] The Joule heating module is equipped with two temperature detection methods: an infrared temperature probe (primary) non-contactly measures the actual high temperature of the carbon ring / heating area for PID closed-loop main temperature control; and a thermocouple (secondary) contactively measures the ambient temperature inside the heating chamber as auxiliary monitoring. This dual-temperature design, with one primary and one secondary sensor, retains the accuracy and non-interference of infrared temperature measurement for high-temperature heating elements while using thermocouples to compensate for the shortcomings of infrared temperature measurement in environmental benchmark monitoring.

[0029] Ambient temperature refers to the temperature of components such as the air inside the heated cabin, the insulating ceramic, and the outer shell structure, not the temperature of the carbon ring itself. The carbon ring can operate at temperatures reaching thousands of degrees Celsius, but the cabin environment (such as behind the insulating ceramic and on the inner wall of the outer shell) is relatively cool. Thermocouples are placed in these locations to monitor for abnormalities in the cabin's thermal field distribution, assess the heat dissipation effect of the insulation and water-cooling systems, and provide an ambient temperature reference for infrared thermometry (because emissivity compensation and background radiation correction for infrared thermometry require knowledge of the ambient temperature). When the cabin temperature rises abnormally due to water-cooling failure, interruption of protective gas, or insulation damage, the thermocouples can trigger an alarm or shutdown to prevent equipment overheating and damage or safety accidents.

[0030] Furthermore, the carbon ring heating element is a graphite ring, a carbon fiber composite ring, a pyrolytic carbon ring, or a silicon carbide coated carbon ring.

[0031] These materials are all carbon-based or carbon derivatives, and together they possess stable resistive thermal properties, extremely high temperature resistance (far exceeding the softening temperature of quartz / glass), and geometric adaptability to be processed into rings. They can form a reliable circumferential Joule thermal field around the sample under an inert atmosphere. Among them, graphite rings are preferred embodiments of the present invention due to their moderate resistivity, uniform heating, good machinability, and low cost. Carbon fiber composite rings, pyrolytic carbon rings, and silicon carbide coated carbon rings are respectively suitable for working conditions with special requirements for resistance to thermal shock, high-purity environments, or long-life oxidation resistance.

[0032] Furthermore, the motion control card uses electronic gearing to enable the left and right servo axes to move synchronously in opposite directions at a set ratio, with one axis being the master axis and the other axis being the driven axis.

[0033] The tapering process requires the clamps on both sides of the sample to move simultaneously in opposite directions at the same speed. If the speed or displacement on the left and right sides is inconsistent, the softened area of ​​the sample will deviate from the center of the carbon ring thermal field, resulting in uneven heating; different stretching amounts on both sides will result in an asymmetrical or even bent tapering shape; excessive stretching on one side may cause the sample to break prematurely or the tip to shift. Therefore, the left and right axes must maintain strict motion synchronization and displacement symmetry.

[0034] When it is necessary to prepare asymmetric cones, bias stretching, or adjust specific cone profiles, ratios such as 1:0.8, 1:1, and 1:1.2 can be set to make the stretching speeds on both sides different, and the softened area of ​​the sample will be controllably offset relative to the carbon ring, thereby obtaining special structures with one side longer than the other or different cone angles.

[0035] Electronic gears, through a software synchronization mechanism of "one master and one slave, proportional following", ensure that the left and right servo axes move strictly in opposite directions at a ratio of 1:1 or a set ratio with extremely high real-time performance and precision. This eliminates the gaps and wear of traditional mechanical linkages and is more resistant to interference and easier to program than independent dual-axis control. It is the core motion control method for realizing symmetrical or controllable asymmetrical tapered pulls.

[0036] On another aspect, the present invention provides a controllable tapering method, which includes fixing the middle part of the sample to be drawn to the center of the thermal field of the annular Joule heating element, starting the heating element, adjusting the power output according to the actual temperature feedback from the non-contact temperature measuring device, and controlling the left and right electric displacement actuators to perform synchronous reverse stretching after the temperature enters the softening window. At the same time, temperature, electrical parameters, displacement and speed data are collected synchronously, and static formula and dynamic time series data are saved.

[0037] Specifically, the sample to be stretched is fixed on the clamps of the left and right electric displacement actuators, with the center of the sample located at the center of the thermal field of the annular Joule heating element; a stretching formula is set, which includes at least the target temperature, heating current parameters, torque limit, stretching speed, and termination conditions; the annular Joule heating element is activated, and the power output is adjusted according to the actual temperature feedback from the non-contact temperature measuring device, so that the heating area enters and stabilizes at the set softening window; after determining that the sample has entered the softening window based on the actual temperature feedback from the non-contact temperature measuring device, the left and right electric displacement actuators are controlled to perform synchronous reverse stretching, and the displacement and / or speed are monitored in real time through the displacement feedback device, while temperature, electrical parameters, displacement, and speed data are collected simultaneously; after the termination condition is reached, heating and displacement output are stopped, and data is collected during the cooling process until the temperature drops to a safe threshold; the static formula and dynamic time-series data are saved, including the actual temperature, target temperature, ambient temperature, real-time voltage, real-time current, left and right axis displacement, left and right axis speed, total stretching speed, and stage status.

[0038] Furthermore, before synchronous reverse stretching, a pre-stretching force or low-speed pre-stretching is applied to the sample, and the sample is judged to produce the expected displacement response based on displacement feedback. After confirming that the sample has actually softened, the subsequent stretching or breakage stage is entered.

[0039] In Joule hot drawing, the carbon ring temperature can be quickly reached to the set value via infrared feedback. However, the sample itself has thermal inertia, and the thermal conductivity and softening point vary among quartz / glass tubes of different diameters, wall thicknesses, or materials. If the drawing process proceeds directly to the fracture stage based solely on the temperature signal, two scenarios may occur: first, the sample may not be sufficiently softened internally, leading to brittle fracture or end blunting during stretching, preventing the formation of a sharp point; second, the sample may be excessively softened or even melted, resulting in collapse or an excessively long and thin tip during direct stretching. Therefore, temperature feedback only provides the necessary condition for "thermal field readiness," not the sufficient condition for "safe stretching."

[0040] After the temperature enters the softening window, this scheme first applies a very small pre-stretching force (or a very low pre-stretching speed) via dual servo guides, which is equivalent to performing a mechanical probe test on the sample. If the sample has actually softened, its viscosity decreases, and measurable plastic flow or viscous displacement will occur under a small external force. After the encoder provides real-time feedback on this expected displacement response, the state machine determines that the sample is in a stable deformable state and then switches to the fracture stage. If the expected displacement is not detected, it means that the sample is still in a rigid state, and the system continues to maintain the temperature or fine-tune the temperature to avoid blind stretching.

[0041] Furthermore, the sample is one or more of the following: single-channel capillary, dual-channel capillary, multi-channel capillary, borosilicate glass capillary, quartz capillary, optical fiber, coated wire, or prefabricated electrode carrier.

[0042] In another aspect, the present invention provides the use of the above-described controllable tapering device or the above-described controllable tapering method in the preparation of nanopipettes, nanopore precursors, single-molecule detection devices, micro / nano optical fibers or other micro / nano glass / quartz devices.

[0043] The present invention has the following beneficial effects:

[0044] (1) This invention does not simply trigger stretching based on a fixed heating time or a single temperature threshold, but combines infrared non-contact temperature measurement feedback with the pre-stretching / displacement response of dual servo guides to form a dual judgment mechanism of "temperature-limited thermal state window - mechanical probe confirming actual softening - formal synchronous reverse stretching". This avoids brittle fracture and end blunting caused by direct stretching when the sample is not sufficiently softened, as well as collapse or morphological fluctuations caused by stretching under overheated conditions, making tip forming more stable and controllable, and producing a synergistic effect of 1+1>2.

[0045] (2) The left and right dual servo motor guide rails are used to replace the traditional traction arm, spring plate or pulley mechanical traction structure. With the real-time feedback of the encoder, the displacement, speed, acceleration and termination conditions of the left and right clamping ends can be finely set according to the multi-stage process formula. The electronic gear function realizes synchronous reverse movement of 1:1 or set ratio, ensuring that the stretching on both sides is strictly symmetrical and the sample softening area is always kept in the center of the thermal field, thereby significantly improving the consistency and geometric accuracy of the conical structure.

[0046] (3) Infrared non-contact temperature measurement is used for the carbon ring / graphite ring Joule heat source, which avoids the problems of installation difficulties, local temperature field interference and response lag that exist when the contact thermocouple is used to directly measure the high temperature carbon ring. It can more realistically and continuously reflect the actual temperature of the heating area, and use this as the basis for PID closed-loop control and motion triggering, so that the sample can complete the stretching within a stable and repeatable softening window.

[0047] (4) The system synchronously collects and saves time-series data such as temperature, voltage, current, left and right axis positions, left and right axis speeds, total stretching speed and stage status during each stage of heating, pre-stretching, breaking and cooling, forming a complete process file corresponding to the static formula. This not only facilitates the reverse deduction of process causes from failed samples, but also supports rapid optimization of the formula through parameter iteration (such as adjusting temperature, tension and displacement threshold), which significantly improves R&D efficiency and process transparency. Attached Figure Description

[0048] Figure 1 This is a front view of the instrument;

[0049] Figure 2 This is an isometric side view of the instrument;

[0050] Figure 3 A schematic diagram of the carbon ring body;

[0051] Figure 4 This refers to the internal structure of the heating chamber;

[0052] Figure 5 This is the manual current mode curve;

[0053] Figure 6 For PID mode curves;

[0054] Figure 7 This is a diagram illustrating the effect of segmented temperature control.

[0055] Figure 8 The principle of the electrical control system of the tapered cone;

[0056] Figure 9 Flowchart for sample drawing;

[0057] Figure 10 Record the real-time temperature and guide rail displacement parameters after the drawing is completed;

[0058] Figure 11 This is a representation of the finished product from the first drawing process;

[0059] Figure 12 This is a representation of the finished product after the second stretching process;

[0060] Figure 13 This is a representation of the finished product after the third stretching process;

[0061] Figure 14 A schematic diagram defining the geometric parameters of the drawing tip;

[0062] Figure 15 Characterization of the finished product tips of samples with different end scales;

[0063] Figure 16 Characterization of temperature-free, motion-linked drawn products;

[0064] Figure 17 Characterization of stretched products with temperature-motion linkage;

[0065] Figure 18 The response curves of infrared non-contact temperature measurement and thermocouple contact temperature measurement during the heating process of carbon ring are shown.

[0066] Figure 19 Micrograph of an undrawn optical fiber with an external coating;

[0067] Figure 20 Microscopic image of a micron-sized thinned segment of optical fiber after drawing;

[0068] Figure 21 Microscopic morphology of a glass capillary-embedded optical fiber composite sample after drawing;

[0069] Figure 22 This is a verification diagram of the light transmission of a composite tip with an embedded optical fiber inside a glass capillary. Detailed Implementation

[0070] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be noted that the embodiments described below are intended to facilitate the understanding of the present invention and do not limit it in any way.

[0071] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0072] Example 1: A controllable tapered device with Joule heating and dual servo synchronous guide rail linkage

[0073] like Figure 1 and Figure 2As shown, this embodiment provides a controllable tapered device that links Joule heating with dual servo synchronous guide rails, including a Joule heating module, a dual servo motor guide rail module, a sample clamping and centering module, a host computer control module, and a safety and auxiliary module.

[0074] The Joule heating module includes a carbon ring heating element, a DC adjustable power supply, an infrared temperature probe, a thermocouple, a heat source controller, a heating chamber, a water cooling unit, and a protective gas unit.

[0075] Specifically, such as Figure 2 As shown, the main body of the heating chamber is a hollow rectangular aluminum box, fixed to the heat-insulating ceramic plate by four screws. An adjustable bracket and an infrared temperature probe are secured to the top of the outer shell with fastening nuts; a lens is located at the fastening nut. During heating, infrared radiation emitted by the carbon ring or the heating area passes through the lens and enters the infrared temperature probe. The infrared temperature probe feeds back the actual heating temperature to the heat source controller for PID closed-loop regulation and subsequent guide rail movement triggering.

[0076] The top of the outer shell is equipped with a water-cooling pipe, and the internal structure is a finned radiator. When the instrument is working, cooling water at about 10°C is continuously introduced to dissipate heat from the chamber.

[0077] After removing the outer casing, as Figure 4 As shown, the heating module uses a graphite ring heating element. Figure 3 As shown, the carbon ring has a through hole in the middle for the sample to be heated (such as a glass tube, quartz capillary, optical fiber, etc.) to pass through, and both ends are fixed to a copper electrode fixture through connecting holes and fasteners. The electrode passes through a heat-insulating ceramic and is connected to the heating current line behind it. During operation, a DC adjustable power supply supplies power to the carbon ring through the power line and the electrode. The carbon ring heats up based on the Joule heating effect, forming a localized high-temperature thermal field near the through hole that can cover the softening temperature range of glass or quartz.

[0078] Thermal insulation ceramics are used to insulate the cabin from heat escaping outwards and to protect components such as heating electrodes at the rear of the ceramic.

[0079] During operation, some of the high-temperature heat generated by the carbon ring dissipates into the air inside the compartment and is eventually carried away by the cooling water on the outer shell and top of the outer shell; the other part is conducted to the rear end through the copper electrodes. Therefore, after passing the top of the compartment, the cooling water pipe continues to pass through the two heating electrodes, that is, the cooling water starts from the water chiller, passes through the top of the compartment outer shell and the two heating electrodes in sequence, and then returns to the water chiller, forming a complete cooling circuit.

[0080] Thermocouples are used to monitor the real-time temperature of the heated chamber, serving as detection elements for ambient temperature and safety status, and inputting temperature control compensation parameters into the heat source controller. An external flow meter and nitrogen cylinder are connected to the protective gas pipeline, continuously supplying protective gas (such as nitrogen) into the chamber during operation to slow down the oxidation rate of the carbon rings at high temperatures and improve their service life.

[0081] In terms of heating control, the heat source module can switch between or combine manual current mode, threshold switching mode, and PID closed-loop temperature control mode. In manual current mode, a large current is directly written to quickly bring the carbon ring close to the target temperature range. The infrared temperature probe reads the temperature of the carbon ring or heating area in real time, providing feedback signals for subsequent threshold switching and closed-loop temperature control. In PID closed-loop temperature control mode, the DC adjustable power supply output is adjusted according to the deviation between the infrared temperature reading and the target temperature, stabilizing the carbon ring temperature near the set softening window. Figure 6 During the drawing process, the device can employ a segmented temperature control method combining manual current rapid heating, threshold temperature reduction, and PID closed-loop temperature stabilization to ensure that the sample heating zone quickly reaches and stabilizes at the target temperature. Figure 7 As shown.

[0082] The dual servo motor guide rail module includes two sets of servo motors (left and right), linear guide rails, encoders, limit / return-to-zero units, motion control cards, and servo controllers.

[0083] Specifically, such as Figure 8 As shown, the computer is connected to the motion control card via a network cable, and the control card is connected to the servo controller via a signal cable. The computer converts the pulse signals sent by the motion control card into drive signals for the guide rail, driving the guide rail to slide left and right. The guide rail itself has two platforms on the same linear bearing, and the movement of the left and right platforms can be controlled independently.

[0084] There are three main modes of guide rail movement: speed mode, which drives the table to move at a corresponding speed based on the analog voltage given by the control card; displacement mode, in which the motion control card sends pulse commands to the servo controller, and the servo motor drives the slide to move according to the number of pulses and system parameters, thereby realizing quantitative displacement control of the left and right clamps; and torque mode, which applies a certain amount of torque to the movement of the table based on the analog voltage given by the control card.

[0085] The system uses encoder feedback to read the position and speed of the left and right slides in real time for synchronous control and data recording during the drawing process. The control card has an electronic gear function, allowing the left and right axes to establish a 1:1 or other proportional linkage relationship via electronic gears. This ensures that one axis is the master axis and the other is the driven axis, moving synchronously to guarantee the consistency of the drawing motion on both sides, thus achieving symmetrical drawing. The system can also set guide rail torque limits via the analog output of the motion control card to limit the output torque during guide rail movement, thereby creating a pre-stretching or force-limiting control effect.

[0086] In addition, the system provides functions such as guide rail power on / off, automatic zeroing, limit monitoring, electronic gear switch, and encoder zeroing. Therefore, the instrument can automatically return the clamp to its original position before drawing and can safely release or reset after drawing the tapered section.

[0087] The sample clamping and centering module includes left and right clamps, a carbon ring center alignment structure, and insulating / heat-insulating supports. The left and right clamps are respectively mounted on left and right slides and are used to clamp the sample sections on both sides. The carbon ring center alignment structure ensures that the area to be drawn from the capillary or optical fiber is located at the center of the carbon ring's thermal field, guaranteeing consistent heating and stress distribution.

[0088] The host computer control module includes a graphical interface, process parameter tables, state machine control programs, and data logging programs. The host computer communicates with the heat source controller and motion control card via a switch, and is used to read the recipe and coordinate the movements of the heat source and guide rails, generating a complete process record of temperature, displacement, speed, and current.

[0089] The host computer software executes the drawing process using a timed cyclic state machine. Upon clicking "start," the system begins cycling according to pre-defined steps. Within each cycle, the system reads data from the heat source controller and the guide rail motion control card to obtain the actual temperature, target temperature, ambient temperature, real-time voltage, real-time current, left and right axis positions, and left and right axis speeds of the carbon ring. Based on different execution states, the system performs corresponding actions. The state machine includes at least the following execution states:

[0090] Initialization state: Click "Draw", the system reads the drawing parameters, writes the first stage target temperature, torque limit and heating parameters, to ensure that the heat source and guide rail enter the process from a unified initial state.

[0091] Heating / softening judgment state: Perform segmented heating; when the actual temperature reaches near the target temperature, apply a small tension force to the guide rail and record the pre-stretch displacement response. Based on the temperature and displacement response, determine whether the sample has entered a softening state suitable for breakage.

[0092] Tensile failure state: When the pre-stretch displacement reaches the set threshold, the system stops heating output and switches to a larger tensile force, causing the sample to break in the softening zone and form a pair of conical tip structures.

[0093] Stop heating and cooling recording status: After reaching the set duration, displacement, speed or other termination conditions, the heat source and guide rail output are turned off, and the cooling and guide rail sliding are recorded to capture the cooling and solidification process, which is convenient for analyzing the relationship between the finished product morphology and the process curve.

[0094] End and save status: Recording stops after the temperature drops to a safe threshold, and the formula parameters and time series data are saved as a CSV file to enable process traceability, experiment reproduction and batch optimization.

[0095] The safety and auxiliary module includes functions such as guide rail power on / off control, electronic gear linkage / disengagement, zero return, gas valve or protective gas interface, and abnormal stop, to improve the safety of equipment operation and maintainability under different sample working conditions.

[0096] In this embodiment, the carbon ring heating element can be a graphite ring, a carbon fiber composite ring, a pyrolytic carbon ring, or a silicon carbide coated carbon ring, preferably a graphite ring.

[0097] The device in this embodiment achieves coordinated control of Joule heating closed-loop temperature control and dual servo guide rail motion state machine through the collaborative work of the above modules. The specific collaborative relationship is as follows: The Joule heating module obtains the actual temperature of the carbon ring or heating area in real time through an infrared temperature probe. The heat source controller adjusts the DC adjustable power supply output according to the feedback signal to raise the heating temperature to and stabilize it within the set softening window. During the heating and stabilization process, the host computer control module controls the left and right servo motors through the motion control card to apply a small pulling force to the clamping sections on both sides of the sample, so that the left and right slides generate a monitorable pre-stretch displacement during the sample softening process. The encoder provides real-time feedback on the position and speed of the left and right axes, and the host computer adjusts the temperature according to the actual temperature of the carbon ring. The system uses the pre-stretch displacement response under small tensile force to determine whether the sample has reached the softening condition. When the temperature enters the target range and the pre-stretch displacement reaches the set threshold, the system determines that the sample has entered a softened state suitable for breakage. Subsequently, the carbon ring heating output is stopped, and the guide rail output is switched to a larger breaking force, so that the sample is broken in the softened area, forming a pair of conical tip structures. During the heating, pre-stretching, breaking, and cooling processes, the system simultaneously collects data such as the actual temperature of the carbon ring, ambient temperature, electrical parameters, left and right axis displacement, and velocity. After the breaking is completed or the safe termination condition is met, the system stops heating and guide rail output, and continues to collect data during the cooling process until the temperature drops to the safe threshold and all data is saved.

[0098] Example 2: A controllable tapered method

[0099] Using the controllable tapering device as described in Example 1, this embodiment provides a controllable tapering method that links Joule heating with dual servo synchronous guide rails, including the following steps:

[0100] Turn on the power to all instruments, start the host computer control software, turn on the water chiller and confirm that the cooling water circulation is normal. Turn on the gas cylinder knob and open the protective gas valve to continuously introduce protective gas (e.g., nitrogen) into the heating chamber. Set the protective gas flow rate to 0.02-0.1 L / min; in this embodiment, it is set to 0.03 L / min to purge air from the chamber and establish an inert atmosphere. Perform the automatic zeroing operation of the left and right guide rails via the host computer or manual operation to reset the left and right clamps to their initial positions. The capillary sample to be drawn (such as borosilicate glass capillary, quartz capillary, or optical fiber) has two sections fixed on the left and right guide rail clamps respectively. The total length of the sample is 100 mm, the outer diameter is 1.0 mm ± 0.02 mm, the inner diameter is 0.6 mm ± 0.02 mm, and the wall thickness is 0.2 mm ± 0.01 mm. Before use, the sample can be cleaned with plasma or wiped with anhydrous ethanol and dried with nitrogen to remove surface organic contaminants and dust; it can also be dried depending on the degree of contamination. The left and right clamps hold approximately 15 mm sections of the sample on each side. The clamping position is not at the very end of the sample, but at a certain distance from the end, and as close as possible to the center of the carbon ring, within the limits of structural tolerance, to reduce the effect of gravity-induced capillary sagging on the drawing process. The exposed length of the sample between the two clamps near the carbon ring is approximately 40 mm. Adjust the sample clamping and centering module to ensure the area to be stretched in the middle of the capillary is precisely positioned at the center of the through-hole of the carbon ring heating element. The axial length of the through-hole of the carbon ring heating element is 2 mm, which can be used as the nominal heating width. The middle part of the sample passes through the through-hole of the carbon ring, and the sample section near the center plane of the carbon ring forms the main heated area. Due to heat conduction and radiation, the actual softening zone can extend to both sides along the sample axis, and its length can be adjusted according to the carbon ring temperature, heating time, sample material, and cooling conditions. The left and right sides of the sample enter the clamping area of ​​the fixture at a distance of approximately 20-22 mm from the center plane of the carbon ring. Ensure that the sample axis is coaxial with the stretching direction, and then lock the fixture.

[0101] Select or import drawing parameters in the host computer graphical interface. These drawing parameters include at least the target temperature, heating parameters, PID temperature control parameters, minimum drawing force parameters, pre-stretch displacement threshold, breaking force, cooling time, and data acquisition parameters. Specifically, the target temperature is used to determine the temperature control target for the carbon ring heating zone; the heating parameters and PID temperature control parameters are used to control the heating and stabilization process of the carbon ring; the minimum drawing force parameter is used to apply pre-stretching to the clamping sections on both sides of the sample during heating or stabilization; the pre-stretch displacement threshold is used to determine whether the sample has reached a suitable softening state for breaking; the breaking force is used to break the sample after the softening condition is met; and the cooling time and data acquisition parameters are used to control the cooling and recording process after breaking. For multi-stage or special drawing processes, the parameters may further include a second-stage target temperature, a second-stage minimum drawing force parameter, electronic gear ratio, breaking speed, disconnection displacement, and protection shutdown threshold.

[0102] In this embodiment, the sample is a borosilicate glass capillary. Taking single-stage drawing as an example, the initial parameters include: target temperature 760℃, pre-tension force (small tension) corresponding to 8000 counts in the control card, pre-tension displacement threshold 200 μm, breaking tension corresponding to 30000 counts in the control card, and cooling time 10 s. Here, "count" is the pulse counting unit inside the control system, corresponding to the output of the servo driver. The specific physical quantity conversion relationship can be determined based on the equipment calibration results.

[0103] When the carbon ring Joule heat source is activated, the equivalent resistance at room temperature between the two electrode clamping positions of the carbon ring heating element in the assembled state is greatly affected by the carbon ring material, geometry, electrode contact position, clamping state, and measurement method. In this embodiment, the equivalent resistance at room temperature near the electrode pressing / fixing position is approximately 5 Ω. This value is mainly used to characterize the conduction state after the carbon ring and electrodes are assembled. In actual operation, the equivalent heating resistance, power supply output voltage, and heating power of the local high-temperature area of ​​the carbon ring will change with temperature and contact state. The operating current can be set in the range of approximately 30~200A according to the target temperature and heating stage. In this embodiment, approximately 90A current is used for rapid heating during the heating stage, and the current is automatically adjusted to fluctuate within the range of approximately 60-70A after entering the PID temperature stabilization stage. The heat source controller first controls the DC adjustable power supply to output a large current, so that the carbon ring heating element heats up rapidly to approach the target temperature range; at the same time, the infrared temperature probe reads the surface temperature of the carbon ring in real time without contact. The infrared temperature probe is an online short-wave infrared temperature probe used for non-contact temperature measurement of the carbon ring heating element or heating area. Its temperature measurement range covers 500~2500℃, and the response wavelength can be selected from 1 μm or 1.6 μm short-wave infrared bands depending on the probe model. The response time is in the millisecond range, and the emissivity parameter can be set, calibrated, or corrected according to the carbon ring material and surface condition. When the temperature difference between the actual temperature and the target temperature of the carbon ring decreases to a set threshold (e.g., 50℃), the heat source controller automatically reduces the current output level and enters the threshold switching stage. When the temperature difference further decreases to another set threshold (e.g., 10℃), the system automatically switches to PID closed-loop temperature control mode based on infrared temperature measurement feedback, dynamically adjusting the power output according to the deviation between the actual temperature and the target temperature to stabilize the carbon ring temperature within the set range for entering the sample softening window. During this process, the thermocouple synchronously monitors the ambient temperature of the heating chamber, which can be used as a reference parameter for infrared temperature measurement calibration, compensation, or equipment safety status assessment.

[0104] When the actual temperature of the carbon ring fed back by the infrared temperature probe enters the sample softening window (e.g., close to and stable at the target temperature of 760℃), the system enters the temperature-motion linkage stage. At this time, the host computer state machine does not directly initiate the breakage action, but first controls the left and right servo motors through the motion control card to apply a small pre-tensioning force to the clamping sections on both sides of the sample, for example, corresponding to 8000 counts inside the control card, so that the left and right slides produce a small displacement in opposite directions under the action of small tension. The encoder provides real-time feedback on the position and displacement changes of the left and right axes. The host computer judges whether the sample has reached a suitable softening state for breakage based on the temperature feedback and the pre-tensioning displacement response: if the sample has not been sufficiently softened, the displacement fed back by the encoder is small or there is no continuous displacement, then the system determines that the sample is still in a rigid or insufficiently softened state, and continues to heat up or keep warm by the Joule heating module to avoid blind breakage leading to brittle fracture; if the sample produces a stable and continuous displacement response under the action of small tension and reaches the set pre-tensioning displacement threshold, such as 200 μm, then the system determines that the sample has entered a suitable softening state for breakage. Subsequently, the state machine switches to the breaking stage, stops the carbon ring heating output, and activates the electronic gear function via the motion control card, setting one servo axis as the master axis and the other as the driven axis. This causes the left and right slides to move synchronously in opposite directions at a 1:1 ratio. Simultaneously, the guide rail output is switched to the set breaking force, such as 30,000 counts, causing the sample to break in the softening zone, forming a pair of conical tip structures. Throughout the heating, pre-stretching, breaking, and cooling processes, the host computer synchronously collects and records the actual temperature, target temperature, ambient temperature, real-time voltage, real-time current, left and right axis positions, left and right axis speeds, total stretching speed, and stage status data of the carbon ring, at a sampling frequency of, for example, 100 Hz.

[0105] Once the sample breaks or reaches a preset termination condition (such as a set time, abnormal displacement, or sudden current change), the host computer's state machine enters a state of stopping heating and recording cooling. The heat source controller shuts off the DC adjustable power supply output, stopping the carbon ring heating; the motion control card stops outputting drive signals to the servo motor. During the sample cooling and solidification process, the system continues to synchronously collect the temperature drop curve and residual slip data of the guide rail through an infrared temperature probe and encoder until the chamber temperature drops below the set safety threshold (e.g., 100°C), ensuring that the sample has been fully solidified and set, and avoiding deformation caused by accidental contact at high temperatures.

[0106] Once the temperature drops to the safe threshold, the state machine enters the end and save state. The system automatically aligns the static formula parameters of this drawing process (including target temperature, torque limits at each stage, displacement thresholds, PID parameters, etc.) with the dynamic time-series data (including temperature, voltage, current, displacement, speed, and stage status collected synchronously throughout the process) with a unified timestamp and saves it as a CSV file, enabling traceable recording of the process. Figure 10 As shown.

[0107] Subsequently, the drawn product was observed under an optical microscope. The processing effect was evaluated based on the tip morphology, cone continuity, tip length, and fracture marks, and the formula was iteratively optimized accordingly.

[0108] First stretching test (parameters: target temperature 760℃, minimum tensile force 8000 counts, pre-stretch displacement threshold 200 μm, breaking force 30000 counts): After starting the carbon ring Joule heat source, the carbon ring is rapidly heated using the same segmented heating parameters, with an initial current of 90 A, a deceleration current of 60 A, and a PID temperature difference of 25℃. Since the infrared temperature probe does not output an effective temperature reading below 500℃, the initial temperature is only displayed as the lower limit of the range at 500℃. Once the infrared temperature value enters the effective temperature range, the system continues to heat to near the target temperature of 760℃, and uses PID control to maintain the carbon ring temperature within the set temperature window. Subsequently, the left and right clamps apply a minimum tensile force of 8000 counts to the sample to determine the softening state of the sample at the current temperature; during this stage, the system continuously records the displacement response of the left and right servo axes. When the sample produces a stable and continuous displacement response under a small tensile force, and reaches the set pre-stretch displacement threshold of 200 μm, the system determines that the sample has entered a tensile softening state and immediately switches to the tensile breaking stage, breaking the sample with a tensile force of 30,000 counts. Figure 11 The obtained sample showed severe fracture marks at the tip, with no obvious continuous tip formed at the end. Analysis of the entire process data indicated that the target temperature was too low and the pre-stretching force was too high, causing the sample to break due to insufficient softening or an unstable softening window. Therefore, the formulation was adjusted as follows: the target temperature was increased to 840℃, and the minimum tensile force was reduced to 3000 counts to improve sample softening and reduce mechanical impact during the pre-stretching stage.

[0109] Second tensile test (parameters: target temperature 840℃, minimum tensile force 3000 counts, pre-tension displacement threshold 200 μm, breaking force 30000 counts): The heating parameters were the same as the first test. After the carbon ring temperature reached the target temperature and entered PID temperature stabilization, a minimum tensile force of 3000 counts was applied to the sample; when the pre-tension displacement threshold reached 200 μm, the system switched to the breaking stage and broke the sample with a breaking force of 30000 counts. The results are as follows. Figure 12 The obtained sample showed a significant increase in tip length, but the cone transition was too long, indicating that the target temperature was too high, leading to excessive softening and excessive material flowability under the same pre-stretch displacement threshold. Therefore, the formulation was adjusted again: the target temperature was lowered to 820℃, while maintaining a low tensile force of 3000 counts, in order to find a better match between temperature and the softening judgment under low tensile force.

[0110] The third tensile test (parameters: target temperature 820℃, minimum tensile force 3000 counts, pre-stretch displacement threshold 200 μm, breaking force 30000 counts): The heating parameters were the same as the first test. After the carbon ring temperature reached the target temperature and entered PID temperature stabilization, a minimum tensile force of 3000 counts was applied to the sample; when the pre-stretch displacement reached 200 μm, the system switched to the breaking stage and broke the sample with a breaking force of 30000 counts. Figure 13 The obtained sample had an ideal tip morphology, a natural cone transition, good tip continuity, and no obvious breakage or collapse defects. According to... Figure 14 The parameters shown are defined, and estimated using the scale bar and low-magnification optical microscopy image. The length of the necked section at the tip of the sample is approximately 250 μm, the cone angle θ is approximately 8°, and the cross-sectional diameter D40 at approximately 40 μm from the tip is approximately 22 μm. These dimensions are estimates derived from the optical microscopy image and the scale bar in the figure, and can be used to evaluate the consistency of the geometry near the sample tip at the same magnification. Since the low-magnification optical microscopy image cannot directly resolve the tip opening and nanoscale aperture, these dimensions can be further confirmed through high-magnification microscopy, scanning electron microscopy, or electrical testing.

[0111] Therefore, this set of parameters was determined as the preferred drawing formula for borosilicate glass capillaries of this specification and saved to the process library for subsequent reproduction.

[0112] Through the above steps, the method of this embodiment achieves deep linkage between Joule heating closed-loop temperature control and dual-servo synchronous reverse stretching. The pre-stretch displacement response is used to confirm the actual softening state of the sample, avoiding the blindness of traditional stretching based on fixed time or a single temperature threshold. At the same time, through full-process data recording and formula iteration, the controllability, reproducibility and finished product qualification rate of the stretching process are significantly improved.

[0113] To verify the repeatability of the above-mentioned optimized formulation (target temperature 820℃, low tensile force 3000 counts, pre-stretch displacement threshold 200 μm) in batch production, 50 borosilicate glass capillaries were continuously drawn under the same conditions using this formulation. The morphology near the tip of each sample was observed and estimated under an optical microscope at the same magnification. Since the field of view of the optical microscope mainly covers the local area of ​​the tip, and the position too close to the tip is greatly affected by optical resolution and focusing, this embodiment selects the local cone angle and the cross-sectional diameter D40 at approximately 40 μm from the tip as characterization indicators of near-tip morphology repeatability. Among them, the local cone angle is defined as the angle between the two outer contour edges near the tip in the microscopic image, and D40 is defined as the cross-sectional width between the outer contours of the sample at approximately 40 μm from the tip.

[0114] The following three geometric indicators are used to quantify the threshold values ​​for finished product qualification:

[0115] (1) Local cone angle consistency: The outer contours on both sides near the tip of the sample should form a continuously contracting cone structure, and the local cone angle distribution should be relatively concentrated. There should be no abnormal tip shape that deviates significantly from the overall distribution of samples in the same batch.

[0116] (2) Consistency of outer diameter near the tip: The cross-sectional diameter D40 at a distance of about 40 μm from the tip should be within the main distribution range of the same batch of samples, and should not be obviously too thick or too thin or have abnormal morphology caused by defocusing, breakage or collapse;

[0117] (3) Integrity of the tip porosity: The tip should be continuous and intact when observed under an optical microscope, without obvious brittle fracture, excessive melting and collapse, severe bending or longitudinal cracks longer than 10 μm.

[0118] Overall qualification criteria: When all of the above indicators are met, the sample is considered to have qualified morphology under an optical microscope; if any indicator is obviously abnormal, it is considered unqualified or requires re-verification.

[0119] The results are shown in Table 1:

[0120] Table 1. Statistical results of 50 borosilicate glass capillary samples

[0121]

[0122] The results show that, with the synergistic effect of Joule thermal closed-loop temperature control, dual servo synchronous guide rails, encoder feedback, upper computer state machine linkage, and full-process data recording, this device can stably and repeatedly prepare a batch of borosilicate glass capillary tip structures with similar morphology and continuous and complete tips under an optical microscope without human intervention.

[0123] Example 3: Consistency Analysis of Quartz Capillary Drawing

[0124] To verify the repeatability of this instrument in drawing quartz capillaries, 50 capillaries (100 mm in length, 1 mm in outer diameter, and 0.6 mm in inner diameter) were continuously drawn under the same conditions using the optimized parameters for the quartz capillaries (target temperature 1760℃, minimum tensile force 3000 counts, and pre-stretch displacement threshold 500 μm). The morphology of the sample tips was observed and estimated under an optical microscope.

[0125] The results are shown in Table 2:

[0126] Table 2 Statistical results of 50 quartz capillary tube samples

[0127]

[0128] Table 2 shows that the coefficient of variation of the local cone angle during the drawing process of quartz capillary was 13%, and the coefficient of variation of D40 was 9.6%, both of which showed good consistency. The pore integrity of the tips of all 50 samples was qualified. Compared with borosilicate glass (Table 1), quartz capillary, due to its higher drawing temperature (1760℃ vs 820℃), has a more concentrated softening zone, resulting in a smaller cone angle (11.9° vs 13.55°) and a faster tip taper (D40: 19.5 μm vs 23.21 μm). However, the coefficients of variation of the two materials are at similar levels, indicating that the device can provide stable process control under different material systems and temperature conditions. At the same time, the carbon ring heating element can still maintain temperature stability through PID closed-loop control at a high temperature of 1760℃, verifying the engineering reliability of the device under extreme high-temperature drawing conditions.

[0129] Example 4: Drawing borosilicate glass capillaries of different sizes

[0130] This method utilizes borosilicate glass capillaries (outer diameter 1 mm, inner diameter 0.6 mm) to fabricate micro / nano probes with different end scales. Figure 15 The probe tip morphology images are shown at different magnifications, with dimensions and drawing parameters as follows: Figure 15 In the figure, 'a' is approximately 20 μm in size, the target temperature is 820℃, the minimum tensile force is 3000 counts, the pre-tension displacement threshold is 356 μm, and the breaking tensile force is 27500 counts. Figure 15 b in the figure: approximately 10 μm, target temperature 820℃, small tensile force 3620 count, pre-tension displacement threshold 410μm, breaking tensile force 31000 count; Figure 15 In the figure, c represents a value on the order of approximately 1-2 μm, the target temperature is 825℃, the minimum tensile force is 2860 counts, the pre-tension displacement threshold is 350 μm, and the breaking tensile force is 39000 counts. Figure 15 The tip of 'c' in the image is close to the resolution of an optical microscope, and obvious interference can be seen in the image. The specific aperture can be further confirmed by high-magnification microscopy, scanning electron microscopy or electrical testing.

[0131] Example 5: The Influence of Temperature-Motion Linkage on Drawing

[0132] To verify the advantages of temperature-motion linkage control over no linkage control and to confirm the synergistic effect of the linkage scheme, the controllable tapered device described in Example 1 was used, with borosilicate glass capillary tubes as samples, and the drawing comparison experiments were conducted under the environmental conditions of the third drawing in Example 2 (nitrogen protection, the same target temperature range, and the same carbon ring heating element), with and without temperature-motion linkage.

[0133] Group 1 (No Linkage): This disables the infrared temperature feedback triggering function for the guide rail movement and the pre-stretch displacement response judgment function. The guide rail initiates stretching according to a preset fixed delay or program, without relying on the actual temperature of the carbon ring or small-force trials as the starting condition. Specifically, after setting the target temperature, the system directly starts the guide rail for stretching with a fixed heating time. After stretching is complete, the sample is observed using an optical microscope.

[0134] Group 2 (Linkage): Activating the temperature-motion linkage function, the system uses an infrared temperature probe to acquire the actual temperature of the carbon ring or heating area in real time, allowing the carbon ring to first enter the set heating window. The left and right servo guide rails apply a small pre-tension force (or low-speed pre-stretch) to the sample, and the encoder provides feedback to observe whether the sample produces the expected displacement response at that temperature. When the sample is not sufficiently softened, even with a small tension applied by the guide rails, it is difficult for the sample to produce stable deformation. Directly entering the formal stretching stage at this point can easily cause end blunting, breakage, or failure to form a sharp point. Once the sample reaches a suitable softening state, the encoder detects the expected displacement response, and the system determines that the sample has met the conditions for stable deformation, then switches to the breakage stage. After stretching is completed, the sample is observed using an optical microscope.

[0135] The results are as follows Figure 16 , Figure 17 As shown, the softening state of the sample in group 1 was unstable during the stretching stage. After stretching, no obvious tip was formed at the end, resulting in an unsatisfactory forming result with end blunting or fracture marks. Since the actual temperature of the carbon ring was not used as the motion initiation condition, the sample may not have softened sufficiently during stretching (leading to brittle fracture and end blunting) or may have softened excessively (leading to collapse or inability to form a stable cone). Therefore, a continuous and symmetrical cone tip structure could not be obtained. Group 2 judged the softening window through real-time temperature feedback and small tensile displacement response. The sample was able to form a more obvious tip, the cone transition was more natural, the tip continuity was good, and the forming effect was better.

[0136] The comparative experiments above show that the temperature-motion linkage is not simply "starting the motor after the temperature is reached", but rather combines infrared temperature feedback to limit the thermal state range with the small tension / displacement response of the dual servo guide rails to further determine the actual softening state of the sample. The temperature control system provides a repeatable heating state, and the motion system provides feedback on the degree of sample softening through pre-stretching. The two together determine the timing of the breakage stage, thereby significantly reducing the failure of drawing due to misjudgment of the softening state, making the drawing tip formation more stable, and achieving a synergistic effect of "1+1>2".

[0137] Example 6: System Functional Collaboration Analysis

[0138] To illustrate the collaborative relationship between Joule heating closed-loop temperature control, dual-servo synchronous reverse stretching, encoder feedback, and the host computer state machine in this device, the following analysis considers several possible scenarios with missing functions. This analysis is intended to explain the role of each functional module in the stretching process of this device and is not a test embodiment after disassembling and modifying the device.

[0139] Using capillary samples of the same specifications, if only a carbon ring Joule heat source is used for closed-loop temperature control, and the stretching process is still triggered by a fixed delay without encoder feedback for motion control, the system can control the heating state of the carbon ring, but cannot determine its actual softening state based on the sample's displacement response under small tensile forces. Since different batches of capillary tubes, the contact state of the carbon ring, the flow of protective gas, and the ambient temperature of the heating chamber can all affect the sample softening process, relying solely on a fixed delay to initiate stretching can easily lead to stretching before sufficient softening or stretching after excessive softening, resulting in decreased tip forming stability.

[0140] If only an encoder recording function is added to the above, but the encoder signal does not participate in motion phase switching and closed-loop control, the system can only obtain process records such as displacement and velocity after the drawing process is completed. This method is helpful for post-process analysis, but it cannot correct the motion state in real time during the drawing process, nor can it be used as a basis for judging the softening state of the sample and for controlling the start of formal drawing. Therefore, it has limited improvement on the stability of a single drawing process.

[0141] If dual servo motors are used to drive the left and right slides respectively, and the position and speed of the left and right slides are fed back through encoders, but the electronic gear synchronous reverse stretching function is not enabled, and the host computer sends motion commands to the left and right axes respectively, the movement of the left and right axes may be affected by factors such as communication cycle, command issuance order, and controller response time. It is difficult to ensure that the two clamps maintain strictly synchronous reverse movement throughout the entire stretching process. For the capillary tip stretching process, the displacement difference and velocity difference between the left and right sides will affect the heating and stretching symmetry of the sample relative to the center of the carbon ring, thus affecting the consistency of the cone transition section and tip morphology.

[0142] If dual-servo synchronous reverse stretching and encoder feedback are retained, but infrared thermometry is not used for closed-loop temperature control of the high-temperature region of the carbon ring, and open-loop heating is only performed based on fixed current, fixed power, or fixed heating time, the system will find it difficult to obtain the actual temperature of the carbon ring and the softening window of the sample. Since the carbon ring resistance, contact state, protective gas flow, and chamber heat dissipation will change during use, the time and extent to which the sample enters the softening state under open-loop heating conditions may fluctuate, leading to reduced tip morphology consistency and a decreased yield.

[0143] This device uses a Joule-heated carbon ring as a local heating source, and an infrared temperature probe collects the temperature of the high-temperature zone of the carbon ring as feedback for PID closed-loop temperature control. Simultaneously, dual servo motors drive the left and right clamps to move synchronously in opposite directions via guide rails. Encoders provide real-time feedback on the position and speed of the left and right axes, and a host computer's state machine switches between stages based on temperature target attainment, pre-stretch displacement, and breakage conditions. Thus, temperature control, softening state judgment, synchronous reverse stretching, and full-process data recording are integrated into a single drawing process. This reduces the uncertainty caused by simply fixing the heating time or delaying the stretching, and improves the controllability and repeatability of the capillary tip morphology.

[0144] In summary, none of the steps mentioned above can be omitted; without any one of them, the 100% product qualification rate and the low geometric variation coefficient of 6.8% to 13% achieved in the above experiments could not be obtained. This application achieves stable and reproducible micro / nano-tip structures through the organic synergy of the four core steps mentioned above.

[0145] Example 7: Compatibility Analysis of Different Temperature Measurement Methods

[0146] This device employs infrared thermometry as the primary temperature control method for the high-temperature zone of the carbon ring, and thermocouples can be used for auxiliary monitoring of the ambient temperature or safety status of the heating chamber. To illustrate the rationality of this temperature measurement configuration, the following analysis examines the compatibility of different temperature measurement methods during the Joule hot drawing process of the carbon ring, taking into account the structural characteristics of this device.

[0147] For schemes using only thermocouples as the main control temperature sensing element, the effective heating area of ​​the carbon ring is relatively small, and the sample is locally heated by passing through the through-hole of the carbon ring. Therefore, it is difficult to stably position the thermocouple probe in the high-temperature region of the carbon ring that truly reflects the softening state of the sample. If the thermocouple is only placed inside the heating chamber or near the carbon ring, the measured temperature reflects more the ambient temperature of the chamber or the local support temperature, making it difficult to reflect the real-time temperature changes in the effective heating area of ​​the carbon ring in a timely manner. If the thermocouple is directly attached to the outer wall of the carbon ring or close to the heating area, the thermocouple wire and its fixing structure will introduce additional heat conduction channels and local heat dissipation boundaries, potentially altering the local temperature field near the carbon ring and affecting the circumferential heating uniformity of the sample. Furthermore, contact temperature measurement is also affected by the contact state, installation position, and thermal inertia, making it difficult to use as the main control feedback signal for the high-temperature region of the carbon ring in this device.

[0148] For schemes employing only infrared non-contact temperature measurement, the infrared probe can acquire the apparent temperature of the high-temperature region of the carbon ring without contact, offering a fast response and avoiding disturbance to the local thermal field near the carbon ring and sample. This makes it suitable as the primary feedback signal for PID closed-loop temperature control. Through infrared temperature measurement, the system can determine whether the sample has entered the softening window based on the actual heating state of the carbon ring, and coordinate with the pre-stretch displacement response, formal stretching initiation, and breakage stage switching. However, infrared temperature measurement results may be affected by factors such as the emissivity of the carbon ring surface, measurement distance, observation angle, observation window state, and the background temperature of the heating chamber. Therefore, during device installation and use, it is preferable to maintain consistency in the infrared probe position, measurement angle, and temperature measurement area to improve the consistency of temperature feedback.

[0149] Therefore, this device preferably adopts a configuration of "infrared primary temperature measurement + thermocouple secondary temperature measurement". The infrared temperature probe is aimed at the high-temperature zone of the carbon ring, serving as the main input for the PID closed-loop temperature control of the heat source controller, providing real-time feedback on the heating status of the carbon ring. The thermocouple is placed inside the heating chamber or near the water cooler, support, etc., to monitor the ambient temperature, cooling status, or abnormal temperature rise within the chamber. The two work in a primary-secondary manner: infrared temperature measurement controls the high-temperature zone of the carbon ring, while the thermocouple assists in environmental and safety monitoring. This configuration avoids disturbances to the thermal field of the small-sized carbon ring caused by contact temperature measurement and improves the reliability of temperature feedback from the carbon ring Joule heat source during the drawing process.

[0150] To further illustrate the difference in response between thermocouple contact temperature measurement and infrared non-contact temperature measurement during the rapid heating process of carbon rings, Figure 18 Typical response curves of two temperature measurement signals during the same heating-holding-stop heating process are shown. Because the infrared temperature probe is directly aimed at the high-temperature region of the carbon ring, it can quickly follow the temperature change of the carbon ring after entering the effective temperature measurement range and form a stable feedback near the target temperature. Although the thermocouple temperature measurement signal can output readings at room temperature, its heating response is significantly lagging behind the infrared temperature measurement due to the probe's thermal inertia, installation position, contact state, and heat dissipation from the surrounding structure. Furthermore, even when the infrared temperature measurement has stabilized near the target temperature, the thermocouple reading is still lower than the temperature of the high-temperature region of the carbon ring. After heating stops, the infrared temperature measurement can quickly reflect the temperature drop in the high-temperature region of the carbon ring, while the thermocouple signal still shows a certain delay and slow decay. The above curves indicate that in the small-sized carbon ring local Joule heating structure of this device, the temperature measured by the thermocouple is difficult to accurately represent the actual temperature of the heated area of ​​the sample. If used as the PID main control feedback, it may lead to the system misjudging the temperature state of the carbon ring, affecting the softening window judgment and the switching of the pulling stage. Therefore, this device uses infrared non-contact temperature measurement as the main control feedback for the high-temperature zone of the carbon ring, and uses thermocouples for monitoring the ambient temperature, cooling status, or abnormal temperature rise of the heating chamber.

[0151] Example 8: Explanation of Material Selection for Carbon Ring Heating Element

[0152] The carbon ring heating element can be made of graphite, carbon fiber composites, pyrolytic carbon, or other carbon-based conductive materials. Different materials can generate Joule heat through an electric current; their differences mainly lie in engineering suitability factors such as processing difficulty, cost, mechanical strength, thermal shock resistance, and electrical resistance stability. This device preferably uses a graphite-based carbon ring heating element, which is easy to process, has low cost, can be fabricated into annular through-hole structures, and exhibits good thermal stability under a protective atmosphere.

[0153] Table 3. Comprehensive Engineering Compatibility Specifications for Carbon Ring Heating Element Materials

[0154]

[0155] The aforementioned material differences are mainly due to engineering selection factors for the heating element. The focus of protection in this case is not to limit a single type of carbon material, but rather to the combination of the carbon ring Joule heating element with infrared temperature measurement closed-loop control, dual servo synchronous reverse stretching mechanism, and drawing process.

[0156] Example 9: Drawing of optical fiber samples and glass capillary samples

[0157] 9.1 Drawing of fiber optic samples

[0158] To verify the applicability of this device to slender glass samples such as optical fibers, a G.652D single-mode communication fiber was selected as the drawn sample. The cladding diameter of this fiber is approximately 125 μm, and the outer coating diameter is approximately 250 μm. Figure 19 The image shows the morphology of an undrawn optical fiber under an optical microscope.

[0159] Before drawing, the outer coating of the area to be heated and drawn is removed using fiber strippers, exposing the quartz glass cladding. Partial coating is retained in the clamping areas on both sides to improve clamping stability and reduce the risk of breakage at the clamping points. During drawing, the carbon ring Joule heating source is first heated to the target temperature and kept stable. Then, the left and right guide rails move synchronously in opposite directions in position mode, slowly drawing outwards at the same speed. The fiber located in the carbon ring heating area softens and necks due to heat. Drawing stops once the left and right guide rails reach the set drawing distance.

[0160] In this embodiment, the target temperature is 1150℃, the drawing speed is 0.3 mm / s, and the drawing distance is 30 mm. After drawing, the optical fiber locally forms a continuously thinning segment with a diameter of approximately 10 μm. Figure 20 As shown in the figure. This result demonstrates that the device can achieve micron-level thinning of optical fiber samples.

[0161] 9.2 Synchronous drawing of optical fibers embedded in glass capillaries

[0162] To further verify the applicability of this device to composite samples, a G.652D single-mode communication fiber was inserted into a borosilicate glass capillary to form a glass capillary-embedded fiber composite sample. Before drawing, at least the outer coating layer of the fiber located in the carbon ring heating zone and its adjacent area was removed to ensure that the quartz glass cladding of the embedded fiber was located within the area to be drawn.

[0163] In this embodiment, a borosilicate glass capillary is used as the outer sheath, and G.652D single-mode communication fiber is used as the embedded fiber. During the drawing process, a carbon ring Joule heat source first heats the borosilicate glass capillary to a softened state. Then, the left and right guide rails apply synchronous reverse traction to the composite sample, causing the outer sheath to neck and pulling the embedded fiber together. After the sample reaches the set pre-stretch displacement threshold, the system switches to the breakage stage. A large breaking force causes the glass capillary and the embedded fiber to break in the necking region, forming a glass-clad embedded fiber composite tip structure.

[0164] In this embodiment, the target temperature is 1100℃, the minimum tensile force is 3000 counts, the pre-stretch displacement threshold is 500 μm, and the breaking tensile force is 8000 counts. The morphology of the stretched sample under an optical microscope is as follows. Figure 21 As shown, a distinct contraction structure is formed at the end of the glass capillary, and the embedded optical fiber extends along the tube axis to the tip region.

[0165] To preliminarily verify the light-guiding capability of this composite tip structure, single-mode light was coupled into the exposed side of the optical fiber at the other end of the sample. A significant light emission phenomenon was observed in the composite tip region, such as... Figure 22 As shown in the figure. The results demonstrate that, in a composite sample with an optical fiber embedded in a borosilicate glass capillary, this device can, under the same thermal field and the same set of dual-servo linkage logic, cause the outer tube to neck and simultaneously stretch the embedded optical fiber. After reaching the pre-stretch displacement threshold (500 μm), it automatically switches to the breakage stage, forming a composite tip structure of "glass-clad embedded optical fiber." Optical verification shows that this composite tip possesses actual light-guiding capability. This indicates that the present invention is not only applicable to single-material optical fibers but also to the synchronous stretching of optical fiber / glass composite samples, enabling the integrated fabrication of a composite tip with a "rigid outer sheath + retained light transmission," providing a feasible sample form for applications such as single-molecule detection devices and micro / nano fiber optic devices.

[0166] 9.3 Comparison of fiber optic and glass capillary drawing effects

[0167] To further illustrate the versatility of this device and method for different types of glass samples, a comparative analysis was conducted on the fiber drawing process (9.1) and the glass capillary composite sample drawing process (9.2). In terms of device composition, both use the same Joule heating ring module and dual-servo synchronous reverse guide rails, with adjustments made only to the process parameters and control stages to address the material softening characteristics. Regarding control logic, the fiber sample, being a single quartz-based glass material, exhibits continuous viscous flow after softening. Uniform reverse stretching in position mode is sufficient to obtain continuously thinning micro / nano fiber segments, making the control strategy relatively simple. The glass capillary embedded fiber composite sample comprises both an outer tube and an embedded fiber. A small pre-stretching force is applied, and the actual softening is determined by a displacement threshold. Once the threshold is reached, the process switches to a high-force breakage stage, causing the outer tube to neck and the embedded fiber to break together, forming a glass-coated composite tip. This control strategy emphasizes staged processing and displacement response determination.

[0168] Regarding the drawing temperature, stable micro / nano fiber segments can be obtained at 1150℃ for the optical fiber sample, while the glass capillary sample softens sufficiently at 1100℃. This indicates that the device can cover materials with different softening windows on the same heat source through PID closed-loop, without requiring hardware replacement. In terms of product morphology, the drawn optical fiber sample yields continuously variable micro / nano fiber segments with a diameter of approximately 10 μm, suitable for bare fiber micro / nano fiber devices. The drawn glass capillary composite sample forms a composite tip structure consisting of a glass tube wall covering an embedded optical fiber extending to the tip. Figure 21 ), and through Figure 22 It has been verified to have practical light guiding capabilities, and its mechanical strength and integrability are superior to bare micro / nano optical fibers, making it particularly suitable for single-molecule detection devices and micro / nano optical fiber probes.

[0169] The above comparison shows that the device and method of the present invention are universal for different glass samples: they can perform uniform stretching on single-material optical fibers, and can also perform multi-stage control of "pre-stretching - threshold determination - breakage" on multi-layer composite samples. The same set of hardware and data traceability system can simultaneously support two typical scenarios: basic research on micro-nano optical fibers and the fabrication of composite cutting-edge devices, further verifying the positioning of the present invention as a general-purpose micro-nano glass processing platform.

[0170] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A controllable tapered device that integrates Joule heating with dual servo synchronous guide rails, characterized in that, It includes a Joule heating module and a dual servo motor guide rail module; the dual servo motor guide rail module operates based on the actual temperature feedback from the Joule heating module.

2. The controllable tapered device as described in claim 1, characterized in that, The Joule heating module includes a carbon ring heating element, a DC adjustable power supply, an infrared temperature probe, and a heat source controller. The carbon ring heating element is used to form a circumferentially enveloping local thermal field in the middle of the sample. The infrared temperature probe is used to non-contactly measure the actual temperature of the carbon ring heating element or the heating area. The heat source controller is used to adjust the output of the DC adjustable power supply according to the feedback signal of the infrared temperature probe so that the heating temperature is stabilized within a set softening window.

3. The controllable tapered device as described in claim 1, characterized in that, The dual servo motor guide rail module includes two sets of servo motors (left and right), a linear guide rail, an encoder, and a motion control card. The two sets of servo motors drive the left and right slides to move axially along the linear guide rail, and the encoder is used to provide real-time feedback on the position and speed of the left and right axes.

4. The controllable tapered device as described in claim 2, characterized in that, The Joule heating module also includes a thermocouple, which is used to detect the ambient temperature and safety status of the heating chamber and serves as a temperature control compensation parameter.

5. The controllable tapered device as described in claim 2, characterized in that, The carbon ring heating element is a graphite ring, a carbon fiber composite ring, a pyrolytic carbon ring, or a silicon carbide coated carbon ring.

6. The controllable tapered device as described in claim 3, characterized in that, The motion control card uses electronic gears to make the left and right servo axes move synchronously in opposite directions at a set ratio, with one side axis being the master axis and the other side axis being the driven axis.

7. A controllable tapering method, characterized in that, The process includes fixing the middle of the sample to be stretched at the center of the thermal field of the annular Joule heating element, activating the heating element, adjusting the power output according to the actual temperature feedback from the non-contact temperature measuring device, and controlling the left and right sets of electric displacement actuators to perform synchronous reverse stretching after the temperature enters the softening window. At the same time, temperature, electrical parameters, displacement and speed data are collected synchronously, and static formula and dynamic time series data are saved.

8. The method as described in claim 7, characterized in that, Before synchronous reverse stretching, a pre-stretching force or low-speed pre-stretching is applied to the sample, and the sample is judged to produce the expected displacement response based on displacement feedback. After confirming that the sample has actually softened, the subsequent stretching or breakage stage is entered.

9. The method as described in claim 8, characterized in that, The sample is one or more of the following: single-channel capillary, dual-channel capillary, multi-channel capillary, borosilicate glass capillary, quartz capillary, optical fiber, coated wire, or prefabricated electrode carrier.

10. Use of the controllable tapering device according to any one of claims 1 to 6 or the controllable tapering method according to any one of claims 7 to 9 in the preparation of nanopipettes, nanopore precursors, single-molecule detection devices, micro / nano optical fibers or other micro / nano glass / quartz devices.

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