Method for homogenizing the structure of the high-performance tool steel collar of a paper cutter

Abstract

This invention discloses a heat treatment method for homogenizing the microstructure of the rim of a high-performance tool steel paper cutter, relating to the field of paper cutter heat treatment technology. The method includes the following steps: After preheating the rim to a subcritical state, a polarization pulse is applied through a follower contact electrode to form a surface deconstruction zone and superequilibrium vacancies on the rim surface; the follower contact electrode is then fixedly connected to a follower jet assembly to limit the transfer lag time of the surface deconstruction zone into the cryogenic medium; subsequently, an alternating magnetic field is synchronously applied in the cryogenic medium jet zone to break the surface vapor isolation film and freeze the superequilibrium vacancies; finally, acoustic emission signals are collected during the tempering cycle, and an alternating magnetic field is applied based on the characteristic acoustic signature closed loop to control the segregation and precipitation of carbon atoms towards the frozen vacancies. This method maintains the rigidity of the blade back and the stability of the bimetallic interface, achieving microstructure refinement and precipitation homogenization of the rim, and is applicable to the rim heat treatment of bimetallic composite paper cutters.

Description

Technical Field

[0001] This invention relates to the field of heat treatment technology for paper cutters, specifically a heat treatment method for homogenizing the microstructure of the pressing edge of a high-performance tool steel for paper cutters. Background Technology

[0002] In actual industrial applications, paper cutters are generally used in continuous processes such as three-sided cutting of books and periodicals, paper stack cutting, and cardboard slitting. Paper cutters are generally long and wide blades, and during operation, they involve reciprocating shearing, clamping and sharpening, and batch blade changes with a large cycle time. This requires the blade working area to have stable hardness, wear resistance, and consistent cutting edge, as well as the entire blade to have straightness, flatness, and stable mounting dimensions. Therefore, the heat treatment process not only affects the blade life but also the cutting edge quality, equipment cycle time, and the number of sharpening cycles.

[0003] In the prior art search, the closest prior art is the heat treatment process for alloy tool steel cutting tools described in Chinese patent application CN112481472A. This document employs a process of vacuum quenching, delayed cooling, rapid oil bath cooling, room temperature cooling, and tempering of the entire formed alloy tool steel cutting tool. Specifically, the entire cutting tool is heated and held in a vacuum to enter the austenitizing stage; then it is placed in a vacuum to stand; next, the entire cutting tool is rapidly cooled in an oil bath, followed by tempering; finally, a balance between hardness and brittleness is found during tempering. A dependent solution could add a deep cryogenic step after room temperature, using low-temperature nitrogen and a controlled cooling rate for deep cryogenic treatment.

[0004] The basic concept of the above technology is to treat the blade as a monolithic component with relatively consistent material, cross-section, and thermal response. Therefore, its main control objectives are the overall austenitization, overall quenching, and overall tempering of the entire blade. In the working scenario of long-width bimetallic composite paper cutters, this path is prone to structural gaps: On the one hand, the material composition, thermal and electrical conductivity, cross-sectional stiffness, and phase transformation sensitivity of the edge working area and the back of the blade are inconsistent. High-temperature holding and rapid cooling of the entire blade will cause heat, stress, and phase transformation to couple and diffuse along the thickness and length directions. On the other hand, vacuum standing, rapid cooling in an oil bath, and deep cooling after room temperature are boundary conditions at the blade scale, which makes it difficult to independently constrain the microstructure evolution of the micro-region of the cutting edge. This can easily lead to inconsistent microstructure along the length direction of the cutting edge, accumulation of thermal distortion of the blade body, changes in the performance of the bimetallic bonding area, and increased costs for re-grinding and blade replacement.

[0005] In summary, existing technologies make it difficult to achieve controllable and consistent homogenization of the microstructure in the critical working area of ​​the bimetallic composite paper cutter edge without altering the overall blade size and interface stability. Summary of the Invention

[0006] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a heat treatment method for homogenizing the microstructure of the edging edge of a high-performance tool steel paper cutter. This method involves fixing a follow-up contact electrode to a follow-up jet assembly, limiting the transfer lag time of the surface deconstruction zone into the cryogenic medium. Subsequently, an alternating magnetic field is synchronously applied in the cryogenic medium jet zone to break the surface vapor barrier film and freeze superequilibrium vacancies. Finally, acoustic emission signals are collected during the tempering cycle, and an alternating magnetic field is applied in a closed loop based on characteristic acoustic signatures to control the segregation and precipitation of carbon atoms towards the frozen vacancies. This method maintains the rigidity of the blade back and the stability of the bimetallic interface, achieving microstructure refinement and precipitation homogenization of the edging edge, thereby solving the technical problems described in the background art.

[0007] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: A heat treatment method for homogenizing the microstructure of a high-performance tool steel edge for a paper cutter, the paper cutter comprising a low-carbon steel blade body and a high-performance tool steel edge composited around the blade body edge, including... The pressure edge is locally preheated to a subcritical state, and a high-frequency polarization pulse is applied along the extension direction of the strip carbide through the follower contact electrode to form a surface deconstruction region and super-equilibrium vacancies on the surface of the pressure edge, while maintaining the cold rigidity of the back of the tool body; the follower contact electrode is fixedly connected to the follower jet assembly and follows the movement, and the transfer lag time of the surface deconstruction region into the cryogenic medium is limited by the physical spacing and scanning speed. An alternating magnetic field is simultaneously applied in the cryogenic medium injection zone to break the surface vapor isolation film and freeze the superequilibrium vacancies. Acoustic emission signals are collected in the subsequent tempering cycle, and an alternating magnetic field is applied according to the characteristic acoustic pattern closed loop to control the segregation and precipitation of carbon atoms to the frozen vacancies.

[0008] Furthermore, the paper cutter is rigidly clamped onto the clamping base, so that the back of the cutter body is against the back support with a circulating cooling channel, and a continuous electrical insulation pad is set between the back of the cutter body and the back support; the preheating module only establishes a follow-up heating zone for the local pressing edge.

[0009] Furthermore, the follower contact electrode includes a front roller electrode and a rear roller electrode arranged in a front-to-back manner along the scanning direction. Both the front roller electrode and the rear roller electrode are pressed against the edge side. The front roller electrode injects a polarization pulse current, and the rear roller electrode recovers the polarization pulse current and closes the polarization pulse current near the surface of the edge.

[0010] Furthermore, an impedance monitoring unit and a gate driver are connected in series in the output circuit of the polarization pulse current; the controller synchronously determines the sampling voltage and sampling current, and when the circuit impedance changes from the surface closed state to an abnormal bypass state that shifts towards the back of the tool body or the bimetallic joint surface, the controller controls the gate driver to turn off the pulse output and switches to the induction heat preservation state.

[0011] Furthermore, the follower contact electrode and the follower jet assembly are fixed on the same spindle slide and continuously follow along the length of the pressure edge. The follower jet assembly is located after the follower contact electrode. The controller limits the transfer lag time of the same point based on the physical distance between the roller electrode conduction center and the nozzle spray center and the spindle scanning speed.

[0012] Furthermore, the follow-up jet assembly performs a low-flow pre-blowing before the main jet to displace ambient air and condensed water vapor from the pressure edge surface and maintain the jet center corresponding to the surface deconstruction zone; the controller combines the transfer lag time and the pressure edge surface temperature trajectory to determine the main jet permission, and only opens the main jet valve group when the surface deconstruction zone reaches the cryogenic medium access zone.

[0013] Furthermore, an annular induction coil is fitted around the nozzle of the follow-up jet assembly. The central axis of the annular induction coil coincides with the nozzle axis and moves synchronously with the main shaft slide. At the same time as the main spray valve group is opened, an alternating magnetic field is applied to the annular induction coil, so that the cryogenic medium coverage area and the alternating magnetic field coverage area fall together on the surface deconstruction area.

[0014] Furthermore, the controller maintains the output of the alternating magnetic field based on the surface normal vibration velocity at the injection point. The surface normal vibration velocity is determined by the current alternating magnetic field frequency and the corresponding vibration amplitude. When the surface normal vibration velocity reaches the continuous film rupture threshold, the main injection valve group and the ring induction coil are kept working synchronously so that the steam isolation membrane is in a continuous rupture state.

[0015] Furthermore, during the tempering cycle after deep cooling, an acoustic emission sensor array is set at the cold end of the tool body, and a reference sensor is set at the clamping base; the controller performs homologous discrimination on the sampling signals of the acoustic emission sensor array and the reference sensor, and retains only the lattice acoustic pattern conducted along the tool body by self-pressure as the input for subsequent state determination.

[0016] Furthermore, the controller sequentially performs bandpass filtering, short-time framing, frequency domain analysis, and stage determination on the lattice acoustic pattern to extract composite characteristic acoustic patterns that characterize martensitic shear, carbon atom desolvation, and segregation nucleation; and performs phase-locked drive on the alternating magnetic field based on the current main characteristic acoustic pattern, stopping the magnetic field output at the end of the tempering cycle.

[0017] (III) Beneficial Effects This invention provides a heat treatment method for homogenizing the microstructure of the rim of a high-performance tool steel for paper cutters, which has the following beneficial effects: By locally preheating the pressure edge to a subcritical state, a polarization pulse is applied to the servo contact electrode along the extension direction of the ribbon-like carbide, forming a surface deconstruction zone and superequilibrium vacancies on the surface of the pressure edge. This disperses the large eutectic carbides, preventing the thermal impact from diffusing to the back of the blade, and creating a pre-tissue state for the cryogenic medium inlet. By rigidly connecting the servo contact electrode and the servo jet assembly, the transfer hysteresis time is determined by the physical spacing and scanning speed. This ensures that the surface deconstruction zone enters the cryogenic medium inlet region before the superequilibrium vacancies decay, reducing the recovery consumption caused by high-temperature dwell time, and transferring the tissue formed in the previous step to the next step.

[0018] By applying an alternating magnetic field in the cryogenic medium injection zone, the resistance of the vapor isolation film to heat exchange is reduced, ensuring that the cryogenic medium repeatedly contacts the exposed metal surface, avoiding surface fog obscuring and insufficient internal cooling, and ensuring that the surface deconstruction zone plays a cryogenic role.

[0019] The superequilibrium vacancies retained in step two are converted into frozen vacancies in step three. Precipitation sites that can be recycled during the next tempering stage are obtained on the surface of the pressure edge. This allows the previous processing to continue after deep cooling, and the microstructure reconstruction becomes a controllable and stable evolutionary state. Acoustic emission signals are acquired at the cold end of the blade during the tempering cycle. An alternating magnetic field is applied based on the characteristic acoustic signature closed loop, causing the carbon atom segregation and precipitation to proceed according to the microstructure stage, rather than applying the same beat at different pressure edge positions at a fixed time. This establishes a correspondence between the precipitation process and the frozen vacancies.

[0020] By forming a surface deconstruction zone, constraining the transfer lag time, breaking the vapor isolation membrane, retaining the frozen vacancy, and driving the characteristic sound pattern closed loop, a four-step synergistic process chain can be formed during the heat treatment of the bimetallic composite paper cutter, which can achieve homogenization of the edge structure, maintenance of the rigidity of the back of the blade, and stability of the bimetallic bonding surface. Attached Figure Description

[0021] Figure 1 This is a system architecture diagram of the present invention for the photovoltaic storage and charging scenario; Figure 2 This is a diagram of the internal hardware structure of the dual-core smart meter of the present invention; Figure 3 This is a flowchart illustrating the overall process of the energy management method of the present invention. Figure 4 This is a diagram of the homogeneous sampling and cross-chip wake-up mechanism in step one of the present invention; Figure 5 This is the state freezing and sparse tensor tree addressing diagram for step two of the present invention; Figure 6 This is the microscopic solid-phase diffusion constraint flow diagram for step three of this invention; Figure 7 This is the protocol compliance wave packet shaping and DC bus compensation diagram for step four of the present invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Please see Figures 1-7 This invention provides a heat treatment method for homogenizing the microstructure of the rim of a high-performance tool steel for paper cutters. The research focuses on the most challenging aspect of bimetallic composite paper cutters: the edge microstructure. The goal is not simply to increase the temperature, but to apply localized excitation only to the surface layer of the high-performance tool steel edge while maintaining low-temperature rigidity on the back of the blade. This process first deconstructs the coarse eutectic carbides that originally extended continuously along the rolling direction, leaving a super-equilibrium vacancy layer in the matrix that can be taken over by subsequent cryogenic steps.

[0024] Therefore, all the following actions are performed by the same multi-field coupled CNC follow-up machine tool. The machine tool simultaneously undertakes five types of tasks: clamping, localized preheating, waveform output, impedance sampling, and abnormal cut-off. This consolidates the material state, power-on path, and subsequent freezeable objects into the same process chain, avoiding the chain break situation where heating is separate from power-on and subsequent steps cannot be continued.

[0025] Step 1: Without expanding the thermally affected zone of the bimetallic interface, construct a directionally electrified deconstruction zone and an inheritable superequilibrium vacancy layer on the pressure edge surface to provide a clear input object for the transfer delay control in Step 2.

[0026] The challenge of bimetallic composite paper cutters lies not in heating the edge, but in the inherent differences in electrical conductivity and thermal capacity between the edge and the low-carbon steel blade body. If conventional overall heating or low-frequency high-current direct-flow methods are used, the current will preferentially diffuse along the low-resistance path, and the heat will also spread laterally along the bimetallic interface. As a result, the banded carbides inside the edge are not yet broken down, but the back of the blade body enters the softening zone first, followed by blade deflection, stress redistribution at the interface, and uncontrolled dimensional rebound of the edge.

[0027] Therefore, a continuous processing approach was adopted, which first shrinks the hot zone to the pressure edge, then locks the current to the surface of the pressure edge, and finally cuts off the abnormal bypass at the moment of its inception, so that material modification and structural conformation can be compatible within the same time window.

[0028] In the process chain, step one does not aim to complete the entire microstructure at once, but rather to first generate a surface deconstruction zone with controlled thickness. This surface deconstruction zone needs to simultaneously meet three conditions: First, the pressing edge locally reaches a subcritical high temperature so that stress concentration and atomic migration channels at the eutectic carbide boundary are opened; second, the high-frequency polarization pulse closes only on the surface of the pressing edge and does not extend to the back of the tool body and the deep part of the bimetallic interface; third, once the circuit impedance exhibits an avalanche-like drop, the system immediately exits the pulse mode, preserving the already formed thermal state and preventing bypass current from continuing to damage the interlayer structure.

[0029] A continuously laid electrically insulating pad is provided between the low-carbon steel blade body and the copper alloy back support. This electrically insulating pad is preferably made of alumina ceramic or silicon nitride ceramic, used to confine the back support as a mechanical support and back heat dissipation component, rather than as a pulse circuit conductor. The pair of follower roller electrodes are both arranged on the pressure edge side. A pulse current is injected by the front roller electrode and recovered by the rear roller electrode, closing the circuit near the pressure edge surface. The roller electrode clamping force is denoted as... The contact width is denoted as The contact arc length is denoted as The effective contact area ;in, Set by a spring loading mechanism or a servo clamping mechanism, and Obtained through calibration using indentation test pieces or pressure-sensitive paper, and calculated as follows Write to the controller to calculate pulse current density And check the surface conduction status.

[0030] The machine tool places the bimetallic composite insert horizontally along its length on a gantry clamp. The low-carbon steel insert body rests against a copper alloy backing seat with an internal circulating water cavity, with the pressing edge facing the side of the induction coil and the servo electrode's movement trajectory. This arrangement is not simply for clamping, but rather to transform the back of the insert body into a stable, low-temperature support, making the pressing edge the only actively heated working area. The induction coil uses a narrow magnetic field window extending along the length of the pressing edge, its width covering the pressing edge while avoiding the back of the insert body. Temperature acquisition is accomplished by both an infrared thermometer and an embedded thermocouple; the former tracks the temperature rise on the pressing edge surface, while the latter checks whether the hot zone has penetrated too deeply into the bimetallic interface.

[0031] In one exemplary embodiment, the operator first feeds the long bimetallic composite blade into the clamping frame. After the back of the blade is aligned with the support, the flatness is locked by the pressure blocks on both sides. Subsequently, the induction coil starts from one end of the blade and slowly moves along the pressure edge. The screen only shows the local temperature zone along the pressure edge moving forward, while the back of the blade maintains its original metallic luster and does not show an overall reddening phenomenon. It can be directly seen on site that the heated area always moves along the pressure edge and does not cross over to the back of the blade.

[0032] The reason for controlling the local pressure edge within the subcritical range of 900℃ to 980℃, instead of pushing the entire pressure edge to a higher temperature, is that this temperature window is sufficient to weaken the binding of the carbide boundary and increase the dislocation slip activity, without simultaneously bringing the entire tool body into a fully austenitic unstable state.

[0033] In other words, by first separating the areas that need to be modified by current and the areas that must continue to bear geometric constraints through thermal field partitioning, it is equivalent to drawing an invisible process boundary on the structure. The direct result of this arrangement is that the subsequent pulse current no longer needs to undertake the task of large-scale preheating, but only needs to act on the surface layer of the pressure edge that has been softened to a suitable state, reducing ineffective heat input from the source; at the same time, the back of the tool body continues to bear geometric support, so that the pressure edge does not wobble due to overall instability when the surface layer is subsequently deconstructed.

[0034] When the local temperature of the pressure edge enters the subcritical range of 900℃ to 980℃, the controller issues a contact permission to the follower roller electrode. The two roller electrodes press against each other along the length of the pressure edge and make the current input direction consistent with the extension direction of the ribbon carbide.

[0035] The emphasis on directional consistency stems from the fact that ribbon-like carbides are inherently continuous, hard, and brittle channels. If the current enters obliquely, electron momentum disperses between different structural boundaries, making it difficult to form continuous deconstruction bands within the same shallow layer. Conversely, when the current propagates along the direction of the ribbon-like carbides, local electromigration and thermal stress release unfold along the existing brittle network, making it easier to disassemble the continuous network structure into discrete fragments. The pulse waveform is generated by a high-speed timing board, or alternatively by a pulse controller with equivalent functionality. Its output is an asymmetric alternating square wave, with the pulse fundamental frequency denoted as... The pulse current density is denoted as .in: Skin depth The equivalent penetration depth of the high-frequency polarization pulse in the edge is preferably controlled between 5 and 8 mm, which is used to confine the main electron momentum within the deconstructed region of the edge surface; it is a calculation quantity used by the controller for frequency selection during the process design stage.

[0036] resistivity The equivalent volume resistivity of the material under subcritical conditions is taken as 0.6 × 10⁻⁶. -6 Up to 1.8×10 -6 This is used to reflect the change in conductivity of the pressure edge after heating; the preferred method for obtaining this value is: first, perform four-terminal resistance measurement on small samples of the same steel grade and before heat treatment to establish a temperature-resistivity calibration curve; then, on the production line, use the measured temperature as the independent variable to look up a table or interpolate the value. Magnetic permeability The equivalent permeability of the material under subcritical conditions, taking a value of It is used together with the pulse fundamental frequency to determine the degree of current adhesion to the surface layer; the preferred method of obtaining it is to perform high-temperature magnetic response calibration on samples of the same steel grade, or to use the initial value from the material handbook and correct it with a small sample.

[0037] pulse fundamental frequency The fundamental frequency of the asymmetric alternating square wave is 1.0 × 10⁻⁶. 4 Up to 8.0×10 4 Hz is used to compress the current distribution to the surface of the pressure edge instead of allowing it to diffuse deeper; it is directly given by the pulse drive unit and set by the controller. In the formula, pulse current density The current carrying capacity per unit contact area is taken as 1.0 × 10⁻⁶. 3 Up to 8.0×10 3 A / cm 2 Used to provide sufficient electron wind momentum for the deconstruction of eutectic carbides; pulsed current The instantaneous output current when the roller electrode closes is determined by matching the pressure edge width and contact area, and is used to form a polarization pulse that propagates directionally along the surface of the pressure edge; the contact area... The effective conductive contact area formed between the roller electrode and the pressing edge surface is determined by the roller width, pressing amount, and surface roughness. It is used to stabilize the current density and avoid local arcing.

[0038] The asymmetric alternating square wave is preferred because the forward pulse segment carries the main momentum injection, while the reverse pulse segment carries the local depolarization and surface heat accumulation release. This alternation ensures that the surface layer can maintain high-energy electron wind impact without forming continuous erosion grooves under unidirectional long pulse widths. In the production environment, this waveform arrangement results in a uniformly moving narrow bright band on the pressure edge surface, rather than a flickering dot-like arc.

[0039] In a preferred embodiment, the front roller electrode uses a tungsten-copper composite conductive layer, and the rear roller electrode uses a molybdenum-based conductive layer. Both float along the edge contour via an insulating swing arm. The CNC system simultaneously outputs pulses based on temperature compliance signals and displacement encoder signals. Therefore, the roller electrodes are not blindly energized on cold metal, but rather surface energy is injected only after the edge has entered a subcritical window. The visible result is a continuous narrow bright band on the edge surface, with no large-area erosion marks behind it, indicating that the decomposition occurs in the shallow layer rather than deep ablation. Besides dual roller electrodes, a combination of one roller electrode and one arc-shaped slipper electrode can also be used, as long as the current remains closed on the edge surface, the decomposition mechanism remains consistent.

[0040] After completion, the coarse eutectic carbides change from a continuous banded state to a discrete and fragmented state, leaving a large number of vacancy defects in the pressure-edge matrix that have not yet recovered equilibrium. More importantly, these vacancy defects are not randomly scattered throughout the entire tool body, but are confined to the surface deconstruction region that can be rapidly taken over by the cryogenic medium. Therefore, they provide a clear and inheritable material object for the short-term transfer in step two.

[0041] High-frequency skin contact alone is not enough to guarantee process stability, because if the oxide film breaks, the contact water film invades, or there is local bridging near the bimetallic interface, the current may still suddenly shunt along the low-carbon steel blade body.

[0042] To prevent this shunting from dragging the aforementioned surface deconstruction region into the runaway hot zone, a microsecond-level impedance monitoring unit is connected in series in the circuit. The monitoring unit can employ a four-terminal voltage and current synchronous sampling circuit, or a combination of a Rogowski coil and a high-speed voltage divider probe. Its output is sent to the decision channel before the gate driver. The controller does not wait for the arc to form before stopping; instead, it triggers cutoff as soon as the avalanche leading edge appears on the impedance curve. Specifically: In the formula, impedance drop-off rate The degree of drop in current loop impedance relative to the reference impedance, preferably with a threshold of 0.18 to 0.35, is used to convert potential bypass shunting states into determinable hard trigger values; reference impedance. The reference impedance is determined when the roller electrode is in stable contact and the current is only closed at the surface of the pressure edge. Its value is obtained from calibration during no-load testing and low-energy test runs, and is used to provide a comparison benchmark for normal conduction. On a standard cutting tool of the same steel grade, the impedance is continuously collected for multiple pulse cycles in low-energy test mode, and the median or moving average value of the results is taken as the reference impedance. Current loop impedance The instantaneous loop impedance during pulse processing varies with contact state, material temperature, and surface structure, and is used to reflect whether an abnormal bypass channel has occurred. It is obtained by synchronous sampling using a four-terminal method, with voltage and current acquired in the same period.

[0043] Reference impedance Acquired from standard inserts of the same steel grade in low-energy scanning mode, the controller continuously... The median value of the loop impedance for each sampling window is taken as... The current loop impedance The sampling frequency is measured in real time by a four-terminal synchronous sampling circuit. Not lower than the pulse fundamental frequency Ten times that. When the impedance dropout rate Exceeding the threshold At this time, the gate driver turns off the insulated gate bipolar transistor before the end of the current pulse cycle and maintains the induction insulation state.

[0044] Current loop impedance Based on the sampling voltage within the current pulse period and sampling current calculate: Reference impedance From the low-energy test phase continuously Establish the average loop impedance over one stable pulse cycle: in, The effective voltage of the current pulse period is obtained by synchronous sampling using the four-terminal method; The effective current for the same pulse period; Used to characterize the current circuit conduction state; The number of stable pulse cycles used to establish the reference impedance; For the first The loop impedance corresponding to one stable pulse cycle. Used to represent the reference impedance under normal surface conduction conditions; Used to determine whether the current loop has transitioned from a surface-closed loop to an abnormal bypass. When impedance drop rate... Exceeding the threshold At this time, the gate driver turns off the insulated gate bipolar transistor before the end of the current pulse cycle and switches to inductive heat preservation mode.

[0045] In one exemplary embodiment, when oxide scale residue is present in a localized area of ​​the blade, the impedance curve on the screen will initially show a brief dip. The gate driver then turns off the insulated-gate bipolar transistor, and the induction coil continues to maintain its in-situ temperature. The operator can see the roller electrode lift while the edge temperature does not drop sharply, indicating that the system has maintained its hot state and rejected abnormal power supply. After the edge surface is cleaned, the roller electrode re-attaches, and the pulse is reintroduced. If the production line uses a dry protective atmosphere, the impedance threshold can be linked to the atmosphere dew point for correction, but the judgment object remains the impedance drop rate. The terminology and control chain remain unchanged.

[0046] From a microscopic perspective, impedance drop is not merely an electrical anomaly signal; it typically corresponds to a transient event where a closed surface pathway is rewritten into a cross-layer pathway. Once this event persists, the back of the blade will be passively involved in the heating process, breaking the aforementioned low-temperature rigidity maintained by the back support. Therefore, the preferred execution sequence here is to cut off the fault first and then determine the cause, rather than observing while powering on. The purpose of this step is to limit the most dangerous failure mode to its nascent stage, ensuring that high-frequency surface deconstruction and blade back conformation no longer interfere with each other. After completion, step one outputs not an abstract heating state, but three intermediate results that can be directly followed by subsequent steps: first, a surface deconstruction zone with a clearly defined spatial location; second, a super-equilibrium vacancy layer distributed within this surface deconstruction zone; and third, the blade back, still maintaining low-temperature rigidity, and the bimetallic interface unaffected by overheating. Thus, localized preheating solves the problem of heat distribution that cannot be simultaneously addressed by the pressure edge and the back of the cutter body; skin polarization pulse solves the problem that eutectic carbides are difficult to be directionally disassembled in shallow layers; and impedance avalanche identification restricts abnormal bypass to the early stage of cutability.

[0047] Step 2: The superequilibrium vacancy layer formed in the surface deconstruction zone in Step 1 is sent into the cryogenic medium control zone in a controlled and reproducible transfer hysteresis relationship, so that the superequilibrium vacancy layer maintains sufficient survival density before reaching Step 3.

[0048] Although step one has already obtained a surface deconstruction region and a superequilibrium vacancy layer on the cutting edge, this superequilibrium vacancy layer is not stable. As long as the cutting edge remains in the high-temperature region, the vacancies will re-migrate and annihilate along grain boundaries, dislocation entanglement regions, and carbide fracture boundaries. Traditional heat treatment lines often mount electrodes, nozzles, and guide wheels on different supports, relying on manual adjustment of paths and cycles. Superficially, it appears to be the same production line, but in reality, each mechanism operates according to its own inertia. Ultimately, this results in different transfer times for the preceding and following sections of the same batch of cutting tools, and the surface deconstruction region has already undergone varying degrees of recovery before entering the cryogenic medium.

[0049] Therefore, shortening the process time is not understood as a general assembly line cycle time problem, but rather as a survival problem of completing the medium connection before the superequilibrium vacancy layer has significantly decayed. Accordingly, step two no longer discusses a single time value, but rather considers the physical spacing... Scanning speed Transfer lag time and vacancy survival factor Placed within the same constraint chain, the path length is determined by the mechanism's position, the travel speed is determined by the interpolation program, and the timing of the cryogenic medium connection is determined by both of these factors.

[0050] First, the machine tool structurally connects the roller electrode and the jet nozzle to the same spindle slide, ensuring that the surface deconstruction zone, after leaving the roller electrode, will inevitably follow a fixed path to the jet nozzle. Second, the CNC system reads the combined signals from the spindle encoder, linear scale, and nozzle position switch to control the scanning speed. Perform continuous interpolation to make the physical spacing It will not be randomly amplified during operation. Finally, based on the position of the surface deconstruction zone output in step one, the controller allows the cryogenic medium to enter at a predetermined time, without allowing the jet to prematurely flush the pressure edge that is still in the energized state, and without allowing the jet to lag behind until a large number of superequilibrium vacancy layers have migrated back.

[0051] In this step, the jet nozzle only performs spatial following, jet alignment, and low-flow pre-blowing protection; it does not undertake the main quenching function. The low-flow pre-blowing protection is used to displace ambient air and condensed water vapor from the pressure rim surface; its flow rate is lower than the main jet flow rate and it does not serve as the main heat transfer source for freezing vacancies. The controller is based on the physical spacing. Scanning speed and vacancy survival factor Joint determination shall be made if and only if Not exceeding the preset upper limit and Not lower than the minimum survival threshold When the main injection permit signal is received, the main injection valve group is opened and an alternating magnetic field is superimposed.

[0052] In this design, the machine tool sequentially arranges a roller electrode mounting base, an insulating isolation section, and a jet nozzle mounting base on the same spindle slide. These three components are arranged sequentially along the scanning direction, with the roller electrode in the front and the jet nozzle in the rear. A low-thermal-expansion alloy connecting rod maintains a constant center distance between them. The insulating isolation section is sandwiched between the two components to prevent reverse coupling of the jet pipeline into the pulse circuit. A ceramic heat insulation sleeve is installed on the outside of the connecting rod to reduce the drift effect of radiant heat from the pressure edge on the center distance. With this arrangement, the roller electrode is responsible for completing the surface deconstruction action in step one, and the jet nozzle follows closely along the same trajectory; neither needs to be separately aligned with the same pressure edge line.

[0053] In a preferred embodiment, after the operator feeds the starting end of the cutting tool into the machine tool, the roller electrode can be directly observed moving forward along the pressure edge, with the jet nozzle always following behind, without any independent oscillation between the two. Even if there is slight edge undulation in a localized area of ​​the cutting tool, the spindle slide simply follows as a whole, preventing the electrode from pressing against the pressure edge while the nozzle deviates to the back of the cutting tool. The most easily observable result on-site is that the position where the roller electrode leaves and the position where the jet nozzle arrives always move along the same narrow band, indicating that the surface deconstruction zone formed in step one does not deviate from the predetermined path during the transfer process.

[0054] This configuration is not simply a matter of assembling two components together; rather, it transforms the transfer path of the empty space into a spatial topology directly defined by the mechanism. In this way, subsequent timing control no longer deals with the starting and ending points of the drift path, but instead obtains a clear transfer window based on fixed geometric relationships. For long components like bimetallic composite paper cutters, this spatial topology locking directly alleviates the inconsistency in fabric structure caused by the different relative displacements of the mechanism between the front and rear sections of the pressure edge, while retaining alternative implementation paths: the jet nozzle can adopt either a single-hole circular jet configuration or a slit jet configuration that expands along the width of the pressure edge. As long as the jet centerline and the roller electrode's running trajectory remain in the same surface deconstruction zone, the technical principle remains unchanged.

[0055] After the spindle common configuration is determined, the geometric path is further transformed into a definite transfer hysteresis relationship. The CNC system reads the spindle position pulses and, combined with the displacement feedback from the linear grating ruler, continuously calculates the moment when the roller electrode leaves a certain pressure edge position. Using this moment as the zero point, it calculates the time difference between the jet nozzle reaching the same position. This time difference is not an abstract timing at the software level, but rather determined by the physical distance. and scanning speed The decision is made jointly, therefore, as long as both are continuously constrained, the transfer lag time... It was then implemented in hardware. The relationship can be described as follows: Where: transfer lag time The time interval between the surface deconstruction zone detaching from the roller electrode and reaching the jet nozzle spray center is preferably controlled between 0.5 and 30 seconds, used to define the duration of the superequilibrium vacancy layer exposed to the high-temperature recovery environment; physical spacing. The equivalent center distance between the roller electrode conduction center and the jet nozzle spray center along the scanning direction is determined by the connecting rod length and assembly position in the main spindle co-frame configuration. Scan speed The travel speed of the spindle slide along the length of the pressure edge is preferably matched synchronously with the length of the temperature compliance zone in step one; the acquisition method is the fusion of a servo encoder and a linear grating ruler.

[0056] To avoid scanning speed Sudden drops occur during start-up, stopping, and corner correction. The interpolation program preferably uses a spline interpolation method with limited accelerometer, but a seven-segment speed planning method that ensures continuous speed can also be used. The controller does not simply provide an average speed; instead, it recalculates the spindle setpoint within each sampling period based on the current position, remaining path, and nozzle positioning status, ensuring the physical distance... Under fixed conditions, scanning speed The transfer time is not delayed due to local yielding actions. Exceeding the scheduled window.

[0057] In one exemplary embodiment, after the blade tip enters the stable section, the position curve and speed curve on the screen unfold synchronously. The operator will see that after the roller electrode passes a certain point on the pressure edge, the jet nozzle arrives at the same point at a fixed subsequent moment. If the machine tool increases the clamping height due to changing the pressure block, the controller first recalibrates the physical distance. The projected value is then used to allow the spindle to start again, instead of using the old scan speed. The direct result of this processing is that the initial, middle, and final sections of the same blade all follow the same transfer hysteresis relationship, preventing premature decay of the superequilibrium vacancy layer in certain regions due to human estimation errors.

[0058] In practice, the critical gating in step two relies on verifiable mechanical spacing and displacement feedback. This arrangement works in conjunction with the surface deconstruction zone in step one; the former determines where the surface deconstruction zone forms, and the latter determines when the surface deconstruction zone is taken over by the cryogenic medium. Together, they form a continuous process chain.

[0059] Furthermore, in terms of physical spacing and scanning speed Jointly determine the transfer lag time After that, it is necessary to determine whether this time window is sufficient for the superequilibrium vacancy layer to enter step three.

[0060] Therefore, the controller inputs the surface temperature trajectory of the pressure edge into the vacancy attenuation calculation unit, and obtains the vacancy survival factor based on the initial surface temperature value at the end of step one and the temperature measurement results during the transfer stage. Its expression is written as: Where: vacancy survival factor : The transfer lag time of the superequilibrium vacancy layer The retention level at the end of step one, relative to the retention level at the end of step one, ranges from [value missing]. This is used to convert the vacancy decay process into a quantity that can be used for injection trigger determination; vacancy decay rate The equivalent rate at which vacancies migrate and annihilate towards grain boundaries, dislocation entanglement regions, and carbide fracture boundaries within the surface deconstruction region, with values ​​varying with the surface temperature at the pressure edge. Pre-rate factor : Represents the initial attenuation scale of materials of the same steel grade under the calibration reference. The preferred method for obtaining this scale is fitting a small-sample isothermal residence test of the same steel grade. Apparent activation energy : Represents the equivalent energy barrier of the vacancy annihilation process, preferably obtained by fitting parameters from two or more isothermal residence experiments. Universal gas constant. Surface temperature: A mathematical physical constant that can be directly used in this field. : Represents the surface temperature of the pressure edge during the transfer process, preferably obtained by a combination of dual-color infrared thermometry and embedded thermocouple; in discrete implementation, it is denoted as the . Surface temperature at each sampling point .

[0061] Surface temperature trajectory The temperature change of the pressure edge surface from the moment the roller electrode leaves the nozzle to the moment the jet nozzle is connected is a function of time. The value is obtained by fitting the infrared thermometer and the thermocouple together, and is used to calculate the vacancy decay rate. Provide thermal history input; transfer lag time In this formula, the definition from the previous formula is continued to give the upper limit of integration, thereby linking geometric motion with the calculation of vacancy survival; When vacancy survival factor When the preset lower limit is met, the controller opens the jet valve assembly, allowing the cryogenic medium to precisely access the surface deconstructed zone; when the vacancy survival factor... When the pressure drops below a preset lower limit, the controller does not force spraying, but instead first reduces the fluctuation of the scanning speed and shortens the physical spacing. The assembly compensation amount or the surface deconstruction zone of step one is re-established before entering the next cycle. If the superequilibrium vacancy layer has been significantly decayed, even if extremely strong cryogenic and alternating magnetic fields are applied in step three, it will be difficult to restore the vacancy group that should have been frozen, and the problem will be postponed to the subsequent tempering stage.

[0062] In a preferred embodiment, the operator can observe the following continuous on-site action: after the roller electrode leaves the pressure edge, the nozzle does not immediately dispense liquid, but rather opens only after the spindle slide has moved forward a short distance; once opened, the spray band precisely covers the narrow area just traversed by the roller electrode, rather than covering the wider surface of the cutter body. If the nozzle position shifts due to a cutter change on the production line, the system first requires a re-measurement of the physical spacing. Otherwise, the jet valve assembly will not be released. The effect of this implementation is not an abstract control improvement, but rather to retain the superbalanced vacancy layer within the space window that can be directly frozen in step three.

[0063] As a parallel extension, if the production line adopts a symmetrical arrangement of dual nozzles, the equivalent spray centers of the two nozzles still correspond to the same physical distance. Definition: If the production line uses an annular covering nozzle, the position of the geometric center of the annular opening projected onto the pressure edge trajectory is taken as the jet nozzle spray center, and the aforementioned transfer hysteresis relationship remains unchanged.

[0064] When used, via vacancy survival factor By linking the thermal microstructure results of step one with the cryogenic nozzle conditions of step three into a closed loop, step two becomes not a simple transport section, but a survival-gated section that determines whether the superequilibrium vacancy layer still has the value for subsequent freezing. At the same time, the cryogenically rigid back of the blade and the bimetallic interface that has not been disturbed by overheating continue to provide geometric constraints throughout the transfer process, preventing the pressure edge from undergoing new thermally induced drift after leaving the roller electrode.

[0065] Step 3: Through the coaxial coordination of the cryogenic medium jet and the alternating magnetic field, the vapor isolation film on the surface of the deconstructed zone is continuously broken, and the superequilibrium vacancy layer retained in Step 2 is frozen to the pressure edge surface within an extremely short heat exchange window.

[0066] Although step two has completely delivered the superequilibrium vacancy layer to the cryogenic medium control zone, the superequilibrium vacancy layer is still in a high-temperature recoverable state. If conventional liquid nitrogen injection is used directly, a vapor isolation film will immediately form on the high-temperature steel surface. The vapor isolation film reduces the actual contact area between the cryogenic medium and the metal, and also converts the jet momentum into surface slip. As a result, the surface of the deconstructed zone appears to be covered by white mist, but the actual heat exchange is locked outside the vapor isolation film.

[0067] This problem is even more pronounced for bimetallic composite paper cutters because the back of the blade remains rigid at low temperatures, and there is a significant temperature difference between the surface and the interior of the pressure edge. If cooling is slowed down by the vapor isolation film, the superequilibrium vacancy layer will be annihilated first on the high-temperature surface, and the subsequent step four will lose the freezing vacancy sites available for carbon atom segregation. Based on this, instead of simply increasing the flow rate of the cryogenic medium, a continuous chain of jet coverage - internal vibration - surface film rupture - in-situ freezing is established, transforming the heat transfer problem into an feasible process driven by both structure and time.

[0068] First, within the cryogenic medium inlet area determined in step two, the machine tool coaxially positions the jet nozzle and the induction coil, causing the cryogenic medium coverage area and the alternating magnetic field coverage area to spatially overlap. Second, the controller applies an alternating magnetic field frequency to the induction coil simultaneously with the jet's activation. and magnetic induction intensity This causes periodic magnetostrictive vibrations to occur on the surface of the pressure layer. Furthermore, these vibrations are transmitted to the surface through the deconstructed region, continuously disturbing the newly formed vapor barrier film, allowing the cryogenic medium to repeatedly contact the exposed metal and establish a high cooling rate.

[0069] A ring-shaped induction coil is fitted around the outer periphery of the jet nozzle on the machine tool. The central axis of the induction coil coincides with the axis of the nozzle, and both are fixed together to the rear section of the spindle slide in step two. The nozzle outlet preferably faces the center of the surface deconstruction zone of the pressure rim. A fixed spray distance is maintained between the nozzle and the pressure rim surface. The ring-shaped induction coil is located behind the nozzle outlet, ensuring that the center of the magnetic field first covers the pressure rim volume near the spray landing point, and then moves synchronously with the spindle slide. With this arrangement, the cryogenic medium does not first impact the pressure rim separately and then wait for the magnetic field to intervene, but instead enters the same surface deconstruction zone at the same time.

[0070] In a preferred embodiment, the operator can directly observe that as the spindle slide moves along the pressure edge, the white cryogenic medium jet ejected from the nozzle falls along the narrow band of the pressure edge, and the annular induction coil always surrounds the outer periphery of the nozzle, without oscillating independently from the spray center. If there are slight undulations in the blade edge, the slide as a whole follows, while the nozzle landing point and the magnetic field center still move along the same surface deconstruction zone. The most obvious result on-site is that a continuous narrow cooling band is formed on the pressure edge surface, rather than a wide, diffused atomization band, indicating that the surface deconstruction zone output in step two is completely controlled.

[0071] The physical spacing given in step two and transfer lag time While ensuring the timely delivery of the superbalanced vacancy layer is crucial, the actual freezing depends on the precise overlap between the cryogenic medium coverage area and the alternating magnetic field coverage area. By designing the jet nozzle and the annular induction coil as a coaxial configuration, step three transforms the overlap relationship from a manually adjusted property into an inherent attribute of the mechanism, thus providing a clear spatial boundary for the subsequent membrane rupture action. Besides the annular induction coil, saddle-shaped coils distributed on both sides of the nozzle can also be used, as long as their main magnetic field coverage area still surrounds the jet landing point, maintaining the same technical principle.

[0072] It should be noted that the initial cooling at the beginning of step three does not rely entirely on magnetostrictive film breaking. Instead, the initial cooling is achieved by the incident momentum of the cryogenic medium jet itself and the temperature difference between the pressure edge surface and the cryogenic medium. As the temperature of the surface deconstruction zone continues to decrease and enters the effective magnetic response zone of the steel grade, the periodic excitation of the surface deconstruction zone by the alternating magnetic field gradually shifts to the dominant film breaking stage.

[0073] Therefore, the film-breaking mechanism in step three is not static across the entire temperature range, but rather transitions from the initial cooling of the jet to continuous film breaking through internal vibration along the cooling trajectory, thereby enabling the cryogenic medium to continuously contact the exposed metal surface.

[0074] When the cryogenic medium valve group is opened, the controller synchronously outputs an alternating magnetic field frequency to the ring induction coil. and magnetic induction intensity The pressing material is in a high-carbon, high-alloy state, exhibiting a significant magnetostrictive response to alternating magnetic fields. This results in the formation of a mechanoelastic longitudinal wave propagating reciprocally along the thickness direction within the surface deconstructed region. This longitudinal wave does not depend on external mechanical impact but is directly generated by the periodic expansion and contraction within the material, with its propagation direction pointing from the interior of the surface deconstructed region towards the metal surface.

[0075] When the vapor barrier membrane is newly formed, its thickness is still thin and its adhesion is unstable. When the internal mechanical elastic longitudinal waves reach the surface, they introduce rapid normal disturbances at the metal-vapor interface, causing localized ruptures in the vapor barrier membrane. This allows the cryogenic medium to re-engage with the exposed metal. Specifically: First, let's represent the magnetostrictive strain: The surface normal vibration velocity is then represented as follows: Magnetostrictive strain Magnetostriction coefficient: Represents the dynamic expansion and contraction of the indentation surface under the current magnetic field and temperature, used to characterize the intensity of internal vibrations. : Indicates the magnetic induction intensity of the same grade of liner material. and temperature The stretching response function under combined action is preferably obtained through temperature-segmented magnetostriction calibration of samples of the same steel grade. Magnetic induction intensity Generated by the outer coil of the nozzle, it is obtained by measuring the distance near the nozzle landing point using a Hall probe during the installation and commissioning phase, and indirectly converted from the coil current during operation. Alternating magnetic field frequency. Output from the inverter power supply and set by the controller.

[0076] Effective vibration path This represents the equivalent length of the normal vibration propagation component actually participating in the surface deconstruction zone. The preferred method for obtaining this length is a sample excitation test or finite element method calibration. Surface normal vibration velocity. This indicates the velocity amplitude of the internal vibration after it reaches the surface, used to determine whether continuous film breaking capability is available. When the surface normal vibration velocity... Reaching the preset membrane rupture speed threshold At that time, it is determined that the steam isolation membrane has entered a state where it can be continuously ruptured.

[0077] In one exemplary embodiment, when the alternating magnetic field is not yet activated, the operator will see the surface of the spray area quickly enveloped by a uniform white mist. Once the alternating magnetic field is activated, the white mist layer will continuously break and contract along the direction of the pressure rim, and a narrow, bright metallic band will intermittently appear behind the nozzle, indicating that the vapor barrier film is being continuously broken. Here, the vapor barrier film is not removed by external mechanical brushes, but rather by the internal vibration of the pressure rim material itself, thus avoiding the introduction of additional components that directly rub against the pressure rim surface. As a parallel extension, if the pressure rim material system has a weak magnetostrictive response, the equivalent film-breaking driving force can be maintained by adjusting the number of turns of the annular induction coil, the core material, or the spray landing point. However, this does not change the principle of internal vibration breaking the external membrane layer.

[0078] Once completed, the vapor barrier is no longer a stable barrier that exists long after its initial formation, but rather a short-cycle state of formation-rupture-regeneration-re-rupture. It is precisely because the vapor barrier is constantly in an unstable state that the cryogenic medium can repeatedly contact the surface deconstructed region.

[0079] With the vapor barrier membrane continuously broken, the contact process of the cryogenic medium is further transformed into a freezing process of the superequilibrium vacancy layer. Once the vapor barrier membrane breaks, the cryogenic medium directly washes over the exposed metal, and the heat in the surface deconstruction zone is no longer mainly dissipated by the vapor outside the membrane, but rapidly enters the cryogenic medium flow.

[0080] At this point, the temperature in the surface deconstruction zone drops sharply along the thickness direction. The superequilibrium vacancy layer retained in step two does not have time to migrate back to the grain boundaries and dislocation entanglement regions, and is therefore locked in the low-temperature structure. To reconcile this frozen state with the vacancy survival factor from step two... Connecting these components, the controller further calculates the freeze vacancy retention factor. : Where: Freeze-off vacancy retention factor The relative proportion of frozen vacancies remaining in the surface deconstruction region after cooling to the initial superequilibrium vacancy layer in step one is used to characterize the level of available vacancy sites output from step three to step four; vacancy survival factor. Following the definition in step two, represents the degree of retention of the superequilibrium vacancy layer when it enters the cryogenic medium control zone, and is used as the pre-freezing state input in this formula; freezing duration The duration from the initial stable contact of the cryogenic medium with the exposed metal to the transition from the surface deconstruction zone to the freezing zone is determined by the injection intensity, the frequency of vapor barrier rupture, and the scanning speed. This is jointly determined to identify the time window for effective freezing; the freeze decay rate. : in temperature trajectory Under the influence of the action, the equivalent rate at which the remaining mobile vacancies continue to recover is used to characterize the intensity of vacancy loss in the final stage before freezing; surface temperature trajectory : A function of surface temperature change in the deconstructed zone during cooling, used to incorporate thermal history information into the frozen vacancy retention factor. The pursuit; In a preferred embodiment, the nozzle employs liquid nitrogen jets. After the valve assembly is opened, the white mist area on the pressure edge surface intermittently rolls under the coverage of an alternating magnetic field, followed by a rapid extension of the cooling zone. The subsequent temperature acquisition unit shows that the surface temperature after the jet impact point no longer slowly decreases but instead enters a steep drop phase. At this point, the machine tool no longer changes its physical spacing. and scanning speed Instead, it maintains the rhythm established in step two, ensuring that each surface deconstruction zone experiences the same freezing duration. The direct result visible on-site is that a continuous and clearly defined deep cold zone has formed on the surface of the pressure zone, without large areas of warming and darkening, indicating that the superequilibrium vacancy layer has been sealed in a zone.

[0081] During use, after the vapor isolation membrane is continuously broken, the cryogenic medium no longer remains on the outside of the membrane and slides, thus enabling the surface deconstruction zone to obtain real high-intensity heat transfer; the superequilibrium vacancy layer delivered in step two, during the freezing period The tissue is pressed into a low-temperature environment to prevent excessive re-migration before proceeding to step four.

[0082] Step 4: Based on the acoustic pattern of the edge lattice, the alternating magnetic field is phase-locked, so that the frozen vacancy sites sealed in Step 3 are preferentially occupied by supersaturated carbon atoms during the tempering stage, and the surface deconstruction region is reconstructed into a finely distributed precipitate structure.

[0083] After step three, although the surface of the edge has acquired frozen vacancy sites, freezing is not equivalent to final stabilization. For high-performance tool steel edge trimmings, what truly determines the uniformity of the microstructure is not the presence of vacancy sites, but whether carbon atoms arrive at these sites at the appropriate time and along the appropriate path. Traditional practices usually treat the tempering after deep cryogenic treatment as an independent heat treatment stage, only providing the furnace temperature, holding time, and cooling cycle, without considering whether the phase transformation inside the edge trimmings has been initiated or to what extent.

[0084] The result is that, even though the front and back sections, edges and middle sections, and surface and subsurface layers of the same long paper cutter undergo the same tempering regime, they do not necessarily experience the same precipitation rhythm. Therefore, instead of using a fixed time-history drive, the acoustic emission signal emitted by the pressure edge during the phase transition is used as the primary criterion. The acoustic signature first characterizes the current tissue state, and then the phase-locked loop (PLL) drive unit organizes the magnetic field output according to this state, so that carbon atom segregation, site occupation, and secondary carbide nucleation occur on the same controlled chain.

[0085] First, the acoustic emission sensor array is positioned between the cold end of the blade and the clamping base, avoiding the direct nozzle impact zone and external mechanical collision zone, and only acquiring the lattice response transmitted through the blade. Second, the acquired raw acoustic emission waveform is pre-amplified, bandpass filtered, short-time framing, and frequency domain analysis, and then decomposed into characteristic acoustic patterns corresponding to martensitic shear, carbon atom desolvation, and segregation nucleation. Third, the phase-locked loop (PLL) drive unit generates an alternating magnetic field frequency based on the current main characteristic acoustic pattern. Magnetic induction intensity and duration of action The adjustment amount ensures that the frozen vacant sites saved in step three are preferentially activated and occupied during the tempering process.

[0086] The characteristic acoustic signature used here to characterize martensitic shear and carbon atom desolvation is an indirect characterization quantity, rather than a direct monitoring of the movement of individual carbon atoms. The controller simultaneously calculates the target frequency band energy percentage from the purified acoustic emission signal within a fixed analysis window. Unit window sudden count Spectral centroid and the rate of change of tempering temperature The above indicators are compared with the pre-established stage template; only when the above indicators meet the current stage template will the state machine switch to the corresponding drive segment and allow the phase-locked drive unit to output an alternating magnetic field that matches the current main characteristic voiceprint.

[0087] In this multi-field coupled CNC follow-up machine tool, before entering the tempering section, a stable contact is maintained between the back of the tool body and the clamping base, and an acoustic emission sensor array is set on the cold end of the tool body. The acoustic emission sensor array preferably consists of two broadband piezoelectric sensors and one reference sensor. The two broadband piezoelectric sensors are clamped on the front and rear sides of the cold end of the tool body, and the reference sensor is fixed to the clamping base. This arrangement is not to increase the number of sensors, but to simultaneously obtain the tissue acoustic signature transmitted from inside the tool body and the environmental interference acoustic signature transmitted from the base, and then perform homogeneity discrimination in the acquisition unit. Since step four occurs in the tempering stage after deep cooling, external jet noise has already fallen out of its dominant position. At this time, the most likely sources to be mixed in are the micro-slippage of the clamp, furnace door movement, and electromagnetic coupling sound from the coil. Therefore, the acoustic emission acquisition unit first samples the three signals synchronously, and then, based on the arrival time difference and waveform correlation, removes the interference components that are synchronously enhanced with the base, retaining only the lattice acoustic signature transmitted from the pressure edge along the tool body.

[0088] In a preferred embodiment, the operator places the cryogenically cooled blade into the tempering section while maintaining its original clamping position, and three waveforms scroll simultaneously on the screen. When the furnace door closes, the base reference sensor first displays a wide pulse, followed by low-amplitude and differently shaped responses from the broadband piezoelectric sensors on both sides of the blade's cold end. The controller identifies these signals as environmental disturbances and rejects them. Once continuous, fine acoustic signatures begin to be released from within the pressure edge, a stable correspondence emerges between the waveforms on both sides of the cold end, and the base reference channel no longer amplifies synchronously. The operator can see the feature channel illuminated, indicating that subsequent judgments use the pressure edge's own lattice acoustic signature.

[0089] In this step, the basis for judgment in step four is changed from the external equipment status to the internal tissue status of the pressure edge. As a result, the characteristic acoustic patterns extracted subsequently are no longer dominated by the opening and closing of the furnace door, slight friction of the clamps, or electromagnetic crosstalk of the coils, but can truly reflect the tissue evolution near the frozen vacancy sites.

[0090] As a parallel extension, if the equipment space is limited, the two broadband piezoelectric sensors can be replaced with a combination of one broadband piezoelectric sensor and one fiber optic acoustic emission sensor. As long as the same source discrimination is still performed according to the cold end main channel and the base reference channel, the technical principle remains the same.

[0091] After completing the lattice acoustic signature cleanup, the acquisition unit divides the cleaned acoustic emission waveform into fixed frame lengths and sequentially performs bandpass filtering, envelope extraction, and fast Fourier transform on each frame. The bandpass filter preferably employs a Butterworth structure or a digital filter structure with equal amplitude-frequency flatness to suppress low-frequency vibrations and high-frequency electromagnetic glitches in the tempering furnace body. The fast Fourier transform maps each frame waveform to the frequency domain to distinguish between pulsed shear sound, continuous desolvation sound, and clustered nucleation sound. The controller then calculates the characteristic acoustic signature index. : Where: Characteristic Voiceprint Index The ratio of lattice acoustic ripple energy within the target frequency band to background frequency band energy is used to characterize whether the current acoustic emission has entered a definite phase transition stage; power spectral density. The purified acoustic emission waveform at angular frequency The frequency domain energy distribution at a given location is used to account for the differences in frequency domain between different phase transition events; target frequency band. The angular frequency range corresponding to the current tissue event to be identified is used to extract the main acoustic region of martensitic shear, carbon atom desolvation, or segregation nucleation; the preferred acquisition method is to calibrate with the same steel grade sample to establish three sets of template frequency bands: shear-desolvation-nucleation; background frequency band. : The reference angular frequency range after avoiding the main speaker area is used to provide a background noise reference within the same frame waveform; angular frequency Frequency domain analysis variables, used to describe the frequency components in the power spectral density. The position in the middle; The controller does not rely solely on a single characteristic voiceprint index. Instead of switching states when the threshold is exceeded, the state machine makes a determination based on the persistence of adjacent frames, peak density, and main frequency drift direction: when pulsed high-energy peaks appear first and fall back quickly, it is judged as the martensitic shear stage; when the continuous band spectrum is enhanced and the main frequency shifts to the mid-to-high frequency, it is judged as the carbon atom desolvation stage; when the discrete peaks re-concentrate and a stable repeating beat appears, it is judged as the segregation nucleation stage.

[0092] In one exemplary embodiment, the operator can see short, sharp peaks appearing on the screen at the beginning of the tempering process. The waveform then transitions to a more continuous banded pattern, finally converging into clusters of pulses with relatively stable intervals. The controller does not display abstract tissue names to the operator; instead, it directly switches between three worksheets on the interface: shear, desolvation, and nucleation, while simultaneously recording the main frequency range corresponding to the current worksheet. At this point, the subsequent phase-locked loop (PLL) drive unit uses the main frequency range corresponding to the current worksheet as input, instead of using a fixed frequency output.

[0093] This allows the previously invisible internal phase transition process to be decomposed into identifiable working stages, thus providing a clear driving basis for the next technical step. Because the state switching is driven by characteristic voiceprint indices... Its continuity determines that it will not be mistakenly triggered by a single noise pulse, nor will it confuse different tissue stages.

[0094] The phase-locked loop (PLL) drive unit consists of a phase discriminator, a second-order loop filter, and a digitally controlled oscillator; the phase discriminator uses the phase of the current main characteristic voiceprint component. Phase of the coil current sampling signal As input, the loop filter output control word updates the numerically controlled oscillator to correct the phase of the alternating magnetic field output in real time.

[0095] After the current tissue phase is determined, the phase-locked loop (PLL) drive unit receives the dominant frequency, phase start point, and duration window of the current main characteristic acoustic signature, thereby generating an alternating magnetic field drive waveform. This is not a simple replication of the acoustic emission frequency, but rather aligning the alternating magnetic field with the most active tissue event beat, causing the migration direction and arrival timing of carbon atoms near the frozen vacancy sites to be pulled in the same direction. Its phase-locking error is written as: Phase-locked error The deviation between the current main characteristic acoustic signature phase and the alternating magnetic field output phase is used to assess whether the magnetic field drive is synchronized with the current tissue beat; acoustic signature phase. The phase position of the current main characteristic acoustic signature within an analysis window, used to describe the time starting point of the lattice event; magnetic field phase. The phase position of the alternating magnetic field output by the phase-locked drive unit within the same analysis window is used to describe the starting point of the driving action applied to the pressure edge.

[0096] When phase-locked error After entering the preset tolerance band, the alternating magnetic field begins to be applied stably; when the phase-locked error... When the deviation continues, the drive unit first corrects the magnetic field phase, and then decides whether to maintain the current magnetic induction intensity. and duration of action Since step three has already sealed the frozen vacancy sites within the surface deconstruction region, the alternating magnetic field no longer undertakes the task of breaking the film or cooling, but only the task of pushing carbon atoms to the correct positions at the correct time. The tempering execution unit maintains the predetermined tempering temperature at this point, not aiming to drastically alter the thermal field, but rather allowing the magnetic field drive to superimpose with the acoustic signature, causing supersaturated carbon atoms to preferentially aggregate towards the frozen vacancy sites, where they complete the formation of fine precipitation nuclei.

[0097] In a preferred embodiment, the operator can observe the following continuous on-site actions: after the tempering furnace temperature stabilizes, the main frequency cursor of the main characteristic sound pattern on the interface is continuously refreshed, and the coil drive current waveform is slightly adjusted accordingly; when the segregation nucleation stage is established, the main frequency cursor tends to stabilize, and the coil drive current waveform also maintains a stable beat. Further on, the clustering pulses gradually weaken and fall back, and the controller determines that the segregation nucleation is nearing completion, thus gradually reducing the magnetic induction intensity. And ultimately, the alternating magnetic field output stops, instead of continuing to energize the coil. The direct, observable result on-site is that no localized overheating and darkening bands appear on the surface of the pressure edge at the end of tempering, indicating that the magnetic field output promptly ceases as the process ends. As a parallel extension, if the production line uses a segmented coil arrangement, each coil still shares the same main characteristic acoustic signature determination result, but their respective magnetic field phases differ. Fine-tuning is made based on the propagation delay of the segment in which it is located, while the terminology system and control principles remain unchanged.

[0098] During use, the alternating magnetic field output is controlled by the phase-locked error. The constraint is no longer blindly applied out of the current organizational rhythm, so the frozen vacant sites can be occupied by carbon atoms at the right time; after the segregation nucleation is completed, the magnetic field withdraws in time to avoid the accumulation of ineffective magnetothermal heat and continue to disturb the already formed fine precipitated tissue.

[0099] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0100] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0101] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0102] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0103] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A heat treatment method for homogenizing the microstructure of a high-performance tool steel edge for a paper cutter, the paper cutter comprising a low-carbon steel blade body and a high-performance tool steel edge composited on the edge of the blade body, characterized in that: include, The pressure edge is locally preheated to a subcritical state, and a high-frequency polarization pulse is applied along the extension direction of the strip carbide through the follower contact electrode to form a surface deconstruction region and super-equilibrium vacancies on the surface of the pressure edge, while maintaining the cold rigidity of the back of the tool body; the follower contact electrode is fixedly connected to the follower jet assembly and follows the movement, and the transfer lag time of the surface deconstruction region into the cryogenic medium is limited by the physical spacing and scanning speed. An alternating magnetic field is simultaneously applied in the cryogenic medium injection zone to break the surface vapor isolation film and freeze the superequilibrium vacancies. Acoustic emission signals are collected in the subsequent tempering cycle, and an alternating magnetic field is applied according to the characteristic acoustic pattern closed loop to control the segregation and precipitation of carbon atoms to the frozen vacancies.

2. The tissue homogenization heat treatment method according to claim 1, characterized in that: The paper cutter is rigidly clamped onto the clamping base, with the back of the cutter body against the back support seat equipped with a circulating cooling channel, and a continuous electrically insulating pad is placed between the back of the cutter body and the back support seat; the preheating module only establishes a follow-up heating zone for the local area of ​​the pressing edge.

3. The tissue homogenization heat treatment method according to claim 2, characterized in that: The follower contact electrode includes a front roller electrode and a rear roller electrode arranged in the front and rear along the scanning direction. Both the front roller electrode and the rear roller electrode are pressed against the edge side. The front roller electrode injects polarization pulse current, and the rear roller electrode recovers the polarization pulse current and closes the polarization pulse current near the edge surface.

4. The tissue homogenization heat treatment method according to claim 3, characterized in that: The output circuit of the polarization pulse current is connected in series with an impedance monitoring unit and a gate driver; the controller synchronously determines the sampling voltage and sampling current. When the circuit impedance changes from the surface closed state to an abnormal bypass state that shifts towards the back of the tool body or the bimetallic joint surface, the controller controls the gate driver to turn off the pulse output and switches to the induction heat preservation state.

5. The tissue homogenization heat treatment method according to claim 4, characterized in that: The follower contact electrode and the follower jet assembly are fixed on the same spindle slide and continuously follow along the length of the pressure edge. The follower jet assembly is located after the follower contact electrode. The controller limits the transfer lag time of the same point based on the physical distance between the roller electrode conduction center and the nozzle spray center and the spindle scanning speed.

6. The tissue homogenization heat treatment method according to claim 5, characterized in that: Before the main jet, the follow-up jet assembly performs a low-flow pre-blowing to displace ambient air and condensed water vapor from the pressure edge surface and maintain the jet center corresponding to the surface deconstruction zone. The controller combines the transfer lag time and the surface temperature trajectory of the pressure edge to determine the permission for the main jet, and only opens the main jet valve group when the surface deconstruction zone reaches the cryogenic medium access zone.

7. The tissue homogenization heat treatment method according to claim 6, characterized in that: A ring-shaped induction coil is fitted around the nozzle of the follow-up jet assembly. The central axis of the ring-shaped induction coil coincides with the nozzle axis and moves synchronously with the main shaft slide. At the same time as the main spray valve group is opened, an alternating magnetic field is applied to the ring-shaped induction coil so that the cryogenic medium coverage area and the alternating magnetic field coverage area fall together on the surface deconstruction area.

8. The tissue homogenization heat treatment method according to claim 7, characterized in that: The controller maintains the output of the alternating magnetic field based on the surface normal vibration velocity at the injection point. The surface normal vibration velocity is determined by the current alternating magnetic field frequency and the corresponding vibration amplitude. When the surface normal vibration velocity reaches the continuous film rupture threshold, the main injection valve group and the ring induction coil are kept working synchronously to keep the steam isolation membrane in a continuous rupture state.

9. The tissue homogenization heat treatment method according to claim 8, characterized in that: During the tempering cycle after cryogenic treatment, an acoustic emission sensor array is set at the cold end of the tool body, and a reference sensor is set at the clamping base. The controller performs homologous discrimination on the sampling signals of the acoustic emission sensor array and the reference sensor, and retains only the lattice acoustic pattern conducted along the tool body by self-pressure as the input for subsequent state determination.

10. The tissue homogenization heat treatment method according to claim 9, characterized in that: The controller sequentially performs bandpass filtering, short-time framing, frequency domain analysis, and stage determination on the lattice acoustic pattern to extract composite characteristic acoustic patterns representing martensitic shear, carbon atom desolvation, and segregation nucleation. It performs phase-locked drive on the alternating magnetic field based on the current main characteristic voiceprint, and stops the magnetic field output at the end of the tempering cycle.

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