A steel material cutting positioning system

Abstract

The present application relates to the technical field of dynamic positioning of steel material local heating cutting, and discloses a steel material cutting positioning system, which comprises a cutting energy source numerical control controller and a thermal signal sensing base station which moves integrally with a workpiece, wherein the actual thermal diffusivity of the workpiece is self-calibrated through double-point inquiry before cutting, and in the cutting, the thermal pulse emitted by the energy source is responded by the base station and the real position is solved through three-side measurement to generate a coordinate offset value to correct the subsequent path in real time, the present application directly establishes the measurement reference on the workpiece body, so that the physical drift and deformation of the workpiece caused by local heating are converted from a continuous cumulative positioning error source into a background condition which is real-time surveyed and internally eliminated in each position solving, thereby solving the problem of dynamic disconnection of the coordinate system.

Description

TECHNICAL FIELD

[0001] The present application relates to a steel material cutting positioning system, belonging to the technical field of dynamic positioning of local heating cutting of steel materials. BACKGROUND

[0002] In the laser or plasma cutting process of steel materials, the basic technical method is to perform one-time initial positioning on the workpiece before processing through visual means or the like, to assign the physical coordinate relationship of the workpiece to the digital coordinate system of the numerical control system, and the numerical control system thereafter executes the cutting path based on the initial coordinate relationship. This method is widely used in the field of mechanical processing, and the premise of its effectiveness is that the relative position between the processing object and the machine tool coordinate system remains stable.

[0003] However, in local heating cutting, the continuous action of high-energy beams inevitably generates uneven thermal stress fields inside the workpiece, which in turn causes real-time physical deformation and position drift of the workpiece. This physical process destroys the basis for the aforementioned processing method to be established, i.e., the real physical coordinate system of the workpiece has deviated from the digital coordinate system initially set by the numerical control system. The precise path executed by the numerical control system under closed digital logic is ultimately applied to a physically deformed workpiece, resulting in inevitable geometric errors.

[0004] To solve this problem, the prior art usually uses external visual monitoring or the like for compensation, but this type of method still observes a deformed workpiece based on the fixed reference frame of the machine tool, and the correction instruction has inherent delay compared to the occurrence of deformation. Specifically, the prior art mainly has the following principle constraints: 1. Separation of positioning reference: the measurement reference frame is established on the machine tool body, while the error source, i.e., thermal deformation, occurs in the workpiece body. The separation of the two makes the measurement result unable to truly reflect the real-time relative position of the cutting tool and the deformed region of the workpiece; 2. Lag of correction behavior: any external monitoring workflow is to deform first, then observe, and then compensate. This time sequence determines that the correction behavior cannot be synchronized with the error at the moment of cutting; 3. Accumulation of error information: due to the lack of a real-time reference bound to the workpiece body, the small displacement and angle generated by thermal deformation continuously accumulates throughout the cutting process, especially in large or complex path processing, ultimately leading to contour deviation. Therefore, how to establish a positioning method that can directly establish a measurement reference on the workpiece body and move synchronously with it, thereby eliminating the dynamic positioning error caused by the separation of the reference frame, has become a technical problem to be solved by the present application. SUMMARY

[0005] The present application provides a steel material cutting positioning system, which mainly aims to solve the problem that the existing positioning method cannot real-time eliminate the dynamic positioning error caused by thermal deformation due to the separation of the measurement reference and the workpiece.

[0006] To achieve the above object, the present application provides a steel material cutting positioning system, which comprises:

[0007] At least three thermal signal sensing base stations configured to be detachably arranged on the surface of the workpiece to be processed and move integrally with the workpiece;

[0008] A cutting energy source and a numerical control controller; the numerical control controller is wirelessly connected with the at least three thermal signal sensing base stations and connected with the cutting energy source, and the numerical control controller is configured to: before the cutting process starts, control the cutting energy source to emit calibration heat pulses at two calibration points with a known distance which is accurately controlled by the numerical control controller, and inversely solve the actual thermal diffusivity of the workpiece to be processed according to two time differences recorded by any thermal signal sensing base station During the cutting process, control the cutting energy source to emit a high-energy short heat pulse to form a heat wave source at a predetermined time and record the emission time Receive the thermal signals collected by the thermal signal sensing base stations and formed by the heat wave source through the thermal diffusion of the workpiece, and perform cross-correlation operation on the thermal signals and the theoretical waveform generated based on the actual thermal diffusivity To determine the arrival time of the thermal signals as the time when the operation result reaches the peak value Based on the emission time And each arrival time Calculate the time difference And according to the actual thermal diffusivity Convert each time difference Into the distance from the heat wave source to each thermal signal sensing base station Through trilateration on the distances Solve the real physical position of the heat wave source in the workpiece coordinate system with the at least three thermal signal sensing base stations as the reference Compare the real physical position With the instruction position of the numerical control controller To obtain the coordinate offset value And superimpose the coordinate offset value To the subsequent cutting path instruction in the subsequent control cycle for real-time correction.

[0009] Preferably, the numerical control controller is configured to perform an operation before the cutting process starts, which is specifically configured to: control the cutting energy source to emit a first calibration heat pulse at a first calibration point, and record a first time difference when a heat signal sensing base station receives the first calibration heat pulse; control the cutting energy source to move a preset accurate distance from the first calibration point to a second calibration point, and emit a second calibration heat pulse at the second calibration point, and record a second time difference when the same heat signal sensing base station receives the second calibration heat pulse; based on the preset accurate distance and the first time difference and the second time difference, establish an equation set and solve the actual thermal diffusivity .

[0010] Preferably, the heat signal sensing base station comprises: a magnetic base for adsorbing the workpiece, a thermistor fixedly connected to the magnetic base, and a wireless communication module electrically connected to the thermistor and used for sending a signal to the numerical control controller.

[0011] Preferably, the numerical control controller is configured to control the cutting energy source at a predetermined time, and the determination rule of the predetermined time is: triggering the emission of the high-energy short heat pulse according to a preset cutting path length interval, or at a geometric inflection point of the cutting path, or according to a preset time interval.

[0012] Preferably, the numerical control controller is configured to control the cutting energy source to emit a high-energy short heat pulse, and the duration of the high-energy short heat pulse is in the order of milliseconds, and the instantaneous power thereof is higher than the cutting power in the normal cutting process.

[0013] Preferably, the numerical control controller is configured to perform cross-correlation operation on the heat signal and a theoretical waveform, which is specifically configured to: before emitting the high-energy short heat pulse, according to the preset energy of the high-energy short heat pulse, the known thickness of the workpiece, the actual thermal diffusivity calculated, and the estimated distance between the cutting energy source and the target heat signal sensing base station, generate an ideal noise-free theoretical waveform at the target heat signal sensing base station on-line through a heat conduction point source model ; perform cross-correlation operation on the heat signal actually received by the target heat signal sensing base station and the theoretical waveform . , wherein is a cross-correlation function, is a time delay; when the cross-correlation function reaches a peak value, the time delay at this time is determined as the arrival time of the heat signal.

[0014] Preferably, at least one thermal signal sensing base station is pre-arranged on the cutting path, and the numerical control controller is further configured to: continuously monitor the temperature change rate of the pre-arranged thermal signal sensing base station during the movement of the cutting energy source along the cutting path to the pre-arranged thermal signal sensing base station; compare the monitored temperature change rate with a reference change rate which is learned through the initial cutting stage or pre-set according to the material properties; and pre-adjust one or more cutting process parameters of the cutting energy source before the cutting energy source reaches the pre-arranged thermal signal sensing base station when the deviation of the monitored temperature change rate from the reference change rate meets a pre-set condition.

[0015] Preferably, the numerical control controller is further configured to: record the time difference data of all three thermal signal sensing base stations synchronously when the calibration thermal pulse is emitted at the first calibration point and the second calibration point; independently calculate three actual thermal diffusivity values based on the data from different thermal signal sensing base stations; Preferably, the numerical control controller is further configured to: record the time difference data of all three thermal signal sensing base stations synchronously when the calibration thermal pulse is emitted at the first calibration point and the second calibration point; independently calculate three actual thermal diffusivity values based on the data from different thermal signal sensing base stations; Preferably, the numerical control controller is further configured to: record the time difference data of all three thermal signal sensing base stations synchronously when the calibration thermal pulse is emitted at the first calibration point and the second calibration point; independently calculate three actual thermal diffusivity values based on the data from different thermal signal sensing base stations; Preferably, the numerical control controller is further configured to: record the time difference data of all three thermal signal sensing base stations synchronously when the calibration thermal pulse is emitted at the first calibration point and the second calibration point; independently calculate three actual thermal diffusivity values based on the data from different thermal signal sensing base stations.

[0016] Preferably, the numerical control controller is configured to superimpose the coordinate bias value onto the subsequent cutting path instructions, and is specifically configured to: establish a temporary bias coordinate system in the numerical control controller, the translation and rotation amounts of the bias coordinate system being defined by the coordinate bias value , and all subsequent cutting path instructions are calculated and output in the temporary bias coordinate system before the coordinate bias value is updated by the next high-energy short thermal pulse.

[0017] Preferably, the numerical control controller is configured to convert the time difference into a distance , and the conversion follows the formula based on the thermal diffusion physical model: , wherein is a system correction coefficient calibrated together with the actual thermal diffusivity through the operation before the start of the cutting process.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] 1. The method, during cutting, controls the cutting energy source to emit a high-energy short thermal pulse at a specific moment, the thermal pulse propagates on the workpiece to form a thermal signal, which is received by at least three thermal signal sensing stations arranged on the surface of the workpiece; in this way, the cutting energy source, the workpiece as a signal propagation medium, and the sensing stations attached to the workpiece, together form a dynamic measurement closed loop with the workpiece as the carrier, so that the position of the cutting energy source is calculated, and the reference frame is no longer the fixed coordinate system of the machine tool, but the sensing station coordinate system that moves synchronously with the thermal deformation of the workpiece, thus, the physical position drift and deformation of the workpiece caused by local heating are transformed from a continuous cumulative positioning error source into a background condition that is real-time determined and internally eliminated in each position calculation.

[0020] 2. On the basis of the measurement closed loop, the method also controls the cutting energy source to emit calibration thermal pulses at two calibration points with known accurate distances before cutting starts, and records the two time differences by the same sensing station; this process uses the accuracy of the CNC system position control of the machine tool as a known input to inversely calculate the actual parameters of the thermal propagation characteristics in this specific workpiece, which makes the physical constants relied on by all subsequent positioning calculations no longer depend on theoretical or empirical values provided by external databases, but directly derived from on-site measurement of the physical characteristics of the current processing object itself, thereby avoiding systematic positioning deviations caused by material batch differences or uneven composition.

[0021] 3. Further, the present application pre-arranges at least one thermal signal sensing station on the cutting path, and continuously monitors the temperature change rate of the station during the movement of the cutting energy source to it and compares it with the reference change rate; this turns a sensing station for discrete positioning into a feedforward information source for continuous process monitoring, which reflects not the geometric position of the cutting tool, but the stability of the heat conduction process when the cutting energy source interacts with the material in front of the path, when the stability deviates, the system can adjust the cutting process parameters in advance, which makes the working logic of the whole system not only has the ability of dynamic correction of position coordinates, but also has the ability to avoid the risk of unstable process in front. BRIEF DESCRIPTION OF DRAWINGS

[0022] Fig. 1 The logical flow chart of the present application in orbit self-calibration and dynamic closed loop correction;

[0023] Fig. 2 The verification comparison chart of the suppression effect of the cutting contour deviation of the system of the present application;

[0024] Fig. 3 The hardware composition and signal flow diagram of the closed loop positioning system of the present application. DETAILED DESCRIPTION

[0025] In order to make the technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described in detail below. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0026] The present application provides a steel material cutting positioning system, which mainly comprises a numerical control controller, a cutting energy source controlled by the numerical control controller, and at least three thermal signal sensing base stations arranged on the surface of a workpiece to be processed in a detachable manner. The system is configured to establish a measurement reference on the workpiece body to real-time determine and eliminate positioning errors caused by physical deformation due to local heating cutting in a measurement closed loop. The technical solution is realized by a working process comprising initial on-track self-calibration and dynamic positioning correction in cutting.

[0027] In a typical application scenario, for example, in a laser cutting operation of the profile of a large-size Q345B steel plate with a thickness of 20 mm, due to the local high-temperature effect of the cutting energy source, the workpiece will generate thermal stress and cause real-time physical drift and deformation, which causes dynamic disconnection between the numerical control system preset digital coordinate system and the real physical coordinate system of the workpiece. To deal with this situation, the present application scheme first performs an on-track self-calibration step to obtain the physical characteristic parameters of the current workpiece to be processed before the cutting process starts. Specifically, the numerical control controller first controls the cutting energy source to move to the first calibration point on the surface of the workpiece , at which a high-energy short thermal pulse with a duration of milliseconds and a transient power higher than the normal cutting power is instantaneously emitted, i.e., a first calibration thermal pulse. The thermal pulse propagates on the workpiece and is received by all three thermal signal sensing base stations. The numerical control controller synchronously records the emission time of the thermal pulse and the respective arrival times of all three base stations, thereby obtaining a set of time difference data . Subsequently, the numerical control controller drives the cutting energy source to move along the X-axis in a positive direction by a preset accurate distance L (for example, L = 100.00 mm) to the second calibration point , at which a second calibration thermal pulse with the same parameters is emitted, and the response time difference of all three base stations is recorded again . At this time, the system has data from three independent physical channels, and based on these data, three independent actual thermal diffusivity values are solved in parallel. Taking the data of base station A as an example, the physical model followed by the solving process is as follows: , wherein is the distance from the thermal wave source to the base station, The system corrects the coefficient, since the base station A relative to and geometric relationship with the known distance together constitute a constraint condition, the system can solve the equation set inverse calculation of the actual thermal diffusivity of the current workpiece and correction coefficient , similarly, the system uses the data of base station B and base station C to independently calculate and ; the specific procedure of on-orbit self-calibration, from a base station relative position calibration step, that is, after the three thermal signal sensing base stations are adsorbed on the workpiece surface, the numerical control controller drives the cutting energy source to move to a preset physical marker point on the magnetic base of each base station in turn, and records the corresponding machine tool coordinates of each point, and the system calculates the relative position relationship among the three base stations in the machine tool coordinate system, thereby establishing a sensing base station coordinate system with a determined geometric configuration on the workpiece; on this basis, the system performs double-point inquiry, when the cutting energy source emits thermal pulses at the first calibration point p1 and the second calibration point p2, since the relative position of the base station and the position of the calibration point are both known quantities, the geometric distance and from any base station to p1 and p2 are determined values, after the corresponding time difference and are measured, the system can establish an overdetermined equation set according to the physical model: (wherein is the lumped physical parameter to be solved), and fit the optimal solution of C through the least square method, which is the conduction coefficient used for subsequent positioning calculation, which has contained the actual physical characteristics of the current workpiece.

[0028] It should be noted that this step contains a confidence evaluation and consistency decision mechanism, the system compares the three independently calculated values for consistency, if the deviation of the three values is less than a preset tolerance threshold, for example, 5%, it indicates that the material properties in the calibration area are uniform, and the system takes the average value as the actual thermal diffusivity used in subsequent calculation , if the deviation of one value, for example , exceeds the tolerance threshold, the system determines that the calibration process data is not reliable, and triggers the material internal abnormal alarm, at the same time, the abnormal data from base station B is excluded, and the value of is recalculated using the remaining data; through the on-orbit self-calibration, the system makes the physical constants used in all subsequent positioning calculations directly derived from the on-site measurement of the physical characteristics of the current machining object, thereby avoiding the positioning deviation caused by material batch difference or uneven composition. After completing the above on-orbit self-calibration and obtaining the reliable actual thermal diffusivity Afterward, the system begins the cutting operation. During the cutting process, due to continuous heat injection, the physical position and deformation state of the workpiece are constantly changing. This causes any one-time initial positioning to gradually become ineffective as processing progresses. To solve this problem, the system is configured to periodically perform a dynamic position query according to preset triggering rules, such as at the geometric inflection points of the cutting path. Specifically, at a predetermined time... The CNC controller controls the cutting energy source to emit a high-energy short thermal pulse to form a heat wave source. At least three thermal signal sensing base stations are arranged on the workpiece surface. Each of these base stations consists of a thermistor fixed to a magnetic base for adsorption onto the workpiece and a wireless communication module electrically connected to the thermistor. These modules are responsible for receiving the thermal signal diffused from the workpiece body. A key point is that in long-distance or thick plate cutting applications, the thermal signal will diffuse during propagation, leading to a decrease in the signal-to-noise ratio. To address this, the system employs a matched filtering method based on a physical model. Before emitting the thermal pulse, the CNC controller determines the pulse's preset energy, the known thickness of the workpiece, and the calculated actual thermal diffusivity. In addition, the estimated distance between the energy source and the target thermal signal sensing base station is calculated, and a noise-free theoretical waveform at the base station is generated online using a heat conduction point source model. When the base station actually receives a thermal signal containing noise Then, the system compares it with the theoretical waveform. Perform cross-correlation calculation: and the cross-correlation function Time delay at peak value The corresponding time is determined as the arrival time of the heat signal. Thus, the CNC controller obtains the emission time of the thermal pulse. Arrival time of each base station Based on this, the time difference of each channel is calculated. Subsequently, based on the actual thermal diffusivity calibrated during the on-orbit self-calibration process... With system correction coefficient Through the formula: Time differences Converted to the physical distance from the heat wave source to each heat signal sensing base station The system then obtained the distances from the heat wave source to the three base stations with known spatial locations. The physical position of the heat wave source relative to the workpiece coordinate system with reference to the three sensor base stations is obtained by performing geometric calculations using a trilateration algorithm. Because the sensor base station moves as an integral part of the workpiece, this location The calculation datum moves synchronously with the workpiece, thus eliminating the influence of the overall position drift of the workpiece on the measurement results; after calculating the physical position... The system then correlates it with the command position of the CNC controller at that moment. By comparing, a coordinate offset value can be obtained. The coordinate offset value The translation and rotation errors between the digital coordinate system and the physical coordinate system at this moment are quantified. In subsequent control cycles, the CNC controller will use this coordinate offset value. The correction is then applied to subsequent cutting path commands. Specifically, this involves establishing a system within the CNC controller based on this coordinate offset value. Before the next high-energy short thermal pulse updates the offset value, all subsequent cutting path commands are calculated and output to the servo system under the defined temporary offset coordinate system. Thus, the system forms a dynamic measurement and correction closed loop with the workpiece as the carrier.

[0029] The system also integrates a process early warning mechanism based on feedforward thermal signal gradients. This mechanism aims to address process instability issues such as incomplete cutting or overheating that may occur due to unknown inclusions or abrupt thickness changes within the material. It is implemented by pre-positioning at least one thermal signal sensing base station along the future cutting path. As the cutting energy source moves along the cutting path towards the pre-positioned base station, the CNC controller continuously monitors the temperature change rate dT / dt of that base station. It should be noted that in a stable cutting process of a homogeneous material, this temperature change rate will present a smooth and predictable baseline curve, which the system can learn from during the initial cutting phase. Alternatively, the baseline rate of change can be preset based on the material properties. When the deviation between the real-time temperature change rate monitored by the system and the baseline rate of change meets a preset condition, such as the deviation of multiple consecutive sampling points exceeding 15%, the system determines that the cutting energy source is about to enter a process instability region. Based on this, one or more cutting process parameters are pre-adjusted before the cutting energy source reaches the region, such as smoothly reducing the cutting speed or increasing the cutting power. This transforms a sensor base station used for discrete positioning into a feedforward information source used for continuous process monitoring, enabling the entire system to have the ability to dynamically correct position coordinates while also having the ability to pre-avoid the risk of process instability ahead.

[0030] Example 1: This example illustrates the operation of a steel cutting positioning system in a specific industrial application. In this application, the workpiece to be processed is a heterogeneous high-strength steel plate measuring 15m × 3m × 40mm, used for large ship section construction. The cutting path consists of a combination of long straight lines and multiple small-radius arcs. Due to the large size of the steel plate and the potential for localized thermophysical inhomogeneities caused by the rolling process, nonlinear thermal deformation is the primary factor leading to dimensional deviations in the final profile when using a high-power laser for long-path cutting. Before the cutting task begins, the operator attaches three thermal signal sensor bases to the steel plate surface at three different locations away from the preset cutting path using magnetic bases. The system then enters an on-orbit self-calibration step, with the CNC controller controlling the cutting energy source at the first calibration point. and distance Second calibration point The system transmits calibration thermal pulses sequentially and simultaneously records the time difference data of all three thermal signal sensing base stations. Based on the data from different base station channels, the system independently calculates the three actual thermal diffusivity rates. The values ​​are respectively After comparing the consistency of the three independently calculated values, it was found that their deviations were within the preset 5% tolerance threshold. Based on this, the system determined that the material properties within the calibration area were uniform, and adopted the average of the three values ​​as the actual thermal diffusivity of the completed field calibration used in all subsequent positioning calculations in this task. .

[0031] After the cutting process starts, when the cutting energy source travels along the preset path to the entrance of the first long arc segment, i.e., a preset geometric inflection point, the system automatically performs a dynamic position query. The CNC controller controls the cutting energy source to emit a high-energy short thermal pulse. At this time, due to the heat accumulation from the first half of the long straight-line cutting, the workpiece has undergone physical deformation, bending to one side. The three thermal signal sensing base stations, along with the workpiece body, deviate from the initial coordinate system of the CNC system. They receive the thermal signals propagated through the deformed workpiece. The CNC controller, in a specific implementation based on theoretical waveforms... With the actual received signal Cross-correlation calculations are used to determine the arrival time of each thermal signal. Furthermore, the system utilizes the actual thermal diffusivity obtained from the on-orbit self-calibration step, which already includes compensation for the current workpiece properties. Through the formula: time difference Converted to physical distance from the heat source to each base station It should be noted that this step relies on the self-calibration steps providing the necessary information. The accuracy of the values, both in synergy, enables the result of the distance calculation to reflect the propagation characteristics of the heat in the current specific workpiece, and the system compares the calculated distance The physical position of the heat wave source relative to the workpiece coordinate system with three base stations as a reference is obtained by trilateration The position The reference for the calculation is the sensor base station coordinate system that deforms with the workpiece, rather than the fixed coordinate system of the machine tool, so the physical position drift and deformation of the workpiece caused by heat are converted from a continuous cumulative positioning error source into a background condition that is real-time determined and internally eliminated in the current position calculation. The system compares the physical position with the instructed position of the numerical control controller to obtain a coordinate offset value and superimposes the offset value on the subsequent cutting path instructions for real-time correction. The cutting energy source completes the machining of the arc segment under the guidance of the corrected path, and as the entire cutting task progresses, the system repeatedly executes the above-mentioned dynamic position inquiry and real-time correction closed-loop process at multiple preset path geometric inflection points or according to preset cutting path length intervals. Each correction is a re-calibration of the deviation between the workpiece physical coordinate system and the numerical control system digital coordinate system at the current time. Ultimately, although the workpiece undergoes a complex, nonlinear thermal deformation process during the entire machining process, the contour size of the steel plate part ultimately produced is still within the tolerance range required by the drawing when detected by a three-coordinate measuring machine. This result shows that the system in this embodiment, by converting an open-loop positioning problem that relies on prior physical parameters into a closed-loop positioning problem with self-calibration capability based on the response of the workpiece itself, effectively overcomes the loss of machining precision caused by thermal deformation of large steel materials during local heating and cutting without relying on external observation equipment.

[0032] Example 2: To verify the effect of the technical solution of the present application in suppressing cutting contour deviation caused by thermal deformation, a set of comparative tests were designed and performed in this example. The purpose of the tests was to quantify the difference in geometric precision of the final product between the cutting process using the positioning system of the present application and the traditional cutting process without using the system. The test platform consisted of a standard numerical control system fiber laser cutting machine, a Q235 steel plate workpiece with dimensions of 2000mm x 1000mm x 10mm, and a set of laser trackers for independently measuring the coordinates of the cut profile. The position resolution of the laser tracker was 0.01mm and could be used to evaluate the cutting error.

[0033] The test sets up a test group applying the method of the present application and a control group applying the traditional method, both groups of tests use the same laser cutting process parameters, and cut the same preset path in different areas of the same steel plate, which contains long straight line segments and right angle corners, aiming to excite and accumulate thermal deformation, the operation of the control group is to perform one-time initial positioning by visual centering before cutting starts, and then perform the entire cutting path without any compensation, while the test group is arranged according to the method of the present application, three thermal signal sensing base stations are arranged on the surface of the workpiece, and an on-track self-calibration step is performed before cutting to obtain the actual thermal diffusion rate of the current workpiece During cutting, the trigger rule of dynamic position inquiry is set to be performed at an interval of cutting path length, the setting of interval distance is to balance the frequency of positioning correction and the influence on cutting efficiency, for the current medium thickness plate and medium complexity path, the trigger interval is set to 500mm, which can balance between suppressing error accumulation and maintaining cutting efficiency; During the test, the laser tracker is used to measure the actual contour position after cutting of the two groups of tests at 8 key detection points on the preset path, and the measurement value is compared with the instruction position of the numerical control system to calculate the final contour deviation, for the test group, the physical position calculated by the system after performing dynamic position inquiry before each detection point and the coordinate offset value are also recorded synchronously, the measurement data of each detection point and the key parameters recorded by the system are summarized in Table 1.

[0034]

[0035]

[0036] From the data in Table 1 (see Table 1), the contour deviation of the control group shows a cumulative effect as the cutting path lengthens, reaching a maximum of 0.75mm at detection point 5 farthest from the starting point, which reflects the open-loop control method's inability to cope with real-time thermal deformation of the workpiece, in contrast, the final contour deviation of the test group remains at a low level throughout the path, with a maximum deviation of no more than 0.09mm, the data shows that at detection points 2, 3, 4, etc., the X component of the coordinate offset value calculated by the system continues to increase, which is consistent with the physical process of thermal expansion and drift caused by long straight line cutting, and the system resets the error after each correction period by using this offset value for subsequent path correction, thereby blocking the continuous accumulation of errors, this test result verifies that the steel material cutting positioning system of the present application can suppress the influence of thermal deformation on cutting accuracy by using the technical path of on-track self-calibration and dynamic closed-loop correction under the condition of using general cutting equipment.

[0037] Example 3: This example combines Figs. 1 to 3 A description of a steel material cutting and positioning system, such as... Fig. 1 As shown, the process includes an initial self-calibration step performed before cutting, and a dynamic positioning correction closed loop that is repeatedly executed during cutting. The initial self-calibration step involves emitting calibration thermal pulses sequentially at two calibration points with known precise distances, and performing two-point interrogation based on the time difference and precise distance to calculate the actual thermal diffusivity of the current workpiece. This provides a field-calibrated physical reference for subsequent positioning calculations. During the cutting process, the system triggers positioning queries according to predetermined rules, such as path length, geometric inflection points, or time intervals. This involves emitting high-energy short thermal pulses to form a heat wave source on the workpiece surface. Each thermal signal sensing base station receives the raw thermal signal, which includes noise, propagating through the workpiece. A key module, namely, matched filtering based on a physical model, performs cross-correlation calculations between the received signal and the online-generated theoretical waveform to accurately determine the signal arrival time. Then, the system, based on the calibrated... The value converts the time difference into the physical distance from the heat source to each base station. The true physical position of the heat wave source in the coordinate system following the workpiece motion is calculated by trilateration. Then the actual location With the command position of the CNC system By comparison, the coordinate offset value of the quantization error is obtained. And ultimately this bias value The error is superimposed on subsequent cutting path instructions to eliminate accumulated errors. In addition, the process also integrates a process early warning mechanism based on feedforward thermal signal gradient. By continuously monitoring the temperature change rate of the base station on the path and comparing it with the benchmark, it predicts internal material anomalies, thereby avoiding process risks in advance and adjusting cutting process parameters in advance.

[0038] like Fig. 2 As shown, the horizontal axis represents several detection points set along the cutting path, and the vertical axis represents the contour deviation measured after cutting. The curve representing the control group using the traditional open-loop control method shows that its contour deviation accumulates continuously as the cutting path extends, reaching a peak at detection point 5. The curve representing the experimental group using the system of this invention shows that its final contour deviation is suppressed to an extremely low level throughout the entire processing. Meanwhile, the other coordinate offset value in the figure... The curve shows that its trend is highly consistent with the error accumulation trend of the control group. This indicates that the system of the present invention can accurately calculate the real-time physical deviation caused by thermal deformation in each correction cycle and eliminate it through a closed-loop correction mechanism, thereby effectively blocking the accumulation of errors and ensuring the final processing accuracy.

[0039] like Fig. 3 As shown, the controller integrates two software modules: a positioning and correction algorithm and a wireless communication service. It drives a cutting energy source, such as a laser head or a plasma torch, to apply cutting energy or emit thermal pulses to a workpiece, i.e., a steel plate, through control signals. At the same time, at least three thermal signal sensing base stations, A, B, and C, are arranged on the surface of the workpiece and interact with the CNC controller via wireless communication. When the cutting energy source forms a heat source on the workpiece, the heat is conducted through the workpiece body as a thermal signal and received by each sensing base station, thus forming a closed-loop measurement system with the workpiece as the information transmission medium.

[0040] Example 4: In a scenario involving the cutting of a special alloy steel plate with a thickness of 80mm, due to the attenuation and dispersion of the thermal pulse signal during long-distance propagation within the workpiece, the actual thermal signal received by the thermal signal sensing base station... The waveform exhibits a low signal-to-noise ratio and a flat rising edge, making it difficult to determine the signal arrival time by fixing a threshold or searching for peaks. The method failed; to address this situation, the system generates a theoretical waveform online before performing dynamic position query. The generation process is an algorithmic flow, whose inputs are a set of known physical and system parameters, including the preset energy E of the high-energy short thermal pulse, the known thickness h of the workpiece, and the actual thermal diffusivity of the current workpiece obtained through the on-orbit self-calibration step. And the estimated distance between the energy source and the target thermal signal sensing base station. The estimated distance is the result of the previous positioning cycle. Its heat conduction point source model is a simplified analytical solution of the three-dimensional heat conduction equation under the action of an instantaneous point heat source for the two-dimensional diffusion problem of the plate. Its form is: Where p is the material density and c is the specific heat capacity, both of which are known physical properties. The theoretical waveform used for matched filtering The effective coupling energy E parameter upon which its generation depends is determined through a standardized parameter calibration procedure performed before the start of the cutting task. The specific steps of this procedure are as follows: on a reference steel plate from the same batch as the workpiece to be processed, at a known distance from a thermal signal sensing base station... At the location, a calibrated thermal pulse is emitted with a set of power and pulse width parameters preset for the cutting task, and the actual peak temperature rise at the base station is recorded. Subsequently, the system will , Substitute other known physical parameters into the heat conduction point source model: , the system internally establishes a mapping function or lookup table from the "device instruction parameters" to the "effective coupling energy E", and in each dynamic position inquiry in the subsequent cutting process, the system can directly call the function or lookup table to obtain an accurate E value for generating the theoretical waveform corresponding to the current inquiry according to the instruction parameters used for the current thermal pulse emission; the numerical control controller calculates a series of theoretical temperature values starting from t = 0 based on the model and input parameters, forming a noise-free theoretical waveform with clear morphological characteristics curve.

[0041] After obtaining the theoretical waveform and the actual received thermal signal , the system performs a cross-correlation operation: to determine the arrival time, this embodiment also provides a calibration procedure for determining the tolerance threshold in the on-orbit self-calibration step, the specific steps of which are as follows: selecting a reference steel plate of the same batch as the workpiece to be processed and confirmed to have uniform physical properties, randomly selecting 10 different areas on the reference steel plate, and repeatedly performing the independent value parallel solving process based on double-point inquiry in the specific embodiment in each area to obtain 30 independent measurement values, calculating the standard deviation of the group of measurement values , and then setting the tolerance threshold as the percentage corresponding to , in a specific calibration, if the calculated group of average values is , and the standard deviation is , the tolerance threshold can be set to 3x(0.15 / 7.5)=6%, which is then fixed in the system and used for consistency decision-making during on-orbit self-calibration of all subsequent workpieces; in the dynamic position inquiry of the thick plate cutting scene, the actual received thermal signal is submerged in the background thermal noise, but the theoretically generated waveform provides a morphologically matched template, and the cross-correlation result of the two presents a peak curve, and the system determines the time corresponding to the peak as the arrival time of the thermal signal , and the subsequent trilateration and coordinate offset value calculation and correction process is consistent with the specific embodiment, the operation of this system shows that through a deterministic model generation process and parameter calibration procedure, the stability of the positioning calculation can be maintained under the condition of reduced signal quality.

[0042] Example 5: In a profile cutting task of a thick-walled high-pressure container forging with possible internal slag inclusion defects, the forging will be scrapped due to cutting failure, and the internal material abnormalities in front of the cutting path need to be avoided without damaging the workpiece. Before the cutting task officially starts, the system first performs a baseline learning and threshold calibration process. The operator plans a 300mm long straight learning path on the process allowance area of the workpiece to be processed or on a reference sample block of the same furnace number, and arranges a thermal signal sensing base station at the end of the learning path. Then the system controls the cutting energy source to cut along the learning path with the cutting process parameters preset for the cutting task. In this process, the numerical control controller continuously records and stores the temperature data of the thermal signal sensing base station at the end of the learning path at a sampling frequency of 10Hz, and calculates the temperature change rate dT / dt, thereby obtaining a temperature change rate curve corresponding to the current material and process parameters. The system stores this curve as the baseline change rate for comparison in the subsequent cutting process. At the same time, the system statistically analyzes the signal fluctuations of the baseline change rate curve and calculates the standard deviation of the signal noise . The preset condition for triggering the early warning is determined as a statistical threshold, that is, when the deviation between the real-time monitored temperature change rate and the stored baseline change rate at the corresponding position is greater than for 3 consecutive sampling points, the early warning is triggered.

[0043] In the subsequent official cutting process, another thermal signal sensing base station is arranged behind a circular segment on the main cutting path. When the cutting energy source moves towards the base station, the change trend of the real-time monitored temperature change rate dT / dt curve is consistent with the baseline change rate curve established previously. However, when it is about to enter the circular segment, the monitored dT / dt value appears a persistent decrease beyond the threshold . The system judges that there is a material defect area with abnormal heat conduction in front of the cutting head path, and immediately automatically reduces the cutting speed by 20% and increases the cutting power by 15% before the cutting energy source reaches the area. The cutting energy source with adjusted parameters passes through the area containing internal slag inclusion, avoiding possible cutting interruption due to mismatched process parameters. After the cutting head passes through the area, the system monitors that the dT / dt value returns to the range of the baseline change rate, and then restores the cutting parameters to the preset values. This process shows that through the pre-executed baseline learning and threshold calibration process, the system can perform feedforward identification of internal material defects and adaptive adjustment of process parameters in the official cutting.

[0044] Embodiment 6: This embodiment provides an engineering procedure for confidence evaluation and abnormal data processing of the output results of the on-track self-calibration step. In a working condition of cutting a titanium alloy plate with high internal cleanliness requirements in aerospace, even if the material is detected, there is still a risk of undetected point-like subsurface defects. If such defects are located on the heat propagation path of self-calibration, it will cause the actual thermal diffusivity calculated to be deviated, thereby affecting the accuracy of the entire subsequent cutting path.

[0045] To avoid this risk, the system has a set of confidence evaluation and consistency decision logic based on full-channel information redundancy checking when performing the on-track self-calibration step. When the system controls the cutting energy source to emit a calibration heat pulse at the first calibration point and the second calibration point , the numerical control controller not only synchronously records the time difference data of all three thermal signal sensing stations and , but also calculates three independent actual thermal diffusivities based on this. In addition, the system immediately starts a consistency decision algorithm, which first calculates the average value of the three values , then calculates the relative deviation of each independent value from the average value, and compares the deviation with a tolerance threshold determined by the above calibration procedure. In this titanium alloy plate cutting task, the system calculates: , , , and the average value of is . The system calculates the relative deviation of from the average value as 9.1%, and the relative deviations of and are both less than 5%. If the preset tolerance threshold is 6%, the system determines as an abnormal data point. At this time, the system triggers a preset abnormal processing procedure, which first sends an alarm to the operator that the material in the calibration area is abnormal, and highlights the suspected area composed of the calibration point and the base station B on the control interface. At the same time, the system automatically excludes the data of from this calculation, and only uses and with high data consistency to recalculate the average value, and uses the recalculated value as the actual thermal diffusivity for the subsequent cutting path correction. The execution of this procedure makes the on-track self-calibration step from a parameter measurement process to a closed-loop verification process with self-diagnosis and data purification capabilities.

[0046] It is apparent for a person skilled in the art that the application is not limited to the details of the above-described exemplary embodiments, but that the application can be implemented in other concrete forms without departing from the spirit or essential characteristics of the application.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application but not limit the present application, and although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced, without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A steel material cutting positioning system, characterized by, The system comprises: at least three thermal signal sensing base stations configured to be detachably arranged on the surface of the workpiece to be processed and move integrally with the workpiece; The cutting energy source and the numerical control controller; the numerical control controller is wirelessly connected with at least three thermal signal sensing base stations and connected with the cutting energy source, and the numerical control controller is configured to: before the cutting process starts, control the cutting energy source to emit calibration heat pulses at two calibration points with known distances which are accurately controlled by the numerical control controller, and inversely calculate the actual thermal diffusivity of the current workpiece to be processed according to two time differences recorded by any thermal signal sensing base station ; during the cutting process, control the cutting energy source to emit a high-energy short heat pulse at a predetermined time to form a heat wave source and record the emission time ; receive the thermal signals collected by each thermal signal sensing base station formed by the thermal diffusion of the workpiece through the heat wave source, and perform cross-correlation operation on the thermal signals and the theoretical waveform generated based on the actual thermal diffusivity to determine the time when the operation result reaches the peak value as the arrival time of the thermal signal ; based on the emission time and each arrival time , calculate the time difference , and according to the actual thermal diffusivity , convert each time difference into the distance from the heat wave source to each thermal signal sensing base station ; by performing trilateration on the distance , the real physical position of the heat wave source in the workpiece coordinate system with at least three thermal signal sensing base stations as the reference is calculated ; compare the real physical position with the instruction position of the numerical control controller to obtain the coordinate offset value , and superimpose the coordinate offset value on the subsequent cutting path instructions in the subsequent control cycle for real-time correction.

2. A steel material cutting positioning system according to claim 1, wherein The numerical control controller is configured to perform an operation before the cutting process starts, and is specifically configured to: control the cutting energy source to emit a first calibration heat pulse at a first calibration point, and record a first time difference at which a heat signal sensing base station receives the first calibration heat pulse; control the cutting energy source to move a preset accurate distance from the first calibration point to a second calibration point, and emit a second calibration heat pulse at the second calibration point, and record a second time difference at which the same heat signal sensing base station receives the second calibration heat pulse; based on the preset accurate distance and the first time difference and the second time difference, establish an equation set and solve the actual heat diffusion rate .

3. A steel material cutting positioning system according to claim 1, wherein the thermal signal sensing base station comprises a magnetic base for adsorption on the workpiece, a thermistor fixed to the magnetic base, and a wireless communication module electrically connected with the thermistor and used for sending signals to the numerical control controller.

4. A steel material cutting positioning system according to claim 1, wherein The numerical control controller is configured to control the cutting energy source at a predetermined time, and the determination rule of the predetermined time is to trigger the emission of the high-energy short thermal pulse according to a preset cutting path length interval, or at a geometric inflection point of the cutting path, or according to a preset time interval.

5. A steel material cutting positioning system according to claim 1, wherein The numerical control controller is configured to control the cutting energy source to emit the high-energy short thermal pulse, the duration of the high-energy short thermal pulse is in the order of milliseconds, and the instantaneous power thereof is higher than the cutting power in the normal cutting process.

6. A steel material cutting positioning system according to claim 1, wherein The numerical control controller is configured to cross-correlate the thermal signal with a theoretical waveform, which is specifically configured to: before emitting the high-energy short thermal pulse, according to the preset energy of the high-energy short thermal pulse, the known thickness of the workpiece, the calculated actual thermal diffusivity , and the estimated distance between the cutting energy source and the target thermal signal sensing base station, generate a noise-free theoretical waveform at the target thermal signal sensing base station online through a thermal conduction point source model ; cross-correlate the thermal signal actually received by the target thermal signal sensing base station with the theoretical waveform : , where is a cross-correlation function, is a time delay; and when the cross-correlation function reaches a peak value, the time delay is determined as the arrival time of the thermal signal.

7. A steel material cutting positioning system according to claim 1, wherein At least one thermal signal sensing base station is arranged in advance on the cutting path, and the numerical control controller is further configured to: continuously monitor the temperature change rate of the arranged thermal signal sensing base station during the movement of the cutting energy source along the cutting path to the arranged thermal signal sensing base station; compare the monitored temperature change rate with a reference change rate set in advance through an initial cutting stage learning or according to material properties; and when the deviation between the monitored temperature change rate and the reference change rate meets a preset condition, adjust one or more cutting process parameters of the cutting energy source in advance before the cutting energy source reaches the arranged thermal signal sensing base station.

8. A steel material cutting positioning system according to claim 2, wherein The numerical control controller is further configured to: record the time difference data of all three thermal signal sensing base stations synchronously when the calibration thermal pulse is emitted at the first calibration point and the second calibration point; Based on data from different thermal signal sensing base stations, three actual thermal diffusivities are independently calculated A consistency comparison is made on the three independently calculated actual thermal diffusivity values; if the deviation of one actual thermal diffusivity value from the other two actual thermal diffusivity values exceeds a preset tolerance threshold, the tolerance threshold being any value in the range of 5% to 15%, an internal material anomaly alarm is triggered, and the anomaly whose deviation exceeds the preset tolerance threshold is removed value, the mean value of the remaining values is calculated as the actual thermal diffusivity ; otherwise, the average value of the three actual thermal diffusivity values is taken as the actual thermal diffusivity used in subsequent calculations.

9. A steel material cutting positioning system according to claim 1, wherein The CNC controller is configured to superimpose a coordinate offset value to subsequent cutting path instructions, which is specifically configured to: establish a temporary offset coordinate system inside the CNC controller, the translation and rotation amount of the offset coordinate system is defined by the coordinate offset value , and update the coordinate offset value before the next high-energy short thermal pulse, all subsequent cutting path instructions are calculated and output under the temporary offset coordinate system.

10. A steel material cutting positioning system according to claim 1, wherein The numerical control is configured to convert the time difference into a distance The rule followed by the conversion is a formula based on the physical model of heat diffusion: where is the actual heat diffusion rate calibrated together with the system correction coefficient.

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