CN115014502B - Real-time amplitude automatic measurement system of ultrasonic knife - Google Patents
Real-time amplitude automatic measurement system of ultrasonic knife Download PDFInfo
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- CN115014502B CN115014502B CN202210932869.4A CN202210932869A CN115014502B CN 115014502 B CN115014502 B CN 115014502B CN 202210932869 A CN202210932869 A CN 202210932869A CN 115014502 B CN115014502 B CN 115014502B
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Abstract
The invention discloses an ultrasonic knife real-time amplitude automatic measurement system which comprises a distance measurement detection module, a vibration harmonic construction module, a driving fatigue analysis module and a driving compensation adjustment module; the driving fatigue analysis module analyzes the driving fatigue offset of the ultrasonic knife at the surface temperature of the piezoelectric driver; and the driving compensation adjusting module is used for compensating the driving fatigue offset according to the driving fatigue offset of the ultrasonic knife under the surface temperature of the piezoelectric driver. According to the invention, by measuring the amplitude of the ultrasonic knife, the motion track of the ultrasonic knife in the working process can be obtained in real time, the offset degree of the surface temperature of the piezoelectric driver to the workpiece processing of the ultrasonic knife is established, the offset degree of the ultrasonic knife processing is compensated according to the surface temperature, and the processing precision of the ultrasonic knife is improved.
Description
Technical Field
The invention belongs to the technical field of ultrasonic knife measurement, and relates to an automatic real-time amplitude measurement system for an ultrasonic knife.
Background
The principle of ultrasonic vibration machining is that the vibration with micron-sized ultrasonic frequency is applied to a cutter, and the vibration frequency, the vibration amplitude and the vibration direction of the cutter are controlled, so that a machining tool and a workpiece are periodically separated at high frequency, and the machinability of the material is greatly improved. The elliptical vibration cutting is based on the common cutting, and utilizes a vibration excitation source to make a cutter generate additional vibration along an elliptical track to form variable-speed cutting between the cutter and a workpiece.
In the prior art, in the processing process of the ultrasonic knife, the amplitude transformer is driven to vibrate by the piezoelectric driver so as to drive the ultrasonic knife positioned at the front end of the amplitude transformer to process, but as the working duration increases, the vibration amplitude of the piezoelectric driver is interfered by temperature and can shift, so that the ultrasonic knife shifts the processing process of a workpiece, and the processing precision of the surface of the workpiece is reduced; the motion trail of the ultrasonic knife cannot be drawn according to the real-time amplitude of the ultrasonic knife; the existing ultrasonic knife is only judged through manual experience, human factors exist, and the abrasion degree of the ultrasonic knife in the machining process cannot be accurately evaluated.
Disclosure of Invention
The invention aims to provide an automatic real-time amplitude measuring system for an ultrasonic knife, which solves the problems in the prior art.
The purpose of the invention can be realized by the following technical scheme:
an ultrasonic knife real-time amplitude automatic measurement system comprises a distance measurement detection module, a vibration harmonic wave construction module, a driving fatigue analysis module and a driving compensation adjustment module, wherein the distance measurement detection module comprises two laser distance measurement sensors which are mutually perpendicular to laser emission light sources and respectively detect the distance in the feeding direction and the cutting depth of an ultrasonic knife;
the vibration harmonic wave construction module respectively extracts the distances from the two laser ranging sensors to the surface of the ultrasonic knife, correlates the distances detected by the two laser ranging sensors, obtains the real-time position coordinate of the cutting edge of the ultrasonic knife according to the geometric relation, obtains the motion track of the ultrasonic knife in the working process, analyzes the motion track of the ultrasonic knife, and obtains the vibration harmonic wave equations of the ultrasonic knife on the x axis and the y axis;
the driving fatigue analysis module extracts the surface temperature of a piezoelectric driver for driving the amplitude transformer under the continuous accumulated working time T, obtains the amplitude of driving displacement of the piezoelectric driver under the interference of the surface temperature by analyzing the surface temperature of the piezoelectric driver, and analyzes the driving fatigue by combining the vibration parameters of the front ultrasonic knife and the rear ultrasonic knife on the x axis and the y axis to analyze the driving fatigue offset of the ultrasonic knife under the surface temperature of the piezoelectric driver in real time;
the driving compensation adjusting module is used for obtaining the driving fatigue offset of the ultrasonic knife under the surface temperature of the piezoelectric driver, respectively judging whether the driving fatigue offset of the ultrasonic knife in the feeding direction and the cutting direction is larger than a set driving fatigue offset threshold value, and if the driving fatigue offset in one direction is larger than the set driving fatigue offset threshold value, controlling the ultrasonic knife head to perform driving fatigue offset compensation along the direction by using the set driving fatigue offset threshold value.
Further, the laser ranging sensor a and the laser ranging sensor b are triggered simultaneously, and the measured data at the same time point are correlated.
Further, the real-time position coordinates (xi, yi) of the blade edge of the tracked ultrasonic knife are known by adopting a geometrical relation:
the point of the ultrasonic knife is diamondAnd the included angle of the point of the ultrasonic knife is
The values of the parameters, which are known,
when the blade of the ultrasonic knife is positioned at the origin of coordinates and is in a static state, the distance from the laser ranging sensor b to the surface of the ultrasonic knife,
when the ultrasonic knife is in a static state, the distance from the laser ranging sensor a to the surface of the ultrasonic knife,
the distance from the laser ranging sensor b to the surface of the ultrasonic knife at the ith sampling time,
the distance from the laser ranging sensor a to the surface of the ultrasonic knife at the ith sampling time;
the real-time position coordinates xi and yi of the cutting edge of the ultrasonic knife are obtained by the formula
。
Further, the method for constructing the vibration harmonic equation on the x axis and the y axis respectively in the working process of the ultrasonic scalpel specifically comprises the following steps:
step 1, respectively extracting intersection point positions of a motion track of the ultrasonic knife and an x axis and a y axis, wherein the coordinates of the intersection points of the motion track of the ultrasonic knife and the x axis are (x 1, 0) and (x 2, 0), and the coordinates of the intersection points of the motion track of the ultrasonic knife and the y axis are (0, y 1) and (0, y 2);
step 2, calculating the amplitude A of the harmonic wave of the ultrasonic knife in the feeding direction and the amplitude B of the harmonic wave of the ultrasonic knife in the cutting direction,
，
；
step 3, extracting position coordinates on the n-times motion track and bringing the position coordinates into a vibration harmonic equation
Respectively deducing the vibration initial phases of the rotating shaft on the x axis and the y axis at the sampling time point t, wherein the vibration initial phases are respectively
And
and is and
f is the sampling frequency sent by the laser ranging sensor, and the sampling frequency of the laser ranging sensor a is the same as that of the laser ranging sensor b;
step 4, substituting the amplitude of the vibration harmonic wave in the step 2 and the vibration initial phase in the step 3 to obtain a vibration harmonic wave formula of the ultrasonic scalpel on the x axis
And vibration harmonic formula in the y-axis
。
Furthermore, the vibration frequency f1 of the ultrasonic knife and the vibration frequency f2 of the two laser ranging sensors meet the conditions
And f2 is>>f1, m is the number of samples.
Further, the driving fatigue analysis module performs driving fatigue interference analysis according to the surface temperature of the piezoelectric driver, and adopts the following method, specifically comprising the following steps:
step 1, continuously supplying sine voltage with fixed frequency to a piezoelectric driver of the ultrasonic scalpel;
step 2, extracting the surface temperature of the piezoelectric driver for driving the amplitude transformer under the continuous accumulated working time T, and drawing a surface temperature curve;
step 3, establishing a surface temperature model of the piezoelectric driver along with the working time;
step 4, obtaining a driving displacement curve chart of the piezoelectric driver at each surface temperature, wherein the driving displacement curve chart at the same surface temperature is in a sine wave form due to the fact that the driving voltage of the piezoelectric driver is in a sine driving voltage;
step 5, extracting the amplitude values in the driving displacement curve chart at each surface temperature, establishing a mapping relation corresponding to the surface temperature of the piezoelectric driver and the amplitude value of the driving displacement, and enabling the driving displacement curve at different surface temperatures to drift;
step 6, extracting vibration parameters of the ultrasonic blade before and after the continuous accumulated working time t, analyzing the driving fatigue offset of the voltage driver to the ultrasonic blade by adopting a driving fatigue interference model, wherein the vibration frequency of the ultrasonic blade changes along with the change of the vibration frequency of the piezoelectric driver;
further, the surface temperature model of the piezoelectric actuator is
，
The surface temperature of the piezoelectric actuator under the continuous accumulated working time t,
the surface temperature at the initial operating state of the piezoelectric actuator,
the surface temperature is continuously accumulated for the piezo actuator for an operating time period T.
Further, the formula for calculating the driving fatigue offset of the piezoelectric driver to the ultrasonic knife is as follows:
The system further comprises a cutter abrasion pre-estimation module, wherein the cutter abrasion pre-estimation module is used for acquiring the processing time of the ultrasonic cutter on the surfaces of workpieces made of different materials and the feeding amount of the ultrasonic cutter, extracting the pre-established reverse abrasion coefficients of the different materials to the ultrasonic cutter, acquiring a cutter abrasion pre-estimation amount, judging whether the cutter abrasion pre-estimation amount reaches a set cutter abrasion threshold value, and if the cutter abrasion pre-estimation amount is larger than the set cutter abrasion threshold value, replacing the ultrasonic cutter.
The invention has the beneficial effects that:
according to the invention, the two mutually perpendicular laser ranging sensors are adopted to measure the amplitude of the ultrasonic knife, so that the motion trail of the ultrasonic knife in the working process can be obtained in real time, and the motion trail support is provided for the ultrasonic drive fatigue analysis in the later stage.
According to the invention, the surface temperature of the piezoelectric driver under the continuous accumulated working time is analyzed, the driving displacement amplitude of the piezoelectric driver under the surface temperature interference is analyzed, the driving fatigue test is carried out on the piezoelectric driver by combining the vibration amplitudes of the ultrasonic knife on the x axis and the y axis, the fatigue offset of the ultrasonic knife driving under the surface temperature interference of the piezoelectric driver can be analyzed, the offset degree of the surface temperature of the piezoelectric driver to process a workpiece on the ultrasonic knife is accurately established, the offset degree of the ultrasonic knife processing is compensated according to the surface temperature, the condition that the ultrasonic knife processing is offset due to the surface temperature interference of the piezoelectric driver is eliminated, and the processing precision of the ultrasonic knife is improved.
According to the invention, through the pre-estimation analysis of the abrasion of the ultrasonic knife tool, the abrasion degree of the ultrasonic knife can be accurately analyzed according to the processing time length, the processing speed and the feeding amount of the tool, once the abrasion degree of the ultrasonic knife is greater than a set value, the ultrasonic knife tool is replaced in time, the influence of the ultrasonic knife with large abrasion degree on the processing of a workpiece is avoided, the processing reject ratio is reduced, and the processing precision of the workpiece is greatly improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic view of the position coordinates of the cutting edge of an ultrasonic blade according to the present invention;
FIG. 2 is a schematic diagram of the motion trajectory of the ultrasonic blade of the present invention;
FIG. 3 is a schematic view of the fixed mounting of the ultrasonic blade cutter of the present invention;
FIG. 4 is a graph showing the driving displacement of the piezoelectric actuator at various surface temperatures according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The system measures the amplitude of the ultrasonic knife and adjusts the installation angle and the position of the two laser ranging sensors, so that the two laser ranging sensors are perpendicular to each other, the focus of one laser ranging sensor a is aligned with the cutting edge in the feeding direction of the ultrasonic knife, the focus of the other laser ranging sensor b is positioned right above the knife face in the cutting direction of the ultrasonic knife, and light sources emitted by the two laser ranging sensors are perpendicular to each other.
And constructing a coordinate origin for amplitude measurement of the ultrasonic knife, and establishing XY coordinates by taking the focal point of the extension line of the light source emitting points of the two mutually perpendicular laser ranging sensors as the coordinate origin of the ultrasonic knife in a static state, wherein the position coordinates of the laser ranging sensor a are (0, ly0) and the position coordinates of the laser ranging sensor b are (Lx 0, 0).
In this embodiment, the blade of the ultrasonic blade is used as the origin of coordinates, that is, the intersection point of the light sources emitted by the two laser ranging sensors is used as the origin of coordinates, the distance from the laser ranging sensor b located on the x axis to the origin of coordinates is Lx0, and the distance from the laser ranging sensor a located on the y axis to the origin of coordinates is Ly0.
An automatic real-time amplitude measuring system for an ultrasonic knife comprises a distance measuring detection module, a vibration harmonic wave construction module, a driving fatigue analysis module, a driving compensation adjustment module and a cutter abrasion prediction module.
The distance measurement detection module comprises two laser distance measurement sensors which are perpendicular to each other and used for detecting the distance between the feeding direction of the ultrasonic knife and the cutting depth respectively.
The vibration harmonic wave construction module respectively extracts the distances from the two laser ranging sensors to the surface of the ultrasonic knife, correlates the distances detected by the two laser ranging sensors, obtains a real-time position coordinate of the cutting edge of the ultrasonic knife according to a geometric relation, draws the position coordinate of the cutting edge of the ultrasonic knife on an xy axis to obtain a motion track of the ultrasonic knife in the working process, analyzes the motion track of the ultrasonic knife, and obtains vibration harmonic wave equations of the ultrasonic knife on the x axis and the y axis.
The laser ranging sensor a and the laser ranging sensor b are triggered simultaneously, and the distances detected by the two laser ranging sensors are correlated, so that the distances detected by the two laser ranging sensors are the distances from the laser ranging sensors to the surface of the ultrasonic knife, which are collected at the same sampling time point.
Wherein, acquire the real-time position coordinate of ultrasonic knife cutting edge under the ith sampling time point:
as shown in fig. 1, the real-time position coordinates (xi, yi) of the blade of the ultrasonic blade to be tracked can be known, and by adopting the geometrical relationship, the following can be known:
the point of the ultrasonic knife is rhombic, and the included angle of the point of the ultrasonic knife is
The parameters, for the known parameters,
the distance from the laser ranging sensor b to the surface of the ultrasonic knife when the cutting edge of the ultrasonic knife is positioned at the origin of coordinates and in a static state,
the distance from the laser ranging sensor a to the surface of the ultrasonic knife when the ultrasonic knife is in a static state,
in order to measure the distance from the sensor b to the surface of the ultrasonic knife at the ith sampling time,
the distance from the laser ranging sensor a to the surface of the ultrasonic knife at the ith sampling time;
as can be obtained by the above-mentioned formula,
。
the embodiment at least discloses a method for acquiring a coordinate origin of a blade of an ultrasonic scalpel, which respectively acquires reset coordinate points of laser ranging sensors on an x axis and a y axis (the reset coordinate points are default coordinate positions when the specified laser ranging sensors are restarted or power failure is restarted);
controlling the laser ranging sensor b to move along the cutting direction of the ultrasonic knife from the reset coordinate point, and recording the distance from the laser ranging sensor b to the ultrasonic knife;
extracting the moving distance of the laser ranging sensor b corresponding to the minimum value of the distance from the laser ranging sensor b to the ultrasonic knife, which is detected by the laser ranging sensor b, and recording the moving distance as L1, wherein when the laser ranging sensor b detected by the laser ranging sensor b is positioned at a reset coordinate point, the distance from the laser ranging sensor b to the ultrasonic knife is minimum, and the moving distance L1 is equal to 0;
controlling the laser ranging sensor a to move along the feeding direction of the ultrasonic knife from the reset coordinate point, and recording and measuring the distance from the laser ranging sensor a to the ultrasonic knife;
extracting the moving distance, which is recorded as L2, of the laser ranging sensor a corresponding to the maximum distance value between the laser ranging sensor a and the ultrasonic knife, which is detected by the laser ranging sensor a;
and respectively adjusting the laser ranging sensor b and the laser ranging sensor a according to the moving distances L1 and L2, so that the tool nose of the ultrasonic knife is positioned at the original coordinate point, and valuable references are provided for drawing the motion track of the ultrasonic knife and the vibration harmonic equation of the ultrasonic knife on the x axis and the y axis in the later stage.
The embodiment at least discloses a method for constructing vibration harmonic equations on an x axis and a y axis respectively in the working process of an ultrasonic knife, which comprises the following steps:
step 1, respectively extracting intersection point positions of the motion track of the ultrasonic knife and an x axis and a y axis, wherein the coordinates of the intersection points with the x axis are (x 1, 0) and (x 2, 0), and the coordinates of the intersection points with the y axis are (0, y 1) and (0, y 2), as shown in fig. 2;
step 2, calculating the amplitude A of the harmonic wave of the ultrasonic knife in the feeding direction and the amplitude B of the harmonic wave of the ultrasonic knife in the cutting direction,
，
；
step 3, extracting position coordinates on the n-times motion track and bringing the position coordinates into a vibration harmonic equation
Respectively deducing the vibration initial phases of the rotating shaft on the x axis and the y axis at the sampling time point t, wherein the vibration initial phases are respectively
And
and is and
f is the sampling frequency sent by the laser ranging sensor, and the sampling frequency of the laser ranging sensor a is the same as that of the laser ranging sensor b;
step 4, vibrating in the step 2The amplitude of the harmonic wave and the initial phase of the vibration in the step 3 are substituted, and a vibration harmonic wave formula of the ultrasonic knife on the x axis is obtained
And vibration harmonic formula in the y-axis
。
Wherein, the vibration frequency f1 of the ultrasonic knife and the vibration frequency f2 of the two laser ranging sensors meet the conditions
And f2 is>>f1, m is the sampling frequency, the requirement of the laser ranging sensor on the measurement frequency of the ultrasonic knife in the motion state of the ultrasonic knife in a motion period is met by limiting the sampling frequency m, the number of points of the motion trail drawn by the obtained real-time coordinate points of the ultrasonic knife in the motion state is increased, and the accuracy of drawing the motion trail of the ultrasonic knife is improved.
And synthesizing the vibration harmonic waves given by the ultrasonic knife in the feeding direction and the cutting defense line to form an elliptic track.
As shown in fig. 3, the cutter of the ultrasonic blade is fixedly installed at the front end of the horn, piezoelectric drivers are installed in the axial extension direction of the horn and in the direction perpendicular to the axial extension direction of the horn, the piezoelectric drivers on the axial extension of the horn reciprocate along the axial direction of the horn by applying a sine voltage with a specific frequency to the piezoelectric drivers, and the piezoelectric drivers on the axial extension direction perpendicular to the axial extension direction of the horn reciprocate along the direction perpendicular to the axial direction of the horn, so that the cutter of the ultrasonic blade performs simple harmonic motion along the acting direction of the piezoelectric drivers.
The driving fatigue analysis module respectively extracts vibration parameters of the ultrasonic blade on the x axis and the y axis before and after the continuous accumulated working time T, simultaneously extracts the surface temperature of a piezoelectric driver for driving the amplitude transformer under the continuous accumulated working time T, obtains the amplitude of driving displacement of the piezoelectric driver under the interference of the surface temperature by analyzing the surface temperature of the piezoelectric driver, performs driving fatigue analysis by combining the vibration parameters of the ultrasonic blade on the x axis and the y axis before and after twice, and analyzes the driving fatigue offset of the ultrasonic blade under the surface temperature of the piezoelectric driver in real time.
When the ultrasonic knife is subjected to drive fatigue analysis, the related vibration parameters are the vibration frequency and the vibration amplitude of the ultrasonic knife, and the amplitude transformer connected with the ultrasonic knife is driven by the piezoelectric driver, so that the piezoelectric driver generates heat along with the increase of the use duration, the problem of drive fatigue occurs, and the work of the ultrasonic knife tool is influenced.
The invention discloses an analysis method of a driving fatigue interference coefficient in at least one embodiment, wherein a driving fatigue analysis module is used for analyzing the driving fatigue interference according to the surface temperature of a piezoelectric driver, and the method comprises the following steps:
step 1, continuously supplying sine voltage with fixed frequency to a piezoelectric driver of the ultrasonic scalpel;
step 2, extracting the surface temperature of the piezoelectric driver for driving the amplitude transformer under the continuous accumulated working time T, and drawing a surface temperature curve;
step 3, establishing a surface temperature model of the piezoelectric actuator along with the working time, and recording the model as the surface temperature model
，
The surface temperature of the piezoelectric actuator under the continuous accumulated working time t,
the surface temperature at the initial operating state of the piezoelectric actuator,
continuously accumulating the surface temperature of the piezoelectric driver under the working time T, wherein the surface temperature model is the surface temperature of the piezoelectric driver under the normal working conditionA degree model, wherein the surface temperature cannot be predicted under the condition of piezoelectric actuator failure;
step 4, obtaining a driving displacement curve chart of the piezoelectric driver at each surface temperature, wherein the driving displacement curve chart at the same surface temperature is a sine wave as the driving voltage of the piezoelectric driver is a sine driving voltage, as shown in fig. 4;
step 5, extracting the amplitude values in the driving displacement curve graph at each surface temperature, establishing a mapping relation corresponding to the surface temperature of the piezoelectric driver and the amplitude value of the driving displacement, and enabling the driving displacement curve at different surface temperatures to drift;
step 6, extracting vibration parameters of the ultrasonic knife before and after the continuous accumulated working time t, analyzing the driving fatigue offset of the voltage driver to the ultrasonic knife by adopting a driving fatigue interference model, and changing the vibration frequency of the ultrasonic knife along with the change of the vibration frequency of the piezoelectric driver;
the formula for calculating the driving fatigue offset of the piezoelectric driver to the ultrasonic knife is as follows:
For both piezoelectric actuators on the horn axis and those perpendicular to the horn axis, the actuation displacement occurs with changes in surface temperature.
The method comprises the steps of analyzing a piezoelectric driver for driving an ultrasonic knife, obtaining the surface temperature of the piezoelectric driver caused by the change of the piezoelectric driver along with the single accumulated working time, establishing a mapping relation between the surface temperature of the piezoelectric driver and the driving displacement between the piezoelectric drivers, analyzing the driving fatigue offset of the piezoelectric driver to the ultrasonic knife according to the driving displacement of the piezoelectric driver and the vibration amplitude of the ultrasonic knife, analyzing the driving condition of the piezoelectric driver to the ultrasonic knife under the influence of temperature by establishing the correlation between the piezoelectric driver and the ultrasonic knife, establishing the processing offset generated along with the change of the service time of the ultrasonic knife, and performing driving compensation according to the driving fatigue offset of the piezoelectric driver to the ultrasonic knife in the later period so as to ensure that the processing precision of the ultrasonic knife is kept constant and is not interfered by the performance of the piezoelectric driver.
The single accumulated working time is that the ultrasonic knife is timed from the time of starting working to the time of stopping working, and the ultrasonic knife continuously works in the process from the beginning of working to the time of stopping working.
The driving compensation adjusting module is used for obtaining the driving fatigue offset of the ultrasonic knife under the surface temperature of the piezoelectric driver, judging whether the driving fatigue offset of the ultrasonic knife in the feeding direction and the cutting direction is larger than a set driving fatigue offset threshold value or not respectively, and if the driving fatigue offset in one direction is larger than the set driving fatigue offset threshold value, controlling the ultrasonic knife head to perform driving fatigue offset compensation along the direction by using the set driving fatigue offset threshold value, so that the surface of a workpiece is in a horizontal state when the ultrasonic knife performs processing on the workpiece, the situation that the processing size of the workpiece deviates from the actual state due to the driving fatigue offset of the piezoelectric driver is avoided, and the processing precision of the workpiece is greatly improved.
In the industry, when the ultrasonic knife is used for machining, long-term abrasion between the ultrasonic knife and the surface of a workpiece also interferes with the machining precision of the ultrasonic knife to cause abrasion of the ultrasonic knife, and the temperature compensation of the piezoelectric driver and the cutter abrasion of the ultrasonic knife need to be considered at the same time to further improve the machining precision of the ultrasonic knife on the surface of the workpiece.
Therefore, the system further comprises a cutter abrasion pre-estimation module, wherein the cutter abrasion pre-estimation module is used for acquiring the processing time of the ultrasonic cutter on the surfaces of workpieces made of different materials and the feeding amount of the ultrasonic cutter, extracting the pre-established reverse abrasion coefficients of the different materials to the ultrasonic cutter, acquiring a cutter abrasion pre-estimation amount, judging whether the cutter abrasion pre-estimation amount reaches a set cutter abrasion threshold value, and if the cutter abrasion pre-estimation amount is larger than the set cutter abrasion threshold value, replacing the ultrasonic cutter.
The reverse wear coefficient is a wear numerical value of the ultrasonic knife caused by the fact that the ultrasonic knife slides for a unit distance when cutting is carried out on a unit feeding amount, the higher the hardness of the material is, the larger the reverse wear coefficient of the ultrasonic knife is, and the reverse wear coefficients corresponding to workpieces made of different materials are obtained through experiments.
The tool wear is estimated as
，
For the expected amount of ultrasonic blade tool wear,
in order to obtain the reverse wear coefficient when processing the j-th workpiece material,
the speed of the ultrasonic knife in the cutting direction in the process of cutting the jth workpiece material,
the accumulated processing time of the ultrasonic knife to the jth workpiece material,
the feed amount of the ultrasonic knife for cutting the surface of the j-th workpiece.
Because the abrasion detection difficulty of the ultrasonic knife is high, the abrasion condition of the ultrasonic knife is estimated by adopting reverse derivation of a workpiece machined by the ultrasonic knife so as to replace the ultrasonic knife, the actual abrasion condition of the knife obtained by adopting the calculation formula of the tool abrasion estimated value is close to the estimated abrasion condition, the abrasion condition of the knife can be estimated quickly and accurately by adopting the calculation formula of the tool abrasion estimated value, the effective estimation of the abrasion degree of the ultrasonic knife in the workpiece machining process is improved, and the error of manual judgment of the abrasion degree of the knife is reduced.
The foregoing is illustrative and explanatory only of the present invention, and it is intended that the present invention cover modifications, additions, or substitutions by those skilled in the art, without departing from the spirit of the invention or exceeding the scope of the claims.
Claims (6)
1. The utility model provides a real-time amplitude automatic measuring system of ultrasonic knife, includes range finding detection module, and range finding detection module includes two laser emission light source mutually perpendicular's laser range finding sensor, detects the distance on ultrasonic knife feed direction and the depth of cut respectively, its characterized in that:
the device also comprises a vibration harmonic wave construction module, a driving fatigue analysis module and a driving compensation adjustment module;
the vibration harmonic wave construction module respectively extracts the distances from the two laser ranging sensors to the surface of the ultrasonic knife, correlates the distances detected by the two laser ranging sensors, obtains the real-time position coordinate of the cutting edge of the ultrasonic knife according to the geometric relation, obtains the motion track of the ultrasonic knife in the working process, analyzes the motion track of the ultrasonic knife, and obtains the vibration harmonic wave equations of the ultrasonic knife on the x axis and the y axis;
the driving fatigue analysis module extracts the surface temperature of a piezoelectric driver for driving the amplitude transformer under the continuous accumulated working time T, obtains the amplitude of driving displacement of the piezoelectric driver under the interference of the surface temperature by analyzing the surface temperature of the piezoelectric driver, and analyzes the driving fatigue by combining the vibration parameters of the front ultrasonic knife and the rear ultrasonic knife on the x axis and the y axis to analyze the driving fatigue offset of the ultrasonic knife under the surface temperature of the piezoelectric driver in real time;
the driving fatigue analysis module carries out driving fatigue interference analysis according to the surface temperature of the piezoelectric driver, and adopts the following method, which comprises the following specific steps:
step 1, continuously supplying sinusoidal voltage with fixed frequency to a piezoelectric driver of an ultrasonic knife;
step 2, extracting the surface temperature of the piezoelectric driver for driving the amplitude transformer under the continuous accumulated working time T, and drawing a surface temperature curve;
step 3, establishing a surface temperature model of the piezoelectric driver along with the working time;
step 4, obtaining a driving displacement curve chart of the piezoelectric driver at each surface temperature, wherein the driving displacement curve chart at the same surface temperature is a sine wave as the driving voltage of the piezoelectric driver is a sine driving voltage;
step 5, extracting the amplitude values in the driving displacement curve chart at each surface temperature, establishing a mapping relation corresponding to the surface temperature of the piezoelectric driver and the amplitude value of the driving displacement, and enabling the driving displacement curve at different surface temperatures to drift;
step 6, extracting vibration parameters of the ultrasonic blade before and after the continuous accumulated working time t, analyzing the driving fatigue offset of the voltage driver to the ultrasonic blade by adopting a driving fatigue interference model, wherein the vibration frequency of the ultrasonic blade changes along with the change of the vibration frequency of the piezoelectric driver;
the surface temperature model of the piezoelectric actuator is
，
The surface temperature of the piezoelectric actuator under the continuous accumulated working time t,
the surface temperature at the initial operating state of the piezoelectric actuator,
continuously accumulating the surface temperature of the piezoelectric driver under the working time T;
the formula for calculating the driving fatigue offset of the piezoelectric driver to the ultrasonic knife is as follows:
the driving compensation adjusting module is used for obtaining the driving fatigue offset of the ultrasonic knife under the surface temperature of the piezoelectric driver, respectively judging whether the driving fatigue offset of the ultrasonic knife in the feeding direction and the cutting direction is larger than a set driving fatigue offset threshold value, and if the driving fatigue offset in one direction is larger than the set driving fatigue offset threshold value, controlling the ultrasonic knife head to perform driving fatigue offset compensation along the direction by using the set driving fatigue offset threshold value.
2. The system for automatically measuring the real-time amplitude of the ultrasonic knife according to claim 1, wherein the two laser ranging sensors are a laser ranging sensor a and a laser ranging sensor b, respectively, the laser ranging sensor a and the laser ranging sensor b are triggered simultaneously, and the measured data at the same time point are correlated.
3. The system for automatically measuring the real-time amplitude of the ultrasonic knife as claimed in claim 2, wherein the real-time position coordinates (xi, yi) of the blade of the ultrasonic knife, which are tracked, are known by using a geometrical relationship:
the point of the ultrasonic knife is rhombic, and the included angle of the point of the ultrasonic knife is
The values of the parameters, which are known,
the distance from the laser ranging sensor b to the surface of the ultrasonic knife when the cutting edge of the ultrasonic knife is positioned at the origin of coordinates and in a static state,
the distance from the laser ranging sensor a to the surface of the ultrasonic knife when the ultrasonic knife is in a static state,
in order to measure the distance from the sensor b to the surface of the ultrasonic knife at the ith sampling time,
the distance from the laser ranging sensor a to the surface of the ultrasonic knife at the ith sampling time;
the real-time position coordinates xi and yi of the cutting edge of the ultrasonic knife are obtained by the formula
。
4. The system for automatically measuring the real-time amplitude of the ultrasonic blade of claim 3, wherein the method for constructing the vibration harmonic equation on the x axis and the y axis respectively during the working process of the ultrasonic blade comprises the following steps:
step 1, respectively extracting intersection point positions of a motion track of the ultrasonic knife and an x axis and a y axis, wherein the coordinates of the intersection points of the motion track of the ultrasonic knife and the x axis are (x 1, 0) and (x 2, 0), and the coordinates of the intersection points of the motion track of the ultrasonic knife and the y axis are (0, y 1) and (0, y 2);
step 2, calculating the amplitude A of the harmonic wave of the ultrasonic knife in the feeding direction and the amplitude B of the harmonic wave of the ultrasonic knife in the cutting direction,
，
；
step 3, extracting position coordinates on the n-times motion track and bringing the position coordinates into a vibration harmonic equation
Respectively deducing the vibration initial phases of the rotating shaft on the x axis and the y axis at the sampling time point t, wherein the vibration initial phases are respectively
And
and is and
f is the sampling frequency sent by the laser ranging sensor, and the sampling frequencies of the laser ranging sensor a and the laser ranging sensor b are the same;
step 4, substituting the amplitude of the vibration harmonic wave in the step 2 and the vibration initial phase in the step 3 to obtain a vibration harmonic wave formula of the ultrasonic knife on the x axis
And vibration harmonic formula in the y-axis
。
5. The system of claim 4, wherein the vibration frequency f1 of the ultrasonic blade and the vibration frequency f2 of the two laser ranging sensors satisfy the condition
And f2 is>>f1, m is the number of samples.
6. The system of claim 5, further comprising a tool wear estimation module, wherein the tool wear estimation module is configured to obtain a length of time for processing the surface of the workpiece made of different materials by the ultrasonic tool and a feeding amount of the ultrasonic tool, extract a pre-established reverse wear coefficient of the ultrasonic tool made of different materials, obtain a tool wear estimation, determine whether the tool wear estimation reaches a set tool wear threshold, and replace the ultrasonic tool if the tool wear estimation is greater than the set tool wear threshold.
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