阅读说明：本技术 一种超声滚压加工温度测量分析方法 (Ultrasonic rolling processing temperature measurement analysis method ) 是由 丁丛 朴钟宇 周振宇 于 2019-10-17 设计创作，主要内容包括：本发明公开了一种超声滚压加工温度测量分析方法,涉及工程材料表面强化技术领域,通过在工件表面附近安装热电偶温度测量装置,在超声滚压加工过程中,实时采集滚压刀具与工件表面间产生的温度信号,然后运用混沌理论对温度信号进行非线性动力学分析,揭示某一特定工艺参数下加工过程中产生的温度信号的动力学特性及演化规律,分析温度信号与工艺参数间的相关性,进而优化超声滚压加工工艺参数,提高材料力学性能。本发明从动力学角度分析工艺参数对材料力学性能的影响,避免了加工后一系列工件表面的力学性能测试与分析,不仅节省了大量测试时间与费用,还大幅度加快和提高了工艺参数优化进程与效率。(The invention discloses an ultrasonic rolling processing temperature measurement and analysis method, which relates to the technical field of engineering material surface strengthening. The invention analyzes the influence of the process parameters on the mechanical property of the material from the aspect of dynamics, avoids the mechanical property test and analysis of the surfaces of a series of processed workpieces, saves a large amount of test time and cost, and greatly accelerates and improves the process and efficiency of optimizing the process parameters.)

1. The ultrasonic rolling processing temperature measurement analysis method is characterized by comprising the following steps of:

(1) installing a temperature measuring device on the workpiece;

(2) acquiring a temperature signal generated between a cutter and the surface of a workpiece in real time in the ultrasonic rolling process, wherein the sampling frequency is 500 Hz;

(3) after the processing process is finished, carrying out noise reduction on the temperature signal, then calculating the maximum Lyapunov index of the temperature signal, and carrying out chaotic characteristic analysis;

(4) testing and analyzing the mechanical property of the processed workpiece;

(5) performing correlation analysis on the chaotic characteristic of the temperature signal and the mechanical property of the temperature signal, and determining the correlation between the chaotic characteristic of the temperature signal and the mechanical property evaluation parameter;

(6) adjusting ultrasonic rolling processing technological parameters according to the chaotic characteristics of the temperature signals, then processing, analyzing the temperature signals, analyzing the corresponding mechanical properties, then further optimizing the technological parameters, and finally obtaining the optimal technological parameter combination.

2. The ultrasonic rolling processing temperature measurement analysis method according to claim 1, characterized in that: in the step (1), a mounting hole is processed on the side surface of the workpiece, and the hole is deep to the central position of a processing area; and installing a needle-shaped thermocouple at the position of the installation hole, connecting the needle-shaped thermocouple with the signal acquisition card, and finally accessing the needle-shaped thermocouple into a computer for subsequent signal processing and analysis.

3. The ultrasonic rolling processing temperature measurement analysis method according to claim 1, characterized in that: in step (3), every 10000 data points in the temperature signal are continuously and non-overlapped and divided into a plurality of parts, and the maximum Lyapunov index corresponding to each part is calculated.

4. The ultrasonic rolling processing temperature measurement analysis method according to claim 1, characterized in that: in the step (5), the chaos characteristic and the complexity of the temperature signal are corresponding to the roughness, the hardness and the micro-morphology of the surface of the processed workpiece, and the chaos characteristic and the complexity are used for further selecting the process parameters.

5. The ultrasonic rolling processing temperature measurement analysis method according to claim 1, characterized in that: in the step (6), the technological parameters are replaced to carry out ultrasonic rolling processing, meanwhile, temperature signals between the cutter and the surface of the workpiece are collected, different mechanical property tests are not carried out on the processed workpiece, and the mechanical property of the workpiece under the technological parameters is obtained directly by analyzing the chaotic characteristics of the temperature signals and is used for guiding the optimization technology of the technological parameters.

6. The ultrasonic rolling processing temperature measurement analysis method according to claim 2, characterized in that: a mounting hole with the diameter of 1mm is machined at the position 1mm away from the surface to be machined on the side surface of the workpiece, and a needle-shaped thermocouple with the diameter of 1mm is installed at the position of the mounting hole.

7. The ultrasonic rolling processing temperature measurement analysis method according to claim 3, characterized in that: and (3) calculating the maximum Lyapunov value of the temperature signal by adopting a Wolf reconstruction method, wherein the specific calculation process is as follows:

①, carrying out phase space reconstruction on the univariate temperature signal x (t) by using Takens theory;

② selection of a trajectory in reconstruction space:

y(t)＝{x(t),x(t+τ),…,x(t+(m-1)τ)} (1)

where m is the embedding dimension and τ is the time delay;

③ then looks at the point on the track closest to the initial reference point in equation (2) and sets the distance between these two points to L (t)₀)；

y(t₀)＝{x(t₀),x(t+τ),…,x(t₀+(m-1)τ)} (2)

In the formula, t₀Is the initial time; y (t)₀) Is t₀A track corresponding to the moment;

④ at a later time t₁Initial length L (t)₀) Evolution as L' (t)₁) Then, the next data point is found to replace, and the new data point should satisfy two criteria: a. ensuring the distance L (t) between the point and the evolved reference point₁) Is small enough; b. ensuring an angle theta between an evolution length element and a replacement length element₁The variation is small; continuously evolving and replacing the data until the data run through the whole reference track;

⑤ according to the values of all points and length elements, the calculation result of the maximum Lyapunov exponent is finally obtained as follows:

wherein M is the total number of substitution steps, t_MIs the total time; t is t_k-t_k-1Is the time step between two substitutions;

⑥, analyzing the maximum Lyapunov value corresponding to each part of the temperature signal after reconstruction, if the maximum Lyapunov value is larger than 0, indicating that the temperature signal has chaotic characteristics, and if the maximum Lyapunov value is smaller than 0, indicating that the temperature signal does not have chaotic characteristics.

Technical Field

The invention relates to the technical field of engineering material surface strengthening, in particular to an ultrasonic rolling processing temperature measurement and analysis method.

Background

The rolling processing is a surface strengthening technology without cutting, and the ultrasonic rolling processing is a novel surface strengthening technology which combines the rolling technology with the flutter generated by ultrasonic waves. The mechanical properties of the workpiece after ultrasonic rolling processing need to be measured and analyzed for roughness, hardness, residual stress and surface micro-topography. When the surface roughness of a workpiece is measured, a surface profiler is required for measurement, the measurement result of the equipment has larger errors after long-term operation, and the corresponding measurement result inevitably influences the evaluation of the surface quality to a certain extent. When the surface hardness of a workpiece is tested, a test sample with a specific size needs to be prepared, and the test sample also needs to be cleaned, embedded, ground and polished, so that the degree is too complex and tedious. When observing the surface microscopic morphology, a pretreatment sample with a specific size needs to be prepared, and then sample inlaying, grinding and polishing, corrosion treatment and the like are carried out. The sample preparation procedure is not only complicated, but also has very high requirements on the preparation technology. And finally, analyzing and evaluating different mechanical property parameters to obtain the working performance of the rolled workpiece under the process parameters.

The mechanical property parameter testing and analyzing process is not only complex and tedious, but also has very high technical requirements on testers, which greatly increases the time of the testing and analyzing process, and the testing cost is too high. Importantly, the time for optimizing the technological parameters of the ultrasonic rolling processing is prolonged. In the ultrasonic rolling process, a temperature signal is generated between the rolling cutter and the surface of a workpiece, and the signal can change along with the change of parameters such as pressure, main shaft rotating speed, rolling times, ultrasonic frequency and the like.

Disclosure of Invention

In order to overcome the defects of the existing detection technology for the performance of the machined workpiece, the invention provides an ultrasonic rolling machining temperature measurement analysis method, wherein a thermocouple is used for collecting a temperature signal in the machining process, the chaos characteristic of the temperature signal is researched by applying the chaos theory, the mechanical property of the surface of the workpiece under different process parameter combinations is reflected, and then the process parameters are optimized; the complexity and time consumption of a test sample testing process in the traditional mechanical property testing process and high testing cost are solved, the mechanical property of a workpiece is more accurately analyzed from the aspect of mechanics, the optimization process of ultrasonic rolling processing technological parameters is accelerated, and the optimization efficiency and accuracy are greatly improved.

The technical scheme adopted by the invention for solving the technical problems is as follows:

an ultrasonic rolling processing temperature measurement analysis method comprises the following steps:

(1) installing a temperature measuring device on the workpiece;

(2) acquiring a temperature signal generated between a cutter and the surface of a workpiece in real time in the ultrasonic rolling process, wherein the sampling frequency is 500 Hz;

(3) after the processing process is finished, carrying out noise reduction on the temperature signal, then calculating the maximum Lyapunov index of the temperature signal, and carrying out chaotic characteristic analysis;

(4) testing and analyzing the mechanical property of the processed workpiece;

(5) performing correlation analysis on the chaotic characteristic of the temperature signal and the mechanical property of the temperature signal, and determining the correlation between the chaotic characteristic of the temperature signal and the mechanical property evaluation parameter;

(6) adjusting ultrasonic rolling processing technological parameters according to the chaotic characteristics of the temperature signals, then processing, analyzing the temperature signals, analyzing the corresponding mechanical properties, then further optimizing the technological parameters, and finally obtaining the optimal technological parameter combination.

Further, in the step (1), a mounting hole is machined in the side face of the workpiece, and the hole is deep to the center of the machining area; and installing a needle-shaped thermocouple at the position of the installation hole, connecting the needle-shaped thermocouple with the signal acquisition card, and finally accessing the needle-shaped thermocouple into a computer for subsequent signal processing and analysis.

Still further, in step (3), each 10000 data points in the temperature signal are continuously and non-overlapped and divided into a plurality of parts, and the maximum Lyapunov index corresponding to each part is calculated.

And (5) establishing a corresponding relation between the chaotic characteristic and the complexity of the temperature signal and the roughness, the hardness and the micro-morphology of the surface of the processed workpiece for further selecting the process parameters.

And further, in the step (6), replacing the technological parameters to carry out ultrasonic rolling processing, simultaneously acquiring temperature signals between the cutter and the surface of the workpiece, not carrying out different mechanical property tests on the processed workpiece, directly analyzing the chaotic characteristics of the temperature signals to obtain the mechanical properties of the workpiece under the technological parameters, and using the chaotic characteristics to guide the optimization technology of the technological parameters.

And further, a mounting hole with the diameter of 1mm is machined at the position, 1mm away from the surface to be machined, of the side surface of the workpiece, and a needle-shaped thermocouple with the diameter of 1mm is installed at the position of the mounting hole.

Further, the maximum Lyapunov value of the temperature signal is calculated by adopting a Wolf reconstruction method, and the specific calculation process is as follows:

①, carrying out phase space reconstruction on the univariate temperature signal x (t) by using Takens theory;

② selection of a trajectory in reconstruction space:

y(t)＝{x(t),x(t+τ),…,x(t+(m-1)τ)} (1)

where m is the embedding dimension and τ is the time delay;

③ then looks at the point on the track closest to the initial reference point in equation (2) and sets the distance between these two points to L (t)₀)；

y(t₀)＝{x(t₀),x(t+τ),…,x(t₀+(m-1)τ)} (2)

In the formula, t₀Is the initial time; y (t)₀) Is t₀A track corresponding to the moment;

④ at a later time t₁Initial length L (t)₀) Evolution as L' (t)₁) Then, the next data point is found to replace, and the new data point should satisfy two criteria: a. ensuring the distance L (t) between the point and the evolved reference point₁) Is small enough; b. ensuring an angle theta between an evolution length element and a replacement length element₁The variation is small; continuously evolving and replacing the data until the data run through the whole reference track;

⑤ according to the values of all points and length elements, the calculation result of the maximum Lyapunov exponent is finally obtained as follows:

wherein M is the total number of substitution steps, t_MIs the total time; t is t_k-t_k-1Is the time step between two substitutions;

⑥, analyzing the maximum Lyapunov value corresponding to each part of the temperature signal after reconstruction, if the maximum Lyapunov value is larger than 0, indicating that the temperature signal has chaotic characteristics, and if the maximum Lyapunov value is smaller than 0, indicating that the temperature signal does not have chaotic characteristics.

The invention has the following beneficial effects: according to the temperature measurement analysis method, a thermocouple, an acquisition card and a computer are used for acquiring temperature signals, the chaos theory is used for performing dynamic analysis on the temperature signals, the correlation between the temperature signals and mechanical properties is established, the temperature measurement analysis method is further directly used for evaluating the mechanical properties of the strengthened workpieces under different process parameter combinations, the defects that a common mechanical property test method is time-consuming, high in cost, high in preparation technology and the like are overcome, the process of optimizing process parameters is accelerated, and the optimization efficiency and accuracy are improved.

Drawings

FIG. 1 is a flow chart of the operation of the present invention.

Fig. 2 is a diagram of a temperature measuring device of the present invention.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

Referring to fig. 1 and 2, an ultrasonic rolling process temperature measurement analysis method includes the following steps:

(1) mounting a temperature measuring device on a workpiece: processing a mounting hole with the diameter of 1mm at a position 1mm away from the surface to be processed on the side surface of the workpiece 1, wherein the hole is deep to the central position of a processing area; a needle-shaped thermocouple 2 with the diameter of 1mm is arranged at the position of a workpiece mounting hole, the needle-shaped thermocouple 2 is connected with a signal acquisition card 3, and finally the needle-shaped thermocouple is connected into a computer 4 for subsequent signal processing and analysis;

(2) carrying out ultrasonic rolling on the aluminum alloy workpiece under the conditions that the rolling force is 60N, the transverse feed amount is 118mm/min, the rotating speed of a main shaft is 500r/min, the amplitude of ultrasonic waves is 6 microns and the rolling frequency is 6 times, and acquiring a temperature signal generated between a cutter and the surface of the workpiece in real time in the ultrasonic rolling process, wherein the sampling frequency is 500 Hz;

(3) after the processing process is finished, MATLAB software is used for carrying out noise reduction processing on the temperature signal, then every 10000 data points in the temperature signal are continuously and non-overlapped and divided into a plurality of parts, the Wolf reconstruction method is adopted to calculate the maximum Lyapunov index corresponding to each part, chaotic characteristic analysis is carried out, and the specific calculation process is as follows:

①, carrying out phase space reconstruction on the univariate temperature signal x (t) by using Takens theory;

② selection of a trajectory in reconstruction space:

y(t)＝{x(t),x(t+τ),…,x(t+(m-1)τ)} (1)

where m is the embedding dimension and τ is the time delay;

③ then looks at the point on the track closest to the initial reference point in equation (2) and sets the distance between these two points to L (t)₀)；

y(t₀)＝{x(t₀),x(t+τ),…,x(t₀+(m-1)τ)} (2)

In the formula, t₀Is the initial time; y (t)₀) Is t₀A track corresponding to the moment;

④ at a later time t₁Initial length L (t)₀) Evolution as L' (t)₁) Then, the next data point is found to replace, and the new data point should satisfy two criteria: a. ensuring the distance L (t) between the point and the evolved reference point₁) Is small enough; b. ensuring an angle theta between an evolution length element and a replacement length element₁The variation is small; continuously evolving and replacing the data until the data run through the whole reference track;

⑤ according to the values of all points and length elements, the calculation result of the maximum Lyapunov exponent is finally obtained as follows:

wherein M is the total number of substitution steps, t_MIs the total time; t is t_k-t_k-1Is the time step between two substitutions;

⑥, analyzing the maximum Lyapunov value corresponding to each part of the temperature signal after reconstruction, if the maximum Lyapunov value is larger than 0, indicating that the temperature signal has chaotic characteristics, and if the maximum Lyapunov value is smaller than 0, indicating that the temperature signal does not have chaotic characteristics;

(4) testing and analyzing the mechanical property of the processed workpiece;

(5) establishing a corresponding relation between the chaotic characteristic and the complexity of the temperature signal and the roughness, the hardness and the micro-morphology of the surface of the processed workpiece for further selecting process parameters;

(6) adjusting ultrasonic rolling processing technological parameters according to the chaotic characteristics of the temperature signals, then carrying out ultrasonic rolling processing, simultaneously acquiring the temperature signals between the cutter and the surface of the workpiece, not carrying out different mechanical property tests on the processed workpiece, directly obtaining the mechanical property of the workpiece under the technological parameters by analyzing the chaotic characteristics of the temperature signals, then further optimizing the technological parameters, and finally obtaining the optimal technological parameter combination.

The invention utilizes the thermocouple, the acquisition card and the computer to acquire the temperature signal, dynamically analyzes the temperature signal by using the chaos theory, establishes the correlation between the temperature signal and the mechanical property, is further directly used for evaluating the mechanical property of the strengthened workpiece under different process parameter combinations, overcomes the defects of time consumption, high cost, high preparation technology and the like of a common mechanical property testing method, accelerates the process of process parameter optimization, and improves the optimization efficiency and accuracy.