CN104897268A - Laser-scanning-based apparatus and method for modal shape testing of high-grade numerical control machine tool - Google Patents

Abstract

The invention discloses a laser scanning-based high-grade numerical control machine tool modal vibration shape testing device and method, belonging to the technical field of vibration testing. Including: signal generator, multiple power amplifiers, multiple exciters, multiple force sensors, laser scanning device, data acquisition instrument, industrial computer; signal generator is connected with industrial computer and multiple power amplifiers at the same time; multiple One-to-one independent connections between the power amplifier and multiple exciters and between multiple exciters and multiple force sensors; multiple force sensors are distributed and installed on the predetermined vibration points of the machine tool; each The output ends of the force sensors are all connected to the input ends of the data acquisition instrument; the other input end of the data acquisition instrument is connected to the output end of the laser vibrometer in the laser scanning device; meanwhile, the data acquisition instrument is also interconnected with the industrial computer ; The present invention makes up for the lack of advanced measurement technology and measurement means in the machine tool industry.

Description

Modal vibration testing device and method for high-end CNC machine tools based on laser scanning

technical field

The invention belongs to the technical field of vibration testing, and in particular relates to a laser scanning-based modal vibration testing device and method for a high-grade numerically controlled machine tool.

Background technique

In the machine tool industry, the number of axes controlled by the CNC machine tool is generally used as the standard to classify the grades. Those with less than three axes are low-grade, and those with three to five axes or more than five axes are high-end CNC machine tools. At present, my country's machine tool manufacturers are competing to develop high-end CNC machine tools, but most of the market share of high-end CNC machine tools in my country is occupied by foreign companies. One of the important reasons is that the machine tool industry's basic research and development capabilities are weak, the experimental software and hardware conditions are backward, and there is a lack of advanced measurement. Technology and measurement means. The vibration shape test of high-end CNC machine tools is an important link in the development process of machine tools. It generally includes modal vibration test and working vibration shape test. is of great significance. Since the laser vibrometer has the advantages of non-contact and non-destructive testing, and the vibration measuring distance is adjustable, it can also realize vibration testing in high-speed rotation, high-frequency, high-temperature and other environments. At present, many machine tool companies hope to apply it to the modal vibration test of high-end CNC machine tools, but due to the inconvenient use of traditional laser vibrometers, they cannot meet the modal vibration test of high-end CNC machine tools with large structure size and complex surface shape. demand.

Contents of the invention

Aiming at the deficiencies in the prior art, the present invention provides a laser scanning-based modal vibration testing device and method for a high-end numerically controlled machine tool.

Technical scheme of the present invention:

A laser scanning-based modal vibration testing device for a high-end numerically controlled machine tool, comprising: a signal generator, multiple power amplifiers, multiple vibrators, multiple force sensors, a laser scanning device, a data acquisition instrument, and an industrial computer;

The input end of the signal generator is connected with the output end of the industrial computer; the output end of the signal generator is connected with the input ends of the multiple power amplifiers at the same time; the multiple power amplifiers are connected with the multiple power amplifiers Each vibrator and between the multiple vibrators and the multiple force sensors are all one-to-one independent connections; the multiple force sensors are distributed and installed at each excitation point of the machine tool determined in advance on; the output end of each force sensor is connected to the input end of the data acquisition instrument; the other input end of the data acquisition instrument is connected to the output end of the laser vibrometer in the laser scanning device; meanwhile, the data The collector is also interconnected with the industrial computer;

The signal generator is used to send multi-channel random excitation signals of corresponding frequencies according to the instructions of the industrial computer and send them to multiple power amplifiers respectively;

The multiple power amplifiers are used to amplify multiple excitation signals respectively at the same time, and send the amplified excitation signals to multiple exciters respectively;

The plurality of exciters are used to simultaneously excite vibrations at different positions to excite high-grade CNC machine tools to vibrate;

The plurality of force sensors are distributed and installed on the positions of the predetermined excitation points of the machine tool, and are used to respectively obtain the excitation force signals sent by the plurality of exciters and send them to the data acquisition instrument;

The data acquisition instrument is used to collect and record vibration response signals and excitation force signals in real time and transmit them to industrial computers;

The laser scanning device is used to obtain the vibration response signals of different response measuring points of the high-grade CNC machine tool and send them to the data acquisition instrument; the laser scanning device further includes:

The laser vibrometer is used to automatically adjust the position of the laser vibrometer to scan the response measuring points of the high-end CNC machine tool point by point, obtain the vibration response signals of different response measuring points of the high-end CNC machine tool and send them to the data acquisition instrument ;

The automatic position adjustment mechanism of the laser vibrometer is used to automatically adjust the position of the laser vibrometer on the X-axis of the mechanism, the position of the laser vibrometer on the Z-axis of the mechanism, and the rotation of the laser vibrometer on the mechanism. According to the angle of Z-axis rotation, the mechanism can also be moved to the desired position by the user according to the test needs;

The industrial computer is used to control the signal generator to send an excitation signal of a corresponding frequency; according to the structure, shape and size relationship of the machine tool, a wire frame model of a high-end CNC machine tool is established; based on the obtained excitation force signal corresponding to each excitation point and the response signals of each response measuring point, and calculate multiple frequency response functions; use the multi-input multi-response modal parameter identification method to identify the frequency response function, and obtain the natural frequency and modal shape of the high-end CNC machine tool; the obtained The modal vibration shape of the machine tool is simulated, and the animation of the modal vibration shape of the machine tool is obtained.

According to the modal shape testing device for high-end CNC machine tools based on laser scanning, the automatic position adjustment mechanism of the laser vibrometer is composed of an XZ moving platform and a Z-axis rotating platform, and the Z-axis rotating platform can be placed on the XZ moving platform Move along the Z axis and move along the X axis; the laser vibrometer is set on the Z axis rotating platform.

The method for determining the modal vibration shape of a high-grade numerically controlled machine tool by using the laser scanning-based high-grade numerically controlled machine tool mode shape testing device comprises the following steps:

Step 1: Adjust the high-end CNC machine tool to the test state;

Step 2: According to the structure, shape and size relationship of the machine tool, establish a wire frame model of the high-end CNC machine tool, and determine the response measuring points and the interested vibration directions of each response measuring point on the wire frame model of the high-end CNC machine tool;

Step 3: Select j response measuring points from the response measuring points determined in step 2 as excitation points;

Step 4: Distribute and install multiple force sensors at each excitation point;

Step 5: Use the wireframe model of the high-end CNC machine tool to conduct a pre-judgment experiment on the excitation parameters to determine the number of excitation points, the location and direction of the excitation points, and the amplitude of the excitation force at each excitation point;

Step 5-1: In order to obtain good experimental results, a pre-judgment experiment of excitation parameters is required before the formal experiment. Select i response measurement points in the wireframe model of the machine tool, and the number of i satisfies:

i≥λj (1)

In the formula, λ=3~5, the larger the value of λ, the better the effect of the excitation parameter prediction experiment, adjust the laser measuring point to the position of the above i response measuring point, and respectively test to obtain the i response measuring points respectively relative to Based on the coherence function of each excitation point, i*j set of coherence functions are obtained;

Step 5-2: For each excitation point, sum and average the coherence functions of the i response measurement points with respect to the excitation point to calculate the lumped coherence function of the excitation point, and obtain j lumped coherence functions ; If most of the coherence coefficient values corresponding to the lumped coherence function are greater than 0.8, it proves that the excitation amplitude, position and excitation direction corresponding to the excitation point meet the requirements of the mode shape test, and the excitation parameters of the excitation point can be used For formal experiments; if most of the coherence coefficients corresponding to the lumped coherence function are less than 0.8, it is necessary to adjust the excitation amplitude, position and excitation direction corresponding to the excitation point;

Step 5-3: Repeat step 5-2 until the pre-judgment of all excitation points is completed, and finally determine the number of excitation points, the position of each excitation point, the excitation direction of each excitation point, and the The magnitude of the exciting force at the vibration point;

Step 6: Start the formal experiment, start the signal generator to send a random excitation signal, and amplify the excitation signal through the power amplifier and input it to the corresponding exciter;

Step 7: Each exciter excites the machine tool under test at the same time with different excitation amplitudes, and at the same time records the excitation force signal corresponding to each excitation point in real time through the data acquisition instrument;

Step 8: Determine the laser scanning rate, use the laser scanning device to scan point by point along the machine tool response measuring point, and scan along the four directions of +X, -X, +Y, -Y respectively, in line with line by line or line by line Scanning is carried out. During the scanning process, the time domain waveform of the response signal is recorded in real time by the data acquisition instrument, and the vibration scanning time domain signal corresponding to the wireframe model of the machine tool in different rows and columns is obtained;

Step 9: Accurately identify the response signals of different response measuring points corresponding to the vibration scanning signals of different rows and columns in the wireframe model through the sliding window reduction method;

Step 9-1: Determine the number of sliding windows;

According to the n measuring points contained in the row or column corresponding to the scanning signal, determine the number of sliding windows as n;

Step 9-2: Determine the position of the sliding window;

Assuming that the scanning rate of the laser scanning device is v, the vibration response time to complete a certain row or column is t, and the time corresponding to the first scanning response measurement point is the scanning start time t ₀ , then two adjacent response measurement points The time difference τ of is:

τ=t/(n-1) (2)

At this time, the moment corresponding to the kth measuring point (k=1,2,...,n) concerned is:

${\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; t</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

Step 9-3: Use the sliding window width determination criterion to set the time width of the sliding window; the sliding window width determination criterion is as follows:

$\mathrm{<span\; class="notranslate">\; \&Delta;t</span>}<span\; class="notranslate">\; \&le;</span>\frac{\mathrm{<span\; class="notranslate">\; d</span>}}{\mathrm{<span\; class="notranslate">\; v</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

In the formula, Δt is the width of the sliding window; d is the diameter of a single response measuring point, generally 0.001-0.005m; v is the scanning rate of the laser scanning device, the unit is m/s;

Step 9-4: extracting the response signal of the response measuring point from the vibration scanning signal;

For k=1, that is, the first response measuring point, take the time t ₀ to t ₀ +Δt of the vibration scanning time domain signal as the response signal of the response measuring point; for k=2,...,n-1, that is, the first From 2 response measuring points to the n-1th response measuring point, take the time t _k -0.5Δt time to t _k +0.5Δt time of the vibration scanning time domain signal as the response signal of the response measuring point; for k=n, that is, For n response measuring points, take the vibration scanning time domain signal from t-Δt time to t time as the response signal of the response measuring point.

Step 10: Calculate multiple frequency response functions based on the obtained excitation force signals corresponding to each excitation point and the response signals of each response measurement point;

Step 11: Use the multi-input multi-response modal parameter identification method to identify the frequency response function, obtain the natural frequency and mode shape of the high-end CNC machine tool, and simulate the obtained mode shape of the machine tool to obtain the mode shape of the machine tool animation.

Beneficial effects: the present invention utilizes the advantages of non-contact and non-destructive testing of the laser vibrometer, and on the basis of the laser vibrometer, aims at the requirements of the modal vibration test of high-end numerically controlled machine tools with large structural dimensions and complex surface shapes, and develops a The laser scanning device with flexible movement and fast scanning vibration measurement function also proposes a sliding window reduction method to more accurately and efficiently complete the task of modal vibration test of high-end CNC machine tools, making up for the advanced measurement technology and measurement of the machine tool industry. The lack of means will help improve the market competitiveness of domestic high-end CNC machine tools.

Description of drawings

Fig. 1 is a schematic structural view of a high-grade numerically controlled machine tool modal shape testing device based on laser scanning in an embodiment of the present invention;

Fig. 2 is a structural schematic diagram of an automatic position adjustment mechanism of a laser vibrometer according to an embodiment of the present invention;

Fig. 3 is a flow chart of a method for testing the modal vibration shape of a high-end numerically controlled machine tool based on laser scanning in an embodiment of the present invention;

Fig. 4 is a wireframe model diagram of a high-grade numerically controlled machine tool of an embodiment of the present invention;

Fig. 5 is the schematic diagram that adopts laser scanning device to obtain the vibration response signal of different response measuring points of high-grade numerical control machine tool in an embodiment of the present invention;

6 is a schematic diagram of a method for identifying response signals of different response measuring points from vibration scanning signals according to an embodiment of the present invention;

Fig. 7 is a frequency response function curve diagram for identifying natural frequency, damping ratio and mode shape according to an embodiment of the present invention;

Fig. 8 is an animated diagram of the third-order mode vibration shape of a high-end numerically controlled machine tool according to an embodiment of the present invention.

Detailed ways

An embodiment of the present invention will be described in detail below in conjunction with the accompanying drawings.

The high-grade numerically controlled machine tool modal shape testing device based on laser scanning of the present invention, as shown in Figure 1, comprises: signal generator, multiple power amplifiers, multiple exciters, multiple force sensors, laser scanning device, data Acquisition instrument, industrial computer; wherein, the input end of the signal generator is connected with the output end of the industrial computer; the output end of the signal generator is connected with the input end of each power amplifier at the same time; between multiple power amplifiers and multiple exciters and Multiple exciters and multiple force sensors are connected one-to-one independently, that is, the output end of a power amplifier is connected to the input end of a corresponding exciter, and the output end of an exciter is connected to the corresponding The input end of a force sensor is connected; a plurality of force sensors are distributed and installed on each excitation point of the machine tool determined in advance; the output ends of each force sensor are connected to the input end of the data acquisition instrument; the other input end of the data acquisition instrument is connected to the The output end of the laser vibrometer in the laser scanning device is connected; at the same time, the data acquisition instrument is also interconnected with the industrial computer;

The laser scanning device is used to obtain the vibration response signals of different response measuring points of high-end CNC machine tools and send them to the data acquisition instrument; the laser scanning device further includes a laser vibrometer and an automatic adjustment mechanism for the position of the laser vibrometer: a laser The vibrometer is used to automatically adjust the position of the laser vibrometer to scan the excitation measurement points of the high-end CNC machine tool point by point, and obtain the vibration response signals of different excitation measurement points of the high-end CNC machine tool and send them to the data acquisition instrument; The laser vibrometer of this embodiment adopts the SOPTOP LV-S01-DB non-contact portable laser vibrometer, which is connected to the data acquisition analyzer through the BNC output terminal, and the minimum resolution of the vibration velocity is 0.02 μm/s. Its working distance is 0.15m ~ 30m, and its frequency range is 1Hz ~ 22KHZ. It uses red laser, which is safe and visible. It is used to make up for the influence of the traditional acceleration sensor on the inherent characteristics of the test system due to the heavy additional mass; the position of the laser vibrometer is automatically The adjustment mechanism is used to automatically adjust the position of the laser vibrometer on the X-axis of the mechanism, the position of the laser vibrometer on the Z-axis of the mechanism, and the rotation angle of the laser vibrometer around the Z-axis on the mechanism. It can also be moved to the desired location by the user according to the testing needs. The automatic position adjustment mechanism of the laser vibrometer in this embodiment is shown in Figure 2. It is composed of an XZ moving platform and a Z-axis rotating platform, and the Z-axis rotating platform can move along the Z-axis and along the X-axis on the XZ moving platform. Axis movement; the SOPTOP LV-S01-DB non-contact portable laser vibrometer in this embodiment is set on the Z-axis rotating platform.

The signal generator is used to send multi-channel random excitation signals according to the instructions of the industrial computer and send them to a plurality of power amplifiers respectively; the signal generator in this embodiment adopts the SG4100ARF signal generator of Tektronix; the multiple The power amplifier is used to amplify multiple excitation signals respectively at the same time, and send the amplified excitation signals to a plurality of exciters respectively; what the power amplifier of this embodiment adopts is the 2732 type power amplifier of BK Company; Two exciters are used to excite vibrations at different positions at the same time, to excite high-end CNC machine tools to make them in different order resonance states; due to the large structure size of high-end CNC machine tools, it is difficult to effectively control them with a hammer or a single exciter Excitation requires the use of multiple exciters to vibrate at different positions at the same time to achieve a good vibration test effect, and in order to obtain the three-dimensional mode shape of the high-end CNC machine tool more accurately, it is also necessary to simultaneously excite vibrations in different directions; What the vibration exciter of this embodiment adopts is the 4824 type vibration exciter of B&K Company; The multiple force transducers are distributed and installed on each excitation point position of the machine tool determined in advance, and are used to obtain the vibration force emitted by a plurality of vibration exciters respectively. The exciting force signal is sent to the data acquisition instrument; the force sensor of the present embodiment adopts the 8230-002 type force sensor of B&K company; the data acquisition instrument is used to collect and record the vibration response signal and the exciting force signal in real time Send to industrial computer; What the data acquisition analyzer of present embodiment adopted is the 3560-D portable multi-channel data acquisition instrument of B&K company, and this data acquisition analyzer is connected with industrial computer by network cable;

The industrial computer is used to control the signal generator to send an excitation signal of a corresponding frequency; according to the structure, shape and size relationship of the machine tool, a wire frame model of a high-end CNC machine tool is established; based on the obtained excitation force signal corresponding to each excitation point and the response signals of each response measuring point, and calculate multiple frequency response functions; use the multi-input multi-response modal parameter identification method to identify the frequency response function, and obtain the natural frequency and modal shape of the high-end CNC machine tool; the obtained The modal vibration shape of the machine tool is simulated, and the animation of the modal vibration shape of the machine tool is obtained. What the industrial computer of this embodiment selects is DELL M6400 high-performance notebook computer.

The high-end CNC machine tool in this embodiment is a vertical machining center produced by Shenyang Machine Tool Factory, its model is VMC 0540d, and its size parameters are shown in Table 1.

Table 1 Dimensional parameters of high-end CNC machine tools (mm)

The method for determining the modal vibration shape of a high-grade numerically controlled machine tool by using the laser scanning-based high-grade numerically controlled machine tool modal vibration test device, as shown in Figure 3, includes the following steps:

Step 1: Adjust the high-end CNC machine tool in this embodiment to the test state: remove the protective equipment of the high-end CNC machine tool, operate the CNC system of the machine tool, adjust the machine tool to the usual working position, and ensure that its sliding parts are in a fixed and locked state; at the same time, Tighten the anchor bolts of the machine tool to ensure that its constraint boundary conditions remain unchanged during the test;

Step 2: According to the structure, shape and size relationship of the machine tool, establish a wire frame model of the high-end CNC machine tool, and determine the response measuring points and the interested vibration directions of each response measuring point on the wire frame model of the high-end CNC machine tool;

According to the size parameters of the high-grade CNC machine tool of the present embodiment shown in Table 1, the wireframe model of the high-grade CNC machine tool is established, the wireframe model of the high-grade CNC machine tool of the present embodiment and the response measuring points determined on the wireframe model, as shown in the figure 4 shown;

Step 3: Select 3 response measuring points from the response measuring points determined in step 2 as excitation points;

Step 4: Distribute and install multiple force sensors at each excitation point;

Step 5: Carry out a pre-judgment experiment of excitation parameters, determine the number, position and direction of the excitation points, and the amplitude of the excitation force of each excitation point;

Step 5-1: In order to obtain good experimental results, a pre-judgment experiment of excitation parameters is required before the formal experiment. Select i response measurement points in the wireframe model of the machine tool, and the number of i satisfies:

i≥λj (1)

In the formula, λ=3~5, the larger the value of λ, the more accurate the prediction result of the excitation parameters, but the longer it takes. Adjust the laser measuring points to the positions of the above i response measuring points, and test and obtain the coherence functions of the i response measuring points respectively relative to each excitation point, and obtain i*j sets of coherence functions;

Step 5-2: For each excitation point, sum and average the coherence functions of the i response measurement points with respect to the excitation point to calculate the lumped coherence function of the excitation point, and obtain j lumped coherence functions ; If most of the coherence coefficient values corresponding to the lumped coherence function are greater than 0.8, it proves that the excitation amplitude, position and excitation direction corresponding to the excitation point meet the requirements of the mode shape test, and the excitation parameters of the excitation point can be used For formal experiments; if most of the coherence coefficients corresponding to the lumped coherence function are less than 0.8, it is necessary to adjust the excitation amplitude, position and excitation direction corresponding to the excitation point;

Step 5-3: Repeat step 5-2 until the pre-judgment of all excitation points is completed, and finally determine the number of excitation points, the position of each excitation point, the excitation direction of each excitation point, and the The magnitude of the exciting force at the vibration point;

As shown in Figure 5, fixed force sensors are installed on the bed, column and spindle box respectively, and the excitation parameter prediction experiment is carried out; according to the excitation parameter prediction experiment results, the number of excitation points is determined to be 3, the location and The directions are +83Y, -292X, +121X respectively, and the average excitation force amplitudes of each exciter are 45N, 87N, 64N,

Step 6: Start the formal experiment, start the signal generator to send a random excitation signal, and amplify the excitation signal through the 2732-type power amplifier and input it to the corresponding 4824-type exciter;

Step 7: Each exciter excites the machine tool under test at the same time with different excitation amplitudes, and at the same time records the excitation force signal corresponding to each excitation point in real time through the 3560-D portable multi-channel data acquisition instrument;

Step 8: Determine the laser scanning rate, use the XZ mobile platform and Z-axis rotating platform, use the SOPTOP LV-S01-DB non-contact portable laser vibrometer to scan point by point along the machine tool response measurement points, and scan along the +X , -X, +Y, -Y four directions, as shown in Figure 5, are scanned row by row or column by column, and the time of the response signal is recorded in real time by the 3560-D portable multi-channel data acquisition instrument during the scanning process. Domain waveform; obtain the vibration scanning time domain signals corresponding to different rows and columns of the wireframe model of the machine tool, and number the vibration scanning signals and scanning directions;

When scanning, the response measuring points blocked by the exciter are not scanned first, but manually tested after the overall scanning is completed;

Step 9: Accurately identify the response signals of different response measuring points corresponding to the vibration scanning signals of different rows and columns in the wireframe model through the sliding window reduction method, as shown in Figure 6;

Step 9-1: Determine the number of sliding windows;

According to the n measuring points contained in the row or column corresponding to the scanning signal, determine the number of sliding windows as n;

Step 9-2: Determine the position of the sliding window;

Assuming that the scanning rate of the laser scanning device is v, the vibration response time to complete a certain row or column is t, and the time corresponding to the first scanning response measurement point is the scanning start time t ₀ , then two adjacent response measurement points The time difference τ of is:

τ=t/(n-1) (2)

At this time, the moment corresponding to the kth measuring point concerned is:

${\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; t</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

Step 9-3: Use the sliding window width determination criterion to set the time width of the sliding window; the sliding window width determination criterion is as follows:

$\mathrm{<span\; class="notranslate">\; \&Delta;t</span>}<span\; class="notranslate">\; \&le;</span>\frac{\mathrm{<span\; class="notranslate">\; d</span>}}{\mathrm{<span\; class="notranslate">\; v</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

In the formula, Δt is the width of the sliding window; d is the diameter of a single response measuring point, generally 0.001-0.005m; v is the scanning rate of the laser scanning device, the unit is m/s;

Step 9-4: extracting the response signal of the response measuring point from the vibration scanning signal;

For k=1, that is, the first response measuring point, take the time t ₀ to t ₀ +Δt of the vibration scanning time domain signal as the response signal of the response measuring point; for k=2,...,n-1, that is, the first From 2 response measuring points to the n-1th response measuring point, take the time t _k -0.5Δt time to t _k +0.5Δt time of the vibration scanning time domain signal as the response signal of the response measuring point; for k=n, that is, For n response measuring points, take the vibration scanning time domain signal from t-Δt time to t time as the response signal of the response measuring point.

For example, as shown in Figure 6, the response signals of three response measuring points are extracted from the vibration scanning signal, where Δt=0.5s, t ₀ =0s, t ₂ =4.45s, t ₃ =8.9s, for k=1, that is For the first response measuring point, take the 0s to 0.5s of the vibration scanning time domain signal as the response signal of the response measuring point; for k=2, that is, the second response measuring point, take the 4.2s to 4.7 of the vibration scanning time domain signal s is the response signal of the response measurement point; for k=3, that is, the third response measurement point, the 8.4s to 8.9s of the vibration scanning time domain signal is taken as the response signal of the response measurement point.

Step 10: Based on the obtained excitation force signals corresponding to each excitation point and the response signals of each response measurement point, multiple frequency response functions are calculated, as shown in Figure 7, and the calculation formula is as follows:

$\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

In the formula, X(f) is the frequency spectrum of the response signal, and F(f) is the frequency spectrum of the excitation force signal.

Step 11: Use the multi-input multi-response modal parameter identification method to identify the frequency response function. The identification results in the first 100 Hz are shown in Table 2, and the natural frequency, damping ratio and modal shape of the high-end CNC machine tool are obtained, and the obtained machine tool The modal vibration shape is simulated to obtain the machine tool modal vibration animation. The third-order vibration shape is shown in Figure 8. The dark color in the figure represents the relatively large vibration amplitude of the part where it is located, and the light color represents the vibration amplitude of the part where it is located. Relatively small.

Table 2 The modal parameters of each order of the whole machine within 100Hz and the basic characteristics of the mode shape

Modal order Frequency (Hz) Damping ratio (%) Mode shape description 1 20.7 1.42 The whole machine tool shakes forward and backward along Y 2 40.9 1.55 The whole machine tool shakes left and right along the X direction 3 52 1.54 Overall torsion of the machine tool 4 55.8 2.48 headstock nod

.

Claims (10)

1. based on a high-grade, digitally controlled machine tools Mode Shape proving installation for laser scanning, it is characterized in that: comprising: signal generator, multiple power amplifier, multiple vibrator, multiple force snesor, laser scanning device, data collecting instrument, industrial computer;

The input end of described signal generator is connected with the output terminal of described industrial computer; The output terminal of described signal generator is connected with the input end of described multiple power amplifier simultaneously; Be as separate connection one to one between described multiple power amplifier and described multiple vibrator and between described multiple vibrator and described multiple force snesor; Described multiple force snesor distributing installation is on each impacting point position of predetermined lathe; The output terminal of each force snesor all connects the input end of described data collecting instrument; Another input end of described data collecting instrument is connected with the output terminal of the laser vibration measurer in described laser scanning device; Meanwhile, data collecting instrument is also interconnected with industrial computer;

Described laser scanning device, for obtaining the vibration response signal of the difference response measuring point of high-grade, digitally controlled machine tools and sending to data collecting instrument; Described laser scanning device comprises further:

Laser vibration measurer, be arranged on the automatic mechanism of laser vibration measurer position, for passing through laser vibration measurer position automatic mechanism, point by point scanning is carried out to the response measuring point of high-grade, digitally controlled machine tools, obtains the vibration response signal of the difference response measuring point of high-grade, digitally controlled machine tools and send to data collecting instrument;

Laser vibration measurer position automatic mechanism, for automatically adjusting position on this mechanism's Z axis of the position of laser vibration measurer in this mechanism's X-axis, laser vibration measurer and single-point laser vialog around the angle that Z axis rotates in this mechanism, this mechanism can also be needed to move to desired location according to test by user;

Described industrial computer is used for the pumping signal that control signal generator sends corresponding frequencies; According to structure, the shape and size relation of lathe, set up the wire-frame model of high-grade, digitally controlled machine tools; The response signal of the exciting force signal corresponding based on each obtained impacting point and each response measuring point, calculates multiple frequency response function; Utilize multi input multiple response Modal Parameters Identification identification frequency response function, obtain natural frequency and the Machine Tool Modal vibration shape of high-grade, digitally controlled machine tools; The Machine Tool Modal vibration shape obtained is emulated, obtains Machine Tool Modal vibration shape animation.

2. the high-grade, digitally controlled machine tools Mode Shape proving installation based on laser scanning according to claim 1, it is characterized in that: described signal generator is used for the instruction according to industrial computer, send multichannel random excitation signal and send to multiple power amplifier respectively; Described multiple power amplifier is used for amplifying multichannel pumping signal respectively simultaneously, and the pumping signal after amplifying is sent to multiple vibrator respectively.

3. the high-grade, digitally controlled machine tools Mode Shape proving installation based on laser scanning according to claim 1, is characterized in that: described multiple vibrator is used for being excited at the same time in different positions, and excitation high-grade, digitally controlled machine tools make it vibrate.

4. the high-grade, digitally controlled machine tools Mode Shape proving installation based on laser scanning according to claim 1, is characterized in that: described multiple force snesor, for obtaining exciting force signal that multiple vibrator sends respectively and sending to data collecting instrument.

5. the high-grade, digitally controlled machine tools Mode Shape proving installation based on laser scanning according to claim 1, is characterized in that: described data collecting instrument is used for Real-time Collection and record vibration response signal and exciting force signal and sends industrial computer to.

6. the high-grade, digitally controlled machine tools Mode Shape proving installation based on laser scanning according to claim 1, it is characterized in that: described laser vibration measurer position automatic mechanism is combined by XZ mobile platform and Z axis rotation platform and forms, and Z axis rotation platform can move along Z axis and move along X-axis on XZ mobile platform.

7. the high-grade, digitally controlled machine tools Mode Shape proving installation based on laser scanning according to claim 6, is characterized in that: described laser vibration measurer is arranged on Z axis rotation platform.

8. adopt the method for the high-grade, digitally controlled machine tools Mode Shape proving installation based on laser scanning according to claim 1 test high-grade, digitally controlled machine tools Mode Shape, it is characterized in that: comprise the steps:

Step 1: high-grade, digitally controlled machine tools are adjusted to test mode;

Step 2: according to structure, the shape and size relation of lathe, set up the wire-frame model of high-grade, digitally controlled machine tools, and on the wire-frame model of these high-grade, digitally controlled machine tools, determine the direction of vibration interested responding measuring point and each response measuring point;

Step 3: select j to respond measuring point as impacting point from step 2 in determined response measuring point;

Step 4: by multiple force snesor distributing installation on each impacting point position;

Step 5: the wire-frame model utilizing high-grade, digitally controlled machine tools, carries out excitation parameter anticipation experiment, determines the quantity of impacting point, the position of impacting point and direction of excitation, and the amplitude of each impacting point exciting force;

Step 6: start formally to test, enabling signal generator sends random excitation signal, and input to corresponding vibrator after pumping signal being amplified by power amplifier;

Step 7: each vibrator encourages tested lathe with different excitation amplitudes simultaneously, passes through exciting force signal corresponding to each impacting point of data collecting instrument real time record simultaneously;

Step 8: the speed determining laser scanning, use laser scanning device, point by point scanning is carried out along lathe response measuring point, respectively along+X ,-X ,+Y during scanning,-Y four direction, carry out according to the mode of lining by line scan or scan by column, by the time domain waveform of data collecting instrument real time record response signal in scanning process, obtain lathe wire-frame model at different rows and oscillating scanning time-domain signal corresponding to different lines;

Step 9: by the response signal of the difference response measuring point corresponding to the oscillating scanning signal of different rows and different lines in sliding window "flop-out" method accurate recognition wire-frame model;

Step 10: the response signal of the exciting force signal corresponding based on each obtained impacting point and each response measuring point, calculates multiple frequency response function;

Step 11: utilize multi input multiple response Modal Parameters Identification identification frequency response function, obtain natural frequency and the Machine Tool Modal vibration shape of high-grade, digitally controlled machine tools, and the Machine Tool Modal vibration shape obtained is emulated, obtain Machine Tool Modal vibration shape animation.

9. the method for the test of the high-grade, digitally controlled machine tools Mode Shape proving installation based on laser scanning high-grade, digitally controlled machine tools Mode Shape according to claim 8, is characterized in that: described step 5 comprises the steps:

Step 5-1: choose i response measuring point in the wire-frame model of lathe, the number of i meets:

i≥λj (1)

Wherein λ=3 ~ 5; Regulate laser measuring point to above-mentioned i response point position, and test obtain i response measuring point respectively relative to the coherence function of each impacting point respectively, obtains i*j group coherence function;

Step 5-2: for each impacting point, to carry out i response measuring point suing for peace the lump coherence function being averaged and calculating impacting point relative to the coherence function of impacting point respectively, obtains j lump coherence function; If coefficient of coherence overwhelming majority value corresponding to lump coherence function is greater than 0.8, then proves that excitation amplitude that this impacting point is corresponding, position and direction of excitation meet the requirement of vibration mode test, can be used for formal experiment; If the coefficient of coherence overwhelming majority value that lump coherence function is corresponding is less than 0.8, then need to adjust excitation amplitude corresponding to this impacting point, position and direction of excitation;

Step 5-3: repeat step 5-2, until complete the anticipation of whole impacting point, and finally determines the direction of excitation of the quantity of impacting point, the position of each impacting point and each impacting point, and the amplitude of each impacting point exciting force.

10. the method for the test of the high-grade, digitally controlled machine tools Mode Shape proving installation based on laser scanning high-grade, digitally controlled machine tools Mode Shape according to claim 8, is characterized in that: described step 9 comprises the steps:

Step 9-1: determine sliding window number;

The row corresponding according to sweep signal or n the measuring point comprised in arranging, determine that the number of sliding window is n;

Step 9-2: determine sliding window position;

The sweep speed supposing laser scanning device is v, and the vibratory response time completing certain row or certain row is t, and moment corresponding to scanning the 1st response measuring point is scanning initial time t ₀, then the mistiming τ of adjacent two response measuring points is:

τ＝t/(n-1) (2)

Now paid close attention to a kth measuring point (k=1,2 ..., n) the corresponding moment is:

$t_k=t_0+\frac{t}{(n-1)}(k-1)---\left(3\right)$

Step 9-3: utilize sliding window width determination criterion, the time width of sliding window is set; Described sliding window width determination criterion is as follows:

$\mathrm{\&Delta;t}\&le;\frac{d}{v}---\left(4\right)$

In formula, Δ t is sliding window width; D is the diameter of single response measuring point, is generally 0.001 ~ 0.005m; V is the sweep speed of laser scanning device, and unit is m/s;

Step 9-4: the response signal extracting response measuring point from oscillating scanning signal;

For k=1, namely the 1st response measuring point, gets the t of oscillating scanning time-domain signal ₀moment is to t ₀+ Δ t is the response signal of response measuring point; For k=2 ..., n-1, namely the 2nd response measuring point is to (n-1)th response measuring point, gets the t of oscillating scanning time-domain signal _k-0.5 Δ t is to t _k+ 0.5 Δ t is the response signal of response measuring point; For k=n, i.e. the n-th response measuring point, the t-Δ t of getting oscillating scanning time-domain signal is the response signal of response measuring point to t.