WO2018098656A1

WO2018098656A1 - Laser vibration detector-based machine cutting real-time vibration monitoring device and vibration detection method

Info

Publication number: WO2018098656A1
Application number: PCT/CN2016/107889
Authority: WO
Inventors: 李鹤; 李晖; 于浩
Original assignee: 东北大学
Priority date: 2016-11-30
Filing date: 2016-11-30
Publication date: 2018-06-07

Abstract

A laser vibration detector (3)-based machine (1) cutting real-time vibration monitoring device and a vibration detection method, wherein the device comprises a laser vibration detector (3), a data collector and an industrial computer, the laser vibration detector (3) being connected to the industrial computer by means of the data collector. In order to block foreign matters such as a cutting liquid from affecting the laser vibration detector (3), the device is provided with optical path protectors at the laser vibration detector (3) and at points to be tested, wherein the optical path protector comprises a plurality of optical path protection sleeves (4) and an optical path converter (5) used for connecting the bent optical path protection sleeves (4); the optical path protection sleeves (4) may be mutually spliced, and may be coupled with the laser vibration detector (3), so as to allow a laser beam emitted from the laser vibration detector (3) to be projected to any location of the machine (1), thereby obtaining a vibration response at any location while the machine (1) is in cutting vibration.

Description

Machine tool cutting vibration real-time monitoring device and vibration measuring method based on laser vibrometer

Technical field:

The invention belongs to the technical field of vibration testing, and particularly relates to a real-time monitoring device for detecting vibration of a machine tool based on a laser vibrometer and a vibration measuring method.

Background technique:

Machine tool cutting vibration testing is an important part of the machine tool development process. It is of great significance for understanding the weak links of the machine tool, structural optimization design, fault diagnosis and cutting stability prediction. Because the laser vibrometer has the advantages of non-contact non-destructive testing, and the vibration measurement distance is adjustable, it can also achieve vibration testing in high-speed rotation, high-frequency, high-temperature environment, etc., so many machine tool enterprises hope to apply it to machine tool development and production process. In particular, it is used in real-time vibration monitoring of key components such as machine tool spindles and tool tips. However, due to the large size of the traditional single-point laser vibrometer, it is inconvenient to move, and it can not meet the requirements of real-time testing of cutting vibration of machine tools with large structure and complex surface shape, and the cutting fluid, metal shavings and equipment itself will be laser The light path causes a lot of interference, and there is no suitable solution in the industry. Although well-known domestic machine tool companies are striving to build their own performance testing capabilities, including test standards, test procedures, test instruments and various parts test benches, most of the performance tests are only at the factory inspection level of machine tool performance. Research testing techniques to improve machine performance, especially online testing techniques, are far from adequately addressed.

Summary of the invention:

In order to solve the problems existing in the prior art, the present invention provides a real-time detecting device for detecting cutting vibration of a machine tool based on a laser vibrometer, and a detecting method thereof, the device comprising a laser vibrometer, a data collecting instrument and an industrial computer; The instrument is connected to the industrial computer through the data acquisition instrument. In order to isolate the influence of the foreign matter such as the cutting fluid on the laser vibrometer, the real-time detecting device for the cutting vibration of the machine tool based on the laser vibrometer is used in the laser vibrometer The measuring point to be tested is provided with an optical path protector, the optical path protector comprising a plurality of optical path protection tubes and an optical path converter for connecting the converted optical path protection tubes; the optical path protection tubes can be spliced to each other and can be combined with the laser for vibration measurement The instrument is matched so that the laser beam emitted by the laser vibrometer can be projected to any position of the machine structure, thereby obtaining the vibration response at any position when the machine is cutting vibration.

The optical path converter includes a bent outer casing and a mirror disposed in the outer casing for changing a laser light path, and the outer casing of the optical path converter can be spliced with the optical path protection cylinder.

Due to the complicated structure of the machine tool, in order to improve the flexibility of the optical path protector, the optical path protection cylinder is composed of a plurality of straight sleeves and can be expanded and contracted.

Due to the different optical path directions in different situations, in order to more flexibly set the optical path protector, the optical path converter comprises several curved outer casings with different turning angles.

In order to more accurately and accurately determine the working state of the machine tool, the optical path protector further includes a photometric head, the rear end of the photometric head is provided with a hollow optical channel, and the rear end can be connected with the optical path protection tube, the front end Set to have a conversion angle Degree of commutation mirror.

The optical path protection tube is provided with a scale, the scale has a ruler, and the ruler can be disposed at two ends of the optical path protection tube, one end of the scale is fixedly disposed on the ruler seat, and the other end can slide relative to the ruler seat, and the optical path can be conveniently measured. The size of the protective cylinder.

The optical path protector further includes a rotating base, one end of the rotating base can be connected to the optical path protection tube, and the other end can be connected to the optical path converter, and the rotating seat is provided with a rotating angle disk and a pointer.

As a further improvement of the rotating base, a bevel gear train capable of adjusting the angle of the rotating base is provided in the rotating base, and the bevel gear train is driven by a stepping motor. It is also possible to adjust the angle of the swivel seat by means of a worm gear, wherein the worm is driven by a manual knob.

The optical path protector also includes a horizontal angle disc that can be placed on the machine tool.

The machine tool cutting vibration real-time detecting device further comprises a vibrometer protection box, wherein the vibrometer protection box is provided with a strong magnet, which can be arranged on the machine tool through a strong magnet.

Step 1: Adjust the machine to be tested to the normal working state, and install the laser vibrometer through the vibrometer protection box on the upper end of the machine headstock;

Step 2: Install the optical path protector at the lower end of the spindle box of the machine tool;

Step 3: Adjust the position and angle of the optical measuring head, the optical path protection tube and the reversing mirror respectively, to ensure that the laser beam emitted by the laser vibrometer can be projected to a certain measuring point of the machine to be tested and record their respective Corresponding rotation angle disc, position or angle corresponding to the horizontal angle disc pointer and the position of the scale on the optical path protection cylinder, so that the next measurement position can be quickly adjusted to the next measurement position;

Step 4: Perform a idling vibration test of the machine tool to evaluate whether the connection form of the optical path protector meets the requirements of real-time vibration measurement. If yes, proceed to step 5, if not, repeat step 4 until it meets the requirements;

Step 5: Carry out a formal experiment, input different parameters such as speed, feed rate, cutting thickness and depth of cut in the CNC machine system. Under complicated cutting conditions, obtain a certain measuring point of the machine tool through the laser vibrometer. The position of the vibration response, and the time domain waveform of the vibration signal is recorded in real time by the data acquisition instrument, and then the spectrum of the vibration response is obtained by the spectrum analysis method.

The evaluation method for evaluating whether the connection form of the optical path protector satisfies the requirements of real-time vibration measurement described in step 4 is as follows:

Step 4-1: Firstly, the laser beam emitted by the laser vibrometer is projected onto the tool nose point of the machine tool, and the rotation speed is respectively set to the low, medium and high three-speed idle speed gear position, and the machine tool is started to idle;

Step 4-2: Under any idle speed position, test the vibration response of a certain measuring point position, test each speed position three times, and record its time domain waveform through the data acquisition instrument, and then obtain the spectrum analysis method. The spectrum of its vibration response;

Step 4-3: Compare the fundamental frequency, 2 times frequency and 3 times frequency amplitude of the vibration spectrum obtained by the three tests respectively. If the fundamental frequency A ₀ , A' ₀ , A'' ₀ , 2 times the frequency A obtained by the three tests ₂ , A' ₂ , A'' ₂ and 3 octave amplitudes A ₃ , A' ₃ , A" ₃ satisfy the following formula, which proves that the test repeatability index value S is better, and the optical path protector used is connected. The form can meet the requirements of real-time vibration measurement. If the following formula is not satisfied, the connection form of the optical path protector (for example, the support member and the viscoelastic vibration-damping material) needs to be adjusted until it meets the requirements.

S=(A ₂ +A' ₂ +A'' ₂ )/(A ₀ +A' ₀ +A'' ₀ )+(A ₃ +A' ₃ +A" ₃ )/(A ₀ +A' ₀ _{+ A '' 0) ≤1%} ,

Where S is the test repeatability index value, A ₀ , A′ ₀ , A′′ ₀ are the fundamental frequency amplitudes of the vibration response spectrum obtained by the first, second and third tests, respectively; A ₂ , a _{_'2,} a _"2 for the first, second and third vibration test response obtained amplitude frequency spectrum _{_{2; a 3, a' 3,}} a" 3 for the first, second 3 times the amplitude of the vibration response spectrum obtained by the second and third tests;

Step 4-4: Obtain the test repeatability index value S at the low, medium, and high three-speed idle speeds respectively. If it can satisfy the formula (1), proceed to the next step. If not, continue to adjust the optical path protector. Connection form until it meets the requirements;

BRIEF DESCRIPTION OF THE DRAWINGS:

Figure 1 is a schematic view showing the structure of an embodiment of the present invention;

Figure 2 is a schematic structural view of the optical path converter of Figure 1;

3 is a schematic structural view of the optical path protection cylinder of FIG. 1;

Figure 4 is a schematic structural view of the horizontal angle disk of Figure 1;

Figure 5 is a schematic structural view of the photometric head of Figure 1;

Among them: 1-machine tool, 2-tool, 3-laser vibrometer, 4-light path protection tube, 5-ray path adapter, 6-horizon angle plate, 7-shell, 8-mirror, 9-scale, 10 - Photometric head, 11-commutation mirror, 12-foot seat.

detailed description:

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. As shown in FIG. 1 to FIG. 4, a real-time detecting device for detecting cutting vibration of a machine tool based on a laser vibrometer, and a detecting method thereof, the device comprising the laser vibrometer 3, a plurality of force sensors, vibration exciters, data acquisition devices, and industrial computers; the laser vibrometer 3 and the force sensors are connected to an industrial computer through a data acquisition device, and the vibration exciter and the force sensor can be disposed on the machine tool 1 In order to isolate the influence of foreign matter such as cutting fluid on the laser vibrometer 3, the machine tool cutting vibration real-time detecting device of the laser vibrometer 3 of the present invention is provided with optical path protection between the laser vibrometer 3 and the tool 2 to be tested. The optical path protector includes a plurality of optical path protection cylinders 4 and an optical path converter 5 for connecting the converted optical path protection cylinders 4; the optical path protection cylinders 4 can be spliced to each other and can be combined with the laser vibrometer 3 In cooperation, the optical path converter 5 comprises a curved outer casing 7 and a mirror 8 arranged in the outer casing 7 for changing the laser beam path, and the outer casing 7 of the optical path converter can be spliced with the optical path protection cylinder 4.

Due to the complicated structure of the machine tool, in order to improve the flexibility of the optical path protector, the optical path protection cylinder 4 is composed of a plurality of straight sleeves and is expandable and contractible.

In order to more flexibly and accurately determine the working state of the machine tool, the optical path protector further includes a photometric head 10, the rear end of the photometric head 10 is provided with a hollow optical channel, and the rear end can be associated with the optical path protection cylinder 4 Connected, the front end is provided with a diverting mirror 11 capable of converting an angle.

A scale 9 is disposed on the optical path protection cylinder 4, and the scale 9 is provided with a ruler 12, and the ruler 12 can be disposed at two ends of the optical path protection cylinder 4. One end of the scale 9 is fixedly disposed on the ruler 12, and the other end can be opposite to the ruler The seat 12 slides, and the length of the optical path protection cylinder 4 can be conveniently measured.

The optical path protector further includes a rotating base, one end of the rotating base can be connected to the optical path protection cylinder 4, and the other end can be connected to the optical path converter, and the rotating seat is provided with a rotating angle disk and a pointer.

The optical path protector further comprises a horizontal angle disk 6 that can be placed on the machine tool 1.

The method for detecting a real-time detecting device for cutting vibration of a machine tool based on the laser vibrometer comprises the following steps:

Step 1: Adjust the machine tool 1 to be tested to the normal working state, and install the laser vibrometer 3 through the vibrometer protection box on the upper end of the spindle box of the machine tool 1;

Step 2: Install the optical path protector at the lower end position of the spindle head of the machine tool 1;

Step 3: Adjust the position and angle of the optical measuring head 10, the optical path protection cylinder 4 and the reversing mirror 11 respectively, and ensure that the laser beam emitted by the laser vibrometer 3 can be projected to a certain measuring point position of the machine tool to be tested. And recording their respective corresponding rotation angle discs, the position or angle corresponding to the pointer of the horizontal angle disc 6 and the position of the scale 9 on the optical path protection cylinder 4, so as to be able to quickly adjust to the last measurement position in the next test;

Step 4: Perform a idling vibration test of the machine tool 1 to evaluate whether the connection form of the optical path protector satisfies the requirements of real-time vibration measurement. If yes, proceed to step 5, if not, repeat step 4 until it meets the requirements;

Step 5: Carry out a formal experiment, input different parameters such as speed, feed rate, cutting thickness and depth of cut in the CNC machine system. Under complicated cutting conditions, obtain a certain measuring point of the machine tool through the laser vibrometer. The vibration response of the position, and the time domain waveform of the vibration signal is recorded in real time by the data acquisition instrument, and then the vibration is obtained by the spectrum analysis method. The spectrum of the dynamic response.

Step 4-1: Firstly, the laser beam emitted by the laser vibrometer is projected onto the tool nose point of the machine tool, and the rotation speed is respectively set to the low, medium and high three-speed idle speed gear position, and the machine tool 1 is started to idle;

S=(A ₂ +A' ₂ +A'' ₂ )/(A ₀ +A' ₀ +A'' ₀ )+(A ₃ +A' ₃ +A" ₃ )/(A ₀ +A' ₀ +A'' ₀ ) ≤ 1%,

Where S is the test repeatability index value, A ₀ , A′ ₀ , A′′ ₀ are the fundamental frequency amplitudes of the vibration response spectrum obtained by the first, second and third tests, respectively; A ₂ , A' ₂ , A'' ₂ are the 2 times amplitude of the vibration response spectrum obtained by the first, second and third tests; A ₃ , A' ₃ , A′ ₃ are the first and the first 3 times the amplitude of the vibration response spectrum obtained by the second and third tests;

Claims

A real-time detecting device for cutting vibration of a machine tool based on a laser vibrometer, comprising: a laser vibrometer, a data acquisition instrument and an industrial computer; the laser vibrometer is connected to an industrial computer through a data acquisition instrument for isolation cutting The influence of liquid and other foreign matter on the laser vibrometer, the real-time detecting device for cutting vibration of the machine tool based on the laser vibrometer, the device is provided with an optical path protector at the laser vibrometer and the measuring point to be tested, the optical path The protector comprises a plurality of optical path protection cylinders and optical path converters for connecting the converted optical path protection cylinders; the optical path protection cylinders can be spliced to each other and can cooperate with the laser vibrometer to enable the laser beam emitted by the laser vibrometer It can be projected to any position of the machine structure to obtain the vibration response at any position when the machine is cutting vibration.
The laser vibration vibrometer-based real-time detecting device for cutting vibration of a machine tool according to claim 1, wherein the optical path converter comprises a bent outer casing and a mirror disposed in the outer casing for changing a laser light path. The outer casing of the optical path converter can be spliced with the optical path protection cylinder.
The laser vibration vibrometer-based real-time detecting device for cutting vibration of a machine tool according to claim 1, wherein the optical path protection cylinder is formed of a plurality of straight sleeves and is expandable and contractable in order to improve flexibility of the optical path protector.
A real-time detecting device for cutting vibration of a machine tool based on a laser vibrometer according to claim 2, wherein the optical path converter comprises a plurality of curved outer casings having different turning angles.
The apparatus for detecting a cutting vibration of a machine tool based on a laser vibrometer according to claim 1, wherein the optical path protector further comprises a photometric head, and a rear end of the photometric head is provided with a hollow optical channel. The rear end can be connected to the optical path protection cylinder, and the front end is provided with a commutating mirror capable of converting the angle.
The real-time detecting device for cutting vibration of a machine tool based on a laser vibrometer according to claim 1, wherein the optical path protection tube is provided with a scale, the scale has a ruler, and the ruler can be disposed at both ends of the optical path protection tube. One end of the scale is fixedly disposed on the ruler seat, and the other end can slide relative to the ruler seat, which can conveniently measure the size of the optical path protection cylinder.
The apparatus for detecting a cutting vibration of a machine tool based on a laser vibrometer according to claim 6, wherein the optical path protector further comprises a rotating base, one end of the rotating base being connectable with the optical path protection cylinder, and the other end The connection can be connected to the optical path converter, and the rotary angle plate and the pointer are arranged on the rotary base.
The real-time detecting device for cutting vibration of a machine tool based on a laser vibrometer according to claim 7, wherein a bevel gear system capable of adjusting an angle of the rotating base is provided in the rotating base, and the bevel gear system is stepped by stepping Driven by the motor. It is also possible to adjust the angle of the swivel seat by means of a worm gear, wherein the worm is driven by a manual knob.
The laser vibration vibrometer-based real-time detecting device for cutting vibration of a machine tool according to claim 1, wherein the optical path protector further comprises a horizontal angle disc that can be disposed on the machine tool.
The real-time detecting device for cutting vibration of a machine tool based on a laser vibrometer according to claim 1, wherein the real-time detecting device for cutting vibration of the machine tool further comprises a vibrometer protection box, and the vibrometer protection box is provided with Strong magnets that can be placed on the machine with strong magnets.
A vibration measuring method for real-time detecting device for cutting vibration of a machine tool based on a laser vibrometer according to claim 1, characterized in that it comprises the following steps:

Step 1: Adjust the machine to be tested to the normal working state, and install the laser vibrometer through the vibrometer protection box on the upper end of the machine headstock;

Step 2: Install the optical path protector at the lower end of the spindle box of the machine tool;

Step 3: Adjust the position and angle of the optical measuring head, the optical path protection tube and the reversing mirror respectively, to ensure that the laser beam emitted by the laser vibrometer can be projected to a certain measuring point of the machine to be tested and record their respective Corresponding rotation angle disc, position or angle corresponding to the horizontal angle disc pointer and the position of the scale on the optical path protection cylinder, so that the next measurement position can be quickly adjusted to the next measurement position;

Step 4: Perform a idling vibration test of the machine tool to evaluate whether the connection form of the optical path protector meets the requirements of real-time vibration measurement. If yes, proceed to step 5, if not, repeat step 4 until it meets the requirements;

Step 5: Carry out a formal experiment, input different parameters such as speed, feed rate, cutting thickness and depth of cut in the CNC machine system. Under complicated cutting conditions, obtain a certain measuring point of the machine tool through the laser vibrometer. The position of the vibration response, and the time domain waveform of the vibration signal is recorded in real time by the data acquisition instrument, and then the spectrum of the vibration response is obtained by the spectrum analysis method.

The evaluation method for evaluating whether the connection form of the optical path protector satisfies the requirements of real-time vibration measurement described in step 4 is as follows:

Step 4-1: Firstly, the laser beam emitted by the laser vibrometer is projected onto the tool nose point of the machine tool, and the rotation speed is respectively set to the low, medium and high three-speed idle speed gear position, and the machine tool is started to idle;

Step 4-2: Under any idle speed position, test the vibration response of a certain measuring point position, test each speed position three times, and record its time domain waveform through the data acquisition instrument, and then obtain the spectrum analysis method. The spectrum of its vibration response;

Step 4-3: Compare the fundamental frequency, 2 times frequency, and 3 frequency doubling amplitude of the vibration spectrum obtained by the three tests respectively. If the fundamental frequency A 0 , A′ 0 , A′′ 0 , 2 octave A 2 obtained by the three tests are obtained , A' 2 , A′′ 2 and 3 octave amplitudes A 3 , A′ 3 , A′′ 3 satisfy the following formula, which proves that the test repeatability index value S is better, and the connection mode of the optical path protector used can be To meet the requirements of real-time vibration measurement, if the following formula is not satisfied, it is necessary to adjust the connection form of the optical path protector (for example, increase or decrease the support member and the viscoelastic vibration-damping material) until it meets the requirements.

S=(A 2 +A' 2 +A" 2 )/(A 0 +A' 0 +A" 0 )+(A 3 +A' 3 +A" 3 )/(A 0 +A' 0 +A " 0 " ≤ 1%,

Where S is the test repeatability index value, A 0 , A′ 0 , A′′ 0 are the fundamental frequency amplitudes of the vibration response spectrum obtained by the first, second and third tests, respectively; A 2 , a '2, a "2 for the first, second and third vibration test response obtained amplitude frequency spectrum 2; a 3, a' 3, a" 3 for the first, second And the 3 times amplitude of the vibration response spectrum obtained in the third test;

Step 4-4: Obtain the test repeatability index value S at the low, medium, and high three-speed idle speeds respectively. If it can satisfy the formula (1), proceed to the next step. If not, continue to adjust the optical path protector. Connection form until it meets the requirements;