CN1584495A - Linear movement reference device of cylindricity instrument with laser penetrance and reflection monitoring compensation - Google Patents

Abstract

A superprecise linear cylindricity standard apparatus of major-minor dual track structure in monitoring and compensating type based on laser transparent and reflecting combination is disclosed by the present invention according to action rule of reference motion error of track linear motion to measured result of cylindricity measuring device with utilizing laser beam as physical reference.

Description

Laser transmission and anti-combination monitoring compensation type cylindricity instrument Linear motion reference device

technical field

The invention relates to a linear motion reference device of a laser transmission and reflection combined monitoring compensation type cylindricity instrument, which belongs to the technical field of surface shape measurement and is especially suitable for an ultra-precision cylindricity measurement device.

Background technique

The continuous development of modern industry, especially the cutting-edge industrial technology of national defense, puts forward higher and higher requirements for the measurement of the surface profile of the rotary workpiece. For example, in the process of ultra-precision machining and measurement, the roundness tolerance of the aerostatic spindle, which is usually used as ultra-precision equipment such as ultra-precision machine tools, lithography machine turntables, laser direct writing equipment and ultra-precision test turntables, has reached 0.05 after grinding. μm, the tolerance of cylindricity and coaxiality reaches 0.2μm/100mm～0.5μm/100mm; the tolerance of cylindricity and coaxiality of the rotor shaft of inertial devices widely used in aerospace, aviation and other fields is 0.3μm/100mm～0.8 μm/100mm, while the next-generation inertial device cylindricity and coaxiality tolerance will reach 0.1μm/100mm ~ 0.5μm/100mm. The technical indicators listed above need to be accurately measured, which puts forward higher requirements for the measurement accuracy of the existing cylindricity measuring device, such as the roundness measurement uncertainty should reach 0.005μm, the cylindricity and coaxiality measurement should The degree of certainty should reach 0.1μm/100mm.

At present, the existing cylindricity measuring device generally adopts the device structure as shown in FIG. 1 , which is mainly composed of a base 23 , a vertical main rail motion sleeve 19 , a rotary table 24 , a measuring sensor 25 and a workpiece 26 to be measured. The vertical main rail sleeve 19 is used as its linear motion measurement benchmark. Due to the limitation of processing technology and use state, when the guide rail motion system is used vertically, the initial horizontal state of its processing detection is changed, and it is difficult to maintain its original manufacturing and Detection accuracy, especially in the case of high motion accuracy requirements and large motion stroke, is particularly prominent. Because the vertical guide rail loses its own gravity when it is in the horizontal processing and detection state, its vertical state often shows an overall bending. At present, the reference accuracy of the linear motion of the guide rail can only reach the temporary limit level of about 0.1μm/100mm. It has become It is the biggest obstacle restricting the further improvement of the measuring accuracy of the cylindricity measuring device. There are two reasons for this: First, the absolute accuracy level of the linear motion benchmark is an order of magnitude lower than that of the rotary motion benchmark. If the contribution of the error separation technology to the rotary motion accuracy is considered, the linear motion benchmark accuracy level is about two orders of magnitude lower ; Second, the error of the linear motion reference has no periodic reproducibility, and it is difficult to reduce the linear motion error by means of error separation technology. Therefore, how to reduce the linear motion error of the sensor has become the key to improving the measurement accuracy of the cylindricity measurement device.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the linear motion reference technology of the existing cylindricity measuring device, integrate the laser transmission and reflection combined monitoring and compensation technology, the main and auxiliary double guide rail straight travel technology and the isolated anti-interference drive technology, and use the laser beam as the The physical benchmark, according to the law of action of the guide rail linear motion reference motion error on the measurement results of the cylindricity measurement device, provides an ultra-precision cylindricity linear motion reference device based on the laser transmission and reverse combined monitoring compensation type main and auxiliary double guide rail structure.

The technical solution of the present invention is: a laser transmission and reflection combined monitoring and compensation type cylindricity instrument linear motion reference device, including the main rail column 16 and the main rail sleeve 19, which is characterized in that the device also includes:

The laser beam 10 parallel to the movement direction of the main guide sleeve 19, the semi-transparent and semi-reflective plane mirror 6 placed in the direction along the laser beam 10, the laser transmission beam centered on the main guide sleeve to detect the offset of the main guide sleeve Monitoring system 4. A laser transflective monitoring system for guide rail motion error composed of a main guide rail sleeve angle drift photoelectric detection system 13 placed in the direction of the reflected beam of the semi-transparent and semi-reflective plane mirror 6;

The auxiliary guide rail column 17 arranged parallel to the main guide rail column 16, the auxiliary guide rail cover 18 is arranged on it, and the flexible connecting belt 15 connects the main guide rail cover 19 and the auxiliary guide rail cover 18 through the pulley mechanism 14 to form a main and auxiliary double guide rail straight running system;

DC drive motor 22, precision lead screw 21, decoupling driven screw nut connection mechanism 20 connected with auxiliary guide rail cover 18, indicating grating 8 fixed on auxiliary guide rail cover 18, and auxiliary guide rail column 17 arranged in parallel An isolated anti-jamming drive and height measuring system composed of the height measuring scale grating ruler 9.

In order to ensure the original basic accuracy of the main guide rail system, eliminate the medium and high-frequency disturbances to the straight guide rail caused by the drive system during the movement process, and protect it from the interference of the drive system, vertical grating measurement system and other links, the present invention adopts Double guide rail structure and isolated drive technology for main and auxiliary guide rails. The double guide rail structure makes the main guide rail motion system and the auxiliary guide rail motion system in a quasi-balanced state, and the micro-drive force can realize stable driving, reduce the driving load of the motor, and make the main and auxiliary motion guide rail systems in a stable state. At the same time, the motor drives through contact with the sphere without radial force, and only produces Z-direction thrust. The driving link acts on the auxiliary guide rail, and the vertical grating measurement system also acts on the auxiliary guide rail. connection to minimize interference with the main rail sleeve 19. Since the drive system is isolated from the main rail system, the high-frequency vibration in the micro-motor is filtered through the air film of the auxiliary rail, so that only low-frequency components exist in the disturbance to the main rail sleeve, so that the random component of the motion error of the main rail system is maximized degree of suppression, and lay the premise and foundation for the monitoring and compensation of its motion error. The double guide rail structure and the isolated drive technology of the main and auxiliary guide rails of the cylindricity measuring device are one of the invention points that distinguish the present invention from the prior art.

As mentioned above, the main rail column 16 of the cylindricity measuring device loses its own gravity when it is in the horizontal processing and testing state, so its vertical state is often bent as a whole, and it is also disturbed by various random quantities. The present invention analyzes the action mechanism of the motion error of the linear motion guide rail of the cylindricity measuring device, and obtains that θ _x and ε _y are fundamental to the linear motion error of the single measuring head cylindricity instrument. To this end, a combined monitoring and compensation technology based on laser transmission and reflection is proposed. This technology monitors the angular swing and translation in a specific direction of the guide rail of the cylindricity measurement device, and then uses the model to solve the compensation of the linear motion reference motion error. The laser monitoring and compensation technology for the linear motion error of the cylindricity measuring device based on the combination of laser transmission and reflection is the second invention point that distinguishes the present invention from the prior art.

After adopting the above technology, not only the systematic error of the motion guide rail can be monitored and compensated in real time, but also its random motion error can be monitored and compensated in real time, so that the linear motion accuracy of the cylindricity measuring device can reach 30nm/100mm; 40nm/300mm; 50nm/500mm.

Description of drawings:

Figure 1 is a schematic diagram of the existing cylindricity sensor structure

Figure 2 is a schematic diagram of the structure of the linear motion reference device of the laser transmission-reflection combined monitoring compensation type cylindricity instrument

Figure 3 is a schematic diagram of linear motion error

Figure 4 is a schematic diagram of laser transmission and reflection combined monitoring and compensation technology

Figure 5 is a composition diagram of the drift feedback control fiber alignment system

Figure 6 is the experimental data diagram of the horizontal drift test

Figure 7 is the experimental data diagram of the vertical drift test

In the figure: 1 laser, 2 single-mode fiber collimation system, 3 micro-displacement centering table, 4 centering monitoring system, 5 micro-displacement monitoring sensor, 6 semi-transparent and semi-anti-plane mirror, 7 quarter-wave plate, 8 Indicating grating, 9 scale grating, 10 laser beam, 11 polarization beam splitter PBS, 12 laser direction stabilization device, 13 angle drift photoelectric detection system, 14 pulley mechanism, 15 flexible connecting belt, 16 main rail column, 17 auxiliary guide rail column, 18 pair of guide rail sets, 19 main guide rail sets, 20 lead screw nut connection mechanism, 21 precision lead screw, 22 DC drive motor, 23 device base, 24 rotary table, 25 measuring sensor, 26 workpiece under test, 27 beam expander , 28 fiber optic coupler, 29 collimating mirror, 30 beam two-dimensional translation optical mirror mechanism, 31 space corner mirror mechanism, 32 computer, 33 beam splitter BS1, 34 beam splitter BS2, 35 four-quadrant detector QPD1 system, 36 focusing Objective lens, 37 four-quadrant detector QPD2 system, 38 horizontal curve of single-mode fiber after collimation, 39 horizontal curve of drift feedback control after collimation, 40 vertical curve of single-mode fiber after collimation, 41 drift feedback control Straight back vertical direction curve.

Detailed ways

The structure and working principle of the linear motion reference device of the compensation type cylindricity meter based on the combination of laser transmission and reflection monitoring of the present invention will be described in detail below in conjunction with the accompanying drawings:

The device of the present invention includes a main and auxiliary double guide rail straight-track system, a laser transflective monitoring system for guide rail movement errors, an isolated anti-interference drive and height measuring system.

As shown in Figure 2, the main and auxiliary dual guide rail straight-line system includes a main guide rail column 16 and an auxiliary guide rail column 17 perpendicular to the device seat 23, a main guide rail cover 19 is arranged on the main guide rail column 16, and an auxiliary guide rail cover 18 is arranged on the auxiliary guide rail column 17 , the flexible connection belt 15 connects the main guide rail column 16, the main guide rail cover 19, the secondary guide rail column 17 and the secondary guide rail cover 18 through the pulley mechanism 14.

The guide rail motion error laser transflective monitoring system includes a highly directionally stable laser 1 that generates a reference laser beam, a single-mode fiber collimation system 2, a laser direction stabilizing device 12, and a polarization beam splitter 11 placed in the direction of the output beam of the laser direction stabilizing device. The laser beam 10 parallel to the z-direction of the movement direction of the main rail sleeve 19, the quarter wave plate 7 placed in the direction along the laser beam 10, the semi-transparent and semi-reflective plane mirror 6, and the detection guide rail sleeve placed on the main rail sleeve Offset laser transmission beam center monitoring system 4, a main rail cover angle drift photoelectric detection system 13 placed on the reflected beam direction of the semi-transparent and semi-reflective plane mirror 6, wherein the beam center monitoring system 4, y-direction cylindricity sensor The micro-displacement monitoring sensor 5 is connected to the micro-displacement centering workbench 3 for the centering of the measuring direction.

The isolated anti-interference drive and height measurement system includes a DC drive motor 22, a precision lead screw 21, a decoupling drive type lead screw nut connection mechanism 20, an indicating grating 8, and a height measuring scale grating ruler 9. The decoupling driven screw nut connection mechanism 20 is connected with the auxiliary guide rail cover 18, and is used to drive the auxiliary guide rail cover 18 to move along the Z direction, indicating that the grating 8 is fixed on the auxiliary guide rail cover 18, and the grating 9 is parallel to the auxiliary guide rail column 17 Setting, the indicating grating 8 and the scale grating 9 form a height measuring device, which is used to measure the height of the main rail sleeve 19 in the z direction of the movement direction.

The working process of the device of the present invention is shown in Figure 2. The laser light emitted by the highly directional stable laser 1 is primary collimated by the single-mode fiber collimation system 2, and then emitted by the laser directional stabilizing device 12 into a laser beam with high directional stability. 10. The laser beam is used as a physical reference beam and incident on the beam-splitting surface of the polarization beam splitter PBS 11, and the reflected beam reflected by the PBS 11 and parallel to the z-direction of the guide rail movement direction passes through the quarter-wave plate 7 and irradiates on the solid surface. The semi-transparent and semi-anti-plane mirror 6 that is connected on the moving guide rail, the reflected light reflected by the semi-transparent and semi-anti-plane mirror 6 returns to the quarter-wave plate 7 and passes through the beam splitting surface of the PBS 11 to irradiate the angle above the PBS11. Drift photoelectric detection system 13 is used to measure the angular pendulum variation θ _x of the main rail sleeve around the x-axis direction; the light beam transmitted by the semi-transparent and semi-anti-plane mirror 6 is irradiated to the main rail sleeve 19. The laser centering monitoring system 4 is based on The micro-displacement centering workbench 3 with piezoelectric ceramic PZT drive technology drives the laser centering monitoring system to align with the laser beam, and its displacement is monitored by the y-direction centering micro-displacement monitoring sensor 5. The y-direction translation is obtained by the y-direction component of the laser centering monitoring system 4 and the y-direction micro-displacement monitoring sensor 5, so that the translation ε _y of the main moving rail sleeve 19 along the y-direction can be obtained. Knowing the angular pendulum variation θ _x of the main rail sleeve 19 around the direction perpendicular to the paper surface and the translation ε _y along the y direction, and then solving the model, the influence values of ε _y and θ _x on the cylindricity measurement results are calculated from the cylinder Finally, the detection and compensation of the linear motion error of the ultra-precision cylindricity measuring device can be realized.

During the movement of the guide rail, the DC drive motor 22 drives the precision screw 21 to rotate, and drives the screw nut connection mechanism 20 to move upward. The decoupling driven screw nut connection mechanism 20 is connected with the auxiliary guide rail cover 18 for driving the auxiliary guide rail cover 18 Movement along the Z direction, due to the use of the main and auxiliary double guide rail straight-line system and the linear motion reference of the main guide rail and the balance guide rail of the auxiliary guide rail are in a quasi-balanced state, so that the use of micro power can achieve balanced drive and reduce the driving load of the motor , so that the moving body is in a quasi-stationary state. At the same time, the motor drive adopts the contact between the sphere and the lower plane of the auxiliary guide rail sleeve 18, and only the Z-direction thrust is generated. The driving link acts on the auxiliary guide rail. The vertical grating measurement system also acts on the auxiliary guide rail. The "flexible" steel wire connection minimizes the interference to the main rail sleeve 19, so that the interference has minimal influence on the measuring sensor 25 of the cylindricity meter.

Theoretical basis and principle of laser transmission and reflection combined monitoring and compensation for straight line motion error of cylindricity meter:

As shown in FIG. 3 , the initial position coordinate system of the main rail sleeve 19 is set as Ox _o y _o z _o , where O is the coordinate origin and z _o is the direction of motion. When the main rail sleeve 19 arrives at a certain position from the initial position along the z _o direction, the coordinate system of the object becomes O′-xyz. Due to the influence of the motion error of the object, the coordinate origin O leaves the ideal motion direction z _o axis and reaches O′ (ε _x , ε _y , ε _z +v _t ) point. The linear motion error of the object during the motion can be decomposed into the translational motion errors ε _x and ε _y generated in the directions of the x _o axis and the y _o axis, and the rotation errors around the three coordinate axes x _o , y _o and z _o respectively θ _x , θ _y and θ _z and the positioning error ε _z along the z _o axis motion errors.

Select any point r on the main rail sleeve 19 as a reference point, and set the initial position coordinates before the movement as r(r _xo , r _yo , r _zo ), due to the movement errors of the main rail sleeve 19 θ _x , θ _y , θ _z , Influenced by ε _x , ε _y and ε _z , the arrival point in the coordinate system O′-xyz is r′(r _x , r _y , r _z ), and its coordinate position is relative to the initial coordinate system Ox _o y _o z _o The relationship is equivalent to the three rotations of the coordinate system O′-xyz around the x, y and z coordinate axes and the translation along the z axis, that is, first rotate a -θ _x angle around the x axis to obtain the intermediate coordinate system O′-xy ₁ z ₁ , then rotate around the y-axis by a -θ _y angle to get the second coordinate system O′-x ₁ y ₁ z _o , then rotate around the z-axis by a -θ _z angle to get the coordinate system O′-x _o y _o z _o , and then translate along the z _o axis to obtain the coordinate system Ox _o y _o z _o ,

When the coordinate system produces translation of ε _x and ε _y in the direction of x _o axis and _{y o} axis, and produces translation of ε _z + v _t term along the direction of z _o axis, that is, when the coordinate origin moves from O′ to O, the vector r′ is in Ox _o y _o z _o coordinate system can be expressed as:

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; xo</span>}}\\ {\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; the\; yo</span>}}\\ {\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; zo</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{ccc}\mathrm{<span\; class="notranslate">\; 1</span>}& {<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}& {\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}\\ {\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}& \mathrm{<span\; class="notranslate">\; 1</span>}& {<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}\\ {<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}& {\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}& \mathrm{<span\; class="notranslate">\; 1</span>}\end{array}\right]\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}\\ {\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}\\ {\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}\end{array}\right]<span\; class="notranslate">\; +</span>\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}\\ {\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}\\ {\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}\end{array}\right]<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

In the ideal state without motion error, point r should reach the ideal position (r _x , _ry , r _z +v _t ) after moving, then the deviation between the motion error and the ideal position is:

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; \&Delta;r</span>}}_{\mathrm{<span\; class="notranslate">\; xo</span>}}\\ {\mathrm{<span\; class="notranslate">\; \&Delta;r</span>}}_{\mathrm{<span\; class="notranslate">\; the\; yo</span>}}\\ {\mathrm{<span\; class="notranslate">\; \&Delta;r</span>}}_{\mathrm{<span\; class="notranslate">\; zo</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; xo</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}\\ {\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; the\; yo</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}\\ {\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; zo</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{ccc}\mathrm{<span\; class="notranslate">\; 0</span>}& <span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}& {\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}\\ {\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}& \mathrm{<span\; class="notranslate">\; 0</span>}& {<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}\\ {<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}& {\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}& \mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right]\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}\\ {\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}\\ {\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}\end{array}\right]<span\; class="notranslate">\; +</span>\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}\\ {\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}\\ {\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}\end{array}\right]<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

As far as the linear motion is concerned, the positioning error ε _z in the z _o direction is directly measured by the displacement sensor. In the linear motion error of the guide rail, this error may not be considered, that is, if ε _z = 0, then the above formula can be simplified as:

There are five independent variables ε _x , ε _y , θ _x , θ _y and θ _z in formula (3). If these five variables are obtained, five independent equations must be established simultaneously, that is, three different monitoring points, detect their deviations from the ideal state respectively, and substitute them into Equation 3 to obtain the values of the linear motion error.

According to the above motion error model, three laser beams parallel to each other and in the same direction as the guide rail are used as monitoring benchmarks, and three points r ₁ , r ₂ and r ₃ are selected as monitoring points on the moving object on the guide rail, and three four-quadrants are used to detect The device QPD detects the respective dot position status. At the initial position, make the centers of the three laser beams coincide with the centers of the three QPDs, so that when the moving guide rail moves along the Z axis, the three QPDs can respectively measure their translational deviations from the x and y axes Δr _xoi , Δr _yoi i=1, 2, 3, according to the formula (3):

Select r ₁ point as the origin of the reference coordinates, that is, r _x1 = r _y1 = r _z1 = 0, the error of the main rail sleeve 19 can be described as: the translation error ε _x , ε _y of point r ₁ on the x and y coordinates and the r Rotation angle errors θ _x , θ _y and θ _z of _1- point rotation, at this time: r _x1 ＝ry _y1 ＝r _z1 ＝0

Solve equation (5) to get:

Then the motion error state of any point Q(x, y, z) on the main rail can be expressed as:

where ε _x , ε _y , θ _x , θ _y and θ _z are determined by Equation 6.

In the cylindricity measuring device, the sensor is usually arranged as a single probe method as shown in FIG. The measurement sensitive direction of the single-probe cylindricity measurement sensor is set to y, and the influence of the guide rail motion error on the sensor measurement can be obtained by formula (7):

Δy=ε _y -xθ _z +zθ _x (8)

When the optical path is arranged, if x=0, z=0, that is, when the extension line of the sensor measurement line intersects with the monitoring point of the moving guide rail, the influence of the guide rail rotation angle error on the sensor measurement value can be completely eliminated. However, in general, due to the difference in the measurement position of the workpiece and the installation position of the sensor, z≠0, then:

Δy = ε _y + zθ _x (9)

In the detection of guide rail movement error separation, the three-beam laser reference guide rail straightness monitoring method can theoretically completely separate five kinds of motion errors of the moving guide rail, θ _x , θ _y , θ _z , ε _x , ε _y , but the premise is that the three beams The reference beam is kept strictly parallel to the moving direction of the guide rail, the initial positions of the centers of the receiving surfaces of the three QPDs should coincide with the centers of the three beams and be perpendicular to the moving direction, the directional stability of the three laser beams is excellent, and the detection sensitivity of the QPD is high. From a technical point of view, it is very difficult in actual adjustment to satisfy the above conditions, especially to satisfy that the three reference beams are strictly parallel to the moving direction of the guide rail. It can be seen from formula 9 that for the linear motion reference monitoring system under the specific use conditions of the linear reference guide rail of the cylindricity instrument, it is not necessary to completely separate and detect the five kinds of motion errors of the motion guide rail, but only need to separate and detect θ _x and ε _y in real time, that is, It can completely separate and compensate the influence of the linear motion reference motion error on the measurement accuracy of the cylindricity measuring device. Aiming at the special need of cylindricity, a laser-based transmissive and trans-cylindricity guideway error detection method is proposed here, which is used to detect the moving body errors of the main guideway sleeve θ _x and ε _y in real time, and obtain the distance between θ _x and ε _y After the dynamic error is modeled and solved, the sensor error caused by the motion guide error θ _x and ε _y can be obtained, and removed from the sensor measurement results in real time, and then the high-precision real-time monitoring and compensation of the cylindricity guide rail motion error is realized.

Based on the above analysis, the present invention proposes a laser beam detection and compensation method and technology for monitoring the rectilinear motion error of the cylindricity measuring device based on the transflective combination for the specific application status of the linear motion reference of the cylindricity measuring device. The principle of beam transmission and anti-combination monitoring and compensation technology is shown in 4. When the optical path is laid out, the distance between the semi-transparent and semi-anti-plane mirror 6 and the laser centering detection system 4 should be minimized. The micro-displacement centering workbench 3 is connected with the main rail sleeve 19, and the centering monitoring system 4 for detecting the translation amount in the y direction is located on it, and controls the micro-displacement drive system so that the center of the QPD is always aligned with the energy center of the reference laser beam 10, and the micro-displacement The driven displacement is detected by the high-precision micro-displacement monitoring sensor 5, and the sum of its magnitude and the y-direction offset of the QPD corresponds to the y-direction translation during the movement of the guide rail sleeve. According to the principle of optical levers, the larger the size of the H direction, the higher the detection sensitivity of the angular pendulum monitoring system. If the structural size of the H direction is limited, the angle sensor can also be designed as a critical angle sensor based on the principle of internal reflection, which increases the detection sensitivity. The ability to measure the angular swing of the guide rail. The height of the H dimension can be measured by the altimeter grating system in Figure 2.

The specific principle of laser transmission and anti-combination monitoring and compensation technology is shown in Figure 4. The highly stable laser beam after direction stabilization treatment is used as a physical beam, and it is incident on the beam splitting surface of the polarization beam splitter PBS 11 and then transmitted through a quarter of the beam. A wave plate 7 is irradiated on the semi-transparent and semi-reflective plane mirror 6 fixed on the moving guide rail, and the reflected light reflected by the mirror returns to the quarter wave plate 7 and irradiates the corner through the light splitting surface of the PBS 11. Drift photoelectric detection system 13 is used to measure the angular pendulum variation of main rail cover 19 around the x direction perpendicular to the paper surface, as shown in Figure 4a; the transmitted light is irradiated on the four-quadrant silicon photocell centering detection system 4, It is used to measure the translation amount of the main guide sleeve 19 along the y direction, as shown in FIG. 4b. When the optical path is arranged, H can be much larger than h, so that the influence of the angular drift on the level drift can be minimized. At the same time, a large H can make the change of Δx caused by the angular swing large, which can increase the detection sensitivity of the angular swing .

At present, the detection accuracy of the optical lever angle detection system can reach the order of 10 ^-8 rad, and the detection accuracy of the translation amount can reach within 10nm, which can fully meet the accuracy requirements of the laser detection of the linear motion error of the benchmark cylindricity meter. The drift of the laser beam itself is generally on the order of 10 ^-4 ~ 10 ^-6 rad, which is far from meeting the collimation accuracy requirements of the reference beam which should reach the order of 10 ^-7 rad. In order to meet the requirement of high-directional stability reference laser beam in the high-precision laser monitoring of the linear motion error of the reference cylindricity meter, in this invention, a fiber collimation system with feedback control of stable laser beam drift is proposed.

Its composition principle is shown in Figure 5. The beam emitted by the laser 1 enters the single-mode fiber 2 through the beam expander 27 and the fiber coupler 28. The single-mode fiber 2 and the collimating mirror 29 perform primary collimation and become parallel light to the beam two-dimensionally. Translating light mirror mechanism 30, the light emitted by translation light mirror mechanism 30 is directed to beam splitter BS1 33 and beam splitter BS2 34 through space corner mirror mechanism 31, and the light reflected by BS1 is irradiated on the center of four-quadrant detector system QPD1 35 for The amount of flat drift of the detection beam, the light reflected by BS2 is focused on the center of the four-quadrant detector system QPD2 37 through the focusing objective lens 36, and QPD2 is located on the focal plane of the focusing objective lens 36 for detecting the angular drift of the beam. During the collimation process, the computer 32 firstly controls the two-dimensional driving mechanism to rotate the angle mirror 31 according to the spatial two-dimensional angular drift component of the laser beam detected by QPD1 to rotate the laser beam in the direction of reducing the angular drift to reduce the laser beam. Angular drift of the beam. The value detected by QPD2 is mainly reflected in the flat drift of the laser beam, which can be suppressed by controlling the two-dimensional translation of the optical mirror mechanism 30 of the beam. In the beam drift amount feedback control collimation system, the QPD1 and the beam space drift amount control mechanism 30 constitute a beam space drift amount feedback control system to control the beam space drift amount in real time. The QPD2 and the light-passing space angle mirror mechanism 31 constitute a feedback control system for the space drift of the light beam, which controls the space angle drift of the light beam in real time. In the beam real-time feedback control collimation process, the space level drift and angular drift of the laser beam are separated and detected and form real-time feedback control respectively, which reduces the mutual coupling in the laser beam control process and improves the beam space drift. Control accuracy and collimation efficiency.

In the collimation system, the QPD detector is selected from the S1557 model produced by HAMAMATSU Corporation of Japan, and the line width of the crossed separation line is 10 μm. In order to reduce the impact of the crossed dividing lines on the accuracy of the detection circuit and improve the resolution of the system, the laser is selected from the 1145P model produced by JDS Uniphase in the United States, and its output power is as high as 35mW. The single-mode optical fiber adopts the single-mode polarization-maintaining optical fiber transmission system of model 05FDS207 produced by the American MELLES GRIOT company. It integrates the coupling system, optical fiber and collimation system. The efficiency of the outgoing beam after coupling is as high as 65%, and the diameter of the outgoing beam is The roundness of the φ0.7mm light spot is better than 95%, and the stability of the exit point is better than 1μrad/℃. The piezoelectric ceramic driver is a scalable piezoelectric ceramic driver from the Chengdu Institute of Optoelectronics, Chinese Academy of Sciences. ×10 ^-8 rad, the effective adjustment range is up to 20×10 ^-6 rad. The translation control mirror has a resolution of 3nm and a control range of 2000nm. The focal length of the focusing lens is f=150mm. The signal acquisition and control card adopts Advantech PCL813B. At a collimation distance of about 500 mm, the collimation effect of the collimated reference beam in the vertical and horizontal directions was tested. The test time is 900s, and a total of 40,000 points are collected. The experimental data of the horizontal drift test is shown in Figure 6, and the vertical drift test is shown in Figure 7.

After the laser beam is collimated by the single-mode fiber, as shown by the curve 38 in Figure 6, the collimation accuracy of the outgoing beam reaches about 0.9×10 ^-6 rad in the horizontal direction; as shown by the curve 40 in Figure 7, the vertical direction reaches about Collimation accuracy of 0.8×10 ^-6 rad. The beam is collimated by a single-mode fiber and then controlled by drift feedback, as shown by curve 39 in Figure 6, the horizontal direction reaches a collimation accuracy of about 0.6×10 ^-7 rad; as shown by curve 41 in Figure 7, the vertical The direction achieves a collimation accuracy of about 0.5×10 ^-7 rad. It can be seen from experiments that after beam drift feedback control and compensation, the beam drift is obviously suppressed, and the collimation effect is improved by an order of magnitude.

Claims (4)

1. A laser thoroughly, the anti-monitoring compensation linear movement reference device of cylindricity instrument that makes up, comprise main guide rail column (16), main guide rail cover (19), it is characterized in that this device also comprises:

   The laser-transmitting light beam that be parallel to the laser beam (10) of main guide rail cover (19) direction of motion, be placed on along the semi-transparent semi-reflecting level crossing (6) on laser beam (10) direction successively, is placed on the detection main guide rail cover side-play amount that main guide rail puts to heart monitoring system (4), be placed on the saturating anti-monitoring system of guide rail movement error laser that the main guide rail cover angle shift photodetector system (13) on semi-transparent semi-reflecting level crossing (6) the folded light beam direction constitutes;

   The secondary guide rail upright columns (17) that be arranged in parallel with main guide rail column (16), secondary guide rail sleeve (18), flexible link belt (15) are set on it are connected the two guide rail craspedodrome systems of major-minor that main guide rail cover (19) and secondary guide rail sleeve (18) constitute by pulley mechanism (14);

   Direct-drive motor (22), precision lead screw (21), the decoupling zero drive-type feed screw nut bindiny mechanism (20) that links with secondary guide rail sleeve (18), be cemented in indication grating (8) on the secondary guide rail sleeve (18), isolated anti-interference driving and height-finding system that the high scale grating of the survey chi (9) that be arranged in parallel with secondary guide rail upright columns (17) constitutes.
2. 2. device according to claim 1 is characterized in that said laser-transmitting light beam is provided with the cylindricity instrument sensor measurement direction that drives based on piezoelectric ceramics (PZT) (y to) micrometric displacement to heart monitoring system (4) and looks for middle worktable (3) and y micrometric displacement monitoring sensor (5) in looking for.
3. 3. device according to claim 1 and 2 is characterized in that also comprising the system that produces the reference laser light beam that this system comprises high direction stable laser (1), single-mode fiber colimated light system (2), laser direction stabilising arrangement (12).
4. 4. device according to claim 1 is characterized in that also comprising the polarization spectroscope (10) that is placed on laser direction stabilising arrangement (12) the outgoing beam direction, is placed on quarter-wave plate (7) semi-transparent, half-reflecting mirror (6) top.

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