Machine tool guideway five-degree-of-freedom error measuring device and method with light beam drift compensation

Abstract

The application discloses a machine tool guide rail five-freedom error measuring device and method for compensating beam drift, which comprises a fixed end composed of a laser, a quarter-wave plate, a first beam splitter, a first mirror, a second beam splitter, a third beam splitter, a fourth beam splitter, a first four-quadrant detector, a first convex lens, a first position sensitive detector, a second mirror, a fifth beam splitter, a second four-quadrant detector, a second convex lens, a second position sensitive detector, a third convex lens and a third position sensitive detector, and a moving end composed of a first corner cube reflector, a half-transmission half-reflection mirror, a second corner cube reflector, a polarization beam splitter, a first photodiode and a second photodiode.

Description

Technical Field

[0001] This invention belongs to the field of machine tool error measurement, and in particular to a device and method for simultaneously measuring beam drift and five-degree-of-freedom errors of machine tool guideways. Background Technology

[0002] High-end equipment manufacturing is a strategic high ground that determines my country's comprehensive competitiveness, the backbone of the modern industrial system, and an engine for industrial transformation and upgrading. Large CNC machine tools, as the "mother machines" of high-end equipment manufacturing, are widely used in key areas such as national defense equipment, aerospace, transportation, and hydropower, directly impacting my country's manufacturing level and influence in the international division of labor. CNC machine tools are listed as one of the strategic battlegrounds for China's manufacturing industry, and their importance is self-evident. Linear guideways are a crucial component of large CNC machine tools, and the machining accuracy of machine tools heavily depends on the positioning accuracy of the guideways. Online measurement of guideway geometric errors is a vital means to ensure and improve guideway positioning accuracy. By monitoring the operating status and positioning accuracy of machine tool guideways in real time, compensation for guideway errors can be achieved in conjunction with the CNC system, thereby improving the machining accuracy of the machine tool. This method is economical and effective, reducing the manufacturing and maintenance costs of high-precision machine tool guideways, while also improving the accuracy of a large number of existing aging machine tool guideways in my country, which is of great significance. According to the relevant content of the ISO 230 standard, if any axial movement of a machine tool is considered as a rigid body motion, then the machine tool guideway has six degrees of freedom geometric errors, including positioning error, pitch angle error, yaw angle error, roll angle error, and horizontal and vertical straightness errors. Among these, the positioning error can usually be measured by the machine tool's built-in linear encoder or rotary encoder, achieving sub-micron accuracy while exhibiting good stability, meeting the requirements of machine tool machining. Therefore, researching and implementing the measurement of the five degrees of freedom errors of the machine tool guideway, excluding positioning error, is crucial for improving the machining accuracy of machine tools.

[0003] Currently, traditional methods for measuring geometric errors of machine tool guideways, such as laser interferometers and laser tracking interferometers, can only be used offline. These methods are complex to install and debug, have long measurement cycles, cannot measure errors introduced during machining, and their compensation accuracy is limited by the repeatability and stability of the machine tool. The laser multi-degree-of-freedom measurement method integrates the measuring device onto the machine tool, enabling simultaneous acquisition of multiple geometric errors during guideway operation. The measurement of pitch and yaw angles is based on the laser self-collimation principle, the measurement of horizontal and vertical straightness is based on the laser collimation principle, and the measurement of roll angle is based on the dual-collimated beam method. This method has advantages such as high efficiency, low cost, and ease of integration, making real-time measurement and compensation feasible. However, several problems remain to be solved: firstly, laser beam drift introduces measurement errors, which increase with distance; secondly, the accuracy of roll angle measurement largely depends on the parallelism of the two parallel beams, which is severely affected by the environment. Therefore, researching a device and method for simultaneously measuring five-degree-of-freedom errors of machine tool guideways with beam drift and non-parallelism compensation is of great significance. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a device for simultaneously measuring five degrees of freedom errors of machine tool guideways. This device is compact, low-cost, and can be integrated into CNC machine tools for online measurement. It also provides a method for simultaneously measuring five degrees of freedom errors of machine tool guideways, enabling simultaneous measurement of all errors except positioning errors, significantly improving the measurement efficiency of machine tool errors and avoiding errors introduced by environmental changes during measurement. Furthermore, it provides a beam drift compensation method that can compensate for beam drift in real time during the measurement of geometric errors of machine tool guideways, improving the accuracy and robustness of the five degrees of freedom error measurement process. Finally, it provides a dual-beam non-parallelism compensation method that enables real-time compensation of the parallelism of two collimated beams, greatly improving the measurement accuracy and robustness of the roll angle.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A five-degree-of-freedom error measurement device for machine tool guideways with beam drift compensation includes a laser, a quarter-wave plate, a first beam splitter, a first reflecting mirror, a second beam splitter, a third beam splitter, a first pyramidal reflecting mirror, a semi-transparent mirror, a fourth beam splitter, a first quadrant detector, a first convex lens, a first position-sensitive detector, a second reflecting mirror, a second pyramidal reflecting mirror, a fifth beam splitter, a second quadrant detector, a second convex lens, a second position-sensitive detector, a third convex lens, a third position-sensitive detector, a polarizing beam splitter, a first photodiode, and a second photodiode; wherein the laser, quarter-wave plate, and first beam splitter... The fixed end consists of a first reflecting mirror, a second beam splitter, a third beam splitter, a fourth beam splitter, a first quadrant detector, a first convex lens, a first position-sensitive detector, a second reflecting mirror, a fifth beam splitter, a second quadrant detector, a second convex lens, a second position-sensitive detector, a third convex lens, and a third position-sensitive detector; the movable end consists of a first pyramidal reflecting mirror, a semi-transparent mirror, a second pyramidal reflecting mirror, a polarizing beam splitter, a first photodiode, and a second photodiode; when the error measuring device is in use, the fixed end is fixedly installed at a fixed position on the axis to be measured of the CNC machine tool, and the movable end is installed on the slide of the axis to be measured of the CNC machine tool and moves accordingly;

[0007] The collimated laser emitted by the laser is linearly polarized light, which is converted into circularly polarized light by a quarter-wave plate. The beam emitted by the quarter-wave plate is split into two beams by the first beam splitter. The transmitted beam from the first beam splitter is reflected by the first mirror and then split into two beams by the second beam splitter. The transmitted beam from the second beam splitter passes through the third beam splitter and the first pyramidal mirror in sequence and is then split into two beams by a semi-transparent mirror. The transmitted beam from the semi-transparent mirror passes through the fourth beam splitter and is split into two beams again. One beam is received by the first four-quadrant detector to measure the horizontal and vertical straightness errors, and the other beam passes through the first convex lens and is received by the first position-sensitive detector to measure the angular drift of the beam emitted from the right side of the fixed end.

[0008] The reflected beam from the second beam splitter passes sequentially through the second reflecting mirror and the second pyramidal reflecting mirror before being split into two beams by the fifth beam splitter. One beam is received by the second quadrant detector to measure horizontal and vertical straightness errors, while the other beam passes through the second convex lens and is received by the second position-sensitive detector to measure the angular drift of the beam emitted from the left side of the fixed end. The roll angle is calculated from the vertical straightness error measured by the first and second quadrant detectors. The reflected beam from the third beam splitter passes through the third convex lens and is received by the third position-sensitive detector to measure pitch and yaw angle errors. The reflected light from the first beam splitter is split into two beams by a polarizing beam splitter, which are received by the first and second photodiodes, respectively, to compensate for the non-parallelism of the double-collimated beams on the right and left sides of the fixed end.

[0009] Furthermore, the fast axis of the quarter-wave plate makes an angle of 45° with the polarization direction of the outgoing beam.

[0010] This invention also provides a method for measuring the five-degree-of-freedom error of a machine tool guideway with beam drift compensation. The five-degree-of-freedom error measurement of the machine tool guideway includes the measurement of errors in pitch angle, yaw angle, roll angle, horizontal straightness, and vertical straightness, and includes the following steps:

[0011] a. To achieve pitch and yaw angle measurement, when the mobile terminal has a pitch angle ε x At that time, the light spot on the third position sensitive detector moves Δy along the y-axis. 20 The focal length of the third convex lens is f. 19 Pitch angle ε x Expressed using equation (1):

[0012]

[0013] When the mobile device has a yaw angle ε y At that time, the light spot on the third position sensitive detector moves Δz along the z-axis. 20 The focal length of the third convex lens is f. 19 yaw angle ε y Expressed using equation (2):

[0014]

[0015] b. To achieve horizontal and vertical straightness measurement, when the mobile end has a horizontal straightness δ x At that time, the light spot on the first quadrant detector moves Δx along the x-axis. 10 Horizontal straightness δ x Expressed using equation (3):

[0016]

[0017] When the vertical straightness δ exists at the first four quadrant detector of the mobile terminal y At that time, the light spot on the first four-quadrant detector moves Δy along the y-axis. 10 Horizontal straightness δ y Expressed using equation (4):

[0018]

[0019] c. Implement roll angle measurement, when there is vertical straightness δ at the first four-quadrant detector of the mobile end. y And there is a roll angle ε z At that time, the light spot on the first four-quadrant detector moves Δy along the y-axis. 10 The light spot on the second and fourth quadrant detector moves Δy along the y-axis. 16The distance between the first quadrant detector and the second quadrant detector is d, and the roll angle is ε. z Expressed using equation (5):

[0020]

[0021] The present invention also provides a method for measuring and compensating for optical path angle drift, comprising:

[0022] a. The y-axis of the beam emitted from the right side of the fixed end experiences an angular drift θ. yr At that time, the light spot on the first position-sensitive detector moves Δz along the z-axis. 12 The focal length of the first convex lens is f. 11 Laser angle drift θ yr Expressed using equation (6):

[0023]

[0024] Compensated yaw angle ε y Expressed using equation (7):

[0025]

[0026] The yaw angle present on the mobile device is ε y The light spot on the third position sensitive detector moves a distance Δz along the z-axis. 20 The focal length of the third convex lens is f. 19 ;

[0027] Considering laser angle drift θ yr When considering the effect on horizontal straightness, assuming the laser rotates around the center of the third beam splitter and ignoring the component distance inside the fixed end, the distance between the fixed end and the moving end is l. Therefore, the compensated horizontal straightness δ... x Expressed using equation (8):

[0028]

[0029] δ x For the horizontal straightness of the mobile device, Δx 10 This represents the distance the light spot on the first four-quadrant detector moves along the x-axis.

[0030] b. The x-axis of the beam emitted from the right side of the fixed end experiences an angular drift θ. xr At that time, the light spot on the first position sensitive detector moves Δy along the y-axis. 12 The focal length of the first convex lens is f. 11 Laser angle drift θ xr Expressed using equation (9):

[0031]

[0032] Compensated pitch angle ε x Expressed using equation (10):

[0033]

[0034] The tilt angle on the mobile device is ε x The light spot on the third position sensitive detector moves Δy along the y-axis. 20 ;

[0035] Considering laser angle drift θ xr When considering the effect on vertical straightness, it is assumed that the laser rotates around the center of the third beam splitter, and the distance between components inside the fixed end is ignored. Therefore, the distance between the fixed end and the moving end is l, and the compensated vertical straightness δ is... y Expressed by equation (11):

[0036]

[0037] The vertical straightness at the first four quadrant detector of the mobile terminal is δ y The light spot on the first quadrant detector moves Δy along the y-axis. 10 ;

[0038] c. When the x-axis of the beam emitted from the left side of the fixed end shifts by an angle θ xl At that time, the light spot on the second position-sensitive detector moves Δy along the y-axis. 18 The focal length of the second convex lens is f. 17 Laser angle drift θ xl Expressed using equation (12):

[0039]

[0040] Ignoring the component distances within the fixed end, the distance between the fixed end and the moving end is l, and the distance between the first quadrant detector and the second quadrant detector is d. Therefore, the compensated roll angle ε... z Expressed using equation (13):

[0041]

[0042] The light spot on the second-fourth quadrant detector moves a distance Δy along the y-axis. 16 .

[0043] This invention also provides a method for compensating for non-parallelism of two beams, where the angle between the emitted beam on the right side and the emitted beam on the left side of the fixed end is ε. d At that time, it is calculated from the voltage signals received by the first photodiode and the second photodiode. The voltages of the first photodiode and the second photodiode are I1 and I2, respectively. Then ε dExpressed using equation (14):

[0044]

[0045] Ignoring the component distances within the fixed end, the distance between the fixed end and the moving end is l, and the distance between the first quadrant detector and the second quadrant detector is d. From geometric relationships, the introduced roll angle measurement error ε... zd Expressed using equation (15):

[0046]

[0047] Then the compensated roll angle ε z "This can be expressed using equation (16):"

[0048]

[0049] Δy 16 Δy represents the distance the light spot on the second-fourth quadrant detector moves along the y-axis. 18 Δy represents the distance the light spot on the second position-sensitive detector moves along the y-axis. 10 Δy represents the distance the light spot on the first four-quadrant detector moves along the y-axis; 12 f is the distance the light spot on the first position-sensitive detector moves along the y-axis; 17 f is the focal length of the second convex lens. 11 This is the focal length of the first convex lens.

[0050] Compared with the prior art, the beneficial effects of the technical solution of the present invention are as follows:

[0051] (1) The machine tool guideway five-degree-of-freedom error simultaneous measurement device provided by this invention uses a double collimated beam for measurement, which is reflected and then received by the sensor, thus doubling the resolution of the five-degree-of-freedom error measurement. Compared with traditional methods, which require increasing the distance between the two beams to improve resolution when measuring roll angle, this device has a compact structure, is easy to integrate and install with the machine tool guideway, uses fewer optical components, and can complete the measurement using a semiconductor laser, resulting in lower cost.

[0052] (2) The machine tool guideway five-degree-of-freedom error simultaneous measurement method provided by the present invention can simultaneously measure all errors of the machine tool guideway except for positioning error, which greatly improves the measurement efficiency of machine tool error and avoids errors introduced by environmental changes during the measurement process, thereby improving the accuracy and reliability of machine tool error measurement.

[0053] (3) The beam drift compensation method provided by the present invention can compensate for beam drift in real time when measuring the geometric error of machine tool guide rail, improve the accuracy and robustness of the five-degree-of-freedom error measurement process, and make it adaptable to the harsh environment of industrial site.

[0054] (4) The dual-beam non-parallelism compensation method provided by the present invention can compensate for the parallelism of the dual collimated beams in real time, greatly improving the measurement accuracy and robustness of the roll angle, and solving the problem of low roll angle measurement accuracy of traditional methods. Attached Figure Description

[0055] Figure 1 This is a structural diagram of a machine tool guideway five-degree-of-freedom error simultaneous measurement device for beam drift and non-parallelism compensation.

[0056] Figure 2 This is a front view of the position change of the light spot on the third position sensitive detector when the mobile device has a pitch angle.

[0057] Figure 3 This is a front view of the position change of the light spot on the third position sensitive detector when there is a sway angle on the mobile terminal.

[0058] Figure 4 This is a diagram showing the change in the position of the light spot on the detector in the first four quadrants when the mobile device has horizontal straightness.

[0059] Figure 5 This is a diagram showing the change in the position of the light spot on the detector in the first four quadrants when the mobile device has vertical straightness.

[0060] Figure 6 This is a diagram showing the position changes of the light spots on the first and second quadrant detectors when the mobile device has a roll angle.

[0061] Figure 7 This is a diagram showing the change in the optical path when the y-axis of the beam on the right side of the fixed end shifts at an angle.

[0062] Figure 8 This is a diagram showing the change in the optical path when the beam on the right side of the fixed end experiences angular drift along the x-axis.

[0063] Figure 9 This is a diagram showing the change in the optical path when the beam on the right side of the fixed end experiences angular drift along the x-axis.

[0064] Figure 10 This is a schematic diagram of the principle for monitoring and compensating for changes in the non-parallelism of dual beams.

[0065] Reference numerals in the attached figures: 1-Laser, 2-Quarter-wave plate, 3-First beam splitter, 4-First reflecting mirror, 5-Second beam splitter, 6-Third beam splitter, 7-First pyramidal reflecting mirror, 8-Half-transparent and half-reflective mirror, 9-Fourth beam splitter, 10-First quadrant detector, 11-First convex lens, 12-First position sensitive detector, 13-Second reflecting mirror, 14-Second pyramidal reflecting mirror, 15-Fifth beam splitter, 16-Second quadrant detector, 17-Second convex lens, 18-Second position sensitive detector, 19-Third convex lens, 20-Third position sensitive detector, 21-Polarizing beam splitter, 22-First photodiode, 23-Second photodiode, 24-Fixed end, 25-Moving end; Detailed Implementation

[0066] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0067] In the following embodiments, ε x Let ε be the pitch angle. y For the deflection angle, ε z For the roll angle, δ x For horizontal straightness, δ y For vertical straightness, Δx 10 It is the distance the light spot moves along the x-axis on the first four-quadrant detector 10, Δy 10 It is the distance the light spot moves along the y-axis on the first four-quadrant detector 10, Δy 20 It is the distance the light spot moves along the y-axis on the third position sensitive detector 20, f 19 It is the focal length of the third convex lens 19, Δz 20 It is the distance the light spot moves along the z-axis on the third position sensitive detector 20, Δy 16 d is the distance the light spot moves along the y-axis on the second quadrant detector 16, d is the distance between the first quadrant detector 10 and the second quadrant detector 16, and Δz is the distance between the first quadrant detector 10 and the second quadrant detector 16. 12 It is the distance the light spot moves along the z-axis on the first position sensitive detector 12, f 11 θ is the focal length of the first convex lens 11, l is the distance between the fixed end 24 and the moving end 25, and θ is the focal length of the first convex lens 11. yr θ represents the laser angle drift in the y-direction of the beam on the right side of the fixed end. xr θ represents the laser angle drift of the beam on the right side of the fixed end in the x-direction. xl The laser angle drift of the beam on the left side of the fixed end in the x-direction.

[0068] Example 1

[0069] This embodiment provides a separate five-degree-of-freedom error measurement device with optical path drift compensation, such as... Figure 1 As shown, the machine tool guideway five-degree-of-freedom error simultaneous measurement device consists of a laser 1, a quarter-wave plate 2, a first beam splitter 3, a first reflecting mirror 4, a second beam splitter 5, a third beam splitter 6, a first pyramidal reflecting mirror 7, a semi-transparent and semi-reflective mirror 8, a fourth beam splitter 9, a first quadrant detector 10, a first convex lens 11, a first position sensitive detector 12, a second reflecting mirror 13, a second pyramidal reflecting mirror 14, a fifth beam splitter 15, a second quadrant detector 16, a second convex lens 17, a second position sensitive detector 18, a third convex lens 19, a third position sensitive detector 20, a polarizing beam splitter 21, a first photodiode 22, and a second photodiode 23.

[0070] Laser 1, quarter-wave plate 2, first beam splitter 3, first reflecting mirror 4, second beam splitter 5, third beam splitter 6, fourth beam splitter 9, first quadrant detector 10, first convex lens 11, first position sensitive detector 12, second reflecting mirror 13, fifth beam splitter 15, second quadrant detector 16, second convex lens 17, second position sensitive detector 18, third convex lens 19, and third position sensitive detector 20 together constitute fixed end 24;

[0071] The first pyramidal reflector 7, the semi-transparent and semi-reflective mirror 8, the second pyramidal reflector 14, the polarizing beam splitter 21, the first photodiode 22, and the second photodiode 23 together constitute the moving end 25.

[0072] When using the machine tool guideway five-degree-of-freedom error simultaneous measurement device, the fixed end 24 is installed at the fixed position of the axis to be measured on the CNC machine tool and remains stationary, while the moving end 25 is installed on the slide of the axis to be measured on the CNC machine tool and moves accordingly.

[0073] Specifically, the collimated laser emitted by laser 1 is linearly polarized light, which is converted into circularly polarized light by a quarter-wave plate 2, with its fast axis making an angle of 45° with the polarization direction of the emitted beam. The emitted beam from the quarter-wave plate 2 is split into two beams by the first beam splitter 3. Its transmitted beam is reflected by the first reflecting mirror 4 and then split into two beams again by the second beam splitter 5. Its transmitted beam passes through the third beam splitter 6 and the first pyramidal reflecting mirror 7 in sequence and is then split into two beams by the semi-transparent and semi-reflective mirror 8. Its transmitted beam passes through the fourth beam splitter 9 and is split into two beams again. One beam is received by the first four-quadrant detector 10 to measure the horizontal and vertical straightness errors, and the other beam passes through the first convex lens 11 and is received by the first position-sensitive detector 12 to measure the angular drift of the emitted beam from the right side of the fixed end. The reflected beam from the second beam splitter 5 passes sequentially through the second reflector 13 and the second pyramidal reflector 14 before being split into two beams by the fifth beam splitter 15. One beam is received by the second quadrant detector 16 to measure the horizontal and vertical straightness errors, while the other beam, after passing through the second convex lens 17, is received by the second position-sensitive detector 18 to measure the angular drift of the beam emitted from the left side of the fixed end. The roll angle can be calculated from the vertical straightness error measured by the first quadrant detector 10 and the second quadrant detector 16. three Beam splitter 6 The reflected beam is received by the third position-sensitive detector 20 after passing through the third convex lens 19, and is used to measure the pitch angle and yaw angle errors. The reflected light from the first beam splitter 3 is split into two beams after passing through the polarizing beam splitter 21, and is received by the first photodiode 22 and the second photodiode 23 respectively, and is used to compensate for the non-parallelism of the double collimated beams on the right and left sides of the fixed end.

[0074] Example 2

[0075] This embodiment provides a method for simultaneously measuring the five degrees of freedom errors of machine tool guideways, including beam drift and non-parallelism compensation, for the measuring device structure of Embodiment 1. The five degrees of freedom error measurement of the machine tool guideways includes the measurement of errors in pitch angle, yaw angle, roll angle, horizontal straightness, and vertical straightness, and is implemented in the following steps:

[0076] a. To achieve pitch and yaw angle measurement, when the mobile end has a pitch angle ε at 25°. x At times, such as Figure 2 As shown, the light spot on the third position-sensitive detector 20 moves Δy along the y-axis. 20 The focal length of the third convex lens 19 is f. 19 Pitch angle ε x Expressed using equation (1):

[0077]

[0078] When the mobile terminal 25 has a yaw angle ε y At times, such as Figure 3 As shown, the light spot on the third position-sensitive detector 20 moves Δz along the z-axis. 20 The focal length of the third convex lens 19 is f. 19 yaw angle ε y Expressed using equation (2):

[0079]

[0080] b. To achieve horizontal and vertical straightness measurement, when the moving end 25 has a horizontal straightness δ x At times, such as Figure 4 As shown, the light spot on the first quadrant detector 10 moves Δx along the x-axis. 10 Horizontal straightness δ x Expressed using equation (3):

[0081]

[0082] When the vertical straightness δ exists at the first quadrant detector 10 of mobile terminal 2 y At times, such as Figure 5 The light spot on the first quadrant detector 10 moves Δy along the y-axis. 10 Horizontal straightness δ y Expressed using equation (4):

[0083]

[0084] c. To achieve roll angle measurement, when the vertical straightness δ exists at the first four-quadrant detector 10 of the mobile end 25. y And there is a roll angle ε z At times, such as Figure 6 As shown, the light spot on the first quadrant detector 10 moves Δy along the y-axis. 10 The light spot on the second quadrant detector 16 moves Δy along the y-axis. 16 The distance between the first quadrant detector 10 and the second quadrant detector 16 is d, and the roll angle is ε. z Expressed using equation (5):

[0085]

[0086] Example 3

[0087] This embodiment provides a method for measuring and compensating for optical path angle drift based on the measuring device structure of Embodiment 1;

[0088] When the emitted beam from the right side of the fixed end 24 experiences angular drift, it affects the measurements of pitch angle, yaw angle, horizontal straightness, vertical straightness, and roll angle; when the emitted beam from the left side of the fixed end 24 experiences drift, it affects the measurement of vertical straightness at the second quadrant detector 16, and consequently, the roll angle measurement. Measuring and compensating for optical path angular drift involves the following steps:

[0089] a. The y-axis of the beam emitted from the right side of fixed end 24 experiences angular drift θ. yr At times, such as Figure 7 The light spot on the first position sensitive detector 12 moves Δz along the z-axis. 12 The focal length of the first convex lens 11 is f. 11 Laser angle drift θ yr Expressed using equation (6):

[0090]

[0091] Compensated yaw angle ε y Expressed using equation (7):

[0092]

[0093] Considering laser angle drift θ yr When considering the effect on horizontal straightness, it is assumed that the laser rotates around the center position of the third beam splitter 6, and the distance between components inside the fixed end is negligible. Therefore, the distance between the fixed end 24 and the moving end 25 is l, and the compensated horizontal straightness δ is... x ′ is represented by (8):

[0094]

[0095] b. The x-axis of the beam emitted from the right side of fixed end 24 experiences angular drift θ. xr At times, such as Figure 8 The light spot on the first position sensitive detector 12 moves Δy along the y-axis. 12 The focal length of the first convex lens 11 is f. 11 Laser angle drift θ xr Expressed using equation (9):

[0096]

[0097] Compensated pitch angle ε x Expressed using equation (10):

[0098]

[0099] Considering laser angle drift θ xrWhen considering the effect on vertical straightness, it is assumed that the laser rotates around the center position of the third beam splitter 6, and the distance between components inside the fixed end is negligible. Therefore, the distance between the fixed end 24 and the moving end 25 is l, and the compensated vertical straightness δ is... y ′ is represented by (11):

[0100]

[0101] c. When the x-axis of the beam emitted from the left side of the fixed end 24 shifts by an angle θ xl At times, such as Figure 9 The light spot on the second position sensitive detector 18 moves Δy along the y-axis. 18 The second convex lens 17 has a focal length of f. 17 Laser angle drift θ xl Expressed using equation (12):

[0102]

[0103] Laser angle drift θ xl When the vertical straightness of the second position sensitive detector 18 is affected, and thus the roll angle is affected, it is assumed that the laser rotates around the center position of the second reflector 13, and the distance between the components inside the fixed end is negligible. Therefore, the distance between the fixed end 24 and the moving end 25 is l, and the distance between the first quadrant detector 10 and the second quadrant detector 16 is d. The compensated roll angle ε is then calculated. z ′ is represented by (13):

[0104]

[0105] Example 4

[0106] This embodiment provides a dual-beam non-parallelism compensation method for the measuring device structure of Embodiment 1;

[0107] When the emitted beams from the right and left sides of the fixed end 24 are not parallel, it will greatly affect the measurement accuracy of the roll angle. When the angle between the right and left beams is ε... d At that time, it can be calculated from the voltage signals received by the first photodiode 22 and the second photodiode 23, such as Figure 10 As shown. The voltages of the first photodiode 22 and the second photodiode 23 are I1 and I2 respectively, then ε d It can be represented by (14):

[0108]

[0109] The distance between components inside the fixed end 24 is negligible, so the distance between the fixed end 24 and the moving end 25 is l, and the distance between the first quadrant detector 10 and the second quadrant detector 16 is d. From geometric relationships, it can be seen that the introduced roll angle measurement error ε... zd It can be represented by (15):

[0110]

[0111] Then the compensated roll angle ε z "Use (16) to represent:

[0112]

[0113] This invention is not limited to the embodiments described above. The above description of specific embodiments is intended to illustrate and explain the technical solutions of this invention. The specific embodiments described above are merely illustrative and not restrictive. Without departing from the spirit and scope of the claims, those skilled in the art can make many specific modifications based on the teachings of this invention, and these modifications all fall within the scope of protection of this invention.

Claims

1. A five-degree-of-freedom error measuring device for machine tool guideways with beam drift compensation, characterized in that, The system includes a laser (1), a quarter-wave plate (2), a first beam splitter (3), a first reflector (4), a second beam splitter (5), a third beam splitter (6), a first pyramidal reflector (7), a semi-transparent mirror (8), a fourth beam splitter (9), a first quadrant detector (10), a first convex lens (11), a first position-sensitive detector (12), a second reflector (13), a second pyramidal reflector (14), a fifth beam splitter (15), a second quadrant detector (16), a second convex lens (17), a second position-sensitive detector (18), a third convex lens (19), a third position-sensitive detector (20), a polarizing beam splitter (21), a first photodiode (22), and a second photodiode (23); the laser (1), quarter-wave plate (2), first beam splitter (3), first reflector (4), second... The fixed end (21) is composed of beam splitter (5), third beam splitter (6), fourth beam splitter (9), first quadrant detector (10), first convex lens (11), first position sensitive detector (12), second reflector (13), fifth beam splitter (15), second quadrant detector (16), second convex lens (17), second position sensitive detector (18), third convex lens (19), and third position sensitive detector (20); the movable end (25) is composed of first pyramidal reflector (7), semi-transparent and semi-reflective mirror (8), second pyramidal reflector (14), polarizing beam splitter (21), first photodiode (22), and second photodiode (23); when the error measuring device is used, the fixed end (24) is fixedly installed at the fixed position of the axis to be measured on the CNC machine tool, and the movable end (25) is installed on the slide of the axis to be measured on the CNC machine tool and moves accordingly; The collimated laser emitted by the laser (1) is linearly polarized light. After being converted into circularly polarized light by a quarter-wave plate (2), the outgoing beam of the quarter-wave plate (2) is split into two beams by the first beam splitter (3). The transmitted beam of the first beam splitter (3) is reflected by the first mirror (4) and then split into two beams by the second beam splitter (5). The transmitted beam of the second beam splitter (5) passes through the third beam splitter (6) and the first pyramidal mirror (7) in sequence and is then split into two beams by the semi-transparent mirror (8). The transmitted beam of the semi-transparent mirror (8) passes through the fourth beam splitter (9) and is then split into two beams again. One beam is received by the first quadrant detector (10) to measure the horizontal and vertical straightness errors. The other beam passes through the first convex lens (11) and is received by the first position sensitive detector (12) to measure the angular drift of the outgoing beam from the right side of the fixed end (24). The reflected beam after passing through the second beam splitter (5) passes sequentially through the second reflector (13) and the second pyramidal reflector (14) before being split into two beams by the fifth beam splitter (15). One beam is received by the second quadrant detector (16) to measure the horizontal and vertical straightness errors, and the other beam passes through the second convex lens (17) and is received by the second position-sensitive detector (18) to measure the angular drift of the beam emitted from the left side of the fixed end (24). The roll angle is measured by the first quadrant detector (10) and the second quadrant detector (14). The vertical straightness error measured by the quadrant detector (16) is calculated; the reflected beam after passing through the third beam splitter (6) is received by the third position sensitive detector (20) after passing through the third convex lens (19), and is used to measure the pitch angle and yaw angle errors; the reflected light from the first beam splitter (3) is split into two beams after passing through the polarizing beam splitter (21), and is received by the first photodiode (22) and the second photodiode (23) respectively, and is used to compensate for the non-parallelism of the double collimated beams on the right and left sides of the fixed end (24).

2. The five-degree-of-freedom error measuring device for machine tool guideways with beam drift compensation according to claim 1, characterized in that, The angle between the fast axis of the quarter-wave plate (2) and the polarization direction of the outgoing beam is 45°.

3. A method for measuring the five-degree-of-freedom error of a machine tool guideway with beam drift compensation, based on the five-degree-of-freedom error measuring device for machine tool guideways as described in any one of claims 1-2, characterized in that, The five-degree-of-freedom error measurement of machine tool guideways includes the measurement of errors in pitch angle, yaw angle, roll angle, horizontal straightness, and vertical straightness, and includes the following steps: a. To achieve pitch and yaw angle measurement, when the mobile end (25) has a pitch angle ε x At that time, the light spot on the third position sensitive detector (20) moves Δy along the y-axis. 20 The focal length of the third convex lens (19) is f. 19 Pitch angle ε x Expressed using equation (1): When the mobile terminal (25) has a yaw angle ε y At that time, the light spot on the third position sensitive detector (20) moves Δz along the z-axis. 20 The focal length of the third convex lens (19) is f. 19 yaw angle ε y Expressed using equation (2): b. To achieve horizontal and vertical straightness measurement, when the mobile end (25) has horizontal straightness δ x At that time, the light spot on the first quadrant detector (10) moves Δx along the x-axis. 10 Horizontal straightness δ x Expressed using equation (3): When the vertical straightness δ exists at the first quadrant detector (10) of the mobile terminal (25) y At that time, the light spot on the first quadrant detector (10) moves Δy along the y-axis. 10 Horizontal straightness δ y Expressed using equation (4): c. To achieve roll angle measurement, when there is vertical straightness δ at the first four-quadrant detector (10) of the mobile end (25). y And there is a roll angle ε z At that time, the light spot on the first quadrant detector (10) moves Δy along the y-axis. 10 The light spot on the second quadrant detector (16) moves Δy along the y-axis. 16 The distance between the first quadrant detector (10) and the second quadrant detector (16) is d, and the roll angle is ε. z Expressed using equation (5): 。 4. A method for measuring and compensating for optical path angle drift, based on the five-degree-of-freedom error measuring device for machine tool guideways as described in any one of claims 1-2, characterized in that, include: a. The y-axis of the beam emitted from the right side of the fixed end (24) undergoes an angular drift θ. yr At that time, the light spot on the first position sensitive detector (12) moves Δz along the z-axis. 12 The focal length of the first convex lens (11) is f. 11 Laser angle drift θ yr Expressed using equation (6): Compensated yaw angle ε y Expressed using equation (7): The yaw angle of the mobile terminal (25) is ε y The light spot on the third position sensitive detector (20) moves a distance Δz along the z-axis. 20 The focal length of the third convex lens (19) is f. 19 ; Considering laser angle drift θ yr When considering the effect on horizontal straightness, it is assumed that the laser rotates around the center position of the third beam splitter (6), and the component distance inside the fixed end (24) is ignored. Then, the distance between the fixed end (24) and the moving end (25) is l, and the compensated horizontal straightness δ x Expressed using equation (8): δ x For the horizontal straightness of the mobile terminal (25), Δx 10 The distance the light spot on the first quadrant detector (10) moves along the x-axis; b. The x-axis of the beam emitted from the right side of the fixed end (24) experiences an angular drift θ. xr At that time, the light spot on the first position sensitive detector (12) moves Δy along the y-axis. 12 The focal length of the first convex lens (11) is f. 11 Laser angle drift θ xr Expressed using equation (9): Compensated pitch angle ε x Expressed using equation (10): The pitch angle of the mobile device (25) is ε x The light spot on the third position sensitive detector (20) moves Δy along the y-axis. 20 ; Considering laser angle drift θ xr When considering the effect on vertical straightness, it is assumed that the laser rotates around the center position of the third beam splitter (6), and the component distance inside the fixed end (24) is ignored. Then, the distance between the fixed end (24) and the moving end (25) is l, and the compensated vertical straightness δ y Expressed by equation (11): The vertical straightness at the first quadrant detector (10) of the mobile terminal (25) is δ y The light spot on the first quadrant detector (10) moves Δy along the y-axis. 10 ; c. When the x-axis of the beam emitted from the left side of the fixed end (24) undergoes an angular drift θ xl At that time, the light spot on the second position sensitive detector (18) moves Δy along the y-axis. 18 The focal length of the second convex lens (17) is f. 17 Laser angle drift θ xl Expressed using equation (12): Ignoring the component distances inside the fixed end (24), the distance between the fixed end (24) and the moving end (25) is l, and the distance between the first quadrant detector (10) and the second quadrant detector (16) is d. The compensated roll angle ε z Expressed using equation (13): The light spot on the second quadrant detector (16) moves a distance Δy along the y-axis. 16 .

5. A dual-beam non-parallelism compensation method, based on the five-degree-of-freedom error measuring device for machine tool guideways as described in any one of claims 1-2, characterized in that, When the angle between the beam emitted from the right side and the beam emitted from the left side of the fixed end (24) is ε d At that time, it is calculated from the voltage signals received by the first photodiode (22) and the second photodiode (23). The voltages of the first photodiode (22) and the second photodiode (23) are I1 and I2, respectively. Then ε d Expressed using equation (14): Ignoring the component distances inside the fixed end (24), the distance between the fixed end (24) and the moving end (25) is l, and the distance between the first quadrant detector (10) and the second quadrant detector (16) is d. From geometric relationships, the introduced roll angle measurement error ε zd Expressed using equation (15): Then the compensated roll angle ε z "This can be expressed using equation (16):" Δy 16 Δy represents the distance the light spot on the second quadrant detector (16) moves along the y-axis; 18 Δy represents the distance the light spot on the second position-sensitive detector (18) moves along the y-axis. 10 Δy represents the distance the light spot on the first quadrant detector (10) moves along the y-axis; 12 f is the distance the light spot on the first position-sensitive detector (12) moves along the y-axis; 17 f is the focal length of the second convex lens (17). 11 Let be the focal length of the first convex lens (11).

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