A roll angle measurement system based on the principle of autocollimation
Through a rolling angle measurement system based on the principle of self-collimation, combined with a plane mirror system and a level, the problem of measuring the rolling angle error of machine tool guide rails in the prior art is solved, accurate measurement of the vertical axis is achieved, and measurement accuracy is improved.
Patent Information
- Application Number
- CN202210619986.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-06-02
- Publication Date
- 2025-04-29
- Estimated Expiration
- 2042-06-02
AI Technical Summary
It is difficult for the prior art to effectively measure the rolling angle error of machine tool guide rails, especially in the measurement of vertical axis, where there are problems such as limited accuracy and complex structure of optical methods.
A rolling angle measurement system based on the principle of self-collimation is adopted. The system includes a semiconductor laser, a spectroscopic prism, a focus lens and a position-sensitive detector. Combined with a planar mirror system and a level meter, it realizes accurate measurement of rolling angle through spot position calibration and system error compensation.
The system is simple in structure, convenient in dimming, low in cost, easy to integrate, can meet the rolling angle measurement requirements of the vertical axis, and removes plane mirror errors through level calibration to improve measurement accuracy.
Smart Images
Figure CN115218826B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of precision mechanical error measurement, and in particular relates to a rolling angle measurement system based on the autocollimation principle. Background Art
[0002] Manufacturing has increasingly become the pillar of economic development, and the processing technology level of CNC machine tools directly determines the manufacturing level of a country. Machine tools are basic equipment in the industrial field and have always been called "working mother machines". The level of machine tool processing accuracy is directly related to the industrial development of a country.
[0003] According to the ISO 230-1 standard, the linear guide motion pair of a machine tool will produce six degrees of freedom geometric motion errors during its motion (such as Figure 1 The six degrees of freedom errors are positioning error (δ y ), vertical straightness error (δ z ), horizontal straightness error (δ x ), roll angle error (ε y ), yaw angle error (ε z ) and pitch angle error (ε x ). Among them, the measurement of roll angle error is a difficult point. Common non-optical methods for measuring roll angle include the level method and the physical position reference method. However, the level method requires the direction of gravity as a reference, and can only measure the horizontal axis of motion, but cannot measure the roll angle of the vertical axis of motion; the physical position reference method uses the square iron as a reference, and measures the straightness error of the square iron to calculate the roll angle error of the guide rail; common optical measurement methods include geometric method and interference method. In the geometric method, the use of double parallel beams to measure the roll angle error is more commonly used. By detecting the straightness error of two positions on the working platform, the roll angle error is obtained through the geometric relationship. However, the double beam method is difficult to ensure that the two beams are parallel, and there is a non-parallelism error; the interference method uses specific optical elements to convert the roll angle into an optical path difference or phase difference change, and obtains the roll angle error by detecting the optical path difference or phase difference change. The measurement accuracy of the interference method is greatly affected by mechanical vibration and environmental changes, so it needs to meet higher measurement conditions, and the structure is complex and difficult to miniaturize. Summary of the invention
[0004] In view of the problems existing in the prior art, the present invention provides a roll angle measurement system based on the autocollimation principle, which has a simple structure, convenient light adjustment, and can meet the vertical axis measurement requirements.
[0005] The technical solution of the present invention:
[0006] A roll angle measurement system based on the autocollimation principle includes a laser autocollimation measurement device 11 and a plane reflector system 12; the laser autocollimation measurement device 11 includes a semiconductor laser 1, a beam splitter prism 2, a focusing lens 3 and a first position sensitive detector 4, which is located on the side of a guide rail 8 to be measured and is used for roll angle measurement; the plane reflector system 12 includes a second position sensitive detector 5, a third position sensitive detector 6 and a plane reflector 7, which are used to measure and adjust the initial and terminal light spot positions during the measurement process to ensure that the light spot is always near the same straight line on the plane reflector 7 during the measurement process.
[0007] The plane reflector 7 is vertically mounted on the motion platform 9 of the guide rail 8 to be measured, and the second position sensitive detector 5 and the third position sensitive detector 6 are mounted at both ends of the plane reflector 7 for spot position calibration.
[0008] The beam splitter prism 2 is located in front of the semiconductor laser 1, the focusing lens 3 is located on the side of the beam splitter prism 2, and the first position sensitive detector 4 is located behind the focusing lens 3; the light beam generated by the semiconductor laser 1 is split into two after passing through the beam splitter prism 2, and its transmitted light enters the plane reflector 7, and the light beam reflected back by the reflector 7 passes through the beam splitter prism 2 again, and the reflected light at this time enters the focusing lens 3 and then enters the first position sensitive detector 4.
[0009] When measuring the guide rail rolling angle, the specific steps are as follows:
[0010] Step (1) Installing a level meter 10 on the motion platform 9 and measuring the rolling angle of the guide rail by the level meter 10;
[0011] Step (2) installing the laser autocollimation measuring device 11 and the plane reflector system 12, first adjusting the installation position of the plane reflector 7 so that when measuring the start and end positions of the measured guide rail 8, the light spot emitted by the laser autocollimation measuring device 11 illuminates the center positions of the second position sensitive detector 5 and the third position sensitive detector 6; the roll angle of the measured guide rail 8 during the movement process is calculated by the value measured by the first position sensitive detector 4; the roll angle difference measured in step (1) and step (2) is the system error of the roll angle measurement system based on the autocollimation principle;
[0012] Step (3) When measuring the rolling angle of other guide rails, a rolling angle measurement system based on the autocollimation principle is installed for measurement, and the system error obtained in step (2) is compensated to the measured rolling angle to finally obtain the actual rolling angle.
[0013] The beneficial effects of the present invention are as follows: the system of the present invention uses a semiconductor laser to measure the roll angle, has a simple structure, convenient dimming, low cost, and is easy to integrate. It can be used not only for measuring the roll angle of the horizontal axis, but also for measuring the roll angle of the vertical axis. A level is used to calibrate the measurement result, thereby removing the mirror shape error of the plane mirror and improving the measurement accuracy of the roll angle error. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 It is a schematic diagram of the 6-DOF motion error of the machine tool guideway;
[0015] Figure 1 Middle: δ x is the straightness error in the X direction. z is the straightness error in the Z direction; δy is the positioning error; ε x is the pitch angle error; ε z is the yaw angle error; y is the roll angle error.
[0016] Figure 2 is a schematic diagram of a roll angle measurement system based on the autocollimation principle of the present invention;
[0017] Figure 3 is a schematic diagram of a plane mirror system;
[0018] Figure 4 It is a schematic diagram of the plane mirror error measurement principle;
[0019] Figure 2-4 In the figure: 1 semiconductor laser; 2 beam splitter prism; 3 focusing lens; 4 first position sensitive detector; 5 second position sensitive detector; 6 third position sensitive detector; 7 plane reflector; 8 measured guide rail; 9 motion platform; 10 level; 11 laser self-collimation measuring device; 12 plane reflector system. DETAILED DESCRIPTION
[0020] The specific implementation method of the present invention will be further explained in conjunction with the accompanying drawings and technical solutions.
[0021] like Figure 2-Figure 3 As shown, a roll angle measurement system based on the autocollimation principle includes a semiconductor laser 1, a beam splitter prism 2, a focusing lens 3, a first position sensitive detector 4, a second position sensitive detector 5, a third position sensitive detector 6, a plane reflector 7 and a level 10. Among them, the semiconductor laser 1, the beam splitter prism 2, the focusing lens 3, and the position sensitive detector 4 constitute a laser autocollimation measurement device 11 for deflection angle measurement. The second position sensitive detector 5 and the third position sensitive detector 6 are respectively installed at both ends of the plane mirror 7, and together with the plane reflector 7, they constitute a plane reflector system 12.
[0022] When measuring the rolling angle motion error of the guide rail, the plane reflector system 12 is installed on the motion platform 9 of the guide rail to be measured, and moves with the motion platform 9 of the guide rail to be measured. The light beam generated by the semiconductor laser 1 is split into two after passing through the beam splitter prism 2, and its transmitted light is incident on the plane reflector 7. The light beam reflected by the reflector 7 passes through the beam splitter prism 2 again, and then enters the position sensitive detector 4 after passing through the focusing lens 3. The rolling angle error can be calculated by the position change of the light spot on the position sensitive detector.
[0023] However, the plane reflector 7 has a mirror shape error ε error This error will affect the measurement of the roll angle. It is necessary to use a level 10 to measure and correct the shape error of the plane reflector 7. Figure 4 As shown, the level 10 and the plane reflector system 12 are installed on the motion platform 9 and move with the motion platform 9. The laser autocollimation measuring device 11 is fixed to the side of the measured guide rail 8. First, the installation position of the plane reflector 7 should be adjusted so that the light spot emitted by the laser autocollimation measuring device 11 illuminates the center position of the second position sensitive detector 5 and the third position sensitive detector 6 at the beginning and end of the measurement. In this way, during the movement of the measured guide rail 8, the moving track of the light spot is basically on the connecting line of the second position sensitive detector 5 and the third position sensitive detector 6.
[0024] like Figure 4 As shown, during measurement, the level 10 and the built measurement system are used to measure the rolling angle of the guide rail 8 at the same time. According to the measurement difference between the two, the influence of the shape error of the plane mirror 7 on the rolling angle measurement is calculated. After the shape error of the plane mirror 7 is known, when the rolling angle error of other guide rails is measured by this measurement system, it can be directly compensated to obtain an accurate rolling angle motion error value. The details are as follows:
[0025] The motion platform 9 moves along the y direction. At different y-direction positions, the plane mirror error has different effects on the angle. At position i, the system and the level 10 are used to measure the roll angle simultaneously. The roll angle ε measured by the level 10 is level(i) For reference, the system measures the value ε′ y(i) The difference between the value measured by the level 10 is the error ε of the plane mirror at position i. error(i) As shown in formula (1):
[0026] ε error(i) =ε′ y(i) -ε level(i) (1)
[0027] Measured ε error(i)is a scattered value, and spline fitting is required for the data, so as to obtain the position error of the plane reflector 7 between the second position sensitive detector 5 and the third position sensitive detector 6. After measuring the plane mirror error, when using this system to measure other guide rail rolling angles, the value ε′ is directly measured. y(i) When the actual rolling angle error ε of the guide rail at any position i is calculated, the compensation can be performed by formula (2). y(i) As shown in formula (2):
[0028] ε y(i) =ε′ y(i) -ε error(i) (2)
[0029] The invention has a simple structure, low cost, and is easy to integrate, and can be used for vertical axis measurement. A level is used to calibrate the measurement result, thereby removing the plane mirror error and improving the measurement accuracy of the rolling angle error.
Claims
1. A roll angle measurement system based on the autocollimation principle, characterized in that: The roll angle measurement system based on the autocollimation principle comprises a laser autocollimation measurement device (11) and a plane reflector system (12); the laser autocollimation measurement device (11) comprises a semiconductor laser (1), a beam splitter prism (2), a focusing lens (3) and a first position sensitive detector (4), which is located on the side of the guide rail (8) to be measured and is used for roll angle measurement; the plane reflector system (12) comprises a second position sensitive detector (5), a third position sensitive detector (6) and a plane reflector (7), which are used for measuring and adjusting the initial and terminal light spot positions during the measurement process; The plane reflector (7) is vertically mounted on a moving platform (9) of a measured guide rail (8), and a second position sensitive detector (5) and a third position sensitive detector (6) are mounted at both ends of the plane reflector 7 for spot position calibration; The beam splitter prism (2) is located in front of the semiconductor laser (1), the focusing lens (3) is located on the side of the beam splitter prism (2), and the first position sensitive detector (4) is located behind the focusing lens (3); the light beam generated by the semiconductor laser (1) is split into two after passing through the beam splitter prism (2), and its transmitted light enters the plane reflector (7), and the light beam reflected by the reflector 7 passes through the beam splitter prism (2) again, and the reflected light at this time enters the focusing lens (3) and then enters the first position sensitive detector (4); When measuring the guide rail rolling angle, the specific steps are as follows: Step (1) Installing a level meter (10) on the motion platform (9), and measuring the rolling angle of the guide rail by means of the level meter (10); Step (2) installing a laser autocollimation measuring device (11) and a plane reflector system (12), first adjusting the installation position of the plane reflector (7) so that when measuring the start and end positions of the measured guide rail (8), the light spot emitted by the laser autocollimation measuring device (11) illuminates the center positions of the second position sensitive detector (5) and the third position sensitive detector (6); the roll angle of the measured guide rail (8) during the movement process is calculated by the value measured by the first position sensitive detector (4); the roll angle difference measured in step (1) and step (2) is the system error of the roll angle measurement system based on the autocollimation principle; Step (3) When measuring the rolling angle of other guide rails, a rolling angle measurement system based on the autocollimation principle is installed for measurement, and the system error obtained in step (2) is compensated to the measured rolling angle to finally obtain the actual rolling angle.