CN103017690A - Method for measuring straightness of super-long guide rail - Google Patents

Abstract

The invention relates to a method for measuring the straightness of a guide rail and particularly relates to a method for measuring the straightness of a super-long guide rail, which aims to solve the problems that the conventional measuring method is low in measurement precision and has large errors, and the data processing and operation are complex. According to the method, a plurality of data points on the super-long guide rail are measured and acquired through a laser tracker, the data points are subjected to spatial straight line fitting, and data information of the acquired N tested sampling points is subjected to straightness calculation by a least square fitting algorithm, thereby obtaining the straightness of the guide rail. The method provided by the invention has the beneficial effects of easiness and convenience in data analysis and experimental operation, short testing time, simplicity data processing, low testing cost and high testing efficiency.

Description

A Method for Measuring Straightness of Super-long Guide Rail

technical field

The invention relates to a method for measuring the straightness of a guide rail, especially an extra-long guide rail.

Background technique

With the continuous development of industrial technology, super-length guide rails are being used in more and more fields, such as machine tools, transmission devices, railway tracks, etc. The straightness is the most important technical index of the guide rail, and its precision is directly related to the accuracy, reliability and stability of the equipment.

At present, there are many methods for testing the straightness of guide rails. Generally, there are three methods, namely level measurement method, autocollimator measurement method and laser interferometer measurement method.

The level meter measurement method is a traditional straightness measurement method, which is simple to operate, convenient to use, and low in cost. But its measurement accuracy is low, generally only up to 20μm/m. Using the level meter measurement method requires a graphical method to solve the straightness error of the guide rail. Data collection and analysis are prone to errors. This method needs to manually collect the coordinates of some fixed sampling points on the guide rail, so it is very difficult to measure the straightness of the ultra-long guide rail. .

The accuracy of the autocollimator measurement method has been improved compared with the level measurement method, generally 5 μm/m, but it is still difficult to meet the test requirements for the straightness of high-precision guide rails. In addition, since the test light is not absolutely collimated in the air, the larger the measurement range, the greater the deviation. Therefore, for the measurement of the ultra-long guide rail, the measurement error is very large.

The laser interferometer measurement method has a large measurement distance and high measurement accuracy, and the measurement accuracy can generally reach 0.4 μm/m. However, for the measurement of ultra-long guide rails, due to the long optical path, a series of factors such as air disturbance and vibration will have a great impact on the measurement, and the data processing and calculation of this method are relatively complicated, so it is difficult to complete with high precision. Measurement of the straightness of extra-long guide rails.

Contents of the invention

The invention provides a method for measuring the straightness of an ultra-long guide rail in order to solve the problems of low measurement accuracy, large error, and complex data processing and calculation in the existing measurement method.

A method for measuring the straightness of an ultra-long guide rail, the method is realized by the following steps:

Step 1, planning N test sampling points on the super-long guide rail, the intervals of the N test sampling points are equal, and the N is a positive integer;

Step 2. The spherical fixed reflector is adsorbed on the reflector base, and the reflector base is adsorbed on the guide rail slide seat, and the guide rail slide seat is placed on the super long guide rail described in step 1 along the length direction At the first test sampling point;

Step 3, adjust the laser tracker so that the light beam emitted by the laser tracker returns to the laser tracker after passing through the spherical fixed reflector, and the laser tracker obtains the data information of the first test sampling point;

Step 4. Move the guide rail slide to the next test sampling point, and the laser tracker collects the data information of each test sampling point in turn; realize the data collection of N test sampling points;

Step 5, using the least squares fitting algorithm to calculate the straightness of the data information of the N test sampling points collected in step 4, to obtain the straightness of the super-long guide rail.

Beneficial effects of the present invention: the present invention can accurately realize the measurement of the straightness of the ultra-long guide rail by expanding the existing functions of the laser interferometer; the method described in the present invention is simple and convenient in data analysis and experimental operation, short in test time and fast in data processing. Simple, low test cost and high test efficiency.

Description of drawings

Fig. 1 is a structural representation of the device in a method for measuring the straightness of a superlong guide rail according to the present invention;

Fig. 2 is a flow chart of a method for measuring the straightness of a superlong guide rail according to the present invention;

Fig. 3 is an effect diagram of a method for measuring the straightness of an ultra-long guide rail according to the present invention.

In the figure, 1. Laser tracker, 2. Super long guide rail, 3. Spherical fixed reflector, 4. Reflector base, 5. Guide rail sliding seat.

Detailed ways

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 1. This embodiment is described in conjunction with FIGS. 1 to 3 , a method for measuring the straightness of an ultra-long guide rail, wherein the device involved in the method mainly includes a laser tracker 1 , an ultra-long guide rail 2 , and a spherical fixed reflector 3 , reflector base 4 and guide rail slide seat 5; the concrete process of this method is:

1. Plan test points; plan several test sampling points on the super-long guide rail 2 at equal intervals;

2. Adjust the optical path; attach the reflector base 4 (magnetic) to the guide rail slide seat 5, and attach the spherical fixed reflector 3 to the reflector base 4. Due to the magnetic adsorption, the connection between the three is very After the connection is complete, adjust the optical path so that the laser tracker 1 is aligned with the first test point. Since the guide rail slide 5 is parallel to the super-long guide rail surface, measure the fluctuation of points on the guide rail slide surface at different positions It reflects the straightness of the guide rail.

3. Test point measurement: Align and test the first test point with the laser tracker 1, record and collect the spatial position coordinates (X ₁ , Y ₁ , Z ₁ ) of the first test point, and adjust them at equal intervals through the numerical control mechanism Move the guide rail slide 5, the laser tracker 1 will always track the spherical fixed reflector 3, so that the spatial position coordinates (X ₂ , Y ₂ , Z ₂ ), (X ₃ , Y ₃ ) of other test points can be measured and collected ,Z ₃ )…(X _N ,Y _N ,Z _N ) (assuming there are N test points in total).

4. Data judgment: judge whether the data is accurate and reliable, if there are many bad points in the measurement data, re-adjust the optical path, re-measure the test points and collect data; if the data is accurate and reliable, calculate the straightness. Wherein, the data bad point specifically refers to setting a threshold value. Since the threshold value is related to the accuracy of the measured super-long guide rail 2 itself, for the measurement of high-precision super-long guide rails, the threshold value is generally 10 μm. For the measurement of the guide rail, the threshold value is generally 50 μm.

5. Calculation of straightness; N test points are multiple discrete points on the spatial straight line, and a spatial straight line can be obtained by performing least square fitting on these points. Combined with Figure 3, this is a minimum cylindrical surface containing the actual line The straight line, the diameter value D of the cylinder is the straightness of the space straight line, that is, the straightness of the guide rail, which is the comprehensive straightness of the guide rail along two directions.

6. Separation of straightness; project the discrete data points obtained from the measurement onto the two base surfaces of the guide rail respectively. Combined with Figure 1, you can choose the surface of the guide rail slide 5 (base surface 1) and another plane (base surface 1) perpendicular to it. Surface 2), a series of discrete points can be obtained on the two base surfaces, and the straight line fitting of these discrete points on the respective base surfaces can be obtained to obtain the straightness of the two straight lines, that is, the guide rails along the two Straightness in direction.

The laser tracker 1 described in this embodiment is a high-precision, large-capacity portable three-dimensional coordinate measuring device. The laser tracker 1 emits a laser beam, and the beam returns to the laser tracker 1 through a spherical fixed reflector 3 . With two rotary encoders, horizontal and vertical, and a laser-based distance measurement system, the laser tracker 1 is able to determine the position of the spherical fixed reflector 3 target. The spherical fixed reflector 3 (SMR) is the target of the laser tracker 1, said spherical fixed reflector 3 comprising three mutually perpendicular mirrors positioned to the center point of the SMR. The laser tracker 1 tracks and locates the position of the SMR in real time, and all the light beams entering the SMR return in a parallel offset manner with the incident light. The position sensor in the laser tracker 1 detects the position of the reflected light beam and drives the servo motor so that the tracker is always aimed at the center of the SMR. This closed-loop system updates 1,000 times per second and allows the tracking head to track the target as it moves. The laser tracker uses two high-precision rotary encoders to measure the horizontal and vertical angles. The horizontal or azimuth encoder is located at the bottom of the cylindrical laser tracker. Its resolution is 0.02 arc seconds (5.5×10 ^-6 degrees). The vertical or apex axis encoders are positioned on the vertical top of the tracking head (inside the tracking head) of the laser tracker 1 and have the same resolution. The Position Sensitive Detector (PSD) also measures the angular position of the part of the target. The laser tracker 1 obtains information from the angle encoder and PSD and transmits the information through the motion mode. This model contains two rotational and two translational parameters, which can eliminate the systematic error of the laser tracker 1 .

The laser tracker 1 described in this embodiment is generally used to measure the relative positional relationship between objects, but its function can be broadened to realize the measurement of the straightness of super-long guide rails. Due to the use of laser technology, its measurement range can reach 230 feet (70 meters), and the high-precision option of laser tracker 1 - interferometer (IFM) has a maximum allowable error of 2μm+L 0.4μm/m, where L is laser tracking The distance between the instrument and the super long guide rail. Therefore, in this embodiment, the length of the ultra-long guide rail 2 measured by the laser tracker 1 can reach 70 m, and the detection accuracy is 0.4 μm/m.

Claims (2)

1. A method for measuring the straightness of superlong guide rail, characterized in that, the method is realized by the following steps: Step 1. Planning N test sampling points on the super-long guide rail (2), the intervals between the N test sampling points are equal, and the N is a positive integer; Step 2. The spherical fixed reflector (3) is adsorbed on the reflector base (4), and the reflector base (4) is adsorbed on the guide rail slide seat (5), and the guide rail slide seat (5) is The length direction of the guide rail is placed at the first test sampling point of the super-long guide rail described in step 1; Step 3. Adjust the laser tracker (1) so that the beam emitted by the laser tracker (1) returns to the laser tracker (1) after passing through the spherical fixed reflector (3), and the laser tracker (1) obtains the first Data information of test sampling points; Step 4. Move the guide rail slide (5) to the next test sampling point, and the laser tracker (1) collects the data information of each test sampling point in turn; realize the data collection of N test sampling points; Step 5. Using the least squares fitting algorithm to calculate the straightness of the data information of the N test sampling points collected in step 4, to obtain the straightness of the super-long guide rail (2). 2. a kind of method for measuring superlong guide rail straightness according to claim 1, is characterized in that, before step 5, also comprises the process of judging the data information of N test sample points, when the test sample of measurement When the data information of the point is greater than the threshold, step 3 is performed, and the range of the threshold is 10 μm to 50 μm.

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