Measurement tooling design and data reduction Total station measurement must have a target coordination. The standard circular prisms and reflectors cannot be used in this measurement work, so the ball prism is used as the cooperation target. According to the report in [3], the accuracy of the TDA5005 total station with CCR1.5′′ spherical prism is better than ±0.15mm, which fully meets the requirements of detection accuracy. Usually the measurement target should be directly in contact with the measured object to facilitate measurement. And data processing, but it is impossible to place the ball prism directly on the anchor bolt, so the corresponding auxiliary measuring tool is designed according to the size of the anchor bolt, as shown in 2.
Direct measurement of the hole When the hole diameter r < d < 1.5 r, the ball prism can be directly placed on the hole for measurement. Obviously, the center of the ball prism passes through the central axis of the hole, and the height from the hole is h = r2 - d24 (1) where d is the diameter of the hole.
When the hole diameter d<r or d>1.5r is measured, the ball prism cannot be directly placed on the hole for measurement. In this case, the machining tool is required to match the measurement. Insert the tool into the hole as shown in Figure 4 and place the ball prism on the tooling. The tooling also needs to ensure that the center of the ball passes through the centerline of the hole. At this time, the deviation of the center of the sphere is h=h1+h2 (2), where h1 is the height of the tooling, and h2 can be obtained according to the diameter of the hole in the tooling according to the formula (1). This measurement uses the first tooling design to ensure that the centerline of the bolt passes through the center of the ball prism and facilitates the data reduction. In order to reduce the deviation of the human eye sighting target, the target automatic recognition (ATR) function of the TDA5005 total station is activated during the detection process.
When measuring, the total station is placed at the center of the upper layer. As shown in Fig. 1, the radius of the circle and the position coordinates of the center of the circle can be calculated by measuring the three-dimensional coordinates of the bolt point, thereby obtaining the radius error and the center deviation. Since there are more than 400 Bolts in total, in order to improve work efficiency, more than 80 points have been measured from the inner and outer rings of the lower ring. A total of more than ten points have been measured on the upper ring, and a total of 180 points have been measured, which is completed in about 1.5 hours. The inspection task.
The fitting calculation of the measurement data processing circle can be performed directly in the measurement coordinate system. Since the upper and lower layers of the Anchor Bolts are flattened by the leveling instrument, it can be considered that the measuring points of the layers are on the same horizontal plane. Therefore, the measuring points are projected to a certain horizontal plane, and then the circle fitting calculation is performed to obtain the center coordinates of the circle and Radius value. The position of the total station remains unchanged throughout the measurement process, that is, the measurement coordinate system remains unchanged. Therefore, the three-dimensional coordinate difference between the centers of the upper and lower circles is the concentric (axis) error.
Actual test results The round fit was performed without any restrictions. It can be seen that the concentricity of the inner and outer rings of the lower ring is very good, but the difference from the design radius is large, and the concentricity of the upper ring is also greatly deviated, but the overall accuracy is about 3 mm, which is due to the accuracy of the instrument itself. . In addition, the error in the Z direction is large in the test results, indicating that the bolts are not strictly on one plane, that is, the accuracy of the civil construction is not high, and the main reason is that the accuracy of the instruments selected during construction is low, so in order to ensure the measurement Accuracy, the choice of the instrument with the right accuracy during construction is critical.
Conclusion This measurement shows that the application of the total station measurement system in the detection of anchor bolts is successful. The adjustment of the bolt placement accuracy is given at the same time as the bolt placement accuracy. The main conclusions are as follows: 1) The total station measurement system has its own superiority compared to other measurement systems, not only the system establishment speed is fast, but also suitable for narrow environment with poor measurement conditions and unrecognized conditions. . 2) The total station with the corresponding measuring tool is very necessary in the actual measurement work, not only can improve the measurement efficiency, but also ensure the measurement accuracy, which is conducive to the processing of measurement data. 3) The method of obtaining the adjustment amount of the rail anchor bolt is given, and the adjustment of the anchor bolt is guided.
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