Based on the current detection methods, the transfer function of chord length measurement method is not always equal to 1, which can not correctly reflect the track irregularity. Inertial reference method is greatly influenced by speed. At low speed, the acceleration signal is weak and the signal-to-noise ratio is low, so it is necessary to do integral operation, and the low frequency signal is easy to cause integral saturation. Considering the integral stability, the error is large. Therefore, there are still many shortcomings in the current detection methods. With the development of photoelectric technology, on the basis of chord length measurement and inertial reference method, it is necessary to develop a detection method to obtain displacement signals by photoelectric displacement meter or photoelectric camera technology, and the detection accuracy will be greatly improved. Based on the application of wave grinding detection system in Huang Shuo railway, this paper guides rail grinding and explores grinding cycle.

Wave milling RMS milling

Wave grinding is the wave-like wear of the top surface of the rail on the railway line, and the light band on the surface of the rail is flickering. It has two properties: wavelength and valley depth. Wavelength is the longitudinal distance between two adjacent peaks, and valley depth is the vertical distance between adjacent peaks and valleys.

1 the influence of rail fluctuation on train operation

1. 1 Increase the maintenance cost of the public works department and damage the track.

(1) accelerates the crushing of stone slag. When the vertical force on the track increases, the ballast will be squeezed, and the workload of replacing and maintaining the ballast will increase.

(2) The phenomenon of empty hanging, white knots and boiling mud increased. Combined empty crane will turn the white ballast to the rail surface, which is a typical feature of empty crane. Long-term aerial suspension and the influence of natural disasters will make the track boil and mud. (3) Cracks and faults of sleepers increase. In the wave grinding area, the load and vertical force of the wave crest on the sleeper increase, the track is crushed, and many sleepers will form cracks or even fail.

2 composition and function

The wave abrasion detection system consists of software and hardware. The hardware mainly includes left and right axle box accelerometers, real-time acquisition computer, preprocessing device, wave mill waveform machine and so on. The software mainly includes real-time detection software for rail corrugation, data receiving software, over-limit editing and report generation software and waveform analysis software.

2. 1 System component function

(2) Pre-pretreatment device. The pretreatment device consists of 15V and 5V integrated regulated power supply and left (l) and right (r) acceleration processing boards. The front panel has debugging and detection holes, which can monitor the original signals of various sensors and the signals entering the A/D acquisition board through the processing board. The left (L) and right (R) acceleration signal processing boards preprocess the left and right acceleration signals respectively, including zero adjustment, gain adjustment and anti-aliasing filtering.

(3) Real-time processing computer for wave grinding. Real-time processing computer of wave mill is the core and brain of wave mill system. Under the real-time processing platform of wave mill, the original acceleration signal is displayed and stored at equal intervals. At the same time, through digital processing, integral filtering and other technologies, the displacement of the rail top surface relative to the axle box is calculated, and the amplitude of rail corrugation is output. After the industrial computer is turned on, the detection information should be set correctly on this interface.

Before acquisition, the real-time processing interface should correctly set the detection line, direction, starting mileage and status. The interface displays three groups of waveforms from top to bottom, that is, the wave mill peak waveform, the wave mill effective value waveform and the original trigger signal waveform, and transmits the data to the waveform machine in real time.

(4) wave mill. The wave mill waveform machine is located under the real-time processing computer of wave mill in the car. Its main functions are data storage and waveform display, which can compare the historical data of waveforms, output the overrun report in real time, and edit, count and print the data.

(5) The overrun report includes the overrun position, type, peak size, length, grade, speed and detection standard.

(6) The waveform diagram includes real-time detection speed and mileage, left and right original trigger signals, left and right original value waveforms, and left and right effective value waveforms. When browsing the waveform diagram, you can view the fluctuation and trend of the rail surface, click the zoom function, enlarge the waveform diagram, and click Measure to get the original peak value of the wave mill at any point and the root mean square value of the wave mill at any section. It can also predict the development trend of diseases by comparing the historical data of waveforms, guide rail maintenance and evaluate rail maintenance quality.

2.2 detection principle

Rail corrugation detection system is a dynamic on-line detection system for rail top corrugation. It uses inertial reference method to realize equidistant sampling, display and storage of the original acceleration signal under QNX real-time operating system platform, and the computer carries out secondary integration and filtering processing on the original trigger signal to calculate the displacement of the rail top surface relative to the axle box, thus obtaining the amplitude of the wave mill.

2.3 Practice and application

Because the wave abrasion disease mainly occurs in the lower strand of the curve, the current wave abrasion detection system guides the rail grinding, and mainly depends on the descending arrangement of the root mean square of the lower strand of the curve, so as to formulate the milling or grinding scheme (as shown in table 1).

(2) Evaluate the quality of track maintenance. Whether milling operation or grinding operation, wave grinding detection system can be used to evaluate the quality of operation before and after construction. By using the zoom and measurement functions of the waveform diagram, specific values can be read. The gray waveform represents the amplitude of rail surface wave grinding before grinding, and the blue waveform represents the amplitude of surface wave grinding after grinding. Through comparison, it is found that the amplitude of wave grinding after milling is obviously reduced.

(3) Establish a wave mill observation ledger. Wave wear is the main disease of rail surface. In order to explore the line grinding cycle and study the comprehensive technical measures to prolong the service life of heavy-haul railways, it is necessary to conduct on-site verification and study the effectiveness and practicability of the comprehensive technical measures. On this basis, we explore the grinding (milling) cycle by establishing the observation account of the milling section. As shown in Table 2.

As shown in Table 2, April represents pre-grinding wave grinding, and May, June, July, August and September represent post-grinding wave grinding development. The wave grinding after grinding is obviously lower than that before grinding, and the wave grinding amplitude increases month by month with time. Through tracking observation, when the amplitude of wave grinding is equal to that before milling, the milling period is obtained.

3 Conclusion

Based on the current detection methods, the transfer function of chord length measurement method is not always equal to 1, which can not correctly reflect the track irregularity. Inertial reference method is greatly influenced by speed. At low speed, the acceleration signal is weak and the signal-to-noise ratio is low, so it is necessary to do integral operation, and the low frequency signal is easy to cause integral saturation. Considering the integral stability, the error is large. Therefore, there are still many shortcomings in the current detection methods.

With the development of photoelectric technology, on the basis of chord length measurement and inertial reference method, it is necessary to develop a detection method to obtain displacement signals by photoelectric displacement meter or photoelectric camera technology, and the detection accuracy will be greatly improved.

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