Journal unloading trough ultrasonic testing inspection 'seven'

Journal unloading trough ultrasonic testing inspection 'seven' - 2021 01 - 03 ultrasonic testing is one of the industrial nondestructive testing method, is one of the important means to detect railway wagon wheel in our country, during the railway wagon wheel and parts inspection operations, vehicle system inspection staff, after many years of practical work, summarizes the railway truck axle shaft neck unloading slot 'seven word detection method of ultrasonic flaw detection: : sensitivity for improve opportunely, slight defect hold fast; Nuclear: a basic information check, inspection focus on heart; Check: check the shaft end center hole, eliminate interference without holes; : three means determined alternately, detection stability doesn't stand out; Diagnosis: found different wave good diagnosis, swinging probe crack; Than, the same shaft, regular crack waveform; Guide: withdrawal magnetic to identify, continuous improvement goals. 'seven character flaw detection of specific interpretation: ask: after daily sensitivity calibration, the actual detection, sensitivity based on the calibration value will increase 4 - again 6 db, on the premise of not appear too much clutter detection operations, in the incipient stage of crack, in the case of reflected wave is not very high, don't pass the smaller crack defects, found that the crack sensitivity will reply again after wave to the original calibration value, to determine. Nuclear: each wheel and axle inspection before, must be carefully checked and CARDS, axles axle tags, detailed control wheels for assembly, and the basic information of the bearing pressure equipment inspection were accomplish know fairly well, to the wheel to the assembly and the bearing pressure equipment for a long time and defect of multiple manufacturers and some imported key inspection check axle, axle speed overloading. Check: check the axle end surface and center hole inspection quality of working face, a convex table scarp, flash, burrs must be removed to ensure inspection surface level off, conform to the requirements of the inspection. Evenly railway rolling bearings bearing grease, found a large central hole of shaft impact testing, bearing magnetic back directly. : the probe points to the center hole, alternating with thumb and forefinger and middle finger hole to locate in the center of the shaft end, to evenly force 2 n - probe 5 n to 20 mm/s - The speed of 50 mm/s in the center hole and shaft end ring between bolt hole area make step reciprocating movement, and deflection 3 & deg; - 5° Scan. First clamp thumb and middle finger probe on both sides of the hole at the center of the index finger on the position along the circumferential and radial ( To realize the radial index finger flexion and extension mobile probe) Make step reciprocating movement and deflection 3 & deg; - 5° Scan to 1/3 of the shaft end weeks; Then alternate finger, thumb and index finger grip the probe on both sides of the hole at the center of the middle finger on position along the circumferential and radial ( By the thumb and index finger swinging realize radial mobile probe) Make step reciprocating movement and deflection 3 & deg; - 5° Scan to the end of the shaft in addition a third week; Finally, alternate fingers, use forefinger and middle finger grip the probe on both sides of the hole at the center of the thumb on the position along the circumferential and radial ( Realize radial mobile probe on the index finger and middle finger flexion and extension) Make step reciprocating movement and deflection 3 & deg; - 5° Scan to the end of the shaft end face a third week; To scan, make probe force more evenly, scan surface is more complete, more convenient operation, ensure the stability of the detection sensitivity. Diagnosis: after suspicious crack wave, little change along the radial move the probe waveform ( Because of the probe in the shaft end radial movement range is limited, beam to the influence of the centre hole depth) , circumferential swinging probe, crack rapid fierce wave of ups and downs, and frontier steep, clear wave root, unlike the general inherent reflection affected the formation reflected wave little change, such as grease and slow, wave root coarser, basic in a week. But in the incipient stage of crack ( Shaft neck more than in the corrosion area) Reflection is not strong, it is difficult to distinct and separate from general inherent reflection wave, if the circumferential swinging probes, waveform and fast fierce, no matter how high wave height, and only exist in journal a place, all in conformity with the characteristics, consider the bearing magnetic. If reflection wave exists in a week, circumferential swinging probe, waveform has severe fluctuations ( With general inherent reflection affected fat such as formation of the reflection wave distinguish) Processing, most of mark defect ( Serious cause stress concentration cracks) , also want to consider magnetic. Than: after find it hard to judge the suspicious of wave, but with the same axle and with the ends of the bearing type or being connected with others is the same as material, coaxial, shaft bearings, with regularity do contrast, because of the material, structure, same of ultrasonic reflection has the certain regularity, unlike other suspicious wave. Guide: the final withdrawal bearing magnetic particle inspection appraisal results shall prevail. By detection master called inspection work and the relevant personnel to consultation, for without defects identified after withdrawal, carefully analyze the causes of suspicious wave; For cracks and defects, and a comparison before and after withdrawal of bearing in the waveform, sum up experience, improve the detection accuracy, reduce inspection misjudgment rate. By adopting ', nuclear, check, calm, diagnosis, and than, as' detection to judge journal roots or unloading trough and defect of crack, the key is to make 'nuclear, fixed, diagnosis, than'. 'nuclear' is done before the inspection have a knowledge of shaft natural situation, prerequisite to determine priority inspection shaft; 'fixed' is to ensure that the probe scanning range is more comprehensive, the stress is more uniform, the detection sensitivity of a more stable extension method; 'diagnosis is an important means of judging crack injury wave, also is the key of the' seven words' detection method; 'than' is found the law of reflection wave, the effective way of summing up experience. （ Source: the resources of railway vehicle platform)