Research On Spring Flat Steel Detection Technology Based On Ultrasonic Shear Wave

Spring flat steel is an important material widely used in the industrial system and people's daily life.The reliability of spring flat steel performance plays an important role in ensuring the safe operation of production and people's lives and property.Due to the existence of tiny uncontrollable factors in the production craftwork and production process of the spring flat steel,there are minor defects in the spring flat steel product.The high frequency alternating stress and large load under the service environment will cause stress concentration around minor defects in the spring flat steel,and the stress concentration causes the small defects to expand and cause the deterioration of the mechanical properties of the spring flat steel until the fracture is damaged.Therefore,non-destructive testing of minor defects before the service of the spring flat steel is a very necessary task.The conventional ultrasonic detection technology has the characteristics of high detection energy,large detection depth,high detection sensitivity,and high detection accuracy.Specific detection methods include: transmission method,pulse reflection method,time of flight diffraction method,etc.Phased array ultrasonic detection technology is emerging in recent years ultrasonic detection technology,based on the principle of phased array,integrates the rapid development of materials technology,electronic control technology,and digital signal processing technology,becoming a hot technology with rapid development and promising prospects.In order to develop a non-destructive testing technology that is more suitable for industrial production of flat spring steel,this project carried out research on the method of fast non-destructive testing of defects in spring flat steel based on conventional ultrasonic testing technology and phased array ultrasonic testing technology.Firstly,in order to make the ultrasonic multiple-reflection shear wave detect the spring flat steel length as long as possible by one shot,the influence of the width of the transverse beam of the oblique incident spring flat steel on the detection signal is analyzed from the propagation path of the transverse wave acoustic beam and the propagation of the acoustic beam;The theoretical formula deduces the influence of the frequency on the width of the beam detected by the shear probe,and optimizes the frequency of the probe for testing.In addition,the effect of probe slope on testing various defects in spring flat steel was analyzed through experimental methods,and the selection method of probe slope was determined.Secondly,in order to improve the positioning accuracy of the multi-waves of the transverse wave.The calculation method of the horizontal distance from the defect to the incident point of the probe and the depth of the defects are proposed according to the propagating path of the transverse wave obliquely entered spring flat steel to the defect and the case where there are slight differences among propagation spans of the transverse wave.According to the proposed defect location calculation method and test data,the horizontal distance from the defect to the incident point of the probe and defect depth are calculated,and a high positioning accuracy is obtained.In order to improve the detection efficiency,the transverse width of the ultrasonic transversal wave beam was analyzed,an efficient scanning method for spring flat steel which can be applied to automatic detection was put forward.Thirdly,the imaging experiment of all types of defects in spring flat steel method was executed in the transverse wave fan sweeps mode.The trend of the flaw echo amplitude was analyzed at each scanning angle when the probe is at different distances from the defect;the variation characteristics of the detection signal amplitude of each defect was summarized under each scanning line,and one identification method of internal defects and surface defects in spring flat steel was proposed based on the phased array ultrasonic transverse wave scanning detection technology.The multi-reflection shear wave detection technology of the spring flat steel presented in this study combines the advantages of high efficiency and reliability,and provides an effective non-destructive testing method for the quality evaluation of spring flat steel products;The combination of multiple reflection shear wave inspection technology and ultrasonic phased array technology can rapidly inspect and image defects in flat steel,providing important technical support for quality control of spring flat steel and production technology innovation.