For meeting the requirements of high-precision and high-speed in on-line detection for strip and plate’s internal defects, in the paper, based on elaborating methods and principle of conventional ultrasonic testing, the research status of traditional ultrasonic testing technology and non-contact ultrasonic testing techniques, there analysis and discuss the problems and causes in the process of detection. In the end, the trend of development is given.
To obtain a new method to improve hydrodynamic bearing carrying capacity, hydrodynamic journal bearing’s characteristics as well as the current study direction are analyzed. According to the calculation of general cylindrical hydrodynamic journal bearing, the mathematic model for sinusoidal surface hydrodynamic bearing’s carrying capacity is established. It is used to calculate, analyze and compare these two bearings’ carrying capacity with example. The bearing, which has the characteristic of sinusoidal surface, has stronger carrying capacity than general cylindrical hydrodynamic bearing. What’s more, the improvement is more obvious when the number of waves is 3, also it has wider carrying area. Compared with other journal bearings, the journal bearing with sinusoidal surfaces has stronger carrying capacity, smaller friction moment and longer life-span. Therefore, it has extensive prospect.
Friction between the guideway and the bench of large-type CNC lathe will cause thermal deformation of the guideway, which causes processing error of the lathe,thereby reduces machining precision of the workpiece. The authors establish the mathematical model of temperature field and thermal deformation of the guideway in the work process, numerically simulate the guideway thermal characteristics by ANSYS finite element analysis software, and obtain the distribution regularities of temperature field and thermal deformation and their major influencing factors, which provide a theoretical basis for optimizing design and thermal error compensation design of the lathe guideway.
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