Key Research On Technology Of Internal Threadrecognition And Detection Based On Doppler

In the machinery industry of our country,the thread plays an important role in the connection and fastening of different parts,so detection of the processing thread qualified or not has become more and more important,and the current detection methods of internal thread,no matter artificial detection method or optical image method,both have the problem that the measurement accuracy are not ideal,which can not meet actual needs of production.In recent years,with the continuous development of Doppler technology,this paper proposed a new method of internal thread detection,that is internal thread detection method based on Doppler,this method has the characteristics of non-contact,high precision.The core idea of this paper is to use the laser Doppler to measure the turbulence caused by the flow of the gas through the internal thread.Through the analysis of characteristics of the turbulent flow,the corresponding thread parameters are obtained.In this paper,the main contents of the study of internal thread detection based on Doppler are as follows:First of all,the application and development of the classification of thread and detection technology is briefly introduced,and introduces the basic principle of Doppler velocity measurement,which is based on the Doppler effect,the particle velocity is known through the relationship between the frequency difference and speeds.Secondly,the turbulent characteristics of the gas formed by the inner whorl are analyzed,tracer particles are added in air,when the airflow passes through the internal thread,the gas turbulence is formed,coherent structures are in turbulent flow,and the coherent structure has the characteristics of the inevitability and reapeatbility,when the air flow the internal thread,the parameters of internal thread are included in the coherent structure,Based on the investigation of the coherent structure of the turbulent flow in the jet and scanning process,they are analyzed for the characteristics of the pulse velocity on the surface and time characteristics of the edge for the inner thread.Then,according to the detection of gas turbulence in internal thread data information needs,because the internal thread data information needs detected by the gas turbulence,sothey are designed for the signal processing system and the optical system of the Doppler,based on the double beam and double scattering light path model,the optical signal of gas turbulence is collected by using a semi external cavity double longitudinal mode laser,and DSP is used to analyze the signal.USB is used to input into the computer and the signal is processed by MATLAB.Finally,a gas laser Doppler type internal thread detector is developed,the data are processed by the box diagram method,and the standard model box line diagram of the internal screw thread is established,and the detection of the turbulence data of the internal screw thread is compared with that of the standard sample box.The results show that the method can meet the design requirements completely.Compared with the traditional method,this method has high efficiency and high speed,and provides a good experimental platform for further study of the advanced technology of thread measurement.