Design And Research On The Control System Of The Contact Petroleum Pipe Thread Measuring Instrument

The petroleum pipe is the main carrier in the process of exploitation and transportation of oil and gas,and the measurement of petroleum pipe thread is one of the main means to check the safety and reliability of the petroleum pipe.At present,themost commonly instruments used forPetroleum Pipe-Thread detection are thread gauge,length measuring instrument,coordinate measuring instrument and image measuring instrument,etc.,these instruments have many problems,such as low measurement accuracy,single measurement parameters,low measuring efficiency and easy to be influenced by environmentin actual use.So in this paper,the control system of petroleum pipe thread measuring instrument is developed by using modern microprocessor and high precision trigger probe,to realized oil pipeline automatic thread contour scanning and the measurement of pitch,tooth angle and taper parameter.The research mainly includes the following content:First,the requirements of API SPEC 5B and GB/T 9253.2-1999 standards for the measurement of oil pipe threadis analyzed,the requirements of the performance parameters of the control system is proposed,the main structure of the screw measuring instrument is designed,and the overall structure of the control system is planned.Second,the IMC3042 motion control card is used as the control core of the system,and realizes the system motion control,data acquisition and auxiliary function.According to the requirements of the control performance of the system,the drive system hardware,the measuring feedback device(the grating ruler)and the probe head are selected,and the connection circuit of hardware and motion control card is designed.Third,the software programming of the control system in the Labview programming environmentis completed,and the software system including man-machine interface,system initialization,motion control,data acquisition,data processing and auxiliary function module,etc.Fourth,the motion path of the probe is programmed by using the multi axis control function of the IMC motion control card and the switch probe signal.The program of the planning algorithm of intelligent acceleration and deceleration and the control system of the stepping closed-loop system are completed.Fifth,the process of data processing and parameter calculation are discussed.The validity of the measured data is judged by the FFT spectrum analysis,and then the data are uniformly densification by Gauss filtering and data interpolation,finally according to the piecewise curve fitting method to calculate the thread parameters.Last,the error of the measuring instrument is analyzed and compensated,and the comparative experiments of different sizes and different types of petroleum pipe threads are carried out on the basis of the prototype developed by the research group and the Mitutoyo coordinate measuring machine.The experimental results show that the measurement resultsmeet the requirements of measurement accuracy.