The Control System Design Of Digital Thread Function Size Measuring Instrument

The position of thread with the relevant elements has a great impact on the threaded connection, such as quality, reliability, service life and so on. The effect axis of thread is an important indicator of the location accuracy. At present, most of the thread detection technology is concentrated in the measurement of single parameters, and the measurement theory and method of the effect axis of thread, which combined effects of multiple parameters is rarely involved. Digital thread function size measuring instrument has a standard tooth type measuring end(standard threaded axial slices) which can fluctuate in four directions, and a rotary-type space measurement system. Tooth type measuring end remain engaged with the measured thread during the measurement and move in a standard helix which consistent with the measured thread. TESA can reflect the pose changes of the standard tooth type measuring end which changing with the measured thread's surface topography. The pose changes of standard tooth type measuring end express the comprehensive effect of measured thread in the tested section. We use some of the data processing means to get a set of tooth type measuring end's pose, which express the overall effect of the measured thread with tooth type measuring end. After digitizing, we can truly measure the effect axis of thread.According to the measurement principle, this paper optimized the control system on the basis of the original control scheme, a range of techniques were employed, including communication optimization, motion control optimization, go-home optimization, data acquisition optimization, re-commissioning the TESA signal acquisition board. And based on piecewise linear interpolation algorithm quantify digital value to displacement in PC. And a new software system has been designed, including go-home control, calibration, status monitoring, data display, single-axis motion control, mechanical scanning, spiral motion, feedback command status bar, etc. can achieve real-time monitoring states of the measuring instrument and screwing with the measured thread automatically. And the user can choose a variety of movement patterns, including absolute and relative motion mode, fast and low manual control and measuring linkage.This paper presents a lot of experiments to verify the reasonableness of the control system. According to the experimental results, TESA micrometer maximum error is less than 1.5?m,positioning error of go-home is less than 1?m, single-axis positioning error relate with motion parameters(Such as speed, displacement, etc.). When the motion axes run faster and short distance(<5mm), the positioning error of around 4?m. We can choose the best motion parameters by experiment, control the positioning error within 2?m. Each module of existing control systems can meet the design requirements and the measurement needs.