Low velocity operation characteristics of servo platform of FRP pipe thread grinding machine

In order to realize automatic trapezoidal thread manufacturing of large diameter fiber reinforced plastic (FRP) pipe, the numerical control machine tool, which can implement pre-taper manufacturing and thread grinding, is designed. This paper introduces the mechanical structure and the composition of the open numerical control system. A three-loop control model with friction effects is built for the radial axis servo platform which runs at low speed. The friction model of the motion platform is fitted by experiment data, and the friction dynamics simulation for low speed operation characteristics of speed loop and position loop is conducted. The influence of none-linear friction on dynamic characteristics of the servo platform is researched. The feedforward friction compensation control is applied to eliminating the phenomenon of “dead zone” and “flat top” caused by friction, and the low speed performance and the tracking accuracy are improved, which realizes the thread grinding of large diameter high-pressure FRP pipes with high accuracy.