Research on Heat Compensation Control of Giant Magnetostrictive Material in the Micro Feed

Abstract

This paper present a Giant Magnetostrictive Actuators (GMA) which used magnetostrictive characteristics of Giant Magnetostrictive Material (GMM) and is applied on Micro displacement of precision instrument. Since GMM is influenced by temperature and the electrified coils generating magnetic field are the main sources of heat in GMA, so the temperature impacts factors on the output displacement of magnetostrictive material are analyzed firstly, and also a control method based on existing magnetostrictive actuators is redesigned, while model is established according to the relation between output displacement and voltage values. Finally a solution is proposed about heat compensation control in GMA, and also adds a water cooling system to the cavity of GMA and controls the temperature of cooling water by Single Chip Microcomputer (SCM) according to the detected temperature of magnetostrictiverod; therefore compensations for the GMAs feed displacement are allocated. Displacement closed-looped PID controls are used to tests, which can proves that the heat compensation control system of GMA can lower the impact of increasing temperature on GMMs magnetostriction coefficient and increase positioning accuracy.

Study on heat transfer characteristics and thermal error suppression method of cylindrical giant magnetostrictive actuator for ball screw preload

“…The convective heat transfer coefficient h can be calculated from equation (15), in which Nu is the Nusselt number and l is the characteristic length.…”

“…The heat transfer from the cooling cavity wall to the cooling oil is forced convection, and the convective heat transfer coefficient is also calculated from equation (15), in which the Nusselt number should be obtained firstly because it has different experimental correlation formula under different flow patterns. The most primary flow is judged by the Reynolds number calculated from equation (19).…”

“…The hollow copper tube with recirculated cooling water is used to make the GMA keep constant temperature, but the structure is complex. 15 The finite element analysis method was adopted to optimize the cooling water system of the magnetostrictive jet dispenser and the thermal characteristics was improved significantly, which lower the temperature increasement by 13.6°C and the thermal expansion displacement by 8.1 mm. Such forced water cooling method has obvious heat dissipation effect, however, the mechanical structure and thermal model are complex, and the electrical insulation is poor.…”