Nano surface interaction and model of vibrating probe

Abstract

The high precision measurement has been a focus in the field of manufacturing and microelectronics in this year. The micro/nano probe for coordinate measuring machine (CMM) acts as a key characteristic because it can measure the high-aspect-ratio components with high precision. Various micro/nano-CMM probes with different principles and different structures have been developed in the last decade. However, most of these studies focused on the sensing principle and measurement methods. There is little research on the behavior of the surface interaction between the probe tip and the workpiece. And the measurement accuracy and reliability of the current probe, especially those of the low stiffness probe, are limited by interaction forces including capillary force, van der Waals force, electrostatic force and Casimir force. Therefore, it becomes a challenge to reduce the effect of the surface interaction forces for the Micro/nano CMM probe. A new trigger probe based on the vibrating principle is analyzed and an optimal method for the appropriate vibrating parameters is presented in this paper. The structure and principle of the probe are briefly described in the first part. In this system, a tungsten stylus with a tip-ball is fixed to the floating plate, which is supported by four L-shape high-elasticity leaf springs. The fiber Bargg grating (FBG) sensors are used in the probe for micro-CMM due to their superiority in t of small size, high sensitivity, large linear measuring range, immunity to electromagnetic interference, and low cost. One end of FBG is attached to a floating plate, and the other end to a retention plate which is connected with the piezoelectric ceramic actuator (PZT). The probe is driven by the PZT vibrating. Assuming that the driving forces can offset the surface interaction forces, then the probe can be described as a forced vibration model of the spring oscillator. Therefore, the equivalent model of the probe is set up. In the second part, a relationship between the vibration parameters of the probe and the surface interaction can be confirmed. Through theoretical analysis and numerical simulation, the appropriate vibrating parameters including resonance amplitude, velocity and frequency of the probe are designed, which can offset the surface interaction forces. In the third part, a probe is designed based on the above theories and an experimental system is set up to verify its rationality. The results show that the resonant micro/nano probe after optimizing its parameters can effectively reduce the influence of surface forces and improve the measurement accuracy.