Qiangxian Huang

An analogue contact probe using a compact 3D optical sensor for micro/nano coordinate measuring machines

This paper presents a new analogue contact probe based on a compact 3D optical sensor with high precision. The sensor comprises an autocollimator and a polarizing Michelson interferometer, which can detect two angles and one displacement of the plane mirror at the same time. In this probe system, a tungsten stylus with a ruby tip-ball is attached to a floating plate, which is supported by four V-shape leaf springs fixed to the outer case. When a contact force is applied to the tip, the leaf springs will experience elastic deformation and the plane mirror mounted on the floating plate will be displaced. The force–motion characteristics of this probe were investigated and optimum parameters were obtained with the constraint of allowable physical size of the probe. Simulation results show that the probe is uniform in 3D and its contacting force gradient is within 1 mN µm − 1. Experimental results indicate that the probe has 1 nm resolution, ± 10 µm measuring range in X − Y plane, 10 µm measuring range in Z direction and within 30 nm measuring standard deviation. The feasibility of the probe has been preliminarily verified by testing the flatness and step height of high precision gauge blocks.

Design of a large-scanning-range contact probe for nano-coordinate measurement machines

A new high-precision contact probe with a large scanning range is proposed and validated, which is able to measure miniature components on a micro/nano-coordinate measuring machine (CMM). This scanning probe is composed of a fiber stylus with a ball tip, a mechanism with a wire-suspended floating plate, a two-dimensional (2-D) angle sensor, and a miniature Michelson linear interferometer. The stylus is attached to the floating plate. The wires experience elastic deformation when a contact force is applied, and then the mirrors mounted on the plate are displaced; the displacements can be detected by corresponding sensors. According to industrial demands, such as scanning range, resolution, equal stiffness, contact force, and probe size, several constrained conditions are established, and the optimal structure parameters of the probe are selected. Each component of the probe is designed, fabricated, and assembled in this research. Simulation and experimental results show that the probe can achieve uniform stiffness, ±20-μm scanning range, and 1-nm resolution in x, y, and z directions. The contact force is about 40 μN when the tip ball is displaced 20 μm. It can be used as a contact and scanning probe on a micro/nano-CMM.

Design of an analogue contact probe for nano-coordinate measurement machines (CMM)

A new high precision analogue contact probe with long measurement range that is able to measure miniature components on a micro/nano-coordinate measuring machine (CMM) is proposed. This analogue probe is composed of a fiber stylus with a ball tip, a mechanism with a wire-suspended floating plate, a two-dimensional angle sensor and a miniature Michelson linear interferometer. The stylus is attached to the floating plate. The wires experience elastic deformation when a contact force is applied and then the mirrors mounted on the plate will be displaced, which displacements can be detected by two corresponding sensors. Each component of the probe is designed, fabricated and assembled in this research. Base on the design requirements and stiffness analysis of the probe, several constrained conditions are established, and optimal structure parameters of the probe are worked out. Simulation and experimental results show that the probe can achieve uniform stiffness, ±20μm measurement range and 1nm resolution in X, Y and Z directions. The contact force is less than 50μN when the ball tip is displaced by 20μm. It can be used as a contact and scanning probe on a Micro/Nano-CMM.

Fabrication and Study of Micro Monolithic Tungsten Ball Tips for Micro/Nano-CMM Probes

Micro ball tips with high precision, small diameter, and high stiffness stems are required to measure microstructures with high aspect ratio. Existing ball tips cannot meet such demands because of their weak qualities. This study used an arc-discharge melting method to fabricate a micro monolithic tungsten ball tip on a tungsten stylus. The principles of arc discharge and surface tension phenomenon were introduced. The experimental setup was designed and established. Appropriate process parameters, such as impulse voltage, electro discharge time, and discharge gap were determined. Experimental results showed that a ball tip of approximately 60 µm in diameter with less than 0.6 µm roundness error and 0.6 µm center offset could be realized on a 100 µm-diameter tungsten wire. The fabricated micro ball tip was installed on a homemade probe, touched by high-precision gauge blocks in different directions. A repeatability of 41 nm (K = 2) was obtained. Several interesting phenomena in the ball-forming process were also discussed. The proposed method could be used to fabricate a monolithic probe ball tip, which is necessary for measuring microstructures.

Elastic mechanism design of a CMM contact probe

The measurement of miniature components with a micro- or nano-coordinate measuring machine requires a high precision contact scanning probe. The elastic mechanism of low stiffness is a major component of the contact scanning probe. A new elastic mechanism is analyzed by the theory of elasticity and finite element analysis in this paper. It is to realize the probe’s mechanical behavior and stiffness when designing an elastic mechanism for a contact scanning probe. The contact scanning probe is composed of a tungsten stylus with a ruby ball tip, a mechanism of floating plate suspended by four V-shaped leaf springs, and a 3D optical sensor. The leaf spring experiences elastic deformation when a contact force is applied. Uniform stiffness model is analyzed. Simulation and experimental results verify the correctness of the analysis.