Integration of a silicon-based microprobe into a gear measuring instrument for accurate measurement of micro gears

Abstract

The integration of silicon micro probing systems into conventional gear measuring instruments (GMIs) allows fully automated measurements of external involute micro spur gears of normal modules smaller than 1 mm. This system, based on a silicon microprobe, has been developed and manufactured at the Institute for Microtechnology of the Technische Universität Braunschweig. The microprobe consists of a silicon sensor element and a stylus which is oriented perpendicularly to the sensor. The sensor is fabricated by means of silicon bulk micromachining. Its small dimensions of 6.5 mm × 6.5 mm allow compact mounting in a cartridge to facilitate the integration into a GMI. In this way, tactile measurements of 3D microstructures can be realized. To enable three-dimensional measurements with marginal forces, four Wheatstone bridges are built with diffused piezoresistors on the membrane of the sensor. On the reverse of the membrane, the stylus is glued perpendicularly to the sensor on a boss to transmit the probing forces to the sensor element during measurements. Sphere diameters smaller than 300 µm and shaft lengths of 5 mm as well as measurement forces from 10 µN enable the measurements of 3D microstructures. Such micro probing systems can be integrated into universal coordinate measuring machines and also into GMIs to extend their field of application. Practical measurements were carried out at the Physikalisch-Technische Bundesanstalt by qualifying the microprobes on a calibrated reference sphere to determine their sensitivity and their physical dimensions in volume. Following that, profile and helix measurements were carried out on a gear measurement standard with a module of 1 mm. The comparison of the measurements shows good agreement between the measurement values and the calibrated values. This result is a promising basis for the realization of smaller probe diameters for the tactile measurement of micro gears with smaller modules.

3D micro probing systems for gear measurements with nanometer-scale deviation

“…The holder presented can easily be screwed onto a change plate [12] [13]. The change plate forms a standard interface between tactile probes and a coordinate measuring machine (CMM).…”

“…10) [13], but the new design can also be used with other CMMs using a change plate as a standard interface. The electrical signal variations of the probe generated during the measurement process are amplified and then digitalized in the control system of the P40 by an analog-digital converter.…”

“…By way of example, the micro probing system used in this work has a full membrane and the piezoresistors are arranged in a square form [13]. Due to the fact that the longitudinal and transversal orientation on a (100)-silicon wafer have high piezoresistive coefficients [14] [15], two resistors are placed in longitudinal and two in transversal direction.…”

3D piezoresistive silicon microprobes with stacked suspensions for tailored mechanical anisotropies

“…Strain sensors are provided by piezoresistive paths realized by local diffusion doping of the membrane (Figure 1b.). Such microprobes have already been integrated into a commercial CMM (gear measuring machine P40, Klingelnberg) and a micro gear artifact has been measured for test purposes [2,15]. However, it was noticed that the stiffness of these systems in the z-direction (about 20 N·mm -1 ) is 20 to 40 times higher than in x-, y-directions (about 1 N·mm -1 ), which leads to recognizable slipping effects.…”

Dynamic Modelling and Analysis of the Microsegment Gear

“…From then on, gear transmission has entered the new era. Its theory systems on design [1,2], manufacture [3,4], measurement [5,6], standard [7], lubrication [8][9][10][11], and dynamics [12][13][14][15][16][17] of involute gear have been established gradually. As such, involute gear driving has developed to the most important transmission model.…”