Highly accurate force and distance measuring head which determines broad range of physical properties

摘要

A measuring device determines the force acting on its measuring head caused by a defined head movement, which is occasioned by a drive system. The novel assembly includes a piezoelectric actuator, which is combined with a unit (18) with larger feed resolution, and additional units (17), or the head drive alone. To the measurement head drive, devices are connected which measure the feed movement (16) and the force exerted (15). Also claimed are uses of the device in the measurement of: hardness, viscosity, compression, stress-strain, adhesive-, static-, sliding- or rolling frictional forces, Young's modulus of elasticity, coating thickness, failure criteria or transverse modulus of elasticity. Pref. the head drive is a combination of units with higher-, smaller- and/or intermediate feed resolutions, pref. connected in series. The unit with smaller feed resolution is an electromagnetic drive. One of the units with greater or intermediate feed resolution is a piezoelectric drive. The force measurement device (15) is located between measuring head tip (20) and the adjacent measuring head drive unit. It is interchangeable and is arranged axially with, or parallel to, the head drive. The feed measurement device is rigidly connected to the measurement head, and it too, may be interchangeable. Feed measurement is performed by an optical system, e.g. an encoder with a slotted disc, light source and light detector. Alternatively it is a laser system. The feed measurement is made by a non-contact detection system employing: microwaves, resistance strain gauge measurement, capacitance, inductance or any form of resonance.