Strain gauge test frame for weighing machine - has steel plate with deposited gauges and surface mounted electrical circuits attached to elastic bar

摘要

An elastic metal bar (1) has one end embedded in a fixed structure (9), while the other is free to respond to a force to be measured. A thin steel plate (8), is secured to one face of the bar, but with a very small clearance, obtained by distance plates (10a) (10b), to avoid friction between the two surfaces. Extension gauges (2-7), and associated electrical circuits comprising a Wheatstone bridge, are deposited by a screen process as a layer on the surface of the steel plate (8). The thin steel plate is of less than 1 mm thickness to avoid inertial effects, and of a composition such that its mechanical properties remain unchanged after heating to 900 degrees Celsius. When the force to be measured is applied, the resistance of the extension gauges is changed and this causes the Wheatstone bridge to produce a signal proportional to the force exerted. ADVANTAGE - Improved elasticity and high resistance to mechanical shock.