Measuring apparatus for measuring the roll gap in gauge-controlled roll stands

Claim 1

Roll gap measuring apparatus comprising two relatively movable components, a measuring surface on each component, wherein said two components engage one another in a telescoping manner, the inner component having a chamber part-filled with a fluid whose density is substantially constant during temperature changes, and being one of said measuring surfaces, and the outer component having a cup-shaped configuration with an annular cover at one end to permit an elongated projection of the inner component to project outwardly from said outer component, said outer component further including a rod attached to a closed end thereof, said rod being immersed in said fluid contained in said inner component and bearing the other of said two measuring surfaces, a pulsed ultrasonic signal transmitter and a sound receiver located on the same measuring surface, and measuring means for measuring the time taken for sound pulses to travel between said measuring surfaces, means for allowing said fluid to freely expand if the depth of penetration of said immersed rod increases to maintain said constant pressure of said fluid, said fluid container includes a base wall and said signal transmitter and sound receiver are located adjacent thereto, and said measuring surface on said immersed rod is constructed as a spherical reflector for pulses emitted by said transmitter.