Device for measuring hollow cylinder surfaces

Apparatus for measuring the inner surface of a generally cylindrical bore, comprising

• (a) a housing adapted for insertion within the bore;
• (b) clamping jaw means for clamping said housing within the bore;
• (c) a longitudinal measuring arm rotatably connected with said housing for rotation about, and extending longitudinally of, the bore axis;
• (d) first drive means for rotating said arm relative to said housing;
• (e) a measuring head connected with said measuring arm for axial displacement along the length thereof;
• (f) second drive means for axially displacing said measuring head relative to said arm;
• (g) sensor means connected for radial displacement relative to said measuring head;
• (h) leaf spring means connected at one end with said measuring head, the free end of said leaf spring means being movable in the direction of the longitudinal axis of said sensor means to bias said sensor means radially outwardly relative to said head toward a position in engagement with the inner surface of the bore;
• and
• (i) foil strain gauge means responsive to the deflection of said leaf spring for generating an electrical signal corresponding with the radial displacement of said sensor means relative to said measuring head, thereby to afford an indication of the inner surface contour of the bore.