Durometer according to Rockwell system

US4107978A · kind A · utility

Inventor

• Alfred Ernst · Lugano, CH

Key dates

• Filing date: Feb 28, 1977
• Grant date: Aug 22, 1978
• Expiry date: Feb 28, 1997

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B23Q17/20
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

An apparatus for testing the hardness of a workpiece has a lower structure having a surface defining a reference plane from which can project an axially displaceable penetrator. A preload spring biases the penetrator with a relatively small preload force into a position projecting from the plane. Upper structure adapted to receive an applied load force directed axially toward the lower structure is displaceable through a long axial distance between an upper rest position relatively far from the lower structure and a lower position directly abutting the lower structure. Intermediate structure is axially displaceable between the upper and lower structures toward the upper structure from a lower position resting on an abutment fixed on the upper structure. This intermediate structure is spaced axially a relatively short distance from the penetrator in the lower position of the intermediate structure and upper position of the upper structure so that displacement of the upper structure down from its upper rest position first engages the intermediate structure with the penetrator and thereafter engages the upper structure directly with the lower structure. A load spring between the inter…