Measuring and testing – Hardness – By penetrator or indentor
Patent
1974-10-17
1976-06-29
Gill, James J.
Measuring and testing
Hardness
By penetrator or indentor
G01N 348
Patent
active
039657272
ABSTRACT:
An instrument for measuring and indicating the hardness of such compressible materials as plastic foam compositions, including a frame adapted to be conveniently manipulated by the user, an indentor movably mounted in the frame and resiliently biased downwardly relative to the frame, the indentor having a downwardly directed thin elongated convex marking edge projecting through an elongated slot formed in a lower plate of the frame. The plate has a lower contour matingly congruent with the contour of the sample to be tested, and its relatively large area serves to limit downward movement of the frame toward the sample; thus, the length of the line of penetration of the indentor marking edge into the sample becomes a measure of the density of the sample. Desirably the marking edge is preliminarily colored by a suitable material, such as being rolled on a conventional stamp inking pad; after testing, the length of the colored line on the sample, suitably calibrated, is a measure of the hardness of the sample and, indirectly, of its density. A longitudinal scale is provided on the frame for convenience in measuring the length of the indented line. The instrument includes calibration means, comprising a horizontally disposed calibration bar which may be selectively adjustable in position relative to the frame, and which serves as the upper abutment for resilient means in the form of compression springs bearing downwardly on the indentor. Limit means are provided on the indentor for establishing the lower rest or inoperative position of the indentor, including a pair of spaced legs fixed to the blade near opposite ends thereof and extending upwardly through frame openings, the legs having upper enlargements abuttable downwardly against the frame adjacent to the openings.
REFERENCES:
patent: 1802685 (1931-04-01), Trier
patent: 1875862 (1932-09-01), Fair
patent: 2436435 (1948-02-01), Kent
patent: 2656716 (1953-10-01), Hoggatt
patent: 2976732 (1961-03-01), Hautly
Ciarlante Anthony V.
Gill James J.
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