Patent ID: 6354148
Filing Date: 2002-03-12
Classification: G01N

Abstract:
A rebound-type hardness tester comprising:a measuring cylinder comprised of a body having an axial passage; a first light projecting hole formed in the body of the measuring cylinder; a first light receiving hole formed in the body of the measuring cylinder; a first light source for projecting light through the first light projecting and first light receiving holes; a first photodetector device for receiving light projected from the first light source and passing through the first light projecting and first light receiving holes; a second light projecting hole formed in the body of the measuring cylinder at a preselected distance from the first light projecting hole; a second light receiving hole formed in the body of the measuring cylinder; a second light source for projecting light through the second light projecting and second light receiving holes; a second photodetector device for receiving light projected from the second light source and passing through the second light projecting and second light receiving holes; an indenter hammer mounted within the passage of the measuring cylinder body for undergoing axial movement therein in a forward direction to impact a specimen and in a rearward direction away from the specimen immediately after the impaction, and for temporarily blocking the light emitted from the first and second light sources and received by the first and second photodetector devices, respectively, during respective movement in the forward and rearward directions; a spring member for generating a spring force to accelerate the indenter hammer in the forward direction to impact the specimen: measuring means for measuring a first time value corresponding to a time elapsed between the blocking of the light to the first photodetector device and the blocking of the light to the second photodetector device by the indenter hammer during movement thereof in the forward direction, and for measuring a second time value corresponding to the time elapsed between the blocking of the light to the second photodetector device and the blocking of the light to the first photodetector device by the indenter hammer during movement thereof in the rearward direction; calculating means for calculating an impacting velocity of the indenter hammer corresponding to a velocity of the indenter hammer immediately before the impact thereof with the specimen in accordance with the first time value measured by the measuring means and the preselected distance between the first and second light projecting holes, and for calculating a rebounding velocity of the indenter hammer corresponding to a velocity of the indenter hammer immediately after the impact thereof with the specimen in accordance with the second time value measured by the measuring means and the preselected distance between the first and second light projecting holes; and processing means for calculating a hardness of the specimen in accordance with the impacting velocity and the rebounding velocity calculated by the calculating means.