GB280292A - Improvements in, or relating to, devices for testing the hardness of metals - Google Patents

Abstract

280,292. Firth, J. C. B., and Dickinson, F. G. Aug. 12, 1926. Testing hardness of metals.-Comprises particular constructions of apparatus of the type in which an impression is made by an indentor through the medium of a spring under a load, the spring being located in a cylinder slidable axially in a fixed or sliding head in a standard, without the administering of a blow to the indentor. The cylindrical body b is fixed or slidably mounted on a standard a. Within the body b is slidably mounted a cylinder carried by a screw e passing through a closure member f on the head b. A ball-thrust bearing h is provided and a ratchet wheel k is fixed to the screw. Between a spigot n threaded into the cylinder c and a nose q threaded into a slidable inner cylinder b is located a spring p. The nose p carries the indenting member s. One side of the cylinder c is provided with a groove w in which is a detent x mounted on a pivot z and pressed by a spring 2 so that the upper end tends to engage and prevent rotation of the wheel k. In use after the member s is engaged with the metal by advancing the screw e, the. spring is compressed and the cylinder q moves upwards within the cylinder c until a recess comes opposite a notch 6 on a member 4 on the arm x whereupon the spring z presses the arm into engagement with the teeth of the wheel. On rotating the screw reversely the cylinders are retracted together. The spigot n may be adjusted to place any given load in the spring being sealed by a set-screw in adjusted position. A modification is described in which the arresting of the movement of the cylinders is accomplished by electromagnetic means. Means are also described for indicating the load on the spring.