Hardness testers have many types, in which the plunging hardness tester is applied the most. Following is a brief introduction of plunging hardness testers according to test method principle.
Frame is the supporting part for all assembly units of the hardness tester, and it has good rigidity and stability.
2. Force Loading Structure
Force loading structure consists of a device producing test force, a device loading and unloading test force and a device controling appliment of test force etc.
The device producing test force includes following types:
(1) Direct force loading
It is a type that test force directly load weights on the principle axis. The hardness tester seems heavy and large. However, this kind of producing test force is very accurate and deduces the error made by lever structure. Therefore, it is mainly applied in standard and benchmark hardness testers.
(2) Lever loading
The lever loading type(there are single lever and double lever two kinds) hardness testers are usually used on site or in test rooms. The advantage of this type is that the small and light weight would form test force through enlarging the lever. The common Rockwell hardness testers usually apply single lever loading (such as HR-150A, HR-150DT, HR-150F...) because its maximum test force is only 1470N(150 kgf). The Brinell hardness testers would usually apply double lever loading (the typical model is HB-3000, HB-3000B types) in order not to make the lever too heavy , because its maximum test force is 29.421kN (3000kgf).