Salutron HardyTest HARTIP 1800, Руководство по эксплуатации

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1. Forewords
1.1. History
The Leeb measuring method was first brought into measurement technology in 1978. It
is defined as the quotient of an impact body’s rebound velocity over its impact velocity,
multiplied by 1000. Harder materials produce a higher rebound velocity than softer
materials. For a specific group of material (e.g. steel, aluminum. etc.), Leeb hardness value
represents a direct relationship to its hardness properties. For ordinary metal, conversion
curves of hardness HL versus other standard static hardness (HB, HV, HRC, etc.) are
available, enabling you to convert HL into other hardness values.
1.2. Leeb Hardness Test (definition)
An impact body with a spherical test tip made of tungsten carbide is propelled against the
sample surface by a spring force and then rebounds back. At a distance of 1mm from the
sample surface, the impact and rebound velocity of the impact body are measured by the
following method: A permanent magnet embedded in the impact body, when passing
through the coil in its coil holder, induces in the coil an electric voltage proportional to the
velocities of the magnet. Leeb hardness is expressed by the following formula:
1000 *
Vi
Vr
HL

Where: HL is Leeb Hardness
V
r
is the rebound velocity of the impact body
V
i
is the impact velocity of the impact body
The voltage characteristic of output signal, when the
impact body passes through the induction coil is illustrated in the following figure:
Voltage characteristic of output signal
A Leeb’s Hardness Tester measures the hardness of sample material in terms of Hardness
Leeb (HL), which can be converted into other Hardness units (Rockwell B and C, Vicker,
Brinell and Shore D).
1.3. Notation of Leeb’s Hardness
When measuring the hardness of a sample material using the traditional static hardness
testing method, a change of applied pressure will result in a change in the hardness
reading. This will also happen during a Leeb’s Hardness test when one changes the
impact device. In hardness measurement of the same test sample with different impact
devices, the Leeb’s hardness values obtained will vary.
For example: 720HLD≠720HLC
Because different converting curves are obtained from different impact devices, when
converting hardness HL into another hardness values, the notation for the converted
hardness value should include the impact device used.