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How to use the Leeb hardness tester
Jan 10, 2019

How to use the Leeb hardness tester

The Leeb hardness tester is a test equipment. The principle is that with the development of single-chip technology, in 1978, Dr. Leeb of Switzerland proposed a new method of measuring hardness. The basic principle is that it has a certain quality impact body. Under the action of a certain test force, the surface of the sample is impacted, and the impact velocity and the rebound velocity at 1 mm from the surface of the specimen are measured. The electromagnetic principle is used to induce a voltage proportional to the velocity.

So what is the use of the Leeb hardness tester?

1. Preparation and inspection before use

Test sample surface requirements

The condition of the surface of the specimen shall comply with the relevant requirements in Table 3.

The surface temperature of the crucible sample should not be too high and should be less than 120 °C.

The surface roughness of the crucible sample should not be too large, otherwise it will cause measurement error. The surface to be tested of the sample must be exposed to metallic luster and be flat, smooth and free of oil.

重量 sample weight requirements: for heavy samples larger than 5kg, no support is required; test pieces with weight of 2-5kg, test pieces with overhanging parts and thin-walled test pieces are applied to support during testing to avoid impact The force causes the specimen to deform, bend and move. For medium-sized specimens, they must be placed on a flat, strong surface. The specimens must be placed in a smooth position without any sloshing.

☼ Curved specimen: The test surface of the specimen is preferably flat. When the measured surface radius of curvature R is less than 30mm (D, DC, D+15, C, E, DL type impact device) and less than 50mm (G type impact device), the test shall use a small support ring or a profiled support. ring.

The enamel sample shall have sufficient thickness and the minimum thickness of the sample shall comply with Table 3.

☼ For specimens with a hardfacing layer, the depth of the hardened layer shall comply with Table 3.

☼ coupling

—— For light samples, it must be tightly coupled with a strong support. The two coupling surfaces must be flat and smooth, and the amount of coupling agent should not be too much. The test direction must be perpendicular to the coupling plane;

——When the sample is a large-area plate, long rod, and bent piece, even if the weight and thickness are large, the test piece may be deformed and unstable, resulting in inaccurate test values, so it should be reinforced or supported on the back side of the test point.

2. Measurement

1 measurement

☼ Before the measurement, the instrument can be inspected by using the random standard Leeb hardness block. The indication error and repeatability should not exceed the requirements of Table 5.

2 start

插入 Insert the impact device plug into the impact device socket at the top of the instrument.

☼Press the [Power On] key, the power is turned on and the instrument enters the measurement state.

3 loading

Pushing the loading sleeve downwards locks the impact body; for the DC impact device, the loading rod can be sucked onto the test surface, and the DC impact device is inserted into the loading rod until the stop position, at which point the loading is completed.

4 positioning

Pressing the impact device support ring against the surface of the sample in the selected measurement direction, the impact direction should be perpendicular to the test surface;

5 measurement

☼Press the release button on the top of the impact device to test. At this time, the sample, the impact device, and the operator are required to be stable, and the direction of the force should pass through the axis of the impact device.

Five measurements are typically taken at each measurement site of the helium sample. Data dispersion should not exceed ±15 HL of the average.

距离 The distance between any two indentations or the distance from the center of any indentation to the edge of the specimen shall comply with Table 6.

☼ For a specific material, to accurately convert the hardness value of the Richter to other hardness values, a comparative test must be performed to obtain the corresponding conversion relationship. The method is: the test is carried out on the same sample by using a qualified Leeb hardness tester and a corresponding hardness tester. For each hardness value, five points of hardness were measured uniformly around three or more hardness indentations to be converted, and the hardness average curve and the corresponding hardness average value were respectively used as corresponding values to make a hardness comparison curve. The curve should include at least three sets of corresponding data.

6 Read the measured value.

The average of multiple valid test points is used as a measurement test data.

7 printout results.

See 6.3.3 and 6.6 for specific settings.

8Press the {} key to shut down.

9 test results representation method

☼ The hardness value is shown before the Richter hardness symbol HL, and the impact device type is shown after HL. For example, 700HLD means that the Leeb hardness value measured by the D-type impact device is 700.

其它 For other hardnesses converted in Leeb hardness, the corresponding hardness symbol should be attached before the Richter hardness symbol. For example, 400 HVHLD indicates that the Vickers hardness value measured by the D-type impact device is 400.

Note: The HL values measured for different impact device types are different, for example 700HLD ≠ 700HLC.

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