Metrology Calibration and Maintenance of Leeb Hardness Tester

The multi-function leeb hardness tester is a new type of hardness testing instrument, which is designed according to the latest Leeb hardness testing principle using the most advanced microprocessor technology.

The durometer gauge is suitable for the rapid hardness test of metal materials, and has the characteristics of high test accuracy, small size, easy operation and convenient carrying; The HL values measured in different directions can be automatically converted into Brinell, Rockwell, Vickers, shore and other hardness values, and printed and recorded.

We believe that the Leeb hardness tester can be seen in major factories, so do you know the steps of its measurement and calibration method?

Ⅰ. Correctly use the Leeb hardness tester to measure the workpiece

DOHP200 touch screen Leeb hardness tester is a new type of hardness testing instrument, which is designed according to the latest Leeb hardness testing principle using the most advanced microprocessor technology.

Dohp200 Leeb portable hardness tester has a 3.8-inch touch LCD screen with rich display contents and touch screen operation. It can directly switch materials, directions, conversion standards, statistical points, and other contents on the measurement interface. It can automatically adapt to a variety of impact devices. It is suitable for rapid hardness tests of metal materials. It has the characteristics of high test accuracy, easy operation, and convenient carrying; The HL values measured in different directions can be automatically converted into Brinell, Rockwell, Vickers, Shore, and other hardness values, and printed and recorded.

When using the DOHP200 Leeb hardness tester, pay attention to the following matters to improve the measurement efficiency and accuracy. The following is a description of the Leeb hardness tester equipped with a D-type impact device.

1. During the preparation of the sample surface, the influence on the surface of the sample due to cold and thermal processing should be avoided as much as possible.

2. The test surface of the sample should preferably be flat, the test surface should have metallic luster, and there should be no oxide scale and other dirt.

The surface roughness of the test surface Ra≤1.6

3. Specimens must be of sufficient mass and rigidity. If the mass and rigidity are insufficient, displacement or bouncing will occur during the impact of the test, which may cause large measurement errors.

Generally speaking, samples with a mass of ≥5kg can be tested directly; samples with a mass of 2-5kg should be tested after being fixed by appropriate clamping means; samples with a mass of 0.05-2kg should be tested after coupling and connection; samples with a mass <0.05kg The sample should not use the Leeb hardness test method for hardness test.

The coupling method is: prepare a flat and clean plane on the back of the test surface of the sample as the supporting surface, spread a little coupling agent (can be replaced by industrial vaseline), and press it to the plane of the supporting seat (the mass of the supporting seat should be greater than 5 kg, It can be replaced by the standard Leeb hardness block support surface) and fit together.

4. The specimen shall have sufficient thickness and sufficient surface homogeneous layer. Using the D-type impact device, the thickness of the sample should not be less than 5mm, and the surface homogeneous layer (or surface hardening layer) should not be less than 0.8mm. If the hardness of the base material is to be accurately measured, it is best to remove the case hardened layer by machining.

5. When the test surface of the sample is not flat, the surface curvature radius of the test point and the adjacent area should be greater than 30mm. And should choose the appropriate support ring.

6. The specimen shall not be magnetic. Magnetism will seriously interfere with the work of the impact device in the impact device, resulting in inaccurate test results.

7. If the direction of the measured workpiece is not 90 degrees, the measured value should be corrected and compensated for the direction;

8. Measure the workpiece at least 3 times, and calculate the average value. If the difference between the hardness values exceeds 20HL, the number of tests should be increased and the average value should be calculated;

9. When measuring the workpiece, it is necessary to convert the hardness value of other scales, such as HRC, the material properties of the workpiece should be determined, and the corresponding material conversion should be selected on the Leeb hardness tester, otherwise it will cause conversion deviation;

Ⅱ. The maintenance and repair of Leeb hardness tester

The portable Leeb hardness tester is widely used in practical applications, which brings great convenience to people. But when applying the Leeb hardness tester, we should pay attention to its maintenance.

1. After using the Leeb hardness tester for 1000-2000 times, use a nylon brush to clean the guide sleeve and impact body of the impact device. When cleaning the catheter, first unscrew the support ring, then take out the impact body, and use the nylon brush to reverse it. Rotate into the tube in the clockwise direction, pull it out at the end, repeat this for 5 times, and then install the impact body and the support ring;

2. After the Leeb hardness tester is used, the impact body should be released;

3. It is strictly forbidden to use various lubricants in the impact device.

4. When the measurement result is unstable, check whether the impact body steel ball is seriously worn, and the impact steel ball should be replaced in time to avoid affecting the measurement result.

5. After use, the Leeb hardness block should be wiped and maintained with oil paper to prevent the hardness block from rusting;

6. The connecting wire of the impact device is connected to the terminal head of the host computer and the three-pin position of the impact device should be avoided to be bent, so as to prevent the connecting wire from being bent for a long time and have poor contact.

7. When the Leeb hardness tester is not used for a long time, if it is powered by dry batteries, the battery should be taken out to prevent battery leakage from damaging the host. If the rechargeable battery supplies power, the battery shall be charged and discharged regularly. Generally, it shall be charged and discharged once every three months to prevent the battery from being damaged by over discharge.

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