1. Overview of Leeb hardness testing technology
The Leeb hardness testing technology is a new technology developed internationally after the hardness of cloth, Rockwell, Vickers, and Shore. The Leeb hardness tester manufactured according to the Leeb hardness theory has changed the traditional hardness testing method. Because the hardness sensor is as small as a pen, you can hold the sensor in the production site to directly test the hardness of the workpiece in various directions, so it is difficult for other desktop hardness testers to do. Since the birth of the Leeb hardness tester, it has become more and more popular in the world. In China, the Leeb hardness technology has been initially developed. In order to promote this advanced technology, with reference to international standards, the Ministry of Machinery Industry has promulgated the "Leech hardness tester technical conditions ZBN7l 010-90", and the National Quality and Technical Supervision Bureau has promulgated. Metallic hardness test method GB / T 17394-98 ".
1. What is the Leeb hardness? The Leeb hardness concept was proposed by the American Dr. Dietmar Leeb, which is a dynamic hardness test method. When the impact body of the hardness sensor impacts the workpiece to be measured, the ratio of the rebound speed and the impact speed at 1 mm from the workpiece surface is multiplied by 1000, which is defined as the Leeb hardness value, and the HL represents the Leeb hardness calculation formula as follows:
HL = Vb / Va × 1000 Among them, Vb: indicates the rebound speed, Va: indicates the impact speed

2. Features of Leeb hardness tester
2.1, Shore and Leeb hardness are both dynamic load test methods, but Shore examines the vertical height of the rebound of the impact body, so it is determined that the Shore hardness tester should be used vertically downwards, which is bound to cause a great deal in actual use. The limitations of Leeb are different. Leeb is looking at the speed of the rebound and impact of the impact body. Through the speed correction, it can be used in any direction, which greatly facilitates the user.
2.2. Commonly used cloth, Rockwell and Vickers hardness testers. Due to its large size, it is not easy to use in the field, especially when testing large and heavy parts. Since the hardness tester table cannot be accommodated, it cannot be detected at all. The Leeb hardness tester does not require a workbench. Its hardness sensor is as small as a pen and can be directly operated by hand. It can be easily detected whether it is a large or heavy workpiece or a workpiece with a complex geometric size.

3. Relevant factors of the Leeb hardness Since the Leeb hardness test method is a dynamic load test method, the Leeb hardness value must be related to the elastic modulus E of the metal material. The elastic modulus corresponding to different materials is also different, so the Leeb hardness tester is classified and tested according to the type of material.

4. Conversion of Leeb hardness to other hardnesses There is a correspondence between Leeb hardness values ​​and other hardness values ​​(HRC, HRB, HB, HV, HSD). Therefore, the Leeb value (HL) can be converted into other hardness values. The Leeb hardness tester can be automatically converted by the built-in microcomputer.

5. The classification comparison and detection of the Leeb hardness and other hardness require classification from the microscopic deformation. The cloth, Rockwell and Vickers hardness are the plastic deformation of the material, which is expressed as the size or depth of the indentation; the Leeb and Shore hardness inspection What is the elastic deformation of the material, the size or height of the rebound speed.

6. Requirements of the Leeb hardness tester for measurement 6.1. Requirements of the sample surface The test surface should have metallic luster, no oxide scale and other dirt, and the surface roughness should meet the following requirements:

Impact device type

Surface roughness of test piece (um)

D, DC type

≤1.6

Type G

≤6.3

Type C

≤0.4

6.2. Sample weight requirements The sample must have sufficient mass and rigidity to ensure that no displacement or springing occurs during the reconstruction process, and the quality should meet the following requirements:

Impact device type

Sample quality (Kg)

Stable placement

Fixed or clamped

Need to be coupled

D, DC type

> 5

2 ～ 5

0.05 ～ 2

Type G

> 15

5 ～ 15

0.5 ～ 5

Type C

> 1.5

0.5 ～ 1.5

0.02 ～ 0.5

6.3 The thickness of the sample requires that the sample should have sufficient thickness, and the minimum thickness should meet the following requirements:

Impact device type

Sample minimum thickness (mm)

D, DC type

5

Type G

10

Type C

1

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