What are the reasons for the slippage of the tensile testing machine and the operating procedures of the equipment?

What are the reasons for the slippage of the tensile testing machine and the operating procedures of the equipment?

Tensile testing machine is also called general material testing machine, used to perform static load, tension, compression, bending, shearing, peeling and other mechanical properties of various materials. The technical staff of our company will share with you the reason and operation process of the tensile testing machine! www.lyxyantech.com

1. Reasons for the slippage of the tensile testing machine during use
1. Human factors cause the tensile testing machine to slip

The reason for the slippage of the tensile testing machine caused by human factors is that the operator did not press the test button during the test. The correct operation method is caused by two main factors: the length of the sample clamp is short, and the jaws of the clamp are improperly selected.

2. The test clamping length is short. www.lyxyantech.com

The correct way to use the fixture of the tensile testing machine of the testing machine should be, when the fixture length of the test piece is the same as the length of the fixture tooth surface, first use external force to make it generate initial friction on the clamping surface, and then pass the tester The beam moves to load the sample. When the friction force pulls the jaws (wedge-shaped mouth) due to the action of the inclined surface, the greater the axial tension, the greater the clamping force generated. Designed according to the above-mentioned clamping method and bearing uniform compressive stress, a wedge-shaped large opening with two inclined surfaces is designed on the clamping body of the testing machine.

However, some operators did not operate in accordance with the requirements of the testing machine. The clamping length of the sample is too short, or the processing time of the sample is too short, resulting in uneven force on the inclined surface of the wedge and local stress on the wedge. It far exceeds the yield strength of the material, resulting in plastic deformation of the wedge-shaped mouth, severe eversion, and collapse or wear of the inclined surface of the wedge-shaped mouth. In this case, the clamp will continue to be used, thereby reducing the angle of the wedge-shaped nozzle, worsening the stress state of the clamp body and causing slippage. www.lyxyantech.com

3. Improper selection of clamps

The clamps of the tension tester have various specifications and clamping surfaces. Different chucks are used for different samples. Some operators use large fixtures when testing. Clamping a sample with a small cross-section, or using a flat chuck to clamp a larger sample, will make the clamp and the sample not tight, thereby greatly reducing the coefficient of friction. The most intuitive performance is that the scaly peaks of the fixture are flattened by the divisor, and the friction is great. The amplitude is reduced. When the force on the specimen gradually increases to reach the maximum static friction force, the specimen will slip, causing false yield on the surface. www.lyxyantech.com

3. The equipment causes the tensile testing machine to slip

The main reason for the equipment is that when the stretcher pulls the sample, the oxide scale falls into the inclined surface of the wedge, causing the stretcher to slip. The oxide scale of the metal oxide is produced during the stretching process of the metal sample. The oxide scale will fall into the inclined surface combined with the wedge and the clamp, which will damage the flatness of the inclined surface and severely reduce the surface roughness, resulting in inflexible movement of the wedge nozzle (wedge). When the pulling force continues to increase, the wedge will crawl (jump) as it slides along the dovetail slope. This is how the sounds of bangs and bangs often appear during the loading process. This is commonly referred to as slippage. www.lyxyantech.com

After reading and sharing the reason and operation steps of the tensile testing machine slipping, can you solve the problem? Mechanical equipment is essentially the same, and different components are coordinated. Only by mastering the correct method can the whole experiment process be smoother and the experimental data more accurate. www.lyxyantech.com