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Fastening Tool Several Major Problems

Aug 02, 2017

Fastening Tool Several major problems

With the development and progress, the quality of its industrial demand is also getting higher and higher, so the requirements of the fastener is also rising, high-strength fasteners to meet everyone's needs, at present, high-strength fasteners development prospects, But the domestic high-strength fasteners or there are some problems, according to understand, mainly the following major problems. 1, to ensure that the load, wedge load failed. Ensure that the load and wedge load are the key items of the mechanical properties of the product under tensile load. , Especially for high-strength fasteners. To ensure that the load is to assess the tensile load under the provisions of the product resistance to plastic deformation, if the index does not meet the requirements, due to the role of preload and work load, may produce plastic deformation, thereby reducing the preload, The Wedge load test is to assess the tensile strength of the bolt product and the head of the joint strength, the indicators failed, in the larger working load, especially the impact load or support surface by partial load, the emergence of fracture or U-turn, resulting in connection failure, or even a security incident.

2, hardness is not qualified. Hardness is also an important indicator of the mechanical properties of fasteners, the materials used in the performance grade products are different, the choice of mechanical properties when the fastener is an important basis for the installation and use in accordance with the performance level to determine the work load And the installation of torque, for a specific material, the hardness should be controlled at a reasonable level, high hardness may reduce the product's fatigue resistance, some enterprises in order to improve product strength, hardness control at a higher level, resulting in some products exceeded.

3, decarburization layer exceeded. Decarburization layer is also a Class A project, due to decarburization, making the parts of the surface hardness and strength greatly reduced serious impact on the fastener surface contact strength and fatigue life, especially for the threaded parts of the more prominent. The main reason for decarburization is decarburization of raw materials, decarburization during decontamination of materials and decarburization during heat treatment.

4, size tolerance. Fasteners are common parts, interchangeability requirements are higher, the size of the tolerance will directly affect its interchangeability, and even affect the connection strength, anti-loose performance or life. The main reason for the size of the failure of a process is not properly controlled, in order to save some of the size control in the vicinity of the lower limit, the production process is not timely adjustment of equipment, the use of ultra-poor die: Second, poor inspection, process inspection and factory inspection Lax, so that some failed to pass off; Third, the use of measuring tools can not be regularly measured, and even use more than the wear limit gauge.

Contact person: Ms. Nancy Yue