General problems about the prevention of fastener grinding

Fasteners have high toughness and high thermal strength. The cutting edge of grinding wheel abrasive grains has a relatively large negative rake angle, and the grinding chips during the grinding process are not easy to be cut away. The cutting resistance is large, and the extrusion and friction are severe. The grinding force per unit area is very large, and the grinding temperature can reach 1000℃~1500℃. At the same time, under the action of high temperature and high pressure, abrasive debris is generally easier to adhere to the grinding wheel, filling the gaps between the abrasive particles, and also making the abrasive particles lose the cutting effect. The types of fasteners are different, and the situation of grinding wheel blockage is also different. For example, grinding of concentrated nitric acid-resistant fasteners and heat-resistant fasteners, adhesion and blockage are more serious than 1Cr18NiTi, and 1Cr13, 2Cr13, etc. Body fasteners are relatively light. (Guide: Which aspects are included in the acceptance criteria of non-standard screws)

The thermal conductivity of fasteners is small, the high temperature during grinding is not easy to be derived, and the surface of the workpiece is prone to burns and annealing. The depth of the annealing layer can sometimes reach 0.01~0.02 mm. Severe extrusion deformation occurs during the grinding process, resulting in work hardening of the ground surface, especially when grinding austenitic fasteners, because the austenite structure is not stable enough, it is easy to produce martensite structure after grinding, making the surface Severe hardening.

Fasteners have a large linear expansion coefficient, which is easy to deform under the action of grinding heat, and its size is difficult to control. Especially for thin-walled and slender parts, this phenomenon is more serious.

Most types of fasteners cannot be magnetized. During surface grinding, only mechanical clamping or special fixtures can be used to clamp the workpiece. The side of the workpiece is used to clamp the workpiece, which will cause deformation and cause shape or size errors. The workpiece is more prominent. At the same time, it can also cause chattering during grinding and scaly ripples.

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