How to reduce defects in the processing of plastic products
This paper analyzes how the plastic product mold reduces defects during processing, mainly from the following five aspects.
1. Reasonably use the cooling lubricant to play the three functions of cooling, washing and lubrication, keep the cooling and lubrication clean, and control the grinding heat within the allowable range to prevent the workpiece from being thermally deformed. Improve the cooling conditions during grinding, such as the use of oil-impregnated grinding wheels or internal cooling wheels. The cutting fluid is introduced into the center of the grinding wheel, and the cutting fluid can directly enter the grinding zone to exert an effective cooling effect to prevent the surface of the workpiece from being burned.
2. The quenching stress after heat treatment is reduced to a minimum, because the quenching stress and the reticulated carbonized structure under the action of the grinding force, the phase change of the structure is extremely easy to cause cracks in the workpiece. For high-precision molds, in order to eliminate the residual stress of grinding, low-temperature aging treatment should be performed after grinding to improve the toughness.
3, eliminate the grinding stress can also be immersed in the 260 ~ 315 ° C salt bath for 1.5min, and then cooled in 30 ° C oil, so the hardness can be reduced by 1HRC, residual stress reduced by 40% ~ 65%.
4. For precision grinding of precision molds with a dimensional tolerance of less than 0.01 mm, attention should be paid to the influence of ambient temperature, and constant temperature grinding is required. It can be seen from the calculation that for a steel piece with a length of 300 mm, the material has a change of about 10.8 μm at a temperature difference of 3 ° C (10.8 = 1.2 × 3 × 3, and the deformation amount per 100 mm is 1.2 μm / ° C), and each finishing process needs to be fully considered. The impact of this factor.
5, using electrolytic grinding processing to improve mold manufacturing accuracy and surface quality. In electrolytic grinding, the grinding wheel scrapes off the oxide film: instead of grinding the metal, the grinding force is small, the grinding heat is small, and no grinding burrs, cracks, burns, etc. occur, and the surface roughness is generally better than Ra0. .16μm; In addition, the wear of the grinding wheel is small, such as grinding cemented carbide, the wear of the silicon carbide grinding wheel is about 400% to 600% of the weight of the hardened carbide. When grinding with electrolytic grinding, the wear of the grinding wheel The amount is only 50% to 100% of the amount of cemented carbide.