The marks on the surface of the mold that we often see are caused by the defects of mold processing, so how can we reduce the various types of defects in the production of mold processing?
1. Reasonable selection of color steel tile machinery and grinding wheel dressing, white corundum grinding wheel is good, its performance is hard and brittle, new cutting edges are prone to appear, cutting force, grinding heat is small, medium-sized use and size, such as 46 ~ 60 mesh is better, use soft and soft hardness (ZR1, ZR2 and R1, R2) in the grinding wheel, that is, the wheel is coarse grained, the hardness is low, and the good self can reduce the cutting heat.
It is very important to select a suitable grinding wheel for fine grinding. For die steel with high vanadium and high molybdenum, gadolinium single crystal corundum grinding wheel is used. When machining cemented carbide, quenching materials with high hardness, it is preferred to use organic bond diamond grinding wheel The use of organic binder grinding wheel self-grinding, grinding out the roughness of Ra0.2 M, in recent years, with the application of new materials, CBN (cubic boron nitride) grinding wheel shows good processing effect, in CNC grinding machine , Machining grinders, CNC grinders, are more than other types of grinding wheels. In the dressing of the grinding wheel, attention should be paid to keep the grinding wheel sharp, when the grinding wheel, the surface of the workpiece slides, rubs and squeezes, causing burns on the surface of the workpiece and reduced strength.
2. The rational use of cooling lubricating fluid plays an important role in three cooling, lubricating, cleaning, cooling and lubricating to keep clean to control the grinding heat within the allowable range to prevent thermal deformation of the workpiece. In order to improve the grinding under cooling conditions, such as the use of oil-immersed wheels or internally cooled grinding wheels and other measures. The cutting fluid is introduced into the center of the grinding wheel, and the cutting fluid can directly enter the grinding area to cool and prevent burns on the surface of the workpiece.
3. The heat treatment stress after quenching is reduced to a small extent, because of the quenching stress, the network carbide structure in the grinding force, the structure change is very easy to crack the workpiece. For high-precision molds, in order to eliminate the grinding residual stress during grinding, the low-temperature aging of toughness should be improved.
4. To eliminate grinding stress, the mold can also be cooled by bathing at 260 ~ 315 ℃ for 1.5 minutes, and then oiling at 30 ℃, so the hardness can be reduced by 1hrc, and the residual stress can be reduced by 40% ~ 65%.
5. For grinding precision molds with tolerance accuracy within 0.01 mm, attention should be paid to the influence of ambient temperature and the grinding requirements of constant temperature. By calculation, the steel is 300 mm long, the temperature is 3 °C, and the material changes about 10.8 μ, (10.8 = 1.2 × 3 × 3, 1.2 μm/°C deflection per 100mm), the completion of the processing process needs to fully consider the impact 6, electrolytic grinding Machining to improve the manufacturing accuracy and surface quality of the mold.
Electrolytic grinding, grinding wheel scraping film: replace metal grinding, therefore, the grinding force, grinding heat is small, no grinding burrs, cracks, burns and other phenomena, the general surface roughness can be better than ra0.16μM; in addition, the wear of the grinding wheel Small, such as grinding carbide, silicon carbide grinding wheel wears carbide grinding 400% ~ 600%, the weight is about electrolytic grinding, grinding wheel wear is only 50% ~ 1007 carbide grinding amount, reasonable choice of grinding parameters , small radial feed grinding methods and fine grinding.
For example, if the radial feed speed and wheel speed increase, the axial feed speed is appropriately reduced, the contact area between the grinding wheel and the workpiece is reduced, and the heat dissipation conditions are improved, thereby effectively controlling the increase in surface temperature.