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Mould processing to reduce the defects of the seven skills, watching you become an expert!
by：CSSSLD
2021-01-23
In order to improve the performance of the mold, the mold many vendors will be properly processing, mold processing refers to the molding and blocking tool processing, moreover also includes shear die and die cutting mould, but in many cases, the mould processing will also reflect the machining defects, cause mould performance degradation, that how to build mould processing defects?
The following seven measures to build mould processing defects.
1, the reasonable choice and dressing grinding wheel, using white corundum grinding wheel is better, it is the performance of hard and brittle, and easy to produce the new cutting edge, so the cutting force is small, the grinding heat is small, use on the granularity of medium size, such as better 46 ~ 60 mesh, using soft and soft on grinding wheel hardness ( ZR1, ZR2 and R1, R2) , that is, coarse granularity, low hardness of the grinding wheel, good self excitation can reduce heat cutting.
of selecting the appropriate fine grinding wheel is very important, in view of the condition of the die steel with high vanadium high molybdenum, choose GD is suitable for single crystal corundum grinding wheel, when processing hard alloy, high quenching hardness of materials, the priority using organic binder diamond grinding wheel, since the organic binder grinding wheel grinding, grinding the workpiece roughness of Ra0. 2 microns, in recent years, with the application of new materials, CBN ( Cubic boron nitride) Grinding wheel shows very good processing effect, both inside and outside the CNC forming grinder, jig grinding machine, CNC grinding machine on finishing, is better than other kinds of grinding wheel. In grinding, attention should be paid to timely dressing grinding wheel, keep the wheel sharp, when grinding wheel after passivation can slip on the workpiece surface wipe, extrusion, surface caused by burns, strength decrease.
2, rational use of liquid cooling and lubrication, cooling, washing, lubrication should play the role of the big three, cooling and lubrication to keep clean, so as to control the grinding heat within the scope of the permit, to prevent thermal deformation. Improve the cooling conditions when grinding, such as by oil immersion wheel or inner cooling grinding wheel and other measures. The cutting fluid into the center of the grinding wheel, cutting fluid can be directly into the grinding zone, give play to the role of effective cooling, prevent the workpiece surface burn.
3, after heat treatment of quenching stress reduced to a minimum, because quenching stress, reticular tissue under the action of the grinding force, carbide organization transformation to make the workpiece to produce crack. For high precision mould in order to eliminate the residual stress of the grinding, the grinding should be done after aging treatment of metal in order to improve the toughness at low temperature.
4, eliminate grinding stress also die in 260 ~ 315 ℃ can be soaked in salt bath 1. 5 min, and then in 30 ℃ oil cooling, so can drop 1 HRC hardness, residual stress reduced by 40% ~ 65%.
5, for the size tolerance in 0. 01
mm within the precision mould precision grinding attention should be paid to the influence of environment temperature, requires constant temperature grinding. The calculation shows that 300 mm long steel, temperature 3 ℃, the material has 10. The change of around 8 microns, ( 10. 8 = 1. 2 * 3 * 3, each 100 mm 1 deformation. 2μm/℃) , the machining process are required to fully consider the influence of this factor.
6, the electrolytic grinding processing, improve the mould manufacturing precision and surface quality. Electrolytic grinding, grinding wheel shaving oxide film: instead of grinding, metal and small grinding force, grinding heat is small, won't produce the phenomenon such as grinding burrs, cracks, burns, surface roughness can be better than Ra0 commonly. 16μm; In addition, the grinding wheel wear small, such as grinding hard alloy, silicon carbide grinding wheel wear is about for grinding of cemented carbide of the weight of 400% ~ 600%, electrolytic grinding, grinding wheel wear is only hard alloy grinding in addition amount of 50% ~ 100%.
7, reasonably choosing grinding dosage, the smaller radial feeding method of fine grinding and fine grinding. Such as appropriate to reduce the radial feeding and grinding wheel speed, increase the axial feeding, reduce grinding wheel and workpiece contact area, cooling condition is improved, so as to effectively control the improvement of surface temperature.
1, the reasonable choice and dressing grinding wheel, using white corundum grinding wheel is better, it is the performance of hard and brittle, and easy to produce the new cutting edge, so the cutting force is small, the grinding heat is small, use on the granularity of medium size, such as better 46 ~ 60 mesh, using soft and soft on grinding wheel hardness ( ZR1, ZR2 and R1, R2) , that is, coarse granularity, low hardness of the grinding wheel, good self excitation can reduce heat cutting.
of selecting the appropriate fine grinding wheel is very important, in view of the condition of the die steel with high vanadium high molybdenum, choose GD is suitable for single crystal corundum grinding wheel, when processing hard alloy, high quenching hardness of materials, the priority using organic binder diamond grinding wheel, since the organic binder grinding wheel grinding, grinding the workpiece roughness of Ra0. 2 microns, in recent years, with the application of new materials, CBN ( Cubic boron nitride) Grinding wheel shows very good processing effect, both inside and outside the CNC forming grinder, jig grinding machine, CNC grinding machine on finishing, is better than other kinds of grinding wheel. In grinding, attention should be paid to timely dressing grinding wheel, keep the wheel sharp, when grinding wheel after passivation can slip on the workpiece surface wipe, extrusion, surface caused by burns, strength decrease.
2, rational use of liquid cooling and lubrication, cooling, washing, lubrication should play the role of the big three, cooling and lubrication to keep clean, so as to control the grinding heat within the scope of the permit, to prevent thermal deformation. Improve the cooling conditions when grinding, such as by oil immersion wheel or inner cooling grinding wheel and other measures. The cutting fluid into the center of the grinding wheel, cutting fluid can be directly into the grinding zone, give play to the role of effective cooling, prevent the workpiece surface burn.
3, after heat treatment of quenching stress reduced to a minimum, because quenching stress, reticular tissue under the action of the grinding force, carbide organization transformation to make the workpiece to produce crack. For high precision mould in order to eliminate the residual stress of the grinding, the grinding should be done after aging treatment of metal in order to improve the toughness at low temperature.
4, eliminate grinding stress also die in 260 ~ 315 ℃ can be soaked in salt bath 1. 5 min, and then in 30 ℃ oil cooling, so can drop 1 HRC hardness, residual stress reduced by 40% ~ 65%.
5, for the size tolerance in 0. 01
mm within the precision mould precision grinding attention should be paid to the influence of environment temperature, requires constant temperature grinding. The calculation shows that 300 mm long steel, temperature 3 ℃, the material has 10. The change of around 8 microns, ( 10. 8 = 1. 2 * 3 * 3, each 100 mm 1 deformation. 2μm/℃) , the machining process are required to fully consider the influence of this factor.
6, the electrolytic grinding processing, improve the mould manufacturing precision and surface quality. Electrolytic grinding, grinding wheel shaving oxide film: instead of grinding, metal and small grinding force, grinding heat is small, won't produce the phenomenon such as grinding burrs, cracks, burns, surface roughness can be better than Ra0 commonly. 16μm; In addition, the grinding wheel wear small, such as grinding hard alloy, silicon carbide grinding wheel wear is about for grinding of cemented carbide of the weight of 400% ~ 600%, electrolytic grinding, grinding wheel wear is only hard alloy grinding in addition amount of 50% ~ 100%.
7, reasonably choosing grinding dosage, the smaller radial feeding method of fine grinding and fine grinding. Such as appropriate to reduce the radial feeding and grinding wheel speed, increase the axial feeding, reduce grinding wheel and workpiece contact area, cooling condition is improved, so as to effectively control the improvement of surface temperature.
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