1290 Каталог KORLOY 2020 Инструмент и оснастка для станков по металлу Стр.L30

Каталог KORLOY 2020 Инструмент для станков по металлу Стр. L30 1290 Lab2u

Drills O The shape of drills and the names Height of point Margin width Chisel edge Chisel angle Width of land Relief angle Flank Point relief angle Lead Drill diameter Flute width Cutting edge Shank diameter Cuting face Flute length Total length O Shape and the feature of cutting Helix angle Plays rake angle of cutting edge’s role. If helix angle increases Cutting force decreases. On the other hand If helix angle is too big Drill rigidity decreases Poor machinability 4 low - Helix angle - high Smooth chip evacuation Hard workpiece (hardened steel) 4 low - Helix angle - high Soft material (aluminum etc) Length of flute The path of both chip evacuation and cooling lubricant Too big length of flute weakens drill rigidity and too small length of flute worsens chip evacuation to breakage Point angle Point angle has big influence on cutting performance. It mainly depends on workpiece. In case of standard drills Point angle is generally 118 thrust resistance decrease low - Point angle - high thrust resistance increase Torque increase, Burr on exit increase A low - Point angle - high Torque decrease, Burr on exit decrease Soft material (aluminum etc) A low - Point angle - high Hard workpiece (hardened steel) Margin While machining Margin is the part of contact between workpiece and drill’s external. It prevents bending and plays guide’s role It depends on drill size Cutting force decrease 4 small - Margin - big Cutting force increase Poor guide 4 small - Margin - big Good guide Web thickness Web is the part of center of drill and drill’s rigidity depends on the web. Drill needs cutting edge, chisel edge, at the tip of drill because drill makes a hole at the beginning of drilling . When web thickness is big Thinning is needed to reduce cutting force Cutting force decrease Rigidity decrease Good chip evacuation Soft material (aluminum etc) small - Web thickness - b small - Web thickness - b 4 small - Web thickness - b 4 small - Web thickness - big g g g Cutting force increase Rigidity increase Bad chip evacuation Hard workpiece (hardened steel) Back taper Drill diameter size is getting smaller from point to shank in order to avoid the friction between drill periphery and workpiece. The decrease of diameter divided by flute length 100mm generally becomes 0.04 0.1mm. As for high performance drills and drills for hole shrinkage workpiece during operation have big back taper Thinning In general drills Thrust effects on chisel over 50%. Chisel edge length depends on web thickness and chisel angle. But if web is thin Drill rigidity weaken. Therefore without web thickness change Thinning makes chisel edge short or gives rake angle. In other words, Thinning makes rake angle at chisel and improves chip evacuation and decrease thrust Types of Edge shape Feature Korloy’s drills X type 5 r Good centering High central thickness Crank shaft Mach solid drill (MSD) Vulcan drill (VZD) S type J 5 > For wide use For general Easy regrinding Solid drill (SSD) 30 Technical Information