Turning the workpiece in a lathe using themethod of cutting tool rotation processing workpiece. Turning processingcutting is mainly composed of workpiece and not provide tools. Turning is themost basic, the most common method of cutting, occupies a very importantposition in the production. Turning for processing rotary surface, a large partof workpiece with rotating surface turning method of processing can be used,such as the external cylindrical surface, inside and outside the cone face, face,groove, screw and rotary forming surface, the tool is mainly used tools.Turning precision is generally it11-it7, some can reach IT6, surface roughnessRa 12.5-08um. can be achieved by Turning Parts, we call turning parts, thereare many kinds of turning parts, most famous is via hard turning to maintainthe thermal stability of the parts.
Basically,we can realise it on differentraw material,like copper alloy,steel,and aluminium alloy.
(1) The biggest problem is to use orwithout cooling liquid. For interrupted cutting parts such as gears, the bestuse of "dry turning", otherwise the thermal shock feed and withdrawalknife is likely to cause the blade to rupture. As for the continuous cuttingknife head, high temperature produced in dry turning process to toughening(softening) the pre cutting area, thereby reducing the hardness of the materialto make it easy to cut. This phenomenon shows that the stem cutting speedincrease is good. At the same time, no coolant cutting method has obvious costadvantages. (2) Layer whitening whitening scald layer (heat affected zone)"may be a dislike to appear in hard turning and grinding operation, namelyin the material surface to form a layer of invisible to the naked eye is verythin (typically 1 m) crust. The formation of albino layer in the hard turningprocess, usually because of blade Passivation causes too much heat to the innerparts. Often whitening on bearing steel form, and it is very harmful to thebearing ring like need to withstand high contact pressure parts, with thepassage of time, the albino layer may stripped and lead to bearing failure.
(3) Machine:stiffness determines precisionhard turning. Nearly 15 ~ 20 years of manufacturing machines in the almost allhave good rigidity, enough to withstand hard turning. In many cases, theoverall condition of the machine is largely over the use of life is moreimportant, the general maintenance The opening of the bed can also be used forhard turning. In order to increase the rigidity and damping characteristics forhard turning machine, hatey characteristics of many advanced machine tool forthe machining center, including polymer composites reinforced with a springclip (the spindle support near the workpiece) is directly matched with thespindle and hydrostatic guideway system. The maximum rigidity means a tool toreduce vacant, and extending parts out, and cancel the adjustable gap plate andgasket, its goal is to keep all parts as close as possible to the turret.
(4) Process:because of the heat generatedby hard turning most chips away, before and after the processing of chipinspection You can find the whole process is coordinated. Continuous cutting,the chip should be blazing orange, and like a ribbon like flowing out. If thechip after cooling by hand pressure fracture, shows that cutting heat isnormal.
(5) Blade:cubic boron nitride (CBN) insertsthe price is expensive, but the most suitable for the hard cutting bladeCBN.Cbn blade can keep unchanged in the positioning of intermittent cuttingprocess, to provide a safe tool wear rate in continuous cutting process. Whenusing the hard turning process reasonable, except in the control of CBN bladediameter tolerance is not better than grinding, other properties are second tonone.