随着机床技术的发展，主轴转速越来越高。目前，普通高速主轴大多数角接触球轴承的接触角为15度和25度。Withthedevelopmentofmachinetooltechnology,spindlespeedishigherandhigher.Atpresent,thecontactanglesofmostangularcontactballbearingsofordinaryhighspeedspindleare15degreesand25degrees.15°接触角的江苏NSK轴承转速较高，但轴向承载力和刚度较低。一般来说，大多数磨削、铣床和高速加工中心使用角接触角为15度的角接触球轴承。随着主轴转速的进一步提高，这种轴承往往不能满足要求。必须开发新的超高速轴承。The15degreecontactangleofJiangsuNSKbearinghashigherrotationalspeed,buttheaxialbearingcapacityandstiffnessarelower.Generallyspeaking,mostgrinding,millingmachinesandhighspeedmachiningcentersuseangularcontactballbearingswithangularcontactanglesof15degrees.Withthefurtherimprovementofspindlespeed,thisbearingoftencannotmeettherequirements.Newsuperhighspeedbearingsmustbedeveloped.在15°接触角下，江苏NSK轴承在光预紧和润滑脂作用下的DMN值可达到1×106mmr/min，在油气润滑下可达到1.4×106mm／r/min。如果DMN值太高，由于离心力大，球与外圈滚道之间的接触压力将非常大，从而降低轴承的寿命。Underthecontactangleof15degrees,theDMNvalueofJiangsuNSKbearingcanreach1x106mmr/minundertheactionoflightpretighteningandlubricatinggrease,anditcanreach1.4*106mm/r/minunderoilandgaslubrication.IftheDMNvalueistoohigh,duetothelargecentrifugalforce,thecontactpressurebetweentheballandtheouterraceracewaywillbeverylarge,thusreducingthelifeofthebearing.在江苏NSK轴承离心力作用下，球与滚道的接触角减小或甚至减小到零，球与内圈滚道的接触角增大。前者减小了轴承的轴向刚度，后者降低了径向刚度。此外，过快的旋转速度会在球上产生较大的陀螺力矩，从而增加热量并在笼上产生附加应力。UnderthecentrifugalforceofNSKbearinginJiangsu,thecontactanglebetweenballandracewaydecreasesorevendecreasestozero,andthecontactanglebetweenballandinnerraceracewayincreases.Theformerreducestheaxialstiffnessofthebearing,andthelatterreducestheradialstiffness.Inaddition,excessiverotationalspeedwillproducelargergyroscopicmomentsontheball,therebyincreasingheatandproducingadditionalstressesonthecage.因此，为了进一步提高江苏NSK轴承速度，必须降低球的质量。近年来国外已经发展了两种超高速轴承，接触角为15度。一个是球轴承，球直径比普通轴承小，另一个是陶瓷球轴承。Therefore,inordertofurtherimprovethespeedofNSKbearinginJiangsu,wemustreducethequalityoftheball.Inrecentyears,twokindsofultrahighspeedbearingsh***ebeendevelopedabroad,andthecontactanglesare15degrees.Oneisballbearing,theballdiameteris***allerthancommonbearing,andtheotherisceramicballbearing.它不仅直径小，而且还用于陶瓷（内外环仍然是钢）。外形尺寸与一般的角接触轴承相同，可以互换。当然，陶瓷内环和圆柱陶瓷轴承是***近发展起来的。Itisnotonly***allindiameter,butalsousedinceramics(innerandouterringsarestillsteel).Theoutlinesizeisthesameasthegeneralangularcontactbearing,anditcanbeinterchanged.Ofcourse,ceramicinnerringsandcylindricalceramicbearingsh***ebeendevelopedrecently.由于小滚珠的存在，江苏NSK轴承的承载能力下降。与普通轴承相比，额定动载荷降低约40%。然而，考虑到机床主轴的负荷较小，高速主轴的负荷较轻，所以没有问题。Duetotheexistenceof***allballs,thebearingcapacityofNSKbearinginJiangsuhasdecreased.Comparedwithordinarybearings,therateddynamicloadisreducedbyabout40%.However,c***ideringthattheloadofthespindleofthemachinetoolis***all,theloadofthehighspeedspindleislighter,sothereisnoproblem.球很小，球的数量增加了。江苏NSK轴承的刚度与球直径的1/3的功率和球数的2/3的功率成正比。因此，轴承的刚度也得到了改善。尤其对于陶瓷球轴承，陶瓷的弹性模量约为3.14×105MPa，比钢（2.08x105）高约50%，因此硬度较高。Theballis***allandthenumberofballsincreases.ThestiffnessofNSKbearinginJiangsuisdirectlyproportionaltothepowerof1/3andthepowerof2/3ofballnumber.Therefore,thestiffnessofthebearinghasalsobeenimproved.Especiallyforceramicballbearings,themodulusofelasticityofceramicsisabout3.14x105MPa,whichisabout50%higherthansteel(2.08x105),sothehardnessishigher.文章来自：江苏SKF轴承www.wh-Thearticlecomesfrom:JiangsuSKFbearingwww.wh-文章来自：江苏INA轴承a-Thearticlecomesfrom:JiangsuINAbearinga-文章来自：江苏NSK轴承Thearticlecomesfrom:JiangsuNSKbearing)