幸福是个过程

May 9th, 2010 by dongmiao158

Happiness is a journey We always convince ourselves that life will be better after we get married, have a baby, than another. Then we are frustrated that the kids aren’t old enough and we’ll be more contet when they are. After that we’re frustrated that we have teenagers to deal with. we will certainly be happy when they are out of that stage. We always tell ourselves that our life will be complete when our spouse gets his or her act together. when we get a nice car, and are able to go on a nice vocation when we retire. The truth is, there’s no better time than right now. If not now, when? our life will always be filled with challenges. It’s best to admit this to ourselves and decide to be happy anyway. One of my favorite quotes comes from Alfred Souza. He said.”for a long time it had seemed to me that life was about to begin-real life. But there was always some obstacle in the way, someting to be gotten through firest, some unfinished business, time still to be served, a debt to be paid. Then life would begin. At last it dawned on me that these obstacles were my life.” This perspective has helped me to see that there is no way to happiness. Happiness is the way. So treasure every moment that you have. And remember that time waits for no one. So stop waiting until you finish school, until you go back to school; until you get married, until you get divorced; until you have kids; until you retire; until you get a new car or home; until spring; until you are born again to decide that there is no better time than right now to be happy…. Happiness is a journey, not a destination.So, work like you don’t need money, love like you’ve never been hurt, And dance like no one’s watching.

切削刀具用量的选择

May 9th, 2010 by dongmiao158

切削刀具用量的选择

    切削刀具粗加工阶段的切削深度可达到单边50mm,相应的切削速度为10m/min左右,进给量1.5mm/r。因为粗加工阶段以去除余量为主要加工目的,因此按照机械加工中切削余量的确定原则,为提高切削效率,应加大切削深度。重型切削时由于切削深度大,所以切削力大,相应的选择较低的切削速度,一般为10~15m/min,进给量为1~2mm/r。采用这样的切削用量,工件的表面粗糙度比较差,只能达到Ra12.5~Ra6.3,可以通过滚压的方法提高粗糙度值,以满足后序加工的要求。

    这种新型硬质合金机夹车刀,装有可调整的附加卷屑器,使切屑卷成螺旋线型滑出。图1中,附加卷屑器4同时又是刀片6的夹持器,使刀片紧固在刀夹1中。切削时,切屑碰到卷屑器的工作部分就卷起来,此部分焊一个厚3~5mm的硬质合金片。附加卷屑器的前端压住硬质合金刀片,而后端则压住挡铁3。挡铁3下部及垫板2上部有锯齿纹,刀片磨损后,借此结构可将刀片伸出。垫板,用合金及淬火工具钢制成,用以保护硬质合金刀片不受折损。

    该新型机夹车刀采用长方形刀片,磨刀时,刀片夹在专用刀杆内,磨出的刀具角度用样板检查。硬质合金刀片的刃磨角度为,前角g=10°,后角a=8°,主偏角kr=55°或45°,副偏角kr1’=15°。为使刀杆可以重复使用,用45#钢锻造制成,热处理硬度为HRC45~48。用该车刀的切削刀具经验表明:切屑在高速切削时卷成螺旋线型是最好的形状(切削断面很大),切屑在切削刃附近就即行折断。若重型车床运转平稳,则硬质合金刀片切削刃不致破碎,生产效率就大大提高。

    经过使用比较,该型车刀与采用整体硬质合金刀具焊接的车刀使用寿命相同。但与生产中其它类型的硬质合金车刀比较,在大多数的情况下,该型重型车刀更耐用,可切削切屑的剖面更大。经验证明,在任何条件下,切屑卷出条件均好,切屑以长螺旋型或短螺旋型卷出。当切削深度与进刀量之比不大于3~4时,切屑碰在刀杆后即变成细碎块掉落。

    这种带有卷屑装置的新型硬质合金机夹车刀,在车床上及立式车床上切削钢件时使用。剖面为40mm×60mm及40mm×40mm的车刀,若切削余量均匀,其最大的切屑剖面在宽30mm的刀片上为20mm2,在宽25mm的刀片上为15mm2。当切削余量不均匀的硬皮时,切屑剖面要缩小30%~40%,当加工过程冲击很大时,不宜采用这种结构的重型车刀。

    刃磨该类硬质合金刀片时应注意,把硬质合金刀片放在刀杆槽内,用螺栓和卷屑器的垫板固定住。刀片从刀杆内伸出长度不要超过1~1.5mm。垫板要安置在刀片的前面,安放时,要使切屑能够成螺旋状卷出。从刀片中部测出的距离或伸出量依据切屑剖面的大小而定。伸出量的尺寸,不应小于表1中所列值,否则切屑将猛烈击打卷屑器,会造成车刀的切削部分破裂,甚至把刀杆打断。当切削时,要及时更换磨钝的或破裂的刀片。更换刀片必须把切屑渣从刀杆上清理净。

    该型刀具结构优点在于:刀块与刀体间有误差时,可以进行修磨,从而保证装配精度;压紧螺栓位于后刀面上,不容易被切屑损坏。板式刀架比较适合重型切削,因为它极大地增加了刀片受力方向的刚度,在增加切削用量后,也不致产生大振动,有利于生产效率和加工质量的提高。数控刀具

    切削刀具粗加工阶段的切削深度可达到单边50mm,相应的切削速度为10m/min左右,进给量1.5mm/r。因为粗加工阶段以去除余量为主要加工目的,因此按照机械加工中切削余量的确定原则,为提高切削效率,应加大切削深度。重型切削时由于切削深度大,所以切削力大,相应的选择较低的切削速度,一般为10~15m/min,进给量为1~2mm/r。采用这样的切削用量,工件的表面粗糙度比较差,只能达到Ra12.5~Ra6.3,可以通过滚压的方法提高粗糙度值,以满足后序加工的要求。

    切削刀具与普通车削相比,其实际加工同理论计算区别很大。目前,切削刀具的很多工艺及刀具资料都是以普通机械加工为依据,这并不完全适用,因此需要做更深入的探讨。