【正文】 ................................................ 18 Determine the specification model of the ball screw nut .... 19 The vertical feed system design and calculation ................. 19 Dall screws for bearing capacity check .............................. 19 The ball screw nut critical pression load calibration ........................................................................................... 19 The critical speed of the ball screw nut checksum .... 20 Dall screw pair rated life C heck ..................................... 21 Calculate the mechanical transmission system of stiffness 22 Calculate the mechanical transmission system of stiffness .............................................................................. 22 C alculate the stiffness of the ball screw nut supportin g bearing ................................................................................ 23 .3 Calculate the contact stiffness of the ball and the raceway............................................................................... 24 C alculate the feed drive system inte grated tension and pression stiffness .......................................................... 25 Calculate the torsional stiffness of the ball screw nut ....... 26 Chapter 4 drive motor selection and calculation ......................... 27 The calculation of muted to the motor shaft load moment of inertia ................................................................................... 27 A single rotary part of the moment of inertia calculation .......................................................................... 27 CM6132 型精密車床進(jìn)給系統(tǒng)的數(shù)控改造 VIII The moment of inertia of moving parts, converted to motor shaft.......................................................................... 27 Increase the total load on the motor rotation inertia calculation .......................................................................... 28 C alculate the load torque converted to motor shaft ............ 28 Converted to a motor shaft of the cutting load torque calculation .......................................................................... 28 Converted motor shaft friction load torque calculation ........................................................................................... 29 Generated by the ball screw preload and calculation of load torque converted to motor shaft ................................... 29 Converted to motor shaft load moment of calculation ........................................................................................... 30 Calculation of converted to electric on the shaft of the accelerating torque .................................................................... 30 S elect the model of the drive motor ................................... 31 Select the model of the drive motor .......................... 31 Determine the maximum static torque ...................... 32 C hecking the inertia match....................................... 32 Chapter 5 Mechanical syste m dynamic analysis ........................ 34 C alculation of the lowest natural frequency of the screw Longitudinal vibration system .................................................... 34 Calculation of the lowest natural frequency of torsional vibration system ........................................................................ 34 Calculate the mechanical transmission of the reverse dead zone ........................................................................................... 35 The mechanical transmission system by the integrated pressive and tensile stiffness changes caused by positioning error .......................................................................................... 35 The calculation of ball screw error to reverse the deformation.................................................................................................. 36 The calcula tion of the amo unt of deformation of the CM6132 型精密車床進(jìn)給系統(tǒng)的數(shù)控改造 IX Torque caused by the ball screw pair ........................ 36 Conclus ion ..................................................................................... 37 Thanks ........................................................................................... 38 References ..................................................................................... 39 CM6132 型精密車床進(jìn)給系統(tǒng)的數(shù)控改造 1 第 1 章 緒論 選題的意義 我國近幾年數(shù)控機(jī)床雖然發(fā)展較快，但與國際先進(jìn)水平還存在一定的差距，主要表現(xiàn)在：可靠性差，外觀質(zhì)量差，產(chǎn)品開發(fā)周期長，應(yīng)變能力差 [1 ]。 第三代數(shù)控：從 1965 年開始采用小、中規(guī)模集成電路的 NC 系統(tǒng)。隨著電子技術(shù)和控制技術(shù)的飛速發(fā)展，當(dāng)今的數(shù)控系統(tǒng)功能已經(jīng)非常強(qiáng)大，與此同時加工技術(shù)以及一些其他相關(guān)技術(shù)的發(fā)展對數(shù)控系統(tǒng)的發(fā)展和進(jìn)步提出了新的要求。 總體方案的擬定 本篇設(shè)計(jì)研究的對象為 CM6132 車床，適用于車削精密零件，并可加工公制、英制、模數(shù)和徑節(jié)螺紋。 CM6132 型精密車床進(jìn)給系統(tǒng)的數(shù)控改造 5 進(jìn)給電機(jī)伺服系統(tǒng)的改造設(shè)計(jì) 為滿足盡可能減少改動量的要求，采用步進(jìn)電機(jī)經(jīng)接口箱驅(qū)動絲杠，帶動刀具縱向和橫向移動，用滾珠絲杠螺母機(jī)構(gòu)代替普通的滑動絲杠螺母機(jī)構(gòu)，具有摩擦力小，運(yùn)動靈敏，無爬行現(xiàn)象的特點(diǎn)，也可以進(jìn)行預(yù)緊，以實(shí)現(xiàn)無間隙傳動，以使傳動剛度好，反向時無空程死區(qū) [1 3 ]。 聯(lián)軸器 當(dāng)電動機(jī)與滾珠絲杠之間傳遞的扭矩較大時，由于伺服電動機(jī)優(yōu)越的力矩特性，可以采用電動機(jī)與滾珠絲杠直接連接的方法，這不僅可以簡化結(jié)構(gòu)、減少噪音，而且對減少傳動鏈的間隙、提高傳動剛度也有打的好處。這樣依靠彈性鋼片組對角聯(lián)接 (即撓性 )傳遞扭矩，且與電機(jī)軸和絲杠都無鍵聯(lián)接，便是撓性聯(lián)軸節(jié)的工作原理。 在此轉(zhuǎn)速下，主軸具有最大扭矩和功率， 有文獻(xiàn) [19,219]可知 刀具的切削速度為 v = 60Dn? = 60 3 ??? ?=取機(jī)床的機(jī)械效率 ?= ，由 文獻(xiàn) [2,1013]可知，主切削力 ZF = vPm? 103 = ? 103= 計(jì)算各切削分力 走刀方向的切削分力 Fx 和垂直走刀方向的切削分力 yF 。 取進(jìn) 步電 動機(jī) 的步 距角 a =176。對于不同的支承方式， 其計(jì)算方式不同，本次設(shè)計(jì)方案采用一端固定、一端游動支承方式的滾珠絲杠安裝 1. 一端固定，一端自由或游動時，有 2md ? ELFm a x010102 ???? = ? LF mm (311) 式中 E — — 彈性模量 （ MPa） ，一般滾珠絲杠取 E =105 MPa； 2md — — 估算的滾珠絲杠螺母副允許的最大軸向變形量（ μm）； 0F — — 導(dǎo)軌的靜摩擦力 （ N） ， 0F = W?0? ； L — — 滾珠絲杠螺母至絲杠固 定端支承的最大距離（ mm） ， L =行程 +安全行 程 +余程 +螺母長 度 +支承長 度≈ （ ～） 行程 +（ 25～ 30） 0L 。因此，只要此時的轉(zhuǎn)速不超過臨界轉(zhuǎn)速