759 柴油機(jī)連桿的加工工藝,柴油機(jī),連桿,加工,工藝 數(shù)控機(jī)床加工精度異常故障的診斷和處理生產(chǎn)中經(jīng)常會(huì)遇到數(shù)控機(jī)床加工精度異常的故障。此類故障隱蔽性強(qiáng)，診斷難度比較大。形成這類故障的原因主要有五個(gè)方面：{1}機(jī)床進(jìn)給單位被改動(dòng)或變化。{2} 機(jī)床各個(gè)軸的零點(diǎn)偏置 [NULL OFFSET]異常。{3}軸向的反向間隙[BACK LASH]異常。{4}電機(jī)運(yùn)行狀態(tài)異常，即電氣及控制部分異常。{5}機(jī)械故障，如絲杠，軸承，軸聯(lián)器等部件。另外加工程序的編制，刀具的選擇及人為因素，也可能導(dǎo)致加工精度異常。1． 系統(tǒng)參數(shù)發(fā)生變化或改動(dòng) 系統(tǒng)參數(shù)主要包括機(jī)床進(jìn)給單位，零點(diǎn)偏置，反向間隙等。例如SIMENS，F(xiàn)ANUC 系統(tǒng)，其進(jìn)給單位有公制和英制兩種。機(jī)床修理過程中某些處理，常常影響到零點(diǎn)偏置和間隙的變化，故障處理完畢后應(yīng)作適時(shí)的調(diào)整和修改；另一方面，由于機(jī)械磨損嚴(yán)重或連結(jié)松動(dòng)也可能造成參數(shù)實(shí)測(cè)值的變化，需要對(duì)參數(shù)做相應(yīng)的修改才能滿足機(jī)床加工精度的要求。2． 機(jī)械故障導(dǎo)致的加工精度異常 一臺(tái)THM6350立式加工中心，采用SIMENS 840D系統(tǒng)。在加工聯(lián)桿模具過程中，忽然發(fā)現(xiàn)Z軸進(jìn)給異常，造成至少1毫米的切削誤差量（ Z向過切） 。調(diào)查中了解到：故障是忽然發(fā)生的。機(jī)床在點(diǎn)動(dòng)，MDI（手動(dòng)數(shù)據(jù)輸入方式）操作方式下各個(gè)軸運(yùn)行正常，且回參考點(diǎn)正常；無任何報(bào)警提示，電氣控制部分硬故障的可能性排除。分析認(rèn)為，主要應(yīng)對(duì)以下幾個(gè)方面逐一進(jìn)行檢查。 [1]檢查機(jī)床精度異常時(shí)正在運(yùn)行的加工程序段，特別是刀具長(zhǎng)度補(bǔ)償，加工坐標(biāo)（G54—G59）的校對(duì)和計(jì)算。 [2]在點(diǎn)動(dòng)方式下，反復(fù)運(yùn)動(dòng)Z軸，經(jīng)過視，觸，聽對(duì)其運(yùn)動(dòng)狀態(tài)診斷，發(fā)現(xiàn)Z向運(yùn)動(dòng)噪 音異常，特別是快速點(diǎn)動(dòng)，噪音更加明顯。由此判斷，機(jī)械方面可能存在隱患。 [3]檢查機(jī)床Z軸精度。用手搖脈沖發(fā)生器移動(dòng) Z軸， （將其倍率定為1X100的擋位，即每變化一步，電機(jī)進(jìn)給0.1毫米） ，配合百分表觀察Z軸的運(yùn)動(dòng)情況。在單向運(yùn)動(dòng)精度保持正常后作為起始點(diǎn)的正向運(yùn)動(dòng)，脈沖器每變化一步，機(jī)床Z軸運(yùn)動(dòng)的實(shí)際距離d=dl=d2=d3….=0.1mm ，說明電機(jī)運(yùn)行良好，定位精度也良好。而返回機(jī)床實(shí)際運(yùn)動(dòng)位移的變化上，可以分為四個(gè)階段：①機(jī)床運(yùn)動(dòng)距離d1>d=0.1mm(斜率大于1)； ②表現(xiàn)出為d1=0.1>d2>d3(斜率小于1)；③機(jī)床機(jī)構(gòu)實(shí)際沒移動(dòng)，表現(xiàn)出最標(biāo)準(zhǔn)的反向間隙；④機(jī)床運(yùn)動(dòng)距離與脈沖器給定數(shù)值相等（斜率等于1） ，恢復(fù)到機(jī)床的正常運(yùn)動(dòng)。 無論怎樣對(duì)反向間隙（參數(shù)1851）進(jìn)行補(bǔ)償，其表現(xiàn)出的特征是：除了③階段能夠補(bǔ)償外，其他各段變化依然存在，特別是① 階段嚴(yán)重影響到機(jī)床的加工精度。補(bǔ)償中發(fā)現(xiàn)，間隙補(bǔ)償越大，①階段移動(dòng)的距離也越大。 分析上述檢查認(rèn)為存在幾點(diǎn)可能原因：一是電機(jī)有異常；二是機(jī)械方面有故障；三是絲杠存在間隙。為了進(jìn)一步診斷故障，將電機(jī)和絲杠完全脫開，分別對(duì)電機(jī)和機(jī)械部分進(jìn)行檢查。檢查結(jié)果是電機(jī)運(yùn)行正常；在對(duì)機(jī)械部分診斷中發(fā)現(xiàn)，用手盤動(dòng)絲杠時(shí)，返回運(yùn)動(dòng)初始有非常明顯的空缺感。而正常情況下，應(yīng)能感覺到軸承有序而平滑的移動(dòng)。經(jīng)過拆卸檢查發(fā)現(xiàn)其軸承確實(shí)受損，且有滾珠脫落。更換后機(jī)床恢復(fù)正常。3． 機(jī)床電氣參數(shù)未優(yōu)化電機(jī)運(yùn)行異常 有一臺(tái)北京產(chǎn)的立式數(shù)控銑床，配備SIMENS840D系統(tǒng)。在加工過程中，發(fā)現(xiàn)X軸精度異常。檢查發(fā)現(xiàn)X軸存在一定間隙，且電機(jī)啟動(dòng)時(shí)存在不穩(wěn)定的現(xiàn)象。有手觸摸X軸電機(jī)時(shí)感覺電機(jī)抖動(dòng)比較厲害，停止是抖動(dòng)不明顯，尤其是點(diǎn)動(dòng)方式下比較明顯。分析認(rèn)為，故障原因有兩點(diǎn)，一是絲杠反向間隙很大；二是X軸電機(jī)工作異常。利用SIMENS系統(tǒng)的參數(shù)功能，對(duì)電機(jī)進(jìn)行調(diào)試。首先對(duì)存在的間隙進(jìn)行補(bǔ)償；調(diào)整伺服增益參數(shù)及脈沖抑制功能參數(shù)，X 軸電機(jī)的抖動(dòng)消除，機(jī)床加工精度恢復(fù)正常。4． 機(jī)床位置環(huán)異常或控制邏輯不妥 一臺(tái)TH61140加工中心，系統(tǒng)是FANUC18I，全閉環(huán)控制方式。加工過程中，發(fā)現(xiàn)該機(jī)床Y軸精度異常，精度誤差最小為0.006mm ，最大為1.4mm。檢查中，機(jī)床已經(jīng)按照要求設(shè)置了G54工件坐標(biāo)系。在MDI （手動(dòng)數(shù)據(jù)輸入方式）方式下，以G54坐標(biāo)系運(yùn)行一段程序即“G00G90G54Y80F100 ；M30；”，待機(jī)床運(yùn)行結(jié)束后顯示器上顯示的機(jī)械坐標(biāo)值為“-1046.605”，記錄下該數(shù)值。然后在手動(dòng)方式下，將機(jī)床點(diǎn)動(dòng)到其他任意位置，再次在MDI方式下運(yùn)行上次的程序段，待機(jī)床停止后，發(fā)現(xiàn)此時(shí)機(jī)床機(jī)械坐標(biāo)數(shù)值顯示為“-1046.992”，同第一次執(zhí)行后的數(shù)值相比差了0.387mm。按照同樣的方法，將Y 軸點(diǎn)動(dòng)到不同的位置，反復(fù)執(zhí)行該程序段顯示器上顯示的數(shù)值不定。用百分表對(duì)Y 軸進(jìn)行仔細(xì)檢查，發(fā)現(xiàn)機(jī)械位置實(shí)際誤差同數(shù)顯顯示出的誤差基本一致，從而認(rèn)為故障原因?yàn)閅 軸重復(fù)定位誤差過大。對(duì)Y軸的反向間隙及定位精度進(jìn)行檢查，重新做補(bǔ)償，均無效果。因此懷疑光柵尺及系統(tǒng)參數(shù)等有問題。但為什么產(chǎn)生如此大的誤差，卻未出現(xiàn)相應(yīng)的報(bào)警信息呢？進(jìn)一步檢查發(fā)現(xiàn)，次軸為垂直方向的軸，當(dāng)Y 軸松開時(shí)主軸箱向下掉，造成了誤差。 對(duì)機(jī)床的PLC 邏輯控制程序做了修改，即在Y軸松開時(shí)，先把Y 軸使能加載，再把Y軸松開；而在夾緊時(shí)，先把軸夾緊后，再把 Y軸使能去掉。調(diào)整后機(jī)床故障得以解決。CNC machining accuracy of the abnormal fault diagnosis and treatmentProduction often encounter unusual precision CNC machining of the fault. Such failure concealed strong, and the diagnosis more difficult. Such a failure of the main reasons there are five areas: (1) machine tool unit to be altered or changed. (2)-axis machine tools all the 0.1 bias [NULL OFFSET] anomaly. (3) axial reverse the gap [BACK LASH] anomaly. (4) abnormal motor running, electrical and control of the anomaly. (5) mechanical failure, such as the screw, bearings, shaft and other components for the. In addition the establishment of procedures for processing, tool selection and human factors, may also lead to abnormal processing accuracy1. System parameters change or alterationSystem parameters including machine feeding units, 0.1 bias, such as reverse gap. For example, SIMENS, FANUC system, feeding its metric and English units of two. Machine repair in certain treatment, often affecting 0.1 gap and offset the change, fault should be disposed of after timely adjustments and amendments on the other hand, due to mechanical wear or link may also be caused by loose parameters measured the changes , The parameters need to be revised accordingly to meet the requirements of precision machining.2. Mechanical failure caused by abnormal processing precisionTHM6350 a vertical machining centers, used SIMENS 840D system. Die-processing in the process, suddenly found Z-axis feed anomaly, at least one millimeter of error of cutting (Z to the cut-off). In that survey: the fault is all of a sudden. Machine tools to move in, MDI (manual data input method) mode of operation under normal operation of the shaft, and the reference point back to normal without any warning tips, electrical control of the hard rule out the possibility of failure. Analysis, the main one by one the following aspects should be checked[1] check accuracy of abnormal machine is running at the processing procedures, the length of particular tool compensation, processing coordinates (G54-G59) the proof-reading and computing. [2] to move in the way, the Z-axis movement repeatedly, through visual, touch, listen to their campaign of state, found that the noise Z to the abnormal movement, in particular to move fast, noise more pronounced. This judgement, machinery possible hidden dangers[3] Z-axis precision machine tool inspection. Using hand-cranked generator mobile Z-axis, (its rate set at the Shift 1 X100, which is in step, the electrical feed 0.1 mm), with Bai Fenbiao observe the movement of Z-axis. In a one-way movement to maintain normal accuracy of the positive movement as a starting point, every change in pulse-step machine Z-axis movement of the actual distance d = dl = d2 = d3… .= 0.1 mm, that motor running well and also positioning accuracy Good. Back to the actual movement and displacement of the machine changes, can be divided into four stages:① machine movement distance d1> d = 0.1mm (slope greater than 1); ② show for d1 = 0.1> d2> d3 (slope less than 1); ③ machine actually did not move bodies, showing the most standard reverse gap ; ④ movement from the machine and pulse for a given numerical equivalent (slope equal to 1), return to the normal movement of the machineNo matter how the reverse gap (parameters 1851) compensation to their performance characteristics: In addition to ③ stage to compensation, all of the other changes still exist, especially ① stage seriously affect the accuracy of the processing machine. Compensation found that the greater the compensation gap, ① stage of moving from the greaterAnalysis of the inspection that there may be a few reasons: First, motor abnormalities and the other is in a mechanical fault; three screw there is space. In order to further diagnose problems, and the screw will be fully undocked from the electrical, mechanical and electrical were part of the inspection. Inspection results of the electrical operating normally in the diagnosis of the mechanical parts that move hand-screw, to return to the initial campaign have a very clear sense of vacancy.And under normal circumstances, should be able to feel bearing orderly and smooth movement. After the demolition inspection found that it really damaged bearings, and the ball is falling. After the replacement machine back to normal3. Machine did not optimize the electrical parameters of abnormal motor runningBeijing has a capacity of vertical milling machine, equipped with SIMENS840D system. In the process, we found abnormal X-axis precision. X-axis inspection found that there are certain gaps, and the motor of instability at the start of the phenomenon. A hand touching the X-axis motor, sensory motor jitter relatively powerful, and stop dithering is not obvious, especially under way to move more obvious. Analysis of that failure for two reasons, First, screw reverse big gap and the other is abnormal X-axis electrical work. SIMENS system using the parameters of function, the motor debugging. First on the compensation gap, adjusting the servo gain parameters and pulse suppression parameters, X-axis motor to eliminate the jitter, precision machining back to normal4. Central location of machine control logic is nothing wrong or unusualTH61140 a processing center, the system is FANUC18I, closed-loop control the whole way. In the process, found that the Y-axis precision machine tools abnormal, the smallest error for the accuracy of 0.006 mm, the largest to 1.4 mm. During the inspection, and machine tools have been set up G54 in accordance with the requirements of the workpiece coordinates. In MDI (manual data input method) mode, the G54 to coordinate procedures for running a section that is "G00G90G54Y80F100; M30;", machine tool operation to be displayed on the monitor after the end of the mechanical coordinates for the "-1046.605," a record of the numerical.Then in the manual mode, the machine will be to move to any other location, again running under way in the last MDI procedures, the question following the cessation of machine tools, machine tools found at this time numerical mechanical coordinates displayed as "-1046.992," with the first After the implementation of the numerical difference compared to the 0.387 mm. In accordance with the same methods, will move the Y-axis to a different location and repeatedly monitor the implementation of the program displayed on the numerical uncertain. Bai Fenbiao with the Y-axis to double-check and found that mechanical error with the actual location of the show was basically the same error, the reasons for that failure to repeat Y-axis positioning error too large.Y-axis on the reverse gap and positioning accuracy check and re-do of compensation, no effects. Therefore suspected grating device and system parameters such as a problem. But why have such a large error, the alarm has not been a corresponding information? ? Further inspection found that the vertical axis of the shaft, when the Y-axis release me down when the spindle out, causing the error.The PLC logic of the machine tool control program made changes, that is, in the Y-axis release, the first Y-axis can be loaded, then release the Y axis and in clamping, the first axle clamp, then Y-axis can be removed. After adjusting machine fault is resolved.