加工中心主軸傳動系統(tǒng)設(shè)計(jì)
加工中心主軸傳動系統(tǒng)設(shè)計(jì),加工,中心,主軸,傳動系統(tǒng),設(shè)計(jì)
摘 要
加工中心由于備有刀庫并能自動更換刀具，使得工件在一次裝夾中可以完成多工序的加工。加工中心一般不需要人為干預(yù)，當(dāng)機(jī)床開始執(zhí)行程序后，它將一直運(yùn)行到程序結(jié)束。加工中心還賦予了專業(yè)化車間一些諸多優(yōu)點(diǎn)，如：降低機(jī)床的故障率，提高生產(chǎn)效率，提高加工精度，削減廢料量，縮短檢驗(yàn)時間，降低刀具成本，改善庫存量等。由于加工中心的眾多優(yōu)勢，所以它深受全球制造企業(yè)的青睞。
加工中心主要由主軸組件、回轉(zhuǎn)工作臺、移動工作臺、刀庫及自動換刀裝置以及其它機(jī)械功能部件組成。其中的主軸組件是機(jī)床重要的組成部分，其運(yùn)動性能直接影響機(jī)床加工精度與表面粗糙度。本文在查閱大量國內(nèi)外文獻(xiàn)的基礎(chǔ)上，通過研究分析不同加工中心主軸組件的性能，綜合地比較了其特點(diǎn)，并擬定了一個較為合理的主軸組件結(jié)構(gòu)方案。同時，還就主軸、軸承以及絲杠等重要零件的機(jī)械性能進(jìn)行了探討，并對這些零件的剛度和強(qiáng)度進(jìn)行了校核。此外，本設(shè)計(jì)中所采用的陶瓷軸承能有效地增加主軸的剛度，從而提高了加工中心的可靠性和穩(wěn)定性。
關(guān)鍵詞 主軸組件；加工中心；數(shù)控機(jī)床
I
Abstract
Machining center evolved from the need to be able to perform a variety of operations and machining sequences on a workpiece on a single machine in one setup. Machining center requires little operator intervention, and once the machine has been set up, it will machine without stopping until the end of the program is reached. Some of the other advantages that machining centers give a manufacturing shop are greater machine uptime, increased productivity, maximum part accuracy, reduced scrap, less inspection time, lower tooling costs, less inventory and so on. Because of their many advantages, machining centers become widely accepted by manufacturing enterprises in the world.
Machining centers are equipped with spindle units, rotary workbench, moving workbench, tool magazines and automatic tool changers, and other mechanical function components. Spindle unit is the important motion part of the metal cutting machine tool. Its movement behavior affects the machining accuracy and surface roughness of part to be machined. Through referring to a variety of technical literatures, the characteristics of some kinds of spindle units are compared with each other based on analysis and research work on different machining centers. A reasonable scheme can be studied out. Meanwhile, the mechanical behaviors of principle parts such as the spindle, bearings and lead screw are discussed. Their rigidity and strength are calculated and examined here. Morever, a kind of advanced ceramic bearings is introduced into the spindle unit, which can effectively enhance the rigidity of spindle units. They will improve the reliability and stability of machining centers.
Key words spindle unit;machining center; NC machine tool
-II-
目 錄
摘 要 I
Abstract II
第1章 緒 論 1
1.1 加工中心的發(fā)展?fàn)顩r 1
1.1.1 加工中心的國內(nèi)外發(fā)展 1
1.1.2 主軸部件的研究進(jìn)展 2
1.3 課題擬解決的關(guān)鍵問題 3
1.4 解決上述問題的策略 4
第2章 方案擬定 5
2.1 加工中心主軸組件的組成 5
2.2 機(jī)械系統(tǒng)方案的確定 5
2.2.1 主軸傳動機(jī)構(gòu) 5
2.2.2 主軸進(jìn)給機(jī)構(gòu) 6
2.2.3 主軸準(zhǔn)停機(jī)構(gòu) 7
2.3 加工中心主軸組件總體設(shè)計(jì)方案的確定 9
第3章 主軸組件的主運(yùn)動部件 11
3.1 主軸電動機(jī)的選用 11
3.1.1 主電機(jī)功率估算 11
3.1.2 主電機(jī)選型 12
3.2 主軸 12
3.2.1 主軸的結(jié)構(gòu)設(shè)計(jì) 12
3.2.1.1 主軸軸徑的確定 13
3.2.2 主軸受力分析 13
3.2.3 主軸的強(qiáng)度校核 16
3.2.4 主軸的剛度校核 17
3.2.5 軸承的配合 18
3.2.6 主軸軸承設(shè)計(jì)計(jì)算 18
3.2.6.1 軸承受力分析 18
3.2.6.2 軸承7017AC壽命計(jì)算 19
3.2.6.3 軸承7015AC壽命計(jì)算 19
3.3同步帶的設(shè)計(jì)計(jì)算 20
第4章 主軸組件的進(jìn)給運(yùn)動部件 24
4.1 進(jìn)給電動機(jī)的選用 24
4.1.1 進(jìn)給電動機(jī)功率的估算 24
4.1.2 進(jìn)給電動機(jī)的選用 24
4.2 聯(lián)軸器的設(shè)計(jì)計(jì)算 25
4.3 垂直方向伺服進(jìn)給系統(tǒng)的設(shè)計(jì)計(jì)算 25
4.3.1 切力削估算 25
4.3.2 滾珠絲杠副的設(shè)計(jì)計(jì)算 26
4.3.2.1 滾珠絲杠的導(dǎo)程的確定 26
4.3.2.2 確定絲杠的等效轉(zhuǎn)速 26
4.3.2.3 確定絲杠的等效負(fù)載 26
4.3.2.4 確定絲杠所受的最大動載荷 27
結(jié) 論 28
致 謝 30
參考文獻(xiàn) 31
附錄1 33
附錄2 37
-IV-
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附錄1
中文名稱：機(jī)械加工中心 英文名稱：machining center 其他名稱：自動換刀數(shù)控機(jī)床
定義：能自動更換工具，對一次裝夾的工件進(jìn)行多工序加工的數(shù)控機(jī)床。 機(jī)械加工中心,簡稱cnc，是由機(jī)械設(shè)備與數(shù)控系統(tǒng)組成的使用于加工復(fù)雜形狀工件的高效率自動化機(jī)床。加工中心又叫電腦鑼。加工中心備有刀庫，具有自動換刀功能，是對工件一次裝夾后進(jìn)行多工序加工的數(shù)控機(jī)床。加工中心是高度機(jī)電一體化的產(chǎn)品，工件裝夾后，數(shù)控系統(tǒng)能控制機(jī)床按不同工序自動選擇、更換刀具、自動對刀、自動改變主軸轉(zhuǎn)速、進(jìn)給量等，可連續(xù)完成鉆、鏜、銑、鉸、攻絲等多種工序，因而大大減少了工件裝夾時間、測量和機(jī)床調(diào)整等輔助工序時間，對加工形狀比較復(fù)雜，精度要求較高，品種更換頻繁的零件具有良好的經(jīng)濟(jì)效果。 按控制軸數(shù)可分為：
（1）三軸加工中心
（2）四軸加工中心
（3）五軸加工中心。
項(xiàng)目二 機(jī)械加工中心設(shè)備技術(shù)分類 加工中心的品種、規(guī)格較多，這里僅從結(jié)構(gòu)上對其作一分類。
一、立式加工中心 指主軸軸線為垂直狀態(tài)設(shè)置的加工中心。其結(jié)構(gòu)形式多為固定立柱式，工作臺為長方形，無分度回轉(zhuǎn)功能，適合加工盤、套、板類零件。一般具有三個直線運(yùn)動坐標(biāo)，并可在工作臺上安裝一個水平軸的數(shù)控回轉(zhuǎn)臺，用以加工螺旋線零件。 立式加工中心裝夾工件方便，便于操作，易于觀察加工情況，但加工時切屑不易排除，且受立柱高度和換刀裝置的限制，不能加工太高的零件。 立式加工中心的結(jié)構(gòu)簡單，占地面積小，價(jià)格相對較低，應(yīng)用廣泛。
二、臥式加工中心 指主軸軸線為水平狀態(tài)設(shè)置的加工中心。通常都帶有可進(jìn)行分度回轉(zhuǎn)運(yùn)動的工作臺。臥式加工中心一般都具有三個至五個運(yùn)動坐標(biāo)，常見的是三個直線運(yùn)動坐標(biāo)加一個回轉(zhuǎn)運(yùn)動坐標(biāo)，它能夠使工件在一次裝夾后完成除安裝面和頂面以外的其余四個面的加工，最適合加工箱體類零件。 臥式加工中心調(diào)試程序及試切時不便觀察，加工時不便監(jiān)視，零件裝夾和測量不方便，但加工時排屑容易，對加工有利。與立式加工中心相比，臥式加工中心的結(jié)構(gòu)復(fù)雜，占地面積大，價(jià)格也較高。
3、 龍門式加工中心 龍門式加工中心的形狀與龍門銑床相似，主軸多為垂直設(shè)置，除自動換刀裝置外，還帶有可更換的主軸附件，數(shù)控裝置的功能也較齊全，能夠一機(jī)多用，尤其適用于加工大型或形狀復(fù)雜的零件，如飛機(jī)上的梁、框、壁板等。
我國加工中心的未來發(fā)展趨勢！
未來發(fā)展的前景確實(shí)喜人，不過吳柏林也表示，由于我國工業(yè)基礎(chǔ)相對薄弱、以企業(yè)為主體的創(chuàng)新體系尚未建立、數(shù)控車床產(chǎn)業(yè)化時間短等原因，技術(shù)上和產(chǎn)業(yè)上與西方發(fā)達(dá)國家相比還存在一定差距，當(dāng)前的發(fā)展還需要注意四個方面的問題。
2008年12月，《高檔數(shù)控車床與基礎(chǔ)制造裝備科技重大專項(xiàng)》得到國家批準(zhǔn)。專項(xiàng)對高檔數(shù)控車床等重大裝備、數(shù)控系統(tǒng)、功能部件與關(guān)鍵部件、共性技術(shù)、創(chuàng)新平臺建設(shè)及應(yīng)用示范工程做出了部署。“今年專項(xiàng)將開始逐步啟動實(shí)施，車床工具行業(yè)自主創(chuàng)新能力將進(jìn)一步提高，將為國產(chǎn)高檔數(shù)控車床持續(xù)發(fā)展奠定堅(jiān)實(shí)的技術(shù)基礎(chǔ)。”吳柏林說。
三年前接受中國工業(yè)報(bào)記者采訪時，吳柏林提出需要重視功能部件的發(fā)展，此時又被他再一次重點(diǎn)提出。功能部件發(fā)展滯后的狀況似乎并沒有太多的改觀。“數(shù)控車床的發(fā)展需要高水平、專業(yè)化、規(guī)?；a(chǎn)的功能部件作基礎(chǔ)，目前我國差距很大?！睋?jù)了解，大多數(shù)中高檔數(shù)控車床主要配套的還是發(fā)那科和西門子等國外數(shù)控系統(tǒng)，刀庫機(jī)械手、數(shù)控刀架、滾珠絲杠和導(dǎo)軌、電主軸等主要還是日本、德國或中國臺灣地區(qū)的產(chǎn)品，用戶選購國產(chǎn)車床時普遍提出選用境外功能部件的要求。功能部件發(fā)展的滯后性，將制約國產(chǎn)中高檔數(shù)控車床的發(fā)展。
吳柏林還認(rèn)為，當(dāng)前外商獨(dú)資趨勢應(yīng)引起重視。近幾年來，車床行業(yè)有些合資企業(yè)逐步擴(kuò)資轉(zhuǎn)為外商絕對控股或獨(dú)資，同時又新成立一批外商獨(dú)資企業(yè)，這些企業(yè)的產(chǎn)品以占領(lǐng)國內(nèi)中高端市場為目標(biāo)，其技術(shù)由國外母公司控制?！拔覀冇檬袌鰮Q不到技術(shù)，又喪失市場，客觀上壓制了國內(nèi)車床企業(yè)的產(chǎn)業(yè)升級?！?
首先是新產(chǎn)品開發(fā)能力不足。從行業(yè)總體看，基礎(chǔ)技術(shù)和關(guān)鍵技術(shù)研究還很薄弱，基礎(chǔ)開發(fā)理論研究、基礎(chǔ)工藝研究和應(yīng)用軟件開發(fā)還不能適應(yīng)數(shù)控技術(shù)快速發(fā)展的要求，全行業(yè)科技人才不足，缺乏高級技術(shù)人員，科技投入和科研設(shè)施尚不適應(yīng)等。據(jù)了解，當(dāng)前，國防軍工生產(chǎn)科研和國家重大工程提出的一批高端數(shù)控車床，如超重型雙龍門鏜銑床等，由于車床企業(yè)開發(fā)能力不足或完成開發(fā)的周期太長而不能承接合同，一些數(shù)控專機(jī)也由于開發(fā)人員缺乏而拖延。
同時，擴(kuò)大產(chǎn)能與未來實(shí)際需求錯位也需引起重視。當(dāng)前行業(yè)企業(yè)技術(shù)改造項(xiàng)目的產(chǎn)能目標(biāo)過于龐大，技改項(xiàng)目產(chǎn)品的大型化、重型化趨勢明顯，高檔數(shù)控車床制造能力和功能部件的投入顯得不足。而且，車床企業(yè)自身裝備的數(shù)控化率低，信息化管理水平不高，生產(chǎn)效率低，企業(yè)的競爭力沒有得到足夠的提高，“從行業(yè)整體看，是否與未來的市場需求相符，還需要研究。
數(shù)控機(jī)床是一種高技術(shù)設(shè)備,它可以通過改變數(shù)控程序,適應(yīng)不同零件的自動加工,而且可以采用較大的切削用量,利用軟件進(jìn)行精度校正和補(bǔ)償,從而提高生產(chǎn)效率、加工精度和加工質(zhì)量,可以實(shí)現(xiàn)工序集中、一機(jī)多用,能完成復(fù)雜型面的加工。數(shù)控機(jī)床是現(xiàn)代制造業(yè)的關(guān)鍵設(shè)備,一個國家的數(shù)控機(jī)床的產(chǎn)量和技術(shù)水平在某種程度上反映了這個國家的制造業(yè)水平和競爭力。因此數(shù)控機(jī)床是將來機(jī)床研制的重點(diǎn)。本文針對經(jīng)濟(jì)型數(shù)控立式銑床及其控制系統(tǒng)的設(shè)計(jì)作簡要的討論。
數(shù)控銑床是機(jī)械和電子技術(shù)相結(jié)合的產(chǎn)物，，它的機(jī)械結(jié)構(gòu)隨著電子控制技術(shù)的在銑床上的餓應(yīng)用，以及銑床性能提出的新要求，而逐步變化。與不同銑床相比數(shù)控銑床用三個數(shù)控伺服系統(tǒng)替代了傳統(tǒng)的機(jī)械進(jìn)給系統(tǒng)，其外形和結(jié)構(gòu)與普通銑床類似。數(shù)控銑床的設(shè)計(jì)主要是進(jìn)行主運(yùn)動系統(tǒng)與進(jìn)給系統(tǒng)的機(jī)械結(jié)構(gòu)設(shè)計(jì)和控制系統(tǒng)設(shè)計(jì)
通常，一個典型的數(shù)控機(jī)床進(jìn)給系統(tǒng)，由位置比較，放大元件、驅(qū)動單元、機(jī)械傳動裝置和檢測反饋元件等幾部分組成。其中，機(jī)械傳動裝置是位置控制中的一個重要環(huán)節(jié)。這里所說的機(jī)械傳動裝置，是指將驅(qū)動源的旋轉(zhuǎn)運(yùn)動變?yōu)楣ぷ髋_的直線運(yùn)動的整個機(jī)械傳動鏈，包括齒輪裝置、絲杠螺母副等中間傳動機(jī)構(gòu)。
齒輪傳動是應(yīng)用非常廣泛的一種機(jī)械傳動，各種機(jī)床的傳動裝置中幾乎都有齒輪傳動。在數(shù)控機(jī)床伺服進(jìn)給系統(tǒng)中采用齒輪傳動裝置的目的有兩個。一是將高轉(zhuǎn)速的轉(zhuǎn)矩的伺服電機(jī)（如步進(jìn)電機(jī)、直流和交流伺服電機(jī)等）的輸出改變?yōu)榈娃D(zhuǎn)速大轉(zhuǎn)矩的執(zhí)行件的輸入；另一是使?jié)L珠絲杠和工作臺的轉(zhuǎn)動慣量在系統(tǒng)中專有較小的比重。此外，對于開環(huán)系統(tǒng)還可以保證所要求的運(yùn)動精度。
為了盡量減小齒側(cè)間隙對數(shù)控機(jī)床加工精度的影響，經(jīng)常在結(jié)構(gòu)上采取措施，以減小或消除齒輪副的空程誤差。如采用雙片齒輪錯齒法、利用偏心套調(diào)整齒輪副中心距或采用軸向墊片調(diào)整法消除齒輪側(cè)隙。
這里進(jìn)給系統(tǒng)采用步進(jìn)電機(jī)開環(huán)控制，由滾珠絲杠螺母副來實(shí)現(xiàn) ，縱向和橫向進(jìn)給采用130BF001型步進(jìn)電機(jī)驅(qū)動，經(jīng)圓柱齒輪傳動帶動滾珠絲杠傳動，通過絲杠螺母機(jī)構(gòu)來實(shí)現(xiàn)；垂直方向進(jìn)給運(yùn)動由150BF003型步進(jìn)電機(jī)驅(qū)動，經(jīng)圓錐齒輪帶動滾珠絲杠傳動。縱向和橫向齒輪可采用斜齒輪彈簧調(diào)整法來消除齒輪間隙；垂直方向的齒輪間隙可采用圓錐齒輪周向彈簧調(diào)整法來消除。
附錄2
What is the mechanical machining center?
Chinese Name: Machining Center English Name: Machining Center Title:
automatic tool changing definition: can automatically replace the tool, NC machining of a workpiece fixture. Machining center, referred to as CNC, is composed of mechanical equipment and CNC system for machining of complex high automation tool shape workpiece. Machining center is also called computer gongs. Machining center with knife, the knife has the function of automatic change, is the NC machining of a workpiece fixture after. Machining center is a kind of mechanical and electrical products, workpiece clamping, the CNC system can control the machine tool according to different process automatic selection, automatic tool setting, automatic tool change, change the spindle speed, feed, which can continuously complete drilling, boring, milling, tapping, reaming and many other processes, thus greatly reducing the workpiece clamping time, measuring tools and adjust the auxiliary operation time, processing more complex shapes, high precision, varieties of frequent replacement of parts with good economic effect. According to the number of control axis can be divided into:
(1) three axis machining center,
(2) four axis machining center
(3) of five axis machining center. Many items of equipment technology of the two machining center classification processing center varieties, specifications, here only the structure makes the classification. A vertical machining center, a machining center spindle axis arranged vertically. Its structure is of a fixed column, table is rectangular, no dividing rotating function, suitable for machining disc, cover, plate parts. There are three general rectilinear motion coordinate, NC rotary table and can be installed in a horizontal axis on a workbench, used for processing spiral parts. Vertical machining center fixture workpiece convenient, easy to operate, easy to processing, but the processing chip is not easy to remove, and the height of the column and the knife changing device limitations, can not be too high parts processing. Structure of vertical machining center, covers an area of small, relatively low price, widely used. Two, horizontal machining center machining center spindle axis refers to the state level settings. Usually with a work table indexing rotary motion. Horizontal machining center has three to five moving coordinate, common is three rectilinear motion coordinate with a rotary motion coordinate, it can make parts except the mounting surface and the top surface of the remaining four face machining in a fixture to complete, the most suitable for processing box type parts. Horizontal machining center debugging and test cutting processing is inconvenient inconvenient observation, monitoring, clamps and measurement is not convenient, but when processing chip easily, the processing advantage. Compared with the vertical machining center, horizontal machining center structure complex, covering an area of large, the price is higher also. Three, Longmen Longmen machining center machining center and Longmen similar shape milling machine, spindle is arranged vertically, in addition to the automatic tool change device, but also with a spindle attachment can be replaced, NC device's function is more complete, to the use of a machine, especially suitable for processing large or complex shape parts, as the plane beam, frame, panels etc.
Future development trend of China's processing center!
未來發(fā)展的前景確實(shí)喜人，不過吳柏林也表示，由于我國工業(yè)基礎(chǔ)相對薄弱、以企業(yè)為主體的創(chuàng)新體系尚未建立、數(shù)控車床產(chǎn)業(yè)化時間短等原因，技術(shù)上和產(chǎn)業(yè)上與西方發(fā)達(dá)國家相比還存在一定差距，當(dāng)前的發(fā)展還需要注意四個方面的問題。
Future is indeed gratifying, but Wu Bailin also said that, due to China's relatively weak industrial base, with enterprises as the mainstay of the innovation system has not been established, CNC lathe industry in short time and other reasons, the technology and the industry compared with the western developed countries still have a certain gap, the current development also need to pay attention to four aspects the problem.
2008年12月，《高檔數(shù)控車床與基礎(chǔ)制造裝備科技重大專項(xiàng)》得到國家批準(zhǔn)。專項(xiàng)對高檔數(shù)控車床等重大裝備、數(shù)控系統(tǒng)、功能部件與關(guān)鍵部件、共性技術(shù)、創(chuàng)新平臺建設(shè)及應(yīng)用示范工程做出了部署。“今年專項(xiàng)將開始逐步啟動實(shí)施，車床工具行業(yè)自主創(chuàng)新能力將進(jìn)一步提高，將為國產(chǎn)高檔數(shù)控車床持續(xù)發(fā)展奠定堅(jiān)實(shí)的技術(shù)基礎(chǔ)?！眳前亓终f。
In 2008 December, "major projects" lathe and basic manufacturing equipment and technology approved by the national high-end cnc. Special made the deployment of high-grade CNC lathes and other major equipment, CNC system, functional components and key parts, common technology, innovation platform construction and application demonstration project. "Special will be started this year gradually started, the ability of independent innovation lathe tool industry will be further enhanced, will lay a solid technical foundation for the sustainable development of domestic high-end CNC lathe." Wu Bailin said.
Accept China industrial daily news reporter interviewed three years ago, Wu Bailin put forward the need to attach importance to the development of functional components, then he again put forward. Functional components development lags behind the situation does not seem too much. "The development of numerical control lathe to feature high level, specialized, large-scale production base, at present our country difference." It is understood, the majority of high-grade CNC lathe main supporting or FANUC and Siemens abroad NC system, the knife manipulator, CNC turret, ball screw and guide rail, spindle, mainly Japan, Germany or Chinese Taiwan products, generally the foreign function parts require users to buy domestic lathe. Hysteresis function components development, to restrict the development of domestic high-end CNC lathe.
Wu Bailin also believes that the current foreign investment trend, attention should be paid to. In recent years, lathe industry some joint ventures are gradually expanding to foreign capital holding or sole proprietorship, and at the same time, the newly established a number of wholly foreign-owned enterprises, the products of these enterprises to occupy the domestic high-end market as the goal, the technology is controlled by the foreign parent company. "We use market for less than the technology, the loss of market, objectively to suppress the domestic lathe industrial upgrading of enterprises."
The first is the lack of the ability of new product development. From the industry overall look, the technology and the key technology is still very weak foundation, foundation for the development of theoretical research, basic technology research and application of software development can not meet the requirements of the rapid development of NC technology, science and technology talents in all industries, the lack of senior technical personnel, investment in science and technology and research facilities are not adapt. It is understood, at present, national defense scientific research and production of major national projects proposed a number of high-end CNC lathe, such as super heavy double gantry boring and milling machine, lathe enterprises due to the periodic development ability is insufficient or completion of the development is too long and can not accept the contract, some special NC machine because developers lack of delay.
At the same time, the expansion of production capacity and actual future demand mismatches also need to pay attention. The current industry enterprise technical transformation project of the production target is too large, large, heavy trends of technological transformation project products obviously, high-end CNC lathe manufacturing capacity and functional components of the input is insufficient. Moreover, the rate of NC lathe enterprises its equipment is low, the information management level is not high, the production efficiency is low, the competitiveness of enterprises has not been enough to raise, "look from the whole industry, in line with the future market demand, but also need to study
NC machine tool is a kind of high technology equipment, it can change the NC program, adapt to the automatic processing of different parts, but also can use a larger amount of precision cutting, correction and compensation for the use of the software, so as to improve the production efficiency, machining precision and machining quality, can realize the process using concentrated, a machine, can complete the machining of complex surface. NC machine tool is the key equipment of modern manufacturing, numerical control machine tool of a country's production and technical level reflects the level of manufacturing industry and competitiveness of the country in a certain extent. Therefore NC machine tool is the key tool for the future. According to the design of the economical CNC vertical milling machine and its control system are briefly discussed.
CNC milling machine products, machinery and electronic technology combined, the mechanical structure of the electronic control technology in milling hungry applications, as well as the new requirements proposed by performance, and gradually change. Compared with different milling machine CNC milling machine to replace the traditional mechanical feed system with three CNC servo system, its shape and structure and the ordinary milling machine similar. Design of NC milling machine is mainly the design of mechanical structure design and control system of the main motion system and feed system
Usually, a typical NC machine tool feed system, the position is, the amplification element, a driving unit, a mechanical driving device and a feedback element and other parts. Among them, the mechanical driving device is an important link in the position control. The mechanical transmission device here, refers to the entire mechanical transmission chain rotational movement of the driving source into linear motion worktable, including gears, lead screw intermediate transmission mechanism.
Gear is a mechanical transmission is widely used, almost all transmission devices of various machine in gear transmission. The gear transmission device in the NC machine tool servo system has two purposes. One is the high speed of the servo motor torque (such as stepper motors, DC and AC servo motor etc.) output change of low speed and high torque actuator input; the other is the moment of inertia of table and ball screw are smaller in proper proportion. In addition, for the open loop system can also ensure the precision required.
In order to minimize the impact on small side gap of machining accuracy of NC machine tools, often take measures in structure, to reduce or eliminate the deadpath error of gear pair. Such as the use of double gear tooth method, using the eccentric sleeve adjusting gear center distance or the axial shim adjustment method to eliminate the gear backlash.
Here the feed system uses the open-loop control of a stepper motor, a ball screw pair to achieve, longitudinal and transverse feed using 130BF001 type step motor drive, drive the ball screw drive with cylindrical gear transmission, to realize the screw nut mechanism; vertical direction feed motion driven by 150BF003 stepper motor, drives the ball screw drive the bevel gear. The longitudinal and transverse gear can be used to eliminate the backlash of the gear helical gear spring adjustment method; gear gap perpendicular to the direction of the cone gear circumferential spring adjusting method to eliminate.
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