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智能機器人傳菜員總體方案設(shè)計及液壓端盤機械手的設(shè)計與制作
Intelligent pass-through member of robot ’s overall scheme designed with devising and manufacture of hydraulic manipulator end plate
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智能機器人傳菜員總體方案設(shè)計及液壓端盤機械手的設(shè)計與制作
1. 論文結(jié)構(gòu)
1.1 總體結(jié)構(gòu)的設(shè)想
論文的總體結(jié)構(gòu)將做如下安排:
1.綜述目前國內(nèi)外餐廳智能機器人傳菜員及相關(guān)智能服務(wù)機器人的基礎(chǔ)理論研究與應(yīng)用研究狀況、餐廳智能服務(wù)機器人及相關(guān)智能服務(wù)機器人的機械結(jié)構(gòu)、控制系統(tǒng)、檢測系統(tǒng)的研究狀況、市場上已投入運作的相關(guān)機器人其主要的控制方式。
2.分析餐廳能機器人傳菜員的工作環(huán)境及工作條件。做出總體方案設(shè)計及布局。
3.將機器人分為機械系統(tǒng)、檢測系統(tǒng)及控制系統(tǒng)三大部分進行研究。并進行機械系統(tǒng)設(shè)計、檢測方法及傳感器的選擇、控制程序的編寫。
4.實物制作調(diào)試、實驗并分析。
5.根據(jù)理論及實驗分析,得出結(jié)論。
1.2 主要解決的問題
1.調(diào)整傳感器及控制方式,保證機器人在行走時的穩(wěn)定性,機器人在循跡行走時不偏離設(shè)定軌跡。
2.調(diào)整機器人在工作時機械手的工作方式,確保每次能找到、抓到盤子并將其送至餐桌。
3.機器人整體程序協(xié)調(diào)控制。
1.3 主要工作
1.主要完成系統(tǒng)總體方案圖的設(shè)計
2.主要完成該機器人液壓系統(tǒng)圖的設(shè)計,同時確定所需要的零件的品牌和型號。
3.主要完成三組傳感器安排和設(shè)計。
4.主要完成該機器人控制程序設(shè)計框圖,并輔助編制控制程序
5.主要完成根據(jù)設(shè)計圖紙監(jiān)控該機器人制造全過程。并實施裝配
6.主要完成對機器人/傳感器和控制程序進行運動調(diào)試。
7.負(fù)責(zé)總體安排參加的大賽全面協(xié)調(diào)工作。
2. 文獻綜述
2.1 智能餐廳服務(wù)機器人及其相關(guān)智能服務(wù)機器人技術(shù)的基礎(chǔ)理論與應(yīng)用研究
在人民生活水平不斷提高、科技日新月異的時代,機器人將逐步走入人類的日常生活,與人類友好共處,是未來社會生活發(fā)展的必然趨勢。服務(wù)機器人系統(tǒng)技術(shù)不僅是智能機器人發(fā)展的前沿技術(shù),也是引領(lǐng)人類未來生活新模式、培育機器人新產(chǎn)業(yè)革命的一種核心技術(shù)。
智能機器人領(lǐng)域起源歐美發(fā)達國家,自動化控制技術(shù)現(xiàn)在日本、德國、法國等發(fā)達國家領(lǐng)先于各個國家,但真正應(yīng)用民用行業(yè)的還十分罕見,日本早期研制出一款類人型服務(wù)機器人,技術(shù)先進,但僅限于技術(shù)研發(fā),突破相關(guān)技術(shù)問題,實用性不強。智能服務(wù)機器人是在非結(jié)構(gòu)環(huán)境下為人類提供必要服務(wù)的多種高技術(shù)集成的智能化裝備,研究設(shè)計方法、制造工藝、智能控制和應(yīng)用系統(tǒng)集成等共性基礎(chǔ)技術(shù)。智能服務(wù)機器人技術(shù)集機械、電子、材料、計算機、傳感器、控制等多門學(xué)科于一體,是國家高科技實力和發(fā)展水平的重要標(biāo)志,目前國際智能服務(wù)機器人研究主要集中在德國、日本等國家,并成功將智能服務(wù)機器人應(yīng)用于各個行業(yè)中,我國近些年在智能服務(wù)機器人研究方面也取得很多進展,很多機器人研發(fā)公司將研究重點轉(zhuǎn)向智能服務(wù)機器人開發(fā)。而作為餐廳這樣一個服務(wù)型行業(yè),智能機器人以替代人工的勞動也顯得尤為重要。
餐廳服務(wù)機器人的研究主要依靠于機電一體化技術(shù),將計算機控制、電機控制技術(shù)及機械有機構(gòu)有機的配合起來,通過傳感技術(shù)實現(xiàn)形高精度、高可靠性、的智能服務(wù),大多數(shù)機器人控制系統(tǒng)控制系統(tǒng)主要依托于51單片機來控制。如北京工業(yè)大學(xué)的“輪式智能自主移動服務(wù)機器人”其主要工作原理是采用了圖像采集系統(tǒng)來對機器人周圍環(huán)境進行分析計算,進行導(dǎo)航。行走模式為輪式,上部為復(fù)雜的前后移動可動式機械結(jié)構(gòu)。理論上存在可行性,實際運營中存在兩個最大的技術(shù)難點,由于上身復(fù)雜機械結(jié)構(gòu)和大數(shù)據(jù)復(fù)雜的圖像運算都需要比較大量供電系統(tǒng),在實際服務(wù)過程中存在供電不足現(xiàn)象。第二由于其數(shù)據(jù)定位是給予圖像計算,因此其計算的反應(yīng)速度將遠(yuǎn)遠(yuǎn)達不到現(xiàn)實要求的速度,實際服務(wù)過程中嚴(yán)重影響客戶的服務(wù)體驗。再例如深圳先進技術(shù)研究院的“一種餐廳服務(wù)機器人系統(tǒng)”此項系統(tǒng)設(shè)計包括了,控制模塊、行進模塊、交互模塊、感知模塊、執(zhí)行模塊。各種電子模塊很多,但回避了一個機器人最基本的功能,就是機器人如何到達其所要到達的位置,如何定位機器人所在位置,及機器人在到達過程中遇到障礙,躲避后路線選擇的問題。
2.2 餐廳智能服務(wù)機器人的研究現(xiàn)狀
起初智能服務(wù)機器人的研究其控制模式都比較復(fù)雜,成本較高,不適用于實際生活,如北京工業(yè)大學(xué)的“輪式智能自主移動服務(wù)機器人”其主要工作原理是采用了圖像采集系統(tǒng)來對機器人周圍環(huán)境進行分析計算,進行導(dǎo)航。行走模式為輪式,上部為復(fù)雜的前后移動可動式機械結(jié)構(gòu)。理論上存在可行性,實際運營中存在兩個最大的技術(shù)難點,由于上身復(fù)雜機械結(jié)構(gòu)和大數(shù)據(jù)復(fù)雜的圖像運算都需要比較大量供電系統(tǒng),在實際服務(wù)過程中存在供電不足現(xiàn)象。第二由于其數(shù)據(jù)定位是給予圖像計算,因此其計算的反應(yīng)速度將遠(yuǎn)遠(yuǎn)達不到現(xiàn)實要求的速度,實際服務(wù)過程中嚴(yán)重影響客戶的服務(wù)體驗。再例如深圳先進技術(shù)研究院的“一種餐廳服務(wù)機器人系統(tǒng)”此項系統(tǒng)設(shè)計包括了,控制模塊、行進模塊、交互模塊、感知模塊、執(zhí)行模塊。各種電子模塊很多,但回避了一個機器人最基本的功能,就是機器人如何到達其所要到達的位置,如何定位機器人所在位置,及機器人在到達過程中遇到障礙,躲避后路線選擇的問題。再如山東大陸科技有限公司設(shè)計的一款設(shè)置有控制器以及與控制器連接的動力裝置、驅(qū)動裝置、行走裝置、無線信號傳輸裝置和語音裝置的餐廳服務(wù)機器人主要依靠磁條循跡,通過磁性傳感器、讀卡器和若干存有編號數(shù)據(jù)的磁性增強卡,設(shè)置在每個餐位處并且其編號數(shù)據(jù)與餐位順序編碼相對應(yīng),所述磁性傳感器和讀卡器與控制器連接,磁性傳感器用于檢測導(dǎo)軌的磁性信號,讀卡器用于讀取主體所經(jīng)過的磁性增強卡的編碼數(shù)據(jù),所述控制器用于根據(jù)磁性信號確定導(dǎo)軌位置,同時判斷接收到的編號數(shù)據(jù)與預(yù)設(shè)的餐位順序編碼是否對應(yīng),雖然說此設(shè)計較前兩種設(shè)計已是簡便不少,可是在實際餐廳磁條如何鋪設(shè)也是一種問題,而且無法實現(xiàn)機器人的360度轉(zhuǎn)彎,無法實現(xiàn)沿原路返回。同時所有機器人只能提供將菜送至桌旁,無法將餐盤送至桌子上,同時將空盤子回收的功能。根據(jù)現(xiàn)狀我們便想開發(fā)一款結(jié)構(gòu)更簡單,控制更方便,功能更齊全的餐廳服務(wù)機器人。
2.3 對于餐廳智能機器人傳菜員系統(tǒng)設(shè)計方案的綜合分析
智能餐廳服務(wù)機器人主要建立于三大模塊上,即:控制系統(tǒng)、檢測系統(tǒng)和機械執(zhí)行系統(tǒng)??刂葡到y(tǒng)目前大多采用51單片機,通過建立相應(yīng)的算法,利用C語言編寫控制程序。51單片機是對所有兼容Intel8031指令系統(tǒng)的單片機的統(tǒng)稱。其代表型號是ATMEL公司的AT89系列,它廣泛應(yīng)用于工業(yè)測控系統(tǒng)之中。單片機中,CPU、RAM、ROM、輸入/輸出設(shè)備,全部被做到一塊集成電路芯片中,在附加其他電子元件便可組成一個控制電路板??刂葡到y(tǒng)一般由多個模塊組成,一般餐廳智能服務(wù)機器人設(shè)有語音模塊、電機模塊、紅外模塊、傳感模塊、液晶顯示模塊、無線模塊、報警模塊及時鐘模塊。而51單片機作為上位機控制這些所有模塊的按照指定的程序工作。
檢測模塊主要要多個不同的傳感器組成,一般磁鐵循跡,則會裝有磁性傳感器,黑條循跡則會裝有紅外傳感器。作為餐廳服務(wù)機器人則必須具有避障功能,一般障礙物檢測傳感器應(yīng)用較多的兩種是超聲波傳感器和紅外傳感器。而紅外傳感器相對超聲波傳感器更簡單方便一些。由多組不同傳感器的協(xié)調(diào)工作別組成了機器人的高準(zhǔn)確度。
機械機構(gòu)主要作為機器人的執(zhí)行機構(gòu),則要求簡單靈活。現(xiàn)在多數(shù)采用四輪但轉(zhuǎn)彎半徑要求較大,電機數(shù)目較多,不方便機器人自身的協(xié)調(diào)與控制,而且耗電量較大。而具備機械手設(shè)計的餐廳智能服務(wù)機器人更是沒有。作為機械手的設(shè)計目前已廣泛應(yīng)用于工業(yè)生產(chǎn),但作為送餐機械手,工作性能要求更高。
2.5 餐廳服務(wù)機器人的國內(nèi)外研究概述
公共服務(wù)機器人近年來得到快速發(fā)展,并且已經(jīng)應(yīng)用到公共場所為人類服務(wù)。例如,在展覽會會場、辦公大樓、旅游景點為客人提供信息咨詢服務(wù)的迎賓導(dǎo)游機器人[1],在建筑物內(nèi)或者居民區(qū)內(nèi)進行自動巡視的安防巡邏機器人[2]等,技術(shù)上都已經(jīng)比較成熟,已經(jīng)開始走向?qū)嶋H應(yīng)用。隨著社會的不斷發(fā)展進步,人們的人均收入提高,隨之而來的是人們的消費水平不斷地提高,從而大大地促進了餐飲業(yè)的迅速發(fā)展。在餐飲業(yè)領(lǐng)域,最繁雜的工作莫過于為顧客點餐和送餐等服務(wù)。由于人力成本的提高,餐館在服務(wù)人員的人力成本支出越來越高,如在日本、香港,普通服務(wù)員的工資和產(chǎn)業(yè)工人的工資已經(jīng)不相上下。如果使用機器人代替/部分代替服務(wù)員為顧客服務(wù),如點菜、送菜,不但能提高服務(wù)效率,減少服務(wù)人員數(shù)量,更能建立餐廳特色,打造餐廳品牌,進而提升餐廳的業(yè)績。餐廳服務(wù)機器人作為一類特殊的公共服務(wù)機器人,集成了移動機器人技術(shù)、多任務(wù)集成、人機交互、多模態(tài)分析等。因此,研究和開發(fā)餐廳服務(wù)機器人系統(tǒng),不僅可以積累研發(fā)其他服務(wù)機器人的技術(shù),具有重要的理論價值,還具有重大的實際應(yīng)用價值和廣闊的市場前景。
餐廳服務(wù)機器人作為一種特殊的服務(wù)機器人,集成了移動機器人、多傳感器信息融合和多模態(tài)人機交互等技術(shù),具有較高的理論價值;同時,餐廳服務(wù)機器人能夠代替或者部分代替餐廳服務(wù)員為顧客服務(wù),具有廣闊的市場前景。
加拿大L.Meeden等人于1999年研制了餐廳服務(wù)機器人Alfred[3],其外形似一只企鵝。Pantelis??Elinas等人于2002年研制了服務(wù)機器人José[4],José開始采用人形,具有上半身。José和Alfred都能通過語音識別技術(shù)進行人機對話。不同的是Alfred采用人工設(shè)置路標(biāo),基于超聲測距傳感器信息的導(dǎo)航和定位,而José采用是基于自然標(biāo)志物和視覺信息進行導(dǎo)航和定位。José和Alfred在嘈雜環(huán)境下的語音識別正確率很低,并且他們與顧客的互動性還比較差。José只能通過語音與顧客“交流”,這種方式在嘈雜環(huán)境中受到很大限制;Alfred除了語音“交流”之外,通過安裝在其本體上的筆記本電腦顯示臉部表情來和顧客交流,這種“交流”雖然表情豐富,但缺乏真實感。
臺灣國立云林科技大學(xué)和吳鳳技術(shù)學(xué)院合作研發(fā)了餐廳服務(wù)機器人[5],第一代餐廳服務(wù)機器人采用電磁導(dǎo)航,第二代采用激光測距傳感器進行導(dǎo)航,具有較好的定位和導(dǎo)航能力。
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[7]?趙興,閆維新,趙言正等.基于DSP和CPLD的自動烹飪機器人設(shè)計[J].機器人,2007,29
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摘要: 開發(fā)一款操作簡單、功能齊全、價格便宜的全自動智能送餐機器人。通過自主設(shè)計的獨輪行走機構(gòu)、三自由度液壓機械手及以 STC89C51 型單片機為控制核心的控制系統(tǒng)并結(jié)合循跡傳感器模塊、紅外傳感器模塊、繼電器模塊、及電機模塊,模擬真實餐廳環(huán)境??蓪崿F(xiàn)遙控輸入桌號及啟動、90°及180°轉(zhuǎn)彎、停止及餐桌位置判定、避障、餐盤定位、機械手自動送菜及原路返回等功能。其性能可靠,可實際應(yīng)用于餐廳。
關(guān)鍵詞:傳感器;循跡;機械手;餐桌定位
Abstract: For developing a simple, functional, inexpensive robot of automatic intelligent in serving dish, it’s using unicycle that through self-designed running gear, three DOF manipulator and as STC89C51 microcontroller to control the core of the control system in combination with tracking sensor module, infrared sensor module, relay module, and the motor module to simulate real restaurant environment.It’s able to remote input table number and start, 90 ° and 180 ° turning, stopping and table position determination, obstacle avoidance, plate positioning robot automatically backtrack to send food and other functions. It’s performance reliable and available to practical application in restaurant.
Key words:Sensor; Traction; Manipulator; Table positioning
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目 錄
內(nèi)容摘要...............................................................
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Abstract.................................................................
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1 導(dǎo)言.................................................................
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1.1 智能機器人傳菜員研究的背景及意義....................................
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1.2 智能機器人傳菜員國內(nèi)外研究狀況......................................
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1.3 本課題設(shè)計的智能機器人傳菜員........................................
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2 總體方案設(shè)計.........................................................
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2.1 機器人總體結(jié)構(gòu)設(shè)計..................................................
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2.2 機器人實驗環(huán)境布局..................................................
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2.3 機器人總體電路設(shè)計..................................................
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3 控制系統(tǒng)的實現(xiàn).......................................................
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3.1 傳感器的布局........................................................
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3.2 機器人控制系統(tǒng)......................................................
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3.3 具體實施方案.......................................................
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3.4 步進電機偏轉(zhuǎn)程序設(shè)計................................................
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3.5 路徑信息采集程序設(shè)計................................................
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3.6行進中避障程序設(shè)計...................................................
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3.7 紅外控制啟動程序設(shè)計.................................................
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4 機械手液壓系統(tǒng)設(shè)計...................................................
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4.1 液壓系統(tǒng)設(shè)計........................................................
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4.2 液壓元件的計算與選擇................................................
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4.3 機械手爪的設(shè)計及安裝................................................
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參考文獻...............................................................
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附錄:開題報告...........................................................
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程序..............................................................
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致謝...................................................................
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英文原文
Influence factors on the quality of the workplace surface
Processing process on the surface quality of the influence
The vibration of the process system of the influence on the quality of the surface
In mechanical processing process technology system sometimes occur vibration, that is, in the cutting edge tool and workplace is cutting surface except on the name between cutting motion, but also can appear a cyclical relative motion.
Vibration that process system by forming movement of the interference and damage, make processing surface appear chatter marks, increases the surface roughness value, worsening processing surface quality.
Cutter geometrical parameters, materials and cutting quality to the surface quality of the influence
The cutting tool geometric parameters on the surface roughness of the biggest influence is vice PianJiao, the main point PianJiao, arc radius. Under certain conditions, reduce PianJiao, Lord, vice PianJiao point arc radius can reduce surface roughness. Under the same conditions, carbide cutting tools process of surface roughness value less than high speed steel paper cutting knife, and diamond and CBN) tools and better than hard alloy, but because the diamond and iron family affinity materials, it should not be used for processing iron family materials. In addition, the cutting tool before and after the face, cutting knife blade itself directly influence the roughness of the processing the roughness of the surface, therefore, improve the quality of cutting tool, cutting tool and face, cutting knife blade roughness value should be lower than the roughness of the 1 ~ 2 levels.
Cutting fluid to the influence on the quality of the surface
Cutting fluid cooling and lubrication effect can reduce the cutting process of interface friction, reduce the temperature of cutting zone, the cutting metal surface layer of plastic deformation degree down, restrain the develop the thorn and scales produced in the production of different materials for reasonable choice of cutting fluids can reduce the surface roughness.
The workplace material on the surface quality of the influence
The workplace material nature; Processing plastic materials, the cutting tools for metal extrusion produced plastic deformation, and the cutting tool and workplace forced separation of the torn scraps effect, make the surface roughness value increase. The workplace material tenacity the better, metal, plastic deformation, the bigger the processing surface is the more the rough. Processing brittle material in the chip broken granular, due to the collapse in broken and endows the machined surface left many pitted surface roughness.
General toughness large plastic materials, processing after large surface roughness, and toughness of smaller plastic materials, processing to get smaller after the surface roughness. For the same kind of material, the greater the grain size of the organization, the larger the surface roughness. Therefore, in order to reduce the surface roughness, often in cutting processing of material before quenching and tempering or is the fire of treatment to obtain homogeneous fine grain organization and high hardness.
Cutting condition the influence on the quality of the surface
And cutting condition of the relevant process factors, including cutting dosages, cooling lubrication. In low speed processing plastic materials,, easy to produce the develop and scales thorn, so, improve the cutting speed, can reduce the develop and scales thorn, decreasing part already the surface roughness value; For brittle material, general won't form the develop and scales thorn, so, cutting speed on the surface roughness basically no influence. The increase speed, plastic deformation also increases, the surface roughness increases, so, reduce the speed can reduce the surface roughness value, however, feeding reduced to certain value, roughness won't obviously decreased. Normal cutting conditions, cutting depth on the surface roughness the impact is not big, therefore, mechanical process cannot select the too small cutting depth.
Cutting speed on the surface roughness influence
General at the early choose low speed cutting and finishing choose high speed cutting can reduce the surface roughness. In the medium speed cutting plastic materials, due to easy to produce the develop, and plastic deformation is bigger, so after processing parts surface roughness is bigger. Usually by low or high speed cutting plastic material, can effectively avoid the develop of generation, this to reduce table and roughness have positive role.
On the surface quality of the grinding effects
The influence of the grinding wheel grinding wheel granularity the thinner, per unit area grain number grinding, the more of the grinding surface in fine scratches the surface roughness is small; But if too fine granularity, processing to jam wheel it will increase the surface roughness, also easy to produce the ripple and cause burns. The hardness of the grinding wheel should be the right size, its half the longer the better passivation period; The hardness of the grinding wheel is too high, grinding mill is not easy to fall off when grain, make processing surface is of friction, extrusion action intensifies, thus increasing the plastic deformation, making the surface roughness increases, also easy cause burns; But the grinding wheel is too soft, grits too easy to fall off, can make grinding action is reduced, leading to the surface roughness increases, so to select the right grinding wheel hardness. Grinding wheel dressing the higher the quality, the surface of the grinding wheel cutting the blade, cutting the number of all the more the better of the blade contour sex, grinding surface roughness and smaller.
The influence of the grinding wheel speed increase dosage, unit time through the processing of grinding surface grain number increase, each star grits is ground to reduce thickness of the metal, the surface area of the residual reduced; And at the same time, improve the grinding wheel speed can also reduce the workplace material of plastic deformation, these can make processing surface roughness value reduced. Reduce the speed, unit time through the processing of grinding surface grain number increase, the surface roughness decreased; But the low speed, workplace and grinding wheel contact time long, to the quantity of heat of the increasing, opposite will increase the roughness, may also increase surface burn. Increase grinding depth and longitudinal feeding, the plastic deformation increase, will lead to the surface roughness value increase. Radial feeding increase, the grinding process grinding force and grinding temperature will increase, grinding surface plastic deformation degree increase, which will increase the surface roughness. To guarantee the machining quality in the premise of grinding efficiency increase, will require a higher surface the coarse grinding and fine grinding separately, coarse grinding is used when the big radial direction feeding, fine grinding the radial feeding the smaller when, finally without into to grinding, to get the surface roughness of surface is very small.
The workplace material the workplace material of hardness, plastic and thermal conductivity on the surface roughness of big effect. Large plastic soft material easy jam grinding wheel, thermal conductivity poor heat resistant alloy easy for the abrasive early caving, will lead to increased grinding surface roughness.
In addition, because grinding to the high temperature, reasonable use cutting fluids can reduce the grinding of temperature, reduce burns, can also rushed to fall off the grits and scraps, avoid scratch workplace, so as to reduce the surface roughness.
Affect the surface of physical and mechanical properties of factors
Surface layer cold hardening. The cutting edges obtuse radius increased, and the surface of metal the extrusion of enhanced, plastic deformation intensifies, cold hard to strengthen. After cutting tool knife surface wear increases, the knife surface and after processed surface friction intensified, plastic deformation increase, cold hard to strengthen. Cutting speed increase, cutting tool and workplace role time is shortened, make plastic deformation expand the depth decreases, and cold hard layer depth decreases. After cutting speed increase, heat cutting in the surface layer effect time also shortened, will make cold hard degree increase. Feeding increases, cutting force also increased, and the surface of the metal plastic deformation intensifies, cold hard effect is strengthening. The workplace material of plastic is larger and the cold hard phenomenon the serious.
Surface layer material metallographic composition change. When cutting the heat was processing surface temperature of phase change after more than temperature, the surface of the metal microstructure will change. Grinding burns when a surface temperature of phase change to millers temperature above, metal surface microstructure occurred change, make the surface of the metal strength and hardness of the lower, and with residual stress produce appear even microscopic cracks, this phenomenon is called grinding burns. Improve grinding burns grinding heat caused by grinding way is the root of the burn, so improving grinding burns by two ways: one is as far as possible to reduce the generation of grinding heat; 2 it is improved cooling condition, make as far as possible the quantity of heat to produce less workplace. The correct choice grinding wheel reasonable choice of cutting dosages improved cooling conditions.
Surface layer residual stress. Produce residual stress of reason: cutting in processing the metal layer and the surface when there were plastic deformation occurs, the surface of the metal to hematocrit increase; Cutting processing, cutting area will have a lot of heat cutting produce; Different analysis of metallographic organization has different density, also have different olume is necessarily affected by the change of connected the matrix of the metal bar, hence residual stress produce. The main work surface eventually process to the choice of methods. Choose the main parts work surface eventually process method, we must consider the main parts of the specific work surface working conditions and the possible damage to the form. In alternating load, the machine parts on the surface of the local micro cracks, because of tensile stress of action to make primary crack expanding, resulting in parts fracture. Improve parts from the view point of fatigue damage resistance, the final process should choose the surface in the surface produces residual stress processing method. In the machining process, tools on the squash and friction make metal materials happen plastic deformation, cause the original residue area of distortion or groove lines deepened, increases the surface roughness. When the medium or medium low cutting speed cutting plastic material, the surface before the sword in easy to form a high hardness of the devolop, it can take the place of the cutting tool, but state very unstable, the develop generation, grow up and fall off will seriously affect the machined surface roughness value. In addition, in cutting process due to the strong scraps and former knife friction role and tear phenomenon, but also in processing on the surface may produce scale thorn, make processing surface roughness increases.
Grinding surface layer analysis of metallographic organization changes and grinding burns
Mechanical processing produces in the process of heat cutting processing surface of workplace will make the rise of temperature of the violently, when the temperature more than the workplace material metallographic organization changes of the critical temperature, metallographic organization change will occur. In grinding processing, because most grits before cutting Angle is negative, grinding temperature is high, the quantity of heat of generation is much higher than cutting calories at, and grinding heat have 60 to 80% to the workplace, so very prone to the change of metallographic organization, makes the metal surface hardness and strength of decline, produce residual stress and even cause microcracks, this phenomenon is called grinding burns. Produce grinding burns, processing surface often appear yellow, brown, purple, green and burn color, this is grinding surface oxidation of high temperature in instantaneous film under color. Different burns color, shows that the surface of different levels by burns.
Grinding hardened steel, workplace surface layer due to the role of the instantaneous heat, it may produce the following three metallographic organization changes:
If grinding surface layer temperature not over phase transition temperature, but more than martensite transition temperature, then martensite will change to become low hardness of tempering methods, and meanwhile body or body, this call tempering burns.
If grinding surface layer temperature more than phase transition temperatures, the martensite transformation for austenitic, at this time without cutting fluids, the grinding surface hardness fell sharply, surface was annealing, this phenomenon is called annealing burns. When dry grinding is easy to produce this kind of phenomenon.
If grinding surface layer temperature more than phase transition temperature, but have the full cutting fluid on the cooling, the grinding surface layer will be urgent cold forming secondary hardened martensitic, hardness than tempering martensite high, but the surface layer is very thin, and only a few microns thick, under which the low hardness for tempering saxhlet body and saxhlet body, make the surface layer general hardness still reduce, called quenching burns.
Grinding burns improvement measure
Influence factors of grinding burns is grinding dosage, grinding wheel, the workpiece material and cooling conditions. Because grinding heat caused by grinding burns is the root cause of, because this wants to avoid grinding burns, should as far as possible to reduce the heat generated when grinding and decrease as far as possible to the quantity of heat of workplace. Specific can adopt the following measures:
Choosing grinding reasonable dosage cannot use the too big grinding depth, because when grinding depth increases, the plastic deformation is increased, the surface layer and the temperature will increase, burns will also increase; The speed increase, a surface temperature will increase grinding zone, but due to the hot action time reduced, so can reduce the burn.
The workplace material the workplace material grinding zone of the influence of the temperature of depends primarily on its hardness and strength, toughness and thermal conductivity. The workplace material hardness, the higher the strength, toughness, the bigger the grinding work when the more consumption, the quantity of heat that produced the more, the easy generation burns; Thermal conductivity of poor material, also easy to appear in the grinding burns.
The choice of high hardness of the grinding wheel grinding wheel, passivated grits is not easy to fall off, easy to produce burns, so with soft grinding wheel is better; Choose coarse granularity grinding wheel grinding, not easily by grinding wheel grinding jams, can reduce burned; Combine agent of grinding burns also has a great influence, resin combination agent than ceramic combination agent easy to produce burns, rubber binder than resin binder are more likely to have burned.
Cooling conditions for reduction in grinding of temperature, widely used in this cutting liquid cooling. In order to make cutting fluids can injection to the surface, usually the cutting fluid flow increase.
中文譯文
影響工件表面質(zhì)量的因素
加工過程對表面質(zhì)量的影響
工藝系統(tǒng)的振動對工件表面質(zhì)量的影響
在機械加工過程中工藝系統(tǒng)有時會發(fā)生振動,即在刀具的切削刃與工件上正在切削的表面之間除了名義上的切削運動之外,還會出現(xiàn)一種周期性的相對運動。
振動使工藝系統(tǒng)的各種成形運動受到干擾和破壞,使加工表面出現(xiàn)振紋,增大表面粗糙度值,惡化加工表面質(zhì)量。
刀具幾何參數(shù)、材料和刃磨質(zhì)量對表面質(zhì)量的影響
刀具的幾何參數(shù)中對表面粗糙度影響最大主要是副偏角、主偏角、刀尖圓弧半徑。在一定的條件下,減小副偏角、主偏角、刀尖圓弧半徑都可以降低表面粗糙度。在同樣條件下,硬質(zhì)合金刀具加工的表面粗糙度值低于高速鋼刀具,而金剛石、立方氮化硼刀具又優(yōu)于硬質(zhì)合金,但由于金剛石與鐵族材料親和力大,故不宜用來加工鐵族材料。另外,刀具的前、后刀面、切削刃本身的粗糙度直接影響加工表面的粗糙度,因此,提高刀具的刃磨質(zhì)量,使刀具前后刀面、切削刃的粗糙度值應(yīng)低于工件的粗糙度值的1~2級。?
切削液對表面質(zhì)量的影響
切削液的冷卻和潤滑作用能減小切削過程中的界面摩擦,降低切削區(qū)溫度,使切削層金屬表面的塑性變形程度下降,抑制積屑瘤和鱗刺的產(chǎn)生,在生產(chǎn)中對于不同材料合理選用切削液可大大減小工件表面粗糙度。
工件材料對表面質(zhì)量的影響
工件材料的性質(zhì);加工塑性材料時,由刀具對金屬的擠壓產(chǎn)生了塑性變形,加之刀具迫使切屑與工件分離的撕裂作用,使表面粗糙度值加大。工件材料韌性越好,金屬的塑性變形越大,加工表面就愈越粗糙。加工脆性材料時其切屑呈碎粒狀,由于切屑的崩碎而在加工表面留下許多麻點使表面粗糙。
一般韌性較大的塑性材料,加工后表面粗糙度較大,而韌性較小的塑性材料,加工后易得到較小的表面粗糙度。對于同種材料,其晶粒組織越大,加工表面粗糙度越大。因此,為了減小加工表面粗糙度,常在切削加工前對材料進行調(diào)質(zhì)或正火處理,以獲得均勻細(xì)密的晶粒組織和較高的硬度。?
切削條件對工件表面質(zhì)量的影響
與切削條件有關(guān)的工藝因素,包括切削用量、冷卻潤滑情況。中、低速加工塑性材料時,容易產(chǎn)生積屑瘤和鱗刺,所以,提高切削速度,可以減少積屑瘤和鱗刺,減小零件已加工表面粗糙度值;對于脆性材料,一般不會形成積屑瘤和鱗刺,所以,切削速度對表面粗糙度基本上無影響。進給速度增大,塑性變形也增大,表面粗糙度值增大,所以,減小進給速度可以減小表面粗糙度值,但是,進給量減小到一定值時,粗糙度值不會明顯下降。正常切削條件下,切削深度對表面粗糙度影響不大,因此,機械加工時不能選用過小的切削深度。
切削速度對表面粗糙度的影響
一般在粗加工選用低速車削,精加工選用高速車削可以減小表面粗糙度。在中速切削塑性材料時,由于容易產(chǎn)生積屑瘤,且塑性變形較大,因此加工后零件表面粗糙度較大。通常采用低速或高速切削塑性材料,可有效地避免積屑瘤的產(chǎn)生,這對減小表而粗糙度有積極作用。?
磨削加工對表面質(zhì)量的影響
砂輪的影響 砂輪的粒度越細(xì),單位面積上的磨粒數(shù)越多,在磨削表面的刻痕越細(xì),表面粗糙度越??;但若粒度太細(xì),加工時砂輪易被堵塞反而會使表面粗糙度增大,還容易產(chǎn)生波紋和引起燒傷。砂輪的硬度應(yīng)大小合適,其半鈍化期愈長愈好;砂輪的硬度太高,磨削時磨粒不易脫落,使加工表面受到的摩擦、擠壓作用加劇,從而增加了塑性變形,使得表面粗糙度增大,還易引起燒傷;但砂輪太軟,磨粒太易脫落,會使磨削作用減弱,導(dǎo)致表面粗糙度增加,所以要選擇合適的砂輪硬度。砂輪的修整質(zhì)量越高,砂輪表面的切削微刃數(shù)越多、各切削微刃的等高性越好,磨削表面的粗糙度越小。
磨削用量的影響 增大砂輪速度,單位時間內(nèi)通過加工表面的磨粒數(shù)增多,每顆磨粒磨去的金屬厚度減少,工件表面的殘留面積減少;同時提高砂輪速度還能減少工件材料的塑性變形,這些都可使加工表面的表面粗糙度值降低。降低工件速度,單位時間內(nèi)通過加工表面的磨粒數(shù)增多,表面粗糙度值減??;但工件速度太低,工件與砂輪的接觸時間長,傳到工件上的熱量增多,反面會增大粗糙度,還可能增加表面燒傷。增大磨削深度和縱向進給量,工件的塑性變形增大,會導(dǎo)致表面粗糙度值增大。徑向進給量增加,磨削過程中磨削力和磨削溫度都會增加,磨削表面塑性變形程度增大,從而會增大表面粗糙度值。為在保證加工質(zhì)量的前提下提高磨削效率,可將要求較高的表面的粗磨和精磨分開進行,粗磨時采用較大的徑向進給量,精磨時采用較小的徑向進給量,最后進行無進給磨削,以獲得表面粗糙度值很小的表面。
工件材料 工件材料的硬度、塑性、導(dǎo)熱性等對表面粗糙度的影響較大。塑性大的軟材料容易堵塞砂輪,導(dǎo)熱性差的耐熱合金容易使磨料早期崩落,都會導(dǎo)致磨削表面粗糙度增大。
另外,由于磨削溫度高,合理使用切削液既可以降低磨削區(qū)的溫度,減少燒傷,還可以沖去脫落的磨粒和切屑,避免劃傷工件,從而降低表面粗糙度值。
影響工件表面物理機械性能的因素
表面層冷作硬化。切削刃鈍圓半徑增大,對表層金屬的擠壓作用增強,塑性變形加劇,導(dǎo)致冷硬增強。刀具后刀面磨損增大,后刀面與被加工表面的摩擦加劇,塑性變形增大,導(dǎo)致冷硬增強。切削速度增大,刀具與工件的作用時間縮短,使塑性變形擴展深度減小,冷硬層深度減小。切削速度增大后,切削熱在工件表面層上的作用時間也縮短了,將使冷硬程度增加。進給量增大,切削力也增大,表層金屬的塑性變形加劇,冷硬作用加強。工件材料的塑性愈大,冷硬現(xiàn)象就愈嚴(yán)重。
表面層材料金相組織變化。當(dāng)切削熱使被加工表面的溫度超過相變溫度后,表層金屬的金相組織將會發(fā)生變化。磨削燒傷當(dāng)被磨工件表面層溫度達到相變溫度以上時,表層金屬發(fā)生金相組織的變化,使表層金屬強度和硬度降低,并伴有殘余應(yīng)力產(chǎn)生甚至出現(xiàn)微觀裂紋,這種現(xiàn)象稱為磨削燒傷。改善磨削燒傷的途徑磨削熱是造成磨削燒傷的根源,故改善磨削燒傷由兩個途徑:一是盡可能地減少磨削熱的產(chǎn)生;二是改善冷卻條件,盡量使產(chǎn)生的熱量少傳入工件。正確選擇砂輪合理選擇切削用量改善冷卻條件。
表面層殘余應(yīng)力。產(chǎn)生殘余應(yīng)力的原因:切削時在加工表面金屬層內(nèi)有塑性變形發(fā)生,使表面金屬的比容加大;切削加工中,切削區(qū)會有大量的切削熱產(chǎn)生;不同金相組織具有不同的密度,亦具有不同的比容的變化必然要受到與相連的基體金屬的阻礙,因而就有殘余應(yīng)力產(chǎn)生。工件主要工作表面最終工序加工方法的選擇。選擇零件主要工作表面最終工序加工方法,須考慮該零件主要工作表面的具體工作條件和可能的損壞形式。在交變載荷作用下,機器零件表面上的局部微觀裂紋,會因拉應(yīng)力的作用使原生裂紋擴大,最后導(dǎo)致零件斷裂。從提高零件抵抗疲勞破壞的角度考慮,該表面最終工序應(yīng)選擇能在該表面產(chǎn)生殘余壓應(yīng)力的加工方法。在切削加工過程中,刀具對工件的擠壓和摩擦使金屬材料發(fā)生塑性變形,引起原有的殘留面積扭曲或溝紋加深,增大表面粗糙度。當(dāng)采用中等或中等偏低的切削速度切削塑性材料時,在前刀面上容易形成硬度很高的積屑瘤,它可以代替刀具進行切削,但狀態(tài)極不穩(wěn)定,積屑瘤生成、長大和脫落將嚴(yán)重影響加工表面的表面粗糙度值。另外,在切削過程中由于切屑和前刀面的強烈摩擦作用以及撕裂現(xiàn)象,還可能在加工表面上產(chǎn)生鱗刺,使加工表面的粗糙度增加。
磨削表面層金相組織變化與磨削燒傷
機械加工過程中產(chǎn)生的切削熱會使得工件的加工表面產(chǎn)生劇烈的溫升,當(dāng)溫度超過工件材料金相組織變化的臨界溫度時,將發(fā)生金相組織轉(zhuǎn)變。在磨削加工中,由于多數(shù)磨粒為負(fù)前角切削,磨削溫度很高,產(chǎn)生的熱量遠(yuǎn)遠(yuǎn)高于切削時的熱量,而且磨削熱有60~80%傳給工件,所以極容易出現(xiàn)金相組織的轉(zhuǎn)變,使得表面層金屬的硬度和強度下降,產(chǎn)生殘余應(yīng)力甚至引起顯微裂紋,這種現(xiàn)象稱為磨削燒傷。產(chǎn)生磨削燒傷時,加工表面常會出現(xiàn)黃、褐、紫、青等燒傷色,這是磨削表面在瞬時高溫下的氧化下膜顏色。不同的燒傷色,表明工件表面受到的燒傷程度不同。
磨削淬火鋼時,工件表面層由于受到瞬時高溫的作用,將可能產(chǎn)生以下三種金相組織變化:
如果磨削表面層溫度未超過相變溫度,但超過了馬氏體的轉(zhuǎn)變溫度,這時馬氏體將轉(zhuǎn)變成為硬度較低的回火索氏體或索氏體,這叫回火燒傷。
如果磨削表面層溫度超過相變溫度,則馬氏體轉(zhuǎn)變?yōu)閵W氏體,這時若無切削液,則磨削表面硬度急劇下降,表層被退火,這種現(xiàn)象稱為退火燒傷。干磨時很容易產(chǎn)生這種現(xiàn)象。
如果磨削表面層溫度超過相變溫度,但有充分的切削液對其進行冷卻,則磨削表面層將急冷形成二次淬火馬氏體,硬度比回火馬氏體高,不過該表面層很薄,只有幾微米厚,其下為硬度較低的回火索氏體和索氏體,使表面層總的硬度仍然降低,稱為淬火燒傷。
磨削燒傷的改善措施
影響磨削燒傷的因素主要是磨削用量、砂輪、工件材料和冷卻條件。由于磨削熱是造成磨削燒傷的根本原因,因此要避免磨削燒傷,就應(yīng)盡可能減少磨削時產(chǎn)生的熱量及盡量減少傳入工件的熱量。具體可采用下列措施:
合理選擇磨削用量 不能采用太大的磨削深度,因為當(dāng)磨削深度增加時,工件的塑性變形會隨之增加,工件表面及里層的溫度都將升高,燒傷亦會增加;工件速度增加,磨削區(qū)表面溫度會增高,但由于熱作用時間減少,因而可減輕燒傷。
工件材料 工件材料對磨削區(qū)溫度的影響主要取決于它的硬度、強度、韌性和熱導(dǎo)率。工件材料硬度、強度越高,韌性越大,磨削時耗功越多,產(chǎn)生的熱量越多,越易產(chǎn)生燒傷;導(dǎo)熱性較差的材料,在磨削時也容易出現(xiàn)燒傷。
砂輪的選擇 硬度太高的砂輪,鈍化后的磨粒不易脫落,容易產(chǎn)生燒傷,因此用軟砂輪較好;選用粗粒度砂輪磨削,砂輪不易被磨削堵塞,可減少燒傷;結(jié)合劑對磨削燒傷也有很大影響,樹脂結(jié)合劑比陶瓷結(jié)合劑容易產(chǎn)生燒傷,橡膠結(jié)合劑比樹脂結(jié)合劑更易產(chǎn)生燒傷。
冷卻條件為降低磨削區(qū)的溫度,在磨削時廣泛采用切削液冷卻。為了使切削液能噴注到工件表面上,通常增加切削液的流量和壓力并采用特殊噴嘴,并在砂輪上安裝帶有空氣擋板的切削液噴嘴,這樣既可加強冷卻作用,又能減輕高速旋轉(zhuǎn)砂輪表面的高壓附著作用,使切削液順利地噴注到磨削區(qū)。此外,還可采用多孔砂
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