沖壓木塊機(jī)的設(shè)計(jì)【說明書+CAD】
沖壓木塊機(jī)的設(shè)計(jì)【說明書+CAD】,說明書+CAD,沖壓木塊機(jī)的設(shè)計(jì)【說明書+CAD】,沖壓,木塊,設(shè)計(jì),說明書,CAD
目 錄
摘要 I
Abstract II
第1章 緒論 1
1.1 沖壓木塊機(jī)概述 1
1.1.1 沖壓木塊機(jī)發(fā)展現(xiàn)狀 1
1.2 沖壓木塊機(jī)的主要特點(diǎn) 4
1.3 沖壓木塊機(jī)設(shè)計(jì)的目的和意義 4
第2章 系統(tǒng)設(shè)計(jì)總體方案 7
2.1 沖壓木塊機(jī)的結(jié)構(gòu)設(shè)計(jì) 7
2.2 刀具體的確定 9
2.3 撥料裝置 12
2.4 機(jī)架結(jié)構(gòu) 14
第3章 機(jī)械系統(tǒng)設(shè)計(jì)方案的確定 16
3.1 設(shè)計(jì)參數(shù)設(shè)定 16
3.2 運(yùn)動(dòng)系統(tǒng)的設(shè)計(jì)計(jì)算 16
3.2.1 電動(dòng)機(jī)的選擇計(jì)算 16
3.2.2 減速機(jī)的確定 17
3.2.3 鏈傳動(dòng)的特點(diǎn)與應(yīng)用 18
3.2.4 鏈傳動(dòng)的設(shè)計(jì)計(jì)算 19
3.2.5 軸的設(shè)計(jì)說明 22
3.2.6 主軸的的結(jié)構(gòu)設(shè)計(jì) 23
3.2.6 軸的強(qiáng)度校核計(jì)算 27
3.2.7 校核軸承壽命 28
第4章 沖壓木塊機(jī)的使用說明書—MJB205 30
4.1 主要用途及適用范圍 30
4.2 主要規(guī)格及技術(shù)參數(shù) 31
4.3 主要結(jié)構(gòu)及性能 31
4.4 安裝與調(diào)整 32
4.5 使用與操作 33
4.6 維護(hù)與保養(yǎng) 33
結(jié) 論 34
致 謝 35
參考文獻(xiàn) 36
CONTENTS
Abstract II
Chapter 1 Introduction 1
1.1 Overview of stamping pieces of wood machine 1
1.1.1 Stamping pieces of wood machine development status 1
1.2 The main features of the machine of stamping pieces of wood 4
1.3 The purpose and significance of the design of stamping pieces of wood machine 4
Chapter 2 System design of the overall program 7
2.1 The structural design of stamping pieces of wood 7
2.2 The knife concrete to determine 9
2.3 Dial feeding device 12
2.4 Frame structure 14
Chapter 3 The determination of the mechanical system design 16
3.1 Design parameter settings 16
3.2 Design calculations of the movement system 16
3.2.1 Motor selection and calculation 16
3.2.2 The determination of the speed reducer 17
3.2.3 Characteristics and applications of the chain drive 18
3.2.4 The design of the chain drive 19
3.2.5 Axis of the design description 22
3.2.6 Spindle structural design 23
3.2.6 The axis of the strength check calculation 27
3.2.7 Check bearing life 28
Chapter 4 The manual of stamping pieces of wood—MJB205 30
4.1 The main purpose and scope of 30
4.2 Main specifications and technical parameters 31
4.3 The main structure and performance 31
4.4 Installation and adjustment 32
4.5 Use and operation of 33
4.6 Care and Maintenance 33
Conclusions 34
Thanks 35
References 36
V
確定材料抵抗加工變形的機(jī)械性能
摘要：這篇論文分析了材料在加工過程中的抵抗塑性變形的實(shí)驗(yàn)性的結(jié)果和一些假設(shè)。必須要考慮到應(yīng)變速度以及溫度對(duì)材料的機(jī)械特性的影響。可以用不同的等式來描述材料抵抗塑性變形的規(guī)律，這些等式能夠表達(dá)其中應(yīng)變功。在加工進(jìn)程中，根據(jù)具體變形功的差異，可以分析推斷出屈服點(diǎn)和變形之間的關(guān)系式或者流動(dòng)曲線。我們可以發(fā)現(xiàn)，在切削形成區(qū)域以及切削邊緣處的堆積區(qū)在絕熱條件下，流動(dòng)曲線是呈拱形的。其中屈服點(diǎn)在變形中達(dá)到了它的最大值，這個(gè)值要比滲透到切屑形成區(qū)的材料實(shí)際最終切變力的值更低一些。通常將這些屈服點(diǎn)的最大值作為材料加工的機(jī)械特性。本論文敘述了一些理論性和實(shí)驗(yàn)性的調(diào)查研究，主要目的是為了確定應(yīng)變和屈服點(diǎn)以及正應(yīng)力間的相互關(guān)系（考慮到在屈服點(diǎn)處的溫度影響）。采用應(yīng)力功分析的好處不僅是因?yàn)樗妥冃螠囟戎苯酉嚓P(guān)，更是因?yàn)樗梢酝ㄟ^正應(yīng)力和實(shí)際最終切變力科學(xué)地確定這種變形功。采用這種方法，并運(yùn)用實(shí)證物理常數(shù)可以確定變形溫度如何影響屈服點(diǎn)。
關(guān)鍵詞: 機(jī)床 切斷 機(jī)械性能 流動(dòng)曲線
1 簡(jiǎn)介
機(jī)械材料在斷裂時(shí)的抗變形特性通常可以通過張力和壓力的機(jī)械檢測(cè)方法以及對(duì)檢測(cè)后塑性變形必要量的推斷來確定。然而，此時(shí)材料變形以及加工中的應(yīng)力變形功高一個(gè)數(shù)量級(jí)，應(yīng)變率和標(biāo)準(zhǔn)的張壓力檢測(cè)得到的數(shù)值相比要高八個(gè)數(shù)量級(jí)。此外，較大的塑性變形以及主要建切變區(qū)域處變形的不均勻分布會(huì)導(dǎo)致不均勻的溫度分布。反過來，這樣也會(huì)導(dǎo)致機(jī)械材料具有不均勻的抵抗塑性變形的阻力。必須要考慮到對(duì)于材料的變形條件在切屑形成區(qū)或第一和第二切變區(qū)以及在切屑和裂痕間的塑性接觸區(qū)的差異。同樣，還要考慮到材料抵抗塑性變形的阻力在切變區(qū)和堆積區(qū)中的差異是非常大的。
在機(jī)械加工中，變形，應(yīng)變率，和溫度都是相互關(guān)聯(lián)的。在通過標(biāo)準(zhǔn)測(cè)試來測(cè)定材料的機(jī)械性能時(shí)，操作者確立這些有交集的因素時(shí)并沒有使它們相互關(guān)聯(lián)。這樣在確定機(jī)械加工材料性能時(shí)則會(huì)產(chǎn)生實(shí)質(zhì)性的錯(cuò)誤。上述提到的因素是如何影響加工變形時(shí)的屈服點(diǎn)的相關(guān)參數(shù)通常不被人們充分考慮到。但是這種考慮是必須的，因?yàn)楹蜆?biāo)準(zhǔn)試驗(yàn)相比，機(jī)械加工時(shí)材料變形的條件是不同的。如今，只能通過檢驗(yàn)屈服點(diǎn)平均數(shù)值來分析機(jī)械材料在斷裂時(shí)抵抗塑性變形的阻力規(guī)律，并根據(jù)平均值擴(kuò)展到更大的形變變化范圍，這個(gè)范圍包括加工材料的硬化區(qū)域和軟化區(qū)域。許多研究唯獨(dú)都被切屑形成區(qū)和主要切變區(qū)的正應(yīng)力的實(shí)驗(yàn)測(cè)定所限制。這也就是說，我們可能無法充分地得出變形時(shí)屈服點(diǎn)的相關(guān)參數(shù)或加工過程的流動(dòng)曲線，也不能估算屈服點(diǎn)的最大值。
在不同的加工條件下，切屑形成區(qū)中部分區(qū)域都會(huì)出現(xiàn)變形。部分變形迅速出現(xiàn)于切屑形成區(qū)邊緣的狹窄部位。這塊狹窄區(qū)域中的發(fā)生形變的地方對(duì)加工材料的軟化有很大的影響。在確定流動(dòng)曲線時(shí)，這個(gè)影響必須考慮在內(nèi)。
因?yàn)榍凶儏^(qū)域形變的不均勻，所以我們不可能通過在切削加工條件下進(jìn)行的實(shí)驗(yàn)來確定流動(dòng)曲線。此外，加工材料的屈服點(diǎn)不僅和變形的大小有關(guān)，還與溫度的變化有關(guān)。溫度的變化還涉及到形變和屈服點(diǎn)的變化。上述提到的參數(shù)都是相互關(guān)聯(lián)的，不可以通過實(shí)驗(yàn)來得到。所以在確定流動(dòng)曲線時(shí)，實(shí)驗(yàn)和理論的分析檢驗(yàn)必須同時(shí)兼顧到。
本論文敘述了一些理論性和實(shí)驗(yàn)性的調(diào)查研究，主要目的是為了確定應(yīng)變和屈服點(diǎn)以及正應(yīng)力間的相互關(guān)系（考慮到在屈服點(diǎn)處的溫度影響）。
2.關(guān)于在加工中抵抗材料變形的假設(shè)的分析
2.1 應(yīng)變，應(yīng)變率，以及屈服點(diǎn)溫度的影響
許多研究者都認(rèn)為，材料的不同斷裂方式，例如在拉伸，成型及材料去除時(shí)，材料抵抗塑性變形的規(guī)律都是統(tǒng)一的。大量的拉伸試驗(yàn)的研究則顯示了應(yīng)力強(qiáng)度取決于應(yīng)變，應(yīng)變率，以及同系溫度的增加。
下面這個(gè)等式表示切變屈服點(diǎn)，應(yīng)變率，以及相應(yīng)溫度增量間的關(guān)系。
上述條件方程不能直接運(yùn)用于機(jī)械加工的材料模型中，因?yàn)樵谇袛鄷r(shí)溫度的增加量并不是獨(dú)立變化的，而是與變形和切變應(yīng)力有關(guān)。因此，加工中滿足變形條件的方程式要從含有實(shí)證常數(shù)的流動(dòng)曲線中得到。這些常數(shù)有應(yīng)變，應(yīng)變率，和溫度。
2.2斷裂產(chǎn)生的載荷的簡(jiǎn)單形式應(yīng)用假設(shè)
將車削異種鋼時(shí)正切面上的正應(yīng)力的C參數(shù)和切斷變形時(shí)張力的切變屈服點(diǎn)參數(shù)相比較。其中的正應(yīng)力被解釋為切屑形成區(qū)域的屈服點(diǎn)的最大值。然而，實(shí)驗(yàn)所獲得的正應(yīng)力應(yīng)該更準(zhǔn)確地翻譯為和最終切變有關(guān)的應(yīng)變系數(shù)或屈服點(diǎn)的平均值。這個(gè)解釋來源于楔斜面力RS和RV在切斷平面A的投影力F在切屑形成區(qū)所產(chǎn)生的應(yīng)力的定義，以及切屑變形區(qū)處根據(jù)切力和應(yīng)變力所具有的變形能力的定義。
下面的這個(gè)關(guān)系可以由上述以及圖一推導(dǎo)出來。
V2是工件在切斷平面A方向上的切屑斷裂速度，w時(shí)實(shí)際最終切變，K是切屑?jí)毫严禂?shù)。
2.3正應(yīng)力在切屑變形區(qū)的穩(wěn)定性假設(shè)以及其在材料拉伸實(shí)驗(yàn)的中與材料強(qiáng)度的關(guān)聯(lián)
我們可以發(fā)現(xiàn)機(jī)械加工產(chǎn)生的正應(yīng)力和拉伸時(shí)的斷裂屈服點(diǎn)相近。這里的屈服點(diǎn)是根據(jù)式子（3），應(yīng)用在實(shí)際加工中的斷裂變形尺寸所推導(dǎo)出來的。因此，我們建議用經(jīng)驗(yàn)關(guān)系式來估算加工時(shí)在剪切面的正應(yīng)力。
其中A是經(jīng)驗(yàn)系數(shù)，A2.5是拉伸實(shí)驗(yàn)中剪切屈服點(diǎn)。由一個(gè)推導(dǎo)公式推出。
其中幾個(gè)經(jīng)檢驗(yàn)的鋼，它們大部分的正應(yīng)力不隨變形的增加而增加，并沒有遵守如（6）中“單一載荷”的規(guī)律。其正應(yīng)力始終不變甚至減少。
除了關(guān)系式（7），應(yīng)力和強(qiáng)度的其他關(guān)系特征在拉伸實(shí)驗(yàn)中也被提及到。在這些關(guān)系特征中，下列經(jīng)驗(yàn)關(guān)系是從切屑形成區(qū)和傾斜面中所確定的正應(yīng)力中獲得的，此正應(yīng)力是在用帶有短的前面切削的工具切削不同的鋼時(shí)所產(chǎn)生的[1，16]：
圖二表示出了由經(jīng)驗(yàn)所獲得的關(guān)系式。其中常數(shù)和遞減的相關(guān)度顯示抗拉實(shí)驗(yàn)中的流動(dòng)曲線和機(jī)械加工時(shí)的曲線并不一致。這符合實(shí)驗(yàn)性機(jī)械加工的實(shí)驗(yàn)性研究，也滿足鋁在剪切變形時(shí)0.6-1.5范圍內(nèi)的壓力變化值。機(jī)械加工時(shí)剪切區(qū)的正應(yīng)力要比抗拉強(qiáng)度大得多。
在機(jī)械加工時(shí)，應(yīng)力在剪切區(qū)的應(yīng)變率會(huì)導(dǎo)致壓力的流動(dòng)曲線和較小范圍內(nèi)變形的加工不一致。溫度對(duì)屈服點(diǎn)的影響和溫度切削加工的正應(yīng)力的影響也以不同的方式被驗(yàn)證。一方否認(rèn)溫度影響切屑形成區(qū)和楔斜面的正應(yīng)力。
這是因?yàn)橐话阋?guī)定切屑形成區(qū)的溫度不能超過400度。另外，我們可以假定，由于高溫時(shí)應(yīng)變率對(duì)屈服點(diǎn)的影響，屈服點(diǎn)的減少可以完全得到補(bǔ)償。所以可以據(jù)此認(rèn)為溫度對(duì)剪切形成區(qū)及楔斜面上的正應(yīng)力沒有實(shí)質(zhì)上的影響。另一方則確信應(yīng)變率和溫度對(duì)加工時(shí)的屈服點(diǎn)有相當(dāng)大的影響。
下面實(shí)驗(yàn)數(shù)據(jù)的分析將要對(duì)后一種觀點(diǎn)進(jìn)行驗(yàn)證。
3.溫度和應(yīng)變率對(duì)切屑形成區(qū)的正應(yīng)力的影響
3.1應(yīng)變率的影響
根據(jù)對(duì)實(shí)驗(yàn)結(jié)果的分析，我們可以從[3]中看出在拉伸和切削中應(yīng)變率的比例對(duì)屈服點(diǎn)平均值的影響。加工不同鋼時(shí)，在剪切深度a=0.22mm和楔正交傾角處檢測(cè)正應(yīng)力值。在v=0.2m/min的極低速度進(jìn)行的實(shí)驗(yàn)性分析中可以排除溫度對(duì)正應(yīng)力的其中一個(gè)影響。另外，拉伸實(shí)驗(yàn)是以相同的應(yīng)變率同時(shí)進(jìn)行的。切削加工的應(yīng)變系數(shù)要比常規(guī)切削參數(shù)將近小二次方。然而這個(gè)系數(shù)已經(jīng)足夠大了，并且已經(jīng)達(dá)到了106。
鑒于平均屈服點(diǎn)值表示了切屑形成區(qū)正應(yīng)力的特征這樣一個(gè)觀點(diǎn)，它們可以和推導(dǎo)出來的抗拉強(qiáng)度作比較：
其中， A w,t在抗拉試驗(yàn)中無量綱的應(yīng)變力，可以推導(dǎo)出加切削時(shí)最終剪切變形量。如果考慮到應(yīng)變率而將溫度影響排除在外，正應(yīng)力在切屑形成區(qū)承受平均抗拉強(qiáng)度就可以用下面的公式近似表示：
K e是變形系數(shù)，決定了切削和拉伸實(shí)驗(yàn)中切屑形成區(qū)加工材料的加工條
的不同。
表1顯示的是將剪切平面的正應(yīng)力和屈服點(diǎn)比較的實(shí)驗(yàn)數(shù)據(jù)。
在加工檢驗(yàn)鋼時(shí)，力幾乎比抗拉強(qiáng)度平均值大1.3倍，根據(jù)切削時(shí)實(shí)際最終剪切變形量推導(dǎo)出來的（見表1）。因此，這個(gè)系數(shù)是1.3。根據(jù)這個(gè)系數(shù)，應(yīng)變率可以高達(dá)106，使其可以適應(yīng)從抗拉試驗(yàn)過渡到相對(duì)較低的對(duì)應(yīng)溫度，能夠引起屈服點(diǎn)平均值大量增加。
為了能同系溫度對(duì)變形系數(shù)的影響，應(yīng)變率相對(duì)變化如何影響加工不同材料時(shí)的屈服點(diǎn)是需要進(jìn)行分析的。這些材料可以是鉛，鋁，或鋼。分析結(jié)果在圖3。
因此，切削變形系數(shù)和其他變形，例如抗拉試驗(yàn)，不僅和應(yīng)力比率的變化有關(guān)，還和同系溫度變換有關(guān)。在現(xiàn)代機(jī)械加工中，切屑速度的差異均在一次方范圍內(nèi)。而與之相反的是，標(biāo)準(zhǔn)抗拉試驗(yàn)的或壓力實(shí)驗(yàn)的速度和切削加工的剪切速度相差八次方。變形速度的變化在一次方以內(nèi)（這個(gè)變化是不同加工過程的速度變化）可使變形系數(shù)從1.258變換到1.344。這個(gè)變形系數(shù)的影響可以被忽略。因此，在常規(guī)范圍內(nèi)的切削參數(shù)應(yīng)變系數(shù)和抗拉試驗(yàn)的應(yīng)變系數(shù)是大約是108并且可以被設(shè)置為常數(shù)。因此，K e的值必須隨著同系溫度的升高而增大，這個(gè)系數(shù)可以同系溫度的次方關(guān)系式所表示：
3.2變形溫度的影響
根據(jù)在切屑形成區(qū)和楔斜面的正應(yīng)力的實(shí)驗(yàn)數(shù)據(jù)，可以根據(jù)系數(shù)變化量推斷出存在硬化效應(yīng)的相同溫度情況下也存在著軟化效應(yīng)。例如，從圖2a中的可以推導(dǎo)出屈服點(diǎn)在實(shí)際斷點(diǎn)處成比例上升，而系數(shù)s t /S b隨實(shí)際抗拉強(qiáng)度或相應(yīng)的變形溫度的增加而減少。
C V是材料加工的體積比熱容系數(shù)。
圖四顯示在切削不同鋼溫度是如何影響平均屈服點(diǎn)的。用楔前刀面切削鋼時(shí)，在工具和切屑間的正應(yīng)力要比在切屑形成區(qū)處的正應(yīng)力低很多。在切屑形成區(qū)及塑形接觸區(qū)中正應(yīng)力平均值的比率可以根據(jù)加工材料斜面的屈服點(diǎn)值隨溫度增加而減少。這導(dǎo)致了正應(yīng)力在楔斜面分布不均勻，并涉及到溫度的增加。這就是溫度對(duì)切削加工屈服點(diǎn)的影響。
可以認(rèn)為屈服點(diǎn)在低溫切削邊緣的堆積區(qū)B處的達(dá)到了最大值。因此，前面q0和后側(cè)面堆積區(qū)的屈服點(diǎn)最大值應(yīng)該比和大很多。
考慮到如今的測(cè)量技術(shù)，為什么會(huì)有如此大的值在非常小的堆積區(qū)B處以確定的的正應(yīng)力變化量表示，這個(gè)原因是非常難甚至不可能直接通過實(shí)驗(yàn)確定的。然而，它可以由后側(cè)面的堆積區(qū)G建立的正應(yīng)力間接表示出，其中的變形條件和堆積區(qū)B處地相應(yīng)條件非常相似。切削C45鋼時(shí)發(fā)現(xiàn)在后側(cè)面堆積區(qū)G處發(fā)生這樣的變化?？梢园l(fā)現(xiàn)堆積區(qū)G處地正應(yīng)力比切屑成區(qū)的正應(yīng)力要大。
在切削C45鋼時(shí)，進(jìn)行對(duì)力和壓縮比的實(shí)驗(yàn)檢驗(yàn)，可以發(fā)現(xiàn)正應(yīng)力系數(shù)并不是常數(shù)，而是隨著斜面的算術(shù)切削溫度值或者P數(shù)減少而減少。
從實(shí)驗(yàn)結(jié)果我們可以看出，如果加工條件不同，正應(yīng)力就會(huì)有非常大的變化。由于變形，應(yīng)變率，和溫度的影響，屈服點(diǎn)會(huì)有更大的偏離，這個(gè)偏離要比它的平均值的變化大得多。由于整個(gè)流動(dòng)曲線的數(shù)學(xué)模型是十分復(fù)雜的，首先要做的是限制機(jī)械材料硬化規(guī)律檢測(cè)，為了能夠平衡變形和應(yīng)變率引起的硬化強(qiáng)度以及溫度引起的軟化強(qiáng)度。
4 切削加工材料流動(dòng)曲線的理論性的確定
應(yīng)用應(yīng)力變形功的優(yōu)點(diǎn)不僅在于它和變形溫度有直接關(guān)聯(lián)，另一個(gè)優(yōu)點(diǎn)則是可以通過正應(yīng)力和實(shí)際最終剪切確定變形功。從這方面來看，通過經(jīng)驗(yàn)常數(shù)確定變形溫度對(duì)屈服點(diǎn)的影響是可能的。
4.1確定絕熱條件下，切屑形成區(qū)的流動(dòng)曲線
等式（2）將屈服點(diǎn)定義為一個(gè)含有三個(gè)獨(dú)立變量的函數(shù)：形變比：
應(yīng)變率比：，以及同系溫度比：?？梢约俣ㄇ邢鲿r(shí)應(yīng)變率比例和抗拉試驗(yàn)應(yīng)變率比例是個(gè)常數(shù)并且接近108。變形系數(shù)可以作為關(guān)于同系溫度增量的函數(shù)，來描述這個(gè)比例。
在幾乎絕熱加工的變形條件下，同系溫度的增量可以由變形現(xiàn)行值組成，這個(gè)值是由正應(yīng)力功的現(xiàn)行值得出的，符合如下變形：
和剪切屈服點(diǎn)相比，加入正應(yīng)力功的優(yōu)點(diǎn)是應(yīng)力功可以根據(jù)試驗(yàn)獲得的正應(yīng)力，實(shí)際抗拉強(qiáng)度和實(shí)際最終剪切而確定。和功Aw,t相反，屈服點(diǎn)不能直接根據(jù)切削實(shí)驗(yàn)確定。將正應(yīng)力功作為機(jī)械材料變形條件參數(shù)加入，也可以從條件關(guān)系式中排除溫度和屈服點(diǎn)參數(shù)。
如果要考慮到（14）和（15），條件等式(2)也可以如下轉(zhuǎn)換：
正應(yīng)力功也可以如下定義：
將根據(jù)等式（18）計(jì)算出的應(yīng)力值和根據(jù)切削實(shí)驗(yàn)測(cè)量力和切屑?jí)毫驯嚷实贸鰜淼膽?yīng)力值作比較?？梢詮闹锌闯隼碚摵蛯?shí)驗(yàn)的一致。
抗拉試驗(yàn)的應(yīng)力功是根據(jù)等式（10）定義的。根據(jù)單一載荷法則而推導(dǎo)出的這些值，和普通切削變形相一致，如果考慮到應(yīng)變率和溫度影響，這個(gè)值的差異就會(huì)非常大，要遠(yuǎn)遠(yuǎn)大于和實(shí)驗(yàn)結(jié)果值的差異。合力和切屑?jí)毫崖实膶?shí)驗(yàn)數(shù)據(jù)的使用更為合理（這些數(shù)據(jù)是為了直接確定實(shí)際剪切正應(yīng)力功），比描述流動(dòng)曲線要合理得多。
根據(jù)比例（15），等式（18）可以根據(jù)確切削變形條件下的確立的流動(dòng)曲線而有所不同，并考慮到應(yīng)變率和溫度的影響。
將切削和抗拉試驗(yàn)中的流動(dòng)曲線在以相同溫度，不同應(yīng)變率的情況下作比較，可以發(fā)現(xiàn)，應(yīng)變率對(duì)屈服點(diǎn)有很大影響。
分析圖8可以看出，切削C45鋼時(shí)，當(dāng)前實(shí)際剪切中的變形和屈服點(diǎn)參數(shù)與最終剪切正應(yīng)力并沒有任何關(guān)系。其他研究者也得出了這個(gè)結(jié)論。從此看出，當(dāng)前屈服點(diǎn)和最大屈服點(diǎn)的不同僅僅只是平均值的不同。就變形而言，這個(gè)數(shù)據(jù)也顯示出流動(dòng)曲線在切削和抗拉實(shí)驗(yàn)中在很大范圍內(nèi)是不同的。因此，對(duì)不同加工材料而言，屈服點(diǎn)和最終變形的關(guān)聯(lián)可以增大，可以減小，或者保持恒定，這取決于這些材料是發(fā)生形變硬化還是溫度軟化。如果加工材料有相同的硬化和軟化強(qiáng)度，那么就可以得到屈服點(diǎn)最大值和相應(yīng)的剪切變形值。
4.2確定切屑形成區(qū)在等溫變形條件下的流動(dòng)曲線
在靠近切屑形成區(qū)邊界的狹窄區(qū)域的集中變形處，硬化條件并不是必要的。由于變形的集中，屈服點(diǎn)不能大于最高溫度對(duì)應(yīng)的剪切力實(shí)際值：
狹窄區(qū)域集中變形現(xiàn)象和加工材料軟化現(xiàn)象可能會(huì)在很大程度上影響應(yīng)力功和正應(yīng)力在實(shí)際最終剪切的切削形成區(qū)中的相互關(guān)系。如圖9呈現(xiàn)了35Cr3MoNi鋼加工的例子。
跟據(jù)計(jì)算可知，在加工35Cr3MoNi鋼時(shí)，實(shí)際抗拉強(qiáng)度剪切屈服點(diǎn)比率可以在集中剪切值為時(shí)得到最大值。如果最終剪切，那么實(shí)際抗拉強(qiáng)度的屈服點(diǎn)比率就會(huì)穩(wěn)定在0.694。而與之相反的是如果最終剪切分別等于3和4，那么這個(gè)比率就會(huì)穩(wěn)定在0.593和0.544。因此，實(shí)際最終剪切的切屑形成區(qū)正應(yīng)力參數(shù)的減小，是由于狹窄區(qū)域集中變形時(shí)穩(wěn)定的屈服點(diǎn)處變形溫度所造成的。見圖10。
因此，材料在加工中抵抗塑性變形能力以及最終剪切如何影響切屑形成區(qū)的正應(yīng)力規(guī)律中的差異之間和這些因素有關(guān)聯(lián)，例如加工材料的硬化變形趨勢(shì)，屈服點(diǎn)B處的變形溫度影響以及抗拉強(qiáng)度等。
正應(yīng)力在切屑形成區(qū)的信息并不能充分地描述材料在加工中抵抗變形的能力。實(shí)驗(yàn)結(jié)果（圖3中）表明，變形條件系數(shù)在變形區(qū)域由于不同的溫度分布而而呈現(xiàn)不同的值，即使最終剪切是常數(shù)，這個(gè)洗漱2也會(huì)隨著溫度平均值的增加而變化。
考慮到加工，能夠區(qū)別切屑形成區(qū)和堆積區(qū)B， G處的變形條件系數(shù)符號(hào)是很重要的：用于切屑形成區(qū)，而用于堆積區(qū)。因此同系溫度T=0.167的情況下，K通常約等于13，這是應(yīng)變不均勻分布的剪切區(qū)的特點(diǎn)。
4.3確定楔的斜面及側(cè)面堆積區(qū)處絕熱變形條件下的流動(dòng)曲線
若溫度在堆積區(qū)B處是平均分配（見圖1）在T’=0.33處，變形條件系數(shù)可取得極大值。此時(shí)溫度的不均勻分配也會(huì)影響變形系數(shù)。因此屈服點(diǎn)參數(shù)q（指在堆積區(qū)B和G的當(dāng)前實(shí)際剪切中）可以由根據(jù)下面的這個(gè)等式用變形條件系數(shù)確定：
屈服點(diǎn)在切屑形成區(qū)和堆積區(qū)都有相似的公式（圖11）。加工C45鋼的實(shí)際剪力為時(shí)，可得到屈服點(diǎn)最大值
由等式（9）可知在切削形成區(qū)達(dá)到的屈服點(diǎn)的最大值僅僅取決于加工材料的常數(shù)。這些常量決定了材料在抗拉試驗(yàn)中的強(qiáng)度特征，一種向硬化變形和應(yīng)變率的趨勢(shì)，還有是向溫度軟化的趨勢(shì)。因此，屈服點(diǎn)的最大值可以表述機(jī)械加工材料在切屑形成區(qū)的抵抗變形的普通特性。在堆積區(qū)B處，屈服點(diǎn)需要下列式子來確定更大的強(qiáng)化應(yīng)變率。由分式測(cè)溫：
在這些變形條件下，不斷變化的塑性變形抵抗力可以描述加工材料的特點(diǎn)。屈服點(diǎn)最大值用來描述材料抵抗堆積區(qū)B處塑性變形的特征。在處的鋼C45的實(shí)際最終剪切屈服點(diǎn)最大值達(dá)到了q=794Mpa，鋼C45具有和圖11實(shí)驗(yàn)數(shù)據(jù)相符的機(jī)械特征。在加工C45鋼時(shí)屈服點(diǎn)最大值794Mpa，要比實(shí)際剪切抗拉強(qiáng)度高出1.76倍。
研究屈服點(diǎn)的分配和楔側(cè)面和倒角堆積處的熱流動(dòng)密度對(duì)于計(jì)算工具側(cè)面的溫度是很重要的。確定屈服點(diǎn)在B和C邊界處的最大值也是同樣的重要。這個(gè)信息是用來計(jì)算溫度分布及屈服點(diǎn)的大小的，它們相互關(guān)聯(lián)，并楔斜面和切屑之間的區(qū)域C中存在塑形接觸。
5.結(jié)論
最終推導(dǎo)出的實(shí)驗(yàn)結(jié)果，我們可以確定正應(yīng)力在不同加工條件下有很大的變化，這是由于變形，應(yīng)變力還有溫度的影響。如果質(zhì)量很大，它們還會(huì)影響其屈服點(diǎn)。
如果切削材料的硬化和軟化強(qiáng)度可以被抵消，變形則會(huì)位于切屑形成區(qū)中的一個(gè)狹窄區(qū)域，并會(huì)導(dǎo)致屈服點(diǎn)的變化，也會(huì)由于最終整個(gè)定位區(qū)域的最終溫度影響而減小。通過實(shí)驗(yàn)可以證明屈服點(diǎn)在切屑形成區(qū)和堆積區(qū)中達(dá)到了最大值，堆積區(qū)的屈服點(diǎn)比切屑形成區(qū)更高。因?yàn)榍c(diǎn)并不由加工條件所決定，所以可以將它作為加工材料的實(shí)際機(jī)械特性。為了確定這些機(jī)械特性，必須實(shí)施理論方法，可以作為熱機(jī)模型來確定加工材料的實(shí)際機(jī)械特性。
熱機(jī)模型可以從分別質(zhì)量和數(shù)量上解釋屈服點(diǎn)如何在多種加工條件下產(chǎn)生大范圍的變化。另外，加工工件的實(shí)際機(jī)械特征（需要通過已知的熱機(jī)模型來確定）可以用在大量的剪切材料模型。
MACHINE TOOLDetermining mechanical characteristics of material resistanceto deformation in machiningValerii KushnerMichael StorchakReceived: 14 April 2014/Accepted: 4 July 2014/Published online: 22 July 2014? German Academic Society for Production Engineering (WGP) 2014AbstractThis paper analyses experimental results anddifferent hypotheses about the resistance of the machinedmaterial to plastic deformation in machining. It is neces-sary to take into account that strain rate and temperatureaffects the mechanical properties of the material. It isuseful to describe the regularities of material resistance toplastic deformation with differential equations, determin-ing a dependence of the specific deformation work ondeformation. For machining processes, the correlationsbetween yield point and deformation or rather flow curvesare analytically deduced from the differentiation of thespecific deformation work. It has been found out that theflow curves are vaulted for the adiabatic conditions ofdeformation in the chip forming area and the accumulationzones near the cutting edge. The yield point here reaches itsmaximum for deformations that are usually lower than thetrue final shear of the material penetrating through the chipforming area. It is suggested to take these maximum valuesof the yield point as mechanical properties of the materialto be machined. The main goal of the theoretical andexperimental investigations presented in this paper is toestablish the analytical dependence of the specific defor-mation work and therefore also of yield point and specifictangential forces on deformation, taking account of theeffect of temperature on yield point. The main advantagesof applying the specific deformation work is not only itsdirect relation to deformation temperature but also thepossibilityofexperimentallydeterminingthisworkthrough specific tangential forces and true final shear. Inthis way it is possible to establish how deformation tem-peratureaffectsyieldpointbymeansofempiricalconstants.KeywordsMachine tool ? Cutting ? Mechanicalproperties ? Flow curve1 IntroductionThe resistance characteristics of the machined material todeformationincuttingareusuallydeterminedbymechanical test methods for tension and pressure and thesubsequent extrapolation to the necessary amount of plasticdeformation occurring during machining. However, thedeformation of the material and hence the specific defor-mation work during machining is usually higher by oneorder of magnitude, and the strain rate is higher by abouteight orders of magnitude than in standard test methods fortension and pressure. In addition, large plastic deformationand an inhomogeneous deformation distribution in theprimary shear zone cause a heterogeneous temperaturedistribution. In turn, this leads to an uneven resistance ofthe machined material to plastic deformation. It has to betaken into account that the conditions differ for the defor-mation of the material in the chip forming area or ratherprimary and secondary shear zones as well as in theaccumulation zones and in the areas of the plastic contactbetween chip and wedge 1. It must also be taken intoconsideration that the resistance of the material to plasticdeformation in the shear and accumulation zones variesvery much.V. KushnerDepartment of Mechanical Engineering and Materials Science,Omsk State Technical University, pr. Mira 11, 644050 Omsk,RussiaM. Storchak (&)Institute for Machine Tools, University of Stuttgart,Holzgartenstrae 17, 70174 Stuttgart, Germanye-mail: michael.storchakifw.uni-stuttgart.de123Prod. Eng. Res. Devel. (2014) 8:679688DOI 10.1007/s11740-014-0573-8Deformation, strain rate and temperature are linked toeach other during the machining process. When deter-mining the mechanical properties of a material with astandard test, an operator establishes these factors irre-spective of such interactions. This leads to substantialerrors when determining the mechanical properties of thematerial to be machined. How the above-mentioned factorsinfluence the dependence of yield point on deformation inmachining is not taken into sufficient account. Such con-siderations are necessary because the conditions of thematerials deformation in machining processes differ con-siderably from standard tests. At present, analysing theregularities of the machined materials resistance to plasticdeformation in cutting is limited to examining only themean values of yield point, which are extended to a widerange of change in deformation. This range includes boththe areas of the hardening of the material to be machinedand the areas of the softening 26. Many investigationsare exclusively restricted to the experimental determinationof specific tangential forces in the chip forming area orprimary shear zone 35, 7, 8. This is, however, insuffi-cient to be able to establish a dependence of yield point ondeformation or rather a flow curve for machining processesand to evaluate maximum values of yield point.For different machining conditions, deformation partlyoccurs in a relatively large region of the chip forming area.This deformation is partly located in a narrow regionimmediately at the boundary of the chip forming area 5.The localisation of deformation in this narrow area has aconsiderable effect on the softening of the material to bemachined. Such an effect must absolutely be taken intoconsideration when determining the flow curve.Itisimpossibletodetermineaflowcurveofthemachinedmaterial by experiment under cutting conditions due to theuneven distribution of deformation in the shear zones.Moreover, the yield point of the material to be machineddoes not only depend on the size of deformation but also onthe change in temperature, which involves changes indeformation and yield point. The parameters mentionedhave a certain interaction with each other, which cannot beestablished by experiment. That is why not only experi-mental but also theoretical or analytical examinations haveto be carried out to determine flow curves.The main goal of the theoretical and experimentalinvestigations presented in this paper is to establish theanalytical dependence of the specific deformation work andtherefore also of yield point and specific tangential forceson deformation, taking account of the effect of temperatureon yield point.2 Analysis of hypotheses about the regularitiesof material resistance to deformation in machining2.1 Effect of strain, strain rate and temperatureon the yield pointMany researchers assumed that there are uniform regular-ities, applying to the resistance of the material to bedeformed to plastic deformation, for different cutting lay-outs of a material, including tension, forming and materialremoval, see, e.g., 35. A large number of investigationson tensile tests assume that stress intensity depends onstrain ei, strain rate _ eiand an increase in homologoustemperature DT0913:ri f ei;DT0; _ ei1Among other things, the equation (called conditionalequation in the following) representing a dependence ofshear yield point spon deformation ep, strain rate _ e and anincrease in homologous temperature DT0is defined asfollows 15:spSbffiffiffi3p ?epffiffiffi3p?ln1d=100 !m?_ e_ e0?k?DT0?exp?B?DT0;DT0DTTmT?T0Tm;2where Sbis true tensile strength, epis current value of thetrue shear, e0ffiffiffi3p? ln 1 d=100 is true shear defor-mation at a specific strain d, is strain shear rate in tension,T is the temperature of a deformable material, m, n, k, Bare empirical constants representing an effect of deforma-tion, strain rate and temperature on a current value of theyield point sp, D?T0is the mean value of increase in thehomologous temperature in the chip forming area, DT isthe change in absolute temperature, T is the current tem-perature, T0is room temperature, Tmis the melting tem-perature of the material.The conditional equation in the form of (2) cannot bedirectly applied as material model for machining processes,as an increase in temperature during cutting is not anindependent variable and depends on deformation epaswell as the current yield point sp. Hence, the conditionalequationformeetingthedeformationconditionsinmachining has to be searched for in the form of a flowcurve sp(ep) containing empirical constants. These con-stants represent effects of deformation, strain rate andtemperature.680Prod. Eng. Res. Devel. (2014) 8:6796881232.2 Hypothesis about an application of the simple formof loading by cuttingThe dependences of specific tangential forces stin theconditional shear plane on true final shear ewwhen turningdifferent steels were compared with the dependences ofshear yield point on shear deformation in tension sp(ep) 3.The specific tangential forces stwere interpreted here asmaximum values of the yield point in the chip formingarea. It is, however, more correct to interpret the specifictangential forces st, obtained by experiment, as quotient ofthe specific deformation work in relation to true final shearewor rather as average of the yield point. This follows froma definition of the specific tangential force stin the chipforming area by the projection Fsof the forces Rnand Rmon the rake face of the wedge onto the shear plane A andthe deformation capacity in the chip forming area throughthis force Fsand the specific deformation work AwFig. 1.The following dependences can be deduced from theabove-mentioned and Fig. 1:Fs? v2 ss?a ? bsin uy? v2 Aw? Sb? a ? b ? v3where b is width of cut.AwZew0spSbdep4The following can be concluded from (3):ssSb1ew? Aw;ssv ? sinuyv2? Aw? Sb;v2 v ?cos ccos uy? c?;ewv2v ? sinuyK 1=K ? 2 ? sin ccos c5where m2is the velocity of the chip shear relative to theworkpiece in the direction of the shear plane A, ewis truefinal shear, K is chip compression ratio.To extrapolate the dependences sp(ep), a law of singleload was used which does not take account of an effect ofstrain rate and temperature on yield point 15:spSbffiffiffi3p ?epe0?m62.3 Hypothesis about the stability of specific tangentialforces in the chip formation zone and their relationto material strength by tensile testIt was detected that specific tangential forces stinmachining were close to the shear yield point in tensionin several cases 3. This yield point was established hereby extrapolating the dependence (3) on the size ofdeformation of the true shear during machining. For thisreason an empirical correlation was suggested to estimatespecific tangential forces stin the shear plane duringmachining 3:st? A ? 2:5m A2:5;7where A is the empirical coefficient; A2.5is the shear yieldpoint in tensile tests, which is extrapolated to a deformationof e = 2.5.Regarding the majority of several examined steels, theforces stdid nevertheless not increase with growingdeformation as required by the law of single load (see 6).They rather remained constant or even decreased.Apart from the dependence (7), other correlationsbetween forces stand strength characteristics in tensiletests were suggested as well. Among other things, thefollowing empirical correlations were obtained for estab-lishing specific tangential forces stin the chip forming areaand on the rake face qFwhen turning different steels usingtools with shortened rake faces 1, 16:Fig. 1 Layout for establishing the specific tangential force ssin thechip forming area (a), velocity diagram and cutting scheme (b)Prod. Eng. Res. Devel. (2014) 8:679688681123st 0:8 ? Sb;qF 0:6 ? Sb8These correlations obtained by experiment are presentedin Fig. 2.These constant and decreasing dependences st(ew) showthat the flow curves sp(ep) for tensile tests and machiningdo not agree with each other. This corresponds with theexperimental investigations on machining and pressure ofaluminium in the range of changes in shear deformationbetween 0.6 and 1.5 9. The specific tangential forces inthe shear plane during machining were considerablygreater here than the compression strength.That the flow curves for pressure and machining in therange of smaller deformations do not agree can beexplained by the effect of strain rate on the stresses in theshear plane during machining. The effect of temperature onthe yield point and the specific tangential forces inmachining are assessed differently as well. One side con-tests that temperature affects the specific tangential forcesin the chip forming area and on the rake face of the wedge3, 4, 14. This is confirmed by the fact that the temperaturein the chip forming area does not exceed a limit of 400 ?Cas a rule 15. In addition, it was assumed that a decrease inyield point during machining is completely compensatedby its increase on account of a major effect of strain rate athigher temperatures 16. Assuming that temperature hasno substantial effect was accepted regarding both the spe-cific tangential forces in the chip forming area and thespecific tangential forces on the rake face of the wedge 8,13, 17. Another side confirms that strain rate and tem-perature have a considerable effect on the yield point inmachining 1, 15.The following analysis of the experimental data is pre-sented to justify the latter point of view.3 Effect of strain rate and temperature on specifictangential forces in the chip forming area3.1 Effect of strain rateOwing to the analysis of results obtained by experiment, itis detected in 3 that the ratio of strain rates in tension andmachining affects the mean value of yield point. Specifictangential forces stare examined when machining differentsteels at a depth of cut of a = 0.22 mm and a toolorthogonal rake angle of the wedge of c = 20?. Experi-mental analyses were carried out at extremely low cuttingspeeds of m = 0.2 m/min to rule out an effect of temper-ature on specific tangential forces st3. In addition, tensiletests were simultaneously conducted at the same strainrates. A quotient of the strain rates in machining and tensiletests was approximately two powers smaller than withconventional cutting parameters. This quotient is, however,great enough and reaches about 106.In view of the fact that specific tangential forces stin thechip forming area are characterised by mean values of yieldpoint, they are compared with extrapolated mean values oftensile strength:st;m1ew?Zew0Sbffiffiffi3p ?epe0?mdep1ew? Aw;t? SbA ? Sbm 1? emw;9Aw;tZew0spSbdep;10where Aw,tis the dimensionless specific deformation workin tensile tests, which is extrapolated to deformations of thetrue final shear during machining ew.If the strain rate is taken into account and an effect oftemperature is ruled out, a dependence of specific tangen-tial forces stin the chip forming area at mean values ofFig. 2 Mean specific tangential forces stin the chip forming area andon the shortened rake face of the wedge qFdepending on true tensilestrength Sbin machining 16682Prod. Eng. Res. Devel. (2014) 8:679688123tensile strength can be approximated by the followingfunction:st Ke? st;m;11where Keis the coefficient of deformability, determiningthe differences between the deformation conditions of themachined material in the chip forming area for machiningand tensile tests.Table 1 shows the experimental data and results whencomparing specific tangential forces stin the shear planewith the mean values of yield point ss,m.In the machining of the examined steels, the forces stareapproximately 1.3 times greater than the mean values oftensile strength extrapolated to the deformation of true finalshear in machining (see Table 1). Hence, the coefficient Keis 1.3. According to this coefficient, an increase in strainrate by about 106, which corresponds to a transition fromtensile tests to machining at relatively low homologoustemperatures T0= 0,165), is capable of causing a consid-erable rise in the mean value of yield point st,m.To estimate the effect of homologous temperature on thecoefficient of deformability Ke, it is analysed how relativechanges in strain rate affect the yield point in the machiningof different materials 4 such as lead, aluminium and steel.The results of the analysis are shown in Fig. 3.Hence,thecoefficientofdeformabilityKeinmachining and other kinds of deformation such as, e.g.,tensile tests does not only depend on changes in strainrate _ e/_ e0but also on changes in homologous temperatureDT0. For modern machining processes, the difference incutting speed is within one degree of power at most.Contrary to this, the difference between the speed of astandardised tensile or pressure test and the cutting speedin machining is eight degrees of power. A change indeformation speed within in one degree, which impliesthe change in cutting speeds for different machiningprocesses, changes the derived coefficient of deformabi-lity from 1.258 to 1.344. This change in the coefficientof deformability can be ignored. Therefore, a quotient ofstrain rates for machining in the range of conventionalcutting parameters and for tensile tests is about 108andcan be assumed as constant 15. Accordingly, the valuesof the coefficient Kehave to be greater with growinghomologous temperature (see Fig. 3). This coefficient canbe represented as a function of the increase in homolo-gous temperature:Ke 108k?DT0123.2 Effect of the deformation temperatureOwing to the experimental data of specific tangential forcesin the chip forming area and on the rake face of the wedge,it can be inferred that there is a hardening effect of themachined material due to the change in coefficient Keaswell as a softening effect of the temperature in machining1. For example, it can be concluded from the experi-mental data shown in Fig. 2a, that yield point rises roughlyproportionally to the increase in true breaking point as wellas that the quotient st/Sbdecreases with increasing truetensile strength Sbor correspondingly increasing defor-mation temperature hD:hD?st? ewCV;13where CVis the specific volumetric heat capacity of thematerial to be machined.Figure 4 shows how temperature affects the mean yieldpoint when machining different steels. Specific tangentialforces in the area of plastic contact between tool and chipare lower than in the chip forming zone, when machiningsteels with a shortened rake face of the wedge (see 8):qF& 0.75 ? st16. Such a ratio of the values of meanspecific tangential forces in the chip forming area and inthe area of plastic contact can be interpreted in favour ofthe decrease in yield point of the machined material on therake face with growing temperature (see Fig. 4b). Thisresults in the uneven distribution of the specific tangentialforces on the rake face of the wedge, involving an increaseTable 1 Experimental data for machining and tensile tests (rbelastic limit)No.Kind ofsteeld, %rb,MPamss,m,MPaewst,MPa1St00383180.33564.14602C10423620.33803.3490320Cr354800.34773.15804Cr18Ni9Ti636340.56702.51,030Fig. 3 Effect of homologous temperature on the coefficient ofdeformability KeProd. Eng. Res. Devel. (2014) 8:679688683123in temperature. This leads to the effect of temperature onyield point in machining.It is assumed that the maximum value of yield point isreached in the accumulation zone B (see Fig. 1a) near thecutting edge at lower temperatures. Accordingly, themaximum value of yield point in the accumulation zones ofthe rake face q0and the flank face should be considerablygreater than stand qF.Regarding todays state of the measuring technology, itis impossible or very difficult to determine the directexperimental reason why there is such a maximum bymeans of establishing the change in specific tangentialforces in the very small area of the accumulation zone B.However, this can be indirectly accounted for by estab-lishing specific tangential forces in the accumulation zoneG of the flank face (see Fig. 1a), where the deformationconditions are very similar to the corresponding conditionsof the accumulation zone B 16. Such changes in specifictangential forces in the accumulation zone G of the flankface were investigated for the machining of steel C45 1.It was found out that the specific tangential forces in theaccumulation zone G are greater than in the chip
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