礦用液壓支架設(shè)計(jì)

礦用液壓支架設(shè)計(jì),液壓,支架,設(shè)計(jì) 河南理工大學(xué)萬方科技學(xué)院本科畢業(yè)設(shè)計(jì)（論文）中期檢查表指導(dǎo)教師： 楊志波 職稱： 副教授 所在系部（單位）： 機(jī)械與動(dòng)力工程學(xué)院 教研室（研究室）： 機(jī)械教研室 題 目 礦用液壓支架的設(shè)計(jì)學(xué)生姓名林超專業(yè)班級(jí) 07機(jī)制2班 學(xué)號(hào)0720150088一、選題質(zhì)量1， 該選題為礦用液壓支架設(shè)計(jì)，符合專業(yè)培養(yǎng)目標(biāo)，能夠體現(xiàn)綜合訓(xùn)練的要求，可以對(duì) 我們大學(xué)四年所學(xué)知識(shí)進(jìn)行一次全面的練習(xí)。2， 這將對(duì)我們以后深造學(xué)習(xí)和工作起到十分有效的幫助，也能達(dá)到一個(gè)綜合訓(xùn)練的效果，又加強(qiáng)了實(shí)際的動(dòng)手動(dòng)腦能力。3， 題目的難易程度很適中，對(duì)我們既是一個(gè)挑戰(zhàn)也是一個(gè)很好的鍛煉提高過程。4， 題目的工作量：要求完成3張以上的A0圖紙，5060頁的說明書一份。5， 選題不但能緊密的結(jié)合生產(chǎn)和實(shí)踐，而且在我們所學(xué)課程的范圍之內(nèi)，對(duì)我們 以后不管是科研還是從事實(shí)際的工作都有很大的幫助。二、開題報(bào)告完成情況在老師指導(dǎo)和同學(xué)們的幫助之下，我順利的開始本次畢業(yè)設(shè)計(jì)。我在自己經(jīng)過一些查閱資料的前提下，慢慢地理出頭緒,摸索出了設(shè)計(jì)思路。 由于我們這次是礦用液壓支架的設(shè)計(jì)，以前接觸這方面的知識(shí)較少，所以在剛開始不是很順利，甚至感到有些無從下手，但是經(jīng)過和指導(dǎo)老師的提導(dǎo)、與本組同學(xué)的商量、在工廠實(shí)習(xí)觀看實(shí)物之后， 我逐漸找到設(shè)計(jì)的切入點(diǎn)，順利的完成了開題報(bào)告。并有了一定的成果和進(jìn)行了一些前期的工作，并使本次設(shè)計(jì)有了一個(gè)良好的開始。在查閱了一些資料后，已經(jīng)進(jìn)行了計(jì)算設(shè)計(jì)，正在整理說明書,并進(jìn)行初步繪制草圖.我將繼續(xù)努力，認(rèn)真完成這次畢業(yè)設(shè)計(jì)。 三、階段性成果 1通過對(duì)液壓傳動(dòng)原理的學(xué)習(xí)，在加上老師的仔細(xì)講解，我收集了大量的資料和文獻(xiàn)，為設(shè)計(jì)的順利完成打下了堅(jiān)實(shí)的基礎(chǔ)。 2. 在老師的指導(dǎo)和同學(xué)的幫助下找到了設(shè)計(jì)的基本方法，開始了一些基本的原理的設(shè)計(jì)計(jì)算，并取得了一定成果。 3. 完成了開題報(bào)告。 4對(duì)整個(gè)設(shè)計(jì)有了一個(gè)總體的方案,并進(jìn)行了前期的一些工作和設(shè)計(jì).四、存在主要問題 由于在液壓傳動(dòng)原理及機(jī)械原理的理解不夠深入,實(shí)際經(jīng)驗(yàn)不足,而且這方面參考資料有限,所以隨著設(shè)計(jì)的逐漸進(jìn)行中我遇到了許多新的和更加復(fù)雜的問題，這些問題使我充分認(rèn)識(shí)到了自己在以前學(xué)習(xí)中的不足和自己與一些同學(xué)在專業(yè)知識(shí)方面的差距，所以我要以本次設(shè)計(jì)為契機(jī)加強(qiáng)自己在學(xué)習(xí)上薄弱環(huán)節(jié)，爭取使我的畢業(yè)設(shè)計(jì)能夠取得好的成績，也能夠使我所學(xué)的知識(shí)能夠在以后的工作中發(fā)揮更大的作用。五、指導(dǎo)教師對(duì)學(xué)生在畢業(yè)實(shí)習(xí)中，勞動(dòng)、學(xué)習(xí)紀(jì)律及畢業(yè)設(shè)計(jì)（論文）進(jìn)展等方面的評(píng)語指導(dǎo)教師： （簽名） 年 月 日河南理工大學(xué)萬方科技學(xué)院本科畢業(yè)設(shè)計(jì)（論文）開題報(bào)告題目名稱礦用液壓支架學(xué)生姓名林超 專業(yè)班級(jí)07機(jī)制2班學(xué)號(hào)0720150088一、 本課題的研究目的和意義通過本次畢業(yè)設(shè)計(jì)，培養(yǎng)學(xué)生綜合運(yùn)用液壓傳動(dòng)、機(jī)械設(shè)計(jì)、工程理學(xué)等課程中所學(xué)理論知識(shí)的能力；強(qiáng)調(diào)設(shè)計(jì)的獨(dú)創(chuàng)性和實(shí)用性，培養(yǎng)和提高設(shè)計(jì)者獨(dú)立分析問題和解決實(shí)際問題的能力，為今后適應(yīng)工作崗位和創(chuàng)造性地開展工作打下堅(jiān)實(shí)基礎(chǔ)。采用綜合機(jī)械化采煤方法是大幅度增加煤炭產(chǎn)量，提高經(jīng)濟(jì)效益的必由之路。為了滿足對(duì)煤炭日益增長的需要，必須大量生產(chǎn)綜合機(jī)械化采煤設(shè)備，迅速增加綜合機(jī)械化采煤工作面（簡稱綜采工作面）。而每個(gè)綜采工作面平均需要安裝150臺(tái)液壓支架，可見對(duì)液壓支架的需要量時(shí)很大的。由于不同采煤工作面的頂?shù)装鍡l件，煤層厚度、煤層傾角、煤層的物理機(jī)械性質(zhì)等的不同，對(duì)液壓支架的要求也不同，為了有效的支護(hù)和控制頂板，必須設(shè)計(jì)出不同類型和不同結(jié)構(gòu)尺寸的液壓支架。因此，液壓支架的設(shè)計(jì)工作是很重要的。由于液壓支架的類型很多，因此其設(shè)計(jì)工作量是很大的，由此可見，研制和開發(fā)新型液壓支架是必不可少的一個(gè)環(huán)節(jié)。在過去的半個(gè)多世紀(jì)中，煤礦井下開采支護(hù)設(shè)備的設(shè)計(jì)和使用發(fā)生了巨大變化。其中，最引人矚目的是世界范圍內(nèi)廣泛采用液壓支架作為長臂開采支護(hù)工程的主要設(shè)備。從采煤設(shè)備的發(fā)展過程來看，采用液壓支架管理頂板是當(dāng)代采煤技術(shù)史上一次重要的變革，也是煤礦現(xiàn)代化的主要標(biāo)志。液壓支架作為綜合機(jī)械化采煤的關(guān)鍵設(shè)備之一，其重量約占綜合采煤設(shè)備總重量的80%90%，其費(fèi)用約占綜合采煤設(shè)備總費(fèi)用的60%70%。因此，為了降低成本提高采煤的經(jīng)濟(jì)效益，世界各主要產(chǎn)煤大國都一直在積極地開展液壓支架的研究。河南理工大學(xué)萬方科技學(xué)院本科畢業(yè)論文摘 要本論文主要闡述了一般掩護(hù)式液壓支架的設(shè)計(jì)過程。設(shè)計(jì)內(nèi)容包括：選架型、總體設(shè)計(jì)、主要零部件的設(shè)計(jì)、主要零部件的校核和液壓系統(tǒng)的設(shè)計(jì)。由于該煤層厚度適中，選用掩護(hù)式液壓支架。煤層厚度介于之間，煤層厚度變化較大，選用調(diào)高范圍大且抗水平推力強(qiáng)且?guī)ёo(hù)幫裝置的掩護(hù)式支架。支架采用正四連桿機(jī)構(gòu)，以改善支架受力狀況。頂梁、掩護(hù)梁、底座均做成箱體結(jié)構(gòu)；立柱采用雙伸縮作用液壓缸，以增加工作行程來滿足支架調(diào)高范圍的需要。推移千斤頂采用框架結(jié)構(gòu)，以減少推溜力和增大移架力。為了提高移架速度，確保對(duì)頂板的及時(shí)支護(hù)，采用錐閥液壓系統(tǒng)。關(guān)鍵詞：液壓支架 液壓 四連桿機(jī)構(gòu) 采煤 支架選型 推溜 移架- III -河南理工大學(xué)萬方科技學(xué)院本科畢業(yè)論文AbstractThe article mainly elaborated the general shield type hydraulic pressure support design process. The design content includes: Chooses, the system design, the main spare part design, the main spare part examination and the hydraulic system design.Because this coal bed thickness is moderate, selects the shield type hydraulic pressure support. Coal bed thickness is situated between between the 2.53.8 rice, coal bed thickness change bigger, selects adjusts the high scope big also the anti- horizontal thrust is strong also the belt protects helps the equipment the shield type support. The support uses the four link motion gear, improves the support stress condition. The top-beam, caving shield, the foundation makes the packed in a box body structure; The column uses the double expansion and contraction function hydraulic cylinder, increases the power stroke to satisfy the support to adjust the high scope the need. Passes the hoisting jack to use the portal frame construction, reduces pushes slides the strength and increases moves a strength. In order to enhance moves a speed, guarantees is prompt to the roof support, uses the mushroom valve hydraulic system.Key word: The hydraulic pressure support , hydraulic pressure , four-link mechanism , mining coal, support shaping push forwards the conveyer, advancing the powered support.河南理工大學(xué)萬方科技學(xué)院本科畢業(yè)論文目 錄1 概述11.1 液壓支架的組成和分類11.1.1液壓支架的組成11.1.2液壓支架的分類21.2液壓支架的工作原理21.3 液壓支架的支護(hù)方式51.4支架選型的基本參數(shù)61.4.1 對(duì)液壓支架的基本要求62 液壓支架的總體設(shè)計(jì)2.1 液壓支架的選型2.2 液壓支架參數(shù)的確定2.2.1 支護(hù)強(qiáng)度和工作阻力2.2.2 初撐力2.2.3 移架力與推溜力2.2.4 支架調(diào)高范圍2.2.5 中心距和寬度的確定2.2.6 底座寬度2.3 采煤機(jī)、液壓支架和輸送機(jī)的配套2.3.1 采煤機(jī)、液壓支架和輸送機(jī)的配套2.3.2 其他附屬設(shè)備的配套2.4 四連桿機(jī)構(gòu)設(shè)計(jì)2.4.1 四連桿機(jī)構(gòu)的作用2.4.2 用優(yōu)選設(shè)計(jì)法設(shè)計(jì)四連桿機(jī)構(gòu)2.5 頂梁長度的確定2.6立柱及柱窩位置的確定2.7平衡千斤頂位置的確定2.7.1 平衡千斤頂安裝位置的確定原則2.7.2 平衡千斤頂在頂梁上位置的確定2.8其它千斤頂技術(shù)參數(shù)的確定2.8.1 推移千斤頂技術(shù)參數(shù)2.8.2 側(cè)推千斤頂技術(shù)參數(shù)2.8.3 前梁千斤頂技術(shù)參數(shù)2.8.4 護(hù)幫板千斤頂?shù)募夹g(shù)參數(shù)3 液壓支架受力分析和計(jì)算3.1 受力分析計(jì)算3.2 支護(hù)強(qiáng)度計(jì)算3.3 底座比壓的計(jì)算4 液壓支架的主要部件的設(shè)計(jì)4.1 前梁4.2 主頂梁4.3 掩護(hù)梁4.4 前、后連桿4.5 底座4.6 立柱4.7 千斤頂4.7.1 推移千斤頂5 主要零、部件的強(qiáng)度校核5.1校核的基本要求5.2前梁強(qiáng)度校核5.2.1 前梁受力情況5.2.2 前梁強(qiáng)度計(jì)算5.3 主頂梁強(qiáng)度校核5.3.1 主頂梁受力情況5.3.2 主頂梁強(qiáng)度計(jì)算5.4 掩護(hù)梁強(qiáng)度校核5.4.1 掩護(hù)梁受力情況5.4.2 掩護(hù)梁強(qiáng)度計(jì)算5.5 底座強(qiáng)度校核5.5.1 底座受力情況5.5.2 底座強(qiáng)度校核5.6 立柱強(qiáng)度的校核5.6.1 立柱穩(wěn)定性校核6 液壓系統(tǒng)6.1 液壓支架的液壓系統(tǒng)的簡介6.1.1 液壓支架傳動(dòng)系統(tǒng)的基本要求6.1.2 液壓支架的液壓傳動(dòng)特點(diǎn)致 謝參考文獻(xiàn)IV河南理工大學(xué)萬方科技學(xué)院本科畢業(yè)論文1 概述1.1 液壓支架的組成和分類1.1.1液壓支架的組成液壓支架是綜采工作面支護(hù)設(shè)備，它的主要作用是支護(hù)采場頂板，維護(hù)安全作業(yè)空間，推移工作面采運(yùn)設(shè)備。液壓支架的種類很多，但其基本功能是相同的。液壓支架按其結(jié)構(gòu)特點(diǎn)和與圍巖的作用關(guān)系“般分為三大類，即支撐式、掩護(hù)式(圖1-2)和支撐掩護(hù)式(圖1-3) 根據(jù)支架各部件的功能和作用，其組成可分為4個(gè)部分：(1) 承載結(jié)構(gòu)件，如頂梁、掩護(hù)梁、底座、連桿、尾梁等。其主要功能是承受和傳遞頂板和垮落巖石的載荷。(2) 液壓油缸，包括立柱和各類千斤頂。其主要功能是實(shí)現(xiàn)支架的各種動(dòng)作，產(chǎn)生液壓動(dòng)力。 (3) 控制元部件，包括液壓系統(tǒng)操縱閥、單向閥、安全閥等各類閥，以及管路、液壓、電控元件等。其主要功能是操作控制支架各液壓油缸動(dòng)作及保證所需的工作特性。圖1-2 掩護(hù)式液壓支架結(jié)構(gòu) 圖1-3 支撐掩護(hù)式液壓支架結(jié)構(gòu) (4) 輔助裝置，如推移裝置、護(hù)幫(或挑梁)裝置、伸縮梁(或插板)裝置、活動(dòng)側(cè)護(hù)板、防倒防滑裝置、連接件等。這些裝置是為實(shí)現(xiàn)支架的某些動(dòng)作或功能所必需的裝置。1.1.2液壓支架的分類按液壓支架在采煤工作面的安置位置來劃分，有端頭液壓支架和中間液壓支架。端頭液壓支架簡稱端頭支架，專門安裝在每個(gè)采煤工作面的兩端。中間液壓支架是安裝在除工作面端頭以外的采煤工作面所有位置的支架。中間液壓支架按其結(jié)構(gòu)形式來劃分，可分為三種基本類型，即：支撐式、掩護(hù)式和支撐掩護(hù)式。1.2液壓支架的工作原理液壓支架在工作過程中必須具備升、降、推、移四個(gè)基本動(dòng)作，這些動(dòng)作是利用泵站供給的高壓乳化液通過工作性質(zhì)不同的幾個(gè)液壓缸來實(shí)現(xiàn)完成的。如圖1-5示1. 升柱當(dāng)需要支架上升支護(hù)頂板時(shí)。高壓乳化液進(jìn)入立柱的活塞腔，另一腔回液，推動(dòng)活塞上升，使與活塞桿相連接的頂梁接觸頂板。2. 降柱當(dāng)需要降柱時(shí)，高壓液進(jìn)入立柱的活塞桿腔，另一腔回液，迫使活塞桿下降，于是頂梁脫離頂板。圖1-5 液壓支架工作原理-頂梁 -立柱 -底座 -推移千斤頂 -安全閥 -液控單向閥 、-操縱閥 -輸送機(jī) -乳化液泵 -主供液管 -主回液管3. 支架和輸送機(jī)前移支架和運(yùn)輸機(jī)的前移，都是由底座上的推移千斤頂來完成的。當(dāng)需要支架前移時(shí)，先降柱卸載，然后高壓液進(jìn)入推移千斤頂?shù)幕钊麠U腔，另一腔回液，以輸送機(jī)為支點(diǎn)，缸體前移，把整個(gè)支架拉向煤壁；當(dāng)需要推運(yùn)輸機(jī)時(shí)，支架支撐頂板后，高壓液進(jìn)入推移千斤頂?shù)幕钊?，另一腔回液，以支架為支點(diǎn)，是活塞桿伸出，把運(yùn)輸機(jī)推向煤壁。支架的支撐力與時(shí)間曲線，稱為支架的工作特性曲線，如圖1-6所示：支架立柱工作時(shí)，其支撐力隨時(shí)間的變化過程可分為三個(gè)階段-初撐階段； -增阻階段； -恒阻階段；-初撐力；-工作阻力（1）初撐階段支架在升柱時(shí)，高壓液進(jìn)入立柱下腔，立柱升起使頂梁接觸頂板，立柱下腔壓力增加，當(dāng)增加到泵站工作壓力時(shí)，泵站自動(dòng)卸載，支架的夜控單向閥關(guān)閉，立柱下腔壓力達(dá)到初撐力，此階段為初撐階段，此時(shí)支架對(duì)頂板的支撐力為初撐力。支撐式支架的初撐力為 (1.1) 圖1-6 支架的工作特性曲線式中 -支架立柱的缸徑，；-泵站的工作壓力，；-支架立柱的數(shù)量。 由上式可知，支架初撐力的大小取決于泵站的工作壓力，立柱缸徑和立柱的數(shù)量。合理的初撐力是防止直接頂過早的因下沉而離層、減緩頂板下沉速度、增加其穩(wěn)定性和保證安全生產(chǎn)的關(guān)鍵。一般采用提高泵站工作壓力的辦法來提高初撐力，以免立柱的缸徑過大。（2）承載增阻階段支架初撐后，隨頂板下沉，立柱下腔壓力增加，直到增加到支架的安全閥調(diào)正壓力，立柱下腔壓力達(dá)到工作阻力。此階段為增阻階段。（3）恒阻階段隨著頂板壓力繼續(xù)增加，使立柱下腔壓力超過支架的安全閥壓力調(diào)正值時(shí)，安全閥打開而溢流，立柱下縮，使頂板壓力減小，立柱下腔壓力降低，當(dāng)?shù)陀诎踩y壓力調(diào)整之后，安全閥停止溢流，這樣在安全閥調(diào)整壓力的限制下，壓力曲線隨時(shí)間呈波浪形變化，此階段為恒阻階段。此時(shí)支架對(duì)頂板的支撐力稱為工作阻力，它是由支架安全閥的調(diào)定壓力決定的。支撐式支架的工作組力為 (1.2)式中 -支架安全閥的調(diào)定壓力 ；支架的工作阻力標(biāo)志著支架的最大承載能力。對(duì)于掩護(hù)式和支撐掩護(hù)式支架，其初撐力和工作阻力的計(jì)算還要考慮到立柱傾角的影響因素。支架的工作阻力是支架的一個(gè)重要參數(shù)，它表示支架支撐力的大小。但是，由于支架的頂梁長短和間距大小不同，所以并不能完全反映支架對(duì)頂板的支撐能力。因此，常用單位支護(hù)面積頂板上所受支架工作阻力值的大小，即支護(hù)強(qiáng)度來表示支架的支護(hù)性能。即 (1.3) 式中 支架的支護(hù)面積，。1.3 液壓支架的支護(hù)方式綜采工作面的主要生產(chǎn)工序有采煤、移架和推溜。 3個(gè)工序的不同組合順序，可形成液壓支架的3種支護(hù)方式，從而決定工作面“三機(jī)”的不同配套關(guān)系。1 即時(shí)支護(hù)般循環(huán)方式為：割煤一移架一推溜，工作面“三機(jī)”的配套關(guān)系。即時(shí)支護(hù)的特點(diǎn)是，頂板暴露時(shí)間短，梁端距較小。適用于各種頂板條件，是目前應(yīng)用最廣泛的支護(hù)方式。2 滯后支護(hù)一般循環(huán)方式為：割煤一推溜一移架。滯后支護(hù)的特點(diǎn)是，支護(hù)滯后時(shí)間較長，梁端距大，支架頂梁較短。可用于穩(wěn)定、完整的頂板。3 復(fù)合支護(hù)般循環(huán)方式為：割煤一支架伸出伸縮梁一推溜一收伸縮梁一移架。復(fù)合支護(hù)的特點(diǎn)是：支護(hù)滯后時(shí)間短，但增加了反復(fù)支撐次數(shù)?？蛇m用于各種頂板條件，但支架操作次數(shù)增加，不能適應(yīng)高產(chǎn)高效要求，目前應(yīng)用較少。1.4支架選型的基本參數(shù)1.4.1 對(duì)液壓支架的基本要求1. 為了滿足采煤工藝及地質(zhì)條件的要求，液壓支架要有足夠的初撐力和工作阻力，以便有效地控制頂板，保證合理的下沉量。2. 液壓支架要有足夠的推溜力和移架力。推溜力一般為左右；移架力按煤層厚度而定，薄煤層一般為,中厚煤層一般為,厚煤層一般為。3. 防矸性能要好。4. 排矸性能要好。5. 要求液壓支架能保證采煤工作面有足夠的通風(fēng)斷面，從而保證人員呼吸、稀釋有害氣體等安全方面的要求。6. 為了操作和生產(chǎn)的需要，要有足夠?qū)挼娜诵械馈?. 調(diào)高范圍要大，照明和通訊方便。8. 支架的穩(wěn)定性要好，底座最大比壓要小于規(guī)定值。9. 要求支架有足夠的剛度，能夠承受一定得不均勻載荷和沖擊載荷。10. 滿足強(qiáng)度條件下，盡可能的減輕支架重量。11. 要易于拆卸，結(jié)構(gòu)要簡單。12. 液壓元件要可靠。山東科技大學(xué)學(xué)士學(xué)位論文 液壓支架的總體設(shè)計(jì)河南理工大學(xué)萬方科技學(xué)院本科畢業(yè)論文2 液壓支架的總體設(shè)計(jì)2.1 液壓支架的選型正確選擇液壓支架的架型，對(duì)于提高綜采工作面的產(chǎn)量和效率，充分發(fā)揮綜采設(shè)計(jì)的效能，實(shí)現(xiàn)高產(chǎn)高效，是一個(gè)很重要的因素。在具體選擇架型時(shí)，首先要考慮煤層的頂板條件。表2-1是根據(jù)國內(nèi)外液壓支架的使用經(jīng)驗(yàn)，提出了各種頂板條件下適用的架型，它是選擇支架的主要依據(jù).由于給定參數(shù)中頂?shù)装嫘再|(zhì)：老頂I級(jí)、直接頂2級(jí)，底板平整，無影響支架通過的斷層，初步選擇為掩護(hù)式支架。1 煤層厚度煤層厚度不但直接影響到支架的高度和工作阻力，而且還影響到支架的穩(wěn)定性。當(dāng)煤層厚度大于(軟煤層下限，硬煤層上限)時(shí)，應(yīng)選用抗水平推力強(qiáng)且?guī)ёo(hù)幫裝置的掩護(hù)式或支撐掩護(hù)式支架。當(dāng)煤層厚度變化較大時(shí)，應(yīng)選用調(diào)高范圍大的支架。因此本次設(shè)計(jì)應(yīng)選用抗水平推力強(qiáng)且?guī)ёo(hù)幫裝置的掩護(hù)式支架。2 煤層傾角煤層傾角主要影響支架的穩(wěn)定性、傾角大時(shí)易發(fā)生傾倒下滑等現(xiàn)象。當(dāng)煤層傾角大于時(shí)，應(yīng)設(shè)防滑和調(diào)架裝置，當(dāng)傾角超過時(shí)，應(yīng)同時(shí)具有防滑防倒裝置。給定煤層傾角，不用設(shè)置防滑和調(diào)架裝置。3 底板性質(zhì)底板承受支架的全部載荷，對(duì)支架的底座影響較大，底板的軟硬和平整性，基本上決定了支架地做的結(jié)構(gòu)和支撐面積。選型時(shí)，要驗(yàn)算底座對(duì)底板的接觸比壓，其值要小于底板允許比壓（對(duì)于砂巖底板，允許比壓為,軟底板為左右）4 瓦斯涌出量 對(duì)于瓦斯涌出量大的工作面，支架的通風(fēng)斷面應(yīng)滿足通風(fēng)的要求，選型時(shí)要進(jìn)行驗(yàn)算。表2-1老頂級(jí)別IIIIIIIV直接頂級(jí)別12312312344支架類型掩護(hù)式掩護(hù)式支撐式掩護(hù)式掩護(hù)式或支撐掩護(hù)式掩護(hù)式支撐掩護(hù)式支撐掩護(hù)式支撐或支撐掩護(hù)式支撐或支撐掩護(hù)式支撐式采高小于2.5m時(shí)支撐掩護(hù)式采高大于2.5m時(shí)支架支護(hù)強(qiáng)度采高12340.2940.343（0.245）0.441（0.343）0.539（0.441）1.30.2941.30.343（0.245）1.30.441（0.343）1.30.539（0.441）1.60.2941.60.3431.60.4411.60.53920.29420.34320.44120.539應(yīng)結(jié)合深孔爆破，軟化頂板等措施處理采空區(qū)單體支柱支護(hù)強(qiáng)度采高123.0.1470.2450.3431.30.1471.30.2451.30.3431.60.1471.60.2451.60.343按采空區(qū)處理方法確定注：括號(hào)內(nèi)的數(shù)字是掩護(hù)式支架的支護(hù)強(qiáng)度。表中所列支護(hù)強(qiáng)度在選用時(shí)，可根據(jù)本礦情況允許有5%的波動(dòng)范圍。表中1.3、1.6、2分別為II、III、IV級(jí)老頂?shù)姆旨?jí)增壓系數(shù)；IV級(jí)老頂只給出最低值2，選用時(shí)可根據(jù)本礦實(shí)際確定適宜值。2.2 液壓支架參數(shù)的確定2.2.1 支護(hù)強(qiáng)度和工作阻力支護(hù)強(qiáng)度取決于頂板性質(zhì)和煤層厚度。支護(hù)強(qiáng)度可根據(jù)下列公式估算： （2.1）式中K作用與支架上的頂板巖石系數(shù)，一般取。頂板條件好、周起來壓不明顯時(shí)取下限，否則取上限；H采高，頂板巖石密度，一般為放頂煤支架的支護(hù)強(qiáng)度一般為支架工作阻力P應(yīng)滿足頂板支護(hù)強(qiáng)度的要求，即支架工作阻力由支護(hù)強(qiáng)度和支護(hù)面積所決定。 （2.2）式中 F支架的支護(hù)面積，可按下式計(jì)算2.2.2 初撐力初撐力的大小是相對(duì)與支架的工作阻力而言，并與頂板的性質(zhì)有關(guān)。較大的初撐力可以使支架較快地達(dá)到工作阻力，防止頂板過早的離層，增加頂板的穩(wěn)定性。對(duì)于不穩(wěn)定和中等穩(wěn)定頂板，為了維護(hù)機(jī)道上方的頂板，應(yīng)取較高的初撐力，約為工作阻力的80%；對(duì)于穩(wěn)定頂板，初撐力不宜過大，一般不低于工作阻力的60%，對(duì)于周期來壓強(qiáng)烈的頂板，為了避免大面積的垮落對(duì)工作面的動(dòng)載威脅，應(yīng)取較高的初撐力，約為工作阻力的75%。2.2.3 移架力與推溜力移架力與支架結(jié)構(gòu)、噸位、支撐高度、頂板狀況是否帶壓移架等因素有關(guān)。一般薄煤層支架的一架力為;中等厚度煤層支架為;厚煤層為。推溜力一般為.2.2.4 支架調(diào)高范圍支架最大結(jié)構(gòu)高度 (2.5)支架最小結(jié)構(gòu)高度 (2.6)式中 、煤層最大、最小采高偽頂冒落的最大厚度，一般取頂板周期來壓時(shí)的最大下沉量、移架使支架的下降量和頂梁上、底座下的浮矸、煤層厚度之和，一般取確定支架的最低高度時(shí)還應(yīng)考慮到井下的允許運(yùn)輸高度。支架的伸縮比 （2.7）值的大小反映了支架對(duì)煤層厚度變化的適應(yīng)能力，其值越大，說明支架適應(yīng)煤層厚度變化的能力越強(qiáng)，采用單伸縮立柱，值一般為1.6左右。若進(jìn)一步提高伸縮比，需采用帶機(jī)械加長桿的立柱或雙伸縮立柱，其值一般為2.5左右。薄煤層厚度可達(dá)。由于又考慮到煤層厚度較高，初選雙伸縮立柱。2.2.5 中心距和寬度的確定 支架中心距一般等于工作面一節(jié)溜槽長度。目前國內(nèi)外液壓支架中心距大部分采用.大采高支架為提高穩(wěn)定性中心距可采用，輕型支架為適應(yīng)中小煤礦工作面快速搬家的要求，中心距可采用。因此設(shè)計(jì)中預(yù)取1.5m。2.2.6 底座寬度 底座是將頂板壓力傳遞到底板和穩(wěn)固支架的部件。在設(shè)計(jì)支架的底座長度時(shí)，應(yīng)考慮如下諸方面：支架對(duì)底板的接觸比壓要??；支架內(nèi)部應(yīng)有足夠的空間用于安裝立柱、液壓控制裝置、推移裝置和其他輔助裝置；使于人員操作和行走，保證支架的穩(wěn)定性等。通常，掩護(hù)式支架的底座長度取3.5倍的移架步距一個(gè)移架步距為，即左右；支撐掩護(hù)式支架的底座長度取4倍的移架步距，即左右。 2.3 采煤機(jī)、液壓支架和輸送機(jī)的配套2.3.1 采煤機(jī)、液壓支架和輸送機(jī)的配套綜采工作面采煤機(jī)、液壓支架和輸送機(jī)之間在性能參數(shù)、結(jié)構(gòu)參數(shù)、空間尺寸及相互連接等方面，有著嚴(yán)格的配套要求，以保證綜采工作面的最大生產(chǎn)能力和安全生產(chǎn)的要求。（1）生產(chǎn)能力的配套（2）性能配套（3）幾何關(guān)系的配套2.3.2 其他附屬設(shè)備的配套煤層傾角大于時(shí)，采用鏈牽引的采煤機(jī)應(yīng)設(shè)置防滑裝置；當(dāng)傾角大于時(shí)應(yīng)安裝防滑絞車，輸送機(jī)應(yīng)設(shè)置防滑錨固裝置，支架也應(yīng)有防倒防滑和調(diào)架裝置；而對(duì)于大采高工作面設(shè)備，煤層傾角大于時(shí)，即應(yīng)設(shè)防滑裝置。落煤塊度過大時(shí)，工作面轉(zhuǎn)載機(jī)上應(yīng)設(shè)置破碎裝置。本設(shè)計(jì)采用配套 液壓支架 北京煤機(jī)廠 采煤機(jī) 刮板運(yùn)輸機(jī)： 2.4 四連桿機(jī)構(gòu)設(shè)計(jì)2.4.1 四連桿機(jī)構(gòu)的作用四連桿機(jī)構(gòu)是掩護(hù)式支架和支撐掩護(hù)式支架的最重要部件之一。其作用概括起來主要有兩個(gè)：其一是當(dāng)支架由高到低變化時(shí)，借助四連桿機(jī)構(gòu)使支架頂梁前端點(diǎn)的運(yùn)動(dòng)軌跡呈近似雙紐線，從而使支架頂梁前端點(diǎn)與煤壁間距離的變化大大減小，提高了管理頂板的性能；其二是使支架能承受較大的水平力。 為了掌握四連桿機(jī)構(gòu)的設(shè)計(jì)方法，必須正確理解四連桿機(jī)構(gòu)的作用。下面通過四連桿機(jī)構(gòu)動(dòng)作過程的幾何特征進(jìn)一步闡述其作用。這些特征是四連桿動(dòng)作過程的必然結(jié)果。1.支架高度在最大和最小范圍內(nèi)變化時(shí)，頂梁端點(diǎn)運(yùn)動(dòng)軌跡的最大寬度，最好為以下；2.支架在最高位置時(shí)和最低位置時(shí)，頂梁與掩護(hù)梁的夾角和后連桿與底平面的夾角，應(yīng)滿足如下要求：支架在最高位置時(shí)，；支架在最低位置時(shí)，為有利于矸石下滑，防止矸石停留在掩護(hù)梁上，根據(jù)物理學(xué)摩擦理論可知，要求，如果剛和矸石的摩擦系數(shù)，則，為了安全可靠，最低工作位置應(yīng)使為宜。而角主要考慮后連桿底部距底板要有一定距離，防止支架后部冒落巖石卡住后連桿，使支架不能下降。一般取,在特殊情況下需要角度較小時(shí),可提高后連桿下鉸點(diǎn)的高度；3.掩護(hù)梁與頂梁鉸點(diǎn)和瞬心中心間的只限于水平線夾角,滿足。原因是角直接影響支架承受附加力的數(shù)值大小。4.應(yīng)取頂梁前端點(diǎn)運(yùn)動(dòng)軌跡雙紐線向前凸的一段為支架工作段，如圖22所示的h段。圖22所示其原因?yàn)楫?dāng)頂板來壓時(shí)，立柱讓壓下縮，使頂梁有向前移的趨勢(shì)，可防止巖石向后移動(dòng)，又可以使作用在頂梁上的摩擦力指向采空區(qū)。同時(shí)底板防止底座向后移，使整個(gè)支架產(chǎn)生順時(shí)針轉(zhuǎn)動(dòng)的趨勢(shì)，從而增加了頂梁前端的支護(hù)力，防止頂梁前端上方頂板冒落，并且使底座前端比壓減小，防止啃底，有利移架。水平力的合力也相應(yīng)減小，所以減輕了掩護(hù)梁的外負(fù)荷。2.4.2 用優(yōu)選設(shè)計(jì)法設(shè)計(jì)四連桿機(jī)構(gòu)目標(biāo)函數(shù)的確定：令支架由高到低時(shí)，頂梁前端運(yùn)動(dòng)軌跡近似呈斜線；這樣比用直線作為目標(biāo)函數(shù)的雙紐線的上半部分要長。四連桿機(jī)構(gòu)的設(shè)計(jì)通過程序來計(jì)算和驗(yàn)證，程序編制如下所示：Private Sub Command1_Click()Dim h1, h2 As Double 支架最高，最低計(jì)算高度Dim p1 As Double 支架在最高位置時(shí)，頂梁與掩護(hù)梁夾角Dim q1 As Double 支架在最高位置時(shí)，后連桿與底座平面夾角Dim i As Double 后連桿與掩護(hù)梁的比值Dim i1 As Double 前后連桿上鉸點(diǎn)之距與掩護(hù)梁的比值Dim g As Double 掩護(hù)梁長度Dim a As Double 后連桿長度Dim b As Double 前后連桿上鉸點(diǎn)之距Dim f As Double 前連桿上鉸點(diǎn)至掩護(hù)梁上鉸點(diǎn)之距Dim b1, b2, b3 As DoubleDim c As Double 前連桿長度Dim d As Double 前連桿下鉸點(diǎn)高度Dim e As Double 前后連趕下鉸點(diǎn)在底座上的投影距離Dim a1, q2, o1, l As DoubleDim s As Doubleh1 = Val(Text1.Text)h2 = Val(Text2.Text)For p1 = 0.91 To 1.08 Step 0.034For q1 = 1.31 To 1.48 Step 0.034For i = 0.61 To 0.82 Step 0.042For i1 = 0.22 To 0.3 Step 0.02g = h1 / (Sin(p1) + i * Sin(q1)a = i * gb = i1 * gf = g - be1 = g * Cos(p1) - a * Cos(q1)X1 = f * Cos(p1)Y1 = h1 - f * Sin(p1)q2 = 0.436p2 = Atn(Sqr(Abs(g * g - (e1 + a * Cos(q2) 2) / (e1 + a * Cos(q2)X2 = f * Cos(p2)Y2 = b * Sin(p2) + a * Sin(q2)p3 = 3.14 / 2 - Atn(a / g) - Atn(e1 / Sqr(g * g + a * a - e1 * e1)q3 = 3.14 / 2 - p3x3 = f * Cos(p3)y3 = b * Sin(p3) + a * Sin(q3)m = x3 * x3 - X1 * X1 + y3 * y3 - Y1 * Y1n = X2 * X2 - x3 * x3 + Y2 * Y2 - y3 * y3t = 2 * (x3 - X1) * (Y2 - y3) - (y3 - Y1) * (X2 - x3)xc = (m * (Y2 - y3) - n * (y3 - Y1) / tyc = (n * (x3 - X1) - m * (X2 - x3) / tc = Sqr(X1 - xc) 2 + (Y1 - yc) 2)o = c / aIf o 0.9 And o 1.2 Then d = yc e = e1 - xc x4 = e1 + a * Cos(q1) y4 = a * Sin(q1) x5 = e1 y5 = 0 k1 = (Y1 - yc) / (X1 - xc) c1 = Atn(k1) k2 = (y4 - y5) / (x4 - x5) x6 = (k1 * X1 - Y1 - k2 * x4 + y4) / (k1 - k2) y6 = k1 * (x6 - X1) + Y1 l = x6 s = h1 - y6 u = s / l If u 0 And d h1 / 5 And e 45.2前梁強(qiáng)度校核5.2.1 前梁受力情況假定前梁千斤頂缸體內(nèi)徑先按下表標(biāo)準(zhǔn)取為125表5-2506380100110125140(145)200(210)220(230)250則前梁千斤頂?shù)闹瘟椋?（5.2）圖5-1前梁前端受一集中載荷P，其受力圖如上圖所示：前端集中載荷為：在斷面A-A處的彎矩為：前梁做成變斷面箱形結(jié)構(gòu)，A-A斷面如下圖所示：圖5-2 A-A斷面5.2.2 前梁強(qiáng)度計(jì)算(1) 形心位置各板件的計(jì)算數(shù)據(jù)如下表所示：表5-3件號(hào)12345數(shù)量面積形心位置慣性矩11380.511.62169340112317.51027419.5422044891024結(jié)構(gòu)件的形心位置為： （5.3） (2) 慣性矩 （5.4）=+=53790(3) 彎曲應(yīng)力 （5.5）=(4) 安全系數(shù)鋼板材料選取16Mn， （5.6）5.3 主頂梁強(qiáng)度校核 5.3.1 主頂梁受力情況假設(shè)前梁失去作用，主頂梁受一集中載荷，其受力圖如下圖所示：由上面求出為3279.3KN，距離鉸接點(diǎn)1661mm,最大彎矩為圖5-3 主頂梁受力情況圖主頂梁做成等斷面箱式結(jié)構(gòu)，在最大彎矩處的斷面如下圖所示：圖5-45.3.2 主頂梁強(qiáng)度計(jì)算（1）形心位置各板件計(jì)算數(shù)據(jù)如下表所示：結(jié)構(gòu)件的形心位置為： （5.7）=表5-4件號(hào)123456789數(shù)量1139.20.829.7273.62.431.4227.811.91404.8452.211.95268218.8111107.4237.121.25447.7235.221.25166225.921.23804130.411.2914.5(2) 慣性矩 （5.8） (3) 彎曲應(yīng)力 （5.9）(4) 安全系數(shù) 鋼板材料選取16Mn， 5.4 掩護(hù)梁強(qiáng)度校核5.4.1 掩護(hù)梁受力情況由前面已經(jīng)求出在掩護(hù)梁上前后連桿的銷軸處受力為2725.9KN和2096.89KN，其受力圖如下圖所示：圖5-5 掩護(hù)梁受力圖最大彎矩發(fā)生在前連桿處，其值為：最大彎矩處的斷面表示如下圖所示：圖5-65.4.2 掩護(hù)梁強(qiáng)度計(jì)算(1) 形心位置各板件記算數(shù)據(jù)如下表所示：表5-5件號(hào)12345數(shù)量1114215615017518390.64.414.8142717.2673.52960.1249.414.2結(jié)構(gòu)件的形心位置： （5.10）ORIGINAL ARTICLEAn integrated computer-aided decision support systemfor die stresses and dimensional accuracyof precision forging diesNecip Fazil Yilmaz&Omer EyerciogluReceived: 29 January 2007 /Accepted: 14 January 2008 /Published online: 28 February 2008#Springer-Verlag London Limited 2008Abstract Precision forging is a field in which decisionsupport systems can be effectively and widely appliedand depends on knowledge and rules derived from thepast experience of forging die design engineers. Precisecomponents are becoming quite important in attempts toreduce cost and improve reliability. There are thus manyapplication areas in which the rules themselves becomeinherent to the parts or the processes. In forging diedesign, dimensional accuracy is one of the main goals.The load carrying capacity and life of any forged productis greatly affected by its dimensional accuracy. To predictthe precise dimension of the part and determine the diedimension for precision forging, it is necessary to analyzethe factors which affect dimensional accuracy. Dimen-sional evolution of die and product should be analyzed ateach stage of forging. In this study, both radial andtangential stresses are encountered in the determination ofdie stresses since cylindrical workpieces were used. Inorder to sustain dimensional accuracy of the forging die,differences between the forging product and the die insertsuch as elastic die expansion and product contraction arepresented.Keywords Precisionforging.Diestress.Decisionsupportsystem1 IntroductionPrecision forming processes and dimensional accuracy offorged components have a special place in forging. Due toits economical benefits, precision forming is one of themost important goals for metal forming technology toachieve. The higher dimensional accuracy of forged partshas been looked at for precision manufacturing in theforging industry, together with die life. Dimensions of theforged part are likely to be different from that of the diecavity due to the elastic characteristics of the die andworkpiece and thermal influences. Among these features,the elastic behaviour of the tool and work material havegreater influence on the dimensional accuracy 1.Elastic characteristics of the die and workpiece could bevaried according to the shape of the part, even for the samematerials. Therefore, designers should fully recognize theelastic deformation of the die and workpiece for eliminatingtrial-and-error. Many researchers have studied die cavitycompensation experimentally or numerically in search of thebetterdie,dielife,andprocessdesign210. As for numericalstudies, Takshashi and Brebbia 11 analyzed the forging diestress with the boundary element method. Sadeghi and Dean12 studied the dimensional accuracy of precision forgedaxisymmetric components. Eyercioglu 13 and Dean alsostudied design and manufacture of precision gear forging dies.Also, several studies referred to the dimensional accuracy andsome numerical studies such as FEM, upper bound elementaltechnique (UBET), and the slab method were proposed forelastic characteristics of the forging tool 1418.Gerhard and Altan 19 stated that the structural analysis ofthe die and the prediction of stresses and elastic deflections areuseful from die life perspective. Especially in hot forging, dieInt J Adv Manuf Technol (2009) 40:875886DOI 10.1007/s00170-008-1402-zN. F. Yilmaz (*):O. EyerciogluMechanical Engineering Department, University of Gaziantep,27310 Gaziantep, Turkeye-mail: nfyilmazgantep.edu.trstresses, consisting of mechanical contact and thermal stresses,govern die fatigue, surface cracking, and crack growth, andconsequently they influence die life and profitability.The deformation patterns experienced in most formingoperations are very complicated, and thus it is not possibleto describe the patterns in quantitative statements. Thedeformation patterns of the workpiece geometry andmaterial in the forming zone are influenced by a numberof important parameters such as friction condition, lubrica-tion, temperature, velocity, boundary conditions, materialproperties, workpiece, and tool geometry. The optimumdesign of the metal forming process requires the knowledgeof the influences of these parameters as well as theinteraction among these parameters on the process mechan-ics in order to understand a certain metal forming process.In order to obtain the desired geometry and mechanicalproperties, the process parameters must be accurate, welldesigned, and properly controlled 20, 21.The design of forging die, prediction of requiredload, and thus dimensional accuracy can be handled byhighly experienced tool designers using a combinationof accumulated knowledge based on industrial experi-ence. Apart from the mathematical calculations on diestress and forging load, the necessity of the processplanner to take into account the empirical rules andgained knowledge derived from industrial experienceprovides an ideal scenario for the implementation offorging die design 22.2 General die design assumptionDie design is influenced by several factors which will beassociated with the type of product and its shape andindividual circumstances, but chiefly by the strengthrequirements. It should be realized that, with the complexstress distribution existing in a forging die, design in termsof support requirements is not particularly precise. Thesituation arises because, for example, the distribution andmagnitude of radial pressure exerted by the work material isnot known with certainty. In addition, the work materialduring forging of products is moving; therefore, steady stateconditions are not achieved due to the continuouslychanging pressure distribution. But in general it is assumedthat steady state stress conditions are present and there is auniform internal pressure along the whole length of the die23, 24. These assumptions permit calculations based on thetheory of thick-walled hollow cylinders to be carried out.The upper bound elemental technique (UBET) incorpo-rates the advantages of both the upper bound theorem andthe finite element method to provide more accuratepredictions of important parameters such as strain rates,die load, and die cavity filling when compared to the othermethods. UBET is perfect for initial stages of theoptimization algorithms, where it is necessary to reachnear-optimum solutions as quickly as possible.The stresses in dies arise mainly from the high level ofinternal pressure during forging. However, the pressure isnot constant over the whole length of the die. Since it isconcentrated in the portion of the die that is in contact withthe deforming workpiece, the pressure will vary duringforging and the length of the pressurised region will alsochange. The dimension of the forging is different from thedie because of several factors:The die insert is shrink fitted into the outer ring causingan extraction of the die cavity (Ue).In hot forging, the die may be heated prior to forgingand further heated by the hot billet during forging. Thiscauses the die insert to expand (Ut).Contraction occurs during cooling from forging tem-perature to room temperature (Uc).In electrodischarge machining of the die components,spark gap occurs between electrode and workpiece.This decreases the die cavity size (G).As seen in Fig. 1, if the radius of the workpiece isassumed to be equal to the original die radius R0; thus, thefinal radius of the die R4will be:R4 R0 Ue Ut? Uc? G3 Calculation formulae3.1 Calculation of the elastic die expansion (Ue)In order to calculate the changes in workpiece dimensionsdue to elastic deflection of the die, the elasticplasticdeformation of the workpiece has to be considered.Assuming that the workpiece is stressed uniformly by thedie and always remains cylindrical at the maximum forgingR0R1R2R3R4UeUtUcGFig. 1 Half section of a cylindrical forging of die insert 25876Int J Adv Manuf Technol (2009) 40:875886load, the die deflection is elastic and uniform along its axis.Ignoring the friction on workpiecedie interfaces, work-piece dimensions change when the punch load is appliedand removed. Also, changes in workpiece dimensions occurduring ejection 25.In order to calculate the amount of expansion of the dieunder radial pressure, an initially stress-free duplex cylinderis considered. By applying the punch load on theworkpiece, two modes of deformation will occur. First,the workpiece will deform elastically and when the punchpressure becomes equal to the yield stress of the workpiecematerial, plastic deformation starts and simple compressioncontinues until the workpiece touches the die wall. Forcontinuity across the interface, the hoop (tangential) strainsfor insert and shrink ring must be equal at this point,q1 q2.q1Pi1 ?nb2a2?b2a2? 11 ? ud1Ed1Pi1 ? nb2a2? 11 ud1Ed11q2nPic2b2? 11 ? ud2Ed2nPic2b2? ?c2b2? 11 ud2Ed22The subscripts 1 and 2 refer to die insert and shrink ring,respectively. When the maximum load is exerted on theworkpiece, the radial stress will be greater than its yieldstrength. After reaching such a condition, if the punch loadis removed, the die will compress the workpiece plasticallyuntil the radial stress on the workpiece is reduced to twiceits shear yield stress (Sy). By using Trescas yield criterion,the total amount of radial expansion of the workpiece (U) atthe end of this stage can be calculated by:Uaa a21 ? ud1 b21 ud1? 2n2Sy? 2ab2PpEd1b2? a23At the end of the forging process, the punch pressure is zeroand the radial stress (2Sy) is still acting on the workpiece.On ejection, its radius will expand elastically and theamount of recovery (s) can be calculated by assuming acylindrical state of stress (sr sq) and by placing z=0,such that:s 1 ? uwEw2Sya4where Ewand ware the Youngs modulus and Poissonsratio of the workpiece material, respectively. The totalbaTiTpFig. 2 Temperature distribution along the die radius in hot forgingDie Ring azbcabcFig. 4 Die insert and shrink ring dimensionsab0()0 (+)r ()To - Tp=0Ti - Tp= Fig. 3 Radial and tangential stress distributions due to outwardtemperatureInt J Adv Manuf Technol (2009) 40:875886877change in the workpiece dimensions due to elastic dieexpansion is given by:Uea a21 ? ud1 b21 ud1? 2n2Sy? 2ab2PpEd1b2? a21 ? uwEw2Sya53.2 Calculation of the thermal die expansion (Ut)In hot forging, dies are preheated to prevent cracking of thedie components and to reduce the cooling rate of theworkpiece. Some heat is transferred from the workpieceduring forging which further heats the die. The combinationof these two sources of heat causes the die to expand.The temperature distribution along the radius of the diewith a preheat temperature of Tpand bore diameter of Tiisgiven in Fig. 2. The preheat temperature is assumedconstant throughout the die, but the heat transferred fromthe workpiece produces an outward heat flow with radialtemperature gradient. Assuming uniform preheating, the diewall will expand freely. The magnitude of the radialexpansion (Utp) at any radius can be determined as:Utp radTp? Tr?6where Tris room temperature, Tpis preheat temperature, anddis the coefficient of thermal expansion of the die material.The temperature increase on the inner surface of the dieand stress distributions are shown in Fig. 3. Thus, the radialdisplacement at any radius r due to thermal stresses can befound with:Uts?dT3 b ? a? 1 da2b2a b1r 2d? 1r21 ? d b3? a3b2? a2?7Total die expansion (Ut) due to temperature will then be:Ut Utp Uts8 Top Frame Die Geometry Forging Load Geometry Die Assembly Material Parent Frame Fig. 5 General frame structureFriction Flow Stress FORGING LOAD Contour Frame Remove Frame Region Frame DATABASELubricationGoodAveragePoorDryINFERENCE ENGINEFig. 6 Framework for forgingload frame878Int J Adv Manuf Technol (2009) 40:8758863.3 Calculation of the thermal product contraction (Uc)Theamountofshrinkageafterhotformingoperationsdependson the working temperature and coefficient of thermalexpansion of the forged material. Assuming that shrinkagetakes place radially, and the finish forging temperature isuniform, the amount of radial contraction at any radius is:Uc rawTf? Tr?9where Tfis the forging temperature, wis the coefficient ofthermal expansion of the workpiece, and r is the radius of theworkpiece before contraction. In order to achieve closedimensional tolerances on forgings, die dimensions shouldbe closely controlled. From the foregoing it is apparent thatknowledge of the magnitude of the above factors should beobtained before appropriate die and electrode dimensions aredetermined.Using the above analysis, the parameters affecting forgingdimensions were calculated and for a given condition theprofile of the die was determined. A program has been writtento perform these calculations and to create the correctedforging product dimension for die. Die insert and shrink ringdimensions (Fig. 4) are then given in Eqs. 1017.b aQ110c aQ11z b:SyE1K1? Q21?12Q Q1:Q213Q1ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi121 1K1? PPs14Q2 Q1:ffiffiffiffiffiffiK1p15PP PiSydie16K1SydieSyring17Fig. 9 Friction calibration curve in terms of m 27Table 1 Aluminum ring test dataLubricatedDry (ground)Dry (rough)Do1(mm)303030Do2(mm)37.738.538Di1(mm)15.215.215.2Di2(mm)14.813.511.2H1 (mm)101010H2 (mm)5.655.355.3% H43.546.547% D2.6311.1826.3Load (ton)253035m0.250.40.605101520051015DHP(TON)Fig. 7 Disc forging for aluminiumALUMINIUM0501001502000,000,100,200,300,40STRAIN (DH)STRESS(MPa)Fig. 8 Stressstrain curve for aluminiumInt J Adv Manuf Technol (2009) 40:875886879where a is the die insert inner radius, b is the die insertouter radius, c is the shrink ring outer radius, z is theinterference, and Piis the inner pressure.4 General structure of the systemA general structure for building up an inference and controlengine for the decision-support expert system as well as analgorithm for finding a compromise solution for the diestress and dimensional accuracy of the product is achieved.By using an intelligent, knowledge-based object-orientedsystem, high precision manufacture of product has been putinto perspective. Knowledge representation in this workwas structured in the network representation. Parent frames(geometry, forging load, die geometry, die assembly,material) are connected to the top frame. Each parent framealso has child frames. General frame structure is shown inFig. 5.Parent frames are used to describe the general class ofobjects. In a database, the data definition of a recordspecifies how the data is stored so that the database cansearch and sort through the data. To actually enter thevalues into the system, child frames and instances areformed to represent the specific objects. Prediction offorging load has vital importance for the dimensionala b c 4017.53031.1Fig. 10 U-shaped product withdifferent sizes of specimen880Int J Adv Manuf Technol (2009) 40:875886accuracy and die life. This frame has six child frames and itis defined as one of the main frames of the developedsystem (Fig. 6).Contour frame This is the child frame of forging loadparent frame. This frame takes its knowledge from thegeometry parent frame. In order to determine the forgingload, the contour frame is the first frame that is to be fired.The entities are searched to find the inclined lines and arcs.During this process, related rules are fired so that theentities found are inclined line or arc.Remove frame This is the child frame of forging loadparent frame. In this frame, removed entities are stored inthe database. There are two instances. One of them containsthe knowledge about inclined lines and the other containsarcs.Region frame This frame is the child frame of forging loadparent frame. The geometry decomposition is made by theknowledge taken from this frame. Vertical and horizontallines are drawn from the corners to the corresponding line.In this way, rectangular regions are obtained. The knowl-edge about the regions are stored in the database.Friction frame One side of the region contacts one of thematerial, die, or punch. Therefore, each side must bechecked and friction factor must be determined. This frameis used for the determination of sides, whether it contactsthe material, die, or punch.c 2050ab4012.53022.2Fig. 11 T-shaped product withdifferent sizes of specimenInt J Adv Manuf Technol (2009) 40:875886881Lubrication frame This frame takes its knowledge fromfriction frame and adds its own knowledge. This frame hasfour slots: good lubrication, average lubrication, poorlubrication, and no lubrication (dry). These slots arerequired from the user. The entered values are used forthe determination of friction factor for each side of theregion and therefore for all forging products.Flow stress frame Deformation characteristics of eachmaterial are different from the other materials. The flowstress value changes for all deformation conditions.Therefore, this property of the material must be in hand.5 ExperimentationIn the experiments a hydraulic press which has a capacityof 600 kN was used. A graphitewater based lubricant wasused as a lubricant. Great care was taken to ensure that allthe working surfaces were completely and evenly lubricat-ed. As a die insert material, AISI A10 air hardeningmedium alloy cold worked tool steel was used. The tool setcomprised essentially a container, punch, ejector, andbolster.U-shaped, T-shaped, and taper shaped aluminium prod-ucts were forged. Experiments were carried out at roomtemperature. Three different sizes of cylindrical aluminiumbillets were used. Products which have a dimension of40 mm in outside diameter and 20 mm in height wereobtained from stock bars and hollow bars.5.1 Disc forgingA disc forging compression test was carried out to determinethe stress-strain curve for aluminium. To this aim, incrementalcompression was performed and after each loading, reductionof area and corresponding load were calculated and recorded.40123022.32532.1a b cFig. 12 Taper shaped productwith different sizes of specimen882Int J Adv Manuf Technol (2009) 40:875886A reduction in height versus load graphic is shown in Fig. 7,and a stressstrain curve is shown in Fig. 8.In order to determine the friction factor (m), the ringcompression test has been carried out. A flat ring specimenis plastically compressed between two platens. Increasingfriction results in an inward flow of the material anddecreasing friction results in an outward flow of thematerial. For a given percentage of high reduction duringcompression test, the corresponding measurement of theinternal diameter of the test specimen provides a quantita-tive knowledge of the magnitude of the prevailing frictioncoefficient at the die and workpiece interface 26, 27.From this perspective, ring compression test data foraluminum are presented in Table 1. %H and %D valuesFig. 13 a Die stress calculationscreen. b Corrected diedimensionsInt J Adv Manuf Technol (2009) 40:875886883are obtained by the following equations and frictioncoefficient m is found from Fig. 9.%H H1? H2H1*100%D Di1? Di2Di1*1005.2 U-shaped forgingInprecisionforgingoftheproducts,complete fillingofthe dieis regarded as the most important criterion for improving thedimensional accuracy of the forged part. The volume of thepreform should be carefully controlled, otherwise underfillingor overloading of the tools may occur. It can generally be saidthat metal does not flow easily through the corners. Completefilling can be satisfactorily achieved by using appropriateinitial billet geometry.Figure 10 shows the dimensions of the U-shaped forgingproduced from three different sizes of billets by keepingtheir volume constant. The first one was forged from solidcylindrical bar and the product was obtained with 26 tons ofload. The second one (Fig. 10b) was subjected to 55 tons ofload, but the inner side of the specimen could not be filled.In the third one (Fig. 10c) both upsetting and extrusion typemetal deformation exists. In this case the product isobtained with 40 tons o