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Machining process card Product model Part drawing number 1 Product name Bearing seat Part name Support Sum 1 pages No. 1 pages Workshop Procedure number Procedure name Material HT 200 Blank part type Blank dimension Numbers of parts per blank Number of pieces per unit Casting part 360*360*100 1 1 Device name Equipment type Equipment number Numbers of simultaneous processing Milling machine X5030A 1 Fixture number Fixture name Cutting fluid Special fixture No Station appliance number Station appliance name Working hours (minutes) Quasi final Singleton Step Step detials Process equipment Spindle speed Cutting speed Feed Cutting width Feed time Man-hours r/min m/min mm/min mm min basic Auxiliary 1 Milling two side surfaces Milling machine 286 45 183 24 1.6 Sign Number Changed file Signature Date Remark Number Changed file Signature Date Design date Recheck date Audit date Standardized date Jointly sign date 2018.11.02 目錄 目錄 1 序言 2 第1章 零件分析 3 1.1 零件作用 3 1.2 零件的工藝分析 3 第2章 工藝規(guī)程設(shè)計 4 2.1生產(chǎn)類型確定 4 2.2 確定毛坯的制造形式 4 2.3基準(zhǔn)面的選擇 4 2.3 制訂工藝路線 4 2.4機械加工余量、工序尺寸及毛坯尺寸的確定 6 2.5 確定切削用量及基本工時 6 2.5.1粗、精銑φ250前后端面 6 2.5.2銑上端面和右側(cè)端面 8 2.5.3粗、精鏜孔φ180H7 10 2.5.4鉆擴孔φ25 11 2.5.5銑寬槽10mm 13 2.5.6鉆擴6-φ13 13 第3章銑上端面夾具設(shè)計 16 3.1工件自由度分析和定位原理 16 3.3定位誤差的分析 16 3.4切削力及夾緊力的計算 17 3.5夾具設(shè)計及操作的簡要說明 19 結(jié) 論 20 參考文獻 21 序言 近年來，隨著機械制造業(yè)的大速發(fā)展，加工中制造技術(shù)也在不斷發(fā)展，各種機床的應(yīng)用也是越來越廣，各種各樣的零件也隨之要求越來越高。本次設(shè)計針對其撥叉零件進行工藝分析，對此零件制定合理的加工工藝規(guī)程是保證零件的加工質(zhì)量的有效措施。 根據(jù)本次的課題，所列下的基本設(shè)計內(nèi)容包括： 1. 根據(jù) “軸承座”零件圖，進行工藝分析，對零件各表面技術(shù)要求進行分析； 2. 根據(jù)零件制定機械工藝流程； 3. 繪制專用工序的夾具裝配圖； 4. 編寫設(shè)計說明書。 第1章 零件分析 1.1 零件作用 本次的零件為軸承座，軸承座一般是安裝在某個機床上的，此軸承座相應(yīng)的連接孔與相應(yīng)的連接螺桿或者連接轉(zhuǎn)軸連接起來，其中心孔與相應(yīng)的軸上軸承相互配合，隨著轉(zhuǎn)軸的轉(zhuǎn)動，要保證此中心孔與軸有一定的同心效果。 1.2 零件的工藝分析 本次的軸承座零件中要加工的某些表面中，主要包括其上端面和上端面上的寬槽，右下側(cè)端面和右下側(cè)端面上的寬槽，上部寬槽對立的下端面，右側(cè)的寬槽對立的端面，φ250的前后端面等，這些表面特征中φ250的前后端面表面粗糙度要求為Ra6.3，兩部分的寬槽50h11要求也是Ra6.3，除此之外其余各注明的表面粗糙度要求均為Ra12.5，未注明表面粗糙度的均為不加工處理。 孔的特征包括中心基準(zhǔn)上的大圓孔φ180H7，此孔的表面粗糙度要求為Ra1.6，上部寬槽和右下部寬槽上的2-φ25孔表面粗糙度要求為Ra12.5，大端面上6-φ13通孔要求也為Ra12.5。 形位公差要求中上端面與右下端面之間垂直度要求0.12mm，中心大圓孔φ180圓度要求0.008mm，大端面φ250為基準(zhǔn)B，中心大圓孔φ180為基準(zhǔn)C，兩個寬槽相對于B基準(zhǔn)有位置度0.4mm要求，前后大端面相對于C基準(zhǔn)中心有垂直度0.1mm的要求。 第2章 工藝規(guī)程設(shè)計 2.1生產(chǎn)類型確定 零件的生產(chǎn)類型是按照企業(yè)生產(chǎn)的實際情況來進行分類的，它對著零件的工藝規(guī)程的制定有著一定的影響。一般情況下生產(chǎn)類型包括有大批量生產(chǎn)、中批量生產(chǎn)、小批量生產(chǎn)和單件生產(chǎn)等。不同種類的生產(chǎn)類型所對應(yīng)的工藝規(guī)程也是不一樣的的，零件的生產(chǎn)類型也是按照零件的年生產(chǎn)產(chǎn)量和基本的特征來確定的。 本次的軸承座采用的是批量生產(chǎn)，所以考慮生產(chǎn)加工情況就要以批量生產(chǎn)來進行考慮。 2.2 確定毛坯的制造形式 正確的選擇毛坯，對后續(xù)的加工有著很重要的影響，對于毛坯的材料和制造方法，同樣還包括毛坯的制造精度對工件的后續(xù)加工質(zhì)量都有重大的影響。 所以確定好毛坯的制造形式很重要，本次的軸承座考慮為批量生產(chǎn)，根據(jù)零件的形狀確定毛坯為HT200，本次的材料為灰口鑄鐵，需要使用鑄造件來進行毛坯。 2.3基準(zhǔn)面的選擇 零件在加工的時候，一般選擇毛坯上沒有進行加工的表面作為定位基準(zhǔn)的時候叫做粗基準(zhǔn)，經(jīng)過后續(xù)加工后的加工表面作為定位基準(zhǔn)的叫做精基準(zhǔn)。一般來說粗基準(zhǔn)選擇選擇大的、長的、表面特征規(guī)則的、定位位置合適的等方式來進行選擇。 一般都要考慮開始加工的粗基準(zhǔn)，基本上粗基準(zhǔn)可以選擇不加工的外形特征，本次的軸承座零件顯然來看選擇大端面都可以作為粗基準(zhǔn)的選擇。精基準(zhǔn)選擇需要選擇加工后的基本基準(zhǔn)特征，本次的中心大孔φ180加工后可以作為精基準(zhǔn)的使用。 2.3 制訂工藝路線 針對本次的軸承座零件，本次確定制定兩種工藝路線方案，并加以比較擇優(yōu)選擇。如下 （1）工藝方案一 工序一：鑄造毛坯 工序二：粗、精銑φ250前端面 工序三：粗、精銑φ250后端面保證尺寸100mm 工序四：粗、精鏜中心孔φ180H7到位 工序五：銑上部端面及右側(cè)端面 工序六：銑上部下端面和右側(cè)下端面保證兩部分尺寸50mm 工序七：銑上部端面和右側(cè)端面上的寬槽保證尺寸50mm 工序八：鉆、擴2-φ25孔 工序九：鉆6-φ13孔 工序十：去毛刺倒棱角 工序十一：檢驗入庫 （2）工藝方案二 工序1：鑄造毛坯 工序2：粗、精車φ250前端面 工序3：粗、精車φ250后端面保證尺寸100mm 工序4：粗、精車中心孔φ180H7到位 工序5：銑上部對應(yīng)的下端面和右側(cè)下端面保證尺寸50mm 工序6：銑上部和右側(cè)端面上的寬槽50mm 工序7：鉆擴2-φ25孔 工序8：鉆大端面上6-φ13孔 工序9：去毛刺倒棱角 工序10：檢驗入庫 （3）工藝方案的比較分析 我們來分析如上對該軸承座的零件的兩個工藝方案的比較分析。 方案二中采用的是對大端面及大中心孔使用車床來進行加工，車床加工固然可以，但是本次的零件體積較大，在車床加工的時候由于該零件也不是類似于回轉(zhuǎn)體曲面的形狀，這樣就要考慮使用工裝夾具，此零件體積較大，上車床加工既要選擇大車床也要選擇較大的工裝夾具，對安裝時間和使用機床的成本都是大大提高，所以不采用方案二，最終選擇方案一為本次的最終加工方案。 2.4機械加工余量、工序尺寸及毛坯尺寸的確定 根據(jù)軸承座的材料毛坯采用的是HT200灰口鑄鐵毛坯，以此來確定各加工表面的加工余量、工序尺寸及毛坯尺寸。 1、φ250前后端面 查詢《機械制造技術(shù)基礎(chǔ)課程設(shè)計指導(dǎo)教程》表2-24的平面加工余量，本次的軸承座φ250前后端面的平面的表面粗糙度要求為Ra6.3，要經(jīng)過粗、半精加工達到完成，厚度范圍屬于50~100mm，得知粗加工余量單邊為2.5mm，半精加工余量單邊為1.5mm。這樣φ250前后端面的毛坯尺寸為100+4+4=108mm。 2、孔（） 查詢表2-20本次的軸承座中心孔φ180在粗鏜之前的孔直徑最大可以是φ170mm，本次考慮使用一定的加工余量就按照φ160孔的毛坯尺寸制造。 2.5 確定切削用量及基本工時 2.5.1粗、精銑φ250前后端面 （1）粗銑 被加工零件材料：HT200 機床選用：選用立式銑床X53K 刀具選用：選用套式端面銑刀，直徑φ100mm，齒數(shù)為Z=10 銑削深度： 每齒進給量：根據(jù)《機械制造技術(shù)基礎(chǔ)課程設(shè)計指導(dǎo)教程》表5-5，取 銑削速度：參照《機械制造技術(shù)基礎(chǔ)課程設(shè)計指導(dǎo)教程》表5-11，取 機床主軸轉(zhuǎn)速： 進給量： 工作臺每分進給量： 根據(jù)《機械制造技術(shù)基礎(chǔ)課程設(shè)計指導(dǎo)教程》表5-47銑削的基本時間計算，本次為套式面銑刀，銑削的基本工時計算公式如下 式中 工件的銑削長度 刀具切入長度： 式中 為銑削的公稱寬度，查詢表5-11得出本次的面銑刀直徑100mm的銑削寬度為48mm ：銑刀直徑為100mm 代入上式后得出 ，得出 刀具切出長度：取，本次選擇3mm ：工作臺水平進給量 走刀次數(shù)為1 機動時間 （2）精銑φ250端面 被加工零件材料：HT200 機床選用：選用立式銑床X53K 刀具選用：選用套式端面銑刀，直徑φ100mm，齒數(shù)為Z=10 銑削深度： 每齒進給量：根據(jù)《機械制造技術(shù)基礎(chǔ)課程設(shè)計指導(dǎo)教程》表5-5，取 銑削速度：參照《機械制造技術(shù)基礎(chǔ)課程設(shè)計指導(dǎo)教程》表5-11，取 機床主軸轉(zhuǎn)速： 進給量： 工作臺每分進給量： 根據(jù)《機械制造技術(shù)基礎(chǔ)課程設(shè)計指導(dǎo)教程》表5-47銑削的基本時間計算，本次為套式面銑刀，銑削的基本工時計算公式如下 式中 工件的銑削長度 刀具切入長度： 式中 為銑削的公稱寬度，查詢表5-11得出本次的面銑刀直徑100mm的銑削寬度為48mm ：銑刀直徑為100mm 代入上式后得出 ，得出 刀具切出長度：取，本次選擇3mm ：工作臺水平進給量 走刀次數(shù)為1 機動時間 2.5.2銑上端面和右側(cè)端面 被加工零件材料：HT200 機床選用：選用立式銑床X53K 刀具選用：選用套式端面銑刀，直徑φ50mm，齒數(shù)為Z=8 銑削深度： 每齒進給量：根據(jù)《機械制造技術(shù)基礎(chǔ)課程設(shè)計指導(dǎo)教程》表5-5，取 銑削速度：參照《機械制造技術(shù)基礎(chǔ)課程設(shè)計指導(dǎo)教程》表5-11，取 機床主軸轉(zhuǎn)速： 進給量： 工作臺每分進給量： 根據(jù)《機械制造技術(shù)基礎(chǔ)課程設(shè)計指導(dǎo)教程》表5-47銑削的基本時間計算，本次為套式面銑刀，銑削的基本工時計算公式如下 式中 工件的銑削長度 刀具切入長度： 式中 為銑削的公稱寬度，查詢表5-11得出本次的面銑刀直徑50mm的銑削寬度為24mm ：銑刀直徑為50mm 代入上式后得出 ，得出 刀具切出長度：取，本次選擇3mm ：工作臺水平進給量 走刀次數(shù)為1 機動時間 2.5.3粗、精鏜孔φ180H7 （1）粗鏜孔至φ179 選擇高速鋼鏜刀 粗加工吃刀量選擇為 進給量查詢參照《機械制造技術(shù)基礎(chǔ)課程設(shè)計指導(dǎo)教程》表5-36，取 切削速度參照表5-1，得 機床主軸轉(zhuǎn)速： 切削的時間按照下式計算 式中 L：切削的長度按照孔徑179mm ：工件的實際長度為179mm ：粗加工選擇為2mm 主偏角，那么 ，本次選取4mm 進給次數(shù)為 （2）精鏜 選擇高速鋼鏜刀 進給量查詢參照《機械制造技術(shù)基礎(chǔ)課程設(shè)計指導(dǎo)教程》表5-1，取 切削速度參照表5-1，得 機床主軸轉(zhuǎn)速： 切削的時間按照下式計算 式中 L：切削的長度按照孔徑180mm ：工件的實際長度為180mm 主偏角，那么 ，本次選取4mm 進給次數(shù)為 2.5.4鉆擴孔φ25 （1）鉆孔至φ20 進給量：根據(jù)《機械制造技術(shù)基礎(chǔ)課程設(shè)計指導(dǎo)教程》表5-22，取 切削速度：參照《機械制造技術(shù)基礎(chǔ)課程設(shè)計指導(dǎo)教程》表5-22，取 機床主軸轉(zhuǎn)速：， 鉆孔的切削時間計算按照如下式 式中 被切削層長度：本次按照切削的深度為 刀具切入長度： ：錐柄麻花鉆頭的前角，一般為118度，本次按照120度計算 刀具切出長度：，本次是鉆通孔，按照3mm 走刀次數(shù)為1 機動時間： （2）擴孔至φ25 進給量：根據(jù)《機械制造技術(shù)基礎(chǔ)課程設(shè)計指導(dǎo)教程》表5-25，取 切削速度：參照《機械制造技術(shù)基礎(chǔ)課程設(shè)計指導(dǎo)教程》表5-26，取 機床主軸轉(zhuǎn)速：， 擴孔的切削時間計算按照如下式 式中 被切削層長度：本次按照切削的深度為 刀具切入長度： ：錐柄麻花鉆頭的前角，一般為118度，本次按照120度計算 刀具切出長度：，本次是鉆通孔，按照3mm 走刀次數(shù)為1 機動時間： 2.5.5銑寬槽10mm 機床：銑床X53K 刀具：高速鋼鍵槽銑刀 齒數(shù) 進給量：根據(jù)《機械制造技術(shù)基礎(chǔ)課程設(shè)計指導(dǎo)教程》表5-15，取 切削速度：參照《機械制造技術(shù)基礎(chǔ)課程設(shè)計指導(dǎo)教程》表5-15，取 機床主軸轉(zhuǎn)速：， 銑鍵槽的方式來計算，銑削的基本工時計算公式如下 式中 工件的切削長度 刀具切入長度：，按照25mm計算得知 刀具切出長度：取，本次選擇2mm ：工作臺水平進給量 機動時間 2.5.6鉆擴6-φ13 （1）鉆孔至φ10 進給量：根據(jù)《機械制造技術(shù)基礎(chǔ)課程設(shè)計指導(dǎo)教程》表5-22，取 切削速度：參照《機械制造技術(shù)基礎(chǔ)課程設(shè)計指導(dǎo)教程》表5-22，取 機床主軸轉(zhuǎn)速：， 鉆孔的切削時間計算按照如下式 式中 被切削層長度：本次按照切削的深度為 刀具切入長度： ：錐柄麻花鉆頭的前角，一般為118度，本次按照120度計算 刀具切出長度：，本次是鉆通孔，按照3mm 走刀次數(shù)為1 機動時間： （2）擴孔至φ13 進給量：根據(jù)《機械制造技術(shù)基礎(chǔ)課程設(shè)計指導(dǎo)教程》表5-25，取 切削速度：參照《機械制造技術(shù)基礎(chǔ)課程設(shè)計指導(dǎo)教程》表5-26，取 機床主軸轉(zhuǎn)速：， 擴孔的切削時間計算按照如下式 式中 被切削層長度：本次按照切削的深度為 刀具切入長度： ：錐柄麻花鉆頭的前角，一般為118度，本次按照120度計算 刀具切出長度：，本次是鉆通孔，按照3mm 走刀次數(shù)為1 機動時間： 第3章銑上端面夾具設(shè)計 3.1工件自由度分析和定位原理 本次對軸承座上端面進行專用夾具的設(shè)計，采用的定位原理方法借助于六點定位原則方式，六點定位原則的基本方式圖如下 圖3-1六點定位原則 本次考慮以φ250大端面作為主要定位基準(zhǔn)限制三個自由度，考慮使用四個支承釘?shù)亩ㄎ辉绞?，其中三個支承釘作為定位的考慮限制其三個自由度，另外一個起到加強的作用，對自由度限制不考慮。 右側(cè)的端面限制其兩個自由度，采用的定位元件為支承釘，同樣下小部分的端面也采用的是支承釘定位元件限制一個自由度，這樣整個裝置的定位原則方式就是基本按照圖3-1六點定位原則的原始方法圖相同了。 3.3定位誤差的分析 本次的一個定位就是右側(cè)端面和下端面采用的是相互垂直的兩個平面，如下可以進行對其的定位誤差進行分析 圖3-1兩個垂直平面定位 通過兩個垂直平面定位的公差分析計算如下式: 本次的選擇為90度，定位的側(cè)邊兩個尺寸和分別為30和35，代入此式后得出 定位誤差占加工公差的 ，能保證加工要求。 該定位方案能滿足加工的精度要求，定位方案是合理的。 3.4切削力及夾緊力的計算 （1）切削力計算 本次采用的是銑端面，銑削力按照銑削如下公式計算 銑刀為圓柱銑刀、立銑刀、盤銑刀、鋸片銑刀、角度銑刀、半圓成形銑刀 式中 ：切削力 ：使用高速鋼銑刀銑削的時候，工件材料及銑刀類型的系數(shù)查表選取 ：銑削深度 ：每齒進給量 ：銑刀直徑 ：銑削寬度 ：銑刀每分鐘的轉(zhuǎn)速 ：銑刀的齒數(shù) ：用高速鋼銑削的時候，工件材料機械性能不同的修正系數(shù)。對于結(jié)構(gòu)鋼、鑄鋼為， ：工件材料的抗拉強度MPa =2451N （2）夾緊力的計算 由于本次對工件的夾緊是對工件的底面定位的上方進行夾緊。根據(jù)《機床夾具設(shè)計手冊 第三版》中檔其他切削分力較小的時候，僅需要較小的夾緊力防止工件在加工過程中產(chǎn)生振動和轉(zhuǎn)動。 式中 ：原動力 ：實際所需的夾緊力 ：螺桿端部與工件間的當(dāng)量摩擦半徑 ：螺紋中徑之半 ：螺紋升角 ：螺桿端部與工件間的摩擦角 ：螺旋副的當(dāng)量摩擦角 ：機械效率 計算方式如下： Wk =2451N r' = 3 φ1 = 3.2 rz = 6.9 α = 2.5 φ'2 = 9.83 L = 43 η0 = 0.88 l = 21 計算結(jié)果 = 2945N 3.5夾具設(shè)計及操作的簡要說明 本次的夾具是銑上端面夾具，由于工件的特征表面此銑面雖然是兩個不同位置，但是經(jīng)過工件的旋轉(zhuǎn)后此銑面的特征是完全相同，可以借助一個工裝夾具來實現(xiàn)可以加工兩個不同的位置，在銑完一個特征后，需要拆卸下壓緊在工件大端面上的螺母，然后將右側(cè)的活動支承塊拿開，就可以將此工件拿下，然后將工件翻轉(zhuǎn)，這樣可以對另外一個特征在使用此同種夾具上進行操作，這樣節(jié)省了工件安裝時間，方便操作。 整個夾具的裝配圖如下 圖3-3銑上端面專用夾具裝配圖 結(jié) 論 軸承座是一個基本的零件，其性能直接影響到連接的軸及軸承零件的整體加工效果，進而影響到加工零件的精度關(guān)系。因此，本次的研究課題后軸承座的零件工藝分析很好得結(jié)合課本所學(xué)知識，并應(yīng)用機械加工制造工藝學(xué)，對此零件進行工藝分析和最終夾具的設(shè)計。 本次設(shè)計的軸承座的工藝規(guī)程設(shè)計及主要工序的夾具設(shè)計得出的幾點結(jié)論。 1、首先分析零件的工藝性，并制定零件的工藝規(guī)程，制定零件的工藝過程，熟悉這類零件的工藝規(guī)程的設(shè)計方法。 2、制定好零件的工藝后對其中的主要工序進行分析，選擇一個其中的主要工序作為夾具設(shè)計的任務(wù)。本次選擇的是銑大端面夾具設(shè)計。 3、銑上端面夾具使我熟悉掌握了此類零件的六點定位原則方式，熟悉使用支承釘?shù)亩ㄎ辉x擇，熟悉端面的壓板對表面進行的螺旋壓緊方式。 參考文獻 [1]李益民主編 《機械制造工藝簡明手冊》 機械工業(yè)出版社，2003； [2]周開勤主編 《機械零件手冊》 高等教育出版社，2006 [3]吳宗澤主編 《機械零件設(shè)計手冊》 機械工業(yè)出版社，2003 [4]陳宏均主編 《實用機械加工工藝手冊》 機械工業(yè)出版社，2005 [5]毛倩德主編 《袖珍機械設(shè)計師手冊》機械工業(yè)出版社，2005 [6] 《機床夾具設(shè)計手冊》第二版，上?？茖W(xué)技術(shù)出版社，1994,12 21 Course No.: Student No.： Course Project: Manufacturing Technology Design Title The machining process and fixture design of the support Student Name Wang Ting Class Mechanical Design Engineering and Automation (English)151 Student No. 201535510120 Department/College Engineering Institute Advisor Dr. Wang Date Nov.06 2018 II Course Project: Manufacturing Technology Design Design Instruction on Course Project: Manufacturing Technology Design Design Assignment Title：Design of special fixture for upper end face of bearing block Content： 1) Manufacturing process planning sheet 1 2) Assembly drawing of Fixture or jig 1 3) Detail drawing 1 / part 4) Design Instruction 1 5) Assembly animation 1 Course Project: Manufacturing Technology Design Contents Abstract 3 Chapter 1 Preface 4 Chapter 2 Process analysis of workpiece 4 2.1 Function of workpiece 4 2.2 Process analysis of parts 5 Chapter 3 Blank part determination 6 Chapter 4 Manufacturing process planning 7 4.1 Selection of positioning reference 7 4.2 Making process route 7 Chapter 5 Cutting parameters and labor-hour 10 5.1 Determination cutting parameters and Time quota calculation 10 Chapter 6 Jig/Fixture design 13 6.1 Design duty 13 6.2 Locating datum 13 6.3 Fixture Degree of freedom analysis 14 Chapter 7 Fixture design and usage of equipment 15 7.1 Fixture design 15 7.1.1 locating and clamping of the workpiece 15 7.1.2 Analysis of location errors 16 7.2 Calculation of cutting force and clamping force 17 7.2.1 Calculation of cutting force 17 7.2.2 Calculation of clamping force 18 7.3 Brief description of fixture design and operation 19 Chapter 8 Conclusion 21 References 22 Thanks 22 Abstract The design course is a teaching link on the basis of finishing the course Technology of Mechanical Manufacture (including machine tool fixture design)and most of the specialized courses. It is a design of special fixture mainly for the processing technic of parts and some procedure processing of parts. From the process of the parts, it mainly analyses what problems should pay attention in the processing, and what methods and process should be adopted to ensure the accuracy and raise labor productivity. As far as special clamp is concerned, good fixture design can improve product productivity, accuracy, reduce costs and so on, and can also expand the scope of use of machine tools, so that improve the production efficiency and reduce the costs under the premise of ensuring accuracy. This design enables us to apply the basic theory of manufacturing technology, combining with practical knowledge gained from production practice, and analyze and solve process problems independently. Besides, it enables us to master the ability to design a process specification for a moderately complex part (shell) and the knowledge of the basic principles and methods of fixture design. This design is also a practice shot of drawing up jig design plan, completing jig structure design ability, being familiar with and using relevant manuals, charts and other technical data and writing technical documents and other basic skills, which lays a good foundation for future graduate design and future work. Due to limited capacity, lack of experience, there are many inadequacies in the design, I hope the teacher will be more advice. Key words: process planning, design, special fixture Chapter 1 Preface In recent years, with the rapid development of machinery manufacturing industry, manufacturing technology in processing is also developing continuously, and the application of various machine tools is becoming more and more extensive, and various parts are also increasingly demanding. This design carries on the technological analysis to its fork parts, and formulates the reasonable processing procedure for this part is an effective measure to guarantee the processing quality of the parts. According to this topic, the basic design contents include: 1. According to the "bearing seat" part drawing, process analysis is carried out, and the technical requirements of each surface of the part are analyzed. 2. According to element formulate the mechanical process. 3. Draw up the fixture assembly drawing of the special process. 4. Write design instructions. Chapter 2 Process analysis of workpiece 2.1 Function of workpiece This time, the part is the bearing seat. The bearing seat is usually installed on a machine tool. The corresponding connecting hole of the bearing seat relates to the corresponding connecting screw or the connecting shaft. The central hole and the corresponding bearing on the shaft cooperate with each other. With the rotation of the shaft, it is necessary to ensure that the central hole and the shaft have a certain concentric effect. 2.2 Process analysis of parts Some surfaces to be machined in this bearing seat parts mainly include the wide grooves on the upper end face and the upper end face, the wide grooves on the right lower end face and the right lower end face, the opposite lower end face of the upper wide groove, the opposite end face of the right wide groove, and the front and rear end face of the φ250. The surface features of the front and back face of the φ250 are thick. The roughness requirement is Ra6.3, and the wide groove 50h11 requirement of the two parts is Ra6.3. In addition, the other specified surface roughness requirements are Ra12.5, and the unspecified surface roughness requirements are all non-processed. The characteristics of the hole include the large circular hole φ180H7 on the center datum. The surface roughness requirement of the hole is Ra1.6, the surface roughness requirement of the 2-φ25 hole on the upper wide groove and the right lower wide groove is Ra12.5, and the through hole requirement of the 6-φ13 hole on the large end face is Ra12.5. In the form tolerance requirements, the verticality between the upper end face and the lower right end face is 0.12 mm, center large circle hole φ180 degrees roundness requirement 0.008mm, Large end faceφ250 is the base B. Center large circular hole φ180 is the base C. Two wide grooves have positional 0.4mm requirements relative to the B datum. The front and rear faces have the requirement of perpendicularity 0.1mm relative to the C datum center. Chapter 3 Blank part determination Choosing the right blank has a very important impact on the subsequent processing. It also has a significant impact on the material and manufacturing method of the blank, as well as the manufacturing accuracy of the blank on the subsequent processing quality of the workpiece. Therefore, it is very important to determine the manufacturing form of the blank. The bearing seat is considered to be mass production. According to the shape of the parts, the blank is HT200. The material of this time is grey cast iron. Castings are needed for the blank. Chapter 4 Manufacturing process planning 4.1 Selection of positioning reference When parts are processed, it is generally called rough datum when the surface which is not processed on the blank is chosen as the positioning datum, and precise datum when the processed surface is used as the positioning datum after subsequent processing. Generally speaking, rough datum selection chooses large, long, regular surface features, appropriate location and other ways to select. Generally, we must consider the rough datum of starting processing. Basically, the rough datum can choose the shape characteristics of the non-processing. Obviously, the bearing seat parts can be chosen as the rough datum when choosing the large end face. Fine benchmark selection needs to select the basic benchmark characteristics after processing. The center hole 180 can be used as fine benchmark after processing. 4.2 Making process route Aiming at the bearing seat parts, this paper determines two process routes, and compares and chooses the best one. as follows: Process one: casting blank Process two: rough and fine milling 250 front end face. Process three: rough and fine milling 250 100mm, ensure the size of the end face. Process four: coarse and fine boring center hole 180H7 in place. Process five: milling the upper end and the right side. Process six: milling upper and lower ends and lower right sides to ensure two parts size 50mm Process seven: milling the upper end and wide groove on the right side face to ensure the size 50mm Process eight: drill and expand 2- 25 holes. Process nine: drill 6- 13 holes. Process ten: deburring chamfering Process Eleven: Inspection and warehousing Preliminary processing procedures are as follows: Operation number Contents of working procedures Equipment Tools 10 Casting blank Sand mould Sand mould manufacturing equipment 20 Milling the bottom surface milling machine Facing cutter 30 Milling the upper surface milling machine Facing cutter 40 Milling two side surfaces milling machine Milling tool, Carbide chip 50 Milling groove side milling machine Milling tool, Carbide chip 60 Drilling holes of the sides surface Porous group drilling machine Drilling bit M24(through the wall of shell and distribute even) 70 1.Boring bearing holes roughly(φ180mm) Boring lathe Rough boring tool 2.Chamfering Rose reamer 80 Finishing boring bearing holes Boring lathe Composite boring tool 90 Milling inner small end face Milling machine Milling tool Carbide chip 100 Drilling holes of the infront surface Numerical control milling machine Drilling bit M12(through the wall of shell and distribute even) 110 Curettage cavity Upright drill hobbing 120 Wash Cleaning machine 130 Test Checkout console Technics card of machining process can be seen on the appendix. Chapter 5 Cutting parameters and labor-hour 5.1 Determination cutting parameters and Time quota calculation Operation 40 Milling two side surfaces Machined part material: HT200 Machine tool selection: vertical milling machine X53K Selection of tools: sleeve end mill, diameter 50mm, tooth number Z=8. Milling depth: ： Feed per tooth ：According to table 1, get Table 1 Milling speed ：According to table 2，get Table 2 Spindle speed of machine tool: ：， Feed rate ： Worktable feed per minute ： According to the basic time calculation of milling in Table 5-47 of the Course Design Guidance Course of Machinery Manufacturing Technology, this is a sleeve face milling cutter. The basic time calculation formula of milling is as follows. In this formula, Milling length of workpiece: Tool cut in length： In this formula, the nominal width of milling is shown in table 5-11. The width of the face milling cutter diameter 50mm is 24mm. ：milling cutter diameter 50mm Bring these two values into the formula. Can get ，and Cutting length of cutting tool：get ，this time we choose 3mm. Horizontal feed of worktable ： Number of knives Maneuver time Chapter 6 Jig/Fixture design In order to improve labor productivity, guarantee the quality of processing and reduce the intensity of labor, special jigs should be designed when machining the parts. 6.1 Design duty The location mode of milling two side surfaces is easy, but it still needs to limit six degrees of freedom. In order to ensure technical requirements, the key is to find the positioning datum. At the same time, we should consider how to increase labor productivity and reduce the intensity of labor. 6.2 Locating datum The design of the special fixture for the upper end face of the bearing seat is carried out in this paper. The positioning principle method adopted is based on the six-point positioning principle. The basic schematic diagram of the six-point positioning principle is as follows. 6.3 Fixture Degree of freedom analysis In this paper, the main positioning datum of 250 is used to limit three degrees of freedom. Four supporting nails are used as positioning elements. Three supporting nails are used as positioning elements to limit three degrees of freedom. The other one plays a strengthening role and does not consider the limitation of freedom. The right end face restricts its two degrees of freedom. The supporting pin is used as the positioning element, and the lower part of the end face also uses the supporting pin positioning element to restrict one degree of freedom. So the positioning principle of the whole device is basically the same as the original method diagram according to the six-point positioning principle. Chapter 7 Fixture design and usage of equipment 7.1 Fixture design The fixture is as followed. 7.1.1 locating and clamping of the workpiece In this paper, the main positioning datum of 250 is used to limit three degrees of freedom. Four supporting nails are used as positioning elements. Three supporting nails are used as positioning elements to limit three degrees of freedom. The other one plays a strengthening role and does not consider the limitation of freedom. The right end face restricts its two degrees of freedom. The supporting pin is used as the positioning element, and the lower part of the end face also uses the supporting pin positioning element to restrict one degree of freedom. So the positioning principle of the whole device is basically the same as the original method diagram according to the six-point positioning principle. 7.1.2 Analysis of location errors One of the positioning methods of this time is that the right end and the lower end are two perpendicular planes. The positioning errors can be analyzed as follows. Through two vertical plane positioning tolerance analysis, the following formula is calculated. The is selected at 90 degrees. The two sizesandof the side of the positioning are 30 and 35, respectively. After substituting this formula, we can get the result The positioning error accounts for sixteen percent of the machining tolerance, which ensures the machining requirements. The positioning scheme can meet the accuracy requirements of the machining, and the positioning scheme is reasonable. 7.2 Calculation of cutting force and clamping force 7.2.1 Calculation of cutting force The milling end is adopted, and the milling force is calculated according to the following formula. The milling cutter is cylindrical milling cutter, vertical milling cutter, disc milling cutter, saw blade milling cutter, angle milling cutter, semicircle shaped milling cutter. In this formula, ：cutting force ：When using high speed steel milling cutter, select the coefficient of workpiece material and milling cutter type. ：Milling depth ：Feed per tooth ：Milling cutter diameter ：Milling width ：Milling cutter speed per minute ：Tooth number of milling cutter ：When the high-speed steel is milling, the modification coefficient of the mechanical properties of the workpiece material is different. For structural steel, cast steel is ， ：Tensile strength of workpiece materials MPa =2451N 7.2.2 Calculation of clamping force Because the clamping of the workpiece is clamped above the bottom of the workpiece. According to the third edition of the "Machine Tool Fixture Design Manual", when the other cutting forces in the middle are small, only a small clamping force is needed to prevent the vibration and rotation of the workpiece in the process of processing. In this formula, ：Prime motivity ：Actual clamping force required ：Equivalent friction radius between end screw and workpiece ：Half of thread diameter ：Thread lift angle ：Friction angle between screw end and workpiece ：Equivalent friction angle of helix pair ：Mechanical efficiency The calculation is as follows： Wk =2451N r' = 3 φ1 = 3.2 rz = 6.9 α = 2.5 φ'2 = 9.83 L = 43 η0 = 0.88 l = 21 Calculation results = 2945N 7.3 Brief description of fixture design and operation The fixture of this time is the fixture for milling the upper face. Although the feature surface of the workpiece is two different positions, the feature of the milling face is exactly the same after the workpiece is rotated. Two different locations can be machined by means of a fixture. After milling a feature, it needs to be disassembled and pressed down. The nut on the large end face of the workpiece, and then the movable supporting block on the right side is removed, the workpiece can be taken down, and then the workpiece can be turned over, so that another feature can be operated on the same fixture, thus saving the installation time of the workpiece and facilitating the operation. The assembly drawings of the whole fixture are as follows Chapter 8 Conclusion Bearing seat is a basic part, its performance directly affects the overall processing effect of the connecting shaft and bearing parts, and then affects the precision relationship of the processing parts. Therefore, the research topic of the rear bearing seat parts process analysis is very good in combination with the knowledge learned in textbooks, and the application of mechanical processing manufacturing technology, process analysis of this part and the final fixture design. Several conclusions are drawn from the design of the technological process of the bearing block and the fixture design of the main process. 1. Firstly, the technological characteristics of the parts are analyzed, and the technological rules of the parts are formulated, the technological process of the parts is formulated, and the design method of the technological rules of such parts is familiar with. 2. After making the process of the parts, the main process is analyzed, and one of the main processes is chosen as the task of fixture design. This choice is the milling end fixture design. 3. Milling the upper end fixture makes me familiar with the six-point positioning principle of such parts, the selection of positioning elements using supporting nails, and the screw pressing method of the end plate on the surface. References [1]李益民主編 《機械制造工藝簡明手冊》 機械工業(yè)出版社，2003； [2]周開勤主編 《機械零件手冊》 高等教育出版社，2006 [3]吳宗澤主編 《機械零件設(shè)計手冊》 機械工業(yè)出版社，2003 [4]陳宏均主編 《實用機械加工工藝手冊》 機械工業(yè)出版社，2005 [5]毛倩德主編 《袖珍機械設(shè)計師手冊》機械工業(yè)出版社，2005 [6] 《機床夾具設(shè)計手冊》第二版，上?？茖W(xué)技術(shù)出版社，1994,12 Thanks Through this fixture design course, I learned the whole process of bearing seat processing, SolidWorks drawing skills, understand the necessary process and requirements of mechanical processing. Thank you, Mr. Wang Linlin, for teaching.