【正文】 illar industries which show a nation’s development of technology and society. Both traditional and burgeoning industries can’t be separated from verities of mechanical equipment. This disquisition had just selected such a task— to study the machining craft and the fixture for heavy boring shafting bearing holes of Dongfanghong the state of quality and quantity of objects (such as raw materials, semifinished product, ponent or assembly) changes directly in the process is called craft process, such as blank manufacturing, machining, heat treatment, assembly and so on all is called process. In the aspect of machining craft, part drawing and the technological request were thought over， with the help of some information about the machining craft of parts such as boxes it is arranged to produce the part in eighteen steps which include the information on what means to use， which machine tools, what fixtures, assist tools and measure tools needed in each step. Then selected datum plane for each step, studied out orientation and clamping scheme for each step. in the aspect of fixture designing, I had designed a set of fixture for the heavy boring of the shafting bearing holes. After some analyzing and calculating. Keyword: Gearbox casing, Technics process, Working procedure 75 拖拉機(jī)變速箱機(jī)械加工工藝規(guī)程設(shè)計(jì) III目 錄 摘 要 .......................................................................................................................................... I ABSTRACT ............................................................................................................................ II ...................................................................................................................................... 1 機(jī)械制造行業(yè)的地位和發(fā)展 ..................................................................................... 1 設(shè)計(jì)的選題意義 .......................................................................................................... 1 設(shè)計(jì)的主要內(nèi)容和目的 ............................................................................................. 2 本章小結(jié) ..................................................................................................................... 2 ............................................................................................................... 3 零件的作用 ................................................................................................................. 3 零件的工藝分析 ......................................................................................................... 3 技術(shù)要求 ...................................................................................................................... 3 計(jì)算生產(chǎn)綱領(lǐng) ............................................................................................................. 4 計(jì)算生產(chǎn)節(jié)拍 ............................................................................................................. 4 3 毛坯的選擇 ........................................................................................................................ 4 確定毛坯的制造形式 .................................................................................................. 4 毛坯的選擇 .................................................................................................................. 4 毛坯的尺寸和公差 ..................................................................................................... 4 確定機(jī)械加工余量 ...................................................................................................... 6 毛坯圖的繪制 ............................................................................................................. 7 .................................................................................................................... 8 工藝路線(xiàn)的安排 ................................................................................................... 8 工件的時(shí)效處理 .............................................................................................. 8 安排加工工藝的順序時(shí)應(yīng)先面后孔 .............................................................. 8 、粗、精加工階段要分開(kāi) ................................................................................ 8 基準(zhǔn)的選擇 .............................................................................................................. 8 粗基準(zhǔn)的選擇 ................................................................................................... 8 精基準(zhǔn)的選擇 .................................................................................................. 9 制定工藝路線(xiàn) ........................................................................................................ 9 .................................................................................. 11 工序 20：銑四個(gè)定位平面 ....................................................................................... 11 75 拖拉機(jī)變速箱機(jī)械加工工藝規(guī)程設(shè)計(jì) IV 工序 25：銑前后平面 ...............................................................................................12 工序 30： 銑上平面 .................................................................................................15 工序 35：粗鏜孔并鉆孔 ...........................................................................................18 工序 40：精鏜孔 .......................................................................................................22 工序 50：在三個(gè)平面上鉆孔 ...................................................................................27 工序 65： 三面攻螺 紋 ...............................................................................................38 工序 70：鉆孔攻螺紋 ...............................................................................................38 本章小結(jié) ...................................................................................................................39 6 結(jié)論 .....................................................................................................................................39 致 謝 ........