【正文】 故障可能發(fā)生在換擋機(jī)構(gòu)，此時(shí)應(yīng)拆卸變速器蓋檢查叉軸定位所求、凹槽和鎖球彈簧等工作情況。如撥叉變形則應(yīng)校正；磨損較大則應(yīng)將撥叉段焊修；如螺釘松動(dòng)則應(yīng)緊固。如發(fā)現(xiàn)變速器第一軸與曲軸同軸度不符合要求，則應(yīng)予以解決。③ 換擋擺桿球頭與換擋導(dǎo)塊磨損過(guò)大；換擋撥叉制動(dòng)螺釘松動(dòng)、拖出；換檔搖臂制動(dòng)螺栓折斷或脫出。（4）變速器異響1）故障現(xiàn)象① 變速器處于空檔位置時(shí)有異響，塔下離合器踏板時(shí)響聲消失。② 常嚙合齒輪磨損成階梯形或輪齒磨損；變速器齒輪磨損嚴(yán)重；齒隙過(guò)大。 ⑥ 長(zhǎng)期使用是變速箱殼體發(fā)生變形，降低了軸線位置的精度；變速器總成定位不穩(wěn)固。若靠攏某檔位后響聲劇響，相反方向響聲消失，則說(shuō)明該檔位齒輪與相鄰齒輪有碰擦現(xiàn)象。② 使用了不符合規(guī)定的齒輪油。先查看變速器油是否加注過(guò)多、通氣孔是否堵塞，在其正常情況下，可進(jìn)一步實(shí)施檢修。如墊片太薄，有硬化的或有破裂處，則需更換；若結(jié)合平面不平，則可修磨或銑削加工整平，然后重新裝復(fù)擰緊螺釘，加注變速器油再試車。若軸頸磨損，則可采用噴鍍修復(fù)；若座孔磨損，則可鑲套修復(fù)；若是殼體破裂，則可焊修或更換。經(jīng)過(guò)這次設(shè)計(jì)之后使我掌握了機(jī)械加工工藝規(guī)程的制定內(nèi)容和順序：分析被加工零件—選擇毛坯設(shè)計(jì)—工藝過(guò)程—工序設(shè)計(jì)—編制工藝文件。工藝過(guò)程的設(shè)計(jì)主要涉及的問(wèn)題是劃分工藝過(guò)程的組成、選擇定位基準(zhǔn)、選擇零件表面加工方法、安排加工順序和組合工序等。這次的畢業(yè)設(shè)計(jì)結(jié)束我不但了解到叉車變速箱的工藝，還學(xué)到了變速箱的其他作用以及傳動(dòng)系的功用。她淵博的知識(shí)、開(kāi)闊的視野和敏銳的思維給了我深深的啟迪。 最后，再次對(duì)關(guān)心、幫助我的老師和同學(xué)表示衷心地感謝！ 參 考 文 獻(xiàn)[1] ：機(jī)械工業(yè)出版社，2007.[2] 濮良貴 ：高等教育出版社，2010.[3] ：北京大學(xué)出版社，2009[4] :機(jī)械工業(yè)出版社,2008[5] :機(jī)械工業(yè)出版社,1993. [6] ,北京:機(jī)械工業(yè)出版社,2011[7] :機(jī)械工業(yè)出版社，1993.[8] 吉東亮. .[9] :西南交通大學(xué)出版社,2005.[10] ：機(jī)械工業(yè)出版社，2007.[11] 肖永清, :化學(xué)工業(yè)出版社,2006.[12] 孫栓柱 尹祖德 .:機(jī)械工業(yè)出版社，2011[13] 楊國(guó)平. 工程汽車、: 機(jī)械工業(yè)出版社，2009附錄一 科技文獻(xiàn)及翻譯 Numerical and experimental analysis of quenching process for cam manufacturing Abstract: In order to obtain satisfactory mechanical properties for the cam used in highpower ship diesel engines, a new quenching technology was proposed by designing a twostage quenching process with an alkaline bath as the quenching medium. To demonstrate the effectiveness of the proposed new quenching technology, both numerical analysis and study were performed. The new quenching technology was analyzed using finite element method. The bined effects of the temperature, stress and fields were investigated considering nonlinear material properties. Finally, an experimental study was performed to verify the effectiveness of the proposed new quenching technology. The numerical results show that internal stress is affected by both thermal stress and transformation stress. In addition, the direction of the internal stress is changed several times due to thermal interaction and microstructure evolution during the quenching process. The experimental results show that the proposed new quenching technology significantly improves the mechanical properties and microstructures of the cam. The tensile strength, the impact and the hardness value of the cam by the proposed new quenching technology are improved by %, % % pared with those by the traditional quenching technology. Moreover, the residual stress and cam shape deformation are reduced by % and % respectively for the cam manufactured by the new quenching technology. Key words: quenching process。 simulation experimental study1 IntroductionAs an essential part of a highpower ship, a cam must have a working surface with enough hardness, wear resistance, and toughness in order to have a guaranteed lifespan when working under severe conditions, including heavy load, high temperature, and fatigue. To meet the requirements for mechanical properties of the cam, a quenching process is widely used in the manufacturing of cams. However, traditional quenching processes adopted by domestic cam manufacturers cannot provide satisfactory mechanical properties for the cam. This is indicated by spot corrosion, cracks, and rapid erosion on the working surface of the cam within the designed work cycle. Moreover, traditional quenching processes, which generally consist of only one stage of quenching at a specified temperature, have difficulty in accurately analyzing the temperature and stress fields during the quenching process of the cam. In recent years, has been proposed in this subject. Different from the traditional quenching process, the new quenching technology consists of two stages of `quenching, with an alkaline bath as the quenching medium. It is believed that the proposed new quenching technology brings major advantages over the traditional quenching process, including better mechanical properties, better microstructures, and more accurate shape and dim The quenching process is a plicated process in which interaction occurs among cooling rate, temperature variation, phase transformation, an stress?strain state. For various microstructures during the quenching process, the physical properties of materials (including thermal conductivity, heat transfer coefficient, and specific heat at a constant pressure) and mechanical properties (including elastic modulus, plastic modulus, Poisson ratio, and yield strength), change continuously with the temperature variation. Since the process involves high nonlinearity of the cam material, it is very difficult to accurately analyze the temperature and stress fields during the quenching process of the cam. In recent years, a number of numerical investigations have been performed to predict the changes of temperature and stress fields of the cam during the quenching process . The microstructure and stress variations during quenching were analyzed. HOSSAIN et al predicted the residual and thermal stresses that occur during water quenching of solid spherical balls. KANG and IM established a3D elasticplastic model for plaincarbon steel along with phase transformation to improve the accuracy of numerical simulation. KAKHKI et al simulated the continuous cooling and kinetics of phase and predicted the final distribution of microstructures and hardness in low alloy steels using measured heat transfer coefficients of quenching media by an inverse method. ULYSSE and SCHULTZ investigated the effect of various surface treatments on the mechanical response of cylindrical aluminum missiles during warm water quenching. In the review of the dies on analyzing the quenching process, most of studies were solely focused on numerical simulation for onestage liquidquenching. Only a few studies conducted experimental investigations to verify the accuracy of simulation results. Moreover, the geometry of the