有關(guān)齒輪的相關(guān)文獻(xiàn)中英文翻譯

齒輪 齒輪 (Gear) 是依靠齒的嚙合傳遞扭矩的輪狀機(jī)械零件。齒輪通過(guò)與其它齒狀機(jī)械零件（如另一齒輪、齒條、蝸桿）傳動(dòng)，可實(shí)現(xiàn)改變轉(zhuǎn)速與扭矩、改變運(yùn)動(dòng)方向和改變運(yùn)動(dòng)形式等功能。由于傳動(dòng)效率高、傳動(dòng)比準(zhǔn)確、功率范圍大等優(yōu)點(diǎn)，齒輪機(jī)構(gòu)在工業(yè)產(chǎn)品中廣泛應(yīng)用，其設(shè)計(jì)與制造水平直接影響到工業(yè)產(chǎn)品的質(zhì)量。齒輪輪齒相互扣住齒輪會(huì)帶動(dòng)另一個(gè)齒輪轉(zhuǎn)動(dòng)來(lái)傳送動(dòng)力。 將兩個(gè)齒輪分開，也可以應(yīng)用鏈條、履帶、皮帶來(lái)帶動(dòng)兩邊的齒輪而傳送動(dòng)力。 基本介紹 . 齒輪在傳動(dòng)中的應(yīng)用很早就出現(xiàn)了。公元前三百多年，古希臘哲學(xué)家亞里士多德在 機(jī)械問題中，就闡述了用青銅或鑄鐵齒輪傳遞旋轉(zhuǎn)運(yùn)動(dòng)的問題。中國(guó)古代發(fā)明的指南車中已應(yīng)用了整套的輪系。不過(guò)，古代的齒輪是用木料制造或用金屬鑄成的，只能傳遞軸間的回轉(zhuǎn)運(yùn)動(dòng)，不能保證傳動(dòng)的平穩(wěn)性，齒輪的承載能力也很小。據(jù)史料記載，遠(yuǎn)在公元前 400200 年的中國(guó)古代就巳開始使用齒輪，在我國(guó)山西出土的青銅齒輪是迄今已發(fā)現(xiàn)的最古老齒輪，作為反映古代科學(xué)技術(shù)成就的指南車就是以齒輪機(jī)構(gòu)為核心的機(jī)械裝置。 17世紀(jì)末，人們才開始研究，能正確傳遞運(yùn)動(dòng)的輪齒形狀。 18 世紀(jì)，歐洲工業(yè)革命以后，齒輪傳動(dòng)的應(yīng)用日益廣泛；先是發(fā)展擺線齒 輪，而后是漸開線齒輪，一直到 20 世紀(jì)初，漸開線齒輪已在應(yīng)用中占了優(yōu)勢(shì)。 早在 1694 年，法國(guó)學(xué)者 Philippe De La Hire 首先提出漸開線可作為齒形曲線。 1733 年，法國(guó)人 M.Camus 提出輪齒接觸點(diǎn)的公法線必須通過(guò)中心連線上的節(jié)點(diǎn)。一條輔助瞬心線分別沿大輪和小輪的瞬心線 (節(jié)圓 )純滾動(dòng)時(shí)，與輔助瞬心線固聯(lián)的輔助齒形在大輪和小輪上所包絡(luò)形成的兩齒廓曲線是彼此共軛的，這就是 Camus定理。它考慮了兩齒面的嚙合狀態(tài)；明確建立了現(xiàn)代關(guān)于接觸點(diǎn)軌跡的概念。 1765年，瑞士的 L Euler提出漸開線齒形解 析研究的數(shù)學(xué)基礎(chǔ)，闡明了相嚙合的一對(duì)齒輪，其齒形曲線的曲率半徑和曲率中心位置的關(guān)系。后來(lái)，Savary 進(jìn)一步完成這一方法，成為現(xiàn)在的 Eu-let-Savary 方程。對(duì)漸開線齒形應(yīng)用作出貢獻(xiàn)的是 Roteft WUlls，他提出中心距變化時(shí)，漸開線齒輪具有角速比不變的優(yōu)點(diǎn)。 1873 年，德國(guó)工程師 Hoppe 提出，對(duì)不同齒數(shù)的齒輪在壓力角改變時(shí)的漸開線齒形，從而奠定了現(xiàn)代變位齒輪的思想基礎(chǔ)。 19 世紀(jì)末，展成切齒法的原理及利用此原理切齒的專用機(jī)床與刀具的相繼出現(xiàn)，使齒輪加工具軍較完備的手段后，漸開線齒形更顯示出 巨大的優(yōu)走性。切齒時(shí)只要將切齒工具從正常的嚙合位置稍加移動(dòng)，就能用標(biāo)準(zhǔn)刀具在機(jī)床上切出相應(yīng)的變位齒輪。 1908 年，瑞士 MAAG研究了變位方法并制造出展成加工插齒機(jī)，后來(lái)，英國(guó) BSS、美國(guó) AGMA、德國(guó) DIN相繼對(duì)齒輪變位提出了多種計(jì)算方法。 為了提高動(dòng)力傳動(dòng)齒輪的使用壽命并減小其尺寸，除從材料，熱處理及結(jié)構(gòu)等方面改進(jìn)外，圓弧齒形的齒輪獲得了發(fā)展。 1907 年，英國(guó)人 Frank Humphris最早發(fā)表了圓弧齒形。 1926年，瑞土人 Eruest Wildhaber 取得法面圓弧齒形斜齒輪的專利權(quán)。 1955 年， 蘇聯(lián)的 M L Novikov 完成了圓弧齒形齒輪的實(shí)用研究并獲得列寧勛章。 1970 年，英國(guó) Rolh Royce 公司工程師 R M.Studer 取得了雙圓弧齒輪的美國(guó)專利。這種齒輪現(xiàn)已日益為人們所重視，在生產(chǎn)中發(fā)揮了顯著效益。 齒輪是能互相嚙合的有齒的機(jī)械零件，它在機(jī)械傳動(dòng)及整個(gè)機(jī)械領(lǐng)域中的應(yīng)用極其廣泛?，F(xiàn)代齒輪技術(shù)已達(dá)到：齒輪模數(shù) O.004 100 毫米；齒輪直徑由 1毫米 150 米；傳遞功率可達(dá)上十萬(wàn)千瓦；轉(zhuǎn)速可達(dá)幾十萬(wàn)轉(zhuǎn) /分；最高的圓周速度達(dá) 300米 /秒。 隨著生產(chǎn)的發(fā)展，齒輪運(yùn)轉(zhuǎn)的平穩(wěn)性受到重視。 1674 年丹麥天文學(xué)家羅默首次提出用外擺線作齒廓曲線，以得到運(yùn)轉(zhuǎn)平穩(wěn)的齒輪。 18 世紀(jì)工業(yè)革命時(shí)期，齒輪技術(shù)得到高速發(fā)展，人們對(duì)齒輪進(jìn)行了大量的研究。 1733 年法國(guó)數(shù)學(xué)家卡米發(fā)表了齒廓嚙合基本定律； 1765 年瑞士數(shù)學(xué)家歐拉建議采用漸開線作齒廓曲線。 19 世紀(jì)出現(xiàn)的滾齒機(jī)和插齒機(jī)，解決了大量生產(chǎn)高精度齒輪的問題。 1900年，普福特為滾齒機(jī)裝上差動(dòng)裝置，能在滾齒機(jī)上加工出斜齒輪，從此滾齒機(jī)滾切齒輪得到普及，展成法加工齒輪占了壓倒優(yōu)勢(shì)，漸開線齒輪成為應(yīng)用最廣的齒輪。 1899年，拉舍最先實(shí)施了變位齒輪的方 案。變位齒輪不僅能避免輪齒根切，還可以湊配中心距和提高齒輪的承載能力。 1923 年美國(guó)懷爾德哈伯最先提出圓弧齒廓的齒輪， 1955 年蘇諾維科夫?qū)A弧齒輪進(jìn)行了深入的研究，圓弧齒輪遂得以應(yīng)用于生產(chǎn)。這種齒輪的承載能力和效率都較高，但尚不及漸開線齒輪那樣易于制造，還有待進(jìn)一步改進(jìn)。 結(jié)構(gòu)介紹 . 一般有輪齒、齒槽、端面、法面、齒頂圓、齒根圓、基圓、分度圓。 1) 輪齒 ,簡(jiǎn)稱齒，是齒輪上 每一個(gè)用于嚙合的凸起部分，這些凸起部分一般呈輻射狀排列，配對(duì)齒輪上的輪齒互相接觸，可使齒輪持續(xù)嚙合運(yùn)轉(zhuǎn)； 2) 齒槽 ,是齒輪上兩 相鄰輪齒之間的空間；端面是圓柱齒輪或圓柱蝸桿上 ，垂直于齒輪或蝸桿軸線的平面 3)法面 ,指的是垂直于輪齒齒線的平面 4) 齒頂圓 ,是指齒頂端所在的圓 5) 齒根圓 ,是指槽底所在的圓 6) 基圓 ,形成漸開線的發(fā)生線作純滾動(dòng)的圓 7) 分度圓 ,是在端面內(nèi)計(jì)算齒輪幾何尺寸的基準(zhǔn)圓。 齒輪可按齒形、齒輪外形、齒線形狀、輪齒所在的表面和制造方法等分類。 齒輪的齒形包括齒廓曲線、壓力角、齒高和變位。漸開線齒輪比較容易制造，因此現(xiàn)代使用的齒輪中 ，漸開線齒輪占絕對(duì)多數(shù)，而擺線齒輪和圓弧齒輪應(yīng)用較少。 在壓力角方面 ，小壓力角齒輪的承載能力較?。欢髩毫驱X輪，雖然承載能力較高，但在傳遞轉(zhuǎn)矩相同的情況下軸承的負(fù)荷增大，因此僅用于特殊情況。而齒輪的齒高已標(biāo)準(zhǔn)化，一般均采用標(biāo)準(zhǔn)齒高。變位齒輪的優(yōu)點(diǎn)較多，已遍及各類機(jī)械設(shè)備中。 另外，齒輪還可按其外形分為圓柱齒輪、錐齒輪、非圓齒輪、齒條、蝸桿蝸輪 ；按齒線形狀分為直齒輪、斜齒輪、人字齒輪、曲線齒輪；按輪齒所在的表面分為外齒輪、內(nèi)齒輪；按制造方法可分為鑄造齒輪、切制齒輪、軋制齒輪、燒結(jié)齒輪等。 齒輪的制造材料和熱處理過(guò)程對(duì)齒輪的承載能力和尺寸重量有很大的影響。20 世紀(jì) 50 年代前，齒輪多用碳鋼， 60 年代改用合金鋼，而 70 年代多用表面硬化鋼。按硬度 ，齒面可區(qū)分為軟齒面和硬齒面兩種。 軟齒面的齒輪承載能力較低，但制造比較容易，跑合性好， 多用于傳動(dòng)尺寸和重量無(wú)嚴(yán)格限制，以及小量生產(chǎn)的一般機(jī)械中。因?yàn)榕鋵?duì)的齒輪中，小輪負(fù)擔(dān)較重，因此為使大小齒輪工作壽命大致相等，小輪齒面硬度一般要比大輪的高。 硬齒面齒輪的承載能力高，它是在齒輪精切之后 ，再進(jìn)行淬火、表面淬火或滲碳淬火處理，以提高硬度。但在熱處理中，齒輪不可避免地會(huì)產(chǎn)生變形，因此在熱處理之后須進(jìn)行磨削、研磨或精切 ，以消 除因變形產(chǎn)生的誤差，提高齒輪的精度。 材料構(gòu)成 制造齒輪常用的鋼有調(diào)質(zhì)鋼、淬火鋼、滲碳淬火鋼和滲氮鋼。鑄鋼的強(qiáng)度比鍛鋼稍低，常用于尺寸較大的齒輪；灰鑄鐵的機(jī)械性能較差，可用于輕載的開式齒輪傳動(dòng)中；球墨鑄鐵可部分地代替鋼制造齒輪 ；塑料齒輪多用于輕載和要求噪聲低的地方，與其配對(duì)的齒輪一般用導(dǎo)熱性好的鋼齒輪。 未來(lái)齒輪正向重載、高速、高精度和高效率等方向發(fā)展，并力求尺寸小、重量輕、壽命長(zhǎng)和經(jīng)濟(jì)可靠。 而齒輪理論和制造工藝的發(fā)展將是進(jìn)一步研究輪齒損傷的機(jī)理，這是建立可靠的強(qiáng)度計(jì)算方法的依據(jù)，是提高齒 輪承載能力，延長(zhǎng)齒輪壽命的理論基礎(chǔ)；發(fā)展以圓弧齒廓為代表的新齒形；研究新型的齒輪材料和制造齒輪的新工藝； 研究齒輪的彈性變形、制造和安裝誤差以及溫度場(chǎng)的分布，進(jìn)行輪齒修形，以改善齒輪運(yùn)轉(zhuǎn)的平穩(wěn)性，并在滿載時(shí)增大輪齒的接觸面積，從而提高齒輪的承載能力。 摩擦、潤(rùn)滑理論和潤(rùn)滑技術(shù)是 齒輪研究中的基礎(chǔ)性工作，研究彈性流體動(dòng)壓潤(rùn)滑理論，推廣采用合成潤(rùn)滑油和在油中適當(dāng)?shù)丶尤霕O壓添加劑，不僅可提高齒面的承載能力，而且也能提高傳動(dòng)效率。 1、齒面磨損 對(duì)于開式齒輪傳動(dòng)或含有不清潔的潤(rùn)滑油的閉式齒輪傳動(dòng)，由于嚙合齒 面間的相對(duì)滑動(dòng)，使一些較硬的磨粒進(jìn)入了摩擦表面，從而使齒廓改變，側(cè)隙加大，以至于齒輪過(guò)度減薄導(dǎo)致齒斷。一般情況下，只有在潤(rùn)滑油中夾雜磨粒時(shí)，才會(huì)在運(yùn)行中引起齒面磨粒磨損。 2、齒面膠合 對(duì)于高速重載的齒輪齒輪傳動(dòng)中，因齒面間的摩擦力較大，相對(duì)速度大，致使嚙合區(qū)溫度過(guò)高，一旦潤(rùn)滑條件不良，齒面間的油膜便會(huì)消失，使得兩輪齒的金屬表面直接接觸，從而發(fā)生相互粘結(jié)。當(dāng)兩齒面繼續(xù)相對(duì)運(yùn)動(dòng)時(shí)，較硬的齒面將較軟的齒面上的部分材料沿滑動(dòng)方向撕下而形成溝紋。 3、疲勞點(diǎn)蝕 相互嚙合的兩輪齒接觸時(shí)，齒面間的作用力 和反作用力使兩工作表面上產(chǎn)生接觸應(yīng)力，由于嚙合點(diǎn)的位置是變化的，且齒輪做的是周期性的運(yùn)動(dòng)，所以接觸應(yīng)力是按脈動(dòng)循環(huán)變化的。齒面長(zhǎng)時(shí)間在這種交變接觸應(yīng)力作用下，在齒面的刀痕處會(huì)出現(xiàn)小的裂紋，隨著時(shí)間的推移，這種裂紋逐漸在表層橫向擴(kuò)展，裂紋形成環(huán)狀后，使輪齒的表面產(chǎn)生微小面積的剝落而形成一些疲勞淺坑。 4、輪齒折斷 在運(yùn)行工程中承受載荷的齒輪，如同懸臂梁，其根部受到脈沖的周期性應(yīng)力超過(guò)齒輪材料的疲勞極限時(shí)，會(huì)在根部產(chǎn)生裂紋，并逐步擴(kuò)展，當(dāng)剩余部分無(wú)法承受傳動(dòng)載荷時(shí)就會(huì)發(fā)生斷齒現(xiàn)象。齒輪由于工作中嚴(yán)重的沖 擊、偏載以及材質(zhì)不均勻也可能引起斷齒。 5、齒面塑性變形 在沖擊載荷或重載下，齒面易產(chǎn)生局部的塑性變形，從而使?jié)u開線齒廓的曲面發(fā)生變形。 中國(guó)齒輪工業(yè)的發(fā)展 中國(guó)齒輪工業(yè)在 “ 十五 ” 期間得到了快速發(fā)展： 2005 年齒輪行業(yè)的年產(chǎn)值由 2000年的 240億元增加到 683億元，年復(fù)合增長(zhǎng)率 23.27%，已成為中國(guó)機(jī)械基礎(chǔ)件中規(guī)模最大的行業(yè)。就市場(chǎng)需求與生產(chǎn)規(guī)模而言，中國(guó)齒輪行業(yè)在全球排名已超過(guò)意大利，居世界第四位。 2006 年，中國(guó)全部齒輪、傳動(dòng)和驅(qū)動(dòng)部件制造企業(yè)實(shí)現(xiàn)累計(jì)工業(yè)總產(chǎn)值102628183 千元，比上年同期增長(zhǎng) 24.15%；實(shí)現(xiàn)累計(jì)產(chǎn)品銷售收入 98238240 千元，比上年同期增長(zhǎng) 24.37%；實(shí)現(xiàn)累計(jì)利潤(rùn)總額 5665210 千元，比上年同期增長(zhǎng) 26.85%。 2007年 1-12月，中國(guó)全部齒輪、傳動(dòng)和驅(qū)動(dòng)部件制造企業(yè)實(shí)現(xiàn)累計(jì)工業(yè)總產(chǎn)值 136542841千元，比上年同期增長(zhǎng) 30.96%； 2008年 1-10月，中國(guó)全部齒輪、傳動(dòng)和驅(qū)動(dòng)部件制造企業(yè)實(shí)現(xiàn)累計(jì)工業(yè)總產(chǎn)值 144529138千元，比上年同期增長(zhǎng)32.92%。 中國(guó)齒輪制造業(yè)與發(fā)達(dá)國(guó)家相比還存在自主創(chuàng)新能力不足、新品開發(fā)慢、市場(chǎng)競(jìng)爭(zhēng)無(wú)序 、企業(yè)管理薄弱、信息化程度低、從業(yè)人員綜合素質(zhì)有待提高等問題?，F(xiàn)階段齒輪行業(yè)應(yīng)通過(guò)市場(chǎng)競(jìng)爭(zhēng)與整合，提高行業(yè)集中度，形成一批擁有幾十億元、 5 億元、 1 億元資產(chǎn)的大、中、小規(guī)模企業(yè)；通過(guò)自主知識(shí)產(chǎn)權(quán)產(chǎn)品設(shè)計(jì)開發(fā)，形成一批車輛傳動(dòng)系（變速箱、驅(qū)動(dòng)橋總成）牽頭企業(yè)，用牽頭企業(yè)的配套能力整合齒輪行業(yè)的能力與資源；實(shí)現(xiàn)專業(yè)化、網(wǎng)絡(luò)化配套，形成大批有特色的工藝、有特色的產(chǎn)品和有快速反應(yīng)能力的名牌企業(yè)；通過(guò)技改，實(shí)現(xiàn)現(xiàn)代化齒輪制造企業(yè)轉(zhuǎn)型。 “ 十一五 ” 末期，中國(guó)齒輪制造業(yè)年銷售額可達(dá)到 1300 億元，人均銷售額上升到 65萬(wàn) 元 /年，在世界行業(yè)排名中達(dá)到世界第二。 2006-2010年將新增設(shè)備10萬(wàn)臺(tái)，即每年用于新增設(shè)備投資約 60億元，新購(gòu)機(jī)床 2萬(wàn)臺(tái)，每臺(tái)平均單價(jià)30 萬(wàn)元。到 2010 年，中國(guó)齒輪制造業(yè)應(yīng)有各類機(jī)床總數(shù)約 40 萬(wàn)臺(tái)，其中數(shù)控機(jī)床 10萬(wàn)臺(tái)，數(shù)控化率 25%（高于機(jī)械制造全行業(yè)平均值 17%） . 中重型載貨汽車齒輪 我國(guó)中重型載貨汽車齒輪用鋼牌號(hào)較多，主要是為適應(yīng)引進(jìn)當(dāng)時(shí)國(guó)外先進(jìn)汽車技術(shù)的要求。 50 年代我國(guó)從原蘇聯(lián)里哈喬夫汽車廠引進(jìn)當(dāng)時(shí)蘇聯(lián)中型載貨汽車 (即 “ 解放 ” 牌原車型 )生產(chǎn)技術(shù)的同時(shí)，也引進(jìn)了原蘇聯(lián)生產(chǎn)汽車齒輪的20CrMnTi鋼種。 改革開放以后，隨著我國(guó)經(jīng)濟(jì)建設(shè)的高速發(fā)展，為了滿足我國(guó)交通運(yùn)輸?shù)目焖侔l(fā)展需要，從 80 年代開始，我國(guó)有計(jì)劃地引進(jìn)工業(yè)發(fā)達(dá)國(guó)家的各類先進(jìn)機(jī)型，各類國(guó)外先進(jìn)中重型載貨汽車也不斷引進(jìn)。同時(shí)，我國(guó)大汽車廠同國(guó)外著名汽車大公司進(jìn)行合作，引進(jìn)國(guó)外先進(jìn)汽車生產(chǎn)技術(shù)，其中包括汽車齒輪的生產(chǎn)技術(shù)。與此同時(shí)，我國(guó)鋼鐵冶煉技術(shù)水平也在不斷提高，采用鋼包二次冶煉及成分微調(diào)和連鑄連軋等先進(jìn)治煉技術(shù)，使得鋼廠能生產(chǎn)出高純凈度、淬透性能帶縮窄的齒輪用鋼材，從而實(shí)現(xiàn)了引進(jìn)汽車齒輪用鋼的國(guó)產(chǎn)化，使我國(guó)齒輪用鋼的生產(chǎn) 水平上了一個(gè)新臺(tái)階。近年來(lái)，適合于我國(guó)國(guó)情的國(guó)產(chǎn)重型汽車齒輪用含鎳高淬透性能鋼也得到了開發(fā)和應(yīng)用，取得了較好效果。汽車齒輪的熱處理技術(shù)也從原50-60 年代采用井式氣體滲碳護(hù)發(fā)展到當(dāng)前普遍采用由計(jì)算機(jī)控制的連續(xù)式氣體滲碳自動(dòng)線和箱式多用爐及自動(dòng)生產(chǎn)線 (包括低壓 (真空 )滲碳技術(shù) )、齒輪滲碳預(yù)氧化處理技術(shù)，齒輪淬火控制冷卻技術(shù) (由于專用淬火油和淬火冷卻技術(shù)的使用 )、齒輪鍛坯等溫正火技術(shù)等。這些技術(shù)的采用不僅使齒輪滲碳淬火畸變得到了有效控制、齒輪加工精度得到提高、使用壽命得到延長(zhǎng)，而且還滿足了齒輪的現(xiàn)代化熱處理的大 批量生產(chǎn)需要。 有關(guān)文獻(xiàn)指出，汽車齒輪的壽命主要由兩大指標(biāo)考核，一是齒輪的接觸疲勞強(qiáng)度，二是齒輪的彎曲疲勞強(qiáng)度。前者主要由滲碳淬火質(zhì)量決定，后者主要由齒輪材料決定。為此，有必要對(duì)汽車齒輪用滲碳鋼的要求、性能及其熱處理特點(diǎn)有一個(gè)較全面的了解。 9.19 鉻錳鈦鋼和硼鋼 長(zhǎng)期以來(lái)，我國(guó)載貨汽車齒輪使用最普遍的鋼種是 20CrMnTi。這是上世紀(jì)50年代我國(guó)從原蘇聯(lián)引進(jìn)的中型的汽車齒輪 18XTr鋼種 (即 20CrMnTi 鋼 )。該鋼晶粒細(xì)，滲碳時(shí)晶粒長(zhǎng)大傾向小，具有良好的滲碳淬火性能，滲碳后可直接淬火。文獻(xiàn)指 出，在 1980 年以前，我國(guó)的滲碳合金結(jié)構(gòu)鋼 (包括 20CrbinTi 鋼 )在鋼材出廠時(shí)只保證鋼材的化學(xué)成分和用樣品測(cè)定的力學(xué)性能，但是在汽車生產(chǎn)時(shí)常常出現(xiàn)化學(xué)成分和力學(xué)性能合格的鋼材，由于淬透性能波動(dòng)范圍過(guò)大而影響產(chǎn)品質(zhì)量的情況。例如若 20CrMnTi 滲碳鋼的淬透性過(guò)低，則制成的齒輪滲碳淬火后，心部硬度低于技術(shù)條件規(guī)定的數(shù)值，疲勞試驗(yàn)時(shí)，齒輪的疲勞壽命降低一半；若淬透性能過(guò)高，則齒輪滲碳淬火后內(nèi)孔收縮量過(guò)大而影響齒輪裝配。 由于鋼材淬透性能對(duì)輪齒心部的硬度和畸變都有極其重大的影響， 1985 年冶金部頒布了我國(guó) 的保證淬透性結(jié)構(gòu)鋼技術(shù)條件 (GB5216-85)，在此技術(shù)條件中列入了包括 20CxMnTiH、 20MnVBH鋼在內(nèi)的 10種滲碳鋼的化學(xué)成分、淬透性能數(shù)據(jù)。標(biāo)準(zhǔn)中規(guī)定：用于制造齒輪的 20CrMnTi 鋼的淬透性能指標(biāo)為距水冷端 9 咖處的硬度為 30-42HRC。在此之后，采用 20CrMnTi 鋼生產(chǎn)齒輪的齒心部硬度過(guò)低和畸變過(guò)大的問題基本上得到了解決。但是不管齒輪模數(shù)大小和鋼材截面粗細(xì)均采用同一鋼號(hào) 20CrMnTi 鋼顯然是不合理的。近年來(lái)，由于我國(guó)鋼材冶煉技術(shù)水平的提高以及合金結(jié)構(gòu)鋼供應(yīng)情況的改善，已經(jīng)有條件把齒輪鋼 的淬透性能帶進(jìn)一步縮窄，并根據(jù)不同產(chǎn)品 (如變速器齒輪與后橋齒輪等 )的要求開發(fā)新的鋼種以滿足其要求。 通過(guò)與鋼廠協(xié)商， 1997 年長(zhǎng)春一汽先后與生產(chǎn)齒輪鋼廠的生產(chǎn)廠家簽定了將 20CrMnTi鋼淬透性能分擋供應(yīng)的協(xié)議，例如 “ 解放 ” 牌 5t載貨汽車上用于制造截面尺寸較小的變速器第一軸、中間軸齒輪和截面尺寸較大的后橋主、從動(dòng)圓錐齒輪用 20CrMnTiH 鋼淬透性能組別分別為 I 和 ，對(duì)應(yīng)淬透性能分別為 J9：30 36HRC和 J9=36 42HRC。 1960 年前后，由于我國(guó)鎳、鉻鋼的供應(yīng)緊張，影響了我國(guó)含鎳、鉻鋼材 的生產(chǎn)。而當(dāng)時(shí)我國(guó)的汽車工業(yè)是從原蘇聯(lián)引進(jìn)的技術(shù)，蘇聯(lián)大量應(yīng)用含鎳、鉻的鋼材。因此，當(dāng)時(shí)我國(guó)汽車工業(yè)大力發(fā)展了硼鋼的開發(fā)、研制工作，用 20MnVB和 20Mn2TiB鋼代替 20CrMnTi滲碳鋼制造齒輪。這是因?yàn)樵诮Y(jié)構(gòu)鋼中加入微量硼(0.0001%-0.0035%)可以顯著地提高鋼材的淬透性能，因此鋼中加入微量硼可以代替一定數(shù)量的錳、鎳、鉻、鉬等貴重合金元素，因而硼鋼得到廣泛的應(yīng)用。長(zhǎng)春一汽曾在 “ 解放 ” 牌汽車齒輪生產(chǎn)中使用過(guò) 20MnTiB和 20Mn2TiB 鋼。 東風(fēng)汽車公司生產(chǎn)的 “ 東風(fēng) ” 牌 5，載貨汽車變速 器和后橋齒輪分別采用20CrMnTi和 20MnVB 鋼制造。同樣，也與鋼廠簽定了把鋼材淬透性能帶縮窄并分檔供應(yīng)的協(xié)議。變速器和后橋主、從動(dòng)圓錐齒輪用鋼分別為 20CrMnTiH(3)和20MnVBH(2)、 20MnVBH(3)，對(duì)應(yīng)淬透性能分別為 J9=32 39HRC和 J9=37 44HRC、J9=34 42HRC。 我國(guó)綦江齒輪廠引進(jìn)了德國(guó)公司的重型汽車變速器齒輪生產(chǎn)技術(shù)，在國(guó)內(nèi)按德國(guó) 公司的標(biāo)準(zhǔn)試制了該公司的 Cr-Mn-B 系含硼齒輪鋼獲得成功。其齒輪材料的淬透性能為 J10=31 39HRC 當(dāng)然， 20CrMnTi 鋼及 20MnTiB鋼、 20MVB 鋼等含硼鋼也存在不足。一般認(rèn)為20CrMnTi 等滲碳鋼是本質(zhì)細(xì)晶粒鋼，滲碳后晶粒不會(huì)粗化，可直接淬火。但實(shí)際上由于鋼材冶煉質(zhì)量的影響，常常在正常條件下發(fā)生晶粒粗化現(xiàn)象。對(duì)多批材料的實(shí)際晶粒度試驗(yàn)，發(fā)現(xiàn)相當(dāng)部分實(shí)際晶粒度只有 2 3級(jí) (930 保溫 3h條件下 )。文獻(xiàn)認(rèn)為， 20CrMnTi 由于 Ti 含量較高，鋼中 TiN 夾雜物多，尤其是大塊的 TiN夾雜是齒輪疲勞時(shí)的疲勞源，它的存在會(huì)降低齒輪的接觸疲勞性能。這種夾雜物呈立方結(jié)構(gòu)，受力時(shí)易發(fā)生解理開裂，導(dǎo)致齒輪早期失效。另一 個(gè)問題是該鋼的淬透性能有限，不能滿足大直徑大模數(shù)齒輪的要求，滲碳有效硬化層深度和心部硬度均不能滿足重型齒輪的要求。此外，在熱處理過(guò)程中 20CrMnTi 鋼易產(chǎn)生內(nèi)氧化和非馬氏體組織而降低齒輪的疲勞壽命。但目前在我國(guó)齒輪滲碳鋼中還沒有哪一種鋼在滲碳工藝上有 20CrMnTi 鋼這樣成熟和可靠。所以，它仍是目前國(guó)內(nèi)使用最普遍的滲碳鋼種。 20MnVB、 20MnTiB 和 20Mn2TiB 等硼鋼也存在一些缺點(diǎn)，如在冶煉時(shí)由于脫氧去氮不好而使硼不能起到增加淬透性能的作用，因此，使硼鋼的性能不穩(wěn)定，滲碳淬火后的齒輪畸變?cè)龃蠖绊?產(chǎn)品的質(zhì)量。同時(shí)由于混晶和晶粒易于粗大，致變形不易控制和韌性較差，且硼鋼齒輪根部易產(chǎn)生托氏體組織和碳氮共滲齒輪的黑網(wǎng)、黑帶。因此，目前很多工廠中止使用該鋼種。然而，決不能就此得出硼鋼不適宜作齒輪滲碳鋼的結(jié)論。含硼的滲碳鋼在國(guó)外還有使用。例如，德國(guó)著名的 齒輪廠，一直使用由其本廠擬訂的保留鋼種 ZF7，這是一種含硼的低碳鉻錳鋼。該鋼主要化學(xué)成分 (質(zhì)量分?jǐn)?shù)， %)為 0.15 0.20C，0.15 0.40S， 1.0 1.3Cr， 1.0 1.3Mn， 0.001 0.003B。美國(guó)汽車變速器齒輪和后橋主、從動(dòng)齒輪有的也 采用含硼滲碳鋼，如 50B15、 43BVl4和 94B17。因此，只要鋼廠冶煉技術(shù)跟上去，硼鋼的上述問題是能夠解決的。 20CrMnTiH、 20MnVBH 和 20MnTiBH鋼齒輪鍛坯在連續(xù)式等溫正火爐內(nèi)進(jìn)行處理可以保證得到均勻分布的片狀珠光體 +鐵素體。這樣可以使齒輪的熱處理畸變大大減小，使齒輪的精度提高，使用壽命延長(zhǎng)。 齒輪鍛坯等溫正火硬度為 156 207HB。 鉻錳鉬鋼和鉻鉬鋼 22CrMnMo、 20CrMnMoH 和 20CrMoH鋼由于有著較高淬透性而用于中型汽車齒輪。此類鋼可采用滲碳后直接淬 火工藝。由于鉻錳鉬鋼和鉻鉬鋼中含有鉻和鉬等形成碳化物的元素，在滲碳過(guò)程中將促使輪齒表面碳含量增加，容易在滲碳層組織中出現(xiàn)大量碳化物，使?jié)B碳層性能惡化。因此，齒輪采用鉻錳鉬鋼和鉻鉬鋼滲碳時(shí)，宜采用弱滲碳?xì)夥?，以防止形成過(guò)量碳化物。 22CrMnMo 和 20CrMnMoH 齒輪鍛坯正火后在 650 670 進(jìn)行高溫回火處理，金相組織為細(xì)片狀珠光體 +少量鐵素體，硬度為 171 229HB。 20CrMnH齒輪鍛坯最好在連續(xù)式等溫正火爐中處理，935 945 加熱， 640 650 先預(yù)冷后等溫，可獲得均勻的鐵素體 +珠光體組織，硬度為 156 207HB。文獻(xiàn)指出， 20CrMoH鋼冶煉工藝穩(wěn)定，淬透性帶較窄且易于控制，與 20CrMnTi 鋼齒輪比較，具有熱處理畸變?。粷B層有良好、穩(wěn)定的淬透性；金相組織、滲碳淬火后的表面和心部硬度，均能較好地滿足技術(shù)要求；疲勞性能好，比較適合汽車中小模數(shù)齒輪。綜合考慮齒輪的服役條件，既保證齒輪的疲勞壽命，又減少齒輪的熱處理畸變，在用以制造變速箱齒輪時(shí)應(yīng)為 J9=3036HRC，用以制造后橋齒輪時(shí)應(yīng)為 J9=37 42HRC。 9.21 國(guó)外先進(jìn)汽車齒輪用鋼的國(guó)產(chǎn)化 隨著國(guó)外先進(jìn)車型的引進(jìn)，各種齒輪鋼 的國(guó)產(chǎn)化使我國(guó)的齒輪鋼水平上了一個(gè)新臺(tái)階。目前，德國(guó)的 Cr-Mn鋼，日本的 Cr-Mo系鋼，和美國(guó)的 SAE86 鋼滿足了中小模數(shù)齒輪用鋼。國(guó)產(chǎn)載貨汽車齒輪有的采用美國(guó)牌號(hào) SAE8822H 鋼，如 8t和 10t橋用圓錐齒輪采用 SAE8822H，該鋼主要化學(xué)成分 (質(zhì)量分?jǐn)?shù)， %)為 0.190.25C， 0.70 1.05Mn， 0.15 0.35Si， 0.35 0.75Ni， 0.35 0.65Cr， 0.300.40Mo。文獻(xiàn)認(rèn)為，控制淬透性是解決齒輪畸變問題的關(guān)鍵。為減少畸變應(yīng)選用Jominy淬透性帶寬在 4HRC以下的 H鋼。采用 H鋼的齒輪熱處理后精度 (接觸區(qū) )比普通鋼高 70% 80%，使用壽命延長(zhǎng)。因此，工業(yè)發(fā)達(dá)國(guó)家先后規(guī)定了滲碳合金結(jié)構(gòu)鋼的淬透性帶。根據(jù)需要將淬透性帶限制在很窄的范圍 (4 5HRC)。 1)在德國(guó)訂貨時(shí)，可以要求鋼材的淬透性能在給定的范圍內(nèi)，也可以要求縮窄淬透性能的鋼材。 17CrNiM06 非常適合制造大模數(shù)重負(fù)荷汽車齒輪，該鋼主要化學(xué)成分(質(zhì)量分?jǐn)?shù)， %)為 0.15 0.20C， 0.40 0.60Mn， 1.50 1.80Cr， 0.25 0.35Mo，1.40 1.70Ni。此鋼在我國(guó)已開始生產(chǎn)和使用。文獻(xiàn)認(rèn)為 ，在 17CrNiM06 鋼齒輪滲碳過(guò)程中，在適當(dāng)降低滲碳后期碳勢(shì)的同時(shí)加快滲碳后的冷卻速度，由空冷改為風(fēng)冷，阻止大塊碳化物的形成，然后在 630cC 進(jìn)行高溫回火，以析出部分合金碳化物，為的是在 820 二次加熱淬火時(shí)減少殘留奧氏體量，最終獲得較好的金相組織。 2)奧地利 Styer重型汽車廠要求淬透性帶寬為 7HRC。 3)日本中重型貨車，如 “ 日野 ” 牌 KB222 型載重 9t汽車和 “ 日產(chǎn) ” 牌 CKL20DD型載貨 8t汽車的變速器齒輪及后橋齒輪廣泛采用 Cr-Mo系鋼，如 SCM420H和 SCM822H 鋼，相當(dāng)于我國(guó)國(guó)產(chǎn)化 20CrMnMoH 和 22CrMoH鋼。 此類鋼具有較高的淬透性能。在一定范圍內(nèi)，齒輪的彎曲疲勞壽命隨著淬透性的增加而提高。文獻(xiàn)指出，長(zhǎng)春一汽開始在生產(chǎn) “ 解放 ” 牌 9t 載貨汽車后橋齒輪時(shí)，采用 20CrMnTiH 鋼，即使使用淬透性能為 組的鋼材 (J9=36 42HRC)，熱處理后齒輪輪齒心部硬度也只有 22 24HRC，達(dá)不到齒輪技術(shù)條件規(guī)定的要求，汽車在使用時(shí)，后橋主動(dòng)和從動(dòng)圓錐齒輪發(fā)生早期損壞。因此不得不選用淬透性能更高的 Ct-Mo 鋼，其主要成分參考日本的 SCM822H齒輪鋼，該鋼材的主要化學(xué)成分 (質(zhì)量分?jǐn)?shù)， %)為： 0.19 0.25C， 0.55 0.90Mn， 0.15 0.35Si， 0.851.25Cr， 0.35 0.45Mo。經(jīng)與鋼廠協(xié)商，生產(chǎn)出了國(guó)產(chǎn)化的新鋼種 22CrMoH鋼，其淬透性能指標(biāo)為 J9=36 42HRC，較好地滿足了汽車齒輪的使用要求。但是，該鋼的工藝性能較差，齒輪鍛坯要經(jīng)過(guò)等溫退火處理后才能進(jìn)行切削加工，硬度為 156 207HB，金相組織為先共析鐵素體 +偽共析珠光體。此鋼淬透性能較高，普通正火容易產(chǎn)生粒狀貝氏體，粒狀貝氏體的出現(xiàn)對(duì)切削加工極為不利，不僅使刀具的使用壽命大幅度下降，而且由于異常組 織的出現(xiàn)，總是伴隨著金相組織的不均勻性，最終造成齒輪熱處理畸變的增大。 4)近年來(lái)，美國(guó)汽車制造廠家力圖降低生產(chǎn)成本并提高零件的可靠性和耐久性，這就需要產(chǎn)品的幾何尺寸及力學(xué)性能的高度一致。對(duì)熱處理的零件要改善產(chǎn)品性能的一致性，必須降低零件淬火后硬度的分散程度，這就與鋼的淬透性能帶的寬窄程度有直接關(guān)系。齒輪心部硬度的一致性將減少熱處理的畸變，從而提高齒輪的精度，并使輪齒表層的殘余壓應(yīng)力分布更加均勻。美國(guó)載貨汽車變速器齒輪和后橋主動(dòng)圓錐齒輪用鋼有的采用SAE8620 鋼和 SAFA820 鋼制造。美國(guó) SAE8620H、 SAE8822H 等牌號(hào)鋼在我國(guó)也已開始生產(chǎn) (如寶鋼集團(tuán)上鋼五廠等 )和使用，分別用于中型載貨汽車變速器齒輪和后橋圓錐齒輪。 9.22 國(guó)內(nèi)重型汽車齒輪用鋼 目前，我國(guó)齒輪鋼基本滿足使用和引進(jìn)技術(shù)過(guò)程國(guó)產(chǎn)化的要求，而重型車傳動(dòng)齒輪及中重型車的后橋齒輪用鋼，尚有待開發(fā)和生產(chǎn)。根據(jù)國(guó)內(nèi)重型汽車的使用技術(shù)現(xiàn)狀分析，超載使用和路況較差這兩個(gè)問題較為嚴(yán)重，而且短期內(nèi)無(wú)法克服，這就使齒輪經(jīng)常承受較大的過(guò)載沖擊載荷。過(guò)載沖擊載荷介于疲勞和斷裂應(yīng)力之間，它對(duì)齒輪使用壽命有很大影響，往往造成齒輪早期失效。從這一點(diǎn)來(lái)說(shuō)，大模 數(shù)重負(fù)荷汽車齒輪應(yīng)選擇 Cr-Ni 或 Cr-Ni-Mo 系鋼，如德國(guó)的 17CrNiM06 鋼最好，還有國(guó)產(chǎn) 20CrNi3H、 20CrNiMoH 鋼。大功率發(fā)動(dòng)機(jī)的問世促進(jìn)了新型Cr-Ni-Mo 系列齒輪鋼的開發(fā)和應(yīng)用。如新型齒輪用鋼 20CrNi2Mo、 17CrNiM06。一汽集團(tuán)某汽車改裝公司開發(fā)了一種新型載貨汽車橋，其特點(diǎn)是匹配發(fā)動(dòng)機(jī)的功率大。為保證齒輪的使用壽命，對(duì)齒輪的材料及質(zhì)量有了更高的要求，原采用22CrMoH鋼制成的后橋主動(dòng)圓錐齒輪在使用過(guò)程中出現(xiàn)早期失效，嚴(yán)重時(shí)甚至出現(xiàn)斷齒現(xiàn)象。在熱處理方面，由于齒輪材料 熱處理工藝有時(shí)不夠穩(wěn)定，部分齒輪的有效硬化層不夠，齒輪心部和表面硬度偏低，這些都是導(dǎo)致齒輪早期失效的主要原因。而且， Cr 容易形成晶間網(wǎng)狀碳化物，有損滲層力學(xué)性能。分析發(fā)現(xiàn)，齒輪輪齒心部硬度低時(shí)，過(guò)渡層塑性變形會(huì)引起滲碳層產(chǎn)生過(guò)高應(yīng)力，因而導(dǎo)致滲碳層形成裂紋，最后使整個(gè)輪齒斷裂。為此，根據(jù) “ 斯太爾 ” 汽車橋后橋主動(dòng)圓錐齒輪使用 20CrNi3H 鋼的良好行車使用效果，應(yīng)確保齒輪的有效硬化層深度在 1.8 2.2mm，齒輪輪齒心部硬度在 38 45HRC，齒輪表面硬度在 60 64HRC，碳化物在 1 3級(jí)，馬氏體、殘留奧氏 體在 1 4級(jí)，這樣可使齒輪的使用壽命提高 30% 40%。 9.23 粉末冶金齒輪 粉末冶齒輪是少切屑、無(wú)切屑的高新技術(shù)的產(chǎn)物。 雖然粉末冶金齒輪在整個(gè)粉末冶金零件中難以單獨(dú)統(tǒng)計(jì)，但無(wú)論是按重量還是按零件數(shù)量，粉末冶金齒輪在汽車、摩托車中所占的比例都遠(yuǎn)遠(yuǎn)大干其他領(lǐng)域中的粉末冶金零件。因此，從汽車、摩托車在整個(gè)粉末冶金零件中所占比例的上升可以看出，粉末冶金齒輪在整個(gè)粉末冶金零件中處于飛速發(fā)展的地位。如果按零件特點(diǎn)來(lái)分，齒輪屬于結(jié)構(gòu)類零件，而結(jié)構(gòu)類零件在整個(gè)鐵基零件中所占的絕對(duì)重量也遠(yuǎn)遠(yuǎn)大于其他幾類， 粉末冶金零件。 主要粉末冶金齒輪 (1)凸輪軸齒形帶輪 凸輪軸齒形帶輪是各種汽車發(fā)動(dòng)機(jī)中普遍使用的粉末冶金零件，通過(guò)一次成形和精整工藝，不需要其他后處理工藝，可以完全達(dá)到尺寸精度要求，尤其是齒形精度。因此，與用傳統(tǒng)機(jī)械加工方法制造相比，在材料投入和制造上都大大減少，它是體現(xiàn)粉末冶金特點(diǎn)的典型產(chǎn)品。粉末冶金零件配套舉例 配套類別零部件名稱：汽車發(fā)動(dòng)機(jī)；凸輪軸、曲軸正時(shí)帶輪，水泵、油泵帶輪，主動(dòng)、從動(dòng)齒輪，主動(dòng)、從動(dòng)鏈輪，凸輪，軸承蓋，搖臂，襯套，止推板，氣門導(dǎo)管，進(jìn)、排氣門閥座汽車變速箱；各 種高低速同步器齒轂及組件，離合器齒輪，凸輪、凸輪軸，滑塊，換擋桿，軸套，導(dǎo)塊，同步環(huán) 摩托車零件；從動(dòng)齒輪及組件，鏈輪，起動(dòng)棘爪，棘輪，星形輪，雙聯(lián)齒輪，副齒輪，變速齒輪，推桿凸輪，軸套，滑動(dòng)軸承，定心套，從動(dòng)盤，進(jìn)、排氣門閥座 汽車、摩托車油泵；各種油泵齒輪、齒轂，各種油泵轉(zhuǎn)子，凸輪環(huán)汽車、摩托車減振器各種活塞，底閥座，導(dǎo)向座壓縮機(jī)各種活塞，缸體，缸蓋，閥板，密封環(huán)農(nóng)機(jī)產(chǎn)品 各種軸套，轉(zhuǎn)子，軸承 . 其他；分電器齒輪，行星齒輪，內(nèi)齒盤，組合內(nèi)齒輪，各種不銹鋼螺母，磁極。 Gear Gear (Gear) is relying on the tooth meshing torque rotavirus mechanical parts.Gear with other dentate machinery parts, such as a worm gear, rack, transmission, which can realize changed the direction of rotation speed and torque, change the direction of movement and change the movement forms, and other functions.Owing to the high transmission efficiency, accurate and advantages of large range of power transmission ratio, gear mechanism is widely used in industrial products, the design and manufacture level directly affects the quality of industrial products.Gear tooth buckle each gear will drive the other gears to transmit power.Separate two gears, chains can also be applied, caterpillar, on both sides of the belt to drive gear and transmission power. Basic introduction. In the application of transmission gear appeared very early.More than three hundred years BC, the ancient Greek philosopher Aristotle in the mechanical problems, it expounds the bronze or iron gear transmission problem of rotary motion.Invented in ancient China, has been applied in the entire gear train.However, the ancient gear is made of wood or metal moulds, can only transfer between shaft rotary motion, cannot guarantee the stability of transmission, the bearing capacity of the gear are also small.According to historical records, in 400 200 BC in ancient China has already started to use gear, shanxi unearthed bronze gears in our country is by far the oldest gear had been found, as a reflection of ancient science and technology achievements of this work is to gear mechanism as the core mechanism.The 17th century, people started to research, can be delivered right tooth shape of the movement.The 18th century, Europe after the industrial revolution, the application of gear transmission is increasing day by day widely；First the development of cycloidal gear, then the involute gear, until the beginning of the 20th century, involute gear has set up a file in the application. As early as in 1694, French scholar Philippe De La Hire forward involute tooth shape curve can be used as in the first place.In 1733, the French M.C amus put forward the common normal of tooth contact must be on the center of the node.A auxiliary instantaneous center line respectively along the big wheel and little wheel of the instantaneous center line (pitch) for pure rolling, and the auxiliary instantaneous center line solid coupling of auxiliary tooth shape on the big wheel and little wheel envelope formed by two tooth profile curve is conjugated to each other, this is Camus theorem.It takes into account the two tooth surface meshing state；Clearly established the modern concept about contact trajectory.In 1765, Swiss L.E uler involute profile analytic research mathematical foundation, illustrates a pair of meshing gears, the tooth profile curve of the radius of curvature and curvature center position.Later, babies further complete the method, and is now the Eu - let - babies equation.Can contribute to the application of involute tooth profile is Roteft WUlls, he put forward the centre distance change when involute gear has the advantages of the angular speed ratio unchanged.In 1873, a German engineer Hoppe is put forward, with different number of teeth of involute tooth profile of gear in the pressure Angle is changed, thus laid the ideological basis of modern shift gear. The end of the 19th century, generative principle of gear cutting method and using the principle of gear cutting machine and cutting tool appeared, after making the gear machining with the more comprehensive means, involute profile shows high more optimal sex.Teeth mesh as long as the gear cutting tools from the normal position when moving slightly, can use the standard cutter cut out the corresponding shift gears in machine tool.In 1908, the Swiss MAAG displacement method is studied and manufacturing export as processing gear shaper, later, the BSS, American AGMA, Germany DIN successively put forward many kinds of method to calculate the deflection of gear. In order to improve the service life of the power transmission gear and reduce its size, in addition to from material, heat treatment and structure improvement, the circular arc tooth profile of gear obtained the development.In 1907, the British Frank Humphris published a circular arc tooth profile at the earliest.In 1926, rui natives Eruest Wildhaber a patent on the method of surface arc tooth profile helical gears.In 1955, the Soviet unions M.L.N ovikov completed practical research of arc tooth profile gear and get the order of Lenin.In 1970, the British Rolh - Royce company engineers R.M.S tuder achieved double circular arc gear patent in the United States.This kind of gear is now increasingly attention by people, in the production of the show The benefits. Gear is to be able to mesh each other toothed machine part, its application in the field of mechanical transmission and the whole machinery is extremely broad.Modern gear technology has reached: the module of gear o. 004 100 mm；Gear diameter by 1 mm 150 m；On the transmitted power can reach hundreds of kilowatts；Speed up to hundreds of thousands of revolutions per minute；The circumference of the highest speed of 300 m/SEC. With the development of production, the gear operation stability.1674 Danish astronomer roemer first with outer cycloid tooth profile curve is put forward, in order to get stable running gear. In the 18th century industrial revolution, gear technology got rapid development, people have made a lot of research on gear.In 1733 the French mathematician card meters published profile meshing basic laws；In 1765 the Swiss mathematician euler proposed using involute tooth profile curve. Emerged in the 19th century gear hobbing machine and gear shaper, solves the problem of mass production and high precision gear.In 1900, ford for gear hobbing machine is installed on the differential device, can work out helical gear on gear hobbing machine, gear hobbing machine roll grinding wheel gained popularity, generating method processing gear of the landslide, gear involute gear become the most widely used. In 1899, pull up the first implementation of the project of the modified gear.Modified gear can not only avoid wheel tooth root cutting, can also gather together with center distance and improve the bearing capacity of the gear.In 1923 Americas Wilder Hubble first put forward the circular arc tooth profile of gear, 1955 Sue his circular-arc gear to carried on the thorough research, circular arc gear is applied in the production.The gear bearing capacity and efficiency is higher, but it is not as good as involute gear that is easy to manufacture, it remains to be further improved. Structure is introduced. Usually have a tooth, tooth, end face, the method of the surface, addendum circle and dedendum circle circle, dividing circle. 1) tooth, tooth for short, is the gear Every one for the convex part of the mesh, the convex part generally radiating arrangement, pairing the teeth of gear contact each other, can make the gears mesh continuous operation； 2) the tooth, is the space between the two adjacent teeth on the gears；End face is cylindrical or cylindrical worm gear, plane perpendicular to the axis of the gear or worm3) method, is perpendicular to the plane of the gears tooth line 4) addendum circle, is refers to the tooth top round 5) dedendum circle, refers to the bottom of the channel in the round 6) base circle, the formation of involute lines for pure rolling of round 7) dividing circle, it is in the end calculate the benchmark circular gear geometry size. Gear tooth profile can be, the gear shape, tooth shape, tooth surface and manufacturing methods such as classification. Gear tooth profile including tooth profile curve, pressure Angle, depth and deflection.Involute gear is relatively easy to manufacture, so the modern use of gear involute gear majority, with less cycloidal gear and circular-arc gear applications. In the aspect of pressure Angle, the bearing capacity of small pressure Angle gear smaller；And pressure Angle of gear, though bearing capacity is higher, but under the same in the transmission torque of bearing the load increase, so only for special situations.And gear tooth depth has been standardized, generally adopt high standard tooth.The advantage of deflection gear is more, in all kinds of mechanical equipment. In addition, the gear can also according to its shape can be divided into cylindrical gear, bevel gear, the non-circular gear, rack, worm, worm gear；According to the tooth line shape can be divided into straight gears, helical gears, herringbone gear, gear curve；According to the tooths surface is divided into external gear and internal gear；According to the manufacturing method can be divided into casting rolling gear, gear, gear cutting, sintered gear, etc. Gear manufacturing materials and heat treatment process on the gear bearing capacity and size weight has a great influence.Until the 1950 s, gear use carbon steel, the 60 s to switch to alloy steel, and multi-purpose surface hardened steel in the 70 s.According to the hardness, tooth surface can be divided into soft and hard tooth face two kinds of tooth surfaces. Bearing capacity is low, soft tooth surface gear manufacturing more easily, but good running-in, more restrictions on the size and weight without strict for transmission, and a small amount in the production of general machinery.Because the gear pairs, relatively heavy burden on small wheels, so in order to make the working life of the gear is roughly equal size, small tooth surface hardness is higher than the big wheel. Hard tooth surface gear of high bearing capacity, it is after the gear precision cutting, then quenching, surface hardening or carburizing and quenching treatment, in order to improve the hardness.But, in the heat treatment deformation of gear will inevitably produce, so after heat treatment must grind or fine cutting, grinding, to eliminate the error because of the deformation and improve the precision of gear. Material composition Commonly used steel manufacturing gear quenched and tempered steel, hardened steel, carburizing and quenching steel and nitriding steel.Slightly lower than the strength of the cast steel forging steel, used to size the larger gear；Mechanical properties of gray cast iron is bad, can be used for the open gear transmission in light load；Nodular cast iron can partially replace steel manufacturing gear；Plastic gear is used for light load and more requirements of low noise, and its gear pairs, the thermal conductivity is commonly used in steel gears. Future gear is overloaded, high speed, high precision and high efficiency, such as direction, and strive to small size, light weight, long service life and economic and reliable. And gear theory and the development of the manufacturing process will be further study the mechanism for tooth damage, this is to establish a reliable basis for the strength calculation method, is to improve the gear bearing capacity and extend the life of the gear theoretical foundation；Development represented by circular arc tooth profile of the new tooth form；Study of new gear material and the new process to make gear；Study of the elastic deformation of gear, manufacturing and installation error and the distribution of temperature field, to carry on the modification of gear tooth, so as to improve gear running stability, and increase the contact area of tooth, when loaded with so as to improve the bearing capacity of the gear. Friction and lubrication theory is a basic work in gear research and lubrication technology, research on elastic hydrodynamic pressure lubrication theory, promoting the synthetic lubricating oil and properly join extreme pressure additives in the oil, not only can improve the bearing capacity of tooth surface, and also can improve the transmission efficiency. 1, the tooth surface abrasion For open gear transmission or contain dont clean lubricating oil closed gear drive, due to the relative sliding between the meshing tooth surfaces, make some hard grinding grain into the friction surface, so that the tooth profile change, lateral clearance increased, lead to tooth gear so that the excessive thinning.In general, only when mixed abrasive in lubricating oil, will cause tooth surfaces of abrasive wear in the running. 2, tooth surface glue For high-speed heavy-load gear in the gear transmission, because of the friction between the tooth surface is larger, relative velocity, the meshing area temperature is exorbitant, once, and the bad lubrication condition between tooth surfaces of the oil film will disappear, make two tooth surface of the metal contact, mutual bonding to occur.When the two tooth face continue to relative motion, a hard tooth face will be part of the tooth surface of soft material off to form grooves along the sliding direction. 3, fatigue pitting Mutual engagement of two tooth contact, action and reaction between the tooth surface contact stress makes the work surface, the position of the mesh point is the change, and the gear do is periodic motion, so the contact stress is change according to the pulse cycle.Tooth surface for a long time under the effect of the alternating contact stress, the mark will appear small cracks in the gear tooth surface, with the passage of time, this kind of crack on the surface horizontal extension, gradually after the annular crack formation, the tooth surface of the small area of spalling and form a shallow pit some fatigue. 4, tooth broken In running projects to bear load gear as cantilever beam, its roots by the pulse of periodic stress exceeds the fatigue limit of the gear material, will produce crack in the root, and gradually expand, when unable to withstand a load transmission occurs when the rest of broken teeth phenomenon.Gear due to severe shock, partial load and in the work material Uneven may also cause the tooth broke. 5, tooth surface plastic deformation Under the impact load or overloading, tooth surface are prone to local plastic deformation, thus make involute tooth profile of the surface deformation. The development of Chinas gear industry Chinas gear industry got rapid development in the 15 during: gear industry output value in 2005 to increase 2000 yuan from 24 billion yuan in 2000, the compound annual growth rate of 23.27%, in a mechanical components has become Chinas largest industry.In terms of market demand and the scale of production, Chinas gear industry in the world ranking has been more than Italy, fourth in the world. In 2006, the Chinese all gears, transmission and drive components manufacturing enterprises achieve the cumulative gross industrial output value of 102.628183 billion yuan, a year-on-year growth of 24.15% over the same；Implementation accumulative total sales income of 98.23824 billion yuan, a year-on-year growth of 24.37% over the same；Implementation accumulative total profit of 5.66521 billion yuan, a year-on-year growth of 26.85% over the same. 1 - December 2007, the Chinese all gears, transmission and drive components manufacturing enterprises achieve the cumulative gross industrial output value of 136.542841 billion yuan, a year-on-year growth of 30.96% over the same；October 1-2008, the Chinese all gears, transmission and drive components manufacturing enterprises achieve the cumulative gross industrial output value of 144.529138 billion yuan, a year-on-year growth of 32.92% over the same. China gear manufacturing compared with the developed countries there is insufficient capacity for independent innovation, new product development is slow, the market competition, enterprise management is weak, the informationization level is low, the staff overall quality improvement.Gear industry at present stage should through the market competition and integration, improve the industry concentration, forming a group to have billions of yuan, 500 million yuan, 100 million yuan assets in large, medium and small enterprises；With independent intellectual property rights, product design and development, forming a batch of vehicle transmission system (transmission and drive axle assembly) led by enterprise, with leading enterprises supporting capacity and the power of the gear industry resource integration；Realize specialization, network, forming a large number of distinctive technique, distinctive products and rapid response ability of famous brand enterprises；Through technical renovation, to modernize the gear manufacturing enterprise transformation. At the end of the period of 11th five-year plan, China gear manufacturing sales can reach 130 billion yuan, per capita sales rose to 650000 yuan/year, industry in the world ranking of the worlds second.In 2006-2010 will be 100000 sets of new equipment, investment of about 6 billion yuan a year for new equipment, new machine 20000 units, each unit price 300000 yuan on average.By 2010, China gear manufacturing should be about 400000 various types of machine tools, among them 100000 sets of CNC machine, numerical control rate was 25% (17% higher than that of mechanical manufacture the industry average). Medium-duty truck gears Medium-duty truck gear with steel grades more in our country, mainly in order to adapt to the introduction of foreign advanced automotive technology at the time.50 s in our country from the former Soviet union, geoff medium-sized truck plant the introduction of the Soviet union (that is, the liberation brand original models) production technology at the same time, also introduced the former Soviet union in the production of automobile gear 20 crmnti steel grade. After the reform and opening up, with the rapid development of Chinas economic construction, in order to meet the requirements of the rapid development of transportation in our country, starting in the 80 s, our country in a planned way to introduce all kinds of advanced industrial developed countries, all kinds of foreign advanced medium-duty truck is introduced.At the same time, large car factory in China with foreign famous automobile companies to cooperate, the introduction of foreign advanced automobile manufacturing technology, including automobile gear production technology.At the same time, Chinas iron and steel smelting technology level has been improved, based on ladle and secondary smelting composition adjustment and continuous casting and rolling and other advanced smelting technology, makes the steel mill to produce high purity and hardenability band narrow gear steel, so as to realize the localization of the introduction of automobile gear steel, gear steel in our countrys production level on a new step.In recent years, suitable for Chinas national conditions of domestic heavy automobile gear can use nickel high hardenability steel also obtained the development and application, has obtained the good effect.Automobile gear heat treatment technology is also from the original 50-60 - s well type gas carburizing and applied to the current widely used by the computer control of continuous gas carburizing automatic line and box-type multi-purpose furnace and automatic production lines, including low pressure vacuum carburizing technology), the gear carburizing oxidation processing technology, control gear quenching cooling technology (due to the use of special oil quenching and quenching cooling technology), gear forging stock isothermal normalizing technology, etc.These technologies, not only make the gear carburizing and quenching distortion has been effectively controlled, the gear machining accuracy was improved, prolong the service life, but also can meet the needs of the modernization of the gear with the mass production of the heat treatment. Literatures, points out that the service life of automobile gear is mainly composed of two major index evaluation, one is the gear contact fatigue strength and bending fatigue strength of gear.The former is mainly decided by carburizing and quenching quality, which is mainly determined by the gear material.Therefore, it is necessary for automobile gear with the requirement of carburizing steel, properties and heat treatment characteristics a more comprehensive understanding. 9.19 chromium manganese steel and titanium boron steel Long-term since, our country is the most commonly used types of steel truck gear 20 crmnti.This is introduced in the 1950 s in China from the former Soviet union medium-sized automobile gear 18 XTR steel (i.e., 20 crmnti steel).This steel of fine grains, grain growth tendency when carburizing is small, has a good performance of carburizing and quenching, direct quenching after carburizing.Literature points out that in 1980 years ago, our country of carburized alloy structural steel, including 20 crbinti steel) in steel factory only guarantee steel was used to determine the mechanical properties, chemical composition and use but in auto production often appear when chemical composition and mechanical properties of qualified steel, due to the large hardenability can range and affect the quality of products.For example if 20 crmnti carburizing steel hardenability is too low, is made of the gear after carburizing and quenching, heart hardness is lower than the technical conditions of numerical value, fatigue test, the fatigue life of gear lower half；If high hardenability can, the gear inner hole shrinkage after carburizing and quenching which affect the gear assembly. Due to steel hardenability on the core hardness and distortion of gear has the extremely significant effect, metallurgical department in 1985 issued the guarantee of our country hardenability structural steel technical conditions (GB5216-85), in the technical conditions on the, including 20 cxmntih, 20 MNVBH steel, the chemical composition of 10 kinds of carburizing steel, hardenability data.Specified in the standard: 20 crmnti steel hardenability can be used in the manufacture of gear indicator for water-cooled end the hardness of 9 coffee place is from 30-42 HRC.After that, using 20 crmnti steel production hard was low and the distortion of gear teeth, the core is too big problem basically solved.But regardless of the size of the module of gear and steel section thickness all use the same steel grade 20 crmnti steel is obviously unreasonable.In recent years, due to the improvement of steel smelting technology in China and the improvement of alloy structural steel supply situation, has the condition of gear steel hardenability band further narrowed, and according to the different products (such as the transmission gear and rear axle gear, etc.) the requirements of the development of new steel grade to meet their requirements. Through consultation with steel mills in 1997, changchun faw has signed with the production of gear steel manufacturers will be 20 crmnti steel hardenability can FenDang supply agreement, such as liberated brand on the 5 t truck used in the manufacture of small size of cross section of the transmission shaft, intermediate shaft gear 1 and section size larger driving axle and driven bevel gear with 20 crmntih steel hardenability can category I and respectively, and the corresponding hardenability J9 respectively: 30-36 HRC and the J9 = 36 42 HRC. Around 1960, due to the tight supply of nickel, chromium steel in our country, affecting the nickel, chromium steel production in China.At a time when Chinas auto industry from the former Soviet union to introduce the technology, the Soviet union, a large amount of application of nickel, chromium steel.Therefore, when the development of Chinas auto industry to develop the boron steel, the development work, with 20 MNVB and 20 mn2tib steel instead of 20 crmnti carburizing steel gear manufacturing.This is because the add trace boron in steel (0.0001% 0.0035%) can significantly improve the hardenability of steel can, so join the trace boron in steel can substitute for a certain number of manganese, nickel, chromium, molybdenum and other precious metal elements, thus boron steel has been widely used.Changchun faw has been liberated brand automobile gear used in the production of 20 mntib and 20 mn2tib steel. Dongfeng automobile company production of dongfeng brand 5, cargo auto transmission and driving axle gear, respectively, using 20 crmnti and 20 MNVB steel manufacturing.Similarly, also signed with the steel mill, steel hardenability band narrow and along the supply agreement.Transmission and driving axle and driven bevel gear steel 20 crmntih respectively 20 MNVBH (3) and (2), 20 MNVBH (3), the corresponding hardenability can respectively 32 39 HRC and the J9 J9 = = 37 44 HRC, J9 = 34 42 HRC. The qijiang count gear works in our country has introduced the German companys heavy auto transmission gear production technology, in the domestic German company standards of development the company Cr - Mn - B boron steel gear to be successful.The hardenability of gear material can J10 = 31 39 HRC 9.19 chromium manganese steel and titanium boron steel Long-term since, our country is the most commonly used types of steel truck gear 20 crmnti.This is introduced in the 1950 s in China from the former Soviet union medium-sized automobile gear 18 XTR steel (i.e., 20 crmnti steel).This steel of fine grains, grain growth tendency when carburizing is small, has a good performance of carburizing and quenching, direct quenching after carburizing.Literature points out that in 1980 years ago, our country of carburized alloy structural steel, including 20 crbinti steel) in steel factory only guarantee steel was used to determine the mechanical properties, chemical composition and use but in auto production often appear when chemical composition and mechanical properties of qualified steel, due to the large hardenability can range and affect the quality of products.For example if 20 crmnti carburizing steel hardenability is too low, is made of the gear after carburizing and quenching, heart hardness is lower than the technical conditions of numerical value, fatigue test, the fatigue life of gear lower half；If high hardenability can, the gear inner hole shrinkage after carburizing and quenching which affect the gear assembly. Due to steel hardenability on the core hardness and distortion of gear has the extremely significant effect, metallurgical department in 1985 issued the guarantee of our country hardenability structural steel technical conditions (GB5216-85), in the technical conditions on the, including 20 cxmntih, 20 MNVBH steel, the chemical composition of 10 kinds of carburizing steel, hardenability data.Specified in the standard: 20 crmnti steel hardenability can be used in the manufacture of gear indicator for water-cooled end the hardness of 9 coffee place is from 30-42 HRC.After that, using 20 crmnti steel production hard was low and the distortion of gear teeth, the core is too big problem basically solved.But regardless of the size of the module of gear and steel section thickness all use the same steel grade 20 crmnti steel is obviously unreasonable.In recent years, due to the improvement of steel smelting technology in China and the improvement of alloy structural steel supply situation, has the condition of gear steel hardenability band further narrowed, and according to the different products (such as the transmission gear and rear axle gear, etc.) the requirements of the development of new steel grade to meet their requirements. Through consultation with steel mills in 1997, changchun faw has signed with the production of gear steel manufacturers will be 20 crmnti steel hardenability can FenDang supply agreement, such as liberated brand on the 5 t truck used in the manufacture of small size of cross section of the transmission shaft, intermediate shaft gear 1 and section size larger driving axle and driven bevel gear with 20 crmntih steel hardenability can category I and respectively, and the corresponding hardenability J9 respectively: 30-36 HRC and the J9 = 36 42 HRC. Around 1960, due to the tight supply of nickel, chromium steel in our country, affecting the nickel, chromium steel production in China.At a time when Chinas auto industry from the former Soviet union to introduce the technology, the Soviet union, a large amount of application of nickel, chromium steel.Therefore, when the development of Chinas auto industry to develop the boron steel, the development work, with 20 MNVB and 20 mn2tib steel instead of 20 crmnti carburizing steel gear manufacturing.This is because the add trace boron in steel (0.0001% 0.0035%) can significantly improve the hardenability of steel can, so join the trace boron in steel can substitute for a certain number of manganese, nickel, chromium, molybdenum and other precious metal elements, thus boron steel has been widely used.Changchun faw has been liberated brand automobile gear used in the production of 20 mntib and 20 mn2tib steel. Dongfeng automobile company production of dongfeng brand 5, cargo auto transmission and driving axle gear, respectively, using 20 crmnti and 20 MNVB steel manufacturing.Similarly, also signed with the steel mill, steel hardenability band narrow and along the supply agreement.Transmission and driving axle and driven bevel gear steel 20 crmntih respectively 20 MNVBH (3) and (2), 20 MNVBH (3), the corresponding hardenability can respectively 32 39 HRC and the J9 J9 = = 37 44 HRC, J9 = 34 42 HRC. The qijiang count gear works in our country has introduced the German companys heavy auto transmission gear production technology, in the domestic German company standards of development the company Cr - Mn - B boron steel gear to be successful.The hardenability of gear material can J10 = 31 39 HRC 9.19 chromium manganese steel and titanium boron steel Long-term since, our country is the most commonly used types of steel truck gear 20 crmnti.This is introduced in the 1950 s in China from the former Soviet union medium-sized automobile gear 18 XTR steel (i.e., 20 crmnti steel).This steel of fine grains, grain growth tendency when carburizing is small, has a good performance of carburizing and quenching, direct quenching after carburizing.Literature points out that in 1980 years ago, our country of carburized alloy structural steel, including 20 crbinti steel) in steel factory only guarantee steel was used to determine the mechanical properties, chemical composition and use but in auto production often appear when chemical composition and mechanical properties of qualified steel, due to the large hardenability can range and affect the quality of products.For example if 20 crmnti carburizing steel hardenability is too low, is made of the gear after carburizing and quenching, heart hardness is lower than the technical conditions of numerical value, fatigue test, the fatigue life of gear lower half；If high hardenability can, the gear inner hole shrinkage after carburizing and quenching which affect the gear assembly. Due to steel hardenability on the core hardness and distortion of gear has the extremely significant effect, metallurgical department in 1985 issued the guarantee of our country hardenability structural steel technical conditions (GB5216-85), in the technical conditions on the, including 20 cxmntih, 20 MNVBH steel, the chemical composition of 10 kinds of carburizing steel, hardenability data.Specified in the standard: 20 crmnti steel hardenability can be used in the manufacture of gear indicator for water-cooled end the hardness of 9 coffee place is from 30-42 HRC.After that, using 20 crmnti steel production hard was low and the distortion of gear teeth, the core is too big problem basically solved.But regardless of the size of the module of gear and steel section thickness all use the same steel grade 20 crmnti steel is obviously unreasonable.In recent years, due to the improvement of steel smelting technology in China and the improvement of alloy structural steel supply situation, has the condition of gear steel hardenability band further narrowed, and according to the different products (such as the transmission gear and rear axle gear, etc.) the requirements of the development of new steel grade to meet their requirements. Through consultation with steel mills in 1997, changchun faw has signed with the production of gear steel manufacturers will be 20 crmnti steel hardenability can FenDang supply agreement, such as liberated brand on the 5 t truck used in the manufacture of small size of cross section of the transmission shaft, intermediate shaft gear 1 and section size larger driving axle and driven bevel gear with 20 crmntih steel hardenability can category I and respectively, and the corresponding hardenability J9 respectively: 30-36 HRC and the J9 = 36 42 HRC. 9.21 the foreign advanced automobile gear steel nationalization With the introduction of advanced foreign models, all kinds of gear steel localization of gear steel in our country level to a new level.Cr - Mn steel at present, Germany, Japans Cr - Mo steel, and the United States SAE86 steel to meet the medium and small module gear steel.Domestic truck gear using the brand SAE8822H steel, such as 8 t and bevel gears adopt SAE8822H 10 t bridge, the main chemical composition of steel (mass fraction, %) of 0.19 0.25 C and 0.70 1.05 Mn and Si of 0.15 0.35, 0.35 0.75 Ni, Cr of 0.35 0.65, 0.30 0.40 Mo.Documents that control the hardenability is the key to solve the problem of distortion of gear.To reduce the distortion should choose Jominy under 4 HRC of H steel hardenability bandwidth.Using H steel precision gear after heat treatment (contact region) 70% 80% higher than ordinary steel, prolong service life.Therefore, the industrial developed country has stipulated the carburizing alloy constructional steel hardenability band.According to the need to limit hardenability band in a narrow range of (4 5 HRC).1) when you place an order in Germany can request the hardenability of steel can be in a given range, also can ask to narrow hardenability of steel.17 crnim06 very suitable for manufacturing large module heavy duty automobile gear, the main chemical composition of steel (mass fraction, %) of 0.15 0.20 C and 0.40 0.60 Mn, 1.50 1.80 Cr, Mo of 0.25 0.35, 1.40 1.70 Ni.The steel in our country has begun the production and use.Literature thought, in the 17th crnim06 steel gear carburizing process, while decrease the late carburizing carbon potential to speed up the cooling speed after carburizing, air cooled by air cooling instead, prevent the formation of large pieces of carbide, and high temperature tempering at 630 cc, carbide alloy as part of precipitation, so that at 820 second quenching to reduce residual austenite volume, eventually achieve better microstructure.2) Austrian Styer heavy car factory asked hardenability bandwidth for 7 HRC.3) Japan medium-duty truck, such as hino brand KB222 type load type 9 t cars and nissan brand CKL20DD cargo 8 t automobile transmission gear and rear axle gear is widely used in Cr - Mo steel, such as SCM420H and SCM822H steel, equivalent to the localization of 20 crmnmoh and 22 crmoh steel in our country. Can this kind of steel has high hardenability.Within a certain range, the bending fatigue life of gear with the increase of hardenability and improve.Literature points out, changchun faw started in the production of liberation brand 9 t truck rear axle gear, using 20 crmntih steel, even using steel hardenability can group (J9 = 36 42 HRC), the center of the gear tooth hardness after heat treatment and only 22 24 HRC, short of the requirements of the technical conditions of gear, the car use, rear axle driving and driven bevel gear occurred early damage.So had to choose higher Ct - Mo steel hardenability can, its main composition refer to Japanese SCM822H steel gear, the main chemical composition of the steel (mass fraction, %) as follows: 0.19 0.25 C and 0.55 0.90 Mn and Si of 0.15 0.35, 0.85 1.25 Cr, Mo of 0.35 to 0.45.After consulting with steel mills, production out of the localization of new steel grade 22 crmoh steel, its hardenability can index for the J9 = 36 42 HRC, better meet the operating requirements of automobile gear.However, the process performance of the steel is poorer, gear forging stock to after isothermal annealing treatment to machining, hardness is 156 207 hb, metallographic organization first eutectoid ferrite + false eutectoid pearlitic.This steel hardenability can be high, ordinary is prone to fire of granular bainite and granular bainite appear very adverse to machining, not only makes the tool life drastically, and since the emergence of abnormal tissue, is always accompanied by the inhomogeneity of microstructure, resulting in the increase of gear heat treatment distortion.4) in recent years, American car manufacturers to reduce production costs and improve reliability and durability of the parts, this needs the product geometric dimension and mechanical properties of highly consistent.Parts of heat treatment to improve the consistency of product performance, must reduce parts quenching after the dispersion degree of hardness, it is with steel hardenability band width degree has a direct relationship.The consistency of the hardness of the gear the core will reduce heat treatment distortion, so as