發(fā)布時(shí)間：2019-05-12 08:58

【摘要】：螺桿轉(zhuǎn)子是螺桿壓縮機(jī)的核心零件,其截面齒形由多段曲線組成,齒形復(fù)雜非對(duì)稱,其螺旋齒形具有螺距大,螺旋升角大和齒形高度大的特點(diǎn)。螺桿轉(zhuǎn)子的傳統(tǒng)加工方式為切削加工,但切削時(shí)60%以上材料被去除,材料利用率低,同時(shí)加工耗時(shí)長(zhǎng),生產(chǎn)效率低。 為進(jìn)一步改善螺桿轉(zhuǎn)子的工藝水平,提出定軸橫軋螺桿轉(zhuǎn)子的塑性成形新工藝,將螺桿轉(zhuǎn)子的非對(duì)稱大螺旋齒形和階梯臺(tái)階在一個(gè)軋制過程中直接成形,提高其生產(chǎn)效率和材料利用率。選用易切削鋼SAE1141做為軋制材料,其切削性能好,利于后續(xù)機(jī)加工的進(jìn)行。課題采用理論分析、有限元模擬和軋制實(shí)驗(yàn)相結(jié)合的方法,對(duì)螺桿陰轉(zhuǎn)子的定軸橫軋成形工藝展開研究。 通過高溫壓縮實(shí)驗(yàn),對(duì)易切削鋼SAE1141在不同變形條件下的熱流變行為進(jìn)行了實(shí)驗(yàn)測(cè)定�？紤]應(yīng)變量的影響,建立了易切削鋼SAE1141的應(yīng)變修正的Arrhenius本構(gòu)方程,實(shí)現(xiàn)了對(duì)其流變應(yīng)力行為的良好預(yù)測(cè)。 基于空間嚙合原理和矩陣?yán)碚?建立了與模具和軋件實(shí)時(shí)變化的共軛運(yùn)動(dòng)關(guān)系相關(guān)聯(lián)的模具輥型曲線的通用求解方程,實(shí)現(xiàn)了模具輥型曲線的變參數(shù)化設(shè)計(jì)。構(gòu)建得到的符合軋制工藝要求的軋件型線不同于產(chǎn)品原始型線,與原始產(chǎn)品形狀大體保持一致,相應(yīng)精整階段的模具輥型曲線根據(jù)軋制嚙合關(guān)系進(jìn)行求取。 對(duì)大螺旋齒形的軋制成形過程進(jìn)行研究,提出了等型角增長(zhǎng)和變型角增長(zhǎng)的兩種螺旋齒形成形方案,相應(yīng)提出浮動(dòng)結(jié)點(diǎn)法和固定結(jié)點(diǎn)法兩種模具輥型曲線設(shè)計(jì)方案�；诓煌＞咻佇颓�設(shè)計(jì)方案和坯料參數(shù)確定方法,通過有限元仿真模擬分析表明,坯料長(zhǎng)度按照螺旋齒形部分長(zhǎng)度選取,采用固定結(jié)點(diǎn)法方案進(jìn)行模具輥型曲線設(shè)計(jì),軋制過程中金屬變形均勻,齒形長(zhǎng)起能力強(qiáng),適合與楔橫軋工藝配合使用。根據(jù)大螺旋齒形的成形特點(diǎn),提出變齒形、變齒高的螺旋輥型模具設(shè)計(jì)方法,軋制時(shí)保證了模具和軋件的良好嚙合。螺旋輥型模具由多組變導(dǎo)程、變螺旋升角的螺旋凸棱組成,單個(gè)螺旋凸棱的高度漸進(jìn)升高；沿軸向方向,模具螺旋凸棱的高度一致。 通過有限元軟件DEFORM對(duì)大螺旋齒形軋制成形過程進(jìn)行了仿真模擬分析,揭示了軋制變形區(qū)金屬的流動(dòng)特點(diǎn)；軋制螺桿陰轉(zhuǎn)子時(shí),應(yīng)采用與其工作嚙合時(shí)相反的旋向進(jìn)行軋制,利于金屬向徑向齒高方向流動(dòng)。 在上述研究基礎(chǔ)上,利用UG軟件編程完成了螺旋輥型模具的加工制造。通過軋制實(shí)驗(yàn)首次實(shí)現(xiàn)了螺旋升角為45°20′、齒高比例達(dá)45.5%的非對(duì)稱大螺旋齒形和階梯臺(tái)階的直接軋制成形,得到的螺桿陰轉(zhuǎn)子尺寸符合要求、內(nèi)部質(zhì)量合格,表明相關(guān)研究工作的結(jié)論是正確的,定軸橫軋螺桿陰轉(zhuǎn)子的工藝是可行的。相比于傳統(tǒng)切削工藝,定軸橫軋新工藝的節(jié)材率可達(dá)39%,凈軋制耗時(shí)僅5-8s,具有較好的經(jīng)濟(jì)效益和實(shí)用價(jià)值。
[Abstract]:Screw rotor is the core part of screw compressor. Its section tooth profile is composed of multi-segment curve, the tooth profile is complex and asymmetrical, and its spiral tooth profile has the characteristics of large pitch, large spiral lift angle and large tooth profile height. The traditional machining method of screw rotor is cutting, but more than 60% of the materials are removed, the utilization rate of materials is low, and the processing time is long and the production efficiency is low. In order to further improve the process level of screw rotor, a new plastic forming process of screw rotor with fixed axis cross rolling is put forward, and the asymmetric large spiral tooth profile and step of screw rotor are formed directly in one rolling process. Improve its production efficiency and material utilization rate. Easy cutting steel SAE1141 is selected as rolling material, and its cutting performance is good, which is beneficial to subsequent machining. In this paper, the forming process of screw negative rotor with fixed axis cross rolling is studied by means of theoretical analysis, finite element simulation and rolling experiment. The thermal Rheological behavior of easy cutting steel SAE1141 under different deformation conditions was measured by high temperature compression experiment. Considering the influence of strain variables, the strain modified Arrhenius constitutive equation of easy cutting steel SAE1141 is established, and the flow stress behavior of easy cutting steel is predicted well. Based on the principle of spatial meshing and matrix theory, the general solving equation of die roll profile curve related to the conjugated motion relation of die and rolling piece in real time is established, and the variable parameter design of die roll profile curve is realized. The rolling profile constructed in accordance with the requirements of rolling process is different from the original profile of the product and is generally consistent with the shape of the original product. The roll profile curve of the die in the corresponding finishing stage is obtained according to the rolling meshing relationship. In this paper, the rolling forming process of large spiral tooth profile is studied, and two kinds of spiral tooth forming schemes with equal angle increase and variable angle growth are put forward, and two kinds of die roll curve design schemes, floating node method and fixed node method, are put forward accordingly. Based on the design scheme of different die roll profile curve and the determination method of billet parameters, the finite element simulation analysis shows that the blank length is selected according to the partial length of spiral tooth profile, and the fixed node method is used to design the die roll profile curve. In the rolling process, the metal deformation is uniform and the tooth shape is long, so it is suitable for use in combination with cross wedges rolling process. According to the forming characteristics of large spiral tooth profile, the design method of spiral roll die with variable tooth shape and variable tooth height is put forward, which ensures the good meshing between die and rolling piece during rolling. The screw roll die is composed of many groups of helix convex edges with varying lead and angle, and the height of a single spiral convex edge is gradually increased, and along the axial direction, the height of the screw convex edge of the die is consistent. The forming process of large spiral tooth profile rolling is simulated and analyzed by finite element software DEFORM, and the flow characteristics of metal in rolling deformation zone are revealed. When rolling screw negative rotor, the opposite rotation direction should be used to roll the screw negative rotor, which is beneficial to the flow of metal in the direction of radial tooth height. On the basis of the above research, the machining and manufacturing of spiral roll die is completed by using UG software. The direct rolling forming of asymmetric large spiral tooth profile and step with spiral lift angle of 45 擄20 and tooth height ratio of 45.5% is realized for the first time through rolling experiment. the size of the screw negative rotor meets the requirements and the internal quality is qualified. The results show that the conclusion of the related research work is correct and the process of fixed axis cross rolling screw negative rotor is feasible. Compared with the traditional cutting process, the material saving rate of the new fixed axis cross rolling process can reach 39%, and the net rolling time is only 5 脳 8 s, which has better economic benefit and practical value.
【學(xué)位授予單位】：北京科技大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TG335.19

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