本文關(guān)鍵詞： 粉末冶金中空凸輪軸 粘結(jié)處理 生坯裝配 滾花參數(shù)　出處：《北京有色金屬研究總院》2017年碩士論文　論文類型：學位論文

【摘要】：燒結(jié)組合式粉末冶金中空凸輪軸是一種輕量化、高性能的新型凸輪軸。在大力提倡節(jié)能環(huán)保的趨勢下,燒結(jié)組合式粉末冶金中空凸輪軸具有質(zhì)量輕、耐磨性好、設計靈活等優(yōu)點,發(fā)展前景十分廣闊。粉末冶金材料生坯強度低,脆性大,因此凸輪片容易在運輸、裝配過程發(fā)生破損甚至破裂。目前燒結(jié)組合式粉末冶金中空凸輪軸在裝配時需要對凸輪進行預燒處理,增加了工序和設備投入,同時使得能耗增加、尺寸精度變差,導致生產(chǎn)成本提高,因此實現(xiàn)凸輪的生坯裝配是一個亟待解決的難題。本文通過粘結(jié)處理工藝向粉末中添加具有高本征力學性能的粘結(jié)劑,以提高凸輪軸粉末的工藝性能和生坯力學性能,實現(xiàn)凸輪軸生坯的自動裝配工藝。本文對多種粘結(jié)劑樹脂進行了對比和改性研究,確定了粘結(jié)劑種類和用量并對比了粘結(jié)劑處理后粉末性能。通過對粉末壓制工藝和壓坯性能的研究,優(yōu)化了生坯固化工藝,獲得了更高強度和韌性的凸輪生坯。在對裝配過程中的滾花參數(shù)進行適當優(yōu)化后實現(xiàn)了粉末冶金中空凸輪軸的生坯自動裝配,并進行燒結(jié)實驗。得到以下結(jié)論:1)研究了粘結(jié)劑種類對生坯力學性能的影響,并通過共混反應將25 wt.%的熱塑性樹脂TP與75 wt.%的熱固性樹脂W6混合,獲得了綜合力學性能優(yōu)異的WT25粘結(jié)劑,加入1.0wt.%此改性粘結(jié)劑的粉末生坯強度達到了 36.1MPa,拉伸強度達到了 8.7MPa,拉斷變形率為2.6‰,與W6相比,提高了近10倍。2)研究了粘結(jié)劑含量(0～3.0 wt.%)對粉末性能的影響。當粘結(jié)劑的含量為1.0 wt.%時,具有最佳的綜合工藝性能,流動性為30s/50g,松裝密度為2.7g/cm3,細粉粘結(jié)率由25%提高到了 96%,表征成分偏析性的石墨變異系數(shù)由8.6%降低至1.2%。3)研究了固化工藝對生坯力學性能的影響。隨著固化溫度提高和固化時間的延長,生坯綜合力學性能提高,超過210℃后將導致粘結(jié)劑失效。最佳固化工藝為150℃保溫150min,此時生坯強度達到39.3MPa,拉伸強度達到9.6MPa,拉斷變形率為2.8‰。4)利用正交試驗研究了凸輪裝配過程中的滾花齒高,齒長和齒間距對凸輪表面應變的影響。當齒高為0.04mm,齒長為8mm,齒間距為0.6mm時,凸輪裝配時應變最小,為120μm/mm。在此條件下裝配,凸輪不易開裂,產(chǎn)品更加穩(wěn)定。5)用凸輪軸自動裝配機在最佳裝配參數(shù)下對凸輪進行了生坯裝配。裝配后的凸輪軸的凸輪角度和軸向位置合格率為100%,而凸輪表面開裂概率僅為1.3%,實現(xiàn)了凸輪生坯的自動裝配。6)生坯裝配的凸輪軸經(jīng)燒結(jié)后凸輪密度達到7.6g/cm3,凸輪硬度達到55HRC以上,凸輪與軸管間的焊接扭矩約為1000N·m。
[Abstract]:Sintered composite powder metallurgy hollow camshaft is a new type camshaft with lightweight and high performance. Under the trend of promoting energy saving and environmental protection, sintered composite powder metallurgy hollow camshaft has light weight and good wear resistance. Due to the advantages of flexible design and wide prospect of development, the powder metallurgy material has low strength and high brittleness, so the cam sheet is easy to be transported. The assembly process is damaged or even broken. At present, it is necessary to pre-fire the cam in the assembly of the sintered composite powder metallurgy hollow camshaft, which increases the process and equipment input, increases the energy consumption, and makes the dimension precision worse. Therefore, it is an urgent problem to realize the assembly of cam billet. In this paper, binder with high mechanical properties is added to the powder by bonding process. In order to improve the technological properties and mechanical properties of camshaft powder and realize the automatic assembly process of camshaft billet, this paper compares and modifies many kinds of binder resins. The type and amount of binder were determined and the properties of powder treated with binder were compared. The solidification process of raw billet was optimized through the study of powder pressing technology and compaction properties. Cam billet with higher strength and toughness is obtained. The blank of powder metallurgy hollow camshaft is automatically assembled after proper optimization of knurling parameters in assembly process. The effect of binder on the mechanical properties of green billet was studied, and the 25 wt.% TP and 75 wt.% thermosetting resin W6 were mixed by blending reaction. The WT25 binder with excellent mechanical properties was obtained. The strength of the powder billet was 36.1 MPA, the tensile strength was 8.7 MPA, and the tensile deformation rate was 2.6 鈥，

本文編號：1554245