螺旋千斤頂設計計算說明書

1、螺旋千斤頂設計計算說明書院 系 專業(yè)年級 設 計 者 學 號 指導教師 成 績 機械設計大型作業(yè)編號01螺旋千斤頂作業(yè)任務書 姓名 專業(yè) 機制 年級 2008 班級 1 設計完成日期 2010 年 10 月 29 日指導教師 一、題目：螺旋千斤頂原始數(shù)據(jù):（請在指定的設計方案編號后劃）題目設計方案12345678910最大起重量F（kN）20253035404550556065最大起升高度H（mm）150160170180190200210220230240二、機構簡圖三、工作量1、總裝配圖一張；2、計算說明書一份。四、參考資料螺旋千斤頂設計指導書目錄1 螺桿的設計與計算··

2、;··················································

3、;··························41.1 螺桿螺紋類型選擇·····················

4、3;·················································

5、3;···41.2 選取螺桿材料·············································

6、;························ ···········41.3 確定螺桿直徑·············

7、;··················································

8、;· ················41.4 自鎖驗算·······························&

9、#183;·················································&

10、#183;·····51.5 結構···········································

11、··················································

12、51.6 螺桿強度計算················································&

13、#183;································62 螺母設計與計算···············

14、83;·················································

15、83;···············62.1 選取螺母材料································

16、3;················································62.2 確定螺母高

17、度H¢及螺紋工作圈數(shù)u···············································&#

18、183;·······62.3 校核螺紋牙強度········································&#

19、183;·····································72.4 螺母的其他尺寸··········&#

20、183;·················································&#

21、183;·················72.5 螺母與底座的配合······························&

22、#183;············································73 穩(wěn)定性計算····

23、;··················································

24、;··································83.1 計算柔度··············&#

25、183;·················································&#

26、183;·····················83.2 穩(wěn)定性計算··························

27、3;·················································

28、3;······84 托杯的設計與計算··········································

29、;····································95 手柄設計與計算············&

30、#183;·················································&

31、#183;··················95.1 手柄材料·····························

32、3;·················································

33、3;·······95.2 手柄長度Lp·········································

34、;··········································95.3 手柄直徑dp······

35、··················································

36、···························105.4 結構·····················

37、3;·················································

38、3;·····················116 底座設計···························&#

39、183;·················································&#

40、183;·············117 千斤頂?shù)男?#183;·································

41、3;·················································12 參

42、考文獻·················································

43、83;·········································12千斤頂設計計算和說明 計 算 及 說 明結 果1螺桿的設計與計算1.1螺紋牙型的選擇螺紋有矩形、梯

44、形與鋸齒形，常用的是梯形螺紋。方形螺紋作為最初的傳動螺紋，牙型為90度的正方形，傳動效率高，壓根強度差，對中性不好，磨損后間隙也無法補償。因工藝性差，目前僅用于對傳動效率有較高要求的機件。梯形螺紋牙型為等腰梯形，牙形角=30º，梯形螺紋的內外螺紋以錐面貼緊不易松動，基本牙型按GB/T5796.12005的規(guī)定。1.2選取螺桿材料螺桿材料常用Q235、Q275、40、45等。選45鋼。1.3確定螺桿直徑螺桿工作時，同時受壓力和轉矩的作用，因此它的計算可近似按緊螺栓連接的計算公式求出螺紋內徑d1，求出d1后，按標準選取相應公稱直徑d、螺距p及其它尺寸。 式中為螺桿許用壓應力。根據(jù)鋼材抗壓

45、強度近似等于抗拉強度的實踐經(jīng)驗，取s小于45號鋼的屈服極限，即s=320MPa安全系數(shù)s取4。=80MPa故，d120.34mm查機械設計手冊，d取36mm，p取7mm，內徑d1=30mm符合強度要求1.4自鎖驗算理論上自鎖條件為，式中為螺紋中徑處升角；為當量摩擦角。由于影響的因素較多，其值不穩(wěn)定，為自鎖可靠，實際應滿足的自鎖條件為=arctan(f/cos）=/2f為摩擦系數(shù)，在后面選螺母的材料為青銅，鋼對青銅的摩擦系數(shù)f=0.09y=arctan(n p / p d2)=arctan（17/3.1433）故，y=3.86°<r-1°1.5結構 螺桿上端用于支承托杯

46、和在其中插裝手柄，因此需加大直徑，其結構見圖。手柄孔徑根據(jù)手柄直徑確定，mm。為了便于切制螺紋，螺桿上應有退刀槽，退刀槽的直徑應比小約0.20.5mm，退刀槽的寬度取為1.5P。為了便于螺桿旋入螺母，螺桿端部應有倒角或制出稍小于的圓柱形凸臺。為了防止工作時螺桿從螺母中脫出，在螺桿的下端必須安置鋼制擋圈(GB/T891-1986)，擋圈用螺釘固定在螺桿端部，尺寸見圖。其中：1.5p=10.5mm(1.41.6)d=1.5d=54mm1.6螺桿強度計算螺桿材料的許用應力值:71118.333MPa計算當量應力值=52.289MPa，小于許用應力值，因此強度校核通過2. 螺母設計與計算2.1選取螺母

47、材料螺母一直處于高應力作用下，材料此處選擇用青銅ZCuAl10Fe3制造2.2確定螺母高度H¢及螺紋工作圈數(shù)u螺紋圈數(shù)Z和螺母高度H 螺母的螺紋圈數(shù)通常根據(jù)螺紋牙間壓力條件求出，即式中，為螺紋中徑；h為螺紋牙高度；p為螺紋牙表面許用壓力，其值可查閱教材或手冊。考慮到退刀槽的影響，實際螺紋圈數(shù)為ZZ1.5由于載荷在螺紋牙間分配不均，故螺紋圈數(shù)Z不宜大于10，否則應改選螺母材料或加大d值。螺母高HZP 2.3校核螺紋牙強度一般螺母的材料強度低于螺桿，故只校核螺母螺紋牙的強度。材料許用切應力 取 30 40 MPa材料許用彎曲應力b 取 40 60 MPa螺紋牙底寬度 b=2.562mm根

48、據(jù)公式： 計算得：螺桿的抗剪強度 =8.4061 MPa<螺桿的抗彎強度 b=5.225 MPa < b校核通過2.4螺母的其他尺寸螺母其它尺寸見圖。其中；。其中d為內螺紋大徑，d=37mm。2.5螺母與底座的配合 螺母壓入底座上的孔內，圓柱面配合常采用H8/r7或H8/n7。為了安裝簡便，應在螺母下端和底座孔上端加工出倒角。為了防止螺母轉動，還應安置緊定螺釘，其直徑可根據(jù)起重量取M6M12。3 螺桿穩(wěn)定性計算細長的螺桿工作時受到較大的軸向壓力可能失穩(wěn)，為此應按穩(wěn)定性條件驗算螺桿的穩(wěn)定性。Fcr / F ³ 2.5 4螺桿的臨界載荷Fcr與柔度s有關，s=m l/i，m為螺桿的長度系數(shù)，與螺桿的端部結構有關，l為舉起重物后托杯底面到螺母中部的高度，可近似取，i為螺桿危險截面的慣性半徑，若危險截面面積A=pd12/4，則(I為螺桿危險截面的軸慣性矩)3.1計算柔度 （1）計算螺桿危險截面的慣性半徑i=7.5mm（2）求起重物后托杯底面到螺母中部的高度l=150+22.7