千斤顶设计计算说明书.doc

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1、.工业大学机械设计作业设计计算说明书题目：设计螺旋起重器（千斤顶）系别：班号：：日期：2014.10.12..工业大学机械设计作业任务书题目：设计螺旋起重器设计原始数据：起重量：FQ=30KN最大起重高度：H=180mm..目录1.选择螺杆、螺母的材料·······································32.耐磨性计算··················································33.螺杆强度校核················································44.螺母螺纹牙的强度校核·

2、·····································45.自锁条件校核················································56.螺杆的稳定性校核···········································57.螺母外径及凸缘设计·········································68.手柄设计····················································69.底座设计···························

3、·························710.其他零件设计··············································811.绘制螺旋起重器（千斤顶）装配图·························812.参考文献···················································8..1.选择螺杆、螺母的材料考虑到螺杆承受重载，需要有足够的强度，因此选用45钢，需要调质处理。由参考文献[3]表10.2查得45钢的抗拉强度σb=600MPa，屈服强度σs=355MPa。螺母是在重载低速的工况下使用

4、的，并且要求与螺杆材料配合时的摩擦系数小、耐磨，因此，螺母的材料选择铸造铝青铜ZCuAl10Fe3。2.耐磨性计算螺杆选用45钢，螺母选用铸造铝青铜ZCuAl10Fe3，由参考文献[1]表5.8查得，钢对青铜的许用压强[p]=18~25MPa，由表5.8注释查得，人力驱动时，[p]值可提高约20%，即[p]=21.6~30MPa,取[p]=25MPa。由参考文献[1]表5.8查得，对于整体式螺母，系数ψ=1.2~2.5，取ψ=2.5。按照耐磨性条件设计螺杆螺纹中径d2，选用梯形螺纹，则螺纹的耐磨性条件为ps=≤[p]计算螺纹中径d2时，引入系数ψ=以消去H，得d2≥对于梯形螺纹，h

5、=0.5p，则d2≥==19.6mm以上三式中，FQ—螺旋的轴向载荷，N；p—螺距，mm；d2—螺纹中径，mm；h—螺纹工作高度，mm；H—螺母旋合高度，mm；ps—螺纹工作面上的压强，MPa；[p]—许用压强，MPa。根据螺纹中径d2的取值围，由文献[3]表11.5查得，取螺杆的公称直径d=32mm，螺距p=6mm，中径d2=29mm，小径d1=25mm，螺纹大径D4=33mm。说明：此处如果选择螺杆的公称直径d=24mm，螺距p=3mm，中径d2=22.5mm，小径d1=20.5mm，螺纹大径D4=24.5mm，螺杆的强度校核不满足要求。3.螺杆强度校核..螺杆的断面承受轴向载

6、荷FQ和螺纹副摩擦转矩T1。根据第四强度理论，螺杆危险截面的强度理论为σ=≤[σ]式中：FQ—轴向载荷，N；d1—螺纹小径，mm；T1—螺纹副摩擦力矩，N·mm，T1=FQtan(ψ+ρ’）；[σ]—螺杆材料强度的许用应力，MPa，[σ]=。查参考文献[1]表5.10，钢对青铜的当量摩擦系数f‘=0.08~0.10,取f‘=0.09，则螺纹副当量摩擦角ρ’=arctanf‘=arctan0.09=5.1427°。ψ为螺纹升角，ψ=arctan=arctan=3.7679°。把已知的数据带入T1的计算公式中，则得T1=30000tan(3.7679°+5.1427°)=68201N·

7、mm代入强度计算公式，则σ==72.2MPa由参考文献[1]表5.9可以查得螺杆材料的许用应力[σ]=，σs=355MPa，[σ]=71~118MPa,取[σ]=95MPa。显然，σ≤[σ]，螺杆满足强度条件。4.螺母螺纹牙的强度校核由系数ψ=可求得螺母的旋合高度H=ψ×d2=2×29=58mm。螺母螺纹牙根部的剪切强度条件为τ=≤[τ]式中：FQ—轴向载荷，N；D4—螺母螺纹大径，mm；Z—螺纹旋合圈数，Z===9.7，取Z=10；..b—螺纹牙根部厚度，对于梯形螺