螺旋千斤顶说明书.doc

螺旋千斤顶设计计算说明书院 系 工 程 技 术 学 院 专业年级 机械设计制造及其自动化2009级2班设 计 者 王 刚 指导教师 杨 玲 成 绩 2011 年 11 月 28 日螺旋千斤顶设计任务书学生姓名王刚专业年级机械设计制造及其自动化2009级设计题目： 设计螺旋千斤顶设计条件：1、最大起重量F = 65 kN；2、最大升距H =240 mm设计工作量：1、 绘制出总装配图一张，标注有关尺寸，填写标题栏及零件明细表；2、 编写设计计算说明书一份指导教师签名： 20 年 月 日目录1螺杆的设计与计算··················································································································31.1螺杆螺纹类型选择····································································································31.2选取螺杆材料·············································································································31.3确定螺杆直径·············································································································31.4自锁验算······················································································································31.5结构································································································································41.6螺杆强度计算·············································································································41.7稳定性计算··················································································································51.7.1计算柔度·········································································································61.7.2计算稳定性····································································································62螺母设计与计算······················································································································62.1选取螺母材料·············································································································62.2确定螺母高度H¢及螺纹工作圈数u······································································62.2.1求螺母高度H¢································································································72.2.2螺纹工作圈数u·····························································································72.2.3螺母实际高度H¢····························································································72.3校核螺纹牙强度·········································································································72.4结构要求······················································································································83托杯的设计与计算··················································································································84手柄设计与计算······················································································································94.1手柄材料····················································································································104.2手柄长度Lp···············································································································104.3手柄直径dp···············································································································114.4结构·····························································································································115底座设计··································································································································12参考资料·····································································································································13螺旋千斤顶设计计算及说明结果1螺杆的设计与计算1.1螺杆螺纹类型的选择螺纹有矩形、梯形与锯齿形，常用的是梯形螺纹。

梯形螺纹牙型为等腰梯形，牙形角α=30º，梯形螺纹的内外螺纹以锥面贴紧不易松动故选梯形螺纹，它的基本牙形按GB/T5796.1—2005的规定1.2选取螺杆材料螺杆材料常用Q235、Q275、40、45、55等1.3确定螺杆直径按耐磨性条件确定螺杆中径d2求出d2后，按标准选取相应公称直径d、螺距t及其它尺寸有d2≥根据国家规定=1.2~3.5，取=1.2（梯形螺纹）；h=0.5t；查教材表5-12，[p]取20Mpa故，d2≥ = 0.8=41.5mm查机械设计课程设计手册，d取48mm，t=8mm，d1=39mm，d2=44mm1.4自锁验算自锁条件是y≤rv，式中：y为螺纹中径处升角；rv为当量摩擦角（当量摩擦角rv=arctanmv，但为保证自锁，螺纹中径处升角至少要比当量摩擦角小1°查教材表5-12，f取0.09y =arctan(t /p d2)=arctan[ 8/(3.14)] =2.88°rv=arctan（f/cosβ）=arctan[ 0.09/cos(30°/2)]=5.35°则y=2.88°

手柄孔径dk的大小根据手柄直径dp决定，dk≥dp十0.5mm为了便于切制螺纹，螺纹上端应设有退刀槽退刀槽的直径d4应比螺杆小径d1约小0.2~0.5mm退刀槽的宽度可取为1.5t为了便于螺杆旋入螺母，螺杆下端应有倒角或制成稍小于d1的圆柱体为了防止工作时螺杆从螺母中脱出，在螺杆下端必须安置钢制挡圈(GB/T891-1986)，挡圈用紧定螺钉(GB/T68-2000)固定在螺杆端部其中：1.5t=12mm d4=38.5mm D13=(1.7~1.9)d=87mm(1.4~1.6)d=72mm0.25d=0.25×48mm=12mmd+(6~10)=48+8=56mm 1.6螺杆强度计算对受力较大的螺杆应根据第四强度理论校核螺杆的强度强度计算方法参阅教材公式(5-47)，sca=≤[s]其中扭矩 =65×103×tan(2.88°+5.35°) ×44/2N·mm =206830 N·mm查机械设计课程设计手册，对40钢，=335MPa由表5-13，[s]====83.75MPad1=39mm，故，sca==62.50MPa≤[s]=83.75MPa满足强度条件1.7稳定性计算细长的螺杆工作时受到较大的轴向压力可能失稳，为此应按稳定性条件验算螺杆的稳定性。

Fcr / F³ 2.5 ~ 4螺杆的临界载荷Fc。