设计液压专用钻床的液压系统

湖南农业大学工学院课程设计说明书课程名称：液压与气压传动题目名称：设计液压专用钻床的液压系统班级：20级专业班姓名：学号：指导教师：评定成绩：教师评语：2011-4-302目录一、设计要求及设计参数··············································································31、设计要求·····················································································32、设计参数·······················································································3二、负载与运动分析····················································································31、负载分析·······················································································3A)夹紧缸·······················································································3B)工作台液压缸··············································································42、运动分析·······················································································43、负载图F-t和速度图v-t图的绘制························································5三、确定液压系统主要参数···········································································51、液压缸的选定·················································································5A)夹紧缸·······················································································5B)工作台液压缸··············································································52、活塞杆稳定性校核···········································································73、液压缸各运动阶段的压力，流量和功率···············································7A）夹紧缸····················································································7B）工作台液压缸···········································································84、液压缸的工况图··············································································9四、拟定液压系统原理图··············································································10五、液压元件的选择····················································································111、确定液压泵的规格和电动机的功率······················································112、选择阀类元件及辅助元件··································································11六、液压系统发热与升温的验算·····································································123一、设计要求及设计参数1．设计要求设计一台用成型铣刀在加工件上加工出成型面的液压专用铣床，工作循环：手工上料——自动夹紧——工作台快进——铣削进给——工作台快退——夹具松开——手工卸料。2．设计参数设计参数如下：工作台液压缸负载力（KN）：FL=9.8KN工作台液压缸移动件重力（KN）：G=2.5KN工作台快进、快退速度（m/min）：V1=V3=5.5m/min工作台工进速度（mm/min）：V2=48mm/min工作台液压缸快进行程（mm）：L1=280mm工作台液压缸工进行程（mm）：L2=80mm工作台启动时间（S）：t=0.5s夹紧液压缸负载力（KN）：FC=4.8KN夹紧液压缸负移动件重力（N）：GC=60N夹紧液压缸行程（mm）：LC=10mm夹紧液压缸运动时间（S）：tC=1s导轨面静摩擦系数：μC=0.2导轨面动摩擦系数：μd=0.1FLFcGGcV1V2L1L2Lctc9.84.82.5605.54828080101二、负载与运动分析1、负载分析A)夹紧缸工作负载：NGFFdCCl48061.0604800由于夹紧缸的工作对于系统的整体操作的影响不是很高，所以在系统的设计计算中把夹紧缸的工作过程简化为全程的匀速直线运动，所以不考虑夹紧缸的惯性负载等一些其他的因素。B)工作台液压缸1、工作负载工作负载极为切削阻力FL=9.8KN。2、摩擦负载摩擦负载即为导轨的摩擦阻力：(1)静摩擦阻力NGFcfs50025002.0(2)动摩擦阻力NGFdfd25025001.043、惯性负载NDvgGtvgGFti77.465.060/5.58.92500)0(14、运动时间快进svLt0545.360/105.52803111工进svLt667.10660/4580222快退svLLt927.360/105.58028033213假设液压缸的机械效率9.0cm，得出液压缸在各工作阶段的负载和推力，如表1所示。表1液压缸各阶段的负载和推力工况负载组成液压缸负载F/N液压缸推力NFFcm0启动fsFF500555.56加速ifdFFF296.77329.74快进fdFF250277.8工进LfdFFF1005011166.67反向启动fsFF500555.56加速ifdFFF296.77329.74快退fdFF250277.82、运动分析手工上料—按按钮加紧缸自动加紧—按按钮工作台快进—工作台切削进给—工作台快退—按按钮松开夹具—卸料53、负载图F-t和速度图v-t图的绘制三、确定液压系统主要参数1、液压缸的选定A)夹紧缸根据负载选择液压缸的执行压力p=1MPa。2361081.41014806mpFAmmAD3.781081.4443根据GB\T2348-1993规定,D取80mm。根据稳定性校核LC/d10时，液压缸能满足稳定性条件，LC=10mm,,这里取d=40mm。6液压缸的有效作用面积：有杆腔：2322'11077.34/)(mdDA无杆腔：232'21003.54/mDA此时实际工作压力为：MPaMPaAFp1955.0'2，所以选取工作压力1MPa满足要求。B)工作台液压缸所设计的动力滑台在工进时负载最大，参考表2和表3，初选液压缸的工作压力p1=2.5MPa.表2按负载选择工作压力负载/KN55~1010~2020~3030~5050工作压力/MPa0.8~11.5~22.5~33~44~55表3各种机械常用的系统工作压力机械类型机床农业机械小型工程机械建筑机械液压凿岩机液压机大中型挖掘机重型机械起重运输机械磨床组合机床龙门刨床拉床工作压力/MPa0.8~23~52~88~1010~1820~32鉴于动力滑台快进和快退速度相等，这里的液压缸可选用单活塞杆式差动液压缸（A1=2A2），快进时液压缸差动连接。工进时为防止车铣时负载突然消失发生前冲现象，液压缸的回油腔应有背压，参考表4选定背压为MPap8.02，而液压缸快退时背压取0.5Mpa由式02211FApAp得23621011032.510)28.02(67.111662mppFA则活塞直径mmmAD3.821023.81415926.31032.544231参考表5及表6，mmDd4.563.8271.071.0，取标准值得mmdmmD56,80。由此求得液压缸两腔的实际有效面积：7无杆腔：232211003.5408.04mDA有杆腔：23222221056.2056.008.044mdDA实际工作压力为：MPaMPaAFp5.22.210，即选取工作压力2.5MPa满足要求。工进时采用调速阀调速，其稳定流量min/24.0minLq，设计要求最低工进速度min/482mmv，经验算1232min105Amvq合格。表4执行元件背压力系统类型背压力/MPa简单系统或轻载节流调速系统0.2~0.5回油路带调速阀的系统0.4~0.6回油路设置有背压阀的系统0.5~1.5用补油泵的闭式回路0.8~1.5回油路较复杂的工程机械1.2~3回油路较短且直接回油可忽略不计表5按工作压力选取d/D工作压力/MPa≤5.05.0~7.0≥7.0d/D0.5~0.550.62~0.700.7表6按速比要求确定d/D12/vv1.151.251.331.461.612d/D0.30.40.50.550.620.71注：1—无杆腔进油时活塞运动速度；2—有杆腔进油时活塞运动速度。2、活塞杆稳定性校核A)夹紧缸由于夹紧缸的活塞杆直径是利用稳定性校核来计算的，所以不需要进行校核。B)工作台缸因为活塞杆的总行程为360mm，活塞杆的直径是56mm，所以L/d=6.4510，所以满足稳定性要求。3、液压缸各运动阶段的压力，流量和功率A)夹紧缸（23'223'11003.5,1077.3mAmA）回油路背压为0.5Mpa夹紧时：smLvAqc/3.50110101003.533'2'28MPaAFpl95.0'2'2，WqpP8.47'2'2'2放松时：smLvAqc/7.37110101077.333'1'1MPaAApGpcd67.01077.3251563'12'2'1，WqpP3.251''1'2B)工作台液压缸分析可知，快进时，液压缸无杆腔进油，压力为p1；有杆腔回油，压力为p2。快退时，液压缸有杆腔进油，压力为p1；无杆腔回油，压力为p2。由于液压缸是差动连接，回油口到进油口之间的压力损失取MPap5.0。快退时，回油路的背压取0.5MPa，即MPap5.02。表7液压缸各工