[哈爾濱工業(yè)大學(xué)]機(jī)械設(shè)計(jì)基礎(chǔ)第8章習(xí)題精解與答題技巧

1、226機(jī)械原理試題精選與答題技巧8.3例題精解及答題技巧例8181如例81(a)圖示轉(zhuǎn)盤具有四個(gè)圓孔，其直徑和位置為，mmd701?，，，，，mmd1202?mmd1003?mmd1504?mmr2401?mmr1802?，；，，；，mmr2503?mmr1904??5012???7023???8034??mmD780?。今在其上再制一個(gè)圓孔使之平衡，其回轉(zhuǎn)半徑，求該圓孔的直徑mmt40?mmr300?和位置角。例81(a)圖例81(b

2、)圖解題要點(diǎn)：解題要點(diǎn)：剛性轉(zhuǎn)子靜平衡的概念和平衡條件。解：解：要使轉(zhuǎn)盤達(dá)到平衡，應(yīng)使0)(4224232221?????????rrrrrr4321idddddvtQi?式中為轉(zhuǎn)盤材料的比重v今計(jì)算各圓孔的直徑平方與向徑值的相乘積如下：；32211176247cmrd???3222225921812cmrd???；3232325002510cmrd???3242442751915cmrd???取比例尺，分別算出代表各圓孔的直徑平方與其

3、向徑值的相乘積的圖上長(zhǎng)mmcmW3100??度為mmrdWW76.1110011761211????mmrdWW92.2510025922222????mmrdWW2510025003233????1W2W3W4WW?228機(jī)械原理試題精選與答題技巧cmNLLLLLrQrQ??????????????300020202020203015034231234232222cmNLLLLrQrQ????????????33.1333202020

4、2020200342312343333044???rQ在平衡基面ⅡⅡ中各重徑積的分量為0111111?????????rQrQrQcmNrQrQrQ?????????????1500300030150222222cmNrQrQrQ?????????????67.266633.133320200333333cmNrQrQrQ?????????????30000301004444442平衡基面ⅠⅠ中的平衡重量Q?在平衡基面ⅠⅠ中加了平衡重量

5、達(dá)到平衡，應(yīng)使Q?04321???????????????????rrrrrr4321iQQQQQQi取比例尺，分別算出代表重徑積的分量的圖上長(zhǎng)度為mmcmNW??100?；mmrQWW401004000111???????mmrQWW301003000222???????；mmrQWW333.1310033.1333333???????04??W作矢量多邊形如例82(a)圖，則封閉矢量即代表在平衡基面ⅠⅠ中應(yīng)加的平衡重量W?的重徑積，

6、由矢量圖上量得，故得Q?mmW29??cmNWrQW?????????290029100?已知，則cmr50??29005850WWQNr????????的方位角也由該矢量圖上量得rQ??（由沿順時(shí)針?lè)较蛄康降慕牵?117???1r??1Qr??Q3求平衡基面ⅡⅡ中的平衡重量Q??在平衡基面ⅡⅡ中加了平衡重量達(dá)到平衡，應(yīng)使Q??04321????????????????????????????????rrrrrr4321iQQQQQQ