【正文】 m/n 則 60Vm/hn 本科機械畢業(yè)設計論文 CAD 圖紙 401339828 17 Vm—— 機器前進速度， Vm=6Km/h h—— 余擺線縱寬 (刀片工作刃線長度 :) n一割刀轉(zhuǎn)速， n=1833r/min m=(60X6)/()= 由于考慮到制造的方便和運轉(zhuǎn)的平衡問題，刀片數(shù)量確定為 3片。傾角，刀盤和導草罩隨刀盤軸一起旋轉(zhuǎn)時，刀片甩出割草。上刀盤與轉(zhuǎn)軸無相對運動，可知上刀盤的轉(zhuǎn)速與轉(zhuǎn)軸相同且為 1833r/min，則刀片轉(zhuǎn)速也為1833r/min。 （ 3） V 帶尺寸選取 根據(jù)拖拉機和割草機的結構，初步選取中心距 =950mm 根據(jù)公式計算所需基準長 度： /4a0 =(2950+)/2(140+110)+950 =2293mm 由表差值選取帶的基準長度為 Ld=2280mm，公稱長度 Li=2240mm 計算實際中心距 a： a=/2=[950+(2293 一 2280)]/2= 選取中心距為 a=944mm 本科機械畢業(yè)設計論文 CAD 圖紙 401339828 22 錐齒輪傳動設計 錐齒輪傳動為第二級傳動，其傳動比為 1，故主、動齒輪結構尺寸相同。 =118， =3OMPa 主 軸的傳動效率為： ≥ mm 由于軸上開鍵槽，考慮鍵槽對軸的強度削弱，應增大軸徑，一般有一個鍵槽本科機械畢業(yè)設計論文 CAD 圖紙 401339828 24 時，軸頸增大 5%左右，有兩個鍵槽時應增大 10%左右，然后圓整為標準直徑，因此圓整成 主軸結構圖如下圖所示 44主軸結構圖 二、軸的受力分析與強度校核 1輸入軸（左邊）的受力分析和載荷 圖 45受力簡圖 錐齒輪的受力分析 /= 本科機械畢業(yè)設計論文 CAD 圖紙 401339828 25 圖 46YOZ平面內(nèi)載荷分布及 YOZ平面的彎矩圖 帶入數(shù)據(jù)解得： 本科機械畢業(yè)設計論文 CAD 圖紙 401339828 26 圖 47XOY平面內(nèi) 載荷分布及 XOY平面的彎矩圖 =0 帶入數(shù)據(jù)解得 按第四強度理論校核 帶入數(shù)據(jù)解得： 強度足夠 同理校核主軸和左軸的強度滿足要求 四連桿掛接機構設計 機具通過平行四連桿機構與小四輪拖拉機前端懸掛起來，同時，通過液壓提升四連桿的運動，來實現(xiàn)切割器的起落，根據(jù)機具結構和拖拉機結構尺寸，其結構如下圖所示 本科機械畢業(yè)設計論文 CAD 圖紙 401339828 27 圖 48機具掛接機構示意圖 原理說明： 圖中所示的機構為平行四邊形機構。 2020 本科機械畢業(yè)設計論文 CAD 圖紙 401339828 31 外文文獻 1 Bales twine knitter with adjustable wiper Background of the invention This invention relates to twine knitters for hay or straw baling machines and more particularly to an improved wiper arm for such knitters. In one conventional baler, the twine knitter includes a rotatable mounted billhook for forming a loop of twine thereabout. On one side of the billhook is a wiper arm which has a pair of finders defining a fork for receiving and guiding twine used to tie a bale? On one side of the billhook is a knife riveted to the fork for cutting the twine after a loop in the twine has been formed around the billhook. A wiper is formed integrally with the fork of the arm and strips or wipers the loop of twine form around the billhook as the severed end of the twine is held in the billhook jaw. Proper adjustment of the wiper arm relative to the billhook is critical to the operation of the knitter as the wiper must strip or wipe the twine loop from the billhook to plete the formation of the knot. Wiper arm adjustment is performed initially at the point of manufacture and periodically thereafter when servicing the baler. It is acplished by modeling or bending the arm in three areas with a special tool. By modeling, the wiper is centered with respect to the heel of the billhook and adjusted so theta it just clears the billhook jaw. For this reason, it is desirable that the wiper arm be relatively rigid and unyielding so that proper adjustment can be maintained and yet be sufficiently bendable to permit initial adjustment. Also, in recent years , stronger twines are being used on such balers to tie bales of higher density. Such changes subject the wiper arm to higher forces during operation thus making it more difficult to maintain the arm in proper adjustment, while at the same time, making the arm flexible enough to permit initial adjustment. Accordingly, it is an object of this invention to provide a knitter with an improved wiper arm having a strong and rigid construction to maintain an accurate adjustment. Another object of this invention is to provide a knitter with a wiper arm which has a wiper which is easily and accurately adjustable with respect to the billhook of the knitter. SUMMARY OF THE INVENTION These and other objects of the invention are acplished by knitter prising a rotatable mounted billhook for forming a loop of twine thereabout and a wiper arm with an improved adjustably mounted wiper for sliding a twine loop form the billhoo