基于形封閉偏心凸輪與鉸桿增力機(jī)構(gòu)的手動(dòng)壓力機(jī).pdf

文章編號(hào):1004 - 2539(2007)06 - 0091 - 02 基于形封閉偏心凸輪與鉸桿增力機(jī)構(gòu)的手動(dòng)壓力機(jī) (蘇州大學(xué)機(jī)電工程學(xué)院, 江蘇 蘇州 215021) 李全德 鐘康民 摘要 介紹了兩種基于形封閉偏心凸輪與鉸桿增力機(jī)構(gòu)的手動(dòng)壓力機(jī),分析了它們的工作原理,給 出了相應(yīng)的力學(xué)計(jì)算公式。這兩種創(chuàng)新的手動(dòng)壓力機(jī),均采用了形封閉偏心凸輪機(jī)構(gòu),不需要外加復(fù)位 裝置,具有結(jié)構(gòu)簡單,增力效果顯著等優(yōu)點(diǎn)。 關(guān)鍵詞 偏心凸輪 形封閉機(jī)構(gòu) 鉸桿 增力機(jī)構(gòu) 手動(dòng)壓力機(jī) 引言 目前常見的手動(dòng)壓力機(jī),一般采用3種機(jī)構(gòu):1.杠 杠機(jī)構(gòu);2.杠桿 齒輪齒條機(jī)構(gòu);3.力封閉偏心凸輪機(jī) 構(gòu)。相對(duì)來說,杠桿機(jī)構(gòu)的增力系數(shù)取決于主被動(dòng)臂 的長度比,要獲得較大的增力系數(shù),必然使得杠桿的尺 寸過長,導(dǎo)致結(jié)構(gòu)不夠緊湊;而采用力封閉偏心凸輪機(jī) 構(gòu)的手動(dòng)壓力機(jī),則需要外加復(fù)位彈簧,導(dǎo)致在結(jié)構(gòu)上 顯得贅余。 基于上述原因,我們選用形封閉偏心凸輪機(jī)構(gòu),與 鉸桿增力機(jī)構(gòu)進(jìn)行串聯(lián)組合,設(shè)計(jì)了兩種新型的手動(dòng) 壓力機(jī)。 1 工作原理 1.1 采用過渡鉸桿的手動(dòng)壓力機(jī) 壓力機(jī)工作原理如圖1所示,它主要由驅(qū)動(dòng)桿、 偏 心凸輪、 驅(qū)動(dòng)滑塊、 過渡鉸桿、 雙邊鉸桿增力機(jī)構(gòu)和壓頭 組成。為了解決裝置自由度不足的問題,在偏心凸輪機(jī) 構(gòu)與雙邊鉸桿增力機(jī)構(gòu)之間,增加了一支過渡鉸桿。 圖1 通過人手向驅(qū)動(dòng)桿的球頭部施加一個(gè)力,使驅(qū)動(dòng) 桿帶動(dòng)偏心凸輪順時(shí)針轉(zhuǎn)動(dòng),水平方向上便產(chǎn)生一個(gè) 推動(dòng)驅(qū)動(dòng)滑塊向右運(yùn)動(dòng)的力;該力通過鉸接在驅(qū)動(dòng)滑 塊上的過渡鉸桿,傳遞到雙邊鉸桿增力機(jī)構(gòu)上,進(jìn)而由 該機(jī)構(gòu)產(chǎn)生向下的推力,來推動(dòng)壓頭向下運(yùn)動(dòng)對(duì)工件 施加作用力,工作行程即告完成。工件加工完畢后,扳 動(dòng)驅(qū)動(dòng)桿使偏心凸輪逆時(shí)針方向運(yùn)動(dòng),使驅(qū)動(dòng)滑塊等 向左運(yùn)動(dòng),并最終帶動(dòng)壓頭向上運(yùn)動(dòng)脫離工件。 1.2 采用過渡滑塊的手動(dòng)壓力機(jī) 該壓力機(jī)的工作原理如圖2所示,它主要由驅(qū)動(dòng) 桿、 偏心凸輪、 驅(qū)動(dòng)滑塊、 過渡滑塊、 雙邊鉸桿增力機(jī)構(gòu) 和壓頭組成。與第一種所不同的是,在驅(qū)動(dòng)滑塊的中 間開有一個(gè)徑向孔,孔中設(shè)置了一個(gè)過渡滑塊,偏心凸 輪機(jī)構(gòu)與雙邊鉸桿增力機(jī)構(gòu)通過過渡滑塊相連接,巧 妙地解決了自由度不足的問題。 工作時(shí),通過人手向驅(qū)動(dòng)桿的球頭部施加一個(gè)力, 使驅(qū)動(dòng)桿帶動(dòng)偏心凸輪順時(shí)針轉(zhuǎn)動(dòng),水平方向上便產(chǎn) 生一個(gè)推動(dòng)驅(qū)動(dòng)滑塊向右運(yùn)動(dòng)的力;該力傳遞到過渡 滑塊,由于雙邊鉸桿增力機(jī)構(gòu)的作用,使得驅(qū)動(dòng)滑塊徑 向孔中的過渡滑塊向下運(yùn)動(dòng),進(jìn)而驅(qū)動(dòng)壓頭作向下的 滑移運(yùn)動(dòng),從而作用于工件。工件加工完畢后,扳動(dòng)驅(qū) 動(dòng)桿使偏心凸輪逆時(shí)針方向運(yùn)動(dòng),使驅(qū)動(dòng)滑塊等向左 運(yùn)動(dòng),并最終帶動(dòng)壓頭向上運(yùn)動(dòng)脫離工件。 圖2 由圖1、 圖2不難看出,兩種壓力機(jī)都采用了形封 閉偏心輪機(jī)構(gòu),在壓頭回程時(shí)可以方便地脫離工件,并 且都采用了偏心凸輪機(jī)構(gòu)和雙邊鉸桿增力機(jī)構(gòu)相組合 的三級(jí)增力機(jī)構(gòu),增力效果顯著。同樣,它們的差異也 顯而易見,第一種采用了過渡鉸桿的結(jié)構(gòu),盡管結(jié)構(gòu)較 為簡單,但是剛性較差;第二種則采用了徑向孔中放置 19第31卷 第6期 基于形封閉偏心凸輪與鉸桿增力機(jī)構(gòu)的手動(dòng)壓力機(jī) 過渡滑塊的方法,不僅靈活地解決了自由度不足的問 題,還使得整個(gè)裝置的剛性大大增強(qiáng)。 2 力學(xué)計(jì)算 以上壓力機(jī)由兩部分串聯(lián)組合組成,一部分是偏 心凸輪機(jī)構(gòu),另一部分是雙邊鉸桿增力機(jī)構(gòu)。其中,帶 驅(qū)動(dòng)桿的偏心凸輪機(jī)構(gòu),實(shí)質(zhì)上是一種串連式的兩級(jí) 增力機(jī)構(gòu),其中驅(qū)動(dòng)桿的杠桿作用為第一級(jí),偏心凸輪 形成的斜楔作用為第二級(jí)。輸入力經(jīng)過該機(jī)構(gòu)的二次 放大后,又通過雙邊鉸桿增力機(jī)構(gòu)進(jìn)行第三次力放大, 所以此壓力機(jī)為三級(jí)增力機(jī)構(gòu)。 系統(tǒng)的增力系數(shù)是輸出力F0與輸入力Fi的比 值。不考慮摩擦損失的增力系數(shù)為理論增力系數(shù),常 用it表示;考慮摩擦損失后的增力系數(shù)為實(shí)際增力系 數(shù),常用ip表示。 通過建立力學(xué)模型并分析計(jì)算可知,圖1所示壓 力機(jī)的理論增力系數(shù)的計(jì)算公式為 it1= Lcos tan1 1 +tan2tan 2sin2 (1) 式中 L 手柄端部到偏心凸輪偏心的距離 手柄相對(duì)于偏心凸輪中心的擺角 1 偏心輪力作用點(diǎn)處偏心凸輪的升角, 1= esin R-ecos ( e 為偏心距, R為偏心凸輪的半徑) 偏心凸輪轉(zhuǎn)動(dòng)中心與其力作用點(diǎn)處的距 離,=R2+e2- 2Recos 過渡鉸桿的理論壓力角 2 增力鏈的理論壓力角 其實(shí)際增力系數(shù)ip1的計(jì)算公式為 ip1= Lcos tan(1+1)+ tan3 1 - tan(2+2)tan21 +tantan(2+ 2) (1 - tan1tan2 ) / 2tan(2+2) (1 - tantan1 ) (2) 式中 1 偏心凸輪與驅(qū)動(dòng)滑塊作用處的摩擦角 2 鉸鏈副的當(dāng)量摩擦角,2= arcsin 2r l f ( r 為鉸鏈軸半徑, l為鉸桿上兩鉸鏈孔的 中心距, f為鉸鏈副的摩擦因數(shù)) 3 3 偏心凸輪轉(zhuǎn)軸處的摩擦角 1 驅(qū)動(dòng)滑塊與其導(dǎo)向槽之間的摩擦角,1 = arctan(為驅(qū)動(dòng)滑塊與導(dǎo)向槽之間 的摩擦系數(shù)) 2 壓頭與其導(dǎo)向槽間的當(dāng)量摩擦角,其值 由力輸出件的受力及約束方式?jīng)Q定4。 在式(1)、 式(2)中,前一部分為偏心凸輪機(jī)構(gòu)的計(jì) 算公式,后一部分為雙邊鉸桿增力機(jī)構(gòu)的計(jì)算公式。 圖2所示壓力機(jī)的理論增力系數(shù)it2和實(shí)際增力 系數(shù)ip2的計(jì)算公式分別為 it2= Lcos tan1 1 2tan2 (3) ip2= Lcos tan(1+1)+ tan3 1 - tan(2+2)tan11 - tan(2+2)tan2 2tan(2+2) (4) 由此,兩種壓力機(jī)的實(shí)際輸出力F1p和F2p的計(jì)算 公式分別為 Fp1= Lcos1 - tan(2+2)tan21 + tantan(2+ 2) (1 - tan1tan1 ) F i/ 2tan1tan(2+2) (1 - tantan1 ) (5) Fp2= Lcos1 - tan(2+2)tan11 - tan(2+2) tan2 Fi/ 2tan(1+1)+ tan3tan(2+ 2 ) (6) 3 計(jì)算舉例 對(duì)于鉸桿機(jī)構(gòu),從理論上講,其理論壓力角2越 小越好,但由于制造精度等原因,2角的取值不可能 很小,在工程實(shí)際中,一般取min= 3 5 。這里,我們 取2= 4, r= 5mm, l = 100mm, f= 0.1,計(jì)算可得2= 0.57,同時(shí)取= 0.1,2= 10,= 6 。對(duì)于偏心凸輪 機(jī)構(gòu),取參數(shù)如下, L= 500mm,= 30, e= 5mm, R= 30mm,1=3= 6 。根據(jù)式(7)、 式(8 ) , 代入計(jì)算得到 兩種手動(dòng)壓力機(jī)的實(shí)際增力系數(shù)分別為i1= 350.5, i2 = 344.8,二者相差甚微。 若取某手動(dòng)壓力機(jī)人手作用力為500N,根據(jù)求得 的增力系數(shù)i1, i2,可計(jì)算得兩種手動(dòng)壓力機(jī)的實(shí)際輸 出力分別為F1p= 175250N, F2p= 172400N。而如采用 單一的偏心凸輪機(jī)構(gòu),在其它條件一定的情況下,要取 得如此大的輸出力,經(jīng)計(jì)算,驅(qū)動(dòng)桿的力輸入點(diǎn)到鉸鏈 軸的長度L ,需達(dá)3m以上,這在生產(chǎn)實(shí)踐中可以說是 沒有可行性的。(下轉(zhuǎn)第100頁) 29 機(jī)械傳動(dòng) 2007年 實(shí)研究.湖北汽車工業(yè)學(xué)院學(xué)報(bào),2000 ,14(2) :15 24 王紅巖,方泳龍,周云山等.金屬帶式無級(jí)變速傳動(dòng)系統(tǒng)動(dòng)態(tài)特性 的仿真分析.汽車技術(shù),1995 ,(5) :14 25 王紅巖,方泳龍,周云山等.金屬帶式無級(jí)變速傳動(dòng)系統(tǒng)動(dòng)態(tài)特性 的理論與試驗(yàn)分析.汽車工程,1999 ,21(5) :257262 26 張寶生,張伯英,周云山等.金屬帶式無級(jí)變速器液壓控制系統(tǒng)的 仿真金屬帶式無級(jí)變速傳動(dòng) 農(nóng)業(yè)機(jī)械學(xué)報(bào),2002 ,33(2) :2024 27 胡建軍,秦大同,劉振軍.金屬帶式無級(jí)變速傳動(dòng)速比變化特性研 究.汽車工程,2003 ,25(1) :2529 28 馬士澤,雷雨成.金屬帶式無級(jí)變速器速比控制研究.同濟(jì)大學(xué)學(xué) 報(bào)(自然科學(xué)版) ,2003(2) :209211 29 Ercole G. 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IEEE international conference on evolutionary computation , Nagoya , 1996:150153 56 ISHIDA Y, ADACHI N. An immune algorithm for multiagent : application to adaptive noise neutralization. IEEE/ RSJ international conference on intelli2 gent robots and systems.Osaka ,Japan ,1996 ,(3) :17391746 收稿日期:20061103 基金項(xiàng)目:安徽省重點(diǎn)科學(xué)項(xiàng)目(05021028)安徽省 “十五” 科技攻關(guān)項(xiàng)目 (06012095B) 作者簡介:王幼民(1064 - ) ,男,湖北孝感人,碩士,副教授 (上接第92頁) 4 結(jié)論 本文提出的兩種手動(dòng)壓力機(jī)具有以下特點(diǎn): (1)采用了偏心凸輪和鉸桿相組合的三級(jí)增力機(jī) 構(gòu),由計(jì)算結(jié)果可知,輸入力可放大345倍。因而在輸 入力一定的情況下,可以獲得很大的輸出力。 (2)相對(duì)于力封閉機(jī)構(gòu)而言,形封閉機(jī)構(gòu)在壓頭回 程時(shí)不需要復(fù)位彈簧,結(jié)構(gòu)相對(duì)簡單。 (3)第一種壓力機(jī)采用了過渡鉸桿,壓力機(jī)的剛性 較差;第二種采用了過渡滑塊,壓力機(jī)的剛性大大加 強(qiáng);又因?yàn)閮烧咴隽ο禂?shù)相差不大,因而建議優(yōu)先選用 第二種壓力機(jī)。 參考文獻(xiàn) 1 Zhong Kangmin , Guo Peiquan. Orthogonal reinforcement mechanism. and hydraulic drive. In: Proceedingsof tenth world congresson the theoryof ma2 chines and mechanisms (Vol5) . Oulu , Finland: Oulu University Press , 1999 , 20372042 2 鐘康民.偏心夾緊流體傳動(dòng)夾具.新技術(shù)新工藝,2003 3 林文煥,陳本通編著.機(jī)床夾具設(shè)計(jì).北京:國防工業(yè)出版社,1987 4 劉文劍主編.夾具工程師手冊(cè).哈爾濱:黑龍江科學(xué)技術(shù)出版社, 1992 收稿日期:20061220 收改稿日期:20070308 作者簡介:李全德(1982 - ) ,男,山東青島人,碩士研究生 001 機(jī)械傳動(dòng) 2007年 nism synthesized have been obtained including mean point - to - point error , maximal point - to - point error , mean normal error and maximal normal error. The results provide reliable reference data for the design2 er. It is proved that the method is available by an example. Key words Double straight - line guiding mechanism Path synthesis Error analysis Numerical atlas method Graphical Method of Power Flow of the Closed Planetary Gear TrainLu Cunguang , Duan Qinhua(76) Abstract Based on the fundamental formulas , the diagrams are derivated and drawn reflecting the relationship between the structure and power flow of closed planetary gear train. They can be applied to ana2 lyze existed trains for the power flow direction. The process is not only clear and visual , but also convenient and fast. The design and power flow analysis are no longer difficult for closed planetary gear train. Key words Closed planetary gear train Speed ratio Power flow Circulatory power flow Torsional Vibration Analysis of Flexible Drive System based on ADAMSShen Yufeng ,Li Weiwei , Z ou Guangde(78) Abstract The virtual prototype of the flexible driver system is estab2 lished by using ADAMS (Automatic dynamic analysis mechanical sys2 tems) , the effect of elastic coupling on natural vibration frequency of system is analyzed. The results also provide theoretical data to avoid system sympathetic vibration effectively. Key words ADAMS T orsional vibration Natural frequency Flexible body Characteristic Analysis ofIntermittent -motion Linkagewith Slight Difference in Length between links Li Yan ,Ran Hengkui , Chen Xinbo(81) Abstract Some research is done on the intermittent - motion linkage with slight difference in length between the links. T o analyze and evalu2 ate the usability of this intermittent - motion linkage in practical engi2 neering , some analyses of the special linkage , such as the law of mo2 tion , the mechanical advantage , the transmission and dynamic charac2 teristic , are done. At the same time , the virtual prototype of this spe2 cial mechanism is also taken into analysis on the Adams system by mak2 ing use of its powerful functions on kinematics as well as dynamic simu2 lations. The results of these studies show that this special intermitted - motion linkage has a good usage property. This research shows some theoretic foundations for the practical usage of the intermittent - motion linkage. Key words Bar - linkage Intermittent - motion Analysis of link2 age Adams 2 - D Tolerance Analysis based on Vector- loop Assembly Model Peng Heping , Liu Xiaojun(84) Abstract Traditional tolerance analysis methods require an explicit function to describe the relationship between the resultant assembly di2 mensions and manufactured component dimensions. Such an explicit as2 sembly function may be difficult or impossible to obtain for complex 2 - D assemblies. A new method is presentedfor tolerance analysisof 2 - D mechanical assemblies based on vector loop - based models. It has a significant advantage over traditional tolerance analysis methods in that it does not require this explicit assemblyfunction. Furthermore , the tol2 erance analysis problemof 2 - D assemblies can be solved by vector op2 erating to obtain the tolerance sensitivity coefficients. An example is presented to demonstrate the effectiveness of the proposed method. Key words 2 - D T olerance analysis Vector loop assembly model Sensitivity coefficient Configuration Design of Universal Joints from Point of View of In2 terferenceZhang Fan(87) Abstract A systematic approach to the design and optimization of the ideal universal joint with a given input torque for a given joint angle is developed. Universal joints which use the approach presented here will be ensured not to have interference between the various parts of the mechanism when in operation. Key words Universal joint Interference Optimum design Two New Kinds of H and Presses based on Force Amplifier Com2 posed of Form- closed Eccentric - cam and Toggle Li Quande , Zhong Kangmin(91) Abstract Two new kinds of hand press based on force amplifier com2 posed of form - closed eccentric - cam and toggle are introduced. Their working principles are analyzed , and their mechanical calculating for2 mulae are also given. Both these two new presses consist of form - closed eccentric - cam , so they