摘要: 為了掌握球面副磨損間隙對(duì)空間并聯(lián)機(jī)構(gòu)動(dòng)力學(xué)響應(yīng)特性的影響,提出考慮多球面副磨損間隙的空間并聯(lián)機(jī)構(gòu)動(dòng)力學(xué)建模與響應(yīng)特性的分析方法。以3SPS?S空間并聯(lián)機(jī)構(gòu)為研究對(duì)象,基于Archard磨損模型建立球面副間隙處的磨損模型,通過(guò)計(jì)算磨損深度,并對(duì)磨損表面進(jìn)行重構(gòu),得到磨損后的球頭與球窩,建立考慮球面副磨損間隙的空間并聯(lián)機(jī)構(gòu)動(dòng)力學(xué)模型,求解得到數(shù)值結(jié)果,對(duì)比分析磨損前/后機(jī)構(gòu)動(dòng)力學(xué)響應(yīng)的變化,并分析初始間隙值、有/無(wú)負(fù)載對(duì)磨損后機(jī)構(gòu)動(dòng)力學(xué)響應(yīng)的影響。結(jié)果表明,磨損后的非規(guī)則間隙對(duì)并聯(lián)機(jī)構(gòu)動(dòng)態(tài)特性帶來(lái)不利的影響,且增大間隙值和引入負(fù)載降低了并聯(lián)機(jī)構(gòu)運(yùn)行的穩(wěn)定性。
關(guān)鍵詞: 空間并聯(lián)機(jī)構(gòu); 動(dòng)力學(xué)響應(yīng); 球面副; 磨損間隙
中圖分類號(hào): O313.7""" 文獻(xiàn)標(biāo)志碼: A""" 文章編號(hào): 1004-4523(2025)03-0490-09
DOI:10.16385/j.cnki.issn.1004-4523.2025.03.005
Dynamic response analysis of spatial parallel mechanism considering wear clearance of spherical joint
CHEN Xiulong, ZHANG Hao, FAN Huikai
(College of Mechanical and Electronic Engineering, Shandong University of Science and Technology, Qingdao 266590, China)
Abstract: In order to grasp the influence of wear clearance of spherical pair on dynamic response characteristics of spatial parallel mechanism, a dynamic modeling and response analysis method for spatial parallel mechanism considering the wear of spherical joints is proposed. The 3SPS-S spatial parallel mechanism is taken as the research object. The wear model of the spherical joint clearance is established based on the Archard wear model, the worn ball head and ball socket are obtained by calculating the wear depth and surface geometric reconstruction, and the dynamic model of the parallel mechanism considering spherical joint wear is established. The numerical results are obtained by solving the above dynamic model. The change of dynamic response of mechanism before and after wear is compared and analyzed, and the influence of initial clearance value and load on dynamic response of mechanism after wear is obtained. The results show that the worn irregular clearance has adverse effects on the dynamic characteristics of the parallel mechanism, and the increase of clearance value and the introduction of load can reduce the stability of the parallel mechanism.
Keywords: spatial parallel mechanism;dynamic response;spherical joint;wear of clearance
球面副是空間并聯(lián)機(jī)構(gòu)中普遍存在的運(yùn)動(dòng)副之一,空間并聯(lián)機(jī)構(gòu)在長(zhǎng)期使用的過(guò)程中,球面副元素之間會(huì)不可避免地存在碰撞和摩擦,產(chǎn)生磨損現(xiàn)象,從而形成球面副非規(guī)則磨損間隙,這將嚴(yán)重影響并聯(lián)機(jī)構(gòu)的動(dòng)力學(xué)特性,降低機(jī)構(gòu)的運(yùn)動(dòng)精度和穩(wěn)定性[1?3]。因此,建立考慮球面副磨損間隙的并聯(lián)機(jī)構(gòu)動(dòng)力學(xué)模型,分析球面副磨損對(duì)機(jī)構(gòu)動(dòng)力學(xué)響應(yīng)的影響具有重要的意義。
目前考慮運(yùn)動(dòng)副磨損的機(jī)構(gòu)動(dòng)力學(xué)的研究大都針對(duì)含轉(zhuǎn)動(dòng)副的平面機(jī)構(gòu),很少涉及含球面副的空間并聯(lián)機(jī)構(gòu)。ZHUANG等[4]研究了關(guān)節(jié)磨損與機(jī)構(gòu)運(yùn)動(dòng)輸出之間的關(guān)系,介紹了一種基于貝葉斯后驗(yàn)信息的磨損推斷方法。于如飛等[5]以曲柄滑塊機(jī)構(gòu)為例,建立了一種考慮轉(zhuǎn)動(dòng)副磨損間隙的動(dòng)力學(xué)求解方法。喻天翔等[6]建立了一種含間隙鉸鏈機(jī)構(gòu)的運(yùn)動(dòng)學(xué)模型,分析了飛機(jī)艙門(mén)鎖機(jī)構(gòu)中鉸鏈的磨損特性。王庚祥等[7]分析了考慮關(guān)節(jié)磨損多體系統(tǒng)動(dòng)力學(xué)模型的一般建模方法。ZHU等[8]提出了一種考慮接觸剛度影響的磨損間隙運(yùn)動(dòng)副分析方法。韓雪艷等[9]采用牛頓?歐拉法建立考慮磨損間隙機(jī)構(gòu)的動(dòng)力學(xué)模型,分析了磨損前/后機(jī)構(gòu)的動(dòng)力學(xué)性能。LAI等[10]建立了一種考慮轉(zhuǎn)動(dòng)副磨損間隙的多體系統(tǒng)動(dòng)力學(xué)建模方法。LI等[11]分析了磨損深度及間隙尺寸對(duì)曲柄滑塊機(jī)構(gòu)動(dòng)力學(xué)性能的影響。SU等[12]提出了一種結(jié)合系統(tǒng)運(yùn)動(dòng)學(xué)的磨損預(yù)測(cè)數(shù)值方法,研究了多體系統(tǒng)中具有間隙的關(guān)節(jié)磨損與運(yùn)動(dòng)學(xué)之間的相互作用。曹毅等[13]以3?CPaRamp;R1R2混聯(lián)機(jī)構(gòu)為研究對(duì)象,分析了不同參數(shù)對(duì)關(guān)節(jié)磨損特性的影響。WANG等[14]分析了球面副磨損對(duì)空間四桿機(jī)構(gòu)多體系統(tǒng)動(dòng)力學(xué)的影響。侯雨雷等[15]以3RSR并聯(lián)機(jī)構(gòu)為研究對(duì)象,分析了單球面副磨損對(duì)機(jī)構(gòu)動(dòng)力學(xué)性能的影響。
為了精確計(jì)算球面副每一個(gè)區(qū)域的磨損量,將球面副表面離散,將球面副沿經(jīng)線和緯線方向劃分為360個(gè)區(qū)域,在每個(gè)積分步長(zhǎng)上,將每個(gè)區(qū)域?qū)?yīng)的磨損深度進(jìn)行累加,最終得到總的磨損深度,為了更加明顯地觀察出磨損程度,以半徑為3.0×10-6 m的球體作為參考。圖7為4號(hào)與5號(hào)球面副磨損后的表面幾何形貌,分析圖像可知,球面副發(fā)生的磨損為非規(guī)則磨損。
3.2 磨損前/后機(jī)構(gòu)動(dòng)力學(xué)響應(yīng)的對(duì)比
圖8為動(dòng)平臺(tái)繞β和γ方向轉(zhuǎn)動(dòng)的角位移、角速度和角加速度對(duì)比曲線。由圖8可知,磨損前、磨損后與理想情況曲線基本重合,說(shuō)明磨損對(duì)動(dòng)平臺(tái)角位移和角速度的影響非常小。由磨損前/后動(dòng)平臺(tái)在β和γ方向轉(zhuǎn)動(dòng)的角加速度響應(yīng)圖8(c)和(f)可知,磨損前曲線與理想情況曲線基本吻合,而磨損后曲線的整體軌跡雖與理想情況保持一致,但會(huì)出現(xiàn)明顯的高頻振動(dòng),重點(diǎn)出現(xiàn)在波峰位置,并且動(dòng)平臺(tái)γ方向上波動(dòng)的頻率更高。由以上分析可得,磨損對(duì)動(dòng)平臺(tái)角加速度的影響最大,并且對(duì)γ方向的影響大于對(duì)β方向的影響。
依據(jù)表1中參數(shù)及圖6的求解流程,為了分析磨損后間隙對(duì)機(jī)構(gòu)動(dòng)力學(xué)響應(yīng)的影響,對(duì)磨損后的4號(hào)和5號(hào)球面副進(jìn)行動(dòng)力學(xué)數(shù)值求解,給定磨損前初始間隙值為0.3 mm,將理想情況曲線、磨損前曲線、磨損后曲線放入同一圖像中進(jìn)行對(duì)比。
圖9為磨損前/后球頭與球窩之間的碰撞力對(duì)比曲線。在穩(wěn)定運(yùn)行階段,磨損后的碰撞力曲線與磨損前的碰撞力曲線總體趨勢(shì)保持一致,但一直處于高頻波動(dòng)狀態(tài),反映出磨損后的非規(guī)則間隙會(huì)使得球頭與球窩之間的接觸狀態(tài)極不穩(wěn)定,從而引起機(jī)械系統(tǒng)的振動(dòng),影響機(jī)構(gòu)的使用壽命。
3.3 動(dòng)平臺(tái)承受負(fù)載對(duì)磨損后機(jī)構(gòu)動(dòng)力學(xué)響應(yīng)的影響
在工程實(shí)際中,并聯(lián)機(jī)構(gòu)的動(dòng)平臺(tái)往往需要承受一定的負(fù)載,為了模擬負(fù)載作用下磨損后的并聯(lián)機(jī)構(gòu)的動(dòng)力學(xué)響應(yīng),設(shè)置球面副間隙值為0.3 mm,給動(dòng)平臺(tái)施加50 kg負(fù)載,并與無(wú)負(fù)載和理想情況曲線進(jìn)行對(duì)比。
圖10為動(dòng)平臺(tái)承受50 kg負(fù)載、無(wú)負(fù)載以及理想情況時(shí)動(dòng)平臺(tái)角位移、角速度和角加速度對(duì)比曲線。由圖10可知,在承受負(fù)載時(shí),動(dòng)平臺(tái)在β和γ方向的角加速度曲線相比于無(wú)負(fù)載時(shí)曲線波動(dòng)范圍明顯變寬,振動(dòng)的峰值增加。圖11為有負(fù)載和無(wú)負(fù)載時(shí)球面副處的碰撞力對(duì)比曲線。由圖11可知,由于動(dòng)平臺(tái)存在負(fù)載,加劇了機(jī)構(gòu)在運(yùn)動(dòng)過(guò)程中球窩對(duì)球頭的沖擊,導(dǎo)致碰撞力曲線波動(dòng)更加劇烈。
3.4 不同初始間隙對(duì)磨損后機(jī)構(gòu)動(dòng)力學(xué)響應(yīng)的影響
球面副磨損前的初始間隙值大小會(huì)對(duì)磨損后的機(jī)構(gòu)動(dòng)力學(xué)響應(yīng)產(chǎn)生重要影響,為了定量分析該影響,將4號(hào)和5號(hào)球面副初始間隙先后設(shè)置為0.2和0.1 mm,理想情況為不設(shè)置間隙,利用MATLAB軟件將穩(wěn)定后的動(dòng)平臺(tái)響應(yīng)圖像輸出分析。
由圖12可知,0.1和0.2 mm間隙的位移、速度曲線與理想曲線吻合,而角加速度曲線都在保持原有趨勢(shì)的基礎(chǔ)上出現(xiàn)波動(dòng),且初始間隙值0.2 mm曲線相比于初始間隙值0.1 mm曲線振動(dòng)幅度更寬,出現(xiàn)的峰值數(shù)值更大。同時(shí)由圖13所示的間隙碰撞力對(duì)比曲線可知,初始間隙值增大,球面副磨損后關(guān)節(jié)處的碰撞力曲線波動(dòng)增大。綜上可得,增大機(jī)構(gòu)球面副處的初始間隙值,機(jī)構(gòu)長(zhǎng)時(shí)間運(yùn)行磨損導(dǎo)致機(jī)構(gòu)產(chǎn)生更強(qiáng)的波動(dòng),不利于磨損后機(jī)構(gòu)的運(yùn)行狀況。
4 結(jié) "論
本文提出了考慮球面副磨損間隙的空間并聯(lián)機(jī)構(gòu)動(dòng)力學(xué)建模與響應(yīng)特性的分析方法,建立了含球面副磨損間隙3SPS?S空間并聯(lián)機(jī)構(gòu)的動(dòng)力學(xué)模型,分別分析了磨損前/后、有/無(wú)負(fù)載及不同間隙值的情況下機(jī)構(gòu)的動(dòng)力學(xué)響應(yīng)特性。結(jié)果表明,磨損后的非規(guī)則間隙會(huì)對(duì)機(jī)構(gòu)的動(dòng)力學(xué)性能帶來(lái)不利的影響,且增大間隙值和引入負(fù)載會(huì)使機(jī)構(gòu)運(yùn)行穩(wěn)定性降低。
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通信作者: 陳修龍(1976―),男,博士,教授。
E-mail: cxldy99@163.com