4缸發(fā)動機油底殼組合鉆床Ⅱ主軸箱設計【說明書+CAD】,說明書+CAD,4缸發(fā)動機油底殼組合鉆床Ⅱ主軸箱設計【說明書+CAD】,發(fā)動,機油,組合,鉆床,主軸,設計,說明書,仿單,cad 黃河科技學院畢業(yè)設計(文獻翻譯) 第 7 頁 畢業(yè)設計 文獻翻譯 院（系）名稱 工學院機械系 專業(yè)名稱 機械設計制造及其自動化 學生姓名 黎振廷 指導教師 賈百合 2012年 03 月 10 日 INVESTIGATION ON DYNAMIC PERFORMANCE OF SLIDE UNIT IN MODULAR MACHINE TOOL （對組合機床滑臺動態(tài)性能的調查報告） 出處： Peter Dransfield, Hydraulic Control System-Design and Analysis of TheirDynamics, Springer-Verlag, 1981 文獻作者：Peter Dransfield, 翻譯頁數(shù)：p139—144 對組合機床滑臺動態(tài)性能的調查報告 本報告處理調查利用有束縛力的曲線圖和狀態(tài)空間分析法對組合機床滑臺的滑動影響和運動平穩(wěn)性問題進行分析與研究，從而建立了滑臺的液壓驅動系統(tǒng)一自調背壓調速系統(tǒng)的動態(tài)數(shù)學模型。通過計算機數(shù)字仿真系統(tǒng)，分析了滑臺產(chǎn)生滑動影響和運動不平穩(wěn)的原因及主要影響因素。從那些中可以得出那樣的結論，如果能合理地設計液壓缸和自調背壓調壓閥的結構尺寸。 本文中所使用的符號如下： s1-流源，即調速閥出口流量； Sel—滑臺滑動摩擦力 R一滑臺等效粘性摩擦系數(shù)： I1—滑臺與油缸的質量 12—自調背壓閥閥心質量 C1、c2—油缸無桿腔及有桿腔的液容； C2—自調背壓閥彈簧柔度； R1, R2自調背壓閥阻尼孔液阻， R9—自調背壓閥閥口液阻 Se2—自調背壓閥彈簧的初始預緊力； I4, I5—管路的等效液感 C5、C6—管路的等效液容： R5, R7-管路的等效液阻； V3, V4—油缸無桿腔及有桿腔內容積； P3, P4—油缸無桿腔及有桿腔的壓力 F—滑臺承受負載， V—滑臺運動速度。 本文采用功率鍵合圖和狀態(tài)空間分折法建立系統(tǒng)的運動數(shù)學模型，滑臺的動態(tài)特性可以能得到顯著改善。 引言 在組合機床正常工作中，滑臺運動速度的大小和它的方向以及所承受負載的變化都將以程度不同地影響其工作性能。特別是在工進過程中。滑臺上負載的突然消失引起的前進以及負載的周期性變化而引起的運動不平穩(wěn)性，都將影響被加工件的表面質量，在嚴重的情況下會使刀具折斷掉。根據(jù)大連機床廠要求，作者采用有束縛力的曲線圖和狀態(tài)空間分析法建立組合機床滑臺的新型液壓驅動系統(tǒng)一自調背壓調速系統(tǒng)的動態(tài)數(shù)學模型。為了改善滑臺的動態(tài)特性，有必要去分析找出滑臺產(chǎn)生前沖和運動不平穩(wěn)的原因以及主要的影響因素，但那必須通過計算機數(shù)字仿真和研究得出最后的結果。 動態(tài)數(shù)學模型 組合機床滑臺的液壓驅動系統(tǒng)一自調背壓調速系統(tǒng)的工作原理圖如圖I所示。這個系統(tǒng)是用來完成"工進一停止一快退”的工作循環(huán)。當滑臺在工進時，三位四通換向閥處于圖示右位，油泵的供油壓力在濫流閥的有效作用下近似地幾乎保持恒定，該油液流經(jīng)過換向閥和調速閥后進入油缸的無桿腔，以推動滑臺向前移動；與此同時，從油缸有桿腔排出的壓力油經(jīng)自調背壓閥和換向閥流回油箱了。在這個過程中，兩個單向閥和溢流閥的工作狀態(tài)始終都沒有任何變化。對與象組合機床滑臺的液壓驅動系統(tǒng)一自調背壓調速系統(tǒng)這樣的復雜非線性的系統(tǒng)，為了便于研究它的動態(tài)特性，建立一個僅著重考慮主要影響因素的合理簡單的動態(tài)數(shù)學模型是尤其重要的[1][2]。從理論分析和試驗研究的列舉中可以得知：該系統(tǒng)的過程時間是遠大于調速閥的過程時間的，當油缸無桿腔有效承壓面積很大時，調速閥出口流量的瞬時的超調反映為滑臺運動速度的變化是很小的[2]。為了更加拓寬和深入研究系統(tǒng)的動態(tài)特性，使研究工作能在微型計算機上有效地進行，本文章對原模型[2]做進一步簡化處理，假定調速閥在系統(tǒng)的整個通過過程中輸出時候恒定的流量，這被看作其為流源。這樣，系統(tǒng)的動態(tài)模型的結構簡圖如圖2所示，它是由油缸、滑臺，自凋背壓閥和聯(lián)接管路等組成。。 功率鍵合圖是一功效流圖，它是按著系統(tǒng)的能量傳遞方式，以實際結構為基礎，用集中參數(shù)把子系統(tǒng)之間的作用關系抽象地表示為阻性元R、容性元C和感性元I的三種作用元。采用這種方法建模物理概念清晰，結合狀態(tài)空間分析法可準確地描述和分析線性系統(tǒng)，該法在時域中研究復雜非線性系統(tǒng)動態(tài)特性的一種有效的方法。 根據(jù)自調背壓調速系統(tǒng)各元件的主要特性和建模規(guī)則[1]，得出了圖3所示的系統(tǒng)的功率鍵合圖。圖中每根鍵上的半箭頭表示功率流向，構成功率的兩個變量是力變量（油壓P或作用力F）和流變量（流量q或速度v）。O結點表示在系統(tǒng)中屬于并聯(lián)連接，各鍵上的力變量相等而流變量之和為零；1結點表示在系統(tǒng)中屬于串聯(lián)連接，各鍵上流變量相等而力變量之和為零。TF表示不同能量形式間的變換器，TF下標注的字母表示力變量或流變量的轉換比值。鍵上的短橫杠表示該鍵上兩變量間的因果關系。全箭頭表示控制關系。在三種作用元中容性元和感性元的力變量與流變量之間具有積分或微分關系，因此，根據(jù)圖3可推導出具有九個狀態(tài)變量的復雜非線性狀態(tài)方程。本文對滑臺動態(tài)特性的研究是從滑臺的前沖和運動平穩(wěn)性兩方面入手，用四階定步長Runge-Kutta法在IBM-PC微型計算機上進行數(shù)字仿真,仿真結果分別如圖4和圖5所示。 滑臺前沖 滑臺前沖現(xiàn)象是作用在滑臺上的負載突然消失（如鉆削工作的情況)引起的。在此過程中，滑臺的負載F、運動速度V、油缸兩腔壓力P3和P4的變化可從圖4仿真結果看出。當滑臺在負載的作用下勻速運動時，油缸無桿腔油液壓力較高．油液中聚集了大量的能量。當負載突然消失時，該腔油壓隨之迅速降低，油液從高壓態(tài)轉入低壓態(tài)的過程中向系統(tǒng)釋放很多能量，致使滑臺高速向前沖擊。然而，滑臺的前沖使油缸有桿腔油液受壓引起背壓升高，從而消耗掉系統(tǒng)中的一部分能量，對滑臺的前沖起到一定的抑制作用。應當看到，在所研究的系統(tǒng)中，自調背壓閥的入口壓力要受到油缸兩腔油壓的綜合性作用。在負載消失的瞬間，自調背壓閥的壓力將會迅速地上升，并穩(wěn)定地處在高于初始背壓的數(shù)值以上。從圖中可見，自調背壓調速系統(tǒng)在負載消失瞬間油缸背壓力升高的幅度大于傳統(tǒng)的調速系統(tǒng)，所以，其油缸有桿腔中油液吸收的能量就多；結果，滑臺的前沖量比傳統(tǒng)調速系統(tǒng)要小大約20%?？梢姴捎米哉{背莊調速系統(tǒng)作為驅動系統(tǒng)的滑臺在抑制前沖方面具有良好的特性，其中自調背壓閥起了很大作用。 滑臺的運動平穩(wěn)性 當作用于滑臺上的負載作周期變化時（比如說銑削加工的情況），滑臺的運動速度將要產(chǎn)生一定的波動。為于保證加工質量的要求，必須盡可能地減小其速度波動的范圍。而從討論問題的方便性出發(fā)來說，假設負載按正弦波的規(guī)律變化，從而得到的數(shù)字仿真結果如圖5所示。由此可見這個系統(tǒng)與傳統(tǒng)的調速系統(tǒng)有著相同的變化規(guī)律以及非常接近的數(shù)值數(shù)字。其中的原因是負載的變化幅度不大，油缸兩腔的壓力也就沒有較大變化，從而最終導致自調背壓閥的作用不夠明顯顯示。 改善措施 通過研究的結果表明，以自調背壓調速系統(tǒng)作為驅動系統(tǒng)的滑臺，其動態(tài)特性要比傳統(tǒng)的調速系統(tǒng)好的。要減少滑臺的前沖量，就必需在負載消失的瞬間時候迅速提高油缸有桿腔的背壓力；要提高滑臺的運動平穩(wěn)性就需增加系統(tǒng)的剛性，主要措施在于減小油液的體積。從系統(tǒng)的結構得知，油缸有桿腔與排油管之間有一很大的容積，如圖6a所示。它的存在方面延遲和衰減了自調背壓閥的作用，另一方面也降低了系統(tǒng)的剛性，它會限制了前沖特性和運動平穩(wěn)性的進一步改善。因此，改善滑臺動態(tài)特性可從兩個方法進行處理：即改變油缸容積和改變自調背壓閥結構尺寸。通過一系統(tǒng)結構性參數(shù)的仿真計算以及結果的比較可以得出這樣的結果：當把油缸有桿腔與排油管間容積V4同無桿腔與進油管間容積V3之比由原來的5.5改為1時，如圖6b所示，同時，把自調背壓閥閥芯底端直徑由原來的10mm增加為13mm,阻尼三角槽邊長從原來的lmm減小到0.7mm時，可使滑臺的前沖量減小30%,過渡過程時間明顯縮短了，滑臺的運動平穩(wěn)性也將會得到很大的改善。 結論 通過理論上的分析和計算機仿真研究實驗,很明顯的是自調背壓調速系統(tǒng)作為組合機床滑臺的驅動系統(tǒng)是很有推廣使用價值的。影響滑臺動態(tài)特性的主要因素是油缸內部結構性和自調節(jié)背壓閥的尺寸。假如能對其進行合理設計，可使滑臺的動態(tài)特性得到顯著地改善。同時，也說明了采用有束縛力的曲線圖和狀態(tài)空間分析法研究復雜非線性液壓系統(tǒng)的動態(tài)特性是既方便又有效的方法。 附錄 英文原文 翻譯文獻：INVESTIGATION ON DYNAMIC PERFORMANCE OF SLIDE UNIT IN MODULAR MACHINE TOOL （對組合機床滑臺動態(tài)性能的調查報告） 文獻作者：Peter Dransfield, 出處： Peter Dransfield, Hydraulic Control System-Design and Analysis of TheirDynamics, Springer-Verlag, 1981 翻譯頁數(shù)：p139—144 INVESTIGATION ON DYNAMIC PERFORMANCE OF SLIDE UNIT IN MODULAR MACHINE TOOL Author：Peter Dransfield This paper deals with the investigation for slide unit's impact and motion stability in modular machine tool fay means of the method of power bond graph and state space analysis. The dynamic mathematical model of self-adjusting back pressure speed control system used to drive slide unit is established. Main reasons and affecting factors for slide unit impact and motion unstability are analysed through computer digital simulation, It is concluded from those that, if the structural dimensions of hydraulic cylinder and back pressure valve are designed rationally, the slide unit's dynamics will markedly be improved. NOMENCLATURE Sf flow source Sei sliding friction force in slide unit R equivalent viscous friction coefficient in slide unit Ii mass of slide unit and cylinder h mass of SABP valve spool Ci,C2 hydraulic capacitances of rod chamber and non-rod chamber in cylinder re- spec-tively C3 spring compliance of SABP valve R]rR2 hydraulic resistances of damping holes R9 hydraulic resistance of orifice of SABP valve Se2 presetting force of spring in SABP valve I4J5 equivalent liquid inertia in pipe lines C^Cg equivalent hydraulic capacitances in pipe lines equivalent hydraulic resistances in pipe lines V-j V^ oil-containing volumes in non-rod chamber and rod chamber respectively P,r:, P-i oil pressures in non-rod chamber and rod chamber respectively F load acted on slide unit V slide unit velocity * Department of Mechanical Engineering, Dalian Ur.iversity of Technology, Dalian. China. INTRODUCTION During operation of modular machine tool, the changes of slid unit's speed and load acted on it in both magnitude and direction will affect working performar.ee to a different extent Particularly the impact caused by sudden vanishing of load and the motion unstability due to periodical change of load in operation will affect the surface quality of the workpiece machined, and the tool would be broken off under serious conditions, By using the method of power bond graph and state space analysis, the dynamic mathematical model of the system used to drive slide unit is established, that is called as self-adjusting back pressure speed control system and abbreviated to SABP system. In order to improve slide unit's dynamics, it is necessary to find out the main reasons and affecting factors, that must be based on computer digital simulation and study on the results. DYNAMIC MATHEMATICAL MODEL The schematic diagram of SABP system is shown in Fig.l, the system is used to perform the cycle of feeding, stopping and returning. Four way control valve works in the right position during slide unit's feeding. The supply pressure of the pump is approximately constant under the action of pressure relief valve, the oil through the control valve and pressure compensated flow control valve enters the non-rod chamber to put slide unit forward. At the same time, the oil from the rod chamber is discharged through SABP valve and directional control valve to tank. In this process, the state of two check valves and pressure relief valve is not changed, To establish the mathematical model as reasonably and simply as possible, consideration must be focused on main affecting factors for a complex non-linear system such as the SABP system. It is illustrated by theoretical analysis and test result ' , that the transient time of the system is much longer than that of the flow control valve, and the flowrate overshoot of the valve in transients affects very small to slide unit speed because of the ;large effective sectional area of non-rod chamber in cylinder. For investigating the system's dynamics widely and deeply, the initial modeltn is further simplified in this paper, and so the study can be efficiently made with microcomputer. It is assumed that the flowrate through the flow control valve isconstant in the whole transient process, and is denoted to a flow source.Fig.2 shows the structure diagram of the dynamic model of the system, it is composed of cylinder, slide unit, SABP valve and pipe line; etc. By using the method of power bond graph and state space analysis in this paper, the dynamic mathematical model of the system is to be established- The power bond graph is a power flow diagram, which expresses abstractly the actions among sub-systems as three effects, i.e. resistance effect, capacitive effect and inertia effect, according to the way of energy transform, on the basis of practical structure and by means of method of lumped parameters. The model is characterized by a clear conception in physics, and non-linear system can be accurately analysed in combination with method of state space analysis, thus it is a effective method used in the dynamic investigation of complex non-linear system in the'timedomain. From main performances of components in SAEP system, the power bond graph of the system has been formed by means of the rule of model establishing ' and is shown in Fig.3. Half arrow in each bond indicates a direction of power How, two variahles of power are effort variable and flow variable. O-junction illustrates algebraic summation of flow variables at common effort, i.e. parallel connection, 1-junction does algebraic summation of effort variables at common flow, i.e. series connection. The symbol TF represents power transformer between two types of energy, and transforming modulus between efforts or flows is noted below the symbol TF. Short transverse bar across one end of each bond shows causality between two variables. A full arrow expresses a control action. Among three actions, there is an integration or differential form in capacitive effect and inertia effect between two variables. So state equation may be derived from Fig.3, there are nine state variables in this complex nonlinear equation. Studying on the slide unit's dynamics is started with impact and motion stability. The equation is simulated by using the method of 4th order Runge-Kutta integration procedure on IBM-PC computer. Fig.4 and Fig.5 illustrate the results respectively. SLIDE UNIT IMPACT Slide unit's impact phenominon results from load's vanishing in the transients, ■ for example, the situation of drilling through workpiece, Fig.4 expounds the variations of the load and speed of slide unit, the pressures of chambers in cylinder. When slide unit motions evenly under the action of load, the oil pressure in non-rod chamber is very high, and there is a lot of hydraulic energy accumulated in side. The pressure decreases at once with load's discharging rapidly. During the process of oil pressure converting from high to low, the system absorbs some of the energy, so slide unit impacts forward with high speed. And then the oil in rod chamber is 141 compressed to increase back pressure, some of the energy is consumed, which plays a part of restraining the impact of the slide unit. It must be noted that inlet pressure of SABP valve telys on the interaction of pressures of two chambers, and increases rapidly at the instant of load's vanishing, and then stabilizes at some value greater than initial one. This pressure is also greater than one of traditional speed control system, therefore the energy can be absorbed much more in the rod chamber. In result, the impact of slide unit in SABP system is 20% lawer than in traditional's. It is thus clear that slide unit with SABP system for driving has a good performance in restraining the impact and SABP valve plays an important part in that, MOTION STABILITY When load acting on slide unit varies periodically, such as the situation of milling, slide unit's speed will bring about some pulse. In order to meet the requirements of manufacturing quality, the magnitude of the speed pulse must be reduced as small as possible. The variation of the load is assumed to be of sine wave, in order to simplify discussion of the problem, The result of digital simulation is shown in Fig.5 It can be seen that, the response of the system is the sameas traditionl's and the differences between them are very small. The reason for this is that the variation of the load is not targe, there the pressures in chambers vary very little that is, the effect of the SABP valve is not obvious. IMPROVEMENT It is shown by studying, that dynamics of slide unit which used SABP speed control system as driving system is better than that of traditional system. To reduce the slide unit's impact, the back pressure of rod chamber has to be increased rapidly in the transients of load's vanishing; on the other hand, to enhance the slide unit's motion stability, it is necessary to raise the system rigidity. However, main recommendation lies in decreasing the volume of oil. It is known from system structure that, there is a lot of oil-containing volume between the rod chamber and drain pipe as shown in Fig.6a. Because the volume exists, not only the effect of SABP valve is delayed and reduced, hut also the rigidity of the system is decreased. Therefore, it is hindered to further improve the impact and motion stability. To make the slide unit dynamics better, the structural dimensions of cylinder's chamber and the SABP valve must be designed suitably. Based on simulations under the various structural dimensions and comparison among the results, the following two measures can be taken for improvements: the ratio between volumeV4 and V3 is changed from 5.5 to 1 approximately, as shown in Fig,6b; 142 黃河科技學院畢業(yè)設計(論文)文獻翻譯 第 8 頁 the bottom diameter of spool of the SABP valve is increased from 10 mm to 13 mm and.the length of side of triangular damping slot is decreased from 1 mm to 0.7mm the slide unites impact quantity can be reduced by 30%, and the time of dynamic response is shortened. In addition, slide unit's motion stability may be improved obviously. It is thus evident that improvements are very effective. CONCLUSIONS By the way of theoretical analysis and computer simulating investigation, it is obvious that the SABP speed control system used as slide units driving system in modular machine tool is valuable for popularization and utilization, Main factors affecting the slide unit dynamics are the structural dimensions of the cylinder and the SABP valve. In the case of rationally designing, the slide unit dynamics may be obviously improved. Meanwhile, it is shown that the method of power bond graph and state space analysis is a very convenient and effective method in studying dynamics of complex non-linear hydraulic system. REFERENCES [1] Peter dransfield Hydraulic Control System-Design and Analysis of Their Dyna-mics Springer-Verlag, 1981 [2] Dong Bengang, Zhang Zhixiang, Investigation on impact property of selfadjusting back pressure speed control system. Machine tool & Hydraulics No.2, 1987 GuangZhou, China, (in Chinese).