【摘要】：液壓缸是液壓傳動與控制系統(tǒng)中常用的執(zhí)行部件。液壓缸拖動部件運動至行程終端時,往往會發(fā)生劇烈的機械碰撞。這種機械沖擊的產(chǎn)生,不僅會影響液壓缸的工作性能,而且會損壞液壓系統(tǒng)的其它元件,具有很大的危害性。因此液壓缸的緩沖研究就顯的尤為重要了。 本文對現(xiàn)有固定節(jié)流口、圓柱形環(huán)隙節(jié)流、溝槽節(jié)流、圓錐形環(huán)隙節(jié)流、拋物線環(huán)隙節(jié)流五種常用的液壓缸內(nèi)置式緩沖裝置進行了分析,對緩沖過程建立了數(shù)學模型并借助MATLAB進行了計算仿真,探討了各緩沖裝置的緩沖特性。分析表明緩沖性能各不相同,各緩沖裝置緩沖過程壓力峰值較大,雖然都保證了速度無突變,即無硬沖擊存在,但固定節(jié)流口、溝槽節(jié)流以及拋物線環(huán)隙節(jié)流緩沖裝置在緩沖起點或終點加速度變化太大,即存在軟沖擊�？梢�,五種常用緩沖裝置都無法達到最佳緩沖特性。 液壓缸內(nèi)置式緩沖裝置一般保證了無硬沖擊,但如果存在軟沖擊,依然會對液壓缸造成危害。因此,最佳的液壓缸緩沖裝置應該結(jié)構(gòu)簡單容易實現(xiàn),并且其理想的緩沖特性應該是在保證緩沖壓力較小的情況下,避免硬沖擊,減少或消除軟沖擊。本文以砌塊成型機的推板油缸工況需求為例,依據(jù)理想緩沖特性求得的理論節(jié)流面積曲線設計了一種液壓缸緩沖裝置。該緩沖裝置由沿軸向不等距不等數(shù)量的圓形小孔組成,結(jié)構(gòu)緊湊,加工制造容易。以液壓缸末端小孔相應位置的實際節(jié)流面積與理論節(jié)流面積的差值作為約束條件,對小孔數(shù)量和小孔位置進行了合理設計,使其實際節(jié)流面積與理論節(jié)流面積更為接近,性能更加趨近理想緩沖特性。同時對新結(jié)構(gòu)建立了數(shù)學模型,對其性能進行仿真,驗證其除具備無硬沖擊和較低的軟沖擊的緩沖性能外,還具有良好的軟啟動特性。 液壓缸的緩沖性能除與緩沖結(jié)構(gòu)有關(guān)外,還與負載有關(guān),要達到無沖擊或小沖擊緩沖,就需要根據(jù)具體的工況設計液壓缸的緩沖結(jié)構(gòu)。新型緩沖結(jié)構(gòu)可以實現(xiàn)無沖擊緩沖過程,但設計計算過程繁雜,因此本文運用MATLAB和VB軟件編程開發(fā)出了新型液壓缸內(nèi)置式緩沖裝置的設計軟件,用戶只需在界面內(nèi)輸入不同的工況參數(shù)后,就可以得到新型液壓缸內(nèi)置式緩沖裝置緩沖過程的速度與行程關(guān)系、加速度與行程關(guān)系以及理論節(jié)流面積變化曲線,同時獲得最佳緩沖特性下的小孔數(shù)量和分布位置。從而在短時間內(nèi)完成新型液壓缸內(nèi)置式緩沖裝置設計,最后在實例的驗證下證明了軟件的實用價值。
[Abstract]:Hydraulic cylinder is commonly used in hydraulic transmission and control system. When the hydraulic cylinder drives the parts to the stroke terminal, violent mechanical collisions often occur. This kind of mechanical impact will not only affect the working performance of the hydraulic cylinder, but also damage other components of the hydraulic system. Therefore, the study of hydraulic cylinder buffer is particularly important. In this paper, five kinds of commonly used hydraulic cylinder internal buffer devices, such as fixed throttle, cylindrical annular throttle, groove throttle, conical annular throttle and parabolic annular throttle, are analyzed. The mathematical model of buffering process is established and simulated by MATLAB, and the buffering characteristics of each buffer device are discussed. The analysis shows that the buffering performance is different, and the peak pressure of each buffer device during the buffer process is large. Although all of them ensure that there is no sudden change in the speed, that is, there is no hard impact, the fixed throttle outlet is fixed. If the acceleration of groove throttling and parabolic ring gap throttling is too large at the buffer starting point or end point, there will be soft impact. Thus, five kinds of commonly used buffering devices can not achieve the optimal buffering characteristics. Generally speaking, there is no hard impact, but if there is soft impact, it will still cause harm to the hydraulic cylinder. Therefore, the optimal hydraulic cylinder buffer device should be simple and easy to realize, and its ideal buffer characteristic should be to avoid hard impact and reduce or eliminate soft impact under the condition of low buffer pressure. In this paper, a kind of hydraulic cylinder buffer device is designed according to the theoretical throttling area curve obtained from the ideal buffering characteristic, taking the working condition requirement of the push plate oil cylinder of the block forming machine as an example. The snubber consists of a number of circular holes, which are not equal in number along the axial direction, and are compact in structure and easy to process and manufacture. Taking the difference between the actual throttle area and the theoretical throttle area at the end of the hydraulic cylinder as the constraint condition, the number of orifice and the position of the orifice are reasonably designed, so that the actual throttling area is closer to the theoretical throttle area. The performance is closer to the ideal buffering characteristic. At the same time, the mathematical model of the new structure is established, and its performance is simulated. It is verified that the new structure not only has the buffering performance of no hard impact and low soft impact, but also has good soft start characteristics. The buffering performance of hydraulic cylinder is not only related to the buffer structure but also to the load. In order to achieve non-impact or small impact buffering, it is necessary to design the buffer structure of hydraulic cylinder according to the specific working conditions. The new buffer structure can realize the shock free buffer process, but the design and calculation process is complicated. Therefore, the design software of the new type hydraulic cylinder inner buffer device is developed by using MATLAB and VB software. After the user input different operating parameters in the interface, the speed and stroke relation, acceleration and stroke relation and theoretical throttling area change curve of the new type of hydraulic cylinder internal buffer device can be obtained, and the relationship between the speed and the stroke, the acceleration and the stroke, and the theoretical throttling area change curve can be obtained. At the same time, the number and distribution of holes under the optimum buffer characteristics are obtained. Thus, the design of the new type hydraulic cylinder inner buffer device is completed in a short time. Finally, the practical value of the software is proved under the verification of an example.
【學位授予單位】：太原理工大學
【學位級別】：碩士
【學位授予年份】：2011
【分類號】：TH137.51

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