發(fā)布時間：2018-04-23 23:35

  本文選題：短電弧銑削加工 + 電極損耗�。� 參考：《新疆大學(xué)》2017年碩士論文

【摘要】：面對目前高硬度、高強度、高韌性難加工材料應(yīng)用領(lǐng)域及范圍的日益增多,特種加工以其獨有的加工優(yōu)勢為機械制造業(yè)中遭遇的瓶頸開辟了一片新天地,其中包括短電弧加工,它主要是利用極間放電通道中產(chǎn)生的高溫和爆炸力對工件進行去除加工,并且在加工中利用帶一定壓強的氣液混合介質(zhì)將熔化的金屬廢渣沖走。此過程中工具與工件之間本文首先分析了短電弧加工的放電機理,掌握放電通道形成原理、熟悉工件材料被蝕除過程,并采用Thermcamvision A40紅外熱成像儀觀察了實際加工中極間溫度的變化情況,為了避免發(fā)生短路時溫度過高燒毀工件,對不同控制方法的優(yōu)缺點進行比較后,本文提出在控制系統(tǒng)中引入模糊控制算法。本研究的出發(fā)點是對短電弧銑削加工進行優(yōu)化,實現(xiàn)低電極損耗、高加工效率的目的。通過實驗和閱讀文獻發(fā)現(xiàn)正常加工時,引起電極損耗的主要因素包括電參數(shù)(電壓幅值、占空比、頻率)的變化、電極材料的選取、工作介質(zhì)的狀態(tài)、進給量的大小。為了探究不同因素對電極損耗的影響情況,實驗采用單因素分析法,在設(shè)定其他研究參數(shù)不變的情況下,選取多組試驗參數(shù)進行對比,得出電極損耗相對較小的加工狀態(tài)。但在實際加工中,由于放電參數(shù)不連續(xù)、蝕除材料未及時排除等原因會造成短路,此時工具電極與工件材料之間出現(xiàn)“機械加工”,這樣會加劇電極的損耗量,降低工件質(zhì)量。為了避免這種情況,本文提出建立基于模糊PID控制算法的自適應(yīng)控制系統(tǒng),將電信號的實際值與系統(tǒng)設(shè)定閾值的偏差及偏差變化率作為控制器的輸入,根據(jù)控制系統(tǒng)制定的模糊規(guī)則自適應(yīng)調(diào)整控制器的輸出,并對此數(shù)學(xué)模型進行Simulink仿真驗證其可行性。由于加工中通過電流大小來判斷工件與工具的間隙,因此針對電流信號的采集,本文通過對比分析采用了PCI-1716數(shù)據(jù)采集卡,以Delphi 7.0作為開發(fā)工具,運用信號發(fā)生器SG2040A發(fā)送信號,將示波器所顯示的波形與Delphi采集界面顯示的波形進行對比,發(fā)現(xiàn)兩組波形一致,驗證了該采集系統(tǒng)的可行性。
[Abstract]:In the face of the increasing application field and scope of high hardness, high strength and high toughness materials, special machining has opened a new world for the bottleneck encountered in the mechanical manufacturing industry with its unique processing advantages, including short arc processing. It mainly uses the high temperature and explosive force produced in the inter-pole discharge channel to remove and process the workpiece, and the molten metal waste slag is washed away by the gas-liquid mixed medium with a certain pressure in the process. In this process, this paper first analyzes the discharge mechanism of short arc machining, grasps the principle of discharge channel formation, and is familiar with the etching process of workpiece material. Thermcamvision A40 infrared thermal imager is used to observe the change of interpolar temperature in actual processing. In order to avoid excessive temperature burnout of workpiece during short circuit, the advantages and disadvantages of different control methods are compared. In this paper, a fuzzy control algorithm is introduced into the control system. The purpose of this study is to optimize the short arc milling process to achieve low electrode loss and high machining efficiency. Through experiments and reading literature, it is found that the main factors causing electrode loss during normal processing include the change of electrical parameters (voltage amplitude, duty cycle, frequency), the selection of electrode material, the state of working medium, and the size of feed rate. In order to explore the influence of different factors on electrode loss, the single factor analysis method was used in the experiment. Under the condition of setting other research parameters unchanged, several groups of test parameters were selected for comparison, and the processing state of electrode loss was found to be relatively small. However, in practice, because of the discontinuous discharge parameters and the non-timely removal of the etched materials, the short circuit will occur. At this time, there will be a "machining" between the tool electrode and the workpiece material, which will aggravate the loss of the electrode and reduce the quality of the workpiece. In order to avoid this situation, an adaptive control system based on fuzzy PID control algorithm is proposed in this paper. The deviation between the actual value of electrical signal and the threshold value of the system and the rate of deviation change are taken as the input of the controller. The output of the controller is adaptively adjusted according to the fuzzy rules established by the control system, and the feasibility of this mathematical model is verified by Simulink simulation. Because the gap between the workpiece and the tool is judged by the current size in the machining process, the PCI-1716 data acquisition card is adopted in this paper by comparing and analyzing the current signal, and the signal generator SG2040A is used to send the signal with Delphi 7.0 as the development tool. By comparing the waveform displayed by oscilloscope with that displayed by Delphi acquisition interface, it is found that the two groups of waveforms are the same, which verifies the feasibility of the acquisition system.
【學(xué)位授予單位】：新疆大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG661;TG54

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