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  本文選題：熱態(tài)鍛件的尺寸 + 溫度場函數(shù)��； 參考：《燕山大學》2015年碩士論文

【摘要】：大型鍛件是現(xiàn)代工業(yè)設(shè)備的核心部件,而大型鍛件的生產(chǎn)工藝和鍛造水平是國家制造力的重要標志之一。在高溫條件下,大型鍛件的制造生產(chǎn)工藝十分復(fù)雜,并十分耗費能源和材料,且造價極大。因此,大型鍛件的質(zhì)量保證和鍛造工藝的改善對提高制造生產(chǎn)力和國民經(jīng)濟效益有著十分重要的意義。在大型鍛件的熱態(tài)成形過程中,鍛造工藝優(yōu)化的重要理論依據(jù)來源于鍛件尺寸、溫度、高徑比,壓下量等工藝參數(shù)的研究。在眾多的鍛造工藝參數(shù)中,鍛件尺寸和溫度是可以通過現(xiàn)代先進測量手段直接實時獲取的,這為進一步研究鍛件尺寸和溫度的變化規(guī)律以及兩者之間的相互關(guān)系打下了基礎(chǔ)。實時地掌握鍛件尺寸和溫度的變化規(guī)律以及兩者之間的相互關(guān)系,可以及時有效地調(diào)整鍛造工序,從而可以很大程度地提高鍛件的內(nèi)部質(zhì)量和鍛造精度,進而為優(yōu)化鍛造工藝提供可靠的理論依據(jù)。因此,本文基于鍛造過程中實時測量的鍛件尺寸和溫度,以構(gòu)建鍛件尺寸和溫度之間的相互影響關(guān)系模型。首先,基于鍛造過程中鍛件的熱傳導理論和熱源理論,對熱態(tài)鍛件尺寸變化影響下的溫度場進行分析,并將鍛件溫度場分解為溫降和溫升時的兩個溫度場函數(shù)進行研究。結(jié)合鍛造過程中鍛件尺寸和溫度的測量信息,以修正鍛件尺寸變化時的傳熱系數(shù)計算公式,并利用二維非穩(wěn)態(tài)傳熱模型來求取溫降時的鍛件溫度場函數(shù)�；谀芰渴睾阍�,構(gòu)建鍛件尺寸變化時的功能關(guān)系函數(shù),并進一步改進其功能轉(zhuǎn)換系數(shù)。結(jié)合鍛件功能關(guān)系函數(shù),利用可移動坐標系下的虛擬熱源法求得鍛件溫升時的溫度場函數(shù)。通過疊加溫降和溫升時的鍛件溫度場函數(shù),以構(gòu)建鍛件尺寸變化時的溫度場模型。其次,基于熱態(tài)鍛件內(nèi)部成形質(zhì)量參數(shù)的變化過程以及內(nèi)部應(yīng)力變化的特性,從不同的角度對鍛件溫度對鍛件尺寸變化的影響關(guān)系進行分析,并利用多元函數(shù)微分法以求取鍛件尺寸變化和應(yīng)力之間的關(guān)系函數(shù)。結(jié)合鍛件形變時的能量函數(shù)和尺寸應(yīng)變公式,對鍛件能量形變參數(shù)進行分析和求解,以獲取鍛件溫度與應(yīng)力之間的關(guān)系函數(shù),并以鍛件應(yīng)力為中介變量來構(gòu)建鍛造過程中鍛件溫度影響下的尺寸變化模型。最后,結(jié)合上述所建立的鍛件溫度和尺寸變化模型,利用實驗室和鍛壓現(xiàn)場條件構(gòu)建鍛造模擬實驗,以獲取的鍛件測量信息和實驗結(jié)果。并利用Deform-3D軟件對鍛件的鍛造過程進行模擬仿真。通過仿真和實驗結(jié)果的對比分析來驗證模型的可行性,并進一步對模型的可行性進行分析,以明確鍛件溫度和尺寸變化關(guān)系模型的實際意義,為優(yōu)化鍛造工藝提供可靠地理論依據(jù)。
[Abstract]:Large-scale forgings are the core parts of modern industrial equipment, and the production technology and forging level of large-scale forgings are one of the important symbols of national manufacturing force. Under the condition of high temperature, the manufacturing process of large forgings is very complex, energy consuming and material consuming, and the cost is enormous. Therefore, the quality assurance of large forgings and the improvement of forging technology are of great significance to the improvement of manufacturing productivity and national economic benefits. In the hot forming process of large forgings, the important theoretical basis of forging process optimization comes from the research of technological parameters such as forging size, temperature, ratio of height to diameter, reduction of weight and so on. Among the many parameters of forging process, the forging size and temperature can be obtained directly and in real time by modern advanced measurement methods, which lays a foundation for further study on the variation law of forging size and temperature and the relationship between them. To master the changing law of forging dimension and temperature in real time and the relationship between them can adjust the forging process in time and effectively, thus greatly improve the internal quality and forging precision of forging parts. Thus, it provides a reliable theoretical basis for optimizing forging process. Therefore, based on the real time measurement of forging size and temperature during forging process, a model of the interaction between forging size and temperature is constructed in this paper. Firstly, based on the heat conduction theory and the heat source theory, the temperature field under the influence of the change of the size of the hot forging is analyzed, and the temperature field of the forging is decomposed into two temperature field functions of temperature drop and temperature rise. Combined with the measurement information of forging size and temperature during forging process, the formula of heat transfer coefficient is corrected when the forging size changes, and the temperature field function of forging is obtained by using two-dimensional unsteady heat transfer model. Based on the principle of energy conservation, the function relation function of forgings with dimension change is constructed, and the function conversion coefficient is further improved. Based on the function of forging, the temperature field function of forgings during temperature rise is obtained by using the virtual heat source method in movable coordinate system. The temperature field model of forgings when the size of forging is changed is constructed by adding the temperature field function of the forgings with temperature drop and temperature rise. Secondly, based on the changing process of internal forming quality parameters and the characteristics of internal stress change of hot forging, the influence of forging temperature on the change of forging size is analyzed from different angles. The multivariate function differential method is used to obtain the relation function between the dimension change and stress of forgings. Based on the energy function and dimension strain formula of forgings during deformation, the parameters of energy deformation of forgings are analyzed and solved in order to obtain the relationship function between temperature and stress of forgings. The model of dimension change under the influence of forging temperature is constructed with the stress of forging piece as the intermediate variable. Finally, based on the model of temperature and dimension change of forgings, the forging simulation experiments are constructed by using the laboratory and forging field conditions to obtain the forgings' measurement information and experimental results. The forging process is simulated by Deform-3D software. The feasibility of the model is verified by comparing the simulation results with the experimental results, and the feasibility of the model is further analyzed in order to clarify the practical significance of the relationship between the temperature and the size of the forgings. It provides a reliable theoretical basis for optimizing forging process.
【學位授予單位】：燕山大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TG316

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本文編號：1999525