本文選題：拔長 + V型砧�。� 參考：《安徽工業(yè)大學(xué)》2017年碩士論文

【摘要】：軸類大鍛件的發(fā)展應(yīng)用與各行業(yè)領(lǐng)域中大型設(shè)備的運(yùn)轉(zhuǎn)息息相關(guān)。用于生產(chǎn)大鍛件的坯料,內(nèi)部會存在不同程度的疏松、孔洞等缺陷,集中在中心軸線附近,影響鍛件質(zhì)量。而且隨著坯料尺寸改變和重量的增加,坯料芯部缺陷更加嚴(yán)重。這些缺陷的存在直接影響了大鍛件的運(yùn)轉(zhuǎn)和壽命期限。相對于其它生產(chǎn)工藝,鍛造是改善和消除大型鍛件芯部缺陷較為有效的方法。利用鍛造方法來修復(fù)大鍛件內(nèi)部缺陷,就是要在有缺陷的區(qū)域上能夠產(chǎn)生足夠大的變形量和足夠高的靜水壓應(yīng)力,二者缺一不可。本文結(jié)合生產(chǎn)實(shí)際,應(yīng)用有限元軟件MSC.SuperForm對軸類大鍛件拔長過程進(jìn)行熱力耦合數(shù)值模擬,分析了在多種拔長過程中鍛件芯部鍛透性和內(nèi)部應(yīng)力應(yīng)變分布規(guī)律。研究表明,V型砧拔長,鍛后鍛件內(nèi)部等效應(yīng)變分布不均勻,各處變形差異較大,經(jīng)三道次拔長后,鍛件芯部鍛透性較好,平均累積等效應(yīng)變可達(dá)1.6。四砧徑向鍛造,鍛件外層金屬變形較大,芯部金屬變形較小,鍛件芯部鍛透性較差,經(jīng)四道次拔長后,端部中心最小等效應(yīng)變小于0.2;中間部分等效應(yīng)變較大,芯部累積等效應(yīng)變?yōu)?.8左右。V型砧拔長,在拔長過程中鍛件內(nèi)部應(yīng)力表現(xiàn)為兩拉一壓、兩壓一拉和三向壓應(yīng)力狀態(tài);四砧徑向鍛造,芯部周圍始終存在軸向拉應(yīng)力區(qū)域。無論是V型砧拔長還是四砧徑向鍛造,鍛件芯部平均應(yīng)力都為負(fù),有利于芯部缺陷的鍛合。為提高四砧徑向鍛造變形滲透性,本文還分析了四砧徑向鍛造過程中錘頭的尺寸和形狀、轉(zhuǎn)速、壓下量、軸向送進(jìn)量等工藝參數(shù)對鍛件芯部鍛透性的影響規(guī)律,為軸類大鍛件芯部缺陷的鍛合提供參考依據(jù)。
[Abstract]:The development and application of shaft forgings are closely related to the operation of large equipment in various industries. For the production of large forgings, internal defects such as porosity and holes will exist in varying degrees, which are concentrated near the central axis and affect the quality of forgings. And with the change of the blank size and the increase of weight, the defects of the blank core become more serious. The existence of these defects directly affects the operation and lifetime of large forgings. Compared with other production processes, forging is an effective method to improve and eliminate the core defects of large forgings. In order to repair the internal defects of large forgings by forging method, it is necessary to produce large enough deformation and high hydrostatic stress in the defective region. In this paper, the thermo-mechanical coupling numerical simulation of the drawing process of large axial forgings is carried out by using the finite element software MSC.SuperForm, and the forging permeability and stress and strain distribution of the core in various drawing processes are analyzed. The results show that the internal equivalent strain distribution is not uniform and the deformation difference is great. After three times of drawing, the forging core has better forging permeability, and the average cumulative equivalent strain can reach 1.6. In the four anvil radial forging, the outer metal deformation of the forgings is large, the core metal deformation is small, the forging permeability of the forgings core is poor, the minimum equivalent strain of the end center is less than 0.2 after the four-pass drawing, the equivalent strain of the middle part is larger, The cumulative iso-effect of core is about 0.8. During the process of drawing, the internal stress of the forgings is shown as two tension and one press, two pressure and one tension, and three direction compressive stress, and the axial tensile stress region always exists around the core in the radial forging of four anvil. The average stress of the core of the forging is negative, which is beneficial to the forging of the core defect, whether the V-shape anvil is long or the four-anvil is radial forging. In order to improve the deformation permeability of four-anvil radial forging, this paper also analyzes the influence of the technological parameters such as the size and shape of hammer head, rotational speed, reduction amount and axial feed rate on the forging permeability of the forging core during the four-anvil radial forging process. It provides the reference for forging the core defect of the shaft type big forgings.
【學(xué)位授予單位】：安徽工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG316

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