五噸單頭液壓放料機設計圖紙+論文+報告

五噸單頭液壓放料機設計圖紙+論文+報告,五噸單頭,液壓,放料機,設計,圖紙,論文,報告,講演,呈文 河南理大學本科畢業(yè)設計（論文）磨削過程中應力殘留摘要：本論文闡述了對表面磨削殘留應力的調(diào)查研究結果。功率密度加上磨輪/工件接觸時間形成系數(shù)因子B。論文描述了用于估測不同的加工材料，進行本實驗。實驗估測出了加工參數(shù)對系數(shù)因子B及系數(shù)因子B與最大殘留應力間關聯(lián)的影響。這種用于預測表面磨削殘留應力的系數(shù)因子的可用性得到了證實。關鍵詞：殘留應力；磨削；磨輪/工件1.序言磨削適用于加工硬質(zhì)材料的最常用的方法之一，它常常是工藝流程中最后操作步驟之一。因此，磨削過程中的表層特性直接創(chuàng)建形成了工件的功能特性。如疲勞強度，磨蝕及腐蝕抗性等。在磨削過程中，尤其是當使用氧化鋁磨輪時，由于兩個相反的趨向，要形成理想的表面平整度是相當困難的。一方面，為提高生產(chǎn)效率，需引入高加工參數(shù)，然而，這些參數(shù)往往會引起加工工件表面的磨削功率的提高。另一方面，磨削功率的提高使磨削溫度提高，可能造成（磨削）表層嚴重損壞。由于在其他常規(guī)方法中缺少相對簡單統(tǒng)一的措施，要在高生產(chǎn)效率和優(yōu)良的表層特性間找到平衡點是極其困難的。正是由于磨削步驟地重要性，許多研究中心已對這一過程進行調(diào)查研究，一些常用的方法已被闡明。方法之一：分析法4，5，依據(jù)數(shù)學方法，對表面形成過程中涉及的物理過程進行描述。在磨削過程中熱效應因子常常被描述。在對工件溫度分布的計算基礎上，對表層的微硬度、殘留應力、微結構等這些變化進行估測。這種方法前景廣闊但就目前而言，由于復雜的計算，以及對在極端磨削條件下材料反應的有限認知水平僅限于理論上的調(diào)查研究。實驗法1，7以找磨削條件與表層參數(shù)間關聯(lián)為目標。這是一種相對簡單的方法，但存在一些缺陷。它通常是以時間資本消耗為過程，其應用受到限制。而且，在不同的磨削方法與磨削條件下，推算實驗結果可能受到限制。針對表層形成控制問題，還有第三種方法，將那些與表層特性關聯(lián)密切的磨削系數(shù)列入研究范疇2，4。這類系數(shù)因子廣泛存在，其中最常見的有：相同碎片厚度（heq）和功率密度（p）。前者在磨削陶瓷制品時使用，后者常常應用于當使用氧化鋁磨輪時磨削的研究過程。這兩種因子的主要缺陷是：測算時，必須對磨削有效深度或磨輪/工件有效接觸長度進行估算。而在實際的磨削過程中，這兩個量值又很難估算準確。因此，仍然缺乏與表面平整參數(shù)密切相關且容易估算的磨削系數(shù)因子。就系數(shù)因子（功率密度與磨輪/工件接觸時間）與表面磨削殘留應力之間的關聯(lián)，調(diào)查研究闡述如下：2.磨削系數(shù)（功率密度與接觸時間） 實驗證明，磨削后表層殘留應力與最高磨削溫度密切相關。對磨削溫度計算方程式的分析表明，不僅是功率密度才影響磨削溫度，還有另外一個重要因子，即磨輪/工件接觸時間。在表面磨削過程中，具體工件與熱源（磨輪）間的接觸時間可通過以下方程式計算： tc=le/vw 其中l(wèi)e磨輪/工件有效接觸長度；vw工作速度 假設的磨削系數(shù)B由功率密度P和接觸時間tc構成： 其中，p為磨削總功率；bd磨削寬度。 該系數(shù)因子的最大優(yōu)勢即是，在實際磨削過程中，方程式中所有的量（磨削功率，磨削寬度及工作速度）能夠很簡單地被測算。3.實驗設置 本實驗在以下磨削條件的基礎上進行。*加工材料（工件）：炭化鋼0.45%C,28HRC（標注S）；合金鋼40H(0.38%C,0.9%Cr,0.28%N),48HRC;軸承鋼LH15(相當于100 Cr)62HRC(L)。*磨輪：38A60J8V(J),99A80M7V(M)*磨輪速度：26m/s(恒定)*磨削深度：0.0050.06mm*工作速度：0.080.5m/s*磨削液體：乳化劑或無 研究表明，主磨輪的驅(qū)動功率，車床的速度調(diào)節(jié)范圍，及可能出現(xiàn)的，在表層形成的不可能接受的變化(如微裂痕，磨痕等)都限制這些磨削參數(shù)。 要估算系數(shù)因子B，必須測得磨削功率，工作速度及磨削寬度。測量磨削功率有兩種方法：通過測量磨輪主驅(qū)動耗損（實際）（pm）,并同時測量相關的磨削力F1和磨輪速度V。由此，磨削功率可通過方程式來計算。由兩種方法獲得的實際結果對照如表1所示。從圖表中不難看出其中的關聯(lián)，表明了當只有磨輪被主驅(qū)動器驅(qū)動時，只要測量磨輪主驅(qū)動耗損功率即可準確估算系數(shù)因子B。磨輪速度通過移位變極器測量，磨削寬度即場地樣品寬度。4. 實驗結果 通過測量表面磨削過程中p, vw和bd的值，在每次磨削試驗中均可計算出系數(shù)因子B。在磨削過程中所測得測量值能夠便于估測磨削條件對系數(shù)因子B的影響（表2-7）。從表2，4。6中可看出有效磨削深度與B之間的線性依賴關系。這些直線的傾斜度主要由磨輪，工作速度(表2，6)，及磨削液體（表4）決定。以數(shù)字統(tǒng)計的形式近似的正確性在所有情形下值都高于0.9。 工作速度對B的影響（表3，5，7）不像磨削深度的影響那樣始終不變。在一個低范圍工作速度，vw對B的影響很大，表明通過改變工作速度來影響系數(shù)因子B可能受到限制。對于調(diào)查研究的第三種加工材料合金鋼(H),實驗得到類似的關系結果。 實驗中，若不存在微裂痕和磨痕，殘留應力分布的測量可通過熟知的材料移除法進行。從每次磨削試驗所得的殘留應力表面深度圖表中，可確定表層的最大殘留應力。通常，在接近表面1020um深度時，殘留應力達到最大值（可伸縮量）. 對所研究的加工材料，系數(shù)因于B與最大殘留應力間的關系如表8-10所示。在這些圖表中，不考慮其他磨削條件（磨輪特性，磨削液體，磨削參數(shù)），總結得出了各種加工材料的實驗結果。在每種條件，以數(shù)字統(tǒng)計的形式稱呈現(xiàn)各自的線性依賴關系（R0.8529-0.9074)。 這些數(shù)據(jù)表明，對于所給定的加工材料，殘留應力-系數(shù)因于B曲線傾斜度呈現(xiàn)特征性，不受其他磨削條件的影響。軸承鋼（L）傾斜度最大表（10）。合金鋼（H）傾斜度最小表（9）。挑查研究中的其他一些結果表明，應用系數(shù)因于B預測或控制表層的微裂痕、磨痕或微結構等變化化為可能。該系數(shù)因于在其他磨削方法中的可用性有待證實 。 5.結論磨削系數(shù)B(功率密度與磨輪/工件接觸時間)被用于預測表面磨削過程中的殘留應力。實驗發(fā)現(xiàn)系數(shù)因于B與最大殘留應力間的線性相關，并經(jīng)多種加工材料證實。系數(shù)因于B與最大殘留應力間的關聯(lián)似乎不受磨削條件的影響。系數(shù)因于B隨著磨削深度的加深而現(xiàn)行遞增，隨工作速度的提升而遞減，表明在較高工作速度范圍內(nèi)B反映不強烈。即使是在實際的工業(yè)應用中，系數(shù)因于B也不難計算。（6）系數(shù)因于B可能用于磨削過程中諸如微裂痕、磨痕、微結構等表層特性的預測。參考文獻：附科技文原文 AbstractResults of investigations on residual stress in surface grinding are presented in the paper. A coefcient B combining power density andwheel/workpiece contact time was developed. Experimental set-up and software to estimate the coefcient during grinding are described inthe paper. Experiments were carried out for surface plunge grinding for several workmaterials in a wide range of grinding conditions. Theinuence of process parameters on the coefcient B as well as the relation between B and maximum residual stress were experimentallyevaluated. The usefulness of the coefcient to predict residual stress in surface grinding was proved. # 2001 Elsevier Science B.V. Allrights reserved.Keywords: Residual stress; Grinding; Wheel/workpiece 1. IntroductionGrinding is one of the most popular methods of machininghard materials. Because it is usually one of the nal operationsof the technological process, properties of surface layercreated in grinding inuence directly the functional propertiesof the workpiece such as fatigue strength, abrasive andcorrosion resistance, etc.Creating favourable surface integrity, especially in grindingwith aluminium oxide grinding wheels is difcult due totwo opposite tendencies. On one hand, high process parametersare preferred in order to increase productivity.Unfortunately, such parameters usually lead to the increaseof grinding power engaged in creation of the new surface ofthe workpiece. On the other hand, the increase of grindingpower makes grinding temperatures grow, which may causea serious damage to the surface layer created in grinding.Finding a compromise between high productivity andadvantageous surface layer properties is extremely difcultdue to the lack of relatively simple and universal routines,among others. Because of the importance of grinding operationthe investigations of this process are performed in manyresearch centres. Some general approaches are observed inthese investigations.The rst one, strictly analytical 4,5, is based on themathematical description of physical processes involved insurface layer creation. In grinding thermal effects are usuallydescribed. On the basis of the calculations of temperaturedistribution in the workpiece, such changes in surface layerlike microhardness, residual stresses, microstructure, etc. areestimated 5. Such an approach is very promising but at thepresent stage it is limited to theoretical investigationsbecause of complex calculations and still limited knowledgeabout material behaviour in extreme grinding conditions.The experimental approach 1,7 aims at nding a correlationbetween grinding conditions and surface layer parameters.This is a relatively simple method with somedisadvantages. Experimental works are usually time- andcapital-consuming which limits their application. Moreover,there is a limited possibility to extrapolate the experimentalresults on different grinding methods and grindingconditions.There is also a third approach to the problem of control ofsurface layer creation, which involves a search for suchgrinding coefcients, which are strongly correlated withsurface layer properties 2,4. There are many such coef-cients existing. The most popular are: equivalent chipthickness (heq) and power density (P0). The former is provedto be useful in grinding ceramics, the latter is often appliedwhen grinding with aluminium oxide grinding wheels isinvestigated 2.The main disadvantage of both coefcients is that tocalculate them it is necessary to estimate the effectivegrinding depth or effective wheel/workpiece contact length.Both values are very difcult to estimate on-line grindingaccurately.Thus, an easy-to-estimate grinding coefcient, whichwould be strongly correlated with surface integrity parameters,is still lacking. The investigation on the correlationbetween the coefcient combining power density and thewheel/workpiece contact time and residual stress in surfacegrinding is described below.2. Grinding coefcient combining power density andcontact timeIt was proved 3 that residual stresses in surface layerafter grinding are closely correlated with maximum grindingtemperature. The analysis of equations used for temperaturecalculation in grinding 6 indicates that it is not only thepower density that inuences the grinding temperature butthere is also a second important factor wheel/workmaterialcontact time. In surface grinding the contact time ofthe particular workpiece point with heat source (grindingwheel) can be easily calculated astc .levw(1)where le is an effective wheel/workpiece contact length andvw is the workspeed.The proposed grinding coefcient B is a product of powerdensity P0 and contact time tc:B . P0tc .Pbdlelevw .Pbdvw(2)where P is the total grinding power and bd the grindingwidth.The rst advantage of this coefcient is that all quantitiesin this equation (grinding power, grinding width and workspeed)are easy to measure on-line in a grinding process.3. Experimental set-upExperiments were carried out for the following grindingconditions._ workmaterials: carbon steel 0.45% C, 28HRC (marked S),alloy steel 40H (0.38%C, 0.9%Cr, 0.28% Ni) 48HRC (H),bearing steel H15 (equivalent to 100Cr6) 62HRC (L);_ grinding wheels: 38A60J8V (J), 99A80M7V (M);_ wheelspeed: 26 m/s (constant);_ grinding depth: from 0.005 to 0.06 mm;_ workspeed: from 0.08 to 0.5 m/s;_ grinding fluid: emulsion or none.Grinding parameters in these investigations were limitedby the power of the main wheel drive, table speed regulationrange and by the appearance of unacceptable changes in thesurface layer, microcracks and burns.To estimate coefcient B it was necessary to measuregrinding power, workspeed and grinding width. Grindingpower was measured in two different ways: by the measurementof power consumed by wheel main drive (Pm) andsimultaneous measurement of tangential grinding force Ftand wheelspeed vs. The grinding power can then be calculatedcalculatedas Pc . Ftvs. The comparison of the results obtainedfrom both methods is shown in Fig. 1. A very good correlationcan be seen from this gure, which proves that measurementof power consumption of wheel main drive isaccurate enough to estimate coefcient B in the case whenonly grinding wheel is driven by this drive. The wheelspeedwas measured by means of displacement transducer andgrinding width was taken as a width of the sample beingground.4. Experimental resultsOn the basis of measured values of P, vw and bd in surfacegrinding, the coefcient B was calculated in each grindingtest. Measurements carried out during grinding allowed, rstof all, to evaluate the inuence of grinding conditions on thecoefcient B, cf. Figs. 27. The linear dependence betweeneffective grinding depth and B can be seen from Figs. 2, 4and 6. Slopes of these lines depend mainly on grindingwheel, workspeed (Figs. 2 and 6) and on grinding uid(Fig. 4). The correctness of linear approximation was provedin a statistical wayvalues of R2 were higher than 0.9 in allcases.The inuence of workspeed on coefcient B, Figs. 3, 5and 7, is not as uniform as those obtained for grinding depth.Much higher inuence of vw on B is observed for a lowerrange of workspeeds. It indicates that there is a limitedpossibility to inuence coefcient B by changes of theworkspeed. Very similar dependencies were obtained forthe third workmaterial investigated alloy steel (H).For all experiments, in which microcracks and/or burnswere not present, residual stress distribution was measuredby means of the well-known material removal method. Fromresidual stress vs. depth below surface diagrams obtained foreach grinding test, maximal residual stresses in the surfacelayer were determined. Usually, residual stresses reach theirmaximum (tensile values) close to the surface on depths of1020 mm.Relations between coefcient B and maximum residualstress for investigated workmaterials are shown in Figs. 810. In these diagrams the results are summarised for eachworkmaterial regardless of other grinding conditions (grindingwheel properties, grinding uid, grinding parameters). Ineach case the linear dependence was assumed which wasproved in a statistical way (R2 from 0.8529 to 0.9074).It results from these gures that the slopes of residualstress-coefcient B lines are characteristic for the givenworkmaterial and seem to be independent of other grindingconditions. The highest slope was obtained for bearing steel(L), Fig. 10, and the lowest one for alloy steel (H), Fig. 9.Some additional observations recorded during investigationsindicate that there is a possibility to use the coefcientB to predict and/or control such changes in surface layer likemicrocracks, burns or microstructure changes. Additionalinvestigations are necessary to conrm the usefulness of thiscoefcient in other grinding methods.5. Conclusions1. The grinding coefcient B combining power density andwheel/workpiece contact time was developed to predictresidual stress in surface grinding.2. A linear correlation between coefcient B and maximumresidual stress was found experimentally. It wasconrmed for several workmaterials.3. The relation between coefcient B and maximumresidual stress seems to be independent of grindingconditions.4. Coefcient B increases linearly with the increase ofgrinding depth and decreases with the increase ofworkspeed. This decrease shows less intensity in therange of higher workspeeds.5. The coefcient B is easy-to-estimate, even on-line, inindustrial practice.6. The coefcient B may be useful in predicting suchsurface layer properties in grinding like microcracks,burns or microstructure changes.References1 P.G. Althaus, Residual stress in internal grinding, Ind. Diamond Rev. 3(1985) 124127.2 E. Brinksmeier, H.K. Tonshoff, Basic parameters in grinding, Ann.CIRP 42 (1) (1993) 795799.3 E. Brinksmeier, S.T. Comet, W. Konig, P. Leskovar, J. Peters, H.K.Tonshoff, Residual stress-measurement and causes, Ann. CIRP 31 (2)(1982) 491510.4 B.W. Kruszynski, C.A. Luttervelt, An attempt to predict residualstresses in grinding of metals with the aid of the new grindingparameter, Ann. CIRP 40 (1) (1991) 335337.5 H.K. Tonshoff, J. Peters, I. Inasaki, T. Paul, Modelling and simulationof grinding process, Ann. CIRP 41 (2) (1992) 677688.6 E. Vansevenant, A subsurface integrity model in grinding, Ph.D.Thesis, KU Lueven, 1987.7 Y. Zheyun, H. Zhonghui, Surface integrity of grinding of bearing steelGCr15 with CBN wheels, Ann. CIRP 38 (1) (1989) 677688.注： 11