焊接技術(shù)及其自動化畢業(yè)論文

1、焊接技術(shù)及其自動化畢業(yè)論文 (Welding technology and automationgraduation thesis )Welding technology and automation graduation thesis topic: low alloy steel T welding joint deformation, measurement and calculation: Department of materials science and engineering, material forming and control engineering, welding t

2、echnology and automation in welding heat input due to high concentration in the process of transient, in the process of the welding will inevitably produce welding the stress and deformation, and the welding deformation of the appearance of the structure, bearing capacity, service performance and ot

3、her aspects have many negative effects, so it has very important practical significance for analysis and estimation of welding residual deformation. Based on the T component as the research object, making unbeveled or groove welding procedure test, analysis of factors affecting the welding deformati

4、on, especially in the process of welding heat input makes the key discussion; longitudinal shrinkage of T type welds are measured, calculating the deformation amount is calculated in. Based on the simplified science, and the estimated values are compared with the measured value. The experimental res

5、ults show that the selected welding parameters in line with the actual welding requirements formula properly, the welding process and deformation calculation method can provide theoretical basis for the actual production. Keywords: T joint; welding deformation; Abstract Welding is a reliable heat in

6、put and effective method of material connecting so it is widelyapplied to various industries. The presence of residual deformation affects not only thestructure of the dimensional accuracy and appearance and may reduce its carryingcapacity and mechanicalperformance so welding distortion prediction a

7、nd control is veryimportant. With the computer and the development of finite element analysis computersimulation of mechanical behavior of the welding process to become an essential way theuse of inherent strain method to predict welding deformation is a typical example. In thispaper T-welded compon

8、ents for the study analysis and forecasting using the inherentstrain M Ethod T-welded components transverse contraction and longitudinal contraction.Focus on the inherent strain analysis method and computer application process werestudied.Key words: T-joint Welding distortion Heat input Introduction

9、 1 chapter of welding deformation and its influencing factors 31.1welding deformation causes 31.2welding deformation and the classification of the association between 41.3 weldingdeformation factors 7 1.3.1material factors 7.Effects of 1.3.2 structural design factors 7 1.3.3welding methods8 1.3.4 we

10、ldinglayers 8 1.3.5joint type 81.3.6 weld cross-sectional area of welding deformation influence 91.4. The preventionand control of welding deformation. The method 9 1.4.2接 10 1.4.3減少不必要的焊道 11 1.4.4 反變形法 111.4.5 剛性固定法 11 1.4.6錘擊焊縫法 11 第二章 T 型構(gòu)件焊接工藝及焊接變形測 試 12 2.1寸 的成分及性能 12 2.3 焊接工藝參數(shù)的選擇 驟 2.5 焊接變形的測

11、量與結(jié)果 17的計算 17 3.1 焊接變形計算方法 析法 183.1.2 熱彈塑性有限元法 法 203.2.1 固有應(yīng)變 203.2.2 固有應(yīng)變法焊接變形的解析法 223.3算 233.4間斷焊試件的材料及尺12 2.2 材料13 2.4 焊接步16第三章 變形17 3.1.1 解18 3.2 固有應(yīng)變試件焊接變形的計The calculated and measured iscompared233.5 experimental analysis of causes for errors 23references Thanks26 28. Welding technology and au

12、tomation graduation thesis introduction welding applications as the connection of a flexible and efficient method widely in bridges, shipbuilding, construction, aviation, pressure vessel manufacturing and with the rapid development of China's steel structure industry, welding technology has been

13、 widely used in steel structures, various production departments in various fields of industry and agriculture, the welding structure throughout the national economy. From the private traffic to rocket missiles and other vehicles, from agricultural machinery to all kinds of precision machinery and h

14、eavy and is everywhere. However, the residual deformation of welded structure that has plagued the field of welding, this phenomenon has become the focus of the concern. The welding deformation is not only cause the welding structure of shape variation, reducing the size accuracy and bearing capacit

15、y, and the additional moment caused by work load and stress concentration is the main reason of early failure of the welding structure, one of the reasons is caused by the welding structure fatigue strength reduction. These defects are main thermal welding process caused unreasonable. Due to the hig

16、h concentration of transient heat input, and welding in the welding process will produce large welding residual stress and deformation of welding residual deformation, welding shrinkage, warpage welding residual stress, dynamic stress produced in the welding process and welding residual stress defor

17、mation andwelding defects,The stability but also affect the structure of the processing precision and size in a certain degree. Therefore, in the design and construction must fully consider the characteristics of welding stress and deformation. Welding is one of the most important ways to connect me

18、tal materials into components, either adding or not adding filler metal, including the surfacing weld, the welding process of the most core technology is connecting surface melting, followed by continuous cooling, local heat input form partial melting, and as far as possible to reduce heat dissipati

19、on to the internal components and the loss of heat to the surrounding environment, the welding process is a process of uniform and rapid heating and cooling. The melting welding, welding metal by local heating and melting in the heat under the effect of mechanical properties of the material will cha

20、nge significantly, but also directly determines the welding process of the weld and heat affected zone, microstructure after welding residual stress and deformation of the size, so the accurate calculation and determination of welding thermal process is the premise of welding stress and deformation

21、analysis. To make it simple, commonlyused in the actual welding concept as a classification system will be decomposed into welding thermodynamics, mechanics and microstructure of the process, so as to reduce the complexity of the phenomena of welding. In the process of welding and welding structure

22、willinevitably produce weldingdeformation, and the deformation of welding in the construction of the most troublesome is the most difficult to deal with problems. Welding distortion not only affects the structure and appearance of size precision and possibly reduce the bearing capacity and mechanica

23、l performance, more important is easy to cause the instability of welding structure. In the welding process, the welding deformation not only affects the welding structure of manufacturing process, the welding deformation will even seriously affect the manufacturing process, performance, structure o

24、f the welding joint fracture resisting ability, fatigue strength, anti stress 1 welding technology and automation graduation thesis corrosion cracking and creep cracking ability. The welding deformation analysis and estimation of welding deformation has important significance. This paper is divided

25、into three chapters, the first chapter introduces the reasons and influencing factors of welding deformation, and analyzes the relationship between species and various types of welding deformation; in the second chapter, T type welding component as the research object, welding, and longitudinal shri

26、nkage of weld were measured; the third chapter discusses the estimation of welding deformation. And the estimated values are compared with the measured value, so as to provide theoretical basis for production practice. 2 welding technology and automation graduation thesis the first chapter of weldin

27、g deformation and its influencing factors of 1.1 welding deformation of welding stress and deformation is the result of interaction by a variety of factors caused. Usually, if only the effect of restraint in terms of welding stress and deformation can be express as follows. The welding heat input ca

28、used by local heating of inhomogeneous material, the weld zone and high temperature zone melting; thermal expansion and adjacent to the pool is surrounded by material constraints, resulting in uneven compressive plastic deformation; in the cooling process, this part has occurred compressive plastic

29、deformation is also restricted by the surrounding conditions, but not free contraction in different degrees by stretching and unloading; at the same time, solidification of molten pool, metal cooling shrinkage has also produced the corresponding shrinkage tensile stress and deformation. So, in the a

30、rea of welded joint has shortened incompatible strains. The welding deformation causes are the following: (1) the uneven local heating and cooling is the main reason. Whenwelding test plate is heated to melt the local state, form the uneven distribution of regional test plate temperature, the test p

31、late appears uneven thermal expansion, thermal expansion by the surrounding metal hindering free expansion under compressive stress, the surrounding metal is subjected to tensile stress. In the high temperature region near the weld seamside by thermal pressure, away from the weld side by thermal str

32、ess. Whenthe heated metal by pressure stress exceeds the yield point, will cause plastic deformation. The plate cooling, the weld has different cooling time, first the first welding solidification, has certain strength, prevent weld after welding in the horizontal expansion of freedom, which results

33、 in the transverse compression deformation.Weld cooling after welding when the transverse shrinkage is prevented, and the transverse tensile stress, and the first welding part produces transverse compressive stress. Dueto the heating of metal in heating has produced plastic deformation, so the compr

34、ession, finally a length less than the length of the metal heating is not short. (2) the weld metal and HAZ microstructure change. The weld and HAZ metal in welding when heated to the melting point or solid phase transition temperature above the metal cooling process to change. Because the volume of

35、 various tissues are different, so the volumechange occurs. (3) the rigid steel structure is symmetrical in structure, weld layout, reasonable welding procedure can only generate linear shortening; when the weld layout asymmetry, will produce bending deformation; the cross section of the weld joint

36、center of gravity and the center section in the same position, if the welding procedure is reasonable, only whenthe linear shortening; the cross section of the weld joint section of gravity center of gravity, will produce angular deformation. The weld amount is more, the greater the deformation. (4)

37、 welding component after forming, should according to the different geometric size and shape components makethe welding process correctly, the work on the control of welding deformation is significant, most of the amount of deformation is due to the welding process caused by incorrect, such as weldi

38、ng current, electrode diameter, welding speed of crude, will the welding deformation. 3 multilayer welding, welding technology and automation of graduation thesis of the first layer of weld shrinkage is the largest, the more layers of welding deformation is greater. Intermittent weld than the contin

39、uous weld shrinkage of small, welding sequence improper or not weld segment components, then assembled and welded, are easy to produce welding deformation in the construction, so it is important to develop reasonable welding process. 1.2 the classification of welding deformation and the relation bet

40、ween the welding deformation is generally in accordance with the deformation characteristics are divided into the following 7 categories: 1) transverse shrinkage due to the heating heat source of welding arc and subsequent cooling, the temperature is perpendicular to the welding member length and th

41、ickness direction is not homogeneous, which produce transverse shrinkage strain and transverse residual the stress in welding joint. Causes of transverse shrinkage, partly due to the shrinkage of weld metal after cooling, the other part is the expansion of the weld metal hot forming blocked transver

42、se residual plastic deformation caused by the. Transverse contraction deformation and the deflection deformation. The lateral deformation of the size of the welding line energy and thickness, with the increase of welding line energy, transverse shrinkage increases; with the increase of thickness, tr

43、ansverse shrinkage reducing. The distribution of transverse deformation along the weld length is not uniform. This is because the first transverse shrinkage welding of weld after a compression effect, which causes more lateral compression deformation. Therefore, the weld transverse contraction along

44、 the welding direction is increasing gradually increase, to a certain extent tends to be stable. In addition, the transverse shrinkage by manual electric arc welding automatic submerged arc welding when the transverse shrinkage ratio of plate thickness is similar to the small deformation by welding,

45、 when the transverse shrinkage ratio of transverse shrinkage of large amount of manual electric arc welding. If the asymmetric distribution of the transverse weld in the structure, so it can also cause the lateral contraction deformation of structure deflection. 2) the longitudinal contraction in we

46、lding, due to uneven temperature distribution along the weld direction, and near the weld metal had longitudinal compressive residual plastic deformation. The plastic deformation area called plastic deformation zone. The construction of longitudinal contraction deformation depends on the size of the

47、 plastic deformation zone, the construction area, and the length of weld welding line energy. Because of the plastic deformation zone by the contraction of the surrounding metal block, sorelatively less significant lateral contraction of longitudinal contraction. The theory that the longitudinal sys

48、tolic volume is about 1 / 1000 of the length of the weld. Longitudinal contraction deformation and flexural deformation caused by it. Longitudinal contraction deformation depends mainly on component length, cross-sectional area and compressive plastic deformation size. While the compressive plastic

49、deformation associated with the thermal physical parameters of materials and welding sequence, welding method, welding parameters. In the process of welding line energy Q (Qq/v, for energy,V is the main welding speed). In general, the relationship between longitudinal contraction deformation and wel

50、ding line energy is proportional to the. For the same cross-sectional area of the weld, the multilayer welding each welding line energy is much smaller than single-layer welding, so the longitudinal contraction caused by multilayer welding than single-layer welding small. The more layers, each layer

51、 with the line energy is smaller, the deformation is smaller. Similarly, the longitudinal contraction deformation of discontinuous welding than continuous welding is muchsmaller. When the weld in the 4 welding technology and automation graduation on file in the location of asymmetry, the weld induce

52、d stress is not uniform, so it not only makes the component shortened, also make the component bending deflection produced. The longitudinal and lateral retraction of figure 1-1. Figure 1-1 transverse shrinkage and longitudinal shrinkage 3) deflection component after welding bending in shape. Mainly

53、 because of the shrinkage of the same side or on both sides of the weld, shrinkage deformation and the other sideremains unchanged and cause, see figure 1-2. Figure 1-2 deflection angle deformation) 4. The angular displacement of crack plane around the weld after welding structure. Is mainly due to

54、the plate thickness direction of weld shrinkage deformation caused by different. In welding, butt and lap welding of T-joint, due to transverse contraction deformation in the thickness direction of the uneven distribution, tend to produce angular deformation. Angular deformation depends on the size

55、of the component size and distribution of compressive plastic deformation, but also depends on the stiffness of the plate. For the samethickness, with the increase of welding line energy, both sides of the plastic deformation quantity difference will increase, the angular distortion will also increa

56、se. But when the line energy reaches a certain value, the angular distortion is no longer rising, if further increase energy, but will decrease the phenomenonof deformation angle. This is because the line to further improve energy, making the board back with the increase of temperature, the amount o

57、f plastic deformation difference may reduce both positive and negative, so the angle deformation decreases. For the same thickness and groove type multilayer welding deformationthansingle-layer welding, welding more layers, the greater the deformation angle. Other than multi pass welding of multilay

58、er welding angular deformation to large deformation angle icon as shown in figure 1-3. 5 welding technology and automation graduation thesis figure 1-3 angle deformation of 5 wave deformation). The component after welding deformation is wavy, mainly in the welding of thin plate, is due to the presen

59、ce of weld residual stress of thin steel plate after welding, the internal force, the buckling, deformation wave form. Wave deformation in thin plate welding is more general. This is because in the welding, the welding stresses may occur instability (thin plate under pressure, when the pressure reaches a critical value, the sheet will be due to the emergence of wave transformation and loss of carrying capacity, this phen