影响机械加工精度的各种因素.docx

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1、影响机械加工精度的各种因素摘要:本文根据多年经验,结合国内外机组相关资料,阐述水轮机主要焊接部件结构变形的主要种类,介绍焊接变形的火焰矫形的施工方法。Abstract: this paper based on years of experience, combined with domestic and foreign units related information, this turbine main welding parts structure deformation of the main types, introduces construction method of weldi

2、ng deformation of flame straightening.关键词:水轮机;火焰矫形;焊接变形Key words: hydraulic turbine; Flame straightening; Welding deformation目前,大型水轮机部件已经大量的采用焊接结构。而水轮机主要焊接部件是由座环、顶盖、底环等部件组成。这些构件在制作过程中都存在焊接变形问题,如果焊接变形不予以矫正,则不仅影响结构整体安装,还会降低工程的安全可靠性。At present, the large turbine parts have a lot of welding structure. A

3、nd turbine main welding parts consists of seat ring, the top and bottom ring parts. These artifacts welding deformation problems in the production process, if the welding deformation is not corrected, will not only affect the structure of the overall installation, would also reduce the safety and re

4、liability of engineering.焊接水轮机部件产生的变形超过技术设计允许变形范围,应设法进行矫正,使其达到符合产品质量要求。实践证明,多数变形的构件是可以矫正的。矫正的方法都是设法造成新的变形来达到抵消已经发生的变形。Turbine parts from the welding deformation is more than technical design allows the deformation range, should try to to correct, to conform to the requirements of the quality of the

5、product. Practice has proved that most of the deformation of the component can be correct. Correction methods are trying to cause a new deformation to achieve offset has happened.在生产过程中普遍应用的矫正方法,主要有机械矫正、火焰矫正和综合矫正。但火焰矫正是一门较难操作的工作,方法掌握、温度控制不当还会造成构件新的更大变形。因此,火焰矫正要有丰富的实践经验。本文对水轮机部件焊接变形的种类、矫正方法作了一个粗略的分析。

6、Correction methods in general use in the process of production, the main have mechanical correction, flame straightening and comprehensive correction. But the flame correction is a more difficult operation work, improper control, temperature control also creates new bigger deformation. Therefore, fl

7、ame correction should have rich experience in practice. In this paper, a correction of welding deformation type turbine components, method makes a rough analysis.1 水轮机部件焊接变形的种类与火焰矫正1 the kinds of welding deformation and flame straightening turbine parts水轮机部件的主要构件是焊接H型结构(如座环)、箱体结构(如顶盖,底环)、支撑结构。焊接变形经常

8、采用以下三种火焰矫正方法:(1)线状加热法;(2)点状加热法;(3)三角形加热法。下面介绍解决不同部位的施工方法。The turbine parts of main component is welded H structure (such as seat ring), enclosure structure (such as roof, bottom ring), support structure. Welding distortion often use the following three methods of flame correction: (1) linear heating

9、 method; (2) dot heating method; (3) triangular heating method. To solve different parts of the construction method is described below.以下为火焰矫正时的加热温度(材质为低碳钢)Flame correction for the temperature (is made of mild steel,低温矫正 500度600度 冷却方式:水Low temperature correction cooling way: 500 600 degrees of water

10、中温矫正 600度700度 冷却方式:空气和水In 600 700 degrees temperature correction cooling: air and water高温矫正 700度800度 冷却方式:空气High temperature correction 700 800 degrees cooling: air注意事项:火焰矫正时加热温度不宜过高,过高会引起金属变脆、影响冲击韧性。16Mn在高温矫正时不可用水冷却,包括厚度或淬硬倾向较大的钢材。Note: flame correction when the heating temperature is unfavorable a

11、nd exorbitant, become fragile, too much can cause metal impact toughness. 16 mn in high temperature correction is water cooling, including the tendency of hardenability thickness or larger steel.1.1座环环板及顶盖、底环盖板的上拱与下挠及弯曲1.1 seat inside board and the top plate, bottom ring under the arch and the torsi

12、on and bending一、在座环环板及顶盖、底环盖板上,对着纵向焊缝,由中间向两端作线状加热,即可矫正弯曲变形。为避免产生弯曲和扭曲变形,两条加热带要同步进行。可采取低温矫正或中温矫正法。这种方法有利于减少焊接内应力,但这种方法在纵向收缩的同时有较大的横向收缩,较难掌握。A, here inside board and the top and bottom ring plate, to the longitudinal weld, from middle to both ends of line heating, bending deformation can be corrected.

13、 In order to avoid bending and torsion deformation, two tropical to synchronize. Can take corrective or medium temperature correction method at low temperature. This method is beneficial to reduce welding stress, but this method at the same time of longitudinal contraction have larger transverse con

14、traction, more difficult to master.二、座环环板及顶盖、底环盖板上作线状加热,在固定导叶或肋板上作三（版权声明：本文转载自论文网在线()，版权归原作者所有。）角形加热。用这种方法矫正座环环板及顶盖、底环盖板的弯曲变形,效果显著,横向线状加热宽度一般取2090mm,板厚小时,加热宽度要窄一些,加热过程应由宽度中间向两边扩展。线状加热最好由两人同时操作进行,再分别加热三角形三角形的宽度不应超过板厚的2倍,三角形的底与对应的翼板上线状加热宽度相等。加热三角形从顶部开始,然后从中心向两侧扩展,一层层加热直到三角形的底为止。加热固定导叶或肋板时温度不能太高,否则造成凹陷

15、变形,很难修复。2, seat inside board and the top, bottom ring linear heating cover, on the fixed guide vane or floor three (net of paper of copyright statement: this article reprinted from online (), all peer originator.) Angle of heating. Corrected by this method inside board and the top and bottom ring pl

16、ate of the bending deformation, the effect is remarkable, transverse linear heating width generally take a 20-90 mm, thickness, heat width is narrow, heating process should be the width on both sides to expand in the middle. Linear heating is best done by two people at the same time operating, then

17、respectively heating triangle triangle width should not be more than thickness of 2 times, at the bottom of the triangle with a width equal to the corresponding linear heating on the wing. Heating starting at the top of the triangle, and then expanding from the center to both sides, layers of heatin

18、g until the end of the triangle. Fixed guide vane or floor heating when the temperature not too high, cause otherwise sag deformation, difficult to repair.1.2座环环板及顶盖、底环盖板的波浪变形1.2 inside board and the top and bottom ring plate of the wavy deformation矫正波浪变形首先要找出凸起的波峰,用圆点加热法矫正。加热圆点的直径一般为5090mm,当钢板厚度或波浪

19、形面积较大时直径也应放大,可按d=(4+10)mm(d为加热点直径;为板厚)计算得出值加热。烤嘴从波峰起作螺旋形移动,采用中温矫正。当温度达到600700度时,将手锤放在加热区边缘处,再用大锤击手锤,使加热区金属受挤压,冷却收缩后被拉平。矫正时应避免产生过大的收缩应力。矫完一个圆点后再进行加热第二个波峰点,方法同上。为加快冷却速度,可对Q235钢材进行加水冷却。这种矫正方法属于点状加热法,加热点的分布可呈梅花形或链式密点形。注意温度不要超过750度。Correction must first find the bump of the wave, wave deformation correct

20、ion with dot heating method. Heating of dots is 50 90 mm in diameter, and when the thickness of steel plate or wavy area larger diameter should also enlarge, can press d = (4 delta + 10) mm (d to add hot spot diameter; the delta for thickness) heating value is calculated. Baked mouth from wave crest

21、 make spiral movement, using the temperature correction. When the temperature of 600 700 degrees, put hammer heating zone edge, reoccupy hammer hammer, and make the heating area of metal by extrusion, cooling contraction after leveling. Correction should avoid excessive shrinkage stress is produced.

22、 Finish recruit a dot after the heat wave point, the second method is same as above. In order to speed up the cooling speed, can be add water cooling for Q235 steel. This correction method belongs to the dot heating method, add the hot spot can show the distribution of the plum flower form or chain

23、dense point form. Pay attention to the temperature does not exceed 750 degrees.1.3支撑结构的角变形1.3 Angle deformation of the support structure矫正支撑结构角变形。在筋板的上面(对准焊缝外)纵向线状加热(加热温度控制在650度以下),注意加热范围不超过两焊脚所控制的范围。线状加热时要注意:(1)不应在同一位置反复加热;(2)加热过程中不要进行浇水。这两点是火焰矫正一般原则。Correct Angle of supporting structure deformatio

24、n. Aim on the top of the stiffened plates (weld) longitudinal linear heating (heating temperature control at 650 degrees Celsius), pay attention to heat the scope not more than two legs control range. Linear heating should pay attention to: (1) should not be in the same place repeatedly heating; (2)

25、 not to water in the heating process. These two points is a correction of flame general principles.2 结语2 in the火焰矫正引起的应力与焊接内应力一样都是内应力。不恰当的矫正产生的内应力与焊接内应力和负载应力迭加,会使部件的纵应力超过允许应力,从而导致承载安全系数的降低。因此在水轮机部件制造中一定要慎重,尽量采用合理的工艺措施以减少变形,矫正时尽量可能采用机械矫正。当不得不采用火焰矫正时应注意以下几点:Flame straightening as stress and the weldin

26、g stress is caused by internal stress. Inappropriate and the internal stress produced by orthodontic welding stress and load stress superposition, can make the parts of longitudinal stress exceed the permitted stress, thus resulting in a loss of load safety factor. So you should be careful in the tu

27、rbine components manufacturing, adopting reasonable technology measures to reduce deformation as far as possible, as far as possible when corrected may adopt mechanical correction. When forced to by flame correction should be paid attention to the following:1、烤火位置不得在环板或盖板最大应力截面附近;1, the fire locatio

28、n may not be in ring plate or plate near the maximum stress cross-section;2、矫正处烤火面积在一个截面上不得过大,要多选几个截面;2, correct the fire area is on a section may not be too big, want to choose more a few cross section;3、宜用点状加热方式,以改善加热区的应力状态;3, appropriate USES dot heating mode, in order to improve the heating area

29、 stress state;4、加热温度最好不超过700度。4, heating temperature, had better not exceed 700 degrees.待加工后冷却到室温时其长度和直径将有所收缩,由此而产生尺寸误差;加工盘类零件或较短的轴套类零件,由于加工行程较短,可以近似认为沿工件轴向方向的温升相等。对于较长工件(如长轴)的加工,开始走刀时,工件温度较低,变形较小。随着切削的进行,工件温度逐渐升高,直径逐渐增大,因此工件表面被切去的金属层厚度越来越大,冷却后（版权声明：本文转载自论文网在线()，版权归原作者所有。）不仅产生径向尺寸误差,而且还会产生圆柱度误差;对于轴向

30、精度要求较高的工件(如精密丝杠),其热变形引起的轴向伸长将产生螺距误差。After being processed cooling to room temperature when the length and diameter will shrink, the resulting size error; Processing plate parts or short sleeve parts, due to the processing schedule is shorter, can approximate equal thought along the axial direction o

31、f the workpiece temperature rise. For relatively long pieces, such as long axis processing, started feeding, workpiece temperature is low, the deformation is smaller. As cutting, workpiece temperature increased, the diameter gradually increases, so the workpiece is cut to the surface of the metal la

32、yer thickness increasing, after cooling (net of paper of copyright statement: this article reprinted from online (), all peer originator.) Not only produce radial size error, but also produces the cylindricity error; Axial accuracy requirement for higher artifacts (e.g., precision lead screw), the t

33、hermal deformation caused by axial elongation pitch error will occur.5.3.2 工件不均匀受热5.3.2 workpiece uneven heating当工件受热不均时,如磨削零件单一表面,由于工件单面受热而产生向上翘曲变形,加工冷却后将形成中凹的形状误差,这种现象对于加工薄片类零件尤为突出。When the workpiece is heated unevenly, such as single surface grinding parts, up warping deformation due to single heated workpiece, processing after cooling to form a concave shape error, this phenomenon is especially for processing sheet parts.