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重 慶 理 工 大 學
文 獻 翻 譯
二級學院 機械工程學院
班 級 109040205
學生姓名 方敏 學 號 10904020506
防竄焊接滾輪架軸向竄動實驗研究
摘要：簡述焊接滾輪架軸向竄動的基本理論,并同時在焊接滾輪架的實驗模型上進行了試驗研究。 結(jié)果表明, 焊接滾輪架軸向竄動的主要原因在于工件的翻轉(zhuǎn)存在著螺旋夾角， 本文主要分析了螺旋角和工件的圓周速率對竄動的影響。
關(guān)鍵詞:焊接滾輪架 軸向運動 螺旋角 筒體線速度
1.簡介
在大厚壁、大型化、高容量、耐磨蝕的鍋爐、石油、化工壓力容器的焊接生產(chǎn)中，由于焊接滾輪架的制造安裝誤差以及筒體幾何形狀的不規(guī)則（偏離理想回轉(zhuǎn)體）等原因，筒體在滾輪架上轉(zhuǎn)動時，會不可避免的沿其軸向發(fā)生竄動，從而影響環(huán)縫的焊接質(zhì)量。若不進行防竄處理，出現(xiàn)的竄動量大便無法進行焊接。本課題研究提供了當圓形工件焊接時，軸向竄動的機制.設(shè)計反竄動焊接滾輪架. 尤其是應用于滾輪架之上。
2. 實驗
2.1.實驗描述
在圖1中試驗表明,初步的試驗研究了兩個因素:螺旋角和工件的線速度-影響軸向竄動的主要因素。 在實驗過程， 軸向位移Sa和軸向竄動速度Va測量方法如圖1。而進行的方法是將軸向位移傳感器安裝到的圓筒的一端，與傳感器相連的X-Y記錄器記錄工件的軸向位移,每5s記錄一次,平均竄動速度Va在每個角度可以計算出數(shù)據(jù)。在試驗階段，實驗模型是如下:一、調(diào)節(jié)四滾輪高度在同
一個水平線上，并在矩形的四個頂點，那么滾輪與旋轉(zhuǎn)工件相對平衡，工件在一段很長的時間不竄動，或定期竄動一個很小的范圍。
2.2實驗結(jié)果的討論
2.2.1螺旋角的影響
(1)例如圖2所示。Va的變化檢測條件是: vc=35m/h L=422mm , α=60"
Va是與tanβ4成正比的，β4 是與(1~~~6c )相關(guān)的，坡度線為3. 06毫米/秒,Va不再正比tanβ4時, 當β4大于6c,軸向竄動是隨著β4逐漸減小 。 由于只有一個驅(qū)動滾輪(roller No.4)的影響, β4可以改變的,而其他的仍然是零,工件作出了協(xié)調(diào)的運動。當β4的比例較小,Va也小。 圓柱體軸向摩擦力,滾輪最大軸向摩擦力,汽缸產(chǎn)生彈性滑針對滾輪， 軸向運動之間各滾輪和工件協(xié)調(diào)彈性滑動。因此Va是:
理論曲線的斜率k可以按下列公式計算:
k=3.06mm/s的實驗曲線。因此,在考慮到各方面的實驗,兩個斜坡上可被認為是大致相等。 當β4 比較大, 滾輪與工件之間最大軸向摩擦力大于最大摩擦力, 工件產(chǎn)生的摩擦滑動抵抗?jié)L輪存在的滑動摩擦力，由于竄動的存在,Va不再隨著tanβ4的增加而增加,而是逐漸減小。
(2)以下三個實驗,工件的不協(xié)調(diào)軸向竄動隨之改變。由同一螺旋角度來衡量的一個主動滾輪及兩個，三個主動滾輪 。三曲線之間的Sa和Va研究結(jié)果顯示如上圖，隨著滾輪數(shù)量的增加,Va逐漸增大。
Va 3 > Va 2 > Va1
當驅(qū)動滾輪的數(shù)量變化時, 度氣缸的非兼容軸向運動將會有所改變. 隨著同一螺旋角影響下滾輪數(shù)量的增加。兼容的分量越來越大,但互不兼容的分量越來越小。換句話說,工件的軸運動將轉(zhuǎn)化為是否兼容的問題。 因此,最大軸向竄動Va由β角所決定，四輪有相同的螺旋角時Va為:
2.2.2 筒體線速度的影響
螺旋角從平衡位置+2’對4號驅(qū)動滾輪的影響。工件將影響軸向竄動（例如下圖）所顯示va-VC的曲線,后者表明Va是與Vc成正比的, 曲線的斜率大約是0.00708。因為β4=+2實在太小, 工件相對每一滾輪沒有形成軸向竄動。 因此,軸滾輪和工件之間的相對運動是完全協(xié)調(diào)的彈性滑動，Va為：
Va正比于Vc。理論曲線的斜率k可以按下列方程 K"=0.25tan4=0.25tan2'=0.00873wherek=0.00708mm/s. 因此,在考慮到各方面的實驗,協(xié)調(diào)的兩個斜坡上可被認為是大致相等.
3.結(jié)論
（1）因為制造及裝配的偏差，工件的中心線與滾輪軸線不平行，沒有在同一平面,因此形成螺旋角β，存在β是發(fā)生軸向竄動的主要原因。工件軸線方向重力的分量影響,也是軸向竄動的一個原因。
（2）合理調(diào)整軸運動,使不兼容的分量盡可能小和兼容分量盡可能大從而減小軸向竄動。
（3）隨著滾輪數(shù)量的增加相同β角下的軸向竄動將增大,但不兼容的部分減少。隨著兼容部分的增加工件的軸向竄動速度將增加，當軸向滑動摩擦發(fā)生在滾輪和工件之間時， 軸向竄動將被彈性摩擦和滑動摩擦所協(xié)調(diào)，但Vc并不與β成正比，關(guān)系如下：
參考文獻：
(1) Z Wang. 焊接機械設(shè)備教材，甘肅蘭州工業(yè)大學， 張培源(1992)pp85-98
(2)武漢材料技術(shù)研究所，南京化工研究所,與華南工學院，水泥生產(chǎn)機械設(shè)備, 建筑工業(yè)出版社，中國北京,(1981)pp,184-187
(3) J . Halling(ed.)， 麥克米倫出版社,(1975)pp. 174-200
Experiment and study into the axial drifting of the cylinder
of a welding rollerbe
Abstract ：The basic theory of the axial drifting of the cylinder of a welding roller bed is introduced in the paper,and at the same time experiment and study on the mechanism of the axial drifting of the cylinder have been done on an experimental model of the welding roller bed . It is shown that the main cause of the axial drifting of the cylinder lies in the existence of a spiral angle between the cylinder and the cylinder and the roller.This article mainly analyzes the spiral Angle and circumferential velocity's influence on the channeling motion artifacts.
Keywords:welding roller bed axial motion spiral angle Cylinder linear velocity
1 Introduction
The Welding and Production in the big Thick-Cliff、The Large-Scale、High-Content、Endure-Ablation of the pressure vessel of the Boiler、Oil、chemical,because of reason of the error of the manufacture-installation and the abnormity of geometry-form of the cylinder(departure ideal gyration object),the cylinder wheel on the roller bed,inevitably it will occur axial drifting,so that affect the welding quality. If not take the anti-floating measure,the welding cannot going because of the large drifting. This topic research when the circular workpiece welding, axial drifting mechanisms. Design the dynamic welding roller frame. Especially applied to the roller frame.
2.Experiment
2.1 Descriphm of experment
The experimental model is shown in Fig 1. Experiments were done to study two factors: the spiral angle and the cylinder’s circular linear velocity, which affect the axial drifting of the cylinder. In the experimenting process. the axial displacement Sa and the axial drifting velocity Va of the cylinder were measured by the variation of the two factors described above. The measuring method is shown in Fig. 1, and is carried out by means of bringing an axial displacement sensor into contact with one end of the cylinder. with the sensor being connected to an X-Y recorder to record the cylinder’s axial displacement every 5s. Linearly regressing the plot Sa--t (t expresses time), the average drifting velocity Va, at every deflecting angle can be calculated. Before experimenting. the experimental model is initialised as follows: first. the height of the four rollers is adusted by means of a level to put the centers of the four
rollers in the same horizontal plane, and at the four vertexes of the rectangle. then the rollers are deflected so that the rotating cylinder is at the relative equilibrium position. Then the cylinder does not drift over a long time. or periodically drift over a very small axial range
2.2experiment results and discussion
2.2.1 Effect of spiral angle (I) Fig. 6 shows that change of Va with the variation ofThe testing condition is: positive rotalion, Vc=35m/h
L=422mm, α=60”
The Va-tanβ4 curve shows that Va is directly proportional to tanβ4 whenβ4 is relatively small (1~~~6c ). The slope of the line being 3. 06 mm/s, Va is no longer direclly proportional to tanβ4 when β4, is greater than 6C The curve is an arched curve. i. e . with the increment of β4,.Va, increases. but with the increment of Va gradually becoming smallet Because only one driven roller (roller No. 4) is deflected, i.e β4 can be changed whilst the others remain zero, the cylinder makes a non-compatible motion. When β4 is relatively small, Va is small also. The axial frictional forces between the cylinder and rollers are less than the maximum axial frictional force, and the cylinder produces an elastic sliding against rollers. Axial motion between each roller and the cylinder is coordinated by elastic sliding. thus Va is:
in the theoretical curve, the slope K’ can be calculated by
the following equation:
K=3.06mm/s in the experimental curve. Thus, in taking account of the experimental tolerance, the two slopes can be considered to be approximately equal. When β4 is relatively large, the axial frictional forces between the cylinder and the rollers are larger than the maximum axial frictional Force, and cylinder produces frictional sliding against the rollers Because of Ihe existence of sliding frictional resistance. Va is no longer lincarty increased with the increment of tanβ4 With the increment of tanβ4 the increment of V a; with gradually become smaller
(2) The following three experiments were arranged to study the cylinder’s non-compatible axial motion further, deflecting positively one roller. two rollers and three rollers by the same spiral angle to measure three curves between Sa and v The experimental results are shown in Fig 7. With the increment in the number of deflected rollers, Va becomes greater. i e Va 3 > Va 2 > Va1
When the number of driven rollers deflected is varied, the degree of the cylinder’s non-compatible axial motion will be changed. With the increment of the number of lollers deflected by the same spiral angle. the compatible component becomes greater, but the non-compatible component becomes smaller. In other words, the cylinder’s axial motion will be transformed from noncompatible motion to compatible motion. Thus, Va becomes greater also, ultimately, being equal to the compatible axial velocity determined by the spiral angle β Now. the four rollers have the same spiral anyle β. So that Va is:
2.2.2 effect of circular linear velocity
Deflecting driven roller No 4 to a spiral angle of +2”from the equilibrium position, the cylinder will suffer axial drifting, Fig. 8 shows the Va-Vc curve, which latter indicates that Va is directly proportional to Vc, the slope of the curve being approximately 0.00708 because β4=+2 is too small, the cylinder does not make frictional sliding against each roller. Thus, the relative axial motion between the roller and the cylinder is completely coordinated by their elastic sliding, so that Va is
I. e .Va is directly proportional to Ve For the theoretical Curve the slope K * can be calculated by the following equation K”=0.25tanβ4= 0.25tan2'=0.00873 where K=0.00708mm/s in the experimental curve. Thus, in taking account of the experimental tolerance, the two slopes can be considered to be approximately equal.
3 Conclusions
(1).Because of the deviations due to manufacturing and assembling. the cylinder’s central line and the roller’s axis are not parallel. i. e , they are not in the same plane, and there is a spiral angleβ at thc point of contact between the cylinder and the roller in the circular linear velocity direction. The existence of βis the basic reason for the occurrence of axial drifting. The effect of gravity in cylinder’s axial direction is also one of reasons for drifting.
(2)The reasonable adjustment of the axial motion is to make the non-compatible component as small as possible and the compatible component as large as possible.
(3)With the increment of the number of rollers deflected by the same value of βthe compatible component of axial velocity increases, but the non-compatible component decreases. With the increment of the compatible component, the velocity of axial drifting of the cylinder increases
References:
(1) Z Wang(ed ). teaching material on welding machinery Equipment Gansu university of Technology lanzhou P R china (1992) pp 85-98
(2)Wuhan lnstitulcof Buildins Materials and TechnologyI Tongi Universily. Nanjing Institute of Chemical Engineering, and Huanan Institute of Technology. Cement Producing machinery equipment, Architectural Industrial Publishing House of China, Beijing, (1981) pp, 184-187
(3)J . Halling(ed.). Principles of Trilrology The Macmillan Press, (1975) pp. 174-200