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机械φ273钢管矫直机主传动系统设计

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编号:20649174    类型:共享资源    大小:8.71MB    格式:ZIP    上传时间:2019-07-07 上传人:QQ24****1780 IP属地:浙江
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273钢管矫直机主传动系统设计 钢管矫直机主传动系统设计 矫直机主传动系统 主传动系统设计
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机械φ273钢管矫直机主传动系统设计,273钢管矫直机主传动系统设计,钢管矫直机主传动系统设计,矫直机主传动系统,主传动系统设计
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辽宁科技大学本科生毕业设计 第14页Process for Straightening Tube and Method for Producing Tube TherewithTECHNICAL FIELDThe present invention relates to a tube straightening process and a tube production method, in which tube bendingin an axial direction and distortion of cross section (hereinafter referred to as ovality) are suppressed. More particularly ,the present invention relates to a tube straightening process in which generation of the ovality associated with bending correction is suppressed while tube bending correction accuracy is ensured, whereby a ratio (so-called S/N ratio) of signal tobase noise in flaw detection can be enhanced in an eddy current test from inside of a tube by inserting an inner probe and a tube production method in which the tube straightening process is used.RACKGROTLND ARTA U-shaped heat transfer tube utilized in a heat exchanger, such as a steam generator and a feed water heater ,which is used in a thermal or nuclear power plant is produced by bending a small-diameter and long-length heat transfer tube with an outside diameter of 30 mm or less into a U-shape .In the U-shape heat transfer tube, an inspection is performed to detect flaws by the eddy current test from the tube inside asa pre-service inspection after the U-shaped heat transfer tube is assembled in the heat exchanger or as an in-service inspection or a periodic inspection after the U-shaped heat transfer tube is in-service for a certain period. The eddy current test from the tube inside applies strict test criteria because of the need to ensure safety of nuclear power plant facilities.The eddy current test applying the test criteria similar to that of the pre-service inspection or periodic inspectionis also required for an inspection before shipment after the heat transfer tube is produced. As a result of the eddy current test, the heat transfer tube which fails the test criteria becomesnonconforming material. Even within the test criteria, it is necessary that the result of the eddy current test be recorded in each tube while correlated with relevant positions in an axial direction of the heat transfer tube.Usually the heat transfer tube is produced through cold working such as cold drawing and cold rolling and a heattreatment using a mother tube produced by hot extrusion. The bends in an axial direction and ovality of the tube, generated after the cold working and heat treatment, are corrected during a subsequent finishing process using a roll straightening machine. Not only many heat transfer tubes having smalldiameters are used in the heat exchanger, but also an installation space of the heat transfer tube becomes narrowed withminiaturizing heat exchanger. When the bend is generated in the heat transfer tube, a trouble such as interference with other parts is generated in assembling the heat transfer tube into the heat exchanger. Accordingly, it is necessary to ensure bendcorrection accuracy in the roll straightening machine. Usually a cross roll type straightening machine, in which plural drum type rolls are combined, is adopted in a configuration of the roll straightening machine used in thestraightening. There are many configurations in the cross type roll straightening machine according to a combination of the number of rolls, a layout (vertical and horizontal directions),and roll arrangement (opposing type and zigzag type). The FIG. 1 is a view showing an example of the roll layout of the cross roll type straightening machine. Plural pairs of straightening rolls Ra and Rb (collectively referred toas R) are provided in the roll straightening machine. The pairs of straightening rolls Ra and Rb each are vertically disposed as opposed to each other in such a state that directions of rotating axes cross in a plan view (actually, cross-wise passeach other in a spaced-apart relation in a front view). In the roll layout of FIG. 1, three pairs of straightening rolls Ral and Rbl, Rat and Rb2, and Ra3 and Rb3 are disposed on an inletside, the center, and an outlet side respectively, the rolls ofeach pair being opposed to each other, and auxiliary roll Rc is provided at an exit of the outlet-side straightening rolls. Usually the roll straightening machine having such roll layout of FIG. 1 is called (2-2-2-1) type straightening machine of a straightening roll pair Ral and Rbl. A height position in a vertical direction of a first pair of straightening rolls Ral and Rbl and a height position of a second pair of straightening rolls Rat and Rb2, adjacent to the first pair, can be also adjusted separately .In the bend correction, across angle 0oftherotatingaxis of each straightening roll R to a tube to be corrected 1, that is, a roll angle is adjusted such that contact faces of the tube to be corrected 1 fit in contours of the straightening roll ,the opposing rolls clearance between the straightening rolls Ral and Rbl is set slightly smaller than an outside diameter ofthe tube to be corrected 1 to impart a crush, and an offset is imparted to straighten the bend and correct ovality by adjusting the crush amount of the second pair of straightening rolls Rat and Rb2, adjacent to the first pair.Since high rigidity and wear-resistant properties are required for straightening rolls, the straightening roll is made of tool steel or ceramic, and the surface of the straighteningroll is formed by a curved line constituting a drum shape in consideration of a contact surface with a tube to be corrected so as to enable the tube having the outside diameter within a predetermined range to be straightened. After the heat treatment, the heat transfer tube whose bends and ovality are corrected by the roll straightening machine is subjected to aprocess such as cutting, and the inspection before shipment is performed to the heat transfer tube by the eddy current test from the tube inside.FIG. 2 is an example of a chart showing result of theeddy current test from inside of the heat transfer tube. As shown in FIG. 2, Signal S from Standard Flaw defined in thetest criteria and signal N having a predetermined period P areshown in the chart. The signal N is called base noise, and is caused by a minute dimensional fluctuation generated in an axial direction of the heat transfer tube. It is necessary that the magnitude of the signal N be decreased as much as possible inorder not to mistake the signal N for a signal caused by the detected flaw and in order to swiftly judgment whether the signal indicates the flaw to thereby improve the inspection efficiency. Hereinafter, a ratio of Signal S from Standard Flaw to Noise N is referred to as S/N ratio .For example, in the case where automatic judging ismade based on the signals shown in the chart during the eddy current test from tube inside, the large noise, that is, the small S/N ratio hides a signal from a small defect behind the base noise, which makes distinction between the small defect signal and the base noise harder .As described above, the base noise is caused by the minute dimensional fluctuation generated in an axial direction of the heat transfer tube. Therefore, in order to reduce the base noise, it is necessary to suppress the dimensional fluctuation such as bends and ovality in an axial direction of theheat transfer tube, that is, to enhance the dimensional accuracy along an axial direction of the heat transfer tube. Usually, in straightening the tube by the roll straightening machine, as shown in FIGS. 3 to 5, it is necessary that the roll angle, crush amount, and offset amountwhich are the setting conditions be determined to suppress the dimensional fluctuation such as the bends and the ovality in an axial direction of the heat transfer tube.FIG. 3 is a view explaining a relationship between the roll angle of the roll straightening setting conditions and a corresponding travel distance of the tube to be corrected .Assuming that mm) is an outside diameter of the tube to becorrected 1 and (0) is an angle (hereinafter referred to as roll angle) formed by an axial center of the tube to becorrected 1 and the rotating axis of the straightening roll R, a travel distance (hereinafter referred to as feed pitch) M(mm) of the tube to be corrected 1 per one rotation of thestraightening roll R is defined by the following equation (2): 。FIG. 4 is a view explaining the crush amount of theroll straightening setting conditions. As shown in FIG. 4, the tube to be corrected 1b, to which the crush is applied by the roll straightening, is rolled, while being pressed, and deformed into an elliptic shape. A crush amount(mm) is indicated by a difference between an outside diameter d of a pre-deformation tube to be corrected la and an opposing rollsclearance s of the straightening rolls Ra and Rb, and corresponds to a rolling reduction of the outside diameter of the tube to be corrected 1. The bend correction is performed to the tube to be corrected 1 by repeatedly rolling while pressing the tube to be corrected 1 across the total length. The crush amount (mm) is set by raising/lowering the straightening roll Ra.FIG. 5 is a view explaining the offset amount of the roll straightening setting conditions. An offset amount 8(mm) is indicated by a deflection in crush/roll height between the central pair of straightening rolls Rat and Rb2, and the bend correction is performed by imparting a bending stress tothe tube to be corrected 1. The crush height is set by raising the straightening roll Rb2, thereby adjusting the offset amount 8 (mm).As described above, in performing the straightening by the roll straightening machine, it is necessary that a certainlevel of load such as the crush and the offset be applied onto the tube in order to straighten the bends. However, sometimes dimensional fluctuation such as the ovality associated with the load becomes significant. Specifically, in the conventional process for straightening the heat transfer tube such as the steam genera for and the feed water heater, the tube having the excellentpre-straightening dimensional accuracy, for example, the heat transfer tube to which drawing is performed with ahigh-pressure drawing machine, sometimes increases in ovality after straightening to deteriorate the S/N ratio compared with thecross-sectional shape of the pre-straightening tubedue to the straightening performed by the roll straightening machine. On the other hand, when the bend correction isinsufficiently performed in straightening the heat transfer tube, the interference with other component is frequently generated in assembling the heat transfer tube into the heat exchanger, which makes the assembly work difficult. Accordingly, in straightening the heat transfer tube, it is necessarythat the dimensional fluctuation associated with the bend correction be suppressed while the tube bend correction accuracy is ensured. Therefore , there have been conventionally proposed various straightening techniques. In a straightening process disclosed in Japanese Patent Application Publication No. 61-286025, in order to perform the straightening without deteriorating roundness of the inner surface of the tube used in a hydraulic cylinder tube and the like, the offset is imparted to the tube using a cross opposing type roll straightening machine, and the straightening is performed while a predetermined load which does notsubstantially impart the crush is applied to the tube.In a straightening process disclosed in Japanese Patent Application Publication No. 2004-330297, in order to suppress roundness deviation in turning inner and outer surfaces of a cut ring used in a bearing race or the like, a residual stress generated in the tube after the straightening is lowered by a multi-roll straightening machine in which the offset amount is set at 12 mm or more and the crush amount is set at 0.6 mm or less, thereby obtaining a seamless steel tube having little dimensional fluctuation during the turning and excellent roundness.In a process disclosed in Japanese Patent Application Publication No. 60-184424, the roll offset amount and the crush amount are determined from a relationship between an index indicating a plastic region of the tube and a presumptive offset and crush amounts, picked in advance, and the roll position is set to perform the tube straightening, thereby improving the tube bend and/or roundness. However, in the straightening processes proposed inJapanese Patent Application Publication Nos. 61-286025,2004-330297, and 60-184424, it is not intended that the ovality or bends in an axial direction of the tube be corrected inorder to enhance the S/N ratio in the eddy current test from the tube inside.DISCLOSURE OF THE INVENTIONAs described above, in order to enhance the S/N ratio, it is necessary to suppress the minute dimensional fluctuation generated in an axial direction of the tube. As thedimensional fluctuation in the tube is increased, the base noise is increased during the eddy current test, and the distinction between signals and base noises is hardly made in detecting the extremely small defect in the tube inner surface .In view of the problem relating to the straightening of the tube which is the target of the eddy current test with inner coil method, an object of the present invention is to provide a tube straightening process in which, by properly managing the straightening operation as a finishing process after the tube cold working, the generation of the dimensionalfluctuation such as the ovality associated with the bend correction is suppressed while the tube bend correction accuracy is ensured, whereby the S/N ratio can be enhanced in the eddycurrent test from the tube inside, and a tube production method in which the tube straightening process is used .After various studies on the relationship betweenthe roll straightening conditions and the S/N ratio in the eddy current test from the tube inside were made to solve theproblem, the inventors focused attention on the fact that the constant period P (hereinafter referred to as noise pitch) ofthe base noise N emerging in the eddy current test substantially matches with the tube feed pitch M of the straightening roll R shown in FIG. 3. On the basis of the fact, the inventors investigated an influence of the post-roll straightening tube on the S/N ratioand possibly remaining bends using the heat transfer tube ,when the crush amount(and the roll angle 0 of the roll straightening conditions were changed while the offset amount 6 was kept constant (10 mm). The seven-roll (2-2-2-1) type straightening machine shown in FIG. 1 was used as the roll straightening machine, and a roll covered with a urethane resin having the spring type hardness Hs of 95 was used as the outlet-side three pairs of straightening rolls. A Ni-base alloy of ASME SB-163 UNS NO 6690 was used as a testing material, and a tube with the finished dimension comprising anoutside diameter of 19.14 mm, a wall thickness of 1.125 mm and a length of 10000 mm obtained through the cold drawingby the high-pressure drawing machine was used. Table 1shows the settingconditions of the roll straightening machine and resultsThe remaining bends shown in Table 1 is obtainedby inspecting, in particular, the bends near a tube end portion (hereinafter also referred to as nose bend) as the post-straightening tube bends. The nose bend is a bend after the bends generated in the cold working such as the cold drawing and the cold rolling and the subsequent heat treatment is straightened by the roll straightening machine. In the remaining bends of Table 1, o indicates good bend correction in which a bend amount over a distance from a tube end to theposition of 1000 mm away from the end becomes 1 mm or less, and x indicates insufficient bend correction in which the bend amount exceeds 1mm .In the S/N ratio, the eddy current test was performed from the tube inside under conditions of frequency of 550 kHz and differential bobbin coil type, a drilling through-hole of 0.66 mm was used as Standard Flaw, and a minimum value in overall S/N ratios that are derived by segmenting the total length of the tube into each segment of one feet and assessing a S/N ratio in each segment was set as the S/N ratioof the tube. In the case where the crush amount E and the roll angle 0 were changed while the offset amount 8 was kept constant, although the good correction was performed with little remaining bends for all the conditions, the S/N ratio could not reach 30 or more, which was the target value .Then, the tube was straightened by changing the offset amount while the crush amount and the roll angle were kept constant, and it was found that setting the offset amount within a proper range can eliminate the nose bend to ensure the bend correction accuracy after the tube straightening andenhance the S/N ratio to 30 or more, which is the target value in the eddy current test from the tube inside.The present invention is completed based on the above-described findings, and the gist thereof includes (1) a tube straightening process and (2) a tube production method therewith。FIG.1FIG.2FIG.3FIG.4FIG.5钢管矫直工艺以及生产钢管的方法技术领域本发明涉及到钢管矫直进程和管生产的方法,其中包括管在轴向的弯曲和横截面(下文中将它定义为椭圆度)的曲解,尤其,本发明与管矫直过程有关,其中与弯曲修正量有关的椭圆度的产生被阻止当管弯曲纠正精度被确定的时候。凭借一个信号比率(所为的S/N比率)对于裂缝检测中的基干扰能够在管内部的涡流探伤测试(通过嵌入一个内探测器)中被加强。钢管矫直的生产方法在管被矫直的过程中使用。背景技术一个型的热传导管在热交换的过程中被使用,例如锅炉和供热水器,它被使用在热或核电厂的生产中,通过弯曲一个小直径的并且长距离的带着一个或者更少外径热交换管到型。在型的热交换钢管中,一个检查被执行,去发现一个瑕疵通过对管的内部进行涡流探测,作为一个预先检测在这个型传热管在热交换器中被装配或者作为一个在职检测或者一个周期性的检测在这个型传热辊工作了一段时间。从钢管内部进行的涡流测试施行严格的测试标准,因为必须确保核电厂设施的安全。涡流测试使用的这个测试标准类似于预先检测的那个标准或者周期检测,同样要求在热传导管生产以后装运之前进行一次检测。涡流测试的结果是没有达到测试标准的热传导辊变成了不合格的材料。即使达到了测试的标准,这也是很有必要的对于涡流测试的结果被记录在每个管子上当符合相关位置在热传递辊轴线方向上。通常情况下热传递辊通过冷加工的方式被生产,如冷拔、冷轧和热处理(通过热挤压的方法使用一个母管进行生产)。在轴方向上的弯曲和管子(生产在冷拔和热处理之后)的椭圆度通过使用一个轧辊矫直机被修正。不仅许多有小直径的传热管被使用在热交换器上。而且热传导辊的安装空间变的狭窄由于使用热交换器。当在热传导辊中弯曲产生的时候,一个麻烦例如其它部分的干扰会产生在装配这个热交换辊到热交换器上的过程中,因此,这是很有必要的对于在辊式矫直机中确定弯曲修正精度。通常一个跨辊式矫直机,与复数滚筒式卷相结合,是通过在配置滚动矫直机矫直中使用的。有许多配置中的交叉型辊矫直机根据组合的数目卷布局(垂直和水平方向),并滚动安排(反对型和锯齿型)。图片一是一个例子关于交叉辊式矫直机的布局。多元对矫直辊RA和Rb(统称为R )是提供给辊矫直机的。这对矫直辊Ra和Rb每个都是垂直处置的,而不是彼此方向旋转轴交叉在这个国家的计划期内(实际上,跨辊通过彼此的间隔,除了与在前面观看外)。在辊布局图1中, 3对矫直辊Ra1、Ra2和Ra3,且Ra3被分别设置在内测,中心和外侧,每对辊体彼此相反布置,辅助辊Rc被提供给矫直辊的外侧。通常辊矫直机辊具有这种布局图。 1被称为( 2-2-2-1 )型矫直机。反对辊间隙和交叉角可以在矫直辊Ra1和Ra2中分别进行调整。第一对矫直辊Ra1和Ra2在垂直方向的高度位置和第二对矫直辊Rb1和Rb2在垂直方向的高度位置相临近,彼此也能够被调整。在弯曲校正中,每个矫直辊R的旋转轴的跨越角用管予以纠正1,即滚转角调整这种联系面临的管子的接触面以纠正1适合的轮廓矫直辊,相反矫直辊Ra1和Rb1之间的辊间隙设置和被纠正1的管子外部直径相比微小,并且传授给拉直弯曲和纠正调整压榨量的补偿是通过第二对矫直辊Ra1和Rb2对第一对相比完成的。科学的高刚性和耐磨损性能对于矫直辊来说是必须的,矫直辊是由工具钢或陶瓷制成的,并且矫直辊的接触面应该是被修正的,为了使钢管的外直径保持在一个预定的范围内被矫直。在热处理之后,传热辊的弯曲和椭圆度在辊式矫直机的矫直过程中被修正,例如剪切和在装运前通过在钢管内部涡流探伤测试之后视察图二是一个通过表格显示在钢管内表面涡流探伤测后结果的一个例子。就像在图二中显示的那样。信号S源于在测试标准中的缺陷界定标准,在图表中显示信号N有一个预先确定的期限P。信号N被称作基干扰。它是由热传到管在轴线方向上的微小空间波动产生的。这是很有必要的对于发现的缺点所引起的信号N,并且可以迅速判断是否信号表明该漏洞,从而提高检测效率。在下文中,来自于缺陷标准中的信号s与基干扰N的比率被定义为“S/N”。例如,在这种情况下自动判断功能是基于钢管内部涡流测试图表中的信号。干扰越大,也就是说小S/N比隐藏的信号是一个小缺陷背后的基干扰,这使得区分小缺陷信号和基干扰更难。因此,一个观察员仔细的观察在涡流测试中自动生成的结果。当一个可疑信号测试生成再次以较低的速度来区分小缺陷和基干扰,从而降低了检测效率。如上所述,基干扰是由热传到管在轴线方向上的微笑空间波动产生的。因此,为了降低基干扰,有必要制止三维波动,如弯曲和椭圆度在沿着热传导管轴方向上。这就是说要提高沿热传导管轴线方向上的尺寸精度。通常情况下,在用辊式矫直机矫直钢管的过程中,像图3到图5中所显示的那样。矫直辊的放置角度、压下量和补偿量等设置参数都是为了去减少空间波动例如在热传导管轴线方向上的弯曲和椭圆度。图三是一种观点用来解释辊式矫直机辊角的设定条件和与被矫正的钢管相应偏移距离之间的关系。如果该矫直管的外径d被修正1,并且代表一个角度(下文中被定义为辊角),它的形成是通过辊的中心轴的,被修正1,矫直辊R的旋转轴,沿管的一个移动距离(下文中被定义为同步孔距)M被修正为1,矫直辊R每转动一圈被定义为下面的等式(2)M=dtan。图四是一种观点用来解释辊矫直机在设定条件下的压下量,就像图四中所指的那样,钢管被修正为1b,当被压下的时候,形成椭圆形。一个压下量被表示成被修正为1a的反变形管和一个
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