鋼管怎麼劃圓

焊管表面劃傷產生的原因

Causes of scratch on welded pipe surface

使用軋輥成型的焊管要求將帶材橫向彎曲成圓，這是透過一系列不同孔型的軋輥使帶材變形來實現的，每對軋輥以一定轉速轉動，但軋輥表面的線速度因旋轉半徑不同而不同，線速度的差異使帶材與成型輥之間產生的滑動摩擦是焊管表面劃傷產生的根本原因。

The welded pipe formed by roller requires the strip to be bent horizontally into a circle， which is realized by a series of rollers with different passes to deform the strip。 Each pair of rollers rotates at a certain speed， but the linear speed of the roller surface varies with the rotation radius。 The sliding friction between the strip and the forming roller caused by the difference of linear speed is the fundamental reason for the scratch on the welded pipe surface。

大多數焊管機組採用水平成型法，對於這種機組，粗軋輥、導向環輥和定徑輥的主動輥底徑被認為是驅動直徑，這些軋輥底直徑的線速度基本上等於帶材的輸送速度，由於旋轉半徑不同，每個軋輥的輥緣使帶材與輥面之間的相對滑動摩擦大，導致表面劃傷。

Most welded pipe mills adopt horizontal forming method。 For this kind of mill， the driving roll bottom diameter of roughing roll， guide ring roll and sizing roll is considered as driving diameter。 The linear speed of these roll bottom diameter is basically equal to the conveying speed of strip。 Due to different rotation radius， the relative sliding friction between strip and roll surface is large at the roll edge of each roll， which leads to surface scratch。

摩擦力影響表面質量，摩擦力大會產生劃痕，摩擦力增大時，帶材上的正壓增大，帶材的變形增大，導致軋輥對帶材產生應變，產生表面劃痕。

Friction affects the surface quality， friction will produce scratches。 With the increase of friction， the positive pressure on the strip will increase and the deformation of the strip will increase， resulting in the strain of the roll on the strip and surface scratches。

合理的軋輥設計和加工

Reasonable roll design and processing

1。使用遊動翼緣輥

1。Use floating flange roller

為了減少帶材和軋輥面之間的相對滑動，主動輥使用遊動翼緣輥，一種典型的移動翼緣輥結構，其設計是遊動翼緣由軸承支撐，其轉速取決於帶材的輸送速度，不同於軋輥的速度，使用這種軋輥可以減少帶材與軋輥表面之間的相對滑動，從而減少甚至去除焊管表面的劃痕。

In order to reduce the relative sliding between the strip and the roll surface， the active roll uses the moving flange roll， a typical moving flange roll structure。 Its design is that the moving flange is supported by the bearing， and its speed depends on the conveying speed of the strip， which is different from the speed of the roll。 Using this kind of roll can reduce the relative sliding between the strip and the roll surface， so as to reduce or even remove the welded pipe surface It‘s a scratch。

2。四輥成型

2。Four roll forming

除了使用遊動翼緣輥成型，一些焊管機組使用四輥成型，四輥成型用於導向環輥和定徑輥，這時水平輥使用主動輥，立輥使用被動輥，立輥的轉速取決於帶材的遞送速度，這有利於減少帶材與立輥表面之間的相對滑動和滑動摩擦。

In addition to the use of floating flange roll forming， some welded pipe units use four roll forming。 Four roll forming is used for guide ring roll and sizing roll。 At this time， the horizontal roll uses active roll and the vertical roll uses passive roll。 The rotation speed of vertical roll depends on the delivery speed of strip， which is conducive to reducing the relative sliding and sliding friction between strip and vertical roll surface。

3。逸出角和餘隙

3。Escape angle and clearance

除了改變軋輥設計，對軋輥修正也可以減少焊管表面劃傷，常見的方法是在軋輥輥緣加工一個適量的逸出角或餘隙，這種間隙可以降低帶材在該位置的表面壓力，從而減少表面劃痕，加工間隙不但取決於焊管材料、管徑和單位特性，還取決於成型過程中各輥的輥型，逸出角度或間隙要求帶材能夠從輥表面逸出，對於不同用途的焊管，如高強度低合金鋼結構管，表面質量沒有需要整修的焊管高，為了降低生產成本，不需要花太大力氣來消除表面劃痕（如果軋輥劃傷在標準要求範圍以內）。

In addition to changing the roll design， the roll modification can also reduce the surface scratch of welded pipe。 The common method is to process an appropriate escape angle or clearance at the roll edge， which can reduce the surface pressure of the strip at this position， so as to reduce the surface scratch。 The processing clearance depends not only on the material， pipe diameter and unit characteristics of welded pipe， but also on the roll shape of each roll in the forming process The escape angle or gap requires that the strip can escape from the roll surface。 For welded pipes with different uses， such as high strength low alloy steel structural pipes， the surface quality is not as high as that of welded pipes that need to be repaired。 In order to reduce the production cost， it is not necessary to spend too much effort to eliminate the surface scratch （if the scratch of the roll is within the standard requirements）。

表面處理工藝可以在軋輥表面形成一層堅硬的耐磨層，耐磨層包括物理塗層、化學塗層和熱擴散層，塗層材料一般含有氮化鈦和碳化鈦，塗層可以增加軋輥的耐磨性和降低摩擦係數，但軋輥在這一領域的應用受到軋輥變形和修復難度的限制，當鋼管表面粗糙度嚴重時，可以考慮軋輥的表面處理。

The surface treatment process can form a hard wear-resistant layer on the roll surface。 The wear-resistant layer includes physical coating， chemical coating and thermal diffusion layer。 The coating material generally contains titanium nitride and titanium carbide。 The coating can increase the wear resistance of the roll and reduce the friction coefficient。 However， the application of the roll in this field is limited by the deformation of the roll and the difficulty of repair The surface treatment of the roll can be considered in the design。

焊管表面的劃痕可能是由表面摩擦力大或軋輥表面線速度差等簡單原因造成的，但是分析和消除表面劃痕比較麻煩，整個成型過程包括軋輥的設計、軋輥的安裝調整以及潤滑系統的合理使用都要進行分析，才能生產出高質量的產品。

The scratch on the surface of welded pipe may be caused by simple reasons such as large surface friction or linear velocity difference on the surface of roll， but it is troublesome to analyze and eliminate the scratch。 The whole forming process， including the design of roll， the installation and adjustment of roll and the reasonable use of lubrication system， needs to be analyzed in order to produce high-quality products。

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