DE3841795A1 - Method for the continuous production of longitudinally seam-welded tubes and an apparatus for carrying out the method - Google Patents

Abstract

In a method and an apparatus for the continuous production of longitudinally seam-welded tubes, metal strip being fed continuously to a roller cage and there formed into a tube, edge waves are avoided by virtue of the fact that the lower edge of the tube (16) to be formed is, in a first deformation region (18), guided in the roller cage (6) along a contour having a concave curvature, the strip edges of the tube to be formed lying on the inside, in a second deformation region (19) is guided along a transitional curve having a reversal point and only a slight curvature, in a third deformation region (20) is guided along a contour having a convex curvature, the strip edges of the tube to be formed lying on the outside, and in a fourth deformation region (21) is guided along a straight contour and given its final shape. <IMAGE>

Description

The invention relates to a method for continuous Manufacture of longitudinally welded pipes, preferably steel tube,

• - The prepared tape in a Vorverformungsge equips transversely to increase the rigidity in the longitudinal direction is deformed to the longitudinal direction and in a bending frame the band edge area is provided with a curvature, which corresponds approximately to the final diameter of the pipe produced,
• - The tape in a roll basket from a forming hopper forming rolls is formed into a tube and the sub edge of the pipe to be formed on its way through the Roller basket is guided along a curved contour,
• - The exact pipe in a downstream knife stand form is formed and the two in a welding unit Band edges are connected with a longitudinal seam,

and a device for performing the method with one between a pre-forming stand and a caliber height-adjustable scaffold arranged at its ends articulated roller basket, which is made of an all shape giving role supporting frame is formed.

With this method and with such a device is made from an incoming steel strip by reshaping the  Band in the transverse direction and longitudinal welding of the band edges creates a longitudinally welded round tube. The continuous Liche forming of the band to the tube is essentially through a roller basket. This consists of a large number of rolls systematically arranged on a frame, which enclose the continuous band outside and inside and the Specify the desired contour. The location of these roles can be changed by suitable adjustment devices be that with a corresponding change in the bandwidth pipes can be produced with different diameters without that the roles themselves have to be exchanged.

The continuous forming of an endless band is done by affect the strip edge elongation during the forming process is pregnant. This extends into the area of plastic ver formation and leads to corrugations in the band edge area. From the DE-OS 17 52 560 it is already known, the curls in the Belt edges thanks to a height-adjustable one-piece roller to reduce basket and ver for different pipe dimensions set different necessary height curves.

Further investigations have shown that the pipe indentation four different, due to the deformation levels characterized areas of approximately the same length occur.

In a first area, as with the Würdi State of the art executed, too strong tensile stress and plastic deformations in the band edge area. This this is because, based on a unit of length, the length of the Band edges during the deformation is greater than the length of the Lower edges of the pipe to be formed.  

The pipe to be molded tries to be elastic and plastic To balance tensions and bends. At the state of the Technology is already trying this self-curvature in the first Area to follow, but only in rough approximation.

In a second, medium deformation range, the Tensile stresses in the band edge area first increasingly from to there is a build-up of compressive stress, which ultimately Cause for the appearance of curls in the following Deformation area are.

The compressive stresses and thus the corrugations can be reduced by using the already largely molded tube Possibility to admit the tension through self-curvature minimize. This third deformation area has so far no importance attached; at the ratio s / D 1/60, d. H. in the case of thin-walled pipes, the tape was nevertheless produced edges, due to large plastic deformations, undulations, that made the pipe unsaleable.

The invention aims to avoid these disadvantages and the task arises, a method and a device to carry out the method described above Kind of creating the continuous molding of a Tube from a band even with large wall ratios thickness to diameter, without formation of edge waves, he possible.

This object is achieved in that the Bottom edge of the pipe to be formed in a roll basket in one first deformation area along a concave curvature having contour is performed, the band edges of the forming tube lie inside, in a second deformation area along a transition with a turning point curve with only a small curvature and in one  third deformation area along a convex curvature having contour is performed, the band edges of the forming tube are outside and in a fourth deformation area along a straight contour and finished is formed.

A device of the type described above for through The procedure is characterized in that the Roller basket made of several one behind the other, each forming a roller basket section, all shaping rollers supporting frame is composed, and that each rolling basket section, at least at the adjacent end regions, Lifting devices are assigned.

To rule out transfers, it is advisable that neighboring Beard end areas of the roller basket sections with one each common lifting device cooperate. To the character Ristic deformation sections in the section To follow the outline of the roller basket, it is advantageous to line up at least four roller basket sections.

The invention is explained in more detail with reference to the drawings and shows in Fig. 1 the overall arrangement of a plant for the manufacture of longitudinally welded pipes and in Fig. 2 the curved contour generated by the lower edge of the pipe to be formed and the banding achieved at characteristic points.

The tape ( 1 ), which runs through the device in the tape running direction ( 2 ), is unwound from a coil in a Abhaspelein direction, not shown, and fed to a tape welding device. Here, the ends of strips that have been unwound one after the other are welded to form an endless strip. At closing, the tape is fed to a tape storage unit, also not shown, and through a tape insertion unit ( 3 ) a pre-deformation stand ( 4 ), in which the first deformation of the tape takes place, with the required stiffness in the longitudinal direction by shaping transverse to the tape running direction ( 2 ) is achieved. In this scaffold, the belt is given a circular arc shape with a large radius. In the subordinate height-adjustable bending frame ( 5 ), the strip edges are deformed, whereby a radius is sought which corresponds at least to the largest pipe radius generated on the system. A radius is sought which speaks to the radius of the end product.

The strip then passes through the roller cage ( 6 ), in which the actual molding into the tube takes place. The roller basket according to the invention ( 6 ) consists of four roller basket sections ( 6 a , 6 b , 6 c , 6 d ), each roller basket section having a frame ( 7 a , 7 b , 7 c , 7 d ) in which all the contours the rollers ( 8 ) forming the tube to be molded are adjustably attached. The basic structure of the roller cage and the theoretical basics of the molding are already described in US Pat. No. 3,323,341. Adjacent frame parts ( 9 a , 9 b , 9 c ) of the roller cage sections ( 6 a , 6 b , 6 c ) are connected to one another by joints ( 10 ) and are supported by lifting elements ( 11 ). The frame parts ( 9 a , 9 c ) are hinged to the rigid foundation frame ( 12 , 13 ). With the lifting elements ( 11 ), it is possible to adjust the roller basket sections ( 6 a , 6 b , 6 c ) in their height.

The contour ( 14 ) of the lower edge of the pipe to be formed deviates from the horizontal ( 15 ) by the amount H , which depends on the pipe dimension. When choosing a favorable contour, the stresses and thus the strip edge elongation are minimized. When leaving the roller basket, the tube has almost reached its final dimension.

Downstream are knife stands ( 17 ), in which the exact shape required for the welding process is generated. The following longitudinal welding device, in which the strip edges are welded, is no longer shown.

It is possible and advantageous to combine the roller basket section ( 6 d ) and the knife stands ( 17 ). Following the longitudinal welding device, not shown calibration scaffolds are to be provided.

In FIG. 2 the adjustable contour of the lower edge is shown to the forming tube:

The horizontal line ( 15 ) denotes the line of passage of the belt to which all the scaffolds are aligned. The contour ( 14 ) already deviates from the horizontal ( 15 ) in the pre-deformation stand ( 4 ). Together with the bending scaffold ( 5 ), the inclination ( 23 ) of the contour is determined at its starting point, which depends on the wall thickness and diameter of the pipe to be produced. This is followed by the four deformation areas ( 18 , 19 , 20 , 21 ). A concave curvature is set in the first deformation region ( 18 ) following the self-deformation efforts of the formed strip, the strip edges ( 16 ) of the tube to be formed being on the inside. In the third ( 20 ) deformation area ( 20 ), the self-curvature of the pipe to be formed follows a convex curvature, in which the band edges ( 16 ) of the pipe to be formed come to rest on the outside. At the place ( 22 ) where the curvature of the contour again tangentially transitions into the horizontal ( 15 ), the outlet section ( 21 ) follows.

Furthermore, the degree of deformation at the transitions between the deformation regions is shown in FIG. 2.

Claims (5)

1. Process for the continuous production of longitudinally welded pipes, preferably steel pipes,

• - The prepared tape in a Vorverformungsge scaffold ( 4 ) is deformed to increase the rigidity in the longitudinal direction transversely to the longitudinal direction and in a bending scaffold ( 5 ) the band edge region is seen with a curvature that corresponds approximately to the final diameter of the tube produced,
• - The band in a roller cage ( 6 ) is formed into a tube by a funnel-forming rollers and the lower edge of the tube ( 16 ) to be formed is guided on its way through the roller basket along a curved contour ( 14 ),
• - The exact tube shape is formed in a downstream knife frame ( 17 ) and the two strip edges are connected in a welding unit with a longitudinal seam,

characterized in that the lower edge of the tube ( 16 ) to be formed in the roller cage ( 6 )

• - is guided in a first deformation region ( 18 ) along a contour ( 14 ) having a concave curvature, the band edges of the tube to be formed lying on the inside,
• - Is guided in a second deformation region ( 19 ) along a transition curve having a turning point with only a slight curvature and
• - In a third deformation region ( 20 ) is guided along a contour having a convex curvature, the strip edges of the pipe to be formed being on the outside
• - In a fourth deformation region ( 21 ) is guided along a straight contour and finished.

2. Apparatus for carrying out the method according to claim 1 with a height-adjustable, articulated at its ends supported roller cage ( 6 ) arranged between a pre-forming stand ( 4 ) and a knife stand ( 17 ), the frame ( 7 ) carrying all the shaping rolls ( 8 ) a , 7 b , 7 c , 7 d) is formed, characterized in that the roller cage ( 6 ) from several successively arranged, each a roller cage section ( 6 a , 6 b , 6 c , 6 d ) forming and all shaping Rollers ( 8 ) supporting frame ( 7 a , 7 b , 7 c , 7 d ) is put together and that at least some of these roller basket sections ( 6 a , 6 b , 6 c , 6 d ) at adjacent end regions ( 9 a , 9 b , 9 c) of these roller cage sections lifting elements ( 11 ) are assigned. 3. Apparatus according to claim 2, characterized in that these adjacent Endbe areas ( 9 a , 9 b , 9 c ) of the roller cage sections ( 6 a , 6 b , 6 c ) cooperate with a common lifting device ( 11 ). 4. Apparatus according to claim 2 or 3, characterized in that at least four roller cage sections ( 6 a , 6 b , 6 c , 6 c ') are strung together.