Abstract:
The invention relates to a method and device for forming a one-piece flange ( 10, 18 ) or rim on the end of a steel or sheet-metal ( 12 ) pipe. The pipe is placed in a flat position on all sides on the inner surface thereof close to the end thereof and is clamped. One part of the pipe ( 10 ) protrudes above the clamped section of the tube ( 12 ). The protruding part of the pipe is bent by applying surface pressure against a peripheral section on the inner surface thereof, until a desired outward flectional angle is obtained. The desired flectional angle on all parts of the pipe ( 10, 18 ) or a part or section ( 10 ) thereof is gradually achieved by rotating the pipe ( 12 ) relative to the peripheral section wherein the flexing occurs.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The invention concerns a process according to the precharacterizing portion of claim  1 .  
           [0003]    The invention is more specifically concerned with relatively thin-walled pipes, and in particular those with a diameter in the range of approximately 100 to 3000 mm and a wall thicknesses of 1.5 to 6.0 mm. Such pipes are primarily employed for air lines or conduits, ventilation ducts, device housings and the like in ventilation, air conditioning and vacuum engineering, but are however also employed in process engineering.  
           [0004]    2. Description of the Related Art  
           [0005]    There are various types of connections for tightly and securely connecting individual pipe segments with each other. These connections have different influences upon the economics and technical characteristics of the pipe system. Until now angled, flat or other profiled flanges have been employed which are manufactured separately and seated upon the pipe end, although advantages of flanges formed directly, that is, unitarily, as one piece on the pipe ends is readily apparent and thus a need for such formed-on flanges and rims exist. The reason that there is a need is due to the lack of an economically justifiable process for forming desirable flange shapes on the ends of, above all, mass-produced pipes. Until now only radially projecting ring rims with relatively low stability or radially projecting flanges, which are provided with holes for screwing, are formed onto the pipes. The latter is employed primarily for ventilator housings. The simple ring can be produced with two rollers using a beading and rim machine. The latter flat flanges with holes are produced in a press process. For this, the pipe body is caused to rotate with high rotational speed, which is possible only with very short pipe bodies such as axial ventilator housings. The pipe ends are inserted into a die or negative pattern of the flat flange to be formed. With a pressure lever, on the end of which a roller revolves, pressure is applied against the rapidly rotating pipe end until the material is caused to flow and lie against the negative pattern. The “pressure” process is somewhat similar to the deforming of clay using a potter&#39;s wheel. It is also used for the forming of ring flanges on short pipe rings, which are then subsequently seated upon a pipe end and secured thereto. This latter process is described, for example, in DE 196 32857 A1.  
           [0006]    This known process is poorly suited to the formation of flanges directly onto pipe ends, since it is almost impossible and besides this dangerous to spin larger pipes with the necessary speed of rotation. Further, the energy required for many types of forming in the case of a wide variety of different pipes is much too high for an economical process. Above all, however, the manufacture of complex flange shapes, such as for example conical flanges or the like, is not possible due to the occurrence therein of cutbacks or inclusions, since in this case the mold or pattern cannot be removed again from the finished flange.  
           [0007]    For the manufacture of boxes, frames, profiles, or channels with straight edges the so-called beveling process or pivot bend process is known. For this, a planar sheet metal plate is clamped or tensioned between a fixed lower member and a moveable upper member, and bent using a pivotable bending member. The great advantage therein is that during pivot bending an entire sheet metal segment can be raised, or as the case may, be curved, without any stretching. The sheet metal materials need flow only in the area of the edge being formed. All the remaining material remains completely unchanged. Thus, the edge profile without stretching and without any particular effort is precisely straight and free of tension. In contrast thereto, in the case of the above-discussed “pressing” the entire material is bent through and thereby unavoidable tensions are introduced. Accordingly, the energy required for pivot bending is substantially less.  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention is concerned with providing a process and a device for carrying out this process, in which the one-piece forming of even complicated flanges and rims not only on short pipes, but rather in particular also on long pipe segments, is economically possible.  
           [0009]    This task is inventively solved with respect to the process by the characterizing features of claim  1  and with respect to the device by the characteristics of claim  5 .  
           [0010]    The dependent claims are directed primarily to advantageous embodiments of the invention.  
           [0011]    It is the basis of the inventive process to employ the advantages of the linear pivot process also in the case of bending at pipe ends. It is thus referred to herein as the circular-pivot-bending process.  
           [0012]    The linear pivot bending process can obviously not be applied to round pipes without modification, since herein the edges to be produced are not straight or linear, but rather curved, and these curved edges are to be produced with various radii with as few change-outs in work tools as possible. The invention accomplishes this by circumferential clamping of the pipe ends from inside, for example by means of a clamping disk. This clamping disk in has a slightly smaller diameter than the pipe inner diameter prior to clamping. Following insertion into the pipe it is widened, that is, the diameter is increased, until it lies with its outer circumference tightly against the inner surface of the pipe wall. The clamping disk or other device used for clamping can be connected with a strong drive axle for imparting the rotational movement. The tight clamping of the pipe end is thus also simultaneously used for the rotation of the pipe, wherein naturally only substantially lower rotational speeds are necessary than in the case of the pressure process. It is necessary that sufficient friction is created between the inner surface of the pipe and the clamping device, for example clamping disk, such that the pipe can be rotated against the resistance of the bending tools.  
           [0013]    It is on the other hand basically also possible to allow the pipe and the therewith rigidly connected parts of the device to remain stationary and to rotate the bending tools and the therewith rigidly connected parts about the pipe axis.  
           [0014]    The subsequent bending out of a part of the projecting pipe piece to form a rim or flange about the circumference of the pipe piece being modified occurs continuously during the rotation of the pipe. For this, a pivotable bending jaw is preferably employed, which in its rest position lies against the inner side of the pipe end. Its axial breadth should be at least somewhat larger than the segment of the pipe end to be bent. Thereby it is ensured that the segment to be bent is raised as a whole, and not changed in its straight shape. Preferably the contact surface of the bending jaw on the pipe end should have the same radius as the inside of the pipe, such that the segment of the pipe end to be bent has a large surface area contact surface. In principle however a circular shape of the contact surface of the bending jaw, with a somewhat smaller radius than the inside of the pipe, is also possible. Since the pivotable bending jaws can bend respectively only one partial segment of the pipe circumference, the pipe must be caused to rotate in an even, slow rotation. When the pipe rotates, the bending jaws are slowly pivoted unto the position of the desired bending angle. This inventive process can thus be properly referred to as a circular-pivot-bending process.  
           [0015]    In a preferred embodiment of the invention it is possible to additionally apply pressure upon the bending point of the pipe from the outer side of the pipe, preferably using a shaping roller or the like, wherein a tip of the shaping roller cross-section terminates at that location, where the pipe end is to be bent over. Thereby the shape of the bent edge (sharp or round) can be predetermined quite precisely. The remainder of the cross-sectional shape of the shaping roller is determined by the maximal angle of bending of the tip-stretch profile. Since substantial forces are applied upon the shaping roller during the bending process, a precondition for obtaining a clean bent-edge is thus a rigid mounting and positioning of the shaping roller. Preferably, the shaping roller and its mounting are connected to a fixed unit with the likewise fixed and non-rotating bending jaws and the drive means therefore, whereby the stability of the device is substantially increased.  
           [0016]    In the case that high precision in the form of the shaped flange or rim is not required, it is possible in the case of relatively small pipe thicknesses, to bend these without using a shaping roller. In this case the curvature of the pipe wall there suffices to provides sufficient resistance to bending. Sharp bent edges are therein however not possible, and with the increase in the wall thickness the radius of the bent edge continuously increases. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0017]    The sequence of steps of the inventive process, as well as preferred embodiments of the inventive device, will now be described in greater detail with reference to the figures. There is shown  
         [0018]    FIGS.  1 - 12  the process steps of the inventive process on the basis inventive process, showing the steps for forming a conical flange on the end of a pipe, wherein the device parts shown schematically in side view serve only as an example of the results to be achieved by the process and wherein other or differently shaped designs can be achieved,  
         [0019]    [0019]FIG. 13 a schematic side view of a first embodiment of the device for carrying out the inventive process in a first processing position,  
         [0020]    [0020]FIG. 14 a side view of the device according to FIG. 13 in a second processing position,  
         [0021]    [0021]FIG. 15 a side view of the device according to FIG. 13 in a third processing position,  
         [0022]    [0022]FIG. 16 a schematic partial section along the line XVI-XVI in FIG. 13,  
         [0023]    [0023]FIG. 17 a schematic frontal view of the clamping disk employed in accordance with the process shown in FIGS. 13 through 18,  
         [0024]    [0024]FIG. 18 a schematic side view of the parts shown in FIG. 17,  
         [0025]    [0025]FIG. 19 a schematic side view of a clamping disk, pipe and the parts of the drive device of the inventive device,  
         [0026]    [0026]FIG. 20 a sectional side view, shown in reduced scale compared to FIG. 19, of a part of the components shown in FIG. 19,  
         [0027]    [0027]FIGS. 21 and 22 an axial section or, as the case may be, schematic side view of a different embodiment of the clamping disk,  
         [0028]    [0028]FIGS. 23 and 24 schematic side views of pipe, clamping disk, bending jaws and shaping rollers with different locations or positions of the bending jaws,  
         [0029]    [0029]FIGS. 22 through 29 a schematic partial view of a clamping disk and a bending jaw in different bending positions with shaping rollers having differing cross-sections or, as the case may be, without shaping rollers,  
         [0030]    [0030]FIGS. 30 and 31 partial broken away schematic oblique views of parts of an inventive device with pipe, clamping disk, shaping rollers and bending jaws in the resting or, as the case may be, bending position of the bending jaws,  
         [0031]    [0031]FIG. 32 a partial oblique view corresponding to FIG. 30 but without pipe and shaping roller,  
         [0032]    [0032]FIGS. 33 through 35 a partial representation according to FIG. 32 with respectively three differing embodiments of the bending jaws, and  
         [0033]    [0033]FIG. 36 a schematic partial view of an embodiment with two inventive devices working simultaneously on both ends of a pipe. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0034]    [0034]FIGS. 1 through 12 show respectively in schematic partial representation the process steps of the inventive process on one pipe end. FIG. 1 shows, for simplification, a largely broken away partial sectional view through an unprocessed pipe  12  with circular cross-section and with end  10  facing towards the right in FIG. 1. FIG. 2 shows the condition of the pipe end  10  following the first processing step. The pipe end  10  has become a pipe piece to be further bent, which presently is bent outwards approximately 150° about a rounded-off bending edge  14  relative to the axial direction  16  of the pipe  12 . FIG. 3 shows the condition of the pipe  12  following a second circular pivot bending process, wherein the second pipe piece  18  bordering the first pipe piece  10  is bent outwards about a sharp angle or edge  20  about a right angle against the axial direction  16 . Thereby a conical flange is produced from the combination of the adjacent lying pipe pieces  10  and  12 , which are formed as a single piece on the pipe  12 .  
         [0035]    The subsequent FIGS. 4 through 12 illustrate schematically the manner of operation of a device for carrying out the inventive process. In all figures for comparison purposes the same parts are indicated with the same reference numbers.  
         [0036]    [0036]FIG. 4 shows a not-yet-clamped pipe  12  close to a clamping disk  22  in its not yet expanded resting state, which clamping disk  22  is rigidly connected to a drive shaft  24  which can be caused to rotate upon application of force. A first bending jaw  26  for bending the first pipe piece  10  about 150° into a position shown in FIG. 2 is represented in FIG. 4 in the starting position prior to the bending process, in partially broken away view. Therein it is to be noted that FIGS. 1 through 3, in comparison to FIGS. 4 through 12, are mirror images rotated 180° perpendicular to the pipe axis  28 . A second bending jaw  30  is rotated by 180° about the pipe axis  28  relative to the first bending jaw  26  shown likewise in its resting position prior to the bending process and shown partially broken away. The second bending jaw  30  serves for bending or introducing the angle into the second pipe piece  18  90° relative to the axial direction  16  of the position shown in FIG. 3. In FIG. 4 there are further shown a first shaping roller  32  and a second bending roller  34  likewise shown in their resting positions distanced from the pipe  12 . The first bending roller has a cross-section with rounded off tip  36 , of which the flanks  40  encompass an angle of 30°. Rotated by 180° about the pipe axis  28  is the second bend roller  34  provided removed from the pipe  12  into its resting position, of which the cross-section has a sharp angle  38  and of which the flanks  42  define a right angle. The shown condition of the device corresponds to the starting position of the process.  
         [0037]    [0037]FIG. 5 shows a subsequent process stage, in which the clamping disk  22  is introduced into the pipe  12  and is extended to is spread position according to arrows  44  against the inner surface of the pipe  12  from the inside. Together with the clamping disk  22 , the bending jaws  26  and  30  are introduced into the pipe end, but are however both still in the rest position with respect to their pivoting for bending open the pipe end. Likewise, both shaping rollers  32  and  34  are still located in their rest position just as in FIG. 4. At the same time the drive shaft  24  is brought to rotate in the direction of arrow  46 , so that the clamping disk  22  rotates together with the pipe  12 , while the bending jaws  26  and  30  as well as shaping rollers  32  and  34  do not rotate about pipe axis  28 . The friction resistance between the cylindrical outer surface  48  of the clamping disk and the inner surface of the pipe  12  is so large, due to the clamping of the clamping disk  22  in its working position according to FIG. 5, that the pipe  12  rotates along with the clamping disk even overcoming large resistance.  
         [0038]    The next process step of the shaping process is shown in FIG. 6, wherein the first shaping roller  32  is moved to its work position lying solidly against the outer side of the pipe  12 , having been moved along the displacement axis  52  according to arrow  50 .  
         [0039]    According to FIG. 7, next the first bending jaw  26  is bent about an angle of 150° out of its resting position (FIG. 6) into its work position (FIG. 7), said pivoting about an axis perpendicular to the plane of the drawing, whereby the first pipe piece  10  projecting beyond the clamping disk  22  is bent outwards about 150° about the first shaping roller  32 . Since drive shaft  24  and clamping disk  22  rotate simultaneously together with the clamped pipe  12  about the rotation axis  28 , after only a few rotations of these parts about the pipe axis  28  the pipe piece  10  is bent outwards about 150° from the pipe  12  about the rounded off edge  14 . By the rotatable mounting of the shaping roller  32  the frictional resistance of the pipe piece  10  occurring at the location of bending is substantially reduced.  
         [0040]    Subsequently, according to FIG. 8, the first shaping roller  32  is withdrawn along the displacement axis  52 , according to arrow  56 , out of the work position and back into its rest position away from the pipe  12 , and at the same time the first bending jaw  26  is pivoted back out of its work position according to arrow  58 , back into its rest position.  
         [0041]    In the next processing step according to FIG. 9 the second shaping roller is moved out of its resting position along the displacement axis  60  according to arrow  62  into the working position in solid contact against the outer side of the pipe  12 . All of these process steps occur while the drive shaft  24 , the clamping disk  22  and the pipe  12  rotate about the rotation axis  28  and the first bending jaw  26 , second bending jaw  30  as well as the two shaping rollers  32  and  34  remain at rest. Preferably the rotating parts and the non-rotating parts are assembled respectively to stable work units. Within the non-rotating work tool unit, naturally the moveability of the individual parts to and from the rest position and the drive positions must be made possible. On the other hand, it is naturally also possible to allow the drive shaft  24 , clamping disk  22  and pipe  12  comprising work unit to remain at rest and the other work unit comprised of the bending jaws and the shaping rollers to rotate about the pipe axis  28 .  
         [0042]    In the subsequent processing step according to FIG. 10 the second bending jaw  30  is pivoted according to arrow  64  out of its resting position into the working position, whereby the second pipe piece  18  projecting beyond the clamping disk  22  is bent outwards with a sharp bent angle  20  of 90° corresponding to the cross-section of the second shaping roller  34 . The complete bending of the second pipe piece  18  away from the pipe  12  towards outwards is accomplished after the rotating parts  24 ,  22  and  12  have carried out a few rotations about the pipe axis  28 .  
         [0043]    In the next processing step according to FIG. 11 the second shaping roller  34  is retracted from the pipe  12  along the displacement axis  60  according to arrow  66  and the second bending jaw  30  is pivoted back to its resting position along arrow  68 .  
         [0044]    Therewith the path is cleared for the return movement of all parts back to the starting position as shown in FIG. 4. Thus, at the end of the process, all parts in accordance with FIG. 12 are again located in the starting position according to FIG. 4, and the result of the inventive work process is the one-piece or unitary forming onto the end of the pipe  12  a flange comprising the pipe segments  10  and  18 .  
         [0045]    In FIGS. 13 through 16 a preferred embodiment of the device for carrying out the inventive process is shown schematically with the parts necessary for carrying out the invention. For improved overview, individual parts of the pieces are omitted, for example from the pipe  12 , the clamping disk  22 , the drive shaft  24  and the bending jaws  26 . It is further to be noted that in the illustrated device only one bending jaw  26  and shaping roller  32  is shown, which is suitable for a single bending process of a projecting pipe piece  10 . Obviously additional bending jaws and shaping rollers can be provided about the rotation axis  28  outside of the plane of the drawing. Their detailed description can however be omitted, since they function in the same manner as the parts shown in FIGS. 13 through 16. If an individual work unit comprised of bending jaw and shaping rollers is employed for each bent edge, then this has the advantage, that for the individual processing steps no work tools need be changed. It is necessary particularly in mass production that the processing units can come into engagement sequentially without interference.  
         [0046]    Each of the work units including one bending jaw  26  and one shaping roller  32  is respectively mounted on a mobile sled  70 , wherein multiple sleds can be mounted radially on a base plate  72 . In this manner the individual processing units can be easily adapted to the respective diameters of the pipe  12  to be processed. Each sled  70  can be moved along two parallel sled guides  71  according to the double arrow  74  via a threaded spindle  78  rotated by a rotational drive  76 .  
         [0047]    Two parallel side plates  80  (FIG. 16) are provided parallel and spaced apart from each other on the sled  70 , which are connected rigidly with each other in the manner of a frame by intermediate plates  82 . Between the two side plates  80  lying slidingly on the inner sides of the side plates  80  is a broad, somewhat circular or cylindrically shaped sector plate  84 , on which by means of screws  86  the bending jaws  26  are secured. The sector plate  84  forms, parallel to the side plates  80 , as can be seen in the cross-section of FIG. 13, an incomplete sector of a circle, of which the middle segment lying opposite the circular arc  88  is missing, since the center of the arc sector must remain free for the bending process of the pipe piece  10 . The angles  90  and  92  connecting to the outside of the circular arc  88  intersect outside the center point of the arc  88 . The bending jaws  26  are secured to the flat surface  92  of the sector plate  84  by screws  86 .  
         [0048]    It is to be noted that in FIG. 16, in comparison to FIGS. 13 through 15, only those parts necessary for the pivoting of the bending jaws  26  is shown.  
         [0049]    The guidance of the sector plate  84  during the necessary pivoting together with the bending jaws  26  occurs by guide rollers  94 , which run in arc-shaped guide grooves  96  in the side plates  80 . The guide rollers  94  project on both sides beyond the sides of the sector plate  84  and are respectively guided in a guide groove  96 . In the cylindrical circumference surface of the sector plate  84  corresponding to the arc  88  of the cross-section of the sector plate  84  there is provided gear teeth  98 , which are in engagement with a drive pinion  102  driven by rotational drive  100 . The sector plate  84  can therewith be pivoted out of the rest position of the bending jaws  26  according to FIGS. 13 and 14 into the work position of the bending jaws  26  corresponding to the position shown in FIG. 15. The pivot angle of the sector plate  84  can therein be freely widely selected and corresponds in the present case to the angle between the two flanks of the cross-section of the shaping roller  32 .  
         [0050]    From FIGS. 13 through 15 it can further be seen, that the shaping roller  32  is mounted rotatable about its central axis  105  in a fork shaped mounting block  104 , which for its part is moveable along double arrow  50 ,  56  out of its resting position according to FIG. 13 into the working position according to FIG. 14. For moving the mounting block  104  a threaded spindle  106  is provided driven by a drive motor  108 . It is important that the mounting block with shaping roller is secured in work position rigidly and capable of accepting high loads, according to FIGS. 14 and 15, with the working unit comprised of bending jaws, shaping rollers and associated parts.  
         [0051]    In the work condition according FIGS. 13 through 15 the clamping disk  22  is introduced into the pipe end by movement of the pipe  12 , while it is still in its resting state as described above. Subsequently, the clamping disk  22  is, as described in greater detail below, spread to its work position and now cylindrically clamps pipe  12  from the inside. From this there results a pipe piece  10  projecting beyond the cylindrical outer surface of the clamping disk  22 , which is to be subsequently further bent in accordance with the following bending process. Prior to the sliding on of the pipe  12  upon the clamping disk  22  the working unit comprised of bending jaws, shaping roller and associated parts and drive mechanism is so adjusted by means of movement of the sled  70  along the double arrow  78  with respect to the fixed base plate  72 , that it is adapted to the respective diameter of the pipe  12 . In FIGS. 13 through 15 such a working unit is shown. Additional work units can be mounted on the base plate  72  with mostly doubled sled guides  71  radiating outward from pipe axis  28 , so that they can be sequentially brought to bear upon the pipe  12 , in order to respectively deform one pipe piece to a part of a complicated flange. For each sled  70  there is therein provided one rotation drive  76  with threaded spindle  78 , a threaded follower  110  running upon the threaded spindle  78  and a mounting means  112  connecting this with the sled  70 , wherein the mount  112  can be displaced in a slit  114  of the base plate  72  running radially to the pipe axis  28 .  
         [0052]    In the following the design and manner of operation of a first embodiment of the clamping disk  22  is described in greater detail on the basis of FIGS. 17 through 20. Since the task of the clamping disk  22  is comprised therein, to prevent the deformation or change in form of the pipe inner side, it is important that a substantially complete contacting of the inner cylindrical circumference  116  of the pipe wall occurs. The shown preferred embodiment of the clamping disk is thus subdivided into multiple, in the illustrated embodiment six, sectors  118 , which in a subsequently in greater detail described manner can be spread from their inner rest position shown in the left half of FIGS. 17 and 18 into an outward work position in tensioned manner on the inside of the pipe  12  shown in the right half of FIGS. 17 and 18 via an axial drive, for example, a hydraulic cylinder  124  driven pull rod  122 . The number of the sectors is as large as desired. Therein a larger number of sectors has the advantage, that the gap  126  between the sectors  118 , which result following spreading of the clamping disk  22 , becomes smaller, and it covers the wall of the pipe  12 , even when the pipe is very thin walled, without changing the shape of the pipe. The sectors  118  are arc sectors and end, a distance from the pipe axis  28 , in a cylindrical-sectional inner surface  128 . The radial breadth of the sectors  118  can be freely selected, in order to conform the diameter of the clamp  22  to the respective diameters of the pipe  12 . The adaptation or conforming can occur by the simple exchange of sectors  118 . The inner surfaces  128  of sectors  118  lie on the cylindrical outer surfaces  130  of cylindrical shaped clamp jaws  132 . The sectors  118  are secured by radial screws  142  to the clamp jaws  132 . The clamp jaws  132  have a slanted inner face surface  134  with respect to the pipe axis  28 , which respectively lie against a face  136  of the widening end  120  of the pull rod  122 . In the illustrated embodiment the widening end  120  has a hexagonal cross-section, so that one side surface is provided for each of the six clamp jaws  132 .  
         [0053]    The main drive shaft  24  for rotating the clamping disk and the pipe  12  is centrally axially bored through, and the pull rod  122  extends through this bore. By actuation of the hydraulic cylinder  124  the pull rod  122  can be moved from the rest position  138  shown in the lower half of FIG. 19 to the wider or working position  140  shown in the upper half of FIG. 19. Thereby the sectors  118  are moved out of the rest position shown in the left half of FIGS. 17 and 18 with close spacing from the inner surface of the pipe  12  into the working position shown in the right half of FIGS. 17 and 18 lying with tension against the inner surface of the pipe  12 . This movement is caused by the appropriate displacement of the clamp jaws  132 .  
         [0054]    The drive shaft  24  extends through a cutout  144  of the base plate  72  of the overall device and is mounted rotatably in a manner known to those of ordinary skill and is caused to rotate by a drive motor  146  with hollow shaft drive  148 . The opposite end of the drive shaft  24  exhibits a mushroom shaped widening  150  with a planar end face  152 , upon which the planar slide surfaces  154  of the clamping jaws  132  lie radially slideable. The slide surfaces  156  of the clamp jaws lying opposite to the slide surface  154  lie slidingly against the inner surface of a counter slide  158 , which is secured by screws  160  to the mushroom shaped widening  150 . The screws  160  pass through the mentioned holes  169  in the clamp jaws  132 , which allow the necessary slight radial displacement of the clamp jaws  132 .  
         [0055]    The screws  160  are surrounded by distance casing  162 , which together with the holes  169  of the clamp jaws  132  allows a linear radial guidance of the clamp jaws  132 .  
         [0056]    The hydraulic cylinder  124  for operating the pull rod  122  is supported axially on the drive means  148  for the hollow drive shaft. The already sufficiently large force of the hydraulic cylinder  124  is again amplified as desired by the slanting of the widening end  120  of the pull rod  122  relative to the pipe axis  28 . In this manner the necessary amount of clamping force is produced, which produces a sufficient frictional connection of the clamping disk  22  to the pipe wall, in order to rotate the pipe against the resistance of the bending tools (bending jaws  26  and shaping roller  32 ). Of course, the slanting of the widening end  120  can be reversed, that is, be reduced towards the right in FIG. 19, in the case that an oppositely operated pressure rod is employed.  
         [0057]    The return of the clamp jaws  132  during de-tensioning of the clamping disk  122  back into its rest position can occur in simple manner by not shown springs, which are incorporated in the individual clamp jaws, or by an endless pull-spring running about the outer circumference of the clamp jaws, likewise not shown, which would be incorporated in a likewise not shown groove.  
         [0058]    Alternatively, the drive shaft  24  can, in the embodiment shown in FIG. 20, be mounted via a ball rotation ring  164 , of which the outer side (or even the inner side) is provided with gear teeth  166 . The drive motor  146  in this case is seated beside the ball rotation ring  164 . The pinion  168  of its drive shaft  170  engages in the teeth of the ball rotation ring  164  and brings about a driving of the drive shaft  24 . Naturally, other mounting types well know to those of ordinary skill can be considered.  
         [0059]    An alternative advantageous embodiment of the clamping disk referred to in general with 22 and the drive therefore is shown in FIGS. 21 and 22. In this embodiment the clamping disk  22  exhibits clamp ring  174  with cylindrical circumference surface  116  and conical inner surface  176 , which clamp ring  174  is divided by a circumferentially running slanted slit  172 . Against the conical inner surface  176  lies the outer surface  178  of the clamp plate  180  having the same conical shape, which by means of bolts  182  and nuts  184  is secured to the widened end  186  of the pull rod  122 . By displacement of the pull rod  122  in the sense of the double arrow  188  between the detensioned resting position shown in the upper half of FIGS. 21 and 22 and the tensioned work position shown in the lower halves of FIGS. 21 and 22 the clamp ring  174  allows itself to be tensioned or as the case may be detensioned with development any desired amount of force. A slit of the clamping ring  174  running in the axial direction parallel to the pipe axis  128  would also be possible. The slanted arrangement of the slit  172  however prevents, that the gap opening during clamping causes a gap in the widening of the pipe wall causing a deformation or wrinkle in this location. The return of the clamp  174  during detensioning occurs in this case by the spring effect of the clamp ring itself. As necessary the spring effect can be amplified by a not shown circumscribing endless pull spring in a groove of the clamp ring  174 .  
         [0060]    It is apparent that the sheet metal thickness of the pipe  12 , the desired flange shape, or a material change of the clamping disk  22  has no influence on the desired flange shape. The pipe end  10 ,  18  is respectively slid so far over the clamping disk  22 , until sufficient material becomes available for the forming of the designed flange.  
         [0061]    In the subsequent FIGS. 23 through 35 advantageous embodiments of bending jaws  26  and shaping rollers  32  are shown together with a segment of the pipe  12  to be deformed as well as a part of the spread clamping disk  22 . FIGS. 23 and 24 show a first embodiment of these parts, wherein in the above described manner the shaping rollers  32  are moved into a working position pressed against the outer side of the pipe  12 . The bending jaw  26  pivotable in the above described manner lies in its rest position against the inner side of the pipe piece  10  to be bent and extending beyond the clamping disk  22 , whereupon the pipe wall is clamped and held between the clamping disk  22  and shaping roller  32 . The tip  36  of the cross-section of the shaping roller  32  ends at the point, where the projecting pipe piece  10  is to be bent. By the shape of the shaping roller  32  the shape of the bending edge on the pipe end can be determined.  
         [0062]    The pivotable bending jaw  26  lies on its resting position according to FIG. 23 against the inner side of the pipe piece  10 . Its axial breadth is at least somewhat larger than the axial length of the pipe piece  10  to be bent. Thereby it is ensured that the pipe piece to be bent is lifted as a whole and thus is not changed in its linear shape. Likewise the cylindrical contact surface  190  of the bending jaw  26  should have the same radius at the pipe end as the pipe inner side, so that the pipe piece  10  to be bent has a large surface area contact surface.  
         [0063]    Since the pivotable bending jaw  26  can only bend a partial area of the pipe circumference, the pipe  12  must be caused to rotate in an even, slow rotation. If the pipe  12  rotates, then the bending jaw  26  is pivoted slowly to the desired bending angle (FIG. 24). The bending jaw  26  remains in this work position until the end of its last complete rotation of the pipe  12  about the pipe axis  28 , whereupon the bending out of the pipe piece  10  is ended.  
         [0064]    So that the pipe  12  following the forming of the flange or rim can be removed from the clamping disk  22 , the shaping roller  32  with its mounting lock  104  must be withdrawn to a rest position sufficiently far from the pipe. For a further circular bending process now a further processing unit, which is adjusted to a further bending angle, is brought to action in the above-described manner.  
         [0065]    For the easier introduction of the clamping disk  22  into the pipe end  10  the introduction side of its cylindrical outer surface  48  can exhibit a conical narrowing  192 .  
         [0066]    In FIGS. 25 through 28 various embodiments of the shaping roller  32  or, as the case may be,  34  are shown with narrow tip  36  or, as the case may be, right-angled tip  38 . The tip  36  serves for bending of the pipe piece  10  about 1500, while the tip  38  serves for bending the pipe piece  10  about 90°.  
         [0067]    In FIG. 29 there is schematically shown how, absent precise demands on the forming precision of the formed flange or rim, one can entirely bend without shaping rollers and only with clamping disk  22  and bending jaws  26 .  
         [0068]    [0068]FIGS. 30 and 31 show an embodiment of the bending jaw  26  with almost half cylindrical contact surface  190  in resting position (FIG. 30) and work position (FIG. 31).  
         [0069]    [0069]FIG. 32 shows in somewhat enlarged scale a partial representation of a somewhat differently shaped bending jaw  26  with flatter cylindrical contact surface  190 , which is secured by screws  86  to a only partially shown, pivotable sector plate  84 . The contact surface  190  lies with all its frictional force against the inner wall of the not shown pipe. In the following figures the individual advantageous embodiments of a similar bending jaw  26  as in FIG. 32, however with less friction between contact surface  190  and pipe inner wall is shown. It is actually ideal, when the working radius of the contact surface  190  of the bending jaw  26  corresponds to the pipe inner diameter. Without serious disadvantage the radius of the contact surface  190  can however be smaller than the pipe inner radius. Thereby it is possible, with the same bending jaws to change through multiple pipe diameters. In the main friction location in the center of the contact surface  190  there can, for a substantial reduction of friction and drive, in the body of the bending jaw  26  a roller mounted support roller  194  be introduced, of which the rotation axis  196  runs parallel to the contact surface  190  and of which the circumference surface  198  projects slightly beyond the contact surface  190 . The pipe piece  10  to be bent then lies in this area free of friction on the circumference surface  198  of the support roller  194 .  
         [0070]    The bending jaws  26  can be further improved by introduction of a whole series or chain of support rollers  194  in the contact surface  190  in the same manner as the support roller  194  according to FIG. 34. In the shown embodiment according to FIG. 34 five such support rollers  194  are provided in a chain. The remaining part of the contact surface  190  between the support rollers  194  prevents a drooping of the wall of the pipe  12  between the support rollers  194  which would result in wave formation and stretching or distortion.  
         [0071]    A minimal friction between bending jaws  26  and the inner wall of the pipe  12  is achieved when the bending jaws  26  according to FIG. 35 are fully cylindrical with cylindrical contact surfaces  190 , wherein the entire cylindrical bending jaws  26  are mounted rotatable about a drive shaft  200  on the sector plate  84 . Although in this manner the least amount of friction is produced, since however in most cases insufficient space is available for a large diameter of the cylindrical shaped bending jaws  26 , one must accept the disadvantages in the deformation formation as well as stretching of the pipe wall. These disadvantages are lesser in the case of greater pipe wall thicknesses so that in the case of bending thicknesses above 1.5 mm such a “bending roller” can be employed in the place of bending jaw  26 .  
         [0072]    The total inventive device for carrying out of the inventive circular pivot bending process can selectively be carried out both in the horizontal as well as in the vertical pipe axis  28 , wherein there is preferred on the one hand straight pipes and on the other hand shorter pipe-shaped pieces to be shaped.  
         [0073]    For a rational preparation of straight pipes with flanges  10 ,  18  formed on both ends using the inventive circular bending process, devices  204  of the described type are seated upon a common rail system designated overall with 202 mounted to be slidable according to the double arrow  206 , so that the clamping disk  22  and bending jaws  26  indicated schematically lie on opposite ends. Each device  204  can be moved using an independent driven threaded spindle  208  in the rail system  202 .  
         [0074]    For introduction of the pipe  12  the devices  204  are moved apart from each other, until the pipe length of the pipe  12  fits between the clamping disk  22 . After that both devices  204  are moved towards each other, the clamping disks  22  are introduced into the pipe ends until reaching an abutment, which is set to the processing length of the pipe. Both clamping disks  22  are clamped in the processing position, and processing occurs subsequently simultaneously on both sides. For removal of the pipe  12  the devices  204  must again be moved apart from each other.  
                                         Reference Number List                                10   first projecting pipe piece       12   pipe       14   bending edge       16   axial direction of the pipe       18   second projecting pipe piece       20   sharp bending edge       22   clamping disk       24   drive shaft       26   first bending jaw       28   pipe axis       30   second bending jaw       32   first shaping roller       34   second shaping roller       36   tip of first shaping roller       38   tip of second shaping roller       40   flanks, first shaping roller       42   flanks, second shaping roller       44   arrow showing spreading direction       46   arrow, drive shaft       48   outer surface       50   arrow       52   displacement axis       54   arrow       56   arrow       58   arrow       60   displacement axis       62   arrow       64   arrow       66   arrow       68   arrow       70   sled       71   sled guide       72   base plate       74   double arrow       76   rotation drive       78   threaded spindle       80   side plate       82   intermediate plates       84   sector plate       86   screws       88   arc       90   straight       92   straight       94   guide rollers       96   guide rollers       98   gears       100   rotation drive       102   drive pinion       104   mounting block       105   central axis       106   threaded spindle       108   drive motor       110   spindle follower       112   holder       114   slit       116   circumference       118   sector       120   widening end       122   pull rod       124   hydraulic cylinder       126   gap       128   inner surface       130   outer surface       132   clamp jaws       134   end face       136   end face       138   rest position       140   work position       142   screw       144   segment       146   drive motor       148   hollow shaft internal gear       150   widening       152   end face       154   slide surface       156   slide surface       158   counter disk       160   screws       162   distance housing       164   ball rotation mount       166   gear       168   pinion       169   holds       170   drive shaft       172   slit       174   clamping ring       176   inner surface       178   outer surface       180   clamping plate       182   bolt       184   nut       186   connecting end       188   double arrow       190   contact surface       192   slanting       194   support roller       196   rotation axis       198   circumference       200   drive shaft       202   rail system       204   circular rivet bending device       206   double arrow       208   threaded spindle