Abstract:
A device for bending tubular workpieces includes a straight workpiece section that extends in a longitudinal direction and is held in a clamping device. A bending tool for bending the workpiece around a bending axis, that runs transversely to the longitudinal direction, has a radial part and a bending part. The radial part is rotatable about the bending axis. The bending part can be pivoted relative to the radial part for bending the workpiece about the bending axis. For rotatable driving, a radial driveshaft is coupled to the radial part, and a bending driveshaft is coupled to the bending part. To very flexibly create a plurality of different bends and to be able to use variable bend geometries, the radial driveshaft and the bending driveshaft extend in the longitudinal direction. The radial driveshaft and/or the bending driveshaft are designed as a hollow shaft, and one is arranged coaxially around the other.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to a device and method for bending tubular workpieces, in particular pipes. 
         [0002]    Various types of bending machines are known for bending e.g., fuel, brake or hydraulic lines. 
         [0003]    DE 203 01 138 U1 describes a bending machine with a fixed clamping unit for fixing a pipe to be bent and with a bending unit that can move relative thereto with a bending head to which a bending tool is attached at the end of an extension arm. The bending tool comprises a counter roller and a sliding piece that can be pivoted around the counter roller. The bending tool is positioned by moving the bending head at a bending point so that bending of the pipe is effectuated by pivoting the sliding piece around the counter roller. 
         [0004]    In EP 1 591 174, a bending device is described for rod-shaped and tubular workpieces that has a bending head with a bending mandrel and a clamping apparatus for pressing the workpiece to be bent against a shaped groove in the bending mandrel. The bending mandrel can be rotated by means of a rotary drive, and the clamping apparatus can be pivoted concentrically to the rotary axis of the bending mandrel. The bending head is connected to rotary drives that are independent of each other. To transmit the drive from the three rotary drives to the bending mandrel, a conversion gear and the clamping apparatus, three rotary shafts arranged concentrically with each other are provided, each of which is connected to one of the rotary drives. 
       SUMMARY OF THE INVENTION 
       [0005]    It is a principle object of the present invention to provide a device and a method for bending tubular workpieces that can be used very flexibly for a plurality of different bends to produce variable bend geometries. 
         [0006]    For a bending device to be particularly flexible in use, a plurality of elements of the bending tool, which participate in bending, are separately drivable. Whereas in principle a single drivable element would be sufficient to cause bending, such that for example one bending part is pivotable relative to a fixed radial part, the flexible utility for different types of bends and types of tubular workpieces is significantly increased by additional drivable elements, such as for bending to the right/left, bending by rolling and drawing, bending workpieces with flexible sections, etc. 
         [0007]    The size and arrangement of the parts placed on the bending tool is of decisive importance for the achievable bend geometries. These form the so-called interfering edge, i.e., a restriction of achievable bending without the bent end of the pipeline striking. A small interfering edge is of decisive importance, for example with complicated bend geometries, in particular with larger bending angles. 
         [0008]    A central consideration in the development of the device according to the invention and method according to the invention was on the one hand to drive a plurality of elements of the bending tool, whereas on the other hand there should be a small interfering edge. 
         [0009]    With the device according to the invention and the method according to the invention, a longitudinal direction corresponds to the direction of the as yet unbent workpiece, i.e., a straight workpiece section, held in a clamping device, of the workpiece to be bent. This longitudinal direction is dictated for the device by the arrangement of the clamping device and the bending workpiece between which the unbent part of the workpiece extends. In the following description, the workpiece will be consistently termed the pipe, wherein the pipe axis runs in the defined longitudinal direction. However, this does not exclude the device from being able to be used to bend other workpieces of a comparable shape such as rods. 
         [0010]    According to the invention, a bending tool is provided in order to bend the pipe around a bending axis that runs transversely to the pipe axis. The bending tool comprises at least one radial part and one bending part, wherein the radial part can be rotated about the bending axis, and the bending part can be pivoted about the bending axis relative to the radial part in order to bend the pipe. 
         [0011]    A radial driveshaft and a bending driveshaft are provided to rotatably drive the radial part and the bending part. The drive shafts serve to transmit rotation from a drive over a certain distance to the bending tool. The drive can accordingly be arranged at a distance from the bending tool and does not contribute, or only slightly contributes, to the interfering edge. The radial driveshaft is coupled to the radial part, and the bending driveshaft is coupled to the bending part, such that the coupled part is rotated by rotating the respective driveshaft. Accordingly, the two movable elements of the bending tool can be controlled and driven separately by the two driveshafts. 
         [0012]    With the device according to the invention and the method according to the invention, a particularly compact arrangement with a small interfering edge is achieved in that the radial driveshaft and the bending driveshaft extend in the longitudinal direction, i.e., parallel to the alignment of the clamped pipe dictated by the clamping device and the bending tool, and the radial driveshaft and/or the bending driveshaft are designed as a hollow shaft, wherein one of the two driveshafts is arranged around to the other of the two driveshafts. Preferably, the radial driveshaft can be designed as a solid shaft, whereas the bending drive shaft is designed as a hollow shaft and is arranged coaxially around the radial driveshaft. 
         [0013]    By using driveshafts that are arranged coaxially to each other, of which at least the outer one is designed as a hollow shaft, an extremely compact arrangement is achieved. Because this arrangement also extends in the longitudinal direction and hence parallel to the pipe, a particularly small interfering edge arises such that a plurality of bend geometries, including with large bending angles, is still possible on the bending tool without the bent pipe striking the driveshafts or a housing arranged around them. 
         [0014]    In preferred embodiments, the bending tool can comprise further elements that are movable by a drive. For example, a pivotably movable holding part for resting against the pipe can be provided on the tool. Various bends can be supported by a pivotably movable holding part, such as in the case of pipes with flexible sections. To drive the pivotable holding part, a holding part driveshaft can be provided that is coupled to the holding part for rotatable driving, and also extends in the longitudinal direction like the radial driveshaft and the bending driveshaft. It is particularly preferable that the holding part driveshaft can be designed as a hollow shaft and arranged coaxially around the radial driveshaft, and/or the bending driveshaft. A coaxial arrangement of the three driveshafts is particularly preferable, for example with the bending driveshaft as a hollow shaft around the radial driveshaft, and the holding part driveshaft as a hollow shaft around the bending driveshaft. Due to the coaxial arrangement, a particularly compact design with a small interfering edge is achieved, including for bending tools with three elements that are movably driven. 
         [0015]    For the pivotably movable holding part, it is preferable for the holding part to be arranged pivotably about a holding part axis that runs parallel to the bending axis, but is arranged at a distance thereto. The holding part can accordingly satisfy a holding function by resting against the pipe at a distance from the bending point. 
         [0016]    According to a preferred embodiment of the invention, the bending part is designed so that it has at least one, preferably at least two sections that encompass the radial part. Pivotability of the bending part about the radial part can thus be ensured. 
         [0017]    To couple the different drive shafts to the movable elements of the bending tool, preferably one or more corner gears can be provided. These are to be understood as gears that, for example, comprise two or more rotating parts and enable a deflection of the direction of movement so that the rotation of the drive shafts running in the longitudinal direction can be converted into a rotation about the rotary, or respectively pivot axis of the movable parts of the bending tool, wherein these rotary, or respectively pivot axes are preferably aligned transversely, i.e., at least substantially at a right angle, to the longitudinal direction. Accordingly, for example, a corner gear can be provided between the radial driveshaft and the radial part, and/or between the bending driveshaft and the bending part, and/or between the holding part driveshaft and the holding part. Each of the corner gears can comprise at least a pair of bevel gears. Preferably, the drive shafts can have bevel gears on the end. 
         [0018]    In preferred embodiments, the bending tool is not stationary but rather suitably positionable relative to the clamping device. Depending on the desired design, this can comprise a positioning in the longitudinal or transverse direction, or a rotation about the longitudinal axis of the pipe as well, or a combination of several or all of these movements. 
         [0019]    In particular, it is preferable for the bending tool to be arranged on a bending head that can move in the longitudinal direction relative to the clamping device. The respective bending point can thereby be specifically approached. Whereas it is possible to use a fixed bending tool and move the pipe, or respectively the clamping device instead, a fixed clamping device and a pipe securely clamped therein is preferred in relation to which the bending head can be moved. 
         [0020]    It is furthermore preferred for the bending head to be adjustable relative to the clamping device such that the bending tool is rotatable about a rotary axis aligned in the longitudinal direction. With such an arrangement, the bending tool can be rotated about the pipe axis to set the desired bending direction. It is moreover alternatively possible to use a fixed bending tool and instead rotate the pipe, or respectively the clamping device. However in this case as well, a fixed clamping device and fixed pipe are preferred, about the longitudinal axis of which the bending tool can be rotated. 
         [0021]    According to a preferred further embodiment of the invention, the bending head can also be adjustable relative to the clamping device so that the position of the bending tool is adjustable transversely to the longitudinal direction. Depending on the direction, such an adjustment can be designated an offset in the horizontal direction, or a lift in the vertical direction. Such an adjustment, in particular between two or more positions that are arranged at a distance in the direction of the bending axis, can for example be used to bring different pipe sections specifically into contact with different sections of the elements of the bending tool. For example, an adjustable lift can be used to bring grooves of different sizes in the radial part, or respectively bending part, into contact with the pipe. An offset of the bending tool relative to the pipe can in particular be used to switch between bending to the right and to the left. To enable this without switching the pipe, a combined lift/offset movement can be used so that the bending tool passes below the pipe previously accommodated on a side between the radial part and bending part, and again accommodates the pipe on the other side. 
         [0022]    In a preferred embodiment, the drive shafts, i.e., the radial driveshaft, and/or the bending driveshaft, and/or the holding part driveshaft can be arranged in a tubular housing. Preferably, the tubular housing can extend from a movable bending head in the longitudinal direction toward the bending tool. A particularly compact arrangement with a small interfering edge can thereby be achieved. The tubular housing with the driveshafts arranged therein can be very narrow, for example have a maximum extension in the cross-section that is less than half the length. Preferably, the length of the housing is more than four times the lateral measurement (i.e., of the diameter of a round housing). 
         [0023]    For a full understanding of the present invention, reference should now be made to the following detailed description of the preferred embodiments of the invention as illustrated in the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]      FIGS. 1 a , 1 b  and 1 c    are side views of a pipe bending machine in different positions. 
           [0025]      FIG. 2  shows the bending machine from  FIG. 1  in a perspective view. 
           [0026]      FIGS. 3 a  and 3 b    show perspective views of a tool holder of the bending machine from  FIGS. 1 a , 1 b , 1 c    and  FIG. 2 . 
           [0027]      FIGS. 4 a  and 4 b    show a plan view and perspective view of a bending tool on the tool holder from  FIGS. 3 a    and  3   b.    
           [0028]      FIG. 5  is a side view of a tool holder from  FIGS. 3 a  and 3 b    in a longitudinal section. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0029]    The preferred embodiments of the present invention will now be described with reference to  FIGS. 1-5  of the drawings. Identical elements in the various figures are designated with the same reference numerals. 
         [0030]      FIGS. 1 a -1 c    show a pipe bending machine  10  with a fixed clamping unit  12 , relative to which a bending tower  14  in a machine bed  16  can be moved in a longitudinal direction L. 
         [0031]    The bending tower  14  bears a bending head  22  to which a bending tool  26  is attached by a tool holder  24 . The bending head  22  can rotate about the axis. Controllable drives (not shown) are provided for moving the bending tower  14  and rotating the bending head  22 . 
         [0032]    In  FIG. 1 a   , the unbent pipe  20  is securely clamped in a clamping head  18  of the clamping device  12  so that the pipe  20  is aligned in the longitudinal direction L. The clamped pipe end remains consistently stationary during the bending process and is not moved or rotated. The bending head  22  has an opening  28  of an axially running passage through which the pipe  20  is inserted. The bending tool  26  is positioned on the pipe  20 . 
         [0033]    While the pipe bending machine  10  is operating, the pipe  20  is shaped into a desired bend geometry by the bending tool  26  by applying successive bends. First the bending point at the furthest distance from the clamped end of the pipe  20  is approached, and the bending tool  26  is positioned there. By means of a rotating mechanism (not shown), the bending head  22  can be rotated about the longitudinal axis L of the pipe  20  so that the bending tool  26  can be actuated to create a bend about a bending plane running transversely to the longitudinal axis L. 
         [0034]    The elements of the bending tool  26  can be seen more precisely in the depictions in  FIGS. 3 a , 3 b , 4 a  and 4 b   . On movable, driven elements, the bending tool  26  comprises a radial roller  30  that is rotatable about a bending axis B, a bending roller  32  that is pivotable about the bending axis B, and a counter holder  34  that is pivotable about a pivot axis S. 
         [0035]    The radial roller  30  comprises a plurality of bending grooves  36  at a distance from each other in the longitudinal direction of the radial roller  30  that each extend around a part of the circumference of the radial roller  30 . The bending roller  32  comprises associated bending grooves  38  at the same spacing which are arranged on the side of the bending roller  32  facing the radial roller  30 . 
         [0036]    To create a bend in the pipe  20 , it is accommodated between the radial roller  30  and the bending roller  32  in one of the radial grooves  36  and one of the bending grooves  38 . The different radial grooves  36  and associated bending grooves  38  are provided to accommodate pipes of different outer diameters. 
         [0037]    By pivoting the bending roller  32  about the bending axis B, a bend in the pipe  20  is generated in a bending plane perpendicular to the bending axis B while simultaneously rotating the radial roller  30 . 
         [0038]    The bending roller  32  is arranged to pivot around the radial roller  30  by two holding elements  40  that encompass the bending axis B. Bending by rolling as well as drawing is accordingly possible with the bending tool  26 . The bending roller  32  can be pivoted about the radial roller  30  within a pivoting range of at least 180°. Depending on the actuation of the radial roller  30  and bending roller  32  in the bending plane, a bend both to the right and left is possible. 
         [0039]    If required by the respective bend which in particular can be the case when bending pipes with flexible sections, the pivotable counter holder  34  can be placed on the side of the pipe  20 . As a lever, the counter holder  34  can pivot about the pivot axis S that runs parallel from the bending axis B at a distance. The counter holder  34  can be moved into the suitable pivot position for each bend. Various grooves to be placed against the side of the pipe  20  are provided one above the other in the counter holder  34  as well. 
         [0040]    In order to shape the initially unbent pipe  20  into a desired bending geometry, a plurality of bends are made sequentially in the above-describe manner, wherein the bending tool  26  is positioned at the next bending point by moving the bending tower  14  along the longitudinal direction L toward the clamping device  12 , then, by rotating the bending head  22  about the pipe axis L, the bending tool  26  is positioned in the desired bending plane, and subsequently the radial roller  30 , bending roller  32 , and if applicable counter roller  34  are actuated to create the desired bend. 
         [0041]      FIGS. 1 a   - FIG. 1 c    sequentially show how the bending tower  14  always gradually approaches the clamping device  12  when creating the sequential bends. In so doing, the clamping head  18  arranged on an extension  42  of the clamping device  12  is guided through the opening  28  and passage in the bending head  22  until the last bend is performed. The bent pipe can then be removed. 
         [0042]    As shown in  FIGS. 1 a   - FIG. 1 c    and as can be seen in greater detail in  FIGS. 4 a  and 4 b   , only the bending tool  26 , from which extends only the elongated, relatively thin tool holder  24 , is arranged directly on the pipe  20 . Since the tool holder  24  is aligned in the longitudinal direction L and extends toward the clamping device  18 , a design is achieved in which, proceeding from the bending point, there is only a very small interfering edge, i.e.; fixed parts of the bending tool  26 , or of its attachment (tool holder  24 ), which the pipe can strike when bending, in particular at large bending angles. 
         [0043]    The tubular tool holder  24  serves not only to hold and position the bending tool  26 , but also to drive the movable elements  30 ,  32 ,  34  of the bending tool  26 . 
         [0044]    As can be seen from the longitudinal section in  FIG. 5 , the tool holder  24  is a hollow pipe that is fastened at one end to the bending tool  26  and at the other end to the bending head  22  (not shown in  FIG. 3 a   ,  FIG. 3 b    and  FIG. 5 ).  FIG. 5  does not show the entire length of the tool holder  24 ; in fact, the tool holder is about six times as long as it is wide as, for example, can be seen in  FIGS. 3 a    and  3   b.    
         [0045]    Three shafts are coaxially arranged within the interior of the tool holder  24 . A solid inner shaft serves as a radial driveshaft  44 . A hollow shaft arranged around the radial driveshaft  44  serves as a bending driveshaft  46 . Arranged, in turn, around the bending driveshaft  46  coaxial thereto is another hollow shaft as a counter holder driveshaft  48 . 
         [0046]    As can be seen in  FIG. 3 a   ,  FIG. 3 b    and  FIG. 5 , three drive pinions that are arranged axially next to each other are provided on the end of the tool holder  24 . As can be seen in  FIG. 5 , the inner radial driveshaft  44  is coupled to the rear-most drive pinion  50   a , the bending driveshaft  46  is coupled to the middle pinion  50   b , and the outer holding part driveshaft  48  is coupled to the front pinion  50   c.    
         [0047]    Within the bending head  20 , drives (not shown) are provided for the pinions  50   a ,  50   b ,  50   c . They are preferably belt drives. 
         [0048]    As shown in  FIG. 5 , the rotary movement of the three drive shafts  44 ,  46 ,  48  is transmitted by corner gears to the radial roller  30 , bending roller  32  and counter holder  34 . 
         [0049]    For this purpose, corner gears are always provided on the end of each of the drive shafts  44 ,  46 ,  48  by means of which the rotary movement is deflected by bevel gears at an angle of 90° in the depicted example. A first corner gear  52   a  is formed between a first bevel gear  54   a  formed on the end of the radial driveshaft  44  and a second bevel gear  56   a  coupled to the radial roller  30 . A second corner gear  52   b  is formed between a first bevel gear  54   b  formed on the end of the bending driveshaft  46  and a second bevel gear  56   b  coupled to the bending roller  32 . The bevel gears  54   a ,  56   a  of the first corner gear  52   a  are designed solid, whereas the bevel gears  54   b ,  56   b  of the second corner gear  52   b  are designed hollow and are arranged coaxial to the bevel gears  54   a ,  56   a  of the first corner gear  52   a . In this manner, rotary movements of the drive pinion  50   a ,  50   b  are transmitted via the coaxial drive shafts  44 ,  46  and converted into coaxial rotations of the radial roller  30  and bending roller  32 . 
         [0050]    A third corner gear  52   c  is formed on the bending tool  26  at a distance from the first and second corner gear  52   a ,  52   b . For this purpose, the counter holder driveshaft  48  is designed somewhat shorter than the two other driveshafts  44 ,  46 . A first bevel gear  54   c  is arranged on its end and engages with a second bevel gear  56   c  which is arranged around the pivot axis S of the counter holder  34 . In this manner, a rotary movement of the drive pinion  54   c  can be transmitted by the counter holder driveshaft  48  and the corner gear  52   c  to the counter holder  34 . 
         [0051]    Accordingly, the movable elements  30 ,  32 ,  34  on the bending tool  26  can be rotatably driven independently and separate from each other in order to execute desired rotary, or respectively pivoting movements to create desired bends. The achievable movements are not thereby restricted, so that bends to the right/left are also enabled as well as rolling/draw bending as desired. 
         [0052]    Thereby the tool holder  24  makes it possible for the bending tool  26  to be suitably positioned by the bending head  22 , wherein at the same time a drive of the elements  30 ,  32 ,  34  of the bending tool  26  is achieved in an extremely compact arrangement with a small interfering edge. 
         [0053]    There has thus been shown and described a novel device and method for bending pipes which fulfills all the objects and advantages sought therefor. Many changes, modifications, variations and other uses and applications of the subject invention will, however, become apparent to those skilled in the art after considering this specification and the accompanying drawings which disclose the preferred embodiments thereof. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention, which is to be limited only by the claims which follow.