Abstract:
A method and a device for bending and reshaping profiles by means of roller bending or matrix bending. The profile that is to be worked on is bent or reshaped under the influence of one or several bending tools. In order to be able to bend and reshape also brittle profiles that are difficult to bend, an oscillator whose oscillations are supplied to the profile that is to be bent or reshaped, at least in the reshaping zone, is assigned to at least one of the bending or reshaping tools, or both.

Description:
BACKGROUND 
       [0001]    1. Field of the Invention 
         [0002]    The present invention pertains to a method and a device to bend and reshape profiles through roll or matrix bending. 
         [0003]    2. Discussion of Prior Art 
         [0004]    The term “reshape” is understood to mean that a profile is produced from a straight panel section through a reshaping process, for example. The term “bending” is understood to mean that profiles that have already been finished are bent in an arbitrary manner in two or three dimensions. The term “roll bending” is understood to mean that the bending or reshaping process occurs by passing the panel section or profile to be reshaped or bent through a roll bending process. Such a roll bending machine consists essentially of a center shaping roll that lies opposite a center roll to the profile to be bent. 
         [0005]    In the direction of travel of the profile, at least one support roll is located prior to the shaping roll and if necessary a guide roll opposite the support roll, and there can also be a bending roll behind the shaping roll. In the process, other guide rolls or slides can be provided. A roll bending process can also be accomplished in that a few of the rolls mentioned above are not designed as rolls, but as slides or pressure shoes. 
         [0006]    The invention also pertains to not just the bending of profiles in general, but in particular the bending of hollow profiles. Thin-walled hollow profiles present the problem in that the danger exists of collapsing or breaking the profile during bending. In this case, it is preferred that a mandrel shaft be fed inside the profile, said mandrel shaft supporting the profile in the bending zone from the inside. 
         [0007]    The invention also pertains to a method to bend and reshape using one or more matrices. 
         [0008]    Such matrices are bending tools that consist essentially of slides as described in U.S. Pat. No. 5,884,517, for example. In this case, the problem exists as well of reshaping and/or bending a complicated and thin-walled profile through multidimensional rotation, tilting and shifting of the individual matrices. 
         [0009]    All of the bending and reshaping processes mentioned above have been proven in practice. However, problems occur when the profile to be reshaped is hollow with a very thin wall, and when the shaping factor is high. Other problems arise when the material is a very high strength and thin-walled material. Such high strength materials include molybdenum or special alloys with high-strength characteristics that have proven to be especially brittle in the bending and/or reshaping process, thus becoming extremely difficult to bend. 
         [0010]    Such high-strength special alloys (among which include not just steel, but also light-metal alloys) cannot be bent using conventional bending methods. Moreover, it has been shown that the material of these kinds of alloys are so brittle during bending and/or reshaping that it breaks, cracks, bubbles, or returns to its original state. This means that it can&#39;t be bent any longer using conventional means. 
       SUMMARY OF THE INVENTION 
       [0011]    This is where the invention comes in, a purpose of which is to reshape or bend, or both, high-strength steel or light-metal alloys that cannot be bent using conventional methods of the type mentioned above, while nevertheless maintaining good shaping effectiveness with high precision. 
         [0012]    An important feature of the invention is that at least one oscillator is assigned to at least one of the bending tools, the oscillator causing the bending tool to oscillate. 
         [0013]    Thus, in accordance with the invention, a novel solution approach is provided in that during roll or matrix bending the respective bending tool used is subjected to an oscillation, wherein at least one of the bending tools is to be so oscillated. 
         [0014]    According to the invention, the term “oscillator” is understood to include all suitable oscillators that are capable of causing one or more of the above bending tools (rolls and/or slides and/or pressure shoes and/or matrices) to oscillate, that oscillation consequently being transferred to the bending tool and from there to the profile to be bent and/or reshaped. 
         [0015]    Such an oscillator can be an electromagnetic oscillator, for example, wherein a plurality of coil windings is excited by a corresponding excitation current so that the bending tool is caused to oscillate. These oscillations can act on the bending tool both in the longitudinal direction as well as in the radial direction and it is decided from case-to-case what oscillation is introduced to which bending tool or to which advancing tool. 
         [0016]    The invention does not just pertains to the introduction of oscillations to the bending tools but also to the introduction of oscillations to tools that fit inside the profile, such as are provided in particular by means of the mandrel shaft in the longitudinal direction, the mandrel shaft being fastened to a mandrel station. In the process, the mandrel station can itself be excited by the oscillations, as can the mandrel shaft inside the hollow profile (or a tool located inside the profile), which can have its own special oscillator. 
         [0017]    Indeed, an article by Eckart Lehfeldt: “Influence of Ultrasound on Internal Friction during Plastic Deformation of Metallic Tools” in VDI-Z-111 No. 6, pages 359-363 (1969), discloses the influence of ultrasound on internal friction in the plastic deformation of metallic materials in general. This document has been confirmed in general with the appearance of such phenomena in the microstructure of metallic materials without reference made to a bending or reshaping process. 
         [0018]    However, in the bending and reshaping processes according to the invention that operate using a roll or matrix bending method, a characterizing feature is that the profile to be bent or reshaped is subjected to a flow process that takes place outside and inside the bending zone. Outside the zone, the material of the profile to be reshaped is under tension, whereas in the area opposite to this it is under compression. This results in a rolling effect of the profile to be bent or reshaped since at the same time the microstructure is reformed through volume changes due to the flow process in the microstructure of the profile to be reshaped. 
         [0019]    It has now been shown that for high-strength aluminum or steel alloys, this flow process is insufficient if at least one or more of the bending tools are not caused to oscillate. This is where the invention comes in, with the awareness that concerning the tension or compression process at the profile to be bent, which simultaneously results in a volume change due to the rolling processes, is optimally supported by the production of oscillations. 
         [0020]    Tests have shown that, when employing the present invention, for the first time it is now possible to easily reshape high strength steels and aluminum alloys (even thin-walled hollow profiles) without cracking or breaking them or causing any undesired deformation of the profile cross section. 
         [0021]    Above, it has been explained that any arbitrary oscillator can be used as the oscillator if it is able to achieve the required oscillation frequency. Initially, an electromagnetic oscillator consisting essentially of coils excited with current was cited as the oscillator, through which a middle or high frequency oscillation can flow. Such coils can be excited at an oscillation frequency of about 50 Hz to about 20 kHz, or more. 
         [0022]    In the process, the electromagnetic windings used can be arranged in the longitudinal direction, but electromagnetic windings can also be used that run in the direction perpendicular to it, as well as three-dimensional, current-fed electromagnetic windings that produce longitudinal oscillations as well as oscillations in the radial direction, wherein even three-dimensional oscillations occur if oscillating electromagnetic coils are used in various directions. 
         [0023]    In addition to the oscillators in the form of electromagnetic coils, there is a series of other oscillators that should be included in the technical teaching of the invention. In particular, resonators are considered as ultrasonic oscillators, as well as are quartz oscillators and piezo crystals. 
         [0024]    In addition to these oscillators, mechanical oscillators are also considered such as eccentric oscillators, hydraulic oscillators, or pneumatic oscillators, in which the air or fluid cushion produces a corresponding pulsation. 
         [0025]    As explained above, the method provides oscillations from about 50 Hz to approximately 30 kHz, wherein an oscillation in the area of about 16 to 20 kHz is preferred. In this ultrasound range, especially good results were expected from the oscillation of the bending tools. 
         [0026]    With the measures taken according to the invention, an increase in bending effectiveness at profile is accomplished. In the process, either the bending tool itself can be oscillated or a corresponding oscillation can be introduced to the profile to be bent. Both embodiments are encompassed by the concept of the invention. 
         [0027]    If only one method to bend hollow profiles were to be shown in the following description, this would not be understood to be limiting. The present method pertains to the bending or reshaping of solid profiles and/or semi-open profiles such as angle, T or double T profiles as well as U profiles. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0028]    In the following, the invention is explained in more detail using multiple drawing figures depicting possible embodiments. In the process, other features and advantages of the invention derive from the drawing and their description that are essential to the invention, as shown below: 
           [0029]      FIG. 1  is a schematic representation of a bending method according to the invention with the representation of different oscillators at the bending tools; 
           [0030]      FIG. 2  shows a mandrel station to guide a double mandrel shaft, partially shown in section; 
           [0031]      FIG. 3  is a section through the point of introduction of the double mandrel shaft into the back of the profile to be bent; 
           [0032]      FIG. 4  is a partially modified embodiment of  FIG. 1  with representation of other details; 
           [0033]      FIG. 5  is the representation of a chuck with an oscillator according to the invention; 
           [0034]      FIG. 6  is a different embodiment of  FIG. 5  with representation of other details; 
           [0035]      FIG. 7  is a sectional view showing a first embodiment of the arrangement of coil windings in a bending roll in accordance with the invention; 
           [0036]      FIG. 8  is a partial rear view of the design according to  FIG. 7 ; 
           [0037]      FIG. 9A  is a second embodiment of a bending roll in section, according to the invention, showing the coil windings; 
           [0038]      FIG. 9B  is a partial rear view of the  FIG. 9A  embodiment, similar to  FIG. 8 ; 
           [0039]      FIG. 10A  is a third embodiment of a bending roll according to the invention, similar to  FIGS. 7 and 9A ; 
           [0040]      FIG. 10B  is a partial rear view of the  FIG. 10A  embodiment, similar to  FIGS. 8 and 9B ; 
           [0041]      FIG. 11  is a sectional view showing a fourth embodiment of a bending roll according to the invention; 
           [0042]      FIG. 12  is a sectional view showing a fifth embodiment of a bending roll according to the invention; 
           [0043]      FIG. 13A  is a sectional view showing a sixth embodiment of a bending roll according to the invention; 
           [0044]      FIG. 13B  is a partial rear view of the  FIG. 13A  embodiment; 
           [0045]      FIG. 14  is a sectional view showing a seventh embodiment of a bending roll according to the invention; 
           [0046]      FIG. 15  is a rear view of the bending roll according to  FIG. 14 ; 
           [0047]      FIG. 16  is a schematic view of a reshaping process using matrix reshaping according to the invention, in a sectional view; 
           [0048]      FIG. 17  is a rear view of the matrix reshaping according to  FIG. 16 ; and 
           [0049]      FIG. 18  is a side view of the matrix reshaping according to  FIG. 16 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0050]    With reference now to the drawing,  FIG. 1  shows a schematic of a profile roll bending machine that consists essentially of a head machine  1  with a center shaping roll  3  inside its frame that acts on profile  20  to be bent using an initial stress of 400 kN in the direction of arrow  4 , for example. Opposite shaping roll  3  is a center roll  2  that supports profile  20  from the side. 
         [0051]    In the direction of travel behind shaping roll  3  is external support roll  6  that sits against the outside of profile  20  to be bent, whereas inner guide roll  7  sits opposite support roll  6 . Another bending roll  5  can be placed at the discharge side. Rolls  5 ,  6 ,  7  can also be replaced by corresponding slides with the same effect. 
         [0052]    Also shown is that one or more guide rolls  15  are present at the discharge end. These are used to hold the profile to be fed as the profile  20  to be bent is fed in the direction of arrow  62  (see  FIG. 2 ). 
         [0053]    In the back, the profile is led over a bridge  10 , upon which a moveable sled  11  is located. On the sled is chuck  12  with associated jaws  14  that holds the back end of profile  20 . Two mandrel rods  13  that are parallel to one another extend through the interior of profile  20 , wherein each mandrel rod holds a mandrel shaft  16  at its free front end. 
         [0054]      FIGS. 2 and 3  indicate how the respective mandrel shafts  16  are introduced into the associated profile chamber of profile  20  and how the profile is pushed over the mandrel shafts. 
         [0055]    What is important in this embodiment is that an oscillator is associated with one or more of the bending tools. 
         [0056]    In addition, it can also be provided that in addition to the arrangement of oscillators  30 - 37  ( FIGS. 1 and 2 ) in the individual bending tools, other oscillators exist that sit against the outside of profile  20  in the form of slides.  FIG. 1  shows an embodiment of two vibration saddles  8 ,  9  opposite to one another that are located between the bending rolls  3 ,  6  and  2 ,  7 , respectively. These vibration saddles  8 ,  9  contain their own oscillators that are suitable for exerting corresponding oscillations onto profile  20  both in the axial direction as well as in the radial direction. 
         [0057]    The following description of the individual oscillators is not to be considered limiting. It is only necessary to provide a single oscillator at any of the bending tools on a case-by-case basis. In other embodiments, however, it is possible that a plurality of bending tools contain such oscillators. Finally, all bending tools cumulatively can be provided with corresponding oscillators. 
         [0058]      FIG. 1  is shown as an embodiment such that oscillator  30  is located in chuck  12  that exerts an oscillation onto profile  20 , held there via jaws  14 , that oscillation acting in the longitudinal direction. 
         [0059]    Furthermore, schematically shown is that in one or more of the bending or support rolls  2 ,  3 ,  5 ,  6  one or more oscillators  31 - 35  are arranged. 
         [0060]    Finally,  FIG. 2  shows that mandrel station  17 , which supports the free, rear end of mandrel rods  13 , is acted upon by an associated oscillator  36 . In this way, mandrel shafts  16  are also caused to oscillate as a result of mandrel rods  13  that are made to oscillate. More will be said about this later in connection with  FIG. 4 . 
         [0061]      FIG. 2  shows that mandrel shaft seat  18  can also be provided with an oscillator that introduces an oscillation that acts on the mandrel shaft in the vertical direction (=Z-plane) in the direction of arrow  19 . In this manner, a semi-standing wave is produced in mandrel rod  13  and thus in mandrel shafts  16 , which results in especially good reshaping results in the interior of the profile. Details are illustrated in this regard in  FIG. 4 . In  FIG. 4  it can be seen that a respective mandrel rod  13  has a center hole  22  that runs in the longitudinal direction that leaves space through which to pass the cable and an oil channel. Cable  21  is used to supply coil winding  23 , located inside mandrel shaft  16 , with a pulsating direct current or an alternating current. 
         [0062]    Due to the resultant magneto friction and the magnetic effects in the metallic material, the entire mandrel shaft  16  oscillates in the longitudinal direction (direction of arrow  29 ) and in the perpendicular direction thereto, namely in the direction of arrow  19 . 
         [0063]    The oil introduced through center hole  22  passes through mandrel shaft  16  forward in the direction of oil channels  24  that run generally perpendicular to it and radially outward. There, the oil comes to the outer surface of mandrel shaft  16  and produces an oil film  25  at the outer surface. 
         [0064]    The front side of mandrel shaft  16  is made up of a head plate  26 , the outside surface of which contains opposite casing liners  27  that assume a corresponding support function against the high deformational forces in the bending gap between shaping roll  3  and opposite center roll  2 . The high-stress primary bending takes place in the area of casing liners  27 , with a concomitant change in microstructure as described above, wherein the oscillation produced by coil winding  23  is transferred to casing liners  27 , in particular to the inside of profile  20 . 
         [0065]    The vibration production at mandrel shaft  16  acts furthermore secondarily to minimize the friction between the outer surface of the mandrel shaft and the inner surface of the profile to be bent, in particular in the area of the bending zone. 
         [0066]    It has been shown that excellent frictional characteristics have been achieved by the vibration production at oil film  25 , since the oil is especially thin due to the back and forth motion, is distributed well and produces excellent lubrication motion at the inside surface of the profile to be reshaped. For the purposes of completeness, it should be mentioned that coil winding  23  is located in a sleeve  28  inside mandrel shaft  16 . 
         [0067]      FIG. 5  shows that chuck  12  is also provided with an oscillator  30 , wherein the chucking of profile  20  is done using a chucking cylinder  38  that sits against the outside surface of profile  20 . In chuck  12  is oscillator  30  that consists of a current-fed coil winding so that an oscillation is also produced via the chuck in the longitudinal direction. In addition, the figure shows that oscillator  37  is also associated with mandrel rod  13 . Here, the invention provides in one embodiment that only mandrel rod  13  has an oscillator  37 , in which case mandrel shaft  16  has no oscillator. In another embodiment, however, it can be provided that only mandrel shaft  16  has the oscillator described previously, whereas mandrel rod  13  does not have its own oscillator. 
         [0068]    Other details are shown in  FIG. 6 . Here, oil connection  40  is provided for the introduction of oil to mandrel rod  13  at mandrel station  17 . Furthermore, the mandrel rod is introduced via guide rolls  39  to chuck  12  and oscillator  30  mentioned previously is located in chuck  12 . 
         [0069]      FIGS. 7 through 15  show various embodiments of bending tools that are all provided with an oscillator. Here, it is shown only by way of example that such an oscillator can consist of a current-fed coil. The invention is not limited to this, however. Instead of a current-fed coil, other oscillators can be used such as had been mentioned in the general description portion. In particular, piezoelectric crystals and other oscillators that are capable of producing ultrasonic oscillations are included here. 
         [0070]    As a first embodiment, as shown in  FIGS. 7 and 8 , one or more of bending rolls  2 ,  3 ,  5 ,  6  each are designed as metal rolls, wherein a circular notch  42  is placed at each end of the roll into which a respective coil winding  44  is inserted. This coil winding  44  is circular, as indicated in  FIG. 8 . Such coil windings  44  can be manufactured as self-contained elements by casting them in a plastic body for example, and they are then installed as circular elements into each of the associated notches (circular notch  42 ) at the backs of the respective roll. 
         [0071]    In another embodiment, the winding can be inserted directly into circular notch  42  without having to first fix it in a self-contained body. 
         [0072]    In mass production, it is preferred that coil windings  44  can be produced and that they are self-contained so that they can be inserted as a separate element into the circular notch  42  with a perfect fit at each end of the roll  2 ,  3 ,  5 ,  6 . Each end is then closed with a cover  43 . 
         [0073]    The power supply to coil windings  44  is done through slip rings in known manner and are not shown further. The slip rings are, for example, located at one end of bending rolls  2 ,  3 ,  5 ,  6  and are connected to an appropriate power source using associated terminals in a conventional way. Instead of the wired coupling of the excitation current for coil windings  44 , an inductive (wireless) coupling can also be provided. The result is that roll surface  46  oscillates by increasing its diameter, for example forming roll surface  46 , as shown in  FIG. 7 . 
         [0074]    Also, the roll surfaces can be designed to make a sinusoidal oscillation along their entire axial length so that no radial, outwardly directed deformation of roll surface  46  occurs toward that roll surface, but a sine wave that extends along the axial length of roll surface  46  and deforms it in the form of a sine curve. Roll surface  46  is designed between two flanges  41  of enlarged diameter, wherein these flanges can also deform in the manner shown in dashed lines. 
         [0075]    Rolls  2 ,  3 ,  5 ,  6  are mounted rotatably on axial shaft  45  by means of a friction bearing, for example. In addition to a friction bearing, conventional ball bearings or other bearing supports can be used. 
         [0076]      FIG. 9  shows a dual design of a roll  2 ,  3 ,  5 ,  6  compared to  FIG. 7 , where it can be seen that the roll design is twice that according to  FIG. 7  and the two rolls abut one another near center joint  47 . This leads to the result that current-fed coil windings  48  exist in especially concentrated form near joint  47 , whereby a very pronounced mechanical deformation is produced in this area. The vibration effect of such a roll  2 ,  3 ,  5 ,  6  is correspondingly increased in comparison to the effect according to  FIGS. 7 and 8 . 
         [0077]    Another increase results from the design of a roll of this type as a five-part reshaping roll that has a total of six-fold coil windings  48 . 
         [0078]      FIG. 11  shows a fourfold roll according to  FIG. 9 , wherein what is shown additionally is that an additional oscillator can be installed in shaft  45 . This oscillator  63  causes an internal excitation of shaft  45  with a corresponding oscillation. In the center hole  50  of shaft  45  is a sleeve  51  in which one or more coil windings  52  are located. Coil winding  52  is anchored using a threaded rod  53  and the excitation voltage is introduced via connection wires  54 . 
         [0079]    In this way, the entire shaft  45  oscillates in the perpendicular direction, namely, in the direction of arrow  19 , and exerts this oscillation onto the bending tool  2 ,  3 ,  5 ,  6  via the friction bearing mentioned above. This bending tool (bending roll) then oscillates uniquely due to the separate power supply to coil windings  44 . 
         [0080]    In the process, the excitation of the coil winding  52  in the axial oscillator  63  can be produced at another amplitude and another oscillation frequency such as the excitation of coil windings  44 . This guarantees that the bending roll  2 ,  3 ,  5 ,  6  oscillates both in the longitudinal direction as well as in radial direction  19 . 
         [0081]      FIG. 12  shows another oscillator  55  placed on the outside of shaft  45  instead of an oscillator  63  located internal to the shaft. This oscillation package consists essentially of external coil winding  56  that is located in an associated support that is placed on shaft  45  as tightly as possible. In this way, shaft  45  experiences an oscillation in the longitudinal direction and in the perpendicular direction. This oscillation is conveyed to roll  2 ,  3 ,  5 ,  6  as well via the associated friction bearing. 
         [0082]      FIGS. 13A and 13B  shows in another embodiment that coil windings  58  are located near a bushing  57  that forms a friction bearing with shaft  45  as a special part. Bushing  57  is therefore easily replaced and can be replaced by other bushings with other coil windings  58 . 
         [0083]    It supports a center support ring  59  of enlarged diameter through which the bending forces are absorbed, such forces acting in particular on the middle range of the rolls  2 ,  3 ,  5 ,  6 . 
         [0084]      FIGS. 14 and 15  show in another embodiment that rolls  2 ,  3 ,  5 ,  6  can also have axial holes  60  that are distributed along the periphery and that sit parallel to one another. Coil winding  61  fits in each axial hole  60  and all coil windings  61  are fed by a common power source (not shown). Here as well, the two ends are likewise covered by a single cover  43 . 
         [0085]      FIGS. 16-18  show in general a reshaping process that uses known matrix reshaping methods. In the process, a bending matrix  70  is provided in two or three spatial axes. This matrix can be moved in the directions of arrows  71 ,  72 ,  75  and in addition can be rotated in the rotational directions  73 ,  74 . 
         [0086]    The profile  20  to be bent extends through the passage gap of bending matrix  70 . Mandrel shaft  16  is led inside this profile (as shown above) in the bending zone, the shaft being moved by a mandrel rod  13 . One or more fixed matrices  64  are located at a distance from-bending matrix  70  that sit against the profile to be bent and that have lubricating pad  67  at these seat surfaces. 
         [0087]    What is important at this point is that at least one oscillator  65  is assigned to bending matrix  70 , that oscillator producing an approximately centric (star-shaped) oscillation at the passage gap in bending matrix  70  so that it rhythmically enlarges and reduces, and thus communicates a corresponding vibration to profile  20  to be bent. 
         [0088]    In addition, fixed matrices  64  can be assigned their own oscillators  66 . These oscillators act on lubricating pad  67  in particular, which as a result are caused to oscillate in order to produce an improved lubrication effect on profile  20  being fed through at that point. The profile to be bent is fed through in the direction of arrow  68  through fixed matrices  64  and the bending matrix  70  that follows. 
         [0089]    It is evident that mandrel rod  13  and/or mandrel shaft  16  can be acted upon by its own oscillator as was explained above in the general description. Likewise, it is possible to impart the profile itself with an oscillation via chuck  12 . Also, in this exemplary embodiment according to  FIGS. 16-18 , the lubrication in mandrel shaft  16  can occur with the aid of an oscillator as was explained in  FIG. 4 . 
         [0090]    All discussions concerning the roll bending method therefore apply to the matrix bending process according to  FIGS. 16-18 .