Patent Publication Number: US-10315239-B2

Title: Forming tool for the production of a hollow component, and method for operating the forming tool

Description:
RELATED APPLICATIONS 
     The present application claims the priority of German Application Number 10 2017 102 139.6, filed Feb. 3, 2017, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     TECHNICAL FIELD 
     The present invention relates to a forming tool for the production of a hollow component by sheet-metal forming. 
     The present invention furthermore relates to a method for operating the forming tool. 
     The present invention furthermore relates to a forming tool of a hollow component by sheet-metal forming. 
     BACKGROUND 
     It is known in the prior art for components, in particular motor vehicle components, to be produced by sheet-metal forming. To this end, a sheet-metal blank is provided, this in most instances being a sheet-steel blank. Light-metal materials such as, for example, aluminum alloys or similar, can also be used. 
     To this end, the respective sheet-metal blank is formed to a three-dimensionally shaped sheet-metal formed component between an upper tool and a lower tool. Such sheet-metal components in most instances have a shell-shaped configuration. 
     In order for hollow components, in particular hollow components that are closed in the cross section, to now be produced by means of sheet-metal forming methods, U-to-O forming is known from the prior art. To this end, a sheet-metal blank is likewise first provided. This sheet-metal blank is formed in such a manner that said sheet-metal blank has a U-shaped configuration in the cross section. In a subsequent forming step, the outwardly directed or projecting, respectively, legs of the U-shape are then further formed so as to generate a cross-sectional O-shape, consequently a hollow profile that is closed in the cross section. 
     U-shapes and O-shapes in the context of the invention does not mean that a cross-sectional U and an O have to be necessarily adhered to. U-shaped is to be interpreted in such a wide manner that a hollow profile that is unilaterally open is produced, and O-shaped to be interpreted in such a wide manner that a hollow profile that is closed in the cross section is produced, the latter as opposed to the letter O however also potentially having other closed geometries. 
     In order for cross sections that are mutually dissimilar across the longitudinal profile to now be able to be formed, in the case of O-shapes mandrels are driven into particularly the end side of the hollow component to be produced and withdrawn upon completion of the forming procedure. 
     A forming tool in which the end-side plug-in mandrels in conjunction with a U-to-O forming procedure can also be configured in segments is known from DE 10 2011 051 965 A1, for example. 
     SUMMARY 
     It is an object of the present invention to provide a forming tool and a method for operating the forming tool which compared with forming tools known from the prior art can be operated with low complexity in terms of the driving-in of mandrels. 
     The aspect of the device of the object is achieved by a forming tool for the production of a hollow component by sheet-metal forming. 
     An aspect of the method of the object is achieved by a method for the production of a hollow component. 
     A further achievement of the aspect of the device of the object provides a forming tool. 
     Advantageous variants of design embodiments of the present invention are described. 
     The forming tool for the production of a hollow component by sheet-metal forming has an upper tool and a lower tool. A mandrel that is driven into the hollow component to be formed and an auxiliary mandrel that is repositionable relative to the mandrel are disposed on the upper tool. The mandrel and the auxiliary mandrel are by way of in each case one spring-elastic actuation means preferably coupled to the upper tool. The mandrel when the upper tool is being lowered is driven into the hollow component to be formed and at least in part comes to bear therein. The hollow component to be formed at this stage is in particular a U-shaped preformed preform component, consequently a profile that is unilaterally open in the cross section. 
     A further lowering of the upper tool leads to a compression of the spring-elastic actuation means between the mandrel and the upper tool. 
     Once the mandrel has come to bear, a relative movement of the auxiliary mandrel in relation to the mandrel is carried out by further lowering the upper tool. To this end, in particular the auxiliary mandrel is coupled to the upper tool by way of an adjustment mechanism, in particular a coupling bar. The auxiliary mandrel is driven into the hollow component to be formed in particular in a movement direction at an angle in relation to the press stroke direction of the upper tool. 
     The forming procedure from the U-shaped preform component to the O-shaped hollow component is simultaneously carried out by the further lowering of the upper tool. A hollow component having mutually dissimilar cross-sectional geometries in the longitudinal direction is generated by driving in the mandrel and the auxiliary mandrel into an end-side region of the hollow component to be formed. 
     Cross-sectional geometries which are mutually dissimilar in the longitudinal direction can be generated herein during the one forming procedure. 
     On account of the spring-elastic actuation means which in particular is a gas pressure damper or a spring element, the mandrel comes to bear on the preform component already before the upper tool has reached the lower dead center. A further lowering of the upper tool then leads to a compression of the spring-elastic actuation means between the mandrel and the upper tool. The auxiliary mandrel, by virtue of the adjustment mechanism, can carry out a movement relative to the mandrel during this compression, and is thus driven laterally or at the end side, respectively, into the hollow component to be formed, in particular at an angle of more than 10° in relation to the press stroke direction. This movement direction upon completion of the forming procedure is then carried out in the reversed sequence such that the auxiliary mandrel is first driven out of the end side of the formed hollow component, wherein a closed cross-sectional geometry has been produced at the end side at least in longitudinal portions and the auxiliary mandrel is nevertheless able to be withdrawn. 
     The mandrel per se furthermore has an external contour which corresponds to the internal contour of the hollow component to be produced, at least in terms of an end-side longitudinal portion. 
     An incline, hereunder also referred to as an inclined face, is provided in the mandrel per se, wherein the auxiliary mandrel when carrying out the movement relative to the mandrel slides across the inclined face. The inclined face in particular runs at an angle of more than 10°, preferably more than 20°, in relation to the press stroke direction of the upper tool or of the forming tool, respectively. By further lowering the upper tool in the press stroke direction, the auxiliary mandrel thus carries out a relative movement which is not exclusively directed in the press stroke direction but by virtue of the inclined face is simultaneously at least partially also oriented in the direction transverse to the press stroke direction. 
     The auxiliary mandrel is furthermore particularly preferably at least in portions disposed in the mandrel per se. The mandrel in particular has an opening which penetrates the mandrel, wherein the auxiliary mandrel is disposed in the penetrating opening. On one side of the opening, the auxiliary mandrel is coupled to the upper tool by way of the adjustment mechanism. On the other side of the opening, the auxiliary mandrel carries out the movement relative to the mandrel and thus, at the lower dead center of the upper tool, in part protrudes from the mandrel. 
     The auxiliary mandrel is coupled to the upper tool by way of an adjustment mechanism, also referred to as the coupling mechanism. In particular, a spring-elastic actuation means, for example a spring or a gas pressure damper, is likewise conjointly incorporated here. The coupling mechanism can operate according to the principle of a knuckle joint, for example. The spring-elastic actuation means furthermore ensures that in the case of an unexpected blockage or, depending on the layout of the driving-in movement of the auxiliary mandrel, a further lowering of the upper tool does not lead to undesirable deformations but is compensated for by a compression of the spring-elastic actuation means. The spring-elastic actuation means of the mandrel as well as of the auxiliary mandrel is preferably driven passively by the movement of the forming tool. 
     The method according to the invention, which is carried out on the forming tool described above, provides that a hollow component that in the cross section is closed at least in longitudinal portions, is produced by means of U-to-O forming from a planar or flat sheet-metal blank, respectively, by the following method steps:
         providing a sheet-metal blank, and preforming to a preform component that is U-shaped in the cross section;   placing the preform component in a forming tool;   lowering the upper tool, wherein a mandrel is driven into the preform component and comes to bear therein;   wherein by further lowering the upper tool an auxiliary mandrel relative to the mandrel is driven further into the preform component; and   that the preform component by the further lowering of the upper tool by O-forming is formed to the hollow component.       

     In one alternative, the U-shaped preforming can also already be carried out in the forming tool. 
     The method is in particular distinguished in that the auxiliary mandrel during forming is driven in a movement direction into the end side of the hollow component to be produced and in the subsequent opening is also driven out of the hollow component again. Cross-sectional geometries that are mutually dissimilar in longitudinal portions can thus be generated at least in an end portion by way of the mandrel and the auxiliary mandrel. However, the end portion can account for up to 40%, in particular up to 30%, of the entire length of the hollow component. 
     When the forming tool is being opened upon completion of the forming procedure, the auxiliary mandrel is first driven out of the formed hollow component. The mandrel is initially held in the hollow component on account of the relaxation of the spring-elastic actuation means. Upon completion, or else briefly prior to the completion, of the driving-out procedure of the auxiliary mandrel from the hollow component, the mandrel is also driven out of the hollow component by further lifting the upper tool. Canting of the auxiliary mandrel, which at least in part is also driven into the hollow component in a manner transverse to the press stroke direction, is thus avoided. 
     Longitudinal chassis beams, pillars, or roof posts, as well as impact absorbers or crash boxes for motor vehicle bodies can be produced in particular by the forming tool and the production method for a hollow component according to the invention. It would also be conceivable for the forming to be carried out as hot-forming and press-hardening such that a sheet-metal blank, or preform components, respectively, that has/have previously been heated to the austenitizing temperature is/are finally formed and hardened to the hollow component in the forming tool. 
     A further aspect of the device of the object is achieved by a forming tool for the production of a hollow component by sheet-metal forming. To this end, an auxiliary mandrel that is driven into the hollow component to be formed is disposed on the upper tool, wherein the auxiliary mandrel is coupled to the upper tool by way of a spring-elastic actuation means. All features mentioned above also apply to this forming tool, albeit with the difference that a mandrel is not already at least partially driven into the hollow component to be formed in the lowering movement of the upper tool. This aspect of the solution provides that only the auxiliary mandrel is driven into the end side of the hollow component to be formed. To this end, the auxiliary mandrel is likewise at least in part driven into the end side of the hollow component to be formed, prior to the lower dead center of the upper tool being reached. The driving in movement is carried out substantially at an angle in relation to the lowering movement. A further lowering of the upper tool then forms the U-shape of the preform component to an O-shape. The auxiliary mandrel that is driven in at the end side enables a desired cross-sectional contour. A further lowering for forming the U-shape to the O-shape is compensated for by the spring-elastic actuation means between the auxiliary mandrel and the upper tool in such a manner that said actuation means is compressed. 
     An entrainment element that is provided on the upper tool ensures that the auxiliary mandrel, when the upper tool is being opened or lifted, respectively, is driven out in relative manner from the end side of the hollow component that is produced so as to be closed in the cross section. 
     To this end, the auxiliary mandrel is preferably mounted so as to be movable in relative manner in a tool receptacle. The tool receptacle per se is mounted so as to be movable in relative manner on the upper tool. The tool receptacle, when the upper tool is being lowered, preferably comes into contact with, or comes to bear on, a counter bearing, respectively. The spring-elastic actuation means between the tool receptacle and the upper tool is then compressed, this simultaneously leading to a relative movement of the auxiliary mandrel that is mounted in the tool receptacle, such that said auxiliary mandrel is driven into the end side of the hollow component to be formed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The forming tool described here can be carried out according to the method described above, and/or can be combined with the forming tool described at the outset. 
       Further advantages, features, properties and aspects of the present invention are the subject matter of the description hereunder. Preferred variants of design embodiments are explained in the schematic figures. Said figures serve for the ready understanding of the invention. In the figures: 
         FIGS. 1 to 4  show a forming tool according to the invention, and a method sequence for the production of a hollow component; 
         FIGS. 5 a  to 5 c    show various cross-sectional views through a hollow component prior to, during, and after forming; 
         FIG. 6  shows a schematic side view of forming tools for U-to-O forming, having an upper tool and a lower tool; and 
         FIGS. 7 to 10  show an alternative variant of a design embodiment of a forming tool according to the invention, and a method sequence for the production of a hollow component. 
     
    
    
     The same reference signs are used for the same or similar components in the figures, even when a repetition of the description is omitted for the sake of simplicity. 
     DETAILED DESCRIPTION 
       FIG. 1  shows a schematic side view of a forming tool  1  according to the invention. A support unit  3  is suspended from an indicated upper tool  2 . The support unit  3  is configured from a mandrel  4 , from an auxiliary mandrel  5 , and from a respective coupling. The auxiliary mandrel  5 , by way of a coupling mechanism  7 , is coupled so as to be movable in relative manner in an opening  6  of the mandrel  4 . 
     The mandrel  4  per se has an external contour  8  which corresponds to the internal contour  9  of the hollow component  10  to be produced. The hollow component  10  is illustrated by the solid lines  11  in a longitudinal sectional view. The dashed line  12  shows part of the preform component after the U-forming step and prior to the O-forming step. The mandrel  4  on account of a lowering movement of the upper tool  2  in the press stroke direction  13  is driven into an end  14  of the hollow component  10  to be produced in such a manner until the mandrel  4  comes to bear on the internal contour  9  of the hollow component  10 , as is illustrated in  FIG. 2 . 
     A further lowering of the upper tool  2  in the press stroke direction  13  leads to a compression of a spring-elastic actuation means  15  of the mandrel  4 , as is illustrated in  FIG. 3 . The mandrel  4  per se is thus positioned in the hollow component  10  to be produced. 
     However, the auxiliary mandrel  5  by virtue of the coupling mechanism  7  carries out a movement relative to the mandrel  4 . Here, an inclined face  16  is disposed in the mandrel  4 , or in the opening  6  of the mandrel  4 , respectively, wherein the inclined face  16  is oriented at an angle α of in particular more than 1°, preferably more than 10°, in relation to the press stroke direction  13 . The auxiliary mandrel  5  thus is driven in at least partially in a lateral manner, or in a transverse direction  17 , respectively, into the end  14  of the hollow component  10  to be produced. 
     The upper tool  2  is now further lowered in the press stroke direction  13  such that the spring-elastic actuation means  15  of the mandrel  4 , as well as a spring-elastic actuation means  18  of the auxiliary mandrel  5 , are further compressed without the mandrel  4  and the auxiliary mandrel  5  carrying out any further movement. To this end, a detent  19 , or a detent cam, can be provided, for example, such that a further inward pushing movement of the auxiliary mandrel  5  is restricted. 
     The coupling mechanism  7  can be suspended from a repositioning block  20 , for example, which comes to bear on the detent  19 . The actuation means  18  of the auxiliary mandrel  5  can thus also be compressed by a further lowering movement of the upper tool  2  in the press stroke direction  13 , without the auxiliary mandrel  5  carrying out any further relative movement. However, the dashed line  12  is simultaneously formed by a forming surface (not illustrated in more detail) of the upper tool  2  such that the hollow component  10  is formed so as to have a closed cross-sectional geometry. 
     When the forming tool  1  is now opened, the auxiliary mandrel  5  initially carries out a relative movement up to the vertical V, and is thus moved out of the end  14  of the hollow component  10  having the closed cross section such that the mandrel  4  is moved out of the hollow component  10  by further opening in the direction opposite to the press stroke direction  13 . 
     The auxiliary mandrel  5 , or the repositioning block  20  of the auxiliary mandrel  5 , respectively, can furthermore be disposed on a lifting angle  23  such that the relative movement of the auxiliary mandrel  5  can be influenced. In particular, the position of the auxiliary mandrel  5  in relation to the vertical direction, prior to the lowering procedure, consequently the driving-in direction in the transverse direction, can be set by the lifting angle  23 . To this end, the lifting angle  23  per se is in particular configured so as to be settable or adjustable, respectively. The position of the auxiliary mandrel  5  relative to the mandrel  4  is set by setting the lifting angle  23 . 
     Mutually dissimilar cross-sectional geometries are illustrated in  FIGS. 5   a ) to  c ). A planar sheet-metal blank  21  is initially provided according to  FIG. 5   a ), said sheet-metal blank  21  being formed to the preform component  22  according to  FIG. 5   b ). The outer end of each leg of the U-shaped preform component  22  is illustrated here by the dashed line  12 ; however, said preform component  22  is of one piece and a materially integral component part of the sheet-metal blank  21 , said dashed line  12  serving only as a comparison for the dashed lines from  FIGS. 1 to 3 . In a further lowering movement the section line B-B from  FIG. 4  is generated, and the hollow component  10  that is closed in the cross section is produced by O-forming. The cross-sectional geometry can be simultaneously set in a corresponding manner by the auxiliary mandrel  5  that is driven in. 
       FIG. 6  on the left side shows a forming tool  24  for the production of a U-shaped preform component  22 . The forming tool  1  according to the invention for carrying out an O-forming procedure is shown on the right side. First, the U-shaped preform component  22  is produced from the sheet-metal blank  21 , said U-shaped preform component  22  is subsequently placed into the forming tool  1 , and the hollow component  10  that is closed in the cross section is produced by O-forming. The support unit  3 , illustrated in  FIGS. 1 to 4 , having the mandrel  4  and the auxiliary mandrel  5  is suspended from the upper tool  2  of the forming tool  1 . The forming tool  1  furthermore has a lower tool  25 . The hollow component  10  is shaped between the upper tool  2  and the lower tool  25 . 
       FIG. 7  to  FIG. 10  show a forming tool  1  which is used in a preferred refinement or an alternative variant of design embodiment to the forming tool  1  shown in  FIG. 1  to  FIG. 4 . The forming tool  1  according to  FIGS. 7 to 10  herein can be embodied either alone by way of the variant illustrated, in each case relating to the right image plane. Alternatively however, the forming tool  1  can also be used as a forming tool  1  combined with the unit composed of the mandrel  4  and the auxiliary mandrel  5  on the left image plane, and the unit composed of the auxiliary mandrel  26 , the tool receptacle  27  and the counter bearing  28  on the right image plane. Herein, the respective auxiliary mandrel  5 ,  26  is driven into either end side of a hollow component  10  to be formed. 
     Reference is made to the description of the figures pertaining to  FIGS. 1 to 4  for the unit on the left image plane. 
     The unit on the right image plane is described hereunder. The auxiliary mandrel  26  according to the right image side is mounted so as to be movable in relative manner in a tool receptacle  27 . In particular, the auxiliary mandrel  26  by way of a coupling mechanism  7  is mounted on a repositioning block  20 . The repositioning block  20  is coupled to the upper tool  2  by way of a spring-elastic actuation means  18 . 
     The tool receptacle  27  comes to bear on the counter bearing  28  when the upper tool  2  is lowered. A further lowering of the upper tool compresses the spring-elastic actuation means  15  of the tool receptacle  27 . The auxiliary mandrel  26 , moved in relative manner in the tool receptacle  27 , by way of an incline  29  is repositioned at an angle β in relation to the press stroke direction  13 , and is driven into the hollow component  10  to be formed. 
     A lifting angle  23  which is movable relative to the repositioning block  20  is furthermore provided. The lifting angle  23  is preferably coupled directly to the upper tool  2 . When the upper tool  2  is being lifted, after having reached the lower dead center illustrated in  FIG. 10 , the repositioning block  20  of the auxiliary mandrel  26  is thus entrained by the lifting angle  23 , wherein the tool receptacle  27  on account of the compressed spring-elastic actuation element  18  still bears on the counter bearing. On account thereof, the auxiliary mandrel  26  is initially withdrawn from the end  14  of the hollow component  10  formed. Lifting of the tool receptacle  27  is performed only once the auxiliary mandrel  26  has been withdrawn. To this end, the spring-elastic actuation element  15  of the tool receptacle  27  is preferably completely decompressed. 
     The unit that in relation to the image plane is illustrated on the right can be disposed alone in a forming tool  1  for the production of a hollow component  10 . However, the unit can also be combined with the support unit  3  relating to the left image plane, such that driving into the hollow component  10  to be formed is performed from both ends  14 .