Patent Publication Number: US-11389852-B2

Title: Forming tool

Description:
FIELD OF THE INVENTION 
     The invention relates to a forming tool, having a first tool part, which has an upper tool part and a die with a movably used hold-down that is supported against the upper tool part by means of a first pressing means, having a second tool part, which has a lower tool part, a punch that cooperates with the die for the forming, and a movable sheet holder that is supported against the lower tool part by means of a second pressing means, and having a locking device, which is provided between the sheet holder and the hold-down and has at least one spacer element that is supported so that it is able to move from a rest position into a working position as a function of a relative movement, which occurs during the closing of the forming tool, which establishes the distance between the sheet holder and the hold-down during the opening of the forming tool. 
     BACKGROUND OF THE INVENTION 
     In order to lock the hold-down and the sheet holder to each other and to establish their distance from each other during an opening of a forming tool, the prior art has disclosed providing a locking device, which, during the closing of the forming tool, swivels a spacer element embodied in the form of a tilting lever into position between the hold-down and the sheet holder. This locking measure makes it possible to compensate in a particular way for a difference in the pressing force of the two pressing means, for example gas pressure springs—in an attempt to prevent undesirable relative movement between the hold-down and the sheet holder during the opening of the forming tool. In this regard, it is thus possible to reduce a negative impact on the forming quality. This solution of the locking device has the disadvantage, among others, of requiring a comparatively massive embodiment because of the leverage on the tilting lever, which is why such locking devices are unsuitable for tools with that are subjected to comparatively high loads. In addition, such locking devices from the prior art are comparatively complex in their control and structural design—and are therefore cost-intensive to manufacture and maintain. 
     The object of the invention, therefore, based on the forming tool of the above-explained prior art, is to simplify this forming tool with regard to the design complexity and to ensure high durability. In addition, this embodiment should also be suitable for high loads. 
     SUMMARY OF THE INVENTION 
     The invention attains the stated object in that the locking device has at least one wedge drive with a slider and driver, the slider that is equipped with the spacer element being supported so that it is able to move in contact with the driver as a function of the relative movement that occurs between the sheet holder and the upper tool part during the closing of the forming tool in order to move the spacer element into its working position. 
     If the locking device has at least one wedge drive with a slider and driver, then the force-deflecting function that is known from wedge drives can be used to simply actuate the locking device if the slider that is equipped with the spacer element is supported so that it is able to move in contact with the driver as a function of the relative movement that occurs between the sheet holder and the upper tool part during the closing of the forming tool in order to move the spacer element into its working position. In addition, a wedge drive can be embodied as comparatively robust in comparison to an axially supported tilting lever from the prior art, making it possible to transfer even high loads. In this way, it is also possible, for example, to use gas pressure springs as pressing means. On the locking device according to the invention, the wedge drive can firmly establish the distance between the sheet holder and the hold-down. The invention therefore provides a forming tool, which can be used even under high loads and always enables a high forming quality. 
     In general, it should be noted that the forming tool can be a deep-drawing tool for tensile/compressive forming according to DIN 8584. It should also be mentioned that this forming tool can be used to form a sheet, a sheet blank (metal sheet blank), or a tailored blank. 
     In order to reliably establish the distance between the sheet holder and the hold-down, the spacer element—in its working position—can form a stop for the hold-down and/or sheet holder. In addition, this comparatively rugged mechanical embodiment can further improve the durability of the forming tool. 
     If the hold-down has a shoulder that protrudes radially from the die and forms a counterpart stop for the stop of the spacer element, then the design of the forming tool can be simplified further. In addition, this allows the locking device to be provided outside of the tool parts that cooperate in the forming—thus making it possible to achieve a simplification of the design and to avoid possible interfering contours on the forming tool. 
     The loads on the movable tool parts and more specifically on the upper tool part can be reduced if the driver is fastened to the upper tool part and the slider is supported so that it can slide on the sheet holder. 
     If the slider is supported so that it is able to move in contact with the driver in opposition to the action of a first spring, then after the opening of the forming tool, the slider—in a simply designed embodiment—can be guided back into its free rest position. 
     If the spacer element is supported on the slider so that it is able to slide in opposition to the action of a second spring, whose direction of action is oriented opposite from the direction of action of the first spring, then the spacer element can be moved into its working position in a prestressed fashion—which can increase the reliability of the operation of the locking device. In addition, this allows the spacer element to be moved into its working position chronologically offset from the movement of the slider, which can facilitate the adjustment of the wedge guide to the relative movement between the sheet holder and the upper tool part. This makes it possible to further simplify the design of the forming tool. 
     The manipulation of the forming tool—both when loading it with a sheet and when removing the formed sheet/formed blank—remains advantageously unimpaired by the locking device if the slider is supported so that it is able to move in such a way that in the working position of the spacer element, it assumes its position situated closest to the die. To be specific, the slider and spacer element together are removed again from the insertion and removal area between the two tool parts when the forming tool is open, thus preventing the locking device from producing any interfering contours on the forming tool. In addition, this makes it possible to protect the locking device in a simply designed way from damage due to the loading/removal of the sheet—which can contribute to further increasing the durability of the forming tool. 
     Design simplicity in the forming tool can be achieved if the first and second pressing means are embodied in the form of gas pressure springs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject of the invention is shown in greater detail by way of example in the form of an embodiment variant. In the drawings: 
         FIG. 1  shows a cut-away side view of an open forming tool with a sheet blank inserted, 
         FIG. 2  shows the forming tool in a partially closed position, 
         FIG. 3  shows the forming tool in a closed position, and 
         FIG. 4  shows the forming tool as it is being guided back into the open position. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The forming tool  1 , which is depicted as a simply functioning press by way of example in  FIGS. 1 through 4 , is used for deep drawing a sheet, a sheet blank (metal sheet blank), and/or a tailored blank. In  FIG. 1 , this forming tool  1  is in its open position in which the flat blank  2  to be formed has already been inserted. In this open position of the forming tool  1 , a first tool part  3  and a second tool part  4  of the forming tool  1  are visible. 
     An upper tool part  5 , a matrix  6 , and a hold-down  7  belong to the first tool part  3 . The hold-down  7  is supported against the upper tool part  5  by means of a first pressing means  8 , which in the exemplary embodiment is embodied in the form of a first gas pressure spring  108 —see  FIG. 3  with regard to the latter. The matrix  6  is rigidly connected to the upper tool part  5 . 
     A lower tool part  9 , a die  10 , and a sheet holder  11  belong to the second tool part  4 . The sheet holder  11  is supported against the lower tool part  9  by means of a second pressing means  12 , which is embodied in the form of a second gas pressure spring  112 —see  FIG. 3  with regard to the latter. The forming tool  1  according to the invention therefore does not require any bottom air. The die  10  of the second tool part  4  is fastened to the lower tool part  9  and cooperates with the matrix  6  of the first tool part  3  to form the blank  2 . 
     The forming tool  1  also has a locking device  13 , which is provided between the sheet holder  11  and the hold-down  7 . The locking device  13  includes a spacer element  14  with which the distance between the sheet holder  11  and the hold-down  7  can be established. This is necessary for the opening of the forming tool  1  in order, despite possibly different compressive forces of the first and second pressing means  8 ,  12 , to ensure a high quality, e.g. in the formed blank  2 . This locking device  13  is actuated by the closing movement of the forming tool  1 , as shown in  FIG. 2 . When  FIGS. 1 through 4  are considered in combination, it is clear that the spacer element  14  is supported so that it is able to move as a function of a relative movement, which occurs during the closing of the forming tool  1 —specifically from a rest position  15  when the forming tool  1  is open according to  FIG. 1  into a working position  16  according to  FIG. 3 —which establishes the distance between the sheet holder  11  and the hold-down  7  during the opening of the forming tool  1 . 
     According to the invention, this movement of the spacer element  14  is implemented by a wedge drive  17 , which belongs to the locking device  13 . To accomplish this, the wedge drive  17  has a slider  18  and a driver  19 , which form corresponding guide surfaces  20  on the wedge drive  17 . 
     The slider  18  has the spacer element  14  and is supported in sliding fashion—namely on the sheet holder  11  in the exemplary embodiment. As a function of the relative movement that occurs between the sheet holder  11  and the upper tool part  5 , the slider  18 —in contact with the driver  19 , which is fastened to the upper tool part  5  in the exemplary embodiment—is slid and thus moves the spacer element  14  under the hold-down  7 , as a result of which the hold-down  7  strikes the spacer element  14  and thus the sheet holder  11 . For this purpose, the spacer element  14  forms a stop  24  for the hold-down  7 . This establishes the distance between the sheet holder  11  and the hold-down  7 —in the exemplary embodiment, specifically by means of the height of the spacer element  14  and its vertical offset relative to the sheet holder  11 , which vertical offset results from the position of the spacer element  14  on the slider  18 . 
     In this way, a particularly rugged locking device  13  is achieved, which can reliably set the established distance between the sheet holder  11  and the hold-down  7 , even under high loads. The forming tool  1  according to the invention therefore has a particularly high durability. 
     As is also clear from  FIG. 1 , the slider  18  is supported so that it is able to move in contact with the driver in opposition to the action of a first spring  21 , which is embodied in the form of a third gas pressure spring. This spring  21  acts between the slider  18  and the sheet holder  11  and pushes the slider  18  away from the die  6  along its first linear guide  22  on the sheet holder  11 . As a result, in the working position  16  of the spacer element  14 , the slider  18  comes into its position that is situated the closest to the die  6 , which position  23  of the slider is shown in  FIG. 3 . In the rest position  15  of the spacer element  14 , the slider  18  is positioned the farthest from the die  6 . This prevents the occurrence of interfering contours during the loading of the forming tool  1 . 
     It is also clear from  FIG. 1  that the hold-down  7  forms a shoulder  25  that protrudes radially from the die  6  and forms a counterpart stop  26  for the stop  24  of the spacer element  14 . This counterpart stop  26  is provided on the axially protruding section  27  of the radially protruding shoulder  25 , which permits the spacer element  14  to be correspondingly embodied as reduced in height. 
     The spacer element  14  is supported on the slider  18  so that it is able to slide in opposition to the action of a second spring  28 . This spring  21 , which is embodied in the form of a fourth gas pressure spring, acts between the spacer element  14  and the slider  18  and loads the spacer element  14  along its second linear guide  31  on the slider  18  with a direction of action  29  that is oriented opposite from the direction of action  30  of the first spring  21 . As a result, the spacer element  14  can be brought into its working position  16  in a prestressed fashion, which prestressing is visible in  FIG. 2  based on the support of the spacer element  14  in opposition to the action of the second spring  28 . 
       FIGS. 1 through 4  also clearly show that the first and second linear guides  22  and  31  extend parallel to each other. 
     In general, it should be noted—although this is not shown—that the slider  18  is also movably supported on the upper tool part  5  and the driver can be fastened to the sheet holder  11 . In this case, the spacer element then also forms a stop  24  for the sheet holder  11  in order to establish the distance between the sheet holder  11  and the hold-down  7 . It is also conceivable for the spacer element  14  to form a respective stop  24  for the sheet holder  11  and the hold-down  7  — but this is also not shown.