Patent Publication Number: US-2019168477-A1

Title: Setting stamping dies in a press with overhead winching crane

Description:
TECHNICAL FIELD 
     This disclosure relates to a method and apparatus for moving dies into and removing dies from a press with an overhead crane. 
     BACKGROUND 
     Dies are set in a press but must be removed and replaced to service the dies and change over from one die set to another. Dies are placed on a bolster plate that may include a motor drive that is used to move the die into and out of the press. Dies may also be moved with an overhead crane. 
     The orientation of the press and the direction that the die is moved into and out of the press is normally fixed in one reciprocal sliding direction. As shown in  FIG. 1 , a prior art overhead crane  10  is normally provided with a hoist  12  that includes a drum  14  that is rotated about a drum rotation axis by a hoist motor  16  and gear reducer  18 . If the sliding direction is aligned with the drum rotation axis, a “side pull” condition is created that may damage the wire rope  20 . The drum  14  may have helical grooves  22  that the wire rope  20  is wrapped around. In a side pull condition, the wire rope  20  may work against the grooves  22 . Pulling a heavy die  24  with a wire rope  20  in a direction transverse to the grooves  22  may adversely affect the stability of the crane  10  and cause wear of the wire rope  20 . 
     This disclosure is directed to solving the above problems and other problems as summarized below. 
     SUMMARY 
     According to one aspect of this disclosure, an apparatus is disclosed for removing and replacing a die in a press with an overhead crane. The apparatus includes an overhead crane movable in a first direction. A hoist assembly is mounted on the crane to be movable perpendicular to the first direction. The hoist assembly includes a drum rotated about an axis of rotation parallel to the first direction. A press includes a die that is movable into and out of the press reciprocally and perpendicular to the first direction. 
     According to other alternative aspects of this disclosure as it relates to the apparatus, the overhead crane is positioned in the first direction to center the hoist relative to an indicator at the center of the press. A load cell may be operatively connected between the drum and a hook attached to a wire rope to measure the load applied when the die is moved into and out of the press. A guard oriented parallel to and spaced from the crane girder may be attached to a crane girder to restrict the angle of a wire rope relative to the hoist assembly. A sensor system may be disposed in a sheave pocket defined by the hoist assembly for limiting the swing of a wire rope hanging from the hoist apparatus. 
     According to another aspect of this disclosure, a method is disclosed for setting a die in a press. The method includes the steps of positioning an overhead crane to be centered relative to a front opening in a press and securing a sling to the die. The die is then pulled with the sling attached to a wire rope wound on a drum disposed above the press. The wire rope pulls the die in a direction perpendicular to the axis of rotation of the drum. 
     According to other aspects of the method, the die may be removed from the press by pulling the die onto a skid adjacent to the front opening. The die may be inserted into the press by pulling the die off of the skid and into the press with the sling extending through a back opening in the press located on the opposite side of the press from the front opening. 
     The method may also include measuring the load applied to the wire rope with a sensor operatively attached between the wire rope and the drum, and limiting the load to a predetermined level. In addition, the swing angle of the wire rope relative to the drum may be monitored with a sensor system to limit the swing angle of the wire rope to a predetermined degree. 
     The above aspects of this disclosure and other aspects will be described below with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is diagrammatic side elevation view of an overhead crane moving a die with a side pull orientation according to the prior art. 
         FIG. 2  is a diagrammatic front elevation view of an overhead crane moving a die relative to a press according to this disclosure. 
         FIG. 3  is a diagrammatic side elevation view of an overhead crane pulling a die from a press onto a skid according to this disclosure. 
         FIG. 4  is a diagrammatic side elevation view of an overhead crane pulling a die from a skid into the press according to this disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The illustrated embodiments are disclosed with reference to the drawings. However, it is to be understood that the disclosed embodiments are intended to be merely examples that may be embodied in various and alternative forms. The figures are not necessarily to scale and some features may be exaggerated or minimized to show details of particular components. The specific structural and functional details disclosed are not to be interpreted as limiting, but as a representative basis for teaching one skilled in the art how to practice the disclosed concepts. 
     Referring to  FIG. 2 , an improved overhead crane  30  is shown that rides in a first direction A (shown in  FIGS. 3 and 4 ) along a support beam  32  that is part of a building  34 . The overhead crane  30  includes a pair of girders  36  that support a hoist assembly  40 . The hoist assembly  40  moves in a direction B along the girder  36 . 
     The hoist assembly  40  includes a trolley  42  that includes wheels  44 . The trolley  42  moves on the wheels  44  to change the position of the hoist assembly  40  relative to the girders  36 . 
     The hoist assembly  40  includes a drum  36  that is provided with a helical groove  48 . A wire rope  50  is wound on the drum  46  in the helical groove  48 . A hook  42  is connected to the wire rope  50  and a sling  54  is connected to the hoist assembly  40  by the hook  42 . The sling  54  is rigged to a die  56  that is installed in a press  58 . The die  56  is pulled from the press  58  by the sling  54 . The die  56 , when in the press  58 , is attached to a bolster  60 . When the die  56  is removed from the press  58 , the die slides onto a skid  62  that is located adjacent to the bolster  60 . The die  58  is removed from the press  58 , through a front die opening  64 . The die  56  is set in the press  58  by pulling the die  56  with the sling  54  being routed through a rear die opening  66  to the die  56  on the skid  62 . A press cable guard  68  is provided above the front die opening  64  and also above the rear die opening  66 . The press cable guard  68  protects the press  58  from the sling  54 . 
     A press centerline indicator  70  is provided on the press  58  and a wire rope  50  and hook  52  are positioned in line with the press centerline indicator by moving hoist assembly  40  with the trolley  42 . The hoist assembly  40  should be centered relative to the press  58  to remove or set the die  56  in the press  58 . A girder guard  72  is provided on the girder  36  to positively limit the angle of the wire rope relative to the vertical. The girder guard  72  is located to limit the angle of the wire rope  50  relative to vertical to less than 25 degrees. The design angle relative vertical is 20 degrees. The girder guard  72  also protects the girder from being contacted by the wire rope  50 . A sensor may be provided on the girder guard  70  or inside a sheave pocket  78 . 
     A load cell  76  is shown in  FIG. 2  to be either assembled to the drum  46  or operatively connected between the wire rope  50  and the drum  46 . Alternatively, the sensor may be incorporated in the hook  52  or the hook mounting structure. A load cell is monitored by a controller to limit the pulling load for a crane. For example, a 50-ton crane may have a pulling load limit of between 29,000 and 32,000 pounds, or approximately 60% of the rated load capacity. 
     The drum has an axis of rotation that is parallel to the direction B as shown in  FIG. 2 . The axis of rotation of the drum  50  is perpendicular to the direction A shown in  FIGS. 3 and 4  and is also parallel to the direction that the girders  36  move along the support beam  32 . The axis of rotation of the drum  50  is oriented to pull the die in a direction tangential to the helical groove  48  with the wire rope  50 . This orientation is referred to as a straight pull as the drum  46  is oriented perpendicular to the orientation of the drum  14  shown in  FIG. 1  that pulls the die in a side pull condition. 
     Operation of the improved overhead crane  30  is described with reference to  FIGS. 3 and 4 . A die is pulled as shown in  FIG. 3  through the front die opening  64  from the bolster  60  to the skid  62 . The sling  54  is attached to the die  56  to pull the die  56 . The wire rope  50  and hook  52  are attached to the sling  54 . The hoist assembly  40  is aligned with the centerline indicator  70  (as shown in  FIG. 2 ). The hoist assembly  40  retracts the wire rope  50  by winding the wire rope  50  on the drum  46  with the wire rope  50  being received in the helical groove  48 . The die  56  is moved in the direction of the arrow shown in  FIG. 3  through the front opening  64  and on to the skid  62 . The angle of the wire rope is limited by the girder guard  72  to a maximum angular orientation relative to the vertical direction. The load cell  76  monitors the load as the die  56  is pulled from bolster  60  to be sure that the capacity of the overhead crane  30 , the wire rope  40 , or sling  54  is not exceeded. The angle that the wire rope is pulled may be limited by a sensor system  74  located within the sheave pocket  78  or on the girder guard  72 . 
     Referring to  FIG. 4 , the hoist assembly  40  is shown in position to set the die  56  in the press  58 . The sling  54  is connected to the die  56  through the rear die opening  66 . The sling  54  is routed under the press cable guard  68 . The sling  54  is then pulled with the hook  52  and wire rope  50  by winding the wire rope  50  on the drum  46 . The sling  54  slides the die  56  from the skid  62  to the bolster  60 . As previously described with reference to  FIG. 3 , the hoist assembly  40  must be centered with the press centerline indicator  70  (shown in  FIG. 2 ) and the angle of the sling  54  or wire rope  50  is limited either by the girder guard  72  or by the sensor system  74 . Once again, the load cell  76  (shown in  FIG. 2 ) is used to monitor to the tension applied by the hoist assembly to the wire rope  50 . 
     The embodiments described above are specific examples that do not describe all possible forms of the disclosure. The features of the illustrated embodiments may be combined to form further embodiments of the disclosed concepts. The words used in the specification are words of description rather than limitation. The scope of the following claims is broader than the specifically disclosed embodiments and also includes modifications of the illustrated embodiments.