Abstract:
A method and apparatus for forming metal parts in a progressive forming machine wherein one of the opposed tools on a ram and die breast is spring biased to operatively close the tools before the ram reaches front dead center thereby allowing material of the blank to extrude sideways through an aperture formed by both of the opposed tools in the final forward movement of the ram.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to forming techniques used in progressive metal formers. 
       PRIOR ART 
       [0002]    Forging or forming machines have long been used to shape cylindrical blanks into more complex shapes. A common forming method involves upsetting or coning dies in which a blank is axially compressed to expand it radially. There are limits to the amount of radial expansion that can be obtained in a single forming blow without unacceptable buckling of the blank. Consequently, in a progressive former, several stations may be required to produce a desired radially extending shape. On the other hand, some parts may require a reduction in area using an extrusion technique but, again, such processes have physical limits, as recognized in the industry. Still further, to form some irregularly shaped parts using customary processes, it can be necessary to trim a large volume of material from the blank so that the resulting scrap adds significant costs to a process. 
       SUMMARY OF THE INVENTION 
       [0003]    The invention involves lateral extrusion of a blank in a workstation in a progressive forming machine. The invention allows various metal parts to be shaped in fewer stations than has been required in the past, can produce parts with lateral extensions exhibiting a high reduction in area and/or a finished thickness and, can reduce a percentage of scrap by eliminating or reducing the amount of material required to be trimmed from asymmetric and/or accircular parts. 
         [0004]    The invention employs a spring biased slidable tool. During sliding movement, a tool cooperating with an opposed tool is arranged to form a sideways extrusion. The spring biased sliding tool allows the final part of a ram stroke to displace blank material through a lateral aperture bounded by the sliding tool and the opposed tool. The spring is arranged to hold the tools in fixed relation during this blank extrusion step against forces developed in the blank. 
         [0005]    The sliding tool can be mounted on either the ram or the die breast of the progressive forming machine. The spring allows the slidable tool to recede on the part of the machine on which it is mounted while the ram is approaching front dead center (FDC) and displacing blank material through the lateral extrusion aperture. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a diagrammatic isometric view of a progressive forming machine used to practice the invention; 
           [0007]      FIGS. 2-5  show a progression of a blank being formed with the invention; 
           [0008]      FIG. 6  is a somewhat simplified enlarged fragmentary sectional view of the tooling and blank prior to forming at the workstation of  FIG. 7 ; and 
           [0009]      FIG. 7  is a side view of a work station of the machine of  FIG. 1  at which steps of the invention are performed. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0010]      FIG. 1  schematically illustrates a progressive forming machine  10 . Rotation of a crankshaft  11  reciprocates a ram or slide  12  towards and away from a die breast or bolster  13 . The machine  10  is shown with uniformly horizontally spaced cutoff station  14  and three workstations  16 - 18 . The invention, as will be understood with those familiar in the art, can be practiced with machines of a different number of stations. In a customary manner, blanks are cut from round wire stock  19  by a shear at the cutoff station  14  and then are transferred by a mechanism  21  to successive stations  16 - 18  in timed relation to reciprocation of the ram. 
         [0011]      FIGS. 2-5  illustrate various stages of the forming of a workpiece in an application of the invention. An initial blank  26  produced at the cutoff station  14  is shown in  FIG. 2 . Typically, the generally cylindrical blank  26  has irregular ends, a result of the shearing process at the cutoff station  14 . The blank  26  is struck in a die and punch at the first station  16  to square up its ends shown in  FIGS. 3A ,  3 B and thereby improve the quality and uniformity of a finished part. 
         [0012]    At the second workstation  17 , the blank  26  is uniquely shaped with a sideways or lateral extrusion step shown in  FIGS. 4A ,  4 B in accordance with the invention. In the exemplary part being illustrated, the blank  26  is also backward extruded at this second workstation  17 . In the third station  18 , the exemplary part or workpiece is finished by punching a hole in its laterally extruded section as shown in  FIG. 5A , B. 
         [0013]    The cutoff, square-up and hole punching operations and tooling to accomplish the same at the respective cutoff, first and third stations are generally conventional and need no further explanation for an understanding of the invention. 
         [0014]      FIG. 6  illustrates tooling comprising a tool or die  31  and tool or punch assembly  32  at the second station  17  on an enlarged scale. The tooling  31 ,  32  is shown in a position where the blank  26 , received from the first workstation  16  where it was squared up, is just about to be reshaped as the ram  12  approaches FDC. 
         [0015]      FIG. 7  illustrates the tooling  31 ,  32  at the second station  17  in greater detail with the ram  12  at FDC and the blank  26  as it is fully shaped at this stage in the progression as is also shown at  FIG. 4A , B. The die  31  mounted on the die breast, generally indicated at  13  in  FIG. 7 , in the illustrated case presents a flat surface  36 , transverse to the horizontal axis of ram motion, against which the blank  26  is formed. The tool or punch assembly  32  mounted on the ram  12  includes an insert  37  having an internal cavity  38  for shaping the blank  26 , a punch pin  39  and a sleeve  41  all carried in a case  42 . The case  42  is slidably mounted for limited axial movement relative to the ram  12  in a holder  43  fixed to the ram. The insert  37  is resiliently biased through its supporting case  42  towards the die  31  by a high pressure lever  46  such as disclosed in U.S. Pat. No. 8,024,952. The lever  46 , carried on and pivotal on the ram  12 , multiplies a force developed by a gas spring  47  stationarily mounted on the frame of the machine adjacent the die breast  13 . The gas spring  47  is effective on the lever  46  when the ram  12  approaches FDC. 
         [0016]    The sequence of movement of the tooling at the second station  17  follows the transfer of the blank  26  to this station (and the simultaneous transfer of the previous blank to the succeeding station  18 ). With the blank  26  transferred, the ram  12  advances towards the die breast  13  carrying the tool assembly  32  biased by the spring  47  and lever  46  so that these tool parts lead the ram. Prior to FDC, the face of the tool assembly insert  37  engages the die  31 . Together the cavity of the insert  37  and die  31  define the shape of the blank  26  to be produced at this station  17 . The blank shape is depicted in  FIGS. 4A and 4B . The majority of the external shaped surfaces of the blank  26  formed at this station  17  is determined by internal surfaces of the cavity  38  in the tool insert  37 . 
         [0017]    The cavity  38  has a cylindrical bore  51  of a diameter sufficiently large to receive the blank  26  shaped at the first station  16 . The face of the tool insert  37  mates with the die  31  by fitting tightly against the flat face of the die. At one side of the bore  51  is a rectangular aperture having a boundary partially formed by the face of the die  31 . With the faces of the tool insert  37  and die  31  held tightly together by the high pressure lever  46  to prevent escape of material of the blank  26  at their interface, the ram  12  advances towards the die breast  13  driving the punch pin  39  into the blank. 
         [0018]    Initially, with the punch pin  39  and sleeve  41  moving in unison with the ram  12 , the blank  26  back extrudes to fill a space  54  ( FIG. 6 ) behind the lead end of the punch pin and in front of the sleeve  41 . Small vents, not shown, run longitudinally along the outer surface of the sleeve  41  to release air and lubricant otherwise trapped in this area. When the space  54  behind the front face of the punch pin  39  is filled, the blank material is extruded laterally out of the aperture  52  defined between the punch insert  37  and die  31 . The space  54  around the punch pin  39  is filled before the lateral extrusion begins since this backwards extrusion requires less pressure on the material than does the extrusion through the lateral or sideways aperture  52 . The blank material continues to extrude to form a lateral extension or wing  56  until the ram  12  reaches FDC. 
         [0019]    Preferably, the aperture  52  is slightly smaller in cross-section than a space  57  that receives and generally confines the extruded material. Stated otherwise, the receiving space  57  is provided with a slight dimensional relief, i.e. made slightly larger in cross-section than the aperture  52 . This relief reduces resistance to flow of blank material through the space  57 . An end of the receiving space or channel  57  can be closed (apart from suitable air and lubricant venting) to shape the extremity of the extension  56  or can be open. The receiving space  57  is primarily formed in the insert  37  but has a part of its boundary or side formed by the die  31 . 
         [0020]    The ram  12  retracts; when the retraction exceeds the slide movement of the punch assembly  32 , the punch assembly carried by the ram  12  retreats from the die  31  to eventually release the blank  26  for transfer to the third station  18 . The punch assembly sleeve  41 , in the illustrated arrangement, can be used to hold the blank  26  in place on the flat face of the die  31  until it is under control of the transfer mechanism  21 . At the third station  18 , the lateral extension  56  can be further shaped;  FIGS. 5A and 5B  show the result of being worked by a punch that has formed a hole  58 . Other work such as trimming, bending, twisting, cupping, shaping can be done to the blank extension  56 , and/or the remainder of the blank  26  at this third station  18  or any additional work station. 
         [0021]    The extrusion process is distinguished over a traditional upset or coning operation in that the material of a blank being forced into the extruded shape including that contacting, but slipping over, the confining and shaping die and punch tools is all displaced by succeeding increments of blank material. In an upset or coning, the blank material at the confining punch and die surfaces does not slip across these surfaces. 
         [0022]    The lateral or sideways extrusion technique of the invention represented by the foregoing example, can offer many benefits over traditional forming steps. An extruded detail can, as illustrated, be limited to a fraction of the circumference of the blank thereby reducing or eliminating the need to trim material from a workpiece that is asymmetrical or accircular in finish form. The aperture  52  can be dimensioned to produce a lateral extension  56  with a finished thickness or cross section. A workpiece or part can be produced with more than one lateral extension at multiple locations around the circumference in a single forming station. The aperture can extend through  360  degrees around the axis of the original blank to create a full peripheral rim or flange. The die face can have formations other than the disclosed flat to shape a part as long as the punch assembly and die cooperate to form the extrusion orifice and receiving space analogous to the space  57  and allow the extruded extension to be released after it is formed. The spring biased sliding tool can be mounted on the die breast or bolster  13  rather than in the illustrated arrangement where it is mounted on the ram  12 . 
         [0023]    It should be evident that this disclosure is by way of example and that various changes may be made by adding, modifying or eliminating details without departing from the fair scope of the teaching contained in this disclosure. The invention is therefore not limited to particular details of this disclosure except to the extent that the following claims are necessarily so limited.