Abstract:
A stock ejector assembly and method for metal forming dies includes a stock ejector with a large spring and a ring-style stripper. The ring-style stripper provides a larger surface area for contacting the stock. The large compression spring is preloaded and when a load is applied, the stripper retracts and the spring pressure increases. When the dies separate, the stock ejector pushes the part off flat surfaces, separating surfaces sealed by adhesion, including, but not limited to, oil or lubricant adhesion.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    Applicants hereby claim the priority benefits under the provisions of 35 U.S.C. §119, basing said claim of priority on related U.S. Provisional Application No. 62/075,966 filed Nov. 6, 2014. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to metal forming dies and the like, and in particular to a stock ejector assembly and associated method incorporating a unique stock ejector assembly. 
         [0003]    Metal forming dies, such as stamping dies and the like, are well known in the art. 
         [0004]    Progressive metal forming dies are unique, very sophisticated mechanisms which have multiple stations or progressions that are aligned longitudinally, and are designed to perform a specified operation at each station in a predetermined sequence to create a finished metal part. Progressive stamping dies are capable of forming complex metal parts at very high speeds, so as to minimize manufacturing costs. 
         [0005]    Heretofore, the dies used in metal forming presses have typically been individually designed, one-of-a-kind assemblies for a particular part, with each of the various components being handcrafted and custom mounted or fitted in an associated die set, which is in turn positioned in a stamping press. Not only are the punches and the other forming tools in the die set individually designed and constructed, but the other parts of the die set, such as stock lifters, guides, end caps and keepers, cam returns, etc., are also custom designed, and installed in the die set. Current die making processes require carefully machined precision holes and recesses in the die set for mounting the individual components, such that the same are quite labor intensive and require substantial lead time to make, test, and set up in a stamping press. Consequently, such metal forming dies are very expensive to design, manufacture, and repair or modify. 
         [0006]    A liquid, such as a lubricant, mill oil, or water may be used on the stock and one or more of the die parts to decrease the wear on the die parts and/or damage to the stock. When a liquid is used on the stock or upper and/or lower die parts of a metal forming die, the stock has a tendency to stick to the die parts. Thus, something must be done to break the lubricant tension/adhesion on the stock so that it can be removed from that portion of the die. In addition, tension/adhesion can also exist between the stock and flat surfaces on the dies whether or not a liquid is used with the stock and/or dies. Such adhesion between flat surfaces also requires the breaking of the developed tension. One way of breaking the tension is to use a threaded spring plunger. This is a self-contained assembly that includes a very small diameter spring which is prone to fail quickly due to its size. When the threaded spring plunger fails, it is a hassle for stampers as they have to continuously replace the threaded spring plungers. Another problem is that the threaded spring plungers typically have a pointed tip that can leave a mark on the stock if the spring pressure is too great. 
         [0007]      FIGS. 15-18  illustrate two well-known prior art assemblies. For example,  FIG. 15  illustrates the upper die member  72  of a die set with spring plungers  140 . The spring plunger  140  includes a spring portion and a tip  146 . The spring is received in an aperture  142  in the die member  72  such that the threaded surface  144  of the aperture  142  corresponds to the contours of the spring plunger  140 . Such spring plungers  140  typically fail due to the small spring, which effects the overall lifespan of the spring plunger. The tip  146  has a small contact point that can mark the stock material. In addition, due to the small surface area of the tip  146 , the spring plunger  140  can have trouble breaking the lubricant tension/adhesion on the stock strip. As illustrated in  FIG. 15 , the insertion of spring plunger  140  into die member  72  can be a difficult assembly, as the aperture  142  needs to be threaded  144  to correspond to the shape of the spring plunger  140 . 
         [0008]    Another example of the prior art includes ejector pin assemblies  148 , as shown in  FIGS. 17 and 18 . The ejector pins  148  include a pin  151  with a tip  152  that extends through a hole  157  in the bottom surface  161  of the die member  72 . Another hole  158  includes a threaded portion  156  that mates with a set screw  154  of the ejector assembly  148 . A spring  150  is received in hole  158  in between the set screw  154  and the head  160  of the pin  151 . The spring  150  pushes the head  160  of the pin  151  such that the tip  152  of the pin  151  can extend from the underside  161  of the die member  72 . Use of the ejector pins  148  requires costly machining as the die member  72  must receive several small parts. Small holes must be drilled for the pin  151  of the ejector pin assembly  148 . The die member  72  has to be counter-bored and tapped for the set screw  154 . In addition, the components of the ejector pin assemblies  148  are small components and require an immense amount of time to assemble. 
         [0009]    The need for an improved stock ejector thus stems from the issues that metal stamping producers and die shops have long had when creating an “oil breaker” setup in their dies. The improved stock ejector addresses two main items that are currently problematic: The first is that it utilizes a large spring, which provides a much longer product life than a traditional spring plunger. The large spring is on the “exterior” of the assembly and the other construction methods are internal. This design provides the ability for a large spring to be used while keeping the overall footprint of the assembly as small as possible. The second is the increase in surface area that makes contact with the stock. Typical plunger “point” style on spring plungers have very little surface area, and most commonly used are the points that are rounded/spherical. This provides very little contact with the stock and it can leave a “mark” if the spring pressure compared to the contact surface area on the stock are not proper. The improved stock ejector utilizes a “ring” style stripper, which provides more overall surface area in contact with the stock. This amount of contact surface area prevents the stock from being “marked” but is also not so high that the stock wants to stick to it. 
         [0010]    Thus, a product that solves these problems would be advantageous and is described herein. 
       SUMMARY OF THE INVENTION 
       [0011]    One aspect of the present invention is a stock ejector assembly that utilizes a large spring, thereby providing a longer product life. The spring is on the “exterior” of the assembly, allowing for a large spring to be used while keeping the overall footprint of the assembly as small as possible. Another aspect of the present invention is to provide a stock ejector assembly that has an increased surface area that makes contact with the stock. Thus, the present invention includes a “ring” style stripper which provides a larger surface area to contact the stock. The increased contact surface area prevents the stock from being “marked” and prevents the stock from sticking to the ejector. 
         [0012]    Yet another aspect of the present invention is a multi-station progressive metal forming die having at least two, mutually converging and diverging die members between which an elongate stock strip is shifted longitudinally to form parts from the stock strip, along with an improved stock ejector assembly. The stock ejector assembly includes a stock ejector body with an outer end portion oriented toward the stock strip, an inner end portion oriented away from the stock strip, and a medial portion between the outer end portion and the inner end portion. The outer end portion of the stock ejector body includes a shoulder with an outer end surface and an inner end surface. The inner end portion of the stock ejector body includes a threaded shank portion that secures the assembly to one of the die members. The medial portion of stock ejector assembly includes a shoulder with an outer end surface and an inner end surface. The stock ejector assembly includes a stripper with an outer end portion arranged toward the stock strip and an inner end portion oriented away from the stock strip. The outer end portion of the stripper includes an aperture with a first diameter, and the inner end portion includes an aperture with a second diameter. The second diameter is less than the first diameter of the outer end portion, forming a generally annular shoulder that engages the inner end surface of the shoulder of the outer end portion of the stock ejector body. The stock ejector assembly includes a spring member having a generally hollow interior that is received over the stock ejector body, an outer end oriented toward the stock strip that engages the inner end portion of the stripper, and an opposite inner end oriented away from the stock strip that engages the outer end surface of the shoulder of the medial portion of the stock ejector body. The stock ejector assembly optionally includes a spacer having a generally hollow interior that is received over a portion of the threaded shank portion of the inner end portion of the stock ejector body. The space has an outer end surface oriented toward the stock strip that engages the inner end surface of the shoulder of the medial portion of the stock ejector body, and an inner end surface oriented away from the stock strip. 
         [0013]    Yet another aspect of the present invention is a stock ejector assembly for metal forming dies that have least two mutually converging and diverging die members to form parts from the stock strip. The stock ejector assembly includes a stock ejector body with an outer end portion oriented toward the stock strip, an inner end portion oriented away from the stock strip, and a medial portion between the outer end portion and the inner end portion. The outer end portion of the stock ejector body includes a shoulder with an outer end surface and an inner end surface. The inner end portion of the stock ejector body includes a threaded shank portion that secures the assembly to one of the die members. The medial portion of stock ejector assembly includes a shoulder with an outer end surface and an inner end surface. The stock ejector assembly includes a stripper with an outer end portion arranged toward the stock strip and an inner end portion oriented away from the stock strip. The outer end portion of the stripper includes an aperture with a first diameter, and the inner end portion includes an aperture with a second diameter. The second diameter is less than the first diameter of the outer end portion, forming a generally annular shoulder that engages the inner end surface of the shoulder of the outer end portion of the stock ejector body. The stock ejector assembly includes a spring member having a generally hollow interior that is received over the stock ejector body, an outer end oriented toward the stock strip that engages the inner end portion of the stripper, and an opposite inner end oriented away from the stock strip that engages the outer end surface of the shoulder of the medial portion of the stock ejector body. The stock ejector assembly optionally includes a spacer having a generally hollow interior that is received over a portion of the threaded shank portion of the inner end portion of the stock ejector body. The space has an outer end surface oriented toward the stock strip that engages the inner end surface of the shoulder of the medial portion of the stock ejector body, and an inner end surface oriented away from the stock strip. 
         [0014]    Yet another aspect of the present invention is a method for making a multi-station progressive metal forming die having at least two mutually converging and diverging die members between which an elongate stock strip is shifted longitudinally to form parts from the stock strip, with the improvement of at least one stock ejector assembly. The method includes forming a stock ejector body with an outer end portion oriented toward the stock strip, an inner end portion oriented away from the stock strip, and a medial portion between the outer end portion and the inner end portion. The method includes forming said outer end portion of the stock ejector body to have a shoulder with an outer end surface and an inner end surface. The method includes forming said inner end portion of the stock ejector body to have a threaded shank portion that secures the assembly to one of the die members. The method includes forming the medial portion of the stock ejector body to have a shoulder with an outer end surface and an inner end surface. The method includes forming a stripper with an outer end portion arranged toward the stock strip and an inner end portion oriented away from the stock strip. The method includes forming the outer end portion to include an aperture with a first diameter and forming said inner end portion to include an aperture with a second diameter. The second diameter of the inner end portion is less than the first diameter of the outer end portion, forming a generally annular shoulder that engages the inner end surface of the shoulder of the outer end portion of the stock ejector body. The method includes selecting a spring member with a generally hollow interior, an outer end oriented toward the stock strip, and an opposite inner end oriented away from the stock strip. The method includes inserting the spring member over the outer end portion of the stock ejector body with the inner end of the spring member engaging the outer end surface of the shoulder of the medial portion of the stock ejector body. The method includes inserting the stripper over the outer end portion of the stock ejector body. The method includes inserting a tool into the stripper and moving the tool toward the inner end portion of the stock ejector body, thereby compressing the stock ejector assembly such that the inner end portion of the stripper moves past the shoulder of the outer end portion of the stock ejector body. The method includes removing the tool to permit the spring to push the stripper toward the outer end of the stock ejector body, allowing the annular shoulder of the stripper to engage the inner end surface of the shoulder of the outer end portion of the stock ejector body. The method optionally includes selecting a spacer that is placed over a portion of the inner end portion of the stock ejector body. The method includes securing the stock ejector assembly to one die member. 
         [0015]    These and other advantages of the invention will be further understood and appreciated by those skilled in the art by reference to the following written description, claims, and appended drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a perspective view of the stock ejector assembly embodying the present invention. 
           [0017]      FIG. 2  is an exploded perspective view of the stock ejector assembly shown in  FIG. 1 . 
           [0018]      FIG. 3  is a vertical cross-sectional view of the stock ejector assembly shown in  FIG. 1 . 
           [0019]      FIG. 4  is a vertical cross-sectional view of the stock ejector body. 
           [0020]      FIG. 5  is a vertical cross-sectional view of a spring and stripper being loaded on the stock ejector body with a forming tool. 
           [0021]      FIG. 6  is a vertical cross-sectional view of the forming tool being inserted. 
           [0022]      FIG. 7  is a vertical cross-sectional view of the forming tool with an arrow showing the direction of the forming tool to compress the partial stock ejector assembly while flaring the stock ejector body. 
           [0023]      FIG. 8  is a vertical cross-sectional view of the partial stock ejector assembly with the forming tool removed. 
           [0024]      FIG. 9  is a perspective view of the stock ejector assembly after the spacer is added. 
           [0025]      FIG. 10  is a perspective view of the stock ejector assembly being mounted in a die member with a standard hex tool. 
           [0026]      FIG. 11  is a perspective view of the stock ejector assembly installed in a lower die member showing the stock being pressed against the lower die member. 
           [0027]      FIG. 12  is a perspective view of the stock ejector assembly installed in a lower die member as the stock is being separated from the lower die member. 
           [0028]      FIG. 13  is a vertical cross-sectional view of the stock ejector assembly with arrows showing the preloaded spring. 
           [0029]      FIG. 14  is a vertical cross-sectional view of the stock ejector assembly with arrows showing the distance of travel T when a force F is applied. 
           [0030]      FIG. 15  is a schematic cross-sectional view of prior art spring plungers installed in a die member. 
           [0031]      FIG. 16  is a perspective view of a prior art spring plunger. 
           [0032]      FIG. 17  is a schematic cross-sectional view of prior art ejector pin assemblies in a die member. 
           [0033]      FIG. 18  is a perspective view of a prior art ejector pin assembly. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0034]    For purposes of description herein, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” and derivatives thereof shall relate to the invention as oriented in the attached drawings. However, it is to be understood that the invention may assume various alternative orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in  FIGS. 1-14 , and described in the following specification, are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. 
         [0035]    The reference numeral  2  ( FIGS. 1-14 ) generally designates a stock ejector assembly embodying an aspect of the present invention. As shown in  FIGS. 11-14 , the stock ejector assembly  2  is particularly adapted for use in conjunction with a multi-stage progressive metal forming die  70  having at least two mutually converging and diverging die members  72  and  74 , between which an elongated stock strip  30  is shifted longitudinally form parts from the stock strip. 
         [0036]    The stock ejector assembly  2  includes a stock ejector body  4 , a stripper  8 , a fastener  54 , and optionally a spacer  10 , as shown in  FIGS. 1-3 . 
         [0037]    The stock ejector body  4  includes an outer end portion  82 , oriented toward the stock strip  30 , an inner end portion  80 , and a medial portion  84 , as shown in  FIGS. 3 and 12 . The inner end portion  80  has a threaded portion  92 . The threaded portion  92  can be a threaded shank as shown in the Figures. The outer end portion  82  has a shoulder  98  with an outer end surface  97  and an inner end surface  99 , as shown in  FIG. 2 . The medial portion  84  has a shoulder  86  with an outer end surface  88  and an inner end surface  90 . The stock ejector body  4  also has a spring receiving portion  95  that extends to the inner end surface  99  of the shoulder  98 . The spring receiving portion  95  can include a taper  91 , as shown in  FIG. 2 . 
         [0038]    The stripper  8  has an outer end portion  20  oriented toward the stock strip  30 , an oppositely disposed inner end portion  22  oriented away from the stock strip  30  with a hollow interior  21  extending therebetween. The outer end portion  20  of the stripper  8  is generally ring-shaped, as shown in  FIGS. 1-2 and 9 . The outer end  20  engages the stock strip  30 , as shown in  FIGS. 11-12 . 
         [0039]    As illustrated in  FIG. 3 , stripper  8  has an internal generally annular shoulder  24  that is formed by the difference in the inner diameter  100  of the outer end  20  and the inner diameter  102  of the inner end  22  of the stripper  8 . 
         [0040]    The spring member  32  includes a hollow interior  34 , as shown in  FIG. 2 . The spring member  32  also has an outer end  36  that is oriented toward the stock strip  30  and an inner end  38  that is oriented away from the stock strip  30 , as shown in  FIG. 12 . 
         [0041]    The stock ejector assembly  2  also includes an optional space  10  with an outer end surface  14  and an inner end surface  16 . The spacer  10  has a hollow interior  15  that is received over the threaded shank  92  of the stock ejector body  4  when the stock ejector assembly  2  is completed. 
         [0042]    As best illustrated in  FIGS. 4-9 , the stock ejector assembly  2  is assembled by use of a forming tool  12 . As shown in  FIG. 5 , the spring  32  is loaded on the stock ejector body  2  such that the spring  32  surrounds the spring retaining portion  95  of the stock ejector body  2 . As shown in  FIGS. 5-7 , the forming tool  12  is used to compress the partial stock ejector assembly  2  causing the outer end  82  of the stock ejector body  2  to flare. This allows the stripper  8  to be assembled onto the stock ejector body  2  such that the inner shoulder  25  of the stripper  8  moves past the shoulder  98  of the stock ejector body  2 . Once the forming tool  12  is removed and the spring  32  becomes uncompressed, the inner end surface  25  of the shoulder  24  of the stripper  8  will engage the inner end surface  99  of the shoulder  98  of the stock ejector body  2 , as shown in  FIG. 8 . The optimal spacer  10  can then be added over the threaded portion  92  of the stock ejector body  2 , as shown in  FIG. 9 . 
         [0043]    When the stock ejector assembly  2  is fully assembled, the spring member  32  is preloaded, as shown by the arrows P in  FIG. 13 . When a load is applied, as shown by the arrow F in  FIG. 14 , the stripper  8  retracts and the pressure in the spring member  32  increases. The stripper  8  travels a distance T, as the spring member  32  is compressed due to the load. 
         [0044]    The stock ejector assembly  2  can be assembled to one of the die members  72 ,  74  of the metal forming die  70 . As illustrated in  FIGS. 11-12 , an aperture  64  can be formed in the lower die member  74  to receive the stock ejector assembly  2 . The inner end surface  16  of the spacer  10  contacts a surface  65  of the aperture  64  when the stock ejector assembly  2  is inserted into the aperture  64 . A threaded fastener aperture  66  is also machined, tapped, or otherwise formed in the die member  74 . The threaded shank  92  of the stock ejector body  4  is used to secure the stock ejector assembly  2  to the die member  74  as illustrated in  FIGS. 11 and 12 . 
         [0045]    As illustrated in  FIG. 10 , a standard hex tool  60  can be used to install the stock ejector assembly  2  into the die member  74  or into a window  46  that is attached to one of the die members  72 ,  74 . Also as illustrated in  FIG. 10 , a window mount  46  may be used to facilitate the installation of the stock ejector assembly  2  into the die member  74 . The window mount  46  can have an aperture  40  with a threaded portion  44  in a tapered portion of the aperture  40 . The threaded shank  92  of the stock ejector assembly  2  is received in threaded portion  44 . When the stock assembly  2  is installed, the inner end surface  16  of the spacer  10  is received on an internal shoulder  43  within aperture  40  when the stock ejector  2  assembly is fully installed in the window mount  46 . The window mount  46  may be fastened to the die member by the use of fasteners  49  that are received in aperture  48  of the widow mount. A surface on the head of the fastener  49  will engage the shoulder  50  of aperture  48  when the threaded portion of the fastener  49  extends through the lower portion  51  of the aperture  48  and into a threaded hole in the die members  72 ,  74 . 
         [0046]    The stock strip  30  is received between the die members  72  and  74  when the die members  72 ,  74 , converge, as illustrated in  FIG. 11 . When the die members converge, the spring member  32  is compressed. As shown in  FIG. 12 , when the die members  72 ,  74  diverge, the spring member  32  decompresses and pushes the stock strip  30  off of the surface of the die member  72 . When the stock ejector assembly  2  is installed on the lower die member  74 , the stock ejector assembly  2  not only breaks the oil or lubricant adhesion between the die member  74  and the stock strip  30 , it also lifts the stock strip  30  for progression within a multi-station progressive metal forming die and/or removal of the finished part form the die assembly. 
         [0047]    The term “die member” as used herein refers to any portion of a metal forming die or die set, including, but not limited to, an upper die member or a die shoe, a lower die member or a die shoe, and other die components, whether stationary or reciprocating, including a reciprocating pressure pad, and the like. In the illustrated examples, the stock ejector assembly  2  can be mounted in any die member. The stock ejector assembly  2  can be mounted in other types of die members and/or components and in a variety of different positions and orientations, as will be appreciated by those skilled in the art. In addition, the stock ejector assembly  2  can be used in a single stage die assembly. 
         [0048]    Stock ejector assembly  2  has an uncomplicated construction with relatively few components and is therefore quite durable and economical to manufacture. Multiple components of the stock ejector assembly  2  may be formed from a single piece of rigid material. For example, the stripper  8 , stock ejector body  2 , and optional spacer  10  may have a one-piece construction made from a solid bar of material, such as steel. The fasteners and optional window mount  46  attachment of the stock ejector assembly  2  to an associated die members  72 ,  74  provides quick and easy installation and removal of the stock ejector assembly  2 . The spring member  32  and the stock ejector assembly  2  are backed up or axially supported by the die member itself for greater strength and convenience. Stock ejector assembly  2  positively separates the stock strip from the die during operation of the metal forming die, and provides a very compact, low-profile shape that can be used at various locations and orientations on various die members. The installation of the stock ejector assembly  2  can be achieved with simple machining so as to reduce the installation time and cost. The shape of the stock ejector assembly  2  can be configured so as to accommodate many different applications and users. 
         [0049]    In the foregoing description, it will be readily appreciated by those skilled in the art that modifications may be made to the invention without departing from the concepts disclosed herein. Such modifications are to be considered as included in the following claims, unless these claims by their language expressly state otherwise.