Patent Publication Number: US-2007101849-A1

Title: Ball-lock punch retainer inserts

Description:
This application claims the benefit of provisional patent application Nos. 60/736,070 and 60/830,632 filed Nov. 10, 2005 and Jul. 13, 2006, respectively. 
    
    
     BACKGROUND OF THE INVENTION  
      The field of the invention pertains to retainers for industrial punches and, in particular, to ball-lock punch retainers. Ball-lock punch retainers utilize an offset ball detent and spring mechanism next to the punch socket in the retainer.  
      Examples of such retainers are the Accu-Lock™ special retainer inserts from Wilson Tool International, of White Bear Lake, Minn., and the True-Set® retainer from Moeller Manufacturing Co., of Plymouth, Mich. (U.S. Pat. Nos. 5,337,835, 5,410,932 and Des. 351,395).  
      With a view to providing a more versatile ball lock retainer for special purposes, the following retainer inserts have been developed.  
     SUMMARY OF THE INVENTION  
      Die shops have begun using rectangular block punch retainers and re-drilling punch sockets as punch locations are changed with product changes. Unfortunately, such users cannot generally control the tolerances needed to make the punch retainers function properly.  
      To improve on the retainer systems available in industry, the new retainer inserts provide for a simplified and improved design to assist in manufacturing and to improve functionality, accuracy and cost. The first design incorporates a tapered oblong or teardrop insert that completely encloses the punch socket and angle hole ball detent associated with a standard ball-lock punch retainer. The second design incorporates a non-tapered oblong or teardrop insert with an enlarged head. This design also encloses the punch socket and angle hole ball detent associated with a standard ball-lock punch retainer.  
      There is a very critical relationship between the angle hole and the punch hole or socket. To ensure correct functionality, both holes must be manufactured to very tight tolerances. These improved insert designs incorporate both holes completely integrated into the insert and are therefore completely under the control of the insert manufacturer. Competing versions of the inserts rely upon the ability of the user or customer to provide the accuracy of the punch hole and insert combination. When manufacturing the ball-lock retainers, the punch hole and angle hole are precisely held to ten thousandths of an inch. Users and customers, like die shops, generally cannot control the tolerances as needed to make the product function properly.  
      The new insert designs also simplify the manufacture of the insert holder, allowing users the option to manufacture their own holder. The insert holder may be a simple block of low alloy steel with tapered or counterbored oblong or teardrop holes, which can easily be produced by wire electro-discharge machining (EDM) or computer numerically controlled (CNC) milling processes. The new insert designs have the benefit of speeding the process of moving a punch hole location, which often happens during die and holder construction. By simply using EDM or CNC machinery for a tapered or counterbored oblong or teardrop hole in a new location, a new punch location is established and the obsolete hole is abandoned. The machining can be done even if the holder or retainer is in a hardened condition.  
      The new insert design incorporates the Moeller patented one-piece punch hole design with its integrated backing support for the punch hole and angle hole and includes the snap ring ball and spring retention feature in the preferred embodiments. In addition to improved functionality is the benefit of improved lead time required to manufacture multi-punch holders or retainers. The new inserts can be inventoried ready for use and combined with custom built multi-tapered hole or multi-counterbored hole insert holders. Time is saved by eliminating the lengthy heat-treating step when manufacturing complete ball-lock retainers because blank insert holders can be also heat treated and inventoried.  
      Overall, the new inserts allow die shops to build their own stamping and punching details and still incorporate the ball-lock punch retention system. The ease and ability to do die and holder repair and alteration are improved, and lead time is improved. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a top plan view of the first tapered oblong insert;  
       FIG. 2  is a side cross-section of the first insert;  
       FIG. 3  is an end elevation of the first insert;  
       FIG. 4  is a top plan view of a rectangular block oblong tapered insert holder;  
       FIG. 5  is a side cross-section taken along the line  5 - 5  in  FIG. 4 ;  
       FIG. 6  is a side cross-section of the first insert with a screw plug for the ball detent;  
       FIG. 7A  is a side cross-section of an alternative first insert for use with a backing plate;  
       FIG. 7B  is an end cross-section of the new insert of  FIG. 7A ;  
       FIG. 8  is a top plan view of an alternative first tapered teardrop insert;  
       FIG. 9  is a top plan view of a rectangular block tapered teardrop insert holder;  
       FIG. 10  is a top plan view of an alternate form of tapered teardrop insert;  
       FIG. 11  is a side cross-section of the teardrop insert of  FIG. 10 ;  
       FIG. 12  is a side cross-section of the teardrop insert of  FIG. 10  positioned in a modified insert holder;  
       FIG. 13  is a top plan view of an alternative headed teardrop insert;  
       FIG. 14  is a side view of the headed insert;  
       FIG. 15  is a perspective view of the headed insert;  
       FIG. 16  is a top plan view of a rectangular block counterbored teardrop insert holder; and  
       FIG. 17  is a side cross-section taken along the line  17 - 17  in  FIG. 16 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Illustrated in  FIGS. 1, 2  and  3 , the new oblong insert  10  has a punch hole or socket  12  and a ball detent  14  partially extending into the socket. The base of the socket  12  includes a counterbore  16  and dowel pin hole  18 . An angle hole  20  encloses the ball detent  14 , spring  22 , and at the end of the spring remote from the ball a counterbore  24  for a snap ring (not shown) is provided. A relief hole  26  extends from the ball detent  14  to the top  28  of the insert  10 . The sidewall  30  of the insert body is tapered about the entire insert  10  to provide a larger bottom  32  than top  30 .  
      In  FIGS. 4 and 5 , a block retainer or holder  34  is of generally rectangular shape and formed with several bolt holes  36  for attachment of the bottom  38  in contact with a press platen (not shown). Also formed in the block  34  are dowel pin holes  40 . Typically, the bolt holes  36  and dowel pin holes  40  are formed prior to heat treating of the block  34  and then finished for accuracy, if necessary, when the oblong holes  42  are formed by using EDM or CNC methods. The oblong holes  42  are tapered outwardly from the top  44  of the block  34  to the bottom  38 , as best shown in  FIG. 5 , which shows an insert  10  in one of the tapered oblong holes. With the tapered insert  10  in the tapered hole  42  and the block  34  attached to a press platen, the press platen acts as a backing plate against the bottom  38  of the block thereby preventing the insert from loosening in the block and eliminating the need for a backing plate.  
      Illustrated in  FIG. 6  is a modification of the insert  10  wherein a screw plug  46  is inserted in a threaded portion  48  of the angle hole  20 . As with the snap ring above, the screw plug  46  provides a preset spring  22  compression for the ball detent  14 . Where a backing plate is used on the holder, the angle hole  50  is not formed with a threaded portion or a counterbore and the spring  22  extends to the bottom  32  as shown in  FIGS. 7A and 7B . The punch hole  52  extends fully through the insert  10 . A holder and backing plate are further disclosed in  FIG. 12 .  
       FIGS. 8 and 9  disclose a modification to the insert  54  comprising a teardrop shape in plan view. The end  56  of the insert  54  containing the socket  12  is larger as shown than the opposite end  58  containing the angle hole  20  for the ball detent  14 . The sidewall of the insert  54  is tapered outwardly in the same manner as the sidewall of insert  10  resulting in a larger teardrop shape at the bottom of the insert  54 .  
      Correspondingly, the insert holder  60  is formed with teardrop-shaped holes  62  that are tapered outwardly from the top  64  to the bottom. Thus, the teardrop-shaped insert  54  fits into the insert holder  60  with teardrop holes  62  in the same manner as shown at  66  as the oblong insert  10  fits into the insert holder  34 . However, the teardrop configuration prevents any reverse insertion of the insert in the holder which can happen with the oblong insert in its holder.  
       FIGS. 10 and 11  illustrate a modification of the teardrop-shaped insert  68  wherein the socket  70  for a punch is a through hole and the ball  14  and spring  22  are only located in the angle hole  20 . The insert  68  has a tapered sidewall  72  as above which extends outwardly from the top  74  to the bottom  76 . To provide a seat for a punch and retain the ball  14  and spring  22  in the insert  68 , a plate  78  covers the bottom  76  as shown in  FIG. 12 . The plate  78  is affixed to the insert holder  80  by a machine screw (not shown) in the counter-bored hole  82 . The insert holder  80  includes bolt holes  36  and dowel pin holes  40 , as above; however, the bolt holes and dowel pin holes penetrate the plate  78  for attachment to a platen or a press.  
       FIGS. 13, 14  and  15  illustrate the headed or enlarged head teardrop insert having the same punch hole or socket  12  and ball detent  14  partially extending into the socket. The base of the socket  12  includes a counterbore  16  and dowel pin hole  18 . An angle hole  20  is provided for the ball detent and spring (not shown).  
      The sidewall  84  is perpendicular to the top  86  and bottom  88  of the insert. The bottom  88  of the insert is enlarged relative to the top  86  forming an enlarged portion or head  90  of the sidewall  84  adjacent the bottom and a peripheral shoulder  92  in the sidewall.  
      Illustrated in  FIGS. 16 and 17  is a block retainer or holder  94  generally formed as in  FIG. 4  but having insert teardrop-shaped holes  96  formed to accept the enlarged head teardrop insert of  FIGS. 13, 14  and  15 . As best shown in  FIG. 17 , the holes  96  are formed with a counterbore  98  in the bottom  100  of the holder  94  to lock in the enlarged head  90  insert  102  when the holder is fastened to a press platen.