Abstract:
A press mounted cam has an adapter, slide and a driver with range of sizes and working angles provided at low cost by driver and/or adapter constructions having base plates and a series of side by side upright plates of a number corresponding to a given length with an angled top corresponding to a given working angle.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. provisional Ser. No. 60/629,147, filed Nov. 18, 2004. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention concerns press mounted cams, which are mechanisms installed in forming presses to produce a feature on the formed part, such as a punched or tapped hole. Where the feature must be formed by tool motion along a direction at a working angle transverse to the direction of press motion, such cams are used to produce this tool motion. 
     These cams are comprised of a “slide”, carrying the tool, a “body” or “adapter” affixed to one of the die parts or press platens on which the slide is slidably mounted and a separate “driver” mounted on the other of the die parts or press platen. The driver engages the slide and drives the same by mating cam surfaces when the press is operated. 
     In an “aerial” cam shown in  FIG. 1 , a slide  12  is suspended on a body of adapter  10  mounted to the upper platen  2  or die part  6 . A driver  14  is mounted to the lower platen  4  or die part  8  and has a fixed inclined cam surfaces  16  extending parallel to the working angle, typically defined by wear plates affixed to faces on the driver  14  and slide  12 . 
     As the upper platen  2  descends, a resulting cam action causes the slide  12  to be advanced along the working angle against the resistance of one or more springs  15  with tooling T projecting from the slide  12  in that direction. The horizontal component of the motion requires that the working slide  12  also move laterally on the adapter  10 . Engaged horizontal bearing surfaces  18 ,  20  are provided on the top of the slide and the bottom of the adapter  10  for this reason. In other configurations, an angled surface may be on the adapter, and a horizontal surface on the driver as the embodiment seen in  FIG. 10 . 
     In a “die” or “base” mounted cam (shown in  FIG. 2 ) the slide  12  and adapter  10  are both mounted to the lower platen  4  or die part  8  and do not move, but rather the drive  14  mounted to the upper platen  2  or die part  6  descends to engage the slide  12 . 
     The die mounted cam thus does not result in vertical movement of the heavy slide when the press is operated which is necessary in an aerial cam, but which can cause problems as described below. However, aerial cams are often necessarily used to create a clearance space allowing transfer of the workpiece into and out of the die. 
     In a conventional aerial cam, a slide  12  ( FIGS. 3 and 4 ) is suspended on a body or adapter  10  mounted to the upper platen. A driver  14  is mounted to the lower platen and has fixed inclined cam wear surfaces  16 ,  16 A extending parallel to the working angle, typically defined by wear plates affixed to faces on the driver and slide. 
     As the upper platen descends, cam action causes the slide to be advanced along the working angle with tooling projecting from the slider in that direction. The horizontal component of the motion requires that the working slide  12  also move laterally on the adapter  10 . Engaged bearing surfaces  18 ,  20  are provided on the top of the slide and the bottom of the adapter for this reason. 
     In order to accurately locate the tooling, the working slider must be accurately located laterally when engaging the driver and to achieve this, the practice has been to form the lower cam surfaces  16 A in a V-shape so as to provide lateral location of the slide on the driver as well as a camming surface as the slide engages the driver. 
     Additional flat surfaces  16 B are sometimes required for larger sized aerial cams to provide adequate area to distribute the stresses imposed by the press. Precision machining of the compound sloping V-shape camming surfaces is difficult and adds substantially to the cost of making the slider  12  and driver  14 . 
     The slider  12  is suspended on the adapter  10  by means of side plates  20  engaged with plates hooked over plates  22  attached to the sides of the slider  12 . The slider  12  is guided along the plates  20 ,  22  when being advanced by the camming action on the slider caused by the descent of the press upper platen. 
     The plates  22  are confined between side walls  24  to be laterally guided. A vertical hooked bar  26  is mounted on each side to reinforce the fixing of the plates  20 . 
     Particularly in larger sizes, the need to machine the adapter  10  and slide  12  at locations on the outside of these components requires large size machining centers, adding to substantially to the cost of manufacturing the aerial cam. 
     Due to the large mass of the components, an auxiliary roller cam  28  is provided to initiate and assist slider motion by engagement with a machined slot  30  on the driver  14 , just prior to engagement of the cam surfaces. This helps to initiate motion of the slider prior to engagement of the cam surfaces to reduce noise, shock and wear of the cam surfaces. However, this feature also adds substantially to the cost of such aerial cams. 
     A positive retraction auxiliary cam comprised of cam bars  32  and  34  is also provided to insure return movement of the slide  14  if return springs in pockets  36  should fail due to excessive shock loading. 
     A substantial practical difficulty encountered in manufacturing such cams is the great variety of configurations needed. Availability in a large number of working angles and lengths are required. Typically, the angle between the slide upper and lower surfaces is maintained constant, and the driver and adapter angles are varied with changes in the working angle. 
     The adapter, slide and driver have heretofore been machined from castings, a unique casting required for each of these components for each cam configuration, which is very costly particularly in the larger sizes. 
     It is an object of the present invention to provide a press mounted cam which eliminates hard to machine features, and is much easier to manufacture in the large number of configurations needed so as to substantially lower its cost of manufacture. 
     SUMMARY OF THE INVENTION 
     The above object and other objects which will become apparent upon a reading of the following specification and claims are achieved by manufacturing the driver and/or the adapter of a built-up construction rather than being machined from castings. A series of parallel side by side upright plates having their upper ends cut at the required working angle are attached to a flat base plate, the number of upright plates varying depending on the length of the driver or adapter (and slide). A support plate is affixed to the angled upper ends of the upright plates to provide an inclined mounting for mounting the cam wear plates. Drivers and adapters of this construction can be produced at a much lower cost than when using castings, and can easily be made at low cost in a large number of configurations of different lengths and working angles. 
     The slides machined can be from a limited number of castings, cut to length as needed. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partially sectional fragmentary view of a press and die with an aerial cam installed therein. 
         FIG. 2  is a partially sectional fragmentary view of a press and die with a die mounted cam installed therein. 
         FIG. 3  is an exploded pictorial view of an aerial cam of a prior design. 
         FIG. 4  is a pictorial exploded reverse view of a prior aerial cam shown in  FIG. 3 . 
         FIG. 5  is an exploded pictorial view of an aerial cam according to the present invention. 
         FIG. 6  is an exploded reverse pictorial view of the aerial cam shown in  FIG. 5 . 
         FIG. 7  is a pictorial sectional view of the aerial cam shown in  FIGS. 3 and 4 . 
         FIGS. 8A–8D  are reduced size simplified views of an aerial cam according to the invention, showing successive stages in the work cycle. 
         FIG. 9  is a diagrammatic view of the aerial cam shown in  FIGS. 8A–8D , in the fully advanced position. 
         FIG. 10  is a diagrammatic view of an aerial cam according to the invention of a different configuration, showing a workpiece to be formed in a fixture. 
         FIG. 11  is a pictorial view of a slide used in the aerial cam according to the invention illustrating with phantom lines how a common casting can be shortened by cutting off one or both ends to produce slides of different lengths. 
         FIGS. 12 and 13  are enlarged fragmentary sectional views showing the relationship of the T blocks with the slider and driver as the press is cycled. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, certain specific terminology will be employed for the sake of clarity and a particular embodiment described in accordance with the requirements of 35 USC 112, but it is to be understood that the same is not intended to be limiting and should not be so construed inasmuch as the invention is capable of taking many forms and variations within the scope of the appended claims. 
     Referring to  FIGS. 5–7 , a cam  38  according to the present invention is shown which includes an adapter  40 , a slide  42 , and a driver  44 . While an aerial cam is shown in that the adapter  40  and slide  42  is above the driver  44 , the present invention is also applicable to die mounted cams as described above. 
     The adapter  40  is affixed to a press upper platen (not shown) using keys  46  to be accurately and securely positioned thereon. 
     The driver  44  is mounted to a press lower platen (not shown). 
     The slide  42  is suspended on the adapter  40  by a pair of inboard located T blocks  48  affixed to the upper side of the slide, and passed through slot openings  50  in a base plate  52  of the adapter  40 . As seen in  FIGS. 7 ,  12  and  13 , the base plate  52  has an underplate  54  affixed thereto, with slots  56  formed therein freely receiving the narrow lower part  49  of a respective T block  48 , the head portion  51  resting on surfaces adjacent the respective slot  56 . 
     A clearance space  58  ( FIG. 12 ) exists between the mating bearing surfaces on slide  42  and adapter  40  when the slide  42  is suspended from the adapter  40 , but is eliminated after a short delay when the press motion then initially causes the engagement of the slide  42  with the driver  44  for a purpose to be described below. This clearance  58  can be relatively slight, i.e., on the order of 0.001 to 002 inches. 
     The slide  42  slides laterally on the adapter  40  in the embodiment, shown in  FIGS. 5–7  when the slide  42  is shifted by engagement with the driver  44  as the upper press platen descends as seen in  FIGS. 8B–8D . 
     A set of wear plates  60  on the adapter  40  rides on a mating set of wear plates  62  on the upper side of the slide  42 . 
     As will be discussed below, the angle of the engagement surface on the adapter  40  changes with the working angle of the driver  44  since the included angle of the slide  42  typically remains constant with changes in the working angle. Thus, the wear plates on the adapter  40  will be inclined down from horizontal as the working angle becomes shallower. 
     The lateral component of the motion of the slide  42  relative the adapter  40  proceeds against the resistance of a series of compression springs  68  in pockets  64  formed in the slide  42 , the springs  68  projecting out against end wall  66  of the adapter  40 . 
     A closure lock as described in copending U.S. application Ser. No. 10/954,960, filed on Sep. 29, 2004 may be employed if nitrogen springs are used. 
     A combination mechanical spring may be used instead of nitrogen springs as described in U.S. application Ser. No. 10/936,213, filed on Sep. 7, 2004. 
     According to the teaching of the present invention, the driver  44  is of a segmented, built up construction comprised of a flat base plate  70 , having a side by side series of parallel upright flat plates  72  affixed to the upper surface. The length and working angles are easily varied by changing the configuration and number of plates  72  and the size of the base plate  70 . This construction is much cheaper than producing a new casting for each configuration particularly considering that a separate mold must be designed and built for each configuration. 
     A support plate  74  is affixed to the upright plates  72  held at the working angle by the angled upper ends of the upright plates  72 . 
     Cam wear plates  76  are secured to the support plate  74 . 
     The inclined lower side of the slide  42  is provided with mating cam wear plates  78 . 
     An upwardly projecting central locator key  80  is affixed to the driver  44 , aligned with a central slot  82  in the lower side of the slide  42 . 
     The locator key  80  is located and configured to move into the slot  82  as the upper platen lowers the slide  42  onto the driver  44  but before engagement of the cam wear plates  76 ,  78 . This laterally locates the slide  42  and guides it after the slide  42  is advanced along the working angle by the platen motion and engagement of the cam wear plates  76 ,  78 . 
       FIGS. 8A–8D ,  12  and  13  illustrate the working of a cam according to the invention. 
     In the initial condition, the slide  42  is suspended below the adapter  40  by the T blocks, with a clearance space  58  therebetween. 
     As the upper platen  84  descends towards the lower platen  86 , the locator key  80  enters the slot  82  to provide lateral location and guidance, as seen in  FIG. 8B . 
     The clearance space  58  is then still present, and the cam wear plates  76 ,  78  have not yet engaged. 
     Continued descent of the upper platen  84  brings the cam wear plates  76 ,  78  into initial contact as seen in  FIG. 8C . The clearance space  58  still exists, although now being reduced. 
     This initial contact causes the momentum of the slide  42  to be absorbed by driver  44  and results in initiation of the camming motion of the slide  42 , as indicated by the lateral motion of the slide  42 , compressing spring  68 . 
     It should be noted that the extent of this motion and the size of the clearance space  58  is shown exaggerated in order to be readily visible in the drawings. 
     The next stage, shown in  FIG. 8D  shows that the clearance space  58  has now been completely eliminated, and the press forces exerted by the upper platen  84  cause continued camming advance of the slide  42  along the working angle. This drives the tooling  88  into contact with a workpiece  90 , fully compressing the spring  68  in the advanced position, as indicated diagrammatically in  FIG. 9 . 
     Thus, in the initial engagement of the wear plates  76 ,  78  only the momentum of the slide  42  is absorbed, and the positive press drive force is momentarily delayed until the clearance  58  is taken up. This reduces shock and noise, and obviates the need for auxiliary cam rollers, formerly used, and is described and claimed in copending application U.S. Ser. No. 11/069,828, filed on Feb. 28, 2005. 
     As noted, if the working angle is shallower, the adapter  40 A will have an inclined wear plates as seen in  FIG. 10 , and in this case, the adapter  40 A may also be constructed using a parallel series of plates  92  cut at an angle to incline a support plate  94 , in similar fashion to the driver  44 A. The T block  96  passes through a slot in the support plate  94  and rides on the surface of the support plate  94 . The same initial clearance is provided as indicated. 
     The slide  42  is contemplated as being made from a casting. However, a common casting can be used for several length sizes by sawing off portions  42 A of the casting as indicated in  FIG. 11  by the broken lines to reduce the total number of casting lengths required. 
     If the driver has horizontal wear plates for steeply angled adapters, then the driver may be configured in a similar way as to the adapter. 
     Accordingly, a press mounted cam can be economically manufactured in a great number of sizes and working angles.