Abstract:
A press machine includes at least one actuator and at least one linkage to open and close a ram. Another aspect employs a sheet metal-working punch mounted to the ram. A fluid-powered piston drives a carriage coupled to a linkage in another aspect of the present machine. In still another aspect, at least a majority of an actuator is located externally to an outside surface of a stationary structure within which a ram is located. Yet a further aspect both opens and closes a ram with a unidirection movement of an actuator.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/259,697, filed Nov. 25, 2015, which is incorporated by reference herein. 
     
    
     BACKGROUND AND SUMMARY 
       [0002]    The present invention relates generally to press machines and more particularly to a linkage operated press. 
         [0003]    Presses for stamping and piercing sheet metal are well known. Conventional presses typically are driven by a large hydraulic piston, vertically oriented screws rotated by electric motors, or crankshafts, in combination with toggle linkage mechanisms. Examples of these conventional presses are disclosed in the following U.S. Pat. No. 7,810,368 entitled “Multi-Mode Hammering Machine” which issued to Rusch on Oct. 12, 2010; U.S. Pat. No. 6,510,786 entitled “Hydromechanical Press Drive” which issued to Harsch on Jan. 28, 2003; U.S. Pat. No. 4,920,782 entitled “Press Drive” which issued to Hellwig on May 1, 1990; and U.S. Pat. No. 3,763,690 entitled “Press Brake Ram Leveling” which issued to Kirincic et al. on Oct. 9, 1973. All of these patents are incorporated by reference herein. 
         [0004]    These conventional presses, however, suffer various deficiencies. For example, they open and close too slowly. Furthermore, traditional hydraulically and motor driven presses often have jerky opening and closing movements which reduces durability. Prior crankshaft and sector gear mechanisms also require custom, and therefore expensive, parts. 
         [0005]    In accordance with the present invention, a press machine includes at least one actuator and at least one linkage to open and close a ram. Another aspect employs a sheet metal-working punch mounted to the ram. A fluid-powered piston drives a carriage coupled to a linkage in another aspect of the present machine. In still another aspect, at least a majority of an actuator is located externally to an outside surface of a stationary structure within which a ram is located. Yet a further aspect both opens and closes a ram with a unidirection movement of an actuator. Methods of operating a press are also provided. 
         [0006]    The present linkage press machine is advantageous over conventional presses. For example, the present machine operates faster and smoother. Furthermore, standard components can be used to move the present ram, as compared to traditional devices, thereby reducing the expense of manufacturing the present machine. Additional advantages and features of the present machine will become apparent from the following description and appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a diagrammatic front view showing a first embodiment of the present press machine in a first open position; 
           [0008]      FIG. 2  is a diagrammatic front view showing the first embodiment machine in a closed position; 
           [0009]      FIG. 3  is a diagrammatic front view showing the first embodiment machine in a second open position; 
           [0010]      FIG. 4  is a diagrammatic side view showing the first embodiment machine in the open positions; 
           [0011]      FIG. 5  is a diagrammatic front view showing an electromagnetic actuator construction of the first embodiment machine in the first open position; 
           [0012]      FIG. 6  is a perspective view showing a second embodiment of the present machine; 
           [0013]      FIG. 7  is a side elevational view showing the second embodiment machine in a closed position; 
           [0014]      FIG. 8  is an exploded perspective view showing the second embodiment machine; 
           [0015]      FIG. 9  is a fragmentary perspective view showing the second embodiment machine in an open position; 
           [0016]      FIG. 10  is a fragmentary elevational view showing the second embodiment machine in the open position; 
           [0017]      FIG. 11  is a fragmentary perspective view showing the second embodiment machine in the closed position; 
           [0018]      FIG. 12  is a cross-sectional view showing the second embodiment machine in the closed position; and 
           [0019]      FIG. 13  is a diagrammatic view showing portions of the second embodiment machine in the open position. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    A first embodiment of a linkage press machine  21  is illustrated in  FIGS. 1-4 . Machine  21  includes a pair of coaxially aligned fluid-powered actuators  23  and  25 , a carriage or slide  27 , linkages  29 , a ram  31  (also known as a die) and a stationary structure  33 . Structure  33  includes four spaced apart corner posts or frames  35  affixed to and spanning between a base  37  and a cap  39 . Optionally, a table or support  41  is located between base  37  and a factory floor  43 . Adjacent pairs of frames  35  define four generally vertical planes surrounding a periphery of machine  21 . Optionally, protective covers may be externally attached to frames  35 , in which event, they define the vertical planes. A workpiece feeding direction dimension f is less than a perpendicular dimension d for machine  21 . 
         [0021]    Each actuator  23  and  25  includes a fluid powered cylinder  51 , a piston  53  and a piston rod  55 . Hydraulic or pneumatic fluid is pumped into each cylinder at an inlet port  57 , via a hose  59 , which pushes pistons  53  and their associated rods  55 . Fluid on the opposite side of pistons  55  flows out of an outlet port in cylinders  51 . A majority of actuators  23  and  25  is located externally to the adjacent outside surfaces defined by the vertical planes of frames  35 , and also below a horizontal plane defined by a lower surface of cap  39 . A bracket  61  stationarily couples each cylinder  51  to one of the frames  35  and/or cap  39 . 
         [0022]    An elongated rail  63  is mounted to the bottom surface of cap  39  by screws. Carriage  27  is movably coupled to and rides along a rail  63 . Carriage  27  has multiple generally C-shaped fingers extending from a top thereof which slide along but engage with associated undercut channels of rail  63 . One or more ball bearing races may be positioned between carriage  27  and rail  63 . Both piston rods  55  are coupled to carriage  27  by removable threaded or pinned fittings  65  to allow for maintenance of the components. 
         [0023]    Two straight linkages  29  are located on opposite sides of machine  21 . Linkages  29  each have only a first pivot  67 , adjacent an upper end, and a second pivot  69 , adjacent a lower end. Both upper pivots  67  are directly rotatably coupled to carriage  27  and both lower pivots are directly rotatably coupled to ram  31 . Of course, bushings, ball bearing races and pivot pins may be employed at the pivot couplings. Linkages  29  define a parallelogram four-bar linkage mechanism, which is mirrored on the opposite side of ram  31 . Actuators  23  and  25 , carriage  27 , and linkages  29  are the sole driving mechanisms for ram  31 , without any cams, toggles or levers, thereby creating a simplified, durable and cost effective construction. 
         [0024]    Ram  31  is coupled to all four frames  35  via linear, caged ball guides  81 . Guides  81  include vertically elongated rails affixed to frames  35  and blocks mounted to sides of ram  31  which slidably mate with the rails. An exemplary guide  81  is a SHS caged ball LM guide which can be obtained from THK Co., Ltd. of Tokyo, Japan. 
         [0025]    One or more punches  83  are affixed to a bottom of ram  31  and vertically extend therefrom. One or more upstanding dies  85  are affixed to base  37 , aligned with punches  83 . Two sets of punches and dies are shown. Punches and dies deform one or more sheet metal workpieces  87 , such as by bending, piercing holes and/or by creating interlocking clinch joints to fasten the workpieces together. 
         [0026]    Machine  21  operates as follows. First, pistons  53  are internally pushed from one end of their cylinders  51  to the other, from right to left in the exemplary sequence illustrated from  FIGS. 1-3 . The pistons may both be actively driven in a simultaneous manner or one may be active and the other a passive slave depending on the direction. Advancement of pistons  53  moves piston rods  55 , which in turn, moves carriage  27  from right to left. This action rotates linkages  29  thereby vertically advancing ram  31  from its fully open and raised position shown in  FIG. 1  to its fully closed and lowered position shown in  FIG. 2 . Punches  83  and dies  85  deform workpiece(s)  87  in this ram closing operation. Linkages  29  are essentially vertically oriented in an over-center position when ram  31  is closed. 
         [0027]    Continued advancement of pistons  53 , rods  55  and carriage  27  in this same unidirectional movement (right-to-left as illustrated) further rotates linkages in a counterclockwise direction (as illustrated). This reverses and retracts ram  31  from its closed position (shown in  FIG. 2 ) to its open position (shown in  FIG. 3 ), whereby pistons  53  have reached their end of travel positions opposite those illustrated in  FIG. 1 . After the first workpiece(s) is removed and a subsequent one is fed in, the fluid power is reversed causing the pistons, carriage and linkages to reverse direction, thereby closing and then reopening the ram. 
         [0028]    This open-closed-open movement of ram  31  is a single continuous motion of the pistons, carriage and linkages without any intermediate stoppage. Furthermore, this open-closed-open ram movement preferably occurs within 0.5 second for a vertical distance v of at least one inch. The present driving mechanism provides a very fast and smooth operation, in a very compact machine. Moreover, the driving mechanism achieves a continuously variable transmission of ram power with the maximum force to the ram within the last % inch of the advancing stroke adjacent the over-center linkage orientation. 
         [0029]    An alternate construction of machine  21  employs an electromagnetic servomotor actuator  91  connected to a programmable controller via electric wires  93 . A helically threaded and horizontally elongated jackscrew  95  is held by brackets  97  between frames  35  and below cap  39 . Screw  95  is rotated by an armature and an output shaft of motor actuator  91 . An internally threaded ball or nut  97  is enmeshed with screw  95  for linear movement relative to screw  95  when the screw is rotated. Nut  97  is coupled to and prevented from rotating by carriage  27 , and thereby serves to linearly move carriage  27 , which rotates linkages  29  and moves the ram from its open position, to its closed position and then back to its open position as previously discussed with regard to the fluid powered actuation. The present servomotor actuation preferably employs a 1-10 hp motor and a 8:1 motor-to-screw drive ratio, which are both considerably less than conventional arrangements, thereby allowing for lower cost and non-customized components. 
         [0030]    A second embodiment linkage press machine  101  can be observed in  FIGS. 6-13 . This exemplary machine includes an upstanding tool body  103 , a base  105  affixed to the body  103 , a box-like tool support  107  mounted to the tool body opposite base  105 , an actuator  109  coupled to the support  107 , and a transmission mechanism driven by the actuator  109 . The transmission mechanism includes a jackscrew  121 , a ball or nut  123 , a carriage or slide  125 , and one or more linkages  127  (two parallel linkages being shown). 
         [0031]    Jackscrew  121  is coupled for rotation with an output shaft  129  of actuator  109 , which is a servomotor including a rotating armature therein. Jackscrew  121  is held within support  107  by a pair of downwardly extending brackets  131  with internally affixed support bearings  133 . Nut  123  has an internal thread which is enmeshed with a helical external thread of jackscrew  121 . Flanges of nut  123  are attached to a back edge of carriage  125  by way of screws. An oversized bore  135  of carriage  125  is coaxially aligned with but is clear of jackscrew  121  so that carriage  125  linearly moves with but prevents rotation of nut  123  when actuator  109  rotates the jackscrew. An upper flange of carriage  125  is slidably coupled to an elongated rail through generally C-shaped fingers  139  which engage undercut channels in rail  137 . Rail  137  is attached to an upper plate  141  of support  107  by screws, which is also screwed to perpendicularly planar side plates  143  of the support. A lower plate  145 , parallel to upper plate  141 , of support  107  is mounted to body  103  via screws or may alternately be integrally cast or machined as a single piece with the body. 
         [0032]    Each linkage  127  has only two pivots  161  and  163  defined by holes adjacent ends of the linkages with associated bushings  165 , pivot pins  167  and pin-fastening clips  169 . The linkages are straight. For each linkage  127 , pivot  161  rotatably couples an upper end of the link to a section of carriage  125  below jackscrew  121 , opposite rail  137 . Jackscrew  121 , carriage  125  and pivot  161  are always located within support  107  in all operating conditions. Pivot  163  of each linkage is rotatably coupled adjacent an upper end of a linearly movable and vertically elongated ram  181 . Accordingly advancement of carriage  125  away from actuator  109  in a generally horizontal direction (from right to left as illustrated) causes linkages  127  to rotate (counterclockwise as illustrated), which in turn, linearly advances ram  181  from the open position shown in  FIGS. 9 and 10 , to the closed position shown in  FIGS. 11 and 12 . Reverse rotation of actuator  109  retracts the carriage, linkages and ram back to the open position. 
         [0033]    A vertically elongated linear rail  183  is mounted to body  103  by screws. A mating slide  185  is affixed to and moves with ram  181 . Slide includes generally C-shaped fingers which slideable mate with undercut channels of rail  183 . A protective, sheet metal cover or housing  187  is mounted to body  103  and support  107  to hide ram  181  and the bottom of linkages  127 . 
         [0034]    One or more vertically elongated metal-working punches  191  (two are shown) are removably affixed to a bottom of ram  181 . A stripper  193  that strips a workpiece  195  away from the punches after deformation, may also be optionally present. At least one aligned die  197  (two are shown) is affixed to base  105 . The punches and dies may be used to bend, pierce and/or form clinching joints in one or multiples of sheet metal workpieces  195 . 
         [0035]    In one exemplary construction of machine  101 , as illustrated in  FIG. 13 , a pivot-to-pivot ( 161  to  163 ) dimension ψ of each linkage  127  is 12 inches, and a vertical distance ψ between pivot  161  and β is also 12 inches. A ram height dimension is β, and a center of pivot  163  to retracted end of stroke dimension is λ, a press load or force is F, an actuator input force is I and a linkage angle between fully retracted and theoretically vertical is ∝. Accordingly, in one example, if ∝ is 1°, β is 0.002 inch, λ is 0.21 inch, an output-to-input force ratio is 57.29 (assuming no friction) and a press load F is estimated to be 103,122 pounds. In another example, if ∝ is 10°, β is 0.182 inch, λ is 2.08 inches, an output-to-input force ratio is 5.67 and a press load F is estimated at 10,208 pounds. A further example provides ∝ as 22°, β as 0.874 inch, λ as 4.50 inches, an output-to-input force ratio as 2.48, and a press load F is estimated as 4,455 pounds. These examples assume an actuator input force of 1800 pounds per square inch. 
         [0036]    While various embodiments have been disclosed, it should be appreciated that alternate constructions are envisioned. For example, servomotor actuators  91  and  109  may be fluid-rotated actuators. Actuator  109  can alternately be a linear motor or fluid driven cylinder driving a rod or cable instead of a screw and nut, however, certain advantages will not be achieved. Furthermore, different slide and rail components may be employed and differing body, support and structure shaped can be used, but many of the present advantages may not be realized. In another variation, rivets or welds can attach together components in place of the noted screws. It is intended by the following claims to cover these and any other departures from the disclosed embodiments which fall within the true spirit of this invention.