Abstract:
A hydraulic press utilizes a product feed mechanism including a product lifting linkage capable of raising and lowering a product-holding platen while maintaining same in a precise horizontal position during such movement. The hydraulic drive for the lifting and lowering mechanism is capable of moving the platen to any precise vertical position and maintaining same at that position before, during and after press operations. In connection with the lifting and lowering mechanism, a linear motor horizontal drive mechanism is coordinated with the lifting mechanism to enable the product feed system to precisely position the platen anywhere along the travel of the linear motor. The combination of the lifting and lowering mechanism with the linear motor horizontal drive mechanism provides, when operated by an open architecture PC control system, a new and improved product feed mechanism more precisely controllable than heretofore known.

Description:
This invention relates to a computer operated hydraulic press utilized as a finishing machine for manufacturing operations on various plastic and/or rubber material parts, and more particularly, to a lifting and feeding mechanism for moving those plastic parts into and out of the finishing operations while maintaining those parts in a predetermined (horizontal) orientation while precisely vertically moving those plastic sheets into and out of the finishing operation. 
   BACKGROUND OF THE INVENTION 
   Presses have for years been utilized to provide cutting, bending, forming and other basic manufacturing operations on parts of small sizes and large sizes sufficient to be inserted between the crown and press bed. While innovations to hydraulic presses have been legion throughout the years because of the versatility of presses in manufacturing operations, persons and entities involved in manufacturing operations in addition to developing numerous dies for use in the process, have developed numerous apparatus for moving material to be operated on in the press into and out of the position at which the press operations take place. Additionally, applicant has been involved in inventing protective rocker-arm safety devices for presses as shown in U.S. Pat. No. 4,161,140. 
   When the product parts are substantially smaller than the opening between the press dies, it is typical to have these parts formed in row-column order on a sheet of material that is passed through the press. The press then stamps, cuts, forms or performs other operations on multiple ones of those parts as each individual part is a discrete segment of that sheet of material. Typically, a sheet of such material that is to be formed into parts is positioned on a movable platen by manual or robotic means, or by transfer of the part from one platen to another in a line or series of presses performing differing operations on the parts to be manufactured. Various press transfer apparatuses have typically included linkages having bell cranks to turn rotary motion into linear motion as shown in U.S. Pat. No. 4,651,866. Screw mechanisms have heretofore been utilized to move platens horizontally into and out of position in presses as shown in U.S. Pat. No. 5,749,290. Parallel linkages have also been utilized to feed material to and through presses and/or equipment for machining operations, as shown in U.S. Pat. No. 5,078,570. 
   In a prior generation of applicant&#39;s presses, sheets of plastic and/or rubber material were positioned on a platen which was moved into position into and over the lower die mounted on the press. In order to conserve energy and motion, the platen was hinged at its far end to a screw drive type feed mechanism and, at the near end of the sheet, the platen was raised and lowered as necessary to put the desired portion of the sheet into the correct spatial zone between the upper and lower dies. This mechanical pivoting of the platen and screw drive horizontal location of the platen provided satisfactory results for then current technology finishing operations in the press. Linear motors have been utilized in machine tool operations and in other manufacturing operations as shown in U.S. Pat. Nos. 5,225,725 and 5,808,382. 
   A need has developed for more accurate positioning of products with respect to the dies in a commercial press. Additionally, a need has arisen to more accurately move a sheet product into a position between the dies of a press to allow manufacturing operations to be undertaken to the sheet of material in a more accurate manner than heretofore known. 
   It is therefore and object of the present invention, generally stated, to provide new and improved apparatus for moving product into and out of a position in a press where operations may be performed on that product. 
   It is a further object of the present invention to provide more accurate means of moving a sheet product vertically with respect to a press than heretofore known. 
   It is a further object of the present invention to provide improved means for moving a sheet product longitudinally with respect to a press than heretofore known. 
   SUMMARY OF THE INVENTION 
   The invention resides in a transfer device for moving material through a press with actuation of the press on that material. The transfer device includes a tray having leading and trailing portions for retaining the material thereon and further includes guide means for aiding in the movement of the tray perpendicularly to the orientation of the press. The invention resides in an improvement comprising means for maintaining the tray in a predetermined orientation with the press while moving the tray vertically with respect to the press and horizontally along the guide means with greater precision than heretofore known. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features of the present invention which are believed to be novel are set forth with particularly in the appended claims. The invention may best be understood by reference to the following description taken in conjunction with the accompanying drawings in which like numerals refer to like parts and in which: 
       FIG. 1  is a ¾ front fragmentary perspective view of the press constructed in accordance with the present invention, carrying platen and product feed mechanism utilized to move same into and out of position for operations thereon; 
       FIG. 2  is a top plan detail view of the press with the crown removed, showing the platen and product movement apparatus shown in  FIG. 1 ; 
       FIG. 3   a  is a side elevational diagrammatic view of the press showing the platen and movement linkage of the invention in its lowered position; 
       FIG. 3   b  is a side elevational diagrammatic view similar to  FIG. 3   a  showing the platen and movement linkage of the invention in an uplifted, extended position; 
       FIG. 4  is a fragmentary enlarged detail front elevational view of the platen moving linkage of the present invention; 
       FIG. 5  is a fragmentary detailed perspective view showing the rear portion of one side of the platen lifting linkage; 
       FIG. 6  is a rear quarter perspective view of the sheet moving platen and linear motor horizontal drive; 
       FIG. 7  is an enlarged detail view similar to  FIG. 6  of the linear motor drive portion showing the stator and armature thereof; 
       FIG. 8  is a rear elevational perspective view of the sheet moving platen and linear motor constructed in accordance with the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIG. 1 , a hydraulically operated press, generally indicated at  10 , includes a press bed  11 , a pair of opposing uprights  12 ,  13 , and a crown  14  extending between the uprights  12  and  13  at the top of the press  10 . A first control box  15  mounted on the outside of upright  13  includes hydraulic control means for operating various parts of the press. 
   A press drive hydraulic cylinder  16  is mounted on the crown  14  and it includes a press slide or ram  17  at the bottom thereof on which upper dies (not shown) are mounted. Below the cylinder  16  and press slide  17  adjacent the press bed  11 , will be positioned a bolster plate (not shown) in which lower dies (not shown) are mounted. 
   Referring to  FIGS. 1 ,  2 ,  3   a  and  3   b , while some hydraulically operated presses feed material through the press parallel to the length of the crown, the press  10  of the present invention includes a product feed mechanism  20  that is perpendicular or transverse to the long dimension of the crown  14 . 
   Referring to  FIG. 6-8 , the product feed mechanism, generally indicated at  20 , is mounted on a box framework, generally indicated at  21 , that is secured to the back of press bed  11 . The box frame  21  includes a pair of elongate side members  22 ,  23  and a back panel  24  fastened, in this embodiment to the side members by vertical bracings  25 ,  26 . Referring to  FIGS. 1-3   b , the product feed mechanism of the invention  20  includes a rectangular platen  30  upon which in the preferred use thereof, a molded plastic sheet will be precisely positioned and firmly retained. Rectangular platen  30  includes a plurality of apertures  30   a — 30   a  through which the dies may operate on the sheet thereon (not shown). The platen  30  rides along a pair of opposing feed bars  31 ,  32  into and through the area between the crown  14  and the press bed  11 . Referring to  FIGS. 3   a ,  3   b , a robotic arm  33  affixed to the crown in this embodiment, is capable of moving sheet products onto and off of the platen  30  as desired. 
   Referring to  FIGS. 1-4 , the lifting mechanism that keeps the platen  30  in a horizontal position while the platen raises, moves toward the space between the crown  14  and the bed  11  and then lowers the platen toward the lower die (not shown) includes a pair of mirror image shaped multiple link mechanisms generally indicated at  34 ,  35  in  FIGS. 1 ,  3   a ,  3   b  and  4  ( 35  is only shown in FIG.  4 ). 
   The front portion of the linking mechanisms  34 ,  35  shown in  FIG. 4  include a pair of pneumatic cylinders  36 ,  37  which drive a single connecting rod  38  mounted at opposing ends to offset levers  40 ,  41  both positioned on a single drive shaft  42  that is bearingly retained by pillow blocks  44 ,  45  mounted on the front wall of the press bed  11 . Adjacent each of the opposed ends of drive shaft  42  is mounted a bell crank  46 ,  47  respectively. At one pivotal position on bell crank  47 , a link  48  extends upward to a block  50  on which feed bar  32  is mounted. At the same position on the opposing bell crank  47 , a link  49  extends upwardly to block  51  and is pivotally mounted thereto. Block  51  is secured to feed bar  31 . At the second pivotal mounting on bell crank  46 , a horizontal link  52  extends backwardly to the rear of the box frame  21 . At the second pivotal mounting of bell crank  47 , an identical horizontal link  53  ( FIG. 4 ) extends backwardly from the bell crank toward the rear of the box frame  21 . At its rear, link  52  is pivotally mounted to a bell crank  56  positioned adjacent the end of a driven shaft  58  bearingly mounted in pillow blocks  60 ,  61 , mounted securely to the back wall  24  of box frame  21 . 
   In like manner, horizontal link  53  extends rearwardly to an opposing bell crank (not shown) mounted on the opposing end of driven shaft  58 . On the opposing pivotal mounting of bell crank  56 , a link  60  connects the bell crank to a mounting block  62  which is rigidly connected to the feed bar  32 . Likewise, an identical link (not shown) mounted to the opposing pivot of the opposing bell crank mounted on the opposite end of driven shaft  58  connects that bell crank with block  64  ( FIG. 6 ) that supports feed bar  31 . 
     FIG. 3   a  shows the previously described identical linking mechanisms  34  ( 35 -not shown) in the downward or lowered position and  FIG. 3   b  shows the linking mechanisms  34  ( 35 -not shown) as they appear in the upward or extended position. While the linking mechanisms drive the platen and feed bars upward and downward, in order to maintain the strict vertical movement of the feed bars  31 ,  32 , and precisely maintain the horizontal position of the platen  30  thereon, each of the front mounting blocks  50 ,  51  are reciprocally slidingly retained in linear bearings  66 ,  67  mounted on the front of the press bed  11 . Each of the rear mounting block  62 ,  63  are reciprocally slidingly retained in linear bearings  68 ,  69  mounted on the inside of back rail  24  of the product feed mechanism  20  of the box frame  21 . 
   These vertically mounted linear bearings assure that the movement of the feed bars  31 ,  32  will be vertical and that the front and back of the platen  30  will be moved vertically the same amount during the travel of the linking mechanisms  34 ,  35 . Thus, completely vertical movement of the lifting and lowering mechanism is assured by use of the linear bearings on the four corners of the lifting and lowering mechanism. 
   Referring to  FIGS. 6-8 , the remaining portion of the product feed mechanism  20  includes a linear motor operated horizontal positioning drive, generally indicated at  72 . Linear motor drive  72  is mounted on a motor bed  73  that extends from the press bed  11  rearwardly past the upright back rail  24  of the box frame  20 . Elongate motor bed  73  further includes left and right guide rails  74 ,  75 , respectively, positioned parallel to the edges of motor bed  73  and extending the length thereof. An elongate stator magnet yoke  76  is positioned between and parallel to the rails  74  and  75  on the top surface of bed  73 . Yoke  76  has a plurality of rectangular magnets  77 — 77  positioned in spatial relation along the length thereof. The magnets are positioned in adjacent north-south polar relation as is customary with linear motors. Outside of the left guide rail  74 , an elongate shelf  78  is positioned to provide a receiving shelf for electrical wiring to be discussed in greater detail below. 
   An armature housing plate  80  includes left and right L-shape angle guide rails  81  and  82  depending therefrom and positioned to complementarily slidingly engage with the left and right guide rails  74 ,  75  respectively to prevent lateral movement of the armature relative to the yoke. A coil armature housing  82  depends centrally from the armature mounting plate  80  and includes armature coils positioned thereon which are located in spatial relation immediately above the stator yoke  76 . 
   Extending between the armature mounting plate  80  and shelf  78  is a movable articulated electrical wiring cage  83  which houses wiring necessary to run the linear motor as the armature mounting plate  80  reciprocates back and forth along the guide rails  74 ,  75 . Articulated wiring cage  83  is capable of moving like tractor treads while keeping the wires therein in captured operating order. A drive arm  84  extends upwardly from the top of armature mounting plate  80  and is secured to the back side of platen  30  to assure that the horizontal motion of the platen  30  will follow the movement of the linear armature mounting plate  80 . 
   In operation, the combined coordinated controlling of the linear motor  72  and the left and right lifting and lowering linking mechanisms  34 ,  35  provide a product feed mechanism  20  that will position the platen  30  with respect to the press bed  11  and crown  14  to an accuracy of plus or minus a few microns, while maintaining the platen  30  and the sheet of material to be operated on (not shown) that is mounted or set onto the platen  30  in precise horizontal position with respect to the upper and lower dies (not shown) at all times during vertical movement of the platen  30  and the sheet (not shown) thereon. In prior press finishing machines that pivoted the back end of the product feed bars, the vertical movement of the front of the feed mechanism had to be greater than in the embodiment of the invention in order to clear the dies during the forward feed. With the front and rear of the platen being horizontal at all times, the vertical travel is lessened and the accuracy of the vertical movement is greater and more precisely controlled. 
   In addition, rather than operating the product feed mechanism by a numerical control apparatus, an open architectural personal computer (PC) is utilized and housed in control box  90  ( FIGS. 3   a ,  3   b ). The PC control provides unlimited programmable movement of the product feed mechanism  20  within the mechanical limits of the linear motor and linkage so that multiple operations may be performed at the same location of the sheet mounted on the platen, or so that multiple operations may be performed at as many differing locations along the length of the sheet mounted on the platen, as necessary. Alternatively, a programmable logic control (PLC) type operating machine control may be utilized, with a preferred unit being made and sold by Allen Bradley Control Logics. 
   In one finishing operation utilizing the product feed mechanism of the invention three inputs are fed into the computer program. The first input is the forward distance from the start point to a first punch point which could be an inside diameter punch, an outside diameter punch or a slitting operation. A second input to the computer would be the distance between the rows of the product to be operated on. A third input would be the number of rows of product. Thereafter, the platen would be moved back to the starting position. As mentioned previously, the use of an open architectural program with a personal computer for a controller allows an infinite number of movements and distances of movements to be input to the press. 
   Thus, an extremely versatile and infinitely controllable product feed mechanism has been shown and described which is usable with a press to move product into and out of the press for operations on that product as required during the manufacture thereof. While one embodiment of the present invention has been shown and described, it will be understood by those skilled in the art that many changes and modifications may be made without departing from the true spirit and scope of the present invention. It is the intent of the appended claims to cover all such changes and modifications which fall within the true spirit and scope of the invention.