Abstract:
A linkage for controlling the removal of a workpiece from a press by controlling the timing between the workpiece support apparatus and the ram as it is raised and lowered. The linkage is connected to the ram in such a manner that the supporting apparatus has an adjustable dwell which can be adjusted by adjusting the length of both the linkage as well as a rod connected between the ram and the linkage.

Description:
BACKGROUND OF THE INVENTION 
     This invention is related to linkage means for connecting the motion of a workpiece supporting apparatus for moving a workpiece between the ram and bed of a press in such a manner as to provide a controlled timing of the support including a dwell enabling gripper means to engage the workpiece. 
     Some presses for working sheet metal are frequently automated so that the blank is inserted by a workpiece supporting apparatus to the opening between the ram and the bed of the press. There are also automated devices for removing the formed blank from the press after the ram has been raised. In order to provide a sufficient period of time for the gripper carried on the workpiece support means, to engage the blank it is desirable to have the connection between the press and the support means provide a dwell in the motion of the workpiece support means. 
     SUMMARY OF THE INVENTION 
     The broad purpose of the present invention is to provide an adjustable linkage for connecting the motion of a ram with a workpiece support means such that as the ram is being raised and lowered there is a dwell period when the workpiece support means is relatively stationary to permit gripper means to engage the blank prior to withdrawing it from the press. 
     Still further objects and advantages of the invention will become readily apparent to those skilled in the art to which the invention pertains upon reference to the following detailed description. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The description refers to the accompanying drawings in which like reference characters refer to like parts throughout the several views and in which: 
     FIG. 1 is an elevational view of a press employing the preferred linkage means showing the gripper means disposed in the opening between the ram and the bed of the press; 
     FIG. 2 is a view showing the gripper means at the opposite end of its stroke, removed from the press opening; 
     FIG. 3 is a view generally seen along lines 3--3 of FIG. 1; and 
     FIG. 4 is a view as seen along lines 4--4 of FIG. 2. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings, FIGS. 1 and 2 illustrate a press, generally indicated at 10, having a lower press member or die 12 and a upper press member or ram 14 slideably mounted in the conventional manner for motion in a vertical stroke in the direction of arrow 16. 
     Frame 18 is mounted on base 20 of the press and carries leg means 22 supporting a pair of rods 24 and 26. Carriage 28 carries upper roller means 30 which ride on rod 24, upper roller means 32 which ride on rod 26, lower roller means 34 which engage the lower side of the rod 24, and lower roller means 36 which engage the lower side of rod 26. The arrangement is such that the carriage is moveable in a horizontal position along a path of motion generally at right angles to the direction of motion 16 of ram 14. 
     Extractor arm 40 is carried by the carriage. Workpiece gripper means 42 are carried at the opposite end of the extractor arm. The gripper means are adapted to open and close by means not shown to engage sheet metal workpiece 44. Vertical leg means 46 are mounted on the bed of the press and carry skid member 48 to slideably support the extractor arm as it moves horizontally between its position adjacent the press and the position in which it is spaced from the press. 
     Link means 50 are connected between carriage 28 and ram 14. Link means 50 includes a link 52. 
     A lower link section 54 is threadably engaged with an opening in the lower end of link 52. Pivot means 56 pivotally connect the lower link member to frame 18 so that link means 50 can be pivoted between a generally vertical position in which the upper end of link member 52 is closely adjacent frame 18, and a lower position in which the link 52 is pivoted toward the right as viewed in FIG. 2. 
     Link members 52 and 54 are threadably connected together so that their overall length can be adjusted. 
     Link means 60 comprises a link member 62 and a shorter link member 64 threadably connected together at 66 so that the overall length of link means 60 can be adjusted. Pivot means 68 connect link member 62 to link member 52 while pivot means 70 connect link member 64 to carriage 28. The arrangement is such that as the link means 60 is pivoted, link means 60 causes the extractor arm to move either toward the press or away from the press. As viewed in FIG. 2, as link member 50 is pivoted toward the left, the extractor arm moves toward the press, and as link member 50 is pivoted toward the right, the extractor arm moves away from the press. 
     Cam plate 72 is mounted on frame 18 adjacent the path of motion of the extractor arm. The cam plate has a cam slot 74, which as viewed in FIG. 1 has a generally vertical section 76 that is generally parallel to the direction of motion of ram 16, and an inclined portion 78 that is inclined with respect to the path of motion 16 of the ram. Connecting member 80 is connected by pivot means 82 to an arm 84 that is attached to ram 14. Connecting member 80 is also formed of two telescopically, threadably engaged members 86 and 88. The overall length of connecting member 80 can be adjusted by threadably adjusting member 88 with respect to member 86. 
     Referring to FIG. 4, a pair of cam rollers 90 and 92 are carried at the lower end of connecting member 88. Cam roller 90 is received in slot portion 78 while cam roller 92 is received in slot 94 provided in link member 52. 
     The arrangement is such that as ram 14 is raised, connecting member 80 causes link number 52 to pivot toward the ram and thus move the extractor arm toward workpiece 44 disposed in the press. The gripper means is actuated by means, not shown, to engage the workpiece. As the ram is raised further, there is a dwell in the motion of the extractor arm as the lower end of connecting link 80 moves up slot section 76. When the ram is lowered, roller 90 engages the bottom of slot section 76. Link 52 is moved toward the right as roller 90 moves in the inclined portion of the cam slot thereby causing the extractor arm to move away from the press. The arrangement is such that the two rollers in slots 94 and 78 move the extractor arm toward the press in a continuous motion which is interrupted when the ram approaches the top of its stroke for a sufficient time for the gripper means to engage and then withdraw the workpiece from the opening between the ram and the bed of the press. 
     It is to be understood that the timing can be changed by either increasing or reducing the overall length of connecting member 80, link means 52 or link means 60. Similarly, the timing arrangement can be changed by changing the cam plate to one having a slightly different cam contour.