Abstract:
A positive lock for infinite adjustable stroke alignment mechanism for a mechanical press with an eccentric bushing disposed within a press connection member with a second eccentric member disposed within the eccentric bushing. A rotatable crankshaft is connected to the second eccentric member. A positive lock alignment mechanism is included for aligning the press connection member with the eccentric bushing to prevent rotation therebetween and permitting rotation of the second eccentric member with the eccentric bushing for infinite stroke adjustment whereby rotation of the crankshaft, when the mechanism is activated causes a press stroke adjustment.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a mechanical stamping and drawing presses, and, more particularly, to an apparatus for a positive lock for infinite adjustable stroke connection for adjusting the stroke length. 
     2. Description of the Related Art 
     In mechanical presses, it is often desirable to adjust or change the stroke length of a reciprocating member, for example the slide, to which a stamping tool is installed. In some prior art tooth adjustment systems, there is a tendency of the system parts to wear after a certain period of operation time. It would be desirable to provide an apparatus or system which may be utilized to quickly, easily and accurately adjust the stroke length of a slide or other parts while ensuring alignment of the stroke connection system. In addition, in some mechanical presses with an indefinite adjustable stroke mechanism, there will be a small amount of slippage from one connection to a second connection on a press with the connections and eccentric on a crankshaft after hundreds of stroke changes. Thus, if one of the eccentric bushings rotates a percentage of degree in relation to the secondary eccentric on the crankshaft during the stroke adjustment process, this will cause the stroke mechanism to be out of adjustment. 
     SUMMARY OF THE INVENTION 
     The present invention provides an alignment connection for use in a dual eccentric adjustable stroke connection system for use in changing the stroke length of the slide or other member of the mechanical press such as described in U.S. Pat. No. 5,865,070. 
     An eccentric on a rotatable crankshaft is supplied within an eccentric bushing disposed thereon. A press connection member, such as a connecting rod or link, is attached about the eccentric bushing. During normal operations, there is a relative movement between the eccentric bushing and the connecting member arm to thereby cause reciprocation of the press slide. During stroke adjustment, pressure oil is communicated between the eccentric bushing and the crankshaft eccentric, thereby relieving the press fit or interference fit there between, and causing the eccentric bushing to expand and form a temporary press fit connection with the connecting arm. At this time, the crankshaft may be rotated, along with its eccentric, to thereby change the position of the eccentric within the eccentric bushing. This causes a change of the stroke length. The oil pressure is then relieved thereby causing the eccentric bushing to contract and again form a press fit with the crankshaft eccentric and release the temporary press fit connection between the outside of the eccentric bushing and the connection member arm. After such oil pressure has been reduced, normal press operations may proceed. During normal operations and repeated press operations and stroke adjustments, there can be slippage between the larger eccentric bushing and the connection arm after repeated stroke changes. Thus, if one of the eccentric bushings rotates a percentages of a degree in relation to the secondary eccentric on the crankshaft during the stroke adjustment process, this will cause the slide parallelism from the bottom of the slide to the top of the bolster on the bed to be out of specification. The addition of the positive lock for infinite adjustable stroke and alignment mechanism ensures that during the stroke adjustment process, no movement or slippage will occur and the stroke adjustment will be made uniformly and accurately during each stroke adjustment. 
     The invention comprises, in one form thereof, a mechanical press having a press connection member, an eccentric bushing disposed within the press connection member, and a second eccentric member disposed within the eccentric bushing. The second eccentric member releasably connectable within the eccentric bushing. A rotatable crankshaft is connected to the second eccentric member. The invention includes a system for connecting the eccentric bushing with the press connection member to prevent rotation there between and permitting rotation of a second eccentric member within the eccentric bushing whereby rotation of the crankshaft, when the system is activated, causes a press stroke adjustment. The invention also includes an alignment connection means that secures the press connection member or multiple press connection members to the eccentric bushings at a predetermined position that ensures the proper positioning of each and every eccentric within the adjustable stroke bushing. 
     The invention comprises, in another form thereof, a double acting cylinder means for activating the alignment means, such as a U-bar, into and out of the key ways provided for proper alignment of the eccentric bushing and the press connecting members. The alignment means includes a spring to hold the U-bar open so that the U-bar and the eccentric bushing never come in contact and causes a collision when the eccentric bushing is rotating and fixed to the crankshaft. 
     An advantage of the present invention is that the mechanical presses may now include a positive lock for infinite adjustable stroke alignment mechanism to ensure simple and compact stroke adjustment connections operated by fluid pressure. This is an improvement over prior stock adjustment connections that utilize keys and/or gearing between the crankshaft and the various eccentrics and ensures no slippage or movement of the larger eccentric and connection arms during stroke adjustment operated by fluid pressure. 
     Another advantage of the present invention is that mechanical presses with infinite adjustable stroke mechanisms will have a small amount of slippage from one connector to the other connector on a press with multiple connection members and their respective eccentric bushings on a crankshaft after hundreds of stroke changes. The present invention will prevent rotational movement of the eccentric bushing in relation to the secondary eccentric on the crankshaft and the bearing cap not to move out of specification, during the time the press stroke is being adjusted. 
     Another advantage of the present invention is that the alignment mechanism can be used with the simple and compact stroke adjustment connection operated by fluid pressure. The present invention utilizes a connection that is simple in design and vastly reduces the number of parts necessary for a stroke adjustment mechanism and a method to ensure proper alignment. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a schematic, prospective view in a partial cut away of a portion of the crankshaft and slide connection; 
     FIG. 2 is a cross-sectional view along line E—E of FIG. 1 of the cylinder support and alignment bar; 
     FIGS. 3 a  and  3   b  are cross-sectional views along the line H—H of FIG.  1  and along the line F—F of FIG. 3 a  respectively, along the crankshaft axis at several times of operation, namely during normal stamping operations and during stroke length/eccentric adjustment; 
     FIG. 4 is an axial, cross-sectional view of the press mechanisms showing the crankshaft and connections along with the cylinder support for the alignment mechanisms; and 
     FIG. 5 is an elevational view of a typical mechanical press utilizing the present invention. 
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of the present invention, the drawings are not necessarily to scale and certain features may be exaggerated or omitted in order to better illustrate and explain the present invention. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The positive lock for the infinite adjustable stroke mechanism of the present invention is ideally suited for a wide assortment of configurations of mechanical and stamping presses utilizing one or more connections. As is conventional, a mechanical press  110  (wherein FIG. 5) typically includes a crown portion  115 , a bed portion  117  having a booster assembly connected thereto, and uprights  113  connecting crown portion  115  with the bed portion  117 . Uprights  113  are connected to or integral with the underside of crown portion  115  and the upper side bed portion  117 . A slide  119  is positioned between uprights  113  for a guided, reciprocating movement relative to bed portion  117 . Tie rods (not shown), which extend through crown portion  115 , uprights  113  and bed portion  117 , are attached with each end with the tie rod nuts. Leg members  118  are formed as an extension of the bed and are generally mounted on the shop floor by means of shock absorbing pads. 
     In order to power the reciprocating motion of slide  119 , a drive mechanism  114  for the press is provided. The drive mechanism  114  includes a motor  116 , a clutch  130 , a press drive shaft  131  and a flywheel  120 . The press driveshaft  131  is connected to a pinion  132  which rotates crankshaft  14 . A flywheel  120  is connected to a main flywheel  133  which in turns selectively engages the clutch of the combination clutch brake to power rotation of the press crankshaft  14 , which in turn effects slide motion via connections extending between the slide and the crankshaft. This description of press  110  and its drive mechanism is merely illustrative. A wide variety of mechanical presses are well known in the art, and the use of the present invention can be utilized with any mechanical press that utilizes a crankshaft type device to achieve reciprocating motion of a press component. An example of a mechanical press is disclosed in U.S. Pat. No. 5,189,928 entitled “Adjustable Stroke Punch Press”, which is incorporated herein by reference. 
     Referring to FIG. 1, there is schematically shown a cross-sectional view of a crankshaft main portion  16 , its associated eccentric bushing  20  and connection  10  which is powered by the crankshaft rotation. The connection may be formed of a bottom portion and a cap, and the bottom portion of connection member  10  is attached in a suitable fashion to the press slide. The crankshaft  14  includes a cylindrical main portion  16  axially centered on the crankshaft axis of rotation and a second eccentric member such as a cylindrical eccentric  18 , rotatably fixed thereto or integrally formed therewith. Although only one crankshaft eccentric is shown, multiple eccentrics and connection members  10  would be provided along the axial length of the crankshaft to cooperate with additional connectors which are not shown. Ringing crankshaft eccentric  18  is an eccentric bushing with a keyway  22  to receive an alignment bar  30  to ensure proper alignment during press stroke adjustment. 
     FIG. 2 is a cross-sectional view of cylindrical support  40  and alignment bar  30 . 
     FIGS. 3 a  and  3   b  illustrate the configuration of the alignment mechanism in the position for production and the position during stroke change. In FIG. 3 a , alignment bar  30  is in the upright position and is not engaging eccentric bushing  20  or crankshaft  14 . This allows crankshaft  14  and eccentric bushing  20  to rotate freely during production without a collision. In FIG. 3 b , alignment bar  30  is shown lowered into eccentric bushing  20  for positive lock position during stroke change. 
     FIGS. 1 and 4 better illustrate the configuration of these components, wherein the crankshaft main portion  16  is shown with crankshaft eccentric  18  and eccentric bushing  20  as these components would appear during normal press operation. Alignment bar  30  is now removed or in the up position and removed from keyway  22  as it would be positioned or appear during normal stamping operation. A double acting cylinder  28  and a spring  26  (shown in FIG. 4) to hold alignment bar  30  in the upward position so eccentric bushing  20  is affixed to the crankshaft and rotates with the crankshaft and alignment  30 , and never communicates into keyway  22  and thus cause a collision with the rotating crankshaft. Found on the sides of keyway  22  are two sensors  24  that detect whether alignment bar  30  is in the up position or the down position through the use of upper limit switch  34  which indicates alignment bar  30  is up, and lower limit switch  32  which indicates that alignment bar  30  is down and engaging eccentric bushing  20 , as shown in FIG. 3 a . Not shown in the figures is a keyway on both sides of connection member  10 . Alignment bar  30  can be a U-shaped bar to engage a similar keyway on the opposite of connection member  10 . 
     FIG. 3 a  depicts the invention with alignment bar  30  lowered into keyway  22  and engaged within eccentric bushing  20  for press stroke adjustment by hydraulic oil pressure as described in U.S. No. Pat. 5,865,070 entitled “Adjustable Stroke Connection”. As depicted in FIG. 3 a , alignment bar  30  has been lowered into keyway  22  by double acting cylinder  28 , shown in FIGS. 1 and 4, so as to affix alignment bar  30  into eccentric bushing  20  to make stroke adjustments. The mechanical press is stopped and crankshaft eccentric  18  and eccentric bushing  20  are aligned on top with keyway  22  in alignment with alignment bar  30 . A double acting cylinder  28  pushes alignment bar  30  into keyway  22  of eccentric bushing  20  and electric sensor  24  detects when lower limit switch  32  indicates alignment bar  30  is in the proper position. In this position, eccentric bushing  28  and the cap of connection member  10  are all locked together. The chamber (not shown) inside eccentric bushing  20  is pressurized relieving the press fit between crankshaft  14  and eccentric bushing  20 , and creating the press fit between the cap  16  of connection member  10  and eccentric bushing  20 . At this time, crankshaft  14  can be rotated to whatever desired stroke position is desired and need in the press operation. Once the desired stroke position is obtained, the high pressure oil (not shown) between eccentric bushing  20  and crankshaft  14  is halted thereby creating the clearance between connection member  10  and eccentric bushing  20 . Double acting cylinder  28  can be energized raising alignment bar  30  (as shown in FIG. 3 b ) until upper limit switch  34  activates sensor  24  putting alignment bar  30  into the position depicted in FIG. 3 a . Spring  26  additionally holds alignment  30  in the up position during mechanical press operation. 
     While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This patent application is therefore intended to cover any variations, uses, or adaptations of the present invention using its general principals. Further, this patent application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.