Abstract:
A lubrication vacuum system for a press includes a vacuum operated fluid leakage collector having a first vacuum device attached to the drive piston of the press, a wiper attached to the frame of the press and in surrounding relationship with the drive piston, and a second vacuum device attached to the frame of the press and adjacent the wiper. Alternately, a third vacuum device can be added adjacent the seal. Still alternately, the first vacuum device can have an inclined slope on its top surface for directing lubrication oil to the vacuum port.

Description:
CONTINUATION DATA  
         [0001]    The present application hereby claims the benefit under Title 35, United States Code §119(e) of U.S. provisional application No. 60/312,912 filed Aug. 16, 2001.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    This invention relates to a lubrication vacuum system for a press, and, more particularly, to a vacuum operated fluid leakage collector system that includes a vacuum device adjacent to a piston wiper and a second vacuum device secured to the piston.  
           [0004]    2. Description of the Related Art  
           [0005]    In machines having relatively movable parts, and particularly in certain mechanical presses having a piston which protrudes from the bottom of a crown, a flexible seal is generally carried by the crown in a surrounding and sealing relationship with the outer surface of the piston. Lubricating fluid facilitates a sliding relationship between the piston and the seal, and the seal substantially prevents the loss of the lubricating fluid from the crown which would otherwise result in the contamination of work pieces below.  
           [0006]    Seal damage due to installation, contamination, corrosion, or seal compression can occur rapidly or gradually in a mechanical press, eventually degrading the seal&#39;s ability to retain lubricating fluid within the crown. With continued press use, seal degradation leads to fluid accumulation about the seal, and fluid eventually reaches the stamped work pieces, thus ruining the product and increasing production costs.  
           [0007]    Accumulation of lubricating fluid about a piston is also undesirable because it reduces the amount of fluid that is available for lubricating purposes and necessitates the addition of lubricating fluid to the machine. Furthermore, it is advantageous to keep the machine exterior free from lubricating fluid so that dust and dirt do not accumulate, and to keep any other preferably dry members in the vicinity free from the fluid.  
           [0008]    It is therefore desirable that lubricating fluid be contained within a piston housing, thereby avoiding fluid accumulation on an external portion of the piston, and it is a principle object of the present invention to provide an arrangement that accomplishes that result.  
           [0009]    Certain prior art arrangements have addressed this issue by securing a vacuum device to the crown at a point immediately below the seal for vacuuming excess lubricating fluid from the piston when seal leakage occurs. This arrangement is disadvantageous because during operation the crown tends to be susceptible to thermal expansion, resulting in unwanted gaps between the piston and the crown-mounted vacuum, or in other cases, resulting in scores in the piston because the vacuum device expanded into the piston. Meanwhile, efficiency of the vacuum device is negatively affected by the variations in spacing between the piston and the vacuum device.  
           [0010]    Other prior art has utilized a wiper apparatus above the seal, resulting in a pool of oil above the seal. This arrangement is disadvantageous because the oil collects above the seal and ultimately promotes excessive leakage around the seal.  
         SUMMARY OF THE INVENTION  
         [0011]    The present invention overcomes the disadvantages inherent in prior art oil control systems by providing a vacuum device secured to the piston below the piston seal and a second vacuum device and wiper combination secured above the piston seal. This arrangement is advantageous because it provides a lower concentration of oil around the piston seal, and provides a vacuum below the seal that is not susceptible to thermal expansion due to its mounting on the piston.  
           [0012]    The present invention is directed to a lubrication vacuum system for a machine press wherein a seal is provided about the drive piston for preventing migration of lubricating oil from the press crown to the slide or to the product worked on by the press. In the invention, a first vacuum device is mounted to the piston below the seal, and a wiper apparatus is secured above the seal and proximal to a second vacuum device. The first vacuum device can also include an inclined upper surface for drawing oil into an annular opening on the vacuum device adjacent the drive piston.  
           [0013]    Alternatively, yet a third vacuum device can be provided, the third vacuum device being positioned below the seal, and attached to the crown. The third vacuum device can be spaced from the piston to accommodate for thermal expansion because the piston-secured vacuum device will operate to remove excess oil.  
           [0014]    An advantage of the lubrication vacuum system of the present invention is the repositioned wiper above the piston seal. The elevated position of the wiper in combination with the adjacent second vacuum device eliminates the pooling of excess oil on top of the piston seal, thereby allowing the piston to run “dryer” and keeping oil loss at an optimal minimum.  
           [0015]    A further advantage of the lubrication vacuum system of the present invention is the mounting of the first vacuum device on the piston. By mounting this vacuum device on the piston, the present invention is able to maintain optimal vacuum capabilities below the piston seal despite thermal expansion. While the crown of the press often reaches high temperatures, the piston typically maintains a relatively constant temperature. Therefore, mounting the vacuum device to the piston resolves inefficiencies and excessive wear due to the expansion and contraction of a crown-mounted vacuum housing.  
           [0016]    A still further advantage of the lubrication vacuum system of the present invention is the inclined upper surface of the first vacuum device. This vacuum device is inclined such that oil drippings that land on the upper surface of the vacuum device are directed radially inwardly toward an annular opening proximally located to the piston periphery.  
           [0017]    Another advantage of the lubrication vacuum system of the present invention is that the oil is constantly coalesced and drained off while the lubrication vacuum system is in operation, providing an environment that is easily accessed for repair without the loss of significant amounts of oil. The oil is reclaimed and routed to a press oil reservoir eliminating the need to replace lost oil.  
           [0018]    Yet another advantage of the lubrication vacuum system of the present invention is control of the leaked oil is accomplished as long as there is a supply of air. Control and capture of oil does not depend on the total integrity of the piston seal, nor does it depend on the design or shape of the seal. Rather, oil collection only depends on the functionality of the press vacuums. This allows various seals and geometries of presses to be utilized with the invention.  
           [0019]    A further advantage of the lubrication vacuum system of the present invention is that the amount of air flow transporting the leaked oil can be adjusted depending on the oil leakage rate. Additionally, the oil can be evacuated from the seal area in this manner to clean the seal housing before service personnel open the press for repair. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    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:  
         [0021]    [0021]FIG. 1 is a front elevational view of a mechanical press incorporating the lubrication vacuum system of the present invention;  
         [0022]    [0022]FIG. 2 is a sectional view of one embodiment of the lubrication vacuum system as it would be applied within the crown of the press; and  
         [0023]    [0023]FIG. 3 is a sectional view of another embodiment of the lubrication vacuum system. 
     
    
       [0024]    Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0025]    As shown in FIG. 1, a typical mechanical press  10  comprises a crown portion  12 , a bed portion  14  having a bolster assembly  16  connected thereto and uprights  18  connecting crown portion  12  with bed portion  14 . Uprights  18  are connected to or integral with the underside of crown  12  and the upper side of bed  14 .  
         [0026]    A slide  30  is disposed between press uprights  18  as shown in FIG. 1. Slide  30  reciprocates within press  10  by the action of main drive motor  32  attached to the top portion of crown  12 . Connected to main drive motor  32  by means of a belt (not shown) and a hydraulic combination clutch/brake (not shown) is drive piston  34 , which drives slide  30 .  
         [0027]    The word “piston” utilized in this application identifies generally any member that slides or reciprocates within another. Specifically, the term “drive piston” relates to the portions of slide  30  that are parallel with slide movement.  
         [0028]    Seal members are known in the art and are used to seal about the drive piston to retain or divert lubricating oil in the event excess oil flows from the press crown. A lubrication vacuum system is also commonly used in conjunction with the seal member to generate negative pressure about the drive piston below the seal member in order to capture oil that leaks past the seal member.  
         [0029]    According to the present invention, and as shown in FIG. 2, a drive piston  34  is disposed for reciprocation within piston housing  42 . Piston housing  42  is attached to crown  12 . Located between piston housing  42  and drive piston  34  is a guide bushing  43  for maintaining adequate clearance between drive piston  34  and piston housing  42 . Seal  40  seals between drive piston  34  and piston seal housing  44 , and is seated in seal groove  37 .  
         [0030]    As shown in FIG. 2, a piston vacuum housing  46  is attached directly to piston seal housing  44 . An annular drain port  47  is connected to conduit  50  of piston vacuum housing  46 . Drain port  47  is utilized for catching leaking oil by virtue of the negative pressure created therein. Slots  998  allow for vacuuming oil from the piston side of seal  40  and wiper  99 . A clearance  49  is formed between vacuum housing  46  and drive piston  34 , which allows for thermal expansion of crown parts, while also allowing excess oil not captured by the vacuum system to run down the periphery of drive piston  34 .  
         [0031]    The present invention, as depicted in FIG. 2, relates to a piston-mounted vacuum housing  80  that places a negative pressure proximal to drive piston  34  to capture any oil that escapes vacuum housing  46  and runs down drive piston  34 . According to the invention, vacuum housing  80  is attached to the exterior of drive piston  34 , disposed between slide  100  and the piston  34 , and includes an annular drain port  86  located proximal to drive piston  34 . O-ring seal  89  provides a static sealing relationship between vacuum housing  80  and drive piston  34 , thereby directing any oil to drain port  86 . By virtue of the negative pressure created therein, drain port  86  catches leaking oil from the piston  34  and dripping oil from other press parts above. Located within vacuum housing  80  is a conduit  90  that connects to flexible conduit  91 , which in turn connects to the pneumatically-driven vacuum producing mechanism  60 A to be described below. Alternatively a vacuum drain as shown in U.S. Pat. No. 5,623,870 may also be utilized. During a seal leak, leaking oil will travel down the surface of drive piston  34  and be vacuumed either into drain port  47 , or into drain port  86 .  
         [0032]    In one embodiment of the invention, shown also in FIG. 2, a wiper  82  connected to a seal housing  44  is further provided for minimizing the amount of oil in contact with seal  40 . Seal housing  44  is secured to piston housing  42  which includes an annular drain port  92 , located proximal to wiper  82 . As piston  34  reciprocates, excess oil is collected from the surface of piston  34  by wiper  82 , and the collected oil travels to drain port  92  and is subsequently propelled through conduit  94  by a vacuum-induced liquid flow.  
         [0033]    In another embodiment, depicted in FIG. 3, upper surface  88  of vacuum housing  80  is inclined. Oil drippings originating from piston  34 , vacuum housing  46 , seal housing  44 , and piston housing  42  and elsewhere are collected by upper surface  88 , and directed to drain port  86  with assistance from housing lip  96  and inclined surface  88 .  
         [0034]    Additional oil control is provided by the bottom surface  48  of vacuum housing  46 . Surface  46  redirects dripping oil toward drain port  86 .  
         [0035]    By drawing off oil at two drain ports  47  and  86 , located below the seal, an oil leak is kept under control for all rates of possible leakage. Furthermore, the inclined upper surface  88  of vacuum housing  80 , as shown in FIG. 3, collects oil drippings from various press parts, thereby preventing contamination to stamped work pieces.  
         [0036]    An additional wiper  49  is disposed between drain housing  46  and piston  34 . Wiper  49  assists movement of oil toward drain port  47 .  
         [0037]    Oil and air are vacuumed into conduits  50  and  90  and proceed to the vacuum generator  60 A as described in U.S. Pat. No. 5,623,870 and then to press oil reservoir  56 . Oil vacuumed into conduit  94  by oil stream through  70  is sent directly to oil reservoir  56 . The vacuum-induced air and oil flowing through conduits  50 ,  90 ,  94  can be generated by any device as is known in the art, but in the particular embodiments shown in FIGS. 2 and 3, it has been found to be most reliably and efficiently generated by a device known as an ejector or jet pump  60 A air to air) or  60 B (liquid to liquid).  
         [0038]    The air flow through vacuum ejector  60 A is preferably kept on at all times, even while the press  10  is not running, so as to constantly evacuate any lubricating oil leaking from about seal  40 .  
         [0039]    In operation, the invention, in one form thereof, operates substantially as follows. During press  10  operation, power from motor  32  will be conducted via a crankshaft (not shown). Rotation of the crankshaft will cause a connecting rod (not shown) to change rotational motion of the crankshaft to rectilinear reciprocating motion of drive piston  34 . Seal  40  seals between reciprocating drive piston  34  and housings  44  and  46 .  
         [0040]    Referring to FIG. 3, any oil escaping past seal  40  along drive piston  34  will be caught in annular drain ports  47  and  86  connected to conduits  50  and  90 . Furthermore, inclined upper surface  88  of vacuum housing  80  collects oil drippings from various press parts, further preventing contamination to stamped work pieces. Bolt  101 , attaching vacuum housing  80  to slide  100 , is placed in bossed receiving hole  102 , so that oil does not transmit through the receiving hole  102 . Finally, piston seal housing  44  is used in combination with wiper  82  to minimize the quantity of oil in contact with the piston seal  40 , thereby allowing the system to run “dryer.” 
         [0041]    Compressed air is injected into the vacuum drain as described in U.S. Pat. No. 5,623,870, whereby a venturi effect is created in ejector  60 A, and a low pressure area will be developed in conduits  50 ,  90  connected to the vacuum drain through air inlet  68 . A combination of air and oil drawn through conduits  50 ,  90  is now caused to flow through ejector  60 A and into an oil demister assembly of U.S. Pat. No. 5,623,870 and then to reservoir  56 . Oil drawn through conduit  94  is now caused to flow through ejector  60 B and directly into reservoir  56 .  
         [0042]    The oil is contained in press oil reservoir  56 , while the air, now substantially free from entrained oil via an oil demister filter, is allowed to pass back to the ambient atmosphere.  
         [0043]    The amount of air flow transporting the oil can be adjusted for various leakage rates of seals  40  by opening and closing a regulator (not shown) to ejector  60 A. Further, oil control is accomplished as long as there is a supply of compressed air. Oil control of the present invention does not depend on 100% integrity of the seal or the intervention of the press operator. In addition, a liquid (oil) to liquid (oil) jet pump,  60 B, may be utilized to vary the suction rate at conduit  90 .  
         [0044]    The present invention, as shown in the previous embodiment, is not limited to oil control mechanisms located within the crown of a press. Depending upon the size of press  10 , the required tonnage and different operating mechanisms, different locations for a lubrication vacuum system are possible.  
         [0045]    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 application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this 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.