Abstract:
A materials handling apparatus and method utilizing flotation pads to inject a thin fluid film to produce a near frictionless surface for easily positioning and finishing foundry castings. The present invention further relates to a material handling apparatus and method utilizing a vacuum lock to serve as a vice for securing foundry castings or other work pieces during finishing stages. The invention further incorporates an apparatus and method for protecting the vacuum lock components from damage or interference with material movement during positioning.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a material handling apparatus and method, in particular a material handling apparatus and method utilizing a thin fluid film to produce a near frictionless surface for easily positioning and finishing foundry castings. The present invention further relates to a material handling apparatus and method utilizing a vacuum lock device to serve as an anchor for securing foundry castings or other work pieces to a work surface during finishing stages. The present invention further relates to an apparatus and method of protecting the components of the vacuum lock device from damage or interference with positioning of the material. 
     BACKGROUND OF THE INVENTION 
     Parts made by various casting techniques have some form of excess material, which must be removed from the object during finishing. In many instances it is often desirable to perform additional machining on cast pieces during the finishing process. In the finishing of metal parts in particular, the work objects are often very heavy, making it difficult to position these items without mechanical assistance. Even with mechanical assistance, it is often difficult to accurately position a work piece in proper relation to grinders, cutting wheels, drill presses, or other machining tools. Once positioned, work pieces must be secured in place during machining. Worker fatigue and injury can result from the worker attempting to position heavy work pieces during materials finishing processes. Workers may also be injured when they attempt to secure work pieces in place during machining. Improving the ease and speed of work piece aligmnent, providing greater tooling accuracy, improving worker safety, and improving equipment reliability are still possible and desired. 
     SUMMARY OF THE INVENTION 
     It is the object of the present invention to provide a material handling apparatus and method that combines ease of movement, alignment, and securement of heavy work pieces during materials finishing processes. Each of these characteristics enhances worker safety by reducing exposure to hazards associated with handling materials during finishing processes. 
     Ease of movement is achieved by the injection of a pressurized fluid through the flotation pad of the present invention. Injection of the pressurized fluid produces a thin fluid film surface between the flotation pads of the present invention and a table surface at a finishing process station. The thin fluid film provides a nearly frictionless bearing surface, which permits the easy movement of even the heaviest work pieces. 
     Ease of alignment is achieved by the flotation pad&#39;s ability to translate the work piece throughout the horizontal plane defined by the finishing process table. In addition, the flotation pad permits rotation of the work piece about a vertical axis relative to the float pad. 
     Once a work piece is positioned, a vacuum source may be applied to the flotation pad. The vacuum source removes the thin fluid film surface from between the flotation pad and the finishing process table surface, thereby removing the frictionless surface. Additionally, to achieve a substantially stronger bond, a seal on the lower surface of the flotation pad mates with the finishing station table surface forming a vacuum lock between the flotation pad and the finishing station table surface. 
     While the seal on the lower surface of the flotation pad permits the vacuum lock features described in the proceeding paragraph, the seal is subject to damage or may interfere with the nearly frictionless movement of the work piece if the seal is not adequately raised from the table surface when the flotation pad is pressurized. These problems are avoided by the sliding engagement of a flotation pad disk within the flotation pad skirt during pressurization and vacuum cycles. During pressurization, the flotation pad disk extends beyond the lower face of the seal, which in combination with the thin film surface, provides the clearance necessary to avoid seal contact with the table surface. When a vacuum is applied to the flotation pad, the flotation pad disk is drawn into the flotation pad skirt, permitting formation of the vacuum lock. 
     Thus, in addition to positioning a work piece in an infinite number of orientations, the present invention also provides for rapidly securing the work piece in any of the previously mentioned orientations, while protecting the seal from damage or interference with work piece positioning. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Apparatus embodying features of my invention are depicted in the accompanying drawings which form a portion of this disclosure wherein: 
     FIG. 1 is a side elevation view of a table mounted cut-off machine with an air float positioning table; 
     FIG. 2 is a side cross sectional view of a float pad in a neutral position; 
     FIG. 3 is a side cross sectional view of a float pad in response to a pressurized fluid source applied to the fluid port; and 
     FIG. 4 is a side cross sectional view of a float pad in response to a vacuum attached to the fluid port. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings for a clearer understanding of the invention, it may be seen in FIG. 1 that the apparatus includes a frame  11 , which supports a substantially horizontal flat surface  12 , a compressed air source  13 , a vacuum source  14 , and in this embodiment a cut-off saw  15 . 
     Substantially horizontal flat surface  12  is surrounded by a raised lip  16 , which prevents the gondola  17  from sliding off the flat surface  12 . In this embodiment, the gondola  17  has three flotation pads  18  attached to the lower surface of the gondola  17  in substantially isosceles triangular arrangement. The gondola also has a jig  19  for holding the work piece P in place on the gondola  17 . 
     When the compressed air source  13  is applied to the flotation pads  18  via a flexible conduit  20 , as is well known in the art, a thin fluid film layer  34  is formed between the float pad  18  and the flat surface  12 . The thin fluid film layer  34  provides a virtually frictionless bearing between the flotation pads  18  and the flat surface  12 . The gondola  17  holding the work piece P may then be easily positioned under the cut-off saw  15 . Once in position the compressed air source  13  is removed from the float pads  18 . 
     The gondola  17  holding the work piece P may then be further adjusted in position against normal frictional forces between flotation pads  18  and flat surface  12 . When the work piece P is in final position for cutting, a vacuum source  14  is applied to the flotation pads  18  locking the float pads  18  and hence the gondola  17  and work piece P in place for cutting with cut-off saw  15  to trim excess material or otherwise finish the work piece P. 
     A foot switch  21  may be used to control the vacuum  14  and compressed air  13  source applied to the flotation pads  18 . 
     In the presently described embodiment, it is the operation of float pads  18  which perform the foregoing described features of the overall apparatus. The remaining figures diagram the operation of the float pads  18  in response to vacuum  14  and compressed air  13  sources. 
     As may be seen from FIG. 2, each flotation pad  18  comprises of a float pad seal skirt  22 , a floatation pad seal skirt O-ring  33 , a float pad disk  23 , a fluid port  24 , a swivel mount  25 , and a bolt  26  for securing the float pad disk  23  to swivel mount  25 . By this arrangement float pad seal skirt  22  is permitted to reciprocate upwardly or downwardly in response to pressurization and depressurization of fluid port  24 . 
     The float pad seal skirt  22  comprises a lower recessed area  27  defined by a circular downwardly extending annular flange  28 , a central bore  29 , and a fluid port  24 . The downwardly extending annular flange  28  further comprises an inner face  30  and a bottom face  31 . A double tapered annular groove  32  on the seal skirt bottom face  31  receives an o-ring  33  in captive engagement therein. Central bore  29  is of substantially smaller diameter than the lower recessed area  27 . 
     The float pad disk  23  comprises an upper disk surface  42  having an integral cylindrical shaft  35  extending upwardly from the center of the float pad disk  23 . The cylindrical shaft  35  having a diameter such that it is slidably received within the central bore  29  of the seal skirt  22 . Cylindrical shaft  35  further comprises an outer annular groove  36 , which receives an o-ring  37  therein, and an inner bore  45  of varied diameters to accept securing bolt  26 . O-ring  37  provides sliding sealing engagement with the seal skirt central bore  29 . 
     The float pad disk upper surface  42  further comprises an annular groove  38 . Fluid jets  39  are evenly spaced around annular groove  38  such that they are in fluid communication with the annular groove  38  and extend through the float pad disk  23  to the float pad disk lower surface  40 . Fluid jets  39  are dimensioned such that they have a combined cross sectional surface area substantially smaller than the cross sectional surface area of fluid port  24 . 
     The outer circumferential surface  41  of float pad disk  23  is dimensioned such that it is slidingly accepted within the lower recessed area  27  of the float pad seal skirt  22 . The upper and lower edges of the outer circumferential surface  41  are chambered to facilitate the sliding engagement of the float pad disk  23  in the lower recessed area  27  of the float pad seal skirt  22 . An annular groove  43  in the outer circumferential surface  41  accepts an o-ring  44  for sliding sealing engagement with annular flange inner face  30 . 
     The thickness of the float pad disk  23  is dimensioned such that when it is completely engaged in lower recessed area  27 , float pad seal skirt o-ring  33  extends beyond the lower surface  40  of the float pad disk  23 . 
     FIG. 2 depicts, a flotation pad  18  in a neutral position, i.e. without a vacuum  14  or compressed air source  13  applied. 
     FIG. 3 depicts a flotation pad  18  with a pressurized air source  13  connected to fluid port  24 . The pressurized air  13  enters fluid port  24 , which is in fluid communication with annular groove  38  on the upper surface  42  of the float pad disk  23 . Float pad disk o-rings  37  and  44  contain the compressed air  13  within lower recessed area  27 . The compressed air  13  pressurizes the recessed area  27  forcing seal skirt  22  upward. Swivel mount  25  limits the travel of seal skirt  22  such that float pad seal skirt o-ring  33  is raised from the substantially horizontal flat surface  12  protecting o-ring  33  from damage and preventing o-ring  33  from interfering with float pad  18  movement across flat surface  12 . 
     Simultaneously with seal skirt  22  lifting, compressed air  13  passes through fluid jets  39  introducing a thin fluid film layer  34  between flotation pads  18  and flat surface  12 . The presence of thin fluid film layer  34  provides a near frictionless bearing surface. Work piece P is mounted in gondola  17 , and is supported by the fluid film layer  34 , allowing ready translation of the work piece P across flat surface  12 . 
     When compressed air source  13  is removed from fluid port  24  the flotation pad returns to the neutral condition depicted in FIG.  2 . Upon removal of compressed air source  13  thin fluid film layer  34  to quickly dissipates. The absence of the thin fluid film surface  34  returns normal frictional interference between float pad disk lower surface  40 , seal skirt o-ring  33 , and flat horizontal surface  12 . Upon depressurization float pad seal skirt  22  moves downwardly urging seal skirt o-ring  33  against flat surface  12 , conforming to the surface thereof, permitting the formation of a locking vacuum seal upon application of vacuum source  14  at fluid port  24 . 
     FIG. 4 depicts the operation of flotation pad  18  in response to vacuum  14 . Application of vacuum  14  to fluid port  24  evacuates any residual fluid film surface  34  between flat surface  12  and flotation pad  18 . As further vacuum  14  is applied, float pad disk  23  is drawn into recessed area  27  engaging float pad seal skirt o-ring  33  with flat surface  12 , forming vacuum chamber  48  within the area defined by float pad seal skirt o-ring  33 , flat surface  12 , and vacuum source  14 . The vacuum forces lock the float pads  18  and thereby gondola  17  in position while cut-off saw  15  removes excess materials or otherwise finishes work piece P. 
     It is to be understood that the form of the invention as shown herein is a preferred embodiment thereof and that various changes and modifications may be made therein without departing from the spirit of the invention or scope as defined in the following claims.