Abstract:
A plurality of spaced apart supports are designed to closely support a work piece immediately adjacent the edge being worked, ground or polished. Adjacent shear forced are also eliminated by the use of a polymeric interconnections used to both generally contribute to the spacing and to transmit the vacuum in a distributed manner among the individual support units. The top and bottom surfaces of the supports are dressably machineable in place on the working table to insure that all are brought to exactly the same height to insure even support, and utilize a hardened rubber, or any other suitable machinable material which will not enable the work piece to displace significantly downwardly upon the application of vacuum. The tops and bottoms, as a group, are selectively operable. The ability to periodically dress both ends of the interconnected supports gives the user the power to continually insure that each interconnected support set is within a more exacting vertical tolerance. Further, the machineable ends can be removed and replaced.

Description:
FIELD OF THE INVENTION 
     The present invention relates to improvements in the field of work piece holding devices for machines. More specifically, the present invention relates to a multi-element vacuum hold down device which contains upper and lower dressable surfaces and a flexible vacuum transmission web in between the multiple elements and which is useful in supportably working thinner materials, especially for downward beveling grinding forces without failure or with extremely reduced incidence of failure. 
     BACKGROUND OF THE INVENTION 
     In many instances, it is necessary to locate, position and support a work piece which is to be milled, sanded, ground, etc. The precision and stability of the positional device is important, as is the ability to re-position the positional device. Positive location of work pieces which are relatively thick are described in U.S. Pat. No. 6,186,567 to John Blick entitled “Locator and Hold Down system for a Machine” which describes an integrated system for using multiple holders. A system for positive location and support of thin work pieces are described in U.S. Pat. No. 6,286,822 to John Blick entitled “MACHINABLE SUPPORTS FOR CLOSE TOLERANCE EDGE SUPPORT” and describes an integrated system for using multiple separately locatable holders where each holder has a base of sufficient dimension to both support and allow a user integrated placement of each separate holder. Pre-selected variations on shape degree of rigid spaced multiplicity were illustrated. 
     U.S. Pat. No. 5,433,657 to Luigi Bovone issued on Jul. 11, 2001 and entitled “DEVICE FOR FIXING AND MAINTAINING SHAPEABLE GLASS PLATES IN POSITION DURING THEIR MACHINING” discloses a rigidly pivotable series of fixed suction support elements having upper and lower vacuum areas for fixture to a work piece and a work table, respectively. However, the relationship between the suction support elements is based upon a complex hinge arrangement with machined passages in both the elements and the hinge portions. This arrangement is expensive and requires precision measurements both to make absolutely certain that the upper and lower vacuum support element are flush to the floor and work piece surface, as well as to insure that the hinge clearance is so closely tolleranced as to prevent undue vacuum degradation from leakage into the device. 
     The device of Bovone is heavy, bulky and difficult to place precisely about a work piece. Further, the Bovone device is not dressable to enable a greater precision of formation of the sealing and working height. Bovone recites “suckers” 11 which have no other further specification. The Bovone reference appears to indicate that “suckers” are metal structures. Thus height is controlled, but vacuum is not. Any nick on the “suckers” will cause further loss of vacuum. As a result, the structure of Bovone would have to be treated especially gently during handling. 
     Another problem with Bovone relates to the relatively rigid hinging between his support elements. Any twisting of the Bovone assembly, especially during handling could cause the entire series of supports to “bind”. Where one end of the supports was angled with respect to the others, or where the hinge axis was shifted through mishandling, the angularity of the individual support elements could be forcibly mis-aligned as dictated by the tight hinge relationship between the individual support elements. 
     What is therefore needed is a support specially formulated to closely support a thin work piece near its edge, and which provides a series of independent vacuum support elements, which is precision dressable, and which can provide even, secure support to a work piece. 
     SUMMARY OF THE INVENTION 
     The devices and systems of the present invention encompass the provision of a plurality of spaced apart supports specially designed to closely support a work piece immediately adjacent the edge being worked, ground or polished, but especially an edge which is being beveled or some other type of material process where downward force is applied to the edge of the work piece. The top and bottom surfaces of the supports are machineable in place on the working table to insure that all are brought to exactly the same height to prevent adjacent supports from creating uneven support and adjacent shear forces. Adjacent shear forced are also eliminated by the use of a polymeric interconnections used to both generally contribute to the spacing and to transmit the vacuum in a distributed manner among the individual support units. 
     The top and bottom members of the supports are a hardened rubber, or any other suitable machinable material which will not enable the work piece to displace significantly downwardly upon the application of vacuum but which will provide a vacuum downward force from the work piece to the support and from the individual supports to the work table surface. 
     The hardened rubber top of the edge hold down are machinable without losing the ability to act as a vacuum hold down. Such machinability is often referred to as “dressability” and enables significant advantages along with the fact that the top and bottom of the individual supports are selectively operable. 
     A given set of interconnected supports can a selective vacuum applied to hold the sit of interconnected supports to the work table. The upper surfaces can be dressed. The same set of interconnected supports can be turned over with the now bottom ends of the interconnected supports held fast to the table to enable precision dressing of the now upwardly exposed surfaces. 
     The ability to periodically dress both ends of the interconnected supports gives the user the power to continually insure that each interconnected support set is within a more exacting vertical tolerance. The machineable ends can be removed and replaced. This will enable a user to insure that all of his supports are exactly the same height by having the ability to re-dress end contact support ends upon replacement. 
     Replacement of the dressable ends will typically be had for long term wear, and it is contemplated that where all the supports and support sets are dressed over time that the dressing operation will result in an updated new height figure which will be taken to account by an automated system in computing the heights of the grinding spindle. 
     Further, the support sets can be of various unit lengths to reduce the necessity for individual vacuum line connections. For example, a work piece having a 5 foot circumference could be served by a first set of supports having a length of three feet and a second set of supports having a length of two feet. 
     A collection of working support sets could be employed including several three to four foot lengths, several two foot lengths and several one foot lengths. Since each working support set shares an independently actuatable upper and lower vacuum actuation possibility, each working support in each set needs to be vacuum engaged at both ends. In other words, both ends of all the supports need to be engaged between the work piece and the work table. In the given lengths of the working support sets, supports which are in excess of the numbers needed to completely support the periphery of the work piece can be aligned to extend to the vast areas within the periphery of the work piece. 
     As a result, the user selected limitations of the supports within a given length of the set of working supports will only be limited by a user preference on the overall weight of the set to be moved about for a new setup and the numbers of vacuum lines for which independent control of each support set is desired. 
     Further, and since each work piece setup typically involves pulling a vacuum about the complete periphery simultaneously, the working support sets can be serially interconnected from one working support set to another so that actuation of a single working table vacuum connection will create a working table vacuum for all working support sets, and the actuation of a single work piece vacuum connection will create a work piece vacuum for all working support sets. Thus the only limitation should be a user limitation on the number of support units within a set based purely upon handling preferences. 
     Finally, the most impactive aspect of the work piece support set is its simplicity of design, standardization of component parts which translates into further utilization and facilitation of maintenance. Each support contains about ten basic components, of which four are identical, resulting in only six unique components per support. The support within each set which accepts vacuum will have two additional hose tap connectors. The end supports may also include a pair of set screws to block the further transmission of vacuum where the polymeric sleeve has openings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention, its configuration, construction, and operation will be best further described in the following detailed description, taken in conjunction with the accompanying drawings in which: 
     FIG. 1 is a perspective exploded view looking down at a single vacuum support of a series of vacuum sports used in the vacuum support set of the invention; 
     FIG. 2 is an assembled view of the single vacuum support seen in FIG. 1; 
     FIG. 3 is a perspective view of a support set containing twelve interconnected supports and in which the vacuum port connections are mounted in one of the supports, third from the left from the perspective of the viewer; 
     FIG. 4 is a side sectional view taken along line  4 — 4  of FIG.  3  and illustrates the internals of the support having vacuum port connections; and 
     FIG. 5 is a perspective drawing of a vacuum supported piece of glass and illustrating a distributed vacuum connection between two sets of supports. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The description and operation of the invention will be best described with reference to prior art FIG. 1, which is a downward perspective exploded view of a single one of the double ended edge vacuum hold down supports  21 , hereinafter referred to as a support element  21 . Support element  21  includes a body  23  having a main cylindrical extent  25  and a pair of vacuum communication ports including an upper vacuum communication port  27  and a lower vacuum communication port  29 . Ideally the ports  27  and  29  will include a straight through bore access extending straight through the body  23  and out the other side. This will especially be the case if support  21  is to both receive and upper and lower vacuum and to transmit both upper and lower vacuum to the next adjacent support  21 . 
     Typically, the ports  27  and  29  will be threaded to enable them to be plugged with a threaded plug member  30  so that a user can selectively block entry into the body  23 . This is desired where a user may have a set of supports  21  webbed together and want to effectively shorten the set by excising other supports  21 . Where connections to the ports  27  and  29  are exposed, the threaded plug members  30  can be used to seal one side of the support  21 . 
     The support has an upper annular cup shape which includes, from the main cylindrical extent  25 , a radially outwardly extending surface  31 , an outward radial surface  33 , and an upper circumferentially outermost surface  35 . A second circumferentially inward surface  37  is separated from outward radial surface  33  by a slot  39 . Surface  37  is shown as generally even with surface  35 . At the center of surface  37  a threaded bore  41  is seen. 
     Threaded bore  41  is in fluid communication with upper vacuum communication port  27  and a port on the opposite upper side of body  23 . The bottom half of body  23  is a mirror image of the top half of body  23  and thus a threaded bore identical to threaded bore  41  is in fluid communication with lower vacuum communication port  29  and another port on the opposite upper side of body  23  (in alignment generally with port  29 ). 
     The details of the bottom half of body  23  which can be seen are a radially outwardly extending surface  43  and an outward radial surface  45 . 
     Again referring to FIG. 21, the next component seen immediately above body  23  is a flexible elastomeric annular sleeve  51  having a cylindrical body portion  53  and one or two side web portions  55 . Web portions  55  each support an upper vacuum channel  57  and a lower vacuum channel  59 . At the point of approach of the cylindrical body portion  53 , the vacuum channels  57  and  59  communicate with upper aperture  61  and lower aperture  63  which enable a fluid communication from the vacuum channels  57  and  59 , through the upper and lower apertures  61  and  63  and into an inside bore  65  of the cylindrical body portion  53 . 
     When the cylindrical body portion  53  is fitted over the body  23 , the apertures  61  and  63  align with the upper and lower vacuum communication ports  27  and  29  respectively. A second web portion  55  extending to the left also includes the upper vacuum channel  57 , and lower vacuum channel  59 , as well as apertures  61  and  63  for communicating with the upper and lower vacuum communication ports on body  23  not seen in FIG.  1  and which are in communication with the ports  27  and  29 . 
     The fitting of the cylindrical body portion  53 , one or two side web portions  55 , and upper and lower vacuum channels  57  and  59  is preferably done by molding. The material of choice is urethane which may be pumped around a mold cavity containing the aligned support bodies  23  with appropriate structures to form the side web portions  55 , and upper and lower vacuum channels  57  and  59 . 
     Where the element  21  is a terminal element, the left side web portion  55  may be eliminated. In other instances it may be excised from the cylindrical body portion  53  and the upper and lower vacuum communication ports corresponding to ports  27  and  29  respectively can be plugged with a threaded member. 
     Shown above the flexible elastomeric annular sleeve  51  is an “o” ring seal  71  for interfitting within the slot  29  and sealing against a plate  73  shown above the “o” ring seal  71 . The plate  73  generally conforms to the round shape of the end of the body  23 . Above the plate  73  is a hardened rubber dressable member  75 , which can be made of any hard rubber capable of being machined, or any other suitable machinable material which will not enable a work piece to displace significantly downwardly upon the application of vacuum but which is flexible enough to provide a vacuum force. It is preferable for the hardened rubber dressable member  75  to be vulcanized to the upper surface of the plate  73  such that any additional hold down forces on the hardened rubber dressable member  75  will not be necessary. 
     The dressable member  75  has an upper annular surface  77  and an inner lower height annular surface  79 . Inner lower height annular surface  79  surrounds an aperture  81 . The thickness or height of the upper annular surface  77  above inner lower height annular surface  79  is the height of material which is available for precision dressability. Once the dressable member  75  upper annular surface  77  is worn, ground or cut away to the level of the inner lower height annular surface  79 , the dressable member  75  should be replaced. 
     Above the dressable member  75  is a threaded member  85  having a threaded shaft  87  and a flat head  89  with a shaped opening  91 , typically a hexagonal opening for operation with a hex wrench. The shaped opening  91  is in communication with a bore (not seen in the threaded member  85  shown in the upper portion of FIG. 1) which extends completely through to the end of the shaft of the threaded member  85 . 
     Beginning at the bottom of the body  23 , an identical set of components seen above the flexible elastomeric annular sleeve  51  are seen as “o” ring seal  71 , plate  73 , hardened rubber dressable member  75  (seen from its bottom side), and threaded member  85  with its threaded shaft  87 , flat head  89  and a bore  93  which extends through to its shaped opening  91  (not seen in FIG.  1 ). Threaded member  85  through bore  93  enables it to transmit vacuum through to the space between inner lower height annular surface  79  and either a work piece surface or a support surface. 
     The threaded member  85  pulls the plate  73 , which holds the hardened rubber dressable member  75 , against the “o” ring seal  71  and into the slot  39 . The combination enables vacuum source from the threaded bore  41  to be effectively communicated to the space between upper annular surface  77  and inner lower height annular surface  79 . 
     Referring to FIG. 2, an assembled view of the single vacuum support seen in FIG. 1 is seen from a perspective view, but absent the left side is a web portion  55 , the upper and lower vacuum channels  57  and  59 , associated apertures  61  and  63  and the upper and lower vacuum communication ports  27  and  29  which would be associated with the left side of the support  21 . 
     As such, the support seen in FIG. 2 is an end support  101 . Further, where the flexible elastomeric annular sleeve  51  has a cylindrical body portion  53  which covers over both the upper and lower vacuum communication ports  27  and  29 , it may not be necessary to provide threaded plugs into the upper and lower vacuum communication ports  27  and  29  to prevent loss of vacuum. 
     Referring to FIG. 3, a perspective view of a support set  111  containing twelve interconnected supports, including two end supports  101 , nine supports  21 , and a service support  113 . Service support  113  differs from the supports  21  in that it has a pair of side fittings for the application of a vacuum source into the entire set  111 . An upper threaded hose insertion fitting  115  supplies vacuum to all of the upper hardened rubber dressable members  75  seen in FIG. 3, remembering that the set  111  need only be inverted for the upper hardened rubber dressable members  75  to become lower hardened rubber dressable members  75 . A lower upper threaded hose insertion fitting  117  supplies vacuum to all of the lower hardened rubber dressable members  75  seen in FIG.  3 . 
     FIG. 4 is a side sectional view taken along line  4 — 4  of FIG.  3  and illustrating the internals of the service support  113  in its working position to further facilitate the explanation of the action of its vacuum connections. In normal engagement, the set  111 , of which one support  113 , the vacuum service support  113 , is a member is situated between a work piece  121  and a working table surface  123 . 
     Beginning at the top. A vacuum space  125  is created between the work piece  121  and the inner lower height annular surface  79  and flat head  89  of the threaded member  85 . The diameter of the extent of the inner lower height annular surface  79  is from about one to two inches and provides a significant downward holding force on the work piece  121 . Engagement of the work piece  121  is had by the upper annular surface  77  of the hardened rubber dressable member  75 . 
     As can be seen, the hardened rubber dressable member  75  is vulcanized directly to the plate  73 . A gap  127  exists between the aperture  81  of the hardened rubber dressable member  75  and the flat head  89  of the threaded member  85 . As can be seen, any leakage between the head  89  and the plate  73  to the outside is not possible because of the “o” ring seal  71 . 
     The upper and lower threaded hose insertion fittings  115  and  117  have threaded portions which engaged threaded bores in the body  23 . The upper threaded hose insertion fitting  115  is in communication with an upper chamber  131  which is also in connection with aperture  61 . The lower upper threaded hose insertion fitting  117  is in communication with a lower chamber  135  which is also in connection with lower aperture  63 . Note that upper chamber  131 , upper aperture  61  and upper threaded hose insertion fitting  115  are all completely isolated from lower chamber  135 , lower aperture  63  and lower threaded hose insertion fitting  117 . This enables all of the upper ends of the supports  21 ,  101  and  113  within set  111  to have a vacuum applied independently of the lower ends of the supports  21 ,  101  and  113  within set  111 . 
     The same structures are seen below chamber  135  as were seen above upper chamber  131 . It is understood that for both the service support  113  and the support  21  that the upper and lower apertures  61  and  63 , respectively will be oriented for a straight pass through and would be seen to align with the upper and lower apertures  61  and  63  of the service support  113  and the support  21 . The end support  101  would have upper and lower apertures  61  and  63  typically in only one side of the main cylindrical extent  25  of body  23 . 
     However, the end support  101  may also have threaded plugs placed in the threaded upper and lower apertures  61  and  63 . This brings up one of the strongest points to be made in the system which comprises the support sets  111 , which is their modularity. As can be seen, the number of parts for an individual support of support sets  11 , excluding the cylindrical body portion  53  and side web portions  55 , and considering the parts including plate  73  and hardened rubber dressable member  75  to be a single unit, to be four in number. 
     As a result, the system disclosed is easily maintained with a lesser number of different parts to maintain, stock and to buy. Further, by providing a lower vacuum supportability independent from the upper vacuum supportability, the support set  111  can be machine dressed while in place on the working table  123 . Such dressing in place is not only able to be performed more quickly, but enables the machine performing the dressing function to store the current height of the support sets  111  which should all be the same height. Thus it is recommended that a re-dressing operation be performed on all support sets  111  which could be used on a particular work table  123 . 
     Referring to FIG. 5, a perspective drawing of a vacuum supported piece of glass (for see through clarity) as a work piece  121  is shown as supported by a set of three support sets  111 . FIG. 5 also illustrates the vacuum distributability for a pair of support sets  111 . A pair of vacuum hoses including an upper vacuum hose  141  and a lower vacuum hose  143  each extend to a “t” fitting  145  and a “t” fitting  147 , respectively before extending through to connection to upper and lower threaded hose insertion fittings  115  and  117 . From the “t” fitting  145  and  147 , respectively, looping vacuum hoses including an upper vacuum hose  151  and a lower vacuum hose  153  fittings extend to upper and lower threaded hose insertion fittings  115  and  117  of another support set  111 . By using “t” fittings  145  and  147 , any work table  123  can have its support sets  111  controlled with a single pair of (preferably independently actuated) vacuum hoses. 
     In instances where the support sets  111  have been dressed and where it is possible or acceptable to actuate both top and bottom vacuums simultaneously, looping can also be accomplished between the upper and lower vacuum hoses  141  and  143  so that the system of support sets  111  can be actuated with a single vacuum hose. 
     While the present invention has been described in terms of a device and system used in conjunction with securing close edge support work pieces for all types of process machinery, and in particular with machinery for the milling, edging and machining of materials including glass, granite, marble, stone, and the like, one skilled in the art will realize that the structure and techniques of the present invention can be applied to many appliances. The present invention may be applied in any situation where the position of relatively less thick work pieces is desired to be precisely secured to reduce breakage and to reduce lost time. 
     Although the invention has been derived with reference to particular illustrative embodiments thereof, many changes and modifications of the invention may become apparent to those skilled in the art without departing from the spirit and scope of the invention. Therefore, included within the patent warranted hereon are all such changes and modifications as may reasonably and properly be included within the scope of this contribution to the art.