Abstract:
A method and auxiliary work piece table for enhancing the utility of a milling machine or the like machines. The lightweight auxiliary work table is installed onto an original work piece and providing the same mounting features as in the original work piece table after raising an overhead arm by installing a spacer on a support column. This restores the original vertical spacing to allow normal use of the milling machine. The auxiliary work table is easily removable on those infrequent when additional vertical space is required as when very tall work pieces are to be machined, and then reinstalled afterward to enable typical use thereof.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This invention claims the benefit of U.S. provisional patent application Ser. No. 62/150,520 filed on Apr. 21, 2015. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to machine tools and in particular to milling machines or similar machine tools, which are conventionally provided with a built in work table for securing a work piece to be machined with overhead tooling used to perform the machining as the work table is traversed past the tooling. 
       BACKGROUND OF THE INVENTION 
       [0003]    Milling machines and similar surface cutting machine tools include a built in work table, that is, a planar surface on which work pieces are securely and accurately mounted, usually in various types of work holders. The work mounting surface of the work table includes anchoring and alignment structures for the secure and accurate mounting of work pieces to be ready for being machined. The work table of an exemplary milling machine, the Bridgeport® Mill, includes T-slots formed therein, i.e., channels that resemble inverted letters-T&#39;s, which run along the length of the work surface. The T-slots accept a variety of keys and bolts, for the precise alignment and fastening of work piece holders to the work surface. Similar work tables are also included in other similar machines such as CNC machining centers. 
         [0004]    In a typical milling machine, a work piece is affixed to a built in work table and operated upon by a tool mounted in a motor driven quill, which extends downward from a head. The head is held over the work piece by an overarm, which extends from an upright column. The work table is mounted upon a knee, and can be moved vertically, toward or away from the head, by travel of the knee along a vertical track (not shown) and is traversed past the tooling during machining. 
         [0005]    A problem inherent in such machines is the limited vertical travel of the work table. The work table often cannot be lowered sufficiently to accommodate very tall work pieces beneath the head, and cannot be raised sufficiently to bring very short work pieces into the range of an overhead mounted tool. 
         [0006]    One way to solve the problem of insufficient work table travel is to alter the height of the column that supports the head. This requires disassembly and reassembly of structural elements of the milling machine. This solution is time consuming and requires much effort. In the case of Bridgeport® Mill, this is done by detaching the overarm and head from the column; mounting a donut shaped spacer (S in  FIG. 1 ) atop the column; and mounting the overarm upon the spacer. Because the overarm supports a heavy motor drive and transmission, the addition or removal of a spacer is a task that requires a hoist and multiple operators, and can take several hours to complete. For this reason once a spacer has been installed and the job is completed, it is generally simply left in place awaiting the next too tall work piece. 
         [0007]    This is because the adjusted height state of the machine necessitates the use of extended tooling to reach a short or normal sized work piece. Extended tools are less rigid and stable than corresponding tools of normal length their use is usually avoided if possible. Another drawback is that, when the head is articulated to direct a tool toward an edge of the work table, even an extended tool may not reach the most peripheral areas of the work surface which allows the machine to be quickly and easily restored to its original capabilities. As a result, once a spacer has been installed, the machine in question is often only used for jobs involving very tall work pieces, and sits idle most of the time. 
         [0008]    Work-holding accessories have been used that are attachable to the work table of a milling machine, and most them inherently provide some elevation to a work piece but do not restore a modified machine to its normal capabilities. 
         [0009]    For example, several devices mountable upon the work table of a milling machine are disclosed in a web site posted by an author known as John 5293 (http://johnfsworkshop.org/home/links-to-other-pages/the-milling-machine/the-milling-machine-workholding/milling-machine-workholding-tilting-devices/). These devices provide angled surfaces for the attachment of work pieces, and they necessarily also elevate the work pieces above the work surface of the work table. One of the devices is a wedge, depicted in FIG. 427X of John 5293. Although it is simple in construction, and easily handled and mounted, its fixed, sloped upper surface tilts a work piece as well as elevates it. Alignment and anchoring structures, such as T-slots, are not present on the surface of the wedge. Furthermore, the wedge includes no means of stable attachment to a work table. 
         [0010]    Other devices disclosed by John 5293 include a tilting table (FIGS. 40X and 551X), and a sine table (FIG. 38X), which designed to provide work surfaces set at precise angles relative to a work table. These devices do accommodate fastening hardware, and their upper surfaces do replicate the T-slots of the work table. The tilting table and sine table are, however, of heavy and complex construction. They do not mount quickly or simply, because their angling mechanisms must be laboriously adjusted to obtain a work surface parallel to the surface of the work table  28 . 
         [0011]    Another complex accessory that requires angular adjustment is disclosed in U.S. Pat. No. 6,230,070 to Yodoshi. Yodoshi discloses a positioning device including a rectangular base, which is affixable to the work table of a mill machine, and a rectangular mounting member rotatably mounted upon the base. The Yodoshi device does anchor firmly to a work table, but it blocks access to the anchoring and alignment structures of the worktable, and it provides no surface structures to replace them. 
         [0012]    U.S. Pat. No. 2,533,753 to Armitage, et al., discloses work-holding fixtures that can be slid along the work table of a milling machine. These fixtures do elevate a work piece and require no angular adjustment prior to use. They do not however, replicate the surface features of the worktable. Instead, they include specialized holders for particular work pieces. 
         [0013]    None of these prior art accessories allow quick restoration of the original capabilities to elevate a work piece above the work table of a milling machine. 
         [0014]    It is an object of the present invention to provide an arrangement and method enabling a height modified milling machine or the like which enables a quick change to and from a normal machine to a height increased modified machine conveniently to quickly accommodate very high work pieces while being able to be quickly and easily restored to enable normal operation. 
       SUMMARY OF THE INVENTION 
       [0015]    The present invention a solution to the problem of insufficient vertical travel of the work table of conventional milling machines by first adjusting the height of the overhead arm by installing a column spacer. An auxiliary work table is then installed onto the existing work table using the mounting fasteners of the original table. The height of the auxiliary table is of a height about the same as the column spacer. 
         [0016]    Thus, the auxiliary work table is configured so that the auxiliary table upper surface is at the same height relative the overhead arm height as in the unadjusted original machine. The upper side of the auxiliary table accepts the same fastening hardware as the original table for stable anchorage of workpieces on a work table. The upper surface of the auxiliary work table is parallel to the original work surface of a work table and replicates the anchoring and alignment structures of the original work table, such as the T-slots typical of a Bridgeport® Mill work table. 
         [0017]    In the preferred embodiment, the auxiliary table is of unitary construction, and includes hollow bays and integral handles, to reduce weight and facilitate rapid manual mounting and dismounting. 
         [0018]    The present invention also contemplates a kit including at least two auxiliary work tables of different heights readily enable to enable machining of very short work pieces. 
         [0019]    The present invention further includes a method of restoring the standard work table to enable a quick modification of the machine to enable machining of a very tall work piece on short notice by simply removing the auxiliary work table. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a fragmentary view from one side of a mill machine according to the present invention having an auxiliary work table mounted on the original work table of the milling machine shown. 
           [0021]      FIG. 2  is a fragmentary view from the front of the modified milling machine of the milling machine shown in  FIG. 1 . 
           [0022]      FIG. 3A  is a top view of an auxiliary work table according to the invention. 
           [0023]      FIG. 3B  is a view of a cross section taken through the auxiliary work table taken along the line A-A of  FIG. 3A . 
           [0024]      FIG. 3C  is a front view of the auxiliary work table shown in  FIG. 3A . 
           [0025]      FIG. 4A  is a bottom view of the auxiliary work table shown in  FIG. 3A . 
           [0026]      FIG. 4B  is a cross sectional view of the auxiliary work table taken along lines C-C in  FIG. 4A ; and 
           [0027]      FIG. 4C  is a cross sectional view taken through the auxiliary work table taken along lines E-E of  FIG. 4A . 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    In the following detailed description, certain specific terminology will be employed for the sake of clarity and a particular embodiment described in accordance with the requirements of 35 USC 112, but it is to be understood that the same is not intended to be limiting and should not be so construed inasmuch as the invention is capable of taking many forms and variations within the scope of the appended claims. 
         [0029]    Referring to  FIGS. 1 and 2 , a portion of a milling machine M is shown which has an original built in work table  28  mounted to a support  25  which can be moved vertically by operation of a dial  29  in the conventional fashion. 
         [0030]    The upright column C supporting the head  14  has been made higher by the installation of a commercially available donut shaped spacer S ( FIG. 1 ) which raises the holding of a tool supporting overhead arm O in turn elevating the tool holding quill Q ( FIG. 2 ) in the manner known in the art. 
         [0031]    According to the method of the present invention, the spacer S is more or less left permanently in place. 
         [0032]    To restore the original spatial relationship between a work table upper surface and the overhead arm O and quill Q, an auxiliary work table  10  is assembled onto the top of the original work table  28 . 
         [0033]    The auxiliary work table  10  according to the present invention, generally shown as  10  in  FIGS. 1 and 2 , is preferably rectangular in shape but can be of any desired shape, provided that its upper surface  30  and lower surface  24  are both precisely parallel with the work surface  30  of the original work table  28 . The lateral sides  12  and the ends  14  of the auxiliary work table  10  are of a height sufficient to compensate for the gap between the maximum achievable height of the work surface  30  of the work table  28 , and the appropriate height at which a work piece is to be supported. An exemplary auxiliary work table  10  is 6.0 inches in height 35¾ inches in length, and 9.0 inches in width. 
         [0034]    The upper surface  16  of the auxiliary work table replicates at least a subset of the structural elements of the work surface  30  of the original work table  28 . In the case of the exemplary Bridgeport® Mill, the upper surface  16  of the auxiliary work table  10  includes three parallel riser T-slots  18  that exactly replicate the longitudinal T-slots  32  of the specific Bridgeport® Mill work table  28 . The oil trough (not shown) of a Bridgeport® Mill work table  28  can also be included. 
         [0035]    The auxiliary work table  10  of the present invention when securely mounted also provides stability to the work piece that is comparable to the stability of the original work table  28 . In the illustrative example, the auxiliary work table  10  includes bolt holes  36  within the auxiliary work table T-slots  18 , to accept locking bolts  38 , such as T-bolts (not shown) that extend downward through the auxiliary work table  10  to engage the T-slots  32  of the original work table  28 . Alternatively, any suitable engagement hardware can be used to anchor the auxiliary work table  10  atop the original work table  28 . 
         [0036]    The auxiliary work table  10  preferably also includes key locators  40  extending through both ends  14  of the auxiliary work table  10 . The key locator  40  accommodates a removable key (not shown) that protrudes downward below the lower surface  34  of the auxiliary work piece  10 , into a T-slot  32  or other keyway (not shown) of the original work table  28 . The key (not shown) facilitates the rapid and precise alignment of the auxiliary work table  10  with the T-slots  32  of the original work table  28 , before the auxiliary work table  10  is fastened into place. A permanent tab (not shown) or other permanent guide structure can be substituted for key locators  40  and removable keys (not shown). 
         [0037]    The auxiliary work table  10  also includes features that facilitate the tasks of lifting the riser  10 , in mounting it to the original work table  28 , and unmounting it. Lightweight unitary construction machined from a block of aluminum or another suitable lightweight metal or alloy or mold from such a metal. Hollow interior bays  42  are preferably included. The bays  42  can be sealed, partially open to the lower surface  34  of the auxiliary work table  10 , or completely open to the lower surface  34 . Handles  44  also facilitate the manipulation of the auxiliary work table  10 . These are preferably integral, depressed side handles  44 , to further reduce weight and to optimize the simplicity of construction of the auxiliary workpiece  10 . 
         [0038]    The auxiliary work table  10  allows a novel method for dealing with the problem of insufficient vertical travel of the original work table  28  of the milling machine M. 
         [0039]    Firstly, the spacer S is installed to the column C and is permanently left in place during use of the machine M. 
         [0040]    The auxiliary work table  10  is then installed atop the original work table  28  and left in place during normal use of the machine M as the original travel and space is thereby restored. 
         [0041]    Only on the infrequent occasions when very tall work pieces are to be machined, will the auxiliary work table need to be removed. Again, this is a quick and easy process to be convenient to carry out. 
         [0042]    In effect, the milling machine M is permanently reconfigured so as to normally be ready for normal use, but easily modified for the infrequent use with very tall work pieces. 
         [0043]    The auxiliary work table  10  can be deployed without detaching a work piece from a vice or other work holder, because the same T-slots  32  or other surface structures that accept the work holder on the work table  28  are also present on the upper surface  16  of the auxiliary work table  10 . The work holder can simply be removed from the work table  28  and transferred to the auxiliary work table  10 . 
         [0044]    The auxiliary work table  10  is especially useful when provided as a component of a kit, which includes at least two auxiliary work tables  10  of different heights. A kit of auxiliary work table  10  for a Bridgeport® Mill, for example, can provide auxiliary work tables  10  varying at 2.0 inch increments in height, up to a maximum height of 10.0 inches. The auxiliary work table  10  can also vary in length, from a minimum length of 12.0 inches. The kit (not shown) increases the precision and flexibility with which a work piece can be elevated toward a tool that is beyond an elevation attainable by vertical work table travel alone. 
         [0045]    The present invention provides a method for elevating a work piece above the work table  28  of a milling machine (M), including the steps of placing a auxiliary work table  10  on the work surface  30  of the work table  28  of a milling machine (M), orienting the auxiliary work table  10  to a desired point on the work surface  30 , placing a work piece on the upper surface  16  of the auxiliary work table  10 , and elevating the work piece. 
         [0046]    The step of orienting the auxiliary work table  10  at a desired point on the work surface  30  can additionally include the steps of inserting a key (not shown) through a key locator  40  of the auxiliary work table  10 , inserting the key (now shown) into a T-slot  32  of the work table  28 , aligning the auxiliary work table  10  with the T-slot  32  of the work table  28 , and moving the auxiliary work table  10  to a desired point on the work surface  28 . The steps of fastening the auxiliary work table  10  to the work surface  28  can additionally include the steps of inserting a locking bolt  38  through a bolt hole  36  traversing the auxiliary work table  10 , and engaging the locking bolt  38  with a T-slot  32  of the work table  28 . 
         [0047]    The step of placing a work piece on the upper surface  16  of the auxiliary work table  10  can additionally include the steps of placing the work piece in a work holder (not shown), and engaging the alignment structures on a lower surface (not shown) of the work holder (not shown) with the corresponding T-slots  18  or other alignment structures (not shown) on the upper surface  16  of the auxiliary work table  10 . 
         [0048]    Although the auxiliary work table  10  shown is adapted specifically for use on the work table  28  of a Bridgeport® Mill, it is readily adapted for use with any type of work table that is used in conjunction with any sort of machine tool. Modifications in the dimensions of the auxiliary work table  10 , and the substitution of alternative alignment structures for the auxiliary work table T-slots  18 , will produce an auxiliary work table  10  that is enabled for use with any machine tool known in the art which has this problem in use. 
         [0049]    The invention has been described in an illustrative manner, and it is to be understood that the terminology, which has been used is intended to be in the nature of words of description rather than of limitation. 
         [0050]    Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention can be practiced otherwise than as specifically described.