Abstract:
A large bore measuring system includes a modular and extendable bore gage with analog and digital readouts, also includes a settable set-master. The modular bore gage is designed to measure two sets of large bore diameters. A first set of large bores is accomplished by using a modular bore gage design described in this disclosure. The second set of larger bores is accomplished by adding attachments therein extending the gage for the larger range of bore diameters. A set-master is used for both sets of large bores.

Description:
[0001]    This application claims benefit of Provisional application Ser. No. 61/573,907, filed on Sep. 14, 2011, herein incorporated by reference in its entirety, and assigned to a common assignee. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    (1) Technical Field 
         [0003]    The technical aspect of the invention relates to the precise measurement of large bore surfaces using dial indicating and digital instruments, and more particularly to the packaging of a modular system, including a set-master, that can be easily assembled and adjusted to measure a variety of large bore diameters as well as means to extend reachability to a deep bore. 
         [0004]    (2) Description of the Prior Art 
         [0005]    A dial bore gage is one of the most precision tools for measuring a cylindrical bore for out of roundness or taper. Bore gages are comparator type instruments used to compare an internal diameter of a cylindrical bore, which is cut in a solid material, to a known reference ring diameter. The dial bore gage does not give a direct measurement, it indicates an amount of deviation from a preset size, or the amount of deviation from one part of the bore to another. The dial bore gage is preset using either a master ring reference, an outside micrometer or a vernier caliper. 
       SUMMARY OF THE INVENTION 
       [0006]    It has been a primary object of the present invention to provide a user friendly design for measuring a first wide range of large bore diameters by the packaging of a large bore gage that includes both analog and digital gages. This combination improves quality control by allowing visual checking with remote recording. The improved design includes a retractable centralizer to ease placement of the large bore gage into the bore. Furthermore, several adapters are readily assembled to the large bore gage to extend its use for measuring a second wide range of larger bore diameters. A vertical adapter is also provided to extend reachability of the large bore gage to measure deep bore diameters. 
         [0007]    Bore gages are comparator type instruments used to compare manufactured part&#39;s inconsistencies to a known reference dimension by using a master ring facsimile made specifically for comparing a single bore diameter. Therefore, another object of the present invention is to provide a universal set-master that is designed for precisely setting and enabling a large bore gage to measure two ranges of large bore diameters. 
     
    
     
       DESCRIPTION OF THE DRAWING 
         [0008]      FIG. 1  is a perspective illustration of a preferred embodiment showing extendibility of the large bore gage for measuring the greater range of large bore diameters, according to the disclosure. 
           [0009]      FIG. 2  is a perspective illustration showing a contraction of the large bore gage used for measuring a smaller range of large bore diameters, according to the disclosure. 
           [0010]      FIG. 3  is a cross-sectional side view of the large bore gage, according to the disclosure. 
           [0011]      FIG. 4  is a perspective view of the linear array of wrung gage blocks to be positioned and adjusted in a setmaster shown in  FIG. 5 , according to the disclosure. 
           [0012]      FIG. 5  is a perspective view of the set-master, according to the disclosure. 
           [0013]      FIG. 6  is a perspective illustration of the set-master showing the large bore gage with a large bore gage in place, according to the disclosure. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0014]    Refer now to  FIGS. 1 ,  2  and  3 .  FIGS. 1 and 2  show perspective views of a large bore gage showing extendability and contraction of a large bore gage (large bore gage)  50  for measuring two ranges of large bore diameters.  FIG. 3  is a cross-sectional side view of the large bore gage.  FIG. 1 , and more particularly  FIG. 3  show that by adding modular extensions  54   a,    56 ,  58   a  and  63  (shown in  FIG. 3 ) increases the gauging range for the larger set of bore diameters measuring from about 21 to 36 inches in diameter. 
         [0015]    The extended shaft member  56  has the same size thread on both ends, in which one end is a male thread connected to a horizontal gaging member  52 , the other a female thread, connected to an adjustable contact shaft  57 . The large bore gage, of the disclosure has a form factor making it easier to handle and to manipulate by a single user to obtain and record accurate measurements for diameters beyond 36 inches. 
         [0016]      FIG. 1  also indicates one of several available vertical members  58   a,  having different lengths, for measuring deeper bores.  FIG. 2  illustrates the large bore gage with a shorter vertical member  58   b  and without the extended member  56  therewith, achieving a quick and simple transformation for measuring the smaller range of large and shallow bore diameters ranging from about 10 to 24 inches.  FIGS. 1 and 2  illustrate the modular options for measuring the two ranges of large bore diameters. 
         [0017]    Bore gages are comparator type instruments used to compare manufactured part&#39;s inconsistencies to a known reference dimension prearranged and set within a set-master  70  illustrated in  FIG. 4 , to be described later. The large bore gage  50   a  and  50   b  shown in  FIGS. 1 and 2  embodies a rectilinear and extendable apparatus. The large bore gage&#39;s extendibility, as shown in  FIG. 1 , is provided to measure a range of larger bore diameters as well as increased depths using the same instrument simply by adding an extension adapter  56  for larger bores, and an extended adapter  58   a  and b to reach deeper bores. 
         [0018]    Two centralizer housings, a larger centralizer housing  54   a  shown in  FIG. 1  and a smaller centralizer housing  54   b  shown in  FIG. 2 , are provided for two ranges of large bore diameters, as indicated by bore segments  11   a  and  11   b  respectively. Each of the centralizer housings  54   a  and  54   b  have a pair of hardened and rounded contacts  53   a,    53   b.  The rounded contacts are geometrically spaced to accommodate the two ranges of bore diameters. The rounded contacts are assembled onto angled facets at a frontal face of each respective housing. The spacing, between the angled facets, assures contact between the pair of rounded contacts  53   a  and  53   b,  covering respective ranges of large bore diameters. A third contact  57 , adjustable with a set-master, is located at the distal end of the large bore gage. The centralizer housings  54   a  and  54   b  are located at the proximal end of the large bore gage. Located between the pair of contacts,  53   a  and  53   b,  is a rounded and hardened contact end  59  urged forward by the gage pressure of readout assembly  51 , shown is  FIGS. 1 ,  2  and  3 , and is forward limited by stop pin  66  engaged within a relief length in slidable gaging shaft  63 . During bore measurement, centralizer housing  54   a  and  b  are slidably retractable about large bore gage member  61 , and relative to the intermediate gaging shaft  63 . The centralizer is rotationally constrained by key placement  67 . Contacts  53   a  and  53   b  are geometrically spaced and positioned to centralize the large bore gage. After releasing the retracted centralizer, spring  62  restores the centralizer against collar stop  68 , there-upon, making three point contact between contacts  53   a,    53   b,  and, diametrically opposite contact  57 . The first end of gaging shaft  63  moves inward transferring horizontal movement to a vertical shaft  64  contained within adapter  58   a  and  b  and lever support housing  55  via a motion transfer mechanism  60  displaying a plus or minus tolerance reading on the face of dial indicator  51   b  and digital gage  51   a.    
         [0019]    Referring now to perspective views shown in  FIGS. 4 ,  5  and  6  illustrating a method for setting a large bore gage to a given nominal diameter.  FIG. 4  shows a linear array of gage blocks  77  representing the nominal diameter of the bore to be measured. The gage blocks are selected so that the total equals the nominal diameter of the bore diameter. The gage block surfaces are highly polished such that when they are wrung together, squeezing out the air between, affecting therein, a vacuous surface condition so that atmospheric pressure pushes each gage block together making the composite gage block array equal to the nominal diameter of the bore diameter. 
         [0020]    A modular set-master  70  illustrated in  FIG. 5  is designed to accommodate each of the two ranges of large bore diameters. Presetting the set-master is accomplished by installing the linear array of gage blocks  77 , a chosen combination of certified (National Bureau of Standards) square faced gage blocks  77 , of various thicknesses. The selected array of gage blocks, wrung to each other, linearly equal the desired bore diameter to be measured. The gage blocks are placed, en masse, onto rail  73  against centering support members  79  and against a preset adjustable diameter anvil  78 . For smaller diameter bores, slidable block  74  must be relocated and locked in place with knob  76 . Repositioning of block  74  may be necessary, therefore, side support members  79  can be removed and re-fastened at one of several rail locations permitting slidable block  74  to be moved inward without interference. Tightening knob  76  keeps slidable block  74  in place against spring loaded pin  75 . The large bore gage is placed within the set-master, between contacts  71 ,  72  and distal contact  75 . Setting the large bore gage to the nominal bore diameter, the dial indicator&#39;s indicator hand is set to zero as read on its dial face.  FIG. 6  illustratively implies placement of the large bore gage  50  onto the set-master  70  for zeroing. 
         [0021]    Again, referring to  FIGS. 4 ,  5  and  6 , the large bore gage must be set to a particular large bore&#39;s diameter given its nominal diameter and its acceptable deviation. Using the series of gage blocks, wrung together to squeeze out the air, forms a linear array such that the composite array of gage blocks equals the large bore&#39;s nominal diameter. The linear array of gage blocks is then placed in the set-master. The set-master is adjusted to dimensionally conform to the linear array dimension, thereafter, the array of gage blocks is removed and the set-master is now prepared to accept the large bore gage for setting. After placing the large bore gage within the prepared set-master, the dial indicator hand is adjusted to zero, setting the large bore gage to a “zero’ reference so that a plus or minus deviation of the bore diameter can be read on the face of the dial indicator and recorded on a digital receiver. 
         [0022]    During use, the gage is inserted on an angle for easy entry into the bore. The centralizer insures locating on the true diameter while the gage is “rocked” to obtain a true diameter reading. The true diameter is discerned while watching the movement of the needle on the face of the dial indicator  60 . Any discrepancies in the dial reading, i.e., high points produced by particulates causing the needle to indicate a lesser diameter at its location can be easily resolved by an experienced user observing the needle movement. 
         [0023]    Although the invention has been described with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and that numerous changes in the construction, and the manner of combining parts may be made without departing from the spirit and the scope of the invention.