Abstract:
A thread ring gage testing and setting device including one end for testing “GO” ring gages, a second end for testing “NO GO” ring gages. Structure to test for a thread ring gage undersize effective minor diameter includes a non-threaded cylindrical portion on each end. Structure for testing thread ring gage oversize minor diameter includes a non-threaded cylindrical portion located at the innermost position of each end, and is of greater diameter than said means for testing thread ring undersize effective minor diameter.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     A. Field of the Invention  
         [0002]     The present invention generally relates to hand-held measuring devices and, more particularly, to a new and improved master thread setting plug gage adaptable for setting a thread ring gage to size; detecting wear in the thread flanks; and, easily determining the effective minor diameter condition of the thread ring gage being tested. Three embodiments are illustrated and described.  
         [0003]     B. Description of the prior art  
         [0004]     The Thread Ring Gage  
         [0005]     Thread ring gages are used to check the functional size of product thread such as a bolt. The “Go” thread ring gage represents the largest size of the product thread and should assemble with the bolt. The “No Go” thread ring gage represents the smallest size of the product thread and should not assemble with the bolt. This simple checking procedure assures that the bolt has been manufactured within its design limits.  
         [0006]     Thread Ring Gage Terminology  
         [0007]     The thread ring gage ( FIGS. 1A-1D ) includes a body portion  2  with a slot  3  with an adjusting assembly  4   a - 4   d.    
         [0008]     The Major Diameter  5  on a straight thread, is a diameter of the coaxial cylinder that would bound the crest of an external thread or the root of an internal thread.  
         [0009]     The Minor Diameter  6  on a straight thread, is the diameter of the coaxial cylinder that would bound the root of an external thread, or the crest of an internal thread.  
         [0010]     The Pitch Diameter  7  on a straight thread, is the diameter of the coaxial cylinder, the surface of which would pass through the thread profiles at such points as to make the width of the groove equal to one-half of the basic pitch. On a perfect thread this occurs at the points where the widths of the thread and groove are equal.  
         [0011]     The Effective Minor Diameter  8  is effected when thread ring gages wear and are readjusted, which causes an eccentric condition between the thread pitch and minor cylinders which often results in an undersize effective minor diameter (see  FIG. 1D ) which can encroach on the maximum permissible limit for the root profile of the product external thread. This encroachment can result in a loss of manufacturing tolerance for the product; and/or, can result in the rejection of an acceptable product when the ring gages are used to inspect a vendor product, for example.  
         [0012]     Inspection facilities ordinarily available in the field are often inadequate for determining the important pitch and effective minor diameter elements of the thread ring gage.  
         [0013]     Thread setting plug gages are used primarily as master gages to set adjustable “Go” and “No Go’ thread ring gages to size, but are also used to set other gages such as indicating gages and snap thread gages, for example. FIG. 6, of I. T. Wedin U.S. Pat. No. 2,793,443 (1957) discloses a setting gage  36  for testing a thread ring gage  11 .  
         [0014]     Each of the three embodiments of the Improved Thread Setting Plug Gage of the present invention not only function as a normal thread setting gage, but also easily control the interrelated and difficult to measure pitch and minor diameter elements of the thread ring gage.  
         [0015]     Proper use of truncated thread setting plug gages includes when using the truncated plug, the thread ring gage should be adjusted to fit the full thread portion, after which the fit of the ring on the truncated portion should be determined. If there is any appreciable shake or play, on either side of the ring, the ring gage should be re-lapped or discarded.  
         [0016]     Hilo Setting Plug Gages  
         [0017]     These plug gages such as in J. E. Finley U.S. Pat. No. 2,789,360 (1957), the “GO” thread ring gage, as an example, is set to the front and or “Lo” portion of the HILO plug gage (which represents the lower limit of the “GO” ring gage pitch diameter tolerance). When the back or “Hi” portion (which represents the upper limit of the “GO” ring gage pitch diameter tolerance) enters the ring gage, the ring is out of tolerance and should be reset, re-lapped or discarded.  
         [0018]     As shown in  FIG. 1C , to utilize the adjusting assembly ( 4   a - 4   d ), to adjust the ring, first loosen the locking screw  4   a.  This permits the split adjusting screw  4   b  to be screwed back or forth on its external thread. To spread the ring—adjusting screw  4   b  is turned clockwise exerting a pressure on the sleeve  4   c  and against the shoulder  4   d  in the right hand side of the gage. To reduce the size of the ring, turn the adjusting screw  4   b  counter clockwise, reducing pressure of sleeve  4   c  against shoulder  4   d.  Locking the adjustment is accomplished by turning the locking screw  4   a  clockwise, exerting a pull between the shoulder immediately under the head of the locking screw  4   a  and internal threads of the adjusting screw  4   b  confining sleeve  4   c  securely between the body shoulder  4   d  and the adjusting screw  4   b.  Sleeve  4   c  must be securely locked if ring is to retain its setting. Make adjustment while the ring is on the setting plug. Tighten the locking screw securely before removing ring gage from setting plug.  
         [0019]     Worn adjustable thread ring gages may frequently be salvaged by re-lapping the Threads, to restore thread form and roundness, and refinishing the minor diameter. Gages thus salvaged are reworked to tolerances used in the manufacture of new gages.  
       SUMMARY OF THE INVENTION  
       [0020]      FIGS. 2-2D  illustrate an improved thread setting plug gage  10  including an upper limit “GO” thread gage end  11  and lower limit “NO GO” end  30  which are mirror images of each other except the size of the “NO GO” end  30  is of smaller dimensions because it is used to test lower limit gages. For convenience these respective portions will be discussed together. In one embodiment the plain cylindrical portions  12 ,  32  of the gage  10  immediately behind the threaded section  14 ,  34  of the gage are used to check the minimum effective minor diameter  8  ( FIG. 1D ) of the ring gage. The minor diameter of the thread ring gage should clear the section  12 ,  32  of the gage. The larger plain cylindrical part  16 ,  36  of the gage immediately behind the minimum effective minor diameter checks the maximum size of the minor diameter of the ring gage, which should not enter this section of the setting gage. The thread setting gage is attached to a handle  20  of an octagon cross section  28   FIG. 2E , either by a taper fit  22 ,  42  or with a bolt  26  for a larger gage, as illustrated in  FIG. 2D .  
         [0021]     In the second embodiment shown in  FIG. 7  the improved thread setting plug gage  60  has “GO” and “NO GO” ends  61  and  62 , with the plain cylindrical effective minor diameter checking sections  62   a  and  67  located in the approximate center of the ends  61  and  62 , between the full form threaded entry section  64  and the truncated thread section  66  at the “GO” end  61 , and at the “NO GO” end  62  between threaded section  65  and truncated section  63 .  
         [0022]     This setting gage is made and used differently than the gage in  FIGS. 2-6 , which has a constant pitch diameter for the length of the thread. The pitch diameter of the threaded section  64 ,  65  is manufactured to the lower limit of the respective thread ring pitch diameter tolerance. The back truncated thread sections  63 ,  66  are manufactured to the upper limit of the thread ring pitch diameter.  
         [0023]     In the third embodiment shown in  FIG. 13 , the improved thread setting plug gage  70  has “GO” and “NO GO” ends  71 ,  72 , with the plain cylindrical effective minor diameter checking sections  73 ,  74  located outwardly from threaded sections  77 ,  78 . The larger plain cylindrical maximum minor diameter checking sections  75 ,  76  are located inwardly from threaded sections  77 ,  78 .  
         [0024]     The Improved Thread Setting Plug Gage of the present invention not only functions as a normal thread setting gage, but also easily controls the important and difficult to measure pitch and minor diameter elements of the thread ring gage.  
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0025]     Step 1. In use, using the “GO” end as an example, the thread ring gage  1  is adjusted with assembly  4   a - 4   d  to fit the full thread form section  14  of the improved thread setting plug gage as shown in  FIG. 2F .  
         [0026]     Step 2. The ring gage  1  is then advanced toward the plain cylindrical effective minor diameter testing section  12  of the setting gage as shown in  FIG. 2G . If the ring clears this section of the setting gage, it proves that the minor diameter of the ring gage is above minimum size and should not encroach upon the product thread. This effective minor diameter checking feature is a very important element of the present invention.  
         [0027]     Step 3. The thread ring gage  1  is then further advanced toward the larger plain cylindrical section  16  of the setting gage, as shown in  FIG. 3 . The minor diameter of the ring gage is within tolerance if it stops at this section  16  of the setting gage, which represents the upper size limit for the minor diameter.  
         [0028]     Step 4. The fit of the ring gage  1  is then checked on the truncated thread section  18  at the front of the setting gage as shown in  FIG. 4 . If there is no change in the fit of the ring gage, the gage is acceptable. If there is any change (looseness) in the fit of the ring gage on the truncated section  18 , it is an indication that the thread flanks  9  of the ring gage are worn excessively and should be reworked or discarded.  
         [0029]     In  FIG. 5 , in this example, after adjustment to fit the setting gage, the thread ring gage  1  is worn to the extent that the minor diameter of the ring gage will not clear the minimum effective minor diameter testing section  12  of the improved thread setting plug gage  10 . An undersize effective minor diameter is the most common (and costly) defect to be found in adjustable thread ring gages, and often goes undetected. If a thread ring gage is used in this condition it will result in a loss of manufacturing tolerance for the product. If this undersize gage is used to inspect a vendor product, it could cause reject on an in-tolerance part. Ordinary thread setting plug gages such as J. E. Finley U.S. Pat. No. 2,789,360 (1957), or the setting gage  36  depicted in I. T. Wedin U.S. Pat. No. 2,793,443 (1957), will not detect an out of tolerance minor diameter condition. This improved thread setting gage of the present invention will quickly detect thread ring gages having an out of tolerance minor diameter, and may help to resolve disputes between manufacturer and customer.  
         [0030]     In  FIG. 6 , the minor diameter  6  of the thread ring gage  1  clears the maximum minor diameter section  16  of the thread ring gage, showing that the thread ring gage is oversize and out of tolerance. The improved thread setting plug gage will quickly and easily detect such an out of tolerance minor diameter. Ordinary thread setting gages such as in U.S. Pat. No. 2,789,360 (1957), or the setting gage  36  depicted in U.S. Pat. No. 2,793,443 (1957) will not detect this oversize minor diameter condition. This same procedure is repeated at the opposite end  30  to test the “NO GO” ring gage.  
         [0031]      FIG. 7  illustrates an alternate improved thread setting plug gage  60  with the effective minor diameter checking sections  62   a,    67  located respectively in the approximate center of the gage. This setting gage is made and used differently than the gage in  FIGS. 2-6 , which has a constant pitch diameter for the length of the thread. In this embodiment, the pitch diameter of the threaded front sections  64 ,  65  is manufactured to the lower limit  69   a,    69  of the respective thread ring gage pitch diameter tolerance. The back truncated thread sections  63 ,  66  are manufactured to the upper limit  68   a,    68  of the respective thread ring gage pitch diameter tolerance.  
         [0032]     In use, the “GO” or “NO GO” thread ring gage being checked is set to fit the respective thread front sections  64 ,  65  of the improved thread setting plug gage. It is then advanced toward, and should clear, the plain cylindrical effective minor diameter sections  62   a,    67  of the setting gage. The thread ring gage should not assemble with the truncated thread sections  63 ,  66  at the back of the setting gage. The pitch diameter and effective minor diameter elements of the thread ring gage are considered to be within tolerance if it passes this test.  
         [0033]     In  FIG. 8 , Step 1, again using the “GO” end as an example, the GO” thread ring gage  1  being tested is set to the front threaded section  64  of the improved thread setting gage, which represents the lower tolerance limit of the thread ring gage pitch diameter.  
         [0034]     In  FIG. 9 , Step 2, the thread ring gage  1  is advanced toward, and should clear, the plain cylindrical effective minor diameter checking section  62   a  of the setting gage.  
         [0035]     In  FIG. 10 , Step 3, the thread ring gage  1  is then advanced toward the truncated thread  66  of the setting gage, which represents the upper tolerance limit of the thread ring gage pitch diameter. The thread ring gage being tested should not assemble with the truncated section  66  of the setting gage. If this is the case, the thread ring gage is then considered to be within tolerance and is ready for use.  
         [0036]     In  FIG. 11 , the thread ring gage  1  has been adjusted to fit the front section  64  of the improved thread setting plug gage, and then advanced toward the plain cylindrical effective minor diameter section  62   a.  The minor diameter of the worn thread ring gage has been closed down to the extent that it will not clear the plain cylindrical section  62   a  of the setting gage. The thread ring gage  1  is not acceptable for use and should be reworked or discarded.  
         [0037]     In  FIG. 12 , the thread ring gage has been adjusted to fit the front section  64  of the improved thread setting plug gage  60 . The ring gage minor diameter has cleared the plain cylindrical effective minor diameter section  62   a  of the setting gage, and has also assembled with the truncated thread section  66  at the back of the setting gage, which represents the upper size limit of the thread ring gage. When this occurs, it means that the ring gage is worn excessively and is not acceptable for use and should be reworked or discarded.  
         [0038]     This same procedure is repeated at the opposite end  62  to test the “NO GO” thread ring gage.  
         [0039]     Inspection facilities ordinarily available in the field are often inadequate for determining the important pitch and effective minor diameter elements of the thread ring gage.  
         [0040]     The Improved thread setting plug gage of the present invention not only functions as a normal thread setting gage, but also easily controls the important and difficult to measure pitch and effective minor diameter elements of the thread ring gage.  FIG. 13  illustrates another alternate improved thread setting plug gage  70  including an upper limit “GO” thread gage end  71  and lower limit “NO GO” end  72  which are mirror images of each other except the size of the “NO GO” end  72  is of smaller dimensions because it is used to test lower limit gages. For convenience these respective portions will be discussed together. In this embodiment the plain cylindrical portions  73 ,  74  located immediately in front of the threaded sections  77 ,  78  are used to check the minimum effective minor diameter  8  ( FIG. 1D ) of the ring gage. The minor diameter of the thread ring gage should clear the section  73 ,  74  of the gage. The larger plain cylindrical part  75 ,  76  of the gage immediately behind the threaded section  77 ,  78  checks the maximum size of the minor diameter of the ring gage, which should not enter this section of the setting gage.  
         [0041]     In use, the “GO” or “NO GO” thread ring gage being checked should clear the plain cylindrical effective minor diameter checking sections  73 ,  74  of the improved thread setting plug gage. The thread ring is then advanced onto the threaded section  77 ,  78  of the gage and checked for fit on the full form section of the setting gage. If the fit of the ring gage is acceptable, it is then advanced toward, and should not assemble with, the larger plain cylindrical part  75 ,  76  of the gage which checks the maximum size of the minor diameter of the ring gage. The fit of the ring gage is then checked on the truncated section of the setting gage thread. If there is no change (looseness) in the fit of the ring gage, the pitch diameter and minor diameter elements of the thread ring gage are considered to be within tolerance if it passes this test.  
         [0042]     In  FIG. 14 , Step 1, again using the “GO” end as an example, the “GO” thread ring gage  1  has cleared the plain cylindrical testing section  73  of the improved thread setting gage which checks the minimum acceptable effective minor diameter condition of the ring gage. The ring gage has also started to assemble with the threaded section  77  of the setting gage.  
         [0043]      FIG. 15 , Step 2, the thread ring gage  1  has been advanced to, and has assembled with, the full form section of thread  77 . The fit of the ring gage is checked, and adjusted to fit if any looseness is detected.  
         [0044]      FIG. 16 , Step 3, the thread ring gage  1  is then advanced toward the larger plain cylindrical section  75  located at the back of the gage. The thread ring gage should not assemble with this section of the setting gage which represents the upper size limit of the thread ring gage minor diameter. If the ring gage had assembled with the plain cylindrical section  75  of the setting gage, the minor diameter of the ring gage would be worn to the extent that it should be rejected and removed from service.  
         [0045]      FIG. 17 , Step 4. The thread ring gage  1  is then tested for fit on the truncated part of the threaded section  77  of the improved thread setting gage. If there is no change in the fit of the ring gage, the gage is now considered acceptable to use. If there had been a change in the fit (looseness), it is an indication of wear in the thread flanks of the ring gage. If that is the case, the ring gage should be rejected and reworked to new gage tolerances, or discarded.  
         [0046]     This same procedure is repeated at the opposite end  72  to test the “NO GO” thread ring gage. Inspection facilities ordinarily available in the field are often inadequate for determining the important pitch and effective minor diameter elements of the thread ring gage.  
         [0047]     The Improved Thread Setting Plug Gage of the present invention not only functions as a normal thread setting gage, but also easily controls the important and difficult to measure pitch and effective minor diameter elements of the thread ring gage.