Abstract:
A device and method used in a spindle or fixture to measure tool sizes. The device has two conical shapes that have precision machined surfaces. The device&#39;s face has a precise size which is the same nominal size as that of a material removing tool. The device&#39;s shaft allows for concentric and precision fastening of the device to a spindle or a fixture. The nose of the device is located on the end of the larger of the two conical shapes which is visible exposed when mounted and used. The end of the device is at the end of the smaller of the two conical shapes which is hidden after mounting. The combination of using the device and method will allow more accurate programming of machine tools which in turn will provide higher quality results on machined work pieces and reduced machining cycles.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a method used to precisely measure a cutting tool. 
       BACKGROUND OF THE INVENTION 
       [0002]    Cutting tools used in CNC machines are made to nominal sizes but rarely measure the precise size they were designed to. 
         [0003]    The precision machining of components serving many industries becomes more and more demanding. Computerized Numerical Control, or CNC, Machine Tools are becoming more advanced, software programming is becoming more powerful, and new cutting tools grow in user acceptance based on their particular strategy. Throughout all of these continuing improvements with technology, the one variable that is often overlooked is that a nominal size tool does not always measure its designed precise size. 
         [0004]    Precise work pieces can be manufactured with the use of CNC machines. These machines are very accurate and precise. A CNC machine tool has three linear axes of motion while more advanced CNC machine tools are four axis, five axis, or more. CNC machine tools have become very advanced and repeat toolpath positions well within 0.0002″ (two ten-thousandths of an inch). 
         [0005]    Machine tool programming software plays a vital role in achieving efficient tool paths in CNC machines. To achieve efficient tool paths accurate tool paths must be programmed at the machine or through offline CAM (Computer-Aided Manufacturing) software. CNC programs, or tool paths, are primarily based off of the size of tool specified. Tool paths have accuracy to or finer than 0.0002″ (two ten-thousandths of an inch). 
         [0006]    Tooling used in machining centers has rapidly grown in size and shape. Specific tool geometry meets certain criteria to achieve specific tool path strategies. These tools are more commonly made from high speed steel, cobalt, and carbide. Tools can be made from one solid material, or component. Tools may also have two or more materials, or components, commonly known as indexable tools. Tools are designed to standard nominal sizes in both imperial and metric units. 
         [0007]    With the investment of a CNC machine, CAM software, and dedicated tooling, machinists expect high quality results to precisely machine components. However this is not always the result. 
         [0008]    More often than not a tool does not measure the exact nominal size of its design. Software continues to apply paths correctly within 0.0002″, the machine tool continues to repeat a toolpath within 0.0002″, but the cutting tool is more commonly the variable and the reason behind low quality results. 
         [0009]    Tools are not easy to measure with hand instruments. Tools have very fine cutting edges, sometimes an odd number of flutes, or sometimes variable flute geometry . . . just to name a few. Tools very rarely measure their nominal size within 0.0002″ (two ten-thousandths of an inch). 
         [0010]    Some CNC machines offer an electronic means to measure a tool however they will not always identify the condition of a tool with multiple flutes. 
       SUMMARY OF THE INVENTION 
       [0011]    The invention provides a method to accurately measure a cutting tool with the use of a custom gage so the precise size can be utilized when programming a machine tool. Both embodiments of the invention have precision manufactured diameters that measure within 0.0002″ (two ten-thousandths of an inch). The diameters of both embodiments are manufactured concentric to their corresponding shaft and pocket. The shaft and the pocket of both embodiments allow the precision diameters to be accurately located in a tool holder. The distance from the face on the diameters to the dead center of the apertures is the common set point. The nose side on the end of the gage is the visible side when mounted in a tool holder. 
         [0012]    Numerous objects, features and advantages of the present invention will be readily apparent to those of ordinary skill in the art upon a reading of the following detailed description of the presently preferred, but nonetheless illustrative, embodiment of the present invention when taken in conjunction with the accompanying drawings. Before explaining the current embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. 
         [0013]    One object of the present invention is that it brings attention to an issue that is often overlooked and assumed when machining components: nominal sized cutting tools do not measure their precise diameter. 
         [0014]    Another object of the present invention is to provide a method to accurately measure a cutting tool with the use of the custom gage so the precise size can be utilized when programming a machine tool. The knowledge of the exact size of a cutting tool reduces multiple cycle runs, improves accuracy of the finish product, and can even prevent scrap workpieces. 
         [0015]    With the ability to individually pinpoint each of the different cutting edges on a cutting tool the present invention offers a more visible way to evaluate the integrity of a tool. 
         [0016]    Cutting tools are exposed to low and high levels of force leading to changes in their geometry. The present invention provides a standard way of gaging a tool over its lifespan. 
         [0017]    Another object of the present invention is to provide a way for users to accurately measure their cutting tool. 
         [0018]    Another object of the present invention is to provide a method and device that can be used by any user with minimal skill levels. 
         [0019]    Another object of the present invention is to provide an accurate way of setting adjustable tools mounted in a spindle. 
         [0020]    With the ability to determine cutting tool sizes outside a machining center the present invention provides an efficient way to measure using a fixture. Machining center time is more valuable than fixture time due to their manufacturing capabilities. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0021]      FIG. 1  is a front view of the invention with a shank  54  for mounting. The aperture  56  and aperture  58  are shown in the center of the nose  50  and the end  55 . 
           [0022]      FIG. 1A  is a top view of the invention shown in  FIG. 1 . All geometry and features are concentric. 
           [0023]      FIG. 1B  is a bottom view opposite of that of  FIG. 1A . All geometry and features are concentric. 
           [0024]      FIG. 2  is a front view of the alternate embodiment of the invention with a pocket  58  for mounting. The aperture  56  and aperture  58  are shown in the center of the nose  50  and the end  55 . 
           [0025]      FIG. 2A  is a top view of the alternate embodiment. A horizontal slot  59  is shown located on the end  55 . 
           [0026]      FIG. 2B  is a bottom view opposite of  FIG. 2A . The face  51 , aperture  56 , and aperture  57  are concentric. 
           [0027]      FIG. 3  is a front view of a machine spindle  1  with the invention  3  installed showing the invention (gage) setting with an indicator  2 , and  FIG. 3 a    is a detail view. 
           [0028]      FIG. 4  is a front view of a machine spindle  1  with a cutting tool  4  installed showing the tool measurement off of the known indicator setting, and  FIG. 4 a    is a detail view. 
           [0029]      FIG. 5  is an isometric view showing a machine spindle  1  with the invention  3  installed. 
           [0030]      FIG. 6  is an isometric view showing a machine spindle  1  with a cutting tool  4  installed. 
           [0031]      FIG. 7  is a front view of a fixture  9  outside of a machining center with the invention  3  installed showing the invention, or gage, setting with an indicator  2 . 
           [0032]      FIG. 8  is another front view of a fixture  9  outside of a machining center with a cutting tool  4  installed showing the tool measurement from a known indicator setting. 
           [0033]      FIG. 9  is an isometric view showing a fixture  9  with the invention  3  installed. 
           [0034]      FIG. 10  is an isometric view showing a fixture  9  with a cutting tool  4  installed. 
       
    
    
       [0035]    The same reference numerals refer to the same parts throughout the various figures. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0036]    The foregoing features, object, and advantages of the invention will become apparent to those skilled in the trade from the following detailed description of the preferred embodiment, especially when considered in conjunction with the accompanying drawings. 
         [0037]    The present invention, the Standard Tool Diameter Gage, offers the ability to accurately measure a cutting tool in or outside a machine tool. 
         [0038]    With its precise size and capability to be easily mounted into a machine spindle or fixture the present invention serves as an excellent method to measure tool sizes. 
         [0039]      FIG. 1  and  FIG. 2  show the operating dimensional characteristics of the present invention. “D” represents the main measuring diameter. “d” represents the shank or arbor size. “h” represents the land area of the measuring diameter. The measuring diameter can be a minimum size of 0.005 inches and a maximum size of 24.000 inches. “R” represents the corner where a radius may be conveniently present for aid in manufacturing.“L” is the overall length of the gage.  FIG. 1  shows a front view of a round cylindrical shaped head. 
         [0040]      FIG. 1  shows a front view of the present invention. The first diameter as at D is the gage size of the device that is manufactured to precise nominal values. The second diameter as at d is the shank of the device used for mounting into a tool holder. The present invention, or gage has a nose  50  with a face  51  that abuts a block later shown. The nose  50  of the gage is perpendicular to the face  51 . The face  51  and the shaft  54  are concentric to each other. The concentricity deviation between the face  51  and the shaft  54  must be held to a minimum to prevent inaccuracies. Measuring within tenths of an inch (0.0001) any inaccuracies between the face  51  and the shaft  54  will compound error when determining the actual tool size as later mentioned. The concentricity tolerance between the face  51  and the shaft  54  needs to be less than one ten thousandths of an inch (0.0001). A shoulder  52  is perpendicular to the face  51  and is tangent to a neck  53 . The neck  53  has a small radius which serves as a transition between the shoulder  52  and a shaft  54 . The shaft  54  is dimensionally longer than the face  51  for clamping and has an end  55  which is parallel to the nose  50 . The shaft  54  is conical in shape and has parallel sides. The shaft  54  mounts and clamps inside a tool holder. A first aperture  56  is located in the dead center of the device on the nose  50 . A second aperture  58  is located in the dead center of the device on the end  55 . The end  55  is smaller in size in comparison to the face  50 . The first aperture  56  and the second aperture  58  are blind apertures that are drilled in the centerline of the device. The first aperture  56  and the second aperture  58  are shallow in depth and that have sixty degree inclusive bevels at their entries. The first aperture  56  and the second aperture  58  serve as centers for aid in manufacturing. 
         [0041]      FIG. 1A  shows a top view of the device shown in  FIG. 1 . The end  55  is in the center of the shaft  54  and retains the second aperture  58 . The shaft  54  is beneath and perpendicular to the end  55  and follows down to the neck  53 . The neck  53  is adjacent to the shaft  54  which is adjacent to the shoulder  52 . The face  51  of the invention hangs beneath the shoulder  52 . The center of the end  55  is the second aperture  58 . The face  51  and the shaft  54  should be machined together preferably in the same manufacturing setup so that the face  51  is parallel and true to the centerline of the shaft  54 . 
         [0042]      FIG. 1B  shows a bottom view of the device shown in  FIG. 1 . The nose  50  is the complete surface shown outside the first aperture  56 . The nose  50  is the working end of the device. The face  51  of the device is perpendicular to the nose  50 , that is into the plane of this figure. This face  51  surface must be machined to a high tolerance with a smooth surface finish therefore to be used to establish a known indicator setting. The face  51  should be manufactured within one ten thousandths of an inch (0.0001) and should have a surface finish of 32 RMS, root mean square of profile height deviation from the mean line, or better. 
         [0043]      FIG. 2  shows a front view of the alternative embodiment of the invention. This device has less height than the device in  FIG. 1  and suits larger diameter gages. The second aperture  58  is a pocket that accepts an adapter on a tool holder. The nose  50  of the gage is perpendicular to the face  51 . The face  51  and the shaft  54  are concentric to each other. The shoulder  52  is perpendicular to the face  51  and is tangent to the neck  53 . The neck  53  is a small radius which serves as a transition between the shoulder  52  and the shaft  54 . The end  55  is parallel to the nose  50 . The first aperture  56  is located in the center of the nose  50 . The first aperture  56  is a clearance hole for a fastener used to mount the device to an arbor type tool holder. The second aperture  58  is a precise size that locates the device. The second aperture  58  must be machined concentric to the face  51  to eliminate inaccuracies. The throat  57  is clearance for a fastener. The throat  57  communicates to the first aperture  56  and the second aperture  58 . 
         [0044]      FIG. 2A  shows a top view of the alternate embodiment shown in  FIG. 2 . The end  55  is at the end of the shaft  54 . The shaft  54  is perpendicular to the end  55  and follows down to the neck  53 . The neck  53  connects to the shaft  54  then to the shoulder  52 . The face  51  of the device connects to the shoulder  52 . When manufacturing the devices the face  51  needs to be machined perpendicular to the nose  50 . 
         [0045]      FIG. 2B  shows a bottom view of the alternate embodiment shown in  FIG. 2 . The throat  57  is in the center of the device. The first aperture  56  travels around the throat  57 . The nose  50 , appears as the surface shown outside of the first aperture  56 . The face  51  of the device is perpendicular to the nose  50 . The nose  50  is the working end of the device. The face  51  is manufactured with a high tolerance and is used to transfer a measurement. The distance from the center of the device to the face  51  is a known radial value. The face  51  should be manufactured within one ten thousandths of an inch (0.0001) and should have a surface finish of 32 RMS, root mean square of profile height deviation from the mean line, or better. 
         [0046]      FIG. 3  and  FIG. 4  are front views that show a method used to obtain the precise size of a cutting tool used in a machining center. The CNC machine  9  has linear axes that allow the spindle  1  to be traversed. 
         [0047]      FIG. 3  shows a present invention  3  installed in a tool holder  7  located in a machine spindle  1 . A CNC machine  9  with linear axes is shown with a spindle  1 . An indicator  2  is shown set to a known position on the present invention  3 . A contact point  5  of the indicator to the gage  3  has a setting at the highest peak of the gage  2  diameter (D) as also shown in  FIG. 3 a   . The CNC machine  9  has a controller  8  for operating a program and manually joggling the spindle  1 . The indicator block  6  is shown with an indicator  2 . An indicator block  6  allows the indicator  2  to be securely mounted beneath the spindle  1 . 
         [0048]      FIG. 4  shows a cutting tool  4  installed in a tool holder  7  located in a machine spindle  1 . An indicator  2  measures the deviation from the original setting in  FIG. 3 . The contact point  5  of the indicator to a cutting tool  4  is measured at the highest peak of the cutting edge as also shown in  FIG. 4 a   . This measurement shown on the indicator  2  determines the precise size of the cutting tool  4 . 
         [0049]      FIG. 5  is an isometric view of  FIG. 3 . A CNC machine  9  with linear axes is shown with a spindle  1 . A CNC machine  9  has a controller  8  for operating a program as well as joggling the spindle  1 . This view shows the relation between the indicator setting and the present invention  3 .  FIG. 5  shows how a machine spindle  1  having a gage  3  should be positioned closely to a indicator  2  to make the preferred setting. 
         [0050]      FIG. 6  is an isometric view of  FIG. 4 . This view shows the relation between the indicator  2  setting and the cutting tool  4  being measured.  FIG. 6  is the same as  FIG. 5  but with a difference of a cutting tool  4  installed in the spindle  1 .  FIG. 6  shows the deviation of the indicator setting made in  FIG. 5  from that of the highest peak of the cutting edge on the cutting tool  4 . The value on the indicator  2  is the measurement from which the nominal diameter size is calculated. A positive indicator value determines the cutting tool  4  is oversize from the nominal size. A negative indicator value determines the cutting tool  4  is undersize from the nominal size. 
         [0051]    The process shown in  FIGS. 7-10  is referred as an offline process because the time used to determine the actual cutting tool size is done outside a machining center. 
         [0052]      FIG. 7  and  FIG. 8  are front views of the method used to obtain the precise size of a cutting tool  4  used in a fixture  9  outside of a machining center. 
         [0053]      FIG. 7  shows a present invention  3  located in a fixture  9  with a spindle  1 . An indicator  2  is shown being set to a known position on the invention  3 . A fixture  9  retains a spindle  1  that accepts a tool holder  7 . The indicator  2  with an indicator block  6  is mounted near the spindle  1 . The contact point  5  of the indicator to the gage  3  is set at the highest peak of the gage  3  diameter. In  FIG. 7  the indicator  2  is positioned and set at one stationary point to be used again in  FIG. 8 . 
         [0054]      FIG. 8  shows a cutting tool  4  placed in a fixture  9  with a spindle  1 . An indicator  2  measures the deviation from the original setting in  FIG. 7 . The contact point  5  of the indicator to the cutting tool  4  is measured at the highest peak of the cutting edge. This measurement shown on the indicator  2  determines the precise size of the cutting tool  4 . This precise height from the spindle to the cutting edge contact point may need to be predetermined prior to setting the invention  3  in  FIG. 7 . The indicator block  6  with indicator  2  is positioned near the spindle for measuring. The cutting tool  4  assembled in a tool holder  7  is shown taking a measurement off of the indicator  2 . 
         [0055]      FIG. 9  is an isometric view of  FIG. 7 . This view shows the relation between the indicator  2  setting and the invention  3 .  FIG. 9  shows how a spindle  1  in a fixture  9  with the gage  3  should be positioned closely to a indicator to make the preferred setting. Some cutting tools have small surface areas of contact. Without having a CNC machine with a controller to adjust the contact height of the cutting tool contact point  5 , as also later shown in  FIG. 10 , the cutting tool height may need to be predetermined so the indicator  2  is not moved. The indicator block  6  and indicator  2  must be kept in one stationary position for precise results. 
         [0056]      FIG. 10  is an isometric view of  FIG. 8 . This view shows the relation between the indicator  2  setting and the cutting tool  4  being measured.  FIG. 10  shows the deviation of the indicator setting made in  FIG. 9  from that of the highest peak of the cutting edge on the cutting tool  4 . The value on the indicator  2  is the measurement from which the nominal diameter size is calculated from. A positive indicator value determines the cutting tool  4  is oversize from the nominal size. A negative indicator value determines the cutting tool  4  is undersize from the nominal size. 
         [0057]    The standard tool diameter gage has a method for its use included with the invention. The method includes the following steps. 
         [0058]    The process of measuring a cutting tool to obtain its exact precise size is a two step process which is illustrated in  FIG. 3  and  FIG. 4 , and in  FIG. 7  and  FIG. 8 . The two step process has been magnified into the following steps to highlight the critical details of the process. 
         [0059]    First, Install the gage in a spindle. Once the preferred cutting tool  4  is selected for use it will determine the size of the standard tool diameter gage  3  to use. As shown in  FIG. 3 , a standard tool diameter gage  3  is installed in a tool holder  7  and is then mounted in a spindle  1 . 
         [0060]    Second, Set an indicator with the gage. The spindle  1  assembly is traversed to a test indicator  2  which preferable has a dial graduation of 0.0001. As shown in  FIG. 3 , the indicator stylus should be loaded to a common value shown on the dial. Setting this point with the indicator should be done on the highest peak of the standard tool diameter gage  3 . 
         [0061]    Third, Verify the contact point  5  has been achieved. Traverse the standard tool diameter gage back and forth across the indicator to ensure this highest point of contact has been reached. Furthermore manually rotate the spindle to ensure there is no run out as to this would offset the measurement. This new indicator set point will be used to test the cutting tool. 
         [0062]    Fourth, Retract and remove the standard tool diameter gage  3  from the spindle  1 . The indicator  2  and the indicator block  6  must be kept in a stationary position. It is important that the indicator  2  is not adjusted or bumped after this initial setting. The point of contact on the indicator  2  from the center of the spindle is now a known radial value. 
         [0063]    Fifth, Install the cutting tool  4  in a spindle  1 . As shown in  FIG. 4 , the selected cutting tool  4  installed in a tool holder  7  is mounted in a spindle  1 . The cutting tool should be cleaned and clear of any debris from previous manufacturing use. 
         [0064]    Sixth, Reference the cutting tool to the set indicator. It is important that the indicator  2  is not adjusted or bumped from the initial setting from the second step. 
         [0065]    Seventh, Verify the indicator reading. By slowly rotating the spindle, find the highest peak  5  of the cutting edge on the cutting tool  4 . Commonly rotate the cutting tool in the reverse rotation of its cutting use. This allows the indicator  2  to be loaded with little resistance by testing the relieved portion of the cutting edge first. This keeps the indicator  4  in a stationary position. 
         [0066]    Eighth, Record the measurement. The measurement reading taken and shown in  FIG. 4  can be a positive or negative value based off the initial setting in step  1 . A positive reading will indicate the tool is oversize of that of the nominal tool size. A negative reading will indicate the tool is undersize of that of the nominal tool size. 
         [0067]    And, Ninth, Calculate the discovery. The indicator reading on the test indicator is a radial value. The value (whether positive or negative) must be multiplied by  2  in order to add or subtract to the nominal diameter to determine the cutting tool&#39;s precise size. 
         [0068]      FIG. 7  and  FIG. 8  show the same method as described in  FIG. 3  and  FIG. 4  only using a fixture  6  outside of a machine tool.