Patent Publication Number: US-6984094-B2

Title: Drilling tool and method for producing port seals

Description:
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/404,091 filed Aug. 16, 2002, and incorporated by reference herein. The invention is directed to a drilling tool for use in production of predetermined hole geometries. More particularly, the invention is directed to a drilling tool useful in machining hydraulic port seals for fluid power ports. 

   TECHNICAL FIELD 
   Background of the Invention 
   In typical drilling operations, a drilling tool is designed to configure a predetermined hole profile in a machining operation to facilitate particular applications. It is desired to form a predetermined configuration hole profile without secondary machining operations, and in a quick and efficient manner. The cutting or boring action of a drilling tool may be performed by an elongated, substantially cylindrical drilling tool, such as a combination of a tool holder and a drill insert attached thereto. Typically the cutting insert engages the material to be cut upon relative rotation between the tool and work piece. The use of cutting inserts allows for quick changing of the insert upon wear of the cutting surfaces, instead of replacement of the entire tool. Further, the use of cutting inserts allows one tool to be used for varying boring applications by changing the insert configuration instead of the entire drilling assembly. 
   In known port contour cutters for the above application, the tools are typically made of solid HSS, braised tipped carbide, indexable carbide inserts or replaceable carbide inserts. In known configurations and prior methods of forming port holes have generally required multiple machining operations. For example, the manufacturer of a port hole has typically required a first step of spot drilling the port hole, thereafter pre-drilling the port hole and a third operation to size the minor thread diameter and form the port hole. This operation typically encompassed the following after pre-drilling: (1) ream and then use a form tool with a pilot for the port form, and (2) ream and port form combination tool, with the reamer used as a pilot. It would therefore be desirable to provide a drilling tool and method which will drill the port hole to size in a solid material for the minor thread diameter in combination with forming the port in a single operation. Further, in known configurations, the tools are radially non-adjustable, and axial adjustment can only be accomplished by adjusting the stick-out of the cutting tool in the holder. It would be an advantage to provide a port contour cutter which allows radial and axial adjustment in a simple and effective manner. 
   SUMMARY OF THE INVENTION 
   Based upon the foregoing, the present invention provides a novel drilling tool and method which overcomes limitations found in the prior art, and enables the efficient and effective production of port holes. It is therefore an object of the invention to provide a drilling tool comprising a port contour cutter which allows machining of a port hole to produce the minor thread diameter and the port form in a single operation. In general, the drilling tool according to the invention comprises a tool holder having a rotational axis, with which drilling inserts are selectively mounted. A first drilling insert having cutting surfaces on a first side, and a mounting surface on a second side thereof, is selectively mounted along the rotational axis of the tool holder. At least one second drilling insert having a predetermined cutting surface portion and a mounting portion is selectively mounted with the holder at a predetermined outboard location from the rotational axis of the holder. The at least one second drilling insert is non-indexable. The invention also provides a method of drilling a port hole configuration to produce the minor thread diameter and the port form in a single operation. 
   These and other objects and advantages of the invention will become apparent upon a reading of the description of an embodiment thereof, in conjunction with the drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic representation of a port hole configuration having a connector coupled therewith, such as a hydraulic port seal connection as found in the prior art. 
       FIG. 2  shows a side elevational view of an embodiment of the drilling tool according to the invention. 
       FIG. 3  shows a side elevation of the tool as shown in  FIG. 2 , rotated by 90°. 
       FIG. 4  is a top view of the tool as shown in FIG.  2 . 
       FIG. 5  is a partial exploded view showing the tool holder and drilling inserts according to an embodiment of the invention. 
       FIG. 6  is a side elevation view of a port form insert according to an embodiment of the invention. 
       FIG. 7  is a top view of the port form insert as shown in FIG.  6 . 
       FIG. 8  is a side view of the port form insert as shown in FIG.  6 . 
       FIG. 9  is a perspective view of the port form insert as shown in FIG.  6 . 
       FIG. 10  is an elevational view of an alternate embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   In one particular type of application, for a fluid port seal which is threadably engaged with a hydraulic or other fluid line and sealed by means of an o-ring, requires a particular type of hole profile. As seen in  FIG. 1 , the shape of a fluid power port, such as a hydraulic porthole  10 , uses a truncated or tapered hole  12  leading into a threaded hole  14 . A hydraulic connector to the porthole  16  is positioned above the port taper  12  as shown at  18 , and includes a flange  17  which bottoms out against the face of the work piece. Below the flange  17  are typically straight threads (not shown) formed on the connector, which engage the cylindrical, threaded hole at  14 . To provide a seal for the connector  16 , an o-ring  20  is provided in association with an undercut  22  formed in the connector, which mates with the tapered portion of the hole  12 , providing a seal seat for properly sealing the port. Different threads may be used in association with the connector  16 , and the configuration of the machined tapered hole remains substantially consistent except for the provision of alternative threading configurations. For example, in practice, both imperial straight threads and metric straight threads may be used with a hydraulic port, with other dimensions typically provided in metric dimensions. To identify a metric thread porthole, the porthole may be produced with an identification ridge  24 , allowing simple and effective identification that the port thread is metric. 
   Turning now to an embodiment of the present invention,  FIGS. 2-4  illustrate a drill tool assembly  50  for producing predetermined configuration holes in a work piece. Drill tool assembly  50  comprises a holder  52 , having a shank portion  54  and a head portion  56  associated therewith. Within the head portion  56 , a mounting slot  58  is formed at a central portion of the holder  52  to allow selective mounting of a first drilling insert  60  along the rotational axis of the holder  52 . The slot  58  may be configured to have a bottom wall positioned in substantially perpendicular orientation relative to the rotational axis of the holder  52 , and may include a locating boss or pin (not shown), positioned precisely with respect to the rotational axis, for proper positioning of insert  60  along the rotational axis. The configuration of the tool holder  52  with respect to the mounting slot  58  may be generally similar to the tool holder and drill insert configuration such as produced by Allied Machine &amp; Engineering Company, such as in the T-A™ drilling system. The drilling insert  60  is therefore precisely positioned with respect to the holder  50 , to perform the desired drilling function in conjunction therewith. 
   The holder  52  in this embodiment is shown to have a straight round shank leading to a ground qualified shoulder  55 . The shank may be manufactured without a locking flat to be usable with hydraulic chucks, heat shrink holders or collet chucks, to gain higher dimensional accuracy, concentricity and balance. Alternatively a locking flat may be formed in the holder  52 . Alternative configurations of holder  52  are contemplated, such as with alternative shank configurations to adapt to a particular machine spindle, such as CAT, BT, HSK, KM, ABS or the like. Precision holders may have a qualified length to the face, which in turn requires a ground shoulder on the cutting tool that is qualified, but again other configurations are contemplated. 
   The insert  60  is securely mounted in association with head portion  56  by means of clamping arms  62  having apertures  63 , which can accommodate screws or other fasteners to secure the drill insert  60 , having corresponding apertures  64 . Each of the clamp arms  62  may also include a coolant or lubrication vent  66 , which allows the application and flow of a coolant or lubricant adjacent the cutting surfaces of the drill insert  60 , to facilitate the drilling operation. The vents  66  allow a liquid or air coolant/lubricant to be introduced to the hole bottom through the tool holder body  52 . The liquid or air coolant helps to transport machined cuttings from the hole bottom, as well as cool the drill inserts at and from the bottom of the machined hole. Alternatively, an external coolant supply may also be used if desired. The clamp arms  62  may also include angled or curved surfaces  68 , which facilitate chip removal via chip evacuating grooves  70  on each side of the holder  52 . 
   In the embodiment of the invention, there is also provided at least one second drill insert  80  coupled to the drill holder  52  at a predetermined position. In the embodiment as shown in the figures, at least one second insert  80  comprises a pair of such inserts mounted on opposing sides of the holder  52 . The insert  80  includes a mounting aperture  82  corresponding to a mounting aperture  84  formed in the holder  52 . The holder  52  is formed with insert seats  86 , which precisely mount the inserts  80  in relation to the rotational axis of holder  52 , in a non-indexable manner. This can be seen in  FIG. 2 , and similar to the mounting configuration of insert  60 , the mounting holes  82  formed in inserts  80  may be of tapered configuration, and slightly offset from the apertures  84  formed in the tool holder, to selectively bias the insert against the insert seat  86 , for positive and precise mounting thereof. The connection of the inserts  60  and  80  and other aspects of the tool holder  52 , may be generally similar to tool holder and insert mounting configurations as used in the Allied Machine &amp; Engineering tools mentioned previously, or such as described in co-owned U.S. Pat. No. 5,957,635, which is hereby incorporated by reference herein. The inserts  60  and  80  may be made of a sintered metallic hard material such as carbide, cermet, ceramic, monocrystalline and polycrystalline diamond, or boron nitride as examples. Alternatively, high speed steel or other materials may be used. 
   The various inserts  60  and  80  in relation to the tool holder  52  are shown in FIG.  5 . Using a single-sided inserts  60  and  80  in conjunction with tool holder  52 , allows each of the inserts to be selectively removed and replaced in a simple and effective manner upon wear of the inserts during a drilling operation. The drill insert  60  performs a primary drilling operation, and may comprise the T-A™ drill insert produced by the Allied Machine &amp; Engineering Company. The drill insert  60  in conjunction with tool holder  52 , will produce the minor diameter for the thread size required for production of a hydraulic port seal or other connection for fluid power ports, or for other possible applications. The depth for this minor diameter portion of the machined work piece is generally dictated by the port specification, but can also be changed to suit the application and produced as a special tool for a desired depth. 
   In the drilling tool  50 , a port form portion comprises the at least one second insert  80 , or as shown in this embodiment of the invention, two opposing form inserts  80  mounted on tool holder  52 . Using two effective/opposing form inserts  80  for the task of producing the port form in a machined work piece in conjunction with the minor diameter machine hole formed by insert  60 , may enhance formation of both the minor thread diameter and port form in a single operation. In this way, the present invention provides a drilling system which does not require pre-drilling, and will therefore save set up in production time as well as tool cost associated with a pre-drilling operation. The replaceable inserts associated with the drilling system  50  will therefore not require braised carbide re-tipping or regrinding, which can result in size loss or the need to reset tool parameters. The use of precisely machined inserts  60  and  80  allow repeatability in the machining operation, and allow the user to select drill speeds and feeds according to coated carbide or coated HSS drill recommendations as an example. As the machining operation of the minor thread diameter and port form is performed at the same time, drill speeds can be set to the drill diameter and not a spot faced diameter, as a spot face operation performed by the insert  60  is of short duration and does not produce enough heat to damage the port form insert spot face area. By coating inserts  60  and  80  with materials, such as titanium aluminum nitride (TiAlN), diamond or the like, the tool will have a longer life, and replacement of the insert  60  and  80  is simple and efficient. It has also been found that the combination of the drill insert  60  with the at least one second insert  80  provides a drill system which is stabilized during the drilling operation, particularly when the port form inserts  80  are engaged in the work piece. Proper stabilization provides excellent surface finish and accuracy in the machined work piece. The drilling tool system also allows the drilling operation to be performed without dwell, so that the spot face area cannot start scraping to produce chatter or bad surface finish in the machined hole. In the drilling operation, the holder  52  can be made to rotate a sufficient degree to clean up the spot face surface prior to retraction of the holder  52 . 
   In the drilling system  50 , the provision of a pair of second inserts  80  allows the feed rate per insert to be the same as the feed rate per flute for the drill system  50 , such that the feed rate per edge equals the feed rate per revolution divided by two. As shown in  FIG. 5 , the insert seats  86  are located relative to the drill insert  60  mounting location in a predetermined manner. In the embodiment shown, the seat  86  location is rotated approximately 15° below the drill insert  60  location. This will enhance tool life of the drilling system  50  in that chip flow coming from the drill insert  60  will not hit the port form inserts  80 , which could cause possible damage to the cutting surfaces of inserts  80 . Further, the chip flow coming from the inserts  80  will not interfere with the chip flow from the drill insert  60 , ensuring good chip evacuation from both inserts  60  and  80 . In a preferred form, the angle of rotation, such as approximately 15°, is in-line with the axis of the tool, which opens the chip gullet and prevents clogging of the chips that could choke the drill system  50 . Also, the rotation of the inserts may offset the multi-directional tool and cutting forces, decreasing harmonic vibrations and drill chatter. Although the rotation of the inserts  80  approximately 15° has been found to work effectively, the inserts may also be positioned without any rotation or at other rotation angles, such as between 5°-25° for example. 
   Turning to  FIGS. 6-9 , an embodiment of the replaceable insert  80  is shown in more detail. As seen in these FIGS., the insert  80  is generally of rectangular plate form, allowing simple and cost effective manufacture of the inserts  80 , along with simple and cost effective formation of the pockets or seating surfaces  86  in the holder  52 . These aspects are similar for insert  60 , wherein each of the insert  60  and  80  allow precise repeatability of inserts having substantially identical characteristics. The inserts  60  and  80  are also replaceable, and non-indexable, to avoid problems of indexable inserts known in the prior art. For example, indexable inserts may have one side manufactured wrong, making the entire insert scrap. Alternatively, after a first side of an indexable insert is used, it can be easily mislocated or be rendered unusable due to edge build up, chipped edges and/or broken edges caused by the initial drilling operation. Providing simply manufactured inserts  60  and  80 , which are non-indexable, but easily replaceable, allows for a more cost effective operation than in the use of indexable inserts. 
   In the present invention, it may be desirable to hone a sharp edge formed on the insert  80 , which could result in chipping, such as by dry bead blast honing or other suitable method. The hone may aid the adherence of a coating and prolonged tool life, as well as void chipping under certain applications. At the same time, certain applications may require a sharp edge, and such a sharp edge may be maintained in an un-honed and uncoated condition if desired. It may be desirable in an application in which honing is helpful, to provide a heavier hone at the spot facing edge and a lighter hone at the seal angle edge of the insert  80 , as will be hereinafter described. The degree of honing may be compatible with the actual chip thickness produced by the cutting surfaces of insert  80 . 
   The insert  80  in general has a configuration which will be described relative to the minor diameter  90 . At a top portion of the insert  80  adjacent the minor diameter surface  90 , a 45° chamfer  92  may be configured to lead into the seal angle cutting surface  94 , which typically may be a 12-15° angled surface, but may be of another desired angle. A chamfered surface  93  may be provided along the rear seating surface of the insert  80  to correspond to the seating surfaces machined in the holder  52 . The seal angle  94  terminates with a small corner radius at  96  leading to the spot face  98 . The spot face  98  depth from the top of the insert is predetermined based upon port specifications or the like, and may be adapted for any particular application. At the outside of the spot face  98 , a small corner radius  100  leads to a second angle  102  that shapes the outside wall of the spot face diameter at  104 . The outside edge  104  of the insert  80  may be formed as a wiper edge that produces the inner diameter of the spot face, and may be configured to have a slight angle between 0 and 5°, which will allow a slight amount of material to be shaved from the machined surface as the tool cuts deeper so as to slightly enlarge the inner diameter and reduce burr in the finished hole. Other angles for the wiper edge  104  are contemplated. 
   The insert  80  may be referred to as a “full form” insert, or a “wrap around” insert which desirably has the capability to cut around corners and chamfers and blend all surfaces. In this way, a machined form is produced without burrs, witness marks, sharp edges or other surface defects. In the embodiment as shown in  FIGS. 6-9 , there is noted an optional notch  106  which may be formed in the insert  80  to produce the identification ridge  24  (as seen in FIG.  1 ), to identify the port as metric. 
   In the manufacture of insert  80 , by taking advantage of the port seal diameter desired for a particular application, and the spot face diameter tolerances, a single port form may accommodate several port sizes. The inserts  80  can be made from blanks, such that a single blank may accommodate more than one insert. The insert  80  may be coated by known suitable methods, with a desired coating based upon a particular application for the tool  50 . As an example, an application in aluminum may desirably use a diamond film coating on the inserts  60  and  80 , or other coating materials, such as titanium aluminum nitride, may be used. 
   The inserts  80  generally may not need additional coolant holes, as the cutting action performed thereby is of relatively short duration, and at the end of the drilling operation. Residual coolant from the hole being drilled, introduced by coolant holes  66  or an external coolant supply, may be sufficient for cooling the cutting surfaces of the inserts  80 . If a through hole is provided, an outside source of coolant may be required. Although the use of coolant holes to supply coolant directly to the area of inserts  80  may not be necessary for certain applications, such additional coolant holes (shown in ghost at  67 ) could be provided if desired or needed for a particular application. 
   With the configuration of the inserts  80 , several cutting surfaces are formed to produce desired machine surfaces in a work piece. The insert  80  will have two different areas producing two different types of material chips, from the seal form surface  94  as well as spot face surface  98 . The seal form area cutting edge will enter the hole at an angle, such as between 12-15°, adjacent to the centerline. Due to this acute angle, the theoretical chip thickness will only be approximately 10-15% of the actual feed rate and the actual chip thickness not appreciably increased. In the spot face area, the cutting edge will approach the material at approximately 90° to the centerline and the theoretical chip thickness will be approximately 100%. In the embodiment shown in  FIG. 2 , as an example, the inserts  80  are placed above center in the holder  52  to slightly increase the cutting pressures and reduce and/or eliminate chatter and vibration. As an alternative embodiment, as shown in  FIG. 10 , and to provide radial and axial adjustment in the drilling system  50 , the inserts  80  may be located on an independent cartridge  110  formed to be mountable with the holder  52 . A plurality of such cartridges  110  allowing radial and axial adjustment of the relative positions of inserts  80  relative to the holder  52  and cutting insert  60 . Cartridges  110  may be nested against three sides for proper positioning relative to the holder and other tool components, and fastened with a suitable fastener such as a screw. In this manner, the tool  50  may be fine tuned, even when mounted within a spindle for operation, in the case of spindle run-out or other problems a turning machine may have. Adjustment of the cartridges may be performed via shims, set screws or the like, to facilitate repositioning. 
   Although the present invention has been described above in detail relative to a particular embodiment thereof, the same is by way of illustration and example only, and is not to be taken as a limitation on the present invention. Accordingly, the scope and content of the present invention are to be defined only by the terms of the appended claims.