Abstract:
A rotatable cutting tool has a shank portion for coupling to a tool driving device and a cutting portion to which is attached at least one support member for retention of a replaceable cutting element. The support member is so arranged to permit displacement of at least the portion thereof retaining the cutting element whereby the position of the cutting element relative to the body of the cutting tool may be changed by such displacement. A totally enclosed hydraulic force multiplier is mounted within an internal cavity of the cutting tool. The force multiplier is responsive to a control force to effect the displacement of the support member, the control force advantageously supplied by application of pneumatic pressure.

Description:
BACKGROUND OF THE INVENTION 
   I. Field of the Invention 
   This invention relates to cutting tools and particularly to rotatable cutting tools of the type having at least one cutting element the position of which relative to the tool is adjustable by remotely controllable adjusting devices. More particularly, this invention relates to improved actuators for remotely controlled adjusting of relative position of cutting elements of rotatable cutting tools. 
   II. Description of Related Art 
   Known rotatable tools comprising position adjustable cutting elements use various means for effecting changes of position of the cutting elements. Examples of such rotatable tools using mechanical actuating devices are illustrated in EP Patent Application No. 1123766. An example of a rotatable tool using hydraulic actuating devices requiring supply of hydraulic fluid is illustrated in Japanese Utility Model Application No. 62-201231. Tools of this type have the inherent disadvantage of requiring couplings for supply of hydraulic fluid through the tool driving device. U.S. Pat. No. 4,941,782 illustrates tools of the type wherein pneumatic pressure is supplied to a rotatable tool from an external source to control operation of a hydraulically operated device within the tool body. Such known tools have the disadvantage of requiring sliding seals between internal pistons and cavities containing hydraulic fluids. Such seals, if not routinely replaced and reconditioned are a common source of leakage of hydraulic fluid, impairing operation of the adjusting devices. In light of known rotatable tools providing remotely controllable hydraulically operated adjusting devices for adjusting the position of cutting elements, there is a need for improved actuators for such tools to overcome the disadvantages associated with the known hydraulic devices. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a rotatable cutting tool having mounted within an internal cavity a totally enclosed hydraulic force multiplier responsive to a control force for effecting adjustment of position of a cutting element mounted to the tool. 
   It is a further object of the present invention to provide a rotatable cutting tool having a cutting element mounted to a support member, a totally enclosed hydraulic force multiplier mounted within an internal cavity of the tool and responsive to a control force, a push rod responsive to force applied by the force multiplier to move along a first vector, and a drive member interposed between the push rod and the support member for converting motion along the first vector to motion along a second vector intersecting the first vector. 
   Further objects and advantages of the invention shall be made apparent from the accompanying drawings and the following description thereof. 
   In accordance with the aforesaid objects the present invention provides a rotatable cutting tool having a shank portion for mounting to a tool driving device and a cutting portion to which is attached at least one support member for retention of a replaceable cutting element. The support member is so arranged to permit displacement of at least the portion thereof retaining the cutting element whereby the position of the cutting element relative to the body of the cutting tool may be changed by such displacement. A totally enclosed hydraulic force multiplier is mounted within an internal cavity of the cutting tool. The force multiplier is responsive to a control force to effect the displacement of the support member, the control force advantageously supplied by application of pneumatic pressure. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a three dimensional view of a cutting tool having a repositionable cutting element cartridge. 
       FIG. 2  is a partial sectional view of the cutting portion of the cutting tool of  FIG. 1   
       FIG. 3  is an enlarged view of a portion of a cutting tool showing an alternative cutting element cartridge. 
       FIG. 4   a  is an enlarged view of a portion of a cutting tool of  FIG. 2  showing the push rod advanced. 
       FIG. 4   b  is an enlarged view of a portion of the cutting tool of  FIG. 2  showing the push rod retracted. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The invention shall be described with reference to a preferred embodiment illustrated in the accompanying figures. While the preferred embodiment illustrates features of the invention, it is not the intention of applicants that the invention be limited to particular details of the preferred embodiment. 
   A rotatable cutting tool  10  depicted in  FIG. 1  includes a shank portion  12  and a cutting portion  14 . Shank portion  12  is suitable for mounting to an adapter  16  for connection to a tool driving apparatus such as the rotatable spindle of a machine. Adapter  16  may be suitable for tool driving spindles of machines lacking automatic tool changing mechanisms. Further, adapter  16  advantageously conforms to standards to assure compatibility with standardized automatic tool changing equipment, such as well known standards for such adapters: HSK; DIN ISO/DIS 12164-1 &amp; -2; ANSI 7/24 tapers; and, Japan&#39;s BT 7/24 tapers. Cutting portion  14  is generally cylindrical and comprises a cutter body  22  to which cutting elements are mounted. As illustrated in  FIG. 1 , a cutting element  18  is mounted to a support member  20  which is attached to cutter body  22 . 
   Continuing with reference to  FIG. 1 , cutting element  18  is advantageously a replaceable body seated upon a recess of a support member, such as cartridge  20  ( FIG. 2 ) and retained thereupon by screws, clamps, shims and the like to achieve a desired orientation of the cutting element with sufficient rigidity to resist dislocation of the cutting element by cutting forces. Cutting element  18  may comprise one or more cutting edges and is retained on cartridge  20  to expose at least one cutting edge for contact with a workpiece while tool  10  is rotated. The cutting edge so arranged is referred to as the “active cutting edge”. Adjustment of the position of cutting element  18  relative to tool  10  is achieved by adjustment of the position of, at least, the portion of cartridge  20  to which cutting element  18  is affixed by a drive member within tool  10 . 
   Cutting element  18  advantageously comprises a replaceable insert made of hard materials, such as high-speed steel, cemented tungsten carbide, ceramic materials, and the like, as are well known. The replaceable insert is advantageously made to include particular geometric features to enhance cutting performance in particular applications, including relief surfaces, chipbreaking features, chip controlling grooves and the like, all as are well known. Further, the replaceable insert may be formed to effect particular orientations of the cutting edges relative to the cutting tool axis of rotation as the inserts are mounted to the tool body, as is well known. Replaceable inserts usable in the present invention may be of a wide variety of shapes and sizes chosen for the particular type of machining to be performed all as are well known. 
   Referring to  FIG. 2 , cartridge  20  is pivotally mounted to cutter body  22  by pivot pin  24 . Cartridge  20  is pivoted on pin  24  by radial displacement of a drive member such as follower  26  (see FIG.  3 ). Advantageously, to effect radial displacement of the drive member, and hence changes of radial position of cutting element  18 , without transverse mounting of an actuator, a push rod  40  is interposed between follower  26  and an actuator. Head  28  of follower  26  engages driving region  42  of push rod  40 , reciprocation of push rod  40  parallel to the longitudinal axis of tool  10  being converted to radial motion of follower  26 . Hence, push rod  40  and follower  26  are effective to convert motion of an actuator along a first vector to motion of the driving member along a second vector intersecting the first vector. A restoring force opposing displacement of follower  26  is provided by biasing member  30  (shown dashed in FIG.  2 ). Advantageously, biasing member  30  acts on follower  32  engaging restoring region  44  of push rod  40 , whereby the restoring force can be varied within the span of displacement of follower  26 . Hence, where biasing member  30  comprises a spring or other resilient member wherein the restoring force is a function of the effective length of the resilient member, the restoring force may be kept substantially constant throughout the travel of follower  26 . 
   Referring to  FIG. 3 , an alternative arrangement for cutting element cartridge  21  is illustrated in an enlarged partial section. Cutting element cartridge  21  is attached to cutter body  22  by a fixed mounting using mounting screws  50  and  52  so as to leave a portion of cutting element cartridge  21  free from cutter body  22 . Follower  32  engages the free portion of cutting element cartridge  21 . Displacement of follower  32  away from push rod  40  elastically deforms cutting element cartridge  21  to radially adjust the position of cutting element  18  relative to cutter body  22 . The elastic deformation of cutting element cartridge  21  provides a restoring force without use of an additional member such as biasing member  30  illustrated in FIG.  2 . 
   Irrespective of whether the cutting element cartridge is pivotally mounted to cutter body  22  as shown in  FIG. 2  or attached by a fixed mounting as shown in  FIG. 3 , reciprocation of push rod  40  within cutter body  22  displaces driving region  42  relative to follower  26 . As shown in the enlarged partial sectional view of  FIG. 4   a , with push rod  40  advanced, oblique surface  46  ( FIG. 4   b ) of driving region  42  engages oblique surface  48  of head  28  to displace follower  26  away from push rod  40 . As shown in the enlarged partial sectional view of  FIG. 4   b , with push rod  40  retracted, oblique surface  46  of driving region  42  is disengaged from oblique surface  48  ( FIG. 4   a ) of head  28  allowing the restoring force of biasing member  30  to displace follower  28  toward push rod  40 . The radial displacement of follower  26  effects rotation of cartridge  20  about pivot pin  24  altering the position of cutting element  18  relative to cutter body  22 . 
   Continuing with reference to  FIG. 2 , reciprocation of push rod  40  is effected by hydraulic force multiplier  70  within cutter body  22  and restoring spring  56  fitted between end face  58  of push rod  40  and seat  60  of cavity  62  in cutter body  22 . Force multiplier  70  responds to application of a control force, advantageously provided by a variable pneumatic pressure, to produce sufficient force to overcome the restoring force of spring  56  to advance push rod  40  to compress spring  56 . Push rod  40  and force multiplier  70  may be advantageously mechanically connected by attachment of push rod  40  to piston  74  of force multiplier  70 . In  FIG. 2  an interfitting connection is shown in dashed lines at the interface of push rod  40  and piston  74 , the dashed lines representative of, for example, a threaded connection whereby stand off of push rod  40  from piston  74  is adjustable. Not shown in  FIG. 2 , there will be provided conventional facilities for locking the connection of push rod  40  and piston  74  once the desired stand off has been established. With a mechanical connection of push rod  40  and piston  74 , as an alternative arrangement to single spring  56  acting on push rod  40 , one or more springs may be arranged to act directly on piston  74 . 
   Force multiplier  70  comprises small piston  72  and large piston  74 . Large piston  74  is slidably supported within cavity  80  in the interior of cutter body  22 . Force multiplier  70  further comprises small bellows  76  surrounding small piston  72  and large bellows  78  surrounding the volume within which small piston  72  is displaceable. Small bellows  76  and large bellows  78  are advantageously formed of material permitting repeated compaction and expansion along their respective longitudinal axes without perforation from deformation of the bellows folds. Applicants have chosen metallic bellows for both small bellows  76  and large bellows  78 . A rearward extension of mounting flange  82  closely surrounds a portion of small bellows  76 , large bellows  78  surrounds the rearward extension of mounting flange  82  surrounding small bellows  76 , and mounting flange  82  is rigidly fixed to the interior of cutter body  22 . It will be seen that adjustment of stand off of push rod  40  from large piston  74  permits compensation for manufacturing tolerances of the distance from the fixing surface of mounting flange  82  to large piston  74  with large bellows  78  relaxed, i.e. neither expanded nor compacted. The portion of mounting flange  82  surrounding small bellows  76  serves to maintain alignment of small bellows  76  along the longitudinal axis of cavity  80  as small bellows  76  is compacted and expanded. A forward extension of large piston  74  is slidably received within a bore (shown dashed in  FIG. 2 ) of small piston  72 , this sliding engagement maintaining alignment of small piston  72  and large piston  74 . A front end of small bellows  76  is fixed to the rear of small piston  72  to form a seal therewith and a rear end of small bellows  76  is fixed to the front face of the rear end of flange  82  to form a seal therewith. A front end of large bellows  78  is fixed to the rear of the front end of flange  82  to form a seal therewith and a rear end of large bellows  78  is fixed to the front face of large piston  74  to form a seal therewith. 
   By virtue of the sealed attachments of the front and rear ends of large bellows  78  and small bellows  76  as described, a volume is contained within the space surrounded by large bellows  78  and small bellows  76  whereby hydraulic force multiplier  70  constitutes a totally enclosed force multiplier. The totally enclosed volume is filled with an essentially incompressible fluid. As small piston  72  is moved in the direction of large piston  74 , collapsing small bellows  76 , the fluid displaced applies a force on the front face of large piston  74 . With sufficient force thereby applied to large piston  74  to overcome the restoring force of spring  56 , large piston  74  moves away from small piston  72 , expanding large bellows  78 . By virtue of the ratio of effective areas of large piston  74  and small piston  72 , a relatively small force acting on small piston  72  is multiplied to a relatively large force acting on push rod  40 . Further, by virtue of the ratio of the relatively small diameter of small bellows  76  and the relatively large diameter of large bellows  78 , a relatively large translation of small piston  72  is converted to a relatively small translation of large piston  74 . Hence, precise changes of location of cutting element  18  relative to tool  10 , precisely changing the effective machining dimension of tool  10 , may be made within the range of adjustment permitted by the range of travel of large piston  74 . The use of surrounding bellows in force multiplier  70  overcomes the chronic leaking of known hydraulic force multipliers operating with pistons sealed within fixed volume cavities by sliding seals. 
   Continuing with reference to  FIG. 2 , front face  84  of small piston  72  abuts cuphead  86 . Cuphead  86  abuts rolling diaphragm  88  fixed at its periphery to cutter body  22  so as to form a seal therewith creating a sealed volume of cavity  90 . A controlling force is applied to rolling diaphragm  88  by pneumatic pressure via channel  92  through cutter body  22 . Rolling diaphragm  88  deforms in response to pressure differences between pressure in the sealed volume of cavity  90  and the pressure applied through channel  92 . Rolling diaphragm  88  deforms so as to change the offset of the relatively large projecting central portion from the relatively narrower annular recessed portion while simultaneously changing the distance of the annular recessed portion from the surface to which the periphery of diaphragm  88  is affixed. Small piston  72  is moved in response to the force applied by deformation of rolling diaphragm  88  and the restoring force of spring  56  transferred through force multiplier  70 . A restoring spring  94  is interposed between the interior of cuphead  86  and the front face of the front end of mounting flange  82  and surrounding the portion of small bellows  76  projecting forwardly beyond mounting flange  82 . Restoring spring  94  provides a restoring force to return rolling diaphragm  88  to its equilibrium shape. Hence, by controlling the pneumatic pressure applied through channel  92 , deformation of rolling diaphragm  88  can be controlled, and location of small piston  72  within its range of motion can be controlled. Since relatively large changes of location of small piston  72  effect relatively small changes of location of large piston  74 , precise adjustment of the location of cutting element  18  relative to tool  10  can be achieved with regulation of the applied pneumatic pressure. Hence, precise adjustment of effective machining dimensions of tool  10  can be achieved throughout the range of displacement of cutting element  18  by controlling the applied pneumatic pressure. 
   While the invention has been described with reference to a preferred embodiment, and the preferred embodiment has been described in considerable detail, it is not the intention of the applicants that the invention be defined by the preferred embodiment. Rather, it is the intention of the applicants that the invention be defined by the appended claims and all equivalents thereto.