Abstract:
A cutting die head that can be set and/or reset without an external mechanism. To this end, the die head includes a die body including a plurality of radially adjustable blocks, each block having a cutter mounted thereon and a radially outwardly facing cam surface. A sleeve surrounds the die body and has an inner surface. The inner surface has a plurality of cam surfaces arranged to communicate with the cam surfaces of the blocks such that axial movement of the sleeve results in radial movement of the blocks. In one embodiment the sleeve is caused to move axially by fluid pressure.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention generally relates to a cutting die head; specifically a cutting die head designed for use on a machine tool having a fixed or revolving spindle, wherein the cutting die head does not require an external resetting or setting means. 
   2. Description of the Related Art 
   Automatic cutting die heads with external trips and resets are known in the art. U.S. Pat. No. 1,057,014, to O. A. Smith, describes a threading die for use with a stationary spindle that utilizes a lever extending from the die head as a resetting mechanism. Use of such an external lever greatly limits the potential use of the die head. 
   A cutting die head with an improved mechanism for tripping and resetting is described in U.S. Pat. No. 1,952,205, to W. J. Hogg. This device is described as a die head of simple construction having circular cutters or chasers. The die head utilizes an external mechanism such as a yoke, interacting with a grooved collar to trip and reset the die head. This improved mechanism eliminates the need for a fixed lever on the die head and allows for the die head to be used in rotating as well as stationary spindle applications. However, use of such an external mechanism still limits the die head to what machines it may be used on. 
   SUMMARY OF THE INVENTION 
   The invention is directed to a die head that can be reset without an external mechanism. To this end, the die bead of the invention comprises a die body having a front face and a rear face having a rearwardly extending hollow shank terminating in a shank end, a sleeve, a plunger, and a fluid such as, but not limited to: air, oil, or a suitable coolant of a type well known in the art. The front face is has a plurality of slots each provided with a radially adjustable block. Each block has a cutter mounted thereon and a cam surface directed radially outward. The sleeve surrounds the die body and has an inner surface with a plurality of inwardly directed cam surfaces. The cam surfaces of the sleeve are arranged to communicate with the cam surfaces of the blocks in a manner such that axial movement of the sleeve results in radial movement of the blocks. The plunger is positioned within the hollow shank and attached to the sleeve through at least one slot in the hollow shank in a manner such that the sleeve and plunger assembly can slide axially along the hollow shaft a distance delineated by the length of the slot. The fluid is supplied from a reservoir to the shank end. An increase in pressure of the supplied Thud results in the plunger and sleeve assembly being forced toward the front face of the die body causing the blocks and attached cutters to move radially inward setting the die head for a cutting cycle. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further features of the present invention, as well as the advantages derived therefrom, will become clear from the following detailed description made with reference to the drawings in which: 
       FIG. 1  is a partial sectional view of the die head; 
       FIG. 2  is a sectional view of the die head; 
       FIG. 3  is a sectional view of the plunger and adjusting screw; 
       FIG. 4  is a perspective view of the adjusting ring; 
       FIG. 5  is a perspective view of the split ring; 
       FIG. 6  is a side elevational view of the sleeve and head; and 
       FIG. 7  is an exploded view of the entire die head assembly. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Before explaining in detail the present invention and operation thereof, it is to be noted that the invention is not limited to the details of construction and arrangement of parts which are illustrated in the accompanying drawings, since the invention is capable of other embodiments, and that the phraseology employed is for the purpose of description and not of limitation. It is to be noted that the following preferred embodiment of the invention utilizes a modified Vers-O-Tool Model DRF die head (described in detail in U.S. Pat. No. 1,952,205 herein incorporated by reference) but the present invention is not limited to use with just such model cutting die head but may be incorporated into other die head designs. 
   With reference to  FIGS. 1–7 , wherein like numerals designate like components throughout all of the figures, there is illustrated a die head  10  for use in a machine tool generally with either a revolving spindle or a fixed spindle (not shown). The die head  10  comprises a hollow die body  12  having a front face  12   a , a rear face  12   b , and a hollow shank  14  extending rearwardly from the rear face and terminating in a shank end  14   b . The hollow shank  14  has an inner surface  14   c , an outer surface  14   d , and one or more shank notches  15  in the walls along the shank  14 . The outer surface  14   d  has a flat  14   e  having a pressure relief hole  16  near the shank end  14   b , a circumferential groove  14   f  near the die body  12 , and an axial groove  14   g  extending axially from the circumferential groove  14   f  toward the shank end  14   b  (See  FIG. 7 ). The shank end  14   b  is adapted for attachment to the spindle of the machine tool (not shown) capable of supplying, for example a fluid  18  from a reservoir as well known in the art (not shown). A sleeve  20  surrounds the die body  12  extending from the front face  12   a  rearward. The sleeve  20  has a groove, shown generally at  22 . The sleeve  20  includes one or more notches  24  (See  FIGS. 6–7 ) extending radially through the base of the groove  22 . A split ring  26  (See  FIG. 5 ) having at least one or more threaded holes  28  aligned within the length of the notch(es)  24  is adapted to fit within the groove  22 . The split ring  26  is secured in the groove  22  by screws  29  (See  FIGS. 5 and 7 ). 
   Within the hollow shank  14  near the shank notch(es)  15  is a plunger  30  (see  FIGS. 2 &amp; 3 ) of sufficiently small cross-section to fit within the hollow shank  14 . The plunger  30  has a threaded hole  32  on its central axis and a smooth through-hole  34  perpendicular to the threaded hole  32 . The threaded hole  32  of the plunger  30  receives a die trip adjusting screw  36 . The smooth through-hole  34  is aligned such that at least one pilot screw  38  may threadedly engage a threaded hole  28  of the split ring  26  while passing through a shank notch  15  and fitting into the smooth through-hole  34  of the plunger  30  (See  FIG. 2 ). The sleeve  20  is thus rigidly pinned to the plunger  30  by at least one pilot screw  38 . 
   Situated within the hollow shank  14  between the plunger  30  and the shank end  14   b  is a pusher  40 . The pusher  40  is movable axially within the hollow shank  14 . The surface of the pusher  40  is sufficiently sealed against the inner surface  14   c  of the hollow shank  14  such that there is adequate pressure from the fluid  18 , supplied from a reservoir into the center section from the shank end  14   b , to cause the pusher  40  to slide into and “push” the plunger/sleeve assembly toward the front face  12   a  of the die body  12 . The surface of the plunger  40  is sealed against the inner surface  14   c  of the hollow shank by means of at least one o-ring  42  (See  FIG. 2 ). It will be appreciated that excess fluid that passes the pusher  40  can serve as a coolant and/or lubricant for the die head. In an alternative embodiment, the plunger  30  and pusher  40  my be operatively combined into a single element wherein the plunger  30  in addition to functioning as previously described also is sufficiently sealed against the inner surface  14   c  of the hollow shank  14  to be set internally by an increase in pressure of the fluid  18  as previously described. 
   The front face  12   a  is provided with a plurality of receiving slots  44  (see  FIG. 7 ) shown herein as four in number. The number of receiving slots  44  is not limited to four in number but may be more or less as desired for a specific application. Each of the receiving slots  44  is of a T-shaped cross-section for the reception of a one piece, stepped, correspondingly shaped block  46 . The block  46  has a cutter  48  suitably secured thereto. The cutters  48  may include, but are not limited to the following: chasers, turning cutters, grooving cutters, burnishing tools, knurling tools, and the like. In a preferred embodiment, the cutter  48  as shown in  FIG. 7 , includes: a chaser  48   a , a screw  48   b , and a serrated bushing  48   c . Each block  46  has an axial cam surface  52  that interacts with a corresponding axial cam surface  54  on the sleeve  20 . Each block  46  is provided with a rearwardly extending pin  56  projecting into a slot  58  in the rear of the T-shaped receiving slots  44  of the front face  12   a . Each of these slots  58  has a spring  60  and headed plunger  62  located in position to engage the rearwardly extending pin  56  of the block  46  thereby shifting each block  46  along with attached cutter  48  radially outwardly when the sleeve  20  is withdrawn away from the front face  12   a  of the die body  12 . Adjoining each slot  58  containing the spring  60  and headed plunger  62  is a threaded hole  63  having a screw  63   a  threadedly engaged to retain the spring  60  and headed plunger  62  and thus the blocks  46  within each of the receiving slots  44 . The springs  60  also hold the blocks  46  with their cam surface  52  in engagement with the cam surface  54  of the sleeve  20  and by the action of the springs the cutters  48  are opened or released at the proper time. Each of the blocks  46  is also provided with what is designated as a land surface  64  curved circumferentially of the die but straight in the direction of the depth of the die for cooperation with a radial cam surface  66  of the sleeve  20 . Upon relative rotation of the body  12  and sleeve  20 , the blocks  46  with attached cutters  48  may be finely adjusted to make the proper cut. 
   Located within the sleeve  20  is an adjusting ring  68  (See  FIGS. 1 &amp; 4 ) having a fixed guide pin  70  and a fixed stop pin  71  extending toward the rear face  12   b  of the die body  12 . The guide pin  70  is positioned to project into an opening in the rear face  12   b  of the die body  12 . A float bushing  72  is retained in a radial bale  72   b  in the die body  12  by a spring clip  72   c  (See  FIG. 7 ). The guide pin  70  passes through the float bushing  72  thus preventing radial movement between the die body  12  and the adjusting ring  68  while permitting axial movement between the two. The stop pin  71  provides a gap between the adjusting ring  68  and the rear face  12   b  of the die body  12 . The adjusting ring  68  is held against movement axially of the sleeve  20  by a shoulder screw  73  projecting through a slot  74  formed in the adjusting ring  68  that threadedly engages a threaded hole in the sleeve  20  (See  FIG. 7 ). The slot  74  permits rotary movement of the adjusting ring  68  and the sleeve  20 . Circumferential movement is obtained by a pair of adjusting screws  76  carried in suitable threaded openings  76   a  of the sleeve  20  (See  FIG. 7 ). These screws  76  engage lugs  78  projecting from the opposite side of the adjusting ring  68  from the guide pin  70 . The lugs  78  project into recesses  80  located in the rear wall of the sleeve  20 . By adjusting these screws  76 , one inward and the other outward, the adjusting ring  68  and the die body  12 , owing to the connecting guide pin  70  may be rotated relative to the sleeve  20 . This rotary movement of the die body  12  causes the cutters  48  to move radially inward toward the work piece or outwardly therefrom, according to the adjustment desired, owing to the radial cam surfaces  66  hereinbefore referred to on the sleeve  20 , which engage the land surfaces  64  of the blocks  46 . By this means, the cutters  48  are adjusted for the proper diameter of the work piece to be cut Once the appropriate adjustment is obtained, one or more locking screws  82  carried in suitable threaded openings of the sleeve  82   a  are tightened to prevent relative movement of the sleeve  20  and adjustment ring  68  (See  FIG. 7 ). 
   Now, with reference to  FIG. 2 , a detailed operation of the present invention will be described. The fluid  18 , as supplied to the shank end  14   b  of the hollow shank  14  through the spindle of the machine (not shown), may fill and pressurize the hollow shank  14 . The pusher  40  is situated such that by pressurizing the interior of the hollow shank  14  with fluid  18 , the pusher  40  is caused to slide from the shank end  14   b  of the hollow shank  14  toward the die body  12 . As the pusher  40  slides toward the die body  12 , the pusher contacts and pushes the plunger  30  and the rigidly attached sleeve  20  toward the front face  12   a , thus engaging the cutters  48  to the work piece (not shown). Dependent on the application, the work piece or die head may be rotated resulting in the distance between the work piece and die trip adjusting screw  36  of the plunger  30  to decrease. As the work piece (not shown) and adjusting screw  36  engage, the inward movement of the work piece relative to the die head  10  pushes the plunger  30  and sleeve  20  assembly rearward away from the cutters  48  thus tripping the die head  10  and releasing the work piece from the cutters  48 . A retaining plunger  84 , held in a radial hole in the sleeve  20 , limits travel of the sleeve  20  to the length of the axial groove  14   g  (See  FIG. 7 ). The retaining plunger  84  is held in the sleeve  20  by a retaining screw  84   b  and forced into the axial groove  14   g  by a retaining spring  84   c . Once the work piece is removed, the pressure of the fluid  18  is increased thus resetting the die head  10  for another cutting cycle without application of an external resetting means. 
   All documents, patents, and patent applications referred to herein are hereby incorporated by reference. While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation. Various modifications and additions will become apparent to persons of ordinary skill in the art. All such variations and modifications are intended to be encompassed within the scope of this patent, which is limited only by the claims appended hereto. The scope of the appended claims should be construed as broadly as the prior art will permit.