Abstract:
A machining system includes a tool head having a yoke, a housing pivotally mounted to the yoke and a collet rotatable in the housing. The collet includes a tool head rocker driven by fluid to allow rocking of a tool relative to the collet in a plane normal to the housing pivotal axis in the yoke. The machining system also includes a source of constant liquid pressure and a source of constant gas pressure. The collet has pressure chambers in communication with the sources of constant pressures to bias the rockable collet assembly. The collet/tool axis is arranged to trail in the direction of relative motion when the contour of the work is moving away from the tool head and to lead when the contour of the work is approaching the tool head.

Description:
RELATED APPLICATION 
       [0001]    Applicant claims priority from U.S. Provisional Application Ser. No. 61/802,569, filed Mar. 16, 2013, the disclosure of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The field of the present invention is machines for deburring machined parts and for other machining tasks controlled by automation control. 
         [0003]    Deburring machines are well known in the machining industry for removing sharp burrs and/or producing chamfers and the like remaining after the machining process. Such machines may also be used for parts formed through casting and other techniques which need cleaning of surfaces and/or edge machining. Such devices typically include deburring heads mounted to mounts including orthogonal mounts which allow positioning of the deburring heads to address work on work supporting spindles. More than one deburring head is often included in a given system. The heads themselves are typically adjustable for exacting placement and motion. 
         [0004]    A deburring machine from which the present embodiment has evolved is illustrated and disclosed in U.S. patent application Ser. No. 12/549,138, filed Aug. 27, 2009, the disclosure of which is incorporated in its entirety herein by reference. In this prior disclosure, a deburring machine is illustrated which includes a housing with a chamber which is open upwardly. A conventional work supporting spindle is located on the floor of the chamber. An orthogonal mounting fixed atop the housing is made up of conventional components to define two degrees of freedom in a horizontal plane. Two deburing heads are shown supported by the orthogonal mounting. The two deburring heads are further mounted on the orthogonal mounting by vertically translating mounts to provide a third degree of freedom to the deburring heads which extend into the chamber. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention is directed to a machining system having a tool head with a collet assembly in a gimbaled mount receiving a tool. The collet assembly provides a further degree of freedom to a mounted tool to rock in the mount toward and away from the work. This rocking is biased by constant fluid pressure toward the work. A chamber or chambers communicate the pressure force to the tool. The fluid pressure may be compressible, incompressible or both. 
         [0006]    The machining system may be driven such that the collet/tool rotational axis trails the tool head in relative motion of the head across the work when the contour of the work is receding from the head. The collet/tool rotational axis leads the tool head in relative motion of the head across the work when the contour of the work is advancing toward the head. 
         [0007]    Therefore, it is a principal object of the present invention to provide a machining system with an improved drive system and tool head for automated machining processes such as deburring having an advantaged accommodation of work anomalies. Other and further objects and advantages will appear hereinafter, 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a perspective view of a deburring system. 
           [0009]      FIG. 2  is an upward perspective view of the deburring system. 
           [0010]      FIG. 3  is cross-sectional front view of a deburring system with a vertically translating mount. 
           [0011]      FIG. 4  is a cross-sectional front view detail of the drive system of the deburruing system of  FIG. 3 . 
           [0012]      FIG. 5  is a cross-sectional detail view of the deburring head of the deburruing system of  FIG. 3  taken through the housing assembly mounting axis. 
           [0013]      FIG. 6  is a perspective view of the tool mount housing assembly of the deburruing system of  FIG. 3 . 
           [0014]      FIG. 7  is a schematic representation of caster angle of a tool relative to work profile. 
           [0015]      FIG. 8  is a side view showing range of motion of a tool. 
           [0016]      FIG. 9  is a front view of a tool. 
           [0017]      FIG. 10  is a top view of the tool. 
           [0018]      FIG. 11  is a cross section taken along line  11 - 11  of  FIG. 9 . 
           [0019]      FIG. 12  is a cross section taken along line  1212  of  FIG. 9 . 
           [0020]      FIG. 13  is a cross section taken along line  13 - 13  of  FIG. 10 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0021]    Turning in detail to the drawings, an orthogonal mounting  10  defining two degrees of freedom in a horizontal plane of a machining system such as the deburring machine described in the Background of the Invention above and detailed here as the preferred embodiment supports a vertically translating mount  12 . This mount  12  includes a mount housing  14  fixed to the orthogonal mount  10 . The orthogonal mounting  10  and the vertically translating mount  12  are controlled in the three degrees of freedom by linear motion systems  16  such as a ball screw assembly, rack gear, or other linear motion system, controlled by a servo motor, or other positional control devices. 
         [0022]    A top  18  for a deburring chamber is illustrated in  FIG. 2 . A rectangular opening to receive the deburring equipment is obscured by closure sheets  20 ,  22 ,  24 ,  26 . These closure sheets are each mounted on a spring roller  28 ,  30 ,  32 ,  34 , respectively, and drawn out under tension from the respective spring roller to engage a plate  36  fixed with the mount housing  14  at the rectangular opening in the top  18 . Two of the spring rollers  28 ,  30  are mounted to the top  18 . The other two spring rollers  32 ,  34  are slidably mounted to the move laterally toward and away from the first spring rollers  28 ,  30  to maintain a closure of the top  18 . 
         [0023]    A deburring assembly  38 , seen in  FIG. 3 , extends from inside the mount housing  14  where it is slidably mounted and driven vertically along its principal axis by a conventional linear motion system  16 . The deburring assembly  38  includes a series of four concentrically arranged tubes with a drive system  40 , seen in detail in  FIG. 4 , at the proximal end and a tool head, seen in  FIG. 5 , at the distal end. The tool head is illustrated as a deburring head  42  in the preferred embodiment. The outermost tube  44  is slidably mounted in a guide  46  and is vertically controlled by the linear motion system  16  controlling the third degree of freedom. The guide  46  is located between the mount housing  14  and the plate  36 . The outermost tube  44  is constrained from rotating relative to the mount housing  14 . 
         [0024]    There are three rotatably mounted positioning tubes  48 ,  50 ,  52  arranged within the outermost tube  44 . Each has bearings that allow individual and independent rotation. The drive system  40  at the top vertical end of the tube  44  includes a mounting plate  54  fixed to the outermost tube  44 . The mounting plate  54  supports three motion controlled drive systems  56 ,  58 ,  60  that drive the positioning tubes  48 ,  50 ,  52 , respectively. The positioning tubes  48 ,  50 ,  52  are rotatably driven by a gear set, chain, belt or another synchronized drive system controlled by a CNC machine or equivalent. 
         [0025]    Looking then to the deburring head  42 , the outermost tube  44  does not engage the deburring head  42 . The innermost positioning tube  48  extends to engage a yoke assembly  62 . The yoke assembly  62  can be rotated by the innermost positioning tube  48  without limit. The yoke assembly  62  includes an integral inwardly extending mounting pin  64 . An opposed mounting pin  66  is free to rotate relative to the yoke assembly  62 . 
         [0026]    The outermost positioning tube  50  pivotally positions a housing assembly  68  about the mounting pin  64  and the opposed mounting pin  66 . The housing assembly  68  is coupled with the positioning tube  50  through gearing or other drive train means. A first gear wheel  70  is fixed at the end of the positioning tube  50  and engages a pinion  72 . The pinion  72  engages a crown gear  74 , The crown gear  74  has a spur gear thereon which engages idler spur gear  76  which, in turn, engages a final spur gear  78  fixed to the housing assembly  68  about the axis defined by the pin  64  and the opposed mounting pin  66 . This gear train is rotatably mounted in the yoke assembly  62 . In this way, the housing assembly  68  can be driven in pitch motion for more than a total of 280° of arc symmetrical to the axis of the deburring assembly  38 . 
         [0027]    A collet assembly  80  is mounted inside the housing assembly  68 . The collet assembly  80  can rotate with continuous rotations without limits in the housing assembly  68 . In a similar arrangement to the drive for the housing assembly  68 , the collet assembly  80  is engaged through a gear train with the middle positioning tube  52 . The gear train includes a first gear wheel  82  fixed at the end of the middle positioning tube  52  and engages a pinion  84 . The pinion  84  engages a crown gear  86 . The crown gear  86  has a spur gear thereon which engages idler spur gear  88  which, in turn, engages a final spur gear  90  fixed to the opposed mounting pin  66 . The opposed mounting pin  66  supports a further spur gear  92  fixed thereto which engages another crown gear  94  fixed to the collet assembly  80 . This gear train is also rotatably mounted in the yoke assembly  62 . 
         [0028]    The positioning tube  48  has several individual holes thru its entire length that transmit fluids and gases through these holes from the upper end thereof, These holes are plugged at each end and other holes are drilled and staggered radially to intersect, the longitudinal holes to allow transfer, of the fluids, and gases. At the top of the positioning tube  48 , there is rotary high pressure manifold that connect the passages in the positioning tube  48 . The manifold allow fluid transfer, irrelevant to the positioning tube  48  rotating or being stopped. The manifold is mounted to the motion control plate  54 . The yoke assembly  62  at the bottom routs these passages. The yoke  62  is made of arms and a center block  96 . Through sealed passages in the yoke assembly  62 , the fluids and gases are routed to the collet assembly  80 . The fluids and gases are transferred to the collet assembly  80  by a dynamic seal joint. 
         [0029]    Inside the collet assembly  80 , there is a cone shaped tapered bore  98  with a latch system that receives various tools to be quickly removed and replaced using an optional automatic tool changing system. The tapered bore  98 , in the collet assembly  80 , has a series of seals that, when a tool assembly is inserted and latched into place, are properly sealed against fluid or gas leaks, yet the tools can be changed out without significant force or effort in a non precision manner. The tapered shape promotes self alignment and engagement. The unique tapered bore coupling with fluid transfer allow interchangeable tools to be driven or controlled by these fluids and gasses. 
         [0030]    The collet assembly  80  includes a shaft  100  which is positioned and can rotate within a cavity  102  in the housing assembly  68 . A fluid passageway through the yoke assembly  62  passes through the pin  64  to the housing assembly  68  and then through a rotary junction to the collet assembly  80 . Other passageways can provide gas or liquid to the collet assembly  80 . The cavity  102  has a lapped precision fit with the collet shaft  100  to control gas and liquid pressures from escaping in an uncontrolled manner. Holes are provided in the outer diameter of the collet shaft  100  to intersect the gas and liquid sources to allow the fluids to enter the cavity  102 . Annular pressure and relief grooves supply pressurized fluid and vent any fluid leakage flowing axially of the collet shaft  100  back to a return passage. 
         [0031]    A tool  104  is mounted to the collet assembly  80 . The tool  104  is of the type including a hydraulic drive  105  to rotatably drive a machining implement on the shaft  106 . The collet assembly  80  includes a central cavity  107  to mount the tool  104  about a pivot axis. 
         [0032]    A shaft assembly  108  defines the pivot axis and includes a component fixed to the tool  104  to rock therewith. A pressure biased suspension  110  for the tool  104  provides a rocking of the tool  104 . This degree of freedom is in a plane perpendicular to the axis defined by the pin  64  and the opposed mounting pin  66  of the yoke assembly  62 . A crank  112  is mounted to the shaft assembly  108  to rock with the component also fixed to the tool  104 . Two pistons  114 ,  116  are engaged with the ends of the crank  112  by pinned links  118  to slide in cylinders  120 ,  122 . 
         [0033]    Pressurized fluid is provided to the cylinders to control the position of the tool  104 . Except for the rocking, the tool  104  follows a programmed path across the work. As the tool  104  moves away from the work in its programmed path, the tool  104  rocks toward the work, either by expansion of compressible fluid or a programmed supply to keep a constant pressure in the resisting cylinder  120 ,  122 . As the tool  104  moves closer to the work in its programmed path, the tool  104  can back away from the work under the same fluid control. 
         [0034]    The fluid used can be incompressible or compressible; but in this embodiment, compressible fluid is used. Compressible fluid provides a cushioning effect to the rocking position. As the plane through which the rocking is experienced is maintained by the yoke assembly  62 , the pressure is maintained by the housing assembly  68  against the collet assembly  80 . With pneumatic fluid, either the tool  104  receives pressure to one or the other cylinder  120 ,  122  and the tool  104  is pinned at one end or the other of its range of motion. Yet the fluid is compressible such that the tool  104  can flex with the work and a constant pressure can be provided by a constant pressure source, The two cylinders  120 ,  122  can also both be controlled to give interim rocking positions with control including a sensor to locate the tool  104 . The constant pressure source can be set with a magnitude of pressure selected based on the type of tool, the type of worked material and the task to be performed. With hydraulic fluid, additional fluid is introduced or released to maintain constant pressure. 
         [0035]    The employment of the rocker mechanism is further advantaged by the nominal orientation of the rotational axis of the collet assembly  80 . If the yoke assembly  62  is oriented so that the rotary axis of the collet assembly  80  and the tool trails the relative motion of the deburring head  42  across the work, a caster effect of that orientation cooperates positively with the rocking adjustment if the contour of the work is falling away. If the contour of the work is moving toward the deburring head  42  as the head moves across the work, a nominal orientation of the rotational axis of the collet assembly  80  leading the relative motion of the deburring head  42  across the work provides a caster effect to cooperate positively with the rocking adjustment. 
         [0036]    Control of the present system is reasonably uncomplicated. The normal operation of a CNC system or the like can be used for the tool head  42  to follow the nominal profile of the work. Misalignment of and anomalies in the work are accommodated for by the rocker mechanism. The constant fluid pressures can be predetermined through consideration of such factors as the type of tool, the type of worked material and the task to be performed. The CNC is further able to control the yoke assembly  62  to take a leading or trailing orientation to assist the rocking mechanism with caster as it has the data regarding the rising and falling of the work profile. Electrical sensors can also be employed as needed or convenient which are monitored by conductors through the fluid passages. 
         [0037]    Thus, an improved drive system and tool head for automated machining processes such as deburring with an advantaged accommodation of work anomalies is disclosed. While embodiments and applications of this invention have been shown and described, it would be apparent to those skilled in the art that many more modifications are possible without departing from the inventive concepts herein. The invention, therefore is not to be restricted except in the spirit of the appended claims.