Abstract:
A tool adapter includes an adaptor body having a connection portion structured to be attached to a machine tool and a holder portion disposed opposite the connection portion and a tool receiver structured to receive and couple a portion of a rotary cutting tool therein. The tool receiver is mounted in the holder portion so as to be rotatable to a limited extent. The tool receiver is mounted in the holder so as to be elastically resilient in both the axial and circumferential directions.

Description:
BACKGROUND 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates generally to tool adapters having a holder, which can be attached to a machine tool, and having a tool receiver, in which a tool can be received. 
         [0003]    2. Background Information 
         [0004]    An example tool adapter for which the present invention improves upon is shown in U.S. Pat. No. 6,082,236. Here, the tool receiver is realized as a collar, which is rotatably mounted inside the holder by means of two bearing rings. Vulcanized-in between the outer surface of the tool receiver and the inner surface of the holder there is a rubber bushing, which limits the rotation of the tool receiver relative to the holder. A torque can be transmitted from the holder to the tool receiver via the rubber bushing, while, at the same time, vibrations that occur in a radial direction can be damped. In this way, it is also possible to reduce noise produced during the machining of a workpiece by means of a toot clamped in the tool receiver. 
         [0005]    While useful for damping vibrations to a certain extent, there is still room for improvement in terms of vibration damping capabilities over conventional tool adaptors. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention provides a tool adapter that provides both damping and high torque capabilities during machining processes. The tool adapter comprises an adaptor body and a tool receiver. The adaptor body includes a connection portion structured to be attached to a machine tool and a holder portion disposed opposite the connection portion. The tool receiver is structured to receive and couple a portion of a rotary cutting tool therein. The tool receiver is mounted in the holder portion so as to be rotatable about a central axis of the tool adaptor to a limited extent. The tool receiver is mounted in the holder portion so as to be elastically resilient in both the axial and circumferential directions. 
         [0007]    The holder portion may include a number of axial grooves and the tool receiver may include a corresponding number of torque transmission elements coupled thereto and extending radially therefrom, each torque transmission element being disposed within a corresponding groove of the number of axial grooves. Each torque transmission element may comprise a rigid portion coupled to the tool receiver and an elastomeric portion disposed between the rigid portion and the tool receiver. 
         [0008]    The tool receiver may include an outer surface having a number of receivers formed therein and the rigid portion of each torque transmission element may be disposed in a corresponding receiver of the number of receivers. Each receiver may include a threaded aperture and each rigid portion may be coupled to a corresponding receiver via a setting screw threadingly engaged with the aperture. 
         [0009]    The holder portion may comprise a cavity beginning at a mouth portion, extending through a central portion, and ending with an end portion, the end portion having an end face disposed generally perpendicular to the central axis. The tool receiver may comprise a flange portion disposed in the mouth portion and a damping member provided in the mouth portion axially between the flange portion and an edge of the central portion of the cavity. 
         [0010]    The tool receiver may comprise an end portion oriented generally perpendicular to the central axis and disposed in the end portion and a damping member provided in the end portion axially between the end portion and the end face of the cavity. The damping member may be generally ring-like in shape and may have an increased thickness along is outer circumference. 
         [0011]    The tool receiver may be coupled to the adaptor body via an axial clamp screw which passes through an aperture formed in the tool receiver and threadingly engages a threaded aperture formed in the adaptor body. 
         [0012]    The axial clamp screw may comprise an elastomeric member provided between a head portion of the axial clamp screw and the tool receiver. 
         [0013]    The adaptor body may comprise a coolant passage disposed between the connection portion and the holder portion, the axial clamp screw may comprise a central passage, and the coolant passage and the central passage may be structured to provide a supply of coolant from the machine tool to the rotary cutting tool. 
         [0014]    The tool receiver may further comprise a sealing member having one or more openings disposed between the rotary cutting tool and an end portion of the tool receiver, the sealing member being structured to prevent the escape of coolant from between the rotary cutting tool and the tool receiver. 
         [0015]    These and other objects, features, and characteristics of the present invention, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which: 
           [0017]      FIG. 1  shows a sectional view of an embodiment of a tool adapter according to the present invention with a portion of a rotary cutting tool shown installed therein; 
           [0018]      FIG. 2  shows a sectional view of the adaptor body of the tool adapter from  FIG. 1 ; 
           [0019]      FIG. 3  shows a sectional view of the adaptor body of  FIG. 2  taken along line  3 - 3  of  FIG. 2 ; 
           [0020]      FIG. 4  shows a sectional view of the tool receiver of the tool adapter from  FIG. 1 ; 
           [0021]      FIG. 5  shows a sectional view of the tool receiver of  FIG. 4  taken along line  5 - 5  of  FIG. 4 ; 
           [0022]      FIG. 6  shows a sectional view of the tool adaptor of  FIG. 1  taken along the line  6 - 6  of  FIG. 1  with the rotary cutting tool removed; and 
           [0023]      FIG. 7  shows an isometric view of the tool receiver and torque transmission elements of the tool adaptor of  FIG. 1 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    Directional phrases used herein, such as, for example, left, right, front, back, top, bottom and derivatives thereof, relate to the orientation of the elements shown in the drawings and are not limiting upon the claims unless expressly recited therein. Identical parts are provided with the same reference number in all drawings. 
         [0025]    As used herein, the term “number” shall be used to refer to any non-zero quantity, i.e., one or any quantity greater than one. 
         [0026]      FIG. 1  shows a tool adapter  10  which serves to receive and couple a rotary cutting tool  12  (a portion of which is shown in phantom line in  FIG. 1 ) such as, for example, without limitation, a drill, to a machine tool (not shown) in accordance with an example embodiment of the present invention in a manner such that tool adaptor  10 , and thus rotary cutting tool  12 , can be rotated about a central axis M by the machine tool. Rotary cutting tool  12  can be clamped in the tool adapter  10  via a clamping mechanism  14 . In the example illustrated embodiment, rotary cutting tool  12  is shown as having a Weldon shank which is engaged by the clamping mechanism  14  (e.g., without limitation, two setscrews), it is to be appreciated, however, that other cooperating arrangements for clamping a rotary cutting tool may be employed without varying from the scope of the present invention. Tool adapter  10  includes an adaptor body  16  having a connection portion  18  which is adapted to be clamped into a machine tool (not shown) such that rotary cutting tool  12  can be driven, for example, made to rotate. 
         [0027]    Referring to  FIG. 2 , adaptor body  16  further includes a holder portion  20  disposed generally opposite connection portion  18 . Adaptor body  16 , as well as connection portion  18  and holder portion  20  is made of metal. Continuing to refer to  FIG. 2 , holder portion  20  has a generally collar-type form and includes a cavity  22  formed therein. Cavity  22  is disposed about the central axis M and, moving inward, is generally defined beginning at a generally cylindrical mouth portion  24  having a first diameter d 1 , a generally cylindrical central portion  26  having a second diameter d 2 , and a generally cylindrical end portion  28  having a third diameter d 3 . In the example embodiment illustrated in  FIG. 2 , first diameter d 1  is greater than second diameter d 2 , which is greater than third diameter d 3 . Cavity  22  is further defined by an end face  30  of holder portion  20 , which is aligned perpendicularly in relation to center axis M. In the example embodiment illustrated, end face  30  transitions into the wall of end portion  28  via a radiused portion  31 . 
         [0028]    Referring to  FIGS. 2 and 3 , central portion  26  of cavity  22  includes a plurality of outwardly extending axial grooves  32  (five are shown in the illustrated example embodiment) distributed around the circumference thereof. As shown in  FIG. 2 , each of axial grooves  32  extend longitudinally from mouth portion  24  to a short end face  34  disposed generally perpendicular to central axis M such that each of the axial grooves  32  are disposed generally parallel to central axis M. As shown in  FIG. 3 , each axial groove  32  is generally defined circumferentially by two lateral surfaces  36 ,  38  and a curved outer surface  40 . The two lateral surfaces are disposed opposite each other in the circumferential direction and aligned perpendicular to short end face  34 . It is to be appreciated that the particular cross-sectional shape of each axial groove  32  described herein is given for example purposes only and that one or more of the dimensions of shape of such grooves may be varied without varying from the scope of the present invention. 
         [0029]    Referring again to  FIG. 1 , tool adaptor  10  further includes a tool receiver  42  disposed within holder portion  20  of adaptor body  16 . Tool receiver  42  is realized in the form of a collar disposed about a cavity  44  ( FIG. 4 ) in which the rotary cutting tool  12  can be disposed and selectively coupled, such a via clamping mechanism  14 . Referring to  FIG. 4 , similar to adaptor body  16 , tool receiver  42  is composed of metal, and has a generally cylindrical outer surface  46  extending from a flange portion  48 , disposed adjacent the opening (not numbered) of cavity  44 , to an opposite end portion  50  disposed generally perpendicular to central axis M. Outer surface  46  transitions into an outer face  52  (also disposed generally perpendicular to central axis M) of end portion  50  via a beveled portion  54 . As shown in the sectional view of  FIG. 1 , the flange portion  48  of the tool receiver  42  is dimensioned to match the dimensions of the mouth portion  24  of the cavity  22  and the outer surface  46  of the tool receiver  42  near the beveled portion  54  is dimensioned to match the dimensions of the end portion  28  of the cavity  22  such that the tool receiver  42  is received without play inside the holder portion  20  of the adaptor body  16  in a manner such that the tool receiver is aligned with the central axis M. As used herein, the phrase “without play” means that the mouth portion  24  and end portion  28  of cavity  22  define the alignment of the tool receiver  42  in the area of the flange portion  48  as well as the outer surface  46  near the beveled portion  54 , in a precise manner, while, at the same time, the tool receiver  42  can be rotated inside the holder portion  20 . In the example embodiment illustrated, such arrangement provides for two degrees of freedom in potential movement of the tool receiver  42  within the holder portion  20 , axial (movement along central axis M) and tangential (rotation about central axis M). 
         [0030]    In the example embodiment illustrated, tool receiver  42  includes a pair of threaded apertures  55  which, as shown in  FIG. 1 , are threadingly engaged by the clamping mechanism  14 , previously discussed. As a result of such arrangement, the rotary cutting tool  12  is rigidly coupled to the tool receiver  42  only, and thus is not rigidly coupled to the adaptor body  16 . As shown in  FIGS. 1 and 2 , a pair of access ports  56 , each sized larger than clamping mechanism  14  are provided in the adaptor body  16  in order to provide access to clamping mechanism  14  and avoid any rigid engagement between the clamping mechanism  14  and the adaptor body  16 . The full benefits of such arrangement will become readily apparent with the further discussion below. 
         [0031]    Referring to  FIGS. 4 and 5 , the outer surface  46  of the tool receiver  42  is provided with a number of receivers  60  (five are shown in the illustrated example embodiment), which correspond to the axial grooves in the cavity  22  of the holder portion  20 , and in each of which a partially elastic torque transmission element  62  can be disposed, which in the illustrated example embodiment is realized in the form of a vulcanized feather key (see,  FIGS. 1 ,  6  and  7 ). It is to be appreciated that the quantity of transmission elements  62  and corresponding receivers  60  may be varied depending on one or more of the particular size or machining application in which the tool adaptor  10  is employed. It is also to be appreciated that the greater the quantity of partially elastic torque transmission elements employed, the better the damping provided. However, the size of the elements and the added cost associated with increasing the quantity of components are generally limiting factors. 
         [0032]    As shown in the sectional views of  FIGS. 1 and 6 , each vulcanized feather key includes a base portion  64  formed from metal and an upper portion  66  formed from an elastomer, plastic, or other suitable material which is softer that the adjacent metal portions and thus prevents metal to metal contact and provides damping properties. Examples of suitable material for upper portion  66  include, without limitation, Neoprene, Nitrile-butadiene and Isoprene. Although transmission elements  62  in the form of vulcanized feather keys are shown in the illustrated example embodiment, it is to be appreciated, however, that other suitable transmission means, e.g., without limitation, a separate feather key with a separate elastomeric element or elements (in place of single upper portion  66 ) could be employed without varying from the scope of the present invention. It is also to be appreciated that although shown as generally occupying all of the free space between base portion  64  and the walls of axial groove  32 , upper portion (or portions)  66  may occupy less than the remainder of the space in axial grooves  32 . In such embodiments, the remaining “empty” space left in the axial grooves (whether provided circumferentially or axially) is provided to allow for the softer material from which the upper portion or portions  66  are formed to deform or move slightly within each axial groove  32  as desired for the particular application. 
         [0033]    Each torque transmission element  62  has an elongate form, whose longitudinal axis extends parallel to the central axis M, with the base portion  64  portion engaging substantially without play in a corresponding receiver  60  in the tool receiver  42 . As shown in  FIG. 6 , the elastomeric upper portion  66  is offset in the direction of rotation, shown by the arrow R, which provides for torsional damping during machining operations. For the purpose of fastening the torque transmission elements  62  to the tool receiver  42 , a threaded aperture  68  is provided in each receiver  60  into which a setting screw  70 , realized in the form of an alien screw in the illustrated embodiment, may be screwed to selectively couple each of the torque transmission elements  62  into the corresponding receivers  60 . As shown in  FIGS. 1 and 6 , when the tool receiver  42  is installed in the holder portion  20  of the adaptor body  16 , each of the torque transmission elements  62  fit snugly in corresponding axial grooves  32 . As used herein, the term “snugly” shall be used to indicate the presence of at least a slight interference fit. 
         [0034]    In addition to the torsional damping of the tool receiver  42  provided by the elastomeric upper portions  66  of the torque transmission elements  62 , axial damping is also provided to the tool receiver  42  through the inclusion of a plurality of elastomeric elements provided axially between the tool receiver  42  and the adaptor body  16 . Referring to  FIG. 1 , a ring-like first damping member  80  is provided in mouth portion  24  of cavity  22  axially between the flange portion  48  of the tool receiver  42  and the edge (not numbered) of the central portion  26  of the cavity  22 . Another ring-like second damping member  82  is provided in the end portion  28  axially between the outer face  52  and the beveled portion  54  of the tool receiver  42  and the end face  30  of cavity  22 . The second damping member  82  is thickened along its circumference, such that, in combination with the beveled portion  54  of the tool receiver  42 , a wedge effect is achieved. Each of first and second damping members  80 , 82  may be formed from an elastomer, plastic, or other suitable material which is softer than the adjacent metal portions and thus prevent metal to metal contact and provide damping properties. Examples of suitable materials from which the first and second damping members  80 ,  82  may be formed include, without limitation, Neoprene, Nitrile-butadiene and Isoprene. It is to be appreciated that although generally depicted as flat, washer-like members in the illustrated embodiment, each of damping members  80 , 82  may be formed of members of other shapes (e.g., without limitation, o-ring shaped) and may be continuous or formed generally from a plurality of members, either abutting or spaced circumferentially, without varying from the scope of the present invention. 
         [0035]    As shown in  FIG. 1 , in order to couple the tool receiver  42  to the adaptor body  16 , an axial clamp screw  84  is provided which extends through a stepped aperture  86  which extends through end portion  50  of tool receiver  42  and threadingly engages a threaded aperture  88  formed in the adaptor body  16  concentric with the central axis M. In order to maintain the axial damping of the tool receiver as previously described, an elastomeric washer or o-ring  90  is provided between the head portion (not numbered) of the clamp screw  84  and the step of the stepped aperture  86 . It is to be appreciated that the threaded engagement between the clamp screw  84  and the adaptor body  16  allows for the axial preload provided to the first and second elastomeric members  80  and  82  to be adjusted by simply tightening or loosening the clamp screw  84 . In the example embodiment illustrated, such adjust can be accomplished through the use of an alien wrench (not shown) inserted onto cavity  22  of adaptor body  16  (when the rotary cutting tool  12  is not installed) such that the hexagonally shaped end of the wrench engages a hexagonally shaped cavity  92  provide in the head of the clamp screw  84 . 
         [0036]    The example tool adaptor  10  illustrated is adapted to be able to provide an internal flow of coolant to the rotary cutting tool  12  secured therein. In order to provide such feature, a coolant passage  94  is provided in the adaptor body  16  between the connection portion  18  and the holder portion  20 . Also, a central passage  96  is provided in the clamp screw  84  such that coolant provided from the machine tool (not shown) to the connection portion  18  is provided to the rotary cutting tool  12  secured in the tool receiver  42  via the coolant passage  94  and the central passage  96 . In order to prevent coolant leakage from between the cutting tool  12  and the tool receiver  42 , a sealing member  100  ( FIG. 1 , e.g., without limitation, a rubber bushing) having one or more suitably positioned openings  102  (depending on the arrangement of the coolant passage(s) in the tool body  12 ) is disposed between the rearmost portion (not numbered) of the tool body  12  and the end portion  50  of the tool receiver  42 . It is to be appreciated the coolant passage  94 , central passage  96 , and sealing member  100  are optional elements present in some example embodiments and thus such features may be omitted from other example embodiments of the present invention. 
         [0037]    When the rotary cutting tool  12  is to be driven, a torque is transmitted from the adaptor body  16  to the tool receiver  42  and from there to the tool  12 . Since the tool receiver  42  is elastically mounted inside the adaptor body  16 , vibrations that occur during machining performed by means of the tool  12  undergo extensive damping. On the one hand, this is effected in the axial direction, owing to the elastic elements  80 ,  82  and  90 . On the other hand, vibrations are damped in the circumferential direction, since the tool receiver  42  is coupled to the adaptor body  16  in an elastically resilient manner via the torque transmission elements  62 , the base portions  64  of which are guided in the receivers  60  of the tool receiver  42  and the upper damping portions  66  thereof are engaged in the axial grooves  32  formed in the holder portion  20  of the adaptor body  16 . Such arrangement provides for a high load capacity and, at the same time, a long service life because the damping elements are supported over a large area and are shielded from the machining operations by the adaptor body  16  itself. 
         [0038]    A particular advantage of the tool adapter  10  described herein consists in that the bias of the elastic elements  80 ,  82  and  90  can be set by simply turning a alien wrench. It is thereby possible to set the frequencies at which a particularly high damping is effected. A maximum of vibration damping can thus be achieved for any desired machining, such that there is a maximum reduction of the noise produced during machining. 
         [0039]    In view of the foregoing, it is to be appreciated that embodiments of the present invention provide tool adaptors that are particularly useful in applications where large and long tools are used to machine tough and hard materials. Demand for higher feed, speed and material removal rate (MRR) generally results in high cutting forces, vibrations due to chattering, and therefore bad surface quality and reduced tool life. Embodiments of the present invention compensate for such vibrations and thus the noises resulting from such vibrations, which are the main problems in machining processes. By eliminating such “non-required” properties, tool and insert life, surface quality and spindle bearing life may be improved. Embodiments of adaptors in accordance with the invention described herein are applicable to drilling, milling (end mills) and tapping operations. In drilling operations, axial vibrations may commonly result from torsional vibrations due to the helical shape of the flutes. Axial vibrations can adversely affect chip thickness and thus undesirably cause variations in torque. During machining processes, tool movements (both rotational and axial) are directly transferred in embodiments of the present invention through the tool receiver  42  to the elastomeric elements which are disposed circumferentially and axially between the tool receiver  42  and the adaptor body  16 . The elastomeric elements provide required damping by absorbing and dissipating energy. Such damping occurs both radially and axially throughout the machining process at a constant rate directly proportional to the cutting forces. Calming down any tool directly results in chatter free machining and therefore good surface quality and tool life. Also, due to the reduction or elimination of vibrations, noises produced during machining are reduced which provides for a more operator friendly work environment. 
         [0040]    While a specific embodiment of the invention has been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to the details provided herein could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the claims appended and any and all equivalents thereof.