Abstract:
A tool clamping mechanism connects a first member to a second member. The first member has a cylindrical stem with a coupling tooth projecting from the stem. The second member has a clamping cavity formed by the union of a gripping bore and an access hole. The access hole has an access bore and a tooth access hole formed to accommodate the stem and the coupling tooth respectively. The stem diameter of the stem is larger than the gripping bore diameter of the gripping bore. The clamping cavity further has a coupling recess for accommodating the coupling tooth. The coupling recess has a drive surface for engaging a driven surface located on the coupling tooth to create a force which pushes the stem from the access bore into the gripping bore and helps prevent separation of the two members.

Description:
FIELD OF THE INVENTION 
     The present invention relates to tool clamping mechanisms for clamping one member to another. 
     BACKGROUND OF THE INVENTION 
     U.S. Pat. No. 6,394,465 discloses a tool clamping device including a clamping member having an insertion bore formed by the union of an access bore portion and a gripping bore portion. An insertion member having a cylindrical shank portion with a diameter smaller than the access bore portion diameter, is insertable into the access bore. The diameter of the shank portion is slightly larger than the diameter of the gripping bore portion. When the clamping mechanism is transferred to a clamped position, the insertion member is forcibly fitted into the gripping bore portion by an external force exerted on the shank portion by a bearing sleeve or a clamping screw. A firm clamping between the shank portion and the gripping bore portion is maintained by the external force. The external force guarantees that the shank portion remains pressed against the gripping bore portion during operation of the cutting tool. Without the external additional force, the clamping mechanism of &#39;465 cannot perform as such, since any external force applied on the gripped shank portion, in a direction transverse to a longitudinal direction of the shank portion, may pull the shank portion out of the gripping bore portion. 
     In the clamping method where the clamping screw is used to force the shank portion into the gripping bore portion, the wall into which the clamping screw is threaded, must have a minimum thickness, in order for the thread to work properly. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention there is provided a clamping mechanism between a first member and a second member. The first member comprising a front portion at a front end of the first member and a male portion extending rearwardly from the front portion. The male portion comprising a cylindrical stem having a stem diameter D 3 . The stem comprising a stem peripheral surface. The second member comprising: 
     a female portion at a front end of the second member, the female portion comprising a front face, and a clamping cavity opening out to the front face and formed by the union of an access hole and a gripping bore. The clamping cavity comprising an internal coupling recess comprising a drive surface; and 
     a rear portion extending rearwardly from the female portion. 
     The gripping bore having a circular cross section with a gripping bore diameter D 2  in an end view of the female portion, the gripping bore comprising a gripping surface having an arc angle greater than 180 degrees. The access hole comprising a tooth access hole and an access bore having a circular cross section with an access bore diameter D 1  in the end view of the second member, wherein D 1 &gt;D 3 &gt;D 2 . The tooth access hole being formed in the front face and extending rearwardly. The access bore and the gripping bore have respective longitudinal axes spaced apart at least along a portion thereof. 
     Wherein the male portion further comprises a coupling tooth projecting from the stem peripheral surface for being received in the tooth access hole and in the coupling recess, and the coupling tooth comprising a driven surface for engagement with the drive surface. 
     According to embodiments of the present invention, the driven surface of the coupling tooth rises away from the stem peripheral surface in a direction towards a stem rear surface. 
     According to embodiments of the present invention, the driven surface of the coupling tooth rises in a clockwise direction in an end view of the stem. 
     According to embodiments of the present invention, the access bore intersects with the gripping bore at two intersection lines. 
     According to embodiments of the present invention, the gripping surface extends longitudinally the same length as the gripping bore. 
     According to embodiments of the present invention, α equals 181 degrees. 
     According to embodiments of the present invention, in an unclamped position, the coupling tooth is located in the tooth access hole. 
     According to embodiments of the present invention, in a clamped position, the driven surface of the coupling tooth is in engagement with the drive surface of the coupling recess. 
     According to embodiments of the present invention, in a clamped position, the gripping surface of the gripping bore is in engagement with the stem peripheral surface along an area with an arc angle of at least 180 degrees. 
     According to embodiments of the present invention, in a clamped position, a rear face of the front portion is in engagement with the front face of the female portion. 
     According to embodiments of the present invention, the longitudinal axes of the access bore and the gripping bore are parallel. 
     According to embodiments of the present invention, the longitudinal axes of the access bore and the gripping bore are spaced apart a distance L. 
     According to embodiments of the present invention, the gripping bore tapers towards the front face. 
     According to embodiments of the present invention, the drive surface of the coupling recess has a frusto-conical shape. 
     According to embodiments of the present invention, the gripping bore has a cylindrical shape. 
     According to embodiments of the present invention, the access bore has a cylindrical shape. 
     In accordance with the present invention, there is provided a method for assembling the clamping mechanism, comprising the steps of: 
     a) inserting the stem into the access hole until the coupling tooth is aligned with the coupling recess in an axial direction; and 
     b) turning the first member clockwise with respect to the second member, in an end view of the front portion, until the stem is fully transferred from the access hole to the gripping bore and the stem peripheral surface is in full abutment with the gripping surface with the driven surface of the coupling tooth in full engagement with the drive surface of the coupling recess. 
     The first member may be a cutting head. The second member may be a tool shank. Together, cutting head and the tool shank may form a cutting tool. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a better understanding of the present invention and to show how the same may be carried out in practice, reference will now be made to the accompanying drawings, in which: 
         FIG. 1  is an isometric exploded view of a clamping mechanism with first and second members according to embodiments of the present invention; 
         FIG. 2  is an isometric view of the first member; 
         FIG. 3  is an end view of the first member; 
         FIG. 4  is a generally isometric view of the second member; 
         FIG. 5  is an end view of the second member; 
         FIG. 6  is a side view of the assembled clamping mechanism in an unclamped position; 
         FIG. 7  is a cross-section taken along the line VII-VII of  FIG. 6 ; 
         FIG. 8  is a side view of the assembled clamping mechanism in a clamped position; 
         FIG. 9  is a cross-section taken along the line IX-IX of  FIG. 8 ; 
         FIG. 10  is a side view of an embodiment of the second member; and 
         FIG. 11  is an end view of an embodiment of the second member. 
     
    
    
     It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity, or several physical components may be included in one functional block or element. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. 
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following description, various aspects of the present invention will be described. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the present invention. However, it will also be apparent to one skilled in the art that the present invention may be practiced without the specific details presented herein. Furthermore, well-known features may be omitted or simplified in order not to obscure the present invention. 
     Reference is made to  FIGS. 1 to 5 , showing a tool clamping mechanism  10  between a first member  12  and a second member  14  in accordance with embodiments of the present invention. The first member  12  may, for example, be a cutting head  12  having a direction of rotation and provided with one or more cutting inserts, blades, etc. (not shown) at a front end  27  thereof. Meanwhile, the second member  16  may, for example, be a tool shank  16  having a direction of rotation and configured to rotationally drive the cutting head  12  in said rotational direction, the cutting head  12  and the shank  14  together constituting a cutting tool. 
     The first member  12  has a front portion  16  located at a front end and a male portion  18  which extends rearwardly from the front portion  16 . The male portion  18  includes a cylindrical stem  20  with a stem diameter D 3  and a longitudinal stem axis A 3 . The stem  20  has a stem peripheral surface  22  which extends between a rear face  24  of the front portion  16  and a stem rear surface  26 . According to some embodiments, the rear face  24  and the stem rear surface  26  face rearwards. According to some embodiments, the rear face  24  and the stem rear surface  26  are oriented perpendicularly to the stem axis A 3 . 
     The male portion  18  further includes a coupling tooth  28  projecting from the stem peripheral surface  22 . The coupling tooth  28  includes opposite tooth front and rear surfaces ( 30 ,  32 ), opposite tooth side surfaces  34 , a tooth peripheral surface  36  and a driven surface  38 . According to some embodiments, the driven surface  38  extends between the tooth front surface  30 , the tooth peripheral surface  36  and the tooth side surfaces  34 . According to some embodiments, the driven surface  38  rises away from the stem peripheral surface  22 , in a direction towards the stem rear surface  26  (see  FIG. 2 ). According to some embodiments, the driven surface  38  rises in a clockwise direction in an end view of the stem  20  (see  FIG. 1 ) defining lower and higher tooth portions ( 40 ,  42 ). Thus, in some embodiments, the driven surface  38  ramps radially outwardly in a rearward axial direction along the stem axis A 3  and ramps radially outwardly in a circumferential direction of rotation of the first member  12 . 
     Attention is drawn to  FIGS. 4 and 5 , showing the second member  14 . The second member  14  includes a female portion  44  at a front end and a rear portion  46  extending rearwardly from the female portion  44 . The female portion  44  includes a forwardly facing front face  48  at a front end and a longitudinal clamping cavity  50  extending rearwardly and opening out to the front face  48 . The clamping cavity  50  is formed by the union of an access hole  52  and a gripping bore  54  and includes a clamping cavity rear surface  56 . The gripping bore  54  has a longitudinal gripping bore axis A 2  and a circular cross section with a gripping bore diameter D 2 , taken perpendicularly to the gripping bore axis A 2 . The access hole  52  intersects with the gripping bore  54  at two intersection lines  58 , defining a gripping surface  60  having an arc angle α greater than 180 degrees throughout its length. The angle α is preferably chosen to be 181 degrees. 
     According to some embodiments, the gripping surface  60  is semi-cylindrical. According to some embodiments, the gripping surface  60  extends longitudinally the same length as the gripping bore  54 . The access hole  52  includes an access bore  62  with an access bore axis A 1 , the access bore  62  has a circular cross section with an access bore diameter D 1 , taken perpendicularly to the access bore axis A 1 . At any cross section taken perpendicularly to any of the axes A 1 , A 2  and A 3 , the access bore diameter D 1  of the access bore  62  is greater than the stem diameter D 3  of the stem  20 , which is greater than the gripping bore diameter D 2  of the gripping bore  54  (D 1 &gt;D 3 &gt;D 2 ). 
     The access hole  52  further includes a tooth access hole  64  formed in the front face  48  for receiving the coupling tooth  28  of the first member  12 . According to some embodiments, the tooth access hole  64  extends between the front face  48  and the clamping cavity rear surface  56 . The access bore axis A 1  and the gripping bore axis A 2  are parallel and spaced apart a distance L (see  FIG. 7 ). 
     The clamping cavity  50  further includes a circumferentially extending internal coupling recess  66  located axially between the clamping cavity rear surface  56  and the front face  48 . The coupling recess  66  has a circular cross section in an end view of the female portion  44 . The coupling recess  66  is coaxial with the gripping bore axis A 2  and includes a drive surface  68  formed to engage the driven surface  38  of the coupling tooth  28 . According to some embodiments, the drive surface  68  has a right frusto-conical shape, designed to receive the shape of and abut the driven surface  38  of the coupling tooth  28 . When the clamping mechanism  10  is assembled, the drive surface  68  is designed with such dimensions as to allow access to the lower tooth portion  40  of the driven surface  38 , and prevent access to the higher tooth portion  42  of the driven surface  38 . 
     Reference is made to  FIGS. 6 and 7 , showing the clamping mechanism  10 , and the first member  12 , in an unclamped position. In this position, the male portion  18  is located in the clamping cavity  50 , the stem  20  is located in the access bore  62  and the coupling tooth  28  is located in the tooth access hole  64 . The longitudinal axis A 3  of the stem  20  is generally co-aligned with the longitudinal axis A 1  of the access bore  62 , the first member  12  is slidingly free to move in the access hole  52  in the axial direction, with respect to the second member  14  and the gripping surface  60  of the gripping bore  54  does not abut the stem peripheral surface  22 . The male portion  18  of the first member  12  is inserted into the clamping cavity  50  until the coupling tooth  28  is aligned with the coupling recess  66  in an axial direction. 
     Reference is made to  FIGS. 8 and 9 , showing the clamping mechanism  10 , and the first member  12 , in a clamped position. The stem  20  is located in the gripping bore  54  and the gripping surface  60  of the gripping bore  54  abuts the stem peripheral surface  22 . The longitudinal axis A 3  of the stem  20  coincides with the gripping bore axis A 2  (see  FIG. 9 ). In this position, the coupling tooth  28  is located in the coupling recess  66  and the drive surface  68  of the coupling recess  66  abuts the driven surface  38  of the coupling tooth  28  such that the drive surface  68  is in driving engagement with the driven surface  38 . Furthermore, according to some embodiments, the front rear face  24  may abut the front face  48 . 
     Transferring the clamping mechanism  10 , or the first member  12 , from the unclamped position to the clamped position is done by turning the first member  12  with respect to the second member  14  clockwise, in an end view of the front portion  16  of the first member  12 . Turning is only possible in a clockwise direction since, as mentioned hereinabove, the higher tooth portion  42  of the driven surface  38  cannot pass though the coupling recess  66 . As the turning progresses, the coupling tooth  28  is transferred from the tooth access hole  64  to the coupling recess  66 , until at a certain point, the driven surface  38  starts to abut the drive surface  68 . Since the stem diameter D 3  of the stem  20  is greater than the gripping bore diameter D 2  of the gripping bore  54  (D 3 &gt;D 2 ), the stem  20  has to be forcibly pressed into the gripping bore  54 . As disclosed hereinabove, the driven surface  38  rises in a clockwise direction in an end view of the stem  20 . Therefore, when the driven surface  38  starts to abut the coupling recess  66 , a normal force N is generated in a general direction towards the gripping surface  60  (See  FIG. 9 ). The force N, which builds up as the first member  12  is further turned, pushes the stem  20  through the two intersection lines  58  and into the gripping bore  54 , while the gripping bore  54  is slightly expanded. It should be explained that according to some embodiments, the gripping bore  54  is designed with such tolerances as to allow such an expansion of the gripping bore  54 . 
     According to some embodiments, the clamping cavity  50  is formed by the union of an access hole  52  and a gripping bore  254  that tapers towards the front face  48  facilitating the expansion of the gripping bore  254  (See  FIG. 10 ) near the clamping cavity rear surface  56 . 
     According to some embodiments, in a cross section taken in an end view of the female portion, the gripping surface  60  is continuous (see  FIGS. 1 ,  5 - 9 ) and according to some embodiments, the gripping surface  160  is non-continuous and includes longitudinal depressions  161  (see  FIG. 11 ). 
     Furthermore, in those embodiments in which the drive surface  68  has a right frusto-conical shape, the force N also has a component directed rearwardly, in a direction away from the front face  48 . This enables the firm abutment between the front face  48  and the rear face  24 , ensuring axial locking between the first member  12  and the second member  14 . According to some embodiments, passage into and out of the gripping bore  54  may be evidenced by an audible click as the stem  20  passes past the intersection lines  58  between the access and gripping bores ( 62 ,  54 ). 
     While the present invention has been described with reference to one or more specific embodiments, the description is intended to be illustrative as a whole and is not to be construed as limiting the invention to the embodiments shown. It is appreciated that various modifications may occur to those skilled in the art that, while not specifically shown herein, are nevertheless within the scope of the invention.