Abstract:
An anti-slip type electric drill chuck mainly includes a body which is obliquely provided with three pawls for clamping a drill head. The outer surface of one end of the three pawls is provided with a threaded surface for engaging a tapered threaded hole in a bearing nut, which has an outer end with teeth, an end portion provided with a ball ring. A check nut protective sleeve encloses the ball ring and bearing nut, and has elastic pointed portions engage the teeth. A drive annular block engages the inner wall of the bearing nut. A front housing sleeve engages the drive annular block and surrounds the aforesaid components. The front housing sleeve is rotated by hand to advance or retract the pawls to thereby loosen or tighten drill head. When the pawls clamp the drill head, the check nut protective sleeve stabilizes the bearing nut to prevent slippage thereof.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    (a) Field of the Invention  
           [0002]    The invention relates to a chuck of an electric drilling tool, more particular to an anti-slip type electric drill chuck.  
           [0003]    (b) Description of the Prior Art  
           [0004]    A conventional electric drill chuck structure generally has a body connected to a rotary shaft of a motor. The motor is externally provided with an adjusting housing for local rotation. The body has a plurality of slanting pawls annularly disposed thereon. The user can adjust the adjusting housing with his/her hand to control the advancement or retraction of the pawls in an oblique direction to thereby clamp or release a drill head.  
           [0005]    Such a mechanism of using the hand to manipulate of the adjusting housing so as to control advancement or retraction of the pawls may, due to factors such as vibration of the drill head, torque, resistance on drill surface, etc. during the drilling operation, cause the engagement between the pawls and the drill head to become loosened so that it is necessary to stop the machine and lock the drill head again. Otherwise, the drill head will deviate and is likely to be damaged. The drill surface is also likely to be damaged.  
         SUMMARY OF THE INVENTION  
         [0006]    The primary object of the invention is to provide an anti-slip type electric drill chuck, in which a front housing sleeve of a chuck unit is rotated by hand to control the chuck unit to clamp or release a tool such as drill head. When the chuck unit clamps the tool during operation, the chuck can prevent slippage of the drill head due to counteractions of vibration, torque, resistance, etc., resulting from the drilling operation.  
           [0007]    In order to achieve the abovementioned object, an anti-slip type electric drill chuck of the present invention mainly includes a body which is obliquely provided with three pawls for clamping a drill head. The outer surface of one end of the three pawls is provided with a threaded surface for engaging a tapered threaded hole in a bearing nut, which has an outer end with teeth, an end portion provided with a ball ring. A check nut protective sleeve encloses the ball ring and bearing nut, and has elastic pointed portions engage the teeth. A drive annular block engages the inner wall of the bearing nut. A front housing sleeve engages the drive annular block and surrounds the aforesaid components. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    The foregoing and other features and advantages of the present invention will be more clearly understood from the following detailed description and the accompanying drawings, in which,  
         [0009]    [0009]FIG. 1 is an exploded perspective view of the present invention;  
         [0010]    [0010]FIG. 2 is an elevation view of the check nut protective sleeve of the invention and the relevant construction in assembly;  
         [0011]    [0011]FIG. 3 is a sectional view of the check nut protective sleeve of the invention and the relevant construction in assembly;  
         [0012]    [0012]FIG. 4 is a sectional view of the present invention in assembly;  
         [0013]    [0013]FIG. 5A is a sectional view taken along line  5 - 5  of FIG. 4, showing the operation of the invention in the arrow indicated;  
         [0014]    [0014]FIG. 5B is a sectional view taken along line  5 - 5  of FIG. 4, showing the operation of the invention in the arrow indicated;  
         [0015]    [0015]FIG. 5C is a sectional view taken along line  5 - 5  of FIG. 4, showing the operation of the invention in the arrow indicated;  
         [0016]    [0016]FIG. 6 is a cross-sectional view in the same direction of FIG. 5C, showing the second embodiment of the invention;  
         [0017]    [0017]FIG. 7 is a sectional view of the third embodiment of the invention;  
         [0018]    [0018]FIG. 8 is a sectional view of the fourth embodiment of the invention;  
         [0019]    [0019]FIG. 9 is a sectional view of the fifth embodiment of the invention; and  
         [0020]    [0020]FIG. 10 is a perspective view of the drive annular block of the fifth embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]    Referring to FIGS. 1, 2,  3  and  4 , the chuck according to the present invention includes a body  20 , a bearing nut  40 , a check nut protective sleeve  50 , a drive annular block  60 , a front housing sleeve  70 , a tool sleeve  80 , and a rear housing sleeve  90 .  
         [0022]    The body  20  has one end connected to a transmission shaft of an electric drill motor. The body  20  is provided with a first ring  21  and a second ring  22  projecting from the outer periphery of a shaft securing end thereof. The center of the body  20  is provided with a shaft hole  23 . The periphery of the seat body is formed with three equidistantly spaced guide grooves  24 . One end of the three guide grooves  24  passes through the second ring  22 . The other end extends into the shaft hole  23 . Three pawls  30  respectively extend into the guide grooves  24  from exposed holes formed by the three guide grooves  24  in the second ring  22 . The pawl  30  has a threaded surface  31  exposed from the body  20 , and has an inner end portion extending into the shaft hole  23  to form a clamping end  32  for clamping a tool such as a drill head, reamer, screwdriver, tapping cutter, etc.  
         [0023]    The bearing nut  40  is sleeved on the body  20 , and is centrally provided with a tapered threaded hole  41  for engaging the threaded surface  31  of the pawl  30 . The outer periphery of the bearing nut  40  has a surface with different diameters, with a juncture forming an oblique wedged surface  46 . The surface with the smaller diameter is provided with teeth  42 . The end portion of the bearing nut  40  that corresponds to the second ring  22  of the body  20  is fitted with a ball ring  43  and a heat-treated washer  45 .  
         [0024]    The check nut protective sleeve  50  includes a tooth fitting ring  502  and a packing ring  501 . The tooth fitting ring  502  is in the form of an annular sleeve fitted on the bearing nut  40  and has a ring end provided with a plurality of bent openings  52  corresponding to the teeth  42  of the bearing nut  40  such that one side of the respective opening  52  forms an elastic piece  53 . An open end portion of the elastic piece  53  is recessed toward the center of the tooth fitting ring  502  so as to form a pointed portion  54 . The pointed portion  54  can engage the teeth  42 . The packing ring  501  is disposed at the ball ring  43  and washer  45  of the bearing nut  40  to urge against the end of the tooth fitting ring  502 . Corresponding to the wedged surface  46  of the bearing nut  40 , the tooth fitting ring  502  is also formed with an oblique wedged surface  55 . The two wedged surfaces  46 ,  55  abut against each other to be thereby positioned so as to further prevent loosening or slippage of the tooth fitting ring  502 . The check nut protective sleeve  50  encloses the bearing nut  40  and ball ring  43  as an assembly disposed on the body  20  such that the exterior of the packing ring  501  surrounds the second ring  22 .  
         [0025]    The drive annular block  60  has one end fitted in the end edge of the bearing nut  40 . The outer edge of the drive annular block  60  is provided with a plurality of protrusions  61 . The inner periphery of the end portion of the bearing nut  40  is provided with a plurality of recesses  44  for retaining the protrusions  61 . The other end portion of the drive annular block  60  is exposed from the body  20 . The front housing sleeve  70  is a hollow sleeve with two open ends, and is fitted at the end portion of the body  20  to enclose the drive annular block  60 , check nut protective sleeve  50  and bearing nut  40 . The inner periphery of the front housing sleeve  70  is annularly provided with a plurality of recesses  72  for retaining protrusions  61  of the drive annular block  60  such that when the front housing sleeve  70  is turned by hand, the bearing nut  40  can be brought to rotate therewith.  
         [0026]    The tool sleeve  80  is tightly fitted at the end portion of the body  20  to limit the front housing sleeve  70 . The center thereof is provided with an extension hole  81  for extension of a tool, such as drill head  100 , therethrough. The outer edge thereof is provided with a polygonal hole  82  into which a workpiece, such as a sleeve, can be fitted directly. The inner edge of the hole is provided with a semi-curved groove  821  such that a securing ball of the sleeve can be insertably retained therein to thereby position the sleeve. The inner edge of the tool sleeve  80  is annularly provided with an abutting protrusion  83  for tightly abutting against an abutting groove  25  at the end portion of the body  20  so that the tool sleeve  80  will not become disengaged.  
         [0027]    The rear housing sleeve  90  is a sleeve member with a substantially U-shaped cross-section, and is fitted on the first ring  21  of the shaft securing end of body  20 . The rear housing sleeve  90  is internally provided with a projecting retaining portion  91 . The first ring  21  is provided with a groove  211  for retaining the retaining portion  91 .  
         [0028]    The operation of the present invention will be described hereinafter with reference to FIGS. 2 and 5A.  
         [0029]    If it is desired to lock the drill head  100  tight, the end portion of the drill head  100  is inserted into the extension hole  81  in the tool sleeve  80  and further into the shaft hole  23  in the body  20 . The front housing sleeve  70  is rotated by hand to drive the drive annular block  60 , bearing nut  40  and check nut protective sleeve  50  to rotate. At the same time, by means of the tapered threaded hole  41  in bearing nut  40 , the pawls  30  are caused to displace in the direction of the drill head  100 .  
         [0030]    When the clamping ends  32  of the pawls  30  engage the drill head  100 , the ball ring  43  and washer  45  at the end portion of bearing nut  40  will be tightly pressing against the packing ring  501  of check nut protective sleeve  50 . At this time, the pressed check nut protective sleeve  50  will not be able to rotate with bearing nut  40 . If the operation turns the front housing sleeve  70  very slightly, the teeth  42  on bearing nut  40  will push away the pointed portion  54  of the elastic piece  53  of check nut protective sleeve  50  (as shown in FIG. 5B), and a clicking sound of engagement between teeth will be heard. The user can then judge that the front housing sleeve  70  and bearing nut  40  have been rotated to a critical limit and can therefore stop turning the front housing sleeve  70 . The pointed portion  54  of check nut protective sleeve  50  is still retained in teeth  42  of bearing nut  40  (as shown in FIG. 5C).  
         [0031]    It is noted that when the drill head  100  is performing a drilling operation, vibration, torque, resistance, etc., will occur. However, since the pointed portion  54  of check nut protective sleeve  50  of the present invention engages the teeth  42  of bearing nut  40 , and since the ball ring  43  causes the packing ring  501  of check nut protective sleeve  50  to press tightly against the second ring  22  of body  20  so that when check nut protective sleeve  50  rotates with the body  20 , there is a limiting relationship with respect to the bearing nut  40  to keep the tapered threaded hole  41  of bearing nut  40  engaging the pawls  30  firmly, disengagement of drill head due to vibration, torque or resistance will not occur, and the drill head  100  can perform the drilling operation stably.  
         [0032]    When it is desired to remove the drill head  100 , the front housing sleeve  70  is rotated in a reverse direction. After turning the same very slightly, since the check nut protective sleeve  50  is still pressed by the ball ring  43  and washer  45 , there is still the clicking sound due to friction between the teeth when the bearing nut  40  is turned. But when the bearing nut  40  starts driving the pawls  30  to retract, the ball ring  43  and washer  45  will release the pressure on the packing ring  501  of check nut protective sleeve  50  and return to the state wherein the two are loosely engaged. At this time, since the check nut protective sleeve  50  has the pointed portion  54  thereof engaging the teeth  42 , it can rotate with the bearing nut  40  until the pawls  30  are completely retracted from the drill head  100 .  
         [0033]    In the tool sleeve  80  shown in FIGS.  1  to  5 C, the polygonal hole  82  is adapted to receive workpieces, such as sleeves.  
         [0034]    As shown in FIGS. 5A to  5 C, in the first embodiment, the root bottom portion between adjacent teeth  42  of bearing nut  40  is in a pointed shape; therefore, the pointed portion  54  of tooth fitting ring  502  is also in a pointed shape. In the second embodiment shown in FIG. 6, the root bottom portion between adjacent teeth  42  of bearing nut  40  is curved; therefore, the pointed portion  54 ′ of tooth fitting ring  502  is also in a curved shape so as to be engageable therewith.  
         [0035]    Referring to FIG. 7, the third embodiment of this invention does not include a tool sleeve  80 , and a recess  26  is formed at the head end of body  20 . The front housing sleeve  70  is provided with a projecting block  73  for insertion into the recess  26  to thereby position the front housing sleeve  70  and the body  20 .  
         [0036]    Referring to FIG. 8, which shows the fourth embodiment of this invention, the head end of the body  20  is provided with a taper portion  27  that tapers toward the open end. The open end of the body  20  is provided with an inverted-angle stop portion  28 . The inner edge of the front housing sleeve  70  near the open end thereof is provided with a taper surface that matches and engages the taper portion  27 , with the stop portion  28  of the body  20  stopping the open end of the front housing sleeve  70  to thereby position the front housing sleeve  70  and the body  20 .  
         [0037]    Referring to FIGS. 9 and 10, which show the fifth embodiment of this invention, the protrusion  61  of the drive annular block  60  is provided with a retaining groove  62 . The groove  72  of the front housing sleeve  70  is provided with a retaining block  73  corresponding to the retaining groove  62  for engaging the retaining groove  62  so as to position the front housing sleeve  70  on the drive annular block  60  with no likelihood of slippage.