Abstract:
A self-aligning tapping tool comprises an elongate handle having a longitudinal counterbore through a first end. A tap is received in the counterbore. A collar is operatively secured to the tap. The collar is slightly smaller than the counterbore to enable slidable movement and to prevent rotation of the tap relative to the handle. A retainer is secured to the handled at the first end to retain and the collar in the counterbore and has a center opening receiving the tap. A biasing spring in the counterbore biases the tap and the collar outwardly to extend the tap when the handle is turned to thread a hole in a work piece.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to repairing a threaded opening, such as with an oil pan and, more particularly, to a self-aligning tapping tool.  
       BACKGROUND OF THE INVENTION  
       [0002]     In the automotive service industry an oil change is one of the more common services performed. This service comprises removing a drain plug from an oil pan. Frequently the drain plug hole becomes stripped out while removing the plug. The known repairs for a stripped drain plug holes are problematic, at best. One current repair is to insert an oversized plug into the drain plug hole. However, subsequent removal of the oversized plug can completely destroy the hole. A second alternative is to remove the oil pan for repair or replacement. Both are costly due to labor and/or parts requirements. The oil pan can be repaired by drilling and tapping the hole to be of a larger size. Conventionally, a T-bar handle is used in connection with a threaded tap which is positioned at the entrance of the hole. The T-bar handle is turned to rotate the tap to thread the hole. However, the extended length of the T-bar handle will not allow precise centering and alignment because the tap will enter at some angle when the tapping process begins.  
         [0003]     The present invention is directed to solving one or more of the problems discussed above in a novel and simple manner.  
       SUMMARY OF THE INVENTION  
       [0004]     In accordance with the invention, there is provided a self-aligning tapping tool.  
         [0005]     Broadly, the tapping tool comprises an elongate handle having a longitudinal counterbore through a first end. A tap is received in the counterbore. A collar is operatively secured to the tap. The collar is slightly smaller than the counterbore to enable slidable movement and to prevent rotation of the tap relative to the handle. A retainer is secured to the handled at the first end to retain and the collar in the counterbore and has a center opening receiving the tap. A biasing means in the counterbore biases the tap and the collar outwardly to extend the tap when the handle is turned to thread a hole in a workpiece.  
         [0006]     It is a feature of the invention that the handle further comprises a slot at a second end for receiving a drive tool.  
         [0007]     It is another feature of the invention that the collar has a flatted outer side engaging a counterbore flatted side. The collar may comprise a square collar and the counterbore may have a square cross section.  
         [0008]     It is another feature of the invention that the collar is secured to the tap with screws that lock in flutes of the tap.  
         [0009]     It is still another feature of the invention that the retainer comprises an annular retainer having a plurality of radial through openings receiving guide screws extending into flutes of the tap.  
         [0010]     It is yet another feature of the invention that the biasing means comprises a spring acting on the collar. A second spring acts on an inner end of the tap. The counterbore may comprise a shoulder defining an inner seat for the first spring.  
         [0011]     There is disclosed in accordance with another aspect of the invention a self-aligning handheld tool comprising an elongate cylindrical handle having a longitudinal, rectangular counterbore through a first end and a slot at a second end for receiving a drive tool. A tap is received in the counterbore. A rectangular collar is operatively secured to the tap. The collar is slightly smaller than the counterbore to enable slidable movement and to prevent rotation of the tap relative to the handle. An annular retainer is secured to the handle at the first end to retain the collar in the counterbore and has a central opening receiving the tap. Biasing means in the counterbore bias the tap and the collar outwardly to extend the tap when the handle is turned to thread a hole in a workpiece.  
         [0012]     Further features and advantages of the invention will be readily apparent from the specification and from the drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a side perspective view of a self-aligning handheld tapping tool in accordance with the invention with a tap in an extended position;  
         [0014]      FIG. 2  is a perspective view, similar to  FIG. 1 , with the tap in a retracted position;  
         [0015]      FIG. 3  is a top perspective view of the tool of  FIG. 1  illustrating a drive slot;  
         [0016]      FIG. 4  is a bottom plan view of a handle of the tool of  FIG. 1 ;  
         [0017]      FIG. 5  is a sectional view taken along the line  5 - 5  of  FIG. 4 ;  
         [0018]      FIG. 6  is a top plan view of the handle of  FIG. 4 ;  
         [0019]      FIG. 7  is an exploded view of a tap and collar of the tool of  FIG. 1 ;  
         [0020]      FIG. 8  is a side elevation view illustrating the assembled tap and collar of  FIG. 7 ;  
         [0021]      FIG. 9  is an elevation view of a positioning spring of the tool of  FIG. 1 ;  
         [0022]      FIG. 10  is a side elevation view of a tap spring of the tool of  FIG. 1 ;  
         [0023]      FIG. 11  is a plan view of a retainer of the tool of  FIG. 1 ;  
         [0024]      FIG. 12  is a side elevation view of the retainer of  FIG. 11 ;  
         [0025]      FIG. 13  is a partial sectional view of the tool of  FIG. 1  with the tap in an extended position;  
         [0026]      FIG. 14  is a view similar to that of  FIG. 13  with the tap in a retracted position; and  
         [0027]      FIGS. 15A-15D  illustrate use and operation of the tool of  FIG. 1  for drilling and tapping a hole in a work piece. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0028]     Referring initially to  FIG. 1 , a self-aligning handheld tapping tool  20  according to the invention is illustrated. The tool  20  is adapted for repairing stripped oil pan drain plug holes in a variety of vehicles while the oil pan remains on the vehicle. The tool  20  achieves and maintains centering and alignment while tapping a drilled hole either in a flat or rounded surface. The process requires only one hand for the complete operation.  
         [0029]     While the tool is described with respect to tapping an oil pan drain plug hole, the tool  20  could be used for tapping any type hole, as will be readily apparent.  
         [0030]     The tool  20  comprises an elongate handle  22  receiving a slidable tap  24  held in place by a retainer  26 .  FIG. 1  illustrates the tap  24  in an extended position.  FIG. 2  illustrates the tap  24  in a retracted position. As described more particularly below, when the tool  20  is placed against a flat surface having a hole to be tapped, the tap  24  is retracted, as shown in  FIG. 2 . The handle  22  is rotated to turn the tap  24  to tap the hole with the tap  24  gradually extending, as described below.  
         [0031]     Referring to  FIGS. 4-6 , the handle  22  comprises an elongate cylindrical body  30  having a first end  32  and an opposite second end  34 . The body  30  has a knurled outer surface  36 . A square-shaped slot  38  is milled at the second end  34  for receiving a ratchet tool. A longitudinal counterbore  40  is provided through the first end  32  and having an inner end wall  41 . The counterbore  40  comprises a first, circular counterbore  42 . A second, square-shaped counterbore  44  is milled or otherwise formed coaxial with the first counterbore  42  and is larger in size to define a shoulder  46 .  
         [0032]     In the illustrated embodiment of the invention, the handle has a length of about 4.5 inches and a diameter of about 1.25 inches. The handle  22  may be formed of aluminum. The first counterbore  42  has a diameter of about ½ inch and a depth of about 3 inches. The second counterbore  44  is square-shaped in cross section having sides on the order of 0.630 inches and has a depth of just over 2 inches. Three screw openings  48  are provided in the first end  32 , see  FIG. 4 , for securing the retainer  26 , as described below.  
         [0033]     Referring to  FIGS. 7 and 8 , the tap  24  is of conventional construction and is operatively associated with a collar  50 . The tap  24  is generally cylindrical and includes a threaded portion  52  gradually narrowing to an outer end  54  and having an inner shank end  56 . Four flutes  58  are provided radially spaced about the threaded wall  52  for removal of metal shavings or the like. The flutes  58  extend slightly into the shank end  56 .  
         [0034]     The collar  50  comprises a square-shape body  60  having a circular axial through opening  62  for receiving the shank  56 . Four openings  64  are provided around the periphery of the block  60  for receiving #5 Allen head screws  66  that lock in the flutes  58 , as generally illustrated in  FIG. 8 . The collar  60  is machined to about 0.6250 inches square and fits into the 0.630 square counterbore  44 . Particularly, the tap  24  is slidably received in the counterbore  44 . The flatted surfaces of the collar  60 , provided by its square shape, relative to the flatted surface of the second counterbore  44 , also provided by its square shape, enables slidable movement and prevents rotation of the tap  24  relative to the handle  22 .  
         [0035]     Referring to  FIG. 9 , a positioning or collar spring  70  is illustrated. The spring A has a length A of about 2.75 inches, a wire thickness B of about 0.057 inches and diameter C of about 0.614 inches.  
         [0036]      FIG. 10  illustrates a tap spring  72  having a length A of about 1.625 inches, a wire size B of about 0.062 inches and a diameter C of about 0.49 inches.  
         [0037]     Referring to  FIGS. 11 and 12 , the retainer  26  comprises an aluminum annular element  74  having a circular central through opening  36  surrounded by radially extending threaded through openings  78  each for receiving an Allen head screw  80 . A pair of openings  82  are provided parallel with the central through openings  76  for receiving fasteners  84 , see  FIG. 2 , receivable in the openings  48 , see  FIG. 4 , for securing the retainer  26  to the handle  22 . The holes  78  are aligned with the tap flutes  58 . Particularly, an Allen screw  80  in each of the openings  78  extends into one of the flutes  58  to achieve complete alignment of the tap  24 . Particularly, the set screws  80  are turned to contact all four flutes  58  at the same position. Once these screws  80  are set and locked the tap  24  is fully aligned at either its fully extended length or its fully retracted position. The tap  24  is then aligned and moves freely throughout the tool handle  22  during the threading process.  
         [0038]     The assembled tool  20  is illustrated in greater detail in  FIGS. 13 and 14 .  FIG. 13  illustrates the tap  24  in the extended position.  FIG. 14  illustrates the tap  24  in the retracted position.  
         [0039]     As illustrated, the retainer  26  is secured to the handle  22  with the screws  84 , see  FIG. 2 , to retain the collar  50  in the counterbore  40 . The tap  24  extends through the central opening  76 . The collar spring  70  extends between the shoulder  46  and the collar  50 . The tap spring  72  extends between the counterbore end wall  41  and selectively engages the tap shank  56 . The springs  70  and  72  effectively bias the tap  24  outwardly. As is conventional, the tap  24  gradually extends during a tapping operation and in the illustrated embodiment of the invention extends with the aid of the springs  70  and  72  when the handle  22  is turned to thread a hole in a workpiece. Particularly, the two springs  70  and  72  comprise compression springs. The collar springs  70  exerts about 7.6 pounds per square inch. The tap spring  72  exerts about 9.8 pounds per square inch. As the tap  24  is pressed into the tool handle  22  for approximately one inch it has little resistance because the collar spring  70  acts only as a positioning spring. As the tap  24  compresses and is within ½ inch of its fully retracted spring, the tap spring  72  begins to compress. The tap spring  72  has more resistance as it is engaged. The tap spring  72  maintains a consistent force against the tap  24  forcing its end into a drilled hole, in use. Once the force of the tap spring  72  is felt, the tool handle  22  is completely pushed down causing the tap  24  to retract fully into the tool handle  22 , as illustrated in  FIG. 14 . At that time the tool handle body with its flat retaining guide  26  matches a flat surface of a workpiece. As is apparent, if the workpiece is round, it still retains a flat surface on its radius.  
         [0040]     Use of the tool  22  for tapping a hole is illustrated in  FIGS. 15A-15D . Particularly,  FIG. 15A  illustrates a workpiece W having a drilled hole H. For example, the workpiece W could be an oil pan. If a drain plug hole is stripped, then a conventional drill bit can be used to drill a clean hole, such as the hole H shown in  FIG. 15A . The tool  20  is then positioned, as described above, against the workpiece W with the tap  24  retracted, as shown in  FIG. 15B . In this position, owing to the taper of the tap  24 , the distal end of the tap  24  will extend slightly into the hole H. The handle  22  is then rotated, as illustrated by the arrow in  FIG. 15C , such as with a ratchet tool. As the tap  24  begins to form a thread in the hole, and aided by the force of the springs  70  and  72 , the tap  24  extends as the handle  22  is turned until it reaches its fully extended position, shown in  FIG. 15C . The flat surface of the retainer  26  against the flat surface of the workpiece W provides centering and alignment of the tap  24 . Moreover, the square-shaped counterbore  44  in combination with the square-shaped collar  50  acts as a slide track for the tap  24  and allows it to travel in and out with ease while maintaining alignment. Likewise, the retainer guide set screws  80  extending into the tap flutes  58  further provide alignment throughout the tapping process.  
         [0041]     The dimensions given herein and above are intended to be exemplary. Advantageously, the tool  20  can be provided as part of a kit. The kit would comprise the handle  22  and springs  70  and  72 . Multiple size taps  24  and associated collars  50  could be provided each associated with a retainer  26 . The kit could also have multiple size drill bits and drain plugs or the like. In use, the mechanic using the kit can determine the size of the opening necessary and use the drill bit to clean out the opening and then select the appropriate size tap and drain plug to tap the hole and provide suitable repair. The use of the described tool  20  can shorten the repair time to about 5 minutes which can save as much as hundreds of dollars from conventional repairs.  
         [0042]     Thus, in accordance with the invention, there is provided a self-aligning handheld tapping tool for simply and readily tapping an opening, such as in a vehicle oil pan.