Abstract:
A turret hand drill ( 10 ) features a turret ( 22 ) mounted on the drill for swivel motion about a pivot axis ( 5 ) angularly spaced from the tool drive axis ( 3 ) of the drill between a pair of opposite index positions. The turret ( 22 ) includes a pair of chuck assemblies ( 26 A, 26 B) arranged symmetrically about and coplanar with the pivot axis ( 5 ) of the turret ( 22 ) for selective positioning in alignment with the drill tool drive axis ( 3 ), with the idle chuck assembly extending downward out of the way. A spring biased clutch mechanism ( 70 ) allows for disengagement of a chuck shaft ( 30 ) from a drive shaft ( 20 ) of the drill by pulling on the chuck ( 28 ) to switch between chuck assemblies ( 26 A, 26 B). A frusto-conical ramp ( 90  or  94 ) is engaged by a chuck half ( 72 ) of the clutch mechanism as the turret is swiveled to gradually retract the chuck half ( 72 ) against the spring bias so that the chuck half is automatically urged into operative engagement with a drive half ( 74 ) of the clutch mechanism upon alignment therewith.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is the U.S. national phase of International Application No. PCT/US00/09080 filed Apr. 5, 2000, and claims priority of U.S. Provisional Application Ser. No. 60/153,181 filed Sep. 10, 1999. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to powered hand tools, and more particularly to a hand-operated turret drill for quickly changing between a pair of rotary tools such as a drill bit and screwdriver. 
     DESCRIPTION OF THE RELATED ART 
     Most multi-operations that are done with a hand drill are done using two tools: for example, a masonry hand drill bit and a screwdriver. With conventional hand drills having a single chuck for holding a tool, one must continually change back and forth between the two tools while not dropping or losing the idle tool. 
     It is known in the art of motor-driven hand tools to provide a magazine carrying a plurality of different tools and means for selecting a desired tool by aligning the tool with a chuck axis, sliding or moving the tool into place, and tightening the chuck. If another tool occupies the chuck, the tool change operation necessarily includes the initial step of loosening the chuck and returning the prior tool to its location in the magazine. Although designs of this nature are useful for eliminating the problem of lost tools, they do not significantly decrease the time involved in changing between tools. See, for example, U.S. Pat. Nos. 1,022,711; 4,604,005; 4,928,381; 5,022,131; 5,065,498; and 5,893,685. 
     It is further known in the art to provide a hand drill with a turret having a plurality of chucks for holding different tools, whereby the turret is rotated about an axis offset in parallel relation to the drive axis of the drill to select a desired tool. However, in designs of this type, the individual tool-holding chucks of the turret, and the tool shanks themselves, are often of a specialized reduced design in order to keep the hand drill to a reasonably compact and useful size. Consequently, conventionally sized tool-gripping chucks, and conventionally sized tools held thereby, are not well accommodated by these designs. See, for example, GB 1,073,681 and U.S. Pat. No. 2,679,770. 
     A problem common to both the single-chuck “magazine” designs and the multiple-chuck “turret” designs mentioned above is that the idle tools extend beyond the profile of a conventional hand drill, thereby compromising the compactness and utility of such drills. 
     SUMMARY OF THE INVENTION 
     Therefore, it is an object of the present invention to provide a hand turret drill with the utility to quickly change back and forth between two different tools without having to adjust a chuck each time. 
     It is another object of the present invention to provide a hand turret drill that accommodates tools of conventional size and shank design. 
     It is yet another object of the present invention to provide a hand turret drill with a turret that normally resides entirely within an end view projected silhouette of a conventional hand drill. 
     In furtherance of these and other objects, a turret hand drill formed in accordance with a preferred embodiment of the present invention comprises a drill housing enclosing a drill frame and drive means, and a two-chuck turret mounted on the drill frame near a forward portion of the drill for swiveling motion about a pivot axis between a pair of releasably locked index positions wherein a selected chuck is drivably connected to the drive means by a clutch mechanism. The pivot axis of the turret extends downwardly and forwardly from the forward portion of the drill housing at an angle displaced from the rotational tool drive axis of the drill, and a pair of chuck assemblies are arranged symmetrically about the turret pivot axis such that the respective rotational axes of the two chucks are coplanar with the turret pivot axis. Accordingly, when one of the chucks is positioned with its rotational axis aligned with the drill tool drive axis, swiveling the turret one-hundred eighty degrees about the turret pivot axis will switch the positions of the chucks to bring the rotational axis of the other chuck into alignment with the drill tool drive axis. 
     Each chuck assembly includes a chuck, a chuck shaft with a chuck half of the clutch, chuck shaft bearings, a bearing housing, and a clutch retraction spring. In one embodiment, the bearing housing is mounted in a bore in the turret and is biased by the clutch retraction spring so that the bearing housing and chuck shaft are forced to engage the chuck half of the clutch with a drive half of the clutch. This also locks the turret in place. Pulling on the chuck disengages the chuck half of the clutch from the drive half of the clutch so that the turret can be rotated about the pivot axis. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The nature and mode of operation of the present invention will now be more fully described in the following detailed description of the preferred embodiments taken with the accompanying drawing figures, in which: 
     FIG. 1 is a partially sectioned side view showing a hand turret drill formed in accordance with a preferred embodiment of the present invention; 
     FIG. 2 is a front elevational view of the hand turret drill shown in FIG. 1; 
     FIG. 3 is an enlarged partially sectioned view showing a turret of the hand turret drill; 
     FIG. 4 is an enlarged sectional view showing a proposed supplemental locking device of the present invention; 
     FIG. 5 is an enlarged sectional viewing showing a retractable chuck assembly of the turret hand drill in a torque transmitting condition; 
     FIG. 6 is a view similar to that of FIG. 5, however showing the retractable chuck assembly of FIG. 5 in a retracted condition; 
     FIG. 7 is an enlarged sectional viewing showing an alternative retractable chuck assembly in a torque transmitting condition; 
     FIG. 8 is a view similar to that of FIG. 7, however showing the retractable chuck assembly of FIG. 7 in a retracted condition; 
     FIG. 9 is an enlarged sectional viewing showing another alternative retractable chuck assembly in a torque transmitting condition; 
     FIG. 10 is a view similar to that of FIG. 9, however showing the retractable chuck assembly of FIG. 9 in a retracted condition; 
     FIG. 11 is a top plan view of a thumb latch mechanism for the retractable chuck assembly shown in FIGS. 9 and 10; and 
     FIG. 12 is a view similar to that of FIG. 2, however showing an external lifting ramp for a drop-in clutch feature of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring initially to FIGS. 1 and 2, a hand turret drill formed in accordance with a preferred embodiment of the present invention is shown and designated generally by the reference numeral  10 . Drill  10  comprises a frame  11  enclosed by a housing  12 . Frame  11  supports an automatic drive means  14  energized by a rechargeable power source  16  detachably mounted on housing  12 . Drive means  14  can be in the form of an electric motor cooperating with a gear train (not shown) or directly arranged to rotate a drive shaft  20  about a tool drive axis  3  of the drill. Drill  10  is operable using a finger trigger control  18  extending through housing  12 . The structure of drill  10  described to this point is conventional in nature. 
     Referring also now to FIG. 3, drill  10  departs from the prior art by further comprising a turret  22  mounted near a forward portion of frame  11  by a central swivel bearing  24  for rotation about a pivot axis  5  that extends downwardly and forwardly from the forward portion of the drill frame and housing at an angle displaced from the rotational tool drive axis  3  of drill  10 . The angle between tool drive axis  3  and pivot axis  5  is preferably, but not necessarily, about forty-five degrees. Turret  22  includes a pair of chuck assemblies  26 A and  26 B arranged in angular symmetry about the turret pivot axis  5  such that the respective rotational axes of the two chuck assemblies are coplanar with the turret pivot axis. It will be understood from the turret configuration described above that when one of the chuck assemblies is positioned in axial alignment with drill tool axis  3 , the other chuck assembly can be moved into axial alignment with drill tool axis  3  by swiveling turret  22  one-hundred eighty degrees about pivot axis  5 . An optional detent  25  is arranged atop housing  12  for engagement by alignment members  27 A and  27 B provided adjacent respective chuck assemblies  26 A and  26 B to prevent “over swiveling” of turret  22  about pivot axis  5  during a change between chucks. It will be noted from FIG. 2 that when chuck assembly  26 A or chuck assembly  26 B is axially aligned with drill tool axis  3 , the outline of turret  22  and chuck assemblies  26 A, 26 B is contained entirely within the confines of the silhouette of drill  10  as viewed along drill tool axis  3 . 
     Each chuck assembly  26 A, 26 B includes a standard-sized chuck  28  at a distal end of a chuck shaft  30  for holding a drill bit, screwdriver, or other tool adapted for driven rotation by a hand drill. Turret  22  is shaped so it does not extend further forward than the back of chuck  28 . In order to permit chuck  28  to be selectively coupled to and uncoupled from drive shaft  20 , a retractable clutch mechanism  70  is provided that includes a chuck half  72  at a proximal end of chuck shaft  30  and a drive half  74  at a distal end of drive shaft  20 . The clutch halves  72  and  74  can be interlocking splines or other mating tooth and groove configuration that enables clutch mechanism  70  to transmit torque from drive shaft  20  to chuck shaft  30 , guide and restrain the clutch shaft in accurate alignment with the drive shaft, and lock the turret from unintended swiveling about pivot axis  5 . 
     Pursuant to one possible embodiment shown in FIGS. 5 and 6, the chuck shaft  30  is supported for rotation about its longitudinal axis by a pair of shaft bearings  32  and  34  situated within a bearing housing  36 , which is itself slidably supported within a bore  37  in turret  22 . The inner races of shaft bearings  32  and  34  are press fitted onto chuck shaft  30 , and the outer races of shaft bearings  32  and  34  are press fitted within bearing housing  36 , such that axially directed sliding motion between chuck shaft  30 , shaft bearings  32  and  34 , and bearing housing  36  is prevented and the parts move as a unit. A clutch retraction spring  38  is arranged co-axially about chuck shaft  30 . A distal end of clutch retraction spring  38  engages protrusions  40  extending radially through axially extending travel slots  42  in the sidewall of bearing housing  36 , and a proximal end of the spring engages an internal step  44  in the sidewall of the bearing housing, whereby the spring urges the bearing housing including chuck shaft  30  rearward toward drive shaft  20 . 
     FIGS. 7 and 8 show an alternative construction of chuck assemblies  26 A, 26 B wherein chuck shaft  30  is slidably received in a sleeve  46  which in turn is rotatably supported by shaft bearings  32  and  34  within bearing housing  36 , which is integrally formed as part of turret  22 . Clutch retraction spring  38  is arranged co-axially about chuck shaft  30  and sleeve  46  with the spring&#39;s distal end engaging bearing  32  and its proximal end engaging an annular spring seat  48 . Spring seat  48  is fixed relative to sleeve  46  and chuck shaft  30  by a travel pin  50  radially received through a hole  52  through the spring seat, opposite travel slots  54  through sleeve  46 , and a hole  56  through the chuck shaft. Chuck shaft  30  is provided with a radially enlarged distal portion that defines a shoulder  58  in engagement with a distal end of sleeve  46 . Likewise, another shoulder  60  is defined by a radial step in the outer wall of sleeve  46  and engages bearing  34 , which is chosen as a thrust bearing. A retaining ring  62  is provided within an internal annular groove near the proximal end of bearing housing  36  to keep bearing  34  within bearing housing  36 . In the construction of FIGS. 7 and 8, chuck shaft  30  is biased toward clutch engagement with drive shaft  20  by retraction spring  38 , however it is possible to pull chuck  28  to the left as seen in FIG. 8 against the urging of retraction spring  38  such that chuck shaft  30  slides in an axial direction relative to sleeve  46  while travel pin  50  travels within travel slots  54 , which are elongated in the axial direction. 
     FIGS. 9-11 show another alternative arrangement for supporting and biasing the chuck shaft. The arrangement is similar to that described in connection with FIGS. 5 and 6, however protrusions  40  and internal step  44  are reversed such that chuck shaft  30  is urged outward away from drive shaft  20 . To maintain clutch engagement between chuck half  72  and drive half  74 , a retainer latch  75  is mounted to upstanding guard walls  73  on turret  22  by a pivot pin  76  just above associated bearing housing  36 . Retainer latch  75  includes a downwardly depending retainer tab  77  at a distal end thereof for retaining bearing housing  36 , shaft bearings  32  and  34 , and chuck shaft  30  pushed inward against the bias of retraction spring. A depressible spring  78  located opposite retainer tab  77  normally urges retainer latch  75  pivotally about pivot pin  76  toward a locking position. Consequently, as depicted in FIG. 10, thumb pressure exerted on retainer latch  75  to depress spring  78  serves to remove retainer tab  77  and allow clutch disengagement of chuck half  72  from drive half  74  under the outwardly directed biasing force of retraction spring  38 . 
     In the biasing configurations disclosed above, a mechanical spring is disclosed as biasing means, however it will be appreciated that alternative biasing means are known to persons of ordinary skill in the art, including gas springs and magnetic biasing means. 
     An additional, separate locking device  80 , shown in FIG. 4, is preferably provided to prevent clutch mechanism  70  from disengaging should an overwhelming tension be applied to the clutch for any reason. Locking device  80  includes a spring latch  82  mounted atop drill frame  11  and having an opening  84  for receiving a catch member  86  on bearing housing  36 , thereby preventing the bearing housing and the chuck half  82  of the clutch from retracting. Locking device  80  is released by pressing spring latch  82  downward while pulling chuck  28  forward against the bias of spring  38 . 
     FIGS. 3 and 12 illustrate alternative embodiments incorporating an optional “drop-in” clutch feature of the present invention useful with inwardly biased chuck assemblies exemplified in FIGS. 5-8. FIG. 3 shows drive half  74  of clutch mechanism  70  as including an outer frusto-conical ramp  90  along which a rounded head  92  of each chuck half  72  rides during swiveling of turret  22  until “drop in” alignment is achieved. Ramp  90  facilitates adjustment between chuck assemblies  26 A and  26 B by gradually moving the newly selected chuck assembly to a retracted condition without need to manually pull on the newly selected chuck during changeover. As will be appreciated, once chuck half  72  becomes aligned with drive half  74 , it will automatically “drop in” for engagement with drive half  74  due to the bias of spring  38  and will be limited from traveling beyond the alignment point by locking device catch member  86  engaging locking device opening  84 , or alternatively by detent  25  and alignment member  27 A or  27 B, as previously described. 
     In the embodiment of FIG. 12, a frusto-conical ramp  94  is mounted externally of drill housing  12  with its central axis spaced from and parallel to turret pivot axis  5 . Ramp  94  includes a passage  96  aligned along tool drive axis  3 , and rounded head  92  rides along an outer surface of ramp  94  as turret  22  is swiveled about pivot axis  5  until it aligns with passage  96 , at which point the chuck half  72  will automatically be urged into engagement with the drive half  74  of clutch mechanism  70  by retraction spring  38 . 
     The manner of using drill  10  will now be described. Chucks  28  associated with chuck assemblies  26 A and  26 B are each loosened, loaded with a tool shank of a selected tool, and tightened individually in a conventional manner. Assuming chuck assembly  26 A is aligned and locked in operating position, the operator can quickly change to use the tool held by chuck assembly  26 B by pressing spring latch  82 , pulling chuck  28  of chuck assembly  26 A forward to release clutch mechanism  70 , and swiveling turret  22  one-hundred eighty degrees about pivot axis  5  until chuck assembly  26 B is aligned with drill tool axis  3  so that chuck half  72  is forced into engagement with drive half  74  and catch member  86  is resiliently guided through opening  84  until locking of the turret from further rotation occurs. If the chuck assembly is outwardly biased as shown in FIGS. 9-11, thumb latch  75  must be depressed to release the clutch engagement and the newly selected chuck must be pushed inward to engage the clutch mechanism prior to releasing pressure on the thumb latch. 
     The turret hand drill of the present invention permits an operator to repeatedly drill a hole and drive in a screw, without having to stop and replace the tools in the chuck each time. Moreover, the turret hand drill as described herein can be used without interference in all of the spaces available to a non-turreted drill, except for possibly a small overall length disadvantage. When turret  22  is locked in an operating position, all axes are in the central plane of the power drill and power drill handle. The design of the present invention also serves to position the idle tool and its holder so as to be well away from the working surface, and to have its longitudinal axis extending downwards generally parallel to the drill handle.