WO2008017151A2

WO2008017151A2 - Hammer drill bit chuck attachment

Info

Publication number: WO2008017151A2
Application number: PCT/CA2007/001378
Authority: WO
Inventors: Fern Beauchamp; Gerard Grand
Original assignee: Fern Beauchamp; Gerard Grand
Priority date: 2006-08-08
Filing date: 2007-08-08
Publication date: 2008-02-14
Also published as: WO2008017151A3; CA2555533A1

Abstract

A hammer drill bit chuck attachment comprises a main shaft having a forward drill chuck end portion and a rearward shank portion, and defining a longitudinal axis. An impact member is mounted in fixed relation on the main shaft for rotation therewith. An actuator mechanism is mounted on the main shaft for free rotation of the main shaft with respect to the actuator mechanism and for longitudinal sliding movement of the actuator mechanism along the main shaft between a forwardly displaced position and a rearwardly displaced position. Αt least one impact portion is disposed on one of the impact member and the actuator mechanism. At least one roller member is rotationally mounted on the other of the impact member and the actuator mechanism. Rotation of the main shaft and impact member about the longitudinal axis when the actuator mechanism is in force transmitting engagement with the impact member, causes the actuator mechanism to move in a reciprocating motion between the forwardly displaced position and the rearwardly displaced position, and transmits impact forces forwardly along the longitudinal axis to the main shaft.

Description

HAMMER DRILL BIT CHUCK ATTACHMENT

FIELD OF THE INVENTION

[0001] The present invention relates to hammer drills, and more particularly to hammer drill bit chuck attachments.

BACKGROUND OF THE INVENTION

[0002] Hammer drills are well known and are typically used, even by home craftsmen, to drill holes in relatively hard substances, such as concrete and the like. Such hammer drills typically have a rotating spindle that drives the drill chuck. A fixed disc having a rearwardly facing toothed surface is secured to the rotations spindle. A movable disc having a forwardly facing toothed surface is selectively engageable with the rearwardly facing toothed surface of the fixed disc so as to provide the hammer drill function. Although the apparatus does work, it presents a serious drawback in that the impact created by the engagement of the two toothed surfaces is directed forwardly through the drill bit and also back through the drill itself, as a reaction force. Accordingly, the bearings of the drill tend to wear excessively, which is highly undesirable. Further, it is well known that there can be significant heat build with prior art hammer drills.

[0003] Such hammer drills, also known as percussion drills, can be found in for example United States

Patent 2,942,852, issued June 28, 1960 to Muthman and United States Patent 5,653,294, issued August 5, 1997 to Thurier.

[0004] United States Patent 4,450,919, issued May 29, 1984 to Cousineau discloses a drill attachment for use with a conventional electric drill. This drill attachment provides a hammering and drilling action so that a conventional drill may be used to drill into hard substances. The drill attachment comprises a hammer assembly having a rearward case and a forward chuck assembly. A rotating spindle is mounted within the case and has a reciprocating spindle mounted in the front end thereof. The rotating spindle drives a drill chuck within the chuck assembly via the reciprocating spindle. A rotating clutch plate mounted on the reciprocating spindle rotates with the reciprocating spindle. Teeth on the rotating clutch plate engage cooperating teeth on the stationary clutch that is securely mounted on the case. A removable handle connected to the case permits the case, and therefore the stationary clutch, to be selectively moved forwardly such that the teeth of the stationary clutch engage the teeth of the rotating clutch plate, to thereby impart the hammering function to a drill bit retained within the bit chuck. The reaction force is not transmitted back through the drill itself, but is transmitted to the handle, thus saving wear on the bearings of the drill. However, the above described drill attachment is far more complicated and far more expensive than is necessary.

[0005] It is a further object of the present invention to provide a simplified hammer drill bit chuck attachment.

[0006] It is yet a further object of the present invention to provide a simplified hammer drill bit chuck attachment that is inexpensive to manufacture.

[0007] It is yet a further object of the present invention to provide a simplified hammer drill bit chuck attachment that is robust.

[0008] It is yet a further object of the present invention to provide a simplified hammer drill bit chuck attachment wherein the frequency and amplitude of impacts can be adjusted or selected.

[0009] It is yet a further object of the present invention to provide a simplified hammer drill bit chuck attachment wherein heat build up is minimized.

[00010] It is yet a further obj ect of the present invention to provide a hammer drill bit chuck attachment wherein an electric drill used in conjunction with the hammer drill bit chuck attachment can be operated at lower rotational speeds.

SUMMARY OF THE INVENTION

[00011] In accordance with one aspect of the present invention there is disclosed a novel hammer drill bit chuck attachment comprising a main shaft having a forward drill chuck end portion and a rearward shank portion, and defining a longitudinal axis. An impact member is mounted in fixed relation on the main shaft for rotation therewith. An actuator mechanism is mounted on the main shaft for free rotation of the main shaft with respect to the actuator mechanism and for longitudinal sliding movement of the actuator mechanism along the main shaft between a forwardly displaced position and a rearwardly displaced position. At least one impact portion is disposed on one of the impact member and the actuator mechanism. At least one roller member is rotationally mounted on the other of the impact member and the actuator mechanism. Rotation of the main shaft and impact member about the longitudinal axis when the actuator mechanism is in force transmitting engagement with the impact member, causes the actuator mechanism to move in a reciprocating motion between the forwardly displaced position and the rearwardly displaced position, and transmits impact forces forwardly along the longitudinal axis to the main shaft.

[00012] Other advantages, features and characteristics of the present invention, as well as methods of operation and functions of the related elements of the structure, and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following detailed description and the appended claims with reference to the accompanying drawings, the latter of which is briefly described herein below.

BRIEF DESCRIPTION OF THE DRAWINGS

[00013] The novel features which are believed to be characteristic of the hammer drill bit and hammer drill bit chuck attachment according to the present invention, as to its structure, organization, use and method of operation, together with further objectives and advantages thereof, will be better understood from the following drawings in which a presently preferred embodiment of the invention will now be illustrated by way of example. It is 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. In the accompanying drawings:

[00014] Figure 1 is a perspective view from the front of the first preferred embodiment of the hammer drill bit chuck attachment according to the present invention;

[00015] Figure 2 is a perspective view from the rear of the first preferred embodiment hammer drill bit chuck attachment of Figure 1;

[00016] Figure 3 is an exploded perspective view from the front of the first preferred embodiment hammer drill bit chuck attachment of Figure 1;

[00017] Figure 4 is an exploded perspective view from the rear of the first preferred embodiment hammer drill bit chuck attachment of Figure 1; [00018] Figure 5 is an enlarged exploded perspective view from the front of a portion of the second preferred embodiment hammer drill bit chuck attachment of Figure 1;

[00019] Figure 6 is an enlarged exploded perspective view from the back of a portion of the second preferred embodiment hammer drill bit chuck attachment of Figure 1;

[00020] Figure 7 is a side elevational view of the hammer drill bit chuck attachment of Figure 1 , but with the actuator mechanism in a fully forward position;

[00021 ] Figure 8 is a perspective view from the rear of the hammer drill bit chuck attachment as shown in

Figure 7;

[00022] Figure 9 is a side elevational view similar to Figure 7, but with the actuator mechanism in a disengaged position;

[00023] Figure 10 is a perspective view from the front of a second preferred embodiment of the hammer drill bit chuck attachment according to the present invention;

[00024] Figure 11 is a perspective view of a portion of the second preferred embodiment of the hammer drill bit chuck attachment of Figure 10;

[00025] Figure 12 is a perspective view from the front of the third preferred embodiment of the hammer drill bit chuck according to the present invention, without a drill chuck in place;

[00026] Figure 13 is a perspective view from the rear of the third preferred embodiment hammer drill bit chuck of Figure 12;

[00027] Figure 14 is a side elevational view of the third preferred embodiment hammer drill bit chuck of

Figure 12, with the actuator mechanism in its engaged position;

[00028] Figure 15 is a side elevational view of the third preferred embodiment hammer drill bit chuck of

Figure 12, with the actuator mechanism in its disengaged position; [00029] Figure 16 is a rear elevational view of the third preferred embodiment hammer drill bit chuck of

Figure 12;

[00030] Figure 17 is an exploded perspective view from the front of the third preferred embodiment hammer drill bit chuck of Figure 12;

[00031] Figure 18 is an exploded perspective view from the rear of the third preferred embodiment hammer drill bit chuck of Figure 12;

[00032] Figure 19 is an exploded side elevational view of the third preferred embodiment hammer drill bit chuck of Figure 12;

[00033] Figure 20 is a perspective view from the front of the third preferred embodiment hammer drill bit chuck of Figure 12, without a drill chuck in place;

[00034] Figure 21 is a perspective view from the rear of the third preferred embodiment hammer drill bit chuck of Figure 12;

[00035] Figure 22 is a perspective view from the rear of the third preferred embodiment hammer drill bit chuck of Figure 12, showing the actuator collar;

[00036] Figure 23 is a perspective view from the rear of the third preferred embodiment hammer drill bit chuck of Figure 12, showing the stationary toothed collar and the elongate main shaft;

[00037] Figure 24 is a end elevational view of the third preferred embodiment hammer drill bit chuck of

Figure 12, showing the actuator collar;

[00038] Figure 25 is a perspective view from the front of an alternative embodiment of the hammer drill bit chuck according to the present invention;

[00039] Figure 26 is an exploded perspective view from the front of the fourth preferred embodiment of the hammer drill bit chuck according to the present invention; [00040] Figure 27 is an exploded perspective view from the rear of the fourth preferred embodiment of Figure 26;

[00041] Figure 28 is a cross-sectional view of the fourth preferred embodiment of Figure 26, in place on a drill chuck; and,

[00042] Figure 29 is a cross-sectional view of the fourth preferred embodiment of Figure 26, without the drill chuck.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[00043] Referring to Figures 1 through 29 of the drawings, it will be noted that Figures 1 through 9 illustrate a first preferred embodiment of the hammer drill bit chuck attachment of the present invention, Figures 10 and 11 illustrates a second preferred embodiment of the hammer drill bit chuck attachment of the present invention, Figures 12 through 25 illustrate a third preferred embodiment of the hammer drill bit chuck attachment of the present invention, and 26 through 29 illustrate a fourth preferred embodiment of the hammer drill bit chuck attachment of the present invention.

[00044] Reference will now be made to Figures 1 through 9, which show a first preferred embodiment of the hammer drill bit chuck attachment of the present invention, as indicated by general reference numeral 120. The hammer drill bit chuck attachment 120 comprises a main shaft 130 having a threaded forward drill chuck end portion 132, an intermediate impact member receiving portion 133, and a rearward shank portion 134. The main shaft 130 defines a longitudinal axis "L" about which the main shaft 130 rotates.

[00045] A drill bit chuck 135 is mountable on the forward drill chuck end portion 132 of the main shaft

130 for rotation therewith, as can be best seen in Figures 1 and 2. The drill bit chuck 135 is a conventional drill bit chuck and comprises three movable jaw members 136 that receive and retain a conventional drill bit 129 therein. A ferrule member 137 surrounds the jaw members 136 and is wedged between the jaw members 136 and an outer housing 138 to keep the jaw members 136 locked in place on the conventional drill bit 129. A base member 139 is secured in place within the outer housing 138 and the back end 136b of the jaw members 136. The base member 139 has a threaded bore hole 139a that receives a co-operating threaded forward portion 134a of the rearward shank portion 134 in secure engagement. Fundamentally, the hammer drill bit chuck attachment 120 comprises a main shaft 130, an impact member 190 and an actuator mechanism 150, as will be described in greater detail below. [00046] An impact member 140 comprises a main body portion 142, a forwardly facing surface 145, a rearward facing surface 146 and at least one impact portion. Alternatively, the at least one impact member can be mounted on the actuator mechanism 150. In the first preferred embodiment, as illustrated, the at least one impact portion comprises a plurality of impact portions 149. As can be readily seen in the figures, the plurality of impact portions 149 comprise a plurality of impact protrusions 149. Alternatively, it is contemplated that the plurality of impact portions could comprise a plurality of impact indentations. As illustrated, there are twenty-four impact protrusions 149 substantially evenly spaced around the rearwardly facing surface 146 of the impact member 140. Alternatively, there can be any suitable number of impact portions.

[00047] The impact member 140 is mounted in fixed relation on the main shaft 130 for rotation therewith, and projects radially outwardly from the intermediate impact member receiving portion 133. The impact member 140 is threadibly engaged on the intermediate impact member receiving portion 133 the main shaft 130. The threads on the forward drill chuck end portion 132 and the intermediate impact member receiving portion 133 are co-operatingly aligned with each other such that the impact member 140 can be threadibly engaged from the forward drill chuck end portion 132 to the intermediate impact member receiving portion 133. The rearward facing impact surface 146 may be integrally formed on the main body portion 142, or alternatively, as shown in Figures 10 and 11 may be formed on a rearward ring member 145. The alternative embodiment as shown in Figure 10 also shows a protective sheath 147 disposed over the actuator mechanism 150. The protective sheath 147 is preferably made from a suitable plastic material and is overmolded over the actuator mechanism 150. The plastic protective sheath 147 insulates an operator's hand from potential electric shock if the drill bit 129 happens to contact a live electrical wire during drilling.

[00048] The rearward facing impact surface 146 has a plurality of radially directed teeth 148 that are substantially evenly spaced around the rearward facing impact surface 146. Alternatively, the radially directed teeth 148 of the rearward facing impact surface 146 may be irregularly spaced, or spaced apart in any other suitable manner.

[00049] An actuator mechanism 150 comprises a main body member 152, a forwardly facing surface 156 and a rearwardly facing surface 155. The actuator mechanism 150 is mounted on the main shaft 130, mostly at the rearward shank portion 134 rearwardly of the impact member 140, for free rotation about the main shaft 130 and for longitudinal sliding movement along the main shaft 130. In the preferred embodiment, as illustrated, the actuator mechanism 150 is retained on the rearward shank portion 134 by means of a "C"-clip 160 securely engaged in an annular slot 162 in the rearward shank portion 134. Other suitable means may also be used. The section of the rearward shank portion 134 disposed rearwardly of the impact member 140 must be of sufficient length to be securely received in the bit chuck of a conventional electric drill.

[00050] At least one roller member, and in the first preferred embodiment as illustrated, a plurality of roller members (specifically three roller members 160), are rotationally mounted on the main body member 152 of the actuator mechanism 150 by means of mounting pins 161 press fit into cooperating apertures 153 in the main body member 152. Alternatively, the roller members 160 could be mounted on the impact member 140. The axis of rotation "R" of each roller member 160 is substantially perpendicular to the longitudinal axis "L" of the main shaft 150. The roller members 160, as illustrated, are bearing assemblies having an outer ring freely rotatably mounted onto an inner hub. Other suitable designs of roller members 160 could also be used.

[00051] The actuator mechanism 150 is mounted on the rearward shank portion 134, as described above, in freely rotatable relation on the main shaft 130 for rotation about the rearward shank portion 134 and for longitudinal sliding movement along the main shaft 130 between a forward forwardly displaced position, as is best seen in Figures 7 and 9, and a rearward rearwardly displaced position, as is best seen in Figure 8. The "C"-clip 160 defines the rearward rearwardly displaced position of the actuator collar.

[00052] A manually manipulable handle 170 is removably connected to the actuator mechanism 150 by means of a threaded shaft 172 threadibly engaged in a co-operating threaded bore hole 151. The handle 170 permits manual manipulation of the actuator mechanism 150 by a user's hand, so as to cause the longitudinal sliding movement of the actuator mechanism 150 between the forward forwardly displaced position and the rearward rearwardly displaced position. The manually manipulable handle 170 is preferably made from a suitable plastic material in order to insulate an operator's hand from potential electric shock if the drill bit 129 happens to contact a live electrical wire during drilling.

[00053] The rearward shank portion 134 merely freely rotates within the actuator mechanism 150. When the manually manipulable handle 170 is not held by a user, the actuator mechanism 150 and the handle 170 do not rotate with the rearward shank portion 134, but remain essentially in one position due to the weight of the handle 170.

[00054] Rotation of the main shaft 130 and the impact member 140 about the longitudinal axis "L" when the actuator mechanism is in its forwardly displaced position, the roller members 160 engage the plurality of impact protrusions 149 on the rearward facing impact surface 146 of the impact member 140 as the main shaft 130 rotates with respect to the actuator mechanism 150, as would occur during normal use of an electric drill (not shown). The actuator mechanism 150 is thereby caused to move in a reciprocating motion between its forwardly displaced position and its rearwardly displaced position. In this manner, the roller members 160 impart reciprocating motion along the longitudinal axis "L" to the main shaft 130, to thereby transmit impact forces forwardly along the longitudinal axis "L" to the main shaft 130, and therefore to the conventional drill bit 129. It would be readily understood by one skilled in the art that the roller members 160 generally ride along the rearward facing impact surface 146, and may impact all of the impact protrusions 149, or impacts only higher portions of the impact protrusions 149, depending on the speed of rotation of the impact member 140 with respect with the actuator mechanism 150,

[00055] The height, radius of curvature, shape and number of teeth 148 will affect the frequency and amplitude of the impacts of the roller members 150 on the rearward facing impact surface 146.

[00056] As can be readily seen in Figure IQ, the rearward ring member 145 maybe set permanently in place by means of press-fitting or screw-fitting, or both, or maybe removably and replaceable so as to allow an end user to select the frequency and amplitude of impacts, as desired.

[00057] As described above, the conventional drill bit 129 is caused to "hammer" into a piece of material as it rotates, thus causing a drill hole to be drilled readily even into hard materials, such as cement or concrete. It should also be noted that the electric drill itself does not absorb the reaction of the impact of the roller members 160 on the teeth 148 of the rearward facing toothed surface 146.

[00058] A spring means 170 is operatively mounted between the actuator mechanism 150 and the main shaft 130 for biasing the actuator mechanism 150 to the forward forwardly displaced position. More specifically, the spring means 170 comprises a coil spring 170 that is operatively mounted between the actuator mechanism 150 and the impact member 140 through the main shaft 130. The back end of the coil spring 170 bears against a washer 153, which itself bears against the "C"-clip 160. The front end of the coil spring 170 bears against a roller bearing 151 securely seated within the actuator mechanism 150. In this manner, the coil spring 170 biases the actuator mechanism 150 through its forward forwardly displaced position. Accordingly, when the elongate main shaft 30 and the impact member 140 are rotated, the actuator mechanism 150 is rotated therewith. In use, the actuator mechanism 150 is moved slightly rearwardly to its forward forwardly displaced position against the force of the coil spring 170. Further rearward movement of the actuator mechanism 150 will cause the actuator mechanism 150 to move to its rearwardly displaced position.

[00059] In an alternative embodiment of the present invention (not illustrated), it is contemplated that a spring could bias the actuator mechanism 150 to its rearwardly displaced position. Accordingly, the actuator mechanism 150 does not rotate, or at least not substantially so, when the main shaft 130 is rotated during use. This is advantageous in that when the actuator mechanism 150 is grasped by an operator for use, it is not rotating, and is therefore more readily grasped.

[00060] It has been found that with the hammer drill bit chuck attachment 120 of the present invention, there is reduced friction, reduced heat build up, reduced wear and improved drilling performance compared with conventional hammer drills, which have two sets of impacting steel teeth used to perform the hammering function. Heat build up is of particular concern under IEC 60745-1 :2001 , as adopted by UL, CSA and other national governing bodies regulating safety in hand held power tools and accessories. An electric drill using the present invention experiences very minimal loss of speed due to the reduced friction between the roller members 150 and the impact member. Accordingly, the rotational energy is directed to the actual longitudinal vibration, and not to losses due to friction and heat. This is important for being able to achieve the maximum possible speed with a drill, and also for reduced wear of the hammer drill bit chuck attachment of the present invention and an electric drill being used. In contrast, an electric hammer drill actually operates at a significantly reduced rotational speed compared to the maximum rotational speed of the drill, due to the friction of the steel teeth.

[00061] Reference will now be made to Figures 10 and 11, which show a second preferred embodiment of the hammer drill bit chuck attachment of the present invention, as indicated by general reference numeral 220. The second preferred embodiment hammer drill bit chuck attachment 220 is similar to the first preferred embodiment hammer drill bit chuck attachment 120 except that the rearward facing impact surface 246 is formed on a rearward ring member 245 that is secured to the main body portion 242. The rearward ring member 245 may be set permanently in place by means of press-fitting or screw-fitting, or both, or maybe removably and replaceable so as to allow an end user to select the frequency and amplitude of impacts, as desired. The second preferred embodiment also shows a protective sheath 247 disposed over the actuator mechanism 250. The protective sheath 247 is preferably made from a suitable plastic material and is overmolded over the actuator mechanism 250. The plastic protective sheath 247 insulates an operator's hand from potential electric shock if the drill bit (not specifically shown) happens to contact a live electrical wire during drilling.

[00062] Reference will now be made to Figures 12 through 25, which show a third preferred embodiment of the hammer drill bit chuck attachment of the present invention, as indicated by general reference numeral 320. The hammer drill bit chuck attachment 320 comprises amain shaft 330 having athreaded forward drill chuck end portion 332, an intermediate impact member receiving portion 333, and an elongate rearward shank portion 334. The main shaft 330 defines a longitudinal axis "L" about which the main shaft 330 rotates. [00063] A drill bit chuck 335 is mountable on the threaded forward drill chuck end portion 332 for rotation therewith. The drill bit chuck 335 is preferably a conventional drill bit chuck and comprises three movable jaw members 336 that receive and retain a conventional drill bit 329 therein. A ferrule member 337 surrounds the jaw members 336 and is wedged between the jaw members 336 and an outer housing 338 to keep the jaw members 336 locked in place on the conventional drill bit 329. A base member 339 is secured in place within the outer housing 338 and the back end 336b of the jaw members 336. The base member 339 has a threaded bore hole 339a that receives a co-operating threaded forward portion 334a of the rearward shank portion 334 in secure engagement. Fundamentally, the hammerdrill bit chuck attachment 320 comprises a main shaft 330, an impact member 340, and an adapter mechanism 350, as will be described in greater detail below.

[00064] An impact member 340 comprises a main body portion 342, a forwardly facing surface 345 and a rearwardly facing surface 346, and at least one impact portion. Alternatively, the at least one impact member can be mounted on the actuator mechanism 350. In the third preferred embodiment, as illustrated, the at least one impact portion comprises a plurality of impact portions 348. As can be readily seen in the figures, the plurality of ball bearings 348 rotatably mounted in the rearwardly facing surface 346 of the impact member 340. Alternatively, it is contemplated that the plurality of impact portions could comprise a plurality of impact indentations. As illustrated, there are twenty-four impact protrusions 348 substantially evenly spaced around the rearwardly facing surface 346 of the impact member 340. Alternatively, there can be any suitable number of impact portions.

[00065] The impact member 340 is mounted in fixed relation on the main shaft 330 for rotation therewith, and projects radially outwardly from the intermediate impact member receiving portion 333. The impact number 340 is slid over the elongate rearward shank portion 334 and is press-fit onto the intermediate impact member receiving portion 333 of the main shaft 330. The intermediate impact member receiving portion 333 is a few thousandths of an inch larger in diameter than the elongate rear shank portion 334.

[00066] An actuator mechanism 350 having a forwardly facing surface 356 and a rearwardly facing surface 355 is mounted in freely rotatable relation on the rearward shank portion 334 of the main shaft 330, immediately rearwardly of the impact member 340, for free rotation about the rearward shank portion 334 and for longitudinal sliding movement along the rearward shank portion 334. In the preferred embodiment, as illustrated, the actuator mechanism 350 is retained on the rearward shank portion 334 by means of a "C"-cIip 360 securely engaged in an annular slot 362 in the rearward shank portion 334, that bears against a washer 361. A second annular slot 362 is also included. Other suitable means may also be used. The section of the rearward shank portion 334 disposed rearwardly of the actuator mechanism 350 must be of sufficient length to be securely received in the bit chuck of a conventional electric drill. [00067] The actuator mechanism 350 is mounted on the rearward shank portion 334, as described above, for free rotation about the rearward shank portion 334 and for longitudinal sliding movement along the rearward shank portion 334 between a forward forwardly displaced position, as is best seen in Figures 12, 13, 14, 20 and 21, and a rearward rearwardly displaced position, as is best seen in Figure 28. The "C"-clip 360 defines the rearward rearwardly displaced position of the actuator collar.

[00068] The actuator mechanism 350 has at least one roller member rotationally mounted thereon, and in the third preferred embodiment as illustrated, has at least one ball bearing 358 mounted thereon. More specifically, the at least one ball bearing 350 comprises a plurality (specifically twelve) ball bearings 358 rotationally mounted in the forwardly facing surface 356 of the actuator mechanism 350. The ball bearings 358 are rotationally mounted and otherwise positioned to engage the ball bearings 348 in the impact member 340, as will be discussed in greater detail subsequently.

[00069] The ball bearings 358 in the actuator mechanism 350 and the ball bearings 348 in the impact member 340 are each mounted within a co-operating cylindrical recess 349,359 having a diameter slightly greater than the diameter of the ball bearings 348,358, and a depth slightly less than the diameter of the ball bearings 348,358, so that the ball bearings 348,358 project outwardly from the cooperating recesses 349,359 respectfully. Preferably, the ball bearings 348,358 are each mounted within the co-operating recesses 349,359 by means of a suitable grease type material, so as to help retain the ball bearings 348,358 in place.

[00070] It has been found that ball bearings 348,358 having a diameter of about 5/16" are suitable, although other sizes of ball bearings 348,358 could also be used. It has also been found that the ball bearings 348,358 of about this size should protrude beyond the rearwardly facing surface 346 of the impact member 340 and the forwardly facing surface 356 of the actuator mechanism 350, as the case may be, by up to about 0.050", or even more, and preferably by about 0.025", depending on the diameter of the ball bearings 348,358. Although the ball bearings 348 and the ball bearings 358 are shown to be the same diameter as each other, this is not absolutely necessary.

[00071] As can be seen in the Figures, there is also an optional elongate bore hole 353 in communication with each recess 359 in the actuator mechanism 350, for permitting the ball bearings 358 to be readily removed.

[00072] Rotation of the main shaft 330 and the impact member 340 about the longitudinal axis "L" when the actuator mechanism 150 is in its forward forwardly displaced position, causes the ball bearings 358 in the actuator mechanism 350 are in engagement with the ball bearings 348 (the impact portions) of the impact member 340 as the rearward main shaft 330 is rotated. The ball bearings 358 in the forwardly facing surface 356 of the actuator mechanism 350 quickly impact the ball bearings 348 in the rearwardly facing surface 346 of the impact member 340, as the main shaft 330, and therefore the impact member 340, is rotated by the conventional electric drill 322. The actuator mechanism 350 Is thereby caused to move in a reciprocating motion between its forwardly displaced position and its rearwardly displaced position The actuator mechanism 350 thereby imparts reciprocating motion along the longitudinal axis "L" to the drill bit chuck 335, to thereby transmit impact forces along the longitudinal axis "L" to the main shaft 350, and therefore to the conventional drill bit 329 retained therein. In this manner, the conventional drill bit 329 is caused to "hammer" into a piece of material as it rotates, thus causing a drill hole to be drilled readily even into hard materials, such as cement or concrete. The plurality of ball bearings 348 and 358 are each rotationally mounted in evenly radially spaced relation around the longitudinal axis "L" to provide for an even impacting action. It should also be noted that the drill 322 itself does not absorb the reaction of the impact of the ball bearings 358 of the actuator mechanism 350 on the ball bearings 348 of the impact member 340.

[00073] In the rearward rearwardly displaced position, the ball bearings 358 of the actuator mechanism

350 are removed from the rotational engagement with the ball bearings 348 of the impact member 340. The rearward shank portion 334 of the main shaft 330 merely freely rotates within the actuator mechanism 350, or alternatively, the actuator mechanism 350 merely freely rotates around the rearward shank portion 334 of the main shaft 330.

[00074] The third preferred embodiment hammer drill bit chuck attachment 320 further comprises an insulating cover 351 peripherally surrounding the actuator mechanism 350. Preferably, the insulating cover 351 is made from a synthetic rubber or plastic material, and is overmolded on the actuator mechanism 350. The insulating cover 351 is used to electrically insulate the actuator mechanism 350 from a user's hand, when a user grasps the actuator mechanism 350 during use to preclude the actuator mechanism 350 from turning with the impact member 340, thus allowing the ball bearings 358 on the actuator mechanism 350 to impact the ball bearings 348 on the impact member 340, thereby imparting reciprocating motion along the longitudinal axis "L" to the main shaft 330. It has been found that grasping the insulating cover 351 permit for the accurate application of manual force along the longitudinal axis "L".

[00075] It can also be seen that the third preferred embodiment hammer drill bit chuck attachment 320 permits bi-directional rotational operation of the elongate main shaft 330 and therefore the forward drill bit portion 332, although it would not be overly common to require the third preferred embodiment hammer drill bit 320 to operate it the reverse direction. [00076] In an alternative embodiment, a shown in Figure 25, it is contemplated that a manually manipulable handle 370 is removably connected to the actuator mechanism 350 by means of a threaded shaft 372 threadibly engaged in a co-operating threaded bore hole 371. The handle 370 permits manual manipulation of the actuator mechanism 350 by a user's hand, so as to cause the longitudinal sliding movement of the actuator mechanism 350 between the forward forwardly displaced position and the rearward rearwardly displaced position. When the manually manipulable handle 370 is not held by a user, the actuator mechanism 350 and the handle 370 do not rotate with the main shaft 330, but remain essentially in one position due to the weight of the handle 370.

[00077] Reference will now be made to Figures 26 through 29, which shows a fourth preferred embodiment of the hammer drill bit chuck attachment of the present invention, as indicated by general reference numeral 420. The fourth preferred embodiment of the hammer drill bit chuck attachment 420 is similar to the third preferred embodiment of the hammer drill bit chuck attachment 320, except for the inclusion of a spring means 470 operatively mounted between the actuator collar 450 and the elongate main shaft 430 for biasing the actuator collar 450 to the forward forwardly displaced position. More specifically, the spring means 470 comprises a coil spring 470 that is operatively mounted between the actuator collar 450 and the stationary toothed collar 440. The coil spring 470 sits within a recess 452 in the back end of the actuator collar 450, and surrounds the back end of the shank portion 434 of the elongate main shaft 430. The coil spring 470 bears against the forward end 452a of the recess 452 and also bears against a washer 453, which itself bears against the "C"-clip 460. In this manner, the coil spring 470 biases the actuator collar through its forward forwardly displaced position and to its fully forward position. Accordingly, when the elongate main shaft 430 and the stationary toothed collar 440 are rotated, the actuator collar 450 is rotated therewith. In use, the actuator collar 450 is moved slightly rearwardly to its forward forwardly displaced position against the force of the coil spring 470.

[00078] As can be understood from the above description and from the accompanying drawings, the present invention provides a hammer drill bit chuck attachment that is inexpensive to manufacture, that is robust, wherein the frequency and amplitude of impacts can be adjusted or selected, wherein heat build up is minimized, and wherein an electric drill used in conjunction with the hammer drill bit chuck attachment can be operated at lower rotational speeds, all of which features are unknown in the prior art.

[00079] Other variations of the above principles will be apparent to those who are knowledgeable in the field of the invention, and such variations are considered to be within the scope of the present invention. Further, other modifications and alterations may be used in the design and manufacture of the hammer drill bit and hammer drill bit chuck attachment of the present invention without departing from the spirit and scope of the accompanying claims.

Claims

I CLAIM:

1. A hammer drill bit chuck attachment comprising:

a main shaft having a forward drill chuck end portion and a rearward shank portion, and defining a longitudinal axis;

an impact member mounted in fixed relation on said main shaft for rotation therewith; and,

an actuator mechanism mounted on said main shaft for free rotation of said main shaft with respect to said actuator mechanism and for longitudinal sliding movement of said actuator mechanism along said main shaft between a forwardly displaced position and a rearwardly displaced position;

at least one impact portion disposed on one of said impact member and said actuator mechanism; and,

at least one roller member rotationally mounted on the other of said impact member and said actuator mechanism;

wherein rotation of said main shaft and impact member about said longitudinal axis when said actuator mechanism is in force transmitting engagement with said impact member, causes said actuator mechanism to move in a reciprocating motion between said forwardly displaced position and said rearwardly displaced position, and transmits impact forces forwardly along said longitudinal axis to said main shaft.

2. The hammer drill bit chuck attachment of claim 1 , wherein said at least one roller member comprises at least one ball bearing rotationally mounted in said actuator mechanism, and said at least one impact portion is on said impact member.

3. The hammer drill bit chuck attachment of claim 2, wherein said at least one ball bearing rotationally mounted in said actuator mechanism comprises a plurality of ball bearings rotationally mounted in said actuator mechanism.

4. The hammer drill bit chuck attachment of claim 3 , wherein said plurality of ball bearings are rotationally mounted in evenly radially spaced relation around said longitudinal axis.

5. The hammer drill bit chuck attachment of claim 1, wherein said actuator mechanism is retained on said rearward shank portion of said main shaft by means of a "C"-clip securely engaged in an annular slot in said rearward shank portion.

6. The hammer drill bit chuck attachment of claim 1 , further comprising spring means operatively mounted between said actuator mechanism and said main shaft for biasing said actuator mechanism to said forwardly displaced position.

7. The hammer drill bit chuck attachment of claim 1 , further comprising a manual manipulable handle connected to said actuator mechanism for permitting said longitudinal sliding movement of said actuator mechanism between said forward forwardly displaced position and said rearward rearwardly displaced position.

8. The hammer drill bit chuck attachment of claim 7, wherein said handle is removably connected to said actuator mechanism.

9. The hammer drill bit chuck attachment of claim 1 , wherein said impact member has an impact surface and said at least one roller member engages said impact surface.

10. The hammer drill bit chuck attachment of claim 9, wherein said impact surface is rearwardly facing.

11. The hammer drill bit chuck attachment of claim 1 , wherein said at least one roller member comprises a plurality of roller members.

12.The hammer drill bit chuck attachment of claim 11 , wherein said plurality of roller members comprises three roller members.

13.The hammer drill bit chuck attachment of claim 3, wherein said plurality of ball bearings are rotationally mounted in evenly radially spaced relation around said longitudinal axis.

14.The hammer drill bit chuck attachment of claim 1, wherein said impact surface is rearwardly facing.

15.The hammer drill bit chuck attachment of claim 14, wherein said at least one roller member comprises a plurality of roller bearings.

16. The hammer drill bit chuck attachment of claim 12, wherein said plurality of roller bearings comprises three roller bearings.

17.The hammer drill bit chuck attachment of claim 15, wherein said plurality of roller bearings are rotationally mounted in evenly radially spaced relation around said longitudinal axis.

18.The hammer drill bit chuck attachment of claim 15, further comprising a manual manipulable handle connected to said actuator mechanism for permitting said longitudinal sliding movement of said actuator mechanism between said forward forwardly displaced position and said rearward rearwardly displaced position.

19. The hammer drill bit chuck attachment of claim 18, wherein said handle is removably connected to said actuator mechanism.

2O.The hammer drill bit chuck attachment of claim 1 , further comprising spring means operatively mounted between said actuator mechanism and said main shaft for biasing said actuator mechanism to said forwardly displaced position.