I CLAIM :
1. A hammer drill comprising:
a casing;
an electric motor mounted within said casing;
a drive shaft connected in driven relation to said electric motor, and defining a lonqitudinal axis;
a drill bit chuck mounted in driven relation to said drive shaft;
an impact member having at least one impact portion, and
» mounted in fixed relation on said drive shaft for rotation
Lherewith; and, t i
an actuator mechanism having at least one roller member rotationally mounted thereon, said actuator mechanism mounted in freely rotatable relation on said drive shaft for longitudinal sliding movement along said drive shall, between an operatively engaged position whereat said at least one roller member engages said at least one impact portion of said impact member as said drive shaft rotates wilh respect to said actuator mechanism, so as to thereby impart reciprocating motion along said longitudinal axis to said drive shaft and said drill bit chuck, and a disengaged position whereat said at leas I one roller member is removed from said engagement with said at least one impact portion of said impact member.
2. The hammer drill of claim 1, wherein said at least one roller member comprises three roller members.
3. The hammer drill of claim 1, wherein said impact surface is rearwardly facing.
4. The hammer drill 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 operatively engaged position and said rearward disengaged position.
5. The hammei drill of claim 4, wherenη said handle is removably connected to said actuator mechanism.
6. The hammer drill of claim 1, wherein said at least one impact portion form a shaped impact surface.
7. The hammer drill of claim 6, wherein said at least one impact porLion comprises a plurality of impact portions.
8. The hammer drill of claim 7, wherein said plurality of impact portions includes a plurality of protrusions.
9. The hammer drill of claim 6, wherein said plurality of impact portions includes a plurality of indentations.
10. The hammer drill of claim 1, wherein said at least one impact portion comprises a plurality of impact parts secured to said impact member. |
HAMMER DRILL
FIELD OF THE INVENTION
[0001] The present invention relates to hammer drills, and more particularly to hammer drills that produce a hammering effect efficiently.
BACKGROUND OF THE INVENTION
[0002] Hammer drills are well known and are typically used, even by homo craftsmen, to drill holes in relatively hard substances, such as concreLe 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 αf 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.
[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 Thurler.
[0004] It is yet a further object of the present invention to provide a hammer drill that is inexpensive to manufacture.
[0005] It is yet a further object of Lhe present invenlion to provide a hammer drill that is robust.
[0006] It is yet a further object of the present invention to provide a hammer drill wherein the frequency and amplitude of impacts can be adjusted or selected.
[0007] It is yet a further object of the present invention to provide a hammer drill wherein heat build up is minimized.
[0003] It is yet a further object of the present invention to provide a hammer drill that can be operated at lower rotational speeds than prior art hammer drills.
SUMMARY OF THE INVENTION
[0009] In accordance with one aspect of the present invention there is disclosed a novel hammer drill comprising a casing, and an electric motor mounted within the casing. A drive shaft is connected in driven relation to the electric motor, and defines a longitudinal axis. A drill bit chuck is mounted in driven relation to the drive shaft. An impact member having at least one: impact portion is mounted in fixed relation on the drive shaft for rotation therewith. An actuator mechanism has at least one roller member rotational Iy mounted thereon. The actuator mechanism is mounted in freely rotatable relation on the drive shaft for longitudinal sliding movement along the drive shaft between an operatively engaged position whereat the at least one roller member engages the at least one impact portion of the impact member as the drive shafL rotates with respect to the actuator mechanism, so as to thereby impart reciprocating motion along ttψ longitudinal axis to the drive shaft and the drill bit chuck, and a disengaged position whereat the at least one roller member is removed from the engagement with the at least one impact portion of the impact member.
[00010] 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, lhe latter of which is briefly described herein below.
BRIEF DESCRIPTION OF THE DRAWINGS
[00011] The novel features which are believed to be characteristic of the hammer drill according to Lhe present invention, as to iLs structure, organization, use and method of operation, Logether with further objectives and advantages thereof, will be better understood from ths 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:
[00012] Figure 1 is a perspective view from Lhe front of the first preferred embodiment of the hammer drill according to the present invention;
[00013] Figure 2 is a perspective view from the roar of the first preferred embodiment of the hammer drill of Figure 1;
[00014] Figure 3 is a side elcvational view of the first preferred embodiment hammer drill of Figure 1, with the drill chuck not shown for the sake of clarity, and with the actuator mechanism in a fully forward position;
[00015] Figure 4 is a side elovational view similar to Figure 3, but with the actuator mechanism in a disengaged position;
[00016] Figure 5 is a perspective view from the rear of the second preferred embodiment of the hammer drill according to the present invention;
[00017] Figure 6 is a perspective view from the rear of the third preferred embodiment of t the hammer drill according to the present? invention;
[00018] Figure 7 i3 a perspective view from the front of the fourth preferred embodiment of the hammer drill according to the present invention;
[00019] Figure B is a perspective view from the rear of the rear of the fourth preferred embodiment hammer drill of Figure 7;
[00020] Figure 9 is a side elevational view of the fourth preferred embodiment hammer drill of the Figure I 1 with the actuator mechanism in an engaged position; and,
[00021] Figure 10 is a side elevational view of the fourth preferred embodiment hammer drill of Figure I 1 with the actuator mechanism in a disengaged position.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
1000223 Referring to Figures 1 through 10 of the drawings, it will be noted Lhat Figures 1 through 4 illustrate a first preferred embodiment of the hammer drill of the present invention, Figure 5 illustrates a second preferred embodiment of the hammer drill of the present invention, Figure 6 illustrates a third preferred embodiment of the hammer drill of the present invention, and Figures 7 Lhrough 10 illustrate a fourth preferred embodiment of Lhe present invention.
[00023] Reference will now be made to Figures 1 through 4 which show a fj-rst preferred embodiment of the hammer drill of the present invention, as indicated by general reference numeral 120. The hammer drill 120 comprises a casing 128 made from a suitable plastic material, or any other suitable material. An electric motor 120 is mounted within the casing 128 and is electrically powered in a conventional manner for drills, as is well known in the related art: . A drive shaft 130 defines a longitudinal axis ^L" about which it rotates, and in connected in driven, relation to the electric; motor 127.
[00024] A drill bit chuck 135 is mounted on the drive shaft 130 for rotation therewith. The drill bit chuck 135 comprises three movable jaw members 136 that receive and retain a conventional drill bit 129 therein.
[00025] An impact member 140 is mounted in fixed relation on the drive shaft 130 for longitudinal and rotational movement therewith In the first preferred embodiment, as illustrated, the impact member 140 has a rearward facing impact surface 146 that is integrally formed on the main body portion 142. Alternatively, Lhe rearward facing impact surface 146 may be formed on a rearward ring member (not specifically shown) .
[00026] The impact member 140 has at least one impact portion 148 at the impact rearward facing impact surface 146. The at least one impact portion comprises a plurality of impact portions 148, and as can readily be seen in the figures, the plurality of impact; portions 148 includes a plurality of protrusions. Alternatively, iL is contemplated that the plurality of impact portions could include a pluraliLy of indentations. In the first preferred embodiment, as illustrated, there are twenty-four impact portions 14R, that can also bo considered to be in the form of radially directed teeth. The twenty-four impact portions 148 are substantially evenly spaced around the rearwardly facing impact surface 146. Alternatively, there can be any suitable number of impact portions. As can readily be seen in the Figures, the impact portions 148 form a shaped impact surface 146.
[00027] Further, the impact portions can be formed as parl. of the impact member 140 without there actually being an impact surface.
Also alternatively, the roller members 160 may be irregularly spaced, or spaced apart in any other suitable manner.
[00028] An actuator merhanism 150 comprises a main body member 152. The actuator mechanism 150 is mounted in freely rotatable relation on the drive shaft 130 rearwardly of the impact member 140, for longitudinal sliding movement along the drive shaft 130
between a forward operatlvely engaged position, as is best: seen in Figure 3, and a rearward disengaged position, as is best seen in Figure 4. In the first preferred embodiment, the actuator mechanism 150 is retained on the drive shaft 130 by means of a "C"- clip 161 securely engaged in an annular slot 162 in the drive shaft 130. The "C"-clip 161 defines the rearward disengaged position of the actuator collar. Other suitable means may also be used.
[00029] The actuator mechanism 150 has at least one roller member, and in the first preferred embodiment as illustrated, three roller members 160, are rotationally mounted on the main body member 152 of the actuator mechanism 150 by means of mounting pi ns 161 press fit into cooperating apertures 153 in the main body member 152. The axis of rotation "R" of each roller member 160 is substantially perpendicular to the longitudinal axis "L" of the drive shaft 150. The roller members 160, as illustrated, arc bearing assemblies having an outer ring freely rotatably mounted onto an inner hub. other suitable designs of roller members 160 could also be used.
[00030] 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 handl e 170 permits manual manipulation of the actuator mechanism
] 50 by a user's hand, sυ as to cause the longitudinal sliding movement of the actuator mechanism 150 between the forward operatively engaged position and the rearward disengaged position.
The gap between the roller members 160 and the impact portions 148 as occurs in the rearward disengaged position, is indicated by arrow M G" in Figure 4. 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.
[00031] Tn the operatively engaged position the roller members 160 engage the impact portions 148 of the impact member 140 as the drive shaft 130 rotates with respect to the actuator mechanism 150, as would occur during normal use of an electric drill (not shown) . In this manner, the roller members 160 impart reciprocating motion along the longitudinal axis "L" to the drive shaft 130. 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 rearward facing impact surface 146, or impacts only higher portions of the rearward facing impact surface 146, depending on the speed of rotation of the impact member 140 with respecL with the actuator mechanism 150.
[00032] 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.
[000331 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 IAB of the rearwardly facing toothed surface 146.
[00034] In Lhe disengaged position, the roller members 160 are removed from engagement with the rearward facinq impact surface 146. In this manner, an electric drill having the hammer drill 120 of the present invention mounted thereon, would be used as a conventional drα11.
[00035] Reference will now be made to Figure 5, which shown a second preferred embodiment of the hammer driJ 1 o£ the present invention, as indicated by general reference numeral 220. The hammer drill 220 is similar l;o the first preferred embodiment hammer drill 120 except that the at least one impact portion comprises a plurality of impact pal Ls 248 secured to said impact
member 240. More specifically, the impact parts 248 each comprise a sma.11 roller bearing rotatably mounted on the impact member 240. λs can be readily seen, in this embodiment, there is not an overall impact surface on the impact member 240.
[00O36] Reference will now be made to Figure 6, which shows a third preferred embodiment of the hammer drill of the present invention, as indicated by general reference numeral 320. The hammer drill 320 is similar Lo the first preferred embodiment hammer drill 120 except that the plurality of impact portions 348 includes a plurality of indentations .
[00037] in an alternative embodiment of the present invention
(not illustrated), it is contemplated that a spring could bias the actuator mechanism 150 to its disengaged position. Accordingly, the actuator mechanism 150 does not rotate, or at least not substantially so, when the drive shaft 13p is rotated during use. This is advantageous in that when the actuator mechanism 150 is grasped by an operator for use, \t is not rotating, and is therefore more readily grasped.
[00038] Reference will now be made to Figures 7 through 10, which shows a fourth preferred embodiment of the hammer dull 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 4?0 iε similar to the third preferred embodiment of the hammer drill bit chuck attachment 320, except that the at least one impact portion 448 at the .impact rearward facing impact surface 446 of the impact member 440 comprises a plurality of ball bearings 448 mounted within a CO-operating cylindrical recess 449 in the impact member 440, and the at least one roller member comprises a plurality of ball bearings 458 mounted within a co-operating cylindrical recess 459 in the actuator mechanism 450.
[00039] The ball bearings 448,458 are? each mounted within a co-operating cylindrical recess 449,459 having a diameter slightly greater than the diameter of the ball bearinqs 448,458, and a depth slightly IGSS than the diameter of the ball bearings 448,458, so that the ball bearings 448,458 project outwardly from the cooperating recesses 449,459 respectfully. Preferably, the ball bearings 448,458 are each mounted within the co-operating recesses 449,459 by means of a suitable grease type material, so as to help retain the bal] bearinqs 448,458 in place.
[00040] It has been found that ball bearings 448,458 having a diameter of about 5/16" are suitable, although other sizes of ball bearings 448,458 could also be used. It has also been found that
the ball bearings 448, 458 of about this size should protrude beyond the rearwardly facing surface 446 of the impact member 440 and the forwardly facing surface 456 of the actuator mechanism 450, as the case may be, by up to about 0.050", or even more, and preferably by about ϋ.U2b" / depending on the diameter of the ball bearings 448,458. Although the ball bearings 448 and the ball bearings 458 are shown to be the same diameter as each other, this is not absolutely necessary.
[00041] II has been round that with the hammer drill 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 International ElecLrotechnicai Commission IEC 60745 1:2001 (Hand Held Motor-Operated Electric Tools - Safety), and 60745 152001 (2003-01) (Hand Held Motor-qperaLed Electric Tools - Safety - particular requirements for driLls and impact drills), 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 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 rotational speed with a drill, and also for reduced wear of thy hammer drill 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 conventional drill without a load or hammer engagement, due to the friction of the steel teeth.
[00042] As can be understood from the above description and from the accompanying drawings, the present invention provides a hammer drill 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 can be operated at lower rotational speeds, all of which features are unknown in the prior art.
[00043] 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 of the present invention without departing from the spirit and scope of the accompanying claims.
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