Patent Application
20100252290
The present invention relates to hammer drills mechanisms, and more particularly to adjustable amplitude hammer drill mechanisms.
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. An impact receiving member is secured to the rotations spindle. A hammer member engages the impact receiving member as the spindle rotates, so as to provide the hammer drill function. Although hammer drills do work, they present a limitation in that in most hammer drills the impact created by the engagement of the hammer member and the receiving member is not adjustable.
One such example of an adjustable hammer drill can be found in United States Published Patent Application 2007/0039747, published Feb. 22, 2007, to Stirm, which discloses a hammer drill that includes a housing; a motor mounted within the housing; and a tool holder rotatably mounted on the house for holding a cutting tool. A striker is mounted in a freely slideable manner within the housing, for repetitively striking an end of a cutting tool when a cutting tool is held by the tool holder. The striker is reciprocatingly driven by the motor, when the motor is activated, via a drive mechanism. The drive mechanism comprises a pivoting drive arm pivotally mounted within the housing at one end and which is drivingly connected to the striker; a pivotal drive mechanism connected to the pivoting drive arm and which converts a rotary movement generated by the motor into an oscillating pivotal movement of the pivoting drive arm. The amplitude of the oscillations of the pivoting drive arm can be adjusted.
It is an object of the present invention to provide an adjustable hammer drill mechanism.
It is a further object of the present invention to provide an adjustable hammer drill mechanism that is inexpensive to manufacture.
It is yet a further object of the present invention to provide an adjustable hammer drill mechanism that can be used in an attachment for a drill.
It is yet a further object of the present invention to provide an adjustable hammer drill mechanism that can be used in a drill.
In accordance with one aspect of the present invention there is disclosed a novel adjustable amplitude hammer drill mechanism comprising a main shaft having a forward drill chuck end portion and a rearward shank portion, and defining a longitudinal axis. An impact receiving means is mounted in fixed relation on the main shaft for rotation therewith. A selectively operable longitudinal-hammer means is mounted on the main shaft for free rotation of the main shaft with respect to the longitudinal-hammer means and for operative engagement with the impact receiving means. Rotation of the main shaft and impact receiving means about the longitudinal axis when the longitudinal-hammer means is in force transmitting engagement with the impact receiving means, causes the longitudinal-hammer means 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. There is also an amplitude adjustment means for mounting the selectively operable longitudinal-hammer means in the operative engagement with the impact receiving means.
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.
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:
Referring to
Reference will now be made to
The adjustable amplitude hammer drill mechanism 120 comprises a main shaft 130 having a threaded forward drill chuck end portion 132, an intermediate shank portion 133, and a rearward shank portion 134. The main shaft 130 defines a longitudinal axis “L” about which the main shaft 130 rotates. The first preferred embodiment adjustable amplitude hammer drill mechanism 120 comprises an attachment and the main shaft 130 is engageable in a rotatable chuck of a conventional drill (not specifically shown).
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
An impact receiving means 140 comprises a main body portion 142, a forwardly facing surface 145, a rearward facing surface 146 and at least one impact portion. In the first preferred embodiment, as illustrated, the at least one impact portion comprises a plurality of ball bearings 149. Alternatively, it is contemplated that other types of impact portions could be used. As illustrated, the ball bearings 149 are substantially evenly spaced around the rearwardly facing surface 146 of the impact receiving means 140 about the longitudinal axis “L”.
The impact receiving means 140 is mounted in fixed relation on the main shaft 130 for rotation therewith, and projects radially outwardly from the intermediate shank portion 133. The impact receiving means 140 is threadibly engaged on the intermediate shank portion 133 the main shaft 130. The threads of the co-operating threaded forward portion 134 of the forward drill chuck end portion 132 of the main shaft 130 co-operatingly aligned with each other such that the impact receiving means 140 can be threadibly engaged from the forward drill chuck end portion 132 to the intermediate shank portion 133.
Alternatively, the rearward facing impact surface 146 may be integrally formed on the main body portion 142.
A selectively opeable longitudinal-hammer means 150 comprises a main body member 152 and a forwardly facing surface 156. The longitudinal-hammer means 150 is mounted on the main shaft 130, mostly at the rearward shank portion 134 rearwardly of the impact receiving means 140, for free rotation about the main shaft 130 with respect to the longitudinal-hammer means 150, and for operative engagement with the impact receiving means 140. In the preferred embodiment, as illustrated, the longitudinal-hammer means 150 is retained on the rearward shank portion 134 by means of a “C”-clip 158 securely engaged in an annular slot 159 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 receiving means 140 must be of sufficient length to be securely received in the bit chuck of a conventional electric drill.
In the first preferred embodiment, as illustrated, the selectively operable longitudinal-hammer means 150 comprises a hammer ball bearing assembly 150 having a plurality of forwardly projecting ball bearings 160. The plurality of ball bearings 160 in the hammer ball bearing assembly 150 are disposed in evenly radially spaced relation around the longitudinal axis “L”.
The impact receiving means 140 comprises an impact ball bearing assembly having a plurality of rearwardly projecting ball bearings 149. The plurality of ball bearings 149 in the impact ball bearing assembly 140 are disposed in evenly radially spaced relation around the longitudinal axis “L”.
Preferably, the number of ball bearings 160 in the hammer ball bearing assembly 150 is equal to the number of ball bearings 149 in the impact ball bearing assembly 140.
Rotation of the main shaft 130 and impact receiving means 140 about the longitudinal axis “L” when the longitudinal-hammer means 150 is in force transmitting engagement with the impact receiving means 140, causes the longitudinal-hammer means 150 to move in a slight reciprocating motion, as shown in
The height, radius of curvature, shape and number of ball bearings 160 and the ball bearings 149 will affect the frequency and amplitude of the impacts of the ball bearings 160 on the ball bearings 149.
The first preferred embodiment of the adjustable amplitude hammer drill mechanism 120 further comprises an amplitude adjustment means, as indicated by the general reference numeral 170, for mounting the selectively operable longitudinal-hammer means 150 in the operative engagement with the impact receiving means 140. The amplitude adjustment means 170 comprises a carrier member 171 for the selectively operable longitudinal-hammer means 150 and a receiving member 172 for the impact receiving means 140, and wherein the carrier member 171 is mounted on the receiving member 172 for movement along the longitudinal axis “L” between a plurality of engagement positions as can be seen in
Reference will now be made to
The first preferred embodiment of the adjustable amplitude hammer drill mechanism 120 further comprises a locking collar 180 threadibly engaged on one of the carrier member 171 and the receiving member 172. More specifically, the locking collar 180 is threadibly engaged on the carrier member 171.
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 ball bearings 160 of the selectively operable longitudinal-hammer means 150, on the ball bearings 149 of the impact receiving means 140.
More importantly, it has been found that with the adjustable amplitude hammer drill mechanism 120 of the present invention, there is reduced friction, reduced heat build up, reduced wear and improved drilling performance compared with non-adjustable conventional hammer drills, when performing functions where reduced impact is sufficient. 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 ball bearings 160 and the impact receiving means 140. Accordingly, the rotational energy is directed to the actual longitudinal vibration, and not to losses due to friction and heat.
Reference will now be made to
As can be understood from the above description and from the accompanying drawings, the present invention provides a adjustable amplitude hammer drill mechanism 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 adjustable amplitude hammer drill mechanism can be operated at lower rotational speeds, all of which features are unknown in the prior art.
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 adjustable amplitude hammer drill mechanism of the present invention without departing from the spirit and scope of the accompanying claims.
