Patent Application
20080210059
The present invention is in the area of hand-held striking tools, such as hammers, and pertains more specifically to lightweight hammers.
Hand-held striking tools, such as claw hammers, have been used for a variety of tasks for centuries. A hammer is basically a force amplifier that works by converting kinetic energy into mechanical work. Claw hammers typically weigh from 7 to 32 ounces, and are used for driving a target into a substrate, such as a nail into wood. The claw portion of the claw hammer also can be used to remove a target, such as a nail, or for ripping apart a substrate, such as wood or pieces of wood.
This type of hammer works as a third-class lever, with the fulcrum or pivot point being the wrist of the user, and the lever arm being the length of the hammer handle. The head, at a distance of the handle from the fulcrum, moves faster than the user's wrist, and this increased speed factored with the weight of the hammer's head and gravity has typically provided the force for driving the target into a substrate.
In the swing that precedes each hammer blow, a certain amount of kinetic energy gets stored in the hammer's head. When the hammer strikes its target, the head gets stopped by an opposite force coming from the target, for example a nail being driven into a piece of wood, which is equal and opposite to the force applied by the head to the target.
The amount of kinetic energy (KE) delivered to the target by the hammer-blow is equivalent to the mass of the head (m) times the square of the head's speed (v2) at the time of impact, or KE=0.5·m·v2. Increasing the speed of the hammer's head when it strikes a target exponentially increases the kinetic energy delivered to the target, thereby increasing the amount of work done with each strike of the hammer.
One way to increase the speed of the hammer's head is to increase the length of the hammer's handle. However, it is typically more difficult to accurately squarely hit a nail with a longer handled than a shorter handled hammer. Using a longer hammer may also be awkward or impossible in close spaces.
Another way to increase the hammer head's speed is to lighten the weight of the hammer itself, thereby increasing the potential speed with which a user can swing the hammer. Such a lighter hammer can then be swung faster through the arc defined by the length of the hammer's handle rotating about the fulcrum, which is typically a user's wrist.
Prior art has introduced light weight materials into the heads and handles of hammers to increase hammer speed. The drawbacks of many such materials include malleability, high cost, brittleness, tempering, vibration transmitted to the hand of the user and overall lack of durability.
The present invention comprises graphite and titanium regions in the handle that provide for flexibility and an increased strength to weight ratio.
When a hammer's handle has an increased strength to weight ratio, the weight of the head can be reduced somewhat, but the invention maintains the “head-weight” that carpenters are used to. While graphite alone is lightweight, it must be protected with titanium strike surfaces below the head of the hammer and also at the “butt” end of the handle, which is sometimes used as a striking surface. It is the object of the invention to provide a lightweight yet durable hammer that allows the user to increase the work performed by each hammer blow due to the lightness of weight of the hammer itself, and more particularly due to the strength to weight ratio of the hammer's handle.
It is a further object of the invention to provide a hammer that does not unpleasantly vibrate in the hand of the user, and that will neither dent nor crack under normal use, including when the user mis-strikes a surface and the blow lands on the handle of the hammer instead of the striking surface of the hammer's head.
It is a still further object of the invention to provide these qualities in a relatively inexpensive hammer.
It is a still further object of the invention to provide a method of assembling or manufacturing said hammer.
According to the invention, the hammer has a head made of striking grade steel. In one embodiment, the head of hammer has a claw end and a striking head. In one embodiment, the handle comprises a 6-4 titanium hand grip and over strike plate insert in the handle and under the head. The head has an eye for accommodating a handle which in an embodiment is made of a graphite titanium composite comprising from about 60 to 65% graphite by weight and from about 35 to 45% titanium.
Also disclosed is a method of manufacturing the device of the disclosure comprising using one or more bladder compressed carbon fiber processes to anneal the graphite, titanium and steel components of the hammer.
As illustrated in
The head 20 comprises impact grade steel, and the handle 30 comprises a graphite titanium composite. In one embodiment, the handle comprises a graphite titanium and fiberglass composite. In still another embodiment, the handle 30 of the device 10 comprises a graphite titanium fiberglass and foam handle 20.
While many types of titanium can be used in the invention, at least one preferred embodiment comprises 6-4 titanium. Such 6-4 titanium may also be referred to as “grade 5” titanium, comprises a tensile strength of 130,000 psi, and comprises approximately 90 percent titanium, 6 percent aluminum, and 4 percent vanadium. However, other grades and alloys of titanium with slightly different properties may be used.
A titanium overstrike plate 39 runs the length of the handle 30 and wraps around the butt end 36 as the butt end 36 may sometimes be used as a striking surface. The overstrike plate 39 improves strength in the hammer overall by providing at least a single piece of titanium that runs the length of the handle 30 and into the head 20 of the hammer, to which the handle 30 is permanently affixed. Further, the titanium overstrike plate 39 protects the handle's integrity by resisting torque and by providing an overstrike surface to deflect mis-strikes of the hammer in which the head surface does not cleanly contact the target of the hammer's head. Still further, the overstrike plate 39 reduces vibrations transmitted from the surface struck by the hammer to the user's hand and arm.
In one embodiment of the disclosed device 10, as illustrated in
The graphite of the device may be any type of carbon fiber. In a preferred embodiment, the carbon fiber used is standard elastic modulus type fiber (2.4-5.0 GPa tensile strength and 200-280 GPa tensile elastic modulus) or intermediate elastic modulus type fiber (3.5-7.0 GPa tensile strength and 280-350 GPa tensile elastic modulus). However, high elastic modulus fiber (2.4-5.0 GPa tensile strength and 350-600 GPa tensile elastic modulus), while typically more expensive, may also be used to good effect. The carbon fiber is currently available through Toray and Mitsubishi.
The handle 30 of the disclosed device comprises a graphite titanium composition bonded together during a bladder compressed carbon fiber process. After undergoing the bonding method, disclosed below, the graphite bonds with the titanium overstrike plate 39 and the head 20 to form a hollow shell or layer of carbon fiber. In one embodiment, that hollow shell will be filled with foam to create a foam core 38.
In one embodiment, the handle 30 comprises a graphite titanium composite comprising from about 60 to 75% graphite by weight and from about 25 to 35% titanium. In another embodiment, the handle 30 comprises a graphite, fiberglass and titanium composite comprising from about 40 to 55% graphite by weight, about 20-30% fiberglass by weight and from about 25 to 35% titanium by weight. In still another embodiment, the handle comprises a graphite, fiberglass, a medium density cellulose foam and titanium composite comprising from about 35 to 45% graphite by weight, about 25 to 35% fiberglass by weight, about 15 to 25% foam by weight and from about 25 to 35% titanium by weight.
The graphite is bonded to the titanium and other composite components during a bladder compressed molding process. A negative mold is created of the entire device of the disclosure, including the head 20. In one of the preferred embodiments, graphite fibers comprising a graphite cloth are layered onto a prepared mold section according to the direction of the carbon fibers. The number of layers of carbon cloth corresponds to the desired strength needed at that position of the hammer's handle 30.
In one embodiment, carbon fibers embedded in the handle 30 of the disclosed device 10 run perpendicular or parallel to the longitudinal axis of the handle 30 or to the width of the head 20 of the device of the disclosure. In another embodiment, about 50% of the cloth's carbon fibers run parallel to the axis defined by the head A but perpendicularly to the axis defined by the handle B and about 50% run parallel to the axis defined by the handle B but perpendicularly to the axis defined by the head A.
As illustrated but not to scale in
The use of graphite and titanium, with or without the other fiberglass and foam components, provides a lightweight, strong handle that reduces the vibration transmitted from the hammer's head to the hand and arm of a user. Use of fiberglass decreases cost of production. Use of a foam core 38 further strengthens the integrity of the handle, and therefore of the device of the disclosure itself, and also further reduces vibration and impact felt by a user during use of the disclosed device. In one embodiment of the device disclosed, a medium density cellulose foam is used.
The titanium overstrike plate 39 of the handle, as illustrated in
After molding has been completed, a plastic overlayer is added to the entire device to protect the device 10 from disfiguration.
The compression/bladder mold requires all of the elements of the device 10 including its head 20, typically comprised of impact grade steel, the overstrike plate and hand grip of titanium 39, and the handle 30 to be molded together as a single unit. Additionally, as illustrated in
Also disclosed is a method of manufacturing the disclosed device. That method comprises constructing a handle 30 comprising a graphite titanium composite and a titanium overstrike plate 39; constructing a striking grade steel head 20; and joining the striking head 20 to the handle 30.
The graphite used in the method may comprise carbon fibers or carbon fibers woven into a cloth. The fibers of the cloth may be arranged perpendicularly.
The graphite is bonded to the titanium used in the method by heating the fibers in a compression-bladder mold with the titanium. The hammer's steel head 20 is also permanently attached to the handle 30 during this molding step.
In another embodiment of the method of the disclosure, the method of manufacturing the disclosed device comprises:
This application claims priority from U.S. Provisional Application 60/887,322 filed Jan. 30, 2007.
| Number | Date | Country | |
|---|---|---|---|
| 60887322 | Jan 2007 | US |
