Not applicable
Not applicable
1. Field of the Background
The present invention relates generally to hammers with heads having a striking surface attached thereto, and more specifically, where the head and the striking surface may be different materials.
2. Description of the Background
As depicted in
Various striking tools have attempted to improve on the hammer shown in
In one example, a hatchet includes a head with a malleable body. A steel striking surface with a dowel is attached to the head by forcing the dowel into a hole in the head. The hole has a slightly smaller diameter than the dowel causing the striking surface to be firmly secured to the head without the use of a rivet or heat.
In another example, a hammer includes a head made of a soft metal, such as copper. To provide a hard face on the hammer, a shell of hard material, like steel, having a recess with a larger diameter at its bottom portion than its opening is secured to the head. The soft head has a cylindrical projection of uniform diameter that is equal to that of the opening of the shell. The projection of the head is inserted into the shell. By applying pressure to the shell, the soft metal of the head completely fills the hollow in the shell. Additional pressure secures the shell to the head more tightly.
In another example, a hammer has a head made of a hard material with a cylindrical socket with an undercut circumferential groove. A copper or other malleable material plug may be inserted into the socket to form a striking surface. The plug is secured in place by spreading into the undercut circumferential groove upon application of pressure. Continued use secures the plug more tightly. When the plug is worn out, it may be removed and replaced with a new plug.
A further example of a hammer with a striking surface attached to the head includes an impact tip with a tapered shank that is received within a tapered socket of the head. A shock absorbing washer surrounds the shank of the impact tip and is interposed between an annular surface of the impact tip that faces an annular surface of the head. The impact tip is permanently secured to the head.
Another example includes a hammer with a head made of a light weight metal, such as a titanium or titanium alloy, with a hard striking surface or working tip attached thereto by a threaded connector, welding, brazing, adhesives, or shrink fitting (heat treatment).
However, such prior striking tools often relied on heavy construction that added to the weight of the striking tool or used malleable metal heads or striking surfaces, which led to short-lived tools. Further, prior locking mechanisms, whether for permanent affixation of striking surfaces or that allowed striking surfaces to be replaced were not designed for long life. In addition, other connecting methods added significant expense either in terms of the costs for materials and equipment required for affixation and/or in the added steps or energy required to carry out such methods. There is a need, therefore, for light weight striking tools with durable striking surfaces attached economically and permanently that provide greater ease of use, prolonged tool life, and reduced manufacturing cost.
According to one aspect, a striking tool includes a handle with a first end and a second end, a head disposed on the second end and including a receiving surface, and a cap with a mounting surface opposite a striking surface. The cap is affixed to the head with a bushing disposed between the mounting surface and the receiving surface.
According to another aspect, a striking tool includes a handle with a first end and a second end, a head disposed on the second end and including a receiving surface. The head has a first hardness. The striking tool further includes a cap attached to the receiving surface of the head by a concave mounting surface opposite a striking surface. The cap has a second hardness greater than the first hardness. A permanent void space is disposed between an inner surface of the cap and the head.
According to another aspect, a striking tool includes a handle with a first end and a second end, a head disposed on the second end and comprising a receiving surface, a cap attached to the head and comprising a mounting surface, a length of engagement between the mounting surface and the receiving surface, a first perimeter of engagement measured around the receiving surface at a first point along the length of engagement distal from the cap, and a second perimeter of engagement measured around the receiving surface at a second point along the length of engagement proximal to the cap. A ratio of the length of engagement to the difference between the first perimeter of engagement and the second perimeter of engagement is greater than about 0.4.
According to a further aspect, a striking tool includes a handle with a first end and a second end, a head disposed on the second end and comprising a receiving surface, wherein the handle and the head are formed from a single piece of material, a cap attached to the head and comprising a mounting surface, a length of engagement between the mounting surface and the receiving surface, a first perimeter of engagement measured around the receiving surface at a first point along the length of engagement, and a second perimeter of engagement measured around the receiving surface at a second point along the length of engagement. A ratio of the length of engagement to the absolute value of the difference between the first perimeter of engagement and the second perimeter of engagement is greater than about 0.4.
Other aspects and advantages of the present invention will become apparent upon reading the following detailed description and upon reference to the drawings in which:
To overcome the deficiencies of the prior art, the present disclosure is directed to a striking tool 10 that adds to the concepts of
For example, in the embodiment of
In this embodiment, force generated by impact of the striking surface 34 is transferred through the cap 32 and distributed over the mounting surface 36 through the bushing 44 to the receiving surface 42. As a result, the mounting surface 36 and the receiving surface 42 may become more tightly associated through use of the striking tool 10, and the bushing 44 may deform to some degree causing an increase in its overall surface area. The increase in surface area of the bushing 44 is believed to increase the amount of friction between the mounting surface 36 and the receiving surface 42 over time and provide an ever stronger bond between the cap 32 and the head 18.
While not wishing to be bound by theory, it is believed that the attachment of the cap 32 as depicted in
If a tapered mounting surface 36 or bushing 44 surrounding the mounting surface is pressed into a cavity 38 in the neck 20, the vast majority of axial force used is directed outward generally perpendicularly to the receiving surface 42 or bearing surface of the cavity in the neck, and to a greater degree when the receiving surface is angle/tapered. The product of this force multiplied by the static coefficient of friction between the two materials of the cap 32 and head 18 and the area of engagement is the axial force required to remove the mounting surface 36 from the cavity 38 as well as the radial force required to rotate the mounting surface in the cavity.
The cap 32 will be under a bearing load since it will be under compression from all sides of the tapered cylinder (cavity 38) simultaneously. The material surrounding the cavity 38 in the neck 20 will be under a tensile load. As the tensile load exceeds the tensile strength of the material surrounding the cavity 38, the material deforms outwardly and thins around the mounting surface 36. This, in turn, leads to a reduced cross-section of the material around the cavity 38 further reducing the tensile strength of the material. If no additional force is applied, the frictional forces holding the mounting surface 36 against the receiving surface are diminished allowing for the undesirable separation of the cap 32 from the head 18. However, if additional force is applied, it is transmitted to the material having the weakened cross-sectional area around the cavity 38. As the material progressively thins, it cracks, ultimately leading to a relatively rapid failure of the striking tool 10 that can take place over the course of only a few blows of the striking tool.
Therefore, since the tensile strength will fail prior to the bearing strength of the material, it is preferred to use the stronger material having the higher tensile strength as the material that is under tensile load. Since it is desirable that the cap 32 be made of the harder, stronger material, it is then also preferred to have a cavity in the cap subjecting a softer material (e.g., aluminum alloy and the like) in the head 18 and neck 20 to the bearing load. When constructed in this manner, the frictional force holding the cap 32 onto the head 18 may increase with use overtime without the risk of failure of the striking tool 10.
When the cap 32 is affixed to the head 18 in this way with an appropriately sized bushing 44 or without a bushing, a void space 46 may be formed between an inner surface of the cap and the head that provides shock absorption when the striking tool 10 is used to strike an object. The void space 46 may be filled with any manner of shock absorbing materials including gas, foam, fabric, rubber, plastic, wood, malleable metal, and combinations thereof. In one embodiment, the void space 46 is permanent, such that throughout the useful lifetime of the striking tool 10, the void space never bottoms out.
The mounting surface 36 and the receiving surface 42 may each have a cylindrical shape or may be tapered. In
In one embodiment shown in
In an alternative embodiment, the first perimeter or circumference of engagement and the second perimeter or circumference of engagement may be equal.
Similarly, the bushing 44 may be configured to have a taper that may be complementary to that of either or both of the mounting surface 36 or the receiving surface 42 or may have a different configuration that still enables affixation of the cap 32 to the head 18. Further, the bushing 44 may be made of any material that allows for permanent affixation of the cap 32 to the head 18. Alternatively, the bushing 44 may allow removable affixation of the cap 32 to the head 18. The bushing 44 may be made of one or more metals, adhesives, polymers, plastics, and combinations thereof and be formed by one or more pieces of material. In one embodiment, the bushing 44 is made of single metal or metal alloy that is softer than that of the head 18 and the cap 32. Without wishing to be bound by theory, it is believed that using a softer material may provide greater manufacturing tolerance, that is, allow for dimensional variations in manufacturing of the bushing 44, cap 32 (mounting surface 36), and/or head 18 (receiving surface 42). In one embodiment, the bushing may have a hardness that is softer than at least one of the head 18 and the cap 32 or both the head and cap. In another embodiment, the bushing 44 may have the same hardness as at least one of the head material and the cap material or both the head and cap materials. Without wishing to be bound by theory, it is also contemplated that the bushing 44 be manufactured from a hardened material having a hardness equal to or greater than that of the mounting surface 36 and the receiving surface 42 when the components are precision ground or similarly shaped after forging, casting, and/or machining to form a precision mating surface. Further, when the head 18 and the cap 32 have precision mating surfaces, the bushing 44 may be optional.
In the embodiment shown in
In
In
Caps 32 contemplated herein may include any type of striking surface that is associated with a striking tool 10, as known in the art, and may vary by size and shape, as desired. For example, in addition to the flat striking surfaces 34 shown in the figures, it is further contemplated that caps 32 may include a cutting edge (S), such as when the cap is a bit of an axe or a hatchet (
In other embodiments shown in
While the handle 14 and head 18 of the striking tools 10 in
In another embodiment, the handle 14 of the striking tools 10 of
In a further embodiment, the striking tools 10 of
The handle 14 and/or head 18 may be formed by casting, fine blanking, plasma cutting, electrochemical machining, electrical discharge machining, metal injection molding, forging, rolling, extruding, milling, molding, die cutting, a computer numeric controlled machining operation, additive manufacturing, such as 3D printing, selective laser sintering, fused deposition modeling, or direct metal laser sintering or any other machining or manufacturing process suitable for a particular material incorporated into the striking tool.
The overlay 60 may be formed by extruding, molding, laminating, and any other process known in the art.
The grip 12 may be made of any suitable material or combinations of material, such as leather, plastic, rubber, wood, foam, an elastomeric material, and a vibration reducing grip material. In one embodiment, the grip material may have a Shore A durometer of from about 40 to about 80, or about 50 to about 75, or about 63 to about 73, or about 60, or about 65, or about 68. Grip materials contemplated for use also include those disclosed in U.S. Pat. No. 6,465,535.
Caps 32 contemplated herein may be formed of any suitable material or combinations of material and have any shape. For example, the cap 32 may be formed of steel or other metal, plastic, rubber, and combinations thereof, such as, for example, a rubber- or plastic-tipped cap with a metal or plastic base. In one embodiment, the cap 32 has a hardness greater than that of the head 18. In another embodiment, the cap 32 has a hardness equal to or less than the head 18.
One embodiment of striking tool 10 contemplated herein includes a handle 14 and head 18 made from a single piece of titanium, titanium alloy, or aluminum and one or more caps 32 made of steel affixed to the head by zero, one, or more bushings 44.
Another embodiment of striking tool 10 includes a handle 14 that extends at least part way through the separately formed head 18 and is secured thereto by means known in the art, such as a friction fit. In this embodiment, the handle 14 may be a plastic material or other light weight material and the head may be a light weight metal, such as aluminum, titanium, or an alloy thereof. One or more caps 32 made of steel may be affixed to the head 18 as described herein above.
In another embodiment, a striking tool 10 may have the handle 14 formed of a sheet metal to which the head 18 is attached, for example, by welding or other suitable manner. A striking cap 32 may be subsequently affixed to the head 18 as described herein above.
In a further embodiment, the striking tool 10 may be a pry bar (not shown) or a demolition tool that can be used for the demolition of construction materials or other materials with a cap attached to one end thereof to provide a striking surface 34 thereto. Examples of such tools are described in U.S. Pat. No. 6,629,684.
In a further embodiment, the striking tool 10 may incorporate additional features, such as a side nail puller or a lumber manipulating feature, such as described in U.S. Pat. No. 5,850,650.
Specific striking tools 10 contemplated herein include, for example, a nail hammer, an axe, a hatchet, a splitting tool, a welding chipping hammer, a drilling hammer, a sledge hammer, a tinner's hammer, an engineer's hammer, a cross peen hammer, a ball peen hammer, a lineman's hammer, a mason's hammer, a drywall hammer, a roofing hammer, a rock pick, an adze, a deadblow hammer, a tack hammer, a soft faced hammer, or any other tool used to strike a surface.
In one or more embodiments, the structural components illustrated herein are drawn to scale.
Striking tools with one or more striking surfaces attached thereto are described herein. Such striking tools combine the advantage of being able to be light weight while providing a striking surface of sufficient hardness and durability.
Numerous modifications will be apparent to those skilled in the art in view of the foregoing description. Accordingly, this description is to be construed as illustrative only and is presented for the purpose of enabling those skilled in the art to make and use the invention and to teach the best mode of carrying out same. The exclusive rights to all modifications which come within the scope of the application are reserved. All patents and publications are incorporated by reference. All values and ratios disclosed herein may vary by ±10%, ±20%, or ±40%.
This application claims the benefit of U.S. Provisional Application Ser. No. 61/949,838, filed Mar. 7, 2014, which is incorporated herein by reference.
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