1. Field
The present invention is generally related to chisels. More particularly, the application relates to chisels having an improved cutting blade.
2. Description of Related Art
Chisels typically include a blade with a sharp cutting edge and a handle. The handle has an end adapted to be struck by another tool, such as a hammer so that the sharp cutting edge can be used for carving, shaving, or cutting work pieces. In some chisels, a direction and/or angle for using the chisel can be limited to a position of the cutting edge and/or the location of the struck end relative to the striking edge.
One embodiment comprises a chisel having: a handle with a back end of the handle configured to be struck by a striking instrument; and an elongated blade joined with the handle. The blade includes a main body portion, a front beveled cutting edge portion at a forward end thereof, a beveled side cutting edge portion along a first longitudinal side of the blade, and a strike surface along a second longitudinal side of the blade opposite the first longitudinal side. The main body portion that narrows in thickness as it extends in a forward direction from a relatively rearward portion thereof towards the front beveled cutting edge portion, and that narrows in thickness as it extends in a lateral direction from the strike surface towards the beveled side cutting edge portion. The beveled side cutting edge portion has a surface that forms an angle with a surface of the main body portion.
Aspects of the present invention, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. In one embodiment of the invention, the structural components illustrated herein can be considered drawn to scale. It is to be 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. It shall also be appreciated that the features of one embodiment disclosed herein can be used in other embodiments disclosed herein. As used in the specification and in the claims, the singular form of “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.
Referring now more particularly to the drawings,
Chisel blade 10 comprises an elongate main body portion 14 that is connected with a shank portion 16. The main body portion 14 and shank portion 16 may be joined to each other or integrally formed together. The joining of the shank portion 16 and handle 12 form a hand-held chisel 100 that may be used to carve, shave, or cut work pieces made of wood, for example. In one embodiment, the handle 12 and shank may both be formed from the same material (such as steel), and may also be integrally formed.
In an embodiment, the chisel blade 10 includes a neck portion 42 that connects the main body portion 14 with the shank portion 16. Neck portion 42 may comprise a gradual slope formed by a reduction in its diameter from shank portion 16 towards body portion 14. Transition areas 48 and 50 may be formed at a juncture of shank portion 16 and neck portion 42, and neck portion 42 and main body portion 14, respectively, as indicated in
Chisel blade 10 includes an overall length dimension OL. As shown in
Chisel blade 10 has an overall width W, which also corresponds to a width of leading cutting edge portion 24. Overall width W is measured perpendicular to central longitudinal axis A-A from a first elongate side 20 on one longitudinal side of the blade 10 to a second, opposite elongate side 22 along another longitudinal side of the blade 10, as shown in
Main body portion 14 comprises a length L2 measured from top most portion of the blade 10 (i.e., front most cutting edge 44 of front beveled cutting edge portion 24, described further below) to transition area 50 at neck portion 42. In an embodiment, length L2 of the main body portion 14 is between about 4.0 and about 5.0 inches. In another embodiment, length L2 of the main body portion 14 is less than 4.0 inches. In another embodiment, length L2 of the main body portion 14 is greater than 5.0 inches.
Shank portion 16 comprises a length L3, measured from a bottom most surface 17 of chisel blade 10 to neck portion 42. In an embodiment, length L3 of shank portion 16 corresponds to a length of opening 13 in handle 12, for example. In an embodiment, length L3 of shank portion 16 is about 2.0 to about 3.0 inches. In another embodiment, length L3 of shank portion 16 is less than 2.0 inches. In yet another embodiment, length L3 of shank portion 16 is about 2.25±0.1 inches. Shank portion 16 may also comprise a dimension that corresponds to a size or width of the opening 13 in the handle 12 for receiving shank portion 16 therein. In an embodiment, shank portion 16 comprises a diameter D. In an embodiment, diameter D is between about 0.4 to about 0.6 inches.
Neck portion 42 comprises a length L4 measured from about transition area 48 at the juncture with shank portion 16 to about transition area 50 at the juncture with main body portion 14. In an embodiment, length L4 of neck portion 42 is between about 0.5 and about 1.5 inches. In another embodiment, length L4 of neck portion 42 is between about 0.8 to about 1.0 inches. Also, as previously noted, neck portion 42 may comprise a gradual slope which may be formed by a reduction in its diameter from shank portion 16 towards main body portion 14.
Referring now more specifically to working features of the chisel blade 10 shown in
Back portion 36 includes the transition area 50 between the neck portion 42 to the main body portion 14. As better shown in
As seen in
Front-most cutting edge 44 comprises a width that is substantially equal to width W of the chisel blade 10. In a non-limiting embodiment, front-most cutting edge 44 is about 1.0±0.1 inches wide. In one embodiment, back edge 46 may be formed at an angle α relative to front-most cutting edge 44. More specifically, back edge 46 may be formed at an angle α relative to an axis C-C that is perpendicular to longitudinal axis A-A and provided along front-most cutting edge 44 of front beveled cutting edge portion 24. In an embodiment, back edge 46 is formed at an angle α of about 10 degrees to about 20 degrees relative to axis C-C or front cutting edge 44. In an embodiment, the angle α is about 17±2 degrees relative to axis C-C or front cutting edge 44.
Additionally, a side view of the blade as shown in
In an embodiment, a length or distance L7 from front-most cutting edge 44 to back edge 46 is about 0.2 inches to 0.9 inches. In an embodiment, distance L7 is about 0.3 inches to 0.7 inches. In an embodiment, a distance L7 from front-most cutting edge 44 to back edge 46 is about 0.5±0.1 inches.
First elongate side 20 of the main body portion 14 comprises beveled side cutting edge portion 26. Beveled side cutting edge portion 26 may be used to chip, chop, chisel, or cut material. More specifically, as will become further evident, beveled side cutting edge portion 26 may be used to chisel material at a lateral or side angle relative to the longitudinal axis A-A of the blade 10, such as by striking an opposite striking surface 28 of blade 10.
Beveled side cutting edge portion 26 may optionally be provided substantially along an entire length of the first elongate side 20 of chisel blade 10. A top view of the chisel blade 10, as shown in
In a non-limiting embodiment, angled surface 27 may extend substantially along an entire length of first elongate side 20 of main body portion 14. In an embodiment, working side cutting edge 52 comprises a length between about 4.0 to 5.0 inches long. In one embodiment, back edge 54 may be formed at an angle σ relative to side cutting edge 52. More specifically, back edge 54 may be formed at an angle σ relative to an axis B that is parallel to longitudinal axis A-A and provided along working side cutting edge 52 of beveled side cutting edge portion 26. In an embodiment, the angle σ at which back edge 54 is formed relative to axis B or side cutting edge 52 is about 1 degree to about 5 degrees. In another embodiment, back edge 54 is formed at an angle σ of about 2±1 degrees relative to axis B or side cutting edge 52.
The angled surface 25 of front beveled cutting edge portion 24 may, in one embodiment, meet and/or intersect with angled surface 27 of beveled side cutting edge portion 26. At a juncture of the sharpened edges, an edge 31 may be formed.
Striking surface 28 is provided on the opposite, second elongate side 22 of the main body portion 14 of chisel blade 10. Striking surface 28 comprises a surface for impact with a tool (e.g., hammer, mallet) so that beveled side cutting edge portion 26 can be used to chisel materials at an angle with respect to central longitudinal axis A-A of the chisel.
Striking surface 28 comprises a thickness that is larger than a thickness of beveled side cutting edge portion 26. This allows for a larger surface area in which to strike chisel blade 10 on second elongate side 22 with a tool (e.g., so that beveled side cutting edge portion 26 can be used in a chopping operation). Accordingly, main body portion 14 narrows in thickness as it extends in a lateral direction from the striking surface 28 towards the beveled side cutting edge portion 26. In an embodiment, the variation in thickness of the main body portion 14 is formed by providing top surface 30 of the blade 10 at an angle with respect to bottom surface 32.
Further to varying the thickness of the main body 14 in a lateral direction (i.e., via the top surface 30 comprises a downward slope from second elongate side 22 to first elongate side 20), in accordance with an embodiment, a side view of the blade 10 as shown in
Accordingly, both the striking surface 28 and beveled side cutting edge portion 26 may have variable thicknesses in a longitudinal direction. Striking surface 28 may comprise a first thickness T adjacent back portion 36. Because the top surface 30 is configured to slope downwardly from relatively rearward portion 36 towards front portion 34 of blade 10, striking surface 28 may comprise a second thickness T2 at front portion 34, where T>T2. Also, beveled side cutting edge portion 26 may comprise a first thickness T3 adjacent back portion 36 of blade 10 and a second thickness T4 at front portion 34, where T3>T4. The thickness T, T2, T3, and T4 may vary based on both angles Δ and Θ at which top portion 30 slopes.
In an embodiment, beveled side cutting edge 26 may optionally include one or more teeth 38 along its length for cutting or sawing into materials. In the illustrated embodiment, four (4) teeth are shown. However, any number of teeth (including none) may be provided on beveled side cutting edge portion 26. The teeth 38 may be formed at any number of locations and in any grouping along the length of the chisel blade 10.
Because the chisel blade 10 is configured to have a top surface 30 that slopes downwardly at an angle in both a lateral direction (e.g., from striking surface 28 towards beveled side cutting edge portion 26) and in a longitudinal direction (e.g., from back portion 36 towards front portion 34), the chisel blade 10 may comprise a number of thicknesses along its length and width. The noted dimensions (lengths, angles, diameters, etc.) as described herein are not meant to be limiting.
When striking surface 28 receives an impact (e.g., from a hammer), force is transmitted through the main body portion 14 to at least the beveled side cutting edge portion 26. Additionally, front beveled cutting edge portion 24 may be used for chiseling materials. That is, when the end cap 18 of handle 12 receives an impact (e.g., from a hammer), force is transmitted through the main body portion 14 to at least the front beveled cutting edge portion 24. Thus, both striking surface 28 and end cap 18 can be considered to be driving engagement surfaces for using beveled side cutting edge portion 26 and front beveled cutting edge portion 24 for chiseling or cutting.
The materials, hardnesses, and methods of manufacturing chisel blade 10 should not be limited. In one embodiment, main body portion 14 is made of one or more materials. An exemplary embodiment would include body portion 14 made of carbon steel having a Rockwell Hardness (HRC) in the range of 35 to 60 HRC.
Additionally, it should be noted that any number of processes may be used on chisel blade 10. For example, in an embodiment, the chisel blade 10 may be heat treated. Moreover, chisel blade 10 may be formed such that particular parts of the blade are stronger and/or resistant to damage than others. In one embodiment, the entire chisel blade 10 is heat treated and bulk hardened to so that a majority of the main body portion 14 has a hardness of about 38 to about 44 HRC. In a non-limiting embodiment, at least a majority of front portion 34 (e.g., front beveled cutting edge portion 24, or chisel tip) is then locally hardened to a hardness of about 55 to about 58 HRC. In another embodiment, a majority of the main body portion 14 of the chisel blade 10 is hardened to a hardness of about 55 to about 58 HRC. In another non-limiting embodiment, a majority of striking surface edge 28 is then locally heat tempered to a hardness of about 38 to about 44 HRC. The chisel blade 10 may also comprise a combination of hardnesses. For example, in accordance with some embodiments, two thirds of the entire chisel blade 10 is hardened to a hardness of about 55 to about 58 HRC, and the striking surface edge 28 is locally tempered to a hardness of about 38 to about 44 HRC.
While the principles of the invention have been made clear in the illustrative embodiments set forth above, it will be apparent to those skilled in the art that various modifications may be made to the structure, arrangement, proportion, elements, materials, and components used in the practice of the invention.
It will thus be seen that the objects of this invention have been fully and effectively accomplished. It will be realized, however, that the foregoing preferred specific embodiments have been shown and described for the purpose of illustrating the functional and structural principles of this invention and are subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.