This invention relates to trimmers and double acting trimming blade assemblies.
Trimmers that utilize double acting blade assemblies rely on a scissoring action whereby a pair of cutting blades having laterally projecting teeth move back and forth in opposite directions. The opposing reciprocation of the blades alternatively creates and closes openings between teeth. Hedge trimmers, for example, capture leaves and branches within the openings which are then severed as the openings close, trimming the hedge.
Existing trimmers typically include uniformly shaped and arranged teeth extending from opposite edges of the blades. Such blades can be efficient for removing large amounts of material. However, high precision can be difficult to achieve and tight spaces may not be easily negotiable with such blades.
Embodiments of the present invention are related to trimmers and pairs of blades for use with trimmers. In an embodiment, a pair of blades, one or both of which is adapted to be reciprocated along a longitudinal axis, comprises a first blade and a second blade, each blade having a proximal end, a distal end, a length extending between the proximal end and the distal end, and a cutting edge extending along a portion of the length to the distal end. The cutting edge of each blade includes a series of teeth. A width of each blade is stepwise reduced along the cutting edge to the distal end so that one or more teeth from the series of teeth has a cutting surface that is receded relative to a tooth from the series of teeth that is closer to the proximal end. The teeth of the series of teeth are uniformly oriented relative to the longitudinal axis. In a further embodiment, the teeth of the series of teeth of the first and second blade are generally uniform in size and shape. The teeth can be shaped as isosceles triangles, although in other embodiments the teeth can have some other shape.
The following description is of the best modes presently contemplated for practicing various embodiments of the present invention. The description is not to be taken in a limiting sense but is made merely for the purpose of describing the general principles of the invention. The scope of the invention should be ascertained with reference to the claims. In the description of the invention that follows, like numerals or reference designators will be used to refer to like parts or elements throughout. In addition, the first digit of a reference number identifies the embodiment in which the reference number first appears.
As shown, the first blade 102a and the second blade 102b extend from respective tangs 104a, 104b toward respective cutting edges with a generally uniform width. The cutting edges each begin at a kick 106a, 106b that flair the width of each blade 102a, 102b at one edge and not the opposite edge, which remains generally dull and does not perform any cutting. The kicks 106a, 106b are also generally dull and can help protect a hand holding the trimmer from the sharp edge of the most proximal tooth 120a of the cutting edge. The cutting edges of the first blade 102a and the second blade 102b are slightly offset, and the kick 106b of the second blade 102b is slightly smaller than the kick 106a of the first blade 102a. In other embodiments, the kicks 106a, 106b need not be shaped as shown. For example, the kicks can have an arcuate shape. In still other embodiments, the blades need not have kicks. In preferred embodiments, the width of the edge opposite the cutting edge does not flair out, so as to minify the overall width of the blade assembly. However, in other embodiments, the width of both edges can be increased. One of ordinary skill in the art, upon reflecting on the teachings contained herein, will appreciate the variety of shapes that the edges of the blades can have.
The blades 102a, 102b of the blade assembly can be held in close proximity by a rivet-in-slot arrangement. As shown in
The cutting edges of the blade assembly are sized and shaped to improve cutting precision and an ability to negotiate confined or narrow spaces. As shown, the width of the first blade 102a is at a maximum along the first four teeth 120a-126a from a proximal end of the cutting edge. The widths of the first blade 102a is then stepwise reduced along the cutting edge to the distal end so that the next four teeth 128a-134a have cutting surfaces that are receded relative to the teeth that are closer to the proximal end of the cutting edge. The points of the first four teeth 120a-126a are aligned parallel to an axis formed along the length of the blade 102a, while the next four teeth 128-134a are aligned at an angle F to the axis. The teeth 120a-134a of the cutting edge are substantially the same size and shape, and are oriented perpendicular to the axis formed along the length of the blade 102a. As shown, the teeth 120a-134a are shaped as isosceles triangles, although in other embodiments the teeth can have some other shape. The cutting edge of the second blade 102b, and the size, shape, and arrangement of the teeth of the second blade 102b are substantially the same as the first blade 102a. However, a portion 112 of the second blades can extend slightly past the cutting edge so that the blade lengths are the same.
The cutting edges of the blade assembly are longer than the cutting edges of the previous embodiment, and include more teeth. As shown, the width of the first blade 202a is at a maximum along the first five teeth 220a-228a from a proximal end of the cutting edge. The widths of the first blade 202a is then stepwise reduced along the cutting edge to the distal end so that the next five teeth 230a-238a have cutting surfaces that are receded relative to the teeth that are closer to the proximal end of the cutting edge. The points of the first five teeth 220a-228a are aligned parallel to an axis formed along the length of the blade 202a, while the next five teeth 230-238a are aligned at an angle Q to the axis. The teeth 220a-238a of the cutting edge are substantially the same size and shape, and are oriented perpendicular to the axis formed along the length of the blade 202a. As shown, the teeth 220a-238a are shaped as isosceles triangles, although in other embodiments the teeth can have some other shape. The cutting edge of the second blade 202b, and the size, shape, and arrangement of the teeth of the second blade 202b are substantially the same as the first blade 202a. A portion 212 of the second blades can extend slightly past the cutting edge so that the blade lengths are the same.
The cutting edge of the blade is longer than the cutting edges of the previous embodiments, and includes more teeth with different numbers of receded and aligned teeth. As shown, the width of the blade 302a is at a maximum along the first ten teeth 320a-338a from a proximal end of the cutting edge. The widths of the blade 302a is then stepwise reduced along the cutting edge to the distal end so that the next four teeth 340a-346a have cutting surfaces that are receded relative to the teeth that are closer to the proximal end of the cutting edge. The points of the first ten teeth 320a-338a are aligned parallel to an axis formed along the length of the blade 302a, while the next four teeth 340-346a are aligned at an angle to the axis. The teeth 320a-346a of the cutting edge are substantially the same size and shape, and are oriented perpendicular to the axis formed along the length of the blade 302a. As shown, the teeth 320a-346a are shaped as isosceles triangles, although in other embodiments the teeth can have some other shape.
In addition to the fourteen teeth along the cutting edge, the blade 302a further includes a puncturing tooth 312 extending perpendicular to the axis of the blade 302a, the puncturing tooth 312 having the shape of a right triangle.
Although in preferred embodiments, the cutting edge includes a width that is stepwise reduced with receded teeth; in other embodiments all of the teeth can be aligned.
The cutting edges of the blade assembly include ten teeth 420a-438a, 420b-438b. The points of the teeth 420a-438a, 420b-438b are aligned parallel to an axis formed along the length of the respective blades 402a, 402b. The teeth 420a-438a, 420b-438b of the cutting edge are substantially the same size and shape, and are oriented perpendicular to the axis formed along the length of the respective blades 402a, 402b. As shown, the teeth 420a-438a, 420b-438b are shaped as isosceles triangles, although in other embodiments the teeth can have some other shape. A portion 412 of the second blades can extend slightly past the cutting edge so that the blade lengths are the same.
The sets of cutting edges of the blade assembly each resemble the cutting edges from the embodiment of
The sets of cutting edges of the blade assembly each resemble the cutting edges from the embodiment of
The previous description of the preferred embodiments is provided to enable any person skilled in the art to make or use the embodiments of the present invention. While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.
Number | Name | Date | Kind |
---|---|---|---|
155855 | Burgess | Oct 1874 | A |
518204 | Bell | Apr 1894 | A |
547718 | Fletcher | Oct 1895 | A |
1115328 | Murran | Oct 1914 | A |
1354458 | Riggs | Sep 1920 | A |
1875125 | Oster et al. | Aug 1932 | A |
2080451 | Wilcox | May 1937 | A |
2277080 | Davis | Mar 1942 | A |
2322610 | Wilcox | Jun 1943 | A |
2651107 | Bartlett | Sep 1953 | A |
2840904 | Hutchins | Jul 1958 | A |
3372481 | Skinner | Mar 1968 | A |
3970912 | Hoffman | Jul 1976 | A |
4619045 | Mayer | Oct 1986 | A |
4711030 | Ruston et al. | Dec 1987 | A |
D298601 | Tsuji | Nov 1988 | S |
4827616 | Sistare | May 1989 | A |
D348184 | Neshat et al. | Jun 1994 | S |
5402576 | Kiyooka et al. | Apr 1995 | A |
5412873 | Gibson | May 1995 | A |
5473818 | Otsuka et al. | Dec 1995 | A |
5640837 | Ueyama | Jun 1997 | A |
6098288 | Miyagawa et al. | Aug 2000 | A |
6276060 | Faulstich et al. | Aug 2001 | B1 |
D469321 | Smith et al. | Jan 2003 | S |
7251896 | Khubani | Aug 2007 | B2 |
7581319 | Little et al. | Sep 2009 | B1 |
7757404 | Ouchi et al. | Jul 2010 | B2 |
8176637 | Fukutani et al. | May 2012 | B2 |
20050262695 | Ouchi et al. | Dec 2005 | A1 |
20070050991 | Mooney et al. | Mar 2007 | A1 |
20100299930 | Voorhorst et al. | Dec 2010 | A1 |
20110005081 | Ouchi et al. | Jan 2011 | A1 |
20120240409 | Inoue et al. | Sep 2012 | A1 |
Number | Date | Country | |
---|---|---|---|
20130125404 A1 | May 2013 | US |