The present invention relates to scissors or shears and more specifically to agricultural scissors having canted blades.
In horticulture, viticulture, and other related agricultural activities, pruning plants is necessary to promote advantageous characteristics of the plant. For example, fruit trees are pruned to promote annual fruit-production of tasty, storable, transportable, and healthy fruit, to control growth, remove dead or diseased wood, and stimulate the formation of flowers and fruit buds. Pruning often means cutting branches back, sometimes removing smaller limbs entirely. It may also mean the removal of young shoots, buds, and leaves.
A particularly common approach to pruning small branches, new growth, and young shoots involves clipping with a small scissors or shears. However, due to sap and other debris that results during this process, the scissor or shear blades become dirty, sticky, and after about 10-minutes of rapid pruning, the blades are not suitable for cutting, and require a cleaning to remove this detritus from the blades. This results in lost productivity.
Therefore, there is a need for a scissors or shears that reduce or eliminate the build-up of detritus on the blade during a pruning operation.
Possible embodiments will now be described with reference to the drawings and those skilled in the art will understand that alternative configurations and combinations of components may be substituted without subtracting from the invention. Also, in some figures certain components are omitted to more clearly illustrate the invention.
The present invention contemplates a pair of pruning shears or scissors that has a pair of cooperating blades. The pair of cooperating blades differs from the prevalent teaching in the art. A prior art pair of scissors, see
This large flat area of the cutting edge E is very effective at cutting or sheering thin material. However, as the size of the object being cut increases, this flat edge E becomes a hindrance. To counter this, the prior art teaches curved blades. The curved blades also present a flat cutting edge, however the cut zone changes as the two curved blades move toward each other, this has the affect of reducing the friction on the flat edge.
However, in each of these aforementioned prior art teaching, a flat, relatively wide, blade cutting edge is used, and this blade cutting edge becomes covered in sap or other detritus from the material being cut, which necessitates a periodic cleaning. In large-scale nursery environments, or in commercial fruit farming, for example, this periodic cleaning results in a significant loss in productivity.
The present invention contemplates cooperating blades that have a compound taper on each blade. This compound taper produces a visible gap 26 between the blades, see
Also referring to
Specifically referencing
However, the cutting face 42 gives way immediately to a first vertical taper feature 46 that terminates at a bottom 48 of each blade. (The two cooperating blades 24 and 22 are mirror images and symmetric with respect to the other). A second taper runs parallel to an imaginary axis that extends perpendicular to the page in the drawing of
The first taper, along the shorter axis creates about a 1-45 degree taper, but preferably about 5-degrees to about 16-degrees of taper from vertical as measured from a 90-degree vertical line (0-degrees). The second taper, running along a long axis of the blade, creates about from about 1-30 degrees of taper, but preferably 15 degrees.
In yet another preferred embodiment, the present invention provides a scissors or shears 80 that combines the self-cleaning, narrow cut, and precise cut features of a thin wire with the robustness, toughness, and durability of a conventional scissors or shears. To achieve this, the cooperating cutting faces 82 of the first and second blade (22 and 24, respectively) are flat faces that are very narrow in width 84.
Also, the surface of the cutting face defines a plane referred to as the cutting plane.
The leading face 90 arranged somewhat perpendicular, although this is not necessarily a 90-degree angle and can vary from about 75-degrees to about 120-degrees, for example. A common edge between the leading face 90 and the cutting face 82 is the cutting edge 86. A common edge between the cutting face 82 and the trailing face 92 is the trailing edge 88. The cutting face is therefore the surface defined between the cutting edge 86 and the substantially parallel trailing edge 88 from the tip 12 to an intermediate position 52.
The trailing face 92 extends from the trailing edge and extending at a tip angle substantially from 70-degrees to 90-degrees relative to the cutting plane. Or expressed differently, from a vertical reference line V (see, for example,
The cutting face 82 is preferably about 0.6-mm to about 0.7-mm but a range of less than 0.1 mm (approximating a thin, strong wire) to approximately 1.0-mm would work and may only be limited by the type of manufacturing process used (i.e, grinding, or milling, or molding powder metal). The overall blade thickness 90 is preferably about 2.0-mm to about 3.0-mm. Thus, the preferred ratio of cutting surface to blade thickness is from about 1:2.875 to about 1:5 and more preferably about 1:1.333 to 1:1.4.
The taper on the trailing surface is ideally 0-degrees (impossible) to as small as possible (from vertical—want it to be like a wire) up to a 20-degree, with a preferred range between 3-degrees to 16-degrees.
In one contemplated embodiment, the scissors or shears are made from powdered metal with a lubricant pre-impregnated during the formation of the blades.
Although the invention has been particularly shown and described with reference to certain embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the spirit and scope of the invention.
The present invention, being filed as a Patent Cooperation Treaty application, claims benefit for all purposes, including benefit under 35 USC Section 119(e), of U.S. Provisional Patent Application No. ______ filed on 21 Dec. 2012 entitled “Improved Scissors” by the common inventor Owen Papworth.
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/US13/76280 | 12/18/2013 | WO | 00 |
Number | Date | Country | |
---|---|---|---|
61740843 | Dec 2012 | US |