Earth working – Guided by walking attendant; supported – propelled – or held... – Hand tool
Reexamination Certificate
2000-10-10
2002-07-02
Batson, Victor (Department: 3671)
Earth working
Guided by walking attendant; supported, propelled, or held...
Hand tool
C007S158000
Reexamination Certificate
active
06412569
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Field of the Invention
The present invention relates to tools and implements such as hoes of the type which are typically provided with a long handle for grasping and manipulation by an individual person. More particularly, the invention relates to an improved concrete mixing hoe which facilitates the mixing of dry concrete pre-mix with water to form a viscous slurry suitable for pouring into a construction form or other such structure construction applications.
B. Description of Background Art
Dry concrete “pre-mix” consists of a dry mixture of Portland cement ground to a very fine power, sand, and gravel of a particular size range (aggregate). To prepare the dry concrete pre-mix for use in construction projects, a pre-determined volume of water is added to the dry pre-mix, and thoroughly mixed with the water to form a thick, viscous slurry which may then be poured into formworks at a construction site. The water chemically reacts with the constituents of the Portland cement, typically anhydrous tricalcium silicate, tricalcium aluminate, dicalcium silicate and tetracalcium aluminoferrite, to form a solid gel of needle-like crystals that comprise an interlocking framework which binds the aggregate and sand particles. When these reactions have been driven to completion, in a process referred to as curing, the concrete slurry is transmitted into a substantially strong, stone-like solid consisting of a matrix of Portland cement crystals interspersed with aggregates and sand particles.
The strength, durability and appearance of finished or cured concrete depends strongly on the thoroughness with which the pre-mix ingredients and water are mixed prior to pouring the concrete slurry. Therefore, most concrete is mixed by a machine, either by a motor driven drum at a work site or in central batching and mixing plants, with the fresh concrete being taken to a job site in a revolving drum mounted on a ready-mix truck. However, small batches of concrete are mixed by hand on an increasingly frequent basis, by homeowners, handymen and do-it-yourselfers. For these uses, building supply stores and similar establishments sell dry concrete pre-mix in paper bags, typically containing 60 or 90 pounds of material.
A customary method for utilizing individual bags of dry concrete pre-mix for small jobs includes first pouring a pre-determined quantity of water into a mixing container such as a wheelbarrow or shallow rectangular mixing tray. Next, a bag of dry concrete pre-mix is opened, and the contents of the bag dumped into the mixing container, on top of the water. The water and dry concrete pre-mix, the latter consisting of finely powdered Portland cement, sand, and aggregate, the latter usually consists of gravel of a particular size range, are then mechanically worked to thoroughly mix all four component ingredients. The most commonly used method for mixing small batches of concrete consists of repeatedly inserting the blade of a long handled implement such as a hoe into the material in the mixing container, and drawing the hoe repeatedly through the material to intermingle dry concrete pre-mix ingredients with water in the container.
Existing hoes used for hand mixing concrete have a construction similar to that of common long-handled garden or agricultural hoes. One type of hoe which is widely marketed and used for mixing concrete is substantially similar in construction to the Plasterers Hoe disclosed in Canfield, U.S. Pat. No. 317,502, patented on May 12, 1885. That hoe has a generally rectangularty-shaped, laterally elongated blade, the central portion of which is reinforced by a rib which is a forward extending, thickened portion of a tang and which is attached to the front of the blade. The blade is provided with a pair of identical circular perforations or apertures laterally spaced apart and equidistant from a vertical plane passing centrally through the rib. The upper edge of the blade has a pair of laterally spaced apart, arcuately curved convex protrusions concentric with the two apertures through the blade.
The intended function of Canfield's hoe is to mix dry plaster, a homogeneous material consisting essentially of powdered calcium sulphate (Gypsum), with water to form a viscous paste suitable for application to structure wall lathing of buildings, and similar such uses. However, as described above, concrete pre-mix is a heterogeneous, multi-phase conglomeration of Portland cement powder, sand, and gravel, all of which must be thoroughly intermixed with water to prepare the concrete for pouring. Therefore, while presently used concrete mixing hoes provided with a pair of laterally spaced apart circular holes through the blade seem to permit the hoe blade to be more readily drawn through a vicious multi-phase mixture of water and dry concrete pre-mix, mixing concrete with existing hoes of this type is still a strenuous, tedious task.
Subsequent to Canfield's disclosure, a number of U.S. patents have issued for hoes intended to mix mortar, or perform agricultural tasks. These include:
Dickson, U.S. Pat. No. 565,379, Aug. 4, 1896, Mortar Hoe: Discloses a mortar hoe having an improved blade intended to cut and mix mortar finer, more uniformly and with greater ease then common mortar hoes. The blade has through its thickness pairs of vertically elongated slots located on each side of the vertical center of the blade, and a pair of horizontally elongated slots equidistant from the vertical center and extending over the vertical slots. The upper edge of the blade is arcuately curved to form a pair of convex humps spaced laterally apart and equidistant from the vertical center and, the humps form therebetween a concavely curved groove or trough.
Anderson, U.S. Pat. No. 865,150, Sep. 3, 1907, Mortar Mixer Or Hoe: Discloses a mortar hoe having a generally rectangularly-shaped blade provided in one embodiment with two rows of vertically elongated, generally rectangularly-shaped perforations, and in another embodiment with three rows of generally square-shaped perforations.
Holmes, U.S. Pat. No. 1,127,440, Feb. 9, 1915, Mortar Hoe: Discloses a mortar hoe having a generally rectangularly-shaped blade provided with pairs of vertically elongated perforations located equidistant from the vertical center line of the blade, each of the perforations formed from a vane angled outwardly from the plane of the blade.
Birn, U.S. Pat. No. 1,167,971, Jan. 11, 1916, Mixing Hoe: Discloses a mixing hoe having a generally rectangularly-shaped blade comprising an open frame provided with laterally spaced apart, vertically elongated, rectangularly-shaped apertures each bordered by a vertically elongated mixing bar having a diamond cross section and having longitudinally extending sharp edge portions disposed forwardly and rearwardly with respect to the plane of the blade.
Beymer, U.S. Pat. No. 1,185,581, May 30, 1916, Garden Implement: Discloses a garden implement comprising a hoeing blade having two or more meeting edges sharpened for cutting and an angular shank member having one of its ends connected to the upper end of the blade and its other end projecting rearwardly in a line intersecting the blade at the axis of the working resistance.
Rhomberg, U.S. Pat. No. 1,286,779, Dec. 3, 1918, Hoe: Discloses a garden hoe including a handle and a substantially flat blade having horizontal sets of forwardly and rearwardly extending cutters folded out from rectangular perforations arranged in a horizontal row. The forwardly extending set of triangular cutters have their upper edges horizontal and their lower edges oblique, while the rearwardly extending set of triangular cutters have their upper edges oblique and lower edges horizontal.
Clark, U.S. Pat. No. 1,387,883, Aug. 16, 1921, Hoe: Discloses a hoe including a blade having the shape of a sector of a circle with the apex of the sector pointing downwardly.
Miljan, U.S. Pat. No. 3,116,796, Jan. 7, 1964, Multi-Purpose Agricultural Hand Tool: Discloses a hoe-like agricultural hand tool including a substantially triangularly-
Batson Victor
Chapin William L.
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