US3439420A - Knife - Google Patents

Description

United States Patent Office 3,439,420. Patented Apr. 22, 1969 3,439,420 KNIFE Robert L. Erickson, 1360 E. 4th St., St. Paul, Minn. 55106 Filed May 12, 1967, Ser. No. 638,055 Int. Cl. B26b 29/02, 3/08 U.S. Cl. 30-294 8 Claims ABSTRACT OF THE DISCLOSURE Background of the invention The invention relates to knives and similar bladed instruments for cutting sheet material.

Where strips of fabric, embossed vinyl sheeting, and the like are adhered to a wall or other surface, it is aesthetically important for the edges of adjacent strips to abut smoothly and inconspicuously. Since the edges of the material are generally not suificiently true to accomplish this end, it is comomn for such material to be manufactured with selvage edges; adjacent strips are then overlapped and the selvage edges simultaneously cut away from both overlapped strips. Simple though this cutting operation may sound to the uninitiated, the man skilled in the art has found it extremely difficult to do well.

Since scissors can usually not be fitted under the overlapped edges without causing the cut edges to overlap rather than abut, and since there is often insufficient room to start the scissors cut, it is common to use a knife having an extended blade for trimming the selvage from the overlapped edges of adjacent strips. If the knife blade is narrow (e.g., like a razor blade), it tends to deflect erratically sideways, so that cutting does not always take place at right angles to the substrate, causing the line of abutment between the cut strips to appear to waver. Such deflection may also be so violent as to break the blade. On the other hand, if the knife blade is broad enough to remain rigid, it tends to leave a visible gap between the adjacent strips after trimming. Cutting overlapped strips with a knife often damages the substrate to which the strips are adhered; plaster, for example, chips and powders, de-tackifying the adhesive adjacent the edges and causing roughness and irregularity at the seam.

Summary The present invention provides a novel and highly effective knife which is particularly adapted for use in cutting the edges of vinyl or similar sheeting so that adjacent strips snugly abut. The knife does not damage the substrate in any way during the cutting operation, and cutting is accomplished with the blade held at a constant right angle to the surface On which the sheets being out are supported. Despite the fact that an extremely thin blade is employed, breakage during use is virtually unknown.

The knife of this invention has -a shoe which supports the portion of the sheet material being out throughout the cutting operation, sliding smoothly along the wall or other substrate to which the sheet material is applied, or on which it is supported. A thin blade meets the shoe at an acute angle and is supported by a body member which contacts the back and both ends of the blade. The knife is pulled along the material to be cut, the material being forced into the notch angle where the blade meets the shoe.

Brief description of the drawing The invention will be better understood by referring to the accompanying drawing, in which the like numbers refer to like parts in the several views, and in which FIGURE 1 is a side view of the knife of this invention;

FIGURE 2 is a rear view of the knife of FIGURE 1, i.e., as seen by the user;

FIGURE 3 is a view of the knife of FIGURE 1, looking in the direction of arrows 3-3; and

FIGURE 4 is a view showing the manner in which the knife of FIGURE 1 is employed.

Description of preferr d mbodiment The presently preferred embodiment of the invention will now be described with particular reference to the drawings.

Knife 10 comprises body, or holding means 11, having handle means 12 at one end and shoe means 13- at the other end. Blade, or cutting means, 14- is so positioned that it is supported by holding means 11 and held from sliding longitudinally thereof by shoulders 19 and 20. Nibs 16 are provided on each side of the portion of holding means 11 which supports the back of cutting means 14 to minimize the possibility of lateral distortion of cutting means 14 in use. One corner of cutting means 14 is also supported by a small slot 17 in the upper face of shoe means 13.

At the rear of blade 14 is combination guard and locking means 15, which is a U-shaped member formed from thin sheet metal, pivotally attached to body 11 by rivet 21. When guard and locking means 15 is in the position shown in FIGURE 1, it serves the dual purpose of holding one end of blade 14 in position and protecting the thumb and fingers of the user from inadvertent contact with blade 14. When the portion of blade 14 adjacent shoe means 13 becomes dull, means 15 is pivotally rotated so that it releases blade 14, which is then turned end-for-end; means 15 is then pivotally returned to its previous position, again holding blade 14 firmly in position.

Shoe means 13 is preferably formed from thin rigid sheet material, such as ;-inch brass; in order to facilitate construction, it is desirable to form shoe means 13 with a hole, into which a corresponding tongue portion of body 11 is inserted and held by soldering, welding, swaging, etc. Shoe means 13 has a smoothly tapered and convexly rounded leading end, as is particularly shown in FIGURE 2; this end may, for example, have a generally parabolic shape. Additionally this end is provided with a bevel 13a, for a purpose which will become more apparent as the description proceeds.

Referring now to FIGURE 4, the manner of using knife 10 will be discussed. Vinyl sheets 30 and 31 are adhered to a wall so that their respective selvage edges 30a and 31a overlap. A small slit is made at the top edge of the overlapped sheets 30 and 31, after which shoe means 13 is inserted between sheet 30 and the wall, thereby aligning blade 14 with the slit. The user then grips handle 12 and draws knife 10 vertically downward, causing sheets 30 and 31 to be forced into the notch where blade 14 meets shoe means 13 and progressively slitting the two sheets. Handle, or gripping means 12, which may be made of any suitable material such as synthetic resin, wood, or metal, is sufliciently short that knife '10 can be drawn to within 4 inches of the floor, which is a typical baseboard height.

Throughout the slitting operation, beveled edge 13a of shoe means 13 gently forces its way beneath sheet 30, which is adjacent to the wall in the illustration shown in FIGURE 4, while the fiat lower surface of shoe means 13 follows flush against the wall and holds blade 14 at a constant right angle to the wall. When shoe means 13 is inch wide and inch thick, sheets 30 and 31 are lifted just enough so that, after removal of selvage edges 30a and 31a, the freshly cut edges abut snugly and leave no visually distracting line of demarcation.

Cutting means 14 may be a conventional blade of the type used in an injection razor; a single such blade may be used effectively for as long as several days, although somewhat more frequent replacement facilitates the cutting operation and minimizes the possibility of snagging. the sheet material being cut. It has been found from experience that the angle at which blade 14 meets shoe means 13 should be acute; 30 has proved particularly effective. A greater angle may result in picking up threads where the sheet material being cut has a fabric backing; a lesser angle requires shoe means 13 to be longer, thus necessitating a greater initial length of slit where knife is started near the ceiling A knife employed in cutting sheet material adhered to a wall or other support inevitably picks up some of the adhesive, to which dust, threads, etc., often stick. Since such adhesive is typically water-soluble, it is common to clean the knives with water. To reduce the possibility of rust and corrosion, it is accordingly preferred to make the metallic portions of knife 10 from metals which resist corrosion when exposed to water. Stainless steel and aluminum possess such characteristics, and, in fact, an excellent metal for blade 14 is stainless steel. Aluminum, however, is not only deleteriously affected by acidic or basic adhesives, but also tends to leave black smudges on surfaces. It has been found that brass, which is corrosionresistant, non-marking, :and easy to fabricate, is a particularly suitable metal for shoe means 13, body 11, and guard 15.

What is claimed is as follows:

1. For use in the simultaneous cutting of one or more layers of sheet material, especially while said sheet material is positioned on and adhered to a planar support such as a wall, a knife comprising in combination:

a broad, flat thin rigid shoe means which is longer than it is wide and which comprises two sides which convexly curve toward each other to form a smoothly tapered leading end, upper and lower faces which lie in essentially parallel planes, said upper face being beveled at said leading end,

a thin, elongate removable cutting means in contact with said shoe and positioned in a plane substantially at right angles thereto, the long dimension of said cutting means lying at an acute angle to the upper face of said shoe means,

a holding means aflixed to said shoe in a plane substantially at right angles thereto and holding said cutting means in fixed position, and

a U-shaped sheet metal guard and locking means having legs which straddle and are attached to said holding means adjacent the end of the blade distal from said shoe means, said guard and locking means being rotatable over the cutting means to hold it in position and simultaneously help prevent it from cutting the users hand, and

rotatable away from said cutting means to permit removal thereof.

2. The knife of claim 1 wherein the acute angle between the upper face of said shoe means and the long dimension of said cutting means is about 30.

3. The knife of claim 1 wherein the upper face of the shoe means is provided with a shallow slot to receive a portion of said cutting means and help provide support therefor.

4. The knife of claim 3 wherein the holding means comprises a thin rigid metal body, longer than the cutting means and having a gripping means afiixed at the end thereof distal from said shoe means.

5. The knife of claim 4 wherein the holding means is thicker than the cutting means and is provided with a shoulder at each end of the cutting means and a cutting means-supporting portion at the rear side of said cutting means.

6. The knife of claim 1 wherein nibs are provided along the supporting portion of the holding means to minimize lateral distortion and breakage of the cutting means.

7. The knife of claim 1 wherein the shoe means, holding means, and locking means are made of metal which resists corrosion by water.

8. The knife of claim 7 wherein the metal is brass.

References Cited UNITED STATES PATENTS 757,317 4/1904 Kinney 30-294 642,689 2/1900 Garllus 30-294 1,281,664 10/1918 Rosendahl 30330 2,537,287 1/1951 Thomas 30294 2,601,388 6/1952 Guarino 30-330 X 2,601,414 6/1952 Mittelstaedt 30-294 FOREIGN PATENTS 566,233 12/1944 Great Britain.

JAMES L. JONES, JR., Primary Examiner.

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