IES67778B2 - A safety knife or cutter - Google Patents

Abstract

A knife or cutter comprising a body (1) suitable to be gripped manually, a blade (2) projecting from the body (1), a guard plate (6) adjacent to the blade (2) and facing the cutting element thereof, and a thin spring member (7) attaching the guard plate (6) to the body (1), the spring member being forward of the blade and aligned therewith, and a gap "a" being present between the blade (12) and the guard plate (6) in the rest position of the spring member (7), the flexibility of the spring member (7) allowing this gap to be substantially closed when pressure is applied on the blade (2). A groove (10) is provided in the guard plate (6), aligned with the blade (2). A roller (12) or roller bearing may be mounted in the underneath surface of the body, above the rear portion of the guard plate (6). .

Description

This invention relates to a knife or cutter with a safety shield assembly. The knife is intended for many uses in cutting materials such as paper, fabric, cardboard, plastic, floor coverings and the like and is generally of the type used in Do-It-Yourself work or by craftworkers.

Known knives of this type are usually provided with very sharp blades, which give rise to two different problems. Firstly when cutting a material on a table or other substrate, the blade tends to cut down into the substrate, causing damage to it. Secondly, a sharp blade when projecting from a knife can cause injury if it encounters a hand or other part of the body of the user or of another person.

It is an object of the invention to overcome these problems.

French Patent 2 539 574 Longet et al. describes a safety cutter having a slidable cover to hide the blade and a heel which is located under the material to be cut, the heel being joined to the main body of the cutter by a thin and tapered body part which permits the passage of the cut material. The slidable cover has a foot, and the material to be cut is inserted between this foot and the heel of the tool. However in order to accommodate materials of different thickness it is necessary to relocate the slidable cover, and there is no way of pressing the blade onto the material to be cut against a firm backing. 967778 - 2 The blade is angled such that cutting is effected from beneath the material to be cut which would make it difficult to cut on a line. The heel is of substantial thickness and would not easily slide between a sheet material (such as paper) and a table, workbench or other substrate on which the material is laid.

The present invention provides a knife or cutter comprising a body, a blade projecting from the body, a guard plate adjacent to the blade and facing the cutting element thereof, and a thin spring member attaching the guard plate to the body, the spring member being forward of the blade and aligned therewith, and a gap being present between the blade and the guard plate in the rest position of the spring member, the flexibility of the spring member allowing this gap to be substantially closed when pressure is applied on the blade.

In a preferred embodiment, a groove is provided in the guard plate, aligned with the blade. Although the blade presses the material to be cut against the guard plate, the blade tip should not reach the base of the groove in order to minimise wear on the blade tip.

Preferably the spring element is a thin strip suitably having a thickness (perpendicular to the blade) not more than 5 times the thickness of the blade. The spring element should be thin enough to permit easy passage of it along the cut made in the material made by the blade. If desired the spring member may comprise a substantially rigid upper portion, e.g. having a V-shaped cross section with the apex of the V facing the blade, and a lower spring portion adjacent to its attachment to the guard plate.

The invention is illustrated in the accompanying drawings, in wh i ch; Figure 1 is a pictorial view of a first embodiment of a knife according to the invention.

Figure 2 is a side elevation of the knife of figure 1.

Figure 3 is a top plan view of the knife of Figures 1 and 2. - 3 Figure 4 is a detailed pictorial view of the guard plate and spring member.

As shown in Figures 1 - 3, a knife according to the invention comprises a body 1 suitable to be gripped manually, a blade 2 projecting from the body, and a shield assembly 3 adjacent to the blade The bodv 1 and blade 2 may be similar to those of a conventional trimmer knife such as is sold under the Trade Mark STAHLEY. The blade 2 may suitably be housed in replaceable manner inside the body 1, with one triangular portion of the blade projecting from the body. The triangular portion has a sharp point 4 and a cutting edge 5 which extends generally parallel to the longitudinal direction of the body.

The shield assembly comprises a guard plate δ and a thin spring member 7 by which the guard plate δ is attached to the body 1. The spring member 7 suitably comprises a thin strip of metal which is anchored at the top end 8 to the body. A free portion 9 of the strip extends downwardly in front of the body on the vertical mid-line of the body and thus is aligned with the blade. At its bottom end the spring member is fixed to the guard plate 6. The guard plate lies underneath the point 4 and cutting edge 5 of the blade. In the rest position of the spring member 7, there is a gap a between the blade 2 and the guard plate 6 (see Figure 2). As shown in the drawings, the guard plate has the shape of an isosceles triangle with the apex pointing rearwardly. However the guard plate may if desired have at least one edge parallel to the longitudinal direction of the body so that the guard plate can be moved along a straight edge such as a ruler when the knife is being used. The guard plate suitably comprises a rigid abrasion resistant plastics material. It should be readily slidable on a smooth substrate surface and it may be described as a skid..

As shown in the drawings, the guard plate is a thin plate with parallel top and bottom surfaces and a thickness of the order of 0.5 1.5 mm. However it may if desired have converging top and bottom surfaces reducing from a thickness of 3-3.5mm at the front edge (where is is attached to the spring member) down to a minimal thickness e.g. 0.25 mm at the trailing edge or apex.

The guard plate preferably has a groove 10 in its top surface, aligned with the blade 2. During cutting the blade enters the groove but the blade point should not reach the base of the groove so that it is kept sharp.

Optionally, the shield assembly includes a nose 11, suitably of transparent plastics material, which encases the front of the body and protects the spring member. The nose 11 does not extend downwardly as far as the point 4 of the blade.

In use, the body is gripped by hand and the guard plate 6 is placed on a table, work bench or other smooth substrate surface. An edge of the material to be cut is introduced between the guard plate 6 and the body 1. Pressure is then applied on the body, the spring member 7 flexes and the point 4 of the blade is pressed against the guard plate 6. The knife is pulled rearwardly, causing the blade to cut the material which is trapped against the guard plate, with the groove 10 (if present) defining a line on which the material is not supported so that the blade can more easily cut through it. As the knife is drawn rearwardly, the spring member 7 enters the cut formed in the material, and the material passes on either side of the spring member.

The guard plate protects the table (or other substrate surface) from being cut by the knife. When the knife is not in use, the guard plate shields the blade and prevents accidental damage or injury being caused by the exposed blade.

If desired, a roller 12 may be mounted in the underneath surface of the body 1, above the rear portion of the guard plate 6 to facilitate movement of the knife over the material to be cut, the material being pressed against the guard plate by the roller and to restrict the depth of entry of the blade point into the groove 10.

The roller may be formed in two parts with a mid-axial gap so that it does not interfere with the blade. Alternatively the roller may be replaced by roller bearing(s). The roller or roller bearing(s) may be spring-mounted in the body. - 5 The knife of the invention is particularly useful for cutting paper. As the knife is not adapted for sharpening pencils, a * conventional pencil sharpener may be incorporated into the body e.g. at the end of the handle remote from the blade.

Claims (5)

1. A knife or cutter comprising a body, a blade projecting from the body, a guard plate adjacent to the blade and facing the cutting element thereof, and a thin spring member attaching the guard plate to the body, the spring member being forward of the blade and aligned therewith, and a gap being present between the blade and the guard plate in the rest position of the spring member, the flexibility of the spring member allowing this gap to be substantially closed when pressure is applied on the blade.

2. A knife or cutter according to claim 1 wherein a groove is provided in the guard plate, aligned with the blade.

3. A knife or cutter according to claim 1 or 2 wherein the spring element adjacent to its attachment to the guard plate is a thin strip having a thickness (perpendicular to the blade) not more than 5 times the thickness of the blade.

4. A knife or cutter according to any of the preceding claims having a roller or roller bearing mounted in the underneath surface of the body, above the rear portion of the guard plate.

5. A knife or cutter substantially as described herein with reference to and/or as illustrated in the accompanying drawings.