US3888005A

US3888005A - Cutting tool

Info

Publication number: US3888005A
Application number: US502341A
Authority: US
Inventors: Dennis P Bagwell
Original assignee: Tomorrow Enterprises Inc
Current assignee: Tomorrow Enterprises Inc
Priority date: 1974-02-19
Filing date: 1974-09-03
Publication date: 1975-06-10
Anticipated expiration: 1992-06-10

Abstract

An improved cutting tool such as a knife is disclosed, where the tip of the knife is designed to prevent the knife from scratching abrading or cutting a flat support surface which is supporting an article being cut.

Description

United States Patent 1191 1111 3,888,005

Bagwell June 10, 1975 [541 CUTTING TOOL 527,175 12/1894 Hurdl; 3.. [3204386 1,135,987 /l915 Beec er O X [751 Invent Denms La Grangfl- 1,820,234 8/1931 Lees 30/357 73 Assignee; Tomorrow Enterprises, Inc" La 3,363,315 1/1968 Anderson... 30/286 X Grange L 3,842,501 10/1974 Honma 30/286 [22] Filed: Sept. 3, 1974 [21] Appl. No.2 502,341 Primary Examiner-James L. Jones, Jr.

Rented U S Application Data Assistant ExaminerJ. C. Peters [63] Continuation-impart of Ser. No. 443,603, Feb. 19, 1974, abandoned, which is a continuation of Ser. No. 274,642, July 24, 1972, abandoned.

[57] ABSTRACT [52] US. Cl. 30/286 [51] Int. Cl B26b 9/02; B26b 29/02 [58] Field of Sand H 30/286 287' 346 351, An lmproved cutting tool such as a knife 15 disclosed,

30/355 where the tip of the knife is designed to prevent the knife from scratching abrading or cutting a flat sup- [56] References Cited port surface which is supporting an article being cut.

UNITED STATES PATENTS 460,677 10/1891 Christy 30/355 6 Claims, 10 Drawing Figures 2o 22 za s3 fjTENTFDJUMo ms 268K005 sum 2 FIG. 5

CUTTING TOOL RELATED APPLICATIONS This application is a continuation-in-part application of my copending application Ser. No. 443,603, now abandoned filed Feb. 19, 1974, entitled Improved Cutting Tool, which in turn is a continuation of my now abandoned application Ser. No. 274,642, filed July 24, 1972, entitled Improved Cutting Tool,

BACKGROUND It is common for sharp knives to scratch or cut a support surface once the knife has cut through an article resting on the support surface. This problem would appear to be insoluble because the very qualities of sharpness so necessary for efficient cutting are the very same qualities which are responsible for scratching or cutting the support surface. Eventually, surfaces such as Teflon-coated cookware, plastic pottery and china dishware are damaged and disfigured by knives constantly scratching and abrading their surfaces. In some instances this leads to breakage or, as in the case with Teflon-coated material, eventual destruction of the sur face, rendering it useless. I have now invented a cutting tool, particularly a knife, which will cut an article but avoid scratching, abrading or cutting the flat support surface on which the article rests. Preferred embodiments of this knife are shown in the accompanying drawing and described in the following description.

DESCRIPTION OF THE DRAWINGS FIG. I is a side elevational view of a knife designed in accordance with my invention.

FIG. 2 is a plan view of my knife taken along line 2-2 of FIG. 1.

FIG. 3 is an enlarged perspective view of the tip of the knife shown in FIG. 1, where the cutting edge is formed by honing only one side of the blade.

FIG. 4 is an enlarged perspective view of the tip of a knife designed in accordance with my invention, but where the cutting edge is formed by honing both sides of the blade.

FIG. 5 is a side elevational view showing a knife ap parently in accordance with my design, but where at the minimum cutting angle of the knife the knife tips contact surface is not flush against the support surface.

FIG. 6 is an end view of the knife shown in FIG. 5 taken along line 6-6 of FIG. 5.

FIG. 7 is an enlarged, fragmentary side elevational view showing a knife of my design where at the minimum cutting angle of the knife the wide-area contact surface is essentially flush against the support surface.

FIG. 8 is an end elevational view of the knife shown in FIG. 7 taken along the line 88 of FIG. 7.

FIG. 9 is an enlarged fragmentary view in side elevation showing the knife of FIG.

FIG. 10 is an enlarged fragmentary view in side elevation showing the knife of FIG. 4.

DESCRIPTION OF PREFERRED EMBODIMENTS Cutting tool 10 embodying the features of my invention is shown in FIGS. 1 and 2. This tool 10 is a knife having handle 12, blade 14, including a continuous cutting edge l8, and rounded tip 16 designed in accordance with my invention. This tip prevents cutting edge 18 of blade 14 from scratching, abrading or cutting flat support surface 19. Edge 18 preferably is serrated, but

it may also be non-serrated or straight edged. Edge 18 should be continuous, however, to afford smooth, easy cutting.

FIGS. 3 and 4 show alternate embodiments of damage-preventing tip 16. In FIG. 3, tip 16 is formed in leading end 13 of blade 14 by honing cutting edge 18 from one side of the blade. Tip 16 includes a smooth, wide area contact surface 20. As will be explained in greater detail below, this contact surface 20 lies essentially flush against support surface 19 at the minimum useful cutting angle of knife I0. Common to cutting edge 18 and contact surface 20 is junction point 22. Contact surface 20 expands outwardly and away from junction point 22 and terminates at its broadest width 24 in a wide-area, enlarged, smooth surface 26. This enlarged surface 26 is preferably rounded so that it curves around and meets the blunt edge 28 of blade 14.

In FIG. 4 tip 16a is formed by honing cutting edge 18a from both sides of blade 14a. In leading end of blade 14a, tip 16a is formed having the same components as tip 16 except contact surface 200 is shaped slightly different than surface 20. Both, nevertheless, are wedge-shaped. The advantage of such wedge shaped

contact surfaces

20 and 20a is that there will be less drag as the knife blade moves through the object being cut.

Surfaces

20 and 26 have rounded extremities 25, and surfaces 20a and 260 have rounded extremities 250. This is an important feature of my invention, because when the user twists the knife in use, damage to the support surface is avoided or minimized. The embodiment shown in FIG. 3 is preferred because it can be made at low cost using known mass production techniques.

The key to the successful damage avoidance or prevention of tips 16 and 16a is that a major portion of

contact surfaces

20 or 20a must be essentially flush with support surface 19 at the minimum cutting angle of knife 10. This feature is best illustrated in FIGS. 5 through 8. The minimum cutting angle of knife 10 is determined by the manner in which the knife is held. Normally, the user grasps handle 12 and the users hand prevents cutting edge 18 from being flush or at 0 with respect to support surface 30. Ordinarily, the minimum useful angle is from about 2 to about 8, and in some instances as high as 15. It is critical to the suc cessful operation of a damage-preventing tip 16 that at the minimal useful angle a major portion of wide-area contact surface 20 be flush against support surface 19.

FIGS. 5 and 6 illustrate a knife 10b which appears to be equivalent to my design, but at the minimum useful cutting angle contact surface 20b is not flush against support surface 19, but raised slightly off this support surface. This enables cutting edge 18b at junction point 22b to strike into support surface [9 cutting or abrading it. In contrast, FIGS. 7 and 8 illustrate my invention where at the minimum cutting angle all or a major portion of contact surface 20 is flush against support surface 19. Here the forces which would ordinarily abrade or cut support surface 19 are transmitted through knife 10 and distributed uniformly over wide-area contact surface 20, preventing or minimizing damage to support surface 30. At angles greater than the minimum useful cutting angle, tip I6 turns and the rounded, enlarged surface 26 contacts support surface 19. Again, the forces which might damage support surface 30 are uniformly distributed over enlarged surface 26.

FIG. 1 illustrates my invention, where knife 10 is designed to be used at a minimum cutting angle of Here, handle 12 is elevated with respect to cutting edge 18 so that the user can grasp the handle and hold the cutting edge essentially flush against support surface 19. Such knife 10, when designed in accordance with my invention, has the damage-preventing tip 16 as described above at forward end 13 and a damagepreventing planar tip 30 at trailing end 32 of cutting edge 18. As shown in FIGS. 1 and 2, planar tip 30 includes a wide-area contact surface 33 which is essentially flush against support 19 at the minimum cutting angle of 0. Thus the forces which would press cutting edge 18 against support surface 19 and cause it to mar or damage the support surface are distributed uniformly over the contact surfaces 20 and 33 of the damage-preventing

tips

16 and 30. Cutting edge 18 is slightly displaced above support surface 19. Such edge displacement is particularly important when edge 18 is formed by honing only one side of blade 14. I have found that, if edge 18 is not displaced at least about 0.01 inch above surface 19, the support surface is frequently scratched when edge 18 is flush with surface 19, but tilted slightly about the blade 14 and moved across the support surface. In the embodiment shown in FIGS. 1 and 9, when the blade 14 is at its minimum cutting angle of 0 and tilted about a line intersecting the junction points 22 and 23 (FIG. 9), the

rounded extremities

25 and 34 of the contact surfaces 20 and 33 protect the support surface 19 from any damage due to

junction points

22 and 23, and the elevated edge 18 does not contact the support surface 19. Edge displacement is preferably from about 0.01 to about 0.03 inch above surface 19. Moreover the extremities 34 of surface 33 are also rounded to avoid scratching support surface 19 as knife is twisted during cutting.

Although edge 18 is displaced slightly above support surface 19, it curves around at its ends and joins the wide area contact surfaces and 33 at the junction points 22 and 23, respectively at the apexes of the wedge-shaped contact surfaces 20 and 33. FIG. 9 illustrates this feature of my knife 10 best, showing in magniflcation the precise relationship between the edge 18, contact surfaces 20 and 33,

junction points

22 and 23 and the support surface 19 with the blade perpendicular to the support surface 19. As illustrated, the knife edge 18 merges with the contact surfaces 20 and 33 at the junction points 22 and 23 with the contact surfaces and junction points being in a common plane and at the minimum useful cutting angle of 0, contacting and being flush against the flat support surface 19. Thus, the junction points 22 and 23 move through the article being cut, severing the article while remaining flush with the support surface 19 but not striking into said support surface 19, thereby avoiding cutting or abrading said surface. Consequently, my knife 10 not only protects surface 19, but cuts clean through the article being severed and is, therefore an excellent steak knife.

When the blade 14a of a knife is honed from both sides as shown in FIG. 4, then the cutting edge 18a may be brought into direct contact with the support surface 19. This feature is shown in FIG. 10. As illustrated, the tips of the serration just contact the surfact 19. But because the contact surfaces 200 and 33a rest against the surface 19, the tips 17a do not cut into the support surface 19, yet these tips 170 enhance cutting ability.

The advantages of my invention are numerous. Knives with this tip could be used on Teflon cookware without causing damage. Blade scratches on Melmac and plastic dishware, as well as china and pottery, would virtually be eliminated. The need for using cutting boards would be eliminated since food could be sliced on a normal drainboard surface without harm.

I claim:

1. A knife comprising a handle,

a blade attached to the handle and having a blunt top edge and opposite thereto a continuous cutting edge, and

damage preventing tips at both ends of the cutting edge which in normal use at a cutting angle of 0 contacts a flat support surface on which an article being cut rests, said cutting edge at 0 being essentially flush against the support surface so that the article being cut is severed clean through,

each of said tips including a smooth, wide-area contact surface which is essentially flush against the support surface at the cutting angle of 0, and a junction point common to the cutting edge and the contact surface so that at said 0 cutting angle the junction point moves through the article, severing said article while remaining flush with the support surface but not striking into said support surface, thereby avoiding cutting or abrading said surface,

the contact surfaces of both said tips having smooth,

rounded edge extremities such that a twisting motion about the longitudinal axis of the knife blade during cutting will bring the rounded edge extremities into contact with the support surface, whereby said rounded edges are adapted to avoid scratching, abrading or cutting of said support surface.

2. The knife of claim 1 wherein the cutting edge is formed by honing the blade from both sides.

3. The knife of claim 1 wherein the cutting edge is formed by honing the blade from one side only.

4. The knife of claim 1 wherein the contact surface of the tip at the leading end of the blade expands outwardly and away from the junction point and terminates at its broadest width at a wide area, enlarged smooth surface which curves around in an arcuate fashion to meet and join with the blunt top edge of the blade.

5. The knife of claim 4 wherein the contact surfaces have a generally wedge-shaped configuration.

6. The knife of claim 5 wherein the cutting edge is serrated.

Claims

1. A knife comprising a handle, a blade attached to the handle and having a blunt top edge and opposite thereto a continuous cutting edge, and damage preventing tips at both ends of the cutting edge which in normal use at a cutting angle of 0* contacts a flat support surface on which an article being cut rests, said cutting edge at 0* beiNg essentially flush against the support surface so that the article being cut is severed clean through, each of said tips including a smooth, wide-area contact surface which is essentially flush against the support surface at the cutting angle of 0*, and a junction point common to the cutting edge and the contact surface so that at said 0* cutting angle the junction point moves through the article, severing said article while remaining flush with the support surface but not striking into said support surface, thereby avoiding cutting or abrading said surface, the contact surfaces of both said tips having smooth, rounded edge extremities such that a twisting motion about the longitudinal axis of the knife blade during cutting will bring the rounded edge extremities into contact with the support surface, whereby said rounded edges are adapted to avoid scratching, abrading or cutting of said support surface.

6. The knife of claim 5 wherein the cutting edge is serrated.