GB2108887A - Knives - Google Patents

Abstract

A knife comprises a blade having a cutting edge 3 of V-shape on a parallel sided blank, the V-shape being formed by flat grinding to one side 4 of the Vee and grinding with formulations such as scalloping and/or serrations to the opposite side 5 of the Vee. <IMAGE>

Description

SPECIFICATION Knives This invention relates to knives, and is particularly, though not necessarily exclusively, concerned with domestic knives such as would be used, e.g., in the kitchen.

It has been long recognised that the cutting performance of a knife can be enhanced or made to suit a particular cutting purpose by providing at the cutting edge a formulation such as serrations or scallops. However whilst such formulations can improve considerably the cutting action, they have the disadvantage of not readily being resharpenable and have a tendency to tear rather than cut clean. Because the creation of formulations such as serrations or scallops involves a separate grinding step in the production of knife blades, this has the effect of increasing production costs, and yet produces a blade which may not have a total life of a conventional blade by virtue of the difficulties of resharpening.It is, therefore most important that the production costs of the blade with edge formulations are kept to a minimum, whilst providing adequate cutting life and improved cutting performance.

Many attempts have been made hitherto, without success to produce an effective (cost and performance) serrated or scalloped blade for a knife. Thus, it is known to take a parallel-sided blank and grind serrations on one side only at an angle, the angular serrations combining with the plain unground face to produce a cutting edge.

However by not having the cutting edge centrally of the thickness of the blade, the cutting action is impaired, and is not suited to both left hand and right hand usage. It is also known to grind serrations to one side only of a blank, the sides of which taper to a centrally arranged cutting edge, but the use of tapered blanks increases noticeably the cutting force required and adds noticeabiy to the costs of production. It is further known to grind serrations on both faces of a parallel-sided blank to produce a central cutting edge. However this produces what resembles a saw edge with ragged cutting properties.

The object of the invention is to provide a knife having a blade with edge formulations which combines the requirements of improved performance and low costs of production.

According to the present invention, a knife comprises a blade having formulations at its cutting edge to assist the cutting action, said edge being V-shaped on a parallel-sided blank, and being fiat ground to one side of the Vee and ground with formulations to the opposite side of the Vee.

Preferably, the formulations are scallops and/serrations.

Thus, the invention utilises conventional parallel sided blanks, and has a centrally located cutting edge, with the grinding of edge formulations to one side only. Such a blade, therefore, combines relatively low costs of production with the retention of improved cutting performance.

It has been found that the angle of the V-shaped cutting edge, and the scallops and/or serrations ground to one side of the V-shaped cutting have a marked effect on the cutting performance of the blade. It is therefore an important aspect of the present invention that the V-shaped cutting edge has an included angle between 140 and 300. Preferably the included angle lies between 160 and 22", it being further preferred that the included angle lies between 1 80 and 200.

It is yet another important aspect of the invention that serrations are ground to one side of the V-shaped cutting edge, there being from 25 to 50 serrations per inch and preferably 40 serrations per inch, it being further preferred that the included angle of the serrations lies between 800 and 1000 and still further preferably 900. To ensure that the serrations do not produce a saw blade effect, great care has to be taken to produce serrations which, when viewed from the flat ground side of the blank, only marginally protrude above the general level of the edge of the blade.

Because the V-shaped cutting edge is flat ground to one side, and the serrations only protrude marginally, the knife can be resharpened by regrinding by hand or otherwise, the flat ground surface of the V-shaped cutting edge.

It is s still further important aspect of the invention that in addition to serrations, scallops can be ground on the same side of the V-shaped cutting edge. Thus, scallops having a radius in the range 0.1" to 0.25!' can be provided. Preferably the radius is 0.16". The scallops may have pitch in the range 2.5 to 10 and preferably 5 T.P.I. It is further preferred that the serrations, when scallops are present, have an included angle between 500 and 70 , with a still further preference of 600.

Two embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a side elevation of a knife with a knife edge in accordance with the invention; Figure 2 is a side elevation of the opposite side of part of the knife blade of Figure 1; Figure 3 is an enlarged side elevation of part of the blade edge of Figure 1; Figure 4 is a section on the line 4-4 of Figure 3; Figure 5 corresponds to Figure 1 but shows a second embodiment of the invention; Figure 6 corresponds to Figure 2, but shows the knife blade of Figure 5; Figure 7 corresponds to Figure 3, but shows the knife edge of Figure 5; and Figure 8 is a section on the line 8-8 of Figure 7.

In Figures 1 to 4, a knife 1 has a blade 2 the cutting edge 3 of which is of V-shape (see particularly Figure 4) formed by flat grinding to one side of the Vee (at 4) and grinding with formulations 5 to the opposite side of the Vee. As is shown particularly by Figure 4, the included angle of the V-shaped cutting edge lies between -180 and 200. The formulations 5 in Figures 1 to 4 are, as is shown more particularly by Figure 3, serrations that are ground to one side of the V-shaped cutting edge. It is preferred that there are 40 serrations per inch and that the included angle between adjacent serrations is at 900.To prevent the cutting edge from having a saw-blade effect, the depth of grinding of the serrations 5 is such that when viewed in the direction of Figure 2, the serrations only marginally protrude above the general level of the edge of the blade.

In Figures 5 to 8 there is shown a second embodiment of the invention where the cutting edge 6 of the blade 7 of a knife 8 is formed by a combination of serrations and scalloping. Thus, as is shown particularly by Figure 8, the cutting edge is again a V-shaped cutting edge with flat grinding at 9 (Figure 6) to one side of the cutting edge and grinding with serrations and scallops 10 to the other side of the cutting edge. Here again as is shown by Figure 8 the V-shaped cutting edge has an included angle between 1 80 and 200, and as is indicated in Figure 7 the serrations have an included angle between adjacent serrations of 600 with 40 serrations per inch, and the scallops have a radius of 0.1 6" and are provided at a rate of 5 per inch. As with the cutting edge of Figures 1 to 4 and to prevent the serrations/scallops from producing a saw-blade effect, the serrations should only marginally protrude above the general level of the edge of the blade.

Knife blades in accordance with the invention successfully combine relatively low production costs with improved performance over conventional blades, and in the preferred forms, a performance considerably better than other forms of blades with edge formulations known hitherto.

Claims (16)

1. A knife comprising-a blade having formulations at its cutting edge to assist the cutting action, said edge being V-shaped on a parallel-sided blank, and being flat ground to one side of the Vee and ground with formulations to the opposite side of the Vee.

2. A knife as in Claim 1, wherein the formulations are scallops and/or serrations.

3. A knife as in Claim 1 or Claim 2, wherein the V-shaped cutting edge has an included angle of between 140 and 300.

4. A knife as in any of claims 1 to 3, wherein the V-shaped cutting edge has an included angle of between 160 and 220.

5. A knife as in any of Claims 1 to 4, wherein the V-shaped cutting edge has an included angle of between 180 and 200.

6. A knife as in any of Claims 2 to 5, wherein between 25 to 50 serrations per inch are ground to one side of the V-shaped cutting edge.

7. A knife as in any of Claims 2 to 6, wherein 40 serrations per inch are ground to one side of the V-shaped cutting edge.

8. A knife-as in any of Claims 2 to 7, wherein the serrations have an included angle of between 800 and 1000.

9. A knife as in any of Claims 2 to 8, wherein the serrations have an included angle of 900.

10. A knife as in any of Claims 2 to 9, wherein the serrations are ground such that when viewed from the flat ground side of the blank they only marginally protrude above the general level of the edge of the blade.

11. A knife as in any of Claims 2 to 10, wherein scallops having a radius of 0.1" to 0.25" are ground to one side of the V-shaped cutting edge.

12. A knife as in any of Claims 2 to 11, wherein scallops having a radius of 0.16" are ground to one side of the V-shaped cutting edge.

13. A knife as in any of Claims 1 to 12, wherein the scallops have a pitch in the range 2.5 to 10 per inch.

14. A knife as in any of Claims 2 to 13, wherein the scallops have a pitch of 5 per inch.

15. A knife as in any of Claims 2 and 11 to 14, wherein the serrations have an included angle of between 500 and 700.

16. A knife as in any of Claims 2 and 11 to 15, wherein the serrations have an included angle of 600.

1 7. A knife substantially as hereinbefore described with reference to Figures 1 to 4 of the accompanying drawings.

1 8. A knife substantially as hereinbefore described with reference to Figures 5 to 8 of the accompanying drawings.