EP0474295A1

EP0474295A1 - Forged knife provided with ergnomical handle

Info

Publication number: EP0474295A1
Application number: EP91202210A
Authority: EP
Inventors: designation of the inventor has not yet been filed The
Original assignee: Sanelli Danilo
Current assignee: Sanelli Danilo
Priority date: 1990-09-05
Filing date: 1991-08-30
Publication date: 1992-03-11
Also published as: IT220140Z2; IT9021701U1; IT9021701V0

Abstract

Knife consisting of a metal member forged to form a blade (12) integral with a tang (18), provided with a hitch (20), on which is fastened a handle (30a, 32a) having ergonomical shape for helping handling and allowing a prolongated use thereof.

Description

The present invention pertains to a forged knife provided with ergonomical handle, in which the metallic portions forming the blade and the tang, at least partially thickened to form a so-called hitch, are obtained by forging, and the handle is given an ergonomical shape to allow to handle it safely and without any trouble for a prolongated use thereof. Since long time are well-known household knives of the so-called forged kind in which the blade with the tang is obtained by forging a suitable metal piece under a proper forge and then to the tang a handle is joined to allow to handle in a practical way the so obtained knife.
It was, however, recognized in said knives that, as none was concerned with the specific handle shape, there were knives with handles safely fastened to the tang which, however, showed poor handling comfort with attending danger to tire the hand and cause accidents or injuries to the users.
It was decided, to obviate this problem, to reshape the handles of said knives giving them an ergonomical shape, i. e. such a shape to be suited in the best way with the human hand.
A very simple way for obtaining the ergonomical shape of a handle in a forged knife is to take a blade with its tang, to coat said tang with a mouldable matter, such as plasticin, and to have said coated tang handled by a person having medium- sized hands for obtaing on said mouldable coating a mark indicating the ideal shape to be given to a knife handle, in order to be perfectly ergonomical. Subsequentely, the handle and possibly the internal tang are shaped, according to said mark, obtaining a handle perfectly suited to the hand of the individual having to handle it.
However, this system provides too personal handles which cannot be suited for a mass production of knives, such as household knives. Consequently, a knife handle has been to be studied, having ergonomical shape, starting from a hand track left on a mouldable material coating the tang of a forged knife and then processing the so- obtained shape for obtaining a handle of generally ergonomical shape suitable for any user.
To obtain this ergonomical handle, it is necessary to provide a general shape thereof upside convexly curved with a tip ending a little above the back of the knife blade and then descending both to a first end of the handle itself and to a junction point between handle and blade, showing moreover said handle downside at the edge of the blade a first re-entrant curve, starting from a second external end of the handle and ending in an inflexion point substantially halfway with respect to said handle from which starts a second convexed curve, less pronounced than the re-entrant curve joined with said blade at the juction point.
Preferably, said upper curve of the handle, according to the invention lowers more at the external end of the handle than at the junction point of the handle with the blade.
Also preferably, said lower re-entrant curve is more pronounced at the external end of the handle than at the subsequent inflexion point.
Further preferably, the subsequent lower convexed curve is marked substantially in the same way at both the inflexion point and the junction point with the blade.
The features and the advantages of the present invention will be better understood from a detailed description of an embodiment thereof, given in an exemplifying way and not in a limiting way, and provided with the enclosed drawings, wherein:

Figure 1 is a lateral partial view of a forged knife provided with a traditional handle, according to the most common prior art;
Figure 2 is a lateral partial view of a forged knife according to the present invention provided with ergonomical handle;
Figure 3 is a partial top view of a forged knife which could be both the one of the prior art depicted in figure 1 and the one, according to the present invention depicted in figure 2;
Figure 4 is a view, similar to that of figure 2, depicting more in detail and more carefully the criteria for designing the ergonomical shape to be given to a knife handle, according to the present invention.

Referring first to figures 1 and 3, it is seen that a forged knife 10 provided with traditional handle, according to the prior art, consists of a metallic portion forming a blade 12 provided with edge side 14 and back side 16.
The blade itself 12 is obtained by forging in just one piece with a tang 18 connected to the blade 12 through a hitch 20 consisting of two divergent connecting surfaces 22 and 24 ending with two shoulders 26 and 28 generally perpendicular to the lateral faces of the blade 12 and the tang 18. Between the lateral faces of the tang 18 rest two half handles 30 and 32 connected to the tang itself through well-known means, as for example the rivets 34, 36 and 38 shown in the half handle 32 depicted in figure 1. Further, said half handle 32 has a lateral planar portion 40 containing the rivets 34, 36 and 38, and connected through curved surfaces to the rims thereof, is provided with a rear protrusion 42, having the purpose to avoid any lost of grasp from the handle, and with a central relief 44 to help the finger grasp thereon.
As it is well seen in figure 1, the handle of the knife 10 is absolutely traditional, not having other feature than properly coating the tang 18 to allow at least to not too uncomfortably and relatively safely grasp the knife 10 itself, avoiding any un- comfort or injury to the user. However, as already explained, said handle is anything but suitable to the human hand and shows many poor grasping and tiring out problems for the user hand. The problems shown by traditional handles, such as that depicted in figure 1, are relieved in a knife 50, according to the present invention, depicted in the figures 2 and 3, provided with a handle having curves and generally indexed as suggested by a human hand, the directions for said curves and general indexing being obtained by coating a tang 18, integrally connected to a blade 12, with a mouldable material, as for example plasticine, and making grasp said coating by a person having average sized hands, in order to give thereto an anatomical shape to be repeated both in the half handles 30a and 32a (just the half handle 32a is visible in figure 2), coating said tang 18, and possibly in the tang outline, and resting between said tang 18 and the shoulders 26 and 28, remaining connected to the tang 18 by means of rivets 34a, 36a and 38a, as visible in figure 2. Further, as visible in figure 2 and analogously to what depicted in figure 1, said half handle 32a contains a lateral planar portion 40a containing the rivets 34a, 36a and 38a and connected through curved surfaces to the rims thereof.
Looking at figure 2, it is seen that the general shape of the half handle 32a is complexly curved having a top point or tip Pi, located a little above the back 16 of the blade 12, and then lowers to both an end vertex V₁ of the half handle 32a and the shoulder 28 indicating the junction of the half handle 32a with the hitch 20, being the lowering more at the vertex V₁ than at the shoulder 28. Further, the half handle itself 32a shows below, at the edge side 14 of the blade 12, a first re-entrant curve culminating in the point P₂, starting from a vertex V₂ and arriving to an inflexion point F₂ followed by a second less sharp convexed curve culminating in the point P₃, starting from the inflexion point F₂ and arriving to the shoulder 28, being the re-entrant curve sharper at the vertex V₂ and less sharp at the inflexion point F₂, while the convexed curve is substantially sharp at the same rate at both the inflexion point F₂ and the shoulder 28.
For giving more carefull criteria to define the ergonomical handle, according to the present invention, refer to figure 4 having the duty to define ratings for designing the ergonomical shape to be given to a knife handle, according to the present invention.
To this purposes is described a straight line, to be considered substantially horizontal, between a left end vertex V₁ of the handle and the lower right end of the shoulder 28, and the straight line segment comprised between said points is indicated by L. A straight line N perpendicular with respect to the above-mentioned straight line, passing through the top point or tip P₁ of the handle, is then described, intersecting the horizontal straight line in a point and dividing the segment, having length L, in two adjacent segments L, and L₂, being the length of L₁ comprised between 0.60L and 0.76L and the length of L₂ between 0.24L and 0.40L. On said straight line N, at a distance from the point P₁ of a radius R₁, is marked a rotation center for the upper curve of the handle, having said radius R₁ length comprised between 1.98L and 2.42L and being permitted to form with its limiting straight line R_1a, leftside to the straight line N, an angle comprised between 24° and 30° and with its limiting straight line R_1b, rightside to the same straight line N an angle comprised between 9 ° and 11°. Further, on the same straight line N and starting from the same rotation center is determined a radius R₂, having length comprised between 1.53L and 1.87L, removed from said straight line N by an angle between 10° and 12°, forming said radius R₂ with its left limiting straight line R_2a an angle comprised between 14° and 10° and with the right limiting straight line R_2b an angle comprised between 5° and 7°' the angle between said straight lines R_2a and R_2b resulting comprised between 15° and 21°.
At last, always on the same perpendicular straight line N, though above the point A, at a distance from the point P₃ equal to a radius R₃ comprised between 0.80L and 0.94L is described a pivotting point for the lower convexed curve of the handle culminating in the point P₃, forming said radius R₃ with its limiting straight line R_3a an angle on the left side of the straight line N comprised between 7° and 9° and with its limiting straight line R_3b on the right side of the straight line N an angle comprised between 18° and 22°, resulting the whole angle comprised between the straight lines R_3a and R_3b comprised between 25° and 31°.
The above-mentioned data indicate the limits within which is defined the shape of an ergonomical handle for a knife, according to the present invention. However, the preferred shape data for said handle are:

L₁ = 0.68L; L₂ = 0.32L;
R₁ = 2.20L; R₂ 1.70L; R₃ = 0.87L;
angle between R_1a and R _1b 32°;
angle between R_2a and R _2b 14°; and
angle between R_3a and R _3b 28°.

Of course, what has been hereabove disclosed and depicted is just an embodiment of the present invention, and those skilled in the art will be able to devise equivalent or alternate approaches, all to be considered as here covered.

Claims

1. Forged knife provided with an ergonomical handle (32a), characterized by having a general shape upside curved in a convexed way with a tip (Pi), located a little above the back (16) of the knife blade (12), and then lowers both to an external end (V₁) of the handle itself and to a junction point (28) between handle and blade, further having said handle downside, at the edge side of the blade, a first re-entrant curve, starting from another external end (V₂) of the handle and ending in an inflexion point (F₂) substantially halfway with respect to said handle from which starts a second convexed curve, less pronounced than the re-entrant curve connected with said blade (12) in the junction point (28).

2. Forged knife, as in claim 1, characterized in that said upside curve of the handle lowers more at the external end (V_i) of the handle than at the junction point (28) of the handle with the blade(12).

3. Forged knife, as in claim 1, characterized in that said lower re-entrant curve of the handle is more pronounced at the external end (V₂) than at the subsequent inflexion point (F₂).

4. Forged knife, as in claim 1, characterized in that the subsequent lower convexed curve is pronounced substantially in the same way both at the inflexion point (F₂) and at the junction point (28) with the blade (12).