Knife handle

Abstract

The hollow handle of a knife with a retractable blade is made of two shells secured together side-by-side, one shell having an integral female portion defining an oblique nose with a slot-like aperture in which a flat male tongue at the end of the other shell is inserted to define a blade outlet slot. A press button enables a blade held in a slidably mounted plate-like blade supporting carriage to be held against a face of the outlet slot during cutting, simultaneously locking the carriage and blade against unwanted longitudinal movement.

Description

The invention relates to knives, particularly knives with retractable blades such as those that are commonly used to cut moquette carpets, linoleum and other floor coverings and similar sheet materials.

A known type of knife with a retractable blade includes two shell members fitted together side-by-side and enclosing a slidably mounted blade-carrying carriage the longitudinal position of which is set by means of several notches in the blade to adjust the length of a blade protruding from an oblique blade outlet slot.

A fundamental drawback of these known knives in which the blade outlet slot is defined between facing parts of the two shell members is that the blade outlet slot risks becoming pried open in the event of abrupt lateral efforts, or as a result of repeated shaking of the blade upon prolonged use, since the edges of the slot are inherently insufficiently rigid to resist large separating forces.

A primary aim of the invention is to overcome this drawback by providing a hollow knife handle comprising first and second elongate shell members secured together generally edge-to-edge to define therebetween a blade-receiving cavity, in which the first member has at one end an integral female portion defining a nose end of the handle including a slot-like aperture communicating and in alignment with said blade receiving cavity, and the second member has a male end part inserted in said aperture to define therein a blade outlet slot.

The male end part preferably consists of a flat tongue having an outer face applied against one face of said aperture and an inner face defining, with the other face of said aperture, said blade outlet slot.

Another drawback of known knives of the specified type is that to ensure a smooth forward and rearward sliding of the blade and carriage, and to facilitate replacement of the blade, the blade must have a certain lateral play in the outlet slot but during use this play adversely affects the precision of cutting.

The invention aims to overcome this drawback by providing means which enable the blade to be firmly applied against a face of the outlet slot. The same means can be used provide a braking effect to avoid unwanted slipping of the blade in case its position-setting means is unwantedly actuated, and also to enable changing of the blade, when a blade-supporting carriage is in a given position. For example, the blade handle may further comprise a blade-supporting carriage in the form of a plate having a planar main part with parallel edges protruding perpendicular to one face of the main part, means for releasably securing a blade in said carriage against said main part, means for mounting the carriage within said cavity with said main part disposed parallel to the blade outlet slot and said edges of the carriage parallel to the longitudinal direction of the handle for a sliding movement of the carriage along the longitudinal direction of the handle towards and away from said blade outlet slot, and means for releasably holding the carriage in selected positions relative to the handle. The blade securing means advantageously include a resilient tongue integral with said plate, a projection on said tongue normally adopting a blade-securing position protruding from said one face of the main part but being resiliently deformable to a blade-disengaging position in which it does not protrude from said one face of the main part, and means for moving the projection to the blade-disengaging position when the carriage is disposed in a given position relative to the handle. The means for moving the projection can include a push button disposed on a part of the handle tapering towards said nose end thereof. When a blade is held in the carriage, and the carriage is disposed in positions other than said given positions, said button is adapted to move the carriage and blade together to apply the blade transversely against one face of the blade outlet slot.

An embodiment of the invention will now be particularly described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a side elevational view thereof;

FIG. 2 is a top plan view;

FIG. 3 is a cross-section taken along line III--III of FIG. 2;

FIG. 4 is a cross-section taken along line IV--IV of FIG. 3;

FIG. 5 is a cross-section taken along line V--V of FIG. 3; and

FIG. 6 is a cut-away perspective view of the blade-supporting carriage.

The hollow knife handle shown comprises two elongate shells 1 and 2 fitted together generally edge-to-edge to define a cavity therebetween. Shell 2 has at the left hand end (looking at FIGS. 1 and 2) an integral female portion defining a nose 4, oblique in relation to the longitudinal axis of the handle looking in side elevation, this nose 4 having a slot-like aperture communicating and in alignment with the central cavity. The corresponding end of shell 1 has a flat male tongue 3 inserted in said aperture with its outer (i.e., lower looking at FIG. 2) face applied against the corresponding face of the aperture. The inner face of tongue 4 defines, with the other face of the aperture, a slot through which a blade 19 and, as shown, a forward part of a plate-like blade-supporting carriage 14 pass.

A central screw 6 tightly holds the two shells 1 and 2 edge-to-edge against one another, these shells already being held together in nose 4 by the above-mentioned arrangment.

A button 5 slidably mounted in an upper slot of the handle controls a blade-moving device.

On a tapered front part of the handle, a button 7 serves as brake for blade-supporting carriage 14 enabling, by a thumb pressure, lateral shaking of the blade 19, when it protrudes from slot 4, to be avoided.

The rear end of the handle has a bore 8 passing right through the two shells 1 and 2 and adapted to permit the passage of a ring, cord or any other device for suspending the knife.

A press stud or boss 9 protruding from a part of the said rear end enables, when pressed, opening of a clip 10 engaging with a notch 11 to lock a spare-blade magazine 12 in a closed position. The magazine 12 can then pivot about an eyelet 13 receiving two facing studs each integral with and protruding inwardly from a shell 1, 2 and holding magazine 12 onto the handle. In its closed position, magazine 12 does not protrude from the handle apart from the boss 9 which, being located outside the points of gripping in a hand, does not risk being unwantedly operated.

FIGS. 3 and 6 show the blade-supporting carriage 14 movement of which is controlled by button 5 to which it is connected by a spring blade 15 terminating with a T-shaped catch 16 whose two unequal arms pass all the way through button 5. These two arms come to engage in corresponding notches of a rack 17 provided in each shell 1, 2 thereby setting the position of carriage 14 and consequently the length of blade 19 protruding from slot 4. The notches of rack 17 enable a choice, from the various positions of blade 19, of that which is best suited for the thickness of material to be cut.

To avoid that the lateral play required to facilitate the manoeuvre of pressing button 5 to make catch 16 move from one notch of rack 17 to another is not too great, an elongate protecting plate 18 slidably fitted about button 5 slides with it along grooves 18 provided for this purpose in the shells 1, 2 of the handle.

An interchangeable trapezium-shaped blade 19 whose longer parallel edge is a cutting edge is held in place in carriage 14 by two notches 20, 21 disposed symmetrically in the shorter parallel edge in a manner to enable the blade 19 to be held in either of two orientations relative to carriage 14, whereby the blade can be turned around to use both cutting points. A corresponding catch 22 of carriage 14 engages in either of notches 20 or 21 according to whichever face of blade 19 is used.

FIGS. 5 and 6 show the metal plate forming the blade-supporting carriage 14 including parallel edge flanges 23, 24 bent perpendicularly to the plane of blade 19 to hold the latter in the working position, and ensure guiding of the assembly by means of grooves 25, 26 provided for this purpose in the female shell 2 of the handle, and a narrow channel defined between facing ribs 27a, 27b and 28a and 28b of the shells 1 and 2 respectively.

Catch 22 is provided on a resiliently deformable tongue 30 integral with the main face of carriage 14 and including a separate portion 24' of the lower edge flange 24. When button 5 and carriage 14 are in the forwardmost position (shown in FIG. 3) the enlarged inner end of button 7, when depressed, presses against only portion 24' of flange 24 whereby tongue 30 is deformed (to the right looking at FIG. 5) into a corresponding opening 29 in rib 28b to disengage catch 22 from the notch 20 or 21, since the blade 19 remains held against the undeformed main part of carriage 14. In this position therefore, the blade 19 can be removed and turned around or replaced by another blade.

When a blade is fitted and the button 5 is moved rearwards into another notch of rack 17, the carriage and blade 19 are retracted by a corresponding amount. If the button 7 is now pressed in, it acts against flange 24 and the entire carriage 14, and with it blade 19, tend to tilt very slightly and the blade 19 is pressed against tongue 14. This prevents any rattling or shaking of blade 19 during use, and consequently reduces wear to the blade outlet slot. Moreover, longitudinal movement of carriage 14 and blade 19 is braked, and the positioning of arms 16 of button 5 in the chosen groove of the rack 17 is improved to such an extent that if the button 5 should be unwantedly pressed during cutting, the braking effect produced by button 7 practically eliminates any possibility of the blade 19 unwantedly retracting by a notch. The button 7 is so positioned that such a pressure can easily be exerted during use of the knife. Consequently, the knife can be safely used to cut a material to a particular depth (for example to avoid cutting a backing material) by adjusting the blade position and applying the inclined nose 4 against the material during cutting.

The principal advantages of the described embodiment are as follows.

Since the nose end of the knife with the blade outlet slot is in a single piece integral with one of the shells of the handle, the slot can no longer open out under the effect of lateral efforts made necessary by the cutting operation.

The blade positioning device is controlled by means of a press button with a particularly accessible lateral disposition. Its location outside the points of bearing of the hand on the handle enables false manoeuvres to be avoided, even during difficult cutting involving large efforts.

The device for braking and removing the blade is provided in a manner to avoid a false manoeuvre from causing unwanted removal or withdrawal of the blade. For this purpose, the braking button is arranged on the front sloping face of the handle at the blade end. In the working position with the blade withdrawn, the thumb rests naturally on the said button which thus serves as a brake, reinforcing the positioning of the blade-carrying carriage in the chosen notch of the rack and eliminating lateral shaking of the blade.

The moving forwards and backwards of the blade-carrying carriage is facilitated by the provision of the handle-forming shells in plastics material, which material enables reduction of the coefficient of friction of said carriage in its guide grooves, while ensuring a self-lubrification.

The provision on the rear end of the handle of the press-stud for locking the spare blade magazine also avoids the risks of unwanted opening thereof during cutting.

Claims

What is claimed is:

1. A hollow knife handle comprising first and second elongate shell members secured together generally edge-to-edge to define therebetween a blade-receiving cavity, in which the first member has at one end a slot-like aperture and an integral oval shaped female portion extending continuously around said aperture and defining a nose end of the handle, said slot-like aperture communicating with and being in alignment with said blade receiving cavity, and the second member has a male end part inserted in said aperture to cooperate with the oval portion to define therein a blade outlet slot.

2. A knife handle according to claim 1, in which said male end part consists of a flat tongue having an outer face applied against one face of said aperture and an inner face defining, with the other face of said aperture, said blade outlet slot.

3. A knife handle according to claim 1, further comprising a blade-supporting carriage in the form of a plate having a planar main part with parallel edges protruding perpendicular to one face of the main part, means for releasably securing a blade in said carriage against said main part, means for mounting the carriage within said cavity with said main part disposed parallel to the blade outlet slot and said edges of the carriage parallel to the longitudinal direction of the handle for a sliding movement of the carriage along the longitudinal direction of the handle towards and away from said blade outlet slot, and means for releasably holding the carriage in selected positions relative to the handle.

4. A knife handle according to claim 3, in which said blade securing means include a resilient tongue integral with said plate, a projection on said tongue normally adopting a blade-securing position protruding from said one face of the main part but being resiliently deformable to a blade-disengaging position in which it does not protrude from said one face of the main part, and means for moving the projection to the blade-disengaging position when the carriage is disposed in a given position relative to the handle.

5. A knife handle according to claim 4, in which said means for moving the projection include a push button disposed on a part of the handle tapering towards said nose end thereof.

6. A knife handle according to claim 5, in combination with a blade held in said carriage, in which when the carriage is disposed in positions other than said given position said button is adapted to move the carriage and blade together to apply the blade transversely against one face of the blade outlet slot.

7. A knife handle according to claim 3, in combination with a blade, in which the blade is in the shape of a trapezium and includes on a shorter parallel edge thereof two symmetrical notches adapted to cooperate with said projection to hold the blade in either of two orientations relative to the carriage.

8. A knife handle according to claim 7, in which the blade outlet slot is inclined obliquely in relation to the longitudinal direction of the handle in the direction opposite to the non-parallel edge of a held blade protruding from the blade outlet slot, the longer parallel edge of the blade being a cutting edge.

9. A knife handle according to claim 1, comprising a spare-blade magazine pivotally connected to the handle for movement between a first position flush with the handle and a second protruding position by means of an eyelet in the magazine engaging on inwardly facing studs in the first and second shell members.

10. A knife handle according to claim 9, comprising a press-stud cooperating with a clip for releasably locking the magazine in the first position, said press-stud being disposed on a rear end of the handle opposite to said nose end.