GB2206832A

GB2206832A - A knife

Info

Publication number: GB2206832A
Application number: GB08716693A
Authority: GB
Inventors: Tatsushige Mayama
Original assignee: Nippon Tenshashi KK
Current assignee: Nippon Tenshashi KK
Priority date: 1987-07-15
Filing date: 1987-07-15
Publication date: 1989-01-18
Anticipated expiration: 2007-07-15
Also published as: GB8716693D0; GB2206832B

Abstract

A knife, of the type wherein successive segments of a segmented blade can be broken off, has an elongate body 20 having a slot (26, Fig 2) for slidably receiving the segmented blade 40. An adjuster element 2 is connected by a lug 7 to the blade. The adjuster element 2 has a pair of lugs 3 and 4 extending to the exterior of the body through a slot 27. The upper and lower edges of the slot 27 includes a plurality of recesses 28. The adjuster element further includes pairs of opposed teeth 5, 6 acting as opposed pawls when the teeth 5, 6, are located in recesses 28. The teeth lock the adjuster element and hence the blade in position. The adjuster element is formed so that depression of one or other of the lugs 3, 4 urges the respective pawl to disengage from the recess 28 to allow sliding movement of the adjuster element to retract or extend the blade. Preferably, the adjuster element comprises a unitary body formed from plastics material. <IMAGE>

Description

A RNF~ This invention relates to a knife of the type wherein successive predetermined segments of the knife blade can be broken off, in particular, the invention relates to an improvement in the locking and sliding arrangement to the successive movement of the segmented blade.

A knife of the aforementioned type is known from Japanese Utility Model Provisional Publication No.136075/1983.

This knife comprises a body receiving a slider member equipped with a coupling lug for connection to a segmented blade. A single elastic hook is provided on the slider member which can be engaged into one of a large number of stopper recesses formed on the body. An adjuster mounted for movement on the slider member is movable from a neutral position to a forward or reverse sliding position and also includes a protusion to hold the elastic hook in its engaging position with a stopper recess whilst the adjuster is in a neutral position but when the adjuster is moved from its neutral position, the urging of the elastic hook into engagement with the stopper recess is removed. A restoring elastic body is interposed between the slider member and the adjuster to urge the adjuster to its neutral position.

It can be seen that this prior art device requires the restoring elastic body to bring the adjuster to its neutral position and also requires the binding protusion to hold the elastic hook in its state of engagement with the stopper recess. Consequently, this prior art knife requires rather a large number of components so that its structure is relatively complex increasing the resultant manufacturing costs, and the complexity thereof increases the production costs.

It is an object of the present invention to overcome the aforementioned problem and to provide a knife of a simplified structure with a relatively reduced number of component parts.

According to the invention there is provided a knife of the type wherein successive segments of a segmented blade can be broken off, the knife comprising an elongate body having a slot for slidably receiving the segmented blade; a groove aligned with said slot; an adjuster element slidably received in said groove and connected to the blade in said body whereby sliding of the adjuster element along the groove produces a corresponding retraction or extension of the blade to or from the body; the knife including a pluraity of recesses aligned with said groove and the adjuster element having a pair of opposed pawls resiliently biased to engage with a respective recess tc lock the position of the adjuster element and the blade, the adjuster element including release means for overcoming the resilient bias on each pawl to disengage the respective pawl from the recess whereby retraction or extension of the blade can occur.

Thus, the opposed pawls are resiliantly biased to engage with a respective recess so as to lock the position of the blade when the knife is out of operation or when the actual cutting action is taking place. It will be apparent that with this simplified arrangement, the blade is firmly locked in position. In order to retract or extend the segmented blade, the release means is operated by a user to overcome the bias on the appropriate pawls whereby the adjuster element and hence blade can be moved. The bias on only one pawl needs to be overcome since the sliding action in one direction will not be resisted by one of the pawls because of their opposed mounting. Consequently, the knife of the present invention requires few component parts saving on both manufacturing costs and assembly costs.

Preferably, the opposed pawls have a hook shaped ending.

In this way, the bias of only one pawl needs to be disengeged for movement of the blade in one of its dirctions since movement of the adjuster element will cause the hook of the other pawl to ride over the recess.

Conveniently, te adjuster element comprises - body formed, preferably, from a plastics material. Thus, the adjuster element can be formed from a single moulding of plastics material. This makes production of the knife both simple and cost effective.

Conveniently, the adjuster element comprises an elongate generally planar member having connection means at one end connected to the segmented blade and said pawls located at the other end, the member also having press elements extending through the groove and formed whereby a user press on the pressure elements moves the planar member and the pawls sufficiently to disengage them from said recesses. This allows for a particularly simple plastic moulding.

Conveniently, the recesses are provided on said body immedidately adjacent either side of said slot and said pair of opposed pawls are twinned whereby two opposed pawls are resiliently biased into the recesses on one side of the slot and two opposed pawls are resiliently biased into the recesses on the other side of said slot.

This construction gives a much more solid locking of the blade. In an alteranative embodiment of the invention, the aforementioned adjuster element can be formed of metal sheet material.

It wil' b npparent th2' far the 2purpose of the present invention, the tern pawl is to be construed as an element preventing relative sliding movement between it and an object in one direction and allowing that relative sliding movement in an opposing direction.

Examples of the present invention will now be described with reference to the acompanying drawings, in which: Figure 1 illustrates a partly broken away side view of a knife embodying the present invention.

Figure 2 illustrates a cross-sectional plan view of the knife shown in figure 1.

Figure 3 illustrates the operation of the adjuster element of figures 1 and 2 to achieve extension of the blade.

Figure 4 illustrates the operation of the adjuster element of figures 1 and 2 to achieve retraction of the blade.

Figure 5 illustrate an enlarged view of one embodiment of the adjuster element.

Figure 6 illustrates an enlarged view of an alternative embodiment of the adjuster element.

Figures 7 to 9 illustrate further embodiments of the adjuster element.

Referring to Figures 1 and 2, a knife 1 comprises an elongate hollow body 20 which combined define an upper wall 23, a lower wall 1 24 and side walls 2' and 2. An internal slot 26 is defined by these walls. The side wall 21 includes the groove 27 running aligned with the slot 26. The upper and lower edges of the groove 27 have a plurality of indentations or recesses 28 as illustrated.

Referring to Figure 5, an adjuster element 2 comprises a substrate 8 with a lug 7 at one end thereof and a T shaped pressure element 9 at the other end thereof. The element 8 is not completely planar but has a slightly bent cross-section as shown in Figure 2. In addition the substrate has a hollow 15 to and flexing of the substrate. The element 9 extends as a T piece from the plate 8, the side pieces of the T, 10 and 12 defining a solid element having hooked or toothed members 5 and 6 at the end thereof. These hooks are in opposition in their function and face inopposing directions. The T piece 9 also carries a pair of lugs 3 and 4 located so that pressure on the lugs in a direction generally parallel to the upright of the T bends the side pieces 10 and 12 in that direction. Each hook comprises an upright face 14 and a face 17 inclined to the horizontal as illustrated.

The adjuster element 2 has the lug 7 is inserted through an aperture 41 of a known segmented blade 40. The blade and adjuster member 2 can then be inserted in the body 20. The slot 26 is formed to snugly receive the blade where^-s the groove 27 is formed to rece ve the gs 8 and 4. When the adjuster element is inserted into the slot 26 the lugs 3 and 4 protrude through the slot 27, but the side pieces 10 and 12 are located in the slot so that the teeth 5 and 6 enter the recesses 28 as shown in Figure 2.

In order to extend the blade, that.is to say to move the blade in the left hand direction of Figure 1, the lug 3 is dpressed in a direction interior to the knife 1. This causes the teeth 5 to be released from recesss 28 where it was located. Subsequent sliding pressure on the adjuster element 2 along the groove 27 in left hand direction of Figure 1 allows movement of the blade since the other teeth 6 have the inclined face 17 which slides out of the recess 28 when the adjuster element is moved in this direction (see Figure 3). In order to retract the blade, that is to say to move the blade in the right hand direction of Figure 1, the lug 4 is depressed in a dirction interior to the knife 1. So as to release teeth 6 from the recesss 28 where they were located.As the teeth 5 are in oppostion to the teeth 6, movement of the adjuster element in a left hand direction causes the teeth 5 to slide out of the appropriate recess 28 allowing movement in the right hand direction. It will be apparent taht teeth 5 and 6 function as a pair of opposed pawls.

It can therefore be seen that the operates in a step wise manner with the teeth 5 and 6 locating in each subsequent recess 28. As the teeth 5 and 6 are provided in opposition, once they are located, retraction or extension movement of the adjuster element 2 is firmly prevented so that the blade 40 is locked in position. Only when one or other of the lugs 3 or 4 is depressed can the required retraction or extension motion be effected. The adjuster element 2 has a simple construction particulary suitable for comprising a unitary body formed from plastics material. Although the recesses 28 are illustrated as extending through the wall 21, it will be apparent that these recesses could be hidden on the interior surface of the wall.

The emodiments shown in Figures 1 to 4 have the teeth 5 and 6 arranged so that the lug nearer the blade is depressed to allow retraction of the blade and the lug further from the blade is depressed to allow extension of the blade. Figure 7 illustrates an alternative emodiment wherein the teeth 5 and 6 are reversed so that the lug nearer the blade is depressed to allow the extension of the blade and the lug furthest from the blade is depressed to allow retraction of the blade. Also, the embodiments of Figures 4 and 7 illustrate the teeth facing away from one another and in opposition, however, as shown in figures 8 and 9, it is possible to have the teeth facing one another and still in opposition.

Figure 6 illustrates an alternative embodiment of the adjuster element 2 wherein the pressure element 9 is modified so that lugs 3 and 4 are not a solid connection to the upper surface of the element 9 but instead form a bridge thereover and connect to the teeth 5 and 6 respectively, as illustrated. This provides a lighter and cheaper adjuster element. It will be apparent to a person skilled in the art that the present invention encompasses various modifications and alternatives, not described, the production thereof being apparent to the person skilled in the art.

The present invention provides a knife of the type wherein successive segments of the knife can be broken off, which knife has a reduced number of parts relative to prior art knives. The operation of the knife is particulary simple, being mechanically quite direct and giving a good tactile feel to the operation of extension or retraction of the blade. Moreover, when the blade position is finalised, the construction of the knife ensures that the blade is firmly fixed in this position be it retracted or extended.

Claims

CSAIM5

1. A knife of the type wherein successive segments of a segmented blade can be broken off, the knife comprising:an elongate body having a slot for slidably receiving the segmented blade; a groove aligned with said slot; an adjuster element slidably received in said groove and connected to the blade in said body whereby sliding of the adjuster element along the groove produces a corresponding retraction or extension of the blade to or from the body; the knife including a plurality of recesses aligned with said groove and the adjuster element having a pair of opposed pawls resiliently biased to engage with a respective recess to lock the position of the element and the blade, the adjuster element including release means capable of overcoming the resiliently bias of each pawl to disengage the respective pawl from the recess whereby retraction or extension of the blade can occur.

2. A knife as claimed in Claim 1 wherein each pawl comprises one or more inclined teeth.

3. A knife as claimed in Claim 1 wherein each pawl comprises one or more hooks.

4. A knife as claimed In Claim 2 whereby the teeth on salsa pawls either point in opposing dirctions or face one another

5. A knife as claimed in Claim 3 wherein the hooks on said pawls either point in opposing directions or face one another.

6. A knife as claimed in any preceding claim wherein the adjuster element comprises a unitary body.

7. A knife as claimed in Claim 6 wherein the adjuster element comprises plastics material.

8. A knife as claimed in any one of Claims 1 to 5 wherein the adjuster element consists of metal.

9. A knife of the type wherein successive segments of a segmented blade can be broken off, substantially as herein described with reference to the accompanying drawings.