GB2269128A - Knife with automatic blade changing mechanism - Google Patents

Abstract

A knife (10, fig 2) formed from two elongate body shells 14, 16 includes a mechanism 20 for successively feeding a plurality of cutting blades 22 as required from a supply 34 held in a magazine 18 to a position of use. The mechanism comprises a reciprocable plate 46 having an arresting finger 5 to collect a blade from the supply and to deliver the blade to a position of use. The plate co-operates with retractable support surfaces to limit movement of the tool piece in use and has spring actuated cams 54, 56, 58, 60 to alter the position of the support surfaces when the reciprocal plate is retracted to collect a further blade from the supply so that the used blade is released from the plate into a storage chamber 32. <IMAGE>

Description

A KNIFE WITH AN AUTQETt bAD C1iANGIN MECHANISM This invention relates to a hand held tool having a supply of tool pieces which can be fed as required to a position of use and in particular to a knife in which individual blades of the knife can be replaced from the supply.

The invention provides, in a hand held tool a mechanism, for successively feeding a plurality of tool pieces as required from a supply held by the tool to a position of use, said mechanism comprising transfer means to collect a tool piece from the supply and to deliver said article to a position of use, said mechanism co-operating with support means to limit movement of the tool piece in use and having means to alter the position of said support means when said transfer means is actuated to collect a further tool piece from the supply so that the used tool piece is released from the transfer mechanism.

According to a feature of the invention, said transfer means may comprise a reciprocal element having tool piece arresting means for holding a tool piece in cooperation with said support means when the transfer means is in a first position thereby presenting said tool piece in a position for use and for collecting a tool piece from said supply when the transfer means is in a second position and wherein said support means is shifted automatically consequent upon movement of said transfer means from the first to the second position to allow disengagement of a used tool piece from said transfer means.

According to another feature of the invention, said transfer means may comprise a reciprocal plate which plate has cam actuating means to shift said support means during reciprocal movement of said plate.

In constructions where the transfer means is a said cam actuating means may comprise resilient elements and said support means are resiliently mounted for movement transversely of the reciprocal plate by pivotal cams disposed in the path of movement of said resilient elements.

Preferably, said supply comprises a magazine disposed in superposed relationship with said transfer plate said magazine having means to urge a supply of tool pieces towards the path of movement of the transfer plate and positioned so that said arresting means can engage with a leading tool piece present in said supply.

It also is a preferable feature of the invention that the tool piece urging means comprises a resilient element disposed within a chamber for accommodating said supply and closed by said transfer plate.

The magazine may comprise a second chamber disposed adjacent said support means to receive tool pieces discharged from said transfer plate. In constructions where a second chamber is provided resilient means may also be provided to urge a tool piece into contact with said support means and to facilitate discharge of a tool piece into said second chamber when the support means are shifted out of their supporting position.

According to another feature of the invention, the transfer plate and said magazine may be disposed in superposed relationship between a pair of body shells, said shells being connected to provide a body such that a tool piece may be presented for use from one end of the body and said magazine and transfer plate can be manipulated from the opposite end- of said body. In constructions where this feature is adopted, the transfer plate may have locking and release means for co-operation with said body adjacent said opposite end thereof.

In some other constructions, the magazine may also have locking and release means for co-operation with said body adjacent said opposite end thereof.

In the preferred form of the invention, the tool is a knife and the tool pieces are replaceable knife blades.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an exploded perspective view of a knife according to the invention showing the components thereof disassembled; Figures 2a-2f is a sequence of views illustrating the loading and recharging of individual cutting blades of the knife; and Figures 3a-3c illustrate a part of the blade changing mechanism of the knife.

Referring to the drawings, a knife 10 has a body 12 comprising pair of dished elongate body shells 14, 16, respectively which are adapted to be secured together to close the longitudinal peripheral edges of the body.

The body shells define between them a cavity in which a blade magazine 18 and a blade changing mechanism 20 is accommodated in superposed relationship.

The longitudinal peripheral edges of the body shells 14, 16 gradually diminish in height at one (the forward) end of the body to provide a slit in which a blade is supported in position for use so that a forwardly projected part of a blade 22 includes a length of its cutting edge. At its opposite tail end the body presents a larger opening through which both the blade magazine 18 and the blade changing mechanism 20 are slidable in use. The tail end of the body has side recesses 24, 26 formed by cut-away portions of the upper and lower body shells leaving vertically spaced central tongues 28 and 30 respectively, which provide support surfaces for the slidable magazine and blade changing mechanism.

The blade magazine 18 also is in the form of a dished elongate body having a forward chamber 32 which receives used blades which have at least a part of the overall length of their cutting edges dulled. The blade magazine further includes a feed chamber 34 from which fresh blades are fed to protrude forwardly of the body for use.

At its trailing end the blade magazine 8, which may be an injection moulded Acetal, is furnished with an integral resilient locking and release portion 36. The locking and release portion includes flat spring elements 38 which normally are biased outwardly so that they are urged against wall portions of the body at the tail end thereof to hold the magazine locked to the body when in a fully inserted position. The locking and release portion 36 also includes outwardly of the flat spring elements a pair of manipulating flats 40 which are accommodated in the recesses 24, 26 when the magazine is fully located within the body.In order to release the magazine so that it can be withdrawn from the body the manipulating flats are pressed inwardly towards one another thereby to compress the flat spring elements and release them from the body so that the magazine is free to slide relative to the body (Figures 1 and 2a).

A stack of fresh blades 'B' is held in the feed chamber 34 which also contains a feeder spring 42. Spring 42 is a resilient plate which normally is disposed beneath the stack of blades to urge the blade stack upwardly against the underside of the blade changing magazine (Figure 1). As best seen in Figure 2b the blades are of trapizodal form with the longer of the edges providing the cutting edge of the blade. The opposite edge of the blade is formed with a pair of notches 'n' which co-operate with integral posts pl, p2 formed on a sidewall of the feed chamber to retain the blades located in the feed chamber until they are to be fed forward for use. In order to retain the blade stack in the feed chamber during re-charging of the magazine a retaining slide 44 which is moveable longitudinally of the chamber is moved to overlie the uppermost blade in the stack. The loaded magazine is fully inserted into the body to be in the correct position for co-operation with the blade changing mechanism.

The blade changing mechanism 20 comprises a substantially flat plate 46 adapted to overlie the blade magazine within the body. Mechanism 20 has at its trailing end a locking and release portion 48 similar in construction and function to locking and release portion 36 described above. At its leading end the plate 46 is bifurcated to provide a pair of forwardly projecting arms 46a, 46b. Arm 46a terminates in a resilient finger 50 which carries at its free end a stud 52 sized to be located in one of the blade locating notches 'n'.

Normally the plate is fully insert into the back so that the locking and release mechanism is locked to the body and a blade is held supported (as further described) at the opposite end of the plate so that a portion of its cutting edge is presented for use at the forward end of the body.

When the locking and release portion 48 is manipulated to release the blade changing mechanism, the mechanism is retracted relative to the body (Figure 2c) in order to collect the uppermost blade from the supply stack accommodated in the feed chamber. As best seen with reference to Figure 1 the bifurcated arms 46a, 46b of the plate have a pair of juxtaposed integral spring elements 54 and 56 which have both relatively stiff and relatively flexible walls. These spring elements are arranged to co-operate witch pivotal cams 58 and 60 respectively which depend from the inner face of the upper body shell 14.

In order to describe a blade change operation it will be assumed that the blade change mechanism has been operated once to present a blade for use whereby the mechanism is fully inserted into the housing as shown in Figure 2d. In this situation the blade notch 'n' is engaged by the stud 52 and has those lengths of its cutting edge and notched edge supported internally of the body on a pair of similar opposed sprung flange members 62, 64. Flange members 62 and 64 are located on respective ones of a pair of carriers 66, 68 formed integrally with the longitudinal walls of the lower body shell. The flange members have end parts 'r' which are returned about the ends of the carriers and allow the flange members to flex relative to the carriers. The upper peripheral edges 'el' of the forward chamber 32 are stepped down relative to the upper peripheral edges 'e2' of the feed chamber.Guide flanges 70, 72 which are inwardly directed parts of the flange members seat on the longitudinal edges 'el' of the forward chamber such that the upper surfaces of the guide flanges are substantially flush with the peripheral edges 'e2' of the feed chamber.

The guide flanges provide surfaces over which a blade slides during feed for use movement and provide support surfaces for the internal lengths of the cutting and ndtched edges of the blade when it is located in a position of use and for the forward end of the plate 20.

When the exposed length of the cutting edge of a blade becomes dulled through use, the locking and release portion 48 of the blade change mechanism is manipulated and the mechanism retracted from the body. Since the blade is retained by the finger stud 52 it too is drawn rearwardly and thereby retracted into the body. When the blade is located on the guide flanges within the forward chamber it is urged into contact with the guide flanges by a leaf spring 74 which extends downwardly from the upper body shell 14 intermediate the pivotal cams and bears against the uppermost surface of the blade. The pivotal cams are arranged to lie in the longitudinal path of movement of the spring elements 54, 56 carried by bifurcated arms 46a, 46b so that the rearward facing relatively stiff walls of the spring elements abut the cams and cause them to pivot outwardly (Figure 3b).The cams are positioned so that their free ends are pivoted into abutment with the sprung flange members 62,64. When the cams are fully rotated the relatively flexible sides of the spring elements flex to allow passage of the springelements therebetween (Figure 3c) and the cams are urged against the guide elements with sufficient force as to cause outward flexing of the sprung flange members 62, 64.

This outward flexing results in the blade being denied the support of the flanges 70, 72 which are moved beyond the opposed supported edges of the blade. The blade is therefore disengaged from plate 46 and urged downwardly into the forward chamber 32 by the leaf spring 74 to a location below the flange members and retained therein by the force transmitted by spring 74.

Once the spring elements have passed through the space between the cams, the force urged on the cams is relaxed so that the flanges can return to their support positions.

As the blade changing mechanism is further retracted a fresh blade present at the uppermost position in the feed chamber is arrested by engagement between the finger stud 52 and blade notch 'n'. Naturally, the clearance between plate 46 and peripheral edges e2 is such as to allow for accommodation of a single blade therebetween. As the blade changing mechanism is returned into the body of the knife the spring elements again impinge upon the pivotal cams and flex to pivot them away from the guide elements into a more parallel altitude (Figure 3c) so that they are again positioned in the path of movement of the spring elements when the blade changing mechanism is next retracted.

This cycle of events is repeated for successive blades to be fed from the feed chamber to a position of use.

In due course the supply of fresh blades in the feed chamber will become exhausted so that when the blade change mechanism is returned, no blade emerges from the leading end of the body (Figure 2e). The magazine may then be released and withdrawn from the body as previously explained and the blades held in the forward chamber can then be transferred by inversion to the feed chamber so that the previously unused length of cutting edge of each transferred blade will be presented for use when the blade change mechanism is operated to feed successive blades (Figure 2). Of course, if the blades accommodated in the forward chamber having cutting edges which are dulled along the whole of their lengths then the used blades may be discarded and a fresh stack of blades loaded into the feed chamber. In order to facilitate transfer or discard of the blades from the forward chamber the floor of the chamber is formed with an aperture 82 so that ready access to the blades is possible.

It will be appreciated that when a blade is disposed in a position of use it is partially supported upon the guide flanges 72, 72 which also provide support for forward parts of the flat plate 42. Plate 46 also has a central longitudinal runner 84 upstanding from its upper surface and which is guided between a pair of guide rails (not shown) provided in the upper body shell in order to keep the blade change mechanism stable when the blade is in use so that the blade is adequately supported.

Outer shell coverings 86, 86 which may be formed from silicon rubber are provided to improve handling of the knife.

Claims (13)

1. In a tool a mechanism for successively feeding a plurality of tool pieces as required from a supply held by the tool to a position of use, said mechanism v .c comprising a tool holder for collecting a tool piece from the supply and delivering said tool piece to a position of use and means for disengaging said tool piece from the tool holder during return travel of the tool holder to said supply so that the next succeeding tool piece can be engaged and fed by the tool holder.

2. In a hand held tool a mechanism for successively feeding a plurality of tool pieces as required from a supply held by the tool to a position of use, said mechanism comprising transfer means to collect a tool piece from the supply and to deliver said tool piece to a position of use, said transfer means co-operating with support means to limit movement of the tool piece in use and having means to alter the position of said support means when said transfer means is actuated to collect a further tool piece from the supply so that the used tool piece is released from the transfer mechanism.

3. A hand held tool according to claim 2 wherein said transfer means comprises a reciprocal element having tool piece arresting means for holding a tool piece in co-operation with said support means when the transfer means is in a first position thereby presenting said tool piece in a position for use and for collecting a tool piece from said supply when the transfer means is in a second position and wherein said support means is shifted automatically consequent upon movement of said transfer means from the first to the second position to allow disengagement cf a used tool piece from said transfer means.

4. A hand held tool according to claim 2 or claim 3 wherein said transfer means comprises a reciprocal plate which plate comprises cam actuating means to shift said support means during reciprocal movement of said plate.

5. A hand held tool according to claim 4, wherein said cam actuating means comprise resilient elements and said support means are resiliently mounted for movement transversely of the reciprocal plate by pivotal cams disposed in the path of movement of said resilient elements.

6. A hand held tool according to claim 5, wherein said supply comprises a magazine disposed in superposed relationship with said transfer plate said magazine having means to urge a supply of tool pieces towards the path of movement of the transfer plate and positioned so that said arresting means can engage with a leading tool piece present in said supply.

7. A hand held tool according to claim 6, wherein said tool piece urging means comprises a resilient element disposed within a chamber for accommodating said supply and closed by said transfer plate.

8. A hand held tool according to claim 7, wherein said magazine comprises a second chamber disposed adjacent said support means to receive tool pieces discharged from said transfer plate.

9. A hand held tool according to claim 8, wherein resilient means are provided to urge a tool piece into contact with said support means and to facilitate discharge of a tool piece into said second chamber when the support means are shifted out of their supporting position.

10. A hand held tool according to any of claims 6 to 9 wherein said transfer plate and said magazine are disposed in superposed relationship between a pair of body shells, said shells being connected to provide a body such that a tool piece may be presented for use from one end of the body and said magazine and transfer plate can be manipulated from the opposite end of said body.

11. A hand held tool according to claim 10 wherein said transfer plate has locking and release means for co-operation with said body adjacent said opposite end thereof.

12. A hand held tool according to claim 11 wherein said magazine has locking and release means for cooperation with said body adjacent said opposite end thereof.

13. A hand held tool according to any of the preceding claims wherein said tool is a knife and said tool pieces are replaceable knife blades.