SAFETY KNIFE

Abstract

 A safety knife is described comprising a handle 12, a head 14 and a blade 26 carried by the head 14, wherein the head 14 and the handle 12 are removably connected to one another.

Description

[0001] This invention relate to a knife, and in particular to a safety knife of the type in which access to a cutting edge of a blade of the knife, in use, is restricted so as to reduce the risk of injury to a user thereof.

[0002] One form of safety knife in widespread use comprises a handle of moulded plastics material form, the handle being integrally formed with a head within which a metallic material blade is encapsulated. The head is formed with passages, each of which extends to a portion of the cutting edge of the blade. In use, a material to be cut is introduced into one of the passages, and relative movement between the knife and the material to be cut draws the material to be cut to a position in which it engages the part of the cutting edge of the blade that extends across the passage, whereon it is cut by the blade. The dimensions of the passage are chosen so that, whilst the material to be cut can enter and move along the passage and engage the cutting edge of the blade, the passage is sufficiently small that a user cannot introduce one of his or her fingers into the passage by a distance sufficient for it to engage and be cut by the cutting edge of the blade. The risk of injury to a user is thus reduced compared to situations where a user is using a traditional exposed blade knife.

[0003] It is known, for example from GB2414209, for the opposing faces of the head to include channels that extend from the cutting edge of the blade, as continuations of the passage, the channel on one face of the blade being non-aligned with that on the opposing side of the blade. The channels serve to displace parts of the cut material such that one cut edge of the material cut by the blade is non-aligned with the other cut edge thereof, such displacement of the cut parts of the material easing the passage of the knife through the cut material, reducing the risk of the knife becoming jammed, especially when cutting relative stiff materials such as thick cardboard.

[0004] One disadvantage with a knife of the type described hereinbefore is that, once the blade has become worn or damaged, as the blade is encapsulated within the plastics material moulded head part of the knife, replacement of the blade is not possible. The knife, as a whole, is thus disposed of and replaced. Recycling of the materials of the knife is impeded as the presence of the encapsulated blade results in the knife being of a plurality of materials that require processing separately but that cannot readily be separated.

[0005] It is an object of the invention to provide a knife in which at least some of the disadvantages associated with a known knife are overcome or are reduced.

[0006] According to the present invention there is provided a safety knife comprising a handle, a head and a blade carried by the head, wherein the head and the handle are removably connected to one another. The head and the handle are preferably slidable relative to one another. By way of example, one of the head and the handle may be provided with a channel of a re-entrant form, the other of the head and the handle including a projection shaped for receipt within the channel. Conveniently, the channel is formed in the handle, and the projection is formed on the head. The channel and projection are preferably of dovetail shape or form. It will be appreciated, however, that other shapes such as T-shapes may be used. Other shapes that could be used include projections with parts of generally cylindrical form with circular or oval cross-sectional shapes.

[0007] The channel is preferably closed at one end. As a result, the closed end of the channel can serve as a stop, limiting relative movement between the head and the handle. The channel, and the closed end thereof, are preferably orientated relative to the direction of movement of the knife in normal use, such that the projection is pushed towards the closed end of the channel during cutting movement of the knife. As a result, separation of the head from the handle during cutting is avoided.

[0008] The blade may be moulded into the head so as to be encapsulated thereby. Alternatively, the head may be of a design allowing the head to be opened to allow removal and replacement or refitting of a blade thereto once separated from the handle.

[0009] An arrangement of the type described hereinbefore is advantageous in that, upon wear or damage of the blade occurring, the head can be removed from the handle. If the blade is encapsulated within the head, then only the head and blade require disposal or recycling, reducing waste compared to a traditional knife. Where the head is designed to allow removal and replacement or refitting of the blade, then after replacement or refitting of the blade, the head can be refitted to the handle, and just an old, worn blade may require disposal or recycling. It will be appreciated, therefore, that the knife is advantageous in that parts thereof can be used over an extended period of time and so waste is reduced. Furthermore, when parts thereof can no longer be used, recycling thereof is simplified, at least in certain embodiments of the invention.

[0010] The head is preferably shaped to define a passage across which part of a cutting edge of the blade extends, the passage preferably being of a width sufficiently small that a users finger is unable to contact the cutting edge of the blade. By way of example, a width of the passage in the region of the cutting edge is preferably less than 10mm, and is more preferably less than 8mm. The head may be provided with two or more such passages across which different parts of the cutting edge of the blade extend.

[0011] The head is conveniently of two part form, the parts thereof being snap fitted to one another or otherwise securable to one another to hold the blade captive therebetween. Alternatively, the head may be of one piece form, including a flexible part serving as a hinge to allow other parts thereof to be moved to a position in which they overlay one another and hold the blade captive therebetween. Preferably, the projection is formed from the parts of the head in combination. As a consequence, separation of the parts of the head to allow removal of the blade from the head can only be undertaken once the head has been removed from the handle.

[0012] The blade is preferably fitted to the head in such a manner that the part of the cutting edge thereof exposed by the passage is offset from a centreline of the blade. As a result, when the blade becomes worn, upon removal of the head from the handle and opening of the head to access the blade, the blade may be reversed so that a different part of the cutting edge is exposed at the passage upon subsequent reassembly of the knife. It will be appreciated that in such an arrangement, an increased length of the cutting edge of the blade may be used before disposal of the blade is required.

[0013] The invention will further be described, by way of example, with reference to the accompanying drawings, in which:

Figures 1 and 2 are side views of a knife in accordance with an embodiment of the invention;

Figures 3 and 4 are front and rear views, to an enlarged scale, illustrating part of the knife of Figures 1 and 2; and

Figures 5 to 8 are views illustrating parts of the knife in greater detail.

[0014] Referring to the accompanying drawings, a safety knife 10 is illustrated. The knife 10 comprises a handle 12 and a head 14 removably fitted to the handle 12. The handle 12 is shaped to define an opening 20 through which a user extends his or her fingers, in use, the handle 12 thus defining a grip 16 to be held by a users hand, in use, and a guard 18 providing protection to the users fingers, in use. The handle 12 is conveniently of a moulded plastics material, but it will be appreciated that this need not always be the case and it could be of other materials, for example metallic materials. Where the knife is to be used in areas in which food preparation is undertaken, then it may be desired for the material of the handle 12 to be of a type that can be detected using metal detection equipment, so that it can be ensured that no parts of the knife are present within foodstuffs prepared in the area in which the knife is used.

[0015] The head 14, in this embodiment, comprises a first part 20 (see Figures 5a, 6a, 7a and 8a) and a second part 22 (see Figures 5b, 6b, 7b and 8b). The first and second parts 20, 22 are shaped to include interengaging projections and recesses (not shown) to allow them to be releasably secured to one another by being snap fitted to one another. Whilst snap fitting of the parts 20, 22 represents one convenient technique for releasably securing the parts 20, 22 to one another, it will be appreciated that the invention is not restricted in this regard and that other techniques may be used to releasably secure the parts 20, 22 to one another.

[0016] The first part 20 includes, in a face thereof that, in use faces towards the second part 22, a recess 24 shaped to receive a metallic blade 26, the blade 26 thus being held captive between the parts 20, 22 when they are assembled and secured to one another. The shape and size of the recess 24 is such that, in use, movement of the blade 26 relative to the head 14 is prevented or restricted.

[0017] The first and second parts 20, 22 are shaped to, together, define a first passage 28 and a second passage 30. The passages 28, 30 extend into the head 14 by a distance sufficient that the cutting edge 26a of the blade 26 is exposed and extends across each of the passages 28, 30. The passages 28, 30 are of restricted width such that, in use, a user is unable to introduce his or her fingers into the passages 28, 30 by a distance sufficient to allow contact and cutting thereof by the blade 26. By way of example, the passages 28, 30 may be of width less than 10mm, and more preferably less than 8mm. The first part 20 is shaped to define projecting noses 32, 34 that serve to extend the lengths of the passages 28, 30 and to assist in guiding materials to be cut, in use, towards the cutting edge 26a of the blade 26. The noses 32, 34 are of tapering thickness, and further serve (along with the thickness of the head 14) to push a users finger or the like laterally away from the blade, during cutting, thereby further enhancing the protection against injury of a user.

[0018] The passages 28, 30 are angled to the cutting edge 26a of the blade 26, conveniently by an angle of less than 90 degrees, and preferably less than 60 degrees. The angle may be selected to aid cutting of the material intended to be cut using the knife.

[0019] The first and second parts 20, 22 are further shaped to define channels 36 that extend from the passages 28, 30 and along which, in use, the cut edges of the material cut using the knife pass. The channels 36 are arranged such that the channels 36 on the first part 20 are angled relative to the channels 36 on the second part 22, and hence that they are non-aligned relative to one another. As a consequence, in use, one of the cut edges of the material cut using the knife is displaced relative to the other of the cut edges, and it has been found that such displacement assists in using the knife to cut relative stiff materials.

[0020] The first and second parts 20, 22 are shaped to include regions 20a, 22a that, together, define a projection 38 of generally dovetail shaped form. An end part of the handle 12 is formed with a similarly shaped channel 40, the channel 40 extending from a front of the knife adjacent the upper end of the guard 18 towards the rear of the knife. The channel 40 is of re-entrant form, and the end of the channel 40 closest to the rear of the knife is closed. The shape and dimensions of the channel 40 are such that the projection 38 can be received therein, being introduced from the open, front end of the channel 40, to rigidly secure the head 14 to the handle 12. Cooperation between an end of the projection 38 and the closed end of the channel 40 serves to limit the movement of the head 14 relative to the handle 12. Whilst a projections of generally dove-tailed shape is used in this embodiment, it will be appreciated that the invention is not restricted in this regard and other shapes such as T-shapes or projections including parts of generally cylindrical form with a circular or oval cross-section represent examples of other forms that could be used. Furthermore, whilst in this embodiment the projection 38 is formed by the parts 20a, 22a in combination, the projection 38 could be defined by just one or other of them if desired.

[0021] In use, with the knife assembled as described hereinbefore, the knife may be used to cut paper, cardboard and plastics materials, for example. Cutting is achieved by introducing the material to be cut into one or other of the passages 28, 30 and drawing the knife, using the handle 12, relative to the material to be cut to bring the material to be cut into contact with the cutting edge 26a of the blade 26. Continued movement of the knife results in the material being cut, with the cut edges of the material passing through the channels 36. Displacement of the cut edges aids in reducing resistance to the passage of the knife through the material to be cut. It will be appreciated that the movement of the knife, in use, urges the projection 38 against the closed end of the channel 40, and thus that release of the head 14 from the handle 12 during cutting is resisted.

[0022] The projection 38 and channel 40 are conveniently or slightly tapering form, in the longitudinal directions thereof, such that during cutting relative movement between the head 14 and the handle 12, in combination with this tapering form, results in the parts of the knife becoming more tightly secured to one another.

[0023] As described hereinbefore, the shapes of the passages 28, 30 are such that access to the cutting edge 26a of the blade 26 is restricted. Accordingly, accidental injury of a user is restricted.

[0024] In the event that the cutting edge 26a of the blade 26 becomes dulled or damaged and the user desires replacement thereof, then the head 14 can be removed from the body 12 by sliding the head 14 in the forward direction, sliding the projection 38 out of the channel 40. Once removed from the handle 12, the parts 20, 22 of the head 14 can be separated from one another. To assist in release of the snap fit connection therebetween, a screw driver or other tool may be inserted therebetween, and the parts 20, 22 could be shaped to assist in the introduction of such a tool, if desired. Once the parts 20, 22 have been separated from one another, the blade 26 may be removed and replaced with a new blade 26 before reassembly of the head 14, snap fitting the parts 20, 22 to one another, before reattaching the head 14 to the handle 12 by sliding the projection 38 fully into the channel 40. Sliding of the head 14 into position results in the connection between the head 14 and the handle 12 tightening as a result of the slight tapering of the projection 38 and channel 40.

[0025] The worn, dulled or damaged blade 26 removed from the head 14 is of a single material and so may conveniently be recycled rather than simply disposed of.

[0026] Rather than remove and replace a worn blade 26 in the manner outlined hereinbefore, once the parts 20, 22 of the head 14 have been separated, the blade 26 may be reversed or rotated. Conveniently, the location of the recess 24 relative to the passages 28, 30 is such that the exposed parts of the cutting edge 26a are non-symmetrically arranged relative to a centreline of the blade 26. As a result, rotation or reversal of the blade 26 allows different parts of the cutting edge 26a of the blade 26 to be used, upon reassembly of the knife. Accordingly, each blade 26 may have an extended working life and so waste is reduced.

[0027] As illustrated, the knife may include a tape cutter blade 42 located on an end of the head 14.

[0028] It will be appreciated that the knife of the embodiment of the invention described hereinbefore is advantageous in that, by enabling replacement of a blade 26 and allowing reuse of the remainder of the knife, waste is reduced and the used blades can readily be recycled.

[0029] Whilst in the embodiment described hereinbefore the parts 20, 22 are separate components, they could, if desired be integral with one another, interconnected by a flexible region serving as a hinge to allow them to be brought face to face and snap fitted or otherwise secured to one another.

[0030] In an alternative embodiment, the head 14 may be of one piece moulded form taking substantially the shape of the parts 20, 22 when secured to one another, with the blade 26 encapsulated therein during the moulding process. In such an arrangement, upon replacement of the blade 26 being required, the head 14 is removed and replaced as a whole. As, in such an arrangement, the handle 12 may be reused with a new head 14 fitted thereto, it will be appreciated that waste is still reduced. The head 14 of such an arrangement may be designed in such a manner that, one removed, the blade 26 can be extracted therefrom. By way of example, the head 14 may be designed to be readily split apart to allow removal of the blade. Recycling of the materials of the head 14 may thus be undertaken relatively straightforwardly.

[0031] As with the handle 12, the head 14 of any of the arrangements described hereinbefore is conveniently of a plastics material, but other materials could be used. It may be of a detectable material, for example if used in food preparation areas.

[0032] Although not illustrated, the handle 12 could be formed with a latch mechanism or the like, if desired, to positively retain the head 14 to the handle 12.

[0033] It is recognised that in embodiments in which the head 14 can be opened to allow blade changing to be undertaken, a user will be exposed to an unguarded blade 26. If desired, a latch arrangement may be incorporated to resist opening of the head 14 such that it can only be undertaken by those suitably qualified, for example using a suitable release tool. As a result, the risk of injury during blade replacement may be reduced. Blade replacement could be undertaken off site, for example by skilled technicians at the site of the original manufacturer or another organisation.

[0034] When the handle 12 and/or head 14 required replacement, for example as a result of wear thereof, then as the blade can readily be separated from the remainder of the knife, the handle 12 and head 14 may be recycled in a convenient manner.

[0035] Whilst specific embodiments of the invention are described herein, it will be appreciated that the invention is not restricted to the specific arrangements described and illustrated, and that a wide range of modifications and alterations may be made thereto without departing from the scope of the invention as defined by the appended claims.

Claims

1. A safety knife comprising a handle, a head and a blade carried by the head, wherein the head and the handle are removably connected to one another.

2. A knife according to Claim 1, wherein the head and the handle are slidable relative to one another.

3. A knife according to Claim 2, wherein one of the head and the handle is provided with a channel of a re-entrant form, and the other of the head and the handle includes a projection shaped for receipt within the channel.

4. A knife according to Claim 3, wherein the channel is formed in the handle, and the projection is formed on the head.

5. A knife according to Claim 3 or Claim 4 wherein the channel and projection are of dovetail shape or form.

6. A knife according to any of Claims 3 to 5, wherein the channel is closed at one end.

7. A knife according to Claim 6, wherein the channel and the closed end thereof are orientated relative to the direction of movement of the knife in normal use such that the projection is pushed towards the closed end of the channel during cutting movement of the knife.

8. A knife according to any of the preceding claims, wherein the blade is moulded into the head so as to be encapsulated thereby.

9. A knife according to any of Claims 1 to 7, wherein the head is of a design allowing the head to be opened to allow removal and replacement or refitting of a blade thereto once separated from the handle.

10. A knife according to Claim 9, wherein the head includes parts snap fitted to one another to hold the blade captive therebetween.

11. A knife according to any of the preceding claims, wherein the head is shaped to define a passage across which part of a cutting edge of the blade extends, the passage being of a width sufficiently small that a users finger is unable to contact the cutting edge of the blade.

12. A knife according to Claim 11, wherein a width of the passage in the region of the cutting edge is less than 10mm.

13. A knife according to any of the preceding claims, wherein the blade is fitted to the head in such a manner that an exposed part of the cutting edge thereof is offset from a centreline of the blade.

Drawing