HONING DEVICE

FIELD OF THE INVENTION

The present invention relates to a honing device and in particular to a honing device comprising at least one pair of housings or a housing unit in which housings at least one and at least two hones, respectively, is/are mounted. Such honing devices are typically used to sharpen knives.

BACKGROUND OF THE INVENTION

Cutting tools, such as kitchen knives, get dull during use and they therefore need to be sharpened regularly to ensure satisfactory cutting properties. Several types of sharpeners exist of which some strip away metal to form new bevel; this process is referred to as grinding. Other types use a honing process wherein a burr at the very cutting edge of the knife is straightened. Sharpening by removal of material to form new bevel results in the acute angle of the blade formed by the cutting edge becoming larger, which makes it difficult to get a sharp cutting edge. Use of sharpening devices of both the grinding and the honing type often requires good practise to be able to obtain a sharp cutting edge along the whole blade.

Hence, improved hones and honing devices would be advantageous, and in particular more efficient and/or reliable hones and honing devices would be advantageous.

OBJECT OF THE INVENTION

It is an object of the present invention to provide a hone for insertion in a honing device, which hone can prolong the life of the honing device without the need to replace the hones comprised therein compared to presently known hones and honing devices.

It is a further object of the present invention to provide hones and housings therefore which can easily be mounted in a number of designs of honing devices.

It is a further object of the present invention to provide housings for hones and honing devices which guide a knife blade to be honed at a desired angle along the whole length of the blade, when the knife is pulled through the honing device.

It is an object of embodiments of the present invention to provide housings for hones and honing devices with which it is easier to obtain a correct honing angle, and thereby bevel angle of the knife being honed, than with known honing devices.

It is a further object of the present invention to provide an alternative to the prior art.

SUMMARY OF THE INVENTION

Thus, the above described object and several other objects are intended to be obtained in a first aspect of the invention by providing a hone for use in a honing device, the hone having an outer shape with at least a first plane of symmetry and at least a second plane of symmetry, said second plane of symmetry being substantially perpendicular to the first plane of symmetry, and said hone comprising a first honing surface comprising a first honing line, and a second honing surface comprising a second honing line, said first and second honing lines both lying substantially in the first plane of symmetry, and said first and second honing surfaces having substantially mirrored surfaces with respect to the second plane of symmetry.

By "honing" is preferably meant a process wherein a burr at the very cutting edge of the knife is straightened without removal of material. However, the overall idea of the invention may also be applied to tools for grinding, i.e. sharpening comprising removal of small amounts of material from the knife blade. This can be done by using hones having a larger roughness than what is appropriate for honing.

By "honing line" is preferably meant a line on the honing surface along which the honing is carried out. Alternatively, the honing takes places over an area having a

certain width, and in this case "honing line" refers to a centre/symmetry line of the honing area.

In preferred embodiments of the invention, the first and second honing lines may be substantially linear lines which may extend along substantially mirrored angles of inclination with respect to the second plane of symmetry. Such linear lines provides better support of the knife blade than a curved surface would do resulting in a larger certainty for as sharp a knife as possible.

The mirrored honing surfaces may by convex, and the first and second honing surfaces may have substantially mirrored surfaces of inclination with respect to the first plane of symmetry.

A hone according to the present invention may have a circumference lying in a plane substantially perpendicular to both the first and the second planes of symmetry, said circumference having a substantially mirrored extension with respect to the first and second planes of symmetry. Hereby it is obtained that the hones can be turned by 180° and remounted in the housings or directly in the honing device whereby the life of a honing device can be prolonged without the need to replace the hones comprised therein.

In some embodiments the hones are arranged on a base, as will be described in relation to the figures. In such embodiments, the circumference having a substantially mirrored extension with respect to the first and second planes of symmetry may be the circumference of the base.

The angles of inclination with respect to the second plane of symmetry may be 68° to 74°, such as 68° to 70° or 70° to 74°, such as 69°. These angles result in hones which can be arranged to cooperate so that honing angles of 32° to 44° are obtained; this will be described in the detailed description of the invention.

A hone as described above may be made from one ceramic material or a combination of ceramic materials. Alternatively, it may be made of a base material and have a surface layer of at least one ceramic material, at least part of said ceramic material of the surface layer being different from the base material.

By "base" is in this connection meant core material which is covered by another material.

The ceramic material may be one of or a combination of the following materials: Aluminium oxide, Zirconium dioxide, Barium titanate, Bismuth strontium calcium copper oxide, Boron carbide, Boron nitride, Ferrite, Lead zirconate titanate, Magnesium diboride, Silicon Aluminium Oxynitrides, Silicon carbide, Silicon nitride. An advantage of using a ceramic material, as opposed to a metal, is that magnetization of the knife blade during honing is avoided even if the knife blade is moved back and forth along the hones.

The hones may alternatively be made from a non-ceramic material such as carborundum, stainless steel or titanium. Still another alternative is to make the hones from a non-ceramic base material having a surface layer of at least one ceramic material.

A second aspect of the invention relates to a pair of housings, wherein at least one hone as described above is arranged in a first of the housings and at least two hones as described above are arranged in a second of the housings. The hones are preferably separably mounted in the housings so that they can be replaced and/or turned by 180° as described above. The hones are typically held in place in the housings by a press fit. It may further comprise ribs, notches and knobs further ensuring a correct positioning.

In preferred embodiments of a pair of housings according to the present invention, all the hones may be substantially identical.

The number of hones in the second housing is preferably one more than the number of hones in the first housing. There may e.g. be one hone in the first housing and two hones in the second housing. Hereby the hones can be symmetrically mounted in the housings in such a way that the first planes of symmetry alternate between hones from the two housings when the housings are arranged to face each other and ready for use; this will be described in the detailed description. Alternatively there is an equal number of hones in the two

housings, and the alternation between hones from the two housings is made possible by off-setting the hones with respect to a symmetry line of the housings.

The second aspect of the invention further relates to a housing unit comprising two connected parts, wherein at least one hone as described above is arranged in a first part and at least two hones as described above are arranged in a second part. Hereby it is easier to ensure that the desired honing angle is preserved during honing independent on an outer force, such as from a person's hand holding the honing device. All the hones may preferably be substantially identical.

In preferred embodiments of a housing unit according to the present invention, the at least one hone in the first part may extend along the second plane of symmetry, and the at least two hones in the second part may also extend along the second plane of symmetry, and at least one hone in the first part may extend between the at least two hones in the second part, when viewed perpendicular to the second plane of symmetry. The hones may be arranged so that the second planes of symmetry of all the hones are substantially coincident, and so that the hone in the first part extends in the opposite direction of the at least two hones in the second part, when viewed perpendicular to the second plane of symmetry.

A third aspect of the invention relates to a honing device comprising at least one pair of housings as described above, wherein the housings are mounted in the honing device in such a way that the second planes of symmetry of all the hones are substantially coincident. Hereby the first planes of symmetry of all the hones will be substantially parallel.

In preferred embodiments of a honing device according to the present invention, the at least one hone in the first housing may extend along the second plane of symmetry, and the at least two hones in the second housing may also extend along the second plane of symmetry, and at least one hone in the first housing may extend between the at least two hones in the second housing, when viewed perpendicular to the second plane. An example of such an arrangement is shown in figure 4 which will be described below. Hereby it is obtained that during honing, a knife edge is supported by the hones without being able to pass the gap between hones in the first and second housings.

In some embodiments of the invention, the hones may be mounted in the housings in such a way that the first planes of symmetry alternate between hones from the two housings. Hereby the knife edge is as evenly supported as possible for a given number of hones, whereby a correct angle is obtained.

In some embodiments of the invention, the honing device may comprise a holder having two hingedly connected parts in which holder a pair of housings as described above may be arranged so that one housing may be mounted on each part. Such a design means that a holder with housings mounted therein can be supplied as a separate unit adapted to be mounted in different honing devices. This may e.g. result in a more efficient assembly for producers of honing devices. It may furthermore be possible for a user to move a holder from one honing device to another if desired.

A honing device according to the invention may further comprise two position pads adapted to ensure that a blade of a knife to be honed is held substantially perpendicular to the first and second planes of symmetry of the hones. The two position pads are preferably placed opposite each other with one on each part to support the knife blade on both sides. The position pads may be placed closer to the hinge than the housings are, or the housings may be placed closer to the hinge than the position pads are.

The third aspect of the invention further relates to a honing device comprising at least one housing unit as described above. Such a honing device may comprise features as described for a honing device comprising a pair of housings.

A pair of housings according to the second aspect of the invention may preferably be adapted to be mounted in a honing device according to the third aspect of the invention.

The third aspect of the invention further relates to honing device comprising at least one first hone as described above and at least two second hones as described above, wherein the hones are arranged so that the second planes of symmetry of all the hones are substantially coincident, and wherein the at least one first hone extends between and in the opposite direction of the at least two

second hones, when viewed perpendicular to the second plane of symmetry. Such a honing device may comprise the same features as described for the embodiments comprising a pair of housings or a housing unit but with the hones mounted directly in the honing device without housing. The hones may e.g. be arranged on a base which is adapted to be fastened in the honing device. Examples of possible geometries of such a base are illustrated in the figures.

The first, second and third aspect of the present invention may each be combined with any of the other aspects. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE FIGURES

The hones, housings therefore and honing devices according to the invention will now be described in more detail with regard to the accompanying figures. The figures show one way of implementing the present invention and is not to be construed as being limiting to other possible embodiments falling within the scope of the attached claim set.

Figure 1 shows a pair of housings with one and two hones, respectively. Fig. l.a is a perspective view, fig. l.b is a top view, and fig. l.c is a side view.

Figure 2 shows schematically a top view of a hone on a base.

Figure 3 shows a side view of a hone on a base.

Figure 4 shows a side view of two housings placed in a position ready for honing; the housings are shown from the direction indicated by arrow A in figure 2.

Figure 5 shows another side view of the two housings of figure 4; the housings are shown from the direction indicated by arrow B in figure 4.

Figure 6 shows an embodiment of the invention in which a pair of housings and two position pads are mounted in a holder. Figure 6. a shows the holder in an open

position, and figure 6.b shows the holder in a closed position ready to be used for honing.

Figure 7. a is a side view of the holder of figure 6. a, and figure 7.b is an alternative embodiment.

Figure 8 shows an embodiment of a honing device which is adapted to be handheld during use.

Figure 9 shows an embodiment of a honing device which is adapted to stand on a table.

Figure 10. a shows a housing unit which is an alternative to the pair of housings shown in figure 1. The housing unit is adapted to receive bases with one and two hones, respectively, as shown in figures 10. b to 10. d.

Figure 11 shows an alternative embodiment of a hone according to the present invention.

DETAILED DESCRIPTION OF AN EMBODIMENT

A honing device according to the present invention comprises at least three hones which are arranged so that they can be used to sharpen e.g. a knife which is moved along the honing surfaces of the hones. The hones 1 may be mounted in a pair of housings 2 an example of which is shown in figure 1. Fig. l.a is a perspective view, fig. l.b is a top view, and fig. l.c is a side view. The housings 2 are shown next to each other although in use the hones 1 will face each other; this will be described in further details below.

The one or more hone(s) is/are typically arranged on a base Ib which is then mounted in the housing 2. The base Ib and the hone(s) 1 may be manufactured as one unit, or the hones 1 may be manufactured as separate units which are then attached to the base Ib e.g. by mechanical fastening, such-as a click-in solution, or by gluing. Figure 2 shows schematically a top view of a base Ib with a hone 1. The hone 1 has an outer shape with a first plane of symmetry 3 and a

second plane of symmetry 4 which is perpendicular to the first plane of symmetry 3 as shown in figure 2. The hone 1 comprises a first honing surface 5 comprising a first honing line 7 and a second honing surface 6 comprising a second honing line 8. In the illustrated embodiment, the honing lines 7,8 are the linear part of the intersections between the first planes of symmetry 3 and the honing surfaces; see figure 3. The first and second honing lines 7,8 have substantially mirrored angles of inclination α with respect to the second plane of symmetry 4 as shown in figure 3. The base Ib and the housings 2 typically comprise protrusions adapted to ensure a correct positioning in the housings and honing devices, respectively. Examples of such protrusions are marked with 22a and 22b in the figures.

The housings are illustrated as circular, but other shapes, such as rectangular or oval are also possible. The diameter of a circular housing is typically in the order of 25 to 35 mm, and the height is typically in the order of 6 to 10 mm. However, the dimensions mentioned are not to be construed as limiting for the scope of the present invention as the actual size will depend on the application of the invention.

Figures 4 and 5 show the housings arranged ready for honing. Figure 4 shows a side view in which the housings are seen from the direction indicated by arrow A in figure 2. Figure 5 shows another side view of the two housings of figure 4; the housings are shown from the direction indicated by arrow B in figure 4. The two hones 1 on the lower (with respect to the figure) housing 2 means that a knife blade (not shown) to be sharpened is guided at the correct angle, i.e. substantially in the plane of the paper in figure 2 and perpendicular to the plane of the paper in figure 5. The shape and arrangement of the hones ensures that knives with scalloped edges can also be sharpened by use of a honing device according to the present invention. A larger number of hones per housing are also possible within the scope of the invention. This may result in a more efficient sharpening per stroke of the knife through the honing device and an even better support of the blade.

As seen from figure 5, a honing angle β is established by the hones, which honing angle β equals (180 - 2α)°. The honing angle β should equal the bevel angle of the knife edge to be honed. The angles of inclination α of the hones are typically 68°

to 74° resulting in honing angles of 32° to 44°, such as 36° to 40° or 40° to 44°, such as 42°. However, any acute honing angle β is possible within the scope of the invention.

Some knives, e.g. traditional Asian knives, have a blade design with a bevel on just one side of the blade. To obtain a satisfactory sharpening of such knives, it may be necessary to use hones 1 with different designs in the two housings 2; such embodiments are also covered by the scope of the present invention.

Figure 6 shows an embodiment of the invention in which a pair of housings 2 is mounted in holder 10 having two hingedly connected parts. Figure 6. a shows the holder 10 in an open position, and figure 6.b shows the holder 10 in a closed position ready to be used for honing. In addition to the pair of housings 10, two position pads 11 are mounted opposite each other in the holder 10. Such position pads 11 help guiding a knife edge correctly along the hones 1. This may be particularly useful for larger knives of which only a relatively small part of the blade 9 is supported by the hones 1. The position pads 11 may be placed closer to the hinge 12 than the housings 2 are, as shown in figure 7. a, or the housings 2 may be placed closer to the hinge 12 than the position pads 11 are, as shown in figure 7.b. The actual choice between these two possibilities may depend on the design of the honing device into which the holder is to be fitted. Furthermore, an arrangement with the position pads 11 placed closest to the hinge lowers the risk that the knife accidentally slips out of the honing device. It may also be used as a temporary storage place for the knife if the holder is arranged in e.g. a cutting board. The holder typically comprises end guides 13 which make it easier to keep the holder in a suitable closed position for honing. Such end guides furthermore prevents the knife from slipping out of the holder during honing and thereby protects the hands of the person using it. The holder 10 may mounted in a honing device by any appropriate method well-known to a person skilled in the art. Such mounting methods may include permanent fixation, such as by gluing or irreversible click-in solutions, or separable mounting, such as by screws.

Figures 8 and 9 show two embodiments of honing devices according to the present invention. The honing device shown in figure 8 is adapted to be hand-held during use. The honing device is shown to comprise a holder 10 corresponding to

the one shown in figure 7. a. The holder is mounted in an outer cover 14 to ensure a good grip and protect the hand holding the knife during honing. Alternatively (not shown), housings 2 and/or protection pads 11 can be mounted directly in the cover. An advantage of a solution with a separate holder may be that one type of holder can be placed in a number of covers, said covers e.g. having different designs, such as being made from different materials or with different decorations. This makes it possible for a costumer to choose among a range of appearances of a honing device without the supplier needing to supply more than one type of holder with housings and position pads. It may furthermore be possible to move such a holder to another cover if desired.

Figure 9 shows an embodiment of a honing device which is adapted to stand on a table. Figure 9. a is a three-dimensional view, and figure 9.b is a side view. The honing device comprises a foot 15 and two side parts 16 in which housings 2 and protection pads 11 are mounted directly in the side parts 16.

Figure 10 shows a housing unit 17 which is an alternative to the pair of housings 2 shown in figure 1. The housing unit 17 comprises two connected parts which are adapted to receive bases with one and two hones, respectively. Figures 10. a and 10. b show the housing unit without and with hones mounted therein, respectively. Figure 10. c shows the housing unit 17 seen in the direction indicated by A in figure 10. b, and figure 10. d shows the housing unit 17 seen in the direction indicated by B in figure 10. b, Both the pair of housings 2 made as two separate pieces and the housing unit 17 made as one piece can be mounted directly in a honing device, such as the one shown in figure 8 or 9, without use of a separate holder 10, such as e.g. the one shown in figures 6 and 7. However, in this case it may be easier to ensure a correct mutual positioning of the hones 1 with the housing unit 17 being one piece.

The housing unit 17 comprises openings 18 for insertion of a knife blade to be honed and ribs 19 for securing the housing unit 17 in a honing device. The housing unit 17 further comprises notches 20 for receiving corresponding knobs 21 on the bases Ib. The shapes and positions of the ribs 19, notches 20 and knobs 21 may vary from the ones shown in figure 10. The dimensions, shapes and tolerances of the ribs 19, notches 20 and knobs 21 must be determined to ensure

that the bases Ib are securely fastened in the housing unit 17, and that the housing unit 17 is securely fastened in the honing device. By securely fastened is meant that they should not come loose during honing. On the other hand, it should preferably also be possible to dismantle the pieces for turning the hones by 180° (described below), for replacement of the hones, and/or for cleaning.

Figure 11 shows an alternative embodiment of a hone according to the present invention. The hone 1 has a middle section 23 having another angle of inclination than the honing surfaces, so that the edge of a knife being honed is further away from the second plane of symmetry 4 than for the embodiments described above. Hereby it is easier to hone a knife in a housing unit 17 with a design as shown in figure 10 without risking cutting into the housing unit 17. Such a cut could otherwise damage the housing unit 17 and/or the knife. In the illustrated embodiment, the middle section 23 has a single-curved surface, but other geometries are also possible.

For all embodiments of the invention, the hones 1 may preferably be mounted in a way that allows them to be turned/ rotated by 180° when the first honing surface 5 is so worn that that the result of the honing is unsatisfactory. The second honing surface 6 is then ready to use, whereby the user of the honing device obtains a doubling of the lifetime of the hones 1 compared to a honing device in which the hones 1 have only one honing surface. The lifetime of the honing device may be further extended by replacing the hones 1 with new ones. A mounting that allows for such replacement and for the 180° turning of the hones 1 will be well-known to a person skilled in the art. It may e.g. comprise that the housing 2, 17 is made from separable parts of which one has one or more openings through which most of the hone(s) 1 protrude(s) while being held in place by a base Ib not being able to pass through the opening(s).

The hones may be made from a ceramic material, such as Aluminium oxide, Zirconium dioxide, Barium titanate, Bismuth strontium calcium copper oxide, Boron carbide, Boron nitride, Ferrite, Lead zirconate titanate, Magnesium diboride, Silicon Aluminium Oxynitrides, Silicon carbide, Silicon nitride.

Alternatively the hones are made from a base material, such as metal or plastic, covered with a coating made from a ceramic material. Such a coating may e.g. be Zirconium dioxide.

The hones and/or the base may typically be made by injection moulding or by sintering-based methods.

The housings may typically be made from plastic or a lightweight metal, such as aluminium. However, any type of appropriate material is possible within the scope of the invention.

In some embodiments (not shown) of honing devices according to the invention, the hones are arranged directly in the honing device without the use of a pair of housings or housing units as described above but according to the same overall idea. In such embodiments, the hones 1 are typically arranged on bases Ib as shown for the embodiments to be inserted in housings (2,17). However other geometries of the bases Ib are also possible, such as some having cylindrical surfaces with a circumference corresponding to the one of the hone 1 shown in figure 2 at the intersection with the surface of the base Ib.

The present invention has been described in connection with honing of knives. It may, however, also be used for honing of other tools, such as scissors, by appropriate choice of the design of the hones.

The above description is focused on honing, but as mentioned the overall idea of the invention may also be applied to tools for grinding, i.e. sharpening comprising removal of small amounts of material from the knife blade. The hones can also be made to comprise first and second honing surfaces, and thereby first and second honing lines, having different surface roughness. Such hones can be arranged in honing devices designed to allow use of both honing lines of a hone so that the same device can be used e.g. both for honing and grinding.

Embodiments of hones (not shown) are non-symmetrical with respect to the second plane of symmetry. Such hones may e.g. have different angles of inclination α for the first and the second honing lines 7,8. Hereby the hones can

be inserted in honing devices which can be used to hone knives with two different bevel angles. Such hones can be provided with bases Ib and inserted in housings and housing units as described above. Alternatively or in combination therewith the circumference of the hones may not be identical for the two sides of the hones.

Although the present invention has been described in connection with the specified embodiments, it should not be construed as being in any way limited to the presented examples. The scope of the present invention is set out by the accompanying claim set. In the context of the claims, the terms "comprising" or "comprises" do not exclude other possible elements or steps. Also, the mentioning of references such as "a" or "an" etc. should not be construed as excluding a plurality. The use of reference signs in the claims with respect to elements indicated in the figures shall also not be construed as limiting the scope of the invention. Furthermore, individual features mentioned in different claims, may possibly be advantageously combined, and the mentioning of these features in different claims does not exclude that a combination of features is not possible and advantageous.