Blade sharpness tester

Abstract

A blade sharpness tester comprises a roll (6) of mesh strip (7), a lower clamp (10), an upper clamp (11), a force sensor (4) and a display screen (3). The roll (6) can be rotated by hand to cause a stretch (12) of the strip to be played out and secured by the lower clamp (10), and then rotated again in a reverse direction by hand-force to generate tension in the stretch (12). The second clamp (11) is then activated to cause the stretch (12) to be held under tension by and between the clamps. A blade (13) is then manoeuvred through and along the tensioned stretch to make a cut along it. The sensor (4) senses the level force required to make that cut and, based on this, the screen (3) displays information as to whether the level of force is indicative of a need to sharpen the blade.

Description

[0001] TITLE

[0002] Blade Sharpness Tester

[0003] FIELD OF INVENTION

[0004] The invention relates to a tester for indicating how sharp a cutting blade is, for example the blade of a knife used in industry or elsewhere.

[0005] BACKGROUND

[0006] It is known to test the sharpness of a blade as it makes a cut through a medium. This may be done with a device that measures the amount of force needed to make the cut and, based on the measurement, reports on whether the blade is sharp or blunt and therefore whether it needs sharpening. In this regard a lower force is indicative of a sharper blade and a greater force is indicative of a duller blade. Ensuring that working blades are sufficiently sharp is important for their efficient use in industry or domestically, for example in processing or otherwise preparing foods such as meat, bread, vegetables and fruit. However, a problem is that the manner in which many known testing devices are designed makes them difficult to transport and expensive to manufacture or purchase.

[0007] OBJECT

[0008] It is an object of preferred embodiments of the invention to go at least some way towards addressing the above problem. While this applies to preferred embodiments, the object of the invention perse is more general; namely to provide the public with a useful choice. Accordingly, any objects or advantages applicable to any preferred embodiments should not be interpreted as a limitation on the scope of any claims expressed broadly.

[0009] DEFINITIONS

[0010] The term “comprises” or “has”, if and when used in this document in relation to one or more features, should not be seen as excluding the option of there being additional unmentioned features. The same applies to derivative terms such as “comprising” and “having”.

[0011] Orientational terms, for example top, bottom, etc, if and when used in this document, refer to the orientation the associated features will have when in a normal in-use disposition.The term “approximately” or “substantially” when used in relation to a value or parameter means up to ±5%, or up to ±10%, or up to ±15%, of that value or parameter.

[0012] SUMMARY OF THE INVENTION

[0013] According to one aspect of the invention is a blade sharpness tester comprising:

[0014] • a roll of mesh strip;

[0015] • a first clamp;

[0016] • a second clamp;

[0017] • a force sensor; and

[0018] • a display;

[0019] the tester being adapted such that:

[0020] o the roll can be rotated by hand-force to cause a stretch of strip to be played out and secured by the first clamp;

[0021] o the roll can then be rotated, or the strip otherwise moved, in a reverse direction by hand-force to generate tension in the strip such that if the second clamp is then activated a stretch of the strip will be held under tension by and between the clamps;

[0022] o a blade can be manoeuvred through and along at least part of the tensioned stretch by hand force to make a cut along the strip while the sensor senses the level force required to make that cut; and

[0023] o the display, based on what the sensor senses, presents information as to whether the level of force is indicative of a need to sharpen the blade.

[0024] The following optional features may be added to the arrangement above individually or in any combination.

[0025] Optionally the blade sharpness tester has a side wall, a stub-shaft and a guard plate, arranged such that the feeder roll is located between the side wall and the guard plate so that the roll is able to rotate on the stub-shaft when the strip is played out from the roll.

[0026] Optionally the stub-shaft has a stem and a head and the guard plate has an inverted keyhole shaped aperture having a lower lobe and an upper slot, the head being narrow enough to pass through the lobe but too wide to pass through the slot, the tester being such that the plate can be installed by hand-manoeuvring it so that the head passes through the lobe and the plate is able to then move downwards such that the stub-shaft’sstem extends through the slot with the feeder roll located between the plate and the side wall.

[0027] Optionally the blade sharpness tester has a base having an upwards facing slot, and wherein the guard plate has a foot adapted to releasably engage with the slot to supportively retain the plate on the base.

[0028] Optionally the guard plate can be removed from the stub-shaft by hand-force to enable the feeder roll to be removed and replaced.

[0029] Optionally a portion of the outer circumference of the feeder roll projects beyond the guard plate so that the protruding portion can be engaged by hand to cause the feeder roll to rotate.

[0030] Optionally the feeder roll has a central bore hole which has three or more corners, arranged such that when the roll rotates the stub-shaft contacts the corners one after the other to impede such rotation.

[0031] Optionally the bore hole is substantially square or triangular.

[0032] Optionally the blade sharpness tester has a receiver roll adapted to be hand-rotated on a stub-shaft to enable the stretch of strip to be wound onto it after the stretch has been cut in a blade sharpness test.

[0033] Optionally the receiver roll is located between a further side wall and a further guard plate in the same manner as the feeder roll.

[0034] Optionally the first clamp is located above the second clamp.

[0035] Optionally the first clamp comprises a ratchet clamp.

[0036] Optionally the second clamp comprises a lever and a pair of jaws, the lever having a cam surface and being arranged such that when it is activated the cam surfaces move against one of the jaws to cause it to be in a clamping disposition with respect to the other jaw.Optionally the blade sharpness tester has a stopper above the first clamp, positioned to prevent the blade from proceeding past it when a cut is created in the strip.

[0037] Optionally the feeder roll is adapted to be hand-rotated rotated in either of two rotational directions, one after the other, when in use.

[0038] Optionally the blade sharpness tester has one or more sharpening pillar formed such that the blade can be drawn across it to sharpen the blade.

[0039] Optionally the blade sharpness tester has a pair of pillars that extend from a base to support the display screen in spaced relationship to the base, the first clamp being at or adjacent to the top of the pillars and the second clamp being located at the base.

[0040] Optionally the blade can be gripped by hand and manoeuvred forward approximately at right angles to and between the pillars to cut the stretch of strip when held under tension between the clamps.

[0041] Optionally the blade sharpness tester is engaged with the stretch of strip such that it is held under tension between the clamps.

[0042] According to a further aspect, the invention is a method of testing the sharpness of a blade, comprising accessing a blade sharpness tester according to any one of the preceding claims, rotating the feeder roll by way of hand-force such that an unused stretch of the strip extends between the clamps and is secured by the first clamp, rotating the roll in reverse, or otherwise moving the strip, by way of hand-force so that the stretch is tensioned between the clamps, engaging the second clamp such that the stretch is maintained under tension between the clamps, manoeuvring the blade such that it makes a vertical cut in the stretch such that during the cutting the sensor senses the amount of force exerted on the strip by the blade and, based on this, the display displays information indicative of whether the blade needs sharpening.

[0043] The same options mentioned above may be added for the method aspect individually or in any combination.DRAWINGS

[0044] Some preferred embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, of which:

[0045] Figure 1 is an isometric view of a blade sharpness tester;

[0046] Figure 2 is an alternative isometric view of the tester;

[0047] Figure 3 is a further alternative isometric view of the tester;

[0048] Figure 4 is a further alternative isometric view of the tester;

[0049] Figure 5 illustrates the tester when in use with a knife;

[0050] Figure 6 illustrates a display screen forming part of the tester;

[0051] Figure 7 illustrates the way in which a feeder roll of mesh strip is supported by surrounding components of the tester;

[0052] Figure 8 illustrates an upper ratchet clamp forming part of the tester;

[0053] Figure 9 illustrates detail of the feeder roll;

[0054] Figure 10 illustrates detail of an upper region of the tester;

[0055] Figure 11 is an isometric view of a modified version of the tester;

[0056] Figure 2 is an isometric view illustration a further modified version of the tester; Figure 3 illustrates a blade sharpness tester according to a further embodiment of the invention;

[0057] Figure 1 illustrates a blade sharpness tester according to a further embodiment of the invention in longitudinal cross section; and

[0058] Figure 15 illustrates a partially assembled blade sharpness tester according to a further embodiment of the invention.

[0059] DETAILED DESCRIPTION

[0060] Referring to Figures 1-4, the blade sharpness tester has a pair of supports, eg side walls 1, spaced from one another and extending upwards from a base 2 to a display screen 3. The display screen is adapted to show test results when the tester has been used to assess the sharpness of a blade by way of a force sensor 4, for example comprising a load cell, housed within the same casing that supports the display screen.A stub shaft 5 extends horizontally and inwardly from one of the sides and is loaded with and supports a feeder spool having a roll 6 of mesh strip 7 for use as test media. A further stub shaft 8 extends horizontally and inwardly from the opposite side and supports a receiver spool for a roll 9 for the mesh strip when used. In some embodiments the roll 9 may provide a second or spare supply of the strip 7 for running sharpness tests. In that case, used test strip may simply be cut away and discarded rather than being wound into a spool / roll.

[0061] The strip 7 can be played out from the feeder roll 6 by hand so an unused length of it runs above the base 2, passes through a lower clamp 10, and extends upwards to pass through an upper clamp 11, which in this example is a ratchet clamp biased to its closed or clamping disposition. Figures 3 and 4 show a loose end of the strip 7a just beyond the upper clamp 11.

[0062] To prepare for a blade sharpness test, a human operator ensures that the upper clamp 11 is closed onto the of strip with the lower clamp 10 remaining open. The feeder roll 6 is then turned in reverse by hand to generate tension in the strip. With hand force maintaining the tension, the bottom clamp 10 is then activated so that a stretch 12 of the strip is held under tension by and between the clamps 10, 11 when the hand force is relaxed.

[0063] In some embodiments the force on the strip may be applied and adjusted via a hand crank. And in some embodiments tension on the strip may be fine-tuned via a mechanism that expands the distance between the lower clamp 10 and the force sensor 4, or between the lower and upper clamps 10, 11.

[0064] Optionally, instead of rotating the feeder roll 6 backwards, tension may be created by pulling back on the strip 7 between the roll 6 and the clamp 10 and the lower clamp engaged to maintain it. If desired, any loose strip between the clamp 10 and the roll 6 may be tidily wound onto the roll 6 after the lower clamp has been engaged,

[0065] As shown, the side walls 1 are inclined backwards between the display screen 3 and the base 2. Because of this the walls 1 are more out of the way of the hands of a human operator when engaging the lower clamp 10 and manoeuvring the blade 13. Preferably the stretch of strip 12 is substantially vertical when tensioned, although in other embodiments it may be other than vertical.Referring to Figure 5, when the strip has been prepared as above, a knife blade 13 is pushed forwards and downwards by hand so that at least most of the blade runs through and makes a generally vertical cut 14 in the strip. As the cut is made the sensor 4 measures how much force is being applied to the mesh by the blade. A higher amount of force indicates a dull blader and a lower amount of force indicates a sharp blade.

[0066] Preferably the mesh strip is formed of a plastic-coated mesh and is approximately 15-25 mm wide, or more preferably about 20 mm wide. Because the blade has to cut through horizontal strands of the mesh one after the other, a situation is avoided where the strip opens up or tears more easily after the initial incision. In this regard the force needed to cut one horizontal strand of the mesh is not affected by neighbouring horizontal strands. The use of mesh also facilitates the collection of data for a multiple of deliberate measurement points along the blade.

[0067] Referring to Figure 6, the amount of force exerted by the blade on the strip during the cut is displayed on the screen 3. It may show as variable if for example some parts of the blade are sharper than others. This is indicated by the ups and downs of the force line 15. The information presented by the display gives an indication of whether the blade needs sharpening for whatever task it is to be used for. The display may for example present the sharpness on a scale of 0-50, 0-10 or 0-5, and / or may for example indicate it with colours where red means the blade is blunt, green means it is very sharp, and amber means it is moderately sharp. In some embodiments the display may alternatively, or additionally, indicate the cutting force / sharpness along the blade in a histogram format and / or give a value for the average sharpness for the blade based on readings at multiple points along its length.

[0068] When a test has been completed the clamps are relaxed and the used length of strip may be fed to and wound onto the receiver roll 9. All of this causes a new stretch of unused strip to be drawn from the feeder spool 6 and locate between the clamps 10, 11 ready for use in testing another blade in the same way described above, or for doing a repeat test on the same blade.

[0069] Referring to Figure 7, the tester also has a pair of generally semi-circular guard plates 16, 17 each supported on a respective one of the stub-shafts 5, 8. Afoot 18, 19 of each guard plate is located in a respective slot 20 in the base for further support. The guard plates are wider than the largest diameter of the rolls 6, 9 and in effect sandwich the rolls between them and the respective nearest side wall 1 (not shown). The arrangement issuch that the guard plates 16, 17 help to keep the feeder and receiver rolls 6, 9 (only one of which is shown) on the associated stub-shaft and in the correct plane when they are rotating. As the guard plates are wider than the rolls, they also help keep the strip from moving too far sideways as the strip moves off or onto them.

[0070] Continuing with Figure 7, each guard plate has a keyhole 21 with a lower wide lobe 22 and an upper narrow slot 23. The arrangement is such that when the guard plates are installed, the stub-shafts are passed through the lobe 22. This is possible as the lobe is wider than a broad head 24 of the stub-shaft. The guard plate is then made to drop downwards so that a narrower stem 25 of the shaft enters the slot of the keyhole and rests there. Because the head 24 is too large to pass through the slot the guard plate is retained on the stub-shaft until removed by doing the reverse of the steps taken to place it there.

[0071] Still with Figure 7, the lower clamp 10 has a pair of jaws 26, 27 and a cam lever 28. The arrangement is such that lever can be rotated towards either side of the tester so that it presses the upper jaw 26 down against the lower jaw 27. When the strip 7 is between these jaws it becomes clamped so that a blade sharpness test can be run as described above. The cam surfaces 29 of the lever 28 are such that when the lever is in the upright position shown, the jaws are open. Because the clamping action occurs when the lever 28 is hand turned to either side, the clamp 10 can be conveniently engaged regardless of whether the person working it is left or right-handed.

[0072] As also shown in Figure 7, the tester incorporates a stopper platform 30 arranged to prevent a blade from being run too far down the strip when making a cut during testing. The platform may have a relatively soft blade contact surface or landing plateau 31 to protect the blade from damage (eg of plastic or rubber, compared to the other components which may be mainly metallic).

[0073] Referring to Figure 8, as mentioned above, the upper clamp 11 is a ratchet clamp in that it allows the strip to advance forward through it but not back. However, the clamp 11 has a hand operable lever 32 which can be depressed to enable the strip to move freely through the clamp in either direction.

[0074] Referring to Figure 9, the bore 33 of the feeder roll 6 that engages the stub-shaft is preferably other than circular. In this example it is square but in other embodiments it may be triangular, pentagonal or hexagonal, etc. Therefore, as the roll 6 rotates to playout the strip, the corners 34 (in this example they are right-angled corners) of the bore come into contact with the shaft one by one so that rotation of the roll 6 is hindered. This serves to restrict the rate at which the strip is able to be pulled from the roll 6 and avoids an excessive playout of the strip if for example the operator were to inadvertently pull a little too hard on the strip.

[0075] Referring to Figure 10 the upper region of the tester has a casing 35 which houses the force sensor 4 (not shown) and the display screen 3 (also not shown). The sensor and screen are powered by rechargeable battery and / or by a USB power cord.

[0076] Figure 11 illustrates a blade sharpness tester according to a further embodiment of the invention. It is substantially the same as the embodiments described above except that it includes a pair of pillar-like blade sharpening steels 36. These may be abrasive and a blade can be sharpened by drawing it across one or other of them by hand. Preferably one of the steels 36 has a coarser sharpening surface than the other to provide options for different levels of sharpening. Optionally, one or more of the steels 36 may have some blade sharpening parts that are coarser than others.

[0077] Figure 12 illustrates a blade sharpness tester according to a further embodiment of the invention. It is substantially the same as any of the embodiments described above except that it has a smaller base 37 and supportive side pillars 38 rather than side walls. Its feeder roll 39 of mesh strip may be located on a stub shaft (not shown) beneath the base 37, or alternatively the stub-shaft may be absent and the roll 39 may be separated from the base. Optionally one or more of the pillars 38 is blade sharpening as described above.

[0078] In any of the above embodiments the feeder roll and the receiver roll may comprise a spool, but in the examples provide above they are simpler, have of an annular core with the strip would around it.

[0079] Referring to Figure 13, in some embodiments of the invention the sharpness tester (for example as per of figures 1-12) may be such that the length of the strip 7 can be used more than once. For example, several downwards cuts 40 may be made side by side by the same blade, or by different blades, in the same length of strip between the upper and lower clamps. Each cut may be made without adjusting the tension between the clamps, or by tensioning it a little between cuts if the tension has reduced after an immediately preceding cut. A benefit of at least preferred embodiments of the invention (eg asillustrated in Figure 13) is that the sharpness tester has no back wall. This means that the blade being tester can be pushed forward through the strip 7 without encountering any obstructions regardless of how long the blade is.

[0080] Referring to Figure 14, in at least preferred embodiments of the invention the base 2 provides a downwardly ramped pathway 41 for the test strip as it extends from the feeder roll to the lower clamp. Further, this pathway 41 tapers inwards / constricts in its side-to-side dimension as it approaches the lower clamp. The pathway 41 is dimensioned such that the strip does not contact the sides 42 of the pathway at any time. Further, each plate 16, 17 has an inset or stepped / notched forward edge configured to enable the strip to move between the feeder roll of test strip and the lower clamp without obstruction from the plates.

[0081] Figure 15 shows a sharpness tester similar to any of those described above, except that that it includes side wheels 43 with finger grips 44 that can be turned by hand to wind the test strip 7 out from, or onto, the rolls 6, 9.

[0082] As will be appreciated, the testers described above and shown in the drawings are of a type that can be made relatively small for portability and relatively inexpensively.

[0083] While some forms of the invention have been described by way of example, it should be appreciated that modifications and improvements can be made without departing from the scope of the following claims.

[0084] In terms of disclosure, this document envisages and hereby posits any feature mentioned herein in combination with itself or any other feature or features mentioned herein, even if the combination is not claimed.

Claims

CLAIMS1. A blade sharpness tester comprising:• a roll of mesh strip;• a first clamp;• a second clamp;• a force sensor; and• a display;the tester being adapted such that:o the roll can be rotated by hand-force to cause a stretch of strip to be played out and secured by the first clamp;o the roll can then be rotated, or the strip otherwise moved, in a reverse direction by hand-force to generate tension in the strip such that if the second clamp is then activated a stretch of the strip will be held under tension by and between the clamps;o a blade can be manoeuvred through and along at least part of the tensioned stretch by hand force to make a cut along the strip while the sensor senses the level force required to make that cut; ando the display, based on what the sensor senses, presents information as to whether the level of force is indicative of a need to sharpen the blade.

2. A blade sharpness tester according to claim 1, comprising a side wall, a stub-shaft and a guard plate, arranged such that the feeder roll is located between the side wall and the guard plate so that the roll is able to rotate on the stub-shaft when the strip is played out from the roll.

3. A blade sharpness tester according to claim 2, wherein the stub-shaft has a stem and a head and the guard plate has an inverted keyhole shaped aperture having a lower lobe and an upper slot, the head being narrow enough to pass through the lobe but too wide to pass through the slot, the tester being such that the plate can be installed by hand-manoeuvring it so that the head passes through the lobe and the plate is able to then move downwards such that the stub-shaft’s stem extends through the slot with the feeder roll located between the plate and the side wall.

4. A blade sharpness tester according to claim 2 or 3, comprising a base having an upwards facing slot, and wherein the guard plate has a foot adapted to releasably engage with the slot to supportively retain the plate on the base.

5. A blade sharpness tester according to claim 2, 3 or 4, wherein the guard plate can be removed from the stub-shaft by hand-force to enable the feeder roll to be removed and replaced.

6. A blade sharpness tester according to any one of claims 2-5, wherein a portion of the outer circumference of the feeder roll projects beyond the guard plate so that the protruding portion can be engaged by hand to cause the feeder roll to rotate.

7. A blade sharpness tester according to any one of claims 2-6, wherein the feeder roll has a central bore hole which has three or more corners, arranged such that when the roll rotates the stub-shaft contacts the corners one after the other to impede such rotation.

8. A blade sharpness tester according to claim 7, wherein the bore hole is substantially square or triangular.

9. A blade sharpness tester according to any one of the preceding claims, comprising a receiver roll adapted to be hand-rotated on a stub-shaft to enable the stretch of strip to be wound onto it after the stretch has been cut in a blade sharpness test.

10. A blade sharpness tester according to claim 9, wherein the receiver roll is located between a further side wall and a further guard plate in the same manner as the feeder roll.

11. A blade sharpness tester according to anyone of the preceding claims, wherein the first clamp is located above the second clamp.

12. A blade sharpness tester according to anyone of the preceding claims, wherein the first clamp comprises a ratchet clamp.

13. A blade sharpness tester according to any one of the preceding claims, wherein the second clamp comprises a lever and a pair of jaws, the lever having a cam surface and being arranged such that when it is activated the cam surfaces move against one of the jaws to cause it to be in a clamping disposition with respect to the other jaw.

14. A blade sharpness tester according to anyone of the proceeding claims, comprising a stopper above the first clamp, positioned to prevent the blade from proceeding past it when a cut is created in the strip as noted in claim 115. A blade sharpness tester according to any one of the preceding claims, wherein the feeder roll is adapted to be hand-rotated rotated in either of two rotational directions, one after the other, when in use.

16. A blade sharpness tester according to any one of the preceding claims, comprising one or more sharpening pillar formed such that the blade can be drawn across it to sharpen the blade.

17. A blade sharpness tester according to claim 1, comprising a pair of pillars that extend from a base to support the display screen in spaced relationship to the base, the first clamp being at or adjacent to the top of the pillars and the second clamp being located at the base.

18. A blade sharpness tester according to claim 17, formed such that the blade can be gripped by hand and manoeuvred forward approximately at right angles to and between the pillars to cut the stretch of strip when held under tension between the clamps.

19. A blade sharpness tester according to any one of the preceding claims when engaged with the stretch of strip such that it is held under tension between the clamps.

20. A method of testing the sharpness of a blade, comprising accessing a blade sharpness tester according to any one of the preceding claims, rotating the feeder roll by way of hand-force such that an unused stretch of the strip extends between the clamps and is secured by the first clamp, rotating the roll in reverse, or otherwise moving the strip, by way of hand-force so that the stretch is tensioned between the clamps, engaging the second clamp such that the stretch is maintained under tension between the clamps, manoeuvring the blade such that it makes a vertical cut in the stretch such that during the cutting the sensor senses the amount of force exerted on the strip by the blade and, based on this, the display displays information indicative of whether the blade needs sharpening.

21. A method according to claim 20, wherein creating tension in the stretch of strip is achieved by rotating the feeder roll in reverse hand-force.

Images