GB2168630A - Apparatus for sharpening knives and the like - Google Patents

Abstract

An apparatus for sharpening knive blades or the like has two endless abrasive belts (1, 2) each mounted on a respective pair of pulleys (3, 4, 5, 6). The rotary axes of the pulleys are arranged substantially parallel with two of the pulleys (3, 4) being positioned adjacent one another such that the abrasive endless belts contact one another at a point (C) on a straight line drawn between the two pulley axes. The edge of the knife blade is inserted between the pulleys so that the abrasive belts, when driven, abrade or grind both sides of the blade edge simultaneously. <IMAGE>

Description

SPECIFICATION Apparatus for sharpening knives and the like This invention relates to apparatus for readily sharpening knives or similar edged instruments or tools.

According to the present invention there is provided an apparatus for sharpening a knife blade or the like comprising a support structure carrying a pair of rotary abrasive members having contiguous peripheries for receiving therebetween the edge of the said blade for abrasion or grinding thereof by driven rotation of said members in order to sharpen the edge at both sides of the blade simultaneously.

The present invention is further described hereinafter, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side elevation of a preferred embodiment of the present invention, with a cover removed; and Figure 2 is a plan view of the embodiment of Figure 1.

The apparatus shown in the drawings is for sharpening knife blades or the like and has a pair of abrasive members preferably consisting of endless abrasive belts 1, 2 i.e. belts exterially coated with abrasive material, each being supported for driven rotation on a respective pair of wheels or pulleys 3, 4, rotatable on substantially parallel axes 5 and 6. The arrangement is such as to provide a minimal gap between the belts on localised transverse peripheral contact C therebetween where the belts pass over adjacent guide or contact wheels 3, 4.

For simplicity and reduced cost of manufacture one belt viz. the belt 1 is driven by an electric or other drive motor 50 and the other or idler belt 2 is driven by frictional contact with the belt 1 at C, in which event the belts contact each other at C, so that the belts 1, 2 travel in opposite directions as indicated by the arrows. However, each belt 1, 2 may be separately driven if desired. For satisfactory operation and as later decribed the belts 1, 2 are tensioned by spring or other resilient means about their wheels and pulleys 3, 4, 5, and 6 whilst the motor pulley 5 for the belt 1 and the jockey pulley 6 for the belt 2 have a slight barrelled contour at their peripheries to maintain the belts 1,2 in a centralised position as they pass over the parallel peripheries of the guide wheels 3, 4 during running.

In use an edge E of a knife blade K such as a kitchen, carving or other cutlery knife blade is inserted between the driven belts 1, 2 down to the contact point C and then drawn longitudinally so that abrading or grinding of the blade K at the edge E is effected along the required length of the blade and at both sides of it simultaneously. Such mode of application is repeated as aften as necessary to obtain a satisfactory sharpening of the blade edge E.

Although the direction of rotation of the belts 1, 2 tends to resist insertion of the blade edge E between them it is found in practice that a "feel" of the correct depth of insertion can soon be acquired by a user without hindering the friction drive between the belts and without the need for stop or locating means for the blade, although these can be provided if necessary.

The motor 50, guide wheels 3, 4 and pulleys 5, 6 are supported in any suitable manner e.g. f rom a base board or other structure but in the example shown the motor spindle 51 and shafts 31, 41 and 61 for the guide wheels 3, 4 and jockey pulley 6 extend laterally from the support structure shown in the form of an inverted hollow casting 7 so that the belts 1,2 are positioned alongside the latter for ease of replacement. The non-rotatable shafts 31,'41 and 61 carry bearings 30, 40 and 60 for the guide wheels 3, 4 and jockey pulley 6 respectively.

In use the belts 1, 2 are housed in a cover 8 removably attached to the support casting 7, the cover having a slot 80 for insertion of a knife blade K between the belts 1, 2 which slot 80 is aligned with a transverse clearance recess 70 in the casting 7. Preferably, the cover 8 is formed in two parts and the slot forms a dividing line between these parts. The slot 80 is provided with sealing means such as opposed bristles 81 to prevent particles being thrown upwardly from the apparatus during knife sharpening. The slot 80 also guides the knife for correct positioning in relation to the belt peripheries i.e. substantially tangential to both of them.

The support casting 7 can be mounted in a position of use in any convenient manner and is particularly suited for mounting on or trom the upper edges of a box-iike f ree standing support or in a worktop. As a portable apparatus the support casting 7 can be mounted in a carrying case such as a briefcase of the rigid type i.e. from side walls W of one compartment of the latter. The case can carry a plug and flexible lead for the motor, spare belts e.g. of different grade and any other accessories.

Tensioning of the belts 1. 2 is preferably releasable to enable the belts 1,2 to be readily removed for replacement purposes after removal of the cover 8.

In the particular arrangement shown by way of example the motor 50 is pivotally suspended at 57 by a bracket 52 from the support casting 7 which bracket is resiliently loaded e.g. by a spring 53 so as to urge the motor 50 in a direction away from the guide wheel 3 and thus apply tension to the belt 1.

The guide wheel shaft 31 is suspended by a link 32 pivoted to the support casting at 37 the link 32 being locked against swinging movement towards the motor 50 during use as later described.

The guide wheel 4 for the idler belt 2 is pivotally suspended at 47 from the support casting 7 by a bracket 42 carrying the shaft 41 which bracket 42 is also resiliently loaded, e.g. by a spring 43, from the support casting 7 so as to urge the guide wheel 4 towards the guide wheel 3 and thus maintain contact at C between the peripheries of the belts 1,2.

The jockey pulley shaft 61 is suspended by a link 62 pivotally connected to the support casting 7 at 67 and a resilient loading in the form of, e.g. a compression spring 63 Located about and acting on a telescopic rod assembly 64 urges the bracket 42 and link 62 apart to tension the belt at 2.

To release tension in the belt 1 the link 32 is pivotally connected to an arm 93 operated for longitudinal movement by an eccentric 9 rotatably carried by the support casting 7. On appropriate clockwise turning movement of the eccentric 9, as seen in Figure 1, the whole assembly of the motor 50 and the guide wheel 3 initially moves under the force of the spring 53 until the bracket 52 comes into abutment with a fixed stop (not shown): at this point, further movement of the eccentric 9 causes the link 32 to be swung towards the motor 50 and thus releases the belt tension. The eccentric 9 is externally operated by a hand lever 99 secured to the eccentric shaft 90.

Simultaneously to release tension on the belt 2 a connecting rod 96 rotatably fitted about the eccentric 9 at one end is slotted at the other end at 960 where it slidably engages about a projection 610 of the jockey pulley shaft 61. When the eccentric 9 is turned by the lever 99 to slacken the belt 1 in the manner above described, the rod 96 is also drawn in generally the same direction as the arm 93 to cause the rear end of the slot 960 to abut the jockey pulley shaft projection 610. After an initial movement wherein the whole assemby of the guide wheel 4 and the pulley 6 moves under the force of the spring 43 to bring the bracket 42 into abutment with a fixed stop on the casting 7, the jockey pulley 6 is swung towards the guide wheel 4 to compress the spring 63 and remove tension on the belt 2.The slot 960 allows sufficient movement of the link 62 and shaft 61 for tensioning of the belt 2 by the action of the spring 63. It will be appreciated that the action of the lever 99 is an "overcentre" action in combination with the spring 63. That is, the spring 63 acts to pivot the lever 99 anticlockwise to retun it to its rest position until the lever, and therefore the eccentric 9, are turned through approximately 1800 when the spring then acts to pivot the lever clockwise and retain the lever in the "untensioned" position.

Thus by one simple operation of the lever 99 e.g. through approximately 1800 tension on both belts 1, 2 is removed and can be just as readily re-applied after belt replacement by return movement of the lever 99. When belt tension is applied the arm 93 abuts a stop peg 79 on the casting 7 at a position just over centre of the eccentric 9 and is thus maintained in that position by the belt tension so as to lock the link 32 against swinging movement towards the motor 50.

It is to be understood that various mechanisms may be employed for releasably applying tension to the belts 1.2 such as toggle linkage acting between the guide wheels 3, 4 and respective pulleys 5, 6.

For tensioning resilience and/or for belt peripheral contact and also for belt driving purposes the guide wheels 3, 4 or their peripheral parts may be of rubber or other suitable resilient material.

Instead of abrasive belts, grinding wheels may be provided at 3 and 4 or peripheral ly resilient contact wheels receiving removable abrasive bands which are gripped by radial expansion of the wheels during operative rotation. Here again one wheel may frictionally drive the other or each wheel may be separately driven. Such abrasive members may be urged into peripheral contact or close proximity by spring or other loading and/or by resilient peripheral action in the case of band receiving contact wheels.

Although the wheels 3, 4 may be of a soft, resilient material or have a rim of such material it has been found that a more efficient sharpening action is provided by a hard, nonresilient rim of, e.g. aluminium alloy, preferably over a resilient annular layer on a non-resilient core of e.g. metal. The resilient layer serves to damp noise and vibration. In addition, the radially outer surface of the non-resiiient rim may be provided with a central annular ridge extending over a proportion e. g. approximately a quarter, of the wheel width. This assists in transferring drive form the drive belt to the driven belt to reduce slipping. In addition, the position of pulley 6 or one or more of the other pulley or wheels may be finely adjustable along its rotational axis or laterally thereof to adjust tracking of the belt.

Claims (13)

1. An apparatus for sharpening a knife blade or the like comprising a support structure carrying a pair of rotary abrasive members having contiguous peripheries for receiving therebetween the edge of the said blade for abrasion or grinding thereof by driven rotation ot said members in order to sharpen the edge at both sides of the blade simultaneously.

2. An apparatus as claimed in claim 1 wherein one of said abrasive members is rotatably drivable by frictional contact with the other of said abrasive members.

3. An apparatus as claimed in claim 1 or 2 wherein at least one of said abrasive members is resiliently biased towards said other member by biasing means.

4. An apparatus as claimed in claim 3 wherein said at least one member is releasably biased towards said other member.

5. An apparatus as claimed in any of claims 1 to 4 wherein each rotary abrasive member comprises endless belt means supported around at least two pulley means.

6. An apparatus as claimed in claim 5 wherein each said belt means is tensioned by respective tensioning means.

7. An apparatus as claimed in claim 6 wherein each said belt means is releasably tensioned.

8. An apparatus as claimed in claim 7 wherein each said tensioning means is controlled by a common actuating mechanism for applying and releasing said tension.

9. An apparatus as claimed in claim 8 when appendant to claim 4 wherein said biasing means is controlled by said common actuating mechanism for applying and releasing said tension.

10. An apparatus as claimed in any of claims 5 to 9 wherein each said endless belt means passes around a respective guide pulley means arranged adjacent one another to provide said contiguous peripheries and wherein the radially outer peripheries of at least one said pulley means has a greater diameter intermediate the lateral edges of said periphery.

11. An apparatus as claimed in claim 10 wherein the outer periphery of said pulley means is barrelled.

12. An apparatus as claimed in claim 10 wherein said outer periphery of said pulley means has an annular rib intermediate its lateral edges.

13. An apparatus for sharpening a knife blade or the like substantially as herebefore described with reference to the accompanying drawings.