EP3142830B1 - Sharpening device having abrasive belts arranged crosswise - Google Patents

Description

TECHNICAL FIELD TO WHICH THE INVENTION RELATES

The present invention relates to the general field of devices for sharpening the blades of cutting tools such as knives or the like.

It relates more particularly to such a sharpening device comprising at least two movable abrasive belts each provided with an active abrasive top surface and a bottom surface, which belts are offset longitudinally and arranged in a cross to form a crossing line defining, on one side, a sharpening dihedral formed by said moving top surfaces of said bands, and on the other side, an underlying dihedral, formed by said moving bottom surfaces of said bands. And it also relates to a sharpening process using such a device.

TECHNOLOGICAL BACKGROUND

For the blade of a cutting tool such as a knife to maintain good cutting power, it is necessary to subject it to regular sharpening operations and also to sharpening operations, when sharpening no longer restores enough cutting power.

The sharpening of a blade can be carried out by an operator, on a stone, belt, or other grinding wheel.

In this case, the operation requires experience and good dexterity to obtain the desired cutting profile, generally a profile with convex edges, called "rounded", or "shell-shaped", allowing a clean cut and a long life of the blade wire.

The document JP-2007 307658 discloses the preamble of claims 1 and 12.

To facilitate these sharpening operations, the documents JP-2007 307658 , US-2,222,361 , or the embodiment of Figure 10 of the document WO-2010007171 , propose a device of the type with endless mobile abrasive belts each provided with an abrasive top surface and a bottom surface. These documents more particularly describe devices in which the movable bands are offset longitudinally and arranged crosswise, to form a crossing line which defines, on one side, a sharpening dihedral (formed by the moving top surfaces of said bands ), and on the other side, an underlying dihedral (formed by the moving undersurfaces of the bands).

In this case, these sharpening devices are formed of three abrasive bands: - a first band guided by a driving pulley in the lower part and by a return pulley in the upper part, and - two second bands, arranged longitudinally on either side of the first, both guided by said lower driving pulley, and by another upper return pulley.

The sharpening operation is carried out by positioning the cutting edge of the tool in the sharpening dihedral, against the crossing line of the bands, in particular in the median plane of this sharpening dihedral.

In the embodiment of Figure 10 of the document WO-2010007171 , a support roller adjustable in position in a vertical plane is provided at the level of the underlying dihedral, with its active surface in contact with the underside surfaces of the bands, to allow adjustment of the angle of the sharpening dihedral . In the document JP-2007 307658 , two support rods (marked 58) are provided at the level of the underlying dihedral, resting against the endless bands, to allow the angle of the sharpening dihedral to be modified depending on the support applied to the cutting edge of the tool to be sharpened.

But such devices do not make it possible to easily obtain the desired curved cutting profile.

Indeed, the corresponding devices can only make it possible to obtain such a convex cutting edge profile through the dexterity of the operator, or from several sharpening stages, by modifying the sharpening angle by successions of adjustments of the support roller.

OBJECT OF THE INVENTION

The present invention proposes a simple and original solution for improving sharpening devices as described in the documents JP-2007 307658 , WO-2010007171 Or US-2,222,361 , in order to automatically obtain a rounded edge profile, by simple movements of the blade in the median plane of the sharpening dihedral.

For this, and in the context of a sharpening device as described in claim 1, that is to say comprising abrasive bands arranged in a cross, the present invention provides for the presence of means of support against the at least one of the underside surfaces of the bands, at the level of the underlying dihedral, which are adapted to alternately vary the angle of the sharpening dihedral during the movement of said bands.

Such a feature allows automatic variation of the sharpening angles of the blade to be sharpened, to obtain a shell or convex edge profile, this by simple movements of the blade in the plane or substantially in the median plane of the dihedral of sharpening.

According to a preferred characteristic, the support means in question are adapted to generate reciprocating movements whose frequency, per second, is greater than 10, and preferably greater than 20.

Still according to a preferred embodiment, these support means consist of a support roller whose active surface is cylindrical, which support roller is mounted to rotate around an axis off-centered relative to the axis of said cylindrical active surface.

Preferably, the axis of rotation of the support roller extends parallel or substantially parallel to the crossing line of the bands, and it is located in the plane or substantially in the median plane of the sharpening dihedral.

According to another characteristic, the sharpening device comprises means for adjusting the position of the support roller, in the plane or substantially in the median plane of the sharpening dihedral.

These adjustment means then advantageously consist of an elongated slot which extends perpendicular to the axis of said support roller, along which said roller is movable, and on which said roller can be locked in position, by any means of suitable locking.

The support roller is according to the invention mounted loosely around its axis of rotation, its active peripheral surface being in contact with said underlying dihedral formed by the undersides of said strips, and said support roller being driven in rotational movement by said bottom surfaces of said moving bands.

According to yet another characteristic, the abrasive bands wind on a common driving pulley, arranged on the side of the underlying dihedral, and on return pulleys, arranged on the side of the sharpening dihedral.

In this context, the sharpening device advantageously comprises, on the one hand, a first abrasive belt guided by a driving pulley and by a first return pulley, and on the other hand, two second abrasive belts, arranged longitudinally on either side other of the first abrasive belt, and guided by said driving pulley and by another return pulley.

The axes of rotation of the driving pulley, the return pulleys and the support roller are then advantageously parallel to each other, and the median plane of the sharpening dihedral extends vertically or substantially vertically, the pulleys of return being provided in the upper part, and the driving pulley in the lower part.

According to yet another characteristic, the sharpening device comprises a support frame on which said return pulleys and said support means are mounted, said driving pulley being driven in rotation by a motor carried by a carriage which is slidably mounted on a system of slides provided on said support frame, which slides are adapted to ensure automatic tensioning of said strips by the weight or at least part of the weight of said motorization.

This feature allows automatic tensioning of the bands, and authorizes, if necessary, a rapid change of these bands.

Said slides preferably extend in a plane perpendicular to the axis of rotation of the driving pulley and to the median plane of the sharpening dihedral.

Furthermore, said support frame preferably comprises a support plate from one of the faces of which extend overhanging said return pulleys and said support means, and against the other face of which said slides are provided.

According to yet another characteristic, the plane in which the abrasive belts extend is inclined forward relative to the vertical, at an angle between 25° and 45°, this to optimize the ergonomics of the operation. 'sharpening.

The invention also relates to a sharpening method for a knife-type cutting tool blade or the like according to claim 12.

DETAILED DESCRIPTION OF AN EXAMPLE OF WORK

• la figure 1 est une vue en perspective, légèrement par devant, d'un dispositif d'affûtage conforme à l'invention, une partie de son carter périphérique de protection ayant été enlevée ;
• la figure 2 est une vue en perspective par l'arrière du dispositif d'affûtage de la figure 1 ;
• la figure 3 montre le dispositif d'affûtage des figures 1 et 2 vu de face ;
• la figure 4 est une vue de dessus du dispositif d'affûtage des figures 1 à 3 ;
• la figure 5 est une vue de côté du dispositif d'affûtage des figures 1 à 4 ;
• la figure 6 est une vue en perspective partielle par l'arrière du dispositif d'affûtage des figures 1 à 5, la quasi totalité de son châssis support ayant été enlevée ;
• la figure 7 est une vue schématique en perspective des bandes abrasives du dispositif d'affûtage des figures 1 à 6, enroulées autour de leur poulie motrice et de leur poulie de renvoi, et associées au galet d'appui assurant la variation alternative de l'angle du dièdre d'affûtage ;
• la figure 8 est une vue de face de l'ensemble bandes/poulies/galet d'appui de la figure 5 ;
• la figure 9 est une vue de face isolée, du galet d'appui, illustrant sa surface cylindrique active décentrée.

The invention will be further illustrated, without being in any way limited, by the following description of a particular embodiment, given solely by way of example and represented in the appended drawings in which:

• there figure 1 is a perspective view, slightly from the front, of a sharpening device according to the invention, part of its peripheral protective casing having been removed;
• there figure 2 is a perspective view from the rear of the sharpening device of the figure 1 ;
• there Figure 3 shows the sharpening device figures 1 and 2 seen from the front;
• there figure 4 is a top view of the sharpening device figures 1 to 3 ;
• there figure 5 is a side view of the sharpening device figures 1 to 4 ;
• there Figure 6 is a partial perspective view from the rear of the sharpening device figures 1 to 5 , almost all of its support frame having been removed;
• there Figure 7 is a schematic perspective view of the abrasive belts of the sharpening device figures 1 to 6 , wound around their driving pulley and their return pulley, and associated with the support roller ensuring the alternating variation of the angle of the sharpening dihedral;
• there figure 8 is a front view of the belt/pulley/support roller assembly of the figure 5 ;
• there Figure 9 is an isolated front view of the support roller, illustrating its off-centered active cylindrical surface.

The sharpening device 1 illustrated on the figures 1 to 9 includes three abrasive belts 2, 3 and 4, in the form of endless belts. A first strip 2 winds around a lower driving pulley 5 and around a first upper return pulley 6; and two second bands 3 and 4 wind around said lower driving pulley 5 and around a second return pulley 7, this parallel to each other, and arranged longitudinally on either side of said first band 2.

The endless bands 2, 3 and 4 are advantageously identical to each other. They comprise an active abrasive top surface 2 a , 3 a , 4 a and an advantageously non-abrasive bottom surface 2 b , 3 b , 4 b .

Any abrasive belt known to those skilled in the art can be used for the use of the sharpening device 1.

The axis 5' of the common driving pulley 5 extends parallel to the axis 6', 7' of the two return pulleys 6, 7.

The two return pulleys 6 and 7 are arranged in the same horizontal plane, their axes 6', 7' being placed symmetrically with respect to the vertical plane through which the axis 5' of the driving pulley 5 passes.

The abrasive belt 2, on the one hand, and the abrasive belts 3 and 4, on the other hand, are thus arranged in a cross, that is to say they cross to form a crossing line 8.

This crossing line 8 defines, on one side (in the upper part) an upper sharpening dihedral 9 formed by the abrasive top surfaces 2 a , 3 a , 4 a of the bands 2, 3, 4, and the other side (in the lower part) a lower dihedral 10, called “underlying dihedral”, formed by the lower surfaces 2 b , 3 b , 4 b of bands 2, 3 and 4.

The upper return pulleys 6 and 7 are mounted free to rotate on a support frame 11 of the sharpening device 1.

The driving pulley 5 here has a diameter of between 3 and 4 times the diameter of the return pulleys 6 and 7; preferably the driving pulley 5 and the return pulleys 6, 7 have peripheral grooves adapted to maintaining the position of the bands 2, 3 and 4 which they guide.

On the other hand, the driving pulley 5 is rotated by a motor 12, preferably an electric motor. The sharpening device 1 includes an on/off switch 12 a , for switching the motor 12 on or off, visible on the figure 2 , 4 and 5 .

According to a characteristic of the sharpening device 1, this motorization 12 is carried by a carriage 13 which is slidably mounted, on a system of slides 14 provided on the support frame 11, in a plane perpendicular or substantially perpendicular to the axis of the driving pulley 5 ( Figure 6 ).

This carriage 13 slidably mounted on the slide system 14, and which carries the motor 12 with the driving pulley 5, is supported by the three abrasive belts 2, 3 and 4 (via the driving pulley 5), this which ensures the automatic tensioning of the latter, by the weight of the carriage 13/motorization 12/pulley 5 assembly, and which also allows rapid replacement of these bands 2, 3, 4, by simply lifting this assembly , if needed.

At the level of the underlying dihedral 10 of the sharpening device 1, we note the presence of support means 15 which are arranged, in accordance with the present invention, to allow variation, in an alternative manner, of the angle of the dihedral sharpening 9 during the movement of the abrasive belts 2, 3, 4, driven by the driving pulley 5.

These support means consist here of a support roller 15 mounted idly in rotation around an axis 15 a secured to the chassis 11, and whose active surface 15 b (corresponding to its peripheral surface) comprises at least one off-center zone relative to said axis 15 a .

In this case, as can be seen in the Figure 9 , this support roller 15 comprises an active surface 15 b which is cylindrical, which cylindrical surface 15 b is not centered on the axis of rotation 15 a .

To visualize this decentering, we traced on the Figure 9 , dotted, a virtual circle 15 c centered on the axis 15 a .

The cylindrical active surface 15 b of the support roller 15 is placed in contact with the underlying dihedral 10 mentioned above, formed by the bottom faces 2 b , 3 b , 4 b of the bands 2, 3 and 4. This active surface is preferably knurled to optimize the rotational drive of the roller 15.

It is understood that this support roller 15 is driven in rotation around its axis 15 a by the friction, on its periphery, of the surface below 2 b , 3 b , 4 b of the different bands 2, 3, 4 , themselves driven by the motorized pulley 5.

As illustrated on the figure 8 , driving the motorized pulley 5 in a clockwise direction, according to the orientation arrow 16, ensures the driving of the bands 2, on the one hand, and 3, 4, on the other hand, according to the orientation arrows 17 and 18, respectively.

The return pulleys 6 and 7 here rotate in a clockwise direction, driven by said bands 2, 3 and 4, and the support roller 15 also rotates in a clockwise direction, as illustrated by the orientation arrow 19.

The sharpening dihedral 9 comprises a median plane P on either side of which the return pulleys 6, 7 are arranged and in which the axis 15 a of the support roller 15 and the axis 5' extend of the driving pulley 5. This sharpening dihedral 9 is located above the crossing line 8, the latter being located above the underlying dihedral 10, the support roller 15 and the driving pulley 5 .

The movement of the bands 2 and 3, 4 allows an operator to sharpen a tool blade placed at the level of the sharpening dihedral 9, with its cutting edge resting against the crossing line 8 of the bands 2, 3 and 4.

Simultaneously, we understand that the rotation of the roller 15 bearing against said bottom faces 2 b , 3 b , 4 b of the bands 2, 3, 4 automatically modifies, alternately and continuously, the angle of the underlying dihedral 10, and therefore the angle of the sharpening dihedral 9, allowing the desired “rounded” cutting edge to be obtained, while maintaining the blade to be sharpened in the median plane or substantially in the median plane P of the sharpening dihedral 9 ( the operator then simply moves the blade forwards and/or backwards to ensure sharpening over its entire length, maintaining it substantially in the median plane of the sharpening dihedral).

The “rounded” cutting edge is obtained automatically due to the alternating variations in the positioning of the plane of the active surface 2a , 3a , 4a of the bands 2 and 3, 4, thanks to the rotation of the roller with an off-centered axis 15.

The alternative movement of the plane of the bands 2, 3, 4 at the level of the sharpening dihedral 9, and therefore the variation of the angle of the sharpening dihedral 9, can be adapted according to the result that one wishes to obtain, in particularly by modifying the dimensional characteristics of the support means 15 and/or their positioning.

For example, the offset of the axis 15 a of the support roller 15 relative to the axis of its cylindrical active surface 15 b can be a few tenths of a millimeter, for example of the order of 0.2 to 1 mm, for a support roller 15 having 42 mm in diameter, a driving pulley 5 having 100 mm in diameter and return pulleys 6, 7 having 33 mm in diameter.

The value of the alternative angular variation sought for the sharpening dihedral 9 can be determined by adjusting the position of the support roller 15 in the plane or substantially in the plane of said sharpening dihedral 9.

The corresponding adjustment means (not present in the embodiment illustrated in the figures) can consist of an elongated slot, provided perpendicular to the axis of the support roller 15, in the plane or substantially in the median plane P of the dihedral sharpening device 9, along which said roller 15 is movably mounted, and on which said roller 15 can be locked in position, by any suitable locking means (for example by a screw-nut type locking system).

The support means 15 in association with the drive characteristics of the bands 2, 3, 4 (in particular their linear speed) are advantageously adapted to generate reciprocating movements whose frequency is greater than 10 per second, and preferably greater at 20 per second, and more preferably between 30 and 70 per second.

The support frame 11 of the sharpening device 1 comprises in particular a lower base 20 intended to rest on any suitable support, for example a table or a receiving tray, from which extend upwards two connected lateral sides 21 by a spacer plate 22.

The two lateral sides 21 form part of the peripheral casing of the sharpening device 1. The spacer plate 22 extends inside the device. It serves in particular as a support for the axes of the two return pulleys 6 and 7, and for the axis of the support roller 15, which extend overhanging from one of its faces; its opposite face serves as a support for the slides 14 for guiding the carriage 13 ( figure 2 ).

This support plate 22, not shown on the Figure 6 , may include the aforementioned elongated slot for adjusting the positioning of the support roller 15, the axis of the latter then being equipped with the associated removable locking means (for example in the form of a screw-nut system).

This support plate 22 also includes an upper middle opening 23 making it possible not to hinder the movements of the tool blade that is to be sharpened, during its sharpening operation, as well as a lower opening 24 for free movement. in translation of the carriage 13/motorization 12/pulley 5 assembly, along the aforementioned slide system 14.

The support plate 22 advantageously extends in a plane inclined towards the front when the sharpening device 1 is in position on its table or its receiving plate, so that the different strips 2, 3, 4 extend in a parallel inclined plane, in order to improve the ergonomics of sharpening operations. The corresponding angle of inclination has, relative to the vertical, visible on the figure 5 , can be of the order of 25° to 45°.

The sharpening device 1 advantageously comprises a peripheral casing adapted to protect its constituent functional elements, as well as the operator responsible for sharpening a tool blade.

This peripheral casing comprises in particular a front part to hide the driving pulley 5 and the support roller 15, as well as a rear part to hide the motorization 12, which do not appear on the figures 1 to 6 to facilitate the understanding of the structure of the sharpening device 1.

These front and rear parts of the casing are preferably provided as removable.

At the level of an opening 25 provided on the top and the front of the casing of the device 1 to carry out the sharpening operations (that is to say above and in front of the sharpening dihedral 9), we notice the presence of a blade guide device 26 in the general shape of a V, the tip of which is open downwards. In addition, behind this blade guide device 26, a stop structure 27, with a V-shaped section, ensures the protection of the internal mechanics against attacks from dust linked to sharpening, and against possible blade blows. This stop structure 27 is preferably made of a material that is not aggressive to the blade, for example polypropylene; it can be attached to the rear part of the protective casing. Fixed discs 28 are positioned at the overhanging end of the axes of the return pulleys 6 and 7, to protect these pulleys 6 and 7 against attacks from the blades during sharpening.

Alternatively, the support means 15 can be in a form other than a rotating roller with an off-center active surface.

According to an example which is not covered by the invention according to the attached claims, these support means 15 can consist of a roller with an elongated section, for example oval, or even of a movable structure in horizontal translation, according to alternating movements, and whose ends come to rest against the surfaces below 2 b ; 3 b , 4 b of bands 2; 3, 4 in order to alternately vary the angle of the sharpening dihedral 9.

According to another example which is not covered by the invention according to the attached claims, the support means 15 can also be adapted to come into contact with only one of said strips 2, 3, 4, or two of them .

Claims (12)

1. A sharpening device (1) for a cutting tool blade of the knife type or similar, said sharpening device (1) comprising at least two mobile abrasive belts (2; 3, 4) each provided with an active abrasive top surface (2a, 3a, 4a) and a bottom surface (2b, 3b, 4b), wherein the belts (2; 3, 4) being longitudinally staggered and arranged crosswise to form a crossing line (8) defining, on one side, a sharpening dihedron (9) formed by said moving top surfaces (2a, 3a, 4a) of said belts (2, 3, 4), and on the other side, an underlying dihedron (10), formed by said moving bottom surfaces (2b, 3b, 4b) of said belts (2, 3, 4),

   the device including means (15) for pressing against at least one of said bottom surfaces (2b, 3b, 4b) of said belts (2, 3, 4), at said underlying dihedron (10), which are adapted to alternately vary the angle of said sharpening dihedron during movement of said belts (2, 3, 4),

   said pressing means consisting of a pressing roller (15),

   the device being characterized in that said pressing roller is mounted so as to rotate freely about an axis of rotation (15a) and the active peripheral surface (15b) of the pressing roller (15), includes at least one area non centred on said axis of rotation (15a),

   said active peripheral surface (15b) of said pressing roller (15) being in contact with said underlying dihedron (10) formed by the bottom faces (2b, 3b, 4b) of said belts (2, 3, 4), and said pressing roller (15) being driven in rotation by said bottom surfaces (2b, 3b, 4b) of said moving belts (2, 3, 4).
2. The sharpening device according to claim 1, characterized in that said pressing means (15) are adapted to generate alternating movements whose frequency, per second, is higher than 10, and preferably higher than 20.
3. The sharpening device according to any one of claims 1 or 2, characterized in that said pressing means (15) consist of a pressing roller whose active surface (15b) is cylindrical, said pressing roller (15) being mounted for rotation about an axis (15a) off-centre with respect to the axis of said cylindrical active surface (15b).
4. The sharpening device according to any one of claims 1 to 3, characterized in that the axis of rotation (15a) of said pressing roller (15) extends parallel or substantially parallel to said crossing line (8) of said belts (2, 3, 4), and is located in the median plane or substantially in the median plane of said sharpening dihedron (9).
5. The sharpening device according to any one of claims 1 to 4, characterized in that it includes means for adjusting the position of said pressing roller (15), in the median plane or substantially in the median plane of said sharpening dihedron (9).
6. The sharpening device according to claim 5, characterized in that said adjustment means consist of an elongated aperture that extends perpendicular to the axis of said pressing roller (15), along which said roller (15) is movable, and on which said roller (15) can be locked in position, by any suitable locking means.
7. The sharpening device according to any one of claims 1 to 6, characterized in that said abrasive belts (2, 3, 4) are wound onto a common drive pulley (5), arranged on the side of the underlying dihedron (10), and onto deflecting pulleys (6, 7), arranged on the side of the sharpening dihedron (9).
8. The sharpening device according to claim 7, characterized in that it includes, on the one hand, a first abrasive belt (2) guided by said drive pulley (5) and by a first deflecting pulley (6), and on the other hand, two second abrasive belts (3, 4), arranged longitudinally on either side of the first abrasive belt (2), and guided by said drive pulley (5) and by another deflecting pulley (7), the axes of rotation (5', 6', 7', 15a) of the drive pulley (5), the deflecting pulleys (6, 7) and the pressing roller (15) being parallel to each other, and the median plane (P) of the sharpening dihedron (9) extending vertically or substantially vertically, said deflecting pulleys (6, 7) being arranged at the top and said drive pulley (5) at the bottom.
9. The sharpening device according to any one of claims 7 or 8, characterized in that it includes a support frame (11) on which are mounted said deflecting pulleys (6, 7) and said pressing means (15), said drive pulley (5) being driven in rotation by a motor (12) carried by a carriage (13) sliding on a slide system (14) arranged on said support frame (11), said slides (14) extending in a plane perpendicular to the axis of rotation (5') of the drive pulley (5) and to the median plane (P) of the sharpening dihedron (9), and being suitable to ensure an automatic tensioning of said belts (2, 3, 4) by the weight or at least part of the weight of said motor (12).
10. The device according to claim 9, characterized in that said support frame (11) includes a support plate (22) from one face of which said deflecting pulleys (6, 7) and said pressing means (15) extend as a cantilever, and against the other face of which said slides (14) are arranged.
11. The sharpening device according to any one of claims 1 to 10, characterized in that the plane in which the abrasive belts (2, 3, 4) extend is tilted towards the front with respect to the vertical, with an angle (a) between 25° and 45°.
12. A method for sharpening a cutting tool blade of the knife type or similar, by means of at least two mobile abrasive belts (2, 3, 4) each provided with an active abrasive top surface (2a, 3a, 4a) and a bottom surface (2b, 3b, 4b), said belts (2, 3, 4) being longitudinally staggered and arranged crosswise to form a crossing line (8) defining, on one side, a sharpening dihedron (9) formed by said moving top surfaces (2a, 3a, 4a) of said belts (2, 3, 4), and on the other side, an underlying dihedron (10), formed by said moving bottom surfaces (2b, 3b, 4b) of said belts (2, 3, 4),

    the method consisting in implementing means (15) for pressing against at least one of said bottom surfaces (2b, 3b, 4b) of said belts (2, 3, 4), at said underlying dihedron (10), in order to alternately vary the angle of said sharpening dihedron (9) during movement of said belts (2, 3, 4),

    the method being characterized in that the angle of said sharpening dihedron (9) is varied by alternating movements whose frequency, per second, is higher than 10, and preferably higher than 20.

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