DE19700599C1 - Knife sharpener with cutting head - Google Patents

Abstract

The invention aims to provide a knife sharpener which, while removing high amounts of metal and presenting a low risk of injury, also improves the grinding and sharpening of both sides of a knife blade with a constant cut geometry. Grinding and sharpening should occur as close as possible to the end of the blade. The knife sharpener should be appropriate for food-processing purposes, dishwasher-proof, regenerable and easy to handle. The invention comprises a frame on which a sharpening head is mounted, the two halves of which consisting of spherical lamellar bodies (5, 6, 7, 8) with ball-bearing type grinding elements, which are positioned opposite and nested into each other with a degree of play and are mounted in a freely rotatable manner on one axis each in such a way that the inclination of these axes in the direction of the centre of the ball forms a sharpening slit which has the sharpening angle alpha . Special versions of the invention relate to knife sharpeners with a separate driving unit. The knife sharpener can be used for grinding and sharpening knives by means of surface, hollow or camber grinding to achieve symmetrical lateral surfaces.

Description

The invention relates to a knife sharpener according to the Generic term of Claim 1.

The current state of the art is characterized by two basic principles:

• 1. Sharpen parallel to the cutting edge
• 2. Sharpen essentially across the cutting edge

Sharpeners that act parallel to the cutting edge are, for example in DE 27 30 352 A1 or DE 89 14 318 U1 be wrote. They are the worst since they are low Have removal rate or nei to tear the cutting edge gene.

The sharpeners that work essentially across the cutting edge start with sharpening steel. This is still going to be special in the professional sector, viewed as the preferred sharper because its simple structure and its food safety offer greatest advantages. The big disadvantages, however, are the relatively complicated handling, the risk of injury and the low removal rate due to one-sided sharpening and the associated bending out of thin knife blades. A desirable constant cutting edge angle is through the subjective factor not attainable.

Knife sharpeners are used to eliminate these disadvantages have been developed, which are based on the working principle of two opposing frustoconical grinding body based hen. The knife is shaped here by the flanks of the V The annular gap is pulled through or pushed and it arises a grinding movement across the cutting edge (EP 00 99 382 B1, DE 37 02 751 A1, DE 43 41 872 A1,  GB 21 85 919 A, DE 39 01 127 A1). The disadvantages of this Above all, the sharpness lies in the low sharpening power, since there are only two punctiform sharpening points. A Another disadvantage is the limitation of the knife tack on the sharpening rollers, making a long piece of sharp edge is created. This allows very short measurements such as vegetable or pocket knives only in the front part be sharpened if the tapered rollers can also be swiveled be designed, such as in DE 39 01 127 A1.

The invention has for its object a knife to train sharper so that with high removal rate and low risk of injury from grinding on both sides and Sharpening knives with constant cutting edge geometry be improved. The grinding and sharpening is said to be close to the blade end can be done. The knife sharpener should food safe, dishwasher safe and regenerable be, as well as enable good handling.

According to the invention the object is achieved in claim 1 specified knife sharpener ge solves. Design features are in claims 2 to 12 described.

The knife sharpener consists of a frame, which in front preferably by a rack plate or a rack ring is formed and on the opposite two Ge adjusting sockets. Frame feet and a rack handle may be attached. The frame can also be used as Housing be formed.

The essential thing about the knife sharpener according to the invention is that newly trained sharpening head, which is a new sharpening principle enables. This be on the frame or in the housing sensitive sharpening head consists of two spherical lamellar bodies, the opposite one another with game like that telt and are freely rotatable on each axis that due to the inclination of the axes towards the ball  center of the sharpening gap with the sharpening angle α ent stands. The spherical lamellar bodies are preferably as annä formed hemispherical shells. It is advantageous it when these half shells are not only single-walled, but multiple nested double or triple-walled are executed, creating better circulation and guidance the cutting edge to be sharpened is reached. Also be thereby the removal performance when sharpening or grinding increases and the stability of the grinding wheels ver prolongs.

On the end faces of the spherical lamellar body, which through broken or full-walled can be the actual grinding surfaces. Either they exist Ball lamellar body completely from the abrasive material rial, for example ceramic injection molding, or there are Grinding wheel rings firmly applied depending on the application purpose from a variety of known materials can stand, or the grinding surfaces are with abrasive coated. The choice of materials for the grinding wheels depends on the material and the required fine Degree of withdrawal of the knives to be sharpened. For norma le rustproof hand knife is ceramic bound Si Silicon carbide fine grain very suitable. Likewise are natural whetstone materials such as B. Hart Arkansas or Mississippi can be used for fine prints. For the toughest Knife materials is a coating with a cubic crystal linem boron nitride (CBN) to diamond for ceramic Knives can be used.

The two spherical lamellar bodies preferably each have egg ne hub, in which the two axes are and the are in turn connected to the rack socket. The swivel speed of the spherical lamellar body is achieved in that the The hubs are rotatably mounted on the two axles and the Axles and frame bushings are firmly connected. Another possibility is that the axes in  the frame bushings are rotatably mounted and the axes and Hubs are firmly connected. To a quick De assembly, for example for cleaning or switching off replacement of the abrasive wheel, each will allow fixed connection lockable with studs det. The function of the two hubs can be multi-walled Ball slat bodies also through the ball slat bodies be taken over by this in the hub area are firmly connected.

The intersecting, nested sharpness head halves form a front active site and a rear Effective point. The two spherical lamellar bodies are the size of one Hemisphere formed so that between the knitting line w and the center of the sphere gives a distance r. The knife movement when pulling it through turns a automatic drive of the lamellar body reached. In principle, only one active site may be charged the. The sharpening effect is created by the knife with the Cutting edge placed on an effective point and in the direction pushed the opposite working point or is pulled without touching it. This ent stands an extremely advantageous sharpening process.

Another embodiment is a knife sharpener with se paratem drive. In contrast to the manual knife sharpener the sharpening head halves are driven by electro motor or by hand using a crank, hand lever with conversion in rotary motion or the like. With counter-rotating motion the sharpening head halves are the front and rear knives put usable at the same time. There can be no jamming effect come at the effective points. With co-rotation movement of the sharpening head halves is only the effective point bar where the rotation against the cutting edge takes place. The other active site must then be protected.  

The knife sharpener can be used as fixed table device or as a portable handheld device be educated. The forwarding of the To takes place drive rotation via either internally or externally toothed Ke gel gears.

In knife sharpening technology, there are three types of sharpening with regard to the side surfaces of the knife blade:

• 1. face grinding,
• 2. Hollow or concave grinding,
• 3. Crowned or convex cut.

All three types of cuts can be produced with the new active principle and are described geometrically below with the aid of FIG. 3:
The face grinding represents the special form of the working principle and corresponds to the representations of the knife sharpener variants. The most important feature is the coincidence of the working lines 17 and 18 with the straight line g, which runs parallel to the coordinate axis y. This corresponds to an effective line angle β of 90 °.

The hollow or concave grinding results when the lines of action 17 and 18 run obliquely outwards, ie the line of action angle β is less than 90 °.

The spherical or convex cut results from the inclined position of the lines of action from point of action 17 and 18 inwards, ie the line of action angle β is greater than 90 ° and can rise up to 180 °. Then the lines of action are parallel to the z-axis.

For certain purposes, it can be advantageous that the sharpening head, except for the area of the sharpening gap, from Housing is covered.

The advantages of the knife sharpener that works with the new operating principle are as follows:

• - very high removal rate,
• - Very long service life when face grinding in that despite wear of the grinding wheels over their entire width s maintain the grinder's functionality remains,
• - compliance with a constant, adjustable sharpening angle,
• - No cutting out of the cutting edge even with particularly thin ge sharpened knives, towards you diagonally opposite lying point contact,
• - no bending of the entire knife blade, since sharpening done simultaneously from both sides of the knife blade, with which very long and particularly thin knife problem are going to be sharpened
• - Due to the short effective point, there are also very short measurements it can be sharpened easily up to the knife booklet,
• - Food safety thanks to simple, constructive design processing and use of high quality materials such as rust free steel,
• - dishwasher safe,
• - very low risk of injury,
• - good standing due to three-point support,
• - Ensure lightweight design and small dimensions good handling and enable you to carry with you in a professional knife case,
• - Regenerability by replacing the entire ball lamellar body.

In the following the invention will be explained with reference to an embodiment game for a manual knife sharpener without a separate one Drive explained in more detail. Show it:

Fig. 1 is a side view of the knife sharpener

Fig. 2 is a plan view showing the handling

Fig. 3 is a section along the line II. Fig 1 from

Fig. 4 shows the section along the line II-II of FIG. 2.

The manual knife sharpener is one in its longitudinal plane, in which section II-II also lies, approximately symmetrical handheld device. It is for right and left handed users equally applicable.

The knife sharpener consists of a base frame and a sharpening head. The base frame has a hand-shaped frame handle 27 made of elastomeric material, which is dishwasher-safe and has a good grip. At the same time, the left end of this handle 27 represents one of the three non-slip device feet. The other two feet, frame foot rear 15 and frame foot front 16 , are made of the same material. These two frame feet 15 and 16 sit on the Ge collar 25th This, as well as all the following parts, except for the grinding wheels 1 , 2 , 3 and 4 , are made of stainless, food-safe steel.

On the frame ring 25 , the Ge right bushing 13 and on the left side of the frame bushing left 26 are welded. The frame bushing on the left 26 is in turn firmly connected to the frame handle core 24 .

The frame bushings 13 and 26 are so inclined on the Ge collar 25 that their central axes coincide with the sharpening angle α. The transverse bores of the Ge bushings 13 and 26 take the inclined axis sen 12 for the bearings of the sharpening head. Festge sets or solved the axes 12 by means of the threaded pins 11th The center lines of the axes 12 intersect at the center of the sphere 14 of the overall system.

The sharpening head consists of two halves, which are nested into each other, the sharpening gap 19 with the sharpening angle α bil. The left half consists of the hub 9 , which is firmly connected to the spherical disk bodies 5 and 7 . The grinding wheels 1 and 3 are fastened on these. The right half consists of the hub 10 , which is firmly connected to the spherical link bodies 6 and 8 . The grinding wheels 2 and 4 are fastened on these.

The grinding wheels 1 , 2 , 3 and 4 are geometrically Ku ring rings with from 1 to 4 ever smaller diameters. They are designed so that with constant or different ring thickness there is always a certain play from the inside diameter of the larger ring to the outside diameter of the next smaller ring, in order to ensure a free rotation of the rings.

The ball lamellar bodies 5, 6, 7 and 8 are so designed that their outer diameter is always than the respective outer diameter of the grinding bodies and their Innendurchmes are smaller ser always greater than the respective internal diameter of the abrasive body, the wall thickness of the respective Ku ie gell amelle body 5, 6, 7 , 8 is smaller than that of the respective grinding bodies 1 , 2 , 3 , 4 . The spherical lamellar bodies 5 , 6 , 7 and 8 are perforated in their surfaces to ensure a perfect flushing of the entire system when cleaning. But they can also be formed over the entire surface.

The two halves of the sharpening head described are freely rotatable on the axes 12 . The four penetrating grinding wheels 1 , 2 , 3 and 4 form with their grinding surfaces at the points where they cross, the apex of the sharpening angle α. The front knitting point 17 and the rear knitting point 18 result . The position of the annular grinding surfaces of the grinding wheels 1 , 2 , 3 and 4 , which are at right angles to the axis of rotation of the sharpening head, is dimensioned such that the dimension t is approximately 1/10 of the outer diameter of grinding wheel 1 and thus at the front Knitting point 17 or the rear knitting point 18 above the center of the ball 14, articulation points with the distance r from the coordinate axis y arise.

The one designed for normal rustproof hand knives Knife sharpener has ceramic-bonded grinding wheels a fine grain silicon carbide. The use of Sharpening liquids such as water, petroleum or oil aimed yourself after the use case. In the example described is sharpened dry.

The manual knife sharpener is handled as follows:
With the left hand, the device on the frame handle 27 he grips and firmly placed on a countertop. With the right hand, the knife on the knife handle 23 is grasped and brought into the starting position. For this purpose, it is inserted with the knife blade GE 20 vertically into the sharpening gap 19 in such a way that the tack-side end of the knife edge 21 is placed on the front active point 17 and the rear active point 18 is also contacted by the knife edge 21 . The knife sits on two points on the knife edge de 21 . In this position, a sense of proportion is taken on the longitudinal axis of the knife for the knife movement 29 to be carried out subsequently.

There are two options A and B the sharpening process to execute.

The sharpening process A is initiated with the unpressurized retraction of the knife from the starting position while maintaining the contact of the knife edge 21 to both active points 17 and 18 until the knife tip 22 after leaving the rear active point 18 has reached the front active point 17 . The sharpening head halves are still at a standstill. Then the knife movement 29 is reversed. Starting from the tip of the knife 22 , the knife edge 21 is pushed over the front active position 17 with so much pressure that the sharpening head halves are set in rotation. The grinding wheel movement 28 occurs. This knife movement 29 is carried out until the heftseiti ge end of the knife edge 21 is reached, then the reverse is repeated and repeated until the knife is sharp. The path of movement always corresponds to the cutting edge shape of the knife, ie the tangent of the knife cutting edge 21 must always coincide with this at the point of contact with the grinding wheels 1 , 2 , 3 , 4 , so the knife must be guided accordingly.

The sharpening process B is initiated from the starting position described above, by lifting the knife so that the knife edge 21 at the front knitting point 17 lifts slightly, but maintains contact with the rear knitting point 18 . Then the knife is withdrawn. This happens under so much pressure on the rear knitting point 18 , taking into account the non-contacting of the front knitting point 17 that the sharpening head halves are set in rotation. The grinding wheel movement 28 occurs. This knife movement 29 is carried out until the knife tip 22 has reached the rear active point 18 . The knife is then lifted off, moved forward, brought into the starting position and the sharpening process repeated. It is repeated until the knife is sharp.

The sharpening processes A and B can also be carried out in combination, depending on the nature of the knife. It should always be noted that only the working point is engaged, which is the first in the direction of movement of the knife, ie only the rear working point 18 must be engaged when the knife moves 29 towards the operator and 29 during the knife movement from the operator side away (push through) only the front knitting point 17 may be engaged. Otherwise, the cutting edge 21 becomes jammed.

In the case of the manual knife sharpener, the drive torque at the sharpening head is generated by the distance r of the straight line G from the coordinate axis y and the force applied during the knife movement 29 in the direction of this. Due to the fact ent is at the respective point of action a relative movement between the knife edge 21 and the grinding bodies 1, 2, 3 and 4 so that at the same time obliquely from both sides ge gene is sharpened cutting the 21st

The invention is based on two kinematic Principle of operation for separately driven knives Sharpening and knife sharpening devices explained. Show it:

Fig. 5 table device for hand-held knives

Fig. 6 hand tool for fixed knife.

For both variants, the basic structure of the sharpening head is analogous to that of the manual knife sharpener from FIGS . 1 to 4. According to FIGS. 5 and 6, the only difference is that in this case three opposing, nested spherical lamellar bodies with attached spherical ring-shaped bodies Grinding bodies form the sharpening gap 19 with the sharpening angle α.

In contrast to the manual knife sharpener, however the sharpening head halves are driven separately by means of electro engine.

The most important difference to the manual knife sharpener is the counter-rotating movement of the sharpening head halves. This means there is no clamping effect at the active points. The front knitting point 17 and the rear knitting point 18 can therefore be used simultaneously.

The desktop unit in FIG. 5 consists of the housing 30, z. B. in plastic injection molding, with the battery or netzbe driven electric gear motor 31 and the described sharpening head. The sharpening head is designed to be removable, dishwasher-safe and food-safe. The rotary movement of the sharpening head halves can either be carried out completely separately with two electric motors - favorable for the grinder variant - or, as shown, via motion transmission, driven by one side. From the drive pinion 32 , which is designed as an externally toothed bevel gear, the rotation is transmitted directly to the left sharpening head half by driving the internally toothed bevel gear 33 . The right sharpening half is driven by bevel gears 34 , 35 and 36 . The left bevel gear wheel 34 , for example via a hub 9 , is firmly connected to the left-hand sharpening head half. The central bevel gear wheel 35 , which is freely rotating on the axis 37 fixed to the frame, serves to reverse the direction of rotation of the right sharpening head half. The right bevel gear 36 is in turn firmly connected to the right sharpening half.

There are two options c and D the sharpening process to execute.

The sharpening process C proceeds as follows:
The knife is brought into the starting position described under A. As soon as the knife edge 21 contacts the line of action with its grinding surfaces running in opposite directions, the knife must immediately be pulled through evenly with slight pressure on the line of action. It is pushed back without pressure and then reversed again. It is repeated until the knife is sharp.

The grinding process, which is preferably used for the table variant shown in FIG. 5, is carried out in the same way as the sharpening process C.

The handheld device shown in FIG. 6 consists of the housing 30 , likewise advantageously in plastic injection molding, with a built-in rechargeable battery and the electric geared motor 31 operated therewith. The criteria for the sharpening head correspond to the above in Fig. 5. The opposite rotational movement of the sharpening head halves is achieved by the gear motor rotation from the drive bevel gear 38 to the bevel gear wheels 39 and 40 , which are firmly connected to the respective sharpening head halves.

The sharpening process D proceeds as follows:
The hand-held device is gripped with both hands, switched on and then brought to the cutting edge of the fixed machine knife 41 with the sharpening gap 19 . Simultaneously with the placement of the front knitting point 17 and the rear knitting point 18 , the hand-held device is guided along the edge of the knife evenly with slight pressure on the knitting points 17 and 18 . After reaching the end of the cutting edge, it is lifted, the sharpness is checked and, depending on the finish or repeated.

Claims (12)

1. Knife sharpener with a sharpening head located on a frame or in a housing and a holding or fastening device, characterized in that

• - The sharpening head consists of two opposing, at least single-walled and one-sided open spherical lamellar bodies ( 5 , 7 and 6 , 8 ), which are firmly connected to a hub ( 9 and 10 ),
• - The open grinding surfaces of the spherical disk bodies ( 5 , 7 and 6 , 8 ) are provided with an abrasive coating,
• - The two sharpening head halves ( 1 , 3 , 5 , 7 , 9 and 2 , 4 , 6 , 8 , 10 ) are nested with each other with play and are rotatably supported on one axis ( 12 ) in such a way that the axes ( 12 ) in the direction of the center of the sphere ( 14 ) the sharpening gap ( 19 ) with the sharpening angle α arises,
• - The axes ( 12 ) are connected to the frame.

2. Knife sharpener according to claim 1, characterized in that the axes ( 12 ) are detachably connected to the frame and can be locked by means of studs ( 11 ). 3. Knife sharpener according to one of claims 1 or 2, characterized in that the two spherical lamellar bodies by ( 5 , 7 and 6 , 8 ) such that the size of a hemisphere exceed that between the line of action w and the ball center ( 14 ) a distance r results. 4. Knife sharpener according to one of claims 1 or 2, characterized in that the spherical lamellar body ( 5 , 7 and 6 , 8 ) have an electric ( 31 ) or manual drive. 5. Knife sharpener according to claim 4, characterized in that the rotational movement of the spherical lamellar body ( 5 , 7 and 6 , 8 ) is opposed to ge. 6. Knife sharpener according to one of claims 4 or 5, characterized in that the drive rotation via a drive pinion ( 32 ), which is designed as an externally toothed bevel gear, directly on the drive-side sharpening head half ( 1 , 3 , 5 , 7 , 9 ) is done by an internally toothed cone gear ( 33 ) is driven and the right sharpening half ( 2 , 4 , 6 , 8 , 10 ) via bevel gears ( 34 , 35 , 36 ) is driven, with the drive-side bevel gear ( 34 ) firmly the drive-side sharpening head half ( 1 , 3 , 5 , 7 , 9 ) is connected, the central bevel gear ( 35 ), which is freely rotating on the frame-fixed axis ( 37 ), for reversing the direction of rotation of the right sharpening head half ( 2 , 4 , 6 , 8 , 10 ) and the right bevel gear ( 36 ) is firmly connected to the right sharpening head half ( 2 , 4 , 6 , 8 , 10 ). 7. Knife sharpener according to one of claims 4 or 5, characterized in that each of the two sharpening head halves ( 1 , 3 , 5 , 7 , 9 and 2 , 4 , 6 , 8 , 10 ) rotatably mounted on a respective fixed axis is driven. 8. Knife sharpener according to one of claims 4 or 5, characterized in that the drive rotation of a drive bevel gear ( 38 ) is transmitted to two bevel gears ( 39 , 40 ) which head halves with the respective sharpening ( 1 , 3 , 5 , 7 , 9 and 2 , 4 , 6 , 8 , 10 ) are fixedly connected and rotatably mounted on an axis fixed to the frame. 9. Knife sharpener according to one of claims 1 to 8, characterized characterized in that for hollow grinding the Wirkli angle β is less than 90 °.   10. Knife sharpener according to one of claims 1 to 8, there characterized by that for spherical cutting the Wirkli angle β is greater than 90 °. 11. Knife sharpener according to one of claims 1 to 10, characterized in that the sharpening head, except for the loading area of the sharpening gap ( 19 ), is covered by the housing ( 30 ). 12. Knife sharpener according to one of claims 1 to 11, characterized in that the spherical lamellar body ( 5 , 7 and 6 , 8 ) consist entirely of abrasive material.