Knife sharpeners suitable for wet grinding

Abstract

Device for manually grinding and / or polishing the blade of a cutting tool, in particular a kitchen or household knife, comprising a body (10) on or in which a shaft (30) is rotatably mounted, the shaft having a virtual longitudinal direction (LR) assigned to it; a grinding wheel arrangement (40) and a polishing wheel arrangement (60) are rotatably attached to this shaft (30), each consisting of two identical circular discs that touch each other at the center of a mutually facing disc side and that each have a planar conical surface on this disc side that rises slightly from the disc edge to the disc center, so that pairs of conical surfaces form the groove flanks of a circumferential V-shaped groove (55 or 75) that widens towards the circumference of the disc; and Each conical surface is designed either as a grinding surface or as a polishing surface; and For grinding or polishing, the blade is inserted into this V-shaped groove (55 or 75) and moved back and forth within the groove (55 or 75) by the user's hand holding the knife, which sets the shaft (30) in rotation and grinds or polishes or hones the cutting surface in contact with the respective rotating working surface; characterized by the fact that the body 10) is an elongated, semi-open trough enclosing an interior space, consisting of the following trough components: a base plate (12), two spaced-apart side walls (14 and 16), an end wall (18), an end plate (22) and a cover plate (20) having a central gap (21); and in each of the two side walls (14 and 16) a recess (15 or 17) adjoining the contour of the gap (21) is formed in order to be able to insert the blade to be treated through the gap (21) and the recesses (15 and 17) into the V-shaped groove (55 or 75) in one or the other disc arrangement (40 or 60) located in the interior of the trough; and the aforementioned trough components, namely the base plate (12), the two side walls (14 and 16), the end wall (18), the cover plate (20) and an inner end plate (22), form a single-piece body (10) made of plastic or metal, and an outer end plate (25) made of the same material can be attached to this single-piece body (10) by means of a screw (28); and an inner ball bearing (24) is fixedly mounted on the inside of the inner end plate (22) and an outer ball bearing (27) is fixedly mounted on the inside of the outer end plate (25), each ball bearing (24 or 27) being provided with an easily rotatable inner ring; and the shaft (30) has two spaced-apart shaft ends (31 and 32), each of which is rotatably inserted into an inner ring of the ball bearings (24 and 27, respectively), so that the grinding wheel assembly (40) and polishing wheel assembly (60) attached to the shaft (30) are each easily rotatable within the trough interior; and the screw (28) is a threaded screw and has a threaded screw end (29); and the shaft (30) is a hollow shaft, and the screw (28) is passed through the interior of this hollow shaft and is inserted and secured with the threaded screw end (29) into a threaded bore recessed in the inner end plate (22).

Description

TECHNICAL FIELD

[0001] The present invention relates to the technical field of hand-operated devices for grinding and / or polishing cutting tools, in particular knives for use in the kitchen and household. The knife has a blade with an edge to be sharpened. The user's hand grasps the knife, places the edge against a grinding surface of a stationary and rotatable grinding wheel, and moves the knife back and forth so that the edge, in contact with the grinding surface, performs a back-and-forth movement, causing the grinding wheel to rotate. Consequently, the knife blade is ground and sharpened by a constantly renewed, rotating grinding surface section. Wet grinding in water, oil, or other emulsion protects the grinding surface and delivers an even finer grind with lasting sharpness. Polishing or honing the ground knife blade removes grinding debris and deburrs the edge. STATE OF THE ART

[0002] Document US 2013 / 0295823 A1 discloses a knife or blade sharpener with a handle to which an elongated box is attached, in which two grinding devices are housed and secured. Each grinding device includes a largely closed rectangular container, in the end walls of which a shaft is rotatably mounted, to which a grinding wheel assembly is attached, which has two grinding wheels contacting each other near the shaft. Adjacent to this contact zone, a flat grinding surface facing each other is formed on each of the grinding wheels. These grinding surfaces are aligned according to the groove flanks of a V-shaped groove that widens towards the circumference of the wheel. The groove flanks enclose a groove angle that can assume values ​​from 20° to 65°. Slots in the cover plate and adapted recesses in the side walls of the box allow the knife blade to be inserted into the V-shaped groove.The knife blade to be sharpened is inserted into this groove by the user and moved back and forth along a grinding surface with one side of the blade in the system, causing the grinding wheel assembly to rotate. Water or oil is poured into each container of the two grinding units, into which the rotating grinding wheel assembly is immersed. During wet grinding of the blade, the liquid absorbs the heat generated during the grinding process and prevents the blade from becoming dull and blunt, which would otherwise be caused by the heat. Furthermore, the liquid removes the abrasion generated during grinding and keeps the grinding surfaces in good grinding condition without clogging them. In the two grinding units, grinding surfaces made of different grinding materials can be provided; examples of grinding materials include aluminum oxide, silica, and silicon carbide ceramics.

[0003] However, it seems comparatively complex to accommodate two complete grinding devices in one box, each with a container into which the liquid required for wet grinding is to be filled.

[0004] Document EP 3278928 A2 discloses a device for grinding and / or polishing a cutting tool. The device is designed as a so-called roller grinder and has a cylindrical handle in which a shaft is rotatably mounted. At one end of the shaft is a grinding wheel and at the other end, a polishing wheel. The knife to be sharpened is fixedly mounted on a base; the user moves the handle back and forth on this base, with both wheels rolling on the base, and one of the two rotating wheels resting against the knife blade, grinding or polishing it. The grinding wheel has a grinding surface that can consist of a nickel layer electroplated onto a metal core, in which grains of synthetic diamond are dispersed.The polishing disc serves to polish or hone the ground blade and has a polishing layer which may consist of a metal layer in which at least one, preferably several, recess(es) concentric to the disc centre point are formed.

[0005] The German design 402020202386, with design representations -0003.1 and -0003.2 as well as -0005-1 and -0005.2, shows a knife grinder with a solid, elongated, octagonal body, on one end face of which is a grinding wheel assembly and on the other end face of which is apparently a polishing wheel assembly. Both assemblies each have two circular, metallic discs touching each other in the center, between which – adjacent to the contact zone – a circumferential V-shaped groove is formed, widening toward the disc circumference. The two assemblies are apparently mounted in a rotationally fixed manner on a shaft that is rotatably mounted within the body. TASK

[0006] Based on this, the object of the present invention is to provide a structurally simpler knife sharpener of the type described, which performs a grinding function and a polishing or honing function and which is better suited for wet treatment for both functions. INVENTIVE SOLUTION

[0007] Starting from a Device for manually grinding and / or polishing the blade of a cutting tool, in particular a kitchen or household knife, comprising a body on which or in which a shaft is rotatably mounted, to which a virtual shaft longitudinal direction is assigned; a grinding wheel arrangement and a polishing wheel arrangement are mounted on this shaft in a rotationally fixed manner, each consisting of two circular, identical discs which touch each other in the centre of a disc side facing each other and which each have a flat conical surface on this disc side which rises slightly from the disc edge to the disc centre, so that pairs of conical surfaces form the groove flanks of a circumferential V-shaped groove which widens towards the disc circumference; and each conical surface is designed either as an effective surface for grinding or as an effective surface for polishing; and for grinding or polishing, the blade is inserted into this V-shaped groove and is moved back and forth within this V-shaped groove by the user's hand holding the knife, which sets the shaft in rotation and grinds, polishes or hones the cutting surface lying against the respective rotating active surface; The solution to the above problem according to the invention is characterized in that the body is an elongated, semi-open trough enclosing a trough interior, which consists of the following trough components: a base plate, two spaced-apart side walls, an end face, an end plate, and a cover plate having a central gap; and in each of the two side walls, a recess is formed which adjoins the contour of the gap in order to be able to insert the blade to be treated through the gap and the recesses into the V-shaped groove in one or the other disc arrangement located in the trough interior; and the above-mentioned trough components, namely the base plate, the two side walls, the end face, the inner end plate and the cover plate, form a one-piece body made of plastic or metal, and an outer end plate made of the same material can be fastened to this one-piece body by means of a screw; and an inner ball bearing is fixedly mounted on the inside of the inner end plate and an outer ball bearing is fixedly mounted on the inside of the outer end plate, each ball bearing being provided with a slightly rotatable inner ring; and the shaft has two spaced-apart shaft ends, each of which is non-rotatably inserted into an inner ring of the ball bearings, so that the grinding wheel assembly and polishing wheel assembly attached to the shaft are each housed in the trough interior in a slightly rotatable manner; and the screw is a threaded screw and has a threaded screw end; and the shaft is a hollow shaft, and the screw is passed through the interior of this hollow shaft and is inserted with the threaded screw end into a threaded hole recessed in the inner end plate and is secured therein.

[0008] "A flat conical surface rising slightly from the disc edge to the disc center or the disc center" here means a flat conical surface whose alignment with the plane of the disc rear side encloses half a groove angle (Z angle at parallels); and in the case of the exemplary embodiment described in detail below, in particular encloses an angle of approximately 15° to approximately 20°.

[0009] Water or another liquid intended for wet treatment can be poured into the moisture-proof and largely closed trough interior in order to carry out the grinding process of the blade as a wet grinding process and the polishing treatment of the blade as a wet polishing process.

[0010] During wet grinding, abrasive particles are bound in a liquid, such as water, oil, or other emulsion; less abrasive debris settles on the grinding wheels, and the wheels are rinsed clean. Overall, a better grinding result is achieved more quickly. ADVANTAGEOUS DESIGNS

[0011] Advantageous embodiments and preferred embodiments of the invention emerge from the subclaims, the following description and the accompanying drawings.

[0012] The trough typically forms a cuboid-shaped body with a length of 50 to 80 mm, preferably a length of about 65 mm, and a square cross-section with a width / height of 35 mm to 55 mm, preferably a width / height of about 45 mm.

[0013] "Approximately" here and elsewhere in this document refers to a range from minus 3% to plus 3% of the stated numerical value; consequently, in the present case, a trough length of approximately 65 mm may actually have values ​​of 63.05 mm to 66.95 mm.

[0014] The selected trough components—namely, the base plate, both side walls, the front face, the inner front plate, and the cover plate—form a one-piece trough body made of plastic or metal. The outer front plate, which can be attached to this trough body, is made of the same material. The one-piece trough body has distinctly rounded longitudinal edges; this facilitates handling and prevents damage to the surface on which the grinder is placed.

[0015] The plastic should be hard, durable, and serviceable; suitable plastics include polyamides, polycarbonates, polyacrylates, polymethacrylates, and selected materials such as acetal copolymers (e.g., "HOSTAFORM"), rigid PVC, polyester, and sulfone. A melt is typically created from the powdered starting material, from which a one-piece blank is formed using an injection molding or compression process. After fine machining, the finished trough body is obtained. A plastic body can be metallized on its surface or provided with a decorative covering layer.

[0016] A one-piece metal body can, for example, be made of a light metal such as aluminum, magnesium, and their alloys, as well as brass, nickel, or a ferrous metal such as stainless steel or stainless steel, particularly stainless steel. The one-piece metallic trough body can be obtained from a solid metal body by material-removing machining, such as milling or machining, or by a forming manufacturing process. A trough body made of stainless steel is particularly preferred; the surface is inert, durable, and easy to maintain. The combination of high weight and metallic luster conveys a high-quality impression of the grinding tool.

[0017] A handle is firmly attached to the trough body and can have the same cross-section as the trough and be about twice the length. The end plate adjacent to the handle is referred to here as the inner end plate, and the other end plate distant from it is referred to as the outer end plate. The handle is preferably made of wood or metal, particularly stainless steel or plastic; in the case of wood, oak or olive wood, for example, are suitable. The user will place the grinding device, consisting of the handle and trough, on a flat surface, press the handle onto this surface with one hand, hold the knife with the other hand, and insert the knife blade into the V-shaped groove in a disc arrangement and move it back and forth within it.

[0018] Preferably, a frame-shaped, metal guard is inserted between the trough and the handle. The guard may be the same width as the trough and its height exceeds the trough height by 20 mm to 40 mm, preferably by about 25 mm. The guard separates the hand holding the knife from the hand holding the handle, protecting the latter from injury caused by the knife blade.

[0019] A ball bearing is mounted on each of the inner end plate and the outer end plate. A ball bearing made of stainless steel, especially stainless steel, is preferably used. A conventional single-row deep groove ball bearing can be used, which has a row / layer of steel balls between a stationary outer ring and a freely rotating inner ring, held in space by a cage. Such ball bearings are commercially available and are designated by the dimensions of the inner diameter of the inner ring x the outer diameter of the outer ring x the height in millimeters.

[0020] In view of the above-mentioned trough dimensions, the following deep groove ball bearings can preferably be used on the device according to the invention for grinding and / or polishing a cutting tool: 10.00 x 28.00 x 8.00 mm or 12.00 x 28.00 x 7.00 mm or 15.00 x 32.00 x 8.00 mm.

[0021] The outer ring of such deep groove ball bearings is typically made of stainless steel or stainless steel, making it inert and therefore required to be held in a press fit within a ball bearing holder. Consequently, two spaced, integrally formed webs preferably protrude from the inside of each end plate. These webs are bent after the ball bearing is inserted to form angle pieces that hold the ball bearing in a press fit. Alternatively, a circular recess can be cut out on the inside of a comparatively thick end plate, into which the ball bearing is inserted and held in a press fit.

[0022] The two disc assemblies sit on a hollow metal shaft, which, depending on the ball bearing used, can have an outer diameter of 10 mm, 12 mm, or 15 mm, for example. The shaft has two spaced-apart shaft ends, and each shaft end is non-rotatably inserted into the easily rotating inner ring of a ball bearing.

[0023] At a short distance from the inner shaft end, which is inserted into the inner end plate, an inner metal ring is firmly attached or integrally formed on the outer circumference of the hollow shaft. This ring serves as an inner abutment for the other components mounted on the hollow shaft. The inner abutment keeps the first disc assembly at a distance from the adjacent inner ball bearing.

[0024] An inner cover plate made of plastic sits on the hollow shaft between the inner support and the first disc assembly. An outer cover plate made of the same plastic sits on the hollow shaft between the second disc assembly and the outer end plate. A medium-strength, moderately compressible plastic, such as ABS plastic or polyethylene, can be used here, as its compression supports and maintains the mutual interference fit between all components on the hollow shaft after assembly.

[0025] Adjacent to the outer cover plate, an outer metal ring is firmly attached or integrally formed on the outer circumference of the hollow shaft. This ring serves as an outer abutment for the other components mounted on the hollow shaft. Between the inner and outer abutments, the components located between them are press-fitted and held against rotation on the shaft.

[0026] The unit thus obtained, consisting of the shaft and, after the inner abutment, the first cover plate, first plate arrangement, second plate arrangement, second cover plate and outer abutment, which are seated successively on the shaft, forms an independent unit which can be assembled outside the trough, handled and finally inserted into the trough interior.

[0027] An O-ring adapted to the trough cross-section is placed on the inside of the outer end plate, which, after final assembly, seals the outer end plate against the open end of the trough body in a moisture-tight manner.

[0028] For final assembly, the end of the shaft adjacent to the outer abutment is inserted into the inner ring of the outer ball bearing on the inside of the outer end plate and secured there. The unit held on the outer end plate, consisting of the shaft and all components sitting on the shaft, is inserted into the interior of the trough. The inner end of the shaft adjacent to the first cover plate is secured against rotation in the inner ring of the inner ball bearing on the inside of the inner end plate, and the outer end plate is placed against the open end of the trough body. A long threaded screw, preferably an M4 machine screw, is inserted through a hole cut out in the center of the outer end plate, guided through the entire interior of the hollow shaft and finally screwed with its threaded end into a threaded hole formed in the center of the inner end plate.Because the shaft is mounted in two high-quality ball bearings, easy and unhindered rotation of the disc arrangements in the trough interior is guaranteed.

[0029] After this assembly, a first disc arrangement and a second disc arrangement are located in the center of the trough. The first disc arrangement consists of two grinding discs, and the second disc arrangement consists of two polishing discs. All discs have basically the same structure, are circular, have the same diameter of preferably 30 mm to 50 mm, in particular of approximately 40 mm, have a central bore through which the shaft is guided, furthermore have a flat, inert rear side and form on the other opposite side a flat conical surface that rises slightly from the disc edge to the disc center. The conical surface can extend to the bore, or the disc center forms a hollow cylinder with a wall thickness of approximately 2.00 mm to 5.00 mm and a flat end face parallel to the rear side, and the conical surface ends at this disc center.The discs themselves are typically made of metal, preferably stainless steel. In the case of grinding discs, a coating of abrasive material is applied to the flat conical surface. The abrasive material layer forms the grinding surface of the grinding disc. The abrasive material layer contains abrasive grains made of a hard material embedded in a bonding base. A suitable bonding base could be, for example, a nickel layer electroplated onto iron material or a copper-palladium coating. The abrasive grains can be made of synthetic diamond, silicon carbide, or quartz, for example.

[0030] A grinding wheel of this type which is particularly preferred according to the invention has a core made of steel, and on the slightly rising conical surface there is applied a coating of nickel in which abrasive grains of synthetic diamond are dispersed.

[0031] Grinding a knife blade sharpens the cutting edge. Following grinding, the sharpened edge can be polished. Polishing, or honing, serves to further sharpen the edge and remove minor irregularities resulting from the grinding process. Polishing is performed on a polishing surface that should be as smooth as possible.

[0032] The polishing surface is located on a polishing wheel. The two polishing wheels provided according to the invention have basically the same structure as the grinding wheels explained above. The surface of the flat conical surface on the polishing wheel body, which rises slightly from the wheel edge to the wheel center, can directly form the polishing surface. Alternatively, this surface can be machined or modified to serve as a polishing surface; for example, grooves or other depressions can be cut out in the surface layer. A particularly preferred polishing wheel according to the invention has a nearly smooth surface.

[0033] The grinding surfaces on the two grinding wheels and the polishing surfaces on the two polishing wheels are collectively referred to as the active surfaces below. Two identical wheels of this type are arranged on the shaft with their active surfaces facing each other and touching each other with their respective wheel centers. Adjacent to this contact zone, a circumferential V-shaped groove is formed between the two wheels, which widens in the longitudinal direction of the shaft toward the respective wheel edge, and the two flat active surfaces each form a groove flank of this groove. The groove flanks enclose a groove angle of preferably 30° to 50°, in particular a groove angle of approximately 30° to approximately 40°.Because the effective surface extends circumferentially along the entire gently rising conical surface over the majority of the entire disc surface, a knife blade inserted into the V-shaped groove can be moved back and forth not only orthogonally to the longitudinal direction of the shaft, but also within a wide angular range, preferably within an angular range of approximately minus 30° to approximately plus 30°, to a perpendicular to the longitudinal direction of the shaft. Each blade cutting surface constantly and simultaneously rests against an effective surface of each of the two discs, thereby being ground or polished. This allows a high degree of cutting edge sharpness to be quickly achieved with just a few back-and-forth movements of the knife blade on the two grinding wheels.

[0034] Typically, the grinding wheel assembly is arranged adjacent to the inner face plate; the grinding wheel remote from the inner face plate has a flat back surface, and the flat back surface of one polishing wheel of the adjacent polishing wheel assembly can be directly in contact with this flat grinding wheel back surface; alternatively, an annular spacer can be inserted between the grinding wheel assembly and the polishing wheel assembly. EXAMPLE AND DRAWINGS

[0035] The device according to the invention for grinding and / or polishing a cutting tool, in particular a knife for kitchen and household use, is hereinafter referred to as "the grinding device." This grinding device will be explained in more detail below using an exemplary embodiment with reference to the drawings, which show: Fig. 1 shows a schematic oblique view of the grinding device; Fig. 2 partially cut a side view of the grinding device according to Fig. 1; Fig. 3 shows the sectional view in enlarged scale Fig. 2; Fig. 4a and Fig. 4b two grinding wheels arranged at a distance and mirror-inverted to each other; Fig. 4c and Fig. 4d two polishing wheels arranged at a distance and mirror-inverted to each other; Fig. 5 shows an exploded view of the individual components of the grinding device Fig. 1; and Fig. 6 shows an oblique view of the trough interior.

[0036] According to the illustration Fig. 1, the grinding device 2 essentially consists of three components, namely a half-open body 10 shown at the front left, in the opening of which disc arrangements 40 and 60 can be seen, furthermore a frame-shaped bracket 8 shown in the middle and a handle 7 shown at the rear right. Fig. 1 and Fig. 2, the body 10 forms an elongated cuboid with a square cross-section, which is delimited by a base plate 12 with a flat underside 13, by two parallel and spaced-apart side walls 14 and 16, by an outer end face 18 in which a large circular opening 19 is recessed, by an inner end plate 22 and by a cover plate 20. In the center of the cover plate 20, a larger gap 21 is formed, to which an adapted recess 15 in the side wall 14 shown at the front and an adapted recess 17 in the side wall 16 shown at the rear are connected. The gap 21 and the recesses 15 and 17 enable the blade of a knife (not shown) to be inserted into the V-shaped groove 55 or 75 formed in both disc assemblies 40 and 60. The longitudinal edges of the body 10 are clearly rounded.In a practical embodiment of the grinding device 2 according to the invention, described in detail below, the body 10 has a length of approximately 65 mm and a width / height of approximately 45 mm.

[0037] According to an important aspect of the present invention, the base plate 12, the two side walls 14 and 16, the outer end face 18, the cover plate 20, and the inner end plate 22 form a one-piece body 10 made of plastic or metal. The body 10 defines a hollow interior 11, which has an open end, the opening 19 in the outer end face 18. An outer end plate 25 can be applied in a liquid-tight manner to the open end of the body; then, the body 10 and the outer end plate 25 form an elongated, semi-open trough, which defines a hollow interior into which liquid, such as water, oil, or other emulsion, can be poured. After a sufficient amount of liquid has been introduced into the interior of the trough, the disc assemblies 40 and 60 are partially immersed in this liquid. At the point inserted into the groove 55 in the disc assemblies 40 and 60, respectively,A wet treatment can be carried out on the knife blade to be treated, which is inserted into the groove 75 in the disc arrangement 60.

[0038] The outer ball bearing 27, which has a slightly rotating inner ring, is mounted on the inside of the outer end plate 25. The inner ball bearing 24, which has a slightly rotating inner ring, is mounted on the inside of the inner end plate 22. A shaft 30, which has two distal shaft ends 31 and 32, extends through the entire length of the body's interior 11. One outer shaft end 32 is non-rotatably inserted into the inner ring on the outer ball bearing 27; the other inner shaft end 31 is non-rotatably inserted into the inner ring on the inner ball bearing 24; consequently, the shaft 30 is mounted for easy rotation within the body's interior 11. The shaft 30 is designed as a hollow shaft and is made of metal, preferably stainless steel; depending on the ball bearing 24 or 26 used, the shaft 30 can, for example, have an outer diameter of 10 mm, 12 mm, or 15 mm.The longitudinal direction of the shaft 30 defines a virtual shaft longitudinal direction LR.

[0039] As in particular the Fig. As can be seen in Figure 3, a first disc arrangement 40 arranged adjacent to the inner ball bearing 24 is seated on the shaft 30 in a rotationally fixed manner; furthermore, a second disc arrangement 60 arranged adjacent to the outer ball bearing 27 is seated on the shaft 30 in a rotationally fixed manner.

[0040] The wheel assembly 40 consists of two grinding wheels 42 and 42' and forms a grinding wheel assembly. The two grinding wheels 42 and 42' are of the same design, so that only one needs to be described in detail. As is particularly evident from the Fig. 4c, the grinding wheel 42 is circular, has a grinding wheel edge 43, a grinding wheel body 44 with a flat grinding wheel rear face 45, and a bore 46 adapted to the outer diameter of the shaft. After attachment to the shaft 30, the grinding wheel rear face 45 is aligned perpendicular to the shaft longitudinal direction LR. Adjacent to the bore 46, a hollow cylindrical section 47 is formed in the grinding wheel body 44, which can, for example, have a wall thickness of approximately 3 mm to 5 mm; the hollow cylindrical section 47 has a flat end face 48 parallel to the grinding wheel rear face 45. The wheel side opposite the grinding wheel rear face 45 forms, between the wheel edge 43 and the hollow cylindrical section end face 48, a flat conical surface 50 which rises slightly towards the end face 48 and on which an abrasive coating 52 is deposited. The abrasive coating 52 has a primer in which hard material grains are dispersed.Preferably, the grinding wheel body 44 may be made of stainless steel, and a nickel primer is deposited on the conical surface 50, in which grains of synthetic diamond are dispersed.

[0041] For assembly, two grinding wheels 42 and 42' are placed on the shaft 30 with their conical surfaces 50 and 50' facing each other, for which purpose the shaft 30 is guided through the two grinding wheel bores 46 and 46'; the two hollow cylinder section end faces 48 and 48' lie closely against one another and form a contact zone of the two grinding wheels 42 and 42'. The two conical surfaces 50 and 50' form the groove flanks of a circumferential V-shaped groove 55, which widens in the shaft longitudinal direction LR towards the two wheel edges 43 and 43' and which encloses the groove angle NW; in a practically realized embodiment of the grinding device 2, the groove angle NW has a value of approximately 30° to approximately 40°.

[0042] For grinding, the knife blade (not shown here) is inserted into the groove 55 so that the two surfaces of the knife blade edge each rest against a grinding coating 52 or 52'. One hand of the user presses the handle 7 firmly against a flat surface, and the other hand grasps the knife and moves the knife blade back and forth within the groove 55; the blade can be moved back and forth vertically to the shaft longitudinal direction LR; the knife blade edge rests with both cutting surfaces against a grinding coating 52 or 52', so that both cutting surfaces are ground simultaneously.Alternatively, the knife blade inserted into the groove 55 can be aligned within the groove 55 within a wide angular range of approximately minus 30° to approximately plus 30° to the perpendicular to the shaft longitudinal direction LR and, with this alignment, moved back and forth in the groove 55 between the two grinding wheels 42 and 42'; in this case, too, the knife blade edge rests with both cutting surfaces against a grinding coating 52 or 52', so that both cutting surfaces are ground simultaneously; within this angular range, the back and forth movement of the knife blade can be carried out with a constant alignment or with a continuously changing alignment of the knife blade. In any case, the back and forth movement of the knife blade within the groove 55 causes a rotation of the grinding wheel arrangement 40 and thus also a rotation of the shaft 30 and all components mounted thereon in a rotationally fixed manner.

[0043] The disk assembly 60 consists of two polishing disks 62 and 62' and forms a polishing disk assembly. The two polishing disks 62 and 62' are of the same design, so that only one needs to be described in detail. As is particularly evident from the Fig. 4a, the polishing disc 62 is circular, has a polishing disc edge 63, a polishing disc body 64 with a flat polishing disc rear side 65, and a bore 66 adapted to the shaft outer diameter. Adjacent to the bore 66, a hollow cylindrical section 67 is formed in the polishing disc body 64, which can have a wall thickness of approximately 3 mm to 5 mm; the hollow cylindrical section 67 has a flat end face 68 parallel to the rear side 65. The disc side opposite the rear side 65 forms a flat conical surface 70, between the disc edge 63 and the hollow cylindrical section end face 68, which rises slightly towards the end face 68. The polishing disc body 64 can preferably be made of stainless steel, and the naturally occurring conical surface 70 forms the polishing surface without the need for any special post-treatment. The polishing effect is then achieved by fine grooves and scratches in the surface that are formed during use.

[0044] For assembly, two polishing wheels 62 and 62' are placed on the shaft 30 with their polishing surfaces 70 and 70' facing each other, for which purpose the shaft 30 is guided through the two polishing wheel bores 66 and 66'; the two hollow cylinder section end faces 68 and 68' lie closely against one another and form a contact zone of the two polishing wheels 62 and 62'. The two conical surfaces 70 and 70' form the groove flanks of a circumferential V-shaped groove 75, which widens in the shaft longitudinal direction LR towards the two wheel edges 63 and 63' and which encloses the groove angle NW; in a practically realized embodiment of the grinding device 2, the groove angle NW has a value of approximately 30° to approximately 40°.

[0045] Typically, polishing is performed after a prior grinding treatment. For polishing, the knife blade (not shown here) is inserted into the groove 75 so that the two surfaces of the knife blade edge each rest against a polishing pad 72 or 72'. One hand of the user presses the handle 7 firmly against a flat surface, and the other hand grasps the knife and moves the knife blade back and forth within the groove 75; the blade can be moved back and forth perpendicular to the shaft longitudinal direction LR; the knife blade edge rests with both cutting surfaces against a polishing surface 72 or 72', so that both cutting surfaces are polished or honed simultaneously.Alternatively, the knife blade inserted into the groove 75 can be aligned within the groove 75 within a wide angular range of approximately minus 30° to approximately plus 30° to the perpendicular to the shaft longitudinal direction LR and, with this alignment, moved back and forth in the groove 75 between the two polishing wheels 62 and 62'; in this case, too, the knife blade edge rests with both cutting surfaces on a polishing surface 72 or 72', so that both cutting surfaces are polished or dressed simultaneously; within this angular range, the back and forth movement of the knife blade can be carried out with a constant alignment or with a continuously changing alignment of the knife blade. In any case, the back and forth movement of the knife blade within the groove 75 causes a rotation of the polishing wheel arrangement 60 and thus also a rotation of the shaft 30 and all components mounted thereon in a rotationally fixed manner.

[0046] As from Fig. 3, the outer rear side 45 of the grinding wheel 42 of the grinding wheel arrangement 40 can lie directly against the inner rear side 65' of the polishing wheel 62' of the polishing wheel arrangement 60, or a spacer (not shown) can be inserted between these two rear sides 45 and 65'.

[0047] According to the Fig. 5 The following components are mounted on the shaft 30 - viewed from the outside inwards - an outer abutment 38, an outer cover plate 37, a polishing wheel assembly 60 with the two polishing wheels 62 and 62', a grinding wheel assembly 40 with the two grinding wheels 42 and 42', an inner cover plate 36 and an inner abutment 33. These components are arranged one after the other on the shaft 30 outside the body 10. The two abutments 38 and 33 are non-rotatably attached to the shaft 30 and hold the components arranged therebetween in a mutual press fit with one another; all components are non-rotatably connected to the shaft 30. An outer end plate 25 is provided, in the center of which a bore 26 is recessed. An outer ball bearing 27 is placed on the inside of the outer end plate 25 and fixedly fastened.An O-ring 39 is placed around the inner side of the outer ball bearing 27 to act as a seal. The outer shaft end 32 of the shaft 30 is inserted into the inner ring of the outer ball bearing 27 and is rotationally fixed therein; the components specified above are rotationally fixed on the shaft 30. The shaft 30, with the components seated thereon, is inserted through the large opening 19 in the end face 18 of the body 10 into the body interior 11, and the inner shaft end 31 is inserted into the inner ring of the inner ball bearing 24 and is rotationally fixed therein. The inner side of the outer end plate 25, with the O-ring 39 in contact therewith, is placed against the flat outer surface of the end wall 18 of the body 10.A long machine screw 28 having a threaded screw end 29 is inserted through the bore 26 in the outer end plate 25; this machine screw 28 is guided through the entire interior of the shaft 30, which is designed as a hollow shaft, and is screwed with the threaded screw end 29 into a threaded bore (not shown) which is recessed in the center of the inner end plate 22.

[0048] According to the Fig. 6, outside the inner ball bearing 24, in the corner areas of the inner front plate 22, holes are cut out through which wood screws 23 are passed, which are screwed through non-recognizable holes in the protective bracket 8 into the handle 7, which is preferably made of wood, and connect this firmly and permanently to the body 10. List of reference symbols: 2 grinder 7 Handle 8 protective bars 10 one-piece semi-open body 11 Body interior 12 Base plate 13 whose underside 14 a side wall 15 whose recess 16 other side wall 17 whose recess 18 Frontal surface of the body 10 19 large opening in the front face 18 20 cover plate 21 whose gap 22 inner front plate 23 holes in the inner face plate 24 inner ball bearing 25 outer front plate 26 Hole in the outer face plate 27 outer ball bearing 28 machine screw 29 whose threaded screw end 30 wave 31 of which one, inner shaft end 32 whose other, outer shaft end 33 inner abutment 36 inner cover plate 37 outer cover plate 38 outer abutment 39 O-ring 40 grinding wheel arrangement 42 and 42' grinding wheel 43 Grinding wheel edge 44 grinding wheel bodies 45 Grinding wheel back 46 Hole 47 Hollow cylinder section 48 whose frontal surface 50 flat conical surface 55 V-shaped groove of the grinding wheel arrangement NW groove angle of the grinding wheel arrangement 60 polishing disc arrangement 62 and 62' polishing disc 63 Polishing wheel edge 64 polishing wheel bodies 65 Polishing disc back 66 bore 67 Hollow cylinder section 68 whose frontal area 70 flat conical surface 75 V-shaped groove of the polishing wheel arrangement NW groove angle of the polishing wheel arrangement QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 2013 / 0295823 A1

[0002] EP 3278928 A2

[0004]

Claims

[1] A device for manually grinding and / or polishing the blade of a cutting tool, in particular a kitchen or household knife, comprising a body (10) on or in which a shaft (30) is rotatably mounted, to which a virtual shaft longitudinal direction (LR) is assigned; on this shaft (30) a grinding wheel arrangement (40) and a polishing wheel arrangement (60) are non-rotatably mounted, each consisting of two circular, identical discs, which each touch each other in the center of a disc side facing each other and which each have a flat conical surface on this disc side that rises slightly from the disc edge to the disc center, so that pairs of conical surfaces form the groove flanks of a circumferential V-shaped groove (55 or 75) that widens towards the disc circumference; and each conical surface is designed either as an effective surface for grinding or as an effective surface for polishing; and for grinding or polishing, the blade is inserted into this V-shaped groove (55 or 75) and is moved back and forth within the groove (55 or 75) by the user's hand holding the knife, which sets the shaft (30) in rotation and grinds or polishes or removes the cutting surface lying against the respective rotating active surface; characterized by , that the body (10) is an elongated, semi-open trough enclosing a trough interior, which consists of the following trough components: a base plate (12), two spaced-apart side walls (14 and 16), an end wall (18), an end plate (22) and a cover plate (20) having a central gap (21); and in each of the two side walls (14 and 16) a recess (15 or 17) is formed which adjoins the contour of the gap (21) in order to be able to insert the blade to be treated through the gap (21) and the recesses (15 and 17) into the V-shaped groove (55 or 75) in one or the other disc arrangement (40 or 60) located in the interior of the trough; and the above-mentioned trough components, namely the base plate (12), the two side walls (14 and 16), the end wall (18), the cover plate (20) and an inner end plate (22) form a one-piece body (10) made of plastic or metal, and an outer end plate (25) made of the same material can be fastened to this one-piece body (10) by means of a screw (28); and an inner ball bearing (24) is fixedly mounted on the inside of the inner end plate (22) and an outer ball bearing (27) is fixedly mounted on the inside of the outer end plate (25), each ball bearing (24 or 27) being provided with a slightly rotatable inner ring; and the shaft (30) has two spaced-apart shaft ends (31 and 32), each of which is non-rotatably inserted into an inner ring of the ball bearings (24 and 27, respectively), so that the grinding wheel arrangement (40) and polishing wheel arrangement (60) attached to the shaft (30) are each accommodated in the trough interior in a slightly rotatable manner; and the screw (28) is a threaded screw and has a threaded screw end (29); and the shaft (30) is a hollow shaft, and the screw (28) is guided through the interior of this hollow shaft and is inserted with the threaded screw end (29) into a threaded bore recessed in the inner end plate (22) and fixed therein. [2] Device according to claim 1, characterized by that “a flat conical surface which rises slightly from the edge of the disc to the centre of the disc” is a flat conical surface (50, 50', 70 or 70') whose alignment with the plane of the rear side of the disc (45, 45', 65 or 65') encloses half a groove angle, in particular an angle of approximately 15° to approximately 20°. [3] Device according to claim 1, characterized by that the device has a moisture-tight and largely closed trough interior into which water or another liquid suitable for wet treatment can be filled in order to carry out the grinding process of the knife blade as a wet grinding process and the polishing treatment of the knife blade as a wet polishing treatment. [4] Device according to claim 1, characterized bythat the one-piece body (10) is a cuboid body with a square cross-section, which has a length of about 50 mm to about 80 mm and a width / height of about 35 mm to about 55 mm. [5] Device according to claim 1 or 4, characterized by that the body (10) is made of stainless steel. [6] Device according to claim 4, characterized by that a handle (7) is attached to the inner end plate (22) of the body (10), which handle has the square cross-section of the body (10) and approximately twice the length of the body (10). [7] Device according to claim 6, characterized by that the handle (7) is made of wood, for example oak or olive. [8] Device according to claim 6 or 7, characterized bythat a frame-shaped protective bracket (8) made of metal is inserted between the inner front plate (22) and the handle (7), which has the width of the body (10) and whose height exceeds the height of the body (10) by about 20 mm to about 40 mm. [9] Device according to claim 1, characterized by , that the shaft (30) is made of stainless steel or stainless steel; and an annular outer abutment (38) is firmly attached or integrally formed on this shaft (30); Furthermore, at a distance from this outer abutment (38) on this shaft (30) an annular inner abutment (33) is firmly attached or integrally formed; and - viewed from the outside inwards - on this shaft (30) between the outer and inner abutments (38 or 33) there are an outer cover plate (37), the polishing wheel arrangement (60), the grinding wheel arrangement (40) and an inner cover plate (36), which are alternately held in a press fit between the outer and inner abutments (38 or 33) and are connected to the shaft (30) in a rotationally fixed manner. [10] Device according to claim 1 or 9, characterized by , that the grinding wheel arrangement (40) consists of two grinding wheels (42 and 42') in central contact; the polishing disc arrangement (60) consists of two centrally touching polishing discs (62 and 62'); all discs (42, 42', 62, and 62') are circular and have an equal diameter of about 30 mm to about 50 mm and have a central bore (46 or 66) through which the shaft (30) is passed. [11] Device according to claim 1 or 10, characterized by that between the two grinding wheels (42 and 42') touching each other centrally in a contact zone, between the contact zone and the wheel edge (43 or 43') there is formed a circumferential V-shaped groove (55) which is open towards the wheel edge (43 or 43') and extends in the longitudinal direction (LR) of the shaft, the groove flanks of which enclose a groove angle (NW) of approximately 30° to approximately 50°, in particular enclose such a groove angle (NW) of approximately 30° to approximately 40°. [12] Device according to claim 11, characterized bythat a knife blade inserted into the V-shaped groove (55) can not only be moved back and forth orthogonally to the longitudinal direction (LR) of the shaft, but can also be moved back and forth in the groove (55) over a wide angular range, preferably over an angular range of approximately minus 30° to approximately plus 30° to a perpendicular to the longitudinal direction (LR), each blade cutting surface constantly and simultaneously resting on a conical grinding surface (50 or 50') of the two grinding wheels (42 and 42') and being ground in the process. [13] Device according to claim 1 or 9, characterized bythat between the two polishing wheels (62 and 62') touching each other centrally in a contact zone, between the contact zone and the wheel edge (63 or 63'), there is formed a circumferential V-shaped groove (75) which is open towards the wheel edge (63 or 63') and extends in the longitudinal direction (LR) of the shaft, the groove flanks of which enclose a groove angle (NW) of approximately 30° to approximately 50°, in particular enclose such a groove angle (NW) of approximately 30° to approximately 40°. [14] Device according to claim 13, characterized bythat a knife blade inserted into the V-shaped groove (75) can not only be moved back and forth orthogonally to the longitudinal direction (LR) of the shaft, but can also be moved back and forth in the groove (75) over a wide angular range, preferably over an angular range of approximately minus 30° to approximately plus 30° to a perpendicular to the longitudinal direction (LR), each blade cutting surface constantly and simultaneously resting on a conical polishing surface (70 or 70') of the two polishing wheels (62 and 62') and being polished in the process.

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