Knife grinder

Abstract

A knife grinder (1), comprising at least two rotatably mounted grinding discs (2, 3), each grinding disc (2, 3) having a grinding face (4, 5), wherein a grinding notch (6) through which a knife blade (7) can be drawn is formed between the grinding faces (4, 5).

Description

[0001] knife sharpener

[0002] The invention relates to a knife sharpening device for sharpening knife blades. A compact knife sharpening device is proposed which, with simple application, can produce a high-quality, consistent grinding pattern on the knife.

[0003] There are many ways to sharpen a knife. One well-known method is using whetstones. However, achieving a good sharpening pattern on a knife using this method requires a high degree of expertise and practice. In particular, maintaining a consistent angle of the knife is necessary, which can be difficult for inexperienced users.

[0004] Various options for a more user-friendly application have already been proposed in the prior art. For example, DE29913583U1 proposes a device for sharpening cutting tools in which a knife can be drawn through a pair of sharpening devices in two directions. Such a sharpening device can be designed to be small enough to be stored in a drawer, for example. However, even here, holding the device with one hand requires a strong, steady hand to achieve a very good sharpening result with minimal effort.

[0005] Furthermore, DE102017011680A1 proposes a knife sharpening device in which a knife can be drawn through a V-shaped, movable sharpening slot formed by two intersecting grinding bars held in grinding wheel holders. Such a device already produces a very good sharpening finish. However, the device requires a considerable amount of space. In particular, its size makes storage in a drawer difficult. Based on this, the object of the invention is to at least partially solve the problems described with reference to the prior art. Specifically, it aims to provide a knife sharpening device that produces a very good sharpening finish, has a compact design, and can be stored in a drawer.

[0006] This problem is solved by the features of the independent claims. Further advantageous embodiments of the invention are specified in the dependent claims. It should be noted that features listed individually in the claims can be combined with one another in any technologically meaningful way and define further embodiments of the invention. Furthermore, the features specified in the claims are further specified and explained in the description, which also presents further preferred embodiments of the invention.

[0007] A knife sharpening device, comprising at least two rotatably mounted grinding wheels, helps to solve this task. Each grinding wheel has a grinding face, and between these faces is a grinding groove for drawing a knife blade through.

[0008] The knife sharpening device is specifically designed and configured for grinding and sharpening knife blades, particularly kitchen knife blades. Obviously, knives can have different sizes, blade shapes, etc., so the knife sharpening device is specifically configured to grind and sharpen several sizes and / or types of knives. Naturally, this also allows it to be used not only for knives but also for other similar objects (such as scissor blades, etc.). The knife sharpening device is, in particular, a product that houses, (partially) encloses, and provides for the operation of the other components mentioned. The knife sharpening device comprises two rotatably mounted grinding wheels, preferably with exactly two grinding wheels.

[0009] The knife sharpening device includes, in particular, means that allow the grinding wheels to be mounted so that they can rotate about a (central) axis. In particular, (ball or roller) bearings may be provided that allow the grinding wheels to rotate upon external excitation. Specifically, the grinding wheels are mounted such that they can rotate (possibly independently of one another), for example, by means of contact with the knife being sharpened. The grinding wheels are preferably accessible from the outside or can be brought into contact with the knife only from one side.

[0010] A grinding wheel can be a particularly rounded element with a diameter that is, for example, approximately twenty times its thickness. Thus, the grinding wheel can have two end faces (surfaces parallel to the diameter) and a circumferential surface (surface parallel to the circumference).

[0011] Preferably, a grinding wheel has a central hole through which a rotating element, in particular a shaft, can be inserted, on which the grinding wheel is rotatably mounted.

[0012] In particular, it is possible to screw the grinding wheel onto one end of the shaft.

[0013] It is possible (particularly as an alternative) for the connection or screw fastening of the grinding wheel to the shaft to incorporate a spring. This allows the grinding wheel to be axially movable and spring-loaded on the shaft. The spring travel, or degree of freedom of the axial spring travel, can be less than 1.0 mm. Such a spring-loaded mounting of the grinding wheel can help to reduce or compensate for vibrations or jerky movements that may occur when drawing the knife blade through it. The grinding wheel can be made of a single material, for example, Al₂O₃. It is also possible for the grinding wheel to comprise a backing plate, for example, made of metal, and a grinding coating, for example, with diamond abrasives.

[0014] The end face of the grinding wheel preferably extends across the entire diameter of the grinding wheel. The end face may be limited by a transition from the circumferential surface to the diameter. The end face is preferably flat, at least where a grinding engagement with the blade of the knife is intended.

[0015] Contours may be provided (possibly locally limited) on the end face of the grinding wheel, i.e., projecting towards the opposite diameter surface and / or projecting away from the opposite diameter surface. The grinding face may, in particular, have at least one surface recess or chamfer. Preferably, both possible surface recesses and chamfers are continuous, i.e., designed to be circumferential.

[0016] The grinding wheel can be designed so that only one of the two diameter surfaces is a grinding side, i.e., intended for use with the knife.

[0017] It is possible for the grinding wheels to have different (outer) diameters. In particular, the grinding wheel located lower down may have a smaller diameter. Different diameters can help to adjust the grinding area between the grinding wheels, especially to reduce it and thus potentially achieve smaller grinding angles and / or facilitate a smoother pull-through motion. A grinding groove for drawing a knife blade is formed between the end faces of the two grinding wheels. In other words, an approximately V-shaped, three-dimensional gap is formed with the opposing grinding faces, which is longer than the thickness of the grinding wheels. The grinding groove can be a space that widens upwards, into which a knife with a blade can be inserted.Preferably, the knife blade can be drawn through the grinding notch in such a way that the grinding surfaces of both opposing grinding wheels are brought into contact with the knife blade. In other words, drawing a knife blade through can be described as follows: the knife is held by a person and inserted into the grinding notch perpendicular to the base of the knife sharpening device until it touches both grinding surfaces of the grinding wheels in the area of ​​the lower blade. The knife can then be pulled forward or backward. During this movement, the knife blade slides or grinds along the adjacent grinding surfaces of the grinding wheels.

[0018] The pulling motion, combined with contact with the grinding wheels, creates a (rotational) torque that is transferred to the grinding wheels. This causes the grinding wheels to rotate simultaneously due to the pulling motion of the knife blade. Specifically, this generates opposing rotational movements of the grinding wheels, meaning one grinding wheel rotates clockwise and the other counterclockwise.

[0019] The rotary motion allows the abrasive surfaces to glide along the knife blade. This creates a grinding effect that sharpens the blade. Preferably, the grinding effect can be further improved by continuously moving the blade back and forth. This ensures that each side of the blade is worked by the abrasive surfaces, which move in different directions depending on whether the blade is advanced or retracted. This produces a favorable grinding pattern. In particular, a cross-grind can be created in this way, where two grinding directions intersect.

[0020] In particular, the grinding wheels are arranged such that the grinding notch formed between the end faces of the grinding wheels has a notch angle corresponding to a desired grinding angle. Preferably, knives are ground so that one side of the blade has a constant, uniform angle.

[0021] The grinding surfaces can be positioned at an angle to each other. Consequently, the grinding surfaces are not parallel to each other. The angle of the grinding wheels or grinding surfaces determines the notch angle. The notch angle can be fixed or flexibly adjustable. The notch angle is preferably set to less than 45° [degrees]. A notch angle between 15° and 38° is preferred. A notch angle between 28° and 33° is particularly preferred. Preferably, the end grinding wheels are arranged so that the knife can be drawn through the grinding notch on a knife-pass plane (centrally). The knife-pass plane can be a plane that runs transversely to the base plane of the knife sharpening device through the grinding notch.Preferably, the knife can be pulled through the knife sharpening device when it is held perpendicular to the base plane of the knife sharpening device, so that the end-face grinding surfaces meet the knife at the grinding angle.

[0022] At least one of the grinding wheels can have a surface recess on its grinding side, into which the other grinding wheel partially extends. Preferably, a grinding notch can be set in this way, into which the knife blade can be inserted completely or laterally flush. The surface recess allows the grinding sides of the grinding wheels to form a (closed) point of the grinding notch without the grinding wheels touching (e.g., in the area of ​​the lower point of the grinding notch and / or directly). This allows a point of the grinding notch into which the knife blade can protrude. With the surface recess, one grinding wheel can "project" into the other, particularly when considering a cross-section through the grinding wheels that includes their axes of rotation.For example, an edge section of one grinding wheel can plunge into the surface recess of the grinding wheel's other grinding wheel, extending towards its circumference. The resulting plunge depth can be small compared to the grinding wheel's thickness, for example, greater than 0.5 mm and less than 2.0 mm.

[0023] This allows for the smallest possible distance between the grinding surfaces at the tip of the grinding wheel. In particular, it makes it possible to approximate or create a linear point in the grinding notch. This allows the knife blade to be drawn through the grinding notch along its tip, ensuring the entire blade is sharpened.

[0024] The surface recess can be a (single) annular groove or a (central) circular groove. In particular, the surface recess can be designed such that a groove extends into the grinding wheel from the grinding side.

[0025] Preferably, such a configuration creates two (first) grinding areas, positioned one behind the other or spaced apart from each other in the direction of the knife's passage, between a (first) grinding wheel and the knife in the grinding notch, while on the opposite knife blade, a (second), preferably single or continuous, grinding area is formed, extending into the space between the (first) grinding areas when viewed in the direction of the knife's passage. It is possible that the central second grinding area, on the one hand, and the two off-center grinding areas, on the other hand, form opposing grinding, support, and / or guide sections for the knife. Thus, when the knife blade passes through the knife sharpening device, it can pass through a front and a rear (first) grinding area.In particular, it is possible that the knife blade experiences an opposing grinding direction (upwards or downwards) through the (first) grinding wheel in both the front and rear (first) grinding areas.

[0026] The axes of rotation of the grinding wheels can intersect the knife-pass plane at different heights. The grinding wheels can be arranged at different heights. In particular, it is possible that the grinding wheel with the surface recess is the lower grinding wheel, and the other grinding wheel, which engages or plunges into the surface recess, is the upper one.

[0027] The axes of rotation of the grinding wheels can be inclined upwards towards the central area of ​​the grinding wedge. The grinding wheels can be oriented at an angle to each other and to the plane of knife passage. In particular, the axes of rotation can be arranged transversely or perpendicular to the grinding faces. The axes of rotation and the grinding wheels can both form the same angle to each other. The plane of knife passage preferably bisects the angle of the grinding notch or notch angle, or the angle between the grinding wheels.

[0028] The grinding wheels can be mounted on a shaft, each freely rotatable and supported by at least one bearing. Preferably, each shaft is supported by two bearings. The grinding wheels can be attached to the end of the shaft closest to the knife-cutting plane. It is possible for the grinding wheels to be interchangeably mounted on the shaft end. Preferably, the grinding wheels are screwed onto the shaft end. The shaft end preferably projects towards the grinding notch, so that the notch angle of the grinding wheels in the grinding notch can be adjusted by aligning the shaft. The shaft can be supported by at least one bearing in a mounting block of the knife grinding machine. In particular, the at least one bearing can ensure smooth running of the grinding wheels.In particular, the grinding wheels can only be rotated (along with) a passing knife blade and are preferably not motor-driven.

[0029] The holding block of the knife sharpening device can be made in two parts, and the rotatably mounted grinding wheels can be held between two holding block elements. Preferably, the holding block can be disassembled in the middle or in half, so that the bearings with the shafts and grinding wheels are accessible. Preferably, the holding elements are plates or shells, each with half bearing slots, in which the bearings and shafts can be inserted or received in half. By assembling the holding block, the two holding block elements are pressed together, thus clamping or enclosing the bearings and shafts. Preferably, the holding block elements are designed to clamp the bearings with a predetermined tension.In particular, the retaining block elements can have grooves, with opposing grooves forming bearing slots in which the bearings can be placed so that the bearings cannot slip along the axis of rotation.

[0030] The retaining block is preferably separable and is held together, for example, by detachable fasteners such as bolts, screws, nuts, etc. It is also possible that the retaining block is clipped or otherwise held together in a detachable manner.

[0031] It is possible that the holding block has an alignment aid between which the knife blade can be inserted and aligned relative to, or concentrically with, the grinding wedge. The alignment aid can guide sides of the knife blade, making it easier to keep the blade straight. The invention and the technical context are explained in more detail below with reference to five figures. The illustrations are schematic and not intended to demonstrate scale relationships. The explanations given with reference to individual details of the figure can be extracted and freely combined with facts from the preceding description, unless a person skilled in the art necessarily derives otherwise, or such a combination is explicitly excluded. The figure schematically shows:

[0032] Fig. 1: Knife sharpening device in a top view,

[0033] Fig. 2: Knife sharpening device with open holding block,

[0034] Fig. 3: Detailed view of the grinding wheels with surface relief,

[0035] Fig. 4: Front view of the grinding wheels with knife blade, and

[0036] Fig. 5: Side view of the grinding wheels with knife blade.

[0037] Fig. 1 shows a knife sharpening device 1 in a top view. The top view shows how a knife blade 7 is drawn through the knife sharpening device 1. As the knife blade 7 is drawn through, it is guided by an alignment aid 15 in a grinding notch 6. The grinding notch 6 is defined by grinding wheels 2, 3. Finally, a holding block 13 is visible, in which the grinding wheels 2, 3 are held. The holding block 13 rests on a base 25 on a support surface 29. The holding block 13 is bounded at the top by an upper section 26. The upper section 26 is located on the holding block 13 opposite the base 25. The grinding notch 6 has a notch angle 19. The notch angle 19 is adjustable and can be selected so that a desired grinding angle can be ground onto the knife blade 7. A knife-passage plane 10 runs in an angle bisector of the notch angle 19.In the knife pass plane 10, the knife blade 7 is drawn through the knife grinding device 1. The grinding wheels 2, 3 are each rotatable on pivot axes 9. The pivot axes 9 are angled and intersect the grinding wheels 2, 3 at different heights relative to the floor 25 and the support plane 29, respectively. Likewise, the pivot axes 9 intersect the knife pass plane 10 at different heights. In particular, the pivot axis 9 of the first grinding wheel 2 intersects the knife pass plane 10 at a first height 31, which is higher than a second height 32, at which the pivot axis 9 of the second grinding wheel 3 intersects the knife pass plane 10. The retaining block 13 is divisible and is held together by connecting elements 21, in particular bolts and nuts. It is also possible that the retaining block 13 is clipped or otherwise held together.The retaining block 13 has a housing 22 with a first retaining block element 14 and a second retaining block element 20. The first retaining block element 14 can be seen in Fig. 1. The second retaining block element 20 is hidden (see Fig. 2).

[0038] Fig. 2 shows the knife grinding machine 1 with an open retaining block 13. The second retaining block element 20 is visible, in which the grinding wheels 2, 3 with bearings 12 are held by the first retaining block element 14 (see Fig. 1), which is not visible here. The bearings 12 are each supported in a first bearing shaft 23 and in a second bearing shaft 24. The grinding wheels 2, 3 are connected to the bearings 12 by shafts 11. The grinding wheels 2, 3 are fastened to the shafts 11 by (not shown) screws. The knife guide plane 10 is also visible, in which the knife blade 7 is drawn through the knife grinding machine 1. In addition, a guide path 30 is shown, which lies in the knife guide plane 10 and along which the knife blade 7 is drawn through the knife grinding machine 1. However, it is also possible that the knife blade 7 is pulled in the opposite direction to the direction of travel 30 in the knife travel plane 10.

[0039] Fig. 3 shows a detailed view of the grinding wheels 2, 3 with a surface recess 8. It can be seen how the first grinding wheel 2 engages with the second grinding wheel 3 at the surface recess 8. It is also evident how the grinding wheels 2, 3 are positioned obliquely opposite each other on their axes of rotation 9. In the enlarged detail view, it can be seen how an edge between a first grinding face 4 and a first circumferential face 16 of the first grinding wheel 2 projects through a second grinding face 5 of the second grinding wheel 3 into the surface recess 8 (penetration depth 33). A second circumferential face 17 of the second grinding wheel 3 is also visible.

[0040] Fig. 4 shows a front view of the grinding wheels 2, 3 with a knife blade 7, illustrating how the grinding wheels 2, 3 are positioned obliquely opposite each other on the axes of rotation 9, and how a knife blade 7 can be drawn between its grinding surfaces 4, 5. The first grinding wheel 2 has a first diameter 34 and the second grinding wheel 3 a second diameter 35, whereby the diameters can be the same or different. It can also be seen that the surface relief 8 is circumferential. Furthermore, it can be seen that the grinding wheels 2, 3 are positioned at a disc angle 28 relative to each other. The disc angle 28 is defined by the axes of rotation 9. The disc angle 28 has the same angle as the notch angle 19.

[0041] Fig. 5 shows a side view of the grinding wheels 2, 3 with knife blade 7, illustrating how the grinding wheels 2, 3 create two grinding areas 18 through which the knife blade 7 can be drawn. It can also be seen that the axes of rotation 9 of the grinding wheels 2, 3 lie in the same plane. The circumferential surface relief 8 is also visible from another perspective.

[0042] It can be seen that the surface recess 8 influences or limits the grinding area 18 between the first grinding side 4 and the second grinding side 5. The second grinding side 5 is designed (especially with regard to the dimensions of the second diameter 35 and / or the surface recess 8) such that the grinding areas 18 are predefined and the grinding wheels 2, 3 glide past each other as closely as possible.

[0043] It can also be seen that the knife blade 7, in the direction of travel 30, generates a (rotational) torque on the grinding wheels 2, 3, causing them to rotate in opposite directions 27 on the axis of rotation 9. In Fig. 5, with a direction of travel 30 to the right, the direction of rotation of the upper, first grinding wheel 2 is counterclockwise and the direction of rotation of the lower, second grinding wheel 3 is clockwise.

[0044] Reference sign

[0045] 1 knife sharpening machine

[0046] 2 first grinding wheel

[0047] 3 second grinding wheel

[0048] 4 first grinding side

[0049] 5 second grinding side

[0050] 6 grinding notch

[0051] 7 knife blade

[0052] 8 Surface receding

[0053] 9 axis of rotation

[0054] 10 knife pass level

[0055] 11th wave

[0056] 12 warehouses

[0057] 13 Holding block

[0058] 14 first retaining block element

[0059] 15 Alignment aid

[0060] 16 first perimeter page

[0061] 17 second perimeter page

[0062] 18 grinding area

[0063] 19 Notch angle

[0064] 20 second retaining block element

[0065] 21 Connecting element

[0066] 22 cases

[0067] 23 first storage shaft

[0068] 24 second storage shaft

[0069] 25 floor

[0070] 26 Upper area

[0071] 27 Direction of rotation

[0072] 28 disc angles

[0073] 29. Level of insurrection

[0074] 30 Direction of passage 31 First height

[0075] 32 second height

[0076] 33 Immersion depth

[0077] 34 first diameter 35 second diameter

Claims

Claims 1. Knife grinding device (1) comprising at least two rotatably mounted grinding wheels (2, 3), wherein each grinding wheel (2, 3) has an end grinding surface (4, 5) and a grinding notch (6) for drawing a knife blade (7) through is formed between the end grinding surfaces (4, 5).

2. Knife grinding device (1) according to claim 1, wherein the grinding sides (4, 5) are diagonally opposite each other.

3. Knife grinding device (1) according to one of the preceding claims, wherein the grinding wheels (2, 3) have different diameters (34, 35).

4. Knife grinding device (1) according to one of the preceding claims, wherein at least one of the grinding wheels (2) has a surface recess (8) in its grinding side (4) into which the other grinding wheel (3) partially extends.

5. Knife grinding device (1) according to claim 4, wherein the surface recess (8) is an annular groove or circular groove.

6. Knife grinding device (1) according to one of the preceding claims, wherein the axes of rotation (9) of the grinding wheels (2, 3) meet a knife passage plane (10) at different height levels.

7. Knife grinding device (1) according to one of the preceding claims, wherein the grinding wheels (2, 3) are mounted on a shaft (11) so as to be freely rotatable and supported by at least one bearing (12).

8. Knife grinding device (1) according to one of the preceding claims, wherein a holding block (13) of the knife grinding device (1) is designed in two parts and the rotatably mounted grinding wheels are held between two retaining elements (14) of the holding block (13).

Images