Cylindrical grinder having a grinding-disc quick-action closure system

Abstract

The present invention relates to a device (1) for grinding and / or polishing a cutting tool, preferably a household knife, comprising: a grip body (2), at least one spindle (3), which can be rotated relative to the grip body (2), and at least one grinding or polishing disc (4), which is connected to the spindle (3) in such a way that, when the grip body (2) is pulled along a surface, preferably the surface of a table, the grinding or polishing disc (4) rotates relative to the grip body (2). In order to make the changing of a grinding or polishing disc even more user-friendly, in particular easier and quicker, it is provided according to the invention that the spindle (3) and the disc (4, 5) are detachably connected by a rotary cam connection (3b, 4d).

Description

[0001] Roller grinder with grinding wheel quick-release system

[0002] The present invention relates to a device for grinding and / or polishing a cutting tool, preferably a household knife, comprising: a handle body, at least one axis rotatable relative to the handle body and at least one grinding or polishing disk connected to the axis in such a way that when the handle body is pulled, preferably manually, along a surface such as a table surface, the disk rotates relative to the handle body, in particular for grinding and / or polishing a cutting tool applied thereto.

[0003] A grinding and polishing device of this type, also known as a roller grinder, is known from EP 3 278 928 A1 or DE 10 2020 123 501 B3. Grinding and polishing devices of this type are now enjoying great popularity due to their outstanding grinding and polishing results and ease of operation.

[0004] For different applications, such as grinding or polishing cutting tools made of steels of varying hardness, or when they become worn, the grinding and polishing wheels on some conventional models can be changed. In a conventional grinding and polishing fixture, the grinding and polishing wheels are screwed to a rotating spindle mounted in the fixture body. When installing, the user must screw the grinding and polishing wheels deep into the spindle according to the length of the integral threaded stud, and unscrew them again the corresponding amount when removing them.

[0005] The present invention is based on the object of making the changing of a grinding or polishing wheel even more user-friendly, in particular simpler and faster.

[0006] To achieve this object, the invention provides the device according to claim 1. A device for grinding and / or polishing a cutting tool, preferably a household knife, is disclosed, comprising: a handle body, at least one axis rotatable relative to the handle body, and at least one grinding or polishing disk connected to the axis in such a way that when the handle body is pulled, preferably manually, along a surface such as a table surface, the disk rotates relative to the handle body, in particular for grinding and / or polishing a cutting tool applied thereto, wherein the axis and the disk are detachably connected via a cam-shaft connection. A cam-shaft connection is distinguished from a screw connection, among other things, by the fact that the connection can be established and released much more quickly. The cam-shaft connection makes it possible to replace the disk, e.g.This significantly simplifies and accelerates the removal of discs due to wear or to achieve a different effect during grinding or polishing of the cutting tool. The increased operating comfort enhances the user's experience when grinding or polishing the cutting tool. The cam-type rotary joint allows for even faster and safer disc changing and prevents the discs from accidentally coming loose from the spindle.

[0007] It may be advantageous if the cam-shaft connection can be reversibly transferred in less than one rotation (of the disk relative to the axis around a rotational axis of the cam-shaft connection) between a release position, in which the disk and the axis are detached from each other, and a connection position, in which the disk and the axis are connected in a force-locking and / or form-locking manner for grinding and / or polishing the cutting tool, preferably in a maximum of half a rotation, preferably in a maximum of a quarter of a rotation. These features allow the disk to be attached to and detached from the axis particularly easily.

[0008] It may be advantageous for the disc to move toward the handle body when transferring the cam-swivel joint from the release position to the connection position, and / or to move away from the handle body when transferring the cam-swivel joint from the connection position to the release position. Preferably, the disc rests against the shaft in the connection position toward the handle body. This creates a compact unit in the connection position, with the disc and shaft directly adjacent to one another. This also enables particularly precise grinding or polishing of the cutting tool because the rotational movement of the shaft is transferred directly to the disc.

[0009] It can be useful if the cam-shaped rotary connection is designed to be self-locking, so that the disc clamps itself to the axle in the connected position, wherein the clamping force in the connected position can preferably be increased further by increasing rotation of the cam-shaped rotary connection, wherein it is particularly preferred that the cam-shaped rotary connection can only be released with external, preferably manual, force. This design enables the disc to be fixed in a defined manner to the axle in order to withstand even high forces acting on the disc during grinding or polishing of the cutting tool. During grinding or polishing of the cutting tool, the device is rolled back and forth as intended in contact with the cutting edge of a blade of the cutting tool to be machined until the desired result is achieved. In the process, forces act on the disc in various directions, which can, among other things, lead to loosening or tightening.This could lead to the disc coming loose. The self-locking function of the cam-type rotary joint prevents the disc from coming loose accidentally.

[0010] It may be useful to align one rotation axis of the cam slewing ring coaxially with the axis. This allows for a compact design of the device.

[0011] It may prove advantageous if the axle and the disk have complementary, preferably male and female, connecting sections to form the cam-shaft connection, with the axle preferably having a male connecting section and the disk a female connecting section, or vice versa, with the connecting sections preferably being concealed or invisible in the connected position of the cam-shaft connection. This design improves user-friendliness because, in the operating state or the connected position of the disk and axle, no connecting sections are exposed that could interfere with the grinding or polishing of the cutting tool.

[0012] It can be practical if each connecting section has a plurality of cams, which are preferably identically designed and preferably arranged at regular angular intervals on the respective connecting section, with the cams arranged on the different connecting sections interacting complementarily to form the cam-and-shaft connection. Multiple cams allow the forces acting between the disc and the axle to be distributed more evenly than with just one cam.

[0013] It can prove useful if the handle body comprises at least one of the following features: a. The handle body is substantially or exactly cylindrical, in particular hollow-cylindrical. b. The handle body is made of wood or plastic. c. The handle body is hollow or made of solid material. d. The handle body has at least one central blind bore or one central through bore, in which the axis is preferably arranged. e. The handle body has a wood grain on the casing side. f. The handle body has an embossing on the casing side.

[0014] A handle body with these features is easy to grip with a user's left or right hand, with the user's thumb preferably positioned on the side facing the user and the remaining four fingers of that hand positioned on the side facing away from the user. The dimensions of the handle body can be selected accordingly.

[0015] It may be expedient if the axle comprises at least one of the following features: a. The axle comprises an elongated axle body. b. The axle comprises at least one roller configured for rolling on the surface, preferably two rollers, which are preferably arranged at different ends of the axle body, wherein the or each roller is preferably firmly connected to one end of the axle body, for example by screwing or pressing. c. The axle, in particular the axle body, extends partially or completely through the handle body. d. The axle, in particular the axle body, protrudes from the

[0016] handle body. e. The axle, in particular the axle body, is rotatably mounted in the handle body, preferably via at least one plain bearing or at least one rolling bearing, more preferably via at least one ball bearing, wherein the or each bearing is particularly preferably arranged at one end of the handle body. f. The axle, in particular the roller, comprises a connecting section for effecting the cam rotary connection with the disc, preferably on a side facing away from the handle body. g. A maximum diameter of the axle, in particular of the roller, corresponds to a maximum diameter of the handle body. h. A lateral surface of the axle, in particular of the roller, merges flush into a lateral surface of the handle body and / or a lateral surface of the disc.

[0017] An axle with these components and properties is easy to assemble, durable and stable.

[0018] It can be useful if the disc has at least one of the following features: a. The disc is made of plastic or metal, preferably stainless steel. b. The disc has a circular outline. c. The disc comprises a grinding or polishing surface, preferably on a side facing away from the handle body, preferably on an end face, with the grinding or polishing surface particularly preferably extending over the entire end face. d. The disc has a cylindrical outer surface. e. The disc comprises a, preferably female or concave, connecting section for effecting the cam rotary connection with the axis, preferably on a side facing the handle body. f. The disc is a grinding disc, preferably with a coating of an abrasive material on the grinding surface. g. The disc is a polishing disc, preferably with a polishing structure, preferably with concentric circles on the polishing surface. h.When the handle body is pulled along the surface, the disc is spaced from this surface or has no contact with the surface. i. The disc is monolithic. j. The disc approximately has the shape of a lid. k. The disc has a maximum outer diameter that essentially corresponds to the outer diameter of the handle body. I. The disc tapers towards the end face, preferably by rounding.

[0019] A disc with these properties is easy to replace, durable, and stable. Furthermore, the disc offers high utility because it can be equipped with a large, preferably flat, grinding or polishing surface. Furthermore, a disc with these properties reduces the risk of injury and scratches. The omission of the threaded stud / pin familiar from previous models also allows for material savings and a simple design. Since there is no longer a protruding coarse thread, the discs can be arranged, packaged, or stacked more compactly.

[0020] It can be advantageous if the cam rotary joint has at least one cam which meets at least one of the following requirements: a. The or each cam is located on the axle or on the disk. b. The or each cam is designed to interact with an associated cam on the other element of the axle or the disk. c. The or each cam is located on a preferably male or female connecting section. d. The or each cam is integrally formed on a preferably male or female connecting section. e. The or each cam protrudes from a preferably male or female connecting section in the radial direction relative to a rotational axis of the cam rotary joint. f. The or each cam extends exactly or substantially in the circumferential direction relative to a rotational axis of the cam rotary joint, preferably over an angular range of approx.10° to 45°, preferably 20° to 40°, particularly preferably 25° to 35°. g. The or each cam is arranged at an angular distance of approximately 30 to 170°, preferably 45° to 120°, preferably 60° to 90° from an adjacent cam in the circumferential direction. h. The or each cam is designed as a section of a thread which preferably comprises at least one of the following features: i. The thread has a pitch in the range of 3 to 7 mm, preferably 4 to 6 mm, preferably 5 mm. ii. The thread has a flank diameter in the range of 30 to 70 mm, preferably 40 to 60 mm, preferably 45 to 55 mm. iii. The thread has a pitch in the range of 0.75 to 5%, preferably in the range of 1.25 to 3%, more preferably in the range of 1.5 to 2.5% (calculated according to the formula: arctan(pitch / pitch diameter*TT)). iv. The thread is a multi-start thread and comprises at least two parallel, preferably identical, thread sections. v.The thread is an interrupted thread and comprises at least two thread sections that are spaced from one another along a helical line describing the thread pitch. vi. The thread extends over a maximum of one full turn (360°), preferably over a maximum of half a turn (180°), more preferably over a maximum of a quarter turn (90°), particularly preferably over a maximum of an eighth turn (45°). vii. The thread is a right-hand thread. viii. The thread is aligned concentrically to the axis. ix. The thread comprises at least one thread flank facing towards the handle body and / or at least one thread flank facing away from the handle body.

[0021] There is considerable freedom of design when it comes to the cam or cams. The number of cams on the disk and / or the axle can generally be freely selected. A design with three or four threaded cams on the disk and an identical number of threaded cams on the axle has proven successful in practice. By having three or four identical cams spaced at regular angular intervals, the forces acting between the disk and the axle can be distributed well and evenly in the circumferential direction. This prevents singular force peaks between individual sections of the disk and the axle, which could lead to unintentional jamming or tilting of the disk. The cams on the disk and the cams on the axle interact in the connected position via an undercut. It is advantageous if the number of cams on the disk corresponds to the number of cams on the axle.Thus, for each cam on the disc, there is a cam on the axle. In principle, the number of cams on the disc can differ from the number of cams on the axle.

[0022] A further aspect of the present invention relates to a disk for a device according to one of the preceding claims, wherein the disk is detachably connectable to the axle via the cam-shaft connection instead of the detachably connected disk. This aspect is particularly important for the spare parts and accessories business. The cam-shaft connection serves as a universal interface. Through research and further development, improved disks with novel materials, structures, or coatings may be available in the future that are compatible with current models via the cam-shaft connection.

[0023] A further aspect of the present invention relates to a system for grinding and / or polishing a cutting tool, preferably a household knife, comprising a device according to one of claims 1 to 11 and at least one further disc according to claim 12. This aspect is particularly interesting for modular systems, wherein the handle body with the rotatable axis serves as a base module and can be coupled with various discs with different properties as interchangeable attachments.

[0024] Terms and definitions

[0025] Cam slewing ring

[0026] A cam twist connection, such as a cam twist lock, which is also called a cam twist lock or twist-off closure, is known from lids for preserving jars, among other things.

[0027] To enable the twist-off effect, which is the basis of the cam-lock closure, preserving jars do not have a circumferential thread. Instead, they have individual threaded sections into which the twist-off lid can engage with its cams (small protrusions on the inner edge of the lid).

[0028] The advantage of the cam-lock cap is its simplicity. With a preserving jar with a cam-lock cap, the lid can be hermetically closed and reopened with just a 1 / 4 turn. Despite the short and quick turn of the cam-lock cap, no contents of the jar can escape. This secure closing mechanism is created by the high spring tension between the cams in the cap and the thread in the jar. Conventional screw caps have a continuous thread, which means the user must turn several times to open or close the jar.

[0029] Multi-start thread

[0030] A multi-start thread has more than one thread start. The thread then has multiple chamfers and starts, but only one pitch. Multiple threads then run parallel to each other.

[0031] Short description of the characters

[0032] They show:

[0033] Fig. 1 is a perspective view of a grinding and polishing device according to the invention with a dismantled grinding or polishing wheel.

[0034] Fig. 2 shows the grinding and polishing device according to Fig. 1 from a different perspective.

[0035] Fig. 3 is a perspective view of an end face of the grinding and polishing device according to the invention as shown in Fig. 1 with the grinding or polishing wheel removed.

[0036] Fig. 4 is a front view of the end face according to Fig. 3. Fig. 5 is a perspective view of the dismantled grinding or polishing disc according to Fig. 1 with a view of the inside or mounting side of the disc.

[0037] Fig. 6 is a front view of the inside or mounting side of the dismantled grinding or polishing wheel according to Fig. 1.

[0038] Detailed description of the preferred embodiment

[0039] The grinding and polishing device 1 according to the invention, also referred to as a roller grinder, is based on the principle known from EP 3 278 928 A1 or DE 10 2020 123 501 B3. For details regarding the internal structure of the device, reference is made to EP 3 278 928 A1 or DE 10 2020 123 501 B3. At this point, the description of the invention is limited to the aspects relevant here.

[0040] The device 1 of the disclosed embodiment comprises a substantially cylindrical handle body 2 and an axle 3 rotatably mounted in the handle body 2. Typically, a roller grinder comprises an axle 3 rotatably mounted in the handle body 2 and two discs 4, 5 connected to the axle, between which the handle body 2 is arranged. However, alternative solutions are now available on the market in which each roller 3a is connected to its own axle or in which only one grinding or polishing wheel 4, 5 is provided. For this reason, the number of axles 3 and grinding or polishing wheels 4, 5 is at least one.

[0041] Handle body 2

[0042] The handle body 2 of the disclosed embodiment is designed as a hollow body or made of solid material, such as wood or plastic, and is hollow-cylindrical. To accommodate the axle 3 or the axle body, the handle body 2 has at least one central through-bore.

[0043] Axis 3

[0044] The axle 3 in the sense of the disclosed embodiment is an axle arrangement with an axle body (not shown) and two rollers 3a, which are connected to different ends of the axle body and are located (with the smallest possible gap to enable relative rotation to the handle body 2) directly adjacent to the respective axial ends of the handle body 2. The rollers 3a can, for example, be slipped onto the axle body or pressed or screwed to the axle body.

[0045] The axle body (not shown) extends completely through the handle body 2 and protrudes from the handle body 2 on both sides. The axle body is rotatably mounted in the handle body 2 via two plain bearings or roller bearings, which are arranged at the ends in the through-bore of the handle body 2. The roller 3a comprises, on a side facing away from the handle body 2, a central projection 3b, which represents a male connecting section 3b for establishing the cam-shaft connection 3c, 4d with the disc 4, 5.

[0046] The maximum diameter of each roller 3a corresponds to a maximum diameter of the handle body 2 and each disc 4, 5, wherein a circumferential surface of each roller 3a merges flush into the circumferential surface of the handle body 2 and a circumferential surface 4a of the disc 4, 5.

[0047] In this case, each of the rollers 3a has a circumferential annular groove in which a rubber ring 6 is held in a form-fitting manner. The rubber rings 6 on both rollers 3a are the same size and, in conjunction with the continuous axle, ensure stable, straight-line running with particularly smooth operation when using the roller grinder 1.

[0048] The concentric projection 3b on the end of each roller 3a facing away from the handle body 2 has a diameter that is approximately 25% smaller than the diameter of the outer surface of the roller 3a itself. On the cylindrical outer surface of this projection 3b, there are a total of three cams 3c designed as threaded sections, which protrude radially away from the rotation axis X of the cam-type rotary joint 3c, 4d to together form a three-start (right-hand) external thread that extends over approximately 1 / 8 of a turn or revolution. The cams 3c each extend over slightly more than 40° of the outer circumference of the projection 3b and are arranged at regular angular intervals of slightly less than 80°. Due to the large distances between the cams 3c in the circumferential direction, they can be easily inserted into the spaces between the corresponding cams 4d of the disc 4, 5.The projection 3b forms a male connecting section due to its convex shape.

[0049] The three-start thread formed by the three parallel cams 3c or thread sections has a pitch of approximately 5 mm. With a pitch diameter of 50 mm, the formula: arctan (5 mm / 50 mm * TT) results in a pitch angle of 1.82°.

[0050] Disc 4, 5

[0051] Each disc 4, 5 is monolithically made of stainless steel and approximately takes the form of a cover with a disc-shaped cover surface 4a, a cylindrical outer surface 4b with a circular outline, which tapers towards the flat end facing away from the handle body 2 by rounding and forms a circumferential, annular edge on the side facing the handle body 2. Each disc 4, 5 includes a grinding or polishing surface 4a that extends over the entire end face. On a side facing the handle body 2, each disc 4, 5 includes, radially inside the circumferential edge, a concave or female connecting section 4c for establishing the cam-shaped rotary connection 3c, 4d with the axle 3. The outer surface of each disc 4, 5 has the same diameter as the outer surface of the roller 3a and, when connected, merges flush with it.Each disc 4, 5 comprises a (hollow cylindrical) concave receptacle 4b as a female connecting section 4c, on the inner circumference of which are three cams 4d designed as threaded sections, which protrude radially toward the rotational axis of the cam-type rotary joint 3c, 4d to form a three-start mating or internal thread corresponding to the external thread of the axle 3. Each cam 4d on the disc 4, 5 is designed to interact with an associated cam 3c on the axle 3.

[0052] Each cam 4d extends, relative to a rotation axis X of the cam slewing ring, essentially in the circumferential direction U over an angular range of 45°, ie one eighth of a turn, and is arranged at an angular distance of approximately 75° from a cam 3c, 4d adjacent in the circumferential direction U.

[0053] In the embodiment as a grinding wheel 4, the wheel comprises a coating of an abrasive material (diamond) on the grinding surface 4a. The grinding wheel 4 preferably comprises a diamond coating with new superblock diamonds, which are preferably set in a nickel bed, which leads to an increased service life.

[0054] In the design as a polishing disc, the disc comprises a polishing structure with concentric circles on the polishing surface.

[0055] The polishing disc 5 shown in its assembled state in Figs. 1 and 2 is recognizable by its concentric rings and is preferably also connected to the respective roller 3a via an identical cam-shaft connection. To avoid repetition, however, the cam-shaft connection between the polishing disc 5 and the respective roller 3a will not be explained separately. Instead, reference is made to the above explanations.

[0056] The disc 4, 5 has a smaller diameter than the rubber ring 6 and is spaced from the surface when the handle body 2 is pulled along the surface. Therefore, during grinding or polishing of a cutting tool, there is no contact between the disc and the surface.

[0057] Cam slewing ring

[0058] The male and female connecting sections 3b, 4c of the axle 3 and the disk 4, 5, as well as the cams 3c, 4d arranged thereon, cooperate complementarily to form the cam-shaped rotary joint 3c, 4d. In the connected position of the cam-shaped rotary joint 3c, 4d, the male and female connecting sections 3b, 4c, as well as the cams 3c, 4d, are concealed or invisible. The cam-shaped rotary joint 3c, 4d can be reversibly transferred in less than 1 / 8 of a rotation of the disk 4, 5 relative to the axle 3 about a rotation axis X of the cam-shaped rotary joint 3c, 4d between a release position, in which the disk 4, 5 and the axle 3 are detached from one another, and a connection position in which the disk 4, 5 and the axle 3 are connected in a force-fitting and form-fitting manner for grinding and / or polishing the cutting tool.

[0059] The thread is concentrically aligned with axis 3 and right-handed, so that the disc 4, 5 moves toward the handle body 2 when rotated clockwise relative to axis 3, and moves away from the handle body 2 when rotated counterclockwise. In the connected position, the disc 4, 5 rests against the axis 3 in the direction of the handle body 2.

[0060] The cam slewing ring is designed to be self-locking, so that the disc 4, 5 clamps itself firmly to the shaft 3 in the connected position. In the connected position, the clamping force can be further increased by increasing the rotation of the disc 4, 5 clockwise. The cam slewing ring can only be released by external, preferably manual, force. The clamping force can be specifically influenced or increased by a low thread pitch and / or long thread flanks that rub against each other, especially with high friction coefficients.

[0061] In this case, a thread flank of each cam 4d of the disc 4, 5 facing away from the handle body 2 clamps itself frictionally onto a thread flank of an associated cam 3c of the axis 3 facing the handle body 2.

[0062] The cam slewing ring forms a universal interface for various discs 4, 4,5.

[0063] Each replacement or spare disc 4, 5 for the device 1 according to the invention can be releasably connected to the axle 3 via the cam rotary connection 3c, 4d instead of the releasably connected disc 4, 5.

[0064] Method for connecting the disc 4, 5 to the axle 3 via the cam slewing ring To connect the disc 4, 5 to the respective axle 3, the disc 4, 5 is first loosely placed on the projection 3b of the roller 3a so that the cams 4d of the disc 4 move between the cams 3c on the outer surface of the projection 3b of the roller 3a. The disc 4, 5 is then rotated clockwise relative to the roller 3a around the axis of rotation of the cam slewing ring, which coincides with the axis of rotation of the roller 3a, so that the cams 4d of the disc 4 engage with the cams 3c on the outer surface of the projection 3b and form an undercut.By further clockwise rotation of the disc 4, 5 relative to the roller 3a, the cams 4d of the disc 4 and the cams 3b slide against each other in threaded engagement on the outer surface of the projection 3b, so that the disc 4, 5 approaches the roller 3a along the rotation axis of the cam-type rotary joint and finally rests against it without a gap, so that the outer surfaces of the disc 4, 5 and the roller 3a lie flush against each other. Upon further clockwise rotation, the cams 3c, 4d clamp in a self-locking manner as described above. By rotating clockwise, the disc 4, 5 can be released from the axis 3 again.

[0065] Advantages of the invention

[0066] Grip roller 2 is 5mm longer than previous models. It's easy to grip and can accommodate four fingers side by side. The cam-swivel connection represents the innovative quick-release system for discs 4 and 5.

[0067] The design of the device 1 according to the invention is even simpler than that of previous models due to the concealed arrangement of the cam-type rotary joint in the connected position. A manufacturer's logo can be printed or embossed on the handle body 2.

[0068] List of reference symbols

[0069] 1 grinding and polishing device (roller grinder)

[0070] 2 handle bodies

[0071] 3 axis (axis arrangement)

[0072] 3a roller

[0073] 3b projection (male connecting section)

[0074] 3c Cam (external thread)

[0075] 4 grinding and polishing discs

[0076] 4a Grinding and polishing surface

[0077] 4b lateral surface

[0078] 4c receptacle (female connection section)

[0079] 4d cam (internal thread)

[0080] 5 polishing disc

[0081] 6 rubber ring

Claims

Claims 1. Device (1) for grinding and / or polishing a cutting tool, preferably a household knife, comprising: a handle body (2), at least one axis (3) rotatable relative to the handle body (2), and at least one grinding or polishing disk (4, 5) which is connected to the axis (3) in such a way that when the handle body (2) is pulled, preferably manually, along a surface such as a table surface, the disk (4, 5) rotates relative to the handle body (2), in particular for grinding and / or polishing a cutting tool applied thereto, characterized in that the axis (3) and the disk (4, 5) are detachably connected via a cam-type rotary connection (3c, 4d).

2. Device (1) according to the preceding claim, characterized in that the cam rotary connection (3c, 4d) can be reversibly transferred in less than one revolution between a release position, in which the disc (4, 5) and the axle (3) are released from one another, and a connection position in which the disc (4, 5) and the axle (3) are non-positively and / or positively connected for grinding and / or polishing the cutting tool, preferably in a maximum of half a revolution, preferably in a maximum of a quarter revolution.

3. Device (1) according to the preceding claim, characterized in that the disc (4, 5) moves in the direction of the handle body (2) when the cam rotary connection (3c, 4d) is transferred from the release position to the connection position and / or moves away from the handle body (2) when the cam rotary connection (3c, 4d) is transferred from the connection position to the release position, wherein the disc (4, 5) is preferably supported on the axis (3) in the connection position in the direction of the handle body (2).

4. Device (1) according to one of the preceding claims, characterized in that the cam rotary connection is designed to be self-locking, so that the disc (4, 5) clamps itself firmly to the axis (3) in the connecting position, wherein preferably a clamping force in the connecting position can be further increased by increasing rotation of the cam rotary connection, wherein particularly preferably a release of the cam rotary connection is only possible with external, preferably manual, force.

5. Device (1) according to one of the preceding claims, characterized in that an axis of rotation (X) of the cam rotary connection (3c, 4d) is aligned coaxially to the axis (3).

6. Device (1) according to one of the preceding claims, characterized in that the axis (3) and the disk (4, 5) have complementary, preferably male and female, connecting sections (3b, 4c) to form the cam-shaped rotary connection (3c, 4d), wherein preferably the axis (3) has a male connecting section (3b) and the disk (4, 5) has a female connecting section (4c), or vice versa, wherein preferably the connecting sections (3b, 4c) are concealed or invisible in the connected position of the cam-shaped rotary connection (3c, 4d).

7. Device (1) according to the preceding claim, characterized in that each connecting section (3b, 4c) has a plurality of cams (3c, 4d), which are preferably identical and are preferably arranged at regular angular intervals on the respective connecting section (3b, 4c), wherein the cams (3c, 4d) arranged on the different connecting sections (3b, 4c) cooperate complementarily to form the cam rotary connection (3c, 4d).

8. Device (1) according to one of the preceding claims, characterized in that the handle body (2) is substantially or exactly cylindrical, in particular hollow-cylindrical, preferably made of wood or plastic.

9. Device (1) according to one of the preceding claims, characterized in that the axle (3) has an elongated axle body which is rotatably mounted in the handle body (2), wherein the axle (3) preferably comprises at least one roller (3a) configured to roll on the surface, preferably two rollers (3a), which are preferably arranged at different ends of the axle body, wherein the or each roller (3a) is particularly preferably firmly connected to one end of the axle body, for example by screwing or pressing.

10. Device (1) according to one of the preceding claims, characterized in that the disc (4, 5) comprises a grinding or polishing surface (4a), preferably on a side facing away from the handle body (2), preferably on an end face, and a connecting section (4c) for effecting the cam rotary connection (3c, 4d) with the axis (3), preferably on a side facing the handle body (2), wherein the disc (4, 5) preferably tapers towards the end face, preferably by rounding.

11. Device (1) according to one of the preceding claims, characterized in that the cam-type rotary joint has at least one cam (3c, 4d) which meets at least one of the following requirements: a. The or each cam (3c, 4d) is located on the axle (3) or on the disc (4, 5). b. The or each cam (3c, 4d) is designed to cooperate with an associated cam (3c, 4d) on the other element of the axle (3) or the disc (4, 5). c. The or each cam (3c, 4d) is located on a preferably male or female connecting section (3b, 4c). d. The or each cam (3c, 4d) is integrally formed on a preferably male or female connecting section (3b, 4c). e. The or each cam (3c, 4d) protrudes from a preferably male or female connecting section (3b, 4c) in the radial direction relative to a rotation axis of the cam rotary connection (3c, 4d). f. The or each cam (3c, 4d) extends, relative to a rotational axis (X) of the cam-type rotary joint, exactly or substantially in the circumferential direction (U), preferably over an angle of approximately 10° to 45°, preferably 20° to 40°, particularly preferably 25° to 35°. g. The or each cam (3c, 4d) extends, relative to a rotational axis (X) of the cam-type rotary joint, exactly or substantially in the circumferential direction (U), preferably over an angle of approximately 10° to 45°, preferably 20° to 40°, particularly preferably 25° to 35°.each cam (3c, 4d) is arranged at an angular distance of approximately 30 to 170°, preferably 45° to 120°, more preferably 60° to 90° from an adjacent cam (3c, 4d) in the circumferential direction (U). h. The or each cam (3c, 4d) is designed as a section of a thread, which preferably comprises at least one of the following features: i. The thread has a pitch in the range of 3 to 7 mm, preferably 4 to 6 mm, more preferably 5 mm. ii. The thread has a flank diameter in the range of 30 to 70 mm, preferably 40 to 60 mm, more preferably 45 to 55 mm. iii. The thread has a pitch in the range of 0.75 to 5%, preferably in the range of 1.25 to 3%, more preferably in the range of 1.5 to 2.5% (calculated according to the formula: arctan(pitch / pitch diameter*TT)). iv. The thread is a multi-start thread and comprises at least two parallel, preferably identical, thread sections. v.The thread is an interrupted thread and comprises at least two thread sections spaced apart along a helical line describing the thread pitch. vi. The thread extends over a maximum of one full turn (360°), preferably over a maximum of half a turn (180°), preferably over a maximum of a quarter turn (90°), particularly preferably over a maximum of an eighth turn (45°). vii. The thread is a right-hand thread. viii. The thread is concentrically aligned with the axis (3). ix. The thread comprises at least one thread flank facing the handle body (2) and / or at least one thread flank facing away from the handle body (2).

12. Disc (4, 5) for a device (1) according to one of the preceding claims, wherein the disc (4, 5) is detachably connectable to the axle (3) via the cam rotary connection (3c, 4d) instead of the detachably connected disc (4, 5).

13. System for grinding and / or polishing a cutting tool, preferably a household knife, comprising a device (1) according to one of claims 1 to 11 and at least one further disc (4, 5) according to claim 12.

Images