ROLLER SANDER

Abstract

A device for grinding and/or polishing a cutting edge of a cutting tool. The device includes a handle, at least one roller rotatable relative to the handle, and at least one disc that is rotatable relative to the handle for grinding and/or polishing the cutting edge of the cutting tool. The device can be moved over a substrate by exerting force on the handle so that the roller, which is rotating relative to the handle, rolls on the substrate and the disc can be set in rotation. The disc may be rotatable at a different rotational speed/angular velocity to the roller.

Claims

1. A device for grinding and/or polishing a cutting edge of a cutting tool, comprising: a handle; at least one roller rotatable relative to the handle; and at least one disc rotatable relative to the handle for grinding and/or polishing the cutting edge of the cutting tool, wherein the device is movable over a base by exerting force on the handle, so that the roller rotating relative to the handle rolls on the base and the disc can be set in rotation, and wherein the disc is rotatable at a different rotational speed/angular velocity than the roller.

2. The device according to claim 1, wherein the disc rotates at a different rotational speed/angular velocity than the roller when the roller rotates relative to the handle.

3. The device according to claim 1, wherein the disc rotates in the same direction or in an opposite direction to the direction of rotation of the roller when the roller rotates relative to the handle.

4. The device according to claim 1, wherein the disc rotates with a fixed or adjustable transmission ratio with respect to the roller when the roller rotates with respect to the handle.

5. The device according to claim 1, wherein the rotational movements of the roller and the disc are coupled via a gear, and the gear is either a toothed gear or a planetary gear.

6. The device according to claim 5, wherein the transmission has two coaxial central gears and at least one transmission gear motion-coupled to the central gears.

7. The according to claim 5, wherein the roller is a ring gear having internal teeth.

8. The according to claim 1, wherein the device has an axle rotatably mounted on or in the handle, the axle being set in rotation upon rotation of the roller relative to the handle, the disc is connected to the axle in a rotationally fixed and/or detachable manner, and the roller is rotatably mounted on the axle.

9. The device according to claim 1, wherein the handle, the roller, the disc, and the axle are arranged coaxially to each other.

10. The according to claim 8, wherein the axes of rotation of the roller, the disc and the axis coincide with a central axis of the handle.

11. The according to claim 1, wherein a disc is arranged on each of the two end faces of the device, a roller is arranged between each disc and the handle, each of the two discs have its own drive and are coupled via its own transmission to the roller arranged between the disc and the handle.

12. The device according to claim 1, wherein the handle, the roller, and the disc have exactly or substantially identical outer diameters such that shell surfaces of the handle, the roller, and the disc are arranged flush with one another.

13. The device according to claim 1, wherein the roller has a circumferential rubber ring that is arranged in at least one groove on the outer circumference of the roller, the rubber ring having the largest diameter with respect to an axis of the device, so that the rubber ring rolls on the base when the device is moved over the base.

14. A system comprising the device according to claim 1 and a device for fixing the cutting edge of the cutting tool relative to the disc during grinding and/or polishing such that a flank and/or extension plane of the cutting edge of the cutting tool is oriented relative to the disc at an angle in the range from 5° to 30°.

15. The device according to claim 2, wherein the disc rotates at a greater rotational speed/angular velocity than the roller when the roller rotates relative to the handle, the greater rotational speed/angular velocity being at least 50% than the rotational speed/angular velocity of the roller.

16. The device according to claim 6, wherein the roller and the disc are connected or coupled in a rotationally fixed manner to one of the central gears, and an axis of rotation of the at least one transmission gear is offset relative to the axes of rotation of the central gears with respect to the handle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0065] FIG. 1 shows a schematic partial sectional view of a device according to the invention according to the preferred embodiment, the left half of the image being shown in section along the center axis of the device and the right half of the image being shown as an external view of the device; and

[0066] FIG. 2 a schematic cross-sectional view of the device according to the invention as shown in FIG. 1 along line II-II, the components of the device being shown in simplified form.

DETAILED DESCRIPTION

[0067] A preferred embodiment of the present invention is described in detail below with reference to the accompanying drawings.

[0068] The present embodiment relates to a device 1, also referred to as a roller grinder, for grinding and/or polishing a cutting tool such as a household knife. This device 1 is configured to be moved in a rolling manner over a base U, and in so doing to set the grinding and/or polishing wheels 4 arranged on the end face in rotation, so that a cutting edge 9 of the cutting tool applied against the disc 4 is ground or polished. The principle of such roller grinders is basically known from the patent documents EP 3 278 928 A2 as well as DE 297 03 326 U1. The present description of the invention essentially explains the differences from the known roller grinders.

[0069] The roller grinder 1 according to the invention shown in FIGS. 1 and 2 comprises a hollow cylindrical handle 2 made of wood, two annular rollers 3 made of metal arranged on the end face of the handle 2 and rotatable relative to the handle 2, and two circular discs 4 made of metal, each arranged on the end face of the roller grinder 1 and rotatable relative to the handle 2 for grinding or polishing the cutting tool. Force is generally exerted on the handle 2 by the hand of a user, for example by traction or pressure, so that the roller grinder 1 is moved over a base U and the rollers 3 rotate relative to the handle 2 as they roll on the base U. Each disc 4 is screwed to an axle 6 rotatably mounted in the handle 2 via an integrally formed threaded pin and is connected to this axle 6 in a rotationally fixed manner.

[0070] The handle 2, the roller 3, the disc 4 and the axle 6 are arranged coaxially to each other, so that the axes of rotation A of the roller 3, the disc 4 and the axle 6 coincide with the center axis A of the device 1 or the handle 2.

[0071] Each of the two discs 4 arranged on the end face of the device 1 is coupled via its own transmission 5 to the roller 3 arranged between the disc 4 and the handle 2. The handle 2, the roller 3 and the disc 4 have identical outer diameters, so that the cylindrical shell surfaces of the handle 2, the roller 3 and the disc 4 are arranged flush with one another. Each roller 3 comprises a circumferential rubber ring 7 disposed in a groove on the outer circumference of the roller 3. Of all the components of the device 1, the rubber ring 7 has the largest diameter with respect to the center axis A of the device 1, so that when the device 1 is moved over the base U, the rubber ring 7 rolls on this base U.

[0072] In FIG. 1, the roller grinder 1 according to the invention is shown in a partial section along the center axis A of the device 1. As previously explained, the disc 4 arranged on the right-hand end face in FIG. 1 is also coupled to the associated roller 3 via a (concealed, preferably identical) transmission 5. Alternatively, however, it is also possible for the roller 3 and the disc 4 on the right end face to be coupled to each other in a rotationally fixed manner, i.e. without the interposition of a transmission, as is known from patent document EP 3 278 928 A2. The left and right discs 4 can also be coupled to the respective roller 3 via different transmissions or gear ratios.

[0073] Due to the transmission 5, the disc 4 is set in rotation by rotation of the associated roller 3 relative to the handle 2, so that when the roller 3 rotates, the disc 4 rotates at a different rotational speed/angular velocity than the roller 3. Depending on the gear ratio, the rotational speed/angular velocity of the disc 4 is preferably at least 50% higher than the rotational speed/angular velocity of the roller 3.

[0074] In the present embodiment, the transmission 5 is configured as a planetary gear. This planetary gear comprises two coaxial central gears 5a, 5b and at least one transmission gear 5c motion-coupled to the central gears 5a, 5b. In order to optimize the power transmission between the central gears 5a, 5b and distribute it evenly around the circumference of the roller 3, a plurality of planetary gears 5c can be arranged, preferably at regular angular intervals, around the axis of rotation A of the roller 3. The roller 3 is formed as a ring gear and comprises internal teeth on the inner circumference on the side facing the handle 2. This internal toothing is in mesh with an external toothing of the transmission gear 5c, the axis 5d of which is fixed relative to the handle 2 and offset parallel to the central axis A of the handle 2. The axle 6 has external teeth and is also in mesh with the transmission gear 5c.

[0075] When the roller grinder 1 rolls in the direction R1, as shown in FIG. 2, the roller 3 rotates by rolling on the base U in the direction R2. If the handle 2 is held by the hand of a user (not shown), the handle 2 does not rotate with respect to the base U when the roller 3 is rolling on the base U. Thus, the axis 5d of the transmission gear 5c, which is fixed with respect to the handle 2, remains stationary with respect to the base U and the axis of rotation A of the roller 3.

[0076] Due to the meshing between the internal teeth of the roller 3 and the external teeth of the transmission gear 5c, the rotational movement of the roller 3 in direction R2 is translated into the rotational movement of the transmission gear 5c in direction R3. The rolling or circumferential speeds of the gears in mesh in the area of the pitch circles are identical. However, since the transmission gear 5c has a significantly smaller gear or pitch diameter than the roller 3, the transmission gear 5c rotates about its axis 5d at a higher rotational speed/angular velocity than the roller 3 rotates about its axis A.

[0077] Via a further toothed engagement, the rotational movement of the transmission gear 5c is now transmitted to the axle 6, which is rotatably mounted in the handle 2 and is in turn non-rotatably connected to the disc 4. Since the gear or pitch diameters of the transmission gear 5c and the axle 6 are approximately equal, the rotational speed/angular velocity of the axle 6 is approximately equal to the rotational speed/angular velocity of the transmission gear 5c. In the present case, the rotational movements of the roller 3 and the respective adjacent disc 4 are coupled in such a way that when the roller 3 rotates relative to the handle 2, the disc 4 rotates in the opposite direction to the direction of rotation of the roller 3.

[0078] By selecting the gear or pitch diameters of the roller 3, the transmission gear 5c and the axle 6, the ratio of the rotational speed/angular velocity of the disc 4 relative to the roller 3 can be influenced.

[0079] In the present embodiment, the roller 3 and the disc 4 are coupled via the transmission 5, so that the roller 3 provides a mechanical drive for the disc 4.

[0080] If the device 1 is held by the handle 2 and moved over the base U, such as a table surface in the direction R1, the linear movement is converted into a rotational movement via the roller 3 rolling on the base U. The linear movement is then transmitted to the disc 4. Friction or gear contact with the roller 3 drives the transmission gear 5c, which then transmits its rotational movement to the axle 6 and the disc 4 connected to it.

[0081] However, it is also possible that the roller 3 and the disc 4 are mechanically decoupled from each other, whereby, for example, a sensor detects the rotational movement of the roller 3 and outputs a signal to a control unit which, based on the signal output by the sensor, controls a motor to generate the rotational movement of the disc 4 so that the roller 3 and the disc 4 rotate at different rotational speeds relative to each other. Accordingly, the transmission 5 is not an essential feature of the device 1.

[0082] The following embodiments are essentially based on the first embodiment shown in FIGS. 1 and 2 and have identical features except for the differences mentioned below.

[0083] In a second embodiment, the grinding wheel is thicker than in the first embodiment and has a circumferential groove for the rubber ring on the outer circumference. If the rubber ring is moved from the groove on the outer circumference of the roller 3 shown in FIG. 1 into the groove on the outer circumference of the grinding wheel 4, the rolling speed of the roller grinder 1 changes.

[0084] In a third embodiment, the roller grinder 1 has a motor-driven grinding or polishing disc 4 at at least one end, which is driven, for example, by an electric drive and is supplied with energy from a battery or accumulator.

[0085] In a fourth embodiment, the roller grinder 1 has a spring winder motor at at least one end as the drive for the transmission 4. This enables higher rotational speeds for polishing the knife flanks.