Knife-sharpening machine
The invention relates to a knife sharpening machine comprising a plate-type holding device on which two intersecting sharpening bars are rotationally mounted and loaded in relation to each other by means of springs. The sharpening bars, at least in the grinding area, are made of a ceramic material. The plate is provided with a slit which is open on one end and closed on the other, extending as far as the intersection point of the sharpening bars. When pressure is exerted by the knife in the direction of the closed slit end, the sharpening bars are spread apart from each other counter to the force of the springs. Curved guides are provided on both sides of the slit. The ends of the sharpening bars, facing away from the axes of rotation thereof, are guided therein.
1. A knife sharpening apparatus having a holding device on which two intersecting sharpening rods are pivotally mounted and loaded toward each other by springs, said holding device having a slot open at one end and closed at the other end and extending to an intersection point of the sharpening rods so that upon pressure of a knife in the slot in the direction of the closed end of the slot the sharpening rods are spread apart against the force of the springs, wherein the sharpening rods are made of ceramics at least in a grinding area, and curved guides are provided on each side of the slot for guiding ends of the sharpening rods facing away from their rotation axes.
2. A knife sharpening device according to claim 1 , wherein the two sharpening rods have a polygonal cross section, opposing sides of the two polygons extending parallel to each other.
3. A knife sharpening device according to claim 1 , wherein the two sharpening rods have on opposing sides a portion tapering toward the rotation axes in a closed end area of the slot.
4. A knife sharpening device according to claim 1 , wherein the ceramics consists of silicon carbide or tungsten carbide.
5. A knife sharpening device according to claim 1 , wherein the holding device is fastened to a base.
6. A knife sharpening device according to claim 1 , wherein the sharpening rods are each fastened to a respective pin pivotally mounted on the holding device.
7. A knife sharpening device according to claim 6 , wherein the springs swiveling the sharpening rods toward each other are formed by torsion bars extending on either side of the slot and fastened at one end rotationally fast to the respective pin and at the other end to the holding device.
8. A knife sharpening apparatus according to claim 6 , wherein the pins for pivotally mounting the sharpening rods and a second pair of pins for guiding the sharpening rods are formed of plastic and have receiving means for insertion of the ends of the sharpening rods.
9. A knife sharpening device according to claim 1 , wherein the holding device is formed by a plate and the curved guides constitute curved guide slots in the plate.
10. A knife sharpening device according to claim 9 , wherein each said sharpening rod is provided for guidance in the respective curved guide slot at the end facing away from the respective rotation axis with a second pin having a portion with reduced diameter for engaging the guide slot.
11. A knife sharpening apparatus according to claim 9 , wherein the pins for pivotally mounting the sharpening rods have a portion with reduced diameter for engaging a respective bore in the plate.
12. A knife sharpening apparatus according to claim 11 , wherein a counterpart connectable with the pins and having a larger diameter than the portion with reduced diameter is provided on the other side of the plate.
13. A knife sharpening apparatus according to claim 9 , wherein a base to which the holding plate is fastened is formed by a pedestal.
14. A knife sharpening apparatus according to claim 1 , wherein the slot is bell mouthed in an open end area.