| 摘要 |
A device for sharpening includes a housing, inside which the channel is made in the form of a truncated cone with longitudinal cut along the generatrix of the cone. In the cut the cutter is tangentially installed, one part of which, which has a length close in the value to the half of length of cutter, adjoins the larger basis of cone, another part, which is the continuation of the first one, penetrates the smaller basis and comes out of the limits of the latter for the length close to the length of working part of the slate pencil. The cutting edge of the cutter comes out inside the channel for the value of chip, which is removed. In accordance with the invention, another part of cutter is bent back in the outgoing direction from the channel thus that its cutting edge in this part has a form of curve, which does not come out of the limits of channel and generatrix of cone extended beyond the limits of completely open smaller basis to imaginary apex of the cone. Another part of the cutter has a form of curve close to the straight line, bent back for an angle from 1.8 to 3.9° from the imaginary straight line, which is the continuation of the first part of the cutter. The diameter of smaller basis is located within the range from 2.4 to 2.8 mm.
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