1 Introduction
Sharpening its traditional method of grinding principle, when carried out on the flank twist drill grinding, grinding inappropriate if the parameter is selected, or due to the use of the inner cone sharpening increases apex distance when needed, often after drill flank upturned tail carryover phenomenon, this carryover Alice sometimes very high, when Alice to a certain extent, when using this drill hole, after the end of the drill bit flank directly top in the bottom of the hole. So that the drill can not be drilled, therefore, twist drill Sharpening must reduce or overcome this carryover phenomenon.
2.Flank carryover method after overcoming drill

2.1 with optimized grinding parameters
Where grinding parameters can guarantee within a reasonable range of values ​​after the twist angle and the outer edge of the chisel bevel are prescribed to optimize grinding parameters it is called, this time, flank generally no larger carryover phenomenon after drill .

2.2 make a counter-clockwise angle drill additional parameters
When the drill diameter is small, optimized from the apex value is very small, which can cause internal Sharpening When using the structure is difficult to achieve. In order to increase apex distance, and so after the outer edge of the chisel blade bevel angle and kept within a predetermined range of reasonable values, especially not produce carryover phenomenon, add a sharpening parameter allows the drill to attach a counterclockwise rotation angle . After calculation, the actual grinding test and measurement, good effect, proved that this method is not only suitable for small diameter drill bit, also suitable for large diameter drill bit, and that it is for the drill flank after the elimination of the phenomenon of carryover effects.

Comparison of the two grinding methods 3

Sharpening when traditional method of grinding twist drill conducted in accordance with, the drill will be emerging behind the rear flank of upturned carryover phenomenon, in some cases, to eliminate the carryover phenomenon, often to be repeated adjustment trial mill grinding parameters observed and measured, very troublesome, the result is not necessarily satisfactory.
Sharpening using the new method, that is based on the original four grinding parameters on, let the drill to attach a counterclockwise rotation angle, after a lot of on board computing and actual test mill, good effect, can not guarantee drill Inner angle, horizontal edge bevel angle in a predetermined range of reasonable value, but, can effectively control the rear flank of the drill overcome carryover phenomenon.

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