(l) Take measures from the sharpening of the drill bit […]
(l) Take measures from the sharpening of the drill bit to overcome the phenomenon of drilling deviation. To shorten the chisel edge, make the edge shape of the drill well centered, and form a turning point on the main cutting edge, which is conducive to chip separation and chip breaking. Increase the rake angle of the grinding part, increase the chip removal space of the core part, and also ensure that the core of the self-drilling and self-tapping screw has a certain strength.
(2) Cutting probing is recommended. The cutting speed adopts the lower limit when selecting the table or calculating with the formula, and select the feed amount according to the low hardness material of the two materials, feed slowly, and reduce the axial pressure appropriately.
(3) An appropriate selection should be made when determining the drilling position of the self-drilling and tapping screw. When making a punch before drilling, it should be slightly on the side of the material with high hardness, that is, the center of the hole is set on the cast iron side of the edge of the two materials. In order to offset the deviation of the self-drilling and self-tapping screw bit to the low-hardness material caused by the low resistance.
Adopting the above measures has obvious effect on overcoming the hole offset phenomenon of drilling two different materials.