The selection of main geometric parameters for the grinding of twist drill bit

The main geometric parameters of twist drill include the choice of cutting lip angle, the choice of land angle of cutting edge and lip clearance angle of cutting edge, the analysis of the influence of helix angle on the life of drill bit and the treatment of cutting edge.

 

Cutting lip angle determines chip width and bit front angle. When the diameter and feed of the bit remain unchanged, increasing the top angle will narrow the iron filings and reduce the load per unit cutting lip. Cutting lip angle has a great influence on the land angle. Increasing cutting lip angle correspondingly can improve the cutting conditions at the core. Cutting lip angle affects the direction of chip outflow. According to the relevant tool design data and the characteristics of low hardness but high viscidity of the processed product, the cutting lip angle of the bit is selected to be 140°.

 

The land angle of a twist drill is determined by other geometric parameters of the drill. In high-speed cutting, the rake angle has little influence on cutting deformation and cutting force, and the strength of tool tip can be enhanced with a smaller land angle. When the land angle is determined, the bigger the lip clearance angle is, the sharper the edge is, but the wedge angle will decrease correspondingly, which will affect the strength and heat dissipation area of the tool. For this purpose, the lip clearance angle of the drill bit is selected as a smaller one, which is 8°.

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Operation instructions of drill bit grinder

PG drill bit grinder operational processes, Drill Re-sharpener, Drill Bit Grinding Machine Manufacturers, drill bit grinder, twist drill bits, drill bit

How to use drill bit grinder?

Grinding of Cutting Lip Angle

Start switch, after the motor turns steadily, place the fixture group of the chuck on the right side of the grinding table. Make the notch of the fixing seat is aligned to the stepped surface.

Push it to the end until after grinding sound has stopped, then take it out and turn 180 ° .  Grind the other side in the same way until silent.

Do not hold the drill handle while grinding, the force will affect the center of the drill uneven.

Cutting Lip Angle adjustable Angle 90 ° ~ 135 °

 

Grinding of Lip Clearance Angle

When grinding the dead center, chuck fixed group in the dead center grinding, gently pushed to the bottom of the grinding wheel, in the end, after spinning around by the end of silent, then take it out and turn 180 ° . Grind the other side in the same way until silent.

When the dead center is ground, the clamping head fixing tool set moves up and down. The position of the center of the missing Angle line of the clamping head fixator is aligned with the locating pin on the grinding seat.

 

Grinding of Major Cutting Lip

Grinding major cutting lip, chuck fixed with a group in the chisel edge grinding, gently push the bottom wheel, spin to the right to silence, then return to the center, take out and turn 180 °, grinding to the silent on the other side in the same way.

All contact holes in the machine must be cleaned immediately after the drill has been ground for the next use.