V. Re-edge grinding of the drill bit
Drill bit grinding discrimination
The criteria for determining the drill bit to be re-grinded are:
1. The amount of wear on the edges of the cutting edge, cross-edge and edge of the cutting edge;
2. Dimensional accuracy and surface roughness of the machined hole;
3. The color and shape of the chip;
4. Cutting resistance (indirect values such as spindle current, noise, vibration, etc.);
5. Processing quantity, etc.
In actual use, accurate and convenient criteria for judging should be determined from the above indicators according to the specific situation. When using wear as the criterion, the best grinding period for the most economicality should be found. Because the main edge grinding part is behind the head and the cross-blade, if the wear amount of the drill bit is too large, the edge wear takes more time, the grinding amount is large, and the number of re-grindable times is reduced (the total service life of the tool = the tool life after heavy grinding, it will shorten the total service life of the drill bit; the size of the machined hole is precision. When the degree is used as the criterion, the column gauge or limit gauge is used to check the shear expansion, straightness, etc. Once the control value exceeds the control value, it should be grinded immediately. When the cutting resistance is used as the discrimination standard, the method of automatic shutdown immediately after exceeding the set limit value (such as spindle current) can be adopted. When the processing quantity limit management, it should be comprehensive In line with the above judgment, set the criteria for discrimining.
Blade grinding method of drill bit
When re-edge grinding the drill bit, it is best to use a special machine tool or universal tool grinder, which is very important to ensure the service life and machining accuracy of the drill bit. If the original drilling type is well machined, it can be re-grinded according to the original drill type; if the original drill type is defective, the back shape can be appropriately improved and the cross-edge grinding can be carried out according to the purpose of use.
When grinding the edge, you should pay attention to the following points:
1. Prevent overheating and reduce the hardness of the drill bit;
2. The damage on the drill bit (especially the damage to the edge and face position of the edge) should be removed;
3. Drilling should be weighed;
4. Be careful not to touch the edge during edge grinding, and remove the burrs after the edge grinding;
5. For cemented carbide bits, the shape of the edge grinding has a great impact on the performance of the bit. The drill type at the time of leaving the factory is the best drill type obtained through scientific design and repeated testing. Therefore, the original blade type should generally be maintained when re-edge grinding.
