Drilling is to use a certain torque to screw the tap into the bottom hole to be drilled to process the internal thread.
(1) The hole of the threaded bottom hole on the aluminum alloy die casting should be chamfered, and both ends of the thread of the through hole should be chamfered.
(2) The position of the casting clamp should be correct, and try to make the center line of the threaded hole in a horizontal or vertical position, so that it is easy to determine whether the axis of the tap is perpendicular to the plane of the workpiece.
(3) At the beginning of drilling, try to position the tap as much as possible, then apply pressure to the tap and turn the twister. When cutting 1-2 turns, carefully check and correct the position of the tap. Generally, when cutting 3-4 turns of thread, the tap position should be correct. In the future, only need to rotate the twister, and no pressure should be applied to the tap, otherwise the thread profile will be damaged.
(4) When drilling, every 1/2 to 1 turn of the twister should be turned, it should be reversed about 1/2 turn, so that the chips can be easily discharged after breaking, and it can reduce the phenomenon that the cutting edge makes the tap rolling due to sticky chips.
(5) When encountering a screw hole that cannot be tapped, it is necessary to withdraw the tap frequently to remove the chips in the hole.
(6) When using the next tap in the drilling process, first screw it into the tapped thread by hand. When it can no longer screw in, then use the twister to turn it. When the end taper is finished tapping and withdrawing, it is also necessary to avoid turning the wringer quickly. It is best to unscrew it by hand to ensure that the quality of the tapped thread is not affected.
(7) When machine tapping, the tap and the screw hole should maintain coaxiality.
(8) During machine tapping, the calibrated part of the tap should not be fully extended, otherwise the tapping will be disordered when the tap is withdrawn from the machine.
(9) The cutting speed during machine attack is 6-15 m/min for general steel; 5-10 m/min for quenched and tempered steel or harder steel; 2-7 m/min for stainless steel; 8 m/min for cast iron. -10 meters/min. For the same material, the smaller tap diameter takes a higher value, and the larger tap diameter takes a lower value.
Also known as “synchronous feed drilling”. The rigid drilling cycle synchronizes the spindle rotation and feed to match the needs of a specific thread pitch. Since the feed into the hole is synchronized, in theory, an integral tap clamp with any tension compression cannot be used.
However, the problem in this aspect in actual production is that the machine tool cannot accurately match the specific tap pitch being used. There is always a slight difference between the thread processed by the machine tool and the actual pitch of the tap. If an integral tap clamp is used, this difference has a decisive effect on the life of the tap and the quality of the thread, because additional axial force is applied to the tap.
If a tap clamp with tension compression floating is used, the life of the tap and the quality of the thread will be greatly improved, because these additional axial forces on the tap are eliminated. The problem with traditional tension compression tap clamps is that they can cause large changes in drilling depth. As the tap becomes blunt, the pressure required to activate the tap into the hole increases, and the compression stroke used in the tap driver before the tap begins to cut. The result is a shallower drilling depth.
One of the main advantages of rigid drilling is that the depth can be precisely controlled in blind hole machining. In order to accurately and consistently process the workpiece, it is necessary to use a tap holder with sufficient compensation to achieve a higher tap life without causing any changes in depth control.
Professional lubricants are also needed in drilling, which can effectively reduce the friction between the workpiece and the wire tap, reduce wear, and has a strong oil film to prevent scratches and wrinkles on the surface of the workpiece, which can effectively improve work quality and efficiency. At the same time, it suppresses temperature rise, reduces sintering and seizure, extends the service life of molds, protects tools, inhibits the generation of black sludge, and does not corrode the workpiece; the cooling effect is outstanding.
It is very important to choose a suitable lubricant in drilling. When cleaning is not required, use a self-cleaning drilling lubricant. For difficult-to-machine workpieces, pure oil drilling oil is required.