Industry information

The method of removing the drill that is broken in the hole in the mold processing

2021-08-24

The method of removing the drill that is broken in the hole in the mold processing:


Anyone who engages in machining knows that the drill bit will always encounter so many bit breaks when drilling, especially CNC machine drilling, which is particularly easy to break, and some of them are deep holes. This is a headache. But don’t be afraid. Here’s how to take out the broken drill bit for everyone!


1. Fill in some lubricating oil, use a sharp hairpin or a chopper to slowly tap the fracture surface in the opposite direction, and pour the iron from time to time (the most common method in the workshop, but it is too small for the threaded hole or the broken tap Long may be inappropriate, but you can try);

2. Weld a handle or hexagonal nut on the broken section of the tap, and then gently reverse it (this is a good method, but welding is a bit troublesome, or the same, it is not suitable for taps with smaller diameters); 

3 .Use special tools: broken tap extractor, the principle is that the workpiece and the tap are respectively connected to the positive and negative electrodes, and the electrolyte is filled in the middle, which causes the workpiece to discharge and corrode the tap, and then assist the needle-nose pliers to take out, which will cause little damage to the inner hole

4. Use a small hammer to slowly tap the top of the steel roller on the tap crack. The tap is relatively brittle, and finally it becomes slag. Or simpler, directly drill the threaded hole of the broken tap and re-enlarging and tapping (method Some savage, if the diameter of the tap is too small, it won't work, if the diameter is too large, it will be tiring to tap);
5. Weld the threaded hole where the broken tap is located, grind it flat, and drill again. Although it is difficult, you can drill in slowly (if the threaded hole can be changed position, when re-drilling and tapping, it is recommended to change To the original threaded hole);
6. Chisel a slot on the section of the broken tap, and use a screwdriver to reverse it (the slot is difficult to cut out, and it is even more difficult if the diameter of the tap is small);
7. Drill the threaded hole of the broken tap to a large size, and then inlay a wire thread insert or pin or something, then weld, grind, and re-drill and tap. It can be basically the same (this method is troublesome, but very practical. , The size of the tap does not matter);
8. Use electric pulse to knock out, EDM or wire cutting can be used, the hole can be reamed to add wire threaded sleeve (this method is simpler and more convenient, as for the coaxiality, don't consider it for the time being, unless your threaded hole is the same Axial degree directly affects the quality of equipment);
9. Make a simple tool and insert it into the space of the chip groove of the broken tap section at the same time, and carefully pull it out. For example, you can screw 2 nuts on the broken tap with a square tenon, and use steel wire (the number of threads is the same as the number of tap grooves. ) Insert the broken tap and the empty slot of the nut, and then use the hinge lever to pull the square tenon in the exit direction to take out the broken tap (the theme of this method is to connect the chip groove of the broken tap, using steel wire, preferably For the steel needle, make a wrench for taking broken wires. Of course, if such broken wires often occur in the workshop, it is better to make a tool wrench like this);
10. Nitric acid solution can corrode high-speed steel wire cones without scrapping the workpiece.
11. Anneal the tap with an acetylene flame or a blowtorch, and then use a drill to drill. At this time, the diameter of the drill should be smaller than the diameter of the bottom hole, and the hole should be aligned to the center to prevent the thread from being damaged. After the hole is drilled, it is drilled into a flat shape Or square punch and use a wrench to unscrew the tap
12. Use a pneumatic drill to reverse the extraction, depending on the feel, because the tap is not drilled directly, but with a slow speed and a little friction (similar to a car half-clutch) to make the tap turn out.
13. You can use a grinder to grind down the broken wire, and then use a small drill to drill first, and then gradually switch to a larger drill. The broken wire will gradually fall off. After falling off, use the original size tap to re-tap the tooth. The advantage can be without increasing the aperture.

14. Weld an iron rod on the broken-in object, and then unscrew it. (Disadvantages: a. The cut-in is too small to be welded; b. It requires extremely high welding skills and is easy to burn out the workpiece; c. The welding place is easy to break, and the probability of taking out the broken-in is very small.) 

15. Use ratio A hard cone-shaped tool to pry the cut off. (Disadvantages: a. Only suitable for brittle broken objects, break the broken objects into pieces, and then slowly remove them; b. The broken objects are too deep or too small to be taken out; c. The original hole is easy to damage.)

16. Make a hexagonal electrode smaller than the diameter of the broken-in object, use an EDM machine to machine a hexagonal counterbore on the broken-in object, and then use an Allen wrench to unscrew it. (Disadvantages: a. Useless for rusty or stuck interrupted objects; b. Useless for large workpieces; c. Useless for too small interrupted objects; d. Time-consuming and troublesome.)
17. Directly use an electrode smaller than the cut-in object, and use an EDM machine to beat it. (Disadvantages: a. Useless for large workpieces and cannot be put into the EDM machine table; b. Time-consuming; c. When it is too deep, it is easy to deposit carbon and cannot be hit.)
18. Use alloy drills to drill (disadvantages: a, easy to destroy the original hole; b, useless for hard broken objects; c, alloy drills are more brittle and easy to break.)
19. Now there is a portable machine tool designed and manufactured by the principle of electrical machining, which can easily and quickly take out the broken screw and broken tap drill bit.
20. If the screw is not too hard, you can flatten the end face, find the center point, punch a small point up with a sample, drill first with a smaller bit, be vertical, and then use the broken wire extractor to reverse screw Just out.
21. If you can't buy a broken wire extractor, use a larger drill bit to continue reaming. When the hole diameter is close to the screw, some of the wire will fall off. Remove the remaining wires, and then use a tap to refinish it.
22. If the broken thread of the screw is exposed, or the requirements for the broken screw are not strict, and the hand saw can be sawed, you can saw the slit, even the shell, and then remove it with a flat-blade screwdriver.
23. If the broken wire is exposed to a certain length on the outside, and the melting point of the mechanical material is not too low, an extended T-shaped rod can be welded on the screw by electric welding, so that it can be easily unscrewed from the welded rod.
24. If the rust of the screw is very serious and it is not easy to deal with it by the above method, it is recommended to add a little lubricating oil after roasting it red, and then use the above corresponding method to deal with it.
25. After much effort, although the screw is taken out, the hole is also useless at this time. Simply drill a larger hole and tap it. If the original screw position and size are limited, you can also drill a larger one. Screw in, or directly weld and tap, and then drill a small hole in the center of the big screw to tap. However, the internal metal structure problem after welding is sometimes difficult to tap.