Taps in tapping process common problems include: 1, tap break, 2, tap collapse, 3, tap wear too fast, 4, thread diameter is too large, 5, thread diameter is too small, 6, thread surface roughness is too large.
Cause
Tap break: the threaded hole machining of smaller diameter of chip is not good due to clogging; of barrier threads, drilling depth is not enough; thread cutting speed is too high too fast; the diameter of thread with the tap and screw of different axis; tap grinding parameter choice appropriate processing the hardness is not stable; tap used for a long time, excessive wear.
Taps: the front angle of the taps is too large; the taps are too thick for each tooth; the taps are too hard to quench; the taps are too long to use and wear seriously.
Tap wear is too fast: when cutting thread, cutting speed is too high; tapping parameter selection is not suitable; cutting fluid is not selected properly, cutting fluid is not enough; workpiece material hardness is too high; when taps are sharpened, burn phenomenon occurs.
The diameter is too large: tap diameter precision grade improper selection is not reasonable; cutting; thread cutting speed is too high; the threaded hole coaxial with the difference of taps of the workpiece; improper grinding parameters tap; grinding burrs tap, tap cutting cone length too short.
The middle diameter of the thread is too small: the middle diameter of the taps is not properly selected; the selection of the grinding parameters of the taps is not reasonable, the taps are worn, and the choice of the cutting fluid is not suitable.
The thread surface roughness is too large: the selection of grinding parameters of taps is not suitable; the hardness of workpieces is too low, the quality of tapping is not good, the cutting fluid selection is unreasonable, the cutting speed is too high when tapping thread is used, the tap time is too long, and the wear is large.
Solutions
Tap break: the threaded hole diameter of the right to choose; grinding or cutting edge inclination with spiral fluted tap; drilling bottom hole depth to meet the prescribed standards; appropriate to reduce the cutting speed, according to the selection criteria; correction of tap and bottom tapping, ensure the coaxiality requirements, and selection of floating tapping chuck; increasing the tap the anterior horn, shorten the cutting cone length; ensure the workpiece hardness to meet the requirements, the insurance holder; found the tap wear should be replaced.
Taper avalanche: appropriately reduce the front angle of the taps; increase the length of the cutting cone properly; reduce the hardness and change the taps in time. Tap wear is too fast: reduce the cutting speed appropriately, reduce the tap angle, lengthen the length of the cutting cone, select the cutting fluid with good lubricity, heat the processed parts properly, and grind the tap correctly.
The diameter is too large: choose reasonable precision tap diameter; and reducing the cutting speed selection of cutting fluid for correction; taps and tapping thread when the coaxial degree of the floating chuck; reduce rake angle and cutting cone angle; burr grinding taps produced, and appropriately increase the cutting cone length.
The thread diameter is too small: choose the proper diameter of the tap, increase the tap angle and cutting cone angle appropriately, replace the worn taps, and select the cutting fluid with good lubricity.
The thread surface roughness value is too large: increase the tap rake angle, cutting angle; heat treatment, increase the hardness of the workpiece, which taps the rake face of low surface roughness value selection cutting lubricant good; reducing cutting speed; replacement of worn tap.
Because the tap is almost buried in cutting the workpiece, the processing load of each tooth is larger than the other tool, and contact with the workpiece surface along the screw tap is very large, cutting thread when it must accommodate and remove the chip, therefore, can be said to tap work in very harsh conditions. In order to make the tapping smoothly, the possible problems should be considered in advance. Such as the performance of the workpiece material, the choice of what kind of tool and machine tool, the selection of high cutting speed, feed and so on. First of all, five questions should be made before tapping: (1) what is the material to be processed? (2) what is the strength of the workpiece material?
(3) is the machined hole a through hole or a blind hole?
(4) what is the depth of the screw hole (or the thickness of the workpiece)? (5) what are the types and sizes of the screw holes to be processed?
The main difficulty in tapping on difficult material is that the heat produced during cutting and the shrinkage of the workpiece material are wrapped in the cutting tool. Titanium alloys are the most obvious in this field. When tapping on this material, the taps used should have a larger tooth profile and a taper to prevent the taps from working.
In addition, the strength of the taps is also important. Because of the high hardness and strength of the workpiece, it often makes the top of the taps quickly and blunted. In this case, high performance and high speed steel wire cones are recommended, which have high toughness, red hardness, resistance to deformation and wear resistance. When designing a taps for hard material, it is very important to adopt a small front angle, which can make the taps more difficult to cut.
Tapping is not only the difficult problem of the workpiece material. Sometimes, the technique of tapping is also complex and subtle. For example, the tapping of blind holes. In the blind hole tapping, in order to meet the requirements of the drawings, it is necessary to prepare the space for the taps to attack enough depth. It is necessary to drill a bit deeper into the hole. But if it is too deep to drill more than the cut to the next part, it will cause the problem of eccentricity. In addition, in the deep blind hole, the end section of its end will also gradually shift the center.
Suppose you need to attack a 5/16 "-18 thread blind hole, deep 1", and the material is 304 rust.
