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The prevailing stainless steel data, mainly because of its environmental reasons.The internal thread of stainless steel pipe fitting is usually finished with tap.Due to the high viscosity of stainless steel and poor chip breaking performance, it is easy for chip to scratch the workpiece thread in the process of tapping.For stainless steel joint internal thread tapping processing points have what extension tap service life, standard steel pipe stainless steel progress thread processing quality, should pay attention to the following points.
1. Design and manufacture of tap
(1) select better tap material.The wear resistance and toughness of the tap can be significantly improved by using special alloy elements in ordinary high speed tool steels.
(2) coating of titanium nitride on the surface of tap thread can significantly improve the grinding resistance, heat resistance and smoothness of tap.
(3) properly add the big tap front Angle of suzhou stainless steel hydraulic joint.However, it should be noted that if the front Angle of the tap is too large, it is easy to form a broken edge of the tap and tap out of the thread multi-edge.
(4) appropriately increase the amount of tap backhoe.However, it should be noted that, if the amount of shovel back is too large, the full model stainless steel joint is easy to produce chips into the tap back Angle phenomenon, and tapping thread brightness is not good.
(5) reasonable selection of tool thermal treatment method, standard nylon pipe to balance the hardness and toughness of tap.
Stainless steel parts
Stainless steel parts
2. Pre-jjn-r of the bottom hole of the workpiece
(1) should be in line with the criterion of tapping processing capacity as small as possible, at the bottom of the pre machining away L size, especially the NPT threads and British standard American standard F, R thread, its taper is 1:16, whereas most stainless steel factory is according to the small end of the thread diameter cast straight hole as tapping away at the end of L, the tapping of the local processing capacity is larger, easy to bad provoked the following results:
Tapping torque is large, tap easy to break or break edge;
(2) tapping out of the thread brightness is poor;
(3) tapping out of the cylindrical thread ningbo pipe joint with plug gauge detection diameter is small, the reason is not the diameter of the thread is not different, but because of chip scratch thread, there is burr.
(2) the size of bottom hole is equal to the size of the threaded path plus the allowance of 0.10.2MM.
(3) the custom reamer shall be used for machining the drill hole before tapping.With respect to American standard NF, R threads and English standard F, R threads, they should be machined into taper hole hole L.At present, many enterprises adopt waste tap to make reamer by manual whoring, so that waste tap can be used twice.However, there are two problems to be noted in the reamer restructuring:
(1) grinding thread must be grinding out the back Angle;
The front corner face of the tap edge should be straight.
3. Reasonable use of tap
(1) different chip trends should be considered when processing different types of workpiece.When necessary, the new tap also needs to be polished. The grinding line is to discharge the chip groove when tapping as far as possible to avoid scratching the processed thread.Machining collar (SPU): the most common tapping process of the collar is vertical tapping machine (or three tapping machine).The grinding method of tap is as follows:
(1) lengthen the leading part of the tap, so that the tap gradually into the cutting, in order to improve the service life of the tap;
(2) grind the obliquity of the blade on each blade lobe of the tap, but the initial grinding should not be too long (about 34MM), and it can be gradually lengthened later.The criterion to judge the grinding quality of the edge Angle is that the chip is discharged from the end face of the collar in the shape of a horn when tapping, without damaging the tapped thread.When the tapping is stopped for a period of time, if the thread is found to be of poor quality, the dip Angle can be further extended.