Cold extrusion forming of the hottest internal thr

2022-08-08
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Cold extrusion forming of internal thread

cold extrusion forming technology of internal thread has been applied in processing workshops for a long time. However, in recent years, with the optimization design of tap geometry and the continuous progress of coating technology, this chip free processing technology has been applicable to a wider range of workpiece materials. For example, the innoform cold extrusion forming tap series developed by emuge Corp. has 30 combinations of geometric shapes and coatings, which can be applied to the processing of seven categories of workpiece materials. It is said that this is the first round of national defense and military reform of cold extrusion forming taps developed for a variety of different workpiece material categories

unlike using slotted taps for thread cutting, cold extrusion Taps do not produce chips, but form thread shapes by transferring materials. The section shape of this tap is polygon, on which there is a forming wedge exactly the same as the thread contour. The guide cone of the tap produces the thread contour, so that the workpiece material gradually flows from the top of the thread along the side of the thread to the small diameter part. This material flow forms a thin layer with claw like characteristics at the top of the thread. Because the workpiece material is compressed, and its texture only changes the direction without being cut or interrupted, the strength of the side and root of the thread is improved

innoform cold extrusion forming tap

cold extrusion forming tapping is very suitable for processing workpiece materials with tensile strength less than 1200n/mm2 and fracture strain of 5%. Experience has shown that if the workpiece material can produce continuous chips during drilling, it is likely to be suitable for cold extrusion forming taps to process threads. However, even for materials suitable for processing, their requirements for cold extrusion forming tapping are different, which is why for different workpiece materials (such as standard steel, mild steel, hard steel, stainless steel, cast aluminum, malleable aluminum alloy, other non-ferrous metals and materials with limited plasticity), innoform taps need to adopt specific geometric shapes and coating combinations. The coatings used for taps include tin, TiCN and diamond-like amorphous carbon (DLC) coatings. For some materials (such as malleable aluminum), antifriction lubrication coating can also be used to prevent the workpiece material from adhering to the tap

since severe friction will occur during cold extrusion, it is recommended to use cutting oil or emulsion coolant during machining. Minimum lubrication (MQL) can also be used in some processes. Some types of innoform taps are designed with cooling channels in the tool, which is conducive to blind hole tapping. Other innoform thread users must regularly clean the cone, and there are longitudinal oil grooves at the outlet of the inner cooling channel to improve the tapping speed and thread quality

the supply dimensions of emock cold extrusion Taps include metric coarse thread din13 (M3-M16) and fine thread din13 (mf8 × 1-MF16 × 1.5); UNC and UNF inch thread taps are also available. No matter the size of the thread, the accuracy of the pre hole diameter is very important for the correct forming of the thread. If the hole diameter is too small, the workpiece material at the root of the thread will be over formed, resulting in excessive processing force; If the hole diameter is too large, the root of the thread cannot be fully formed, and the small diameter of the thread will be smaller. In order to determine the best drill size, cutting tests must be carried out on the customized drill diameter. (end)

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