Titanium alloy materials are difficult to process materials, have poor thermal conductivity, are easy to adhere to tools, have strong notch sensitivity, and will produce strong work hardening during the rolling process. In actual production, there are a series of problems in the rolling of full profile.
First, after the full profile squeezes the gap between the two rolling wheels during rolling, if the rolling wheels continue to roll, the blank material has nowhere to flow and can only be squeezed back and forth between the rolling wheels. As a result, the thread has a higher surface hardening. F5 Titanium Forging the hardening exceeds the tensile limit of the material, cracks will occur. As shown in Figure 1, the thread flanks and tooth bottom harden the most, so cracks occur;
Second, during full extrusion, each tooth of the rolling wheel involved in rolling is also affected by a strong cyclic load. The energy of rolling also acts on the rolling wheel, causing its life to be seriously reduced. In production, each pair of thread rolling wheels can only roll 3000-5000 titanium bolts, resulting in the phenomenon of tooth crest fragmentation, and the thread rolling wheels can no longer be used, which is extremely expensive. In addition, the thread rolling wheel tooth crest is broken Titanium Grade 2 Round Bar is a forming process in the production, so that the producer cannot determine the eligibility of the rolled thread, that is, when the rolled thread is qualified and when the rolled thread is unqualified;
Third, in the process of rolling and forming the thread, the two sides rise the fastest. When the thread is full, a fold will be formed on the crest. During the inspection, there are fluorescent display marks on the crest of the thread. In order to determine the maximum defect depth, anatomy is required. The method can only determine whether the defect at this place exceeds the standard; fourth, modern fasteners have high fatigue life, and have high precision requirements for bolt holes, and no hole wall damage is allowed during the installation process. The sharper thread crest is very easy to damage the hole wall. In short, the full thread profile brings great trouble to production, which not only increases the chance of cracks, reduces the fatigue life of parts, but also reduces the service life of the rolling wheel. In addition, it brings unnecessary trouble to the inspection. It is easy to cause damage to the hole wall, so it is imperative to correct the major diameter of the titanium tube grade 9 alloy fastener thread.
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