Bolt threads are usually processed by cold, so that the thread blanks in a certain diameter range can be formed by rubbing (rolling) the screw plate (die), and by the pressure of the screw plate (rolling die). The plastic streamline of the threaded part can be obtained without cutting off, the strength is increased, the precision is high and the quality is uniform, so it is widely used. In order to produce the thread outer diameter of the final product, the required thread blank diameter is different, because it is limited by the thread accuracy, material coating and other factors. Rolling (rubbing) threading refers to the process of forming threaded teeth by plastic deformation. It uses a rolling die with the same thread pitch and conodont as the processed thread to extrude the cylindrical screw blank and rotate the screw blank at the same time. Finally, the conodont on the rolling die is transferred to the screw blank to form the bolt threads. The common point of rolling (rubbing) thread pressing is that the rolling speed does not need to be too much, if too much, the efficiency is low, and the surface of thread teeth is prone to separate or screw-up phenomenon. On the contrary, if the rotation is too small, the thread diameter is easy to lose circle, and the pressure increases abnormally at the initial rolling stage, which shortens the life of the die. Common defects of rolling threads: surface cracks or scratches on the part of threads; screw-ups; partial roundness of threads. If these defects occur in large numbers, they will be found in the processing stage. If the number of defects occurs less, the production process will not notice these defects will flow to users, causing trouble. Therefore, the key problems of processing conditions should be summarized, and these key factors should be controlled in the production process.
Heavy Hex Structural Bolt ASTM A325M Standard: ASME B 18.2.1, IFI149,DIN931, DIN933, DIN558, DIN960, DIN961, DIN558, ISO4014 and etc. Size: standard & non-standard, spport customized Material: Carbon Steel, Alloy Steel, Stainless Steel, Brass and etc. Grade: SAE J429 Gr.2, 5,8; ASTM A307Gr.A, Class 4.8, 5.8, 6.8, 8.8, 10.9, 12.9 and etc. Thread: UNC,UNF Finish: Plain, […]
Zinc Plated A325M Bolts Commodity: Top quality customized A325M hex bolt Material: Carbon Steel,Alloy steel, stainless steel and brass Standard: DIN931/933,DIN 6914,A325/A325M Grade: 4.8/6.8/8.8/10.9/12.9 Surface Finish: Black,Zinc plated,Copper plating,Phosphating,Mechanical galvanized Zinc Plated A325M Bolts Size: M6-M164; 1/4″-2″ Supply Ability: 500 MT per month Certificated: ISO9001:2008;ROHS,SGS and environment protection Packing: By carton or gunny bag then […]