Rolling thread
Before rolling the thread, it is necessary to turn the part to be rolled to the middle diameter of the thread.
In rolling, the thread is formed by the pressure of the wire plate (rolling die). The advantage of the thread formed by the rolling process is that the plastic metal fiber flow line of the thread part is not cut, so the bolt strength is increased, the precision is high, and the quality is uniform, so the rolling process 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 accuracy of the thread, whether the material is coated or not. For example, if the thread is to be hot-dip galvanized, it is necessary to consider the effect of surface treatment on the final size of the thread during thread processing. It is necessary to advance the rolling thread.
Rolling (rubbing) screw thread refers to a processing method that uses plastic deformation to shape the thread teeth. It uses a rolling (thread rolling plate) mold with the same pitch and tooth shape as the thread to be processed. While squeezing the cylindrical screw blank, the screw blank is rotated, and finally the tooth shape on the rolling mold is transferred to On the screw blank, the thread is formed.
Rolling (rubbing) pressing thread processing has a common point is that the number of rolling revolutions need not be too much, if too much, the efficiency is low. The surface of the thread teeth is prone to separation or buckling. Conversely, if the number of revolutions is too small, the diameter of the thread is likely to be rounded, and the initial pressure during rolling is abnormally increased, resulting in a shortened die life.
Common defects of rolling thread: cracks or scratches on the surface of the thread, random buckling, and roundness of the thread. If these defects occur in large numbers, they will be found in the processing stage. If the number of occurrences is small, these defects will be circulated to the user and cause troubles during the production process. Therefore, it is necessary to summarize the key issues of processing conditions and control these key factors in the production process.
Surface treatment
There are many materials used to produce bolts, such as carbon steel, alloy steel and stainless steel. But the most commonly used and most economical material is carbon steel. Carbon steel itself has no anti-corrosion ability, so it needs to be properly treated on its surface to meet the requirements of anti-corrosion.
Different surface treatment methods have different anti-corrosion levels, and the characteristics of anti-corrosion coatings are also different, and the use temperature of different coatings is also different.
