The roller die drawing method can be used in the production of niobium-zirconium alloy wire

Roller die drawing technology is a new drawing technology which has developed rapidly and is more practical in recent years. The essence of roller die drawing is to change the sliding friction between material and die hole during the drawing of fixed die into the rolling friction of well-lubricated bearing, thus greatly reducing the drawing friction and thus greatly reducing the drawing friction. In the 1960 s the United States will roller die technology used in the production, is currently used in the production of copper, aluminum and its alloy, stainless steel and high temperature alloy, etc., and Germany also adopts the technology of the roller die drawing aluminum, copper alloy and difficult to deformation, the former Soviet union attaches great importance to technology of roller die drawing, the developed with automatic adjustment groove center roller die equipment, has also developed with support roller of roller die, at the same time increase the frame rigidity to improve the accuracy of the product. At present, the roll drawing technology has been successfully applied to the production of titanium and titanium alloy wire in China, but there is no data to show the application of roll drawing technology in niobium zirconium alloy wire production.

Niobium zirconium alloy wire material because of its high temperature resistance, corrosion resistance, good cold processing performance characteristics, especially because of its thermal expansion coefficient at high temperature and ceramic material similar, so it is particularly suitable for the manufacture of high-pressure sodium lamp parts.

Niobium and zirconium alloy has lower strength and good plasticity, generally USES the traditional fixed die cold drawing processing method, niobium, zirconium wire with fixed die drawing, must be conducted before drawing wire surface pretreatment, the so-called pretreatment, zirconium in niobium wire surface ancestors to form a layer of lubrication film materials, so as to ensure the normal of wire drawing, this is a chemical process. This is because the niobium and zirconium alloy has the high "sticky", such as preprocessing, the wire in the fixed mold drawing due to the material adhesion in the fixed mold surface sizing area, formed the so-called "sticky", serious when due to mold scraper wire break, not the normal drawing, so, if not for surface pretreatment, niobium, zirconium wire of the fixed mold drawing will not be performed, but there are also disadvantages with niobium zirconium wire surface pretreatment.

1. The process is long and complicated, and the production cycle is long.(1) The surface pretreatment requires a long time, is several times the drawing time, or even dozens of times, leading to a long production cycle;(2) after the surface pretreatment, but also in the processing material surface coated with special and expensive lubricant, even so, it is difficult to ensure that the pull-out will not "sticky mold", sometimes need to carry out repeated surface pretreatment can achieve the normal pull-out;(3) after the completion of the drawing process but also through acid washing process to remove the protective film. Therefore, the pretreatment process is the biggest factor affecting the production efficiency of niobium-zirconium wire.

2. Product quality is difficult to control.(1) The pretreatment process is the most difficult to control in the entire production process of niobium zirconium wire, the thickness of the protective film is difficult to control and difficult to evaluate, so the pretreatment process in the factory is a special process. If the control is not good, it will affect the product quality, and if serious, it will make the drawing process difficult to carry out or cause a large rejection rate;(2) in the subsequent pickling remove protective film operation, also easy to produce waste products due to improper pickling;(3) due to the finished product to pickling, so the product surface quality is poor; Surface pretreatment can easily cause niobium zirconium alloy pollution, resulting in a large number of unqualified products. Therefore, the pretreatment process is also an important factor affecting product quality.

3. Small trace extension coefficient and low production efficiency. This is because the protective film formed after pretreatment is hard and brittle, and the friction calorific value is very high during drawing. Even if a special and expensive lubricant is used, it cannot play a very good role, and only a low drawing speed can be used. The larger trace extension coefficient increases the damage degree of the protective film, which is easy to cause "sticky die", so that the drawing can not be carried out normally, so it limits the improvement of trace processing rate.

4. Low product yield. After the drawing, the protective film must be removed by pickling, thus reducing the yield and total recovery of the product. To sum up, in the production of niobium zirconium wire, the surface pretreatment process is the "bottleneck" that affects the product quality and production efficiency. In order to improve the product quality and production efficiency of niobium and zirconium wire, it is necessary to remove the surface pretreatment process. The roller die drawing is an effective method to remove the surface pretreatment.