There are several types of tantalum pipe, such as extruded pipe, rolled pipe, drawn pipe, spinning pipe and welded pipe.
The production methods of tantalum tube blanks mainly include extrusion, sheet spinning and strip welding. The finished tantalum tube production methods mainly include rolling, stretching and spinning.
Tantalum tubes are usually cold rolled, including two-roller & multi-roller processing.
The main characteristics of the two-roller cold rail pipe are: large pass deformation, up to 90%: good stress state, not only used for rolling high plastic metal pipes, but also suitable for rolling low plastic metal pipes; can produce diameter Thin wall pipe with wall thickness ratio (D/S) of 6010; The products produced have high mechanical properties, good surface quality and precise geometric dimensions. Its disadvantages are: complex equipment structure, large investment and low productivity.
The main features of the multi-roller cold-rolled pipe are: due to the use of more than three small-diameter rolls, the metal pressure on the rolls is relatively reduced, and the elastic deformation of the rolls and the core rod is small, so it can produce high-precision thin-walled pipes with large diameters . (D/S ratio can reach 150-250); Due to the uniform deformation, the surface of the produced pipe is smooth and of good quality.
Stretching is also one of the main methods for producing finished tantalum pipes. There are several basic methods for pipe stretching.
-Empty drawing: No core is placed inside the tube blank during drawing. Suitable for small diameter pipes, shaped pipes, coils and heat treated or thermally processed pipes.
-Long mandrel stretching. A long mandrel is inserted into the tube blank. During the process, the mandrel needs to be replaced and materials need to be annealed several times. The process is complicated and has been rarely used in general production.
-Fixed core stretching. When stretching, the core rod with the core head is fixed, and the tube blank is reduced in diameter and wall through the die hole.
-Flowing core stretching. When stretching, the force balance established by the unique shape of the core head stabilizes it in the deformation zone. This method is a more advanced method for pipe drawing, which is very suitable for the production of long tubes and coils.
-Pipe jacking method. The core rod is sleeved into a tube blank with a bottom, and the tube blank is ejected from the die hole together with the core rod during operation, so that the outer diameter and inner diameter of the tube blank are processed. This is often used when producing large diameter tubes.
-Expansion. After the pipe blank passes through the diameter expansion, the diameter increases, and the wall thickness and length decrease. This method is mainly used when the required large-diameter tube blank cannot be produced due to the limitation of the capacity of the tube blank production equipment.
The tube blank is the same as the for Rolling and Stretching process. During the stretching process, in order to prevent the pulled metal and the mold from adhering to each other, the surface of the tube blank should be covered with a special oxide film before stretching, and then a common lubricant is applied on it.