Production method of tantalum tube
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.
Rolled pipe
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.
Stretched tube
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.
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