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Several Methods of Extruding Tubes Forward by Aluminium Extruder

November 20,2019

Through the center of the ingot blank and inserted into the die hole to form an annular shape, metal is forced to pass through the die hole by the pressure of the extrusion shaft to form a pipe, the inner diameter of which depends on the diameter of the piercing needle, while the outer diameter depends on the diameter of the extrusion die hole.

When producing pipes by forward extrusion, hollow ingots can be used for production or solid ingots can be used for piercing extrusion on aluminum extruders according to technological requirements. When the hollow ingot blank is used for extruding the pipe, a large amount of additional processing for drilling the ingot blank is added, and the inner surface of the ingot blank is oxidized during heating, thus easily causing defects on the inner surface of the extruded pipe. Therefore, it is uneconomical to produce pipes by this method. Generally, this method is only used when producing small-sized pipes.
Three-layer PVC Solid Wall Pipe Co-extrusion Production line
In modern extrusion technology, aluminum extruders with independent piercing devices are generally used to extrude pipes. When the pipe is produced by this method, some metal is pushed out by the piercing needle to become waste “radish head”. It is not economical to produce large diameter pipe. Therefore, other methods to reduce the loss of “radish head” are important means to improve the yield. For example, large tube heads with certain sizes can be re-extruded as ingots to produce products with small specifications as long as they can meet the requirements of other extrusion cylinder systems. In addition, a combined extrusion method can be adopted to reduce the loss of perforated material head and improve the yield.

When the aluminum extrusionmachineextrudes the pipe, there is a certain friction between the piercing needle and the metal ingot blank, which smoothes the uneven flow of metal in the extrusion process. Therefore, when extruding pipes, the tail is generally shorter. The main defects of extruded pipes are internal and external surface defects, such as: oxide pressure on internal and external surfaces of pipes, scratches, bubbles, peeling, uneven wall thickness (eccentricity) of pipes, etc. In order to prevent oxide scale from flowing into human products during extrusion, peeling extrusion method can also be adopted. Peeling extrusion is widely used for pipes in modern extrusion technology. For example, high-precision entangling copper tubes, various condensing tubes, waveguide tubes and other alloys.
Silicon Core Pipe Extrusion Line
In order to ensure that the extruded product does not generate high temperature oxidation after flowing out of the die hole, water seal extrusion technology, protective atmosphere extrusion method and the like can be adopted. One of the main quality problems in the horizontal extruder using piercing needles to extrude pipes is the eccentricity of the pipes. There are many factors that affect the eccentricity of extruded pipes, but they are mainly caused by extrusion equipment and tools. Ensuring the mechanical concentricity of aluminum extrusionmachineand the concentricity of extrusion tools (shaft, barrel and die holder) is the primary condition to obtain uniform wall thickness of extruded pipes. Specific solutions should also be based on the conditions of the equipment used and the experience accumulated in production practice.

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