Cooling shaping can guarantee the quality of stainless steel welded pipe and ensure the safety in use. Let's take a look at the cooling setting device of stainless steel welded pipe：
1. Shaping mouth shaping
In this method, the pipe is directly pushed out to form without traction device. The feature of the head structure is that the straight part of the mandrel is about 10-50 mm longer than that of the die. The screw thrust pushes the pipe out of the head and directly enters the cooling stainless steel welded pipe. The outer surface is cooled and hardened, and the inner surface is covered on the mandrel and can not shrink inward to form. The ejection method is generally smaller than the production of small diameter and thick wall pipe The key point is that the equipment investment is small and the operation is convenient, but this method has the advantages of slow discharging, low output, uneven wall thickness and low strength.
2. Internal pressure method
The setting device of types of pipe nipples is a method that uses compressed air inside the pipe and cooling setting sleeve outside the pipe to make the outer surface of UHMWPE pipe stick in the setting sleeve and quickly cool and harden the size of the fixed outer diameter. The stainless steel welded pipe is evenly led out by the traction device, and the setting sleeve is close to the head of the machine and keeps concentric with the die and mandrel.
In order to keep the pressure in the pipe unchanged, an air plug is installed in the pipe at a certain position away from the sizing machine to keep the pressure of compressed air in the pipe constant. The inner diameter of the set is generally larger than the outer diameter of the pipe, and the enlarged size can reduce the shrinkage of the pipe. The length of the set should ensure that the surface of the UHMWPE pipe is cooled to the glass transition temperature.
3. Vacuum method
It adopts the method of vacuumizing outside the pipe to make the outer surface of the stainless steel welded pipe adsorb on the inner wall of the setting sleeve to cool and fix the outer diameter. This method is especially suitable for the setting of the inner lining of the ultra-high molecular weight polyethylene (UHMWPE) pumping pipe.