How to expand the mouth of stainless steel round tube?

Expanding stainless steel round pipes is a common task, and in practical operation, many problems may be encountered. For example, the diameter and wall thickness of steel pipes are inconsistent, or circular pipes may have some defects after welding. To solve these problems, we need to expand our mouth. So, how is the stainless steel round tube expanded?

1、 Determine the expansion size

The expansion size of Stainless Steel Pipes varies depending on their specifications. If it is a stainless steel pipe with a diameter of 20 millimeters, its expanded outer diameter is+10 millimeters. In general, before expanding, the diameter and wall thickness of the expansion need to be determined according to specific production requirements, in order to ensure that the expansion meets the specifications after expansion.

2、 Adjust the mold properly

The expansion work of stainless steel round pipes requires adjusting the mold first to ensure that there is no bending during the expansion process. Adjust the outer and inner diameters to match the outer and inner diameters of the expansion mold, and then fix the mold on the expansion machine.
 
(1). After selecting the expansion mold, the first step is to measure the outer and inner diameters. Then determine the size of the expansion mold based on the measurement results.
 
(2). Determine the material required for expansion based on the thickness of the outer wall and inner diameter of the pipe, and then place the material into the stainless steel round pipe expansion mold. After fixing the expansion mold, fix it on the equipment. According to this method, stainless steel round pipes can be expanded.

3、 Preheat the mold

The expansion of pipes is mainly carried out by utilizing the pressure generated inside, so preheating is necessary during the expansion process. Firstly, place the welded pipe in a dedicated oven for drying, and then place it in the mold. Pay attention to the following points when preheating:
 
(1). Cannot be too high, because the higher the mold temperature, the higher its compressive strength.
 
(2). On the premise of ensuring the mold temperature, try to increase the preheating temperature as much as possible.
 
(3). Ensure that there are no debris on the mold.
 
(4). If the steel pipe is long, it can be heated in sections to prevent local overheating.

4、 Cooling of stainless steel round pipes

(1). Cool it down to a certain temperature. The cooling time depends on the stainless steel material and type. Under the same conditions, the shorter the cooling time, the faster the cooling rate.
 
(2). There are various cooling methods for welded pipes, such as water spray, compressed air or steam spray, etc. When using water spray, it is generally only cooled on the surface.
 
(3). Cooling it with compressed air is also a relatively simple method. Add a certain proportion of water to the compressed air, then turn on the pressure switch and spray the steel pipe into the air for cooling.