The manufacturing process of tees aims to ensure structural strength and sealing through one-time integral forming. The main methods include stamping, specifically filler bulging, hydraulic bulging, and hot pressing.
The filler bulging process uses a straight tube blank internally filled with filler for bulging. The key step is placing the tube blank into the mold cavity and closing the mold, then using a punch to push from both sides, causing the tube blank and filler to be extruded through radial holes. The key technology of this process lies in the selection of the bulging medium filler, such as paraffin wax, grease, nylon, or polyurethane rubber. Its characteristics include uniform wall thickness in all directions, an extruded portion height of 2-3 times the pipe diameter, and no mechanical scratches on the inner wall.
Hydraulic bulging is a forming process that uses axial compensation of the metal material to bulge out a branch pipe. Its working principle is to use a hydraulic press to inject liquid, causing the tube blank to bulge under the combined action of side cylinder extrusion and liquid pressure. This process is suitable for low-carbon steel, low-alloy steel, stainless steel, and non-ferrous metals such as copper, aluminum, and titanium, which have low work hardening tendency.
Hot pressing involves flattening, perforating, heating, and pressing a pipe blank larger than the tee's diameter, then forming it through radial compression and branch pipe stretching. This process requires low-tonnage equipment and is suitable for tees with large diameters and thick walls, using materials such as low-carbon steel, alloy steel, and stainless steel.
Advances in manufacturing processes are also reflected in optimized structural designs. For example, the patent application (publication number CN121474432A) for "Partially Reinforced Thin-Walled Tee Fittings" by Zhongcai Pipeline achieves a compact structure and flexible installation by placing an arc-shaped connecting strip between the first and second inclined reinforcing strips and placing the reinforcing structure within a snap-fit ring groove. This reduces material usage while maintaining strength, saving on material manufacturing costs for mass production.
In specific applications, such as tees in automotive piping systems, the manufacturing process often utilizes seamless pipe processing. Common hydraulic bulging and hot pressing processes ensure the structural strength and sealing of the components, making them suitable for various transportation scenarios such as water, gas, natural gas, and oil.
