Stainless Steel Pipe Fittings

Forming process of seamless pipe fittings (two)

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(2) seamless tee
Tee is a pipe for pipeline branch. For using seamless tube manufacturing tee is usually adopted by the process has two kinds of hydraulic bulging forming and hot pressing. The forming process of cross and tee are similar, so no longer.
A. hydraulic bulging
Three links of hydraulic bulging is through the metal materials of axial compensation bulge out branch pipe of a forming process. The process is to use special hydraulic press, with three links within the tube billet diameter equal injection liquid, through the two horizontal side of the hydraulic cylinder synchronization of the motion of tube billet, billet after squeezed smaller volume, smaller volume of liquid with the tube billet inside the tube billet and pressure, when pressure tee branch pipe bulge out to the metal material in the liquid in the cylinder and the pipe pressure under the dual role of flow along the mold cavity and the branch pipe. Hydraulic pressure forming of tee diagram as shown in figure.


Bulging start (a) (b) (c) in the bulging bulging over
Hydraulic bulging forming tee
Tee hydraulic bulging process can be a forming, high production efficiency; The 3-way head and shoulders wall thickness were increased.
For seamless tee hydraulic bulging process required equipment tonnage is larger, the current domestic is mainly used for less than the standard wall thickness of DN400 tee. Its applicable forming material for cold hardening tend to be relatively low low carbon steel, low alloy steel, stainless steel, including some non-ferrous metal materials, such as copper, aluminum, titanium, etc.
B. thermoforming
Tee hot-pressing forming is more than three links of the diameter of the tube billet, flattening diameter size, about to tee at the site of the tensile branch open a hole; Tube billet heating, in the forming die, and within the tube billet load stretching pipe punching die; Under the action of pressure pipe by radial compression, the radial compression in the process of metal flow in the direction of branch pipe and branch pipe formed under tensile of progressive die. The whole process of the pipe is made by the radial compression and branch pipe drawing process and forming parts. Unlike hydraulic bulge forming tee, hot-pressing tee branch pipe of metal is of the pipe by the radial motion compensation, so also known as the radial compensation technology. Hot pressing forming process of tee as shown below.
Due to adopt heating after pressing tee, material forming required equipment tonnage is reduced. Hot pressing tee with wider adaptability of material, is suitable for low carbon steel, alloy steel, stainless steel materials; Especially large diameter and wall thickness of tee, usually use this forming process.


(a) (b) formed before forming
Hot pressing forming tee
(3) seamless reducer
Reducer is used for pipe diameter changes in a pipe. Usually adopted for reducing the forming process of pressing, expanding to suppress or reducing and expanding, to certain specifications of the reducer and stamping can be applied.
A. reducing forming/hole enlargement
Reducer reducing forming technology is will be equal and reducer big end diameter of tube rounds into the forming mould, through along the axial direction of tube billet, shrink along the cavity movement and metal forming. According to the size of the reducer , divided into the one of pressing or more press forming. Below for reducing the forming of concentric reducer.


Concentric reducer reducing forming schematic diagram
Forming hole diameter is less than reducer big end diameter of the tube billet, used in die forming along the tube billet diameter hole enlargement. Hole enlargement technology mainly to solve the reducer in the variable diameter is larger not easily by reducing forming, sometimes according to the requirements of the materials and products forming, expanding and reducing method of combination.
In the process of reducing or expanding deformation, according to different materials and variable diameter, determination by cold pressing and hot pressing. Under normal circumstances, as far as possible by cold pressing, but the multiple variable diameter and cause serious work hardening of the thick or alloy steel, wall thickness of materials appropriate USES hot pressing.
B. stamping
In addition to the use of steel tube as raw material to produce reducer, the part of the specifications of the reducer can also be used steel plate stamping forming technology is adopted to improve the production. Drawing die shapes used by reference to reducing tube surface size design, use after blanking punching die, stamping steel stretch forming.
(4) cap
Pipe sealing cap is used in the pipe ends of a pipe. And used in pressure vessel head difference between the size of the cap and tube are suitable, general maximum 48 “); Pipe cap for the oval shape.
Pipe cap forming is relatively simple, usually adopts the stamping, the use of mould and die, in the shape of the die determines the shape of the tube cap, after cutting the steel plate after cold or hot forming.
Source: Zhejiang Yaang Pipe Industry Co., Limited (

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