1, hot forming
Hot push bend forming technology is to use special elbow push system core machine,
mold and heating device, to set on the mold of billet in pushing forward movement, under the impetus
of the machine in motion is heated and hole enlargement and forming process. Hot push bend
deformation characteristics are based on volume before and after plastic deformation rule of metal materials determine the pipe diameter, pipe diameter bend
diameter, through the core module and control the deformation of the process, make the inner arc compressed
metal flow, the compensation to other parts of the thinned by hole diameter, wall thickness uniform Angle is obtained. Hot push bend forming technology has a good appearance, uniform wall thickness and continuous operation,
suitable for the characteristics of mass production, thus become the main forming methods of carbon steel,
alloy steel elbow, and also the application in some of the specifications of the stainless steel elbow forming. Forming process of the heating mode with intermediate frequency or high frequency induction heating
(heating can be multiple times or lap), flame heating and reverberatory furnace heating, adopt what kind of
heating mode according to the condition of forming product requirements and energy.
Stamping elbow is first applied to the forming process of the mass production of seamless elbow, at present,
the commonly used in the production of the specifications of the elbow has been replaced by a hot method or
other forming process, but in some of the specifications of the elbow because of less production quantity and
wall thickness too thick or too thin. When the products have special requirements are still in use. Elbow stamping elbow is used to outer diameter
of the same tube billet, use press press forming directly in the mold. Stamping elbow forming diagram as shown in figure
Before stamping, the tube billet is put on a mold, the mold filling and end into the pipe, the upper die downward
movement began to suppress, through external constraints and internal model of the supporting role of bend forming. Compared with the hot pushing process, the appearance of the stamping forming quality is better than the former;
Stamping elbow outer arc in the tensile state during forming, compensate, and no other parts excess metal so the
outer arc of wall thickness thinning is about 10% or so. But due to apply to the individual production and the
characteristics of low cost, so the stamping elbow process used in small batch, more thick wall elbow manufacture. Cold stamping and hot stamping stamping elbow points two kinds, usually according to the nature of materials
and equipment capacity selection of cold or hot stamping. Cold extrusion of bend forming process is the use of dedicated elbow forming machine, pipe to be included in
the external formwork, upper and lower mold clamping, under the impetus of the push rod, tube billet model
along the internal model and reserved clearance sports and forming process.
Figure 15-8 for a manufacturer of stainless steel elbow in extrusion pictures of before and after extrusion. Using die cold extrusion process inside and outside the elbow and good appearance, uniform wall thickness,
size deviation is small, so for the stainless steel elbow especially thin wall stainless steel elbow forming more
made by this technology. This new process used by internal and external mold precision demand is high;
For pipe wall thickness deviation is more demanding. 3, other methods of forming Except the forming process of the above three kinds of commonly used seamless pipe bend forming and
using the tube billet after extrusion to outside, and inside the tube billet passed ball plastic forming technology.
But this process is relatively complex, the operation of trouble, not equal to the process, and the forming quality
is less used.
Source: Zhejiang Yaang Pipe Industry Co., Limited (www.yaang.com)