a. Hot push forming
The forming process of a hot pushed 90 degree elbow is the process of using a dedicated elbow pushing machine, core mold, and heating device to move the billet on the mold forward under the push of the pushing machine, which is heated, expanded, and bent into shape during the movement.
The deformation characteristics of hot pushed elbows are determined based on the law of unchanged volume before and after plastic deformation of metal materials. The diameter of the pipe blank used is smaller than the diameter of the elbow. The deformation process of the blank is controlled by the core mold, which makes the compressed metal flow at the inner arc and compensates for the thinning of other parts due to expansion, thus achieving uniform wall thickness
Bend.
The hot extrusion forming process of seamless 90 degree elbows has the characteristics of uniform wall thickness, beautiful appearance, and continuous operation, which is suitable for large-scale production. Therefore, it has become the main forming method for carbon steel and alloy steel elbows, and is also applied in the forming of certain specifications of stainless steel elbows. The heating methods for the forming process include medium frequency or high-frequency induction heating
(Heating coils can be multiple or single coils), flame heating, and reflection furnace heating. The choice of heating method depends on the demand and power condition of the formed product.
b. Stamping forming
Stamping 90 degree elbow is a forming process used for mass production of seamless elbows. At present, in the production of ordinary specification elbows, they have been replaced by hot pressing or other forming processes. But some specifications have a small production volume, and the wall thickness is too thick or too thin. Products with special requirements are still in use. The stamping technology for forming elbows can
Using a pipe blank equal to the outer diameter of the elbow, and using a press to directly press it into shape in the mold. The schematic diagram of stamping a 90 degree elbow is shown in the figure. Before stamping, the pipe blank is placed on the lower mold, and the inner core and end mold are loaded into the pipe blank. The upper mold moves downward to start pressing, and the elbow is constrained by the outer mold and supported by the inner mold
