The influence of heating temperature to elbow bending: heating the elbow by induction coil. The expansion and bending can be continuous if designing appropriate induction coil, suitable heating condition and pushing rate of pipe. When determining the heating temperature, it should be ensured that enough plasticity of the pipe when pushing. So the heating temperature should be higher than recrystallization of billet material. Combined with practical experience, heating temperature for carbon steel is 750-750 ℃. The ideal heating temperature is that the outlet temperature is higher, and the expansion temperature is lower.
The pushing rate of hydraulic elbow machine determines the forming quality. When pushing speed is higher than thermal deformation capability, the elbow will be cracked. But when pushing speed is lower than it, the elbow will be wrinkled.
The pushing rate is affected by the shape of horn mandrel, bending radius, the material, the uniformity of heating, specification and so on. Generally, the pushing speed is 90-120 mm/min.