| Requirements for comprehensive mechanical properties of elbows for elbow machining
The elbow produced by the push bending machine is made by the mandrel extrusion bending method. The push mechanism is as follows: A set of determining the length of the pipe, in turn, wear on the core shaft, start-up speed regulating motor, through the gear drive screw, to push plate along the screw forward movement, push board will be set on the core shaft tube rounds into the core shaft front horn-type mandrel, at the same time, medium frequency induction coil, sensors for billet heating, tube billet in the process of heated while moving forward, from the horn mandrel extrusion, Due to the action of pushing force and friction resistance, the tube billet is extruded to produce joint deformation of radial expansion and axial bending, so that the small diameter tube billet is pushed into a larger diameter elbow.
Medium frequency heating elbow mechanism is used to make elbow. In its forming process, the flow law of metal is: the inner metal of the elbow flows to both sides, and the outer metal does not participate in the deformation, but only part of the metal is redistributed.
Related requirements for elbow processing quality and comprehensive mechanical properties:
1. Bend machine series hot pushing elbow outer arc tensile plastic deformation is larger, the normal temperature, high temperature yield strength and tensile strength increases, plasticity and significantly lower back and toughness, so should make more reasonable production process, strict control of bend hole enlargement ratio, reducing elbow outer arc tensile plastic deformation, in order to obtain comprehensive mechanical properties.
2. The inner arc wall thickness of the hot push elbow made by elbow machine does not increase, and the inner arc happens to be the high stress area of the elbow. In order to ensure that the inner arc wall thickness of the elbow meets the standard requirements of the product, the tube billet with appropriately thickened wall thickness should be used for pushing.
3. Thermal push elbow in the forming process does not produce axial bending deformation, and radial expansion, so special attention should be paid to check whether the inner and outer wall of the elbow crack, micro crack and intergranular crack.
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