Medium frequency induction heating machine heating bending technology and equipment

Medium-frequency induction heating for local heating of bent pipes is one of the advanced process methods in small bending radius pipe bending processing. Based on the plasticity theory and structural static conditions, this paper conducts a study on the deformation and stress state of medium-frequency induction heating for local heating of bent pipes. Through systematic theoretical analysis, a mechanical model was established to calculate the deflection angle of the bending neutral layer, the axial thrust and shear force in the plastic deformation zone, and the shearing rate of the outer wall thickness of the bend during the bending process under different relative bending radii. and inner wall thickness thickening rate, etc., revealing the influence of each parameter on the quality of bent pipes, and this theoretical model is used to optimize the bending process and equipment parameters of medium frequency heating induction local heating bending pipes, which provides a theoretical basis for the bending processing theory of medium frequency machines. Improvement and process optimization have made a certain contribution. The optimized equipment parameters are the distance between the rear roller and the front roller; the distance between the front roller and the center line of the plastic deformation zone; the middle narrow diameter of the roller; the inclination angle of the roller; relative bending radius. The optimization program is programmed in MATLAB language.

The intermediate frequency machine pipe bending is to put the intermediate frequency induction coil on the steel billet, rely on the intermediate frequency induction current to locally heat the steel billet to the required high temperature, then bend the heated part, and spray water to cool it immediately after bending, so as to obtain the required bending pipe fittings.

Medium frequency pipe bending requires special equipment of medium frequency induction electric heating pipe bending machine. According to the different methods of bending moment applied by the pipe bending machine, it is divided into two types: pull bending type and push bending type. The medium frequency induction heating pipe bending machine is a commonly used hot pipe bending equipment, which can realize the continuous pipe bending process of heating, bending and cooling. This type of pipe bending machine consists of mechanical and electrical parts. The mechanical part includes the clamping and force-applying parts of the bent pipe, and the electrical part includes the motor and the intermediate frequency generating device. According to the different methods of bending the pipe, the pipe bending machine is divided into two types: push bending type and pull bending type. The push-bending medium frequency induction heating pipe bending machine works by applying thrust to the steel billet in the axial direction, heating, bending, and cooling by spraying water to complete the pipe bending process.

The medium frequency pipe bending machine has the following characteristics:

1. When cold bending large diameters and thick walls, a huge cold bending machine is required, which occupies a large area, is high in cost, and requires expensive molds. However, after medium frequency heating, the bending does not require a mold, and only needs to be configured according to different pipe diameters. Just the induction loop.

2. The medium frequency induction heating machine heats quickly, has high thermal efficiency, and does not produce oxide scale on the curved surface.

3. The forming quality of the bent pipe is good, the ovality and wall thickness reduction are smaller than that of cold bending, the bending radius is easy to adjust, and the adaptability is strong. It is especially suitable for bending single or small batches of large-diameter pipe fittings. Since no mold is required, the manufacturing cost is low.