How to solve the local melting problem of induction quenching parts

The surface melting of High frequency induction heating machine quenching parts is often a major defect that results in the scrap of workpiece, so it must be prevented to avoid its occurrence.

 

(1) If the gap between the inductor effective ring and the workpiece is too small, short-circuit and surface melting will occur in the heating process. The preventive measures are as follows:

 

1) The effective ring is coated with insulation and temperature resistant materials. Previously, the ceramic coating layer has been used, but now it is improved to spray alumina (Al2O3) or coated with other high temperature resistant materials, such as glass fiber sleeve, high silicon oxygen ribbon, etc.

 

2) Insulate the heating workpiece from the effective ring. If the workpiece is positioned at the top of the insulated sleeve, the workpiece will not melt even if it touches the effective ring.

 

3) Enhance the rigidity of the effective ring, so as not to change the gap due to the action of electromagnetic force.

 

4) Install clearance positioning block, such as the crankshaft inductor designed with spacing positioning block, to ensure that the effective ring and the workpiece will not contact, positioning block is best with temperature resistance, shock resistance, rapid cooling materials.

 

5) Install grounding fault cut-out.Modern induction quenching machine has been equipped with grounding fault circuit breaker safety device, when the workpiece and effective ring touch, can automatically disconnect within 16ms.

 

(2) Casting defects casting defects (such as shrinkage, porosity, inclusions, etc.) often cause local concentration of inductive power, resulting in workpiece melting.When induction heating, the use of low power density, can reduce the melting.

 

(3) Improve the workpiece design to avoid edge, sharp Angle, hole position and uneven thickness, so as to avoid the concentration of local eddy.

 

(4) Improve the effective ring design, such as local amplification gap, local installation of back guide magnet, shielding plate, etc.