Basic Principles and Applications of Zhengzhou Guoyun Induction Heating Surface Quenching
Zhengzhou Guoyun analyzes the application and basic principles of induction heating surface quenching.
1. Application of Zhengzhou Guoyun Induction Heating Equipment:
Workpieces subjected to torsional, bending, or alternating loads require that the surface layer withstand higher stress or wear than the core. Various shaft hardening processes are used for this purpose.
Quenching technology is widely applied in modern mechanical manufacturing industries. Important mechanical components, especially steel parts used in automobiles, airplanes, and rockets, almost all undergo quenching treatment. To meet various technical requirements, different quenching technologies have been developed. For example, according to the treated part, there are overall, partial, and surface quenching; according to whether phase transformation is complete during heating, there are complete quenching and incomplete quenching (for hypoeutectoid steels, this method is also called subcritical quenching); according to the content of phase transformation during cooling, there are分级quenching, isothermal quenching, and undercooling quenching, etc. Surface strengthening is required for workpieces, suitable for steels with carbon content We=0.40～0.50%.
2. Process Methods of Zhengzhou Guoyun Induction Heating Equipment:
Combining rapid heating with immediate quenching cooling. Through rapid heating, the surface of the steel piece reaches the quenching temperature before the heat is transferred to the center, and it is quickly cooled. Only the surface layer is hardened into martensite, while the center remains as the original ductile and tough annealed (or normalized and tempered) structure.
3. Main Methods of Zhengzhou Guoyun Induction Heating Equipment:
Induction heating surface quenching (high frequency, medium frequency, power frequency), flame heating surface quenching, electric contact heating surface quenching, electrolyte heating surface quenching, laser heating surface quenching, electron beam heating surface quenching.
4. Induction Heating Surface Quenching of Zhengzhou Guoyun Induction Heating Equipment:
(a) Basic Principle:
Place the workpiece inside an inductor made of hollow copper tubing. After passing medium or high-frequency alternating current through it, a corresponding frequency of induced current forms on the surface of the workpiece. The part's surface is rapidly heated (can reach 800-1000 degrees within a few seconds, while the core remains close to room temperature) and immediately water-cooled (or oil-quenched), hardening the surface layer into martensite. (As shown in the figure below)
(b) Selection of Guoyun Heating Frequency:
At room temperature, the depth (mm) to which the induced current flows into the workpiece surface has the following relationship with the current frequency f (HZ): As the frequency increases, the current penetration depth decreases, and so does the hardened layer depth.
Commonly used current frequencies include:
1. High-frequency heating: 100～500KHZ, commonly 200～300KHZ, using electronic tube high-frequency heating, hardened layer depth is 0.5～2.5mm, suitable for small and medium-sized parts.
2. Medium-frequency heating: Current frequency is 500～10000HZ, commonly 2500～8000HZ, power equipment includes mechanical medium-frequency heating devices or thyristor medium-frequency generators. Hardened layer depth ~10 mm, suitable for larger diameter shafts, medium-large gears, etc.
3. Power-frequency heating: Current frequency is 50HZ. Mechanical power-frequency heating power equipment is used, hardened layer depth can reach 10～20mm, suitable for surface quenching of large-diameter workpieces.
(c) Application of Guoyun Induction Heating Surface Quenching:
Compared with ordinary heating quenching, it has the following characteristics:
1. Extremely fast heating speed, can expand the A body transformation temperature range, shorten the transformation time.
2. After quenching, the workpiece surface can obtain extremely fine hidden crystal martensite, slightly higher hardness (2～3HRC). Lower brittleness and higher fatigue strength.
3. Workpieces processed by this process are less likely to oxidize or decarburize, and some can even be directly assembled and used after processing.
4. Deep hardened layer, easy to control operation, easy to mechanize and automate.
5. Flame Surface Heating Quenching:
Suitable for flame surface quenching of medium carbon steels such as 35, 45 steel, medium carbon alloy structural steels such as 40Cr and 65Mn, gray cast iron, and alloy cast iron. It uses flames from acetylene-oxygen or gas-oxygen mixed gas combustion to rapidly heat the workpiece. After the workpiece surface reaches the quenching temperature, it is immediately water-cooled. The hardened layer depth is 2～6mm, otherwise, it would cause serious overheating and deformation cracking of the workpiece surface.
High-frequency heating high-frequency quenching equipment
High-frequency high-frequency quenching equipment
Medium-frequency high-frequency quenching equipment
High-frequency heating high-frequency quenching equipment