Related Issues of Using Car Bottom Furnace in Forging Process

Related Issues of Using Car Bottom Furnace in Forging Process

I. Compatibility of Basic Parameters of Car Bottom Furnaces with Forging Needs

In forging production, whether the basic parameters of a car bottom furnace match the forging needs directly affects the smooth progress of production. The rated temperature of a car bottom furnace must be highly compatible with the temperature range required by the forging process. For example, for common medium carbon steel forging, the heating temperature is typically within 1100 - 1250°C. If the rated temperature of the car bottom furnace cannot reach this interval, it will result in insufficient heating of metal billets, poor plasticity, difficulty in shaping during forging, and prone to defects such as cracks; conversely, if the rated temperature is too high, it not only wastes energy but also may cause overheating or even burning of the billet, seriously affecting the quality of forging.

The size of the furnace chamber of a car bottom furnace is crucial for carrying capacity regarding the size and batch of forged workpieces. If large shaft-like workpieces need to be forged, a furnace chamber that is too small cannot accommodate the workpiece, making the production plan unexecutable. For batch production of small forgings, if the furnace chamber is too large, the space utilization rate inside the furnace is low, heat loss during heating is severe, the heating speed slows down, which not only increases energy consumption but also reduces production efficiency. Therefore, based on the maximum external dimensions of the workpiece and the expected production batch, it is necessary to precisely select a car bottom furnace with an appropriate furnace chamber size.

The heating rate of a car bottom furnace also cannot be ignored, as it must meet the preheating time requirements of forging. A fast heating rate can reduce the heating time of the billet in the furnace, lower the risk of oxidation and decarburization, while improving production efficiency. If the heating rate is too slow, the billet remains in the low-temperature section for a long time, increasing the generation of scale, not only affecting the surface quality of the workpiece but also causing metal loss. For example, some forging workshops with high demands for production efficiency may require the car bottom furnace to reach 800°C within 30 minutes to meet the demand for rapid preheating of billets entering the forging process.

II. Uniform Heating Problems of Car Bottom Furnaces

Temperature differences in different areas inside the furnace have a significant impact on the quality of forged workpieces. When there are large temperature differences within the furnace, the same batch of forged workpieces will experience uneven heating, resulting in variations in structure and performance. During the forging process, parts with higher temperatures have better metal fluidity and larger deformation; whereas parts with lower temperatures deform with difficulty, ultimately leading to uneven internal stress distribution, possible excessive local deformation causing cracks, or inconsistent overall mechanical properties, affecting the stability and pass rate of product quality.

The factors leading to uneven heating are relatively complex. Unreasonable layout of heating elements is a common reason. If heating elements are concentrated on one side of the furnace chamber, it inevitably results in higher temperatures on that side and lower temperatures on the other side. Additionally, poor airflow circulation exacerbates temperature non-uniformity. If airflow is obstructed by furnace structure or workpiece placement during circulation, it fails to evenly transfer heat to various areas, creating temperature dead zones. For instance, in some older car bottom furnaces, due to the lack of reasonably designed guide devices, hot air currents form local vortices inside the furnace, leading to significantly lower temperatures near the furnace door and corners compared to the center area of the furnace.

To improve uniform heating, a series of measures and methods can be adopted. Optimize the layout of heating elements using symmetrical distribution or zoning arrangements to ensure uniform heating across all parts of the furnace chamber. Simultaneously, install efficient airflow circulation devices, such as axial fans, and design guide plates rationally to direct airflow uniformly through every corner of the furnace chamber, enhancing heat transfer. Furthermore, regularly calibrate the car bottom furnace's temperature using multi-point temperature measuring instruments to monitor temperatures at different positions inside the furnace, adjusting the power of heating elements or airflow circulation parameters according to measurement results to ensure uniformity of furnace temperatures within reasonable ranges.

 III. Temperature Control Precision of Car Bottom Furnaces

Conventional car bottom furnaces generally achieve a temperature control precision range of ±5 - ±15°C during forging, but for certain precise forging processes requiring extremely high temperatures, this precision may fall short. For example, specific alloys used in aerospace applications may require temperature control precision within ±2°C to avoid affecting the alloy's microstructure and mechanical properties, thereby impacting the reliability and safety of aircraft components.

Key factors influencing temperature control precision include the sensitivity of the temperature control system, sensor accuracy, insulation performance of the furnace body, and response speed of heating elements. To enhance temperature control precision, advanced PID control algorithms, high-precision temperature sensors, and improved insulation materials can be utilized. Automated monitoring systems can also be introduced to further ensure stable and reliable temperature control.

IV. Loading and Unloading Operations of Car Bottom Furnaces

Proper loading methods play an important role in heating efficiency and consistency of workpiece heating. Workpieces should be arranged following certain rules inside the car bottom furnace to avoid overcrowding or sparseness. Inappropriate loading can lead to inadequate heating and reduced heating efficiency or wasted furnace space and increased energy consumption. Suitable loading tools and safety training for operators are essential to prevent damage and accidents during unloading.

V. Energy Consumption and Energy Saving of Car Bottom Furnaces

Energy consumption of car bottom furnaces constitutes a significant portion of total forging production costs. Factors influencing energy consumption include insulation performance, operation duration, heating element efficiency, and operational practices. Various energy-saving technologies, including the use of new insulation materials, optimized heating element designs, and waste heat recovery systems, can effectively reduce energy consumption.

 VI. Maintenance and Fault Handling of Car Bottom Furnaces

Regular maintenance checks on critical components like seals, heating elements, and temperature control systems are vital for ensuring stable operation. Effective diagnostic methods and rapid repair strategies for common faults like damaged heating elements or malfunctioning temperature control systems help minimize downtime and maintain continuous forging production.

VII. Synergistic Optimization of Car Bottom Furnaces and Forging Processes

Adjusting operating parameters of car bottom furnaces based on the characteristics of forging processes can enhance forging quality and production efficiency. Continuous technological upgrades and improvements to car bottom furnaces are necessary to adapt to advancements in forging techniques like isothermal forging and precision forging, which demand higher standards for temperature uniformity, control precision, and insulation performance. Through synergistic optimization, both forging efficiency and quality can be significantly improved, bringing notable economic benefits and market competitiveness to forging enterprises.