স্বয়ংচালিত ইঞ্জিন ব্লকের কাস্টিংয়ে ইন্ডাকশন ফার্নেসের স্থিতিশীলতা নিয়ন্ত্রণ

মোটরগাড়ি শিল্পে, ইঞ্জিন ব্লকের ঢালাই (সাধারণত HT250/GJL-250 বা HT300/GJL-300 grade Grey Cast Iron) represents a “high-precision” sector. Facing the high-speed demands of automated molding lines (such as DISAMATIC or HWS), দ্য core conflict lies in how to eliminate the fluctuations caused by the “intermittent melting” nature of induction furnaces and provide a supply of molten iron that is as “continuous and stable” as that of a Blast Furnace or Cupola.

আমি. Extreme Consistency Control of Composition and Temperature

In mass production, minute differences in each batch of molten iron can lead to uneven hardness, machining difficulties, or shrinkage porosity in castings. The key to control is transforming “variables” মধ্যে “constants.”

1. Refined Charge Management (উৎস নিয়ন্ত্রণ)

Induction furnaces operate on the principle of “garbage in, garbage out” and lack the metallurgical reaction capabilities of cupolas. অতএব, charge management is the cornerstone of stability.

• Cleanliness Control: Automotive castings are sensitive to gas porosity. Oil, moisture, and rust on Steel Scrap must be strictly controlled. For Bales, density and internal inclusions must be monitored.
• Batching নির্ভুলতা: Automatic batching systems must be used to ensure the ratio errors of Pig Iron, Returns, and Steel Scrap are controlled within ± 1%.
• Trace Element Tracking: Grey iron is extremely sensitive to trace elements (যেমন, এর, পবি, আল). A supplier archive for trace elements must be established to avoid accumulation effects that degrade graphite morphology.

2. “Heel Melting” and Process Discipline

To maintain consistency across continuous batches, the furnace must never be fully emptied.

• Heel Melting Operation: Always maintain 30%~50% liquid iron (the heel) in the furnace.
  • ফাংশন: Shortens the melting time for the next batch and, more importantly, uses the old molten iron as a Buffer to significantly dilute the compositional fluctuations of the new charge.
• Full Power & Rapid Heating: If grey iron stays in the high-temperature zone too long, the nucleation cores (Nuclei) will dissolve/fade, leading to an increased chill tendency. The strategy is: Melt with high power, tap immediately upon reaching temperature, and strictly prohibit holding the iron for long periods.

3. Closed-Loop Temperature Control

• Target নির্ভুলতা: The pouring temperature window is usually extremely narrow (যেমন, 1420°C ± 10°C).
• Tap Temperature Compensation: Considering the temperature drop in the transfer ladle (typically 30–50°C), the furnace tapping temperature must be adjusted via a dynamic compensation algorithm based on transfer distance and ladle status (Cold Ladle vs. Hot Ladle).

Ii. Configuration Schemes for Automated Molding Lines: Duplexing & Multi-systems

Automated molding lines (such as vertical parting lines) are characterized by continuous and high-speed iron consumption (যেমন, 300-500 molds/hour). A single induction furnace cannot simultaneously satisfy the demands of Melting (Batch process) and Pouring (Continuous process).

1. Core Concept: Decoupling Melting and Holding

Separating the “গলে যাওয়া” function from the “Supplying” function is key to achieving a continuous flow.

2. Typical Configuration Schemes

ক. “One-to-Two” বা “Multi-supply-One” Duplexing

This is the most mainstream high-efficiency configuration.

• Mode: Multiple high-power Mains or Medium Frequency Melting Furnaces + 1 large capacity Holding/Pouring Furnace.
• Workflow:
  • Melting furnace melts at full speed and adjusts composition.
  • Iron is tapped into a transfer ladle.
  • Iron is poured into the large holding furnace (যেমন, ক 10-20 ton Channel Induction Furnace or Pressurized Pouring Furnace).
• সুবিধা:
  • Homogenization: The holding furnace acts as a massive “mixing pool.” Even if there are slight Carbon/Silicon fluctuations between melting batches, they are leveled out upon entering the large pool, outputting extremely stable iron.
  • Buffer: During melting furnace maintenance or charging, the holding furnace inventory allows the molding line to continue production for 20-30 মিনিট.

খ. Butterfly Configuration

Suitable for ultra-large-scale production.

• Layout: 2-3 Melting furnaces arranged around a rotating intermediate transfer device or automated charging car.
• Power Distribution: ব্যবহার করে “Dual-Power” বা “Tri-Power” systems (যেমন, one power supply unit feeding two furnace bodies). One melts at full power while the other holds or sinters, achieving seamless switching with minimal power grid fluctuation.

3. Integration of Automated Pouring

At the end of the induction furnace duplexing scheme, an Automatic Pouring Machine (যেমন, Pressure or Bottom-pour type) অপরিহার্য:

• Stream Inoculation: The auto-pourer is equipped with a precise stream inoculation device to ensure consistent inoculant dosage per mold (error < 2%), which is critical for the graphite morphology of grey iron.
• Visual Positioning: Utilizes laser vision systems to automatically adjust flow rate based on the pouring cup liquid level, keeping the pouring cycle perfectly synchronized with the molding line.

Iii. Key Process Control Techniques

To guarantee the stability of the systems mentioned above, the following monitoring methods must be introduced:

সংক্ষিপ্তসার

For automotive engine block casting, “স্থিতিশীলতা” is not just a technical indicator; it is an economic one.

By utilizing a configuration of “Multi-furnace Melting + বড় ক্ষমতা Holding/Homogenization + Automatic Pouring,” combined with strict “Heel Melting” এবং “Precise Inoculation” প্রক্রিয়া, the discreteness of single-batch melting can be eliminated. This satisfies the rigorous requirements of automated production lines for “Zero Defect, Continuous Flow” molten iron.