Wuxi Wondery Industry Equipment Co., Ltd

I. Project Background and Equipment Application Positioning This case study involves a ladle heating station used for preheating ladle linings after repair and before receiving molten metal. The core function of the equipment is to provide smooth and controllable heating of the lining prior to casting, in order to stabilize the casting temperature regime, reduce metal loss, and ensure process repeatability. The operating environment is an industrial workshop, requiring stable operation across multiple heating cycles. The station is designed to accommodate a conical ladle with a 1-ton molten steel capacity. The ladle has an internal top diameter of 500 mm, internal bottom diameter of 410 mm, and depth of 900 mm; the external top diameter is 770 mm, and the overall height is 1,050 mm. These dimensions establish the geometric boundary conditions for heating element arrangement and station structural design – the conical inner cavity means the radial spacing of heating elements varies along the height direction, precluding the conventional arrangement used for equal-diameter cylindrical furnace chambers. II. Heating System Technical Parameter Requirements The equipment requires electric heating with a total installed power of no less than 30 kW. Heating elements are resistance type, required to withstand high-temperature long-term operation and cyclic thermal loading. The maximum heating temperature must be no less than 800°C, and the heating element temperature must exceed the lining working temperature to ensure sufficient heat transfer intensity without localized overheating. There are inherent constraints among these parameters: an 800°C lining target temperature means the heating element surface temperature must be maintained at a higher level to establish an effective radiative heat transfer differential. If the element surface load is set too high, heat transfer intensity increases but element life under cyclic thermal loading is shortened; if set too low, heating time is extended. Therefore, element material selection and surface load design constitute the core technical trade-off of this project. III. Temperature Uniformity and Control Accuracy Requirements The technical requirements specify two temperature indicators: system temperature stability control accuracy of at least ±10°C, and internal ladle temperature differential not exceeding 50°C. Uniform heating of the ladle inner surface is required along the full height, meaning the type and arrangement position of heating elements must be specifically selected in conjunction with the conical ladle geometry to minimize temperature gradients. The design challenge presented by the conical structure is that the lower section has a smaller diameter while the upper section has a larger diameter. If vertically suspended straight rod elements were used, the spacing between the lower section and the lining would be greater than at the upper section, resulting in insufficient radiative heat transfer intensity at the bottom. Therefore, elements may require segmented arrangement or non-standard geometry to compensate for this geometric difference. The control system must be capable of operating automatically according to a given heating curve, and also allow manual control of main parameters. Temperature control is achieved through real-time thermocouple monitoring, with real-time parameters displayed on the operation panel. Lining heating must be smooth and controllable, eliminating abrupt temperature changes – this requirement points to a heating rate limitation function, meaning the control system requires slope control capability rather than simple on-off temperature regulation. IV. Structural and Safety Design Requirements The heating unit must be insertable into the ladle interior and lockable in the working position. Heating elements must have protective structures to prevent mechanical damage and contact with the lining, such as heat-resistant steel protective mesh or protective sleeves. This requirement stems from actual operating conditions: during ladle lifting and positioning, positional deviation exists, and without protection, elements could be damaged by collision with the lining or ladle wall. Cable routing and connection points must be constructed from high-temperature-resistant materials suitable for high-temperature operation. The equipment structure must facilitate maintenance, allowing heating element replacement without complete disassembly – an important availability indicator, since heating elements are periodic consumables and replacement convenience directly affects equipment downtime. Safety requirements include short circuit, overload, and leakage protection devices, as well as emergency stop, over-temperature protection, and abnormal condition interlock protection functions. Hazardous areas must have structural guards to prevent accidental personnel entry. The equipment must be grounded per code, with no accessible live parts under normal operating conditions. Protection scope covers three risk categories: electric current injury, high-temperature injury, and injury from moving and rotating equipment parts. V. Environmental Adaptability and Power Supply Conditions The equipment is powered by AC 380V, 50Hz. The operating environment temperature range is +5°C to +40°C. The equipment structure must be resistant to dust, vibration, and other factors typical of metallurgical production conditions. This environmental requirement imposes constraints on the protection rating and cooling method of the electrical control cabinet – the dust and vibration environment of a metallurgical workshop is unsuitable for conventional open cooling structures. VI. Scope of Supply and Documentation Requirements The scope of supply includes the complete heating station, comprising heating elements, control cabinet, temperature measurement system, and connecting cables. Supply completeness must ensure the equipment can be directly commissioned without additional procurement of major components. Technical documentation includes operation manual, electrical schematic diagrams, general assembly drawings, and installation instructions, sufficient to ensure safe operation and maintenance of the equipment. VII. Service Life and Technical Support Requirements The warranty period is no less than 12 months from the date of commissioning. During the warranty period, faults and defects attributable to the manufacturer shall be rectified by the supplier. Under compliant operating conditions, equipment service life is no less than 5 years. The equipment must reach the set heating temperature within a reasonable process time agreed with the customer, and ensure parameter stability across multiple heating cycles for repeatable process operation. The control system must have high reliability and resistance to industrial interference. Technical support scope includes operational technical consultation, melting mode setup recommendations, and technical assistance under emergency conditions

I. Project Background and Equipment Specifications This case study involves a vertical aluminum alloy rapid quenching furnace with an effective work zone of 1200×1200×1100 mm (diameter × height). It is a cycle-operated resistance heating furnace primarily used for solution treatment and rapid quenching of aluminum alloy castings and plates. The equipment has a rated power of 135 kW, rated voltage of 380V three-phase 50Hz, and a rated temperature of 650°C with adjustable operating temperature. The structural positioning of this equipment differs from conventional box-type quenching furnaces: workpieces are suspended within the furnace, and the quenching tank is located directly below the furnace body. After the furnace door opens, the workpiece can fall directly into the water – this vertical layout is the physical basis for achieving rapid transfer. II. Temperature Control and Zoning Design The temperature control system employs a two-tier architecture. The upper tier is a 10-inch touch screen responsible for centralized setting, control, monitoring, recording, and storage of heat treatment process curves. The lower tier uses Eurotherm 3504 industrial PID temperature controllers with a control accuracy of ±1°C and furnace temperature uniformity of within ±3°C during the holding stage. The heating zones are configured as 2 zones connected in star configuration. Each zone is equipped with an over-temperature alarm device, program completion indication, audible and visual over-temperature alarm, and automatic current cut-off. The temperature controller features an online self-tuning function that calculates optimal PID parameters based on the actual thermal characteristics of the furnace, balancing heating rate against overshoot. III. Furnace Lining and Heating Element Configuration The furnace lining uses standard refractory fiber cotton, with both walls and roof constructed as all-fiber structures with a total insulation thickness of no less than 240 mm. The fiber folded blocks undergo secondary pre-compression before installation, reaching a compressed density of no less than 230 kg/m³, and are secured to the furnace roof shell with stainless steel round bars. This structure offers low thermal conductivity, low heat capacity, good thermal stability, and thermal shock resistance. Fixing components are stamped from 1Cr18Ni9Ti stainless steel sheet. The heating elements are 0Cr25Al5 alloy resistance strips, pressed with dedicated molds to avoid processing damage. The resistance strips are fixed with special ceramic screws, allowing convenient and rapid maintenance and replacement. During installation, ceramic washers are placed between the fiber wall and the resistance strip to prevent direct contact between the fiber surface and the strip, thereby enhancing heat dissipation from the strip. Both ceramic screws and washers are made of high-alumina material and sintered at high temperatures to ensure sufficient strength and service life. The resistance strips are suspended around the furnace chamber, facilitating heat dissipation and airflow circulation. The heating elements use a star connection, with surface load controlled below 1.6 W/cm² – a value below the conventional design limit for resistance strips, intended to extend element service life under frequent heating and cooling cycles. IV. Hot Air Circulation and Air Guiding System A high-temperature-resistant circulating fan rated at 7.5 kW is installed on the furnace roof. The fan material is designed to withstand prolonged high temperatures without deformation, with air-cooled bearings to accommodate the high-temperature roof environment. The air guiding hood maximizes the longitudinal component of the centrifugal force generated by the fan, pressing hot air downward. The air then bypasses the workpiece and is drawn back into the fan intake from the bottom, forming a closed circulation loop. This airflow path ensures temperature field uniformity within the furnace chamber and is a supporting design for the suspension loading method – workpieces have no obstruction around them, allowing airflow to pass through. V. Material Basket Lifting and Furnace Door Interlock Mechanism The material basket lifting mechanism consists of an electric winch, ring lifting chain, and pulley blocks. The winch is a dual-speed electrically controlled unit with a rope speed of up to 18 meters per minute, meeting the requirement for rapid descent into water; the ascent phase uses slow speed to reduce inertial impact when the workpiece and basket enter the furnace. The winch features inching control and a self-locking device, allowing it to stop at any position. Considering the high-temperature furnace environment, a 16Mn ring chain is used. The pulley system is installed on the upper part of the furnace body, consisting of 4 pulleys and 4 sets of bearings, ensuring smooth basket lifting and lowering. The furnace door is located at the bottom of the furnace body and moves laterally, with guide rails on the side to maintain horizontal movement. Door opening and closing is driven by a cylinder. When closing, the cylinder pushes the door to the closed position and continues to apply pressure, lifting the door upward via a lever mechanism on the side to press it tightly against the furnace body. The lifting mechanism and furnace door mechanism are interlocked: the lifting mechanism can only be powered and operated after the furnace door is fully open (at which point the heating element power has been cut off). This interlock logic prevents equipment damage from misoperation when the door is not open. VI. Quenching Transfer Time and Quenching Tank The quenching transfer time is defined as the time from furnace door opening to full immersion of the workpiece in water, with a design requirement of no more than 10 seconds. This parameter is critical to the aluminum alloy solution treatment process – the shorter the transfer time, the higher the cooling rate through the quench-sensitive range, and the better the aging strengthening effect. The quenching tank is of mobile construction, driven by a 2.2 kW motor. Two 3 kW circulation pumps are installed in the tank to continuously agitate the water during quenching, maintaining uniform water temperature and accelerating heat transfer from the workpiece surface. The tank is welded from 5 mm thick steel plate and tested for leak-tightness. The mobile cart is welded from 12# channel steel, with the front section serving as the material frame worktable area and the rear section as the water tank, with three sets of wheels (one set being drive wheels). VII. Process Action Sequence The complete equipment action sequence is as follows: manual loading → quenching cart moves to below the furnace body → furnace door opens → material frame lifting mechanism descends → manual hooking → material frame rises → furnace door closes → heating and holding according to process time → solution treatment ends → stirring water pump starts → furnace door opens → material frame descends → material frame rapidly enters water for quenching → material frame rises → quenching cart exits → material frame descends → manual unhooking followed by return to furnace opening → furnace door closes → manual unloading → next cycle begins.

I. Project Background and Equipment Specifications This case study involves a medium frequency induction melting furnace, model WDL-KGPS-500, with a rated capacity of 0.5 tons and a maximum capacity of 0.6 tons, designed for aluminum melting applications. The equipment employs medium frequency induction heating and is equipped with a hydraulic tilting system for molten aluminum discharge. The most notable configuration feature of this equipment is its grid compatibility scheme: the power supply side is fed at 440V/3P/60Hz, while the medium frequency power supply input voltage is specified at 380V. This means the equipment is intended for 60Hz grid regions (such as South Korea, parts of Central and South America, and the Middle East), requiring a transformer or voltage adaptation unit either inside or external to the power supply cabinet to step down the 440V grid voltage to 380V before feeding the medium frequency power supply. This dual adaptation of both voltage and frequency is a parameter that must be confirmed upfront during the electrical design phase for export projects. II. KGPS Medium Frequency Power Supply System The power supply system adopts the KGPS thyristor-based medium frequency power supply, with a rated power of 400 kW, a medium frequency output voltage of 2400 volts, and an output frequency of 1000 Hz. The power factor exceeds 0.9, and the startup success rate is 100%. The rectifier section is a three-phase full-controlled bridge with a three-phase six-pulse rectifier structure and a parallel-connected inverter. The control circuit employs an eighth-generation digital circuit board architecture, featuring wide frequency range adaptability, constant power control, swept-frequency zero-pressure soft start, and dual closed-loop voltage-current feedback. The swept-frequency zero-pressure startup means the system automatically scans frequencies during startup, establishing medium frequency oscillation upon finding the load resonant point – avoiding the sensitivity to load parameter variations inherent in separate-excitation startup methods. The protection system encompasses overcurrent, overvoltage, undercurrent, undervoltage, water loss, and phase-loss conditions. When any protection parameter exceeds the set threshold, the system automatically blocks pulse output and disconnects the main circuit power. The power supply cabinet panel includes full voltage, current, and power readings along with operating status indicators. The capacitor cabinet provides medium frequency parallel compensation, reducing reactive power transmission losses on the distribution lines. The capacitor bank capacity is matched to the resonant frequency of the induction coil, ensuring operation near the resonant point under rated conditions. III. Induction Coil Design and Magnetic Yoke Shielding The induction coil is the core energy conversion component, constructed from T2/TU1 copper with a wall thickness of 4 mm. When energized, the coil generates a 1000 Hz alternating magnetic field that induces eddy currents in the metal charge within the furnace hearth, generating heat. The coil design is based on electromagnetic field principles and verified through dedicated computer software, with the deviation between actual operating power and design power controlled within 5%. Turn-to-turn insulation is processed using advanced insulation techniques, with dedicated clamping technology reducing axial vibration of the coil. The coil inner wall is sprayed with imported high-temperature-resistant insulating materials, and a furnace lining leakage alarm system is installed – when molten aluminum seeps into the coil layer, the system detects it early and signals the condition, preventing furnace breakout incidents. A refractory coating of 10 to 15 mm thickness is applied to the inner surface of the coil, serving both to facilitate furnace lining construction and to prevent thermal deformation of the lining. The magnetic yokes are of crescent profile construction, laminated from cold-rolled silicon steel sheets and clamped with stainless steel splints. The contact surface between the yoke and the coil outer surface is curved, providing face contact rather than line contact, achieving better clamping efficiency and reduced magnetic flux leakage. The silicon steel sheets are reinforced with dedicated splints rather than through-bolts, maximizing the effective magnetic area and reducing localized heating. The magnetic yokes simultaneously shield magnetic flux leakage, prevent furnace body heating, and support and secure the induction coil. IV. Hydraulic Tilting System Furnace tilting is driven by a hydraulic system with two cylinders arranged on both sides of the furnace body for lifting, with furnace return accomplished by gravity. The hydraulic station is equipped with dual motors and dual pumps – one in service and one on standby, with automatic switching capability. The fuel tank is fully enclosed and welded to prevent hydraulic oil leakage. The tilting angle range is 0 to 95 degrees, with smooth operation without shock or creeping, adjustable speed, and the ability to hold at any position. Tilt operation is controlled via manual valves, suitable for casting processes requiring precise control of molten aluminum pouring volume. V. Crucible Mold and Lining Formation A configuration detail of this equipment is that it supplies a crucible mold rather than a finished graphite crucible. The crucible mold is formed from 3 mm iron plate and is used to control the shape and volume positioning of the refractory lining during formation. The user must select the lining material and ramming/sintering method according to the specific metal being melted and the casting process – a difference at the user operation level compared to solutions that directly supply finished graphite crucibles. The positioning function of the crucible mold ensures dimensional consistency of the lining cavity, thereby maintaining the coupling distance between the furnace hearth and the induction coil stable within the design range. VI. Water Cooling System and Cooling Cables The water-cooled cables are constructed from TU1 multi-strand oxygen-free copper wire, sheathed in high-strength fire-resistant rubber tubing, with cold-formed connectors ensuring contact resistance and tensile strength. The power supply side requires a cooling water flow rate of no less than 8 m³/h, while the furnace body side requires no less than 12 m³/h. The outlet water temperature on the power supply side must not exceed 35°C, and on the furnace body side must not exceed 45°C, with inlet water pressure maintained between 0.15 and 0.35 MPa. The water cooling system employs a fully enclosed circulating cooling method using soft water as the circulating medium. The core advantage of soft water circulation lies in avoiding overheating damage to the power supply, thyristors, capacitors, IGBT modules, and induction coil caused by scale deposition; additionally, soft water contains no ionic conductive components, so cooling components will not be damaged by electrolysis. The system requires no water pool or cooling tower, occupies minimal floor space, and has low makeup water consumption. The cooling system consists of three parts: main machine, water tank, and control box. The main machine includes the housing, copper cooler, exhaust system, spray system, water separator, collecting annulus, and spray pump. The water tank includes the main pump (one in service, one standby), stainless steel water tank, electrical cabinet, temperature control system, and pressure control system. The control box enables remote operation of the water cooling system, displaying water temperature and allowing setup of delayed operation after work hours.