Bogie Hearth Electric Resistance Furnace

1. Electric Furnace Application fields

   This Bogie Hearth Electric Resistance Furnace is mainly used for carbon steel, alloy steel parts heating, annealing, normalizing, quenching, and tempering: surface hardening, tempering: welding stress relief annealing, and another heat-treatment process. 

2. Main technical data of the car-type electric furnace

3. Electric furnace structure

  Bogie hearth electric resistance furnace is mainly composed of heating furnace body, trolley and trolley traction mechanism, furnace door and door lifting and pressing device, heating element and fixing device, electric temperature control system, and other parts.

3.1. Heating furnace body

  The bogie hearth electric resistance furnace body frame is made of channel steel and Angle steel welding, the shell side plate is made of Q235,3mm steel plate welding, the furnace panel is made of 14mm plate, the structure is firm and reliable, the overall strength is good, not easy to deformation, the appearance is smooth and clean.

  Bogie hearth electric resistance furnace lining is full fiber structure, the total thickness of furnace lining fiber is 300mm, using temperature resistant 1460℃ zirconium fiber, after compression volume weight ≥230Kg/m3; Using the scientific and reasonable mounting method, this structure has few thermal bridge short circuit phenomenon, and it is made by combining the two ways of the flat stack. It has the advantages of good air tightness, firm and reliability, convenient maintenance, long service life, good energy-saving effect, lightweight furnace body, the small temperature rise of the furnace body shell, etc. This can effectively prevent the loosening of the furnace lining body, improve the furnace lining thermal insulation performance, save energy, reduce the production and operation cost.

  The bogie hearth electric resistance furnace body and trolley are sealed by trolley brick and furnace body fiber soft seal, sealing effect is good, and easy to operate. The other side of the car also adds a sand groove seal.

  All welding places of furnace body shall be polished, scraped flat with iron putty and sprayed with thermal anti-rust paint, and then painted according to the color standard provided by the user.

3.2. Trolley and trolley traction mechanism

  Trolley consists of frame, bogie hearth electric resistance furnace lining, trolley traction mechanism, and so on.

  The bogie hearth electric resistance furnace frame is made of channel steel and an I-steel frame, the side plate and bottom plate are welded with Q235, 10mm steel plate, the trolley structure is firm and reliable, not easy to deformation and warping, the overall strength is good.

  The heat insulation layer at the bottom of the trolley furnace lining is made of diatomite brick and light straight brick, and the middle of which is made of straight brick. The refractory layer is made of heavy brick. When the refractory layer is built, the high-temperature binder is added into the mud to improve the structural strength. The trolley is built with special-shaped brick around it so that the furnace gas does not directly contact the side plate of the trolley. The refractory layer of the trolley is built into a groove where the heating element is placed, and used for the bottom plate of the furnace.

  The material ZG40Cr25Ni20SiN high-temperature furnace bottom plate is paved above the trolley furnace lining for the use of the workpiece. The new form of the buckle is adopted to prevent the workpiece oxide skin from falling on the heating element and forming a short circuit. The heat-resistant steel furnace bottom plate is made in pieces to reduce deformation and cracking at high temperatures.

  The trolley walking mechanism adopts a wheel-type self-propelled way, running wheels are installed below the trolley body. The headbox of the trolley is provided with a cycloid reducer, through the sprocket and chain, the walking power is transferred to the trolley’s active walking wheel to drive the trolley to move. And equipped with a brake device, to ensure the trolley stop accurately and timely, to prevent the trolley from hitting the furnace body due to inertia.

  Double insurance limit switches are set at both ends of the trolley travel limit to avoid damage to the furnace body and accidents caused by exceeding the travel limit.

  The power supply of the heating element on the trolley is connected by the plug knife installed at the tail of the trolley and the socket at the tail of the furnace shell. The contact is good and there is no electric spark and overheating.

3.3 . Furnace door and door lifting and pressing device

  The furnace door frame is made of channel steel, side plate and bottom plate are welded with Q235 steel plate, the structure is firm and reliable, not easy to deformation and warping, the overall strength is good.

Furnace door lining is also a full fiber structure.

  Furnace door and furnace body sealing, in the upper part of the furnace door frame, are installed with two sets of door lift pulley groups. In addition, four furnace door guide walking wheels are installed at the top and bottom four corners of the furnace door frame plate, and the walking wheels walk along the furnace door track. When the door drops to close the door, the car-type electric furnace door guide walking wheel moves along with the pressing inclined plate in the door track. In the process of pressing the inclined plate line by the door, the partial force generated by its own gravity makes the lining fiber on the door contact closely with the heat-resistant cast iron guide plate on the end face of the furnace body, so as to realize the soft closure of the door and the furnace body. In this scheme, there is no counterweight iron in the door lifting system, which is to make full use of the pressure component produced by the weight of the door itself, so that the sealing effect of the door and the car-type electric furnace body is better.

3.4. Heating elements and fixtures

  The heating element distributes power reasonably according to the uniformity of furnace temperature, and the heating element is arranged on the left and right side wall, furnace door, back wall, and five surfaces on the platform. The heating element is made of corrugated HRE alloy resistance tape.

  The left and right side walls, furnace door, and rear walls are hung on the fiber lining with new-type porcelain screws. The heating elements on the trolley are laid in the groove of refractory brick masonry and fixed with the shaped hook. The surface load of the heating elements is smaller than that of other parts. The new type of porcelain screw suspension will not produce a short circuit phenomenon, replacement and maintenance are more convenient.

3.5. Electric temperature control system

  Adopt a standard control cabinet. The control cabinet of the main control system adopts the international popular GGD vertical 2000×1000×800 combined cabinet. The main circuit of temperature control adopts the Ximandon solid power regulator, which is air-cooled and equipped with functions of overload, overheating, and overcurrent protection. This adjustment function is divided into automatic and manual mode, which can form an automatic temperature control process with a temperature control meter automatically. Manually and temperature controller meter offline, manually adjust the power. It has the function of limiting heating power in automatic or manual mode. Temperature control instrument adopts advanced Japanese Island electric high precision digital display PID self-tuning programmable instrument and touch screen control, with multi-range input, arbitrary temperature setting, a variety of alarm functions. Temperature signal through the thermocouple to receive millivolt signal after amplification operation and conversion, digital display instrument output 4-20mA current signal, control accuracy ±1℃. The temperature control is equipped with a thermocouple correction function, power limit function, and overtemperature alarm function. Temperature record using disc paper recorder to record temperature curve. When the furnace door is opened, the main heating circuit is automatically cut off to realize interlocking protection. The instrument has the advantages of high precision temperature control, stable furnace temperature, and small temperature fluctuation.

  The electric control cabinet is designed with a voltage and current indication meter, and each phase of each zone is designed with a heating indicator light so that the operator can observe whether the heating work in each zone is normal. When the heating slows down, it is conducive to troubleshooting and solving the fault.

  In addition to the heating circuit to provide over-temperature phase break over-current short circuit protection, the furnace door electric lift, trolley access to adopt reliable action chain protection. The loading process has the following chain protection: the furnace door cannot be lowered until the trolley is fully in the furnace, and the heating element power can only be connected after the furnace door is closed. The material discharging process has the following chain protection: the furnace door is opened, and the heating element power supply is cut off at the same time. Only after the car-type electric furnace door is opened to the highest position can the trolley be opened.

4. Automation software for industrial centralized monitoring Introduction

  The bogie hearth electric resistance furnace software uses MCGS state configuration menu and interface, the program function is complete, clear structure, strong independence, occupies little system resources, better ensure the real-time and reliability of data.

5. Product sales and service commitment

  More contact with users, communicate with each other, to ensure that the design and manufacture of products meet user requirements. 

  Site installation and cold and hot state debugging, to ensure the normal use of products. 

  Responsible for providing free on-site training on the theory, maintenance, and operation skills of technical, maintenance, and operation personnel, so that users can use the products correctly and skillfully. The training time is carried out in the bogie hearth electric resistance furnace debugging and trial operation stage. 

  After the final acceptance of the bogie hearth electric resistance furnace, the warranty period is 12 months, during the warranty period, due to design, production, material, and other reasons caused by the damage, by the supplier free replacement and repair.  For the damage outside the warranty period, the supplier will provide preferential service and the supply of wearing parts (only charge the cost), and provide lifelong after-sales service.