4. Production Process Flow Loading→ Transfer the cylinder to the loading conveyor of Quenching Furnace by overhead crane→ Quenching Furnace Door Open→ Convey the cylinder into the Quenching Furnace rapidly → Heating cylinder inside of Quenching Furnace(Meanwhile, cylinders moves slowly to prevent the roller from distortion and increase the uniformity of heating)→ Middle Door (Heat Insulation) Open → Cylinders transferred rapidly to the Holding zone of Quenching Furnace(Meanwhile, cylinders moves slowly to prevent the roller from distortion and increase the uniformity of holding)→ After process time is completed → Unloading Door Open and the cylinders are unloaded quickly → Door Close, Cylinders are transferred to the Side Unloading Conveyor of Quenching Tank→ Transfer cylinders into the Quenching tank for Quenching. Meanwhile, the transfer car moves up and down, as to uniform the quenching media and ensure the quenching quality → Lift up cylinders with Transfer car → Convey cylinders to loading conveyor of Tempering Furnace → Tempering Furnace Door Open → Transfer into tempering furnace for heating(working sequence, Takt time, control mode are all same as quenching furnace)→ Tempering Furnace Door Open after the process time is reached → Unloading rapidly → Cylinders are transferred to Unloading conveyor, cooling down and waiting for unloading → One cycle is completed, Waiting.
5. Brief Equipment Introduction 5.1 Loading Conveyor It is mainly designed for loading and rapid convey of steel cylinder, which consist of supporting bracket, roller, driving device, and control device. Support Bracket: It is made of formed steel and steel plate and welded together, which provides a good appearance. Anchor plate is welded to the bottom of supporting bracket, which is fixed onto the embedded plate of foundation, as to ensure the reliability and safety. Roller Conveyor: It is made of 20# seamless steel tube (φ159×6mm). Positioning device is equipped with the roller to prevent the offset of steel cylinder and falling down during moving. Two ends of roller is made of 45# steel and machined into the shaft shape, and fixed onto the supporting bracket with the bearing. Locating bolts are equipped with the bearing to prevent the roller from deviating. Driving Device: It is driven by speed reducer through sprocket wheels and chains. The speed reducer is recommended to select MD Series helical gear redactor, made by Omiter, Shanghai. Control Device: Driving speed is controlled by Siemens Frequency Converter that outputs signal to speed reducer, as to achieve the speed control of roller. Operation terminal boxes are equipped with both of loading and unloading conveyor, which consists of push buttons like Start, Emergency Stop, Reverse, and etc.. The conveyor starts to work after pressed Start. A pair of photoelectric switches is equipped at the end of roller conveyor. When cylinders pass through the conveyor, photoelectric switch sends out the signal to PLC, and PLC will send the signal to control the speed reducer automatically. Emergency Stop and Reverse are used under emergent conditions. Interlock: All driving system is interlocked with the furnace. It can't be loaded and unloaded until the furnace door opens in place. 5.2 Quenching Furnace It consists of furnace shell, lining, furnace door and its lifting device, roller conveyor, roller driving system, access door, combustion system, exhausting system and etc.. Furnace Shell: It is made of steel plate and formed steel and welded together which provides a good appearance (Welds height is no less than 5mm). Outer shell is made of formed steel which provides a good strength. Lining: It adopts compound structure. The lining material is different at bottom furnace, furnace door, side wall and roof. Bottom Lining: Bottom of furnace shall be cleaned regularly for removing the oxides, therefore, bottom liner is made of light-weight refractory bricks and aluminosilicate fiber. Refractory bricks are on the top surface, as ease to remove oxides. Aluminosilicate fiber is applied between refractory brick and steel plate for heat insulation. Liner of Furnace Door: It is made of heavy weight high aluminum bricks, which is to prevent the lining from being worn out. Liner of Side Wall and Roof: For energy saving and reduction, the insulating materials, pre-compressed aluminosilicate folding blocks (Working temperature is more than 1100ºC), are supplied by Yeso, which will be installed onto the side wall and roof through the special anchors (1Cr18Ni9). Insulating material shall be selected based on the various needs and requirement, such kind of compound structure is less weight, more reliable, less maintenance, minimized the heat loss. Furnace Door and Its Lifting System: Quenching furnace has tow temperature zones, one zone is heating and the other is holding. Middle door is designed between two zones, which is made of heat resistant cast iron. Loading and unloading doors (made of heat resistant cast iron) are designed at two ends of furnace body. Furnace Door: Door and Door Plate are made of heat resistant castings, aluminosilicate fiber blanket shall be provided inside insulation. Such kind of structure is less distortion, less weight, with a longer service life and better heat insulation. Furnace Door Lifting System .The furnace door is driven by the chain and sprocket wheels through a speed reducer or cylinder. The seal between furnace door and door plate is compressed by the guiding track and angle iron, as to ensure the safety and reliability. Opening and Closing of Furnace door is restricted by a limit switch installed at side of lifting chain. Furnace Door Driving Speed Reducer: MD series helical gear reductor, it is equipped with braking device. Furnace door is interlocked with driving system and heating system. In other words, roller conveyor can't be loaded and unloaded until the furnace door is opened in place, and can't be heated until the furnace door is closed in place. Roller Conveyor: It made of heat resistant cast irons (Cr25Ni20Si2) and poured into the castings with φ159×20. Positioning device (Cr25Ni20Si2) is equipped with roller conveyor to prevent the steel cylinder from running off center. Shaft end is casted and fixed onto the steel structures with the vertical bearing. Roller is installed at the intervals of 800mm approximately. Refractory and Insulating material at two ends of roller is standard fiber lagging. Top cover is movable, and attached to the furnace body with the bolts. Expansion will be occurred on the roller after heating. For driving side, it is equipped with locating pins for positioning and freely expansion, which are fixed with bearing. For non-driving side, key slots are designed and round locating bolts are adopted on the bearing, which assured the freely axial expansion and radial driving. Driving Device for Conveyor: It is driven by a speed reductor through the chain and sprocket wheels. Speed reducer is made by Omiter, Shanghai, type: MD series helical gear reductor. The braking device is equipped with the speed reducer, which can stop the action timely. Driving speed is controlled by Siemens frequency converter, it outputs signal to speed reducer and as to control the driving speed of conveyor. During heating, steel cylinders are performed a repeated to-and from movement in each heating zone to assure the service life of conveyor and increase the uniformity of heating. Cylinder's movement shall be restricted by a limit switch to keep it centered, which is more accuracy and reliable. One set of photoelectric limit switch is equipped at the heating zone and holding zone of quenching furnace respectively, which are fixed at the two sides of furnace body with the supporting. The cylinders can be positioned through the signal given by limit switch (positioning accuracy is ≤20mm). Access Door: An access door is designed at the bottom of quenching furnace for removing the oxides regularly, or when the equipment is shut down or maintenance. It is made of steel plate and aluminosilicate fiber. Steel plate is assembled onto the furnace body with the bolts. Connecting nuts adopts wing nuts as to disassemble easily. Sight Hole: Sight holes are designed at intervals of 3~4m of two side walls for observing the working condition of workpieces inside of furnace. Hole seat is made of cast iron, which provides a good seal, and more reliable and safe.
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