Load and Unloading
The main structure of the loading / unloading system is a supporting steel frame and steel roller bed. The rollers for the loading system are rubber coated, and steel Kevlar wound for the unloading system. The roller driving motor is independently controlled through an inverter. There are three finger-reach buttons for the loading system: load-jog, ready and send-in. The operator can easily load small / medium pieces of glass by using these three buttons. The unloading system also has the, unload-jog button to facilitate the unloading of small / medium pieces of glass.
There is a pneumatic pop up table to facilitate free positioning when loading / unloading large pieces of glass.
One pair of photo-electro sensor is installed in each section for measuring the length of glass loading / unloading area, the PLC will then use this data to decide the length of glass oscillation or final stoppage of unloading procedure.
Roller diameter: Ø 55mm, roller core Ø 48mm, high precision steel tube.
Roller pitch: 120mm
Roller quantity: 34 rollers per section
Leading roller (load table) and rear roller (unloading table) are non-driven rubber Coated.
Rubber coated side rollers are fitted to the non-drive side: 2 pieces per section.
Heating furnace is a 4-section casing structure with 250mm thick insulation lining, Sectional structure to facilitate up-grade of the furnace, if needed in the future to add on an additional furnace to change to a double chamber. These sections are linked together by strong bolts, are then vertically divided into top and bottom halves. The top half can be lifted up to 500mm by a motor driven leading screw-jack system for inspection and maintenance of the furnace interior. Between these two halves, there are ceramic roller cut-outs, which are precisely engineered to eliminate heat loss. The furnace has pneumatically actuated doors at the entrance and exit of the furnace, to seal the furnace atmosphere.
Both the top and bottom heating sections are divided into 30 individually controlled heating zones, totalling 60 zones. Each zone is controlled by an integral SCR-thermocouple system that keeps equal of the inner furnace temperature distribution.
The SCR does not produce interferences to the main power supply, as solid state relay sometimes do. SCR is also an easy maintenance system, which only takes minutes to replace.
The furnace is a reversible type, which allows the addition of a different quenching section, for example a bending and quenching section, at the opposite end. Therefore, the customer can invest less money, expanding the product variety.
Ceramic rollers are from Vesuviuz, France
Dimension: Ø 80mm, 3196mm in length.
The ceramic rollers are fitted with easy-fit bearings, which can be easily replaced.
Heating system (radiation)
Heating coil: Cr20 Ni80
Control elements: SCR (Silicon Control Rectifier) System.
Radiation plate (top furnace): Thermo-duration alloy (cast)
Armour Cap (bottom furnace): Thermo-duration steel channel
The heating coils are supported by ceramic tubes and rest on refractory tiles. Cr-Ni alloy is a non-rigid and long duration material that is much less likely to break comparing with Fe-Cr-Al alloy. In the event that a few coils should fail, production can still continue. Generally, coil replacements can be done in non-working hours, when the furnace is completely cooled down. When replacing coils in the top furnace, the radiation plates under the broken coil have to be removed. And when replacing coils in the bottom furnace, three or four ceramic rollers above the broken coil have to be removed. The removal and re-fix of the radiation plates and the ceramic rollers are the most arduous job of changing the coils. Replacing or repairing the coils is much simpler.
Aspiration Pipes: 10
A heat balance convection system is included with this machine. This will operate in tandem with the control system for the furnace and promotes the use of heated compressed air forced into the oven by a series of in line stainless steel pipes, located strategically throughout the encasement. This allows the glass to be soaked with heat more efficiently and thoroughly and will help reduce cycle times, particularly relating to soft coated glasses, and will substantially reduce breakages.
Roller Drive System
Motor drive system: synchronous + inverter (Fuji-GE)
Synchronous motors are much more accurate at speed controlling than AC motors
Transmission: Double rubber belt type.
Emergency Drive System
Component: DC motor + rechargeable batteries.
Emergency drive automatically switches-on during power cuts to enable exit of glass load from the furnace and prevent glass pieces melting over the ceramic rollers. The drive will slowly rotate to prevent the ceramic rollers from permanent distortion.
A1. Silicate mesh / board total thickness 250mm (extra thickness to minimize heat loss)
Automatic SO2 injection device: 1 set
SO2 is very occasional blown into the furnace to grease the roller surface. Most part of the SO2 gas is decomposed under high temperature shortly after entering the furnace atmosphere at 700 ◦ C, thus produces very little harm. The SO2 gas bottle must be provided by the customer. The SO2 gas bottle will normally be housed within the fan room and will be chained to the wall for security and piped in stainless steel to the furnace, with a safety valve at either end.
The quenching section includes supporting frame, quenching nozzle system and roller conveyor. The supporting frame is a steel structure with anti-distortion braces. The blowing nozzles are triangle shaped flat bellows made of cold-pressed steel sheets. The orifice facades are of innovative design and are precisely engineered to improve quenching efficiency. The nozzles are linked together by strong plate to become top quench header and bottom quench header, between them there is a self-balance chain system. The vertical position of the top quench header is precisely controlled by a numeric execution system, the accuracy of which is ±1mm. The rollers are intensively wound with Kevlar, and are driven by synchronous motor, the inverter is provided to control the driving speed. The roller core is high precision extruded steel tube, which is perfectly straight so as to secure the roller bed flat enough to prevent glass distortion. The quenching section is a converted T type, which contains 2 blower fans, controlled by 2 inverters
There is also an integrated sound room around the quench section. This is designed to reduce air inlet noise, fan case breakout noise and quench noise level from approximately 100 dB (A) to approximately 80 dB (A) at one metre outside the enclosure.
Steel Kevlar wound rollers
Dimension: Ø 55mm (core made of Ø 48mm high extruded steel tube)
Roller driving system
Motor system: Synchronous motor and inverter (Fuji-GE)
Transmission: Double rubber belt type.
Quenching nozzles: 35 pairs
Nozzle positioning system
Driving: AC motor + inverter
Transmission: Leading screw-jack system
Position accuracy: ± 1mm
Touch Screen (Hi-Tech):
The touch screen interface is the heart of the complete system; it provides concise and friendly control pages. The main control page contains all the basic parameters of heating and quenching. Pages for further settings and failure indications are provided behind the main page. The touch screen interface is a read-and-write system, with which the operators can input, modify, store and recall 100 sets of production parameters. When producing a similar batch, the operators just need to search and recall the right set of data previously input and start production.
PLC and expansion modules (Mitsubishi):
Mitsubishi PLC system is chosen for its simplicity and reliability. The PLC programme is completely orientated towards the customer needs.
Over-zero trigger SCR system
The 7188 / 7018 micro-cards are for temperature data collection and transmission. They are highly integral elements that are more accurate and sensitive than data modules.
These are used for a finer stable inner furnace temperature measuring. There are 69 thermocouples, 60 for the heating control and 9 for temperature information.
Heating control modules:
Temperature mode: The programme takes the inner furnace temperature to decide the readiness of heating. When the furnace temperature is raised to a certain temperature, the glass sheets will be conveyed out of the furnace directly into the quench.
Time mode: The programme takes the heating time to decide the amount of time the glass remains in the furnace, once the cycle time has reached it’s pre-set limit it will discharge the load into the quench.
Pre-empt mode: The system automatically decides between the above two parameters, whichever comes first.
The above three modes are freely changeable. Operators can switch to whichever mode they feel is more convenient.
Fan Control: Inverter drive, Fuji-GE
Air pressure measurement: The blowing system is measured by micro-sensor transducers that are far more accurate than bellows gauges.
Fail Safe Warning
Voice Alarm and Screen Indication
Roller Drive Speed Control
The roller speed of each section is individually controlled by its own separate inverter drive.
Non-step regulation allows a perfect speed synchrony between each section.