6-wheel Design For Cleaning Of Plates
Blast Cabinet, 6 Nos. of 19 ½" blast wheel Assembly, Bucket Elevator, Abrasive Cleaning System, CFS Separator, Roller Conveyor System, Blow Off cum Brush Off Unit, Hy Pulse Jet type Dust Collector Unit capacity 12000 cfm, Control Panel & electric Motors Generally as per enclosed Specification Sheet No. Surfex/02 & Drawing No. C2-43-07-2K8. Sequence is controlled by PLC
The blasting material is kept on the inward side of the roller conveyor. The components pass through inward tunnel and enter into the blasting chamber for blasting purpose. 6 Nos. of blast wheel stations are located strategically around the cabinet fires abrasives on the components. The components are shot blast finished homogeneously all around. The blasted material moves forward and enters into outlet tunnel. At outlet vestibule brush off cum blow off system is installed to remove stagnated shots lying on the upper side of plate.
Operating Principle :
The machine consist of substantially built Blast Cabinet having 6 Nos. of Blast Wheel Station positioned strategically. The machine is provided with Roller conveyor system for conveying the plate into Blast chamber. The rollers under Blast cabinet are provided with Mn. Sleeve for retarding from abrasion. The machine entails blow off and dust off unit, Pulsejet type dust collector unit of adequate capacity. The plates are placed on inlet side of rollers. The Roller conveyor system carries the plate into Blast chamber for blasting purpose and blast clean in single pass on both side of plate. The blasted plate come out from outlet portion of the machine. The dust off and blow off unit constantly removed shots laying on plate. The entire operation of machine controlled by PLC. The blasted plate is carried by Roller conveyor system into Paint Room. The paint room consist of 2 Nos. of Automatic Paint Gun with Reciprocation Arrangement. One gun is are reciprocated to paint upper side of plate and remaining one gun reciprocate and paint bottom side of plate. The Paint room is adequately ventilated by Dust Collector System having Dry Paint Filter for filtering paint laden air. The coated plate is transferred to slot conveyor and transferred to Baking Oven for curing purpose.
The Blast Cabinet is fabricated from 6-8-10mm thick heavy-duty prime quality steel plates, supported by strong rolled structure welded construction and engineered suitably for strength and rigidity to guarantee the optimum sturdiness. This robust rolled structure with thick plate foundation holds stand the machine and helps to reduce vibration keep within permissible limits. The Blast cabinet bottom is provided with mild steel perforated floor for protection against abrasion wear. The Vestibules are fabricated with 6mm thick sheet. One number of service doors is provided in the vestibules for inspection and maintenance of the machine.
Blast Cabinet Liners:
The entire cabinet is lined with 10mm Mn. Steel overlapping tile. As and when these liner worn-out, the worn-out liners are only to be replaced
Blast Wheel Assembly:
Six Nos. Of blast wheel stations, Size 25RLM195 (19 ½" x 2 ½'') with RADAIOLOC MECHANISM are mounted on 20mm thick heavy-duty prime quality steel plate and strategically around the cabinet and the pass-line of the work. All blast wheels are arranged to blast at an angle with the line of job movement. The unit consists of fabricated steel casing having installation of different alloy steel liners, rotor, blades, control cage, impeller and feed spout. The rotor is made out of EN grade material duly hardened. The drive system of blast wheel (rotor) entails a set of self-lubricated and self-aligning pedestal bearings. The rotor is dynamically balanced. The drive shaft of blast wheel is made out of EN grade material and duly precision grinded to the finest accuracy. The fabricated casing of blast wheel assembly can be easily opened up through bolts/levers for examination of various liners and parts of wheel assembly. Safety switches are provided on blast wheel to prevent accidents. Individual ammeter is provided on control panel to indicate abrasive flow rate / loading of turbine in terms of current loading on ammeter. The abrasive media is centrifuged at a required tangential velocity by blast wheels having 8 Nos. of moly and chromium and various other alloy steel and hardened to 58-62 HRC value blades The latest RLM design makes blade slide fitting type. The rotor, blades and rotor shaft are balanced to the finest accuracy. Blades, control cage and impeller are shell casted to give even wear and tear during operation leading to vibration free performance of entire system.
A vestibule extends beyond the work entrance slot of the blast cabinet. The entrance vestibule is fabricated from 6mm thick steel plates and combined with two set of hanging rubber seals. The spent abrasive trapped within the entrance vestibule is returned to the main abrasive system through hopper. A Photoelectric sensor is provided near inlet vestibule. The blasting will start only when job reaches the nearest blast wheel and blasting will stop when job move away from the blast wheel.
Abrasive Separator, Rotary Screen & Storage Hopper:
The rotor of blast wheel assembly unit fires down the abrasive on the component moving on conveyor. The spent abrasive falls into hopper of the cabinet. The abrasive from hopper slides down to the screw conveyors, which transfers them to the boot of the bucket elevator. These shots are elevated to the desired height with the help of buckets mounted on rubber belt. Brake motor is provided for elevator. The separator is COMPENSATING FLOW STRAIGHT (CFS) AIR WASH A rotary screen is housed within the separator. Oversize contaminants and the media mixture are discharged from the head section of the bucket elevator into the rotary screen by means of an upper screw conveyor. The trashes will be directed by the internal screw flight to a trash and their currents remove the contaminants. The dust and useless fines will be air borne to an expansion chamber from where coarse material will drop into a refuse hopper and thereafter to the floor level through drain tubing and dribble valve control. The fine dust particles will be conveyed through vent piping to the dust collector .
The usable abrasive is transferred into the storage hopper for re-circulation purpose. The abrasive from the storage hopper are transferred into blast wheel unit through feed gates. These gates are enclosing to reduce noise within 80-85 dB. The rotational movement of impeller constantly accelerates the incoming abrasives and feed them to the blades of rotor. An electro-pneumatic valve operated by pneumatic cylinder and solenoid valve regulates the flow of abrasive to the blast wheel unit. The abrasive at high velocity are thrown by rotor on to the job. The flow of abrasive to the wheel is controlled by specially designed dribble valve, which is mounted before the storage hopper. The valve is opened and closed with an air cylinder, which is actuated electrically by a 4-way solenoid pneumatic valve, consuming a few Cfm of compressed air at 80 psi
Abrasive Control Mechanism:
The abrasive flow from storage hopper can be regulated by electro pneumatic 4 way type solenoid valve operated fully enclosed soundabrator valves by a screw regulator. This system consumes small amount of compressed air at 80 psi. The opening of valve can be done through a screw as per ampere meter setting of blast wheel motor. The totally enclosed design of this valve muffle the sound emanated from blast wheel. It is reported lowering of sound level by 5 to 10 dB.
Surfex Hy-Pulse Jet Type Dust Collection System:
`Surfex` Hy-Pulse Jet type Dust Collector of 12000 cfm / 20400M³ per hour with filter cloth area of 360 sq. meter with spun bonded pleated Cartridge .Air to cloth ratio is 3:1. Superior quality of material is used for making bags. The dust collector is pulse jet type and is self-cleaning. The dust-laden enters the dust collector housing through side inlet and passes through into settling, equalizing compartments expansion in the compartment takes place the air velocity drops, and the flow is distributed over the entire setting area. The air then flows up and away from the storage hopper and causing the heavier dust particles to settle. The finer particle will move upwards into the filter bags. The air passes through the tubes to the atmosphere by means of exhaust fan mounted on the ground. The bags are sequentially cleaned by back flushing with air from the clean air plenum. This momentarily air flow reversal is induced by shot bursts of compressed air released by fast acting, high flow diaphragm valves controlled by solenoid pilot valves which are operated one at a time by the control box. Since only one row cleaned at a time the unit continues to collect dust even as filter elements are cleaned. Compressed air at a pressure of 90 to 105 psig is required. Air must be relatively free of moisture and oil. The dust is collected in the tray of the dust collector. The trays are taken out periodically and emptied. . The blower unit of dust collector is dynamically balanced. The dust collector is fabricated in modular design and all the joints are sealed with high quality sealing compound. Exhaust fan is designed with backward curved blades fan driven by 30 HP drives.
Roller conveyor on inlet and outlet and is driven by 7.5 HP x 2 gearbox with variable AC drive. The rollers are mounted on self-aligning bearings. Chain and sprockets transmit power. The rollers in direct blast zone are fitted with Mn sleeve to retard wear. Roller conveyor is provided with devices to get accurate speed of conveyor (mtr/min) on panel which can be further adjusted accordingly
Blow off cum brush off system: This system is installed in outlet vestibule of the machine. Blow off cum brush off system is activated after shot blasting as shots get stagnated on the upper surface of plate; this system is auto adjustable to different thicknesses of plates
Control Panel (ELDON) make:
It composed of
Control Panel: It is an independent dust proof IP-54 aesthetic look control panel manufactured according to TEC regulations and EC directives, having the latest control system with inter-locking. The complete sequence is controlled by PLC.
Instrumentation: The ammeter for each throwing wheel and voltmeter are fitted for instant and accurate reading. The various timers of reputed make are provided for blasting operation.
Protection: It is entails by contactors, relays, push buttons, main isolation switch, safety limit switch, emergency switch, grounding system, HRC fuses, indicating lamps etc. The time control device is provided with visual lamp indicator depicting the passage of time. Various safety features are inbuilt in the system like blast wheel motor will not operate if door is opened
Electrical Power distribution: It is with transformer for low voltage internal consumption, complete wiring on the machine with cables, protection guides, cable with terminal connections and complete wiring inside the electric panel.
All exposed power drives are equipped with totally enclosed Safety vibration free wire mesh guards. The safety guards may be easily and quickly removed and refitted for equipment maintenance.
The blast cabinet doors are equipped with safety interlock switches to automatically shut off the blast wheel units, if by accident either door should be opened during the blasting operations. The switch also prevents starting the wheels unless the doors are completely closed.
When blast wheel casing is opened, machine will not operate.
Inside and outside surface of equipments will be brush cleaned and given two coats of Epoxy primer. Final coat on exterior of the system is Pu paint Air Drying, Shade: Tata Green shaded and electric line channel is GI coated and all the guards of motor are yellow enameled.
Plate Form & Supports:
A service plate form is provided for access to the elevator and separator drive. The plate form floor is constructed of chequered plate. Hand railing, ladder and supports are provided for maintenance and inspection purpose.