Strip Cleaning Machine
Strip cleaning machine are used for stainless steel,descaling of carbon steels. This machine consist of multiple centrifugal blast wheels each of them driven by individual motors to give a through cleaning. The jobs kept on suitable conveying system with variable speed flexibility. The jobs enters the blast cabinet for cleaning from abrasives fired by multiwheels for homogenous finish.
Operation :
The strip is fed from de-coiler to inward side of tunnel /vestibule of pinch rollers of shot blasting machine. Then the strip enters into blasting chamber for blasting operation/purpose.8 no of blast wheel stations are located strategically on to blasting cabinet.(i.e 4 wheels are located on top of blasting cabinet and 4 wheels are located on to bottom portion of blasting cabinet) .the blasted /cleaned strip moves forward and enter into out let tunnel/ vestibule. From there strip is pulled by coiler and other equipment (arranged by customer).The machine is designed for cleaning strip @ 60 mtr per minutes.
Operating Principle :
The machine entails robust and sturdy Blast Cabinet on which 8 Nos. of Blast Wheel Station are located at descaling angle. The cabinet is also equipped with Abrasive Recovery & Cleaning System and Dust Collector for ventilating Blast Cabinet. The strip is fed from decoiler to inward side of tunnel through pinch roller of Shot Blasting Machine. The strips enters into Blasting Chamber for Blast cleaning application. 8 Nos. of Blast Wheel Stations cleans the strips from both sides in single pass. The strip is pulled by Coiler and other equipment and adjustable as per requirement. Maximum Coil Strip is of 60 mtrs. per minute can be achieved. The entire operation of machine is meticulously controlled by PLC.
Blasting Cabinet :
The Blast Cabinet is fabricated from 10-12mm 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 No. of Door with safety device (limit switch to prevent start-up of abrasive blasting if door is open).
Blast Cabinet Liners :
The entire cabinet is lined with 10mm Mn. Rolled Steel Sheet
Blast Wheel Assembly :
Eight No. Of blast wheel stations, Size 25RLM195 (191/2” x 21/2“) 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. Soft starters are provided with blast wheel motors to reduce current consumption. 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.
Vestibule :
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 blast Wheel will start only when job move into the vestibule.
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 Controls 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 16000 cfm / 27200M3 per hour with filter cloth area of 420 sq. meter with spun bonded pleated Cartridge . Air to cloth ratio is 3.5:1. 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 40 HP drives.
Roller Conveyor :
This unit consists of Pinch Roller assemblies at a pitch of 800 mm
NOTE- Coiling and De-coiling arrangement has to be provided by customer
Control Panel :
- 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 sequence of operation 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.
Safety Features :
- 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.
Painting/ Color :
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 synthetic, Shade: Tata Green and electric line channel is GI coated and all the railings and 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.
