GENERAL DESCRIPTION AND TECHNICAL SPECIFICATION OF BELT CONVEYORS
These specifications apply to belt conveyors incorporating rubber and cotton/nylon fabric belting for handling foundry sand of 90-100 lbs. per cft. density
The conveyor belts will be nylon fabric, 315/3 H. D., grade M-24 or heat resisting quality with 3 mm top and 1.5 mm bottom covers. Heat resisting quality belts will be for conveyors handling knocked out return sand and also for some conveyors handling the hot sand above 80 degree C. the belts will conform to IS-1891, Part-I and Part-II as applicable.
The belts if within Wesman’s Scope of Supply will normally be supplied as open ended or as endless belts. Vulcanising of belts, if needed will be done at site during erection and assembly. The Vulcanising charges are included in erection costs, in cases where offer includes erection & commissioning.
Load carrying idlers as also return idlers will be 114 mm O. D. idlers. Idler rollers will be made from ERW steel tubes 4 mm shell thickness. The O. D. of the roller will not be machined. The shaft of 20 mm dia. will be of m. s. bright bar. Bearing housing will be of pressed steel design. The rollers will be fitted with SKF 6204 or equivalent deep groove ball bearings and pre-packed with grease for the life of the roller.
Troughing load carrying idlers will be concentric and will have 3 rolls, 20 degree trough Inclination. For conveyors which are partly troughed and partly flat such as distribution conveyors etc. some of the troughing idlers will have 12 degree trough inclination for better control of the belt contour.
One piece design flat carrying idlers will be provided on conveyors where ploughs are used for discharging sand from the conveyor. Return idlers will also be of flat configuration one piece design.
The idler brackets will be fabricated from suitable m. s. sections.
3. Idler Spacing
The load carrying idlers will generally be mounted at a pitch of 1200 mm except in case of loading points where the pitch will be between 350 - 400 mm. In case of belt feeders below storage bunkers, load carrying idlers will be spaced at a pitch of 200-250 mm.
The return idlers will be space at 2400 mm.
4. Drums of Pulleys
The head, tail and snub pulleys will be of mild steel plate welded construction consisting of shell and two end plates on each of which m. s. hub will be welded. The m. s. shaft will be keyed on to hub. The face of the pulleys will be crowned and face length will be 100 mm more than the belt width. The pulley face will be straight approximately for 1/3rd face length in the centre. For the balance portion on both sides of straight length, pulley will have crown. The pulleys will run in externally lubricated self aligning ball bearing plummer block of C. I. construction. The head pulley nominal diameter will be 400 mm and tail pulley nominal diameter 315 mm except otherwise stated. Snub pulleys of 315 mm nominal diameter will be provided for all conveyors having drum centres (distance between head pulley and tail pulley) over 30.0 metres and wherever design demands. The pulleys will be statistically balanced.
5. Head Unit
The head unit will be integral unit consisting of head pulley with its shaft, bearing blocks fitted on m. s. fabricated frame which can be bolted directly to conveyor structure. Pulley with shaft, bearing blocks as well as base frame will be supplied loose for assembly at site.
6. Belt Cleaning Arrangement
A spring loaded type belt scraper will be provided for fitting on the head unit. The rubber strip used with the scraper will be soft rubber 10 mm thick and will be fixed by means of slotted holes to facilitate adjustments, necessitated due to wear.
7. Tail Unit
The tail unit will also be an integral unit consisting of tail pulley with its shaft, screw type tensioning arrangement fitted on a m. s. fabricated frame which can be bolted directly to conveyor structure. Pulley with shaft, screw type tensioning arrangement and frame will be supplied loose for assembly at site.
8. Take-up Device (Tensioning Device)
Screw type take-up device will be provided sufficient to cope with maximum of 2% of belt elongation for all conveyors.
All conveyors above 50.0 meters drum centres will be provided with gravity type take-up arrangement.
9. Drive Unit
The drive motor will be totally enclosed fan cooled squirrel cage induction motor suitable for operation 415 volts, 3 phase, 50 c/s. A.C. supply system. The motor will be continuously rated to comply with IS-325. The motor will be coupled to the head pulley through an oil immersed worm reduction gearbox. Flexible type coupling will be used between motor and reduction gear as well as reduction gear and head pulley except otherwise stated. The drive motor and gearbox will be mounted on a common m.s. fabricated base frame. Sheet metal guards will be provided for the couplings. All the components of drive unit will be supplied loose for assembly at site.
10. Conveyor Frame
The conveyor frame will consist of channel stringers made from ISMC 100 x 50 connected by cross bracing angles. Individual sections of stringers will not generally exceed 5.0 metres length.
11. Conveyor Supports, Platforms and Walkways
Vertical supports to support the conveyor either in the pit (this applies to conveyors running underground below zero level) or from top of the platform (this applies to conveyors running above zero-zero level) will be provided. Platforms and operator’s walkway as required for different conveyors may be provided, if specifically ordered by client. Vertical supports for conveyors will be generally fabricated from m. s. angle sections while the platforms and walkways will be fabricated from m. s. rolled steel sections such as channels, joists, angles etc. operator’s walkway will be 750 mm wide and will be designed for a live load of 500 kgs./sq. m. operator’s walkway will be covered with 5 mm thick O. P. chequered plate. Hand pipes will be shipped in random lengths and fabricated at site. Necessary access ladders to platforms wherever required will be provided. Access ladders will consist of angle/channel stringers with open steel treads 200 mm wide x 600 mm long.
To facilitate transportation and to reduce shipping volume various components of the conveyors will be offered for inspection and subsequently dispatched in “easy to assemble at site” sub-assemblies like head pulley, tail pulley, take-up device, head unit and take-up unit base frames, bearing blocks, motor, reduction gear, couplings, brackets, idlers etc. Conveyor stringers and supports also will be offered for inspection and subsequently dispatched in knocked-down conditions.