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Plate Feeder Features

STANDARD FEATURES

 

Direct Load Facility


Direct Load Facility

Loaded Start-Up 


Loaded Start-Up

Specially Manufactured Plates 


Specially Rolled Plates

Chains

 
Chains and Rollers

 

 

Head and Tail Shafts

Head and Tail Shafts

Mainframe

Mainframe

Variable Speed Drives

 Drives

 

 

OPTIONAL FEATURES

 

In-Built Fines Retrieval

In-Built Fines Retrieval System

 

DIRECT LOAD FACILITY

The Direct Load facility, incorporated into all MMD Feeders, allows high impact loading of material directly onto the feeder plates, even whilst the feeder is operational.

When material is loaded onto the feeder, the plates cushion the material, absorbing the undefined initial impact forces by deforming within their elastic limit. The supporting impact rails, caterpillar chains and rollers contain and transmit the remaining forces evenly into the fully-welded one-piece mainframe, dissipating impact energy within the confines of the plate feeder. This elimination of impact energy minimises supporting steelwork, enabling the feeder to be easily installed in open pit operations, processing plants and underground applications.

The position of the Caterpillar chains and the impact rails is such that the optimum strength of the conveyor plates is achieved, whilst also making the chain and rollers accessible for routine inspection.

 

LOADED START-UP

Accelerating the feeder from a standstill position whilst fully loaded with material requires the most torque. The size, length and angle of the feeder, together with the type of material and throughput required, all affect the amount of power/torque needed to allow startup of the feeder whilst completely full of material.

 

Using both the vast knowledge and experience gained from the many feeder applications worldwide and also proven calculations, MMD analyse each feeder and match it to the application requirements. This loaded start-up facility provides operators with the flexibility to start or stop the feeder when required, without production stoppages.

 

SPECIALLY ROLLED PLATES

The plate feeder's continuous loading surface, illustrated in orange, is constructed from a series of short plates fixed individually to the caterpillar chain.

These plates are manufactured from MMD designed specially rolled sections. The manufacturing process of these rolled sections provides tighter measurement tolerances, increased wear properties and greater resistance to impact loads than is possible with casting techniques. The close toleranced overlapping edges prevent spillage in between the plates, even in the most exposed areas around the head and tail sprocket.

The ribbed design on the plates optimises surface area and promotes a positive grip on the material, whilst also providing a lightweight yet strong surface to load onto. The ribbed construction also enables the bolts attaching the plates to the chain links to be positioned in the deep recesses of the ribbed plates, protecting the bolts from damage from loading material. The bolted construction allows small sections of plates to be removed easily in order to access and maintain components on the plate feeder.

The strength of the conveyor plates is not only achieved through its design and the manufacturing process, but also by the positioning of the chains and the impact rails. Not only does this positioning support the plates, but it also gives them the flexibility to deform within their elastic limit, providing a strong impact cushion for loading material. As a result of the apron plates deflection properties, severe impact loads dumped onto the feeder are mostly transmitted to the robust mainframe through the solidly mounted impact rails. This prevents impact damage to the rollers and chain and prolongs the service life of these items.

 

CHAINS AND ROLLERS

 

 

Chains and Rollers

CHAINS

MMD Plate Feeders feature two strands of heavy duty chain with a sealed and lubricated hardened steel construction. The process of hardening each part of the assembly is controlled to produce the ultimate in toughness and shock resistance, as well as maintaining uniform wear throughout the long service life of the part.

The sealed chain prevents abrasive material from entering the chain's internal parts, which can cause premature wear. Sealing the chain extends chain life by 20-30%. Sealed and lubricated chain also reduces friction, lowers costs for maintenance, and increases efficiency. The chain has split master chain links at intervals for easy removal and re-installation of small sections.

   

Carry and Return Rollers

 

Return Roller

CARRY AND RETURN ROLLERS

The top carrying rollers are a standard tractor type, spaced at intervals along the length of the feeder to ensure smooth travel of the deck during operation. In the loading zone the rollers are tightly spaced together, providing extra strength and support to take care of the undefined impact loads in this area. The bearings on the carrying rollers have been engineered to accept high impact loads and are sealed for lifetime lubrication and extended wear life.

The return strand of the feeder is carried back on specially heat-treated steel return rollers. The rollers are bolted onto the lower joist. The whole return roller assembly can simply be withdrawn through a hole in the web of the joist, facilitating easy removal and installation from the side of the feeder.

 

 

HEAD AND TAIL SHAFTS

 

Plate Feeder Head Shaft

The MMD Apron Plate Feeder has a heavy duty head (drive) and tail (driven) shaft machined from high grade hot rolled steel. Each shaft is accurately machined to accept the sprocket hubs, bearing assemblies, and on the head shaft, the support rings and the drive unit.

The support rings on the head shaft are positioned in-line with the impact rails and support the apron plates as they travel around the head shaft.

As the tail shaft has no drive, it is contained between the shaft bearing assemblies and is therefore shorter and lighter than the head shaft.

Large bearings are used on both the drive and tail shafts. They are designed to be grease lubricated and have a reservoir for grease in the bearing blocks and end caps.

   

Sprocket and Hub

Sprocket and Hub

SPROCKETS AND HUBS

The sprockets on the head and tail shafts are bolt on segmented design made of a wear-resisting alloy steel. All sprocket tooth segments for both tail and head sprockets are interchangeable for easy maintenace and spare parts ordering. Each sprocket has an odd number of teeth on each wheel, thereby contact with all of the teeth is only completed after two revolutions of the chain. This ensures a longer service life.

The sprocket tooth segments are bolted onto hubs with high tensile bolts for ease of replacement. The sprocket hubs are accurately machined from alloy to transmit the high torque loads required to "Pull-out" from a fully laden start up.

 

 

 

MAINFRAME

 

 

Mainframe

 

At the core of the MMD Feeder is the fully welded fabricated mainframe which utilises rolled steel beams, ribbed and stiffenened creating a robust lightweight construction to minimise supporting steelwork and ease site installation. This design also creates an open structure for convenient visual inspections even whilst the feeder is operational.

The construction starts with two main beams that run along the entire length of the feeder. These are tied together with cross beams to create the main feeder framework. Each beam presents open flanges for convenient and substantial mounting points for external framework i.e. a hopper. The fully welded construction continues with more beams running along the length of the feeder. The impact rails are mounted onto these beams to transfer severe impact loads directly into the main framework.

In certain underground environments and existing plants where space is restricted, the mainframe can be manufactured in sections and bolted together at the final siting location to facilitate easy assembly.

 

VARIABLE SPEED DRIVES

 


A Hydraulic drive

An Electro-Mechanical Drive

Apron Plate Feeders generally require a variable speed drive unit as they are often the main method of controlling the throughput of the plant. Feeders can either be fitted with a  variable speed hydraulic drive or an electro-mechanical variable frequency drive, depending on the application. Both methods offer infinite variable speed control, from 0 to maximum, and give the option of being controlled remotely using simple controls.

Applications that require more power than a single drive can provide, can be installed with a double drive arrangement, positioning a drive on each end of the feeder head shaft.

   

 

FINES RETRIEVAL SYSTEM

Fine particles may be expected to form beneath Apron Plate Feeders depending on the material. MMD Apron Plate Feeders are available with an in-built fines retrieval system.

The fines retreival system works by the employment of cleaning scrapers welded to selected conveyor plates that collect fine material from the bottom of the feeder and bring it to the top of the feeder to be deposited with the rest of the material, eliminating the need for a separate fines conveyor.

Because the fines retrieval system is set within the width and length of a standard feeder, it can often be retro fitted to the feeder if required.

Where the fines retrieval system is not employed, the return strand of the feeder is carried back on rollers mounted along the inside of each of the main frame beams.

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