Pneumatic Chip Collection Conveying Systems

Three Pneumatic Metal Chip Conveying Options

Advanced pneumatic collection and pneumatic conveying methods are important technologies for state of the art metal chip processing systems.

For over 50 years National Conveyors Co., Inc. has been the leader in pneumatic metal chip processing technology, offering three types of systems:

• Dilute phase VACUUM PNEUMATIC metal chip collection & conveying systems
• Dilute phase PRESSURE PNEUMATIC metal chip handling systems
• DENSE PHASE metal chip conveying systems

Each design has its own benefits. National engineers can assist with the most effective selection to suit your requirements.

Vacuum Pneumatic Metal Chip Collection & Conveying

Metal chips are sequentially collected from multiple collection points, such as machine tools, by a vacuum pneumatic conveying system which transports them through pipelines to a central receiving station where they are separated from the induced air flow and discharged into a disposal container storage bin or automatic loadout system. The conveying air flow generated by a mechanical exhauster is filtered prior to discharge into the atmosphere.

System Details / Method Of Operation

Metal chips discharging from individual machine tool conveyors, or from conveniently located transfer stations, are delivered to a pick-up station consisting of a chip surge hopper (MH), metering screw feeder and mixing type intake device. An optional level sensor in each surge hopper signals the vacuum pneumatic conveying system network when a sufficient volume of metal chips have accumulated for conveying. When such signal is received, or by signal of an automatic sequence timer, a pneumatically activated anti-jam swing gate isolation valve (IV) (located just downstream from the pick-up station) opens, exposing vacuum conveying air flow. Simultaneously, the pick-up station (helicoid screw) feeder (MH) begins metering metal chips into the chip intake from which they are rapidly evacuated by the induced air flow and delivered to the downstream receiving equipment.

The incoming air stream reports to a wear resistant cyclonic or radial inlet (receiver) (RH) made of highly abrasion resistant materials where separation of chips from the air flow is accomplished.

The airflow rising from the receiver passes through a high efficiency pulse jet type dust collector/filter (AF) for removal of remaining finely sized metal chip particulates, after which the airflow will be suitable for discharge into the atmosphere.

Metal chips separated by the receiver together with particulates collected by the pulse jet filter report by gravity to a hopper fitted with an airlock type dump gate valve (DG) for discharge.

System Benefits

The National vacuum pneumatic metal chip conveying system offers these benefits:

• No Chip Tub Forklift Traffic or Labor Required
• Modular Design - Easily Adaptable to Different Machine Layouts, Extended or Reconfigured
• Economical Installed Cost
• Minimal Space Requirement
• Clean Working Environment, No Dusting
• Low Maintenance

Pneumatic Chip System Components

Pressure Pneumatic Metal Chip Conveying System

Referring to the diagram shown above, incoming metal chips (from chip wringing operations or other sources) are fed into the system airlock feeder through valve "A" filling the chip storage hopper. Valve "B" is closed. When the hopper is full, valve "A" closes, valve "B" opens, and a helicoid (screw) feeder fitted to the hopper bottom provides a metered stream of chips into the pneumatic conveying pipeline. For short distance conveying, a self relieving, anti-jam rotary airlock feeder can be provided.

Metal chips are normally conveyed to a distant chip receiver/target box (located above a roll-off container or truck) where chips are separated from the airflow. Alternatively, chips may be delivered to a storage silo for subsequent loadout. An upstream mechanical blower unit provides the pressurized airflow for conveying of metal chips.

Dense Phase Pneumatic Metal Chip Conveying System

In addition to dilute phase vacuum and pressure pneumatic metal chip conveying systems used for handling dry chips, National also supplies dense phase pneumatic conveying systems. This technology offers the advantage of being able to convey either wet or dry metal chips with equal effectiveness. Referring to the schematic shown above, chips from machining operations, filtration systems or other sources are stored in a surge hopper from which they are fed in batches of controlled volume through valve "A" into an unpressurized and empty chip transporter. Once the transporter is filled, the inlet and vent valves close and seal. Compressed air is then introduced into the upper area of the transporter and also through a fluidizing lance which extends into the lower section. Controlled fluidization allows the entire chip batch to be forced downward into the discharge (reducing) elbow without jamming or blockage. As metal chips are forced under pressure into the much smaller diameter of the elbow, they concentrate and form a dense slug of material which is pneumatically conveyed to a discharge point. Once the chip slug is discharged, a "line clear" signal is received, pressurized air supply shuts off, transporter inlet and vent valves open, and the transporter is once again ready to receive material.