Automation Engineering News

ZA series line shafts from R+W install as single units and run smoothly without support bearings.

The ZA series is assembled from cut-to-length extruded aluminium tubing with a precision straightness tolerance of 0.2mm/m, lateral stiffness and low mass.

This allows for high-speed operation at a low cost relative to the additional hardware required to assemble a line shaft system.

Software allows for quick calculation of critical speed, moment of inertia and torsional stiffness for any length.

The line shafts are available in a variety of sizes, covering torque ratings from 10Nm up to 4,000Nm and for special applications up to 10,000Nm.

They can be made with a variety of coupling output hubs in addition to the traditional clamping hub, such as flanges, expanding shafts and tapered conical clamping hubs.

A series of Nord geared motors have been installed to drive a chain conveyor belt system in Audi’s production facility in Ingolstadt, where the doors for the Audi A4 and A5 are produced.

In this highly automated production facility, large robot arms reach into special containers and remove sheet metal parts.

Further along the production line, welding robots carry out the remaining work.

The parts for the doors are routed along a chain conveyor belt system powered by Nord drives.

This branches into loading and unloading sections, which convey the vehicle component containers from station to station.

The system is equipped with lifting equipment, transport carriages, plus rotating and elevating platforms.

The complete system is driven by Nord components - mainly bevelled gear drives.

The chain conveyor belt and the rotary units for direction changes are controlled by almost 400 of Nord’s decentralised field I/O modules.

These were specified as they are optimally suited for decentralised operation and are particularly service friendly.

Each node consists of a Nord SK 300E frequency inverter drive with an I/O unit that has a repair switch and M12 connector components for connecting with process sensors and actuators.

The motor is connected to the field I/O module using Harting connectors, so that it - and the inverter drive - can be replaced quickly if necessary.

The field I/O modules communicate with the master controller via Interbus.

The inputs of the field I/O modules enable, among other things, remote reading of the proximity switches for optical position monitoring of the containers.

The system also uses decentralised reverse starters, which can be controlled via the outputs of the field I/O module.

The reverse starters take over functions such as the centring of the containers for position-accurate transfer to the robots.

They move the elevating platforms in the transfer section to the forklifts and lock the load in lift equipment.

The conveyor belt system is equipped with seven lift stations, which are controlled by frequency inverter drives from Nord’s SK 700E range.

Communication with the controller is again implemented via Interbus.

In lift stations that operate over more than two levels, the inverter is equipped with positioning control which takes over the dynamic positioning.

The positions are opto-electronically sensed via a bar code and a reading sensor, then forwarded to the positioning control.

The individual positions are then specified via the controller and the inverter takes over the precise positioning of the lift station.

The same system is also used for the transverse transport carriage, which can switch the container to three different conveyor sections.

If an error occurs in an inverter, the error message is directly sent to the master control via Interbus and displayed on the operating panel, to request manual intervention

Renold Hi-Tec has released a range of UJ couplings for serious misalignment problems in power transmission systems with torques of up to 18,000Nm.

The couplings consist of a rubber-in-compression coupling and a universal joint assembly, and are designed to transmit torque between a diesel engine and a driven interface, where the two cannot be aligned accurately.

The couplings are also used where there is distance between the driving and driven elements or where one can move radially and axially in relation to the other.

The rubber-in-compression coupling is intrinsically fail-safe, controls torsional vibration and provides damping for the drive train.

Typically suited to off-road vehicles, agricultural machinery, marine propulsion, rail traction and pump sets, the UJ coupling range is designed to accept the industry standards DIN and SAE, and Mechanics flange designs for engine flywheels from SAE 10 to SAE 24.

Ondrives will merge with Rino Industries under the single name of Ondrives on 1 April 2009.

This move will bring together the strengths of two companies that have worked closely together over the last 10 years.

The move will see in-house produced gear reduction units, linear actuators, bearing housings and couplings featured in a newly-merged catalogue.

A range of fasteners, including ceramic, stainless steel and treated versions, will be moved over from Rino, along with a large accessories section featuring wheels, bushings, rod ends, anti-vibration mounts and spring assemblies.

Products and services of both companies will be managed through a single website, where CAD images can be download and orders can be placed.

Any enquiries, orders or queries sent to Rino will automatically be passed over to Ondrives and will be dealt with in the usual way.

Ruland Manufacturing Company has introduced quick-clamping shaft collars that do not mar the shaft, do not require tools and are designed for quick adjustments.

The collars are suitable for light duty applications with frequent setup changes or adjustments, or where the need for tools is not practical.

The quick-clamping collars are designed with a low-profile clamping lever, which makes them suitable for rotating and stationary applications.

Industries such as printing and packaging, as well as others, can use quick-clamping collars to retain frequently changed items, such as rolls of media, or for rapid and precise adjustments of guide rails or other setup fixturing.

The quick-clamping design shaft collars are made from high-quality aluminium with an anodised finish.

The shaft collars are available with bore sizes from 5/16in to 1 1/2in in the inch series and 8mm to 35mm in the metric series.

As all Ruland shaft collars, the quick-clamping design collars are single point faced to ensure perpendicularity and proper alignment.

A precise shaft collar face-to-bore relationship ensures that components are properly positioned and not tilted on the shaft.

Collar face perpendicularity also ensures even pressure on interfaced components.

Ruland shaft collars are also available in one- and two-piece clamp-style designs and set-screw design.

R and W present the Ecoflex precision coupling, which handles the torque and size requirements of a very wide variety of small motors.

With a torque rating of 3Nm, and handling English or metric bore sizes all the way from 3 to 16mm, this coupling gives high performance at a low cost.

The hydro-formed stainless steel bellows exhibits a very high level of torsion resistance, but is easily flexible in the lateral, angular and axial directions.

Moment of inertia is kept low by the low mass inherent to its tubular structure.

Water and wastewater services provider Anglian Water has decided to replace old screw pump gearboxes with new planetary gearboxes from Brevini.

Work has been carried out on a trial site at Maldon in Essex

Working closely with Brammer UK, a supplier of industrial maintenance, repair and overhaul (MRO) products and services, Brevini has identified a suitable gearbox and developed a mounting bracket that allows the new gearbox to be installed without the need to re-engineer the original pump.

Working with Brevini and Brammer, Anglian Water identified sites where conventional screw pump gearboxes were running with poor efficiency.

The benefits of replacing these older gearboxes with Brevini’s highly efficient planetary gearboxes were obvious as they are able to run off of a smaller motor than conventional gearboxes and can be retrofitted to existing structures which decreases the cost of installation.

A trial site at Maldon in Essex was identified where a screw pump gearbox was due for replacement.

Following an on-site consultation, Brevini was able to recommend a suitable gearbox and design a mounting bracket that would allow it to fit directly onto the existing structure.

The output shaft was designed to be of the same diameter as that on the previous gearbox, while a backstop was fitted to prevent the screw running backwards when it stops.

Planetary gearboxes are capable of producing very large reduction ratios (they can reach 15,000:1) meaning that they are ideal for driving heavy rotors at slow speeds.

Producing up to 800kNM of torque, the gearboxes are able to produce the same power as large ‘worm-and-wheel’ gearboxes despite being far smaller - often 60 per cent lighter than their equivalent.

Brevini gearboxes have a lifetime of more than 100,000 hours when they are in constant use, keeping maintenance down to a minimum; one oil change per year is all that is needed.

Since the installation of the new gearbox, the Maldon site has reported that the pump is running with 16 per cent more efficiency than previously, the gearbox running to an efficiency of 96 per cent.

Running costs have been greatly reduced as the new gearbox only requires 13.4 amps compared to the previous 16.6.

This equates to a 2.1kW reduction in running power and a saving of GBP1,400 per year, a potentially significant saving if all the company’s gearboxes were to be replaced.

Voith Turbo has launched a multimedia CD-ROM that features animations of fill-controlled fluid couplings.

Fill-controlled fluid couplings operate on the principle of hydrodynamic power transmission; this means that torque is transmitted by a liquid - and occurs in a wear-free manner.

The CD-ROM contains animations of fill-controlled couplings, as well as animated demonstrations of the principles of hydrodynamics and several examples of typical applications.

Voith fill-controlled couplings handle the difficult drive requirements in a variety of applications in the conveying and processing fields.

The main field of applications for this type of coupling include: belt conveyor systems up to several kilometres long; armoured face conveyors (AFC) for underground coal-mining operations; heavy-duty shredders, such as those used in metal recycling; and ball mills used in material processing.

Voith couplings transmit from a few hundred kilowatts up to several megawatts of power.

They ensure controlled acceleration of the driven machine, effectively dampen shocks and vibrations in the drive line, adjust the speed precisely and provide effective overload protection.

They can be used to easily incorporate a clutching function and provide active load sharing in multi-motor drives.

Voith Turbo said it has designed the CD-ROM with the viewpoint of the customer in mind.

In addition to introducing fill-controlled fluid couplings as a product together with the basic principles of operation, examples of applications illustrate the benefits and advantages of using Voith couplings in drive lines.

The CD-ROM is available in English and German, and can be ordered from the Voith Turbo website.

MK1 bellows couplings from R and W Coupling Technology allow for increased bore diameter within a given coupling size through the use of radial set screws with dismounting grooves.

Ideal for use in precision encoders and linear actuators, the MK1 range can help adapt between shafts with a large difference in size.

The coupling incorporates a stainless-steel bellow that compensates for axial, lateral and angular shaft misalignments simultaneously, while operating with zero backlash and high torsion resistance.

Miniature metal bellows couplings are available for a torque range of 0.05-10Nm (0.4-88.5in/lb) and bore sizes from 1-28mm.

Fuse theory, a myth related to couplings, is costing industry a fortune, according to Paul Shuffleton, managing director of Renold Hi-Tec Couplings.

According to fuse theory, rubber-in-shear type flexible couplings protect diesel-driven generator sets by failing or acting like a fuse when there is a potentially damaging short circuit.

This is a myth, because the majority of rubber-in-shear couplings fail through fatigue rather than because of a short circuit.

This is also the main reason for failing rubber blocks.

Rubber-in-shear couplings consist of a rubber element fused in-between two metal hubs.

One hub drives the other through the rubber, the flexing of which protects against shock and vibration.

The coupling is only as strong as the rubber element, so if the rubber fails then the coupling fails too.

When this happens on a diesel-driven generator set, some engineers believe there has been a short circuit and that the relatively inexpensive coupling has acted like a fuse and protected the expensive diesel engine.

In reality all that has happened is that fatigue has caused the coupling to fail.

Rubber-in-shear couplings can quickly fail on applications like these ones.

Premature fatigue failure of rubber-in-shear couplings is a virtual certainty when used in conjunction with diesel engines.

They do not act as fuses, they just fail.

The rubber element in a rubber-in-shear coupling is made up of lots of long-chain molecules that are distributed randomly in the rubber when the coupling is new.

When the drive-hub turns, the rubber element twists slightly and turns the driven hub, which causes the long-chain molecules to quickly orientate to the direction of twist.

When the coupling is subjected to the diesel engine’s torque fluctuations, or worse, torque reversals, the long chains become tangled in their attempt to re-orientate themselves in the opposite direction.

This causes a high degree of stress that will eventually result in rapid fatigue failure.

The solution is to fit a different type of flexible coupling, such as a rubber-in-compression coupling, which protects the system from shock and vibration.

A rubber-in-compression coupling will operate for up to ten years without maintenance or problems with premature fatigue failure.