More than 50 modular platforms in operation across Europe

After the West Coast, South Wales and Thames link projects with installations in Mill Hill and Backfriars, England, Corus Rail has just installed its first modular platform system in France, in the Paris suburb of Mitry Claye. With more than 50 modular platforms in operation across Europe, Corus has become a major player in the market. The main advantage of the Corus system is that its design allows the majority of the installation work (including foundation construction) to be done behind a safety fence and away from operating railway. This means that the railway does not need to close during the majority of the work, resulting in obvious cost savings due to a lack of disruption to train service. (Refer to the two pictures on the right).

Modular platforms fit various needs: length extension for longer trains, height extension (for handicapped or elderly access) of existing platforms, new easy to remove and adjust platforms and more. Whereas engineers usually think concrete, Corus development teams have totally re-designed the railway platform concept to create a wholly modular product made from rectangular hollow steel sections. The objective is to provide a cost-efficient, quick way to design and install passenger platforms. What's more, Corus modular systems can be customised with all kind of surfaces and finishes.

For Mitry Claye, in France, the platform was initially installed to suit the current track position. The track will be moved slightly in 2-3 years time and adjusted to tie in with this new track alignment. The most recent installations in the UK have been part of the Thameslink Project. These were part of the extension of existing platforms in order to allow for longer trains. At Mill Hill (northern suburbs of London) there are 4 platforms that were extended around 50 to 60m each. A 50m temporary platform extension over Blackfriars bridge (Thameslink project) as part of the Backfriars Station works has also been completed.

A reduced total cost of ownership
The use of lightweight components minimises foundation impact and eliminates the need for costly and time consuming ground treatment measures. Moreover, specific installation material is not required, the traffic is not interrupted during erection and the structure has a 75 year life span. During the life span, the Corus modular system is also adjustable and can be relocated.

Only a few weeks for commissioning
The modular platform system allows a full solution to be designed and installed in only a few weeks. Corus has developed specific software that allows a quick customised design, starting from standard modules, whatever the width, length or curvature (convex, concave or reverse). Structural resistance, shape and weight are automatically computed. Thanks to the low weight of the individual components, installation can even be done manually. Each component requires only a one or two person lift. Pre-surfaced modular deck panels can also be proposed or a bespoke finish can be used to enable extensions to fit in aesthetically with existing structures.

Removable and adjustable platform
Modular design and low weight allow the platform to be dismantled and placed in another location if required. The height can be changed by simply altering the adjus table feet. This allows for variation in foundation levels to be readily accommodated within certain tolerances.

Minimum traffic interruption
Thanks to a cantilevered design, the platform can be largely installed in the green zone whilst the line is still open. In that secure area workers can operate while trains are running. Possessions are therefore only required to gauge the platform and lay the final surfacing.

For further information, e-mail: laure.lafare@corusgroup.com or view website: www.corusrail.com   Refer to page 88

New hydrostatic linear guides dampen
loads in high speed machining applications

A new range of hydrostatic linear guides has been developed that combines excellent damping characteristics with the compact dimensions of a profiled rail linear guide.

Following extensive research and development and customer trials, a new range of hydrostatic linear guides is now available from the Schaeffler Group.

The new HLE range of hydrostatic linear guides is ideal for linear motion applications in which high damping characteristics are required and where the damping itself must take place at the point where the load is applied, for example, in high speed machining and high precision grinding applications.

With a demand for increased dynamics and power densities in the machine tool industry, linear guidance systems are now required that offer both high dynamic rigidity and reduced vibration. If machine vibration can be dampened, machine efficiencies can be improved, resulting in higher cutting capacities, higher speeds, improved surface quality and improved machining accuracy.

Unlike conventional ball linear guides or roller linear guides, the hydrostatic guides feature no metal-to-metal contact. The guide carriages move on a thin cushion of high pressure fluid, the end result being zero wear of the guideways. An integral hydraulic controller means the hydrostatic guides are ready-to-fit and the mounting dimensions are interchangeable with monorail guidance systems.

Bad vibes
Vibration in machine tools can be a problem. Vibrations are induced as a result of blade contact shocks, tool wear, regenerative effects and other disruptive forces from outside influences. Due to the large number of 'springs' and 'masses', numerous resonant frequencies occur with, in some cases, strong effects on the accuracy and surface quality of the workpieces. In this case, the lubricant film separating the components in hydrodynamic and hydrostatic guidance systems provides vibration damping by means of the so-called 'squeeze film' effect.

This damps or even eliminates the occurrence of amplitude elevations in the resonant frequencies. The dynamic rigidity of the machine is improved and higher precision is achieved. However, hydrostatic guidance systems have until now been associated with design and economic disadvantages: a larger design envelope is required, increased fitting and adjustment work is needed and costs are therefore higher.

Schaeffler's size 45 (45mm rail width) HLE hydrostatic linear guide, for example, has a damping value of higher than 470,000kg per second. The system operates at 100 bar nominal pressure with an oil viscosity class of ISO VG 46. The flow rate of the carriage is around 1.2 litres per minute. The tensile rigidity almost equates to a corresponding rolling bearing support.

The carriage comprises a steel saddle plate with pressure pockets and two end pieces. At the oil supply side, a corresponding pressure regulation is integrated in the end piece. The second end piece is only for oil recirculation purposes. The design and geometrical dimensions of the contact surfaces of the saddle plate and rails are critical to the performance of the hydrostatic guide.

Bearing life of hydrostatic guides can be considered infinite, as there is no bearing wear, resulting in longer machine life and extended rigidity and precision. Crash protection also improves, because the oil pressure in the pocket increases as the cutting load is applied, creating a restoring force that prevents the fluid gap from closing under very high impact load.

Customer Applications
Extensive tests have been conducted on the hydrostatic guides in numerous customer applications. One of these tests involved evaluating the hydrostatic guide on a three-axis machining centre.

The transverse axis (Y-axis), which guides the main spindle assembly and the Z-axis, was fitted with a size 45 hydrostatic guide. Measuring the deflection showed that the HLE had almost identical values to the roller monorail guidance system, indicating that there were no disadvantages in terms of axis rigidity.

However, on examination of the dynamic resilience in the machine tool centre point (TCP), this revealed a clear reduction in vibration peaks in all axes when using the HLE. This enabled a significant increase in the maximum machining depth. Tests by the customer showed that the cut becomes unstable at a certain machining depth when using monorail guidance systems, with regenerative chatter effects occurring. However, under the same conditions but using HLE guides, the cut is stabilised.

Similar positive results were revealed on workpiece table vibration on a grinding machine. Significant first-order plate vibration was found when excitation occurred in the centre of the workpiece table. When the table was guided using four hydrostatic guide carriages rather than four conventional roller monorail carriages, the resilience frequency measurements showed a significant reduction in vibration amplitudes. The HLE achieved a clear improvement in decay behaviour at the centre of the table. On assessing the results of the grinding by surface measurement, it was found that the HLE optimised both the 'long waviness' and 'short waviness' of the table guide.

To date, most hydrostatic guides have been relatively expensive, time-consuming to mount and require a larger design envelope compared to profiled rail guides. However, the new INA HLE guides are manufactured to fit within the standard design space of a profiled rail linear guide. For machine builders, this ease of mounting means that design and assembly costs can be reduced. And, because the guides comply with ISO/DIN design envelopes and mounting dimensions for monorail guidance systems, a design engineer could, for example, use both a roller guidance system and a hydrostatic guiding element in the same machine design, but for a variety of machine tool performance classes. For further information, e-mail: info.uk@schaeffler.com   Refer to page 11

ARO 65:1 high pressure piston pumps

The ARO Fluid Technologies unit of Ingersoll Rand Industrial Technologies has released newly-designed, high-pressure piston pumps and packages which are ideal for the transfer and supply of medium-to high viscosity materials. The new ARO 65:1 ratio pump is the answer when mastics, inks, sealants, adhesives and other heavy materials are in demand.

The new ARO´s 65:1 chop-check pump packages have been specially designed to handle fluids in excess of 1,000,000 centipoise and pressures up to 515.5 bar.

ARO 65:1 ensures the best levels of durability and reliability. It is equipped with a chrome-plated plunger rod and cylinder that are especially suited to pumping abrasive fluids. What's more, they employ longer strokes that cycle less frequently, delivering the same quantity of fluid with less pulsation than other brands which ultimately prolongs motor life. Finally, a visible solvent cup and adjustable packings minimize downtime and
extend the life of the pump.

To minimize downtime and to ease service, tie rod construction permits quick teardown and repair. Extensive laboratory testing with some of the harshest materials enables ARO a packing design that consistently delivers superior seal wear characteristics. For further information, contact Karina Visciola, e-mail: karina_visciola@eu.irco.com   Refer to page 10