Dynamic analysis and DCG for machine tools

Mori Seiki uses finite element methods to model the behaviour of its machines under cutting conditions at the design stage.

Starting from first principles, Mori Seiki uses finite element methods to model the behaviour of its machines under cutting conditions at the design stage.

A vast amount of data collected over many years has enabled the company to accurately carry out not only static, but also dynamic analysis.

By using their experience, Mori Seiki engineers can accurately model and simulate the effects of deformation, vibration, temperature variation and dynamic stress experienced under actual cutting conditions.

The ability to have a true understanding of the machine tools behaviour while in use has a direct impact on the design of the highly rigid, fine structure, mehanite castings, which form the core of the machine.

Tall ribs on the side walls of the bed, improve Z axis rigidity while unnecessarily massive structures are eliminated, allowing 3 point support for the machine during installation.

The benefit for the customer is that the requirement for foundations for the machine is reduced, while rigidity of the machine structure under operating conditions is not compromised.

Mori Seiki has gone a stage further with the introduction of its DCG (Driven at the Centre of Gravity) technology.

The principle behind DCG is that out of balance forces are greatly reduced by moving the machine through the centre of gravity.

This technology makes it possible to apply full force from the start of an acceleration cycle due to the low levels of vibration, enabling the Mori Seiki to accelerate and decelerate far more quickly than conventionally designed machines.

Not only does this result in improved performance, but it also cuts the forces which are trying to distort the structure of the machine.

The advantage is that the effective rigidity of the machine is further increased without adding to the mass or complexity of the structure by simply minimising the forces generated during its operation cycle.

David Banham, Technical Director for Pollard, added, "DCG greatly reduces vibration and allows the Mori Seiki to achieve very high levels of accuracy and surface finish combined with very fast acceleration and deceleration.

Dynamic analysis of the machine structure enables its design to be optimised, removing reliance on an excessively massive bed for rigidity.".

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