9.12
Requirements on the machine design
9.12.1
General
Derived from design and properties of linear direct drives, the machine con‐
struction must meet various requirements. For example, minimizing of mov‐
ing masses with simultaneous high rigidity should be realized.
9.12.2
Mass reduction
To ensure a high acceleration capability, the mass of the moved machine ele‐
ments must be reduced to a minimum. This can be done by using materials
of a low specific weight (e.g. aluminum or compound materials) and by de‐
sign measures (e.g. half-timbered construction).
If there are no requirements for the highest acceleration, even relative big
mass can be moved. A very rigid coupling of the motor to the weight is a pre‐
condiiton.
9.12.3
Mechanical rigidity
In conjunction with the mass and the resulting resonant frequencies, the ri‐
gidity of the individual mechanical components within a machine chiefly de‐
termines the quality a machine can reach. The rigidity of a motion axis is de‐
termined by the overall mechanical structure. The goal of the construction
must be to obtain an axis structure that is as compact as possible.
Natural frequency
The increased loop bandwidth of linear drives required higher mechanical
natural frequencies of the machine structure in order to avoid the excitation of
vibrations.
To ensure a sufficient control quality, the lowest natural frequency that occurs
inside the axis should not be less than approximately 200 Hz. The natural fre‐
quencies of axes with masses, that are not constantly moving (e.g. due to
work pieces that must be machined differently), change, so that the natural
frequency is reduced as the mass increases.
Mechanically coupled axes
With the stiffness of kinematically coupled axes, it should be taken into ac‐
count that the flexibility of the axes - both the mechanical and the control
components - add up.
If several axes must be coupled cinematically in order to produce path mo‐
tions (e.g. cross-table or gantry structure), the mutual effects of the individual
axes on each other should be minimized. Thus, cinematic chains should be
avoided in machines with several axes. Axis configurations with long projec‐
tions that change during operation are particularly critical.
Reactive forces
Initiated by acceleration, deceleration or process forces of the moved axis,
reactive forces can deform the stationary machine base or cause the fixed
machine base body to vibrate.
110/197
Application and construction instructions
MCL Ironless Linear Motors
Bosch Rexroth AG R911330592_Edition 06
Summary of Contents for rexroth MCL
Page 1: ...MCL Ironless Linear Motors Project Planning Manual R911330592 Edition 06 ...
Page 16: ...8 197 MCL Ironless Linear Motors Bosch Rexroth AG R911330592_Edition 06 ...
Page 52: ...44 197 MCL Ironless Linear Motors Bosch Rexroth AG R911330592_Edition 06 ...
Page 57: ...MCL Ironless Linear Motors 49 197 Dimension sheets R911330592_Edition 06 Bosch Rexroth AG ...
Page 68: ...60 197 MCL Ironless Linear Motors Bosch Rexroth AG R911330592_Edition 06 ...
Page 90: ...82 197 MCL Ironless Linear Motors Bosch Rexroth AG R911330592_Edition 06 ...
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Page 196: ...188 197 MCL Ironless Linear Motors Bosch Rexroth AG R911330592_Edition 06 ...
Page 198: ...190 197 MCL Ironless Linear Motors Bosch Rexroth AG R911330592_Edition 06 ...
Page 204: ...Notes 196 197 MCL Ironless Linear Motors ...