Bosch rexroth MCL, Project Planning Manual

Page: 128 / 206

9.14 Length measuring system
9.14.1 General
A linear measuring system is required for measuring the position and the ve‐
locity. Particularly high requirements are placed upon the linear scale and its
mechanical connection. The length measuring system is used for high-resolu‐
tion position recognition and the determination of the actual velocity.
The necessary length measuring system is not in the scope of de‐
livery of Bosch Rexroth and has to be provided and mounted from
the machine manufacturer themselves( tab. 9-10 "Manufacturers
of length measuring systems" on page 121 ).
Fig. 9-28: Classification of linear scales
Particularities of synchronous line‐
ar motors
It is necessary at synchronous linear motors to receive the position of the pri‐
mary part relating on the secondary part by return after start or after a mal‐
function (pole position recognition). Using an absolute linear scale is the opti‐
mum solution here.
9.14.2 Selection criteria for length measuring system
General
Depending on the operating conditions, open or encapsulated linear scales
with different measuring principles and signal periods can be used. The se‐
lection of a suitable linear scale mainly depends on:
●
The maximum feed rate (model, signal period)
● The maximum travel range (measuring length, model)
● If applicable, utilization of coolant lubricants (model)
● Incidental dirt, chips, etc. (frame size)
● the accuracy requirements (signal period)
Manufacturers of length measuring systems
The following selection is exemplary and does not claim to be complete. You
can also use products from other manufacturers, according to the encoder in‐
terface of the used controller.
120/197
Application and construction instructions
MCL Ironless Linear Motors
Bosch Rexroth AG R911330592_Edition 06