HSD
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6.9.4 Use and technical characteristics of the thermal alarm
The electrospindle is equipped with a bimetallic normally-closed switch, inserted in the electric coils
of the stator, which opens when a temperature that is harmful for the electric coils is reached; the
contact closes automatically when the temperature drops and returns to safe values.
The thermal alarm must be connected to the numerical control, which in turn must stop the
machining operations as quickly as possible and stop the rotation of the shaft of the electrospindle,
if the switch opens.
If the shaft blocks while the tool is still being pushed against the piece being worked, the
bearings of the spindle could break; if you wait too long before moving the tool away
from the piece and stopping the rotation, the stator could be burnt.
6.9.4.1 Technical characteristics of the bimetallic switch:
Power supply
48V DC MAX
Current 1.6A
MAX
Switching cycles
10,000 cycles
Contact breaking time
< 1 ms
Contact resistance (according to MIL R 5757)
< 50 m
Ω
Insulation voltage
2 kV
6.10 ENCODER (OPTIONAL)
6.10.1 General
description
The encoder codes in an incremental system the registered position data with A and B, A negated and B
negated signals.
The signals are in phase quadrature; that is to say the A, B, A- and B- signals are out of phase 90 degrees
between them.
The encoder also provides Zero and Zero negated signals.
The output is taken to the electrospindle “signals connector” (section 4.6.1).
There are three models of encoder available:
•
HSD “Square Wave” type;
•
Bauer “Square Wave” type;
•
Bauer “Sinusoidal” type.
