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Acoustic
Command for interior
and exterior grinding machines
Time
reduction of gap grinding :
In exterior grinding, the wheel usually approaches the part to be grinded
with the advance speed of the "roughness" cycle. The difference
in the over-thickness of the parts has consequently a "dead"
time relatively important during which the wheel does not touch yet the
part. But, the GAP Control system allows working with the multiple approach
speed, called "of compensation" up to the point of contact between
the wheel and the part. At the time of contact, the GAP CONTROL command
generates the signal "commuter on roughness".
Security
against collisions :
The positioning of the parts in reference
to the wheel and the approaching of the wheel up to the over-thickness
of the machining is done on an important travel and at elevated speeds,
especially on CNC grinders. Inverted part or coming from another production
or yet an error of programming can lead to dangerous collisions.
The GAP CONTROL device detects the noise coming from the collision and
order the stop of the current movement. The security level is defined
by the response time of the system (10ms) and the breaking travel of the
concerned gage.
Surveillance
of the wheel condition :
When dressing, the GAP CONTROL analyzes the spectrum.
The condition of the wheel is defined by the command of the machine, depending
on the time during which a level of pre-selection reference was surpassed.
The command will then recognize easily when the wheel needs to be changed
due to worn out or damages.
Working
Principle :
When contacting the part, the grinding wheel emits an acoustic signal
in the ultrasonic range up to 200 kHz. This signal will then be amplified
within the frequency zone having the best ratio between the effective
signal and the background noise signal.
Security
devices :
In case of power failure, of the fuse, the transformer or the integrated
redresser, the output relay is in position "commutation sill passed"
It is the same for the probe if it is not connected or if the cable is
defective.
Ultrasonic
probes :
Piezo-electric, waterproof steel box.
- Type
EM 261A
- Cable length 3 to 20m with or
without protection sleeve.
- Support points on the machine: wheel holder poppet
(near the shaft), poppet or counter poppet (near
part)
"Gap
control" Command Unit :
- MOV
4410 with a compact box
- CAS
420 with 19" cassette
Technical
Characteristics :
- Capture
time of background noise : 0.2 s
- Response
time : 10 ms
- Commutation
power :
230 VAC / 2 A or 40 VDC / 2 A
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