Safeline STANDARD SERIES, Инструкция по эксплуатации

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Page 39
Both proximity and photo-electric devices are
available in a slot sensor type construction, which can
be mounted to sit astride the disk. If this technique is
used the disk should be slotted rather than drilled.
Disc Construction
The disk diameter and number of holes/slots can be
determined when the required shift distance of the
speed sensor is known (see following section). If the
required shift distance is 25mm/shift then the hole/slot
pitch of the disk should be designed so the sensor
gives one pulse cycle out for 25mm moved by the
conveyor, see Figure A-2 below.
Hole Pitch = 6.283 x radius / number of holes
Figure A-2
In building the disk, make sure that the solid and gap
width are such as to keep the pulse width and
frequency within the specified limits.
Determining The Required Shift Distance
Of The Speed Sensor
The speed sensor provides digital pulses in relation to
the distance moved by the conveyor. The
incremental distance moved between pulses is known
as the SHIFT distance and is the smallest interval
measurable by the detector (i.e. its resolution).
Table A-1 can be used to determine the shift distance
for your system. Using distance, d, between the
detection and rejection points
(see Figure A-3 below), follow these steps.
1) Find the point on the table where d lies
between the minimum and maximum limits.
If this value lies at more than one point in the
table select the point that corresponds to the
smallest shift distance,
Example.
For, d = 1000 mm (39 inch)
This value lies at four points in the table,
which corresponds to shift distances of
13 mm, 19 mm, 25.5 mm and 32 mm.
Select the smallest value, 13 mm (0.5 inch).
2) Next check that your maximum conveyor
speed does not exceed the limit specified in the
table.
Example.
For, d = 1000 mm (39 inch) and,
Shift Distance = 13 mm (0.5 inch)
The maximum conveyor speed is 38
m/min (125
ft/min).
Shift Distance 6.5 mm
(0.25 inch) 13 mm
(0.5 inch) 19 mm
(0.75 inch) 25.5 mm
(1.0 inch) 32 mm
(1.25 inch)
Detection to
Rejection. Minimum 191 mm
(7.5 inch) 381 mm
(15 inch) 572 mm
(22.5 inch) 762 mm
(30 inch) 953 mm
(37.5 inch)
Distance, d Maximum 635 mm
(25 inch) 1270 mm
(50 inch) 1905 mm
(75 inch) 2540 mm
(100 inch) 3175 mm
(125 inch)
Maximum conveyor
speed 19 m/min
(62.5 ft/min) 38 m/min
(125 ft/min) 57 m/min
(187.5 ft/min) 76 m/min
(250 ft/min) 95 m/min
(312.5 ft/min)