KE-750_MAINTE.pdf - 第97页
Z axis Vacuum Blow Height of part mount Dashed line indicates the change made on KE-750/760 On KE-750/760, to effectively use the blow , the timing to turn off the blow can be set before completion of t he downward movem…
Ejector
Pressure sensor
Filter
Blow SV
Nozzle
Figures indicate the length of the air tube.
Figure 4 KE-730/740 Figure 5 KE-750/760
Figure 5 shows the location of the pressure related parts and the pipe on
KE-750/760. The blow SV is located close to the ejector so that the blow air
directly flows to the ejector. The direction of union Y between the blow SV and
the nozzle is also set so that the blow air hardly flows. In this construction, the
pressure at the ejector side, which is the source of negative pressure, can be
set at normal room atmosphere within the time for the pressure at the nozzle
part becomes normal room atmosphere. The pressure at the nozzle part
therefore is not pulled to negative after turning off blow.
3.8.2.2 Blow operation timing
As shown in Figure 6, vacuum and blow timing when mounting parts is
determined using four mechanism control parameters. Please note the timing
to turn off the blow SV. Condition, W Blow off [n]≦W Place Vac [n] applies to
KE-730/740.
Where:
W Blow off [n]: Time for blow to be turned off before the Z axis moves
upward.
W Place Vac [n]: Time for the Z axis to be held above the board after it
moves downward to the surface of the board.
Therefore, blow continues until the Z axis moves downward completely even if
the blow is turned off quickly. (When W Blow off [n] = W Place Vac [n]) The
blow time cannot be made long, there is almost no effect of blow. (If the blow
time is made long, the pressure at the tip of the nozzle becomes positive.)
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Z axis
Vacuum
Blow
Height of part mount
Dashed line indicates the
change made on KE-750/760
On KE-750/760, to effectively use the blow, the timing to turn off the blow can
be set before completion of the downward movement of the Z axis. In this way,
the blow can be used at high vacuum pressure which is immediately after
turning off the vacuum, and the pressure in the nozzle can be changed from
negative to normal room atmosphere within a short time.
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3.8.2.3 Vacuum and blow timing of KE-750/760
Figure 7 shows the operation timing of each SV of vacuum and blow on
KE-750/760, and the changes in the pressure values at the tip of the nozzle at
that timing.
Vacuum
Blow
Negative pressure
Vacuum level
Atmosphere
Z axis
Figure 7
NOTE:
For Z axis: q is for square chip parts; w is for Melf, aluminum electrolytic
capacitor, network resistor, trimmer, SOT, SOJ, SOP, and PLCC; e is for QFP,
TSOP, BGA, connector, and socket.
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