KE-750_MAINTE.pdf - 第98页

3.8.2.3 Vacuum and bl ow 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 t he pressure values at the tip of the nozzle at that timing. Vacuum Blow …

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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As shown in Figure 7, the timing of vacuum off and that of blow on/off are the

same regardless of the part types. However, the parameter values of the

vacuum timer in Figure 6 differ for the part type because, for the Z axis, the

speed to move down and the time to be held differ per part type.

By performing blow control, the vacuum destruction time is shortened from 5 ms

(for KE-730/740 as shown in Figure 1) to 12 ms. As a result, a high vacuum

pressure can be maintained for mounting chip parts immediately before their

mount. For other part types, a high vacuum pressure is maintained until the

nozzle stops at the low position. Then, after releasing the vacuum pressure,

the nozzle is moved upward.