| 摘要 |
<p>A system (10), valve and method for intermittent jetting of viscous materials, such as solder paste includes a valve (12) with a valve body having a supply passage (50). A valve stem (26) is mounted for reciprocating movement in the valve body between open and closed positions and includes a tapered end (28). A valve seat (30) is positioned adjacent the end of the valve stem (26) and includes a through passage (36) communicating with an outlet passage (40) of the valve body. The end of the valve stem (26) extends into the through passage (36) in the closed position. A positioner device (20) may carry the valve (12) and can move the valve (12) in multiple directions relative to a substrate (18) during a jetting operation. The amount of material jetted from the outlet passage (40) during a stroke of the valve stem (26) can be less than about 25% of the total combined volumes of the through passage (36) and the outlet passage (40).</p> |
