Abstract: A liquid valve particularly suited for dispensing of glue at high repetition rate has a solenoid-retracted pin that normally engages a valve seat to close the valve. Glue under pressure enters the chamber in which the pin operates, close to the valve seat. To seal against the flow of pressurized glue up along the pin toward the solenoid, and also to exert a light valve closing force on the pin, a thin metal bellows member is sealed and fixed to the pin near its lower end, at one end of the bellows, and to a connector within which the pin slides, at an opposite, upper end of the bellows. The geometry of the valve seat and the valve closure end of the pin is such that only a very slight retraction of the valve pin opens the valve sufficiently to deliver glue at full velocity through the valve orifice. The valve is capable of accurate glue dispensing through a wide range of operating pressure.

Abstract: A glue head delivers lines or spots of glue onto a substrate, such as packaging materials, with precision positioning of the glue pattern, with short and balanced on/off compensation times essentially independent of glue pressure, and at high nozzle velocity. Pressurized glue advances into a plenum of the glue head preferably in a horizontal direction, then into a short and low-volume exit tube and through a nozzle, flowing in a direction perpendicular to the inflow direction. Flow to the nozzle is closed by a diaphragm valve comprising flexible elastomeric material which seats against the upstream end of the exit tube. An important feature is that glue actuator pressure is balanced, and smooth operation and glue delivery are achieved, by a rocker arm above the glue valve which, when the valve is closed by pushing the elastomeric material against the glue delivery tube, releases pressure on the glue at an upstream point in the glue plenum.