Abstract: A solenoid driver system drives a solenoid, such as a solenoid in a glue applicator or any like apparatus incorporating a solenoid, and which requires control of the solenoid in response to a signal voltage. The solenoid driver system generates a turn on signal that enables the solenoid, such as that of a glue gun applicator, to energize quickly because of a rapid rise solenoid signal. A solenoid driver stage of two switching transistors and two high voltage fast recovery diodes are connected to a control pulse through a high side optical isolator and a high side buffer, and a low side optical isolator and a low side buffer. The low side circuit includes a trigger circuit and a delay circuit connected to a gate along with a free-running oscillator for periodically energizing the low side drive of the circuit in a mode as long as the input signal is energized. This ensures that the amount of current dissipated in the solenoid coil is small.

Abstract: A rotary screen printing apparatus for delivering coating fluid from the inside of a print cylinder through patterned openings onto an adjacent advancing substrate, having a print cylinder support frame, a drive mechanism for rotatably driving the print cylinder, a resilient suspension device for supporting the print cylinder at high rotational speeds, an adjacent radiant heater for generating heat energy for absorption by the print cylinder, an enclosure substantially surrounding the print cylinder and confining the radiated heat therein, at least one infrared sensor for sensing heat emitted from the print cylinder, and a control circuit for controlling the radiant heat energy from the heater in response to the sensed emitted radiant energy, about a manually controlled set point.

Abstract: A rotary screen printing device for delivering coating fluid from the inside of a print cylinder through patterned openings onto an adjacent advancing substrate has a print cylinder support frame, a ring-shaped major idler having its periphery retained in rolling contact supported by several minor idlers near each side member of the support frame for rotation about the print cylinder's axis, a plurality of swiveling hooked torque rods, slidably mounted for axial movement at spaced intervals around each major idler, having a hooked inner end facing the opposite major idler, and a resilient mounting urging the hooked end toward its supporting major idler, and a pair of end rings, each secured in telescoped relationship inside one end of the print cylinder, with notches being formed at spaced intervals in the inner periphery of each ring for alignment with the swiveling hooked torque rods of a major idler.

Abstract: A solenoid valve for controlling the flow of hot melt material such as hot melt adhesive. The valve includes an aluminum body in which is disposed a heater cartridge for supplying heat energy to the body. The body is bored to receive an insert constructed of brass of like material having good heat conductivity and the insert defines a cylindric passage. Extending through the cylindric passage is a valve stem that has an outer diameter less than the inner diameter of the cylindrical passage so that an annular flow path is formed. Hot melt material supplied to one end of the annular flow path flows to a valve seat at the other end of the flow path. The diameters of the cylindric passage and the valve stem are established so that the annular path has a sufficiently small radial dimension (e.g. 0.004 inch) that the hot melt material in the path is rapidly and efficiently heated so that when discharged through the valve seat it will be at a suitable operating temperature.

Abstract: An interface circuit for effecting switchover between plural hot melt material delivery systems so that hot melt material can be continuously supplied to applicators or the like. There are two similar relay circuits which are interconnected so that upon depletion of hot melt material from one system, operation is automatically transferred to another system. The relay circuits each include disconnect contacts for disconnecting the depleted system, transfer contacts for activating the new system, lock-out contacts for preventing operation of the system that is not activated and lock-in contacts for activating the new system without attention by the system operator. The coil of the disconnect relay can be connected to a delay circuit so that deactivation of the depleted system can be delayed by delay interval after activation of the new system. The delay circuit affords a fixed delay interval or a variable delay interval.

Abstract: Apparatus for dispensing thermoplastic material, such as hot melt glue, from a shipping container, such as a 55-gallon drum, including a heated follower and mechanism for urging the follower into the container against the surface of the thermoplastic material. A plurality of groups of conductive fins secured to the follower for transferring heat to the material so as rapidly to heat the material to a flowable condition. Each group of fins includes a plurality of parallel fins which define channels therebetween, the channels being oriented so as to afford fluid flow toward the center of the follower, a location at which the inlet of a pump is mounted in receiving relation to the heated material. The thickness of the fins and the width of the channels are established to expedite heat exchange between the heated follower and the material as well as provide a low impedance flow path for the material.

Abstract: Obstructive formations are mounted within the liquid containing chamber closely adjacent the working surface of an applicator wheel and opposite the path of one or more of the pattern-forming wheels recesss. Escape of air or recirculated liquid from the recesses and its replacement by fresh liquid is thereby facilitated, improving the effectiveness of wheel operation, especially at high peripheral speeds.

Abstract: The present hand gun receives pressurized hot melt adhesive and the like via a heated flexible hose. The operator's handle and the supply conduit for adhesive project in a common plane from opposite end portions of the gun barrel. Although generally parallel, the handle and conduit typically are inclined toward each other and are joined at their ends remote from the barrel, forming a rigid generally polygonal frame with ample opening between the handle and conduit to receive the fingers of a hand gripping the handle. The gun thus completely isolates the operator's hand from the path of supply of the molten material, while still permitting the hose to extend generally downward from the gun in most positions of use. The disclosed configuration further provides a well protected location for the control trigger. An improved safety latch for the trigger is disclosed. The swivel connection between gun and hose provides fully enclosed access for electrical wires.