Nordson Corporation

Gould Inc.

Richard P Price

James W Schmitkons

Charles H Scholl

Stephen L Merkel

Jeffrey S Noss

Jan L Shanaberger

Thomas E Lynch

David P Eastman

John R Askew

An air regulator system for a powder coating system and method of operating the system whereby air regulators constructed with inexpensive, on-off servo control valves are positioned side by side and secured to a common bracket and are operated with a pulse width modulating circuitry that quickly and accurately controls the regulator. The circuitry is carried on a circuit board which is also mounted to the common bracket.

Air regulator control system for powder coating operation

A system for monitoring the flow rate of particulate material entrained within an air stream includes a feed hopper providng a source of the particulate material, and a hose for conveying the particulate material within the air stream. A pump draws the particulate material from the feed hopper and transports the particulate material with the air stream through the hose. A flow meter is associated with the hose and measures the mass flow rate of the particulate material through the hose to provide a first flow indication. A device is associated with the feed hopper and measures the change in weight of the feed hopper over a predetermined interval to provide a second flow indication. A controller corrects the first flow indication from the flow meter according to the second flow indication from the gravimetric device. The flow measurement system provides an accurate and fast responding flow meter by combining the advantages of a fast responding in-line flow meter with the accuracy of a weight measurement system.

Powder coating system incorporating improved method and apparatus for

A method for purging cured and partially cured material from a mixer employed in a system for dispensing two-component reactive polymeric materials, includes, in one aspect, the introduction of a pulsed flow of a flushing material into the mixer to purge partially cured two-component mixture from the mix and thus delay the onset of plugging of the mixer, and, in a second aspect, includes heating the mixer to a temperature between the application temperature and decomposition temperature of the cured components and then introducing flushing material at high hydraulic pressure to discharge cured material from the mixer.

Method for cleaning a mixer

A two-component mixing and dispensing system for mixing and dispensing two-component polymeric materials which react chemically with one another when combined to form a mixture includes a controller for adjusting the pressure at which at least one of the components is supplied to a dispenser dependent upon variations in the parameters which affect the cure time of the mixture.

Method and apparatus for compensating for changes in viscosity in a

Changes in the flow characteristics of a fluid being dispensed from a nozzle under then control of a metering valve are compensated for in order to maintain the volume of fluid dispensed over a predetermined time interval substantially equal to a selected setpoint. The volume of fluid delivered to the metering valve during a predetermined interval is measured and a correction factor based on the difference between the measured volume and the setpoint is calculated. The correction factor is used to generate a driving signal from which a control signal applied to the metering valve is generated.

Method of compensating for changes in the flow characteristics of a

Fluid to be dispensed is delivered under pressure to a dispensing nozzle by way of an infinitely variable valve which is disposed in sufficiently close proximity to the nozzle that very little fluid pressure drop takes place in the region between the valve and the nozzle. A parameter correlated to the rate of flow of fluid discharged from the nozzle is sensed between the valve and the nozzle to generate a flow rate signal from which a control signal is derived by comparing the flow rate signal with a signal representing a desired rate of flow. Where the nozzle is to be moved relative a workpiece for dispensing fluid material thereon, the latter signal may be derived from a signal correlated to the speed of relative movement between the nozzle and the workpiece such as a tool speed signal from the robot.

Method for dispensing fluid materials

Apparatus and method for dispensing fluid material whereby the fluid is discharged from a nozzle onto a workpiece. Delivery of fluid to the nozzle is controlled by a metering valve located in close proximity to the nozzle. The flow of dispensed fluid is sensed by a pressure transducer disposed to sense the pressure drop across the nozzle. The pressure transducer generates a feedback signal which can be applied by way of a closed loop control system to an electropneumatic servovalve which operates a double-acting air cylinder the pressure drop across the nozzle thereby controlling the flow of dispensed fluid in accordance with a driving signal. Where the dispenser is carried by a robot, the driving signal can be correlated to the relative speed between the workpiece and the nozzle to accurately control the amount of fluid per unit length contained in a bead deposited on the surface of the workpiece. Due to the rapid response of the system such precise control is possible even during relatively rapid changes in the relative speed between the nozzle and the workpiece. Also disclosed are means for insuring that the volume of fluid dispensed over a predetermined interval corresponds to a desired setpoint thereby correcting for changes in the intrinsic viscosity of the dispensed fluid as may be caused by changes in its temperature.

Apparatus for dispensing fluid materials

A remote control proportional flow adhesive dispensing gun is pneumatically actuated and electrically controlled. An electric current applied to a magnetic torquemotor rotates a torquemotor arm which displaces the spool of a three-way air valve, admitting air to a control valve stem actuating piston. A constant rate feedback spring directly disposed between the actuating piston and the torque arm of the torquemotor acts to restore the air valve spool to an equilibrium non-flow position as the control valve stem approaches a position proportional to torquemotor control current. The air valve exhausts air from the piston and return springs close the control valve when control signal is removed. A shaped control plug attached to the flow control valve stem varies a control opening linearly as stem position changes. A nozzle opening is selected which coordinates with the greatest possible control opening, such that flow is more nearly linearly proportioned to torquemotor control current across the full range of openings in a constant pressure adhesive supply system. The gun body is electrically heated and thermostatically controlled.

Proportional flow control dispensing gun

A controlled temperature hot melt adhesive dispensing system including three closed loop temperature control arrangements along a flow path for hot melt adhesive extending from an upstream adhesive source to a downstream adhesive dispenser. As disclosed, each closed loop temperature control arrangement includes a comparator which compares the temperature sensed by a temperature sensor with a setpoint temperature to produce a control signal for a heater in the temperature control arrangement. The temperature control loops are located along the adhesive flow path so that the second closed loop temperature controller is upstream from the first closed loop temperature controller; and the third closed loop temperature controller is upstream from both the first and second temperature controllers. A first feedback circuit scales and integrates the control signal from the first location to produce a first feedback circuit output which adjusts the setpoint temperature at the second location. A second feedback circuit scales and integrates the control signal from the second location to produce a second feedback output which adjusts the third setpoint temperature. In this way, the three closed loop temperature control arrangements are cascaded so that the control signals developed are coupled, directly or indirectly, to each upstream closed loop temperature control arrangement.

Controlled temperature hot melt adhesive dispensing system

A solenoid driver circuit for a solenoid-operated fluid dispenser in which a valve is operable to dispense a fluid under the control of the solenoid. The driver circuit receives externally applied turn-on and turn-off signals and energizes the solenoid in response to these signals. The driver circuit is responsive to a turn-on signal to couple a pull-in voltage across the solenoid to pull in a solenoid valve armature. The driver circuit is also operable to sense the level of current in the solenoid. When the solenoid current reaches a preset peak current level, the pull-in voltage is removed from the solenoid and replaced by a hold-in voltage. When the hold-in voltage is applied to the solenoid, the driver circuit is operable to control the level of the hold-in voltage in order to maintain a preselected hold-in current in the solenoid. The driver circuit controls the solenoid current so that it makes a gradual transition from the peak solenoid current level to a steady state hold-in current level. The voltage applied to the solenoid to establish the steady state hold-in current is removed by the driver circuit in response to an externally applied turn-off signal.

Controlled current solenoid driver circuit

A method and apparatus for producing a coherent or extruded output stream of viscous liquid containing a dispersed gas to form a foam. The liquid is pressurized and delivered to apparatus having an internal chamber which presents a flow space for the flow of the liquid through it as an integral stream. A gas is introduced under pressure into the liquid, through an opening to the chamber across which the liquid sweeps, to form an unstable mixture of the gas in the liquid. The gas and liquid mixture is not further pressurized by pumping once the gas and liquid have been contacted, but the unstable mixture is maintained under pressure while it flows from the chamber to a restricted outlet orifice which can be closely adjacent to the chamber. At the outlet the pressure of the gas and liquid mixture is suddenly reduced by forcibly ejecting the mixture through the restricted orifice. A coherent stream of the gas/liquid mixture is produced wherein the gas substantially expands to form a foam.

Method and apparatus for producing a foam from a viscous liquid

A parallel hybrid drive system for self propelled vehicles including a direct current motor-generator having a drive shaft in common with an internal combustion engine leading to a variable speed transmission and a final drive train. The motor-generator has a no-load speed, established by a separate field exciter, below which it drives the shaft as a motor and above which it is driven by the shaft as a generator. Storage batteries are operatively connected to the motor-generator to supply power to it below the no-load speed. The internal combustion engine operates over a small RPM range around its most efficient speed at a power level established by a fixed throttle setting. The transmission is operatively connected to an accelerator and direction selector switch to vary the speed and direction of the vehicle.

Growing community of inventors

Parma Heights, OH, United States of America

Richard P Price