Nordson Corporation

Robert C Hall

Carl A Bretmersky

Richard G Klein

Stephen L Merkel

Carl N Baron

Ronald J Hartle

A method of controlling and operating a fluid dispensing apparatus is provided which modifies a tool speed signal from a robot and generates a corrected signal to a dispenser nozzle flow controller to compensate for non-linear flow characteristics of fluids, such as non-Newtonian adhesive fluids, to maintain uniform bead size as the tool speed varies. The corrected tool speed signal is generated by computing the ideal flow for the tool speed, comparing the computed flow with actual flow data stored in memory using linear interpolation of data between the stored values, and generating a control signal modified in accordance with the comparison. The stored data is acquired by operation of the apparatus in a calibration mode wherein a series of standard signals is sent to the fluid controller while the actual flow at each signal level is measured and stored in a table. The method corrects for non-linear flow phenomena such as that known as the shear-thinning effect that is flow rate dependent.

Method of compensating for non-linear characteristics in dispensing a

A fluid dispensing control for controlling the dispensing of a fluid by a metering valve through a nozzle onto a workpiece. An initial value of a flow characteristic of the fluid is determined that is correlated to the relationship between the flow rate of the fluid and nozzle pressure. Desired nozzle pressure values are periodically determined by evaluating a model of flow rate of the fluid through nozzle in response to the initial value of the flow characteristic and a desired flow rate value. Thereafter, the control provides command signals to the metering valve as a function of the desired nozzle pressures. A new value of the flow characteristic is determined as a function of the measured volume of fluid dispensed during the dispensing cycle to the measured nozzle pressure. During a subsequent dispensing cycle, the control determines the desired nozzle pressures by evaluating the model of flow rate of the fluid through the nozzle as a function of the new value of the flow characteristic. The process of reevaluating the flow characteristic over successive dispensing cycles as a function of measured volumes of fluid dispensed and measured nozzle pressures, and using those updated values to reevaluate the model of flow rate of fluid through the nozzle, is repeated.

Method of compensating for changes in flow characteristics of a

A method for depositing liquid material onto a workpiece in the form of a deposit having a desired conformation wherein the material is discharged under pressure from the nozzle of a dispensing gun which can be manipulated by a robot to lay the deposit according to a programmed pattern on the workpiece. One or more gas jets are directed toward the material after the material is discharged from the nozzle to impart a desired conformation to the material deposited on the workpiece. The flow rate of the gas jets is controlled in accordance with the liquid flow rate to maintain substantial uniformity of the conformation of the deposit. The flow rate of the gas jets may also be controlled with reference to a tool speed signal which varies according to the relative speed between the nozzle and the workpiece as well as an auxiliary signal the latter of which can be used to selectively alter the conformation of the deposit. The invention further provides a system for avoiding disruption of a desired conformation due to irregularities in the manner liquid material is pumped to the dispensing gun by sensing occurrence of the irregularity and adjusting the flow rate of the gas jets in timed relation to the manifestation of the irregularity at the liquid discharge nozzle.

Method for gas-aided dispensing of liquid materials

A fluid dispensing apparatus having a controller which operates to modify a tool speed signal from a robot and to generate a corrected signal to the dispenser nozzle flow controller which compensates for non-linear flow characteristics of fluids, such as non-Newtonian adhesive fluids, to maintain uniform bead size as the tool speed varies. The corrected tool speed signal is generated by computing the ideal flow for the tool speed signaled, comparing the computed flow with actual flow data stored in a memory using linear interpolation of data between the stored values, and generating a control signal modified in accordance with the comparison. The stored data is acquired by operation in a calibration mode wherein a series of standard signals is sent to the fluid controller while the actual flow at each signal level is measured and stored in a table. The method of operation corrects non-linear flow phenomena such as the shear-thinning effect.

Apparatus for compensating for non-linear flow characteristics in

An apparatus for depositing liquid material onto a workpiece in the form of a deposit having a desired conformation wherein the material is discharged under pressure from the nozzle of a dispensing gun which can be manipulated by a robot to lay the deposit according to a programmed pattern on the workpiece. One or more gas jets is directed toward the material after the material is discharged from the nozzle to impart a desired conformation to the material deposited on the workpiece. The flow rate of the gas jets is controlled in accordance with the liquid flow rate to maintain substantial uniformity of the conformation of the deposit. The flow rate of the gas jets may also be controlled with reference to a toolspeed signal which varies according to the relative speed between the nozzle and the workpiece as well as an auxiliary signal the latter of which can be used to selectively alter the conformation of the deposit.

Apparatus for gas-aided dispensing of liquid materials

An air regulator system using air-piloted valves for controlling a plurality of different air flows in a powder spray system. A control regulator is used to set the flow rates of a plurality of flow regulators, each of which is associated with a particular air flow in the powder spray system.

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Strongsville, OH, United States of America

Robert C Hall