Method and apparatus for dispensing a viscous material on a substrate

Abstract

A dispenser for dispensing a volume of viscous material on a substrate includes a frame, a gantry system coupled to the frame, and a dispenser unit coupled to the gantry system. The dispenser unit includes a housing having a chamber and a piston disposed in the chamber. The piston is configured to move between a pre-dispense position and a dispense position within the chamber. The dispenser unit further includes a dispensing bore configured to receive the piston therein and a nozzle coupled to the housing. A controller is coupled to the piston to control the operation of the piston. The dispenser is constructed such that a volume of viscous material dispensed from the dispensing bore is substantially equal to the volume of the piston entering the dispensing bore when moving the piston to the dispense position. Other embodiments and methods of dispensing viscous material are further disclosed.

1 . A method of dispensing viscous material from a dispenser of the type having a chamber, an opening to deliver viscous material to the chamber, a dispensing bore in fluid communication with the chamber, and a piston movable within the dispensing bore, the method comprising:
 moving the piston in a direction away from the dispensing bore;   delivering viscous material to the chamber through the opening;   moving the piston in a direction toward the dispensing bore;   cutting off the delivery of viscous material by blocking the opening with the piston as the piston moves toward the dispensing bore; and   ejecting a quantity of viscous material.   
     
     
         2 . The method of  claim 1 , wherein the quantity of viscous material ejected by the dispenser is substantially equal to the volume of the piston moved into the dispensing bore. 
     
     
         3 . The method of  claim 1 , further comprising varying the size of the opening into the chamber. 
     
     
         4 . The method of  claim 1 , further comprising varying the amount of viscous material ejected by varying a length of movement of the piston within the dispensing bore. 
     
     
         5 . A method of dispensing viscous material from a dispenser of the type having a chamber, a dispensing bore in fluid communication with the chamber, and a piston movable within the dispensing bore, the method comprising:
 moving the piston in a direction away from the dispensing bore;   delivering viscous material to the chamber through the opening;   moving the piston in a direction toward the dispensing bore; and   ejecting a quantity of viscous material substantially equal to the volume of the piston moved into the dispensing bore.   
     
     
         6 . A method of dispensing viscous material from a dispenser of the type having a chamber, a barrel having an elongated bore formed therein, the barrel being disposed in the chamber, a dispensing bore in fluid communication with the chamber and the elongated bore of the barrel, and a piston disposed within the elongated bore of the barrel and configured to enter the dispensing bore to dispense a quantity of viscous material, the method comprising:
 selecting a barrel to be disposed within the chamber;   selecting a piston to be disposed within the elongated bore of the barrel;   installing the barrel and the piston within the chamber;   moving the piston in a direction away from the dispensing bore;   delivering viscous material to the dispensing bore;   moving the piston in a direction toward the dispensing bore; and   ejecting a quantity of viscous material.   
     
     
         7 . The method of  claim 6 , further comprising controlling a flow rate of the viscous material from the dispenser by causing the piston to dwell for a controlled period of time each time the piston ejects a quantity of viscous material. 
     
     
         8 . The method of  claim 6 , wherein ejecting a quantity of viscous material comprises moving material from the dispensing bore through a small-diameter bore, the small-diameter bore being smaller in diameter than the dispensing bore.