Constant pressure filament driver for extruder heads in three-dimensional object printers
An additive manufacturing system includes a slip clutch coupled to an actuator of a mechanical driver that feeds solid extrusion material into a heater for supplying thermoplastic material to a manifold in an extruder head. A speed of the actuator can be set to enable the actuator to operate at a rotational speed that is slightly greater than the rotational speed of the mechanical mover. This configuration enables the pressure of the thermoplastic material in the manifold of the extruder head to be in a predetermined range no matter how many nozzles are opened in the extruder head.
1. An apparatus comprising:
an extruder head having a manifold within the extruder head that is configured to store thermoplastic material and at least one nozzle fluidly connected with the manifold to enable thermoplastic material to flow from the manifold and be emitted from the at least one nozzle;
a heater having a channel into which a filament of extrusion material can enter and at least one heating element configured to thermally treat the filament of extrusion material in the channel to melt the filament of extrusion material in a portion of the channel closest to the manifold while the filament of extrusion material remains solid in another portion of the channel to form thermoplastic material in the portion of the channel closest to the manifold, the channel in the heater being fluidly connected to the manifold in the extruder head to enable the thermoplastic material to flow from the channel in the heater and enter the manifold;
an actuator having an output shaft;
a mechanical mover operatively connected to the output shaft of the actuator to enable the actuator to operate the mechanical mover, the mechanical mover being positioned to apply a force to the filament of extrusion material prior to the filament of extrusion material entering the channel of the heater and move the filament of extrusion material into the channel in the heater when the actuator operates the mechanical mover;
a slip clutch operatively connected to the output shaft of the actuator to limit a force exerted by the mechanical mover on the filament of extrusion material being moved into the channel of the heater;
a sensor configured to generate a signal indicative of a pressure of the thermoplastic material within the manifold; and
a controller operatively connected to the sensor and the actuator, the controller being configured to adjust a rotation rate of the output shaft of the actuator using the signal generated by the sensor and to adjust a torque set point of the slip clutch with reference to print conditions.
2. The apparatus of claim 1 wherein the print conditions are one or more of a type of extrusion material being moved to the heater, a temperature of the thermoplastic material, a speed at which the extruder head is being moved, and a position of a feature being formed on the object.
3. The apparatus of claim 1 wherein the mechanical mover is a roller.
4. The apparatus of claim 1 wherein the slip clutch is one of a torque friction disc clutch, a magnetic particle clutch, a magnetic hysteresis clutch, a ferro-fluid clutch, an air pressure clutch, or a permanent magnetic clutch.
5. The apparatus of claim 1 further comprising:
at least one valve operatively connected between the at least one nozzle and the manifold, the at least one valve being configured to open a channel between the manifold and the at least one nozzle selectively; and
the controller being further configured to operate the at least one valve to extrude thermoplastic material from the at least one nozzle selectively.
6. The apparatus of claim 1 , the controller being further configured to:
operate the actuator to produce a pressure of the thermoplastic material in the manifold in a predetermined range before the controller operates the extruder head to form an object with the thermoplastic material.
7. The apparatus of claim 1 , the controller being further configured to:
adjust a pressure set point for operating the actuator with reference to print conditions.
8. The apparatus of claim 7 wherein the print conditions are one or more of a type of extrusion material being moved to the heater, a temperature of the thermoplastic material, a speed at which the extruder head is being moved, and a position of a feature being formed on the object.
9. An apparatus comprising:
an extruder head having a manifold within the extruder head that is configured to store thermoplastic material and at least one nozzle fluidly connected with the manifold to enable thermoplastic material to flow from the manifold and be emitted from the at least one nozzle;
a heater having a channel into which a filament of extrusion material can enter and at least one heating element configured to thermally treat the filament of extrusion material in the channel to melt the filament of extrusion material in a portion of the channel closest to the manifold while the filament of extrusion material remains solid in another portion of the channel to form thermoplastic material in the portion of the channel closest to the manifold, the channel in the heater being fluidly connected to the manifold in the extruder head to enable the thermoplastic material to flow from the channel in the heater and enter the manifold;
an actuator having an output shaft;
a mechanical mover operatively connected to the output shaft of the actuator to enable the actuator to operate the mechanical mover, the mechanical mover being positioned to apply a force to the filament of extrusion material prior to the filament of extrusion material entering the channel of the heater and move the filament of extrusion material into the channel in the heater when the actuator operates the mechanical mover;
a slip clutch operatively connected to the output shaft of the actuator to limit a force exerted by the mechanical mover on the filament of extrusion material being moved into the channel of the heater;
a sensor configured to generate a signal indicative of a pressure of the thermoplastic material within the manifold; and
a controller operatively connected to the sensor and the actuator, the controller being configured to adjust a rotation rate of the output shaft of the actuator using the signal generated by the sensor and to detect a clogging of the at least one nozzle with reference to a signal generated by another sensor that is indicative of a pressure in the manifold or a speed of the output shaft of the actuator and adjust a speed of the mechanical mover and a torque set point of the slip clutch in response to detection of the clogging of the at least one nozzle.
10. An apparatus comprising:
an extruder head having a manifold within the extruder head that is configured to store thermoplastic material and at least one nozzle fluidly connected with the manifold to enable thermoplastic material to flow from the manifold and be emitted from the at least one nozzle;
a heater having a channel into which a filament of extrusion material can enter and at least one heating element configured to thermally treat the filament of extrusion material in the channel to melt the filament of extrusion material in a portion of the channel closest to the manifold while the filament of extrusion material remains solid in another portion of the channel to form thermoplastic material in the portion of the channel closest to the manifold, the channel in the heater being fluidly connected to the manifold in the extruder head to enable the thermoplastic material to flow from the channel in the heater and enter the manifold;
an actuator having an output shaft;
a mechanical mover operatively connected to the output shaft of the actuator to enable the actuator to operate the mechanical mover, the mechanical mover being positioned to apply a force to the filament of extrusion material prior to the filament of extrusion material entering the channel of the heater and move the filament of extrusion material into the channel in the heater when the actuator operates the mechanical mover;
a sensor configured to generate a signal indicative of a rate at which the mechanical mover rotates;
a slip clutch operatively connected to the output shaft of the actuator to limit a force exerted by the mechanical mover on the filament of extrusion material being moved into the channel of the heater; and
a controller operatively connected to the sensor and the actuator, the controller being configured to adjust a rotation rate of the output shaft of the actuator using the signal generated by the sensor so rotation of the output shaft of the actuator is maintained at a rate that is greater than the rate at which the mechanical mover rotates.