Filament drive mechanism for use in additive manufacturing system and method of printing 3d part

A filament drive mechanism for use in driving an elastomeric filament in an additive manufacturing system, the filament drive mechanism comprising:

• a first drive comprising:
• a first rotatable shaft;
• a second rotatable shaft engaged with the first rotatable shaft in a counter rotational configuration;
• and
• a plurality of teeth on each rotatable shaft, and positioned on opposing sides of a filament path with a gap therebetween so as to engage a filament provided in the filament path wherein the plurality of teeth has a land width ranging from about 0.08 inches to about 0.15 inches.

A method for printing a three-dimensional part with an additive manufacturing system, the method comprising:

• providing a consumable material in filament form;
• guiding the filament to a print head having a filament drive and liquefier;
• engaging the filament with filament drive mechanism comprising at least first and second drives spaced a selected distance from each other, each drive comprising:
• a pair of spaced apart filament drive wheels, wherein each pair of the spaced apart filament drive wheels of the at least first and second drives is configured to engage opposing sides of a filament at substantially a same rate, each filament drive wheel pair comprising:
• a first shaft comprising:
• first gear cogs extending around a circumference of the first shaft;
• and
• a first engagement surface spaced from the first gear cogs and extending around the circumference of the first shaft, wherein the first engagement surface comprises a plurality of filament engaging teeth;
• and
• a second shaft substantially parallel to the first shaft, wherein the second drive shaft comprises:
• second gear cogs extending around the circumference of
• the second shaft, wherein the second gear cogs intermesh with the first gear cogs;
• and
• a second engagement surface extending around the circumference of the second shaft, wherein the second engagement surface is spaced from the first engagement surface of the first drive shaft, wherein the second engagement surface comprises a plurality of filament engaging teeth, wherein the first and second shafts rotate in opposing rotational directions;
• a bridge shaft configured to rotatably couple the first drive to the second drive
• wherein one of the shafts is a drive shaft configured to be driven by a motor at a rotational rate selected to advance the filament at a desired feed rate and to cause the other shafts to rotate at the same rotational rate, such that each pair of filament engagement elements will engage a filament in the filament path and will coordinate to advance the filament while counter-rotating at the same rotational rate to drive the filament into a liquefier;
• melting the filament in the liquefier to provide a molten part material;
• and
• extruding the molten part material from the liquefier to print the three-dimensional part.

A method for printing a three-dimensional part with an additive manufacturing system, the method comprising:

• providing a consumable material in filament form;
• guiding the filament to a print head having a filament drive and liquefier;
• engaging the filament with a quad drive, wherein one of the shafts is a drive shaft configured to be driven by a motor at a rotational rate selected to advance the filament at a desired feed rate and to cause the other shafts to rotate at the same rotational rate, such that each pair of filament engagement elements will engage a filament in the filament path and will coordinate to advance the filament while counter-rotating at the same rotational rate to drive the filament into a liquefier;
• melting the filament in the liquefier to provide a molten part material;
• and
• extruding the molten part material from the liquefier to print the three-dimensional part.