Melt flow compensation in an extrusion apparatus
AssigneeStratasys, Inc.
InventorJames W. Comb
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Abstract
Disclosed are a method and apparatus for matching the extrusion rate of a liquifier which extrudes a flow of material to a predetermined target output rate. The present invention adjusts the volumetric rate of material going in to the liquifier to account for a predicted melt flow component of material being extruded from the liquifier. Compensating for the predicted melt flow results in reduced error in an extrusion profile produced by material deposited along a toolpath followed by the liquifier.
Claims13
In an extrusion apparatus having a liquifier which receives a solid element of a material that exhibits thermal expansion, heats the material, and deposits a flow of the material through a dispensing tip thereof along a predetermined tool path at an output rate, said apparatus using a material advance mechanism to supply the solid element of material to the liquifier at an input rate which controls the output rate, a method for matching the output rate to a predetermined target output rate which is selected to achieve a desired extrusion profile of the material deposited along the tool path, comprising the steps of:
- predicting a melt flow component (QMF) of the output rate for a time step corresponding to a segment of the tool path, the melt flow being a rate of flow attributed to thermal expansion of the material heated in the liquifier;
- and
- commanding the input rate (QiS) for that time step so as to compensate for the predicted melt flow.
An extrusion apparatus comprising:
- a liquifier which receives a solid element of a material that exhibits thermal expansion, heats the material, and deposits a flow of the material through a dispensing tip thereof along a predetermined tool path at an output rate;
- a material advance mechanism which supplies the solid element of material to the liquifier at an input rate (QiS) that controls the output rate;
- a control for providing control signals to the material advance mechanism, the control signals commanding operation of the material advance mechanism so that the input rate compensates for a predicted melt flow component (QMF) of the output rate.
Dependencies are inferred from the claim text.