Extrusion apparatus for three-dimensional modeling

• US 6,749,414 B1
• Filed: 04/30/2001
• Issued: 06/15/2004
• Est. Priority Date: 04/30/2001
• Status: Active Grant

• Current Assignee: Stratasys Incorporated
• Original Assignee: Stratasys Incorporated
• Inventors: Batchelder, John Samuel, Bosveld, Michael David, Hanson, Jeffery J.
• Primary Examiner(s): Davis, Robert
• Assistant Examiner(s): Del Sole, Joseph S
• Application Number:
  US09/845,566
• Time in Patent Office: 1,142 Days
• Field of Search: 425/375, 425/174.4, 425/130, 425/131.1, 264/308, 264/401
• US Class Current: 425/130
• CPC Class Codes: B29C 48/023 Extruding materials comprising incompatible ingredients
• CPC Class Codes: B29C 48/03 characterised by the shape of the extruded material at extrusion
• CPC Class Codes: B29C 48/05 Filamentary, e.g. strands
• CPC Class Codes: B29C 48/345 Extrusion nozzles comprising two or more adjacently arranged ports, for simultaneously extruding multiple strands, e.g. for pelletising
• CPC Class Codes: B29C 48/86 at the nozzle zone
• CPC Class Codes: B29C 48/865 Heating
• CPC Class Codes: B29C 64/106 using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material
• CPC Class Codes: B29C 64/118 using filamentary material being melted, e.g. fused deposition modelling [FDM]
• CPC Class Codes: B33Y 30/00 Apparatus for additive manufacturing; Details thereof or accessories therefor
• CPC Class Codes: B33Y 50/02 for controlling or regulating additive manufacturing processes

Abstract

Disclosed is a multi-tip extrusion apparatus and design methodology whereby a single extrusion head having approximately co-planar, fixed-position dispensing tips is used in a three-dimensional modeling machine to deposit multiple types of materials from distinct material supply sources. The tips are spaced apart a distance great enough so that a road of material extruded by a leading one of the tips will cool and shrink from the plane of the tips so that it is not smeared by contact with a trailing one of the tips.

Claims

1. A modeling machine of the type which builds three-dimensional objects by depositing thermally solidifiable modeling material as a road of molten material having a height h into a build environment having a temperature lower than an extrudate temperature of the material, and from an extrusion head that moves at a known speed in a predetermined cross-sectional pattern, comprising:

a first supply of a first thermally solidifiable modeling material, in the form of a continuous filament;

a second supply of a second thermally solidifiable modeling material, in the form of a continuous filament;

a first thermally conductive dispenser carried by the extrusion head and having an inlet for receiving the first supply of the first thermally solidifiable modeling material and a tip for dispensing roads of the first material in molten form, the tip of the first dispenser having a downward face positioned in approximately a z-plane;

a second thermally conductive dispenser carried by the extrusion head and having an inlet for receiving the second supply of the second thermally solidifiable modeling material and a tip for dispensing roads of the second material in molten form, the tip of the second dispenser being maintained in a fixed vertical position relative to the tip of the first dispenser, and having a downward face spaced apart a distance s from the face of the first dispenser and positioned in approximately the same z-plane as the face of the first dispenser;

a thermally conductive body in which the dispensers are carried;

a thermal insulator positioned in the body so as to provide thermal separation between the dispensers;

a means for heating the first dispenser to a temperature at which the first material is flowable; and

a means for heating the second dispenser to a temperature at which the second material is flowable;

wherein the distance s is great enough that a road deposited by one of the tips will shrink due exclusively to cooling during a minimum transit time Δ

t between the tips such that the other one of the tips does not drag across and smear the road.

2. The modeling machine of claim 1, wherein the thermal insulator comprises ambient air that fills a cavity in the body.

3. The modeling machine of claim 1, wherein the thermal insulator comprises a solid material.

4. The modeling machine of claim 1, wherein the road has a thermal diffusivity K_e, and wherein the minimum transit time is characterized by the relationship $\Delta$



 



t=0.3

h2Ka.

5. The modeling machine of claim 4, wherein the extrusion head accelerates and decelerates through a path comprising multiple vertices and the tips have a minimum vertex velocity

v_min and a maximum acceleration a_max, and wherein the spacing s is characterized by the relationship v_minΔ t+1/2a_maxΔ

t²≦

s.

6. In a modeling machine of the type which builds three-dimensional objects by depositing thermally solidifiable modeling material as a road of molten material having a height h into a build environment having a temperature lower than an extrudate temperature of the material, and from an extrusion head that moves at a known speed in a predetermined cross-sectional pattern, the improvement comprising:

a first thermally conductive dispenser carried by the extrusion head and having an inlet for receiving a first thermally solidifiable modeling material and a tip for dispensing roads of the first material in molten form, the tip of the first dispenser having a downward face positioned in approximately a z-plane; and

a second thermally conductive dispenser carried by the extrusion head and having an inlet for receiving a second thermally solidifiable modeling material and a tip for dispensing roads of the second material in molten form, the tip of the second dispenser being maintained in a fixed vertical position relative to the tip of the first dispenser, and having a downward face spaced apart a distance s from the face of the first dispenser and positioned in approximately the same z-plane as the face of the first dispenser;

a thermally conductive body in which the dispensers are carried;

a thermal positioned in the body so as to provide thermal separation between the dispensers;

a means for heating the first dispenser to a temperature at which the first material is flowable; and

a means for heating the second dispenser to a temperature at which the second material is flowable.