Support volume calculation for a CAD model

• US 20040006405A1
• Filed: 06/13/2003
• Published: 01/08/2004
• Est. Priority Date: 07/02/2002
• Status: Active Grant

• Current Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Original Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Inventors: Chen, Yong, Kulkarni, Rajeev B.
• Granted Patent: US 6,907,307 B2
• Time in Patent Office: Days
• US Class Current: 700/119
• CPC Class Codes: B29C 2035/0283 Thermal pretreatment of the plastics material thermal after-treatment B29C71/02
• CPC Class Codes: B29C 64/106 using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material
• CPC Class Codes: B33Y 30/00 Apparatus for additive manufacturing; Details thereof or accessories therefor
• CPC Class Codes: B33Y 40/20 Post-treatment, e.g. curing, coating or polishing
• CPC Class Codes: B33Y 50/02 for controlling or regulating additive manufacturing processes
• CPC Class Codes: G05B 19/4099 Surface or curve machining, making 3D objects, e.g. desktop manufacturing
• CPC Class Codes: G05B 2219/49013 Deposit layers, cured by scanning laser, stereo lithography SLA, prototyping
• CPC Class Codes: G05B 2219/49016 Desktop manufacturing [DTM]; Solid freeform machining [SFM]; Solid freeform fabrication [SFF]
• CPC Class Codes: G05B 2219/49038 Support help, grid between support and prototype, separate easily

Abstract

In solid freeform fabrication processes that make use of a removable support material, pre-calculation of the amount of support material needed for a build is difficult (inaccurate or slow) because the digital data for generating the support material is often not generated until the build is in progress. A method is proposed that has been shown to generate rapid and accurate estimates of the amount of both build and support material needed before a build begins, to accurately predict before a build begins when replenishment materials are needed, and to track material consumptions over time.

Claims

1. In a solid freeform fabrication process wherein an object is formed with a removable support material, the process including the steps of a) rapidly and accurately predicting a volume and weight of said support material required to form said object prior to commencing the building of said object, b) predicting when replenishment of said support material is required, and c) tracking consumption of said support material over time.

3. The method of claim 1 wherein the calculation of said sweeping body volume comprises:

a) calculating the x-y extent boundaries of said object, c) mapping an x-y grid of dimension d within said boundaries, c) identifying for each element of said grid the associated z-height of the top most element of the object below the grid, d) multiplying the grid area (d×

d) by the each associated z-height to calculate the volumes of the rectangular blocks, and summing the said volumes of rectangular blocks to calculate the total sweeping volume.

4. The method of claim 3 wherein said dimension d is between 3 and 54 mils.

5. The method of claim 4 wherein said dimension d is between 6 and 26 mils.

2. In a solid freeform fabrication process wherein an object is formed with a removable support material, the process for rapidly and accurately predicting a volume and weight of said support material required to form said object prior to commencing the building of said object, the process comprising a) selecting the location and orientation of said object in the build chamber, b) calculating a total sweeping body volume associated with said object, c) calculating the volume of said object, d) subtracting said object volume from said total sweeping body volume to give a sweeping body support material volume, d) multiplying said sweeping body support material volume by a density of support structure to give a support material weight, and e) adding an estimated weight of waste support material.

6. In a solid freeform fabrication process wherein an object is formed from a build material with a removable support material, the process including the steps of a) rapidly and accurately predicting a volume and weight of said build material required to form said object prior to commencing the building of said object, b) predicting when replenishment of said build material is required, and c) tracking consumption of said build material over time.

7. The process of claim 6 wherein said step of rapidly and accurately predicting said volume and weight of said build material required to form said object prior to commencing the building of the object comprises a) calculating the build material volume of the triangulated STL model of said object from the sum of the signed volume of each tetrahedron formed by a triangle and an original point, b) multiplying said build material volume by a density of build material to give a build material weight, and c) adding an estimated weight of waste build material.