Procedures for rapid build and improved surface characteristics in layered manufacture

Abstract

Methods for improving layered manufacturing techniques to improve an objects' surface properties and shorten manufacturing time for support structures. One aspect of the invention forms surfaces having reduced or no concavities between layers having improved crack resistance. One method deposits alternate, surface improvement material on each layer near the future location of the main material surface, followed by deposition of the main material, the edges of which conform to the previously deposited and solidified alternate material. In this method, the center of the main material layers can be concave rather than the interlayer regions. Another aspect of the invention provides removable structures to support the deposition of main material. The support structures provide support over main material cavities for depositing the material to form the cavity ceilings, while minimizing the time and material required to build the support structures. Minimized support structures include structures formed as columns supported by the cavity floor and angle braces to supported by the cavity walls. Some supports are supported by the side wall but not the floor, and other by the floor and not the side walls.

Description

RELATED APPLICATIONS [0001] The present application is related to co-pending U.S. patent application Ser. No. ______ [1100.1103101], titled TOOL PATH PLANING PROCESS FOR COMPONENT BY LAYERED MANUFACTURE, filed on date even herewith.FEDERAL SPONSORSHIP [0002] This invention was made with Government support under ______ contract number N00014-94-C-0115, entitled “______”. The Government has certain rights in the invention.FIELD OF THE INVENTION [0003] The present invention is related generally to machine manufacturing of components. In particular, the present invention is related to rapid prototyping manufacturing including layered manufacturing and solid freeform fabrication. BACKGROUND OF THE INVENTION [0004] Using conventional techniques, a desired article to be made can initially be drawn, either manually or automatically utilizing a computer-aided design (CAD) software package. The article can be formed by removing material from material stock to form the desired shape in a machi...

AI Technical Summary

Benefits of technology

[0013] More particularly, the present invention includes methods for forming a mold layer of a second material along the periphery of the object surfaces to be improved. The second material layers can be convexly rounded at the periphery, forming a rounded mold layer to receive the later formed first material. The first material layer can thus form an impression of the second material layer along the periphery of the first material layer. The impression formed along the first layer side face can have a rounded, concave, middle intra-layer region and a convex, inter-layer region where the multiple layers stack together. The inter-layer convexities have superior mechanical strength and superior crack resistance relative to the concave inter-layer regions of the conventionally made parts.

[0016] In the manufacturing phase, the part can be built up, bottom to top, by depositing the secondary and main materials, layer by layer. If secondary material is called for in the current layer, a secondary material nozzle can deposit a bead of secondary material of the desired bead width along the previously calculated path. A main material nozzle can then deposit a bead of main material of the desired bead width and along the previously calculated tool path. The flowable main material, formed along the previously formed secondary mold layers, can form an impression of the mold layers convex edge shape, thereby attaining a concave intra-layer shape and a convex inter-layer shape, where the stacked layers join each other. The secondary material can be later removed, exploiting differential mechanical, chemical, or thermal properties. In a preferred embodiment, the main and secondary materials are not the same, but are the same material in other embodiments. Improved surfaces provided by the present invention can have improved mechanical properties due to the lack of sharp, inter-layer convexities.

Problems solved by technology

In particular, where the stacked bonded layers form the manufactured part side surfaces, the concavities can form sharp crevices having poor properties with respect to crack propagation and fracture.

A large amount of secondary material can be required to build the removable structure, as well as a large build time required to form the secondary material layers.

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