Automated system for forming objects by incremental buildup of layers

[54] AUTOMATED SYSTEM FOR FORMING

OBJECTS BY INCREMENTAL BUILDUP OF
LAYERS

[76] Inventors: Fritz B. Prinz, 5801 Northumberland St.; Lee E. Weiss, 6558 Darlington Rd., both of Pittsburgh, Pa. 15217

[21] Appl. No.: 971,308

[22] Filed: Not. 4,1992

[51] Int. CI.' B23K 10/02; C23C 26/00

[52] UJS. CL 228/33; 228/102;

228/215; 228/261; 29/791; 164/46; 156/59

[58] Field of Search 228/47, 261, 215,125,

228/102, 33,43,190; 29/791, 792, 492; 164/46;

118/719, 724, 725; 156/59

[56] References Cited

U.S. PATENT DOCUMENTS

3,156,968 11/1964 White 29/123

4,665,492 5/1987 Masters 264/40.1 X

4,673,075 6/1987 Ueyama 29/791 X

4,752,352 6/1988 Feygin 156/638

4,825,808 5/1989 Takahashi et al 118/719

5,126,529 6/1992 Weiss et al 164/46 X

5,134,569 7/1992 Masters 364/474

FOREIGN PATENT DOCUMENTS 88312323.4 6/1989 European Pat. Off. .

OTHER PUBLICATIONS "A Rapid Tool Manufacturing System Based on

Stereolithography and Thermal Spraying" by Lee E.
Weiss, E. Levent Gursoz, F. Prinz, Paul S. Fussell,
Swami Mahalingham and E. P. Patrick, published by
the American Society of Mechanical Engineers, vol. 3,
No. 1, Mar., 1990.

Primary Examiner—Kurt C. Rowan
Assistant Examiner—Jeanne M. Elpel
Attorney, Agent, or Firm—Buchanan Ingersoll

[57] ABSTRACT

A system and method for manufacturing an article that is formed by the incremental buildup of layers on a work surface contains a material deposition station to deposit the layers. In addition, a plurality of processing stations are employed. Each processing station performs a separate function such that when the functions are performed in series, a layer of the article is produced and is prepared for the deposition of the next layer. An article transfer apparatus repetitively moves the work surface and any layers formed thereon selectively among the deposition station and the processing stations. The article transfer apparatus continues to move between the processing stations until each layer is processed and a completely manufactured article is produced.

19 Claims, 2 Drawing Sheets

AUTOMATED SYSTEM FOR FORMING OBJECTS BY INCREMENTAL BUILDUP OF LAYERS

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method and apparatus for creating a three-dimensional object by the formation of layers of a deposited material.

2. Description of the Prior Art

Several methods have been proposed for creating three-dimensional objects by incremental buildup of thin layers. In our U.S. Pat. No. 5,126,529 we disclosed a method of producing articles by spray deposition using a series of masks to define cross sectional layers which form the article. In the method there disclosed the article is fully formed with an adjacent complimentary material that is removed after the article has been completely formed. Metal tubular shapes have been made by shape melting. Shape melting is a process whereby structural components are manufactured by depositing weld material layer-upon-layer until the desired geometry is achieved. Weld build up operations like shape melting require a preform which is generally a machined piece of metal onto which the first layer of build up is deposited. One example of this type of manufacture is disclosed in U.S. Pat. No. 3,156,968 to W. D. White, Jr.

In nearly all of the prior art methods for forming articles by incremental build up of layers, the article is first fully formed in a forming station. Then the article is moved for subsequent processing such as machining to a finished form. Cubitol in European Patent Application No. 88312323.4 discloses a system for forming plastic articles by applying layers of plastic which are cured and milled before the next layer is applied. As in other prior art layer deposition processes, the equipment used is a dedicated system which cannot be expanded to include other processing stations. In our pending U.S. patent applications Ser. Nos. 07/737,229, now U.S. Pat. No. 5,207,371, and 07/829,767 and our issued U.S. Pat. No. 5,126,529 we teach that it is often desirable to process individual layers before depositing successive layers thereon. Such processing could include heat treatment, shaping or shot peening. Hence, any system which forms articles, particularly metal articles, by incremental build up of layers should have the capability to be expanded to include additional processing stations.

In our issued patent we teach that various heads designed to provide each of the desired operations could be mounted on a movable platform so that each operation could be done without moving the workpiece as it is being made. However, this may not be practical as it will require the creation of specialized equipment. A better approach is to use and customize existing equipment such as computer numerically controlled (CNC) machines to do shaping, a heat treatment oven to provide heat treating as well as other equipment which perform other operations. Such available equipment cannot be used on a cost effective basis without automated handling of the workpiece to repeatedly place and remove the workpiece in each of the selected stations. Although automated systems have been developed which perform single operations on a part as it moves along an assembly line, or which transfers parts from one location to another, there is no system avail

able which provides repetitive movement of the same workpiece into and out of the same operational stations.

SUMMARY OF THE INVENTION

5 We provide a method and assembly for manufacturing an article that is formed by the incremental buildup of layers on a movable work surface. During the fabrication of an article by the buildup of layers, each layer represents a cross sectional slice of a three dimensional

10 object being built and is composed of the desired deposition material. In addition to the deposition material, each layer may also contain a second portion that acts as a complement of the object shape of the deposition material portion and serves as a support structure for

15 the growing object form. The deposition material and support structure material are each applied in a predetermined sequence. In this way, a layered structure is built up which contains the object made of the deposition material surrounded by the complementary mate

20 rial. The complementary material may be a mask or may be a material that is applied adjacent to the deposition material layers.

During the manufacture of an article by the buildup of layers, several operations are performed on the work

25 piece for each layer. Therefore, in addition to a material deposition station, a plurality of processing stations are employed. Each processing station performs at least one separate function The functions could include any combination of shot peening, cleaning, blasting, heat treat

30 ing, shaping, inspection, mask making and packaging. Furthermore, additional stations can be added as desired.

An article transfer apparatus repetitively moves the work surface and any layers formed thereon selectively

35 between the deposition station and the processing stations. This repetitive movement continues until all layers are deposited and processed and a completely formed article is produced. In the preferred embodiment, the means of depositing

40 the layers is by thermal spray deposition. Thus, in this embodiment, the material deposition station would include a thermal spray deposition assembly. The layers could also be deposited by other suitable deposition means, such as by weld deposition.

45 Other details, objects and advantages of the invention will become apparent as the following description of certain present preferred embodiments thereof proceeds.

FIG. 1 is a sectional view of a block of layers of deposition material and complementary material built up on a substrate placed on a work surface to form a tubular article. 55 FIG. 2 is a schematic view of our preferred automated system.

DETAILED DESCRIPTION OF THE
PREFERRED EMBODIMENT

60 In FIG. 1, a cross section of a block containing a tubular article manufactured by layer deposition is shown. The article is formed by depositing layers 14 of deposition material 31 and complementary material 44 upon a substrate 11 positioned on a movable pallet or

65 work surface 12. The material of which the article is fabricated is the deposition material 31. In the present system, any means of delivering the deposition material 31 is acceptable. However, in the preferred embodiment