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Title:
THREE-DIMENSIONAL MODEL MAKING MACHINE
Document Type and Number:
WIPO Patent Application WO/1990/015375
Kind Code:
A1
Abstract:
Apparatus and a method for forming a metal article on a worktable by a welding head with a control program that causes relative movement between the welding head and the table in three dimensions or axes. Shaping is also done with a cutting tool to remove some of the metal in reaching final size. The control program is generated from data collected in designing the article on the computer with CAD software.

Inventors:
GIFFORD, Ernest, I.
Application Number:
PCT/EP1990/000706
Publication Date:
December 13, 1990
Filing Date:
April 26, 1990
Export Citation:
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Assignee:
Galwelat, Michael
International Classes:
B23K9/04; B23Q33/00; G05B19/4099; G05B19/41; (IPC1-7): B23Q33/00; G05B19/41
Foreign References:
FR2569136A1
DE3711470A1
EP0254526A2
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Claims:
CLAIMS
1. Apparatus for forming a threedimensional metal article comprising, in combination: a table upon which said article is formed; a material supplied welding head supported relative to said table; an xaxis servodrive; a yaxis servodrive; a zaxis servodrive; said x, y and z axis servodrives being connected to produce relative threedimensional movement between said welding head and said table; a controller for controlling the operation of said x, y and z axis servodrives for forming said article on said table by deposit of metal by said welding head according to a program defining said article; and means for selectively removing a portion of said deposited metal in defining the shape of said article.
2. Apparatus according to claim 1 wherein said means for removing metal includes a planar cutter having an axis of rotation parallel to said table.
3. Apparatus according to claim 1 wherein said means for removing a portion of deposited metal includes one of a rotating cutter and an EDM electrode. 5 .
4. Apparatus according to claim 3 wherein said means is moved relative to said table in at least one of the x, y and z axis according to said program defining said article.
5. Apparatus according to claim 1 wherein said welding head is an electric welding head and welding material is supplied as a wire constituting the welding head el ectrode.
6. Apparatus according to claim 5 wherein said controller regulates the voltage and amperage applied to said electric welding head.
7. Apparatus according to claim 1 further including a multifaced turret mounting weldrng heads supplied with different welding materials on said faces, and said controller positions said turret to provide the desired welding head.
8. Apparatus according to claim 7 wherein said turret mounts said means for removing metal on one of said faces.
9. Apparatus according to claim 1 wherein said welding head is fed with a plurality of welding wires of different compositions at controlled rates responsive to said controller for providing a desired alloy in the metal being deposited.
10. Apparatus according to claim 1 wherein said x and y axis servodrives are connected to said table for movement of the table in the x and y axis and said z axis servodrive is connected to said welding head for movement of the welding head in the z axis.
11. Apparatus according to claim 1 further includiπq a computer employing a CAD system for designing said article and generating a data file of threedimensional coordinates for use by said controller in the program defining said article.
12. Apparatus for forming a threedimensional metal article comprising, in combination: a table upon which said object is formed; a material supplied welding head supported relative to said table; an xaxis servodri e connected to said table; a yaxis servodrive connected to said table; a zaxis servodrive connected to said welding head; a controller for controlling the operation of said xaxis, yaxis and zaxis servodrives for movement of said 'table in the x and y axes and said welding head in said zax.is for forming said article on said table by deposit of metal by said welding head according to a program defining said article; and means for selectively removing a portion of said deposited metal in defining the shape of said article.
13. A method of forming a threedimensional metal article comprising the following steps: (a) designing the article with the use of a CAD system on a computer; (b) producing threedimensional coordinate data from step (a) to form said article; (c) providing a table upon which said article is formed having a servodrive movable in at least two dimensions ; (d) providing a welding head supported relative to said table and having a servodrive to move said welding head in at least a third dimension; (e) providing a contoller for controlling said table servodrive and welding head servodrive to provide relative movement between said welding head and said table in accordance with the data produced in step (b); (f) depositing metal by said welding head to form said article on said table as relative movement between said welding head and said table is produced in step (e); and (g) selectively removing a portion of the metal deposited in step (f) in defining the shape of said article.
14. The method according to claijn...l3 wherein step (g) is performed with a planar cutting device.
15. The method according to claim 13 wherein step (g) is performed by one of a vertical rotating cutter or EDM electrode under the control of data produced in step (b).
16. The method according to claim 15 wherein steps (f) and (g) are sequentially performed and step (f) is repeated.
17. The method according to claim 13 wherein the welding head provided in step (d) is an electric welding head which melts materials supplied in wire form for depositing in step (f).
18. The method according to claim 17 wherein current, voltage and gap between welding head and metal being deposited are automatically controlled.
19. The method according to claim 18 wherein the rate of depositing metal is controlled by controlling the feed rate of said wire to said welding head.
20. The method according to claim 19 wherein a plurality of wires of different material are fed to said welding head in a controlled manner to produce a desired alloy in the metal being deposited in step (f).
21. The method according to claim 19 wherein a controlled gas atmosphere is supplied to said welding head during the performance of step (f).
22. The method according to claim 19 wherein a coolant is supplied to the welding head during the performance of step (f) to control the temperature of said welding head. 75 .
23. The method according to claim 13 wherein the table supplied in step (c) has heat transfer means to control the temperature of the article being formed in steps i f ) and (g).
24. The method according to claim 13 wherein the article being formed in step (f) is formed as a plurality of pieces on said table and said pieces are joined in accordance with data produced in step (b).
25. The method according to claim 19 wherein at least a portion of said welding head provided in step (d) is rotated under the control of data produced in step (b) to vary the direction from which said metal is being deposited in step (f).
Description:
THREE-DIMENSIONAL MODEL MAKING MACHINE

Background of the Invent on

Field of t e Invention

This invention relates to a three-dimensional model making machine, and, more particularly, this invention relates to a machine for forming a metallic object on a table by the use of a wel ing head and cutter under three-dimensional or three axis automatic control of relative movement between the welding head and table.

Description of the Prior Art

Computer aided design, CAD, and computer aided manufacturing, CAM, systems have been developed to a high degree so that computer software can be used with data input from the designer to design articles and to provide a program to have the articles machined on machine tools. The designer-comDuter operator can see the design he is developing on a cathode ray tube or television monitor as he refines the design.

Systems have been proposed for producing a prototype of the article by creating a data file from the design file, and using the data file to move a working head in a controlled environment in three dimensions about an origination seed and directing a flow of mass particles from the working head. Such a system is described in U.S. Patent No. 4,665,4*52. While it is somewhat unclear as to what compositions can be used for the mass particle ' s, it is

suggested that they can be a plastic material in an ionized atmosphere so that they can -fuse hy their chemical proDerties or by the use of adhesives. Alternatively, the mass particles can be a slurry of high water content in a closed atmosphere cooled to sub-zero temperatures so that the particles will freeze upon impact with one another and the origination seed. At best, this gives the designer a notion of what the article will look like in three dimensions, but it does not yield a prototype which can be used or tested as the finished article will be used.

In another system described in U.S. Patent No. 4,749,347, a body is formed having a predetermined upper surface topology by progressively extruding a plastic material in layers.

In still another type of system described in U.S. Patent No. ' 4,575,330, a three-dimensional object is generated by creating cross-sectional patterns of the object by synergistic stimulation of a fluid medium to solidify the fluid in successive cross-sectional layers. The layers are then moved to form a build-up of a three-dimensional object.

Summary of the Invention The present invention is directed to apparatus and a method of automatically forming a metallic object in accordance with a program defining the article.

Welding technology is highly developed, and the invention uses well-known inert atmosphere, usually argon, electric arc welding equipment where the material from which the article will be formed is fed as a continuous wire electrode. Since the invention is not directed to

improvements in welding, known or new techniques can be used, for example, plasma or ultrasonic welding units can be employed. The metal from which the article is to be formed is heated and melted by the electrical energy supplied to the welding head, and the metal is deposited on a table on which the article or part is being formed.

Servo drives are used to provide relative motion in the x, y and z axes between the welding head and the table. Preferably, the table moves along the x and y axes, by providing a separate servo drive for moving the carriage in the y axis and a separate servo drive moving a slide mounted on the carriage in the x axis. The welding head will also be moved by a separate servo drive in the z axis.

An essential part of the invention is the provision of means for selectively removing a portion of the deposited metal in order to define the final shape of the article. It is well known that whatever type of welding head is used, the metal is deposited in the form of a bead, and metal removal is necessary in evolving the shape of the article. This metal removal means can take the form of a large rotary cutter to remove metal along a given plane or it can take the form of a rotating cutter or EDM electrode which can be moved in one or more axes, commonly in the z axes in the same manner that the welding head is moved.

Various types of metals may be used, and in fact, more than one metal may be used at different portions of the article to provide desirable properties such as a more ductile metal at one point and a harder metal at another point. It will also be apparent that more than one type of

milling cutter or EDM metal removing head may be used. In order to accommodate this, the apparatus of this invention utilizes a tool turret in which the various welding heads and metal remo ing equipment is mounted. A different material supply can he provided for different welding heads on various of the turret faces. It is also contemplated that a single welding head may be supplied with more than one material so that an alloy of predetermined composition may be automatically formed as the metal is deposited.

A controller controls the operation of the x, y and z axes servo drives according to a program defining the article. The controller performs many ancilliary functions such as controlling the voltage and amperage of the welding head power supply, the flow of inert gas, the cooling supplied to the welding head or metal removing means and the table. The controller will also control the positioning of the tool turret for selection of the proper welding head or cutting tool being used at any point in the forming of the article.

The apparatus and method of t is invention is particularly adapted for use with a CAD, computer aided design, computer system so that the data generated in the design of the article can be compiled or manipulated to provide x, y and z coordinates for movement of the servo driv.es. It will be readily apparent that with the flexibility of such a computer system, complex programming of sequential welding and cutting steps can be performed. For example, the article can be formed from separate elements which are formed on the table and then are joined by the -welding head to form a composite article.

D rawi ng

The preferred embodi ents of the invention are illustrated in the drawing in which:

FIG. 1 is a perspective schematic view of the apparatus of the invention showing the various motions that are imparted to the working heads in the form of welding heads and metal removing equipment and the motion imparted to a table upon which the article is formed; and

FIG. 2 is a fragmentary schematic view of a working head shown to illustrate the possible movements that may be imparted to the working head alone.

Detailed Description of the Presently Preferred Embodiment

The system 10 for forming a three-dimensional metal article, shown as a generally cylindrical or tubular part

12 includes a table 14 which is movable in the x axis as shown by arrow 16 and the y axis as shown by the arrow 18.

The y-axis movement can be provided by a carriage 20 mounted on suitable ways, not shown, driven by servo motor 22 through precision lead screw 24. The x axis movement can be prov ded by a slide 26 mounted with suitable ways, not shown, on the carriage 20. Cross slide 26 is driven by servo motor 28 and through precision lead screw 30.

Machine standard 32 mounts tool turret 34 for a rotation iri the x-y plane as shown by arrow 36. Welding head 38 is shown mounted on turret face 102 in a working position to be driven by z axes servo motor 40 and precision lead screw 42 as shown by arrow 44. Welding material is supplied as a wire electrode from spool 46 to the welding

head 38. The metal is deposited from the welding head tip 48 in forming the article 12 on table 14. Inert gas, usually argon, is suDplied from tank 50 throuqh hose 52 to the welding head 38 to pro i e the proper πon-oxydizing atmosphere for the metal being deposited in the formation of article 12. Electrical current is supplied to the welding head from electric power suDply 54 through cable 56.

A computer system 58 supplied with CAD software is used to design the article 12 and to compile data for movement of the x, y and z servo motors 28, 22 and 40 by connections not shown for clarity. The computer is also connected to the motor 61 for movement of the tool turret 34 and to the welding supply 54 by control cables 60 and 62.

Rotary cutter 64 is mounted on a separate carriage 66 movable, in the x axis as shown by arrow 68 in order to remove a portion of the material being deposited by welding head 48 on the article 12 in defining the shape of the article. Carriage 66 can be manually controlled or controlled from computer 58 by connections not shown.

The turret 34 can carry on its tool holding faces several different welding heads containing different materials or types of welding tips. For example, welding head 70 shown fixed to turret face 72 is fed from two spools 74 and 76 of different materials so that an alloy is formed when the metal is melted and deposited in forming article 12. The relative rate of feed of wire from spool 74 and spool 75 can be controlled to vary the composition of the alloy.

A metal removing tool in the form of a ball mill 78 shown on work head 80 mounted on turret face 82. Normally the ball mill 78 will be moved in the z axes as the table is moved in the x, y axes to selectively remove metal that has been deposited in forming article 12 to refine the surface features more precisely. As shown in the fragmentary schematic type of FIG. 2, the work head 84 may be supplied with a spherical bearing 86 so that the cutting tool or welding tip 88 may be turned in any direction as indicated by the arrows 90 and 92 to control the direction in which the cut is being made on the article 12 or the direction in which the metal is being deposited from the welding tip. This may also be under automatic control from computer 58. Likewise, it is possible to supply the work head 84 with carriages or slides that are servo operated to supplement the z motion action imparted to the work head by z axis servo motor 40 and z axes lead screw 42. This is shown by the y axis arrow 94 and the x axis arrow 96. Work head 98 attached to turret face 100 may be an additional welding head or carry an additional cutting tool and additional work heads 102 may carry welding heads or cutting tools or other devices such as a buffing tool to form the article 12 to the shape programmed by computer 58.

It will be apparent that the computer 58 can be programmed to perform many other control functions. For example, data will control the x, y, and z movements of the table and work head respectively by servo motors 28, 22 and 40, but additionally, the speed of each drive is independently controlled. Also, the computer 58 controls

the cooling of the welding heads such as welding head 38 and independently controls the cooling of table 20 by a cooling coil contained within the slide 26 to control the temperature of the article 12 being formed. Gas flow from tank 50 can also likewise be controlled from computer 58, and in fact it can be a mixture of gases that is varied according to a program contained in computer controller 58.