CA2179922C - Method and apparatus for producing parts by layered subtractive machine tool techniques - Google Patents
Method and apparatus for producing parts by layered subtractive machine tool techniquesInfo
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- CA2179922C CA2179922C CA002179922A CA2179922A CA2179922C CA 2179922 C CA2179922 C CA 2179922C CA 002179922 A CA002179922 A CA 002179922A CA 2179922 A CA2179922 A CA 2179922A CA 2179922 C CA2179922 C CA 2179922C
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- mold material
- machining
- construction material
- mold
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P13/00—Making metal objects by operations essentially involving machining but not covered by a single other subclass
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- G—PHYSICS
- G16—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
- G16Z—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS, NOT OTHERWISE PROVIDED FOR
- G16Z99/00—Subject matter not provided for in other main groups of this subclass
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- Mechanical Engineering (AREA)
- Moulds For Moulding Plastics Or The Like (AREA)
Abstract
A method of forming a three-dimensional object (38) is provided using a combination of molding and machining. In its most basic form, the method of the present invention is achieved by depositing a first layer of mold material (40) onto a support surface (20), machining a first cavity (42) into the first layer of mold material, depositing a first layer of construction material (52) onto the first layer of mold material such that an overlapping portion (52a) of the first layer of construction material fills the first cavity to form a first three-dimensional section of the object and such that a superposing portion (52b) of the layer of construction material covers the first layer of mold material, and machining the superposing portion (52b) to form a second three-dimensional section of the object. A larger object may be produced by repeating such steps in like sequence to form additional three-dimensional sections. In the apparatus of the present invention, control of deposition of materials through dispensers (14, 16) and subsequent machining operations by sculpting means (12) is achieved automatically by a director (24) controlled by a computer system (30) comprised of a microprocessor (34) and a CAD/CAM system (36).
Description
~ 1 METHOD AND APPARATUS FOR PRODUCING PARTS
BY LAYERED SUBTRACTIVE MACHINE TOOL TECHNIQUES
BACKGROUND OF THE INVENTION
This application uvl~D~onds to U.S. application Serial No. 08/361,123, filed December 21, 1994.
Field of the JnYention The present invention relates to a method for Illallura. lulhlg tbree~ i""..l physical structures, in response to computer output, using subtractive tool techniques in a layered fashion. This invention additionally ~ OIl.~ ' a computer-aided apparatus 10 that sequentially sculpts a plurality of layers of two dissimilar materials to construct a desired physical structure in a layer-by-layer manner.
Descri~tion of the Relev~llr Art Traditionally, three~ parts have been produced using subtractive machining methods. In such subtractive methods, material is cut away from a starting 15 block of material to produce the desired physical structure. Examples of subtractive machine tool methods include milling, drilling, grinding, lathe cutting, flame cutting, and electric discharge machining. While these uuuv~llLivual machine tool methods are usually effective in producing the desired part, they are deficient in creating some complex geometries. Such methods are usually best suited for producing Dyu.ul~LIi~,al parts and 20 parts where only the exterior is machined. However, where a desired part is unusual in shape or has internal features, the machining becomes more difficult and often the part must be divided into segments requiring subsequent assembly. In many cases, a particular part cv ~ is not possible because of the limitations imposed upon the tool placement on the part. Thus, the size and .... rv ,.li., of the cutting tool do not permit access of the tool to produce the desired ~v ~ ulaLiull. ~ /, a great deal of human judgement and expertise is typically required to execute ~ullv-llliondl machining processes, making such processes relatively slow and expensive.
Various systems for three fli~--n~inn~l modeling have been proposed and/or developed to overcome the limitations inherent in uv~,.lLiondl subtractive machining methods. For instance, U.S. Pat. No. 3,932,923 to DiMatteo ~ --r' ' the production of a plurality of individual planar elements, corresponding to thin cross sections of the object to be produced, responsive to signals generated from a contour follower. The planar elements are then stacked and physically joined together by various means to form the desired three~ n~ object. This technique has been known to be difFIcult to apply because an u . .,. V./h~h~lill~ number of planar elements may result from high resolution between layers, which may be required for non-uniform three-~imPn~ l objects. The 5 handling of these numerous elements, and the necessity that these elements be precisely stacked to be within tolerances, greatly lengthens production time.
Another method of three ' ' modeling is selective laser sintering, qJluo~.llLdli~., tcachings of which are found in U.S. Pat. No. 4,863,538 to Deckard and in U.S. Pat. No. 4,938,816 to Beaman et al. That method, , ' the deposition of 10 a powder, such as powdercd plastic, in a bounded area to form a powdered layer. This layer, or a selected portion thereof, is then sintered by such means as a laser to bond the affected powder particles of that layer together, thus forming a discrete layer of the three-.liln~ object. Successive alternating steps of powder deposition and sintering occur until the three~:rn~nci~-n~l object is formed. Drawbacks associated with selective layer 15 sintering include the fact that only a limited range of materials can be used and the inherent dangers presented by the production of toxic gases resulting from the reactions with the powder, coupled with a risk of explosion.
Alternatively, powder particles may be bonded together in a layer by use of a bonding agent, such as a ceramic. This process, known as three tlimrnc;~m~l printing and developed at the ~ Institute of Technology by Dr. Emanuel Sachs, is similar to selective laser sintering, except that it ~~Ulltl~UI~' using a printer irlk jet to deposit the bonding agent in a ~ =fl area of a powder layer, rather than using a laser to sinter the particles together.
Both powder-related techniques suffer from a drawback common to all other prior 25 art three-~" I forming techniques, with the exception of the dru-~ ' ~ullv~lAiulldl machining. Namely, such processes are planar in nature, since the parts to be collallu~ ,d are fonned of discrete layers of material. CUII~ U.,ULI.Y, a large number of thin layers are required to form an object within given tolerances.
A three-~imrnci~n~l object may also be formed by ballistic particle ...-...r~.n..;..g, a technique taught in U.S. Pat. No. 4,665,492 to Masters. There, a first particle, ,'( ~ ' as an origination seed and constructed of material such as steel or a ceramic, is placed at the origin of a three--1imrn~ n~1 coordinate system. Working heads emit 2 t 79q22 ~ 3 small particles or droplets of ~ for instance~ a ceramic material ~ according to ~ r~l~ a ~
CUul,'' originating from the seed. These particles bond to the seed and to each other, whereby continued emission of droplets in the ~ d~lr~ ..,' ~l manner ultimately produces the three~ rnpnc;~)n~l object. While a wider array of materials can be used in this 5 technique as opposed to other methods, ballistic particle .., --,.,ri- U.. ;,.~ presents inherent tolerance problems because tolerance is a function of droplet size and droplet po~;Liollill~
accuracy, which is difficult to manage. Full},~l,llul~, the small droplet size (a droplet may be only a few microns in diameter) results in lengthy production time.
The most widely accepted ~ 1 method of producing a three~
object is known as stereolithography, taught in U.S. Pat. No. 4,575,330 to Hull and in U.S. Pat. No. 4,961,154 to Pomerantz et al. In this method, a bath of a photopolymer liquid is contained in a vessel. Generally, layer-by-layer sùlidiru,aliu.. of ,ulr~l I "~i~,r :l areas of the liquid ~hULU~UIYIII~I surface is achieved through sequential exposure to a light source, such as a laser. Discrete layers, each newly-formed layer bonding to an hlul~,didl~ly preceding layer, are formed until the desired three-.li.. ~;.".-~ object is produced. As each new layer solidifies, however, a shrinkage in its volume occurs, causing warpage, which leads to stresses in the formed part. These stresses may cause distortions in the part and thus lead to exceeding tolerances. While Pomerantz et al.
disclose methods of ~ i,.g for the effects of shrinkage, such methods do not 20 prevent shrinkage altogether. Arlr'' "~/, stereolilho~ ,l.y is limited to use of a photopolymer as the material from which the three-rlimpnc~ l object is ultimately formed. Another di ~lv ,, presented by ~ rol;ll~ h,~ is that reactions with yll~ frequently produce dangerous toxic gases.
A modified stereo~ process is taught in U.S. Pat. No. 5,û31,120 to 25 Pomerantz et al. There, a phùlupolylll~l liquid is supplied only in discrete layers, and a supplied liquid layer, or selected portions thereof, is solidirled throughout the entire thickness of the layer, differing from solidifying merely at the surface of a liquid bath, as taught in the ~rulr~. .,li..". d standard s~ /' process. Any u."ulillirl.,d liquid is removed from the layer, such as by ~ ' ~, and resultant voids in the solidirled 30 layer are filled in with a support material, such as wax. The support material is then allowed to solidify, after which time the entire newly-solidirled layer is trimmed to a flat, uniform thickness by such means as a machining unit. After such trimming, subsequent ~ 4 layers are formed in like manner until the three--limPn~in ~1 object is produced. This modifled process presents a greater likelihood that an object thereby produced will meet tolerances, since no temporary support web is necessary, unlike the standard process, where such a web must be constructed for any overhangs of the part and then removed by 5 hand. I~owever, it is still subject to the same dio~lllvduk~ associated with that standard process Moreover, the machine required to implement the modified stereo!hhngr~rhir process is relatively complex and costly, and the rate of object Cu~ u~liOIi is hindered by the additional steps required in this process.
SUMMAI~Y OF THE INVENTION
It is an important object of the present invention to provide a three-~lim~nc;~m~l part production method and apparatus which overcome the foregoing limitations associated with prior art systems.
It is a further object of the present invention to provide a three-.l;,.,~.~;.,,.-~ part production method and apparatus which are not dependent upon resolution of object section 15 thickness to attain a given tolerance for the object.
It is a further object of the present invention to provide a three-~ ;. ":~1 object production method and apparatus which combines molding techniques and machining techniques to illUI~ lly produce the three-dimrncir,n:ll object.
These as well as other objects are ~ h. d by a method of producing a three-20 rl;.. .,- ~ object comprising the steps of depositing a first layer of mold material onto a support surface, machining a first cavity into the frst layer of mold material, depositing a first layer of ~u~ iull material onto Lhe first layer of mold material such that an UV~ portion of the first layer of l_OIl~llUl.liUU material flls the frst cavity to form a first three-rlin ~inn~l section of the object and such that a oU~ JU:~;llg portion 25 of the layer of ~:onOIIu.lion material covers the first layer of mold material, and machining the OU,u"lluu~ g portion of the first layer of ~wlollu~liull material to form a second three-, n~ section of the object.
When additional three-~imrn~inn:il sections are necessary to complete a three-.li.. ,~;.n,~object,theprocessofthepresentinventionuu ~' sequentiallyrepeating 3û the following steps until the object is completely formed: (1) depositing a successive layer of mold material onto an hl"l.r ' '~/ preceding three-dimensional section of the object, (2) machining a ~UII~.oLlUUdil~g cavity into the successive layer of mold material, (3) depositing a successive layer of cu~ uuLiun material onto the successive layer of mold material such that an v._~L~ul);n~ portion of the successive layer of cun,L.u~;Lic., material flls the cù.l~,;.,uo,.di~.t5 cavity to form another three-.l;.,.~ .,.~;.,...l section of the object and such that a ~u~u~,uu~hl~ portion of the successive layer of uull~LIu~Liol~ material covers the 5 successive layer of mold material, and (4) machining the ~U,U.lUoSi.,g portion of the successive layer of col-,L-u~L;oll material to form yet another three-flimrnci~-n~l section of the object.
The di'UI' ~ t;ll J objects of the present invention are also a~o...~uli~h~d by an apparatus for producing a three-~lim~ neir-n~ll object, comprising sculpting means, a director 10 for positioning the sculpting means in a 1~ ,.,;l l area, a mold material dispenser operatively connected to the director, a uull~Llu~Lioll material dispenser operatively connected to the director, and a controller operatively connected to the director, the controller controlling operation of the sculpting means to selectively sculpt mold material and CU.~.,IU~.I;On material.
In general terms, the "layered subtractive machine tool method" ~,UIIi~,lll,U' anew and improved system for making solid objects by ~u~c,,i~,ly machining thin layers, or laminae, of mold and wll~llu~,lioll material. The successive laminae are onn-m~ sllly integrated as they are formed to defne the desired three-.l;~ ;.".~l object. The mold material often provides a sculpted receptacle into which the c, u~,liu" material is 20 deposited, thereby imparting its negative shape to areas of an object which would otherwise be difficult or impossible to machine by conventional means. Additionally, the positive shapes of portions of the object are formed by machining layers of ~ u~lio,.
material.
In a presently preferred ~ .l,ù~' -- by way of example and not necessarily by 25 way of limitation, the present invention harnesses the principals of computer aided design (CAD) in ~.,...l.;..-~;u.. with layered machining, i.e., the use of subtractive machining methods on a layer-by-layer basis for forming three ~lim~nc;~mol objects, to cim~ onCly execute CAD and computer aided ~ .uura~Lu- ..~, (CAM) in producing three-rlimrnci~
objects directly from computer instruction. Intended al,l,lic.lLic).l~ of the invention include 30 sculpting models and prototypes in a ul~lllurh~Lulhl~ system and in a design phase of product d~clo,ul.l~.-L.
21 79q22 ~ 6 The ability to sculpt three tiinlPncinn~l features into each layer makes it possible to work with ~ olls;d.,lAbly thicker slices, thereby reducing ~ Al complexity and CUll~llU-;liull time while increasing part tolerance. Thus, tolerances are not a function of layer thickness but are instead largely dependent on the accuracy of the subtractive 5 machine tool methods. Additionaily, the method of the present invention provides fiexibility in usable materials; for instance, metals, plastics, waxes, woods, polymers, and composite materials, may be employed as UU....Iu.,liUll and/or mold materials. The term "composite material" is intended to generally include any material made from two discrete snhct~nf rc and more specifically is used to denote man-made cnrnroci~pc~ including fiber-reinforced plastics. Composite materials allow a blending of properties of the separate . " ~l,n"~ With specific reference to fiber-reinforced plastics, such composites combine the high strength and stiffness of the fber material with the low weight and fracture resistance of the polymeric matrix.
BRIEF DESCRliPTION OF THE DRAWINGS
The uùll~llu~.liùll designed to carry out the invention will be hereinafter described, together with other features thereof.
The invention will be more readily understood from a reading of the following and by reference to the - , yi-.g drawings fûrming a part thereof, wherein an example of the invention is shûwn and wherein:
FIG. 1 is a perspective view, partly in schematic, of an apparatus ~uu~lluul~ i in accordance with a preferred ~",ho.l;.,.. ~ of the present invention for producing three-.i;,....,.;,.,~ objects;
FIG. 2 is a perspective view of a sphere;
FIGS. 2A-2F illustrate successive stages in the production ûf the sphere illustrated in FIG. 2 according to the method of the present invention;
FIG. 3 is a perspective view of another three-ll;~ UAl object;
FIG. 3A is a sectional elevation view taken along line 3A-3A oi FIG. 3;
FIGS. 3B-3H illustrate successive stages in the production of the object illustrated in FIGS. 3 & 3A according to the method of the present invention;
FIG. 4 is a ~ )~liV~ view of a three-!' ~ object varying slightly from that shown in FIGS. 3 & 3A;
FIG. 4A is a sectional elevation view taken along line 4A-4A of FIG. 4;
~ 7 FIGS. 4B-4E illustrate successive stages in the production of the object illustrated in FIGS. 4 & 4A according to the method of the present invention, said stages being in addition to the stages illustrated in FIGS. 3B-3H.
FIG. S is a p.,.~ view of a hollow sphere;
FIG. 5A is a sectional elevation view taken along line SA-SA of FIG. 5;
FIGS. 5B-5I illustrate successive stages in the production of the object illustrated in FIGS. 5 & 5A according to the method of the present invention;
FIGS. 5J & 5K illustrate alternative methods of removing a void negative;
FIG. 6 is a sectional elevation view of a three-~imrn~inn~l object having a recessed surface; and FIGS. 6B-6E illustrate successive stages in the production of the object illustrated in FIG. 6 according to the method of the present invention.
DESCRIPTION OF THE PR~ EMBODIMENT
Depicting the context in which the method of the present invention is executed, FIG. 1 broadly illustrates an apparatus 10 for producing Lhree-.l; ;.~ objects which is ~ uutl,d in accordance with the preferred l ,l.o.l;--- .d of the present invention.
Generally, apparatus 10 includes sculpting means 12 capable of moving in the directions indicated by arrows 2 and of rotating in the direction shown by arrow 4, a molding material dispenser 14 capable of moving in the directions indicated by arrows 6, a uc)llaL-u.,Liull material dispenser 16 capable of moving in the directions indicated by arrows 8, and a waste remover 18. As will be shown with regard to FIGS. 3E & 3G, dispensers 14 & 16 are preferably operable to dispense a plurality of mold materials and u~ LIul liu materials, ~ ti~",ly.
Mold material dispenser 14 is shown dispensing mold material 22' from its outlet14a. The mold material, as well as c uuLion material, may ~ ,ly be deposited by other means, such as particle beam or particle spray, pouring or spraying of liquids, or deposition of powders for fusing after deposition. The mold material 22' is deposited onto a support surface or platform 20 until an initial layer of mold material 22 is formed.
An example of a mold material is a water soluble wax, such as that sold by YatesInvestment Casing Wax of Chicago, Illinois under the name 550-GOLD SLAB, B4041.
Further examples will be discussed in detail later herein.
2 i 79~22 ~ 8 A first director 24 is operatively coupled to the sculpting means 12 for pu~;Lùn;ll~;
the sculpting means in a ~ ".,;,.. d area, such as area 26 on the top surface 28 of the initial mold material layer 22. Of course, the area 26 may be three-rlimr~ncinn~ thus forming a cavity within the mold material layer 22.
Like the sculpting means 12, the molding material dispenser 14 and the ~,UII;~Il Ul,LiUn material dispenser 16 may also be operatively coupled to the first director 24.
~onn~ctinne between dispensers 14, 16 and the first director 24 are shown at 15 and 17.
Alternatively, dispensers 14, 16 may be u~lùbDIIu-LiY~ly attached to the milling head of sculpting means 12 to constantly move with means 12. Still further, dispensers 14, 16 could be positioned by a separate director, such as second director 25 which, in turn, could be operatively connected to a second controller such that deposition of materials and machining of previously-deposited material layers could occur silllullall.uu~ly.A second director 25, operatively coupled to waste remover 18, may also be provided for directing waste remover 18 in a p,~rl. t.. ,..;". d path, such as 27, for removing 15 waste material in a manner to be discussed in detail herein.
A controller 30, s~h~ irally shown as being operatively coupled to the director 24, controls operation of sculpting means 12 to selectively sculpt deposited layers of both mold material and ~UI~Llu Liul. material.
Sculpting means 12 preferably comprises a three-axis computer Ill~ ally 20 controlled ("CNC") milling machine with tool changing ability, Illallulid~Lu.~d by Bridgeport Machines, Inc. of Bridgeport, (~nnnrrtirllt as Model No. 760/22 DX.
Sculpting means 12 preferably includes a fixture (not shown) for holding a plurality of iut~.~,llà.lgcdblc cutting tools, such as at 32, a cutting tool changer apparatus (not shown), and a cutting motor (not shown) for turning tool 32. To provide quick and efficient 25 production of an object within tolerances, the cutting tool 32 may be: lly changed during operation such that a tool si~ and shape a~lJl UIJI ' ' to the geometry being ~ull~LIu~Ltd may be used. ~or example, a small spherical tool may be a~/lupl for small curved details, a small cylindrical tool may be a~ lu~n forsmall vertical walled details, and a larger tool of an a~ u~l geometry may be used for 30 roughing in of the shape or for areas requiring lesser detail. This ability allows production of parts with area specific tolerances.
g First director 24 preferably comprises a system of stepper motors, worm gears, and linear sliders (not shown) for positioning the sculpting means 12 in three rlim~~ 7nc The type and power of sculpting means 12, the stepper motors, and the cutting motor is dependent upon many factors, and in particular upon the type of materials being dispensed 5 and the desired tolerance of the part being produced. Second director 25 lilcewise comprises a system of stepper motors, worm gears, and linear sliders to move waste mover 18 in a ,UIC~ d path.
The controller 30 preferably comprises a computer which is operatively connectednot only to first director 24, as previously described, but also to second director 25 for controlling waste remover 18. Additionally, by virtue of the ~ : 15 and 17 to the first director 24, controller 30 controls deposition of both mold material and uul~lu~Liu-material. The computer comprising controller 30 preferably illUOl,Ul ' a Illi.lU~,lUCc.,~ul 34 for controlling all of the ~rul~ ' functions and a CAD/CAM system 36 for generating ~lim~nri~n~l data for tlle object to be produced. Cuul~)u.~./cullLIuller 30 is 15 preferably capable of monitoring a position of sculpting means 12 during its removal of extraneous material and is ~IU~, ' with i..rc,.ll..lLiul. indicative of ~ d~tcllllhl~d boundaries of a plurality of three-.l; - .---l sections of the object to be produced.
The production of various examples of three-rlimpncii7n:~l objects will now be described, with reference to the remaining figures.
FIG. 2 illustrates a frst example part, a sphere 38, the ~oll~Llu-Liull of whichinvolves the least amount of steps in a method of the present invention. Sphere 38 is comprised of frst and second three-~ sections 38a and 38b, I~ Livc:ly, these sections being .1; ~d.."..;~l ~d by imaginary equator 39, integrally joined to one another, and formed as described below.
In FIG. 2A, a first layer of mold material 40, ~UII~ JUIIdill~; to layer 22 in FIG.
1, has been deposited onto platform 20 by mold material dispenser 14. The layer 40 is deposiLed on platform 2û either in a solid form or as a liquid which is caused to solidify upon or shortly after deposition. The solill;r~ of this layer may be caused by, but not limited to, thermal, radiation, or chemical methods. A smooth upper surface 41 may be obtained by machining if desired. Vertical walls 21 may be provided on either side of layer 40 to act as a mold material container in c.~n; -- ii.." with platform 20. These walls may be sections of a cylindrical wall or may be walls of a rectangular enclosure. Such '10 ' 2 1 79922 an ~ .",~ lll is particularly desirable where the viscosity of the mold material or uv~tluulion material in its liquid phase is relatively low, or where curing times are relatively long.
.Sl~hseq~Pn~ to the deposition and ~ulidirl~,liù,l of layer 40, subtractive machine tool 5 methods are used to three-fiimpnc;~ iiy sculpt the mold material into a geometry specifed by the computer control system. FIG. 2B illustrates layer 40 as having been machined or sculpted such that a cavity 42 has been formed therein. The depth "d" of cavity 42 is equal to the radius of sphere 38. Waste particles 44 resulting from the machining of cavity 42 are shown to be Iying in the bottom portion thereof.
In the remaining figures to be described, although platform 20 and vertical walls 21 will not be therein shown, it is understood that any initial layer of mold material will be considered to have been deposited upon platform 20 and within vertical walls 21 where desirable.
FIG. 2C illustrates removal of waste particles 44 from machined cavity 42 by waste remover 18. Preferably, waste remover 18 comprises a vacuum head 46 connected to a suitable conduit 48 for conducting the particles 44 in the direction shown by arrow 50.
Second director 25 (FIG. I) is constructed so as to direct remover 18 not only to the area of cavity 42 but also to any upper surface of layer 40, such as surface 41. Alternatively, waste removal may be facilitated by use of a directed air stream which would serve to push any debris off the layer 40. As a further alternative means of removing waste particles, surfaces of layer 40 may be swept by an automated brush. Additionally, if particles 44 are comprised of a metallic material, waste removal may be facilitated by magnetic or cle~llu~ldti~ attraction. Any CVInIJ "nn of the above methods may beemployed to ~rf n~rlich waste removal.
PIG. ZD shows a layer of .on~l~u.liun material 52 as having been deposited upon mold material layer 40. An uv~ g portion 52a of layer 52 is shown as having filled cavity 42, thereby forming first three- ' ' section 38a of sphere 38 (FIG. 2). As used herein, the term "overlap" and variations thereof, as ~ ,. J from the prior art "discrete level" l~llllhlulv~y~ mean that the deposition or machining of mold or~v~ l u~liu~ materials may occur below elevations of upper surfaces of previously deposited layers. For specific example, following deposition of layer 40, subsequent process steps were not directed merely to areas at or above elevation "e" of surface 41 of layer 40: machining of cavity 42 to depth "d" (FIG. 2B) occurred below elevation "e", and a portion of the ' ~ 'S,-added .v~ u~,liuil material layer 52 flowed below elevation "e", into cavity 42.
Additionally shown in FIG. 2D, a DU~ JOD;llg portion 52b of layer 52 is shown 5 to cover layer 40. As used herein, the term "cover" and variations thereof mean that one DUIJl..l~)OD;llg layer need only interface with a segment of the upper surface of another layer.
For specific example, although FIG. 2D shows the width w' of layer 52 extending the full width w of layer 40 for simplicity of i" , thus showing an interface between layer 52 and the full length of surface 41, such a width magnitude is not always necessary.
10 Depending on the dimension of the next three-riimpnci~\n:ll section to be produced, width w' may be less than width w. All that is required for layer 52 to "cover" layer 40 is that there be an interface between layer 52 and a portion of upper surface 41 of layer 40.
An imaginary line 51 is shown in FIG. 2D for purposes of illustration to divide the ~ul~llu~Liull material layer 52 into the portions 52a, 52b. The c,ull~Lluuliull material layer 15 52 may comprise a ".~ le wax, such as that sold by Yates Investment Casing Wax of Chicago, Illinois under product number B-3096. It is ~Oll'C ~ ' ' however, that other uul~ uDiliùns may be used as ~vllDllu liull material, so long as such c.. ~po~;li....~ possess suitable physical strength, stiffness, flexibility, and resistance to thermal .irE",.,I I j~n FIG. 2E depicts the machining of DUI/..I,UU~ S portion 52b of l,UllDllUUIiUll material layer 52 by sculpting means 12, thereby forming the second three-~lim~ ncin~ ~ section 38b of sphere 38. Upon completion of this machining step and after any necessary removal of waste particles in the manner described with regard to FIG. 2C, the completed sphere 38, partially encased in the mold material layer 40, emerges, as shown in FIG. 2F.
Mold material removal is performed following completion of the last three-25 ~ ;n,.l section of an object. The molding material 40 may be removed, or separated from sphere 38, physical means, radiation (electrical, UV, thermal, ultraviolet, etc.), ultrasonic, vibration, electrical induction, or other means or methods such that the ~ollallu.liu.l material is not comprised. FIG. 2F illustrates an early stage of mold material removal, wherein a heating device 54 begins to reduce layer 40 to a liquid mass 40a.
Complete removal of layer 40 results in an isolated completed sphere 38 (FIG. 2).
Although removal of the mold material layer 40 is shown for purposes of illustration in FIG. 2F as being ~ ", ~ h ~l by the heating device 54, it must be kept in mind that such 2 ~ 79922 ~ 12 means would not be used where the layer 40 is a water soluble wax and where the ~VII~UU~liUII material layer 52 is a ~ ,le wax, since these materials possess similar melting points. Instead, removal of such mold material would be d.uull,~ l merely by dissolving the mold material in water.
It is understood that all machining steps ' 7l 1Pntly mentioned herein will be considered as having been performed in like manner to the machining steps described with regard to FIGS. 2B ~ 2E. It is additionally understood that any s l~c-, 'y described step of mold material removal will encompass the means discussed with regard to FIG. 2F. Moreover, although waste particle removal will not be discussed with regard to the remaining figures, it is understood that waste removal according to the means discussed with regard to FIG. 2C may occur subsequent to machining of any layer of mold or cu~ u.Livl, material and before the deposition of a subsequent mold or ~vu~LIu~,lio material layer.
The method of the present invention may be employed to produce three-~l;, . ,. . , -l objects possessing a more complex shape than that of the sphere 38 of FIG. 2. For instance, FlG. 3 illustrates a rounded barbell-shaped three~ object 56 comprisedof a neck portion 58 i~,.,: -'i,.~ in end members 60, 62 at either end thereof.
As seen in FIG. 3A, object 56 may be subdivided into several lnt~ t~. ' three-~irnPncion:ll sections 56a, 56b, 56c, and 56d. The thickness and placement of these sections are parameters which are Inu~ Idullllcl into CAD/CAM system 36 of computer 30 (FIG. 1), and these parameters may vary according to the desired object ~.l, -- .., t~ 1 i. C
such as materials, tolerances, and speed of uull~LIu~liuu. As seen in FIG. 3A, the n(~mrn~;tinn of sections 56c, 56d differs from that of sections 56a, 56b. It is also seen that if object 56 were to be wholly produced by ~u.lv~..llivndl machining lerhnirlllPs, an 25 operator would have difficulty in properly positioning a tool below the u.~,lL~n~illg shape formed by end member 62. Thus, only section 56d could be produced in such a manner without ~ U ' illlj; significant dimculty.
In FIG. 3B, a first layer of mold material 64 has been deposited onto a support surface in the same manner described with regard to FIG. 2A. Additionally, a first cavity 30 66 is shown as having been machined into layer 64.
In FIG. 3C, a frst layer of cuu~llul,lion material 68 is shown as having been deposited onto the first layer of mold material 64. An uv~,.la~ illg portion 68a of layer ~ 13 68 is shown as having filled the first cavity 66, thereby forming first three~
section 56a of object 56 (FIG. 3A). Additionally, a :~U~ V~hlg portion 68b of layer 68 is shown to cover mold material layer 64. An imaginary line 61 is shown for purposes of illustration to divide the first ~o.~ u~liun material layer 68 into the portions 68a, 68b.
FIG. 3D depicts sculpting means 12 machining ;.. l~.,uosh-g portion 68b of the first ~:UII~IlU~iUn material layer 68, thereby forming the second three-~l;..,..,~;...,..l section 56b of object 56. The outline of the portion of section 56b yet to be formed in FIG. 3D is shown in phantom lines. The height of section 56b illustrates that an object produced by the prvcess of the present invention need not be formed in a plurality of equally-thin planar 10 sections, as required by prior art processes, thus greatly increasing the speed of production. To provide a smooth surface to facilitate further cu,.~L.uuliu.., upper end 69 of section 56b may be further machined using any tool which levels the surface of end 69.
Referring to FIG. 3E, a second layer of mold material 70 has been deposited on the first layer of mold material 64 such that the second layer of mold material 74 15 completely covers the second three-~' ' section 56b. As seen from the cross hatching in the region l~ uLi--g second mold material layer 70, that layer is shown to be of a cu.l-l)u~ilion differing from that of the first mold material layer 64. Differing f.,,.,l.h~;lio--- between mold material layers may not always be necessary; however, conditions may require differing ~ ;v~ in some instances, and the process and 20 apparatus of the present invention provides the flexibility to ~ r~m~ h deposition of differing u o---~v~;Lions. For instance, the cunll)va;Lion of the first mold material layer 64 may be that of a water soluble wax, while that of second mold material layer 70 may be a ceramic. To provide a further example, first mold material layer 64 may be onerV .. I~ .n of a ceramic, while the second mold material layer 70 may be another25 rv~u,uldlio" of a ceramic. Any differing romrf~ nn may be used for a mold material layer, so long as that "~ t~ n possesses the desirable properties discussed previously and so long as that nnmr~ is compatible with the uu~ lu~,lioll material which will interface with it. The term "compatible", as used herein to dcscribe I~J.lLivl~ ) between mold and cul~Llu-Lioll materials, generally means that removal of mold material interfacing 30 with a given section of CUII~LIu~,Liull material will not damage or impair that ~ullaLIu~.Liu material section.
FIG. 3F illustrates a second cavity 72 as having been machined into the second mold material layer 70.
In FIG. 3G, a second layer of COI~Ilucliu~ material 74 has been deposited onto the secûnd layer of mold material 70 such that an UV.,I; rr lg portion 74b of second5 UUII~llUCliUII material layer 74 fills second cavity 72 to form the third three~
section 56c of object 56 (FIG. 3A) and such that a ~U~ /ODillg portion 74b of layer 74 covers the second layer of mold material 70. An imaginary line 71 is shown for purposes of illustration to divide the second ~ U iiUl- material layer 74 into the portions 74a, 74b. As shown by the shading in the area lC~Jl..,.,lltillg the second layer of UOII~lUC~iUII
10 material 74, that layer is of a ~ " differing from that of the first layer of cu ~ ;n.. material 68 (FIG. 3C), from which the first and second three-.li..,~"~sections 56a, 56b have been formed. For example, the frst layer of coll~llucliull material 68 may be a ~ IC wax, as previously indicated, while the second layer of cul~llucliull material 74 may be an epoxy or a photopolymer. Cuu~u~uLly, the finished 15 object 56 may be comprised of non-l~, 'L '"' - material. Various culllLJu~;liù.~ may be used for a cul~llu.,Liul~ materials, so long as such ~...l.n~ are sufficiently, ' ' l when in solid form and so long as they are compatible with the . ' ~ mold material.
FIG. 3H depicts sculpting means 12 machining ~UIJ~,l,U(J:~illg portion 74b of the second~u..~llucliullmateriallayer74~therebyformingthefourththree-1l;~" ~ section2û 56d of object 56. The outline of the portion of section 56d yet to be formed in FIG. 3H
is shown in phantom lines. Further machining may be performed, if necessary, to level the top surface 75 of section 56d. Following the step shown in FIG. 3H or any such final machining, the mold material layers 64, 70 may be removed by any of the techniques discussed with regard to FIG. 2F which are suitable for the particular mold material 25 ru~ J~;li,.~ used. The removal of the mold material layers exposes the completed object 56 (FIG. 3).
The steps described with regard to FIGS. 3B-3H may be sequentially repeated to produce additional three-~ llAl sections until a larger object is completely formed.
For instance, FIGS. 4 & 4A illustrate another three-~l~rAPn~innAl object 76 which is comprised of object 56 (FIG. 3) and a raised inverted conical member 78 disposed upon upper surface 75. Member 78 is subdivided into two three-.l.. ~;n., l sections which, since object 56 was shown to have four sections, are fifth and sixth threc-~lirA.- ncinnAAI
sections of object 76, namely ffth three~ i"".l section 76e and sixth three-.l;, .... ,~;....~1 section 76f. As with object 56, the thickness and placement of these sections are parameters which are programmed into CAD/CAM system 36 of computer 30 (FIG.
1), the parameters being variable as previously described.
In FIG. 4B, a successive layer of mold material is shown to have been deposited onto an i ' 1y preceding three- li.~ iùnal section. Specifically, a third layer of mold material 80 is deposited onto the second layer of mold material 70, and layer 80 is seen to completely cover the i.. ~,Ji2ll~1y preceding completed three- li~ ;vllal section 76d (cullc~vllJi-lg to section 56d in FIG. 3A).
FIG. 4C illustrates a Lullc~JullJhlg cavity 82 as having been machined into the vhird layer of mold material 80.
In FIG. 4D, a successive layer of cull~llu~liùn material is shown to have been deposited onto the successive layer of mold material. Specifcally, a third layer of CWI~llucliull material 84 has been deposited onto third layer of mold material 8û such that an uv~ ri hlg portion 84a of layer 84 flls the CUllC~tJol-Uillg cavity 82 to form ffth three-,' l section 76d and such îhat a, ~/..tJV~hlg portion 84b of layer 84 covers the third layer of mold material 80.
FIG. 4E depicts sculpting means 12 machining :~U~ lU~illg portion 84b of the third cv~ u~liu-- material layer 84, thereby forming the sixth three-~ Pne~ section 76f.
20 The outline of the portion of section 76f yet to be formed in FIG. 4E is shown by a phantom line. Following any necessary final surfacing and removal of mold material layers 64, 70, and 80, the completed object 76 (FIGS. 4 & 4A) emerges.
The process of the present invention may also be used to produce hollow three-objects, the term "hollow" including any finished three-~ qnci~mAl object 25 which possesses at least one void at any point within its volume.
FIGS. 5 & 5A illustrate a hollow sphere 86 comprised of first and second three-AI hollow sections 86a and 86b, respectively, which are ù~,..-~u ' by an imaginary line 91. The internal walls of sections 86a, 86b form an enclosure 88 to defne a void 90.
In FIGS. 5B & 5C, one layer of mold material 92 has been deposited, and a first cavity 94 has been formed into layer 92.
~ 16 Moreover, excess mold material is machined away so that mold material layer 92 has level upper surfaces such as at 95.
FIG. SD illustrates one layer of ~.UII:~IlU~,liUll material 96 having been deposited onto mold material layer 92 such that layer 96 fills the first cavity 94.
In FIG. 5E, e uuliull material from layer 96 which was above the elevation of surface 95 has been removed. F~..lh..l~llul~;, a second cavity 98 has been machined into the remaining U~,liUII material layer 96 to form first hollow three-~' ' section 86a of hollow sphere 86.
FIG. 5F illustratcs another layer of mold material 100 having been deposited onto the one mold material layer 92 such that an u .. ,1': p~ ~ ,, portion lOOa of layer 100 fills the second cavity 98 to form a first portion 102a of a void negative and such that au~ 6 portion lOOb of layer 100 covers layer 92 and the first three~
hollow section 86a. Imaginary line 91 divides the mold material layer 100 into the portions lOOa, lOOb.
FIG. SG depicts sculpting means 12 machining . . ~ portion lOOb of the mold material layer 100, thereby forming a second portion 102b the void negative 102.
The outline of the portion of void negative 102 yet to be formed in FIG. 4E is shown by a phantom line.
In FIG. 5H, another layer of cul~lluuliull material 104 has been deposited onto the one layer of mold material 92 such that the layer of u~,liull material 104 completely covers the second portion 102b of void negative 102.
Referring to FIG. 51, layer of UOll~llU~liUn material 104 is shown being machined by sculpting means 12 to form the second three-~ hollow section 86b of hollow sphere 86. The outline of the portion of section 86b yet to be formed in FIG. 5I is shown by a phantom line. It is seen that hollow sections 86a, 86b form the enclosure 88 P... ~ a ~ g the void negative 102.
FIGS. 5J & SK disclose alternative methods of removing void negative 102 from enclosure 88 so as to produce the void 90 (FIG. 5A).
In FIG. SJ, a vent 106 is shown as having been inserted through second three-~ hollow section 86b. A conduit 108 ~" with the outlet of vent 106 at one end and with a vacuum source 110 at another end. Activation of source 110 causes the void negative material 102', which must be in a liquid or gaseous state, to escape from enclosure 88 in the direction indicated by arrow 112. If necessary, the void negative 102 may be partially dissolved prior to evacuation. Such dissolution may be effected by a solvent which, depending upon the . ~ n of Ihe void negative 102, may be such liquids as water or kerosene.
In FIG. 5R, which illustrates a therrnal method of void negative removal, a different void negative material 102" is shown, since for such a method the material 102"
must have a lower melting point than the material comprising mold material layer 92.
Moreover, FIG. 5K illustrates the second three-dimpn~inn~l hollow section 86b as having been formed of a porous material, such as a porous ceramic, as shown by a plurality of pores 114, the relative diameters of which are ~ ,r ~t d for purposes of illustration.
The hollow sphere sections 86a & 86b, mold material layer 92, and the material 102" are subjected to a heated ~llvilu~ lL such as that defined by enclosure 116. Heatingcontinues, causing material 102" to boil and reach a vapor state, whereafter the vapor escapes through the plurality of pores 114 and into the c~uvilvll~ L 117 in the manner indicated by arrows 118.
Void negative 102 may also be removed by a modified process including steps illustrated with respect to both FIG. 5J & 5K. Specifically, a heated ~llvilulllllCllL may liquify the void negative 102, whereafter the material is evacuated via a vent though a three-/l; n.. ~i.. ~l section.
For purposes other than that shown in FIG. 5K, .llvhulllll.llL 117 need not be limited to a heated .llvhulllnc.lL. For illustrative examples, it may be advd..t~ ,uus to cool that .llvhulllll~,llL so as to cause rapid sùlilliri.dLiull of waxes or to flood the .llvhu~ ..lL
with an inert gas to prevent unwanted byproducts from process steps performed upon mold or u~,Liun material.
The process of the present invention may also be used to produce a three-d;"....~, ' object having a recessed surface, such as the object depicted in cross section in FIG. 6, where a three--lim~nsin ~l object 120 is shown having a recessed surface 122.
Surface 122 forms an arcuate indentation with respect to the plane containing either or both of lower planar surfaces 121 and 123. The sequential steps executed to produce 30 object 120 are described below.
FIG. 6A illustrates a layer of mold material 124 as having been deposited.
FIG. 6B depicts sculpting means 12 machining the mold material layer 124 to form a iuLulub~dll~c 126 which, though shown as having a rounded or h~,...;~,)ll..;udl shape, can assume any shape, depending on the shape of the ~Ull~aLJU~ g recessed surface in the object to be produced. In FIG. 6B, iuluLulJ~Idll ~ 126 thrusts outwardly with respect to L~ uu.,diillg upper planar surfaces 124a, 124a' formed by the machining of layer 124. The S outline of the portion of iuluLubcldllLc 126 yet to be formed in FIG. 6B is shown by phantom lines.
In FIG. 6C, a layer of ~,uuaLluuLiOll material 128 is shown as having been deposited onto the layer of mold material 126 such that layer 128 is seen to completely cover i''l' dll.C 126.
As seen in FIG. 6D, machining of the uollal~uL liuu material layer 128 by sculpting means 12 then occurs such that object 120 begins to emerge, the ~ pl~t~d portion of which is lLi~lL,.~ilt~.d by phantom line 129.
FIG. 6E depicts the removal of machined mold material layer 124. Mold material layer 124 is submerged into a solvent 130, which is contained in vessel walls 132 and 15 which may be water if the mold material is a water-soluble wax. As seen in FIG. 6E, former layer 124 is shown as having been partially dissolved into a material mass 124'.
Continued s ' -~ ~-- results in complete removal of tbe mold material. It is to be again understood that mold material removal may take place by any of the techniques discussed with regard to FIG. 2F which are suitable for the particular mold material uulllpuailiulia 20 used.
Due to the shape of object 120, in which no overhangs are present, only one arplir~ition and machining of a r UL liun material layer need occur, such that the only three-(l;'- .I~;I~IIAI section produced is the entire object 12û itself. It will be aiu"l~ l, however, that objects of different cwirli,u,dliulia, such as those with both overhangs and 25 a recessed surface, can be produced by a L.lll hjl lj,"~ of the steps described with respect to FIGS. 6A-6E and preceding figures such that a plurality of three-11;.. ~ sections may have to be formed.
As the foregoing description is merely exemplary in nature, being merely illustrative of the invention, many variations will become apparent to those of skill in the 3û art It is to be iuAliiuulL.ly understood that the process steps l~a~ Li~l.y described in FIGS. 2A-2F, 3B-3H, 4B-4E, SB-SK, and 6A-6E may be combined in any sequence to produce three-~' l objects possessing widely varying external and internal * 19 c~ r~ a~ Such variations are included within the spirit and scope of this invention as defined by the ~ollowing appended claims.
BY LAYERED SUBTRACTIVE MACHINE TOOL TECHNIQUES
BACKGROUND OF THE INVENTION
This application uvl~D~onds to U.S. application Serial No. 08/361,123, filed December 21, 1994.
Field of the JnYention The present invention relates to a method for Illallura. lulhlg tbree~ i""..l physical structures, in response to computer output, using subtractive tool techniques in a layered fashion. This invention additionally ~ OIl.~ ' a computer-aided apparatus 10 that sequentially sculpts a plurality of layers of two dissimilar materials to construct a desired physical structure in a layer-by-layer manner.
Descri~tion of the Relev~llr Art Traditionally, three~ parts have been produced using subtractive machining methods. In such subtractive methods, material is cut away from a starting 15 block of material to produce the desired physical structure. Examples of subtractive machine tool methods include milling, drilling, grinding, lathe cutting, flame cutting, and electric discharge machining. While these uuuv~llLivual machine tool methods are usually effective in producing the desired part, they are deficient in creating some complex geometries. Such methods are usually best suited for producing Dyu.ul~LIi~,al parts and 20 parts where only the exterior is machined. However, where a desired part is unusual in shape or has internal features, the machining becomes more difficult and often the part must be divided into segments requiring subsequent assembly. In many cases, a particular part cv ~ is not possible because of the limitations imposed upon the tool placement on the part. Thus, the size and .... rv ,.li., of the cutting tool do not permit access of the tool to produce the desired ~v ~ ulaLiull. ~ /, a great deal of human judgement and expertise is typically required to execute ~ullv-llliondl machining processes, making such processes relatively slow and expensive.
Various systems for three fli~--n~inn~l modeling have been proposed and/or developed to overcome the limitations inherent in uv~,.lLiondl subtractive machining methods. For instance, U.S. Pat. No. 3,932,923 to DiMatteo ~ --r' ' the production of a plurality of individual planar elements, corresponding to thin cross sections of the object to be produced, responsive to signals generated from a contour follower. The planar elements are then stacked and physically joined together by various means to form the desired three~ n~ object. This technique has been known to be difFIcult to apply because an u . .,. V./h~h~lill~ number of planar elements may result from high resolution between layers, which may be required for non-uniform three-~imPn~ l objects. The 5 handling of these numerous elements, and the necessity that these elements be precisely stacked to be within tolerances, greatly lengthens production time.
Another method of three ' ' modeling is selective laser sintering, qJluo~.llLdli~., tcachings of which are found in U.S. Pat. No. 4,863,538 to Deckard and in U.S. Pat. No. 4,938,816 to Beaman et al. That method, , ' the deposition of 10 a powder, such as powdercd plastic, in a bounded area to form a powdered layer. This layer, or a selected portion thereof, is then sintered by such means as a laser to bond the affected powder particles of that layer together, thus forming a discrete layer of the three-.liln~ object. Successive alternating steps of powder deposition and sintering occur until the three~:rn~nci~-n~l object is formed. Drawbacks associated with selective layer 15 sintering include the fact that only a limited range of materials can be used and the inherent dangers presented by the production of toxic gases resulting from the reactions with the powder, coupled with a risk of explosion.
Alternatively, powder particles may be bonded together in a layer by use of a bonding agent, such as a ceramic. This process, known as three tlimrnc;~m~l printing and developed at the ~ Institute of Technology by Dr. Emanuel Sachs, is similar to selective laser sintering, except that it ~~Ulltl~UI~' using a printer irlk jet to deposit the bonding agent in a ~ =fl area of a powder layer, rather than using a laser to sinter the particles together.
Both powder-related techniques suffer from a drawback common to all other prior 25 art three-~" I forming techniques, with the exception of the dru-~ ' ~ullv~lAiulldl machining. Namely, such processes are planar in nature, since the parts to be collallu~ ,d are fonned of discrete layers of material. CUII~ U.,ULI.Y, a large number of thin layers are required to form an object within given tolerances.
A three-~imrnci~n~l object may also be formed by ballistic particle ...-...r~.n..;..g, a technique taught in U.S. Pat. No. 4,665,492 to Masters. There, a first particle, ,'( ~ ' as an origination seed and constructed of material such as steel or a ceramic, is placed at the origin of a three--1imrn~ n~1 coordinate system. Working heads emit 2 t 79q22 ~ 3 small particles or droplets of ~ for instance~ a ceramic material ~ according to ~ r~l~ a ~
CUul,'' originating from the seed. These particles bond to the seed and to each other, whereby continued emission of droplets in the ~ d~lr~ ..,' ~l manner ultimately produces the three~ rnpnc;~)n~l object. While a wider array of materials can be used in this 5 technique as opposed to other methods, ballistic particle .., --,.,ri- U.. ;,.~ presents inherent tolerance problems because tolerance is a function of droplet size and droplet po~;Liollill~
accuracy, which is difficult to manage. Full},~l,llul~, the small droplet size (a droplet may be only a few microns in diameter) results in lengthy production time.
The most widely accepted ~ 1 method of producing a three~
object is known as stereolithography, taught in U.S. Pat. No. 4,575,330 to Hull and in U.S. Pat. No. 4,961,154 to Pomerantz et al. In this method, a bath of a photopolymer liquid is contained in a vessel. Generally, layer-by-layer sùlidiru,aliu.. of ,ulr~l I "~i~,r :l areas of the liquid ~hULU~UIYIII~I surface is achieved through sequential exposure to a light source, such as a laser. Discrete layers, each newly-formed layer bonding to an hlul~,didl~ly preceding layer, are formed until the desired three-.li.. ~;.".-~ object is produced. As each new layer solidifies, however, a shrinkage in its volume occurs, causing warpage, which leads to stresses in the formed part. These stresses may cause distortions in the part and thus lead to exceeding tolerances. While Pomerantz et al.
disclose methods of ~ i,.g for the effects of shrinkage, such methods do not 20 prevent shrinkage altogether. Arlr'' "~/, stereolilho~ ,l.y is limited to use of a photopolymer as the material from which the three-rlimpnc~ l object is ultimately formed. Another di ~lv ,, presented by ~ rol;ll~ h,~ is that reactions with yll~ frequently produce dangerous toxic gases.
A modified stereo~ process is taught in U.S. Pat. No. 5,û31,120 to 25 Pomerantz et al. There, a phùlupolylll~l liquid is supplied only in discrete layers, and a supplied liquid layer, or selected portions thereof, is solidirled throughout the entire thickness of the layer, differing from solidifying merely at the surface of a liquid bath, as taught in the ~rulr~. .,li..". d standard s~ /' process. Any u."ulillirl.,d liquid is removed from the layer, such as by ~ ' ~, and resultant voids in the solidirled 30 layer are filled in with a support material, such as wax. The support material is then allowed to solidify, after which time the entire newly-solidirled layer is trimmed to a flat, uniform thickness by such means as a machining unit. After such trimming, subsequent ~ 4 layers are formed in like manner until the three--limPn~in ~1 object is produced. This modifled process presents a greater likelihood that an object thereby produced will meet tolerances, since no temporary support web is necessary, unlike the standard process, where such a web must be constructed for any overhangs of the part and then removed by 5 hand. I~owever, it is still subject to the same dio~lllvduk~ associated with that standard process Moreover, the machine required to implement the modified stereo!hhngr~rhir process is relatively complex and costly, and the rate of object Cu~ u~liOIi is hindered by the additional steps required in this process.
SUMMAI~Y OF THE INVENTION
It is an important object of the present invention to provide a three-~lim~nc;~m~l part production method and apparatus which overcome the foregoing limitations associated with prior art systems.
It is a further object of the present invention to provide a three-.l;,.,~.~;.,,.-~ part production method and apparatus which are not dependent upon resolution of object section 15 thickness to attain a given tolerance for the object.
It is a further object of the present invention to provide a three-~ ;. ":~1 object production method and apparatus which combines molding techniques and machining techniques to illUI~ lly produce the three-dimrncir,n:ll object.
These as well as other objects are ~ h. d by a method of producing a three-20 rl;.. .,- ~ object comprising the steps of depositing a first layer of mold material onto a support surface, machining a first cavity into the frst layer of mold material, depositing a first layer of ~u~ iull material onto Lhe first layer of mold material such that an UV~ portion of the first layer of l_OIl~llUl.liUU material flls the frst cavity to form a first three-rlin ~inn~l section of the object and such that a oU~ JU:~;llg portion 25 of the layer of ~:onOIIu.lion material covers the first layer of mold material, and machining the OU,u"lluu~ g portion of the first layer of ~wlollu~liull material to form a second three-, n~ section of the object.
When additional three-~imrn~inn:il sections are necessary to complete a three-.li.. ,~;.n,~object,theprocessofthepresentinventionuu ~' sequentiallyrepeating 3û the following steps until the object is completely formed: (1) depositing a successive layer of mold material onto an hl"l.r ' '~/ preceding three-dimensional section of the object, (2) machining a ~UII~.oLlUUdil~g cavity into the successive layer of mold material, (3) depositing a successive layer of cu~ uuLiun material onto the successive layer of mold material such that an v._~L~ul);n~ portion of the successive layer of cun,L.u~;Lic., material flls the cù.l~,;.,uo,.di~.t5 cavity to form another three-.l;.,.~ .,.~;.,...l section of the object and such that a ~u~u~,uu~hl~ portion of the successive layer of uull~LIu~Liol~ material covers the 5 successive layer of mold material, and (4) machining the ~U,U.lUoSi.,g portion of the successive layer of col-,L-u~L;oll material to form yet another three-flimrnci~-n~l section of the object.
The di'UI' ~ t;ll J objects of the present invention are also a~o...~uli~h~d by an apparatus for producing a three-~lim~ neir-n~ll object, comprising sculpting means, a director 10 for positioning the sculpting means in a 1~ ,.,;l l area, a mold material dispenser operatively connected to the director, a uull~Llu~Lioll material dispenser operatively connected to the director, and a controller operatively connected to the director, the controller controlling operation of the sculpting means to selectively sculpt mold material and CU.~.,IU~.I;On material.
In general terms, the "layered subtractive machine tool method" ~,UIIi~,lll,U' anew and improved system for making solid objects by ~u~c,,i~,ly machining thin layers, or laminae, of mold and wll~llu~,lioll material. The successive laminae are onn-m~ sllly integrated as they are formed to defne the desired three-.l;~ ;.".~l object. The mold material often provides a sculpted receptacle into which the c, u~,liu" material is 20 deposited, thereby imparting its negative shape to areas of an object which would otherwise be difficult or impossible to machine by conventional means. Additionally, the positive shapes of portions of the object are formed by machining layers of ~ u~lio,.
material.
In a presently preferred ~ .l,ù~' -- by way of example and not necessarily by 25 way of limitation, the present invention harnesses the principals of computer aided design (CAD) in ~.,...l.;..-~;u.. with layered machining, i.e., the use of subtractive machining methods on a layer-by-layer basis for forming three ~lim~nc;~mol objects, to cim~ onCly execute CAD and computer aided ~ .uura~Lu- ..~, (CAM) in producing three-rlimrnci~
objects directly from computer instruction. Intended al,l,lic.lLic).l~ of the invention include 30 sculpting models and prototypes in a ul~lllurh~Lulhl~ system and in a design phase of product d~clo,ul.l~.-L.
21 79q22 ~ 6 The ability to sculpt three tiinlPncinn~l features into each layer makes it possible to work with ~ olls;d.,lAbly thicker slices, thereby reducing ~ Al complexity and CUll~llU-;liull time while increasing part tolerance. Thus, tolerances are not a function of layer thickness but are instead largely dependent on the accuracy of the subtractive 5 machine tool methods. Additionaily, the method of the present invention provides fiexibility in usable materials; for instance, metals, plastics, waxes, woods, polymers, and composite materials, may be employed as UU....Iu.,liUll and/or mold materials. The term "composite material" is intended to generally include any material made from two discrete snhct~nf rc and more specifically is used to denote man-made cnrnroci~pc~ including fiber-reinforced plastics. Composite materials allow a blending of properties of the separate . " ~l,n"~ With specific reference to fiber-reinforced plastics, such composites combine the high strength and stiffness of the fber material with the low weight and fracture resistance of the polymeric matrix.
BRIEF DESCRliPTION OF THE DRAWINGS
The uùll~llu~.liùll designed to carry out the invention will be hereinafter described, together with other features thereof.
The invention will be more readily understood from a reading of the following and by reference to the - , yi-.g drawings fûrming a part thereof, wherein an example of the invention is shûwn and wherein:
FIG. 1 is a perspective view, partly in schematic, of an apparatus ~uu~lluul~ i in accordance with a preferred ~",ho.l;.,.. ~ of the present invention for producing three-.i;,....,.;,.,~ objects;
FIG. 2 is a perspective view of a sphere;
FIGS. 2A-2F illustrate successive stages in the production ûf the sphere illustrated in FIG. 2 according to the method of the present invention;
FIG. 3 is a perspective view of another three-ll;~ UAl object;
FIG. 3A is a sectional elevation view taken along line 3A-3A oi FIG. 3;
FIGS. 3B-3H illustrate successive stages in the production of the object illustrated in FIGS. 3 & 3A according to the method of the present invention;
FIG. 4 is a ~ )~liV~ view of a three-!' ~ object varying slightly from that shown in FIGS. 3 & 3A;
FIG. 4A is a sectional elevation view taken along line 4A-4A of FIG. 4;
~ 7 FIGS. 4B-4E illustrate successive stages in the production of the object illustrated in FIGS. 4 & 4A according to the method of the present invention, said stages being in addition to the stages illustrated in FIGS. 3B-3H.
FIG. S is a p.,.~ view of a hollow sphere;
FIG. 5A is a sectional elevation view taken along line SA-SA of FIG. 5;
FIGS. 5B-5I illustrate successive stages in the production of the object illustrated in FIGS. 5 & 5A according to the method of the present invention;
FIGS. 5J & 5K illustrate alternative methods of removing a void negative;
FIG. 6 is a sectional elevation view of a three-~imrn~inn~l object having a recessed surface; and FIGS. 6B-6E illustrate successive stages in the production of the object illustrated in FIG. 6 according to the method of the present invention.
DESCRIPTION OF THE PR~ EMBODIMENT
Depicting the context in which the method of the present invention is executed, FIG. 1 broadly illustrates an apparatus 10 for producing Lhree-.l; ;.~ objects which is ~ uutl,d in accordance with the preferred l ,l.o.l;--- .d of the present invention.
Generally, apparatus 10 includes sculpting means 12 capable of moving in the directions indicated by arrows 2 and of rotating in the direction shown by arrow 4, a molding material dispenser 14 capable of moving in the directions indicated by arrows 6, a uc)llaL-u.,Liull material dispenser 16 capable of moving in the directions indicated by arrows 8, and a waste remover 18. As will be shown with regard to FIGS. 3E & 3G, dispensers 14 & 16 are preferably operable to dispense a plurality of mold materials and u~ LIul liu materials, ~ ti~",ly.
Mold material dispenser 14 is shown dispensing mold material 22' from its outlet14a. The mold material, as well as c uuLion material, may ~ ,ly be deposited by other means, such as particle beam or particle spray, pouring or spraying of liquids, or deposition of powders for fusing after deposition. The mold material 22' is deposited onto a support surface or platform 20 until an initial layer of mold material 22 is formed.
An example of a mold material is a water soluble wax, such as that sold by YatesInvestment Casing Wax of Chicago, Illinois under the name 550-GOLD SLAB, B4041.
Further examples will be discussed in detail later herein.
2 i 79~22 ~ 8 A first director 24 is operatively coupled to the sculpting means 12 for pu~;Lùn;ll~;
the sculpting means in a ~ ".,;,.. d area, such as area 26 on the top surface 28 of the initial mold material layer 22. Of course, the area 26 may be three-rlimr~ncinn~ thus forming a cavity within the mold material layer 22.
Like the sculpting means 12, the molding material dispenser 14 and the ~,UII;~Il Ul,LiUn material dispenser 16 may also be operatively coupled to the first director 24.
~onn~ctinne between dispensers 14, 16 and the first director 24 are shown at 15 and 17.
Alternatively, dispensers 14, 16 may be u~lùbDIIu-LiY~ly attached to the milling head of sculpting means 12 to constantly move with means 12. Still further, dispensers 14, 16 could be positioned by a separate director, such as second director 25 which, in turn, could be operatively connected to a second controller such that deposition of materials and machining of previously-deposited material layers could occur silllullall.uu~ly.A second director 25, operatively coupled to waste remover 18, may also be provided for directing waste remover 18 in a p,~rl. t.. ,..;". d path, such as 27, for removing 15 waste material in a manner to be discussed in detail herein.
A controller 30, s~h~ irally shown as being operatively coupled to the director 24, controls operation of sculpting means 12 to selectively sculpt deposited layers of both mold material and ~UI~Llu Liul. material.
Sculpting means 12 preferably comprises a three-axis computer Ill~ ally 20 controlled ("CNC") milling machine with tool changing ability, Illallulid~Lu.~d by Bridgeport Machines, Inc. of Bridgeport, (~nnnrrtirllt as Model No. 760/22 DX.
Sculpting means 12 preferably includes a fixture (not shown) for holding a plurality of iut~.~,llà.lgcdblc cutting tools, such as at 32, a cutting tool changer apparatus (not shown), and a cutting motor (not shown) for turning tool 32. To provide quick and efficient 25 production of an object within tolerances, the cutting tool 32 may be: lly changed during operation such that a tool si~ and shape a~lJl UIJI ' ' to the geometry being ~ull~LIu~Ltd may be used. ~or example, a small spherical tool may be a~/lupl for small curved details, a small cylindrical tool may be a~ lu~n forsmall vertical walled details, and a larger tool of an a~ u~l geometry may be used for 30 roughing in of the shape or for areas requiring lesser detail. This ability allows production of parts with area specific tolerances.
g First director 24 preferably comprises a system of stepper motors, worm gears, and linear sliders (not shown) for positioning the sculpting means 12 in three rlim~~ 7nc The type and power of sculpting means 12, the stepper motors, and the cutting motor is dependent upon many factors, and in particular upon the type of materials being dispensed 5 and the desired tolerance of the part being produced. Second director 25 lilcewise comprises a system of stepper motors, worm gears, and linear sliders to move waste mover 18 in a ,UIC~ d path.
The controller 30 preferably comprises a computer which is operatively connectednot only to first director 24, as previously described, but also to second director 25 for controlling waste remover 18. Additionally, by virtue of the ~ : 15 and 17 to the first director 24, controller 30 controls deposition of both mold material and uul~lu~Liu-material. The computer comprising controller 30 preferably illUOl,Ul ' a Illi.lU~,lUCc.,~ul 34 for controlling all of the ~rul~ ' functions and a CAD/CAM system 36 for generating ~lim~nri~n~l data for tlle object to be produced. Cuul~)u.~./cullLIuller 30 is 15 preferably capable of monitoring a position of sculpting means 12 during its removal of extraneous material and is ~IU~, ' with i..rc,.ll..lLiul. indicative of ~ d~tcllllhl~d boundaries of a plurality of three-.l; - .---l sections of the object to be produced.
The production of various examples of three-rlimpncii7n:~l objects will now be described, with reference to the remaining figures.
FIG. 2 illustrates a frst example part, a sphere 38, the ~oll~Llu-Liull of whichinvolves the least amount of steps in a method of the present invention. Sphere 38 is comprised of frst and second three-~ sections 38a and 38b, I~ Livc:ly, these sections being .1; ~d.."..;~l ~d by imaginary equator 39, integrally joined to one another, and formed as described below.
In FIG. 2A, a first layer of mold material 40, ~UII~ JUIIdill~; to layer 22 in FIG.
1, has been deposited onto platform 20 by mold material dispenser 14. The layer 40 is deposiLed on platform 2û either in a solid form or as a liquid which is caused to solidify upon or shortly after deposition. The solill;r~ of this layer may be caused by, but not limited to, thermal, radiation, or chemical methods. A smooth upper surface 41 may be obtained by machining if desired. Vertical walls 21 may be provided on either side of layer 40 to act as a mold material container in c.~n; -- ii.." with platform 20. These walls may be sections of a cylindrical wall or may be walls of a rectangular enclosure. Such '10 ' 2 1 79922 an ~ .",~ lll is particularly desirable where the viscosity of the mold material or uv~tluulion material in its liquid phase is relatively low, or where curing times are relatively long.
.Sl~hseq~Pn~ to the deposition and ~ulidirl~,liù,l of layer 40, subtractive machine tool 5 methods are used to three-fiimpnc;~ iiy sculpt the mold material into a geometry specifed by the computer control system. FIG. 2B illustrates layer 40 as having been machined or sculpted such that a cavity 42 has been formed therein. The depth "d" of cavity 42 is equal to the radius of sphere 38. Waste particles 44 resulting from the machining of cavity 42 are shown to be Iying in the bottom portion thereof.
In the remaining figures to be described, although platform 20 and vertical walls 21 will not be therein shown, it is understood that any initial layer of mold material will be considered to have been deposited upon platform 20 and within vertical walls 21 where desirable.
FIG. 2C illustrates removal of waste particles 44 from machined cavity 42 by waste remover 18. Preferably, waste remover 18 comprises a vacuum head 46 connected to a suitable conduit 48 for conducting the particles 44 in the direction shown by arrow 50.
Second director 25 (FIG. I) is constructed so as to direct remover 18 not only to the area of cavity 42 but also to any upper surface of layer 40, such as surface 41. Alternatively, waste removal may be facilitated by use of a directed air stream which would serve to push any debris off the layer 40. As a further alternative means of removing waste particles, surfaces of layer 40 may be swept by an automated brush. Additionally, if particles 44 are comprised of a metallic material, waste removal may be facilitated by magnetic or cle~llu~ldti~ attraction. Any CVInIJ "nn of the above methods may beemployed to ~rf n~rlich waste removal.
PIG. ZD shows a layer of .on~l~u.liun material 52 as having been deposited upon mold material layer 40. An uv~ g portion 52a of layer 52 is shown as having filled cavity 42, thereby forming first three- ' ' section 38a of sphere 38 (FIG. 2). As used herein, the term "overlap" and variations thereof, as ~ ,. J from the prior art "discrete level" l~llllhlulv~y~ mean that the deposition or machining of mold or~v~ l u~liu~ materials may occur below elevations of upper surfaces of previously deposited layers. For specific example, following deposition of layer 40, subsequent process steps were not directed merely to areas at or above elevation "e" of surface 41 of layer 40: machining of cavity 42 to depth "d" (FIG. 2B) occurred below elevation "e", and a portion of the ' ~ 'S,-added .v~ u~,liuil material layer 52 flowed below elevation "e", into cavity 42.
Additionally shown in FIG. 2D, a DU~ JOD;llg portion 52b of layer 52 is shown 5 to cover layer 40. As used herein, the term "cover" and variations thereof mean that one DUIJl..l~)OD;llg layer need only interface with a segment of the upper surface of another layer.
For specific example, although FIG. 2D shows the width w' of layer 52 extending the full width w of layer 40 for simplicity of i" , thus showing an interface between layer 52 and the full length of surface 41, such a width magnitude is not always necessary.
10 Depending on the dimension of the next three-riimpnci~\n:ll section to be produced, width w' may be less than width w. All that is required for layer 52 to "cover" layer 40 is that there be an interface between layer 52 and a portion of upper surface 41 of layer 40.
An imaginary line 51 is shown in FIG. 2D for purposes of illustration to divide the ~ul~llu~Liull material layer 52 into the portions 52a, 52b. The c,ull~Lluuliull material layer 15 52 may comprise a ".~ le wax, such as that sold by Yates Investment Casing Wax of Chicago, Illinois under product number B-3096. It is ~Oll'C ~ ' ' however, that other uul~ uDiliùns may be used as ~vllDllu liull material, so long as such c.. ~po~;li....~ possess suitable physical strength, stiffness, flexibility, and resistance to thermal .irE",.,I I j~n FIG. 2E depicts the machining of DUI/..I,UU~ S portion 52b of l,UllDllUUIiUll material layer 52 by sculpting means 12, thereby forming the second three-~lim~ ncin~ ~ section 38b of sphere 38. Upon completion of this machining step and after any necessary removal of waste particles in the manner described with regard to FIG. 2C, the completed sphere 38, partially encased in the mold material layer 40, emerges, as shown in FIG. 2F.
Mold material removal is performed following completion of the last three-25 ~ ;n,.l section of an object. The molding material 40 may be removed, or separated from sphere 38, physical means, radiation (electrical, UV, thermal, ultraviolet, etc.), ultrasonic, vibration, electrical induction, or other means or methods such that the ~ollallu.liu.l material is not comprised. FIG. 2F illustrates an early stage of mold material removal, wherein a heating device 54 begins to reduce layer 40 to a liquid mass 40a.
Complete removal of layer 40 results in an isolated completed sphere 38 (FIG. 2).
Although removal of the mold material layer 40 is shown for purposes of illustration in FIG. 2F as being ~ ", ~ h ~l by the heating device 54, it must be kept in mind that such 2 ~ 79922 ~ 12 means would not be used where the layer 40 is a water soluble wax and where the ~VII~UU~liUII material layer 52 is a ~ ,le wax, since these materials possess similar melting points. Instead, removal of such mold material would be d.uull,~ l merely by dissolving the mold material in water.
It is understood that all machining steps ' 7l 1Pntly mentioned herein will be considered as having been performed in like manner to the machining steps described with regard to FIGS. 2B ~ 2E. It is additionally understood that any s l~c-, 'y described step of mold material removal will encompass the means discussed with regard to FIG. 2F. Moreover, although waste particle removal will not be discussed with regard to the remaining figures, it is understood that waste removal according to the means discussed with regard to FIG. 2C may occur subsequent to machining of any layer of mold or cu~ u.Livl, material and before the deposition of a subsequent mold or ~vu~LIu~,lio material layer.
The method of the present invention may be employed to produce three-~l;, . ,. . , -l objects possessing a more complex shape than that of the sphere 38 of FIG. 2. For instance, FlG. 3 illustrates a rounded barbell-shaped three~ object 56 comprisedof a neck portion 58 i~,.,: -'i,.~ in end members 60, 62 at either end thereof.
As seen in FIG. 3A, object 56 may be subdivided into several lnt~ t~. ' three-~irnPncion:ll sections 56a, 56b, 56c, and 56d. The thickness and placement of these sections are parameters which are Inu~ Idullllcl into CAD/CAM system 36 of computer 30 (FIG. 1), and these parameters may vary according to the desired object ~.l, -- .., t~ 1 i. C
such as materials, tolerances, and speed of uull~LIu~liuu. As seen in FIG. 3A, the n(~mrn~;tinn of sections 56c, 56d differs from that of sections 56a, 56b. It is also seen that if object 56 were to be wholly produced by ~u.lv~..llivndl machining lerhnirlllPs, an 25 operator would have difficulty in properly positioning a tool below the u.~,lL~n~illg shape formed by end member 62. Thus, only section 56d could be produced in such a manner without ~ U ' illlj; significant dimculty.
In FIG. 3B, a first layer of mold material 64 has been deposited onto a support surface in the same manner described with regard to FIG. 2A. Additionally, a first cavity 30 66 is shown as having been machined into layer 64.
In FIG. 3C, a frst layer of cuu~llul,lion material 68 is shown as having been deposited onto the first layer of mold material 64. An uv~,.la~ illg portion 68a of layer ~ 13 68 is shown as having filled the first cavity 66, thereby forming first three~
section 56a of object 56 (FIG. 3A). Additionally, a :~U~ V~hlg portion 68b of layer 68 is shown to cover mold material layer 64. An imaginary line 61 is shown for purposes of illustration to divide the first ~o.~ u~liun material layer 68 into the portions 68a, 68b.
FIG. 3D depicts sculpting means 12 machining ;.. l~.,uosh-g portion 68b of the first ~:UII~IlU~iUn material layer 68, thereby forming the second three-~l;..,..,~;...,..l section 56b of object 56. The outline of the portion of section 56b yet to be formed in FIG. 3D is shown in phantom lines. The height of section 56b illustrates that an object produced by the prvcess of the present invention need not be formed in a plurality of equally-thin planar 10 sections, as required by prior art processes, thus greatly increasing the speed of production. To provide a smooth surface to facilitate further cu,.~L.uuliu.., upper end 69 of section 56b may be further machined using any tool which levels the surface of end 69.
Referring to FIG. 3E, a second layer of mold material 70 has been deposited on the first layer of mold material 64 such that the second layer of mold material 74 15 completely covers the second three-~' ' section 56b. As seen from the cross hatching in the region l~ uLi--g second mold material layer 70, that layer is shown to be of a cu.l-l)u~ilion differing from that of the first mold material layer 64. Differing f.,,.,l.h~;lio--- between mold material layers may not always be necessary; however, conditions may require differing ~ ;v~ in some instances, and the process and 20 apparatus of the present invention provides the flexibility to ~ r~m~ h deposition of differing u o---~v~;Lions. For instance, the cunll)va;Lion of the first mold material layer 64 may be that of a water soluble wax, while that of second mold material layer 70 may be a ceramic. To provide a further example, first mold material layer 64 may be onerV .. I~ .n of a ceramic, while the second mold material layer 70 may be another25 rv~u,uldlio" of a ceramic. Any differing romrf~ nn may be used for a mold material layer, so long as that "~ t~ n possesses the desirable properties discussed previously and so long as that nnmr~ is compatible with the uu~ lu~,lioll material which will interface with it. The term "compatible", as used herein to dcscribe I~J.lLivl~ ) between mold and cul~Llu-Lioll materials, generally means that removal of mold material interfacing 30 with a given section of CUII~LIu~,Liull material will not damage or impair that ~ullaLIu~.Liu material section.
FIG. 3F illustrates a second cavity 72 as having been machined into the second mold material layer 70.
In FIG. 3G, a second layer of COI~Ilucliu~ material 74 has been deposited onto the secûnd layer of mold material 70 such that an UV.,I; rr lg portion 74b of second5 UUII~llUCliUII material layer 74 fills second cavity 72 to form the third three~
section 56c of object 56 (FIG. 3A) and such that a ~U~ /ODillg portion 74b of layer 74 covers the second layer of mold material 70. An imaginary line 71 is shown for purposes of illustration to divide the second ~ U iiUl- material layer 74 into the portions 74a, 74b. As shown by the shading in the area lC~Jl..,.,lltillg the second layer of UOII~lUC~iUII
10 material 74, that layer is of a ~ " differing from that of the first layer of cu ~ ;n.. material 68 (FIG. 3C), from which the first and second three-.li..,~"~sections 56a, 56b have been formed. For example, the frst layer of coll~llucliull material 68 may be a ~ IC wax, as previously indicated, while the second layer of cul~llucliull material 74 may be an epoxy or a photopolymer. Cuu~u~uLly, the finished 15 object 56 may be comprised of non-l~, 'L '"' - material. Various culllLJu~;liù.~ may be used for a cul~llu.,Liul~ materials, so long as such ~...l.n~ are sufficiently, ' ' l when in solid form and so long as they are compatible with the . ' ~ mold material.
FIG. 3H depicts sculpting means 12 machining ~UIJ~,l,U(J:~illg portion 74b of the second~u..~llucliullmateriallayer74~therebyformingthefourththree-1l;~" ~ section2û 56d of object 56. The outline of the portion of section 56d yet to be formed in FIG. 3H
is shown in phantom lines. Further machining may be performed, if necessary, to level the top surface 75 of section 56d. Following the step shown in FIG. 3H or any such final machining, the mold material layers 64, 70 may be removed by any of the techniques discussed with regard to FIG. 2F which are suitable for the particular mold material 25 ru~ J~;li,.~ used. The removal of the mold material layers exposes the completed object 56 (FIG. 3).
The steps described with regard to FIGS. 3B-3H may be sequentially repeated to produce additional three-~ llAl sections until a larger object is completely formed.
For instance, FIGS. 4 & 4A illustrate another three-~l~rAPn~innAl object 76 which is comprised of object 56 (FIG. 3) and a raised inverted conical member 78 disposed upon upper surface 75. Member 78 is subdivided into two three-.l.. ~;n., l sections which, since object 56 was shown to have four sections, are fifth and sixth threc-~lirA.- ncinnAAI
sections of object 76, namely ffth three~ i"".l section 76e and sixth three-.l;, .... ,~;....~1 section 76f. As with object 56, the thickness and placement of these sections are parameters which are programmed into CAD/CAM system 36 of computer 30 (FIG.
1), the parameters being variable as previously described.
In FIG. 4B, a successive layer of mold material is shown to have been deposited onto an i ' 1y preceding three- li.~ iùnal section. Specifically, a third layer of mold material 80 is deposited onto the second layer of mold material 70, and layer 80 is seen to completely cover the i.. ~,Ji2ll~1y preceding completed three- li~ ;vllal section 76d (cullc~vllJi-lg to section 56d in FIG. 3A).
FIG. 4C illustrates a Lullc~JullJhlg cavity 82 as having been machined into the vhird layer of mold material 80.
In FIG. 4D, a successive layer of cull~llu~liùn material is shown to have been deposited onto the successive layer of mold material. Specifcally, a third layer of CWI~llucliull material 84 has been deposited onto third layer of mold material 8û such that an uv~ ri hlg portion 84a of layer 84 flls the CUllC~tJol-Uillg cavity 82 to form ffth three-,' l section 76d and such îhat a, ~/..tJV~hlg portion 84b of layer 84 covers the third layer of mold material 80.
FIG. 4E depicts sculpting means 12 machining :~U~ lU~illg portion 84b of the third cv~ u~liu-- material layer 84, thereby forming the sixth three-~ Pne~ section 76f.
20 The outline of the portion of section 76f yet to be formed in FIG. 4E is shown by a phantom line. Following any necessary final surfacing and removal of mold material layers 64, 70, and 80, the completed object 76 (FIGS. 4 & 4A) emerges.
The process of the present invention may also be used to produce hollow three-objects, the term "hollow" including any finished three-~ qnci~mAl object 25 which possesses at least one void at any point within its volume.
FIGS. 5 & 5A illustrate a hollow sphere 86 comprised of first and second three-AI hollow sections 86a and 86b, respectively, which are ù~,..-~u ' by an imaginary line 91. The internal walls of sections 86a, 86b form an enclosure 88 to defne a void 90.
In FIGS. 5B & 5C, one layer of mold material 92 has been deposited, and a first cavity 94 has been formed into layer 92.
~ 16 Moreover, excess mold material is machined away so that mold material layer 92 has level upper surfaces such as at 95.
FIG. SD illustrates one layer of ~.UII:~IlU~,liUll material 96 having been deposited onto mold material layer 92 such that layer 96 fills the first cavity 94.
In FIG. 5E, e uuliull material from layer 96 which was above the elevation of surface 95 has been removed. F~..lh..l~llul~;, a second cavity 98 has been machined into the remaining U~,liUII material layer 96 to form first hollow three-~' ' section 86a of hollow sphere 86.
FIG. 5F illustratcs another layer of mold material 100 having been deposited onto the one mold material layer 92 such that an u .. ,1': p~ ~ ,, portion lOOa of layer 100 fills the second cavity 98 to form a first portion 102a of a void negative and such that au~ 6 portion lOOb of layer 100 covers layer 92 and the first three~
hollow section 86a. Imaginary line 91 divides the mold material layer 100 into the portions lOOa, lOOb.
FIG. SG depicts sculpting means 12 machining . . ~ portion lOOb of the mold material layer 100, thereby forming a second portion 102b the void negative 102.
The outline of the portion of void negative 102 yet to be formed in FIG. 4E is shown by a phantom line.
In FIG. 5H, another layer of cul~lluuliull material 104 has been deposited onto the one layer of mold material 92 such that the layer of u~,liull material 104 completely covers the second portion 102b of void negative 102.
Referring to FIG. 51, layer of UOll~llU~liUn material 104 is shown being machined by sculpting means 12 to form the second three-~ hollow section 86b of hollow sphere 86. The outline of the portion of section 86b yet to be formed in FIG. 5I is shown by a phantom line. It is seen that hollow sections 86a, 86b form the enclosure 88 P... ~ a ~ g the void negative 102.
FIGS. 5J & SK disclose alternative methods of removing void negative 102 from enclosure 88 so as to produce the void 90 (FIG. 5A).
In FIG. SJ, a vent 106 is shown as having been inserted through second three-~ hollow section 86b. A conduit 108 ~" with the outlet of vent 106 at one end and with a vacuum source 110 at another end. Activation of source 110 causes the void negative material 102', which must be in a liquid or gaseous state, to escape from enclosure 88 in the direction indicated by arrow 112. If necessary, the void negative 102 may be partially dissolved prior to evacuation. Such dissolution may be effected by a solvent which, depending upon the . ~ n of Ihe void negative 102, may be such liquids as water or kerosene.
In FIG. 5R, which illustrates a therrnal method of void negative removal, a different void negative material 102" is shown, since for such a method the material 102"
must have a lower melting point than the material comprising mold material layer 92.
Moreover, FIG. 5K illustrates the second three-dimpn~inn~l hollow section 86b as having been formed of a porous material, such as a porous ceramic, as shown by a plurality of pores 114, the relative diameters of which are ~ ,r ~t d for purposes of illustration.
The hollow sphere sections 86a & 86b, mold material layer 92, and the material 102" are subjected to a heated ~llvilu~ lL such as that defined by enclosure 116. Heatingcontinues, causing material 102" to boil and reach a vapor state, whereafter the vapor escapes through the plurality of pores 114 and into the c~uvilvll~ L 117 in the manner indicated by arrows 118.
Void negative 102 may also be removed by a modified process including steps illustrated with respect to both FIG. 5J & 5K. Specifically, a heated ~llvilulllllCllL may liquify the void negative 102, whereafter the material is evacuated via a vent though a three-/l; n.. ~i.. ~l section.
For purposes other than that shown in FIG. 5K, .llvhulllll.llL 117 need not be limited to a heated .llvhulllnc.lL. For illustrative examples, it may be advd..t~ ,uus to cool that .llvhulllll~,llL so as to cause rapid sùlilliri.dLiull of waxes or to flood the .llvhu~ ..lL
with an inert gas to prevent unwanted byproducts from process steps performed upon mold or u~,Liun material.
The process of the present invention may also be used to produce a three-d;"....~, ' object having a recessed surface, such as the object depicted in cross section in FIG. 6, where a three--lim~nsin ~l object 120 is shown having a recessed surface 122.
Surface 122 forms an arcuate indentation with respect to the plane containing either or both of lower planar surfaces 121 and 123. The sequential steps executed to produce 30 object 120 are described below.
FIG. 6A illustrates a layer of mold material 124 as having been deposited.
FIG. 6B depicts sculpting means 12 machining the mold material layer 124 to form a iuLulub~dll~c 126 which, though shown as having a rounded or h~,...;~,)ll..;udl shape, can assume any shape, depending on the shape of the ~Ull~aLJU~ g recessed surface in the object to be produced. In FIG. 6B, iuluLulJ~Idll ~ 126 thrusts outwardly with respect to L~ uu.,diillg upper planar surfaces 124a, 124a' formed by the machining of layer 124. The S outline of the portion of iuluLubcldllLc 126 yet to be formed in FIG. 6B is shown by phantom lines.
In FIG. 6C, a layer of ~,uuaLluuLiOll material 128 is shown as having been deposited onto the layer of mold material 126 such that layer 128 is seen to completely cover i''l' dll.C 126.
As seen in FIG. 6D, machining of the uollal~uL liuu material layer 128 by sculpting means 12 then occurs such that object 120 begins to emerge, the ~ pl~t~d portion of which is lLi~lL,.~ilt~.d by phantom line 129.
FIG. 6E depicts the removal of machined mold material layer 124. Mold material layer 124 is submerged into a solvent 130, which is contained in vessel walls 132 and 15 which may be water if the mold material is a water-soluble wax. As seen in FIG. 6E, former layer 124 is shown as having been partially dissolved into a material mass 124'.
Continued s ' -~ ~-- results in complete removal of tbe mold material. It is to be again understood that mold material removal may take place by any of the techniques discussed with regard to FIG. 2F which are suitable for the particular mold material uulllpuailiulia 20 used.
Due to the shape of object 120, in which no overhangs are present, only one arplir~ition and machining of a r UL liun material layer need occur, such that the only three-(l;'- .I~;I~IIAI section produced is the entire object 12û itself. It will be aiu"l~ l, however, that objects of different cwirli,u,dliulia, such as those with both overhangs and 25 a recessed surface, can be produced by a L.lll hjl lj,"~ of the steps described with respect to FIGS. 6A-6E and preceding figures such that a plurality of three-11;.. ~ sections may have to be formed.
As the foregoing description is merely exemplary in nature, being merely illustrative of the invention, many variations will become apparent to those of skill in the 3û art It is to be iuAliiuulL.ly understood that the process steps l~a~ Li~l.y described in FIGS. 2A-2F, 3B-3H, 4B-4E, SB-SK, and 6A-6E may be combined in any sequence to produce three-~' l objects possessing widely varying external and internal * 19 c~ r~ a~ Such variations are included within the spirit and scope of this invention as defined by the ~ollowing appended claims.
Claims (17)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of producing a three-dimensional object comprising the steps of:
depositing a first layer of mold material onto a support surface;
machining a first cavity into said first layer of mold material;
depositing a first layer of construction material onto said first layer of mold material such that an overlapping portion of said first layer of construction material fills said first cavity to form a first three-dimensional section of said object and such that a superposing portion of said first layer of construction material covers said first layer of mold material; and machining said superposing portion of said first layer of construction material to form a second three-dimensional section of said object.
depositing a first layer of mold material onto a support surface;
machining a first cavity into said first layer of mold material;
depositing a first layer of construction material onto said first layer of mold material such that an overlapping portion of said first layer of construction material fills said first cavity to form a first three-dimensional section of said object and such that a superposing portion of said first layer of construction material covers said first layer of mold material; and machining said superposing portion of said first layer of construction material to form a second three-dimensional section of said object.
2. The method set forth in claim 1 further comprising the steps of:
depositing a second layer of mold material, said second layer of mold material covering said second three-dimensional section of said object; and machining a second cavity into said second layer of mold material.
depositing a second layer of mold material, said second layer of mold material covering said second three-dimensional section of said object; and machining a second cavity into said second layer of mold material.
3. The method set forth in claim 2 further comprising the step of filling said second cavity with construction material to form a third three-dimensional section of said object.
4. The method set forth in claim 2 further comprising the steps of:
depositing a second layer of construction material onto said second layer of mold material such that an overlapping portion of said second layer of construction material fills said second cavity to form a third three-dimensional section of said object and such that a superposing portion of said second layer of construction material covers said second layer of mold material; and machining said superposing portion of second layer of construction material to form a fourth three-dimensional section of said object.
depositing a second layer of construction material onto said second layer of mold material such that an overlapping portion of said second layer of construction material fills said second cavity to form a third three-dimensional section of said object and such that a superposing portion of said second layer of construction material covers said second layer of mold material; and machining said superposing portion of second layer of construction material to form a fourth three-dimensional section of said object.
5. The method set forth in claim 4 wherein a composition of one layer of mold material differs from a composition of another layer of mold material.
6. The method set forth in claim 4 wherein a composition of one layer of construction material differs from a composition of another layer construction material.
7. The method set forth in claim 4 further comprising the steps of:
depositing a successive layer of mold material onto an immediately preceding three-dimensional section of said object;
machining a corresponding cavity into said successive layer of mold material;
depositing a successive layer of construction material onto said successive layer of mold material such that an overlapping portion of said successive layer of construction material fills said corresponding cavity to form another three-dimensional section of said object and such that a superposing portion of said successive layer of construction material covers said successive layer of mold material;
machining said superposing portion of said successive layer of construction material to form yet another three-dimensional section of said object; and repeating said steps of depositing a successive layer of mold material onto an immediately preceding three-dimensional section of said object, machining a corresponding cavity into said successive layer of mold material, depositing a successive layer of construction material, and machining said superposing portion until said object is completely formed.
depositing a successive layer of mold material onto an immediately preceding three-dimensional section of said object;
machining a corresponding cavity into said successive layer of mold material;
depositing a successive layer of construction material onto said successive layer of mold material such that an overlapping portion of said successive layer of construction material fills said corresponding cavity to form another three-dimensional section of said object and such that a superposing portion of said successive layer of construction material covers said successive layer of mold material;
machining said superposing portion of said successive layer of construction material to form yet another three-dimensional section of said object; and repeating said steps of depositing a successive layer of mold material onto an immediately preceding three-dimensional section of said object, machining a corresponding cavity into said successive layer of mold material, depositing a successive layer of construction material, and machining said superposing portion until said object is completely formed.
8. The method set forth in claim 7 wherein a composition of one layer of mold material differs from a composition of another layer of mold material.
9. The method set forth in claim 7 wherein a composition of one layer of construction material differs from a composition of another layer construction material.
10. A method of producing a hollow three-dimensional object, comprising the steps of:
depositing one layer of mold material;
machining a first cavity into said one layer of mold material;
filling said first cavity with one layer of construction material;
machining a second cavity into said one layer of construction material to form a first three-dimensional hollow section of said object;
depositing another layer of mold material onto said one layer of mold material such that an overlapping portion of said another layer of mold material fills said second cavity to form a first portion of a void negative and such that a superposing portion of said another layer of mold material covers said first three-dimensional hollow section;
machining said superposing portion of said another layer of mold material to form a second portion of said void negative;
depositing another layer of construction material, said another layer of construction material covering said second portion of said void negative;
machining said another layer of construction material to form a second three-dimensional hollow section of said object, whereby said first and second three-dimensional hollow sections form an enclosure about said void negative; and removing said void negative from said enclosure.
depositing one layer of mold material;
machining a first cavity into said one layer of mold material;
filling said first cavity with one layer of construction material;
machining a second cavity into said one layer of construction material to form a first three-dimensional hollow section of said object;
depositing another layer of mold material onto said one layer of mold material such that an overlapping portion of said another layer of mold material fills said second cavity to form a first portion of a void negative and such that a superposing portion of said another layer of mold material covers said first three-dimensional hollow section;
machining said superposing portion of said another layer of mold material to form a second portion of said void negative;
depositing another layer of construction material, said another layer of construction material covering said second portion of said void negative;
machining said another layer of construction material to form a second three-dimensional hollow section of said object, whereby said first and second three-dimensional hollow sections form an enclosure about said void negative; and removing said void negative from said enclosure.
11. The method set forth in claim 10 wherein said step of removing said void negative from said enclosure includes the steps of:
providing a vent through at least one of said three-dimensional hollow sections; and causing mold material comprising said void negative to escape through said vent.
providing a vent through at least one of said three-dimensional hollow sections; and causing mold material comprising said void negative to escape through said vent.
12. The method set forth in claim 10 wherein said step of removing said void negative from said enclosure includes the steps of:
constructing at least one of said three-dimensional hollow sections from a composition into which a plurality of pores form upon curing of said composition; and causing mold material comprising said void negative to escape through said plurality of pores.
constructing at least one of said three-dimensional hollow sections from a composition into which a plurality of pores form upon curing of said composition; and causing mold material comprising said void negative to escape through said plurality of pores.
13. A method of producing a three-dimensional object having a recessed surface comprising the steps of:
depositing a layer of mold material;
machining said layer of mold material to form a protuberance;
depositing a layer of construction material onto said layer of mold material; and machining said layer of construction material to form a three-dimensional section of said object.
depositing a layer of mold material;
machining said layer of mold material to form a protuberance;
depositing a layer of construction material onto said layer of mold material; and machining said layer of construction material to form a three-dimensional section of said object.
14. The method set forth in claim 13 further comprising the step of removing said mold material layer following said machining of said layer of construction material.
15. An apparatus for producing a three-dimensional object comprising.
sculpting means;
a director operatively connected to said sculpting means for positioning said sculpting means in a predetermined area;
a mold material dispenser operatively connected to said director;
a construction material dispenser operatively connected to said director; and a controller operatively connected to said director, said controller controllingoperation of said sculpting means to selectively sculpt mold material and construction material.
sculpting means;
a director operatively connected to said sculpting means for positioning said sculpting means in a predetermined area;
a mold material dispenser operatively connected to said director;
a construction material dispenser operatively connected to said director; and a controller operatively connected to said director, said controller controllingoperation of said sculpting means to selectively sculpt mold material and construction material.
16. The apparatus set forth in claim 15 wherein said controller comprises a computer operatively coupled to said director to monitor a position of said sculpting means during removal of extraneous material, said computer being programmed with information indicative of predetermined boundaries of a plurality of three-dimensional sections of said object.
17. The apparatus set forth in claim 15 wherein said mold material dispenser and said construction material dispenser are operable to dispense a plurality of materials such that different materials may comprise said mold material and said construction material, whereby a composition of a finished object may be non-homogenous.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002179922A CA2179922C (en) | 1996-06-25 | 1996-06-25 | Method and apparatus for producing parts by layered subtractive machine tool techniques |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002179922A CA2179922C (en) | 1996-06-25 | 1996-06-25 | Method and apparatus for producing parts by layered subtractive machine tool techniques |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2179922A1 CA2179922A1 (en) | 1997-12-26 |
| CA2179922C true CA2179922C (en) | 1999-07-06 |
Family
ID=4158482
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002179922A Expired - Fee Related CA2179922C (en) | 1996-06-25 | 1996-06-25 | Method and apparatus for producing parts by layered subtractive machine tool techniques |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2179922C (en) |
-
1996
- 1996-06-25 CA CA002179922A patent/CA2179922C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2179922A1 (en) | 1997-12-26 |
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