United States Patent (19)
`Crump
`(54) APPARATUS AND METHOD FOR
`CREATING THREE-DIMENSIONAL
`OBJECTS
`S. Scott Crump, Minnetonka, Minn.
`75) Inventor:
`(73) Assignee: Stratasys, Inc., Minneapolis, Minn.
`21 Appl. No.: 429,012
`22 Filed:
`Oct. 30, 1989
`51) Int. Cl. .............................................. G06F 15/46
`52 U.S. Cl. ............................... 364/468; 364/474.24;
`364/477; 264/239; 264/25; 425/1744
`58) Field of Search ....................... 364/472, 473, 477;
`264/308, 13; 425/1744; 427/8, 52; 164/94;
`239/75, 82, 83, 84, 132
`References Cited
`U.S. PATENT DOCUMENTS
`1,934,891 11/1933 Taylor ................................... 239/83
`3,749,149 7/1973 Paton et al. ........................... 164/94
`4,071,944 2/1978 Chuss et al. ............................. 427/8
`4,247,508 l/1981 Housholder ........................, 264/22
`4,293,513 10/1981 Langley et al. ..................... 264/308
`4,545,529 0/1985 Tropecano et al. .................. 239/75
`4,575,330 3/1986 Hull ...................
`... 364/473
`4,595,816 6/1986 Hall et al. ........................... 364/477
`4,665,492 5/1987 Masters .........
`... 364/474.02
`4,681,258 7/1987 Jenkins et al. ........................ 239/83
`4,863,538 9/1989 Deckard .
`4,938,816 7/990 Beannan et al. .
`4,944,817 7/1990 Bourell et al. .
`OTHER PUBLICATIONS
`Article entitled "Instant Gratification', High Technol
`ogy Business Author-Gregory T. Pope-Jun. 1989.
`
`56)
`
`|||||||||||||||
`US00521329A
`5,121,329
`11) Patent Number:
`Jun. 9, 1992
`45
`Date of Patent:
`
`Asyntek Brochure, "Benchtop Automation' May
`1988.
`Primary Examiner-Joseph Ruggiero
`Assistant Examiner-Patrick D. Muir
`Attorney, Agent, or Firm-Moore & Hansen
`57)
`ABSTRACT
`Apparatus incorporating a movable dispensing head
`provided with a supply of material which solidifies at a
`predetermined temperature, and a base member, which
`are moved relative to each other along "X," "Y," and
`"Z" axes in a predetermined pattern to create three-di
`mensional objects by building up material discharged
`from the dispensing head onto the base member at a
`controlled rate. The apparatus is preferably computer
`driven in a process utilizing computer aided design
`(CAD) and computer-aided (CAM) software to gener
`ate drive signals for controlled movement of the dis
`pensing head and base member as material is being dis
`pensed.
`Three-dimensional objects may be produced by deposit
`ing repeated layers of solidifying material until the
`shape is formed. Any material, such as self-hardening
`waxes, thermoplastic resins, molten metals, two-part
`epoxies, foaming plastics, and glass, which adheres to
`the previous layer with an adequate bond upon solidifi
`cation, may be utilized. Each layer base is defined by
`the previous layer, and each layer thickness is defined
`and closely controlled by the height at which the tip of
`the dispensing head is positioned above the preceding
`layer.
`
`44 Claims, 3 Drawing Sheets
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`APPARATUS AND METHOD FOR CREATING
`THREE-DIMENSIONAL OBJECTS
`
`5,121,329
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`the art of stereolithography require the use of a vat of
`liquid comprising a photocurable polymer which
`changes from a liquid to a solid in the presence of light.
`A beam of ultraviolet light (UV) is directed to the sur
`BACKGROUND OF THE INVENTION
`face of the liquid by a laser beam which is moved across
`the liquid surface in a single plane, in a predetermined
`This invention relates to an apparatus and process for
`XY pattern, which may be computer generated by a
`forming a three-dimensional object of predetermined
`CAD system. In such a process the successive layers
`design, and in particular to the making of a model or
`may only be formed in a single, horizontal plane, with
`article by depositing multiple layers of a material in a
`successive layers which solidify in the liquid vat adher
`fluid state onto a base. The material is selected and its
`ing together to form the desired object. Such a process
`temperature is controlled so that it solidifies substan
`and apparatus is disclosed in U.S Pat. No. 4,575,330
`tially instantaneously upon extrusion or dispensing onto
`a base, with the build-up of the multiple layers forming
`issued to Charles W. Hull.
`U.S. Pat. No's. 4,752,498 and 4,801,477 issued to
`the desired article.
`Methods and techniques for making three-dimen
`Fudim disclose more recent methods for the production
`sional articles of a predetermined size and shape are
`of three-dimensional objects by irradiation of photo
`polymers within a liquid medium. Multi-layered objects
`known. In accordance with conventional techniques,
`the desired part is initially drawn, either manually or
`can be made in accordance with the teachings of those
`automatically utilizing a computer-aided design (CAD)
`patents by directing photopolymer solidifying radiation
`procedure, with the article being ultimately formed by
`20
`directly into a desired area within the uncured photo
`removing material from a block workpiece to form the
`polymer with the use of an immersed radiation guide.
`desired shape in a machine operation. The machining
`However, here again, such processes require the use
`operation may also be automatic with the utilization of
`and handling of curable photopolymer liquids which
`a computer-aided machining (CAM) process. This
`are hazardous, and do not permit the forming of ultra
`costly and time consuming process is repeated multiple
`25
`thin layers of material in building up an object with a
`times to perfect the final manufacturing of a part,
`very fine and smooth surface.
`model, or prototype. The designer's success is often
`U.S. Pat. No. 4,818,562 issued to Frank G. Arcella et
`dependent upon either the interpretation or the skill of
`al discloses a method form forming an article by direct
`the machinist making the prototype or model. This
`ing a laser beam to a fusible powder which is melted by
`common practice of mechanically removing material to
`the beam and solidifies on its surface to form an object
`create three-dimensional objects involves significant
`of desired shape. This process is also very expensive,
`machining skills and machining time. Chemical machin
`and is further complicated by the required use of a gas
`ing techniques available to form objects have depth
`which is directed through the powder to fluidize it.
`limitations and are incapable of making complex shapes.
`Impurities in the gas must ultimately be removed, and
`Thermal molding by injection or other molding tech
`the gas must be recirculated or vented by the use of
`niques requires expensive molds and a procedure better
`complex gas-handling apparatus.
`adapted economically for large runs where reproduca
`Devices also exist for the manual making of models or
`bility is required. With respect to jewelry applications,
`sample articles, such as jewelry, from wax by the use of
`nost custom jewelry is now produced manually.
`a wax dispensing gun from which the wax is dispensed
`The current state of the art does embrace processes
`in a heated, molten state. Such a wax-modeling gun is
`for making three-dimensional objects by building-up
`manufactured by the MATT Company, 663 Fifth Ave
`material in a pattern as prescribed by an article to be
`nue, New York, N.Y. Also, glue guns, such as that
`formed. U.S. Pat. No. 4,665,492 issued to William E.
`manufactured by Parker Manufacturing Company of
`Masters discloses such a process wherein a stream of
`Northboro, Mass., are available for heating and dispens
`particles is ejected from a supply head and directed to
`45
`ing adhesives in a fluid, molten state for gluing articles
`the coordinates of the three-dimensional article in re
`together. The Parker glue gun utilizes a glue stick
`sponse to data automatically provided from a CAD
`which is heated within the gun and dispensed as a
`system. This process requires a seed at the point of
`melted glue. However, neither the wax-molding gun
`origin of the article to which the particles are initially
`nor the known glue guns have ever been adapted or
`directed. The particles impinge upon and adhere to
`utilized in conjunction with mechanical means through
`each other in a controlled environment so as to build-up
`which the dispensing gun and/or a substrate may be
`the desired article. The Masters procedure requires the
`mechanically moved with respect to each other so as to
`use of two injection heads to achieve the desired three
`generate a predetermined, three-dimensional shape by
`dimensional article, requires a seed at the point of origin
`applying successive layers of material in a predeter
`about which the article is constructed, and thus does not
`55
`mined pattern.
`lend itself to the formation of successive layers of mate
`Thus, a need continues to exist for a relatively simply
`rial in a predetermined pattern as a relatively simple
`and efficient process and apparatus by means of which
`means for building-up an article, such as a model or
`designers may design and create three-dimensional ob
`prototype. The Masters system builds up the article
`60 jects at office work stations. The process and apparatus
`from a central seed by applying material to predeter
`disclosed herein meets that need with the same ease and
`mined coordinates. Such a process presents inherent
`simplicity of using a desk-top computer and printer,
`difficulties in holding close tolerances in the 0.001 inch
`with the entire modeling process being carried out at
`range and without accumulative error build-up.
`the operator's CAD work station.
`Processes and apparatus also exist in the prior art for
`producing three-dimensional objects through the for
`65
`BRIEF SUMMARY OF THE INVENTION
`mation of successive, adjacent laminae which corre
`This invention has as its primary objective the provi
`spond to adjacent cross-sectional layers of the object to
`sion of a process and apparatus by means of which
`be formed. However, known techniques of that type in
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`hering to the previous layer. A temperature controller
`three-dimensional object can be created at an office
`responsive to temperature sensors on the dispensing
`work station in a very time and cost effective manner. It
`head is used to closely control the temperature of the
`is anticipated that the invention will be particularly
`supply material to a level of about 1° C. above its solifi
`useful in the making of single prototypes or models of
`cation temperature at the point of discharge. This en
`products so that they may be quickly made and studied
`by designers. Products having complicated shapes may
`sures consistent flow and that the material will solidify
`substantially instantly upon cooling, after discharge,
`thus be evolved effectively and efficiently through im
`with resultant efficiency in the article-forming process
`mediate observation of design errors and repeated mod
`as multiple layers are discharged, solidify, and build-up.
`eling.
`A supplemental heater on the nozzle tip responsive to
`These basic objectives are realized by dispensing a
`the temperature controller provides the close control of
`material at a controlled rate from a dispensing head
`the temperature of the material as it is discharged, to
`unto a substrate or base member in a predetermined
`ensure that it is in a fluid state slightly above its solidifi
`pattern dictated by the shape of an article to be formed,
`cation temperature.
`with the material being dispensed in multiple layers
`These and other objects and advantages of the inven
`which solidify and adhere to each other to build up the
`tion will become readily apparent as the following de
`article. The process is controlled so that the material in
`scription is read in conjunction with the accompanying
`the preceding layer, and in particular at least the mate
`drawings wherein like reference numerals have been
`rial under the dispensing head, has solidified before
`used to designate like elements throughout the several
`additional material is applied on top of it to form a
`subsequent layer.
`WeWS.
`Advantageously, material is applied in a fluid state in
`BRIEF DESCRIPTION OF THE DRAWINGS
`very thin layers which adhere to the preceding layers in
`FIG. 1 is a perspective view showing one version of
`a multiple laminate of exceptionally smooth surface
`the apparatus for forming three-dimensional objects;
`quality. The dispensing head is controllably elevated
`FIG. 2 is a diagrammatic view showing the comput
`along a "Z" axis so as to sequentially form layers of
`25
`er-aided design system for operating the article-forming
`material as thin as 0.0001 inches or as great at 0.125
`apparatus;
`inches in thickness. The thickness of each layer is con
`FIG. 3 is a vertical section view of the dispensing
`trolled by regulating the gap between the dispensing
`head and the previously-formed layer.
`head of FIG. 1;
`FIG. 4 is a fragmentary view showing the dispensing
`In order to mechanically form each successive layer,
`head applying multiple layers of material;
`drive motors are provided to selectively move the base
`FIG. 5 is an elevation view of a different embodiment
`member and dispensing head relative to each other in a
`of the material-applying apparatus utilizing a flexible
`predetermined pattern along "X" and "Y" axes as mate
`strand as the supply material;
`rial is being dispensed. Relative vertical movement
`FIG. 6 is a fragmentary, section view of a modified
`along a "Z" axis may also be carried out during the
`35
`form of dispensing nozzle showing multiple flow pas
`formation of each layer, as well as at the completion of
`each layer to achieve desired layer shape and thickness.
`Sages;
`FIG. 7 is a fragmentary, perspective view of a mani
`Such mechanical movements are preferably achieved
`fold type of material dispenser having multiple outlets;
`through drive signals inputed to the drive motors for
`FIG. 8 is a verticle section view of the manifold and
`the base member and dispensing head from a com
`40
`valve assembly of FIG. 7;
`puter/controller CAD/CAM system. In such a system
`FIG. 9 is a diagrammatic illustration showing how
`the design of an article to be formed is initially created
`multiple layers of material can be built up in varying
`on a computer, with commercially available software
`heights and thicknesses; and
`being utilized to convert the three-dimensional shape
`FIG. 10 is a diagrammatic illustration showing how
`into multiple layer data which is transmitted as drive
`45
`material can be dispensed and formed in free space by
`signals through a computer-aided machine (CAM) con
`the apparatus of this invention.
`troller to the aforesaid drive motors. Each layer can
`FIG. 11 is a bottom plan view of an alternative multi
`have its own distinctive shape as controlled by the pro
`ple orifice dispensing head as viewed along lines 11-11
`gram in the CAD system, and the layers may have
`of FIG. 6; and
`different thicknesses.
`FIG. 12 is a diagrammatic illustration showing how a
`The article-forming material is preferably supplied to
`wire frame article can be formed by the apparatus of
`the dispensing head in the form of a flexible strand of
`solid material from a supply source, such as a reel. A
`this invention.
`rod of solid material may also be used as the material
`DESCRIPTION OF THE PREFERRED
`supply medium on the dispensing head. In either case,
`55
`EMBODIMENTS
`the material is heated above its solidification tempera
`Referring now to the drawings, FIG. 1 illustrates one
`ture by a heater on the dispensing head and applied as a
`embodiment of the apparatus of this invention for mak
`fluid. Preferably, the dispensing head includes a flow
`ing three-dimensional articles, the apparatus being gen
`passage connected to a discharge outlet in a nozzle from
`erally indicated by reference numeral 1. The apparatus
`which the fluid material is dispensed. The nozzle may
`includes a movable dispensing head 2 having a dis
`advantageously function as a "doctor blade' acting on
`charge nozzle 4 at its bottom end, dispensing head 2
`the surface of each layer as it is formed to closely con
`being supported from a pedestal 6 by a mounting arm 8.
`trol the thickness of each layer.
`Dispensing head 2 is located in close proximity to a base
`Various material, including waxes, thermoplastic
`member comprising a plate 10 on which an article to be
`resins, and metals may be used to form three-dimen
`formed is built up as hereinafter set forth.
`sional articles as described herein. The material is pref.
`Dispensing head 2 and base plate 10 are supported for
`erably one which will melt at a preselected temperature
`and rapidly solidify without shrink distortion upon ad
`mechanical movement relative to each other. In the
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`the working material is supplied in the form of a solid
`preferred embodiment shown, this is accomplished by
`rod 46, heated to its melting point in dispensing head 2
`providing mechanical means for translational move
`ment of base plate 10 laterally along "X" and 'Y' axes
`and dispensed from nozzle 4 as a flowable fluid.
`Various material may be used for the rod, including
`of a base plane and for vertical movement of dispensing
`bees wax. casting wax, machineable and industrial
`head 2 along a 'Z' axis. Accordingly, as is shown in
`waxes, parafin, a variety of thermoplastic resins, metals,
`FIGS. 1 and 2, base plate 10 is supported on an X-Y axis
`and metal alloys. Suitable metals include silver, gold,
`table 12 having a slide rod 14 in threaded engagement
`platinum, nickel, alloys of those metals, aluminum, cop
`within its drive block 16 with a drive screw 8. A drive
`per, gold, lead, magnesium, steel, titanium, pewter,
`motor 20 provides rotary power to drive screw 18.
`manganese bronze. Glass, and particularly Corning
`Slide rod 14 also carries an elongated drive screw 22
`glass, would also be satisfactory. Materials of varying
`driven by a second motor 24 and coupled to mating
`degree of transparency would be useful in forming cer
`threads (not shown) secured to the underside of base
`tain objects, such as for forming windows in model
`plate 10 for driving engagement therewith. It will thus
`buildings. Chemical setting materials, including two
`be seen that article-receiving base plate 10 may be
`part epoxys would also be suitable. Materials which
`moved along the X and Y axes indicated in FIG. 1 by
`have been found to be particularly suitable for making
`the selected actuation of motors 24 and 20, respectively.
`three-dimensional objects with the apparatus disclosed
`Separate mechanical drive means are provided for up
`and down vertical movement of dispensing head 2. For
`herein include Freeman "machineable wax' manufac
`tured by Freeman Manufacturing and Supply of Cleve
`that purposed, head 2 is mounted for vertical movement
`land, Ohio, "Friendly Plastic' thermoplastic manufac
`on a micro-slide bearing 26 on one end of support arm
`20
`8 by a bracket 28. One apertured end of right angle
`tured by Friendly Plastic of Boulder, Colo., bismuth
`153 alloy manufactured by Metal Specialties of Fair
`bracket 28 is threadedly engaged with a drive screw 30.
`A third drive motor 32 supplies driving, rotary power
`field, Conn., and Thermoplastic Polymer No. 235-10,
`Specification No. 11061 sold by Ad-Tech of Hampton,
`to screw 30 and is mounted on support arm 8 by bracket
`34 as shown. Selected actuation of reversible motor 32
`N.H.
`25
`Supply rod 46 is inserted into supply chamber 50 of
`thus rotates screw 30 to provide up and down vertical
`dispensing head 2 through a guide sleeve 48 as is best
`movement of dispensing head 2 on slide bearing 26. For
`that purpose, motor 32 is preferably a high resolution
`shown in FIG. 3. Various means may be utilized for
`advancing supply rod 46 through supply chamber 50 as
`stepper motor. It is to be noted, however, that various
`material from the rod is dispensed through nozzle 4.
`types of motors could be used for drive motors 20, 24,
`30
`One suitable means which has proven to be suitable for
`and 32, including stepper motors, linear motors, servo
`that purpose comprises a drive rod 52 which is attached
`motors, synchronous motors, D.C. motors, and fluid
`as an extension to reciprocating piston 54 of a power
`OtOS.
`cylinder 56. Cylinder 56 is a fluid cylinder which is
`Preferably, for fully-automated operation, motors 20,
`24, and 32 are computer-controlled by drive signals
`preferably actuated by a supply of pressurized air
`through air line 58 from air compressor 60 and its re
`generated from a computer 36, by means of which a
`ceiver tank 62 in which a reservoir of compressed air is
`computer-aided design (CAD) can be created at a de
`maintained. Air from the compressor/receiver 60/62 is
`sign person's work station. Support table 12 on which
`delivered through supply line 58 and a 3-way solenoid
`base plate 10 is carried is of such a size that it can be
`valve 64 and a pressure-regulating valve 66 to air cylin
`located on a desktop. Thus, by operation of the com
`der 56. A pressure gauge 68 is connected to the air
`puter keyboard 38 as shown in FIG. 1, a three-dimen
`pressure regulator 66, all as shown in FIG. 1.
`sional article can be designed and created at a single
`Drive rod 52 is connected by a pivotal link 70 to a
`office work station by one operator, in the manner here
`ratchet head 72 having one or more ratchet teeth 74
`inafter set forth. As is indicated schematically in FIG. 2,
`which engage supply rod 46 to advance it downwardly
`the design of a three-dimensional article 40 is inputted
`45
`within supply chamber 50 of dispensing head 2 towards
`to computer 36 utilizing commercially available CAD
`dispensing nozzle 4. For that purpose, a predetermined
`software. The article design is sectioned into multiple
`air pressure, preferably at a constant level, is maintained
`layers by a commercially available software program to
`provide multiple-layer data corresponding to the partic
`on top of piston 54 within cylinder 56 so as to move
`drive rod 52 downwardly. It will be understood that as
`ular shape of each separate layer. Such software pro
`50
`rod 52 is moved downwardly, ratchet teeth 74 on
`grams are in commercial use for computer-aided ma
`chining (CAM) purposes, and include NC Polaris,
`ratchet head 72 will advance supply rod 46 down
`wardly within chamber 50. Drive rod 52 extend
`Smartcan, and Mastercan. AUTOLISP, has been suc
`through an apertured bracket plate 78 within supply
`cessfully used to layer AUTOCAD drawings into mul
`tiple layers or sections of specific patterns and dimen
`chamber 50, bracket plate 78 serving as a stop for a
`55
`return spring 76 acting on the bottom of piston 54.
`sions. The layering data signals are directed to a ma
`Supply rod 46 is heated within heating head 84 to a
`chine controller 44 from the layering software 42 as
`predetermined temperature at which it will exceed its
`shown diagramatically in FIG. 2. Controller 44 in turn
`solidification temperature and melt to a flowable, fluid
`is connected to the X, Y, and Z drive notors 24, 20, and
`form. For that purpose, a main or primary cartridge
`32, respectively, for selective acuation of those motors
`type, electric resistance heater 80 is provided within
`by the transmission of the layering drive signals.
`heating head 84 within supply chamber 50 of dispensing
`Various materials in different forms may be used for
`head 2. A suitable seal ring 83 is provided around the
`making three-dimensional articles with the apparatus
`top of heating head 84. An electrical power lead 82 is
`described herein. It is preferred that the material be one
`which is thermally solidifiable from a fluid state in
`connected to resistance heater 80 as shown in FIG. 3.
`65
`which it is applied, either at room temperature or at a
`Heater 80 is closely controlled in order to heat the solid
`predetermined temperature by the use of a cooling me
`material of supply rod 46 to a temperature slightly
`above its melting point, and preferably on the order of
`dium. FIGS. 1 and 3 illustrate one embodiment in which
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`timer 106 as shown schematically in FIG. 1 may be
`l' C. above the melting point of the rod material. This
`is accomplished by the use of an electronic temperature
`utilized to time the downward movement of supply rod
`46 and to initiate the return of drive rod 52 at the expira
`controller 86 connected by an electrical lead or conduit
`tion of a predetermined time interval. Either type of
`90 to a first thermocouple-sensing element 88 as shown
`in FIGS. 1 and 3. Thermocouple 88 is located as shown
`control device would be connected to air valve 64 So as
`in close proximity to the supply rod 46 within heating
`to de-energize that solenoid valve and cut off the supply
`of pressurized air to the top of drive cylinder 56. When
`head 84 so as to be able to sense the temperature to
`which the supply material is being heated. Temperature
`that happens, return spring 76 urges piston rod 54 back
`controller 86 has a main, adjustable controller as indi
`upwardly. That movement is further assisted and per
`cated in FIG. 1 which is set to a predetermined temper
`mitted by the use of a quick release, vent valve 55 con
`ature to which the supply rod material is heated by
`nected to the fitting on the top of air cylinder 56 as
`resistance heater 80, in response to sensing signals re
`shown in FIG. 1. When the supply of pressurized air
`ceived from thermocouple 88.
`through line 58 to air cylinder 56 is cut off by the clos
`A heater blade 92 forming a part of the heating assem
`ing of valve 64, the upward movement of piston 54
`bly is embedded in the supply-rod material as shown in
`under the action of return spring 76 expells the air in the
`FIG. 3 and serves to directly heat it to the predeter
`top of cylinder 56 through valve 55. At the top of the
`mined temperature. At its lower end, supply chamber
`return stroke of drive rod 52, ratchet head 72 takes a
`50 communicates with a flow passage indicated by ref.
`new grip on supply rod 46. Air valve 64 is then re
`erence numeral 94 and extending through discharge
`opened at a timed interval by timer 106 to again intro
`nozzle 4 to a dispensing outlet in the form of an orifice
`duce a supply of pressurized air on top of drive piston
`98 of predetermined size at the bottom end of nozzle 4.
`54 within cylinder 56. The downward, supply move
`A spring-loaded ball check valve 96 is located within
`ment of rod 46 is then reactivated. As supply rod 46
`flow passage 94, and opens to assist in metering the
`moves downwardly within chamber 50, it is heated
`outlet flow of fluid material in response to the pressure
`within heating head 84 to its melting point. As a result,
`maintained on the supply rod 46 within supply chamber
`liquid material flows downwardly into flow passage 94
`50. Check valve 94 also eliminates leakage from nozzle
`and cut through dispensing outlet 98.
`4 when the system is stopped, even temporarily. Supply
`The opening and closing of air valve 64 to regulate
`material from rod 46, reduced to a liquid state by heater
`the supply of pressurized air, and thus the supply of
`80 upstream of flow passage 94, flows downwardly into
`material in a fluid state through dispensing head 2 and
`said flow passage and into dispensing outlet 98 from
`its dispensing outlet 98 may also be accomplished by
`which it may be discharged onto base plate 10 to form
`means of a relay 104 shows schematically in FIGS. 1
`layers of material in the course of building up an article.
`and 2. As is indicated in FIG. 2, relay 104 is responsive
`The size of dispensing outlet 98 may be varied for the
`to the software layering signals directed to the drive
`particular application, as by using interchangeable ori
`motor 32 which provides vertical movement of dispens
`fice inserts in the tip of nozzle 4. Also a variable size
`ing head 2 along a "Z" axis. Relay 104 may thus be
`orifice of the type employed in cameras for varying the
`energized and de-energized to open and close air valve
`aperture could be utilized.
`64 in response to programmed signals indicative of
`It is desired to discharge the supply material in a fluid
`upward and downward movement of dispensing head 2.
`state at a temperature only very slightly above its solidi
`As hereinafter set forth, it may be desirable when build
`fication point, so that the material will solidify very
`ing certain types of articles to close air valve 64 and cut
`rapidly upon cooling after discharge onto base plate 10.
`off the supply of material 46 when dispensing head 2 is
`To ensure that the supply material is discharged from
`moved upwardly to commence the formation of se
`outlet 98 at the desired, predetermined temperature and
`quential layers a predetermined vertical distance above
`that the material is maintained in a liquid state through
`each previously formed layer. When the supply of pres
`out flow passage 94, and does not solidify therein, a
`45
`surized air to cylinder 56 is shut off, spring-loaded
`supplemental electric heater 100 is provided on the tip
`check valve 96 closes flow passage 94.
`of discharge nozzle 4 adjacent to fluid passage 94. Tem
`With the above-described embodiment, utilizing a
`perature controller 86 has a second, adjustable tempera
`solid rod 46 as the source of supply material for forming
`ture regulator for the tip heater 100 as indicated in FIG.
`an article, the metering of the material onto base plate
`1. That temperature regulator receives control signals
`50
`10 at a predetermined rate is accomplished by a combi
`from a second sensing device in the form of a thermo
`nation of the preselected size of dispensing outlet orifice
`couple 102 attached to nozzle 4 in close proximity to
`98 as well as by the preselected, constant pressure main
`flow passage 94 near its outlet end. As is also indicated
`tained on piston 54 so as to control the rate at which
`in FIG. 1, the electrical connectors for thermocouples
`supply rod 46 slowly advances through supply chamber
`88 and 102 both extend through power lead or conduit
`50 of dispensing head 2 as it is heated and reduced to a
`90 connected to the temperature regulators for the main
`liquid state. The metered flow of material is also con
`heater 80 and for tip heater 100 on temperature control
`trolled by the gap or vertical height of the tip of nozzle
`ler 86.
`4 above the last layer and by the material viscosity.
`As drive rod 52 moves downwardly towards the end
`Various substrates may be utilized to receive an arti
`of its rod supply stroke to bring ratchet head 72 near the
`cle being formed on top of base plate 10. Relatively fine,
`position shown in FIG. 3, the piston 54 and drive rod 52
`wire mesh sandpaper 108 as shown in FIGS. 1 and 2,
`must be retracted upwardly in order that ratchet head
`has been found to be particularly satisfactory for that
`72 with its teeth 74 may take a new grip along supply
`purpose. After an article 4.0a is formed on the sandpaper
`rod 46 near its upper end. The upward and downward
`108, corresponding to a master article 40 to be copied as
`movement of drive rod 52 may be controlled by a limit
`65
`shown in FIG. 2, the sandpaper substrate or foundation
`switch within dispensing head supply chamber 50,
`may be readily peeled off of the bottom of the article
`which is activated by the downward movement of
`without damage.
`ratchet head 72 or pivotal link 70; or, alternatively, a
`
`30
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`35