@uropaisches Patentamt

J) •uropean Patent Office ® Publication number: 0 1 79 940

Office europeen des brevets B1 g) EUROPEAN PATENT SPECIFICATION

® Dateof publication of patent specification: 21.09.88 ® Int. CI. : C 23 r 1/04, bObB ia/4Ub, G 05 B 19/19 Jj) Application number: 84113095.8 ® Date of filing: 31.10.84

54) An automated chemical milling process.

® Date of publication of application: @ Proprietor: GRUMMAN AEROSPACE 07.05.86 Bulletin 86/19 CORPORATION . South Oyster Bay Road Bethpage,NY11714(US) (45) Publication of the grant of the patent: 21 .09.88 Bulletin 88/38 _ (72) Inventor: Org,_ Lawrence, H. 21 Robin Drive ® Designated Contracting States: Hauppauge New York (US) CH DE FR GB LI NL SE Inventor: Jaffee, Herbert R. 7 Country Drive Plainview New York (US) (§) References cited: Inventor: Mitzelman, Irwin EP-A-0 122941 49 Wildwood Drive US-A-3 803 960 Wantagh New York (US) US-A-3 881 379 US-A-4117 751 _ „ L ._, „ US-A-4120 583 ® Representative: Schmidt-Evers, Jurgen, Dipl.- US-A-4137118 Ing.etal US-A-4 340 166 Patentanwalte Dipl.-lng. H. Mitscherlich Dipl.- US-A-4 364 1 10 ln9- K- Gunschmann Dipl.-lng. Dr.rer.nat. W. US-A-4 370 720 Korber Dipl.-lng. J. Schmidt-Evers Dipl.-lng. W. US-A-4 371 923 Melzer Steinsdorf strasse 1 0 D-8000 Munchen 22 (DE)

Within nine months from the publication of the mention OTtne gramoTine nuropedn paicm, a,,y .-=y Note- shall notice to the European Patent Office of opposition to the European patent granted. Motice of opposition give fee has been be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition convention). paid. (Art. 99(1 ) European patent ^_ Courier press, Leamington spa, cngiana. 1 0 179 940 2 Description contemplated. In the event multiple etching baths are desired, the cut mask line is recovered with a The field of the present invention relates to an sealant material. After all of the stencil marks improved automated method for chemically mill- have been cut, and the secondary cuts have been ing metal and metallic structures. Chemical mill- 5 coated, one portion of the mask material is ing is widely employed in the aircraft and aeros- removed. The metal plate is then milled and pace industries to remove excess metal from rinsed in a counterflow rinse water. The second metal parts wherein the removed metal is not mark are is removed, and the workpiece is essential to the strength of the component part. reimmersed in the etching bath. The workpiece is The chemical milling process normally employs a io rinsed again and the process is repeated for the series of masking and metal removal steps. The desired number of milling steps. At the conclu- metal is removed by an etching or milling bath sion of the milling step, the workpiece is "de- which may be either caustic or acid depending smutting". A typical "de-smutting" agent is dis- upon the metal or alloy being milled. Chemical closed in U.S. Patent 3,988,254. milling may be used to produce one piece struc- w There are two problems in the present prior art tures having a skin and load bearing ribs or method of chemical milling that are solved by the stiffeners that provide lightweight alternatives for present invention. traditional aircraft skin and stringer constructions. a) controlling the depth of the cut through the The prior art has used chemical milling to masking material. At present, the mask is hand- reduce the weight of metal parts intended for use 20 scribed by skilled workmen. If the cut is too deep, in aircraft or aeronautic applications for over the cut allows the etching bath to mill the metal twenty years. Chemical milling is widely used to and undercut the mask. If the cut is too shallow, increase the strength to weight ratio of com- and the mask material is not completely severed, ponents parts in the aircraft airframe. Chemical it will "blowout", blister or tear when that portion milling traditionally involves the steps of masking 25 of the mask is removed. This necessitates a time- and chemically milling a metallic workpiece and consuming repair step for the stencil mask. In may repeat the sequence several times to further addition, if the "blowout" is not detected, the alter the workpiece configuration. workpiece will be undercut by the etching sol- U.S. Patent 4,137,118 discloses a method of ution. chemically milling an efficient lightweight struc- 30 b) the time consumed in laying each stencil on ture by removing excess metal to form the ribs the workpiece, marking each line to be cut and and skin of an aircraft structure. The milling step cutting each line by hand is substantial. A typical is repeated to sequentially undercut and impart three-feet (0.9 m) by four-feet (1.2 m) workpiece an "I" or "1" section to the ribs and to reduce the requires six to eight hours of hand labor to thickness of the skin. 35 handmark and cut each of the areas to be U.S. Patent 3,745,079 discloses a method of chemically milled. The automated process of the chemically milling a titanium alloy stock for use present invention can do the same marking and as a structural member in an aircraft. cutting in 11 minutes. In addition it can perform U.S. Patent 2,888,335 discloses a process of cuts that cannot be done by hand. chemically milling a workpiece that sets forth a 40 If the chemical milling is done on a three- method of sequentially milling the workpiece with dimensional workpiece, all of the foregoing multiple cuts in the mask material to produce a problems are accentuated. In addition, it is plurality of milled levels in the workpiece. in necessary to preform the metal part around a between each etching bath, a portion of the mask master mold in a molding or die-stamping step to is removed so that the final configuration has a 45 provide the desired three-dimensional configura- milled pattern of varying depths throughout the tion. Each of the stencils must be provided with workpiece. the appropriate compensation for three-dimen- U.S. Patent 3,380,863 discloses masking sional positioning. In the present prior art prac- g material for use in chemical milling having a tice, after the metal plates have been preformed styrene/butadiene block copolymer composition. so to an approximate three-dimensional configura- This material is widely used in chemical milling tion, they are pinned to a master moid, and the processes for masking the part to be protected individual stencils are also pinned to provide during the etching bath. intimate contact between the stencil and the At the present time, the prior art methods workpiece. Further, the three-dimensional nature comprise the steps of marking the aluminum or 55 of the workpiece makes it even more difficult to titanium stock with a reference mark or tooling accurately handcut the stencil to the desired hole for conveying the stock through the etching depth. solution. The metal part is then covered or coated The present invention involves the new use of with the butadiene/styrene copolymer masking two existing devices which have heretofore been material. A template is laid over the masking 60 used for other tasks. material and the masked material is handcut In the drafting and cartography fields, large along the template line. The masking material is computer operated drafting machines have been then marked with a marking pen along the cut or used to mark blueprints and scribe plastic stencils scribe line. These steps are repeated with that are intended for use in photoredproduction separate masks when separate milling levels are 65 processes. These machines are quite large.

2 ) 179 940 laving a drafting area that may be 8 feet (2.4 m) new template geometry on a l.k i via an existing vide by 34 feet (10.4 m) long. A motorized carriage computer program that is currently sold under the raverses the drafting bed in both the x and y "CADAM" tradename. This program will define dimensions and carries on its carriage a plurality of the x and y coordinate values of the newly created stored narking pens. One such device is the Kongsberg 5 mask before they are digitized and on I800S Series Flatbed Drafting Table. This drafting magnetic tape. able may be fitted with a variety of drafting tools The present invention relates to an automated ncluding a tangentially controlled scribing tool, chemical milling process for metals, said process rhis tool uses a single knife or chisel and is comprising coating the metal to be chemically normally used for cutting and stripping material ro milled with a resist coating, digitizing the area(s) to jsed in the photoreproduction of integrated cir- be chemically milled, to define at least x and y :uits. The knives are used to scribe coated films. coordinate values for the perimeter of the area(s) U.S. Patent 3,555,950 discloses a device for to be chemically milled, automatically scribing the automatically cutting a photomask for use in metal and coating with a scribing tool, said sroducing integrated circuits. In this device, the w scribing tool cutting through said coating along aluminum foil is cut, and the plastic laminate the perimeter defined by the x and y coordinate naterial is retained to define an optically trans- values, removing the resist coating from the jarent negative for producing an integrated circuit area(s) to be chemically milled and immersing said aoard. partially coated metal into an etching solution for a Computer controlled cutting means have been w predetermined period of time to remove a pre- /videly used in the garment industry for cutting determined amount of metal from the uncoated ane or more sheets of fabric to a desired pattern area(s). It includes digital automation and the size. These devices also have drive motors for application of two separate and existing devices to noving a cutting tool in x and y directions. a field of use in which they have not been Examples of computer operated cutting devices ?5 previously used. The present invention includes 3re disclosed in U.S. Patents 3,803,960, 3,805,650, the steps of coating the metal that is to be milled 3,895,358, 3,991,636 and 4,171,657. with an etchant resistant mask, such as a styrene While the foregoing devices have been used for copolymer. The perimeter of the area to be computer controlled cutting of cloth and photo- chemically milled is then digitized to define a masks in the prior art, the have not been used or 30 plurality of point definitions along the x, y axis of applied to the chemical milling process. The the flat metal stock, or through a set of x, y, z axes chemical milling process has remained essentially for three-dimensional workpieces. If more than unchanged for over 20 years. The computer con- one area is to be chemically milled in a sequential trolled flatbed drafting tables and cutting tables millingprocess, the values of all of the coordinates have been in existence for over 10 years. To the 35 are defined and stored on a magnetic storage best of applicants' knowledge, these devices have medium such as a magnetic tape, a disc drive or a not been used in the chemical milling process, and bubble memory means. their use in this field provides significant advan- The process includes the step of automatically tages in both speed and accuracy. scribing the metal and the coating with a scribing The foregoing devices, while suitable for 40 tool wherein the scribing tool cuts through the application to chemical milling involving flat stock, resist coating along the perimeter defined by the x, are not sutable for use in chemical milling pro- y coordinate values or by the x, y, z coordinate cesses on three-dimensional workpieces. For values on three-dimensional workpieces. After three-dimensional milling, the tangentially con- each of the mask areas have been scribed, the cut trolled scribing tool is mounted on a robotic device 45 lines are marked for visibility to assist the operator the that may be computer controlled through the x, y, z in removing areas of the resist coating prior to dimensions to provide an accurate scribing depth milling step. If the workpiece is to be involved in a as the robotic device traverses the three-dimen- sequential milling operation, the sequential cut sional contoured surface. One robotic device that lines are recoated with a temporary sealant to scribe may be modified for use in the chemical milling so preventthe entry of the etching bath into the process is manufactured by ASEA, Inc. and is line. described in the ASEA pamphlet YB 11-101 E. After the resist coating has been removed from Both the ASEA robotic device, and the Kong- the area(s) to be chemically milled, the workpiece sberg Drafting Table are capable of traversing an is immersed into an etching solution for a pre- existing template to derive a series of point-by- ss determined period of time to remove a predeter- point measures along the perimeter defined by the mined amount of metal from the uncoated area(s). template. These point-by-point measurements After this step has been completed, the etching may be recorded and stored on magnetic tape. bath is neutralized with a counter-flow water bath. These point-by-point measurements may then be If sequential milling steps are involved the second used to scribe the mask covered workpiece with 60 resist coating covering the second area to be the tangentially controlled scribing tool carried by chemically milled is removed, and the partially the Kongsberg plotter or the ASEA robot. coated metal is then reimmersed in the etching An alternate mans of generating the instructions solution for a predetermined period of time. This for controlling the movements of the robotic series of steps is then completed until the work- device or the flatbed drafting device is to create 65 piece has been milled to its final configuration.

3 5 D 179 940 3 Following the final etching bath, the workpiece is Figure 8 is a diagrammatic view of the ASEA then "de-smutted" to remove the layer of metallic robotic device and a three dimensional work- residue left by the etching bath. piece. The present invention includes the digitizing of Figure 9 is a diagrammatic illustration of x, y, z existing masks to form x, y coordinate values for 5 and y coordinate axes. each of the perimeter lines defined by an existing Figure 10 is a partially cross sectional and mask with respect to either two or three dimen- perspective view of a portion of a three-dimen- sional workpieces. Alternately, new template sional workpiece formed by the present inven- geometry may be created on a CRT connected to tion. a CPU having the appropriate software. One io Figure 1 1 is a perspective view illustrating the software program particularly appropriate for the registration or tooling holes that may be formed creation of new template geometry is the CADAM by the present invention. software, a commercially available licensed soft- Referring to Figure 1, the automated chemical ware package. milling process of the present invention is set The present invention uses an electronically is forth in a diagrammatic flow chart. The aluminum controlled scribing tool that exerts a predeter- alloy or titanium alloy feed stock 11 is first cut to mined amount of pressure against a cutting knife size for the part to be produced, or a series of which engages the resist coating and the base parts when a plurality of parts are intended to be metal to be chemically milled. The cutting produced from a single piece of feed stock. If the pressure may be very carefully controlled to 20 feed stock is a flat stock, it then proceeds to the provide an even and accurate cutting depth flow coating process 12 wherein it is flow coated through the resist coating and .001 inch (25.4 urn) with the styrene/butadiene copolymer resist mask into the workpiece. sold under the brand name of "Turco Mask 522". The present invention may also be used with "Turco" is currently available from Turco Pro- "nesting" software to mill a plurality of metal 25 ducts, Inc., Wilmington, California. If the feed parts from a single large piece of metal stock stock is intended for use as a three-dimensional wherein each of the parts are milled simul- workpiece and is not provided as a three-dimen- taneously by the milling bath. An example of one sional feedstock, it then proceeds to a contouring type of software capable of "nesting" the parts or stamping step 13 wherein the flat feed stock is onto a metal plate is the CAMSCO software, a 30 contoured to the desired three-dimensional con- commercially available licensed software pack- figuration. age. After the feed stock has been coated with the- Therefore the present invention provides an styrene/butadiene copolymer, it then proceeds to automated chemical milling process for the mask cutting step 14. As was indicated pre- chemically milling metal or metallic parts. 35 viously in the prior art, the mask cutting was The advantages of the present invention may accomplished by laying a template over the feed be more readily understood by one skilled in the stock and marking the outline of the template on art with reference being had to the following the feed stock. The marked outline is then hand- detailed description of the several preferred cut so as to cut through the resist coating and embodiments thereof, taken in conjunction with 40 lightly score the surface of the metal workpiece. the accompanying drawings wherein like The desired depth of cut into the metal workpiece elements are designated by identical reference is .001 inches (25.4 urn). Current military speci- numerals throughout the several views, and in fications for use in aircraft intended for purchase which: by the United States Government prescribe a Figure 1 is a schematic flow chart of the method 45 maximum cut into the workpiece of .004 inches or process of the present invention. (101.6 um). If the cut is too deep, the subsequent Figure 2 is a diagrammatic illustration of the milling step will, undercut the resist coating, and if tangentially controlled scribing tool, the resist the cut is not deep enough, it will cause a "blow- coating and a metal workpiece to be chemically out" when the center portion of the template is milled. so removed for milling. The "blow-out must then be Figure 3 is a cross section view of the metal retouched by hand, when is a time consuming, workpiece illustrated in Figure 2 after the milling labor intensive operation. step. The present invention automates the chemical Figure 4 is a cross section and diagrammatic milling processed by one of three separate begin- view which illustrates the sequential milling pro- 55 ning steps. As indicated at 15, an existing tem- cess. plate may be placed on top of the workpiece, and Figure 5 is a curve illustrating the depth of the an optical scan mode of the template. All of the cut made by the tangentially controlled scribing initial starting marks, the workpiece size, the device in response to various "force settings". template number and other desired information is Figure 6 is a perspective view of the carriage 60 keyed into memory along with the optical scan to assembly that carries the tangentially controlled provide the data necessary to align the cutting scribing device, the markers and the recoating device at the appropriate point on the workpiece device for sealing previously scribed cuts. when the mask cutting operation 14 begins. In Figure 7 is a perspective view of the Kongsberg lieu of using an optical scanning device, a stylus Flatbed Drafting Table. 65 may be used to trace the outline of the template

4 7 0 179 940 8 while each of the reference points along the In digitizing an existing template for the robotic template are keyed into memory via the CRT. For device, a similar process is followed. The "ASEA" a simple, flat two-dimensional workpiece, each of robot is equipped with its own computer the straight lines could be keyed by placing the guidance system and is normally programmed by stencil at the corner and keying in the positional 5 the "teach" method which uses a robotic tracking data and cut orientation. The stencil would then method of tracing the stencil with a stylus to be moved to the end of that particular straight line "teach" the robot the desired contour to be and the second key point set of data would be followed. The "ASEA" robot is currently available entered. These steps would be repeated around from "ASEA, Inc.", 4 New King Street, White the entre perimeter of the template until the w Plains, New York 10604. The stencil attached to desired area to be chemically milled had been the robot is placed manually at the initial ref- completely defined by the reference point data. erence starting position, and that key point data is In the event the workpiece was intended in a entered. This operation "teaches" the robot that sequential or multiple milling process, the next this position is to be assumed with respect to template describing the second area to be 15 programmed operation for all future beginning chemically milled would then be overlaid with reference points. The digital positioning values respect to the initial reference marks, and it would for all three axes and the required traverse speeds be optically scanned, or traced with a stylus pencil are then stored in the computer memory. The to derive the key point data for the existing robot is then moved manually along the template template. 20 to the next position and the second set of x, y, z Simultaneously with the optical scan and the coordinate values is entered. The second set is initial key data steps, the CPU 16 would be then stored in memory, and these steps are digitizing the x, y coordinate values of each of the completed until the perimeter of the template has key points entered at 15. The digitizing step is been completely traversed by the stencil. For long indicated us a separate step 17 in Figure 1 25 straight cuts along a two-dimensional plane, only inasmuch as a variety of methods for digitizing an two entry points needs be entered. Along a existing template exist. Two methods for digitiz- complex curve or a three-dimensional curve ing an existing template were set forth above, but traversing all three x, y, z axes, each coordinate is apparent to one skilled in the data processing value ring a shift in the rotationais axes of the art that a variety of methods could be used to 30 robot need to be entered. Once the entire outline define the x, y coordinate values and convert of the three-dimensional template has been them to digital form for use in a conventional CPU entered into the robotic memory, it can then be 16. transferred to a magnetic storage medium such After the template has been converted to digital as magnetic tape or a disc drive. form, a printout is produced as indicated at 18. 35 The reference point data is used as a simple This printout may be done with a Kongsberg way of obtaining coordinate transformation in flatbed drafting table similar to the one that will straight line positioning for the robot. The ref- be used with respect to the mask cutting oper- erence point entered by the key point data at 19 ation 14 later on in the process. The Kongsberg does not cause any robotic motion, it simply flatbed drafting table is currently available from 40 defines the first, second, third ... n, points of the "Kongsberg North America, Inc.", 135 Fort Lee pattern of movement to be traversed. The dis- Road, Leonia, Jew Jersey 07605. Any printout tance and direction to the subsequent reference device will work providing it is capable of generat- point is calculated between reference points and ing a full size template that may be physically executed relative to the point in space at which checked against the template that was entered via 45 the robot is situated before the next reference the optical scan or key data entry indicated at 15. point is entered. The entry of the x, y, z coordinate values for the The ASEA robot will work in one of two modes. robotic device is similar to that used for the If point-to-point control is selected, each of the digitizing of existing templates for flat feed stock. several axes that have to move simultaneously to As was indicated previously, it is customary to 50 reach a new point begins at once, and the trajec- initially preform flat feed stock into its desired tory is not controlled. All axes will start at the three-dimensional configuration as indicated at same position, and each motor will stop when its 13. The preformed flat stock is then placed onto a driven portion has reached its new programmed master mold which is very precisely contoured position. with respect to the desired final configuration. A 55 The robotic device is also equipped with a three-dimensional template is then placed over separate instruction function wherein the motor the feed stock and the resist coating is then cut. speed for each axes is selected so that all axes As indicated above, the handcutting of the reach the new position simultaneously. This is three-dimensional workpiece is even more particularly useful in following contours genera- difficult and time consuming than the cutting of a 60 ted by a series of closely related key data points two-dimensional workpiece. A constant pressure along a complex x, y, z coordinate curve. must be exerted to precisely track the contours of As indicated by the dotted line 24, the keypoint the workpiece to completely cut through the mask data from the robotic tracking of the existing and light score the metal surface without causing template can be read out onto magnetic tape as any undercuts or blow-outs. 65 indicated at 23 or any other form of permanent

5 I 179 940 nagnetic storage media. When it is desired to 25, or suDstitutea tnereror, it tne template nstitute a production run, the magnetic tape geometry has been generated through the xeated for the part that is to be produced is read "teach" function. scribe control 26 >ack into the robotic memory for execution of the Instructions from CPU 25 to hree-dimensional template. > utilizes only the x and y axes for flat feed stock. In A third method of generating masks for the the Kongsberg Flatbed Drafting Table, one motor lutomated chemical milling process of the is used for the x axis and one motor is used for the )resent invention is illustrated at 20 and 21 y axis. These are the only two values that are of vherein new mask geometry is created on a CRT digitized and used to control the positioning controlled hrough the use of a program entitled "CADAM". o the scribing tool. The scribing tool is by scribe control rhe CADAM program is a commercially available, analog signal generated by the 26, icensed software program available through as will be hereinafter described in detail. ;ADAM, Inc. in Burbank, California, or from IBM. When the process is used on three-dimensional for In using the CADAM program, the part to be workpieces, the generation of the commands ireated is displayed on the CRT and a series of •5 the scribe control is substantially more complex. points are entered along the part to define the As indicated by the dotted line 24a, the magnetic :ey the lew mask geometry. The key points are then tape 23 created by the robotic device during illed in by the operator at the CRT to completely "teach" function may be reinserted into the CPU jnclose the perimeter of the -new template controlling the robotic device, and each of the in the geometry. If sequential milling baths are desired, w rotational motions will be generated same jach of the templates are generated by the sequence and order as they were "taught" to the 19. Dperator at the CRT by entering the desired key device during the key point data step joints to define the x, y values of each of the The robotic device contains three to six motors aoints along the perimeter. The new template for traversing the x, y, z axes whereas the flatbed the geometry is digitized as it is created by the CPU ?5 plotter uses two motors for traversing x, y 16, and, if desired, a printout may be generated as axes. New three-dimensional templates may be indicated at 18 to check the mask geometry created via a "CATIA" program as indicated at 21 against the feed stock example or an initial mock for new template geometry. CATIA was Dassault in France modification tip of the part that may have been created in the developed by as a model shop. ?o to the previously described CADAM program. IBM. A If the process involves the creation of a number CATIA is currently available from separate be of parts from a single piece of feed stock, a set of rotational commands must also genera- in separate nesting subroutine 22 is used to nest the ted as indicated at 26b for each of the motors various template perimeters in the most efficient the robotic device. This step computes the direc- manner for the particular size and configuration 35 tion and speed of each of the motors necessary to of the beginning feed stock. The "nesting" sub- traverse the x, y, z contour defined by the digitized routine indicated at 22 is a software program x, y, z values at 21. This may be done as a entitled "CAMSCO" and is available through separate routine between the CPU and the robotic CAMSCO, Inc., 1200 N. Bowser, Richardson, control, or it may be generated at the time the Texas 75081. 40 new template geometry is created by the CPU 1 6. The digitizing of the existing template as indi- The robotic control indicated at 27 is the pro- cated at 17, or the creation if the new template cess of controlling the relative rotational axes of geometry as indicated at 21, is stored in magnetic each of the motors in the robotic device. form in either temporary or permanent storage As is apparent from Figure 1, the scribe controls media as it is created. If it has been stored in a 45 indicated at 26 may be derived in the three- robotic temporary memory, it is then converted to mag- dimensional operating mode from the from netic tape or disc as indicated at 23 for future use control 27, or in the two-dimensional mode in the manufacturing method. Inasmuch as a the Kongsberg table 28. three large aircraft manufacturer may have thousands Scribe control 26 is capable of effecting of templates used for chemical milling parts for so separate operations on each of the pieces of feed the aircraft, it is desired to have a permanent stock 11 that are flow coated as indicated at 12. magnetic record as indicated at 23. This record These three steps are the mask cutting indicated the @may be used whenever it is desired to begin a at 14, the marking step 29 and resealing step production run for a particular part or series of indicated at 30. parts. 55 If a simple one-step milling process is utilized, As illustrated in Figure 1, a separate CPU 25 has the CPU 25 will drive the x, y motors of the been illustrated for use in the production line Kongsberg table as indicated at 28, while the environment. In applicants device, CPU 16 is a scribe control 26 regulates the pressure of the computer that is normally used in the design and cutting knife and the orientation of the cutting engineering departments while CPU 25 is a 60 blade during the mask cutting operation 14. Since separate computer that is used to operate the the most is somewhat resilient, it is difficult to see Kongsberg Flatbed Drafting Table. It would be the cut lines in the mask. Therefore, after the possible, however, to use the same computer for mask has been cut, it is conventional practice to both functions if desired. The ASEA robot has an mark the scribe line as indicated by 29 with a integral CPU which may be used on line with CPU 65 marker to assist the workmen who remove parts

o 1 I 179 940 z of the mask in finding the area to be removed. Ihus, it is apparent that even witn two-aimen- Inasmuch as several thousand types of work- sional flat stock, the tangentially controlled scrib- pieces may come through the production line for ing tool 14a is able to compensate for any waves the etching bath 31, each with its own particular or variations in surface thickness of the feed stock configuration, and each with a separate number 5 1 1a as it scribes the surface. of templates scribed thereon, the marking step, The feed stock 11a may be any metal that is while not absolutely essential, it is highly desir- suitable for etching or other chemical milling. In able to achieve error-free etching or chemical the preferred embodiment, it takes the place of milling. aluminum, or one of its alloys, or titanium, or one If multiple etching baths are desired for the •o of its alloys, commonly used in the aircraft and workpiece 11, the scribe control 26 then recoats aerospace industry. One such aluminum alloy is all but one of the template lines cut during the generally designated in the trade as 20-20-4 and mask cutting operation 14. Normally, the meets a federal specification entitled Q-A-250/4 or innermost template is then removed as indicated Q-A-250/5. One of the titanium alloys used in the at 32, and the workpiece is then immersed in the '5 present invention is designated in the trade as a 6- etching bath 31. If multiple masks and multiple 6-2 titanium alloy and meets a military specifica- milling steps are involved, the workpiece is tion entitled T-9046. It includes, in addition to recycled as indicated at 32a for the removal of the titanium, 6 parts of aluminum, 6 parts of vana- second mask and a return to the etching bath dium and 2 parts of tin. along 31a. After each of the areas have been >o These metals are milled in separate etching milled on the workpiece, it is then de-smutted in a baths although it is apparent from the prior art de-smutting bath 33 and sent to a router for part that a wide variety of etching solutions could be separation as indicated at 34. The part separation used. In the preferred practice of the present step 34 may be used when a plurality of parts are invention, the aluminum alloys are milled in a nested on a single piece of feed stock, or when a ?5 sodium hydroxide alkaline bath while the portion of the feedstock is used for the position- titanium alloys are milled in a hydrofluoric acid ing of the reference or alignment holes that guide bath. Other desired baths for aluminum may the workpiece through the various manufacturing include caustic soda or potassium hydroxide, and steps that it will encounter. another chemical bath that may be highly desir- As illustrated in diagrammatic form in Figure 2, jo able for titanium is nitric/hydrofluoric acid. the tangentially controlled scribing tool uses a While aluminum and its alloys, and titanium single knife 35 that is secured in a central barrel 36 and its alloys, are the principle metals used in the by means of a set screw 37. Barrel 36 is provided present invention, it is apparent that any metal or for both rotational and reciprocating movement material susceptible to milling by an oxidizing by means of an air bearing 37 which completely ?5 acid or strong alkali solution would be usable with surrounds torque piston 38. The piston 38 is the present invention. responsive to two orthogonal stator windings 39 As illustrated in Figure 3, the workpiece 11a and 40 which are in turn connected to sine 41 and illustrated in Figure 2 has been immersed in an cosine 42 analog voltages received from the etching bath to remove a portion of the metal by scribe control 26 illustrated in Figure 1. These 40 chemical milling. The distance "D" representing voltages turns the torque receiver piston 38, and the depth of the etchant cut varies widely depend- subsequently the knife's leading edge to ensure ing on the material, the etchant bath, the tempera- that knife 35 always present its normal cutting ture and the period of time in which the material edge to the material consistent with changes in is immersed in the etchant. The parameters the direction of the motion of the tool. A third 45 involved in the milling steps such as the concen- winding 43 is set by the operator through a tration of active agent, the temperature, the mill- potentiometer or other signal device 44 to control ing rate, etc. will vary from application to applica- the downward pressure exerted by piston 38 on tion. knife 35. The effect of this downward pressure will In the preferred embodiment, when aluminum be hereinafter more fully described with respect so and its alloys are milled in sodium hydroxide, to Figure 5. from .0008 to .0022 mils (0.02 to 0.056 (am) of As illustrated in Figure 2, the aluminum or material will be removed for each minute of titanium workpiece 1 1 has been greatly exagger- immersion in the etchant bath. When titanium ated in depth relative to the size of the tangential and its alloys are immersed in hydrofluoric acid, scribing tool to illustrate the relationship between 55 from .0006— .0012 mils (0.015—0.030 urn) will be the depth of the feed stock 11a, and the depth of removed for each minute in the hydrofluoric the flow coat mask 12a. In actual practice, the etchant bath. It should be noted that all of the aluminum or titanium work stock 11a ranges in workpiece 11a is protected by the masking thickness as illustrated by the arrows "A" from material applied at step 12, except that portion 1/8 of an inch (3.2 mm) to 1/2 an inch (12.7 mm) in 60 which is desired to be chemically milled. Thus, thickness. The thickness of the mask resist coat- the lower mask 12c protects the underside, or in ing 12a, indicated by the arrows "B" in Figure 2 is the case of an aircraft skin section, the outer side approximately 10 mils (254 urn). The reciprocal of the feed stock 11a. range of knife 35, indicated by the arrows "C" in As illustrated in Figure 4, a workpiece 11b has Figure 2 is approximately 1/8 of an inch (3.2 mm). 65 been subjected to a multiple etching bath.

7 13 0 179 940 14 Multiple cuts were made at 14b, 14c and 14d 53 and 54 for reciprocation along the y axis of the through the protective mask to define separate table. A single pinion in the scribe control 26a masks 12a, 12b and 12c. After the cuts 14a— 14d reciprocates the scribe control along a rack were made, cuts 14c and 14d were resealed with mounted in the gantry 50. The surface flatness of "TURCO" or the styrene/butadiene copolymer 5 the bed is plus or minus 0.75 millimeters, or well mask material as indicated at 30a and 30b. The within the 1/8 of an inch (3.2 mm) vertical recipro- initial portion 12a was removed by hand as cating dimension c indicated in Figure 2. The illustrated in Figure 4, and the first layer of metal cutting speed of the table can be as high as 42 was milled away as indicated by the dotted line meters per minute. surrounding 31a. Following this initial milling, the io The scribe control 26a illustrated in Figure 6 has sealant material 30a was removed, the cut mask the tangentially controlled scribing tool 14a and a material indicated at 12d was removed, and the pair of marking pens 55 and 56, one of which is workpiece was reinserted in the etchant bath. cut away from the purposes of illustration in During the second immersion, the metal indicated Figure 6. The scribe control 26a also contains a at 31 b was removed by action of the etchant bath. 15 resealing means 30a that is connected to a reser- After the desired amount of metal had been voir of maskant material such as TURCO, or any removed, the third section of cut mask material sealant that is compatible with the maskant 12e was removed, and portions of metal indicated material and capable of withstanding the acid or at 31c were removed during the third immersion caustic bath to which the mask material will be in the etchant bath. Thus, it is apparent that many 20 subjected during the multiple milling steps. The possible various surface configurations could be resealing step 30 is carried out by means 30a by milled by virtue of the multiple bath process means of a rolling ball 58, a brush, or other fluid illustrated in Figure 4. dispenser as may be desired, depending upon the The curve illustrated in Figure 5 illustrates the flow characteristics of material to be dispensed depth expressed in inches (in brackets in urn) of 25 therefrom. In some applications of the invention, the cut by the knife blade 35 through the mask 12a it may be desirable to combine the sealant with an and into the metal substrate 11a. The horizontal ink or other contrasting pigment to provide a axis labelled "force settings" are indicative of the single step that marks and reseals the cut scribe signals provided by means 44 which originate line. A plurality of air pressurizing means 59, 60 from the scribe control 26 illustrated in Figure 1. 30 and 61 pressurize the containers of sealant 57 and While normally this is preset by the operator at ink containers (not shown). The inks are then the time the cuts are made in the mask, the signal dispensed to marking pens 55 and 56 by means of could be supplied as part of the data processing tubes 62 and 63 for marking the cut lines after the signal stored on magnetic tape 23. As indicated tangentially controlled cutting tool 14a has cut by the slope of curve 45 and 46 the pressure 35 through the mask. generated by the torque piston 38 and winding 43 Electronic control for the scribing tool is main- is sufficient to readily cut through the mask, but tained through an overhead cable 64 illustrated in only lightly score the feed stock. As illustrated in Figure 7 to the scribe control 26a. Electronic Figure 5, the maximum depth of cut through the control of each of the cutting, marking and reseal- aluminum feed stock was .002 inches (51 urn) 40 ing stages is provided by means of connector 65 even at the highest "force setting" for the tangen- and control line 66. The air supply for the tangen- tially controlled scribing tool. This is well within tially controlled cutting tools air bearing is pro- the .004 inches (102 urn) limit set by current vided through conduit 67 while conduit 68 pro- military specifications. Inasmuch as the titanium vides a similar supply for the ball applicator feed stock is substantially harder than the 45 means 30a used in resealing the cut scribe lines. aluminum feed stock, the depth of cut into the While the Kongsberg Flatbed Drafting Table titanium is even less than the cut into the illustrated in Figure 7 is capable of a relatively aluminum. high rate of movement in the x and y axes, it The scribe control step illustrated at 26 in Figure normally does so only on straight cuts. The 1 is more fully illustrated in Figure 6 in the form of so software provided for the Kongsberg table at 28 in scribe control head 26a. The scribe control head Figure 1 provides the CPU 25 with a "look ahead" 26a is mounted on a Kongsberg Flatbed Drafting feature that enables the CPU to look ahead at the Table as illustrated in Figure 7. This particular next block of instructions and slow the scribing drafting table may be extended in 1-1/2 meter tool 26a when a change in direction is indicated. sections up to a maximum length of 10.5 meters. 55 For example, if the device is in the mask cutting The scribe control 26a is carried by a gantry 50 for mode, with the tangentially controlled scribing movements along the x axis and by carriage tool cutting through the mask cut material 12a, means 51 and 52 which reciprocate along guide any change in angle for the knife blade 35 of more rails 53 and 54 (not shown) mounted on either than 7° results in a vertical reciprocation of the side of the flatbed drafting table. A pair of high 60 piston 38 illustrated in Figure 2. The movement of performance dc servo motors provide for precise the scribing tool 26a is momentarily halted, the x, y positioning of the scribe control 26a by means blade 35 is raised and repositioned with respect to of rack and pinion drive mechanisms. The pinions its new angular orientation by means of signal for carriage 51 and 52 are connected via a single generators 41 and 42 provided by the scribe shaft and engage racks mounted in the guide rails 65 control 26. It should be noted that the instructions

8 5 ) 179 940 b :rom the CPU 25 to the Kongsberg table 28 to the surfaces when the robot is traversing a curve scribe control 26 are in analog form insofar as the through three-dimensinal space. Also, as was :angentially controlled scribing tool is concerned. indicated previously, the tangentially controlled The reciprocal cutting feature of this device scribing tool exerts a constant downward snables the operator of the device to insert a very 5 pressure on the scribing knife throughout a narrow knife point for blade 35 and to cut holes in reciprocal range of 1/8 of an inch (3.2 mm). This :he mask material of very small diameter. A round reciprocal movement of the knife provides that ;ircular hole as small as 1/4 of an inch in diameter the knife remains in a constant force engagement nay be smoothly cut in the mask material with with the aluminum or titanium workpiece the present invention. Cuts of this size radius have w throughout the various movements of the robot's b-een heretofore impossible with a handcutting arms. The robot has a positional tolerance for all Dperation. In addition to making cuts that were five axes of ±.004 mm which is compensated for previously impossible, the present invention by the air bearing reciprocal tolerance of 1/8 of an makes possible high speed scribing with high inch (3.2 mm) as indicated at "C" in Figure 2. precision and repeatability. As indicated pre- w Figure 9 illustrates the traditional x, y, z axes viously, one workpiece three-feet by four-feet normally used to span three-dimensional space. with multiple parts that took 6 to 8 hours to A fourth axis y is illustrated to note that any set of handscribe and mark by hand took 11 minutes to x, y, z axes couid be used, provided that no two scribe and mark with the present invention. axes are parallel to one another. If a particular set The present invention also makes possible the 20 of x, y, z axes is more efficient in calculating the application of the scribe control 26a to three- movement through three-dimensjonal space with dimensional workpieces as illustrated in Figures respect to a given surface part configuration, then B— 10. The scribe control 26a is mounted on a the x, y, z axes for that particular part may be robotic device 60 for cutting, marking and mask- altered to provide for more efficient calculation of ing the interior of a workpiece as illustrated in 25 the movements from one x, y, z point coordinate Figure 8. The master moid 70 has thereon a value to another. workpiece 1 1f that has been preshaped to a three- Figure 1 0 is an illustration of a part of an aircraft dimensional contour. that has been chemically milled after the mask The workpiece 11f has also been coated with was cut by a robotic device as illustrated in Figure coating 12a and is ready for cutting, marking and 30 8. As indicated, the aircraft skin 81 remains coated resealing as was previously described with with the resist material on its lower surface respect to Figure 2 — 4. throughout the entire milling operation. The ribs The robotic device 60 is equipped with a plu- 82, 83 and 84 and stringers 85, 86, 87 and 88 are rality of rotational axes, each of which assists the integrally formed with the skin 81 to provide a device in transporting the scribe control 26a from 35 unitary structure that is lightweight, strong and one point on the x, y, z axes to a second point on free from any mechanical joints, rivets, screws or the x, y, z axes. The pedestal 71 rotates about a other fastening devices. The natural undercutting pedestal turning moment 72 which is described action of the chemical milling process will provide as saw in the part separation process. grammed position simultaneously. This provides As hereinbefore described, the present inven- for smooth contouring of three-dimensional work 65 tion eliminates tedious handscribing of the mask

9 7 I 179 940 a m flat and three-dimensional parts intended for wherein steps {a) ana (e) are carnea out Dy from hemical milling. It may eliminate the construction sequentially removing 12a the resist coating if new templates for new parts that are to be each of the areas to be chemicall milled between nanufactured and will eliminate the use of exist- separate additional immersions in said etching ig templates for parts that have already been j solution; lesigned. It eliminates the handmarking of whereby each of the defined areas to be nultiple scribed areas and cuts and eliminates the chemically milled is immersed in said solution for land application of TURCO sealer on the cuts to be differing cumulative time periods. ised in sequential milling of the part. It provides a 5. An automated chemical milling process for :ontrolled depth of cut through the mask into the o metals as claimed in Claims 1 or 2 or 3, which the netal part that is very precise. The cutting can be further includes the step of marking perime- inducted at high speeds with high precision and ter(s) of the area(s) cut by said scribing tool with a ligh repeatability. The tangentially controlled visible marker, said marker marking said coating icribing tool makes it possible to cut curves on along the perimeter line(s) defined by the x, y >oth flat and three-dimensional surfaces and to 5 coordinate values, said marking occurring before iefine holes and curves that have not heretofore said resist coating is removed. )een previously possible with handscribed oper- 6. An automated chemical milling process for rtions. metais as claimed in Claim 4, wherein the recoat- ing step utilizes a visible sealant to simultaneously Claims io reseal and mark the cut scribe lines. 7. An automated chemical milling process for 1. An automated chemical milling process for metals as claimed in Claims 1 to 5, which further netals, said process comprising the steps of: includes the step of nesting 12a, 12d, 12e, 12b the (a) coating 12 the metal to be chemically milled perimeter lines of each of the areas to be with a resist coating; ?5 chemically milled when more than one part is to be (b) digitizing 17 the area(s) to be chemically chemically milled from a single metal plate. Tiilled to define at least x and y coordinate values 8. An automated chemical milling process for :or the perimeter of the area(s) to be chemicall metals as claimed in Claims 1 to 6, which further Tiilled; includes the step of applying a predetermined (c) automatically scribing 25, 26 the metal and 30 constant force on the scribing tool 35 to force said coating with a scribing tool 14, said scribing tool scribing tool into engagement with said metal part cutting through said coating along the perimeter 11a, said force being applied perpendicularly to a defined by the x and y coordinate values; plane defined by at least two point values for each (d) removing 32 the resist coating from the point traversed by said scribing tool. area(s) to be chemically milled; and 35 9. An automated chemical milling process for (e) immersing said partially coated metal into an metals as claimed in Claims 1 to 8, which further etching solution 31 for a predetermined period of includes the scribing and chemical milling of time to remove a predetermined amount of metal registration marks 90, 91 in a metal plate. from the uncoated area(s). 10. An automated chemical milling process for 2. An automated chemical milling process for 40 metals as claimed in Claim 9, wherein tooling metals as claimed in Claim 1, wherein step (b) is holes 90, 91 are subsequently formed from said carried out by defining a three-dimensional space registration marks. with three separate x, y and z axes; wherein no two 11. An automated chemical milling process for axes are parallel to one another and "by digitizing metals as claimed in Claims 1 to 6, which further 17 the area(s) to be chemically milled with x, y and 45 includes the step of raising the scribing tool z point coordinate values; and wherein step (c) is whenever a line or curve described by a future set carried out by scribing 26, 27 the coating and metal of point coordinate values varies from a line or along one or more three-dimensional perimeter(s) curve scribed from a previous set of point coordi- defined by said x, y and z point coordinate values. nate values by more than 7°. 3. An automated chemical milling process for so 12. An automated chemical milling process for three-dimensional metal parts as claimed in Claim metals as claimed in Claims 1 to 11, in which the 2, which further includes the steps of defining metal 1 1 is aluminum or its alloys, and the etching three or more rotational axes 26b for the scribing bath 31 is an alkali metal hydroxide. tool, said scribing tool selecting one or more of 13. An automated chemical milling process for said rotational axes as it traverses said three- 55 metals as claimed in Claims 1 to 11, in which the dimensional space defined by said x, y, z coordi- metal 11 is titanium or its alloys, and the etching nate values. bath 31 is a hydrohalic acid. 4. An automated chemical milling process as 14. An automated chemical milling process for claimed in Claim 1 or 2 or 3 wherein step (c) is metals as claimed in Claims 1 to 13, wherein said additionally carried out by: 60 resist coating is a butadiene/styrene copolymer. separately scribing 14b, 14c, 14d more than one area to be chemically milled for each metal part; Patentanspriiche and recoating the cut scribed lines 30a, 30b for all but 1. Automatisiertes chemisches Frasverfahren one of the areas to be chemically milled, and 65 fur Metalle, wobei das Verfahren die Schritte

10 ithalt: UGIIIIL OIIHJ, ^iiviim..., .. ~ ~ w . ~ • -I der auSeren Begrenzungslinie(n), a) Beschichtung (12) des chemisch zu frasenden Belag entlang die y-Koordinaten festgelegt ist etalles mit einem Resist- oder Abdeck-Beiag; die durch x-, der chemisch zu frasenden (sind), Vorzeichnet, wobei dieses vorzeichnen vor b) Digitalizieren (17) stattfindet. die x- und y-Koordina- der Entfernung des Abdeck-Belages ache(n), urn wenigstens chemisches Frasverfahren fur die aufiere Begrenzung der chemisch zu 6. Automatisiertes n 4, wobei man bei dem asenden Flache(n) festzulegen; fur Metalle nach Anspruch Anzeichnen (25, 26) des Wiederbeschichtungsschritt eine sichtbare Dich- c) automatisches die des mit einer ReilSnadel tungsmasse verwendet, um gleichzeitig etalles und Belages Linien wieder 4), wobei diese ReiSnadel den Belag entlang der durchtrennten vorgezeichneten markieren. llSeren die durch die x- und y- abzudichten und zu Begrenzung, chemisches Frasverfahren aordinaten festgelegt ist, durchtrennt; 7. Automatisiertes nach den Anspruchen 1 bis 5, das d) Entfernen (32) des Abdeck-Belages von der fur Metalle Schritt der Verschachtelung (12a, 12d, ien) chemisch zu frasenden Flache(n); und weiter den der aufceren Begrenzungslinien von e) Eintauchen dieses teilweise beschteten 12e, 12b) chemisch frasenden Flachen enthalt, letalles in eine Atzlosung (31) fur einen festge- jeder der zu als ein Teil einer einzelenen Zeitabschnitt, urn eine festgelegt Menge an sobald mehr von gten chemisch zu frasen ist. letall von der (den) unbeschichteten Flache(n) zu Metallplatte 8. Automatisiertes chemisches Frasverfahren Ttfernen. 1 bis 6, das Automatisiertes chemisches Frasverfahren > fur Metalle nach den Anspruchen 2. einer festgeleg- nach Anspruch 1, wonach Schritt (b) weiter den Schritt des Anlegens ir Metalle, die Reifcnadel (35) enthalt, wird durch Festlegung eines dreidi- ten konstanten Kraft an urchgefiihrt Metallteii (11a) angrei- lensiona'len mit drei getrennten x-, y- um die ReiBnadel an dem Raumes senkrecht wobei keine zwei Achsen parallel fen zu lassen, wobei diese Kraft zur nd z-Achsen, durch zwei Punkte festge- jeinander angeordnet sind, und ; Flache, die wenigstens mit der Reifinadel durchfahre- durch (17) der chemisch zu fra- legt ist, fur jeden Digitalisieren wird. Flache(n) mit und z-Pukoordinaten; nen Punkt angewendet snden x-, y- chemisches Frasverfahren nd 9. Automatisiertes den 1 bis 8, das Schritt (c) durch Anzeichnen (26, 27) des fur Metalle nach Anspruchen wobei Anzeichnens und chemi- und des metalles entlang einer oder 5 weiter den Schritt des elages Bezugs-Markierungen (90, 91) lehrerer dreidimensionaier auKerer Begrenzun- schen Frasens von durch diese und z-Punktkoordinaten in einer Metallplatte enthalt. en, die x-, y- chemisches Frasverfahren sind, durchgefuhrt wird. 10. Automatisiertes sstgelegt nach 9, bei dem die Bearbei- 3. Automatisiertes chemisches Frasverfahren fur Metalle Anspruch 91) nachtraglich durch die iir dreidimensionale Metallteile nach Anspruch 2, 5 tungslocher (90, (90, 91) ausgebildet las weiter die Schritte zur Festlegung von drei Bezugs-Markierungen mehreren Rotationsachsen (26b) fur die werden. ider chemisches Frasverfahren leiBnadel enthalt, wobei diese ReiBnadel eine 11. Automatisiertes den 1 bis 6, das mehrere dieser Rotationsachsen auswahlt, fur Metalle nach Anspruchen tder Anhebens der ReilSnadel die ReiBnadelden durch die x-, y- und z- @o weiter den Schritt des ndem eine Linie oder Kurve, die Coordinaten festgelegten dreidimensionalen enthalt, jedesmal wenn durch eine kunftige Menge an Punktkoordinaten teum durchfahrt. Kurve chemisches Frasverfahren beschrieben ist, von einer Linie oder um 4. Automatisiertes eine fruhere 2 oder bei dem Schritt (c) mehr als 7° abweicht, die durch lach Anspruch 1 oder 3, ist. wird is Menge an Punktkoordinaten vorgezeichnet xisatzlich durchgefuhrt Frasverfahren Anzeichnen (14, 14c, 14d) von 12. Automatisiertes chemisches durch getrenntes 1 bis 11, bei als einer chemisch zu frasenden Flache fur fur Metalle nach den Anspruchen nehr Aluminium oder seinen edes Metallteii und dem das Metail (11) aus und das Atzband (31) ein durch Widerbeschichtung der durchtrennten Legierungen besteht Linien (30a, 30b) aller Flachen w Alkalimetallhydroxid ist. angezeichneten Frasverfahren die chemisch gefrast wird, und 13. Automasiertes chemisches aulSer der einen, 1 bis 11, bei dem wobei die Schritte (d) und (e) durchgefuhrt fur Metalle nach den Anspriiche Titan oder seinen Legierungen werden durch sequentielles Entfernen (12a) des das Metall (11) aus Atzband (31) eine Hydrogenwas- Abdeck-Belages von jeder der chemisch zu fra- besteht und das zwischen zusatzli- 55 serstoffsaure ist. senden Flachen getrenntem Frasverfahren in die Atzlosung; 14. Automatisiertes chemisches :hen Eintauchen 1 bis 13, bei wodurch der festgelegten chemisch zu fur Metalle nach den Anspruchen jede ein Butadien/Styrol-Copo- frasenden Flachen in diese Losung fur verschie- dem der Abdeck-Belag dene anwachsende Zeitabschnitte eingetaucht lymer ist. wird. 60 5. Automatisiertes chemisches Frasverfahren Revendications fur Metalle nach den Anspruchen 1 oder 2 oder 3, chimique automatise pour das weiter den Schritt der Markierung der aufie- 1 . Procede d'usinage ledit procede comprenant les phases ren Begrenzung der Flache(n), die durch die ReiS- metaux, nadel mit einer sichtbaren Markierung durch- 65 consistant a: 21 0 179 940 22 (a) enduire en (12) le metal qu'il s'agit d'usiner consistant a marquer le ou les perimetre(s) de la chimiquement d'un enduit de reserve; zone ou des zones incisee(s) par ledit outil de (b) numeriser en (17) la zone ou les zones a tracage au moyen d'un marquer visible, ledit usiner chimiquement, pour definir au moins des marquer marquant ledit enduit le long de la ligne valeurs de coordonnees x et y pour le perimetre 5 ou des lignes de perimetre definie(s) par les de la zone ou des zones a usiner chimiquement; valeurs de coordonnees x, y, ledit marquage se (c) tracer automatiquement en (25, 26) le metal produisent avant que I'enduit de reserve n'ait ete et I'enduit a I'aide d'un outii a tracer (14), ledit enleve. outil a tracer entaillant ledit enduite le long du 6. Procede d'usinage chimique automatise pour perimetre defini par les valeurs de coordonnees x 10 metaux selon la revendication 4, caracterise en ce ety; que la phase de reenduction utilise un mastic (d) enlever en (32) I'enduit de reserve de la zone visible pour refermer et marquer simultanement ou des zones a usiner chimiquement; et les lignes de tracage incisees. (e) immerger ledit metal partiellement enduit 7. Procede d'usinage chimique automatise pour dans une solution d'attaque (31) pendant un 75 metaux selon I'une des revendications 1 a 5, temps predetermine pour eliminer une quantite caracterise en ce qu'il comprend en outre la phase predeterminee de metal de la zone ou des zones consistant a mettre en serie en (12a, 12c/, 12e, non enduites. 126) les lignes de perimetre de chacune des zones 2. Procede d'usinage chimique automatise pour a usiner chimiquement iorsque plus d'une seule metaux selon la revendication 1, caracterise en ce 20 piece doit etre usinee chimiquement a partir que la phase (b) s'effectue d'une seule et meme plaque metallique. en definissant un espace tridimensionnel selon 8. Procede d'usinage chimique automatise pour trois axes separes x, y et z, dans lequel il n'y a pas metaux selon I'une des revendications 1 a 6, deux axes parallele entre eux et caracterise en ce qu'il comprend en outre la phase en numerisant en (17) le zone ou les zones a 25 consistant a appliquer une force constante prede- usiner chimiquement avec des valeurs de coor- terminee a I'outil de tracage (35) pour mettre a donnees de point x, y et z; et en ce que la phase force ledit outil de tragage en prise avec ladite (c) s'effectue partie metallique (11a), ladite force etant appli- en tracant en (26, 27) I'enduit et le metal le long quee perpendiculairement a un plan defini par au d'un ou de plusieurs perimetres tridimension- 30 moins deux valeurs ponctuelles pour chaque nel(s) defini(s) par lesdites valeurs de coordon- point parcouru par ledit outil de tragage. nees de point x, y et z. 9. Procede d'usinage chimique automatise pour 3. Procede d'usinage chimique automatise pour metaux selon I'une des revendications 1 a 8, des pieces metalliques tridimensionnelles selon caracterise en ce qu'il comprend en outre le- la revendication 2, caracterise en ce qu'il com- 35 tragage et I'usinage chimique de marques de prend en outre les phases consistant a definir reperage ((90, 91) dans une plaque metallique. trois ou plus de trois axes de rotation (266) pour 10. Procede d'usinage chimique automatise I'outil de tragage, ledit outil de tragage selection- pour metaux selon la revendication 9, caracterise nant un ou plusieurs desdits axes de rotation en en ce qu'on forme ensuite a partir desdites mar- parcourant ledit espace tridimensionnel defini par 40 ques de reperage des trous d'outillage (90, 91). lesdites valeurs de coordonnees x, y et z. 11. Procede d'usinage chimique automatise 4. Procede d'usinage chimique automatise pour metaux selon I'une des revendications 1 a 6, selon la revendication 1 , 2 ou 3, caracterise en ce caracterise en ce qu'il comprend en outre la phase que la phase (c) s'effectue en supplement consistant a relever I'outil de tragage chaque fois en tragant separement en (146, 14c, 14c/) plus 45 qu'une ligne ou courbe decrite par un jeu futur de d'une seule zone a usiner chimiquement pour valeurs de coordonnees de points s'ecarte de plus chaque piece metallique, et de 7° d'une ligne courbe tracee a partir d'une jeu en reenduisant les lignes tracees par incision precedent de valeurs de coordonnees de points. (30a, 306) pour toutes les zones a usiner chimi- 12. Procede d'usinage chimique automatise quement sauf une, et en ce que les phases (d) et 50 pour metaux selon I'une des revendications 1 a (e) s'effectuent 11, caracterise en ce que le metal (11) est I'alumi- en elevant sequentiellement en (12a) I'enduit de nium ou ses alliages et le bain d'attaque (31) est reserve de chacune des zones a usiner chimique- un hydroxide de metal alcalin. ment entre deux immersions additionnelles 13. Procede d'usinage chimique automatise separes dans ladite solution d'attaque; 55 pour metaux selon I'une des revendications 1 a de sorte que chacune des zones definies a 1 1 , caracterise en ce que le metal (1 1 ) est le titane uniser chimiquement est immergee dans ladite ou ses alliages et le bain d'attaque (31) est un solution pendant des periodes cumulatives diffe- acide hydrohallogene. rentes. 14. Procede d'usinage chimique automatise 5. Procede d'usinage chimique automatise pour 60 pour metaux selon I'une des revendications 1 a metaux selon la revendication 1 , 2 ou 3, caracte- 13, caracterise en ce que ledit enduit de reserve rise en u qu'il comprend en outre la phase est un copolymere butadiene/styrene.

65

12 D 179 940

KEY KEY POINT DATA DPTICAL SCAN | 15 POINT DATA ROBOTIC TRACKING KEY ENTRY ' 17 8 20 ) — i 19 DIGITIZE YEW TEMPLATE CHECK EXISTING PRINT OUT 3E0METRY cp-24 TEMPLATE

NESTING 21 SUB- 22 ROUTINE II \5

26 b 23 AL OR Tl X Y Z FEED STOCK CONTOURING L f-24a GENERATE ROTATIONAL CP.U ~L-25 AXES FLOWKOTE RESIST MASK KONGSBERG 28 TABLE

14 MASK CUTTING 29 ROBOTIC | SCRIBE MARKING 27- CONTROL CONTROL

REPEALING 30

26- 3la- REMOVE MASK(S) ETCHING 32 BATH a

32

33- DE-SMUTTING BATH

PART -34 SEPERATION

FIG I

1 0 179 940 0 179 940

.000

(127^™) .005 MASK THICKNESS

(254/tm) .010 ( .001

( 76yum) .003 FEED STOCK THICKNESS FORCE SETTINGS

FIG.5 0 179 940

•64 26a 54

FIG.7

72-

FIG.8

4 5