Патент USA US3057336код для вставки
Oct. 9, 1962 3,057,325 T. E. NANCE CARBON DEPOSITION APPARATUS Filed April l, 1959 El 37. /// 'lxl/ // // // // // 2/ 27 ” /70 V INVENTOR ZkølâfÃ/?žw? BY (e 4.. W ATTORNEY (ice 3,057,325 Patented Oct. 9, 1962 2 chambers exposing the articles to the carbonaceous gas 3,057,325 CARBON DEPOSITION APPARAT US Taylor E. Nance, Winston-Salam, N.C., assignor to West em Electric Company, Incorporated, New York, N.Y., a corporation of New York Filed Apr. 1, 1959, Ser. No. 803,529 10 Claims. (Cl. 118--47) in the deposition chamber only. More speci?cally carbon deposition apparatus for car bon coating articles such as ceramic cores includes a pre heating chamber, a coating chamber, and a cooling cham ber. Electrical heating elements maintain the deposition chamber at the correct temperature so as to pyrolize or crack 'a carbonaceous gas forced through the chamber causing the carbon in the gas to be deposited on articles This invention relates to a deposition apparatus and more particularly to an apparatus for depositing a uni 10 which are rolled through the apparatus between spaced guide rolls. form coating of carbon on ceramic cores while rolling The articles are conveyed through the preheating cham the cores through a deposition chamber. ber in an entrance tube which surrounds the guide rolls and opens into the deposition chamber. An outer tube carbon on a refract-ory body such as a ceramic core by 15 spaced from and concentric With the entrance tube forms a closed passage around the entrance tube. Radially heating the core to a predetermined temperature and It is the purpose of the invention to form such articles as deposited carbon resistors by depositing a coating of then exposing the preheated core while in a rolling condi spaced ports in the end of the entrance tube adjacent the deposition chamber open into the closed passage sur tion to an atmotsphere of carbonaceous gas in a coating rounding the entrance tube permittíng a neutral or inert chamber so that the gas is cracked and the carbon con tained in the gas is deposited on the surface of the ceramic 20 gas to ?ow from a suitable source through the entrance core. The carbon coating produces highly desirable re sistance characteristics. By accurately controllíng the tube and into the surrounding passage. An exhaust pump maintains su?icient pressure in the passage to exhaust the neutral gas from the entrance tube whereby the coat ing gas is excluded from the entrance tube. The spaced deposition process, and :thus the amount of carbon de~ posited, a deposited carbon resistor within extremely close resistance tolerances may be formed. By maintaining a 25 guide rollers roll the coated articles from the deposition 'chamber through a cooling chamber within an exit tube. ?ow of ceramic cores through the carbon deposition An atmosphere of neutral gas excludes the coating gas chamber, great quantities of precision resistors or other from the exit tube while an exhaust pump removes the articles can be continuously produced. coating gas and the neutral gas from the deposition The density and thickness of the carbon coating formed on the ceramic cores is dependent on the length of time 30 chamber. A clear Understanding of the invention will be had the core is exposed to the coating gas, the concentration from the following detailed description of a speci?c em of hydrocarbon in the coating gas, and the temperature bodiment thereof, When read in conjunction with the to which the core is heated. These factors are critical and care is necessary to secure a uniform coating of hard carbon on the ceramic core without forming soot or soft appended drawings, in which: carbon deposits. apparatus; FIG. 1 is a cross-sectional View of a carbon deposition FIG. 2 is a partial plan view of a carbon deposition ap paratus; and FIG. 3 is a cross-sectional view taken along line 3-3 stream of ceramic cores while at the same time consistent ~ly 'obtaining predetermined results at a satisfactory pro 40 of FIG. 1. Referring to the drawings a furnace tube 11, composed duction rate. These attempts have failed because of the of a refractory material and having headers 12 and 13 of di?iculty in conveying a continuous stream of ceramic fused silica, extends through an electric furnace 14. The cores through a carbon deposition chamber while at the _furnace 14 is heated by electrical elements 15 spaced same time precisely controlling the length of time that the ceramic cores are exposed to the coating gas. This 45 around and along the furnace tube 11. The elements 15 Numerous attempts have been made to devise a carbon deposition apparatus capable of coating a continuous is caused by reason of the fact that no e?ective manner are connected in parallel and are energized from a suit of scaling the entrance and exit passages through which the articles must pass into and 'out of the deposition cham able voltage source 16. A central portion 17 of elements 15 extend through a heating chamber 18, which is formed of ?re brick or other heat insulating material. The heat ing chamber 18 surrounds the furnace tube 11 and de?nes ber has been devised so as to prevent the articles from being exposed to the coating gas prior to their being re ceived in the deposition chamber or during their departure therefrom. Another inherent dil?culty in present day techniques of coating articles as they pass through a deposition cham ber is that of rotatively supporting an article While at the a central hot zone within the furnace 14. A cylindrical furnace líner 19 of a highly heat conductive material such ras silicon carbide is secured within the furnace tube 11 and de?nes a deposition chamber 21. An entrance tube 22 secured .to the inner face of the header 12 extends through and de?nes a preheating cham same time exposing the entire surface area of the article ber 23 within a portion of the furnace tube 11. The en to the coating gas. trance tube 22 and the preheating chamber de?ned there An object of this invention is to provide an apparatus by open into the deposition chamber 21. An outer tube for depositing a uniform coating of carbon on articles. Another object of this invention is to provide an ap 60 24 mounted concentric with the entrance tube 22 and spaced from the furnace tube 11 is rigidly secured to an paratus for depositing a uniform coating of hard carbon inner side wall face of the header 12. An end cap 25 on ceramic cores as they are continuously rolled through secured to the end of the outer tube 24 and the entrance the coating apparatus. tube 22 adjacent the deposition chamber 21 forms a To accomplish these and other objects carbon deposi closed passage 26 between the entrance tube 22 and the tion apparatus embodying certain features of this inven outer tube. Radially spaced ports 27 formed in the end tion may include a preheating chamber, a deposition of the entrance tube 22 open into the closed passage 26. chamber, and a cooling chamber. A conveyor rolls An exit tube 28 secured to .the inner face of the header ceramic cores through the deposition chamber at a uni 13 extends through and de?nes a cooling chamber 29 form rate of speed where a carbonaceous gas is cracked or pyrolized and a uniform coating of carbon is deposited 70 within a portion of furnace tube 11. The exit tube 28“ and the cooling chamber 29 de?ned thereby opens into the on the ceramic cores. A gaseous atmosphere excludes deposition chamber 21. `the carbonaceous gas from the preheating and cooling 3,o57,325 A suitable source of carbonaceous coating gas 31 such as methane and intermixed with a suitable carrier gas such as nitrogen is connected through a tube 32 into a passage 33 surrounding the outer tube 24 which opens into the deposition chamber 21. An exhaust pump 34 is connected with a passage 35 surrounding the exit tube 28 and which opens into the deposition chamber 21. The exhaust pump 4 spiral grooves 43, the ceramic cores 37 Will be simultane ously rotated and conveyed through the furnace 14 where they are uniformly coated with carbon. The speed of rotation and horizontal movement of the ceramic cores may be varied by adjusting the speed of the motor 49 and varying the pitch of the spiral grooves 43. The ceramic cores 37 are supported by and rotate upon the edges 44 of the base pans 41 and 42. 34 draws the coating gas through the passage 33, the The ceramic cores 37 pass through the furnace 14 deposition chamber 21, and out through the passage 35 into the atmosphere or a suitable gas collector. The coat 10 between the guide rolls 38 and 39' into a receiving cham ber 55 Secured to the header 13. An end portion 56 of ing gas is diffused throughout the deposition chamber 21. each of the guide rolls 38' and 39 is reduced in diameter to The type of coating gas which may be used is not re the depth of the spiral grooves 43 and is supported in a stricted to methane or other gases in the methane series. suitably mounted bearing '57. A hopper 58, supported As is well known, many other types of gas rich in hydro carbon may be employed. By the proper choice of coat 15 directly below the reduced end portions 56 and extending through the receiving chamber `55 receives the carbon ing gas, and additives mixed therewith if desired, and of coated cores 37 as they roll out of the spiral grooves 43 the temperature within the deposition chamber, the carbon in the gas will be deposited as a hard ?lm on articles ex posed to the coating gas within the deposition chamber 21. By controlling the duration and manner of exposure of the article to the coating gas a uniform ?lm of hard carbon will be deposited on the article. This ?lm when deposited on ceramic cores or other refractory bodies gives the core a very desirable resistance characteristic. In the manufacture of deposited carbon resistors it is 25 mandatory that the physical characteristics of the carbon formed in the guide rolls 38 and 39. The cores 37' are supported within the hopper 58 on one or the other of a pair of alternately reciprocable slides 59 which are actuated by pneumatic or other means (not shown). As the slides 59` are reciprocated the cores 37 pass from the hopper 58 into a discharge tube 61 which transports the cores to a next desired position. A neutral gas such a nitrogen, supplied under pressure from a pump 62. in a tube 63, passes into the feeding chamber 541 and through the aperture 40 into the entrance tube 22. The nitrogen gas provides a protective atmos coating formed on ceramic cores be precisely controlled in order to produce the desired resistance value within phere within the feeding chamber '51, preventing the close tolerances. A conveyor assembly 36 for transporting a series of 30 cores 37 from being contaminated before entering the furnace 14. An exhaust pump 64', connected to the ceramic cores 37 or other refract'ory bodies through the passage 26 through a tube 65, draws the neutral gas furnace 14 comprises a pair of spaced parallel guide rolls through the feeding chamber 51, the entrance tube 22, the 38 and 39 rota?tively supported at both ends and within radial-ly spaced ports 27, and through the passage 26 into base pans 41 and 42. The guide rolls 38 and 39* and the atmosphere. By maintaíning a negative pressure in their respective base pans 41 and 42 pass through aper the passage 26 by means of the pump 64 the neutral gas tures 40 in the headers 12 and 13, the entrance tube 22, the is withdrawn with su?icient velocity so as to prevent the deposition chamber 21, and the exit tube 28, respectively. neutral gas from entering the deposition chamber 21 or As shown in FIG. 2, a spiral groove 43 of rectangular the coating gas from contacting the ceramic cores 37 until cross section is formed in each of the guide rolls 38 and 39 and extends along their length. The grooves 43 are 40 they enter the deposition chamber 21. As the cerarnic cores 37 are transported through the entrance tube 22 identical in pitch, one groove forming a left-hand thread they are preheated to the desired temperature by the in guide roll 38 and the other forming a right-hand thread elements 15 surrounding the furnace tube 11. in the guide roll 39. A neutral gas such as nitrogen supplied under pressure The ceramic cores 37 are supported between and perpendicular to the spaced guide rolls 38 and 39` on an 45 from a pump 66 in a tube 67 passes into the receiving chamber 55 and through the aperture 40 into the exit upturned edge 44 formed on each of the base pans 41 and tube 28. The nitrogen gas ?ows through and is swept 42 while the ends of the ceramic cores 37 are received in out of the end of the exit tube 23 adjacent the deposition the spiral grooves 43. 'Ihe core 37 is preferably sup chamber 21 where it turns sharply and is exhausted by ponted such that its horizontal axis will lie in a plane ex tending between the horizontal aXes of the guide rolls 50 the pump 34 along with the coating gas and other prod ucts of the cracking process. The nitrogen gas excludes 38 and 39. the coating gas from the exit tube 28 and provides a pro Intermeshing gears 45 are Secured t'o a reduced end tective atmosphere in which the coated ceramic cores 37 portion 46 -on each of the guide rolls 38 and 39. A are cooled before they are removed from the furnace 14. drive gear 47, ?xed to a shaft 48 which is driven by a motor 49, meshes with one of the gears 45 to rotate the 55 operation gears 45 and the guide rolls 38 and 39 in opposite Ceramic cores 37 are fed in seriation from the supply directions. The guide rolls 38 and 39` may be driven by hopper 52 within the protective atmosphere of the feed separate motors if desired. The shaft 48 passes through ing chamber 51 to the guide rolls 38 and 39 where they a seal in the wall of a feeding chamber `51 formed around the end of the guide rolls 38 and 39 and Secured to 60 are received in the spiral grooves 43. As the guide rolls 38 and 39 are counter-rotated, the cores 37 -will be rotated the header 12. along the edges 44 of the base pans 41 and 42 into the A hopper 52 mounted above the guide rolls 38 and furnace 14. As the cores pass through the inert gaseous 39 and extending through the feeding chamber 51 sup atmosphere maintained within the entrance tube 22, they ports a vertical column of horizontally disposed ceramic cores 37 directly over the spaced guide rolls 38 and 39. 65 are preheated to the desired temperature by the heating elements 15. The preheated cores 37 continue to rotate The ceramic cores 37 are fed into the hopper 52 through along the edges 44 of the base pans 41 and 42 into the a supply tube 53. The cores 37 are supported within the deposition chamber 21 where they are exposed to a hopper 52 on slides 54 which are alternately reciprocated carbonaceous coating gas of methane supplied from the by pneumatic or other suitable means (not shown) to feed the ceramic cores 37 one at a time to the guide rolls 38 70 tank 31. The inert gas supplied by the pump 62 is drawn through the feeding chamber 51, the entrance tube and 39. As the cores 37 fall from the hopper 52, they 22, and the radial ports 27 into the passage 26 by the are supported on the edge 44 of the base pans 41 and 42, pump 64 with sui?cient velocity and pressure to seal the and the ends of the cores are received within the spiral preheating chamber 23 -from the deposition chamber 21 grooves 43. Due to the counter-rotation of the guide rolls 38 and 39 and the opposite threads formed by the 75 and exclude the coating gas from the entrance tube 22. &0573325 5 6 This action shields the ceramic cores 37 from the coat ber, spaced rotatable members for receiving the ends of ing gas until they enter the deposition chamber 21. the ceramic cores and for rolling the ceramic cores in a direction normal to their longitudinal axes through the As the ceramic cores 37 pass into the deposition cham ber 21 they are heated to a desired ?nal temperature. When the coating gas Contacts the heated cores 37, it is cracked and the carbon in the gas is deposited on the deposition chamber, an entrance tube through which articles to be coated are conveyed into the deposition chamber, means for heating the deposition chamber to crack the coating gas in the deposition chamber, an exit grooves 43 and the edges 44 of the base pans 41 and tube in which the articles are conveyed from the deposi 42, the ceramic cores 37 are supported between the guide tion chamber, a tube mounted concentrically with and rolls 38 and 39, and are continuously rotated within the 10 surrounding the entrance tube, a cap on the end of the deposition chamber 21. The surface area of each of the concentric tubes adjacent the 'deposition chamber form ce?'amic cores is evenly exposed to the coating gas as ing a closed passage between the entrance tube and the suring uniform coating. The speed of rotation of the concentric tube mounted therewith, notches formed in ceramic cores 37 may be precisely regulated by adjusting the end of the entrance tube and opening into said pas the speed of the motor 49 or changing the pitch of the 15 sage, and means for maintaining an inert gaseous atmos spiral grooves 43. The rate of travel of the cores phere in the entrance and exit tubes whereby the arti through the furnace is controlled by adjusting the speed cles to be coated are exposed to the coating gas only of motor 49. The conveyor assembly 36 can be readily in the deposition chamber as they are conveyed through adjusted to transport diñerent lengths of articles by vary the furnace. ceramic cores 37 as a hard ?lm. Because of the spiral ing the spacing of the guide rolls 38 and 39 and adjusting 20 4. Apparatus for conveying cylindrical articles com the drive mechanism therefor. prising a pair of spaced parallel guide rolls having oppo As the coated cores 37 leave the deposition chamber 21 site threads formed along their length, means for sup they enter a protective atmosphere of nitrogen or other porting the articles between the guide rolls and within inert gas within the exit tube 28. The nitrogen gas is the opposite threads formed therein, and means for counter-rotating the guide rolls whereby the articles are supplied under pressure from a suitable source by the rotated within the opposite threads and along the length pump 66 and ?ows in a direction opposite to that of of the guide rolls. the ceramic cores 37. As the nitrogen gas passes out of 5. Apparatus for rolling cylindrical bodíes comprísíng the exit tube 28 it is turned sharply, and is withdrawn a pair of spaced guide rolls having opposite threads along with› the coating gas and other products of the cracking process through the passage 35 by the pump 34. 30 formed along their lengths, means for placing the cylin drical bodíes between the guide rolls, means for support This action excludes the coating gas and other products ing the cylindrical bodíes between the guide rolls and of the cracking process from the exit tube 28 and pro within the opposite threads formed therein, and means vides a protectíve atmosphere for the coated cores 37. for rotating the guide rolls in opposite directions whereby The coated cores 37 are cooled as they pass through the the cylindrical bodíes are rotated within the opposite exit tube 28 before entering the receiving chamber 55. threads and rolled along the length of the guide rolls. The uniformly coated cores 37 remain within the spiral 6. A carbon deposition furnace for coating cerarnic grooves 43 until they reach the reduced end portion 56 cores which comprises a preheating chamber, a deposi of the guide rolls 38 and 39 where they roll out of the tion chamber, and a cooling chamber, spaced rotatable grooves 43 into the hopper 58 where they are fed into members for conveying ceramíc cores to be coated the discharge tube 61 by the alternately reciprocating through the preheating, deposition, and cooling chambers, slides 59. means for conducting a carbonaceous gas through said It is to be understood that the above described appara deposition chamber, means for heating the deposition tus is simply illustrative of the application of the broad chamber to crack the carbonaceous gas, an entrance tube principles of the invention. Numerous other arrange through which the ceramic cores to be coated are con ments may be ?devised by those skilled in the art which veyed through the preheating chamber and into the will embody the principles of the invention and fall deposition chamber, an outer tube spaced from and con within the scope thereof. centric with the entrance tube and forming a closed pas What is claimed is: sage about said entrance tube, radial ports formed in the 1. Deposition apparatus for coating ceramic cores which comprises a preheating chamber, a deposition 50 end of the entrance tube adjacent the deposition chamber and opening into said closed passage, a source of neutral chamber, a cooling chamber, conveyor means for support gas connected to the entrance tube, a pump for withdraw ing only the ends of the ceramic cores and for rolling ing the neutral gas from the entrance tube through the the ceramic cores through said preheating, deposition, and radial ports and out the closed passage whereby the coat cooling chambers, means for conducting a carbonaceous ing gas is excluded from said entrance tube, an exit tube coating gas through said deposition chamber, means for in which the cores are conveyed from the deposition heating the deposition chamber to crack the gas and de chamber and through the cooling chamber, a source of posit a coating on the ceramic cores, and means «for ex neutral gas connected to the exit tube, and a pump for cluding the coating gas from the preheating and cooling withdrawing the neutral gas from the exit tube in a direc chambers. 2. A carbon deposition furnace for coating ceramíc 60 tion which is opposite to the direction of travel of the ceramic cores and for withdrawing the neutral gas and cores comprising a deposition chamber, means for main the coating gas from the furnace whereby the coating gas taining a continuous ?ow of a carbonaceous coating gas is excluded from the exit tube. throughout said chamber, conveyor means for rolling the 7. In a conveying apparatus, a pair of spaced supports, ceramic cores through the deposition chamber, an en trance tube through which articles to be coated are con 65 a pair of threaded members mounted for rotation above the outer edges of the respective supports, means for feed veyed into the deposition chamber, an exit tube in which ing articles between said members so that the ends project the articles are conveyed from the deposition chamber, into the threaded members, and means for rotating said and means for maintaining an inert gaseous atmosphere members to advance the articles along the supports. in the entrance and exit tubes whereby the articles to be coated are exposed to the coating gas only in the deposi 70 8. In an article advancing apparatus, an elongated sup tion chamber. port, a pair of members having threaded sections, means 3. A carbon deposition furnace for coating ceramic for mounting said members for rotation above opposite edges of one surface of said support, means for feeding ing a carbonaceous coating gas through said chamber, articles onto said support so that the ends project into means for exhausting the coating gas from said cham 75 the threaded sections, and means for rotating said threaded cores comprising a deposition chamber, means for pass 3,o57,325 7 members to advance and roll said articles along said sup port. 9. In a coating apparatus, an entry chamber, a coating chamber at the terminus of and opening into said entry chamber, van exit chamber at the terminus of and opening into said coating chamber, means for supplying neutral gas to said entry chamber, means for exhausting said neu tral gas from said terminus of said entry chamber, means for supplying a coating gas to said coating chamber, means for supplying neutral gas to said exit chamber, 10 means for simultaneously exhausting said coating gas and said neutral gas at the entrance of said exit chamber, and means for rolling cylinclrieal articles through said entry, coating, and exit chambers. 10. Apparatus for transporting cylindrical bodies which 15 comprises a pair of spaced Parallel guide rolls having identical but opposite threads formed along their lengths, a pair of spaced parallel base pans, each having an up turned edge secured beneath the guide rolls and extending along its length for supporting the cylindrical bodies be 20 8 tween the guide rolls and within the opposite threads formed therein, and means for counter-rotating the guide rolls Whereby the cylindrical bodies supported between the guide rolls -are rotated within the opposite threads in the guide rolls and rolled along the upturned edges of the base pans. References !cited in the ?le of this patent UNITED STATES PATENTS l,564,926 2,328,422 Armstrong et al _________ __ Dec. S, 1925 Christensen ________ __,__ Aug. 31, 1943 2,778,743 2,810,365 Bowman _____________ __ Jan. 22, 1957 Keser ________________ __ Oct. 22, 1957 612,742 800,841 Great Britain _________ __ Nov. 17, 1948 Germany _____________ __ Dec. 11, 1950 146,834 Australia _____________ _._ June 13, 1952 882,074 Germany ______________ __ July 6, 1953 FOREIGN PATENTS L.ac .