May 18, 1926., 1,585,542 K. M. HENRY. PROCESS OF ANNEALING GLASS Filed Nov, 25, H H PT- H H & HE H -- --H () H 1H S.

Transcription

1 - ' May 18, 1926., K. M. HENRY PROCESS OF ANNEALING GLASS Filed Nov, 25, 1924 Q H t HHHHH - H H PT- H H & H t HE H -- tit N HE H -- --H () H 1H S PHEEEEEE HH HHS H H HHHHHH --- H EH HH & FHHHHHH EE HHHHH HE H. HSH EHEEZ-RHHH HHHHHHHHHHHH HHhHHHHHHHHHHHHH -- H. -- E. HE - H S S S S S S S i AM7/M/7/7/// Give/7 MV/ AL/A A/2772/7 a. 77C/e/7Zoy - -- TTTTTT H--- T. Q 278c % E.

2 Patented May 18, UNITED STATES PATENT OFFICE. KENNETH. M. HENRY, OF SAN FRANCISCO, CALIFORNIA, ASSIGNOR TO ILLINOIS PACIFIC GLASS COMPANY, OF SAN FRANCISCO, CALIFORNIA, A. CORPORATION OF CALIFORNIA. PROCESS OF ANNEALING GLASS. Application filed November 25, erial No. 752,110. Thi invention relate to the annealing of gla, more particularly to the art of alo be formed during the cooling through annealing a carried on in temperature-con the annealing range, a explained later. trolled lehr or muffle. My experiment have concluively etab The annealing of gla a heretofore car lihed that at any temperature below the an ried on ha required a great deal of time, nealing range, a above defined, it i impoi in the cae of large bottle, ay of five ble to impart tre train that will af gallon capacity, it ha been practically im fect the ultimate annealing of the gla. poible to properly anneal them in a lehr, Within the annealing range, however, gla reort being had to annealing oven, where can be controlled at will, all exiting the bottle have to be held for everal day. tre train can be removed, or tre The object of my invention i to properly anneal gla article, including large-ized after train the annealing can be imparted i completed. that will remain bottle, in a lehr or temperature-controlled Furthermore, for the complete removal of muffle, to horten the time required by a all poible tre train, temperature matter of everal hour, or even day, de time are correlative factor. At any pending on the ize character of the temperature (within the annealing range) article. there i a definite time interval neceary for It will be helpful to an underting of removal of tre train, which I hall my proce to briefly decribe ome of the term the annealing time. Thu the an term hereinafter ued: nealing time' may conit of a brief period Annealing temperature or the upper if the temperature maintained be high, or it limit of the annealing range' i that tem will be a longer period if the temperature perature at which all exiting tree during the ame be lower. train will be eliminated within two min When a temperature gradient (riing or ute after the gla i ubjected thereto. falling) i imparted to gla in the vicou Annealing range' i a Zone of about 270 tate, the molecule are free to move do degree perature. Fahrenheit below the annealing tem move to conform to the temperature gradi ent without the introduction of tre be Gla, according to the temperature to caue of uch freedom. After thi readjut which it i ubjected exit in three tate, ment, when the gla ha cooled the namely, vicou, platic, elatic. temperature gradient i removed, thi condi Wicou' tate i that condition of the tion i frozen' retained in the platic gla above the upper limit of the anneal elatic tate of the gla ucceively ing range where the relaxation of tree i i a permanent tre train. The intantaneou. ame reult, although partial in degree, may Platic' tate i that condition of the follow from a cooling gradient imparted to gla in the annealing range where the re the gla in the upper reache of the platic laxation of tree take an appreciable tate. There i no harp definition between length of time. the platic the vicou tate, in the Elatic' tate i that condition of the upper reache of the former, the molecule gla below the annealing range where the of gla being omewhat mobile, may par relaxation of tree take an infinite length tially readjut themelve to conform to a of time. cooling gradient take on a change that Temporary tree' are thoe imparted become permanent tre aid train when to the gla in the platic elatic tate. the condition become frozen by the elatic The temporary tre produced by a heating tate. of the gla. gradient i called a "poitive' tre, The molecular readjutment to which ref that produced by a cooling gradient i called erence ha been made i called vicou yield a revere' tre. ing, or lot motion. Permanent tree' are thoe due to the Under prior method of annealing, thee imparting of "a temperature gradient while factor have not been properly oberved, in the vicou tate. Permanent tree may it i the uual practice to bring the gla ar ticle to a high temperature where all train SS S

3 O O 60 diappear in a reaonably hort time, ing period would alo be removed at thi thereafter lowly gradually lower the point. From thi point the gla i cooled temperature. The temperature at which all at a progreively increaing rate, which be the train diappear within a reaonably come very rapid a the lower limit of the hort time i o high, particularly in article annealing range i reached. After the lower O like large bottle, that an inordinate length. limit i paed, the cooling may be a rapid of time i required to cool the article. Any a deired, aving only that the temporary attempt to accelerate cooling in the upper tre imparted by the rapid cooling may not reache of the annealing range will caue re be o great a to overcome the tenile vere train to occur in the gla article, trength of the gla thu reult in reultin imperfect annealing... breakage. In by the preent method, intead of In the foregoing example but two an accomplihing all of the heating in one nealing tage are ued. Thi i not in tage, a in prior method, proviion i obedience to a et rule, but i governed by made for carrying on annealing in two or the chemical phyical characteritic of 80 more tage, that i to ay, the gla article the gla. In ome glae more than two are rapidly heated to a relatively high point tage of annealing may be required before in the annealing range, bordering on the up the gla become ufficiently immobile er limit of the platic tate the lower free from lot motion to permit a rapid imit of the vicou tate. Here the tempera cooling in the final tage of the proce. ture i maintained until all tree A for the theory of the everal tage train are removed, then the tempera employed, let it be here explained that the ture annealing i rapidly range lowered held to a there point long within enough the contant temperature at the high point in the annealing range would uffice to remove to remove the revere train, caued by the all tree, but the cooling gradient from 90 rapid drop in temperature. Thereafter that point would necearily be a low one cooling can be carried on continuouly critically controlled within very narrow with progreively increaing Ey. l limit, to avoid introducing train anew b til the article are at a temperature below yicou yielding. On the other h, anneai the annealing range, without danger of im ing only at the lower reache of the range, parting revere train. Thereby perfect whence the rik of new train would be annealing can be effected in a period of three negligible, would require a time factor that or four hour a againt a period of twelve i economically prohibitive. Therefore, my to eventy-two hour under prior practice. proce remove the tree at a high tem In the accompanying drawing I how.a perature where the annealing time i hort, 100 chart illutrating a temperature curve uit then cool rapidly to a temperature till able for annealing five-gallon bottle of a within the annealing range, where ordinari particular character of gla. Thi curve ly the annealing time would be great, but will vary, depending upon the nature of the i moderate on account of the mall, regu gla depending alo in ome intance lar amount of lot motion engendered by OS upon the hape ize of the article. the traight cooling, from thi point However, the neceary variation can readi the fixed condition of the gla permit of ly be arrived at by thoe killed in the art, reaonably rapid cooling without danger of by mean of preliminary tet. appreciable permanent tre train. Gla article a they iue from the form A pecific example of my proce a ap 10 ing machine may be either hotter or colder plied to a very heavy bottle made to hold than the annealing temperature a found for five gallon of liquid content i hown in the particular gla under treatment. In the accompanying drawing. The vertically either event they are brought Epidly, to Spaced line repreent temperature in de the proper annealing temperature, which gree Fahrenheit, the horizontally may be the upper limit of the platic tate Spaced line time in minute. Although thi or lower limit of the vicou tate. When type of bottle ha been manufactured for the annealing temperature i reached, the many year, it ha been impoible to an heat i held contant until all of the tree nealit conitently properly, on account are removed. It follow that the higher the of it great weight ize. In fact, it i temperature to which gla i heated, the now known that it would not be poible horter will be the time required to remove to anneal uch a bottle in a lehr with good the tree. When the gradient have been commercial reult without employing the removed the gla i cooled rapidly to a tem proce here dicloed. perature lower in the annealing range, Thee bottle generally reach the anneal 25. there again held contant for a ufficient ing apparatu at a temperature below the period of time to remove the tree im upper reache of the annealing range. Im parted by vicou yielding during the cool mediately upon entering the Iehr they are ing, Any tre that wa inadvertently left. heated rapidly, to 9 degree Fahrenheit, in the gla at the end of the firt anneal held at thi temperature for twelve

4 O 5 35 O minute. The temperature i then dropped to 875 degree Fahrenheit a rapidly a the tre imparted during the drop in tempera apparatu will permit. They are held at ture can be afely removed at a low tempera thi temperature for a further period of ture the time of cooling (... iniderably hortened. twelve minute. Succeively they are cooled to 835 degree Fahrenheit at the rate In all known procee heretofore ued, O of two degree per minute, to 7 degree it wa impoible to hle different weight Fahrenheit at the rate of five degree per ize of gla article without changing minute, to 0 degree Fahrenheit at the the annealing cycle. In other word, a curve rate of 10 degree per minute, thence deigned for mall ware would not anneal to room temperature at will, with due re the larger ize. The proce here et forth gard for breakage from udden hock. Due will correctly anneal article of any ize or to the neceity for accurate control of tem weight without change, provided only that perature, it i preferable to carry out thi the gla be of the ame chemical phyi cal nature. proce in an electric lehr. In applying my proce to gla of dif My proce provide a factor of afety 80 ferent phyical or chemical nature, it i uniformity hitherto unobtainable in com neceary firt to determine the proper an mercial practice. - nealing temperature time the rate Finally, the proce naturally economize of cooling. Thi may be done by reorting both pace time. Thi i particularly to a few preliminary tet, firt to determine emphaized in the treatment of the larger 85 the upper limit of the annealing range of ize of gla ware. For example, the five the particular gla under conideration. gallon bottle already cited i perfectly mine Thereafter the temperature variou tet are time made required to deter certainly annealed ready for packing for in three hour, wherea no le than twelve the removal of the maximum tre at dif hour ha been neceary for the imperfect 90 ferent point within the annealing range. annealing hitherto attained in lehr, in perature From thee i choen tet the whoe lowet annealing maximum time tem the cae of oven three to four day were required. w i poible of commercial adaptation, prefer The preent method differ from that di ably thoe temperature with annealing time cloed in my Patent Number 1,540,264, iued of from fifteen to twenty-five minute. In June 2, 1925, in that the former contem practice, a a factor of afety, the annealing plated partial removal of tre train time hould be lengthened from three to five at annealing temperature, neutralizing minute, to inure againt temperature fluc the remaining tree train by the tuation. cooling curve or gradient; wherea in the. 00 In the determination of the cooling rate, preent method all tree train are the initial cooling mut be low, ince the removed at high annealing temperature, lot motion i a function of the temperature whereupon the temperature i uddenly the rate of cooling. The amount of lowered lot motion for identical cooling rate de lower temperature. re-annealing carried on at thi 05 creae by one-half for every 18 degree What I claim a new deire to ecure Fahrenheit drop. Therefore, a the temper by Letter Patent i: ature lower, the cooling rate may bein 1. In a proce of annealing gla article creaed, even within the annealing range, in a temperature-controlled lehr or muffle, without increaing the amount of lot mo the tep of ubjecting the gla-ware to a. O tion. Regard hould alo be paid to the plurality of annealing tage, firt at a high maximum thickne of the gla, ince the temperature thereafter at a lower tem tre i directly proportioned to the quare perature, all within the annealing range. motion. of the thickne for unit gradient or lot 2. In a proce of annealing gla article in a temperature-controlled lehr or muffle, 13 Since the proce i to be commercially the tep of ubjecting the gla-ware to uni applied in an electric lehr, the number of form temperature for a relatively hort time change in the cooling rate hould be gov within the upper reache of the annealing erned by the number of ection economical range, lowering the temperature a ubtan ly poible of cooling, either three or four. tial amount with appreciable rapidity, lo The length of time for cooling at a contant re-annealing at aid reduced temperature. rate i determined by the length of the heat 3. In a proce for the annealing of gla ing element ection, the peed of the article in a temperature-controlled lehr or conveyor within the lehr. muffle, the tep of firt annealing at a rela In by the preent proce, a gla tively high temperature, rapidly reducing article can be completely annealed from the temperature to a point till within the every poible degree variety of tre annealing temperature, re-annealing at train at a high temperature, then uch lower temperature, thereafter con by re-annealing at a lower temperature the tinuouly reducing the temperature to a point below the annealing range.

5 2. 4. A proce of annealing gla article in a lehr or the like, which conit in firt derin ing on the upper limit of the platic bringing the gla-ware to a temperature the lower limit of the vicou tate of ufficiently high to caue removal of all that particular gla, maintaining thi tem: tree in the mot economical time, lower perature ufficiently long to remove all 35 ing the temperature a ubtantial amount tree, lowering the temperature with ap a rapidly a poible, maintaining thi low preciable rapidity to a point within the an ered temperature for a period of time uffi. nealing range, maintaining thi lowered cient to remove any revere train imparted temperature for a time ufficiently long to 40 O during the rapid fall of the temperature, caue all revere tre imparted by the ud thereafter continuouly with pro den fall of temperature to be removed, greively increaing rapidity lowering the thereafter reducing the temperature with temperature to a point below the lower limit progreively increaing rapidity to a point of the annealing range. below the annealing range A proce of annealing gla article in. A proce of annealing gla article in a lehr or the like, which conit in bringing a lehr or the like, which conit of firt the gla-ware to a temperature within the bringing the gla-ware to a temperature of upper reache of the annealing range, main approximately 9 degree Fahrenheit, main taining thi temperature for a time uffi taining thi temperature for a period of ap ciently long to remove all tree, then proximately twelve minute, lowering the I rapidly lowering the temperature to a point temperature rapidly to approximately.875 till within the annealing range, maintain degree Fahrenheit, maintaining thi latter ing thi reduced temperature for a time uf temperature for a period of approximately ficiently long to remove all revere train fifteen minute. thereafter reducing the caued by the udden fall of temperature, temperature at approximately the following greively thereafter, increaing continuouly rapidity, lowering with pro rate: 2 degree per minute for twenty min the ute; 5 degree perminute for the next even temperature to a point below the annealing teen minute; 10 degree per minute range. for the enuing twenty-five minute. 6. A proce of annealing gla article in a lehr or the like, which conit in firt bringing the article to a temperature bor KENNETH M. HENRY. 55