US1840463A - Method of and apparatus for annealing glassware - Google Patents

Description

Jan. 12, 1932. v MULHOLLAND 1,840,463

METHOD OF AND APPARATUS FOR ANNEALING GLASSWARE Original Filed Sept. 10, 1923 3 Sheets-Sheet 1 Jan. 12, 1932. v MULHOLLAND 1,840,463

METHOD OF AND APPARATUS FOR ANNEALING GLASSWARE Original Filed Sept. 10, 1923 3 Sheets-Sheet 2 In $972207? VazyzZ/YaZZaZZarzd WZZaess. 6% mg 3 ail/7077109 Jan. 12, 1932. v. MULHOLLAND 1,340,463

METHOD OF AND APPARATUS FOR ANNEALING GLASSWARE Original Filed Sept. 10, 1923 3 Sheets-Sheet 3 [wavwio Vez gz'Z MzeZfioZZarzd W2 Zwess: a W m narrate VEESG-IL MULHOLLAND, OF WEST HARTFORD, CONNECTICUT, ASSIGNOR Till EARTFOBD EMPIRE COMPANY,'0F HARTFORD, CONNECTICUT, A CORPORATION Q1? DELAWARE BEEIHOD OF AND APPARATUS FOR ANNEALING original application filed September 10, 1923, Serial No. 661.82% Divided this application filed may This invention relates to a method of and apparatus for annealing glassware, and particularly for annealing it as it passes rapldly in continuous procession from the ware-shaping or forming machines in quantity production. This application is a division of my copending application, Serial No. 661,827, filed Sept. 10, 1923, now Patent No. 1,735,353, issued November 12, 1929.

Glassware, after being shaped in a mold, is ordinarily removed therefrom while still very hot and annealed by gradually cooling it to atmospheric temperature. If merely set out in the open air it will cool too rapidly and unevenly. Its outer surface will cool and contract more rapidly than its interior portions, thus altering the relative dimensions and locations of different portions of the piece and creating stresses therein, which tend to disrupt it. To avoid or minimize these stresses is the object of annealing. If not sufficiently or properly annealed so that undue internal stresses still exist therein, the article breaks easily when used or handled, and may even fly into small pieces spontaneously.

'When removed from the mold, the different portions of the article are usually not at the same temperature. These portions which have been in direct contact with the shaping mold or other metallic parts, and especially its thinner portions, are at a lower temperature than other portions of the article. In general, the interior portions of the walls of the article are considerably hotter and more plastic. than are the surface portions, so that frequently a newly molded article is held in shape only by its less plastic surfaces. In some instances the articles, especially those having walls of uniform thickness, are sufficiently uniform in temperature and plasticity to be initially free from undue internal stresses. In other instances, due to lack of uniformity in wall thickness, temperature and plasticity, the article will be full of internal stresses directly after leaving the mold.

In some of the latter instances some articles do, and others do not, contain an amount of heat which, if uniformly distributed throughout the article, would release these stresses. These instances all occur in commercial production, in which different forms of glassware, sometimes from difierent machines, are at various times delivered to the same lehr. An adequate lehr for general. commercial use should, therefore, be adapted to properly and uniformly anneal the glassware delivered to it in any of these varying conditions.

In the usual practice of annealing, the first step is an attempt at equalizing the temperature in each article, and in all the articles by reheating all portions thereof to approximately a low red heat, or at least to a condition suiiiciently plastic to release any thenexisting stresses. With existing apparatus, however, such equalization is more or less imperfect and incomplete, so that difierent articles, or different portions of the same article, are at unequal temperatures and unequal conditions of stress when the next step, which is that of cooling the articles, begins. This inequality of condition at the beginning of the cooling stage is likely to continue and increase throughout that stage, so that initial stresses remain, and additional stresses are produced on account of lack of provisions for distributing the heat and for equalizing the temperature by the transference of heat between difierent articles and between different portions of the same article. This cooling is usually done slowly because of the difiieulty, with existing commercial methods and apparatus, of cooling rapidly and at the same time uniformly enough to avoid unequal contraction of the partially plastic glass and the consequent setting up of new internal stresses.

In annealing glassware commercially, it is customar to pass the were, disposed in several longitudinalrows side by side, on a metallic conveyor througha masonry passage or tunnel heated with a fire box to a low red heat at the entrance end, and havinga gradually decreasing temperature toward the discharge end whereit is at the prevailing atmos- )heric temperature. Such an apparatus is lrnown as a tunnel lehr.

This customary form of tunnel lehr for annealing glassware has various disadvantages, among which are the following: It

requires a considerable uantity of fuel. The time required for annea ing the ware is from 2 to 5 hours, depending on the kind of ware, the bulk of such ware requiring at least four hours to anneal. This long period between the shaping of the ware and its inspection, ermits defective ware to remain undetecte for this period, during which the shaping machine frequently continues to produce ware having such undetected defects, which results in a considerable loss of ware.

The size and weight of such a lehr large enough to hold the large amount of ware produced during such a long annealing period is considerable and its first cost is high. It is made of heavy masonry and requires substantial foundations. It must, therefore, be located with regard to these conditions, must remain where built and cannot easily be lengthened or shortened. On account of the bulk of masonr and metal work which it contains, and t eir capacity for absorbing heat and wasting it by conduction and radiation to the outside, considerablefuel is required to bring it up to and malntaln it at proper operating temperature. Moreover, the annealing done by it is frequently more or less uncertain and incomplete due not only to inadequate control of the initial heating and the rate of subsequent cooling of the ware, but also to considerable difierences in temperature between different points in the same transverse section or zone of the tunnel. This causes or permits too Wide a difference in temperature between different portions of the same article and between different articles of the "same transverse row, as the articles advance through the lehr. For instance, the bottom end of an article being at the bottom of the tunnel, and in contact with the colder metallic conveyor, is frequently much colder than the upper end of the same article as it advances through the lehr. Similarly, the articles at either end of a transverse row-of articles advancing through the lehr may differ in temperature from other articles in the same row. This results in a different rate of cooling for different articles in the same row and also tends to preclude proper annealing of many of the articles, even if each article itself should be at a uniform temperature throughout. These conditions tend to produce, even with a slow rate of cooling, a faulty annealing of the ware.

If all portions of a glass article which is bein annealed are brought to a uniform annealmg temperature and the subsequent cooling be kept uniform as to all. its portions, it can be cooled much more rapidly than in the present annealing lehrs, and yet be perfectly annealed without undue internal stresses. For example, if the article is enclosed in a metallic container and kept out of contact with the container walls, both article and container being at a sufiiciently hi h and even temperature throughout, and t e container is then cooled evenly throughout all portions, the article can be cooled in from 25 to 30 minutes to a temperature at which it ma 'be safety handled and be properly annea ed. This is because all portions of the article, beginning at a sufiiciently high and equal temperature, radiate their heat uniformly and equalize it, so that at no time during the cooling are there substantial temperature difierences between the different portions of the article, thus avoiding the setting up of stresses therein by unequal contraction. The factors contributing to this result include the rapid and uniform distribution of heat throughout the article by radiation and reflection thereof between the container and the article; the exclusion of air currents which would otherwise 0001 some portions of the article more rapidly than other portions; and the cooling of the container at a rate sufficiently uniform and rapid to reduce its temperature just far enough below that of thearticleto permit the desired rate of cooling of the article, by transference of its heat to the container, such a temperature differential or gradient, varied as desired, being maintained until the article is sufiiciently cooled.

There is, however, a certain critical range of temperature between that at which the article is partially plastic and that at which it is completely set. If cooled too rapidly while passing through this critical range, internal stresses will be set up in the article, and it will not be properly annealed. There is, for any kind of glass and type of article, a permissible maximum rate of cooling, which may be applied through this critical temperature range. Any slower rate wastes time without improving the result. After the article has been cooled throughout its critical range of temperature at a sufficiently slow rate, it may then be cooled very rapidly to a temperature at which it may be safely handled.

Under the ideal conditions created by enclosing the article as above described, this maximum rate of cooling may be attained, whereas under ordinary manufacturing conditions obtaining with previous forms of tunnel lehrs, such ideal conditions do not exist and the uniform and maximum rate of cooling cannot be closely approximated.

Most glass articles made in quantity have suflicient heat yet remaining in them when removed from the shaping mold, so that their annealing may begin at the proper temperature without supplying additional heat, provided that the heat already in each article is properly conserved and redistributed. If, for instance, the article is transferred from the mold while still hot directly into a proper environment, as in the container referred to above, it can then without any reheating be gradually cooled and yet be thoroughly annealed. If the container is made of thin sheet metal provided with insulation on the outside, it will not be necessary to preheat it, there being suflieient heat in the article to heat the small mass of the insulated thin sheet metal container to a temperature very nearly as high as that of the article, or surficiently high to begin its proper annealing. This container can then, as before described, be uniformly cooled through the proper cycle to secure the quickest possible cooling and yet properly anneal the article.

Although glassware may, as above described, be satisfactorily and quickly annealed in separate enclosing containers, the problem of so annealing the ware coming rapidly in a continuous procession in quantity production from the Ware-forming machine or machines, presents various difiiculties. To provide and handle enough of the above-described containers would be diificult and expensive and, in view of the present invention, unnecessary.

It is an object of my invention to combine and correlate the above-described features as far as possible to save fuel and reduce the time of annealing, as well as to overcome or minimize the various disadvantages of the present tunnel lehr. More specifically, the object is to create a proper environment through which the glassware may be moved continuously on a conveyor and be subjected as nearly as possible to the ideal cooling conditions and cycle obtainable with the abovedescribed individual containers, so as to produce better annealing than has been customary in commercial manufacture of glassware, and to reduce the time and costof the operation. -Another specific object is to provide a lehr and method of operation capable of annealing glassware as far as possible without fuel; that is, without supplying other heat than that of .the articles themselves. Other objects of my invention will be apparent from the following description.

The ware is passed through a lehr tunnel whose walls are constructed so that the various portions of the tunnel may be quickly raised to the desired temperature with a minimum amount of heat. in this and in other ways the tunnel is adapted to maintain a proper environment about the ware as it is passed therethrough. The temperature of this environment and of the ware as it passes through the tunnel is controlled in part by a eountercurrent of cooling air. The thermal properties of the tunnel, especially at its hot end, are made more efficient by making interior surfaces of that end of the tunnel of bright reflecting material.

The ware is carried through the tunnel by an endless conveyor which is of low heat capacity and adapted to the desired thermal conditions. In returning to thehot end of the tunnel, this conveyor passes through the bottom of the lehr tunnel close to the ware, whereby the return strand when it again takes on the hot ware, is reheated to nearly the temperature of that ware, a factor which contributes to the proper maintenance of the desired thermal conditions in the tunnel. The tunnel is made adjustable in cross-section to suit the size of the were being made, as well as to secure other desirable advantages to' be described. The lehr is made of separable unit sections placed end to end to form the tunnel, and provisions are made for taking care of the expansion and contraction of the parts most subjected to heat. There are various structural features which contribute to the maintenance of such proper heat conditions, such as low heat capacity of the tunnel walls and parts, efficient heat transference, heat balance of the bearing strand and returning strand of the conveyor chain, and maintenance of proper temperatures and temperature gradients. These features, as well as additional features to be hereinafter pointed out, will best be understood from the following description, to-

gether with the accompanying drawings, in

which:

Figures 1 and 2 are side views, which taken together show a central longitudinal section a through the receiving and the discharging ends of the lehr, it being understood that these ends are or may be connected by any desired length of similar construction;

Fig. 3 is a transverse section through one of the lehr sections, as on the line 33 of Fig. 1;

Fig. 4 is an enlarged side view in section in the same plane as Figs. 1 and 2, showing the expansion joint in the bottom o1 the lehr;

Fig. 5 is an enlarged plan view, in section on the line 55 of Fig. 1; ahd

6 is a diagrammatic plan the flow of air around the ware.

The lehr may be, and for general use, preferably is made up of a series of unit sections placed end to end, for convenience in manufacture, shipment and installation. It further enables any desired length of lehr to be built up from standard unit sections. It also enables the length of a lehr to be altered at any time by adding or removing sections.

The assembled lehr comprises a receiving section 6 at its hot end (Fig. 1), as many intermediate sections 7 as may be desired, a delivery section 12, and a cooling section 13 at its cold end (Fig. 2). All of these sections are supported on a structural steel support, including legs 8, which. are preferably adjustable in length to adjust the height of the lehr, and which are secured in adjusted position by bolts 9 and connecting channel irons 10. Both ends of the intermediate sections 7 carry depending angle irons 11, by

illustrating which they may be connected in abutting relation by suitable bolts or other connections.

The lower ends of the angle irons 11 are bolted to the channel ironslO, as shown in Figs. 1 and 2.

The walls'of the tunnel formed by sections 7 and 12 are made of an outer casing of sheet metal or other suitable material, an inner lining of sheet metal as thin as is consistent with the strength required, and an'intermediate filling of heat insulation. The thin sheet metal linings may be quickly heated up to their final working temperature with a minimum amount of heat, since their heat capacity is very low. The insulation outside of these linings reduces their dissipation of heat to the outside, so as to require only a minimum of heat to maintain any portion of the lehr tunnel at the desired temperature.

Each section 7 and 12, as viewed in crosssection in Fig. 3, comprises a horizontal bottom wall with vertical walls at each side, closed by a top plate. The vertical side walls and bottom form a channel which comprises an outside casing 17 which is spaced from a bottom lining 16 and side linings 15 by transverse stays 18 (Figs. 4 and 5), two of which may form ends for the walls of the section. The top 21, preferably made ad justable, consists of a sheet metal casing 22 and a lining 23. The casing 17 and the linings 15, 16 and 23 are made of thin sheet metal. The spaces between the lining 23 and.

the casing 22, and between the linings 15 and 16 and the casing 17, are filled with heat insulating material .19, whichis preferably a loose material of high insulating efficiency and with a low heat capacity, such, for instance, as kieselguhr or mineral wool. The top of each tunnel section is closed by a cover plate 20 which prevents leakage of air. The sheets of metal forming the casings and lin ngs and the top plate may be fastened together in any of the ways well known to sheet metal workers.

In order to better control the air currents and to increase the efficiency of radiation and reflection throughout the cross-section of the tunnel, its cross-sectional area may be adjusted in accordance with the size of the ware being annealed. For this purpose one or more of the tunnel walls may be made separate from the remainder of the tunnel and adjustable relative thereto.

On account of the fact'that in different commercial ware there is more variation in height than in width, and also because it is important to control the circulation of the air between the ware and the top of the tunnel, I prefer to make the top or ceiling walls 21 of the tunnel sections 7 and 12 adjustable vertically between the side walls thereof, to suit the height of the ware being annealed, and also to assist in controlling the currents of air within the tunnel. Openings 25 (Figs. 1 and 2) may be provided in these tops and also in the cover plate 20 for the insertion of a thermometer, and these openings may be closed when not in use.

The device for supporting and adjusting the top comprises studs 26 xed in the top 21 and projecting through holes in the plate 20, and in the reinforcing bars 27 and 28 (Fig. 3), hand nuts 29 being threaded on the studs. One stud is provided near each end of the top, so that theheight of the top may be adjusted independently at either end, and it may be set at an angle or horizontally, as desired. In order to facilitate adjustment of the top, so as to insure that it will clear the ware to an extent determinable from the outside, means are provided outside of the tunnel for indicating the position of the top. For this purpose, the studs 26 are made of 'such length that their projection above the top of the hand nuts 29 is equal to the distance from the upper surface of the conveyor to the lowest part of the top. By thi s construction the top may be adjusted to the desired height by setting a piece of the ware on each nut 29 and turning the nut until the end of the stud 26 projects above the top of the nut a distance equal to the clearance desired over the ware in that portion of the tunnel, as indicated in Fig. 2. A graduated indicating device operating in a similar manner may be fastened to the top, if desired. By setting the adjustable top down fairly close to the top of the ware, the cross-sectional area of the tunnel and the space to be heated are reduced, the air currents are confined closer to and directed between diflerent articles, and the heat reflecting and radiating effects of the tunnel walls are also increased.

In addition to the height adjustment for the tops 21, some or all of them may be provided with means for controlling a flow of air from the cold end toward the hot end of the lehr tunnel. For this purpose the righthand end of the top of each section 7,as viewed in Figs. 1 and 2, is curved so as to form a transversely extending deflector 30 to intercept a part of the air passing through the tunnel and divert it into a stack 31 which extends across the entire width of the tunnel. By means of this construction the hot air or other gases passing through the tunnel may be withdrawn therefrom in uniform quantities transversely thereof, thus insuring a uniform temperature across the tunnel. The tops are made thinner at one end, so that the deflectors on one top may project below the adjacent thinner end of the next top (Figs. 1 and 2). The stacks 31 are supported on the plates 20 with their lower ends extending into the tunnel between the ends of adjacent tops 21. Each stack 31 is provided with a damper 32 by which the escape of air may be regulated. The top for the delivery section 12 and that the stack 53 is larger than the stacks 31, a greater quantity of air may be diverted hy the deflector 52 and stack 53 than is diverted by the other deflectors and stacks. At

the'right-hand end of the delivery section- ,12, a wall 56 is fixed so that vertical adjustment of the top causes the deflector 52 to project more or less below the wall 56, thereby increasing or. lessening the amount of air diverted to the stack 53.

The ware is carried through the lehr by a conveyor which, in order to reduce the mass ofmetal which is to be heated by the ware passing through the lehr, isl madeof a pluralchains themselves form the conveying surface and are sufliciently strong to do their work while having a minimum mass and heat absorbing capacity. The chains are pulled through the lehrby sprockets 36 (Flg. 2) fixed on a shaft 37, driven by a motor 38 through a chain 39, worm and gear 40 and spur gears 41, 42 and 43.- These .gears may be made removable so that others may be substituted-conveniently to change the speed of the conveyor. The chains pass around a roll 46 (Fig. 1) at the receiving-end, and idle rolls 47 are-provided where required to support and guide the chains. As the ware-bearingstrand of the conveyor moves from the hot end of the lehr toward the cold or discharge end thereof, it is PIOilQS- sively cooled. Y The return strand of c am travels back through the heat enclosing tunnel and is progresslvelyreheated, 8.111V1Ilg at the receivlng end of the lehr at about the temperature 'of the ware received.- In this; .g g-way the ware-bearing strand and return strand of the conveyor balance eath other in their heat effect without disturbing the desired conditions in the .lehr'. tunnel. 1

There are 15 of the chains 35 shown in Fig.

- U0 3, but this number may be varied, as desire The lower or idle strands of the chain return through the space or spaces between the bottom linin 16 and the upper or ware-conveying stran s, which are supported in close eproximity. thereto by sheet metal lates or tables 47. This construction exc ude's air currents from the space 45, thereby maintain ing the heat in the lower part of the tunnel and assisting in the} maintenance of uniform '60 heat conditions throughout any cross-section .of the tunnel. The tables 47 are made of thin v. sheet metal to reduce their heat capacity and topermit the rapid transference of heat be-' tween the upper and lower strands of chain.

5 The hotter strands of the chain bearing the to form the whlls and other sheet metal warps and hue eseasily under all length ware heat the tables 47 which, in turn radiate their heat to the colder return strands of the chain underneath, thereby carryin out the heat balancing process above descn ed. To stren hen and support the tables and maintain t e space or spaces 45, the tables are provided with ribs or flanges 48.

The lehr is (provided with expansion joints to permit, un er changes of temperature, the free expansion and contraction of the tunnel walls and parts of the lehr, and particularly of the inner linings of the tunnel and of other arts most exposed to heat. This is articuarly desirable in. a lehr tunnel of t e type described where thin sheet metal is empltgig arts. Such the influence of temperature changes, ess provisions are made to allow it to expand and contract freely.

One of the features whichpermits free exity of parallel light endless ch'a1ns35; The

pansion and contraction of the various parts is the construction of the lehr in a series of unit sections which are placed end to end. Each of these sections 7 and 12 preferabl includes expansion joints so that'all heated parts may expand and contract independently" in each section without affecting the overof the unit, thereby preventing any, longitudinal movement of the lehr as a whole under the influence of heat, and distributing the expansion and contraction over several joints. The tables 47, side linin 15 and bottom linin 16 are provided wit expansion joints in icated at 49 on Figs. 1. and 2. The joints are formed by folding back adjacent marginal edges 50 (Figs. 4 and 5 of the linings and tables andconnecting t e parts by strips 51 having similar turned-over edges loosely embracin the edges 50. These expansion joints are e own as positioned near the middle of each section, but they may be positioned at the end lof-each section or at both places if desired. 'Sim'ilan, expansion joints may be rovided in the outer casing 17, although this is not considered essential, as that casing remains .relativel cool on account of itsinsulation. The various sectional tops 21 are separated in a manner-which would not usually require expansion joints, but they may be provided with simi ar expansion joints, if desired. The transverse stays 18 are suflicient- 1y flexible to permit their inner edges to move with the tunnel linings as the latter expand --orcontract.

In order to control the cooling of the ware as it moves toward the discharge and of the lehr, cooling air is "forced into the lehr tunnel near the dischar end thereof, suitable meansbeing provi ed for a controllable supply of air of the desired "volume. andpressure, which flows from the discharge or colder'end of the lehr toward its hotter end. A blower 57 (Fig. 2) driven no t ' deflector and escaping up 1 by a motor 58 is arranged to force air through a wind box 59 which directs the air against the glassware and into the tunnel. An adjustable damper. 60' is provided to regulate the amount of air discharged by the blower. The air is directed onto the ware and into the tunnel by a series of transverse nozzles 61, gradually decreasing in width toward the hot end of the tunnel and formed by a series of flanges on the bottom wall of the wind box. The volume of air entering the tunnel is controlled by the damper 60 and the air passing through difierent portions of the tunnel is regulated by adjusting the dampers 54 and 32, and by adjusting the height of various tops 21. The air dis-' charged from the wind box 59 is first directed against the colder ware which has emerged from the tunnel, so as to give it its final cooling at a rapid rate. The air then flows between the various pieces of ware and enters the tunnel, the direction'oi flow being indicated by the short arrows in Fig. 2. At about that portion of the tunnel where the were is cooled to about 300 F. a large part of this air is diverted by the deflector 52 and escapes up the stack 53. The remainder of the air continues to flow toward the hot end of the tunnel and is forced to flow between and around the pieces of ware by the low position of the tops 21. As the air approaches the next deflector 30, the gradually lncreasin space above the ware, due to the slope of t e-top, permits a certain portion of the hotter air to rise and flow above the ware, and it is diverted b deflector 30 and escapes up the stack 31. 11 this way the air flows a ong the tunnel toward the hot end, becoming progressively hotter by its absorption of heat from the ware and the tunnel walls, a determinable portion being diverted by each the corres onding stack. Only a ver sma portion 0 the air reaches the hot on of the tunnel. It is preferable, however, and highly advantageous to maintain a sufiicient pressure of air toward the hot end of the tunnel to prevent outside and flowing along it toward the cold end.

By setting the adjustable tops 21 at the pro er height and adjusting the various stac dampers, as well as by sup lying a sufiicient amount of cooling air rom the nozzles 61, the amount of air passin at various points throughout the Ian h o the lehr tunnel may be regulated, an the temperature of the ware as it moves through the lehr may be controlled as desired. With a proper setting of these various parts and a proper supply of cooling air, the latter is forced to circulate between the glass articles as well asalong the linings of the lehr tunnel in a controllable volume. If the air passing along any-portion of a transverse section of the lehr tunnel becomes hotter than it is in other portions of that section, it tends to rise into the adjustable space above the ware and to be diverted into a stack besides having portions of its heat radiated and reflected across the tunnel by the tunnel walls. This assists in keeping the temperature uniform throughout any transverse section.

The cooling air not only cools the ware directly, but it also cools it indirectly by cooling the linings of the tunnel. The ware radiates heat to the linings of the tunnel which, being surrounded by heat insulation, tend to acquire the temperature of the successively passing pieces of ware, and would thus acquire a temperature only very slightly below that of the ware were it not for the cooling air which absorbs heat from these linings, maintaining them at a' suitably lower temperature than that of the adjacent ware, thus maintaining the desired temperature gradient to control the rate of radiation of heat from the were to the linings.

' The cooling air gradually becomes hotter as it progresses from the cold end toward the hot end of the lehr, so that there is at no time an abrupt or injurious difi'erence of temperature between the cooling air and the ware, or between the cooling air and the linings at any transverse zone of the lehr tunnel.

The rate at which the were is cooled is an important factor and contributes to the speed and perfection of annealing. If the drop in temperature throughout the greater portion of the length of the lehr is substantially uniform for each unit of length, the most efiicient annealing may be done very rapidly. Although, as previously indicated, the rate of coolin for some kinds of ware or some kinds of g ass may be increased after it passes through the critical range of cooling temperature, I prefer for safet to continue the uniform rate of cooling suitable for that critical range, down to a temperature of about 300 degrees F., from which point the were may be very rapidly cooled, by subjecting the ware to a large volume of coolcold air entermg the hot end of the tunnel ing air from the nozzles 61 at the cold end of the lehr cooling the'ware rapidly to a safe handling temperature, the excess volume of air being then diverted, as above described.

To obtain the uniform cooling of the ware in uniform units of length of the lehr, the temperature gradient or differential between the cooling air and the tunnel linings, as well as between the cooling air and the ware may be maintained. substantially uniform throughout the desired length of the lehr. The diagram shown in Fig. 6 illustrates the principles here referred to, using. assumed temperatures. It shows three difierent'transverse zones B, C and D in the length of the lehr, the flow of air being indicated by arrows. In zone B the temperature of the ware mightbe 800 F., while the temperature of the adjacent lehr walls might be 675 E the air might be 750 F. Under these condit-ions the temperature of the adjacent lehr walls might be somewhere near 775 F. In zone C, the temperature of the ware might be 700 F., and the temperature of the air passing amongst the ware might be 650 F., while the corresponding temperature of In zone D, the temperature of the ware might be 600 F while the air might be 550 F and the adjacent walls 575 F. In each in-. stance there is or may be a uniform differential of between the air and theware; a uniform difierential of 25 between the air and the walls, and a uniform diflerential of 25 between the walls and the ware. By maintaining a uniform rising temperature radient o the-air as it flows toward'the 'ot end of the lehr, a uniform falling temperature gradient will be-maintained in the lwitlre as it moves towards thecold end of the In Fig. 6 the .ware is for convenience of illustration shown arranged in transverse rows at right angles to the side walls of the lehr. The principle is the same, however, when the ware is staggered or in inclined rows. The temperature gradient in any transverse zone equal to the width of an article is not sufiiciently abrupt to cause stresses between the leading side and the following side of the same article while passing through any of the zones.

' In order to approximate as closely as possible in this lehr the ideal vcoolingconditions, it would be preferable to carry the articles to be annealed through the lehr tunnel in single file. This, however, would require an inconveniently long tunnel, in order to take care of the large commercial production of the average automatic shaping machine and yet provide the proper cooling conditions. To avoid this I carry the articles through the lehr tunnel inseveral longitudinal rows or files, preferably not more than three. This allows a sufliciently equal radiating effect between the articles in each row and the wall linings of thelehr tunnel, so that all the articles and all-parts thereof are subjected to substantially the same heat conditions. If-

. any article or anyportion of any article,

should be at a lower temperature than other portions or thanflother articles in the same transverse zone of the lehr, or the adjacent linings ofthe tunnel walls, then the hotter articles or hotter portions of the same article and of thetunnel linings will radiate and reflect sufli'cient heat to equalize the temperature', thus constantly tending to avoid such when they occur.

differences and to correct themautomatically The reflection of heat from the of the tunnel walls, whether to the articles or from wall to wall may be increasedif-desired by making these linings of metal having portion of the heat radiated to them.

such heat reflecting surfaces, the linings of bright polished surfaces which reflect a lar or or the tunnel walls may be made of various suitable materials, preferbly material capable of 'mai'ntaining a bright reflecting surface at the temperature without corroding, thus maintainmg' the necessary brightness, and may be obtained in sheet form sufiiciently' thin to serve the other purposes above described.

By means of the above described features,

such as tunnel wall construction, which providefor proper insulation, radiation and reflection of heat; the adjustable top or wall, which may be set close to theware to reduce the cross-section of the tunnel and assist in controllin the flow of cooling air; the even cooling eilecton thelehr walls andon the Ware produced by the controlled cooling air,

the temperature of the Warethroughout any transverse section or zone of the tunnel is made so nearly uniform as to approximate the ideal environment. The temperature in any transverse zone of the tunnel is substantially the same in the top, bottom, sides and corners of that zone.

Thus, as the articles pass through the successive zones of the tunnel they have or acquire the progressively falling temperatures of those zones, and all portions of every article passing through any zone acquire approximately the temperature of that zone with sufiicient uniformity for practical annealing. By this apparatus and method average glass articles may be annealed in a very short time, requiring only from 30 to 45 minutes for the annealing and final cooling, as against the usual time of two to five hours required by the best previous commercial anncaling lehrs.

By this method and apparatus most com- -mercial glassware may be annealed entirely which evenwhen removed from the shaping machine and placed in the lehr'in the shortest possible time, do not carry sufiicient heat into the lehr to accomplish proper annealing.

as above described, without the supply of additional heat. It may also sometimes be desirable in the treatmentof the ware, to have articlescooled down before placing them in the lehr to a point where they do not contain suflicient heat for such annealing. In

both these instances, additional heating means may be supplied to the lehr for the purposeof attaining the desired temperature of the ware and of the lehr tunnel at its hot end. For instance, any well known burners or electrical heatingelements may be provided to heat the receiving end of the lehr tunnel, or a lire box of any well-known construction may be used. If desired, a mufiie form of fire box may be employed, so that the receiving end of the lehr is surrounded by a heating jacket instead of by insulation, although if desired, insulation may also be employed outside of the mufile fire box. Such heatin means will only be needed at the hotter en of the lehr, the action of the remaining length of the lehr being as above described.

In starting operation with a cold lehr, some re-heating of the tunnel and conveyor may 7 e desirable, even though it may not be necessary to continue its use after normal heat conditions are established in the lehr. This initial pre-heating may be done by means of burner or other heating elements for the tunnel as above suggested, or in some instances it may be sufiicient to pre-heat the conveyor by a burner 62 or other means which is disposed beneath the idle strand of the conveyor at the receiving end of the lehr. The heat carried in by the conveyor may also be used to pre-heat the tunnel.

The lehr may also be thus preheated initially by passing through it the imperfect ware usually made when starting up the associated shaping machine, until the various molds and molding parts of the shaping machine have been raised to the proper normal working temperature. By the time the shaping machine is producing perfect ware, which sometimes takes as long as twenty minutes to attain, the temperature throughout the lehr will usually be sufficient so that as soon as perfect ware passes into the lehr it will be properly annealed without additional heat.

There are, however, some kinds of ware which may be deliveredfrom the shaping machine into the cold lehr, and the lehr thus started in continuous operation without preheating it, whereupon the various parts of the lehr tunnel will soon reach their proper working temperature and the articles will emerge at the discharge end of the lehr tunnel properly annealed. In any of the above methods of initial pre-heating, the cooling air supply need not be turned on until the ware approaches the discharge end of the lehr, or until the proper temperatures have been attained in the tunnel.

The features'above described, of this invention, relate mainly to its annealing functions. In addition thereto, it has other more general advantages as compared with existing methods and apparatus. The lehr is of light weight and low initial cost. Instead of The various features ofthe invention herebeing built'up by hand labor, in the plant where it is to be used, it may be manufactured complete in a machine shop wherever desired and in quantity production, using jigs and fixtures to facilitate the work and to make its parts interchangeable. It may be made in anneal ware satisfactorily in much less time than is required by other existing commercial lehrs, thusrequiring' a correspondingly less holding capacity for annealing a given production.

v A resultant advantage of this rapid annealing is that the ware asses through the lehr and can be inspected in considerably less than an hour, so that faults due to the molds or other features of the shaping machine can at once be detected and the wastage stopped, thus increasing the saleable production. Moreover, the ware made up to the end of a day can be inspected and packed within an hour after shutting down the shaping machine, instead of requiring several hours, and sometimes an additional shift on Sundays to inspect the ware made the previous day.

The light construction and mobility of this lehr enables its position to be changed whenever or wherever desired. When made of a capacity suitable for annealing the ware moved close to that machine so that the takeout boy can transfer the ware directly from the molds into the end of the lehr, thus saving the services of a carrying-in boy, and saving the breakage of ware by him, which is often very great. Setting the lehr close to the shaping machine also avoids the loss of heat by the ware. The lehr is also well ada ted for receiving the ware from an automatic conveyor or stacker, or directly from an automatic take-out for taking the ware out of the molds.

The method and means employed for conserving and utilizing the heat of the ware, and equalizing that heat throughout the ware by radiation and reflection, minimizes the ,use of fuel and the cost of firing attendance, both of these being avoided altogether in cases where the character of the were permits it to be annealed by its own heat.

Repairs when needed maybe easily effected. When extensive repairs are needed, the lehr may be removed entirely and another lehr substituted in a very short time, and with a minimum of interruption in the production of the shaping machine.

in described as incorporated in a single organized apparatus may be used separately or in other combinations, and various modifications may be made in the arrangement and construction of the parts, and in the method of cooling the article to be annealed. For some uses, as for example for the handling of only one kind of ware, some of the adjustments and other provisions for handling varied kinds of ware may be dispensed with. The lehr tunnel may be made integral throughout its length. In this and in other ways, the method and apparatus herein described and shown may be modified within the scope of the appended claims.

I claim:

1-. A lehr for annealing hollow glassware, comprising insulated walls forming a tunnel, an endless conveyor of open-work material having aworking strand to advance the ware through the tunnel while permitting the circulation of a heat controlling medium about all sides of the ware, and a return or idle strand passing through the tunnel, and a source of heat associated with and below said return strand for heating said strand and also, at least to some extent, said tunnel.

2. A lehr for annealing hollow glassware, comprising a tunnel having an inner wall backed by material of higher heat insulating' characteristics than said inner wall, an endless metallic open-work conveyor having a working strand to directly support the hot ware and move it through the tunnel, and an idle or return strand passing in such close proximity to the working strand along its entire length within the tunnel that it will be heated thereby.

3. A lehr for annealing hollow glassware, eoinprisinginsulated walls forming a tunnel, a metallic conveyor of open structure to advance hot ware through said tunnel while in direct contact therewith, said conveyor being movable in a path in proximity to hot ware for a material period immediately prior to its engagement therewith, whereby the conveyor is preheated before it contacts with hot ware.

4. In the annealing of articles of glassware in an insulated tunnel lehr, that method which comprises conveying the articles through the tunnel on a conveyor of openwork material, preheating the conveyor by passing the return strand thereof beneath the ware bearing strand and in heat transferring proximity to the ware thereon for a material time immediately prior to the engagement of portions of the conveyor with the entering glass articles, and circulating a heat controlling medium on all sides of the Ware.

5. Apparatus for annealing glassware, comprising a tunnel having an inner wall backed by material of higher heat insulating characteristics than said inner wall, a plu- 5 rality of longitudinally extending supporting members disposed within said tunnel, an

conveyor having the ware bearing strand thereof slidably mounted on said supporting members and the idle strand thereof returning through said tunnel beneath said supporting members, so as to become preheated through proximity with the ware, and means located adjacent to the receiving end of the tunnel and beneath the idle strandof said conveyor for heating said tunnel and for augmenting the preheating of the idle strand of said conveyor immediately prior to its active or ware bearing travel through the tunnel.

6. A lehr for annealing glassware, comprising a rigid base structure, a tunnel conheated at intervals with the base structure, and expansion joints in the tunnel walls between the connections.

7. A tunnel lehr for annealing glassware, comprising a lining of insufiicient rigidity to be self sustaining when the lehr is heated during its operation, heat insulating material thereabout, and an outer rigid support maintained relatively cool by said heat insulating material. 7

8. A tunnel lehr for annealing glassware,

' comprising a lining of insufiicient rigidity to be self sustaining when the lehr is heated during its operation, heat insulating material thereabout, rigid supporting members extending longitudinally of said tunnel and maintained relatively cool by said insulating material, and means disposed at intervals longitudinally of said tunnel for supporting said lining from said supporting members.

9. A lehr for annealing glassware, comprising a rigid supporting structure, a tunnel supported at intervals by said supporting structure, and means interposed between said tunnel and said supporting structure to provide for relative expansive movement of the 'tunnel parts and the supporting structure.

10. A tunnel lehr for annealing glassware, comprising a heat reflecting lining of insufiicient rigidity to be self-sustaining when the lehr is heated during its operation, heat insulating material thereabout, rigid supporting members extending longitudinally of said tunnel and maintained relatively cool by saidinsulating material, means disposed at intervals longitudinally of said tunnel for spacing said lining from said supporting members, and an endless open work conveyor passing through the tunnel and adapted to transport articles of glassware therethrough.

11. A lehr for annealing glassware, comprising a rigid supporting structure, a tunnel supported at intervals by said structure, means interposed between said tunnel and said supporting structure to provide for relative expansive movement of the tunnel and supporting structure, a ware conveyor pass-- ing through the tunnel, a plum-lit of supg orts for supporting the conveyor above the ottom of said tunnel, and expansion joints connecting said su ports.

SLifned at Hart 0rd, C0nn., this 17th day of a 1928.

VERGIL MULHOLLAND.

Images