US2275263A - Apparatus for and method of controlling drift in lehrs - Google Patents

Description

March 3, 1942. D. G. MERRILL APPARATUS FOR AND METHOD OF CONTROLLING DRIFT IN LEHRS Filed Oct. 5, 1938 2 Sheets-Sheet l gawwegizz' Z Z I fli iay'figgs March 3, 1942. D. G. MERRILL 2,275,263

APPARATUS FOR AND METHOD F CONTROLLING DRIFT IN LEI-IRS Filed Oct. 5, 19:58 2 Sheets-Sheet 2 [5 2 Donaid 6y w O O x Patented Mar. 3, 1942 APPARATUS FOR. AND METHOD OF CON- TROLLING DRIFT IN LEHRS Donald G. Merrill, West Hartford, Conn., assignor to Hartford-Empire Company, Hartford, Conn., a corporation of Delaware 1 Application October 5, 1938, Serial No. 233,427

18 Claims.

' This invention relates to apparatus for and methods of, controlling drift in lehrs.

In lehrs for annealing glassware, there is a tendency for air or tunnel atmosphere to move through the lehr tunnel in one direction or the other. While uncontrolled longitudinal currents of air in lehr tunnels are generally objectionable, it-may be desirable in many instances to have certain controllable currents of air flowing longitudinally of the lehr tunnel as an aid to controlling the temperature conditions and distribution of heat in the lehr tunnel.

Various types of drift controlling apparatus for lehrs have been proposed and some have been used more or less successfully. All of such types of drift controlling apparatus known to me are in general controlled by or responsive to the drift that exists in a lehr tunnel at any given time. I have discovered that it is advantageous in the operation of a tunnel lehr to control drift in such a lehr in accordance with departures of tudinal section of an intermediate section of a lehr of the general type disclosed in my co-pending application No. 66,611, filed March 2, 1936, as equipped with drift controlling apparatus of the present invention,

Fig. 2 is a relatively enlarged transverse vertical section through the upper portion of the lehr section shown in Fig. 1, -at a plane approximately that indicated by the lines 2-2 of Fig. 1,

Fig. 3 is a fragmentary still further enlarged vertical section substantially along the line 33 of Fig. 2,

Fig. 4 is a relatively enlarged view of the parts of the drift controlling mechanism at the left hand side of the portion of the lehr shown in Fig. 2, the view being mainly in side elevation with a casing that-houses'parts of the mechatemperature from a predetermined temperature at a selected control point inthe lehr and a primary object of the present invention is to provide apparatus for and a method of carrying this discovery into effect.

A further object of the invention is to provide eflicient and reliable mechanism, responsive to temperature changes at a control point in the lehr, for producing a sensitive, flexible andcomprehensivecontrol of drift in the lehr.

A still further object of the invention is to provide a drift controlling mechanism which will act automatically in response-to changes of temperature from a predetermined temperature at a control point in the lehr to establish and maintain desirable drift conditionstherein without requiring manual control after the operation thereof has been initiated.

A further object of the invention is the provision in a drift controlling mechanism of the general type that is disclosed in Patent No.

2,106,678, granted to me January'25, 1938, for

cuits of a reversible electric motor that is included in such apparatus.

Other objects and advantages'of the invention I will hereinafter be pointed out or will become apparent from the following description of illustrative practical embodiments of the invention,

as shown in the accompanying. drawings, in

which Fig. 1 isa view principally in vertical longinism being partially broken away and partially shown in vertical section,

- Fig. 5 is a horizontal section along the line of 5-5'of Fig. 4, Fig. 6 is a similar section at a higherlevel, be-

ing approximately along the line 6-6 of Fig. 4,

Fig. 7 is a diagrammatic view of the drift controlling apparatus of the present invention with the exception of the temperature responsive device that is located at a control point in the lehr, '30

- showing motor driven motion transmitting mechanism of the .drift controlling apparatus of the form shown in Fig. 9. v

A lehr towhich the invention may be applied is partly shown in Fig. 1 and has a tunnel I through which glassware to be annealed may be transported by the upper or ware bearing strand of a suitable open-work conveyor 2, the lower or idle strand of which is returned beneath the lehr to the entrance end of the lehr tunnel. This particular lehr may be constructed as fully disclosed in my co-pending application, Serial No. 66,611, above referred to, and is of the direct fired and direct cooled type although the use of thepresent invention is not restricted to such a ,lehr.

For supplying heat to the tunnel of a lehr of the type partially shown in Fig. 1, a number of burner groups or units, one of which is indi cated at 3, may be employed.

Cooling air may be introduced into the cooling portion of such tunnel by suitable pipes which may extend longitudinally of the cooling portion of the tunnel in the upper corners thereof. One of these pipes is shown at 4 in Fig. 1. This pipe has spaced nozzles 5 which may be directed toward the longitudinal median line of the tunnel above the path of the ware on the conveyor 2. The jets of air from these nozzles may be defiected downwardly in whole or in part, by the inclined sides of deflectors 6 which are located in the upper portion of the cooling section of the ware tunnel, intermediate the sides thereof. The upper portions of the sides of these deflectors 6 or of some of them may comprise hinged sections or dampers, designated 1. As illustrated to advantage in Fig. 7, each damper 1 is provided with a rigid arm 8 which is operatively connected by a link 9 with a crank arm ID on an axle ll. As shown in Figs. 1 and 8, each link 9 extends through a suitable opening in the roof of the lehr tunnel so that, as shown in Fig. 1, the crank arms ID, the axles H and a suitable operating mechanism therefor are disposed above and'outside of the lehr tunnel. As shown (see Figs. 1 and '7), the axles ll may carry sprockets l2 and the entire series of sprockets may be rotated in unison by a chain I3 which is trained around all these sprockets; One of the axles Il may be rocked about its axis, as by means of an operating arm I4, so as to actuate the chain I3 and transmit motion to all the axles. It of course will be understood that the axles ll may be connected with the dampers at both of the opposite sides of the upper portion of the cooling section of the lehr tunnel. It also will be understood that any known expedient may be employed to permit or cause different movements of the respective dampers in response to a given rotary movement of the control axle. However, as shown, the dampers 7 will all be'moved in unison to the same extent and in the same direction when the control axle l I is rocked about its axis by a movement of the operating arm l4 so that all of these dampers will be given simultaneous opening or closing movements according to the direction of rotation of the control axle.

The cooling air discharged into the tunnel by air to the lehr tunnel may be substantially as disclosed in my aforesaid application, Serial No.

parts located in the upper part of the lehr tunnel at a place preferably between the heated and cooling sections of the lehr tunnel, substantially as disclosed in my aforesaid Patent No, 2,106,- 678. However, instead of the particular thermostatic drift responsive device shown and described in Patent No. 2,106,678, I prefer to employ an im-' provement thereover having structural details shown in the accompanying drawings and a mode of operation which will hereinafter be described.

As shown in Figs. 2, 3, 6 and 7, the thermostatic drift responsive device comprises a pipe 2| which is disposed transversely of the upper part of the lehr tunnel and is supported so that it may be rocked about its own axis. The pipe 2| may be supported by bearings in suitable hangers 22 which are carried by a cross bar 23, Fig. 2, which in turn may be supported in place at the top of The operation of the control axle H to effect simultaneous opening or closing movements of the dampers 1 may be effected by the operation of a reversible motor l1, Figs. 1 and 7, the driven shaft of which may be provided with a crank arm la'connected by a suitable link l9'with the axle operating arm I 4. The reversible motor I! may be of any suitable known construction and mode of operation and therefore has been shown only diagrammatically. This motor may be controlled by a thermostatic drift responsive device, generally designated 20, which includes the lehr tunnel, as by the fastening devices 24, Figs. 2 and 3. The pipe 2| may be closed at one end while the opposite end portion thereof e'xtends through a suitable opening 25, Fig, 2, in a side wall of the lehr tunnel and is there provided with a downwardly turned substantially vertical end portion or extension 21 which constitutes a handle or actuator by which the pipe 2| within the lehr tunnel maybe rocked about its axis in its bearings in the hangers 22. The part 27 may be connected with a suitable flexible air supply pipe 28.

The pipe 2|, within the tunnel, may be provided at its upper side with a discharge outlet which may comprise a series of aligned elongate openings or slits 29, Fig. 2, each of which may be substantially as shown in Fig. '7. Such outlet might comprise one continuous slit extending for the desired part of the length of the pipe 2| or may comprisea greater number of openings. The arrangement preferably is such that a substantially continuous thin sheet of air or other suitable gaseous medium may be discharged vertically upward in a plane that extends transversely of the lehr tunnel when the pipe 2| is in the angular position shown in' the drawings and such sheet of air or other gaseous medium may be discharged upwardly in a plane inclined from the vertical at either side thereof when the pipe 2| is rocked about its axis in one direction or the other from the position shown in the drawings. The air supply pipe 28 may be equipped with a suitable valve (not shown) The angular position of the pipe 2| may be adjusted by a bell crank lever 30, Fig, 5, having a forked end portion 3| embracing the downbracket 31, Figs. 2 and 4, within a casing 38 which is secured to one side of the lehr tunnel so as to house the outer portion of the pipe 2| and its downwardly turned handle 21. The bracket 31 may carry an upstanding stud or pivot pin 39, Figs. 4 and 5, on which the bell crank is fulcrumed, the arrangement being -such that when the traveling nut 32 is moved along the shaft 33, the handle 21 will be rocked one way or the other about the axis of the pipe 2| and turn the latter angularly about such axis. The shaft 33 may be rotated to cause movement of the traveling nut 32 by a hand wheel on the outer end of such shaft.

The bracket 31 may support a plate 4| which in turn carries an upstanding tubular bearing 4|-a in which a vertically disposed short shaft or stud 42' is rotatably supported. The shaft 42 carries a spool 43. Another spool, indicated at. 44, is located at the opposite side of the lehr tunnel in a suitable casing 45, being supported non-rotatably by a substantially vertical stud 46 which extends upwardly from the hub of a verticaliy swingable bell crank lever 41. The bell crank lever 41 is pivoted at 48 on a horizontal pivot pin that is carried by a bracket 49 within the casing 45 so that an outwardly extending arm 50 of the bell crank may be urged continuously downward by a tension spring Tiers 52 and 53 of substantially horizontal expansible and contractile wires extend through the upper part of the lehr tunnel above the level of the pipe 2| and at approximately equal distances from the vertical plane passing through the center of that pipe, as best seen in Figs. 3, 6 and 7, considered together. These tiers of wires constitute cooperative temperature responsive members for imparting rotary movement to the spool 43 when there is a difference in temperature conditions effective on the respective tiers. They may be provided by attaching one end of a single wire of expansible and contractile material to the spool 44, as at 54 and then stretching the wire transversely through the lehr tunnel to the spool 43, around the latter and back to spool 44, and thus back and forth between the spools until the desired number of reaches of the single wire have been provided in each of the tiers 52 and'53, the second end of the single wire then being fastened to a lower portion of the spool 44, as at 55. The spools 43 and 44 may be grooved to maintain the separate wires of each tier in spaced relation and corresponding wires of the respective tiers parallel and at the same level. The arrangement is such that the tiers of wires between the spools will at all times be maintained taut by the action of the spring 5| and so that the spool 43 will be rocked about its axis in one direction or the other whenever one of the tiers of wires expands or contracts more than the other.

A compressed spring 56, Figs. 2 and 4, on the upper part of the shaft 42 presses the hub of a switch arm 57 against the upper end of the spool 43 so that the switch arm will be oscillated about IT, to which they are connected by Wires 6| and 62 as best seen in Fig. 7. The motor I1 is provided with a lead Wire 63 and the switches 60 and Gil-a have lead wires 63a and 63-h, respectively. When the switch arm 51 has actuated contact 58 to close switch 60, a motor operating circuit will be provided to cause the motor shaft to be rotated in one direction. Rotation of the motor shaft in the opposite direction will take place when the switch arm 51 has actuated the contact 59 to close the switch 69a. Adjustable stop screws 64 and 64-a may be provided to limit the throw of the switch arm-51 in its swinging transversely movements toward the contacts 58 and 59 of the respective switches 60 and 60a or either of ments 64 and 64-a of the switches 60 and 60a or by either of these adjustments is believed to have been pointed out or sufficiently indicated by the detailed description and explanation of the mode of operation and capabilities of the specifically different apparatus of the disclosure of my Patent No. 2,106,678. The, present invention, however, contemplates automatic adjustment of the drift respective motor operating mechanism in response to changes of temperature from a predetermined temperature at a control point in the lehr tunnel.

As shown in Fig. 1, a thermostat 65 which may be of the'bi-metallic type of construction, depends through the roof of the lehr tunnel at a selected control point and is provided'at its upper end with a contact 66 forjcooperation at different times with adjustably spaced contacts 61 and 68, respectively. The contacts 61 and 68 are connected by wires 69 and 10 with opposite sides of a reversible motor Figs. 1-, 2 and 4. A lead wire 12 is connected with the thermostat 65 and another lead wire 13 is provided for the motor I.

-motor H in the direction required to adjust the pipe 2| angularly about its .axis so that the sheet of air therefrom will be turned angularly in one direction about the axis of the pipe 2| The motor 1| will be operated to turn the pipe 2| in the reverse direction when the temperature to which the thermostat 65 is subjected falls below the predetermined temperature and the sheet of air from the pipe 2| will then be turned in the opposite direction about the axis of the pipe 2|.

In practice, let it be assumed that the angular position of the pipe 2| has been adjusted manually to set up and maintain a predetermined drift condition in the lehr tunnel so that, with a given loading of the lehr conveyor and given service conditions, the temperature at the thermostat 65 will be as desired. This drift condition may be a zero drift or a certain predetermined drift or movement of the tunnel atmosphere in one direction or the other, as explained in detail in my Patent No. 2,106,678. Then, if the rate of loading should be increased or the service conditions should change so that more heat would be carried in the lehr tunnel further toward the rear or exit end thereof,the temperatureat the control point at which the thermostat 65 is located would be increased. The motor would ire operated to effect a corrective angular adjustment of the pipe 2| which wouldbe' effective in the manner explained in Patent No. 2,106,678 to produce closing movements of the dampers I. Consequently, pressure will build up in the cooling section of the lehr sufficiently to resist or retard the forward movement of heat in the lehr tunnel;

The temperature at the control point at which the thermostat is located may thus be reduced to the temperature desired.

On the other hand if the rate of loading should be reduced or the service conditions should change so as to cause the temperature at the control point to fall below the predetermined temperature atiwhich the thermostat 65 is set, the motor H would be turned in the opposite direction to angularly adjust the pipe 2| as required to efiect opening movements of the damp ers I. This would permit egress of more air from the tunnel through the outlets which the dampers 1 control and would reduce the pressure in the cooling section of the lehr so that the heat would be carried or permitted to move further toward the rear or exit end of the tunnel. In consequence, the temperature at the control point would rise to the predetermined temperature desired.

It will be understood that a series of small adjustments of the dampers in either or both directions may be made to produce the result desired. The longitudinal distribution of temperature or heat gradient in the lehr tunnel may thus be maintained as desired better than has been possible by the aid of prior drift controlling apparatus. While the control point for the thermostat 65 preferably is located in a portion of the lehr tunnel intermediate the heated and cooling sections thereof, such control point may be device, such as that disclosed in' my Patent No.

2,106,678. As shown in Fig. 8, the control device comprising the thermostat 65, the flexible thermostatically actuated contact 65 and the adjustably spaced contacts 61 and 68 is connected directly with the motor I! instead of through the lntermediacy of the drift responsive thermostatic device 20 of the Fig. 1 form of construction. As shown in Fig. 8, the contacts 6'! and 68 are connected by wires I 69 and H0, respectively, with the opposite sides of the motor H. The latter also is provided with a lead wire I63.

Whenever, in operation of the apparatus of the Fig. 8 form of construction, the temperature at the control point rises above a predetermined temperature at which'the thermostat 65 is set, the motor I! will be actuated to effect closing movements of the dampers which that motor controls, as in the operation of the Fig. 1 form of construction. Likewise when the temperature at the control point falls below the predetermined temperature, the motor I"! will be operated to effect opening movements of the dampers. The results will be to build up pressure and resist rearward movement of heat on increase of the temperatureat the control point and to lower pressure and permit further rearward movement of heat on decrease of temperature at the control point so that, in each instance, a corrective adjustment of drift and of the longitudinal distribution of temperature or heat gradient in the lehr will be effected.

In Figs. 9 and 10, another form of construction contemplated by the invention is shown. In that form, a motor H! has its driven shaft H8 operatively connected witha crank disk IN. This crank disk carries a crank pin connected by a link H9 with an actuating arm H4 on one of the axles II.. It will be understood that a series of the axles ll may be provided, each carrying a gear l2 and each connected by motion transmitting elements with one of the dampers I as previously described. The gears [2 may all be actuated in unison by the chain l3 as also previously explained. This form of construction includes means for supplementing and extending the drift controlling effects of the dampers I. For example, it may be desirable in some instances to produce a still further forward drift in the lehr tunnel after all the dampers have been closed. This desirable result can be effected with the construction shown in Figs. 9 and 10 by virtue of an adjustment of the damper H5 in the air supply pipe l5 to which air is supplied under pressure, as from a blower fan.

The adjustment of the damper I6 is effected by mechanism actuatedfrom the crank disk I14. As shown, a wrist pin H5 is provided on the crank disk I14 near its periphery and at a predetermined angularly spaced distance from the connection of the link H9 with such crank disk. A gear I16 is mounted to turn freely on the pin I15 and is in mesh with a non-rotatable gear 11 that is supported by a suitable support -l8 in a fixed position, co-axial with the crank disk I14. The gear 76 has an eccentric connection at 19 with one end of a link 80. The link 80 has its other end operativ-ely connected with an actuating arm 8| for adjusting the position of the damper IS in the pipe 15. The link 80 is adjustable as to length, as by means of the turnbuckle 80a which constitutes a part thereof, so that a manual adjustment of the damper l6 can be'made independently of the action of the motor operated damper-actuating mechanism and so that the portion of the complete range of adjustment of the damper I6 that will be controlled by the motor driven mechanism may be selected at will.

The motor ll! may be controlled from a thermostat 65, either directly as in the Fig. 8 form of construction or through an intermediate thermostatic drift responsive device 20 as in the form of construction shown in Fig. 1. The extreme travel of the crank disk I14 is through degrees. The gears I76 and I! may be of the same diameter. The point of location of the pin I15 on the crank disk is so angularly related to the point of attachment of the link H9 to that crank disk and the relationship and coaction of the parts just described are such that the link H9 will be moved rapidly through the middle part of its stroke and slowly at the ends thereof while the longitudinal movement of the link 80 will be relatively rapid at the ends of its stroke and practically zero at the middle portion thereof. In consequence, intermediate adjustments of pressure and drift conditions in the lehr tunnel are effected mainly by the adjustments of the dampers 1 and extreme adjustments of pressure and drift conditions are effected mainly by the adjustment of the damper l6. Adjustment of the damper l6 varies the volume of air supplied through the pipe l5 to the nozzles 5 and thus provides a way of securing a greater range of control of the drift conditions in the lehr tunnel than could be obtained by the adjustment of the dampers I alone.

The expression temperature ata control point in the lehr tunnel as used in the foregoing specification and in the appended claims, is to be understood. as broad enough to include the average temperature at a predetermined transverse Outlets.

section of the lehr tunnel or any predetermined part thereof, a such temperature is indicated by any appropriate known form of thermostatic device.

The invention is not restricted to the illustrative embodiments thereof shown in the accompanying-drawings and particularly described herein or to the operations of such embodiments but instead extends to all combinations of structural elements and method steps that fairly fallwithin the scope of the appended claims.

I claim:

-1. Drift controlling apparatus for lehrs having tunnels and means for conveying ware to be annealed through said tunnels, comprising adjustable means for controlling drift of the atmosphere within the tunnel of such a lehr and means responsive to departures of temperature from a predetermined temperature at a predetermined control point in the lehr tunnel for regulably controlling said adjustable means.

2. Drift controlling. apparatus for lehrs having tunnels and means for conveying ware to be annealed throughsaid tunne1s,-comprising adjustable means for varying the effective pressure of the atmosphere in a portion of the tunnel of such a lehr to vary the drift of the atmosphere in said tunnel, and means responsive to variations of temperature from a predetermined temperature at a predetermined control point in said lehr tunnel for regulably controlling the operation of said adjustable means.

3. Drift controlling apparatus comprising a dampered gaseous medium conducting member in communication with a portion'of a lehr tunnel for regulably controlling drift of the atmosphere in said tunnel, means for conveying the ware to be annealed through said tunnel, and means acting automatically in response to variations of temperature from a predetermined temperature at a control point in said lehr tunnel for controlling said dampered member to vary the drift controlling efiect thereof.

4. Driftcontrolling apparatus for a tunnel lehr comprising means for discharging a gaseous me,- dium into a portion of said tunnel, means for conveying the ware to be annealed through said tunnel, means providing an outlet for the escape of gaseous medium from said tunnel, a damper controlling said outlet, and means operable automatically in response to variations of temperature from a predetermined temperature at a control-point in the'lehr tunnel for adjusting said damper.

5. The combination with a tunnel lehr of means for discharging air into a cooling section of the tunnel of said lehr, means for conveying .the ware to be annealed through said tunnel,

' means providing a series .of air outlets in said means actuated by said temperahire responsive means in response to variations of temperature from a predetermined temperature at said control point for adjusting said dampers to ,vary the volume of air permitted to escape through said 6. The combination with a tunnel lehr having a plurality of spaced outlets in the cooling section of the tunnel thereof for the escape of tunnel atmosphere, means for conveying the ware to be annealed through said tunnel, means for discharging air into the cooling section of said lehr tunnel, dampers controlling said outlets, op-

erating mechanism for said dampers, including a reversible motor, a thermostat located in said lets in the cooling section of the lehr for the escape of tunnel atmosphere, dampers controlling said outlets, a reversible'motor, operating mechanism connecting said motor with said dampers for operating all of them in unison, a thermostat located'in the tunnel of said lehr at a predetermined control point, and electrical conducting means controlled by "said thermostat for operating said reversible motor to adjust said dampers in one direction when the temperature at said control point exceeds a predetermined temperature and to adjust said dampers in the opposite direction when the temperature at said control point falls below said predetermined temperature.

8. The combination with a. tunnel lehr having a heated tunnel section and a cooling tunnel section, means for conveying the ware to be annealed through said tunnel, nozzles spaced longitudinally of the cooling section for discharging air into said cooling section, deflectors. spaced lon-. gitudinally of said cooling section and provided with outlets for the escape of tunnel atmosphere, dampers controlling .said outlets, a reversible ,motor, operating connections between said motor the temperature at said control point falls below said predetermined temperature.

9. The combination with a tunnel lehr having a cooling section and a heated section and an intermediate section between said cooling and heated sections, means for discharging a gaseous medium into said cooling section, means providing an outlet in said cooling section for the venting of part of said gaseous medium, a damper controlling said outlet, a reversible motor operatively connected to said damper for operating it, a thermostatic drift responsive device lo-. cated in said intermediate section of said tun-'v nel, electrical means connecting said thermostatic drift responsive device and said reversible motor to cause said motor to be controlled from said thermostatic drift responsive device, and means ,responsive to variations of temperature from a predetermined temperature at a control point in said lehr tunnel for regulably controlling the operation of said thermostatic drift responsive device.

10. Drift controlling apparatus for tunnel lehrs, comprising adjustable vmeans for is discharging a gaseous medium into a lehr tunnel in a plane extending substantially transverse thereof, a pair of temperature responsive devices located adjacent to said plane anti respectively forwardly and rearwardly thereof, means for adjusting the means for dischargingsaid gaseous ,medium into said tunnel to vary the relative distances between the plane in which said gaseous medium is discharged and said temperature responsive devices, means controlled by said temperature'responsive devices for controlling drift of atmosphere in said lehr tunnel, and means responsive to variations of temperature from a predetermined temperture at a predetermined control point in said tunnel automatically to actuate the means for adjusting said means for introducing said gaseous medium into the lehr tunnel. I

11. In a drift control apparatus for tunnel lehrs, a substantially horizontal rotatably mounted pipe extending transversely of the lehr tunnel and having an outlet at its top for discharging a gaseous medium in a generally upward direction in said tunnel, tiers of expansible and contractile wires adjacent to and above the level of said pipe and respectively located 'fore and aft thereof, spools at the sides of said tunnel supporting said tiers at the ends thereof, one of said spools being rotatable and engaged by said tiers of wires so as to be rotated in either of opposite directions about its own axis according to the temperature difierentials between said tiers of wires, a pair of, normally open switches adjacent to said rotatable spool, a pivoted arm arranged to be oscillated by said rotatable spool for closing one of said switches when said rotatable spool is rotated in one direction and for closing the other of said switches when the ro-' tatable spool is rotated in the reverse direction, and means controlled by said switches for controlling the drift'of atmosphere in said tunnel.

12. Drift controlling apparatus for a tunnel lehr comprising means for discharging a gaseous medium into a portion of the lehr tunnel, means for conveying the ware to be annealed through said tunnel, an outlet in said portion of the tunnel for the escape cg gaseous medium, a damper controlling said outlet, a damper controlling the means for discharging the said gaseous medium into said tunnel, and means responsive to variations of temperature from a predetermined temperature at a predetermined control point in said lehr tunnel for adjusting both said dampers.

13. Drift controlling apparatus for a tunnel lehr comprising means for discharging a gaseous medium into a portion of the lehr tunnel,

means for conveying the ware to be annealed through said tunnel, an outlet in said portion of the tunnel for the escape of gaseous medium, a damper controlling said outlet, a damper controlling the means for discharging said gaseous medium into said tunnel, and means responsive to variations of temperature from a predetermined temperature at a predetermined control point in said lehr tunnel for adjusting both said dampers to vary the pressure and hence the drift in said tunnel, said last named means including operating mechanism so constructed and arranged as to effect differential adjustments of said dampers in response to any given variation of temperature from said predetermined temperature at said control point.

14. In a drift controlling apparatus for lehrs, an adjustable intake damper controlling the inflow of a gaseous medium to a portion of a lehr tunnel, an adjustable exhaust damper for controlling venting of gaseous medium from said portion of the tunnel, a reversible motor, a crank disk arranged to be driven by the motor, a separetely rotatable gear carried by said crank disk eccentrically of the latter, a fixed non-rotatable gear co-axial with said crank disk and in mesh with said rotatable gear, a link connecting the crank disk with the exhaust damper, another link connecting said rotatable gear with said intake damper, said second named link being adjustable to permit pre-setting of the range of adjustment of the intake damper by the throw of its link, said links being so actuated by the rotary movement of said crank disk and the consequent movements of said rotatable gear that the link connected with the exhaust damper will be moved rapidly through the middle part and slowly at the ends of each stroke thereof while the link connected with the intake damper will be moved rapidly at the ends and slowly at the middle portion of each stroke thereof, and means responsive to variations of temperature from a predetermined temperature at a predetermined control point in the lehr tunnel for operating said reversible motor.

15. The method of controlling drift in a tunnel lehr having a tunnel-comprising a heated section and a cooling section and through which the ware to be annealed is passed, which comprises varying the pressure in the cooling section of the lehr tunnel in accordance with variations of temperature from a predetermined temperature at a control point in the lehr tunnel.

16. The method of controlling drift in a tunnel lehr having a tunnel comprising a heated section and a cooling section and through which the ware to be annealed is passed, which comprises introducing a gaseous medium into the cooling section of the lehr tunnel, removing gaseous medium in regulably controlled amount from said cooling section of the'lehr tunnel, and varying the amount of gaseous medium removed to vary the pressure in the cooling section of the lehr in accordance with variations from a predetermined temperature at a control point in the lehr tunnel.

17. The method of controlling drift in a tunnel lehr having a tunnel comprising a heated section and a cooling section and through which the ware to be annealed is passed, which comprises discharging air into the cooling section of the lehr tunnel at a plurality of places spaced longitudinally of said cooling section, venting air from said cooling section at a plurality of places spaced along the length thereof, increasing the amount of air thus vented in relation to the air supplied to the cooling section of the lehr tunnel when the temperature in the lehr tunnel at a control point in advance of said cooling section falls below a predetermined temperature and decreasing the amount of air vented from the cooling section in relation to the amount of air supplied thereto when the temperature at said control point rises above said predetermined temperature.

I 18. The method of operating a tunnel lehr having a tunnel comprising a heated section and a cooling section and through which ,the Ware to be annealed is passed, and having means operable-,to produce a predetermined drift of regulable amount and extent in either of opposite directions in the lehr tunnel, which consists in controlling the operation of said drift-producing means in accordance with variations of temperature from a predetermined desirable temperature at a predetermined control point in the lehr tunnel.

. DONALD G, MERRILL.

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