US2409431A - Heating work - Google Patents

Description

Oct. 15, 1946.

o. HESS 2,409,431

HEATING wonx Filed Aug. 31, 1942 I 2 Sheets-Sheet 1 a x N R w a Q3 a I gggllllllllll/ A TTORNEY V F. O. HESS HEATING WORK File d Aug. 31. 1942 2 Sheets-Sheet 2 N INVENTOR I R: fiPwf/P/c 0. 6 565 ATTORNEY Patented Oct. 15, 1946 HEATING WORK Frederic 0. Hess, Germantown, Pa., assignor to Selas Corporation of America, a corporation of Pennsylvania Application August 31, 1942, Serial No. 456,787

23 Claims.

The general object of the present invention is to provide improvements in. heating work, and, although not to be limited thereto, is especially useful in the manufacture of tin plate. More specifically, the primary object of the invention is to provide a novel and effective method of, and novel and effective means for hot finishing tin plate stock in the form of a thin strip coated with electrolytically deposited tin while the strip is travelling at high speed through a finishing station,

In the manufacture of tin plates it has been found that when plate stock is coated with electrolytically deposited tin and is subsequently subjected to a suitable finishing treatment, the tin coating required for a given use of the finished plates made from the stock may be substantially thinner than has been found necessary in manufacturing tincplates for the same use, from stock plates coated by dipping them in a bath of molten tin as has been customary heretofore. The reduction in the thickness of the tin coating made possible by depositin the tin electrolytically on the plate stock, is strikingly large and results in a reduction of about 70% in the coating tin, per unit of area coated, in the manufacture of tin plates for ordinary uses.

Furthermore, the manufacture of tin plates from electrolytically plated stock can be carried on more rapidly and with a lower labor cost than i has been practically possible in the manufacture of tin plates from dip coated stock plates. The advantages last mentioned result largely from the fact that it is practically feasible to coat plate stock in strip form by moving it continuously through an elongated electrolytic coating bath and that it has not been found practically feasible to satisfactorily coat such strip material by moving it through a molten tin coating bath. Heretofore, tin plate stock has customarily been coated by the essentially intermittent process of moving the stock in" the formfof relatively short pieces or plates, quickly down into andthen up out of a molten tin bath. The hot finishing proc use which I have devised is a continuous process which can be carried out rapidly and at a relatively small expense. 1 i

A thin coating of tin electrolytically deposited on tin plate stock is initially'in a porous condition and to fit such stockfor'the uses to which tin plates are customarily put, the coating pores must be closed. It'has heretofore been found that the coating pores can be closedand that the coating can be smoothed and given a glossy finish andmade to adhere better to the steel strip body by a heat treatment which melts or fuses the tin, but as far as I am aware, no practically satisfactory method had been devised, prior to my invention, for giving the above described hot treatment to strip material moving continuously past the finishing station at a high but varying speed.

My present invention was devised with the specific object in View of providing a practically effective method and practically effective apparatus for subjecting tin plate strip stock to the above described heat treatment while said stock is moving through a finishing station at a speed varying from a maximum which may be as high as 800 feet per minute or higher, and a minimum which may be as low as or 200 feet per minute, and my invention is characterized by the adjustment toward and away from such strip or other work in automatic response to increasesand decreasesin the strip speed, of a heat source, such as refractory heating walls for example, which are maintained at a temperature much above the melting temperature of tin. In so adjusting the position of the heat source with repect to the work, the heat source is preferably moved through distances functionally related to changes in the rate of movement of the work. By thus varying the distance between the heating walls and the strip, I am able to varythe rate at which heat is transmitted from the heating walls to the traveling strip through the wide range and in the rapid manner necessary toheat the strip material with suitable uniformity notwithstanding wide and rapid variations in the speed at which the strip moves through the'treating station. Ordinarily, the speed at which the strip material is moved through the finishing station may be expected to vary widely and rapidly as result of operating conditions in the continuous strip mill from which the tin plate stock passes to the finishing station.

"The apparatus which I have devised comprises a'pair of burner walls of ceramic material at opposite sides of the traveling plate stock strip and in each of which a multiplicity of suitable burners are incorporated. Burners of a type well adapted forsuch use are disclosed in my prior Patent No. 2,215,079 of September 17,1940. Such burners, commonly knownas Duradiant burners, are now in extensive use as furnace wall burners and for other purposes. The Duradiant type of burner shown by said patent is characterized by its shallow cup-like combustion chamber formed'i'n a ceramicumaterial body, and by the provisionsmade for supplying a. combustible mixture of air and gas to the combustion chamber,

in such manner as to effect the complete combustion of the mixture within the combustion chamber, and the maintenance of relatively high combustion chamber temperatures so that a major portion of the heat liberated may be radiated away from the combustion chamber through its open end.

In the ordinary use of the present invention, I contemplate that each burner wall will be wide enough to extend beyond the side edges of the traveling stock strip, which ordinarily will be 2 or 2 feet wide, and that each wall will extend alongside the strip in the direction of its length for 2 or 3 feet or so, and that in normal operation each burner wall will be spaced away from the strip, a distance varying between a minimum of one inch or so and a maximum of several inches as the speed at which the work strip is moved through the space between the two burner walls is increased and decreased.

The considerable areal extent of the burner wall and the high burner combustion chambers maintained, ordinarily about 24.00" F., makes it possible for the burner walls to transmit heat rapidly enough to melt the tin coatings on the opposite sides of the traveling sheet when traveling at a speed as high as 800 feet per minute or higher, although the melting temperature of the tin is about 450 F., and only a small fraction of a second will then be required for the movement of a point on the surface of the tin strip through the space between the burner walls.

In its preferred form my invention comprises means not only effective to automatically move the burner walls toward and away from the travelling work strip, as the speed of the latter increases and decreases through a normal regulation range in which the rate of heat transmission to the work strip will be proportional to its speed past the burner walls, but also effective to give the burner walls rapid and substantial safety movements away from the work strip in the event of an interruption of, or radical reduction in the work strip speed. The means employed for giving the burner walls their above mentioned regulating. and safety movements may take various forms. In a preferred form of the invention those movements are gravitationally produced and are regulated by a hydraulic cylinder controlled by a valve which is actuated to vary the liquid pressure in the cylinder in automatic response to changes in the work strip speed of travel.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, however, its advantages and specific objects attained with its use, reference should be had to the accompanying drawings and descriptive matter in which I have diagrammatically illustrated a preferred embodiment of the present invention.

Of the drawings:

Fig. 1 is a diagrammatic elevation of a desirable form of hot finishing apparatus;

Fig. 2 is a plan view of the portion of the apparatus shown in Fig. 1; and

Fig. 3 is a sectional elevation of a control valve.

In the embodiment of the invention illustrated diagrammatically in the drawings, the tinned plate stock strip A is hot finished as it is being rapidly moved by feed rolls C through a vertical path extending between the feed rolls C and guide rolls B, by the heating action of vertical burner walls D and DA at opposite sides of said path. The wall D is mounted on a truck or carriage E having supporting wheels E on rails F.

The rails F are mounted on an inclined support 5 F and extend away from the path of movement of the strip A, and are downwardly inclined, so that the truck or carriage E has a gravitational bias for movement along the rails F, which will increase the horizontal distance between the burner wall D and the strip A.

The burner wall DA is like the burner wall D, and its supporting carriage EA is similar in form and in the manner in which it is supported, to the carriage E. Further the burners, fuel mixture supply connections, and other parts associated with the burner wall D and carriage E, as hereinafter described, are duplicates of parts associated with the burner wall DA and carriage EA. In consequence the following description of the burner wall D, its burners and burner supply connections, will make it unnecessary to separately describe the burner wall DA, its burners and connections.

As shown, the burner wall D comprises ceramic burner blocks d which may be shaped and assembled edge to edge as they are in a furnace wall arrangement shown in said prior patent, but the burners may be spaced apart or grouped in any manner which conditions make desirable. Each of the burner blocks d is formed with a central horizontal inlet passage 11' which terminates at the side of the burner wall adjacent the strip A in a shallow cup-shaped combustion chamber d coaxial with the passages d and open at its end adjacent the strip A. As shown, the burner blocks (1 in each of the different horizontal rows of the burner wall have their inlet passages d connected to a corresponding horizontal manifold G. The flow capacity of the manifold connection to each burner passage d may be independently regulated in a known manner as by means of a corresponding adjustable needle valve throttling element d accessible for adjustment at the side of the manifold remote from the burner 5 wall D.

Each of the superposed manifolds G associated with the burner wall D is connected by an individual regulating valve G to a vertically disposed drum G mounted on the truck E. A combustible mixture of air and gas is supplied at suitable pressure to the drum G from a stationary mixture supply main H through an adjacent flexible pipe connection H.

In the form of the invention diagrammatically shown, the distance between each of the burner walls D and DA and the adjacent side of the work strip A is directly controlled by a servomotor J in the form of a hydraulic cylinder having its piston J cable connected to each of the carriages ortrucks E and EA. As shown, the cylinder J is vertically disposed with its upper end open and with a passage through its lower closed end through which the stem J of the piston J extends. The lower end of the piston stem J is connected to one end of a cable K which extends about a guide pulley L, turning about a stationary axis beneath the cylinder J. The end of the cable K remote from the cylinder J is connected to an equalizing bar K midway between the ends of the latter, as shown mast clearly in Fig. 2. The two ends of the bar K are similarly connected to the carriages E and EA at the opposite sides of the latter. The connection between each end of the bar K and each carriage at thecorresponding side of the latter, comprises a cable K connected to the end of the bar K and extending under. and thence upward away frame pulley LA which is sod isposed that the uprising-end of the cable K is alongside the-corresponding edge of the vertical portion of the work strip moving upward between the burner wane. Theuprisi-ng end of each of the two cables K is connected to the carriages E and EA by corresponding cables M and MA, respectively.

Each cable M extends over-a guide pulley N mounted on the corresponding carriage support F; From its guide pulley N, each cable M passes in a generally horizontal direction toward the rear end of the truck E t'o-whichit is connected by a pin E Each cable MA runs over a corresponding pulley NA mounted on the support F for the carriage EA and is connected to the latter just as the cable M is connected to the carriage E. As shown, each of the cables M and MA ineludes a turnbuckle M which may be adjusted to vary-the distance between the corresponding burner'wall and the work strip maintained in normal operation.

The gravitational bias of each of the carriages E and EA for movement downward and away from the work strip A along its supporting rails F, tends to maintain the cables K, K M and MA taut at all times, and insures suitably rapid movement of each burner wall along its supporting track rails F away from the work strip A inder J and under sufficient pressure to counter-balance the forces acting downwardly on the piston. Those forces comprise the pull of the cable K, the gravitational bias due to the weight of the piston J and its stem J and a loading force due to the action of a spring J acting between the piston J and a cross head J adjustably secured. to the cylinder J by bolts J The maximum distance the spring J can expand or elongate is fixed by a retaining bolt J 6 in threaded engagement with the head J and acting between the latter and a bell shaped spring follower J interposed betweenthe spring J and the piston J. The portionof the cylinder J above the piston J is freely open to the external atmosphere through portsJ In the arrangement illustrated, liquid is sup-- plied to the cylinder J. by a pipe 0 from a source (not shown) of liquid under a suitable pressure, and the liquid escapes from the cylinder J through an outlet pipe P, when and as permitted by the adjustment .of a control Valve Q. In the arrangement shown, the supply pipe 0. is restricted at 0' so that the maximum rate of. flow through the pipe 0 will be small enough to permit the cylinder J. to empty rapidly when the Valve Q is wide open. I

In a manner hereinafter described, the valve Qis; adjusted automatically in accordance with variations in the speed of travel of the work strip A, to vary the oil pressure acting on the piston J, and thereby adjust the burner walls D andDA toward and away from the work strip Aand from one another through a small working range, as the speed of the strip A varies through a relatively small regulation range, and to permit a rapid and substantial down move- In the form ment of thepiston J when travel of the work strip A is interrupted or is substantially reduced in speed so that itis then desirable to move the burner walls D and DA far enough away from the work strip, to prevent overheatingof the latter.'

The control valve Q may be of any'khown or suitable form adapted to operate as described. As shown in Fig. 3, the body of the valve Q coinprises an inlet chamber Q in communication with the cylinder J through the pipe P, and 'a-n outlet chamber Q from which oil may pass freely 'to a receiving receptacle q. The valve chambers Q and Q are separated by a partition formed with a central circular opening, or port Q normally receiving a coaxial cylindrical valve member Q of a diameter to fit snugly in the port Q so that when the valve member Q is moved downward into its full closing position, the upperend of the valve member will be within, and will close or substantially close the port Q The valve member Q is formed at its periphery with a longitudinal V-shaped-slotQ which extends from the lower end of the valve member to a point some-what below the upper end of the valve member, and progressively diminishes in cross-section from its bottom upward.

When the speed of the strip A is constant and within its normal operating range, thevalve member Q will'occupy an intermediate position with such a portion of the groove Q within the port Q that the throttling effect of the valve member will be so related to the compression of spring J and resultant oil pressure beneath the piston J, that outflow from the cylinder J through valve Q will be equal in rate to the cylinder inflow through the pipe 0. On any adjustment of the valve Q, increasing or decreas ingits' throttling effect, the pressure of the oil in the cylinder J will increase or decrease as needed to equalize the outflow with the inflow to the cylinderf The position of the piston .J and therefore the distance between the work stripand each burner wall, Will thus vary in accordance with the changes in position of the valve. member Q when the latter occupies an intermediate position. I

When the travel of the work strip A is interrupted or its speed decreases below the regula tion range and the valve member Q is moved upward out of the portQ3, the oil is permitted to escape freely from the cylinder J which" then quickly empties and permits a corresponding rapid downward movement of the piston J", and thereby effects a rapid safety movement of each burner Wall awayfrom the work strip.

Inthe arrangement diagrammatically shown,

referring particularly to Fig. 1 the valve member Q is adjusted in automatic accordance with changes the traveler the work stripA, by means comprising "a centrifugal speed governor of conventional type and having its lever S conne'bted to the stem Q of the valve Q by a link R-"which includes a turn buckle R through which the effective lengthof the-link can be adjusted.

The speed governor S comprises shaft S mounted in a support S for rotativabut not for longitudinal movement, and comprises centrifugal weights S link connected to the upper end of the shaft S and, link connected to the lower end of a sleeve 5 surrounding and longitudie turns in the direction to give an opening or a closing adjustment to the valve member Q as the speed of the shaft S decreases or increases.

As shown, the governor shaft S is rotated at a speed proportional to the speed of travel of the Work strip A through a driving connection comprising a shaft T which is transverse to the shaft El and has one end connected to the latter by bevel gears T and has its opposite end connected through bevel gears T to one of the feed rolls C.

In the contemplated normal operation of the apparatus diagrammatically shown, when the speed of travel of the work strip A varies, the governor S effects corresponding adjustments of the valve Q. An immediate operative efiect of an adjustment of the valve Q is to vary the position of the piston J, and an adjustment in the position of the piston J directly varies the distance between each of the heating walls D and ward and from the strip in a normal regulating i range through distances functionally related to changes in speed of travel of the work.

When the speed of the work strip A is within 7 a regulation range, the body of the valve member Q is within the port Q and the rate of flow permitted by the valve with a given pressure in the cylinder J depends on what longitudinal portion of the valve groove Q is within the port Q Th work strip speed range can be varied through wide limits by adjustment of the turn buckle R and the consequent adjustment of the effective length of the link connection between the governor lever S and the valve member Q When the work strip speed is within the regulation range determined by the then existing adjustment of the turn buckle R, the position of the piston J will vary as the pressure of the oil in the cylinder J varies through a range above the minimum pressure required to overcome the piston loading force of the spring J when the latter is expanded to the full extent permitted by the spring follower J and its adjustable retaining member J The actual regulation range of piston movement may be varied by the adjustment of the head J and thereby the parts J J 7 and J longitudinally of the cylinder. The magnitude of the regulation range of adjustment of the piston J can be varied by adjustment of the bolt J to vary the maximum distance between the crosshead J and follower J".

The movements of the piston J in the cylinder J produce corresponding movements of the burner walls D and DA transverse to the work strip A passing them. The relation between any particular position of the piston J and th corresponding position of either burner wall, may be varied by the adjustment of the corresponding turn buckle M or by an analogous adjustment in the ffective length of the mechanical connection between the piston and the burner walls.

When the work speed decreases below the regulation range, fixed in apparatus of the form shown by the adjustment of the turn buckle R, the valve member Q is moved up out of the port Q thereby permitting a rapid discharge of the oil from the cylinder J and a correspondingly rapid downward movement of the piston J The gravitational forces acting downwardly on the piston J duetto the weight of the piston J maintain the oil being discharged from the cylinder under a pressur high enough to appreciably augment its rate of discharge. The ultimate operative effect of the last mentioned adjustment of the valve member Q is thus to effect an immediate movement of each burner wall D and DA away from the work strip a distance adequate in extent to prevent injury to the latter on an interruption of, or radical reduction in speed of the work strip A.

As will be apparent to those skilled in the art, the control of the positions of the burner walls D and DA relative to the work strip A, required in the practice of my method on changes in the work strip speed, which is obtained by the centrifugal speed governor S, valve Q, and servomotor J, illustrated, may be obtained by the use of other known or suitable instrumentalities differing widely from those last mentioned.

The multiplicity of individual and individually regulable burners din each heating wall, and the regulable means through which a combustible mixture of air and gas is supplied to each of said burners in use, permits a ready regulation of the relative heating effects of difierent portions of each heating wall as required to insure uniform heating of the work strip. Furthermore, the described combustible mixture supply regulating provisions permits the overall heating efiect of each burner wall to be varied as required by the conditions or operation. For example, under one operating condition in a particular plant, it may be desirable to maintain a regulation work speed range between limits above and below 600 feet per minute, and under another operating condition to maintain a regulation work speed range between limits respectively above and below a speed of 300 feet per minute. For operation with the higher work speed range all of the burners in each heating wall may be in use and operated at nearly full capacity. For operation at the lower work speed range, several of the manifold supply valves G may be closed to thereby temporarily put the corresponding horizontal rows of burners out of service. In addition, the pressure at which the fuel mixture is supplied to the burners remaining in service, may also be materially reduced.

To appreciate the importance of adequately rapid adjustments of the rate of heat transfer to the work from each burner wall, account should be taken of the high temperature and high rates of heat liberation involved. Thus, for example, it is reasonable to assume that in hot finishing a work strip which is 30 inches wide and of average thickness and which is moved through the finishing station at the rate of 600 feet per minute, each burner wall may have its burner face spaced 1 inch from the work, and may include burners, and to assume further that the burners of each burner wall are collectively supplied with about 30 cubic feet per hour of 500 B. t. u. gas mixed or combined with the required amount of combustion supporting air.

Under the operating conditions just described, the entire burner wall face adjacent the work strip will be incandescent, and the temperature in the combustion chambers of the burners will be about 2400" F. While a portion of the heat liberated in each combustion chamber is radiated directly from the burning gases to the work, the relatively high temperatures and large heat storage capacity of the refractory burner walls, do not permit regulation of the rate of heat transfer from the burner wall to the work strip rapidly enough to compensate for rapid variations in the work strip speedto be effected by' regulation of v the rate at which combustible mixture is supplied tothe burner wall burners.

While in accordance with the provisions of the statutes, I have illustrated and described the best form of embodiment of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit of my invention, as set forthin the appended claims, and that in some cases certain features of my invention may be used to advantage without a correspondinguse of other features.

Having now described 'my invention, What I claim as new and desire to secure by Letters Patent, is:

1. Apparatus for hot finishing'tinplate stock in the form of a thin stri having a tin coating, comprising in combination a pair of refractory walls having opposing faces normally in close proximity to each other, means carried by said walls for maintaining said faces at temperatures substantially higher than the melting point of tin, means normally moving said strip rapidly through the space between said walls, and means responsive to the speed of said strip for increasing the distance between said. faces when the speed of said strip diminishes.

2. Apparatus for hot finishing tin plate stock in the form of a thin strip having a tin coating, comprising in combination a pair of refractory walls having opposing faces normally in close proximity to each other, means carried by said walls for maintaining said faces at temperatures substantially higher than the melting point of tin, means normally moving said strip rapidly through the space between said walls, and means responsive to the speed of said strip for increasing and decreasing the distance between said faces as the speed of said strip decreasesand increases through a regulation range and rapidly and substantially increasing said distance when said speed decreases below said range.

3. Apparatus for hot finishing tin plate stock in the form of a thin strip having a tin coating, comprising in combination a pair of refractory walls having opposing faces in close proximity to each other, means carried by said walls for maintaining said faces at temperatures substantially higher than the melting point of tin, means moving said strip rapidly through the space between said Walls, and means responsive to the speed of said strip for increasing and decreasing the distance between said faces as the speed of said strip decreases and increases through a regulation range.

4. Apparatus as specified in claim 3, including means for varying the magnitude of the strip speed regulating range.

5. Apparatus as specified in claim 3, including means for varying the upper and lower limits of said strip speed regulating range.

6. Apparatus as specifiedin claim3, including means for varying the distance maintained be tween said faces at a given speed within said speed regulating range. V

Apparatus for hot finishing tin plate stock in the form of a thin strip having a tin coating, comprising in combination a pair of refractory walls having opposing facesin close proximity to each other, means carried by said walls for maintaining said faces at temperatures substantially higher than the melting point of tin, means for moving said strip rapidly through the space be- 1 0 tween said: walls, and means for separately adjusting the dits'ance between each of said faces and said strip.

8; Apparatus for hot finishing tin plate stock in the form of a thin steel strip coated with tin, comprising in combination, a pair of refractory walls each having a hot face adjacent and normally in close proxmity to the hot face of the other gas wall, means for maintaining said faces at temperatures substantially above the melting point of tin, means supporting each of said walls for movement in a direction toward and away from the other, means gravitationally biasing each of said walls for movement away from the other, means for rapidly moving said strip in the direction of its length through the space between said walls, positioning means normally operative to prevent movement of said walls away-from one another, and means responsive to the speed of said strip for rendering said positioning means inoperative on a predetermined decrease in the speed of said strip.

9. Apparatus for hot finishing a coating of tin on one side of a thin steel strip, comprisin in combination means for moving said strip at high speed in the direction of its length along a predetermined finishing path, a refractory wall having a hot face and at one side of said path at which said coating is exposed, means carried by said Wall for heating said face to a temperature substanti ally higher than the melting point of tin, and means responsive to the speed ofsald strip for increasing the distance between said face and path on a decrease in the speed of said strip while the latter is moving past said refractory-wall, said heating means during such increase in distance between its face and the path being capable of heating the strip to effect finishing of said coating thereon.

10. Apparatus for hot finishing a coating of tin on one side of a thin steel strip comprising in combination means formoving said strip rapidly in the direction of its length along a predetermined finishing path, a refractory wall at the side of said path at which said coating is exposed, means carried by said wall for heating said face toa temperature substantially higher than the melting point of tin, and means responsive to changes in speed of said strip for increasing and decreasing the distance between said face and patlias the speed of said strip decreases and increases while traveling past said refractory well, said heating means during such increase and decrease in distance between itsface and said path being capable of heating the strip to effect finishing of said coating thereon.

11. In the art of heating work with the aid of a high temperature source of heat in which the work is moved past such source of heat, the improvement which comprises varying the position of said source of heat with respect to the work, while the latter is being heated, responsive to changes in the rate of movement of the work in a normal'regulating range between a first speed and second higher speed of the Work, such variations in the position of said source of heat with respect to the work being effectedbyrelative movement therebetween through distances func-- tionally related to changes in the rate of movement of the work, and adjusting the position of said source of heat with respect to the work so that the work will not be injured by heat from said source of heat when the rate of movement of the work falls below the first speed in said normal regulating range.

12. The combination of means for heating work, means for moving said work past said heating means in a fixed path of movement for progressively heating successive longitudinal portions of the work, said heating means being movable toward and from the work, and mechanism responsive to decrease and increase in the rate of movement of the work in a normal regulating range between a first speed and second higher speed of the work for moving said heating means from and toward the work, respectively, said mechanism including means operable when the rate of movement of the work falls below the first speed in said normal regulating range for moving said heating means such a distance from the work that the latter will not be injured by heat from said heating means.

13. The combination with burner structure for producing gaseous heat to heat work, of means for moving the work past the burner structure for progressively heating successive portions of the work, the burner structure being movable toward and from the work, and means operable responsive to changes in the rate of movement of the work, while the latter is being heated by the burner structure, for moving the burner structure toward and from the work to control heating of the work, said last-mentioned means being constructed and arranged to move the burner structure through distances functionally related to changes in the rate of movement of the work.

14. The combination of means for heating work, means for causing the work to travel past the heating means for progressively heating successive portions of the work, the heating means being movable from and toward the work, mechanism operable while the work is traveling for moving the heating means from and toward the work through distances functionally related to changes in speed of travel of the work, the heating means during such movement effected by the mechanism being capable of heating the work, and said mechanism including means to cause movement of the heating means from the work, when the traveling movement of the work is stopped, through a distance which is not functionally related to change in speed of travel of the work to prevent the latter being injured by heating by the heating means.

15. The combination of means for heating work, means for causing the work to travel past the heating means in a fixed path of movement for progressively heating successive portions of the work, the heating means being movable from and toward the work, and mechanism operable while the work is traveling for moving the heating means through distances functionally related to changes in speed of travel of the work, the heating means during such movement effected by the mechanism being capable of heating the work.

16. In the art of heating work of elongated extent, the improvement which comprises ra idly moving the work in a fixed path of movement, progressively applying through a gaseous medium to successive longitudinal portions of the work, when the latter is traveling in said path of movement at a definite speed, a source of heat which is at a temperature much higher than the melting point of the work and sufficiently close to the work to melt the surface thereof, and, while the source of heat is being so applied to the rapidly moving work, moving the heat source from the work responsive to decrease in speed of the work from the definite speed.

17. In the art of heating work of elongated extent, the improvement which comprises rapidly moving the work in a fixed path of movement, progressively applying through a gaseous medium to successive longitudinal portions of the work, when the work is traveling in said path of movement at a predetermined speed, a source of heat which is at a temperature much higher than the melting point of work and sufliciently close to the work so as to melt the surface thereof, moving the source of heat toward and from the work through distances functionally related to increase and decrease, respectively, in change of speed of the work from the predetermined speed in a normal range of speed variations of the work so as to effect melting of the surface in such normal speed range of the work, and, when the speed of travel of the work falls below the lower limit in the normal speed range, moving the source of heat from the Work such a distance that undesirable overheating of the work is avoided.

18. In the art of heating the opposing surfaces of work of elongated extent, which comprises rapidly moving the work in a fixed path of movement, progressively applying through a gaseous medium to successive longitudinal portions of each surface, when the work is traveling in said path of movement at a predetermined speed, a source of heat which is at a temperature much higher than the melting point of the work and sufiiciently close to the work so as to effect melting of the opposing surfaces thereof, and moving the sources of heat toward and from the work through distances functionally related to increase and decrease, respectively, in change of speed of the work from the predetermined speed so as to effect melting of the opposing surfaces with changes in speed of travel of the work from the predetermined speed.

19. In the art of heating work, the improvement which comprises moving the work in a fixed path of movement past a source of heat for applying heat through a gaseous medium to successive areas of the work, and, while heat is being so applied to the work, varying the position of the source of heat with respect to the work responsive to changes in the rate of movement of the work, such variations in the position of the source of heat with respect to the Work being effected by relative movement therebetween through distances functionally related to changes in the rate of movement of the work.

20. In the art of heating work, the improvement which comprises moving the work in a fixed path of movement past a source of heat, maintaining the heat source a definite distance with respect to the work for movement of the latter at a predetermined speed so as to apply heat through a gaseous medium to the work to heat successive areas thereof approximately to the same desired high temperature, and, while heat is being so applied to the work, moving the heat source toward and from the work responsive to increase and decrease, respectively, in change of speed of the work from the predetermined speed so as to heat successive areas of the work approximately to said desired high temperature upon changes in speed of the work from the predetermined speed.

21. In the art of heating work, the improvement which comprises moving the work in a fixed path of movement past the source of heat, maintaining the heat source a definite distance with respect to the work for movement of the latter it? a predetermined speed so as to apply heat through a gaseous medium to the work to heat successive areas thereof approximately to the same desired high temperature, and, while heat is being so applied to the work, moving the heat source toward and from the work responsive to increase and decrease, respectively, in change of speed of the work from the predetermined speed in a normal range of speed variations of the work so as to heat successive areas of the work approximately to said desired high temperature in such normal speed range of the Work, and, when the speed of travel of the work falls below the lower limit in the normal speed range, moving the heat source from the work such a distance that undesirable overheating of the work is avoided.

22. In the art of heating work, the improvement which comprises moving the work in a fixed path of movement past the source of heat for applying heat, to successive areas of the work, and, while heat is being so applied to the work, moving the heat source with respect to the work responsive to changes in speed of the work in a normal regulating range between a first speed and a second higher speed so as to control the normal heating of the work, and, when the speed of travel of the work falls below the first speed in the normal regulating range, moving the heat source a suificient distance from the work without regard to the normal heating of the work so as to prevent undesirable overheating of the work. 23. In the art of heating work with the aid of a high temperature source of heat possessing such operating characteristics that residual heat is produced thereby after the supply of heat producing medium thereto is substantially reduced, the improvement which comprises moving the work at a rate of speed in a normal speed range past such source of heat for applying heat to successive areas of the work, and, while the work is openly exposed to the source of heat, increasing the distance between the source of heat and the work suificiently to prevent undesirable overheating of the latter when the speed of travel of the work falls below the normal speed range.

FREDERIC O. HESS.

Certificate of Correction Patent N 0. 2,409,431.

FREDERIO O. HESS It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows: Column 4, line 70, for mast read most; column 5, hne 14, before truck insert carriage or; column 10, line 2, claim 7, for d1tsance read dzsta'nce; line 8, claim 8, for proxmlty read proximity; column 11,

comma respectwely, insert while the latter is LESLIE FRAZER, v First Assistant Commissioner of Patents.

October 15,. 1946.

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