US2268986A - Method and apparatus for drying printing ink - Google Patents

Description

Jan. 6, 1942. F. 0. HESS EIAL 2,268,986

METHOD AND APPARATUS FOR DRYING PRINTING INK I Filed May 3, 1958 3 Sheets-Sheet 1 INVENTOR;

fiefiofe/ca [1538 .BY v C/JELPMQNN ATTORNEY.

Jan. 6, 1942.

F. o. HESS ETAL; I

METHOD AND APPARATUS FOR DRYING PRINTING INK 3 Sheets-Sheet 2 Filed May 3, 1938 INVENTORS FEEDER/C 0. Mix? 0 C024, D/WHNN b rm ATTORNEY.

Jan. 6, 1942. F. o. HESS ET AL METHOD AND APPARATUS FOR DRYING PRINTING INK Filed May s, 1938 3 Sheets-Sheet 3 INVENTORS fiZmEe/c 0 H553 C004 DMGNN ATTORNEY.

M E k "gas and air is supplied to the burners.

Patented Jan. 6, 19,42

UNITED -STATES PATENT OFFICE METHOD AND APPARATUS FOR DRYIK G PRINTING INK Frederic 0. Hess, Germantown, 2a., and Carl P. Mann, Riverton, N. 1., assignors, by some assignmenta, to Intcrchemicai Corporation, New York, N. Y., a corporation of Ohio Application May a, 1938, Serial N... 295,682

This inventionerelates to printing and aims to provide an improved method and apparatus for drying printing-ink and other marking materials.

There are marking materials in extensive use at the present time which may be eflecti vely and quickly dried by the application of heat to the web or sheet on which such materials have been applied. One example ofsuch marking materials are the typographic printing inks whose Ve-r hicles consist of binders dissolved in solvents which are substantially non-volatile at ordinary press room temperature (abofit C.) and which become highly volatile at temperatures of about 156 C. It is conventional practice to dry such inks by applying heat of sulficient intensity to volatilize the*ink solvents and then disposing of the volatilized solvents. When such inks are applied to a web in a high speed multiill color printing press, for example, the web may be fed at a speed in excess of four hundred feet per minute and, to prevent offsetting and smudging, it is necessary to dry'the ink in the relative- 1y short space between printing units and between the last printing unit and the rewind roller ill the action of a plurality of gas burners having manifolds mounted within the furnace and through which fuel consisting of a mixture of In the past, the construction of the burners and the manner of cooling ,them and ventilating the furnace did not lend themselves well to changes I in web speed and web width. This often resulted in scorching of the web when its speed was changed, particularly during starting and stopping periods, causing considerable waste of material. Moreover, when the press was stopped,

it was necessary to move the burners to an inoperative position to prevent scorching or burning of the web and this required the use of exably comprises an elongated flame, which may be adjusted in width to correspond with the width of the web or the printed portions thereof, and which is adapted to strike the web with s'ufficient force to move the volatllized 'solventsto either side of the flame. Then fresh air is supplied on bothZsides of the flame for aiding in the combustion of the solvent vapors adjacent the surfaeeof the web. For preventing scorching or burning of the web when the press stops, we employ burners having a very low heat storage capacity and supply an increased .flow. of fresh cooling air thereto during stopping periods while simultaneously increasing the withdrawal of heated air and hot burned vapors from the region of the webr These and other objects and features will become apparent from the following description of specific embodiments of the apparatus features ofour invention, and by reference to the.

Fig. 5 is an enlarged fragmentary detailed sec ti'onal view 'of a portion of a modified burner;

Fig. 6 is a front elevational view of one of the furnace burners; and

Fig. 7 is a detail sectionalview of a portion of one of the burners showing the action of the fiame and air on the web. 1 a

In the apparatus illustrated in the drawings, inkis applied to a web ID, of paper or other marial to be marked, by means of a press I2. As the web emerges from the press, it has its printed surface uppermost and is ledin-the direction indicated by the arrows in Fig. 11 over a guide ,roller l4 and through a drying apparatus l6,

' from .which it passes over a water cooled roller II and rollers 20 to a suitable rewind roll 22 or subsequent treating mechanism. (not shown).

Drying apparatus l8, which in the form shown m Figs. 1 and 2 is suitable for use with ordinary paper, is mounted on a frame 24 attached to the exit or delivery end of the press=and comprises a housing having a top wall 26, bottom wall 28, side walls 20 and end walls 32 all of which may be composed of any suitable material. Included in the housing are an upper air distributing or manifold compartment 34 (Fig.2) and a lower Frederic O. Hess Patent No. 2,228,114, dated January '7, 1941, and are constructed to provide a long ribbon of flame substantially the same width as the web being dried. Briefly, and as best shown in Figs. 4, and 6, each burner comprises a suitable metallic burner body 42 including an integral manifold 44 and a lower gas distributing chamber 48 having a longitudinal opening 48 in the wall thereof which is adjacent the web. The

manifold 44 may be connected,'by means of a threaded connecting conduit 50 outside of the furnace, to a suitable source of fuel-and to a controlling device to be described hereinafter. A plurality of laminae 52 or plates of ceramic refractory material are mounted over and extend across the opening 48, being held in proper position by means of clamping plates or parts 54. Each of the small ceramic plates is provided with any desired number of slots or grooves 58 in one or both of .its sidesso that when mounted in the burner, as shown in Fig. 4, they will provide a series 'of aligned orifices for producing the desired elongated ribbon flame. Moreover, each plate may be provided with extensions 58 on each side of the oriflces so as to produce a trough shaped combustion space 60 which effectively prevents blow-off. Due to the provision of a lower wall of ceramic material, and the extensions 58, the burner has an exceedingly low heat storage capacity and this is an important factor in preventing scorching of the web when the flame is extinguished upon stopping the press. The burners may be lighted by means of ignition devices 62 which, in the present instance, are automatic electric devices arranged to create a spark about twenty times per second. Then, should any burner be extinguished accidentally, it will be relighted automatically before a dangerous amount of gas collects in the furnace chamber.-

We have observed that as the web ll passes through the drying apparatus, it tends to be bowed or curved, as indicated in dot and dash lines in Fig. 6. In order to prevent burning or scorching of the web at the center or highest portions thereof, the burner bodies 42 may be constructed in a plurality of sections 64 having flanges 66 by means of which they may be secured together to form a complete burner of the desired width. By constructing the burner in sections in this manner, it may be, longitudinally curved, as indicated in Fig. 6 to conform substantially to the outline or cross-section of the web passing beneath'it.

oftentimes it is desired todry a printed web which is'narrower than the. drying apparatus.

the burner to a point outside the furnace. Rotation of the adjusting screws will move the pistons in or out to produce a flame of the desired width. These and other means for varying the width of the flame are described in detail in the above referred to patent of Frederic 0. Hess. If the web has an unprinted section or strip in the mid-portion thereof, it may be desired to block out the flame over such an unprinted portion. This may be accomplished by providing substantially T-shaped blocks .12 (Fig. 5) of ceramic refractory material which are adapted to flt in the trough shaped combustion space ill and close of! the orifices in the burner. These blocks may be held in place by means of suitable clips 14 as indicated.

In the drying apparatus the elongated flames provided must-supply enough heat to volatilize the solvents of the ink which solvents will then be burned by the flames. To reduce the overall 'length of the drying apparatus, theflrst burner at the entrance end of said drying apparatus may be operated at a greater capacity than the remaining burners. Since the web is cold as it enters the drying apparatus, the temperature of the ink will, in this way, be raised as rapidly as possible so that the subsequent burners will completely volatilize the ink solvents before the web leaves the drying apparatus.

We have shown four burners 40 in the drying apparatus. The elongated and properly adiusted flame from each of these burners strikes the printed surface of the web with considerable impact and the solvent vapors are thus projected outwardly on each side of the ribbon flame as illustrated in Fig. '1. Bailies IS are provided at the sides of each burner and form ducts 18 for directing air from the manifold compartment 34- about the sides of the burners and into the heating chamber 36. Such air is supplied to the manifold compartment 34 through a conduit 80 which communicates with an inlet chamber .2 secured to the top of the drying apparatus. A

plurality of conduits 84 lead from the inlet chamher to the manifold compartment and by means of a bailie I having conduits or apertures 88 1 therein the air is well distributed throughout the entire compartment. This fresh air, aside from effectively cooling the burners, mixes with the outwardly projected solvent vapors andprovides the necessary oxygen for their combustion.

Moreover, the force with which the flames from the several burners strike the web together with the airsupplied through the ducts ll produce a violent turbulence throughout the heatin chamber 34 which aids materially in the rapid drying of the ink.

Products of combustion and any vapors from the ink which may not have been burned are For adjusting the width of the ribbon flame to pistons and extending through the end walls of withdrawn from. the furnace through a suction or exhaust duct 00 providedabove an extended portion 92 of the furnace chamber. In order that all'such vapors will be withdrawn, there is provided at the end of the extended portion a cover member or skirt '4 which extends over roller l8 to provide a restricted opening to the press room. As indicated by the arrows in Figs. 2 and 3,.fresh air is drawn through this opening from the press room in a direction counter to the travel of the printed web, and this countercurrent of fresh air prevents the travelling web from drawing the products of combustion or solvent vapors with it into the press room. As indicated, this cover member is hinged at .8 to the suction duct Q0 so it may be raised to fa-.

2,2ee,eae- I cilitate feeding the web through the drying ap- Daratus.

In normal operation of the printing press, there are necessary variations in the speed of the web during starting and stopping periods, when making adjustments in register and the like. If a constant amount of heat is supplied by the burners regardless of the speed of the web, it will result in burning or scorching of the web with resulting waste of material and possible danger of fire. We have found. that this difliculty may be overcome by correlating the flow of gas,

to the burners in predetermined correspondence with the speed of the press, so that at all times a proper amount of heat will be supplied for drying the web and at no time will the heat be great enough to damage thewe'b. For accomplishing this, we have provided a special control means which will now be described.

As shown in Fig. 1, the manifolds of the burners in the drying apparatus I8 are connected through a distributing conduit I with a supply conduit I02 leading to a conventional gas and air mixer and pump (not shown). A suitable diaphragm operated control valve I04 is provided in the supply line and one side of the diaphragm thereof is connected by means of a conduit I08, having a pressure relief valve I08 therein, to the outlet side of a positive type rotary pump IIO, said pump, conduit and valve forming part of a closed fluid system. The pump is pref'-' erably operated directly from one of the driven shafts of the press, for example the shaft of the impression or plate cylinder, -so that the speed of the pump, and hence the pressure produced thereby and transmitted to the control valve I04, will be varied in predetermined correspondence with from the heating chambers. vAccordingly, we have provided an auxiliary fresh air supply conduit or duct I22 which is connected to a distributing chamber I24 secured to the front end wall 32 at-the entrance end of the drying apparatus. A plurality of downwardly directed conduits I28 in the lower portion of the chamber I24 are arranged to direct the auxiliary fresh air into the heating chamber 38.

, Fresh air is supplied through the duct In only when the press stops and the burners are ex- 132, respectively. The dampers I30 and I32 are normally open a small amount as indicated, to permit the desired passage of air therethrough during normal operation of the drying apparatus; while the damper I28 in the auxiliary fresh air duct is normally closed during such normal the speed of' the plate cylinder. A conduit II2, having a manually controlled regulating valve II4, therein, leads from conduit I08 to an expansion chamber I I8 from which a conduit II8 i leads to-the inlet side of the pump I I 0. Below the regulating valve II 4, a by-pass conduit I20 may connect the conduit I I2 with the pressure relief valve I08. By means of the manually controlled regulating valve II4, the total volume of fluid circulated by the pump may be returned thereto at any desired pressure differential. Hence, for different heat requirements, this valve may be adjusted to different openings so as to vary the pressure on-the diaphragm and the resultant opening of the valve in the gas line. It will be apparent, however, that when once set, the pressureon the diaphragm will subsequently vary directly or in predetermined correspondence amount of heat supplied by the burners will be varied in predetermined correspondence with the speedof the web so that scorch ng or burning during periods when the press is operating at reduced speeds will be prevented. When, however, the press is stopped completely and the burners extinguished, we. have found it desirable to increase the supply of fresh air to the drying apparatus and simultaneously increase the withdrawal of heated air and burned solvent vapors If deoperation of the drying apparatus. When the press is stopped, however, each of these dampers is immediately and automatically thrown to the open position so as to provide enough fresh air to cool the entire drying apparatus sufficiently to prevent scorching ofv the web. For accomplishing this, there is provided a solenoid I34 which has its piston pivotally connected to the first arm of a three-armed actuating member I38 mounted upon the auxiliary fresh air damper I28. A second arm of the actuating member I38 is pivotally connected by means of a-link I38 to an arm I40 on the main fresh air damper I30. and the third arm is pivotally connected by means of a link I42 to an arm I44 on the exhaust damper I32. The construction of the actuating member and links is such that when the solenoid is energized the dampers will be moved to their completely open positions as shown in dot and dash lines in Fig. 1. Such energization of the solenoid may be arranged in any convenient manner to take place when the press stops. An additional solenoid I48, disposed opposite the first solenoid and likewise having its pistons connected to the first arm of the actuating member I38, may be provided for moving the dampers back' to theirnormal positions when the press again starts operating. While I have shown solenoids for operating the dampers, it willbe understood that any other suitable means, such as motor operated valves, may be used for the same purpose.

When the web I 0 consists of a delicate material which is injured'by a moderate amount of heat, it may be desirable to provide a drying apparatus having additional cooling and exhaust facilities. Such a drying apparatus, which may be mounted on the press as shown in Fig. 1, is illustrated in Fig. 3 and comprises a housing I including ,a manifold chamber I52 and a furnace or heating chamber I54, which areseparated by a wall I58 of suitable insulating or refractory material. Burners I58, similar to the burners 40 shown in. Fig. 2, are mounted at spaced intervals in the wall I58 and provided with 'baflies I for the circulation of cooling air thereabout and into the furnace chamber. The supply of gas to the burners and air for cooling them may be con-'- trolled in accordance with the web speed as described above. Cooling air is supplied to the manifold compartment I82 by means of air inlet conduits I62 provided at each end of the housing. Each of these inlet conduits is connected to an air distributing chamber I64 and, by means of a plurality of conduits I66 and I88, the air is directed into the manifold compartment for circulation therein. Distributed longitudinally throughout the drying apparatus and transversely between the burners I58 are a plurality of exhaust conduits I'Ill which, as shown, lead directly from the furnace or heating chamber I54 to an upper exhaust chamber I12 provided above themanifold compartment. A conduit I14 conducts the exhaust gases from this chamber to a suitable point of disposal. conduits H0, there is also provided an exhaust or suction conduit I16, at each end of the drying apparatus. To prevent the escape of vapors into the press room cover members or skirts 518 may be provided adjacent the exhaust conduits H6 and their associated rollers. Extensions I80 may also be provided at each end of the drying appa- In addition to the ratus so that the furnace chamber will be substantially closed.

The fresh air inlet conduits and the suction or exhaust conduits may be provided with dampers ing apparatus, the hot gases may be readily withdrawn from points distributed throughout the entire apparatus, rather than from the exit end only as in the Fig. 2' construction. In this manner a very rapid flushing of the hot gases from the furnace chamber can be obtained. When this is combined with an increased flow and circulation of cooling air about the heated burners upon stopping the press, scorching or burning of the web is efiectively prevented. It will also be understood that various features of the invention as described herein may be used with the means and methods for cooling the lower side of the web as disclosed in the copending application of Frederic O. Hess, Serial No. l82,210, filed December 29, 1937.

Although preferred embodiments of the invention have been described herein, it will be understood that many changes may be made and certain features employed without others without departing from the invention or sacrificing any of its advantages.

What we claim is:

1. A method of drying printing ink containing a volatilizable inflammable solvent after such ink has been applied to a material, which comprises passing the material beneath an elongated flame which is adapted to produce heat of suificient intensity to volatilize'the solvent/of the ink and to strike the printed surface of the material with sufllcient force to project the volatilized solvent to either side thereof, and supplying a controlled amount of fresh air on either side of said flame which will mix with the volatilized solvent and provide oxygen for the combustion thereof.

- 2. A method of drying printing ink containing a volatilizable inflammable solvent after such ink has been applied to a material, which comprises passing the material through a furnace provided with an elongated gas burner directed toward the printed surface of the material, burning a substantially completely combustible mixture of gas 75 ing the combination with means for continufluid pressure for varying the flow of gas through said solvent vapor.

3. A method of drying a printing ink containing a volatilizable and inflammable solvent after such ink has been applied to a material, which comprises moving the material through a furnace provided with a gas burner directed towards the printed surface of the material, burning a substantially completely combustible mixture of gas and air in said burner, volatilizing the solvent of the ink, projecting a current of air over the burner and then into admixture with the solvent vapor to cool the burner and provide air for combustion of the solvent vapor, controlling the amount of gas and air mixture'supplied to the burner in accordance with the speed of movement of the material, and burning said solvent vapor.

4. A method of drying a printing ink containing a volatilizable and inflammable solvent after such ink has been applied to a material, which comprises moving the material through a furnace provided with a gas burner directed towards the printed surface of the material, burning a substantially completely combustible mixture of gas and air in said burner, volatilizing the solvent of the ink, projecting a current of air over the burner and then into admixture with the solvent vaporto coolithe burner and provide air for combustion of the solvent vapor, controlling the amount of the gas and air mixture supplied to the burner and the amount of air projected over the heater in accordance with the speed of movement of the material, and burning said solvent vapor.

5. In a method of drying printing ink containing a volatilizable and inflammable solvent after such ink has been applied to a material, and wherein the material is passed beneath a gas burner to which: air is supplied for cooling the burner and aiding in the combustion of the volatilized ink solvents and heated air and burned solvent vapors are continuously with drawn from the region of the material and the burner, the step of increasing the flow of air to the burner and material while simultaneously increasing the withdrawal of heated air and burned moving a web to which ink has been applied, .01? a gas burner located adjacent the path of the printed web and arranged so that the flame will be directed upon the printed surface of the web; means for supplying gas to said burner;

and means for varying the supply of gas to said v burner in predetermined correspondence with the speed of the printed web; said last mentioned means comprising a fluid conduit. means operatively connected with said web moving means for creating a pressure in said fluid conduit which is proportional to the speed at which the press is driven, and a diaphragm-operated valve in such gas supplying means and arranged so that the diaphragm thereof is responsive to such the gas supplying means.

7. Apparatus for drying printing ink comprisprising the ously moving a web to which. ink has been applied, 'of a gas furnace located in the path of the.

printed weband comprising av heating chamber, a gas burner in said heating chamber, means for supplying gasto said burner, means for directing air upon said'burner and into said heatingchamber, and means for increasing the quantity of air supplied to said last mentioned means when the web movement is stopped.

8. Apparatus for drying printing ink, comprising the combination with means for continuously moving a web to which ink. has been applied, of a gas furnace located in the path of theprinted web and comprising a heating chamber, a gas burner disposed in said heating chamber, means for supplying gas to said burner, means for directing air upon said burner and into said heating chamber, means for withdrawing air and vapors from said 'heating chamber, means for increasing the supply of air to said heating chamber when the web movement is stopped, and means for increasing the amount of air and vapors withdrawnfrom said chamber when the web movement is stopped;

10. Apparatusfor drying printing. ink, comprising the combination with means for continuously moving a web to which'ink has been point of travel of the web-and longitudinally curved to conform substantially to the crosssection of the web passing beneath it.

' 14. Apparatus for drying printing ink, comprising the combination with means for causing travel of a web-to which ink has been applied, of

- i an elongated gas burner located adjacent a point of travel. of the web and adapted to produce an elongated and substantially continuous flame, and means for adjusting said flame to conform substantially to the width of the web.

15. Apparatus for drying printing ink, comprising the combination with means for causing of a gas furnace located in the path of the travel of a web to which ink has been applied.

of an elongated gas burner located adjacent a point of travel of the web and adapted to produce an elongated flame, and means .to adjust said flame so that it will only be directlyappliedto portions of the web on which printing ink has been applied.

16. Apparatus for drying printing ink con-- taining a volatilizable solvent, comprising the combination with means for causing travel of a web to which such ink has been applied, of an elongated gas burner located adjacent a point of travel of the web and adapted to produce an elongated and substantially continuous flame,

baiiies on each side of said burner which are adapted to form ducts through which air may be applied,-of a gas furnace located in the path of the printed web and comprising a heating chamber, a gas burner disposed in said heating chamber, means for supplying gas to said burner, means for directing air upon said burner and into said heating chamber, means for withdrawing air and vapors from said heating chamber, and means for increasing the amount of air directed upon said burner and into said heating chamber while simultaneously increasing the amount of air and vapors withdrawn from said chamber when the web movement is stopped.

ll. Apparatus for'drying printing ink, comprising the'combination with means for continuously moving a web to which ink has been applied, of a gas furnace located in the path of the printed web and comprising a heating chamber, a plurality of elongated gas burners disposed in said chamber throughout the length thereof, meansfor directing a current of air over said burners and into said heating chamber, and a plurality of exhaust conduits located between said burners and adapted to effect a rapid withdrawal of heated gases from said chamber.-

12. Apparatus for drying marking material,

, comprising the combination with means for causing travel of a web to which the marking material has been applied, of an elongated gas burner located adjacent a point of travel of the web and adapted to produce a continuous flame substantially as wide as the web, and means for ad-' justing the width of the flame so that webs of different widths may be dried. a

13. Apparatus for drying printing ink, comcombination with means for causing travel of a web to which ink has been applied, of an elongated gas burner located adjacent a comprising in combination, means for causing.

travel of a web towhich the marking material has been applied, an elongated gas burner located adjacent a point of travel of the .web and comprising a metallic burner body with an opening in its wall adjacent the web, an orifice wall extending across said opening and formed of plates of ceramic material with orifice grooves in their sides, metallic clamping parts at the side edges of said wall for clamping said plates to said body, and means for moving air over said burner and along said clamping member into contact with the web at the sides of the burning Jets issuing from said orifice grooves.

18. Apparatus for dryingprinting ink, comprising the combination with means for continu-. ously'rnoving a web to which ink has been'applied, of a gas furnace located in the path of the.

printed web and comprising a heating chamber, a plurality of elongated gas burners disposed. in said chamber throughout the length thereof, an air distributing chamber located above said heating chamber, and passages for directing cooling air from said air distributing chamber to the bodies of said gas burners and to the part of the printed web which is adjacent said burners.

19. Apparatus for drying printing ink, comprising the combination with means for continu-.- ously moving a web towhich ink has been ap-' plied, of a gas furnace located in the pathv of part of the printed web which is adjacent said heating chamber.

gases from said 20. Apparatus for drying printing ink, comprising the combination with means for causing travel of avweb to which ink hasbeen applied, of an elongated gas burner located adjacent a point of travel of the web and longitudinally curved to conform substantially to the cross-section of the web passingbeneath it, and means for adjusting the width of the flame produced by said burner so that webs of different widths may be dried.

21. Apparatus for drying printing ink containing' a volatilizable solvent, comprising the combination with means'for causing travel of a web to which uch ink has been applied, of a plurality of elongated gas burners located adjacent a point of travel ofthe web and adapted to produce elongated and substantially continuous flames, means on each side of each of said burners adapted to form ducts through which air may be passed for cooling said burners and aiding in the combustion of ink solvents, and means arranged between said burners and adjacent said .last mentioned means for withdrawing heated in its wall adjacent the web, an orifice wall extending across said opening and formed of ceramic material, metallic clamping parts at the side edges of said orifice wall for clamping said wall to said body, and means for moving a cooling medium over said burner and along said,

clamping member. I v

23. Apparatus for drying. printing ink, comprising the combination with means for continuously moving a web to which ink has been applied, of a gas furnace through which the printed web is moved and comprising a heating chamber,

a gas burner disposed in said heating chamber relatively close, to the web and on the freshly printed side thereof, means fonsupplying gas to said burner, means for directing air into said heating chamber and toward the freshly printed side of the web, and means for increasing the quantity of air supplied "to said last mentioned means when theweb movement is stopped.

24. Apparatus for drying printing ink, comprising the combination with means for c'ontinuously moving a web to which ink has been applied, of a gas furnace through which the printed web is moved and comprising a heating chamber, a gas burner disposed in said heating chamher relatively close to the web and on the freshly printed sidethereo'f, means for supplying gas to said burner, means for directing air into said heating chamber and toward the freshly printed side of the web, and meansfor directing an auxatively close to said web and arranged to provide flames directed toward the freshly printed side of the web and extending in the direction of air flow through said passageways.

ally

aaeaeec 26. In an apparatus for drying an inked web, means for continuously moving a web to which ink has been applied, means forming a plurality of air passageways adapted to deliver air to-the web to be dried, means for circulating air in ex cess of thatrequired for supporting combustion through said passageways to said web, burner means positioned in said passageways relatively close to said web and arranged to provide flames directed toward the freshly printed side of the web and extending in the direction of air flow through said passageways, and means for latershielding said flames from air flowing through said passageways.

27. In a drying apparatus of the character described for drying an inked. web, means for continuously moving a web to which ink has been applied, an air passageway adapted to deliver air to the web to be dried, means for circulating air in excess of that required for supporting combustion through said passageway to said web, and a burner positioned in-said passageway relatively close to said web and adapted to provide a flame directed toward the freshly printed side of the web.

28. In a drying apparatus of the character described for drying an inked web, means for, continuously moving a, web to which ink has been applied, an air passageway adapted to deliver air to the web to be dried, means for circulating air in excess of that required for supporting combustion through said passageway to said web, a burner positioned in-said passageway relatively close to said web and adapted to provide a flame directed toward the freshly printed. side of the webs, and means for preventing the flow of air through 'said passageway from interfering with the operation of said burner.

. 29. A drying apparatus of the character described for drying an inked web including, in combination, a casing forming a drying chamber, means for passing through said casing a web to be dried, a plurality of air supply passageways within said casing adapted to deliver air to the fresh-' ways and adaptdto produce flames directed toward said freshly printed side, a plurality of air return passageways in said casing and means for circulating air through said air passageways,

whereby it is discharged in contact with said web, and then through said air return passageways, whereby it is withdrawn from said web.

30. A drying apparatus of the character described for drying an inked web including, in combination, a casing forming a drying chamber, means for passing through said casing a web to be dried, a plurality of air supply passageways within said casing adapted to deliver air to the freshly printed side of said web at a plurality of spaced points, burners arranged in said passageways and adapted to produce flames directed toward said freshly printed side, a plurality of air return passageways in said casing, means for circulating air through said air supply passageways, whereby it is discharged in contact with said web, and then through said air return passageways, whereby it is withdrawn from said web, and means for controlling the operation of said burners in predetermined correspondence with the speed of travel of .said web.

31. Apparatus for drying printing ink, comprising the combination with means for moving a material to which ink has been applied, of a gas furnace through which the printed material is moved and comprising a. heating chamber, a plurality of elongated gas burners disposed in said said heating chamber and toward the freshly printed side of the material, and a, plurality of enhaust conduits located between said burners and adapted to eflect a rapid withdrawal of heatedgases from said chamber.

- FREDERIC 0. HESS;

CARL P. MANN.

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