Printed paper drying device for offset printing
mte States Patent 1 1 1 3,874,091 Fukumoto Apr. 1, 1975 [54] PRINTED PAPER DRYING DEVICE FOR 2,473,629 6/1949 Andrews: 34/160 OFFSET PRINTING 2,532,032 11/1950 Offen..... 34/13 2,700,226 1/1955 Dun ler 34/160 [76] n ent T a Fukumoto, 3,680,218 8/1972 Belui 34/156 Sanno-cho l-chome, Ota-ku, T J Okyo apan Primary ExaminerCarro11 B. Dority, Jr. [22] Filed: Aug. 3, 1972 Assistant Examiner-Larry I. Schwartz [21] Appl. No.: 277,688  
  [57] ABSTRACT [30] Foreign Application Priority Data Th t l t t d t d d 1s lnven ion re a es 0 a rymg appara us lspose Aug. 6, 1971 Japan 46 69707 adjacent to an Offset p g machine for y g the printed paper sheets, said apparatus being provided [52] US. Cl 34/66, 34/160, 443322//1]3436, with a direct fire y g station and a hot air y g [51] Int Cl F26b l9/00 station arranged in side by side relation, wherein the [58] Fieid 162 62 66 substantial portion of hot air supplied to said hot air 34/ 432277 drying station is returned back to the air heating section where hot air is produced, so as to enhance heat- [56] References Cited ing efficiency and hot air drying performance, thereby realizing quick finishing of prints. UNITED STATES PATENTS 2,297,314 9/1942 Offen 34/160 1 Claim, 4 Drawing Figures PRINTED PAPER DRYING DEVICE FOR OFFSET PRINTING TECHNICAL BACKGROUND OF THE INVENTION There is of late an increasing demand forhigher quality of the prints particularly in offset printing, and it is generally accepted that the quality of the prints depends greatly on drying performed on the printed sheets.  
  For efficient and economical practice of such drying, full utilization of heat is essential. However, when a paper sheet, which has been printed on its both sides, is moving in the air, the surface of the sheet is, as it were, wrapped with a thin film of air which flows at the same velocity as the sheet, and since such air film around the sheet surface has an adhesvie disposition and also acts as a heat insulator, great difficulites, both techically and mechanically, are encountered in excluding such air film and transmitting heat at high efficiency so as to accomplish uniform drying in a short time.  
 SUMMARY OF THE INVENTION A primary object of the present invention is to provide a drying apparatus of the type referred to, in which a direct fire drying means and a hot air drying means are provided in side by side relation in the apparatus and after the web has been heated at high speed by direct exposure to tire, said web is contacted with hightemperature high-speed hot air so as to enhance drying efficiency for both sides of the web travelling in the apparatus and to gasify and isolate solvent gas produced from the printing ink so as to effect immediate exclusion of such gas.  
  It is also an important object of the present invention to provide means whereby a major portion of hot air supplied to the hot air drying section provided immediatley behind the direct fire drying section is circulated to the heating section where said hot air is generated. so as to increase the heating efficiency and to realize most economical utilization of heat.  
  A further object of the present invention is to provide an assembly in which the direct fire drying means, hot air drying means, air heating means, air blower means and web air-cooling means are all combined into a single integral mechanism and wherein each of said means can be operated at its fixed position.  
  A still further object of the present invention is to provide a construction in which said direct fire drying means and hot air drying means are arranged in vertically symmetrical relation to allow optional joining and separation of said both means, so as to facilitate feeding of web into said both means and inspection thereof.  
 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of the apparatus in accordance with the present invention, showing a part of the hot air drying section and essential parts of the air-cooling means;  
  FIG. 2 is a side view as taken along the line 2--2 of Fig. l in the direction of arrows, with parts broken away to show the interior mechanism;  
  FIG. 3 is a prespective view of a part of the apparatus, showing the hot air supply route; and  
  FIG. 4 is an illustrative arrangement plan showing the hot air circulation route.  
 DETAILED DESCRIPTION OF PREFERRED EMBODIMENT OF THE INVENTION The present invention provides a combination type drying system in which direct fire drying and hotair drying are used in combination. The charateristic mechanism of the system is described in detail hereinbelow with reference to the drawings.  
  Substantially in the center of the&#39;body (11 of the apparatus are provided vertically juxtaposed casings or box-like structures (20) and (21) in which there are provided direct fire dryingzones (14) and (15), respectively, where upper and lower flame-ejecting burners (12) and (13) are arranged alternately in opposed relation with their jets directed toward the center, that is to say, toward the web passage, and hot air&#39;drying zones (18) and (19), respectively, where the series of hot air nozzles (16) and (17) are provided in vertically opposed relation, with their jets being also directed toward the center of toward the web passage. Said boxlike structures (20) and (21) are joined together by hinges (22) provided at the rear portions such that they are openable frontwise pivoted by said hinge means (22) and powered by an air cylinder (23) provided at the front side. In the surfaces of said upper and lower structures (20) and (21) are formed openings or windows (24) and (25), respectively, each of which is fitted with transparent heat-resisting glass through which the operator can inspect the condition of flames. At both ends of the upper and lower structures (20) and (21) joined together are provided elongated lateral slots one of which is disigned toserve as an inlet or feed port (26) and the other as an outlet or discharge port (27). The printing paper sheet or web (28) inserted through the inlet (26) travels along a passage indicated by arrows in FIGS. 1 and 4, that is, the sheet or web thus fed in passes first betweenthe flame-ejecting burners (12), (13) and then between the series of hot air nozzles (16), (17) in the respective casing (20), (21), and is discharged out of the casings through the outlet (27), and then said sheet or web further advances passing round the air-cooling delivery rollers (29) and is fi-. nally taken up on a taken-up device (not shown) provided outside of the apparatus. Above the assembly of said air-cooling delivery rollers (29&#39;) is provided a suitable air collector (30), and at the top of the extension of said air collector (30) is provided an exhaust fan (31) driven by a motor (32). Provided at the inlet of said air collector cylinder (30) is an air flow control valve (33) arranged to be operated from the outside of the apparatus so as to be opended or closed as desired.  
  In the lower part of the body (11) of the apparatus are provided a heating chamber (34) where hot air is produced and a fan (35 adapted to feed hot air at high speed. Said heating chamber (34) is provided with combustion burners (36), an outer air inlet (37), a discharge port (38) and a hot air return port (39). The arrangement and function of this hot air return port (39) will be further described later. Said combustion burners (36) and the aforementioned direct drying burners 12), (13) in the direct fire drying station are supplied with fuel through a same supply system, and they are mechnically or electrically incorporated in the apparatus such that their adjustment can be made by operating one of the adjusting wheel handles (40) provided at the front panel of the apparatus.  
 The hot air generated in said heating chamber (34) is forced out through the discharge port (38) and delivered at high speed by the action of the fan (35) into an air chamber (41). Said fan (35) is driven by a motor (42) which is connected to said adjusting wheel handle assembly (40) so. that its rotation can be suitably controlled by operatingsaid handles.  
  Said air chamber (41) is connected through holes (43) and (44) with the hot air ejection nozzles (16) and (17) in the upper and lower hot air drying stations (18) and (19), respectively. Said both stations are also provided with vent sleeves (45) and (46) both of which open sidewise into an exhaust cylinder (47). In the inside of said exhaust cylinder (47) is provided a partition wall (48) whereby a major portion of the hot air flown into said cylinder from ventilators (45) and (46) is obstructed from advancing further on and is forced to flow back into a refluxing chamber (49) which is provided with a refluxing port (50) communicated with the aforesaid hot air return port (39) provided in the heating chamber (34), so that said major portion of hot air exhausted is returned back into the heating chamber (34).  
  In said exhaust cylinder (47) is also provided a suitable air exhausting fan (51) for adjustment of air to be exhausted. Supply of hot air and adjustment of exhaust air can be performed by operating one of the handle wheels (40) at the front panel of the apparatus, in the same way as described above.  
  As the web, which has been printed on both sides thereof, travels along a fixed passage in the drying structures and (21), it is first of all subjected to rapid heating through exposure to flames from the upper and lower burners (l2) and (13) and then undergoes heating with high-temperature high-speed hot air from the nozzle (16) and (17), so that the solvent gas is quickly isolated away from the printed faces of the web, and upon leaving the drying structures (20) and (21), it is immediately passed round a series of cooling rollers (29) to trace a zigzag course, during which periodthe web is exposed to air stream flowing into the air collector (30) to receive a favorable cooling action, and then the web is finally wound up by a suitable takeup means. In the meanwhile, the hot air, which has been ejected from the respective nozzles (16) and (17) and completed its drying action, flows through the respective upperand lower vent sleeves (45) and (46) and enters the exhaust cylinder (47) and refluxing chamber (49). Although a minor portion of said hot air is released to the outside according to the operation of the air exhausting fan (51), most of said hot air is blown back through refluxing port (50) and return port (39) into the heating chamber (34), thereby enhancing the heating efficiency.  
  While the invention has been described by way of illustrative embodiment, it will be apparent that various changes and modifications in its design can be made within the scope of the technical thought of the invention featured by provision of a direct fire drying station and a hot air drying station arranged in a single assemblage and by recirculation of hot air for re-use thereof.  
 What is claimed is:  
  1. A printed paper drying apparatus for off-set printing, comprising in combination: a pair of upper and lower drying box-like structures defining space therein having upper and lower direct-fire drying means respectively, for drying upper and lower surfaces respectively of a strip web conveyable therebetween; a hot air drying space means for providing hot air against the strip web, located serially after said upper and lower direct-fire drying means; roller-assembly and aircooling means defining an air cooling space in juxtaposition to and next in flow series after the hot air drying space means; a vented air collector collection means including a collection space and an exhaust fan mounted therein operatively connected in flow series communication with an upper portion of the air cooling space for variably adjustably controlling exhaust air from the air cooling space; an air heating chamber means for heating air within a chamber space thereof, and mounted in communication with the air heating chamber means chamber space there being an air heating chamber fan for force circulating hot air from the chamber space to a lower portion of said hot air drying space means; and air flow-recycle means including outlet vents to said hot air drying space means and conduit structure providing for recycling the flow thereof to the air heating chamber means; said upper and lower direct-fire drying means comprising opposing serially alternately spaced flame-ejecting burners positioned to alternately and serially expose opposite faces of a strip web to direct flame; said hot air drying space means providing a series of opposingly-directed and axiallyaligned substantially coaxially to one-another upper and lower hot-air-ejection nozzles arranged for simultaneously directing hot air onto upper and lower strip web faces; and hinge means pivotably hinge-mounting the pair of drying box-like structures at corresponding edges thereof for the opening and closing of one relative to the other, and including jack means connected between opposite-side edges of the pair of drying boxlike structures opposite from the hinge-mounted hinge means, for opening and closing&#39;one relative to the other of the pair of drying box-like structures.