Patent GB-667412-A (GB)
Title: Improvements in or relating to printing presses
IPC: B41F23/04
Filed: 1949-08-16
Abstract: 667,412. Printing-machines. ZIMMERMAN, R. G. Aug. 16, 1949, No. 21302/49. Class 100 (ii). [Also in Group XI] Drying - apparatus.- A dryer for a printed web in a printing-machine comprises a burner assembly which includes a number of burners arranged side - by - side, parallel to the run of the web, the burners being of refractory material and having metallic conduit means for directing combustible mixture thereto, and means including a water cooling line in intimate thermal contact with the conduit means for maintaining the conduit at a relatively low temperature. General arrangements. The drying-apparatus may be used, and is readily embodied, in a press for either newspaper or magazine printing, and comprises a number of box-like housings each arranged between a printing-unit. The valves controlling the supply of gas and flushing air, and the motor for retracting the burner assembly, are automatically and electrically controlled from the speed controller of the printing- machine in accordance with the web speed, and further manually-operated controls are provided, especially in the case of emergency stops. Dryer construction. Each dryer 34, Fig. 2, includes a burner assembly 40, enclosed in a boxlike housing 41, arranged parallel to the vertical run of the web 21 to be dried, a reflecting or back plate 61, and an exhaust duct 120. The burner assembly includes horizontal lines 51-60, Figs. 2 and 11, of vertically-spaced burners, each burner having a refractory face portion 70, Fig. 8, which is heated by a gas-air mix supplied from a rectangular tubular manifold 72, Fig. 6, through a stem 71. The burners are secured by metal walls 76, 77 to the manifold 72, and the latter is divided into sections each supplied with gas by a pipe 69 controlled by a valve 69a. The manifolds are all in thermal contact with a copper back plate 73 to which are sweated the convolutions of a cooling water pipe 74. Heat transfer is minimized by asbestos or other insulating material 78 and 83. The burner assembly 40 has end channels 62 including water cooling coils 64. Each burner line complete with pipes 69 is readily removable from the assembly. The reflecting plate 61 and the abutting side walls 87 are provided with water cooling coils 86, 88. The side walls 87 can be slid edgewise to provide access to the web 21 for threading and inspection. The burner assembly 40 is mounted on guides 90, Fig. 2, for movement through a range 91 by a motor 93, which is adapted to drive a shaft 95 connected by linkages to the burner assembly. An air pipe line 110 below the burner housing is adapted to blow air upwardly between the burners and the web under. conditions mentioned below. The exhaust duct 120 exhausts the cooling air and the products of combustion of the gas and ink solvent, and is formed to overlie a cooling drum 35 over which the dried web 21 passes. A set of exhaust apertures 122 is only opened when the burner assembly is moved away from the web. Air-gas supply to burners. Gas is supplied through a line 130, Fig. 11, and air through a line 133, to a line 140 into a header 142 which supplies all the burner manifolds. Valves 151- 160 control the burners, and valves 141, 131, control the header, and gas line, respectively. Dampers 134, 135 are adjusted by a combustion controller 136, and a valve 137 controls an air by-pass. The cooling air pipe 110 is controlled by a valve 149. To prevent " blow-back " in the burners, when the supply of gas is cut off, and to cool them, the burners 54-60 are connected to a source of compressed air through valves 164-170, these valves being electrically interlocked with the valves 154-160. Control of dryer from the operation of the printing-machine. The printing-machine motor controller has, for example, twelve speed settings or points, and these are arranged to control twelve contacts on an auxiliary contact drum which are in an electrical circuit comprising relays which control the supply of gas and air to the burner assembly, and the position of the burners relative to the web 21. The automatic control sequence on increasing web speed from rest is as follows :-First three lines of burners, 51-53, turned on, valves 137 and 149 closed, and valves 131, 141 opened: the valves 151- 153 are normally open. The burner assembly is then brought towards the web in three steps until the burners are within one and a half inches therefrom, at which time the web is moving at quarter full speed. Then, in turn, the valves 154-160 are turned to allow the progressive operation of the burner lines 54-60. The automatic control sequence on gradually decreasing web speed is as follows : -First, the valve 160 is closed, and the burner line 60 cooled by a discharge of air through valve 170. As the web speed is gradually decreased, the valves 159 -154 are progressively closed and cooled. The motor 93 is then operated to move the burner assembly to the fully retracted position: in this position the burner lines 51-53 are still lit. At this stage the operator can manually depress and hold a switch whilst decreasing the web speed by the controller, in which case the valve 131 is closed, valve 137 is opened to allow air to flush the burners, and the valve 149 in the pipe 110 opened to allow air to flow between the web and burners. If the above-mentioned switch is not kept manually-depressed, the flushing of the burners will be stopped, and the air line 110 operated earlier. The automatic control sequence during an emergency stopping of the machine is as follows :-The supply of gas is cut off, flushing air admitted to the burners, and the burner assembly retracted. At standstill, the flushing air is cut off, and the air blast from the pipe 110 turned on. Provision is additionally made for stopping the flushing air at any time and for turning on the air blast from the pipe 110 at the option of the operator.