Patent GB-616292-A (GB)
Title: Improvements in or relating to methods and means of coating explosive charges
IPC: F42B33/14
Filed: 1946-03-20
Abstract: 616,292. Explosive charges. SHACKLETON, J., SEELEY, F. H., ATKINS, A. A., GIBSON, W. H., DELPH, A. E., and COTTERILL, E. March 20, 1946, No. 8656. [Class 9 (i)] [Also in Group XXV] The curved surface of a cylindrical explosive charge 6 is covered with a bonding composition comprising an adhesive base and a volatile solvent, and then wrapped in a plurality of layers of a fabric sheet, carrying on one or both faces an adhesive dope, while the bonding composition is still tacky, two knurled and polished metal rollers 1, 2, carried on a frame, being connected to a driving pulley 3 and supporting the charge 6. A rubber-covered pressure roller 7 slidably mounted on the frame is adjustable by a hand wheel. Sheet fabric 8 fed from a roll on a spindle 9 passes around a rubber-covered tensioning roller 11 loaded by a weight 13. A guillotine for cutting the fabric sheet is placed level with the support rollers. The displacement of the pressure roller during the wrapping process may trip a switch cutting off the power source from the driving pulley. A guide placed below the support rollers has two arms extending upwards which bear against the plane ends of the charge to maintain it in position. One arm is manually adjusted and the second moves into position under the action of a spring as the pressure roller is brought to bear on the charge. The fabric sheet may pass over a steel shaft and be trimmed to the width required by a plurality of adjustable hardened steel cutting shears. The invention is described applied to a cordite charge, diameter 4.3 ins., with an axial passage of star-shaped section, and composition nitrocellulose (12.2 per cent N.) 49.5 parts, nitroglycerine 41.5 parts, diethyl diphenyl urea 9.0 parts, all parts being by weight. A bonding composition of manila copal gum 6 lbs., acetone 4 pints, cyclohexanone 4 pints, castor oil ¢ pint, is painted on to the charge. Fabric sheet woven with a warp of 84 threads per inch 20's American cotton and a weft of 40 threads per inch of 8's American cotton is doped on both surfaces with an adhesive consisting of whiting 59 parts, re-washed scrap rubber 21 parts, whole tyre reclaim rubber 15¥ parts, and " Tackol " 4“ parts by weight. The roll of fabric is placed on the spindle, with the free end across the support rollers. The bonding composition is painted on to the charge which is then placed in position on the fabric-draped rollers and the free end of the fabric wrapped round the charge. The pressure roller is lowered and the support rollers set in motion, the speed being increased gradually. Wrapping is continued until the overall diameter of the charge is 4.65 ins., when the switch is tripped and the fabric cut transversely close to the rollers. Further rolling secures the end of the fabric and excess coating at the ends of the charge is trimmed off. In an alternative method, the bond composition is applied to the doped fabric on a platform attached to the machine. Alternatively, both the charge and the fabric may be painted with the bonding composition. It is stated that charges coated according to the invention withstand storage under temperatures varying from 32‹ to 90‹ F. Specifications 26430/07, [Class 9], and 489,279 are referred to.