Patent GB-325717-A (GB)
Title: Improvements in methods and apparatus for producing double-walled glass containers
IPC: C03B23/13
Filed: 1929-03-13
Abstract: 325,717. Marks, Sir G. C., (American Thermos Bottle Co.). March 13, 1029. Forming vacuum flasks.-Relates to the method of making glass vacuum flasks which consists in nesting an inner cylinder having a contracted neck within an outer cylinder, supporting the cylinders in an inverted position, and heating the lower portion of the outer cylinder until the glass becomes plastic and fuses on to the lower edge of the inner cylinder to form a sealed joint. According to the invention, the heated lower portion of the outer cylinder is forced to assume the shape of the neck of the vessel prior to the formation of the sealed joint. Apparatus for carrying out the method comprises an horizontal frame or spider 2, Fig. 2, which is rotated intermittently by a driving shaft 15 through a Geneva gear 8, and is provided with a number of vertical hubs or bearing sleeves 32 arranged in a circle. An arm 34 clamped to each hub supports a vertical tube 36 which carries at its upper, end an horizontal ring 37 and also serves as a bearing for a shaft 41. A pinion 40, secured to the upper end of the shaft 41, engages a gear ring 39 which is journaled in the ring 37, and a pinion 57, secured to the lower end of the shaft 41, gears with a wheel 56 which has the same number of teeth as the ring 39 and is secured to a sleeve 55 journaled in the hub 32. Thus, rotation of the shaft 41 rotates the ring 39 and the sleeve 55 in unison with one another. The sleeve carries a vertical rod 64 which supports the inner cylinder X of a vacuum bottle, and a collar 65 which engages the neck of the cylinder and prevents it from moving sideways. The ring 39 carries the members 42 of a spring-operated chuck which holds the outer cylinder Y of the bottle. A cup 62 slides on the sleeve 55 and is connected by a pin 61, passing through a slit in the sleeve, to a rod 59 which slides within the sleeve. Thus the cup 62 is forced to rotate with, but is free to slide vertically on, the sleeve 55. The lower end of the rod 59 rests on a cam track 72 having a section that is raised and lowered periodically by a cam on the driving shaft 15, the cam being so shaped that the cup 62 is allowed to fall suddenly. The lower end of the shaft 41 also carries a pinion 58 which, when the frame 2 is stopped by the Geneva gear 8, makes contact with one of a number of horizontal rubber-covered friction wheels 76 driven in unison with one another bv a chain 81. Thus as the frame 2 is rotated step by step, the assembled glass cylinders X, Y are carried from one stopping-place to another and, at each stopping-place, they are rotated on their longitudinal axes by the contact of the wheels 58, 76. At each stopping-place, or station, the outer cylinder is heated over a horizontal zone by the flame from a gas burner. At two of the stations, the glass is shaped by carbon rollers 93, 94, Fig. 7, which are carried by horizontal arms 90, 91 respectively, secured to vertical shafts 88, 89. The vertical shafts are swung through an angle by cams on the driving-shaft 15 so as to bring the rollers, at the proper times, against the heated zones of the outercylinders. A pair of cylinders, assembled as shown in Fig. 2, with asbestos pads or spacers 69 between them, are placed by the operator on the rod 64 at station A. Fig. 7. and the chuck 42 is closed to grip the outer cylinder. The movement of the frame 2 carries the cylinders to station B where the flame from a gas burner 147 plays on the outer cylinder, the cylinders being rotated as a unit during this and each succeeding stationary position of the frame. The cylinders are next moved to station C where the glass is further heated by burners 149. At the next station, D, the glass is further heated by burners 150, 151, and the shaping-roller 93 is swung into contact with the outer cylinder and forms in it a waist 97, Fig. 2. While the cylinders have moved from station A to station D, the cup 62 has been lifted gradually by the cam track 72 until, at station D, it is in supporting contact with the lower edge of the outer cylinder. At the next station E the waist 97, formed by the roller 93, is further heated by burners 152, 153 and is given its final shape by the roller 94. At station F, sharp flames from burners 154, 155 play on a narrow zone of the outer cylinder and the pressure of the flames forces the soft glass of the outer cylinder into contact with the outwardly flared rim of the inner cylinder, as shown in Fig. 12, and fuses them together. The surplus glass 157 is cut off by the flame and is supporsed by the cup 62 until the movable section of the track 72 is suddenly dropped, carrying with it the cup 62 and the surplus glass. The welded cylinders are moved to station G where the fused edges are smoothed and made even by converging flames from burners 158. During this final smoothing, air under slight pressure is blown into the space between the cylinders through the aperture 71 that is formed in the outer cylinder for the attachment of the exhausting apparatus. The pressure of the air prevents the collapse or deformation of the fused joint. By dispensing with the shaping-rollers 93, 94, wide-mouthed food jars, which do not have a contracted neck, may be made on the machine. The cups 62 are not required in this case as there is no surplus glass to be removed.