Patent GB-297794-A (GB)
Title: Improvements in or relating to glass working machines
IPC: C03B11/02
Filed: 1928-08-03
Abstract: 297,794. Whitall Tatum Co., (Assignees of Headley, B. T., Du Bois, D. I., Koob, B. H., and Lobb, F. H.). Sept. 28, 1927, [Convention date]. Pressing.-A press, particularly intended for making electric insulators having an internal screw thread as shown in Fig. 26, comprises a number of moulds mounted on a rotary table, and each mould is provided with a plunger, or plug, which is forced into the mould by a press head and is afterwards screwed out of the finished article by a separate device, the article being left in the mould ready to be removed by a take-out device. The formation of a glass article is illustrated diagrammatically in Fig. 1, which shows the operations carried out at a number of the. stations to which a mould is carried by the rotation of the machine table. At station b, the mould 2, 3 receives a charge G of glass from a feeder, a guiding-funnel 5 being used to direct the charge into the mould. A mould head 4, pivoted above the mould, carries a screw-threaded plug 32 which presses the glass and forms the internal screw thread. At the next station, c, the mould head 4 descends on to the mould and the article is formed by means of a press head 6, operated by a compressed air cylinder, which forces the plug 32 into the mould. At the next station, d, the mould is brought under a chuck 83 which screws the plug out of the mould. At station e, the mould head is swung upwards, and at station g the finished article A is removed from the mould by a take-out device 8 and is deposited on a conveyer belt c. The moulds are each made in two parts 2, 3 hinged together and mounted on the table 13, Figs. 2 and 3, which is rotated step-by-step about a central column 10 by means of a compressed air cylinder 140. The moulds are opened and closed by cams fixed to the central column, and when beneath the press head, the halves of a mould are clamped together by means of a toggle clamp 36 which engages lugs on the mould and is actuated by an air cylinder 34. A mould head 4, pivoted above each mould, carries a housing 108 through which a press plug 32 slides. The plug is formed with a thread of the pitch required in the finished article, and it engages two worm wheels mounted in the housing 108. The wheels are free to rotate but are braked by spring-actuated friction plates. They rotate when the plug is thrust downwards by the press head, but the braking force is sufficiently great to prevent them from moving when the plug is rotated to screw it out of the mould, so that removal of the plug does not put any strain on the thread formed in the glass article. The mould heads are moved to and from the moulds by means ol slides operated by cams on the central column 10. The press plugs are forced down into the moulds by an air cylinder 44, secured to a framework 19, 21, its piston rod 46 carrying a press head 47. When the press head rises, after a downstroke, the plugs 32 are left in the moulds, which are then carried by the table beneath the screw-out mechanism. This consists of a chuck 83 carried at the lower end of a rod 82 which is reciprocated by an air cylinder 86. The cylinder lowers the chuck so that it engages the upper end of a plug 32, and another air cylinder 71 then moves a rack 74 which causes rotation of the rod 82 and thus screws the plug out of the mould. The chuck then rises, the mould head 4 is swung upwards as the table carries it away from the screw-out mechanism, and the mould is opened and brings the finished article into position to be removed from the machine. The take-out device consists of fingers 136 carried by a rack 121 which slides through a rotary frame 122. An air cylinder 131<1> first causes the rank to move inwards so that the fingers 136 engage the finished articles, then rotates the frame so that the article is swung in a vertical plane from the mould to a conveyer belt, and finally withdraws the fingers and swings them back to their original position. The machine is preferably operated by compressed air, and timing valves are provided to synchronize the different movements of the machine. Safety devices are provided to prevent damage in the event of the failure of the air supply or of the moulds being jammed by pieces of glass.