Patent GB-795209-A (GB)
Title: Improvements in or relating to machines for making buttons and other articles from plastic materials
IPC: B29C43/00
Filed: 1955-12-13
Abstract: 795,209. Rotary-table compression moulding machines. MESA, A. Dec. 13, 1955 [Aug. 4, 1955], No. 35812/55. Class 87(2). A machine for continuously moulding plastic articles, e.g., buttons, comprises tablet forming dies and article forming dies mounted on a continuously moving carriage and means for feeding moulding powder to the tablet forming dies, for transferring tablets from the tablet forming to the article forming dies, and removing the formed articles from the latter dies, respectively. Tablet forming dies 33, 17, Fig. 8, and button forming dies 15, 16 are mounted in concentric circles on a carriage 7 rotatable about a hub 67 on which it is supported by radial arms 77. Moulding powder is delivered to the dies 17 via a hopper 28, Fig. 4b, and a regulating device 23 comprising a baffle plate diverts surplus powder into a collecting funnel 29. To control the size of the tablets a push rod 11 forming the base of each die 17 is raised by a cam 12, Fig. 16a, when the die 17 is beneath the regulating device 23, and the cam 12 is vertically adjustable by rotating an eccentric 19g in a bearing ring 19f pivotally connected to a vertically slidable member supporting the cam 12. The filled dies 17 are carried by the carriage 7 beneath a roller 21, Fig. 3, which applies pressure through push rods 32 to the dies 33 to form the tablets. The roller 21 is carried by a pivoted crank 41c, 41d, Fig. 30, through which pressure is applied to the roller 21 by a spring 41a. The applied pressure may be varied by adjusting the height of roller 20 which supports each die 17 at the pressure applying position. The closed dies 17, 33 are revolved by the carriage through 180 degrees to a position where the push rods 32 are raised by a cam 51, and the tablets ejected by the raising of the push rods 11 by a cam (not shown). The ejected tablets are guided by baffles 42<SP>1</SP>, 42<SP>2</SP>, 42<SP>3</SP>, Fig. 21, into the path of fingers 24a, carried by a disc 24, rotated by the engagement of the fingers by pegs 38 on the periphery of the carriage 7. The fingers 24a slide the tablets over a plate 42 into the lower button forming dies 16. The upper button forming dies 15 have stems 52 raised by cams 50 in co-operation with rollers 49 to permit entry of the tablets into the lower dies 16, and on leaving the tablet-receiving position the cams 50 allow the dies 15 to lower, and pressure is applied to form the buttons by a roller 44 carried by a spring pressed pivoted bell crank, the pressure of the spring being adjustable. The dies 15 are locked in their lowered position, by the engagement of a projection 49k with a spring-pressed latch 46n, whilst the carriage 7 rotates through about 200 degrees, during which period the dies 15, 16 are heated by electric heating elements connected to contact rings 78, Fig. 2, which rotate with the carriage and engage stationary brushes 79 supplying current. At the end of the heating period the latch 46n is disengaged from the projection 49k by the actuation of a releasing lever 47 by a cam 48. The dies 15 are now raised by cams 50, the buttons being held in the die elements 56, Fig. 11a, of the dies 15 until they are ejected by pins 55. The latter have heads pressed by springs 55s against a movable plate 54, which on the raising of the dies 15 engages two stop pins 53 fixed to the carriage 7, so that the die elements 56 move upwardly relatively to the pins 55 which thereby eject the buttons. The ejected buttons are guided by a fixed plate 27 into a shoot 26, in which clogging of the buttons is prevented by an air blast.