GB874021A - Machine for moulding, shaping and trimming plastic products - Google Patents

Abstract

874,021. Injection moulding. PLASCO Ltd. April 22, 1958, No. 12717/58. Class 87(2). In a moulding machine wherein a moulded article e.g. a spool 20 is at a trimming station while another article is being moulded at a moulding station, the articles are moved from the moulding to the trimming station by means of a pair of transfer units 141, 142 each of which has a finger 143 for receiving a part of the article at the moulding station and for supporting it at the trimming station, means being provided adjacent the trimming station for stripping the part from the finger of each unit. As shown in Fig. 16 the spool 20 is moulded with an integral sleeve 34 surrounding the supporting finger 143 of one transfer unit 141, and with a gate portion 33. The portions 33 and 34 are removed at the trimming station by tools (as 182, 183, Fig. 24), and the sleeve 34 is then removed from the finger 143 by a stripper sleeve 194, Fig. 16, actuated by means of a compressed air cylinder 199. The transfer unit 141 is carried by a shaft 144, Fig. 15, slidably mounted within a shaft 145 carrying the other unit 142. The unit 142 moves in an arcuate path from the moulding to the trimming station and back again, but the shaft 144 is moved axially as well as rotated in order to by-pass the unit 142. The axial position of shaft 144 is controlled by a spring 153 and a cam operated lever 155 pivoted at 156. Rotation of shafts 144, 145 is effected through gear segments 147, 151 respectively pivoted on a shaft 149 and rotated by cam operated linkage 164, 165. Fig. 8, shows the spool 20 moulded on core units 27, 27<SP>1</SP> between dies 31. The cores 27, 27<SP>1</SP> are mounted on carriers 89, 89<SP>1</SP> (not shown) and moved towards and away from each other by means of cams (not shown). The carriers 89, 89<SP>1</SP> are water jacketed for cooling the cores. Pressure is applied to the cores during injection by means seen in Fig. 25, (not shown) to resist the injection pressure. The spool 20 comprises a barrel portion 22 connected to a centre tube 23 by circumferentially spaced end walls 24. The spool has enlarged rim ends 21 with recesses 25 formed by sleeve core portions 26, 26<SP>1</SP> of the core units which include core pins 28, 28<SP>1</SP> for forming the tube 23. At the ends of the tube 23 are flanges 29, 29<SP>1</SP> which are " formed " by means of tools 184, Fig. 24, during the trimming operation. The machine comprises two injection cylinders 68, 69, Fig. 4, carried by a frame 70 slidably mounted on rods 71. The cylinders 68, 69 have plungers 72, 73 which are brought in turn into register with a hydraulically operated plunger 74 for injection of plastic material through a passage 67 Fig. 8, into the die 31. This movement of the cylinders 68, 69 is effected by a cam 76 through a roller 79 and pivoted linkage 78, 80. Each die 31, Fig. 21, is adjustable in position in a die operating member 100 by means of a threaded rod 99 connected through gearing 102, 103 to a hexagon headed rod 104. The dies are opened and closed by cams (not shown), operating through pivoted linkage 121, 114, 112, Fig. 9, connected to a pivot pin 107 carried by a forked end 106 of the die member 100. An adjustable screw 110 cooperates with an air discharge 111 to stop the machine if the die is not fully closed. The link 121 inlcudes a heavy spring (not shown), to avoid breakage due to foreign particles between the dies. The dies are held closed under heavy pressure applied by a hydraulic cylinder 136 through a lever 116 pivoted at 117 a 115. During movement from the moulding to the trimming station a " flag " 32 of the gate portion 33 is adapted to be positioned momentarily between spaced pairs of air nozzles 179<SP>1</SP> and 180<SP>1</SP>, Fig. 6, so as to block the passage of air across the nozzle gaps, thereby continuing operation of the machine. If a flag should not appear at the proper time suitable controls act to stop the machine. The complete operation of the machine is automatically controlled by motor driven cams.