Patent GB-745280-A (GB)
Title: Packaging machine of the volumetric filling type
Inventor: HOWARD THOMAS PARKER
IPC: B65B1/44
Filed: 1953-11-13
Abstract: 745,280. Automatic weight control systems. PNEUMATIC SCALE CORPORATION, Ltd. Nov. 13, 1953, No. 31587/53. Class 38 (4). In a machine for filling cartons 60, Figs. 1 and 2, moved along a conveyer 74 by a flexible belt 76 having a series of spaced blocks 78 attached thereto, material is delivered from a non-rotary hopper 10 which co-operates with a series of measuring chambers 14 mounted on a plate 18 revolving beneath the hopper and arranged to be telescopically adjustable in accordance with the weight of a measured load as tested at one point in the revolution by a weighing apparatus 70. The stationary hopper 10 is an irregular shape having one wall 11 of radius sufficient to embrace a number of chambers 14 to cause filling as they pass beneath the hopper whilst a wall 13 is of smaller radius so that, after filling, the chambers pass outside the hopper to permit release of the material into their corresponding containers. Each chamber has a valve 36 which is operated by a cam surface 48 on the machine frame so that the chambers may be filled and emptied at the appropriate points in the revolution. All of the measured loads are released into successive containers through funnels 62 except one which is delivered into container 68 of the weighing apparatus 70, the load after test being released into a second container 72 by a valve 400 operated by a cam 410 co-operating with a follower 408. Finally this load is released into a carton 60, during a subsequent revolution of the filling unit, by a valve 412 operated by a cam 416. The conveyer and measuring chambers are rotated by an electric motor 90 driving a central shaft 34. When correction is necessary in consequence of deviation of the test weighing from normal, upper portions 16 of the measuring chambers are automatically adjusted to vary the volume of the chambers. The weighing apparatus is supported on a disc 66 secured to shaft 34 and comprises a pair of adjustably spring-loaded and dashpot damped cantilever springs (not shown) which support the container 68 and control the position of a valve relative to an air-jet 134, Fig. 15, supplied through a pipe 146 and a bore 154 in the central shaft 34. The pressure in the jet chamber, which is thus dependent on the weight is applied to a pressure amplifier 236, the output of which is applied through a bore 244 in shaft 34 to operate pressure-responsive switches 212a-212d which change over at different predetermined pressures. These switches are arranged so that if there is overweight or underweight a reversible electric servomotor (not shown) is operated in the appropriate direction to drive a plurality of screws to raise or lower a supporting ring 26 carrying track rollers 24 of plate 18 so as to adjust the relative position of the parts 16 of the measuring chambers. Switches 212a-212d are also arranged so that if the weight error is less than a predetermined amount in either sense the servomotor is run for one period of time whereas if the weight error is greater than this amount the servomotor is run for a longer period of time. These times are respectively determined by switches operated by cams 278, 276 on a shaft 270 driven from motor 90. During each alternate revolution of the rotary filling unit, the weighing apparatus is locked by pneumatically-operated stop 260 supplied through bore 424 in shaft 34 when a solenoid-operated valve 264 is energized by a switch 266 operated by a further cam 268 on shaft 270. During the next revolution of the filling-machine correction, if necessary, is initiated by a further cam 286 on shaft 270. Instruments 440, 442 indicate and record pressure and hence weight during each weighing, recording being controlled by a switch 462 operated by a cam 468 on shaft 270. Switches (not shown) are provided to change over from automatic to manual control of the servomotor.