GB816363A - Improvements in or relating to automatic powder-feeding apparatus - Google Patents

Abstract

816,363. Screw conveyers; jigging conveyers. WAHL, E. A. Sept. 16, 1957 [Nov. 6, 1956], No. 29119/57. Class 78 (1). Powder is fed from a container at a constant rate by a rotary screw that is subjected to continuous vibration during rotation and to the axis of which mechanical impacts are applied at regular intervals. The hopper 10, Fig. 1, is spanned by bars 14 which support a bearing 15 for the shaft 16 of the screw. A shell 18a having an open bottom is secured to the shaft and carries a triangular agitator 21. The screw 22, which is in the form of a spring, has its upper convolution welded to a bushing 23 which is fast on the shaft 16. The lower part of the spring fits closely into a tubular extension 12 of the hopper and closely surrounds an upwardly extending rod 27 which is coaxial with the shaft 16 but separated from it. A pin 26 is passed through holes in the rod 27 and the tube 12 and is engaged by the lowest convolution of the spring. During rotation the lower end of the spring rides up on the pin 26 thereby causing an axial compression of the lower convolutions. When the end of the spring clears the pin, the spring will snap back to its normal free position and in doing so will agitate the material. The hopper is vibrated continuously by an electromagnetic vibrator 29. In a modification, Fig. 5, the spring is replaced by a rigid screw 32, the shaft 31 of which has a threaded connection with the bushing 32<SP>1</SP>, which itself has a similar connection with the drive shaft 16<SP>1</SP>. A compression spring 35 is confined between cupshaped members 33, 34. The shaft 161 is mounted slidably in a bushing 15<SP>1</SP> which is supported by cross-bars 14 and has a cap 36 secured to its upper surface. The top of the cap is formed as a cam 38 which is engaged by a cam 40 secured to the driving pulley 18. The screw will rise slowly and drop sharply once during each revolution. The cams 36, 40 and the spring 35 can be replaced by a spring 42 which has one end secured to the shaft of the screw and the other end lying below the pin 26. In another modification, Fig. 8, the spring 35 is dispensed with and a weight 43 is added to the driving pulley 18 to impart a blow to the screw when the cam 40 drops sharply. This blow may be imparted to the bottom of the screw by arranging that the shaft 31 strikes the pin 26 before the cam 40 meets the cam 38. In a further modification the hopper, which has a wide outlet, discharges into a jigging trough in the bottom of which the screw, spring and cam mechanism shown in Fig. 5 is disposed horizontally. In the construction shown in Figs. 10 and 12, the hopper 75 is supported on a flat surface by a pair of curved metal bands 76 having rubber feet 77. The lower part of the hopper is surrounded by a flexible bellows-type boot 100 which is secured to the cover 99 of a housing 93. The housing is supported by a base 94 having rubber feet 95. The base supports also a speed-changing unit 91 and a housing 92 enclosing the gearing &c. A trough 101 disposed below the hopper has a tube 96 extending therefrom which contains a helical spring similar to the spring 22, Fig. 1, and acting similarly to the screw 32, Fig. 8. An electromagnetic vibrator 113 is secured to bars 112 which are secured rigidly to the trough bottom. The vibrator imparts vibrations to the trough at right angles to the axis of the spring. Specification 815,691 is referred to.