Patent GB-850227-A (GB)
Title: Improvements in or relating to the charging of hoppers
IPC: B65G47/00
Filed: 1956-07-27
Abstract: 850,227. Endless conveyer systems; hopper control. FOUNDRY EQUIPMENT Ltd., and BEECH, A. S. July 19, 1957 [July 27, 1956], No. 23342/56. Class 78 (1). In apparatus for feeding sand to foundry moulds a series of hoppers 11 supplying the moulds are kept filled with sand by a conveyer system including an endless belt 13 overlying the hoppers, and a series of retractable ploughs 14 which are selectively made operable to divert the sand into the hoppers. The conveyer system includes a supply hopper 33 supplying the belt 13, a mould conveyer 17 for passing the filled moulds through moulding, casting and cooling zones, a series of conveyers 24, 25, 27, 31 and 32 for returning sand tipped from the moulds after use through cleaning and sifting plant to the hopper 33, and a further conveyer belt 64 for returning any sand left on the belt 13 after passing the ploughs 14 to the hopper 33. A hopper 65 connects the remote end of the belt 13 with the return belt 64. A hopper 34 is also provided for introducing new sand into the system. Each plough 14 may be of one of two forms. In one form, Fig. 2, the plough is composed by a diagonal blade 35 secured to a frame 37 mounted for vertical sliding in blocks 38, 39. It is moved to and from operative position by a pneumatic cylinder 52 whose piston rod is pivoted to one end of a centrally pivoted lever 55 the other end of which is pivoted to the frame 37 at one end. Racks 47, 48 on the frame 37 meshing with pinions 45, 46 on a shaft 44 interconnect the two ends of the frame 37 for simultaneous movement. An adjustable stop screw 59 is carried by a bracket 58 secured to the frame 37 to determine the lowest position of the plough. This position is chosen for each plough such that when lowered a certain quantity of material remains on the belt so that succeeding ploughs are not starved. In the second form of plough, Fig. 4, a V-shaped blade 77 is carried by a frame 76 which is secured to a transverse shaft 75. A pneumatic cylinder 80 rotates one end of the shaft 75 through a lever arm 82 to move the plough to and from operative position, whilst an adjustable stop screw 84 on the conveyer frame cooperates with a second lever arm 83 to limit the movement of approach of the plough to the belt. In either construction, there are provided one or more deflecting blades 60, 86 respectively, which are disposed immediately behind the plough to deflect material remaining on the belt 13 inwardly away from the belt edges, and so prevent spillage. The ploughs are selectively operated by a control circuit such as that shown, Fig. 5. Each hopper 11 has a low-level probe 90 and a high-level probe 91. These are connected via respective electronic relays in a box 94 to respective fixed contacts 111, 112 of a multi-bank switch. Further fixed contacts 119, 120 and 121, 122 are connected respectively to solenoids 97 and 104 for performing left and right movements of a shuttle valve supplying air to one or other end of the cylinder associated with the respective plough blade 35 or 77. Also, fixed contacts 113, 114 are connected via separate on-off switches 106, 107 to a source of potential. The arrangement of the moving contacts of the switch is such that the multibank switch can be set to a number of positions, one causing the solenoids 97, 104 associated with all of the ploughs to be controlled by the respective probes 90, 91 in the hoppers, one in which these solenoids are operated manually by the switches 106, 107, and a further series of positions in each of which a selected one of the ploughs has its associated solenoids 97, 104 operated manually by the switches 106, 107 while the remaining ploughs have their associated solenoids controlled by the probes 90, 91 in the respective hoppers 11. An alternative control circuit (Figs. 6-8, not shown) may be used to avoid the use of a complicated multibank switch where a large number of hoppers 11 are used. This consists essentially of a series of electronic control circuits associated with the various hoppers each determining the operation of a plough-operating solenoid, the plough being moved from operative position by a spring or weight upon de-energization of the solenoid, and interconnecting circuits incorporating contacts of the various control circuits connected in series, the arrangement being such that in operation the hoppers are first filled in sequence up to the low-level probe, after which the further filling of the hoppers is controlled by the highlevel probes. By this arrangement should the level in any hopper fall below that of the low. level probe control by the high-level probes is discontinued and that hopper has priority and receives material until it is filled up to the lowlevel probe. An overriding manual control switch is also included in this circuit.