GB812884A - Intermeshing screw pumps and the like - Google Patents

Abstract

812,884. Extrusion machines. IMPROVED MACHINERY Inc. Dec. 13, 1957 [Dec. 31, 1956], No. 38824/57. Class 87(2). [Also in Group XXVI] A screw press having intermeshing screws mounted in a casing between an inlet and an outlet has the screw-threaded members mounted for rotation in the same direction about skew axes 24, 26 the threads of each member being of the same hand and for at least one turn the crest of one thread 23 is deeply engaged in the trough of the other thread 25 or threads to provide fluid sealing. The members may have a generally cylindrical form or be conical as in Figs. 23, 24. For each member the pitch diameter surface PD, Fig. 2, lies on a hyperboloid and is obtained by rotating a work piece W, Fig. 18, on a lathe while cutting the thread along a line T by a tool skewed to the axis of the piece W at an angle ¢α, where α is the skew angle between the axes 24, 26, Fig. 1: The pump shown in Fig. 23 may be used for pumping liquid-solid mixtures, such as wool pulp, and has meshing screw members, 42, 44 in a housing 50 having an inlet 51 and an outlet 53. The members 42, 44 have input extension shafts 54, preferably with a screw conveyer 60 thereon, mounted in bearings 55 and provided with seals 56. Output extension shafts 62 extend through bearings 64 at the opposite end of the housing and are provided with seals 66 and a thrust bearing 68. Each shaft 62 is geared to a common driving pinion 67 through a universal joint 621 and a gear wheel 622. Preferably the conical screws 42, 44 are so mounted that the pumping space increases towards the outlet. The thrust balancing means includes a collar 70 on the shaft 62, which collar extends through the stuffing box 66 and is intended to counteract the thrust on the annular area of the screwthread due to the discharge pressure. To compensate for wear, the members 42, 44 may be adjusted axially relatively to the housing 50 be replacing shims 72 by shims of greater thickness. By mounting conical screw-threaded members 42, 44 with their smaller ends adjacent the outlet from the casing, the arrangement may be used as a press, Fig. 24, to force liquid out of a liquid-solid mixture. The housing 80 is provided with an inlet 82 and an outlet 84, and surrounding the screws has small apertures 81 for the escape of liquid. The screws are carried by shafts 86 mounted in bearings 87, 88 and driven as in Fig. 23.