| 摘要 |
<p>A pump (10) has a housing (11) formed with a chamber (29), a spindle (12) extending through the chamber and mounted for rotation in bearings, and an impeller (14) mounted on the spindle for rotation therewith. The impeller consists of two parts (15, 16) having facing surfaces (17, 18), the surfaces being accurately formed with open channels (19, 20) and the two parts being connected by a joint (21), so that the channels combine to form passages (22). The joint is formed by pegs (23) extending through bores (38, 39) in the two parts, the pegs secured by an electron beam weld (24). A method of forming an accurate internal passage in a pump element, includes the steps of forming (31) the element in two parts having accurately-formed channels in facing surfaces, providing (33) congruent pairs of bores through the two parts, inserting (35) a beveled peg through each congruent pair of bores to form an annular groove between each bore and a corresponding end of the respective bore, and forming (37) a weld in the said groove by use of an electron beam.</p> |
