| 摘要 |
An apparatus for use in machining and statically balancing a large and heavy workpiece such as the runner of a hydraulic turbine. The apparatus includes a vertical center support column on the upper end of which is mounted a rotatable turntable. The workpiece which is to be machined and statically balanced is suitably clamped to and rotates with the turntable, the workpiece extending radially beyond the turntable so that as the turntable is rotated the workpiece is moved past a machining tool which is suitably supported along the path of rotary movement of the workpiece. The turntable is detachably secured to a composite member which comprises a bearing, such as a roller bearing, integral with a gear, such as an internal ring gear, the composite member being in underlying relation to the turntable. A pair of diametrically opposed rotary hydraulic motors are housed within the center support column, each hydraulic motor rotatably driving a pinion gear which meshes with the internal ring gear of the composite member secured to the underside of the turntable, whereby to rotatably drive the turntable. A hydraulic cylinder is carried by the center column, and a piston movable within the hydraulic cylinder is rigidly connected to the turntable. The hydraulic cylinder may be continuously pressurized while the turntable is rotating during the machining operation whereby to exert an upward force on the turntable sufficiently to relieve a predetermined amount of thrust load on the bearing and thus whereby to make a greater part of the rotative power applied to the turntable available for the machining operation. Upon the completion of the machining operation, when it is desired to statically balance the workpiece, the composite member comprising the bearing integral with the gear is detached from the turntable, although the composite member remains in underlying relation to the turntable. For the static balancing operation, the turntable with the workpiece, such as the runner of the hydraulic turbine, still secured thereto, is then elevated by means of the attached hydraulic piston sufficiently to clear the centering joint with which it normally engages the composite bearing and gear. Any improper weight distribution of the workpiece will cause a tilting of the piston in the hydraulic cylinder together with a tilting of the attached turntable and of the workpiece mounted on the turntable, such tilting being sensed by machinist's levels or the like temporarily positioned on the workpiece. An appropriate compensating weight or weights is/are then permanently added to a circumferentially-extending weight pocket on the workpiece whereby to correct the detected improper weight distribution of the workpiece. |
