US2410201A

US2410201A - Plate steel casing joint for rotary hydraulic machines

Info

Publication number: US2410201A
Application number: US532899A
Authority: US
Inventors: Joseph F Corby
Original assignee: Baldwin Locomotive Works
Current assignee: Baldwin Locomotive Works
Priority date: 1944-04-26
Filing date: 1944-04-26
Publication date: 1946-10-29
Anticipated expiration: 1963-10-29

Description

oct. 29, 194e. J F, CORBY 2,410,201

PLATE '-'STEEL CASING JOINT FOR ROTARY HYDRULIC-MGHINESv Filed April 26,1944

Il N Patented ct. 29, y:19426K This invention relates to plate steel volute casings for rotary hydraulic machines such as hydraulic turbines and pumps.

When volute casings are used under certain heads considerable diiiculty is frequently experienced in obtaining proper flow velocity conditions within the casing primarily because of the inability to have'certain portions of the plate steel casing of sufficiently small radius of curvature at the points where the casing joins the usual stay vane ring especially at the small cross-sections of the casing. This difficulty has heretofore arisen because of the necessity to provide an extended straight portion of the plate steel casing adjacent the stay vane ring in order toemploy usual 4riveted butt straps on each side of the 'casing joint and thereby place the rivets in double shear.

Itis an object of my invention to provide an improved combination of elements whereby a plate steel casing of a rotary hydraulic machine may have a relatively small radius ofcurvature adjacent the stay vane ring and particularly at the small cross-sections of the casing, in the case of a volute, where the problem of making small radii of curvature is particularly acute.

Another object is to provide an improved combination of elements for obtaining small radii of curvature, of a plate steel casing,.adjacent the stay vane ring and still cause the rivets tobe in double shear.

Other objects'and advantages will be more apparent to those skilled in the art from the following description of the accompanying drawing in which:

Fig. 1 is a partial sectional view through a casing and a portion of a hydraulic turbine;

HYDRAULIC Corby,. Philadelphia Pa., `assign otiye Works', afcrporatin G JOINT?FSI?3 Applicatiorinpm c, 194.4;y 'zel-assi (ci.44V

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Fig. 2 is anenlarged fragmentary sectional view V of the casing joint shown inFig. 1; and

Figs. 3 and 4 areV enlarged sectional views showing modied forms of arrangements by placing the rivets in double shear.

The particular embodiments of the invention disclosed herein have been applied for purposes of illustration to a Francis type hydraulic turbine including a runner I, adjustable guide vanes 2 and stay vanes 3 which are secured at their upper and lowerends to flow guidingportions 4 and 5 extending as a'surface of revolution around the runner axis. The stay vanes and portions 4 and 5are usually cast'integrally from a stay 'vane ring. A plate steel casing 6, generally of volute form, well-known in the art, is usually riveted to the edges of the stay ringk elements 4 and 5. In order to allow the casing to start its curvature 'I as close as possible to the edge 8 of the guide vanes Ypoint 2| about No states-' i 'Y D 3 and at the same time place the rivets under double shear, I machine a groove 9 and a small rib I0 circularly around the stay vane ring preferably on the uppermost and lowermost surfaces of the respective walls and the plate metal Il of the casing is tted against the rib I0. A rivet strap I2 is anchored to the ring by being provided with a circular key I3 which fits into the keyway 9.' Rivets I4 .extend through the stay vane ring, plate and strap I2 and are placed in double shear by reason of the strap I2 being keyed to and forming in elect a rigid part of the stay ring structure itself. Hence, when the casing is subjected to internal water pressure so that the plate I I is placed under tension the load will be transmitted directly to the stay ring through the rivets and to the plate I2 which in turn transmits the load to key I3 and thence to the stay ring. LIn this manner it is possible to eliminate the excessive space that is normally required to produce a double strap riveted joint which has been necessary in order to place the rivets in double shear. Hence, with my improved arrangement, it is possible to obtain more ideal flow conditions within the casing particularly at the'small cross-section because of the ability to start a small radius of casing curvature close to the stay vanes.

The modification shown in Fig. 3 allows the curvature of the casing to start very abruptly adjacent the stay vane ring plished by providing a plate metal supporting Seria surface I8 of sulicient depth on the stay ring so that the plate metal casing 20 extends to a midway of the radial depth of the guide vane I9. To provide a rm anchor for the'rivet strap 22 it extends inwardly over the whole of the upper end of the stay vane ring with a substantial flanged end of key 23 which overlaps the inner edge 24 of the stay vane ring. Rivets 25 secure the component elements together and the rivets are placed in double shear by virtue ofplate 22 being anchored at 23 and 24. The lianged end 23 of the strap plate is fitted within the corner 26 of the head cover -21 well-known in the art. f

In the modification shown in Fig. 4, the casing plate 30 is placed on the inside of the stay ring 3I while a rivet strap 32 has a key 33 seated in a circular keyway of the stay vane ring. The

From the foregoing disclosure of the several` modifications, it is seen that I have provided an I1, this being accom-V the art Without departing from the spirit of the I invention as set forth in the appended c1aims.,.

I claim:

1. A rotary hydraulic apparatus comprising, in combination, a stay vane ring and .a volute plate steel casing therefor having certain small sections that are relatively small compared to others, said stay vane ring having a portion overlapping one side of said plate steel casing near its edge portion, a rivet strap overlying the other side of the Vplate steel casing, and means for anchoring said strap to the stay vane ring by a direct abutting contact with a transverse surface on said ring whereby rivets extending through said strapy plate and ring will be placed in doubleshear to provide'necessary strength and to allow curvature of the casing at its small sections to start adjacent the stay ring thereby to obtain more desirable flow conditions through the volute casing.

2. The combination set forth in claim 1 further characterized in that a head cover is provided with a recess to receive said stay vane ring, and

said ring has an annular ledge at its innermost edge and the strap has a flanged portion seated in saidvrecess and overlapping and engaging said edge.

JOSEPH F. CORBY.