This patent document describes improvements to sealing glands for rotating machines using sintered metals. It discusses how sintered forms of metal like iron or nickel rub away more readily with less heat generation than cast or wrought metals when used in sealing glands between a rotating shaft and surrounding casing. The invention involves using sintered metal for one or both of the parts in a labyrinth gas gland that are liable to rub against each other.
1. * GB780038 (A)
Description: GB780038 (A) ? 1957-07-31
Improvements relating to sealing glands for rotating machines
Description of GB780038 (A)
PATENT SPECIFICATION
Inventors: LEONARD ELLIS BENSON and THOMAS RAINE Date of filing
Complete Specification Oct. 4. 1955.
Application Date Oct. 18, 1954.
Complete Specification Published July 31, 1957.
Index at acceptance:-Class 122(5), B13(B1A: Cl: C6).
780,038 No. 29952154.
International Classification:-FO6j.
COMPLETE SPECIFICATION
Improvements relating to Sealing Glands for Rotating Machines We,
METROPOLITAN-VICKERS ELECTRICAL COMPANY LIMITED, a British Company
having its registered office at St. Paul's Corner, 1-3, St. Paul's
Churchyard, London, E.C.4, do hereby declare the invention, for which
we pray that a patent may be granted to us, and the method by which it
is to be performed, to be particularly described in and by the
following statement:-
This invention relates to machines having relatively rotating parts
and is concerned with effecting gas sealing.
The invention has an importarnt application inter aria in steam
turbines, gas turbines and electricity generators.
In known types of seals between a rotating shaft and a surrounding
casing one or more glands are provided. Each of these glands comprises
a series of circumferentially extending grooves or ribs forming part
of the shaft or the surrounding casing or both. Alternatively the
grooves or ribs may be formed on a sleeve attached to the shaft.
Clearance between the fixed and moving members is small so, as to
hinder the passage of gas along the shaft. The members are grooved or
ribbed in such a way as to provide a labyrinth with a multiplicity of
sharp edges and fine clearances to hinder the escape of gas. The
clearances should be as fine as possible without actually rubbing
2. together but if the two members do rub together it is desirable that
one or both should wear away quickly and with the minimum generation
of heat. If this does not happen the rubbing may cause serious damage
and the generation of heat may cause undesirable distortion.
The materials from which gland members have usually been made hitherto
are metals such as steel, brass or bronze which are produced either as
casings or wrought by conventional means into the form of forgings,
bar, tube. sheet and strip.
The present invention comprises a labyrinth gas gland between
relatively rotating parts in which one or both of the parts liable to
rub against each other are of a sintered metal.
[Price 3s. 6d.] It has been found from experiment that sintered forms
of metal, as distinct from cast or wrought metals have the advantage
that they 50 rub away more readily with less generation of heat due to
friction than in the case of cast or wrought metals.
Suitable materials are sintered iron, sintered nickel or other
sintered metal or alloy. 55 Preferably the sintered materials used are
not completely bonded, i.e. they are incompletely sintered forms of
the materials, in which the bonding of the particles is not complete.
60 Sintered forms of iron should be satisfactory for gland materials
operating temperatures up to 750 -850 F. but for higher temperatures
where greater resistance to oxidation may be necessary other sintered
materials would be 65 preferred, for example, sintered nickel
containing graphite or sintered alloys such as nickel-chromiunm,
nickel-cobalt, nickel-cobaltchromium, or such alloys containing
graphite.
The accompanying drawing shows an 70 example of apparatus embodying
the invention in which sealing is effected between a rotating shaft 1
and a stationary casing 2 which may for example be the casing of a
turbine. Gland segments of sintered metal 3 are supported in 75
grooves 4 in the casing 1. In the example shown the gland segments are
shown with sharp edges 5. Leaf springs 6 hold the segments 3 downwards
towards the shaft 1.
With metals as used hitherto when rubbing 80 occurs the metal melts
and in the case, for example, of a gas turbine this will allow escape
of the hot gases and the heat may cause distortion of the shaft. A
sintered metal, on the contrary, will wear sufficiently to avoid 85
rubbing but not sufficiently to cause escape of the gases.
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