Seal for a joint or juncture – Seal between relatively movable parts – Circumferential contact seal for other than piston
Reexamination Certificate
1998-08-12
2001-06-26
Knight, Anthony (Department: 3626)
Seal for a joint or juncture
Seal between relatively movable parts
Circumferential contact seal for other than piston
C277S644000, C277S916000, C277S940000, C277S941000, C277S943000
Reexamination Certificate
active
06250643
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a damper plate and a method for producing the damper plate, and more particularly to a damper plate used in a gap between an impeller and a casing, as a thrust pad or a radial pad of a slide shaft bearing, or at a sealing surface of a floating seal device in a rotary machine such as a pump.
2. Description of the Related Art
A damper plate is used in a rotary machine to reduce the amount of fluid leakage between a rotating body and a stationary portion so as to increase efficiency of the rotary machine and provide a cushioning or bearing effect to decrease deflection of the rotating body. Thus, the damper plate is required to be tough enough to withstand a contact with the rotating body which rotates at a high speed. The damper plate is also required to have accurate polygon patterns which perform the cushioning effect in response to the deflection of the rotating body. Also, the damper plate is preferred to be formed in a thin plate so that it can easily bend to fit a curved surface for easy mounting.
One of the examples of such a damper plate is a honeycomb plate shown in
FIGS. 6A through 6D
, having a plurality of convexoconcaves of a hexagonal cross-section. Conventionally, the honeycomb plate is produced by one of the following methods:
(1) Machine processing using a three-dimensional processing machine
(2) Etching process using a thin film mask having a plurality of polygonally patterned holes attached on the metal plate
(3) Laser beam processing using the energy of a laser beam
Since it is difficult to shape convexoconcaves by one step with this method, the plate is first processed to have holes and then incorporated with a bottom plate by brazing or other adhering methods.
(4) Blasting method using a mask
A thin film mask has a plurality of polygonal holes and is secured to the metal plate, in the same way as the etching method. Blasting particles are ejected to define convexoconcaves thereon.
However, each of these methods has the following disadvantages:
(1) Machine Processing
Since fine processing is required, a tool used in the processing is easily worn out and a processing time is long.
(2) Etching Method
Since a periphery of the hole is also etched through the process, the accurate polygonal patterns cannot be achieved. Also, in order to perform a uniform etching, the selection of material is limited.
(3) Laser Beam Machining
A number of steps are required and the cost is expensive.
(4) Blasting Method
Since the thin film mask is also exhausted by the blasting, the processing can be performed only while the thin film remains, and thus deep concaves are difficult to be defined. Also, since a hard or tough material cannot be processed, the materials useable in the process are limited.
For the foregoing reasons, there is required to provide a practical method for producing a honeycomb-type damper plate with a high dimensional accuracy and reasonable cost. Particularly, when a dimensional accuracy is not established, the gap between the damper plate and the rotating body needs to be larger to prevent contacts or galling therebetween. In this case, the rotary machine having a high performance and less vibration cannot be provided by employing the advantages of the honeycomb plate.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a damper plate for a rotary machine and a method for producing the damper plate which makes it possible to produce a honeycomb-type damper plate having accurate dimensions and reasonable cost.
According to a first aspect of the present invention, there is provided a damper plate for sealing between a rotating portion and a stationary portion of a rotary machine and cushioning the rotating portion comprising: a superplastic material plate; and a plurality of convex portions and concave portions defined in the superplastic material plate, the plurality of convex portions and concave portions being formed by a superplastic processing method.
According to a second aspect of the present invention, there is provided a method for producing a damper plate for sealing between a rotating portion and a stationary portion of a rotary machine and cushioning the rotating portion comprising the steps of: preparing a superplastic plate; and defining a plurality of convex portions and concave portions in the superplastic plate by a superplastic processing method.
In the above invention, the superplastic material may be selected from the group consisting of austenitic stainless steel, two-phase stainless steel, aluminum alloy, titanium alloy and ceramics.
According to the present invention, the damper plate having polygonal patterns such as the honeycomb patterns, which is difficult to produce in the conventional methods, can be produced with accurate dimensions and reasonable cost. As a result, the present invention contributes to the improvement in the performance of the rotary machine. Further, since a wide variety of materials can be used in the process, a material of the desired hardness or softness can be selected to differentiate with the counter material. Thus, when an impeller of the rotary machine contacts the damper plate, excess galling can be avoided. Moreover, by joining a plurality of damper plates having the same patterns, it is possible to cover a desired surface of a complex shape. Thus, the present invention permits the damper ring of the rotary machine to provide a bearing effect. As a result, an industrial machine can be miniaturized and be light-weight.
The above and other objects, features, and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings which illustrate preferred embodiments of the present invention by way of example.
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F.R. Mallaire et al., “Evaluation of Wear Ring Seals for High-Speed, High-Pressure Turbopumps”, Transactions of the ASME,Journal of Lubrication Technology, Jul. 1969, pp. 438-450, Figs. 18-20.
Kaneko Atsushi
Ogawa Toshiyuki
Takayama Hirokazu
Armstrong, Westerman Hattori, McLeland & Naughton
Ebara Corporation
Knight Anthony
Pickard Alison K.
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