Pipe joints or couplings – Essential catch – With manipulator
Reexamination Certificate
1999-06-01
2001-01-30
Pham, Teri (Department: 3627)
Pipe joints or couplings
Essential catch
With manipulator
C285S358000, C285S321000
Reexamination Certificate
active
06179346
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a coupling device for joining together adjacent ends of two tubular components, such as two pipe ends.
2. Present State of the Art
Coupling devices are used to join together adjacent ends of tubular components, such as pipes, and must provide (a) a reliable securement together of the adjacent ends via the coupling device so as to resist separation and (b) a sealed joint to withstand leakage under pressure.
In addition to joining together two adjacent pipe ends, coupling devices can be used to join together other types of tubular components e.g. to connect an inlet or outlet pipe to a tubular fitting on a housing.
However, the present invention has been developed primarily in connection with the coupling together of large bore pipes of the type used by the gas and water supply industries. Pipes of this type are usually made of polyethylene, and large bore yellow gas pipes will be a familiar sight to motorists negotiating roadworks.
The commonly used method to connect together successive lengths of this type of pipe and/or of pipes to pipe fittings, involve heating of adjacent ends to partly melt the joining portions, pressing the joining portions so that they fuse together, and allowing the portions to cool and set as a unitary product. Electro-fusion may be used, thereby pipe fittings incorporate wound electrical wire coil resisters embedded in the socket, to provide a heating element used to fuse together pipe/fitting joints. In both types of permanent fusing together (butt and electro-fusion), electrical power is always required.
When electrical power is used, the need to achieve exacting operating and temperature conditions necessary to obtain reliable joints can only be provided by bulky, complex and expensive equipment. Furthermore, skilled operatives are needed, but even then it is difficult, if not impossible, to test the resulting joint integrity in situ, prior to commissioning.
Evidently, the quality and reliability of fused-together joints depends upon (1) operator skill, (2) quality of the materials used to make the joining components and (3) design tolerances in the manufacture of the joining components. It is also difficult to join together pipes of different materials of specifications. Imperfect standards in any single one of these three criteria can result in unacceptable joints, both from the point of view of leakage, and also for resistance to mechanical separation of the joint under load.
Furthermore, joints of this type are necessarily permanent, and therefore can only be un-made by cutting through the joined-together components (often requiring extensive groundworks to complete), and obviously this is not an easily releasable, and subsequently re-makable type of coupling. Also, cannot be assembled without completing the joint, which makes trial lay-outs difficult.
OBJECTS AND BRIEF DESCRIPTION OF THE INVENTION
The above draw-backs, in connection with permanent fusing together of pipe ends has been described as background information, and the invention seeks to provide a new type of mechanical joint for connecting together pipe ends. Although releasable mechanical type couplings are available for smaller diameter pipework, currently there is no reliable mechanical socket/spigot coupling available to cater for the significant tolerance bands and pull-loads (typically measured in tens of tonnes) in connection with large diameter pipe joints.
The invention therefore seeks to provide an improved design of coupling device, which is operative in order to provide a mechanical coupling, or uncoupling, of the adjacent ends of two tubular components, in a way which is mechanically simple to operate and which provides a mechanically reliable and substantially leak proof coupling together, even in the event of substantial variation in tolerances in diameter of the ends of the two components which are to be joined together.
The invention therefore utilises, essentially, a three component type of coupling device for connecting first and second tubular components together and which comprises:
1. an external cap member which is intended to be rotatable mounted on the first tubular component for angular movement between a release position and a clamping position, and which defines a central hole for receiving one end of the second tubular component;
2. an annular seal which is capable of being received by an internal seating in said first tubular component and which has a resiliently deformable sealing portion engageable with the outer periphery of said second tubular component upon entry of the latter through the hole in said external cap member; and,
3. a generally annular gripping member which is housed within said cap member and which is locatable adjacent to the annular seal, said gripping member having a cam-type of engagement with the inner surface of the cap member such that rotation of the cap member to the clamping position causes the gripping member to be moved radially inwardly into gripping engagement with the outer periphery of the second tubular component.
A coupling device as defined above will be referred to hereinafter as “a coupling device of the type set forth”.
According to the invention, there is provided a coupling device of the type set forth, characterised in that the cam-type of interengagement between the inner surface of the cap member and the outer surface of the gripping member comprises:
a primary arrangement of cams and guide surfaces engageable therewith, upon rotation of the cap member to the clamping position, so as to deform the gripping member radially inwardly to gripping engagement with the outer periphery of the second tubular component; and,
a secondary arrangement of cams and guide surfaces engageable therewith, upon rotation of the cap member to the clamping position, so as to take-up any radial clearance which may develop between the inner surface of the cap member and the outer surface of the gripping member as a result of radial inward deformation of the gripping member by the primary arrangement of cams and guide surfaces, and also applying additional gripping force to the second tubular component.
Therefore, upon tightening of the cap member to the clamping position, the primary and secondary cam arrangements and respective guide surfaces are jointly operative to apply inward deformation to the gripping member and into gripping engagement with the outer periphery of the second tubular component, while at the same time taking-up any radial clearance which may tend to develop between the outer surface of the gripping member and the inner surface of the cap member, as a result of the interaction between the guide surfaces and the cams of the primary arrangement.
Preferably, the primary and secondary cams are provided on the outer surface of the gripping member, and co-operative guide surfaces are formed on the inner surface of the cap member. However, these arrangements may be reversed; or indeed one of the sets of cams may be provided on the outer surface of the gripping member, and the other set of cams may be arranged on the inner surface of the cap member.
The outer surface of the gripping member preferably comprises first and second portions, in which the first portion is frusto-conical and increases in diameter in an axial direction inwardly of the coupling, and the second portion comprises a generally axially extending portion.
The primary cams are preferably arranged on the second portion, and the secondary cams are arranged on the first portion.
The primary cams may comprise three separate cam portions spaced circumferentially from each other by approximately 120°, and the secondary cams may comprise six cam portions spaced circumferentially from each other by about 60°.
The gripping member is preferably a split ring, which can be deformed circumferentially and radially.
Preferably, a spacer washer is positioned between the gripping member and the annular seal, to prevent damage and to prevent extrusion of the seal under pressure.
The cap me
Pham Teri
Royack Limited
Workman & Nydegger & Seeley
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