Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – To produce composite – plural part or multilayered article
Reexamination Certificate
1995-08-04
2001-08-21
Ortiz, Angela (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
To produce composite, plural part or multilayered article
C264S259000, C264S268000
Reexamination Certificate
active
06277315
ABSTRACT:
The present invention relates to a method of manufacturing at least two different types of sealing rings for sealing a space between an inner surface of a socket provided with an annular groove and an outer surface of a spigot end introduced into the socket in a pipe joint. The invention relates also to an annular element adapted to be used for manufacturing according to the method of the invention at least two different kinds of sealing rings.
Sealing rings for sealing a space between an inner surface of a pipe socket formed with a groove and an outer surface of a spigot end introduced into the socket comprises a sealing element which in order to provide its sealing function by compression, lip action or a combination thereof must consist of a relatively soft rubber-elastic material. A sealing ring as a whole consisting of a material which is sufficiently soft and elastic for effecting the sealing function is disadvantageous from the point of view that it is difficult to retain in a desired position in the groove of the pipe socket prior to and during the jointing of the pipes for establishing the pipe joint. There also exists the risk that a sealing ring of this kind shall be forced from its sealing position in the pipe joint if there is a great difference in the pressures at opposite sides of the sealing ring. In order to solve these problems and disadvantages it is known to provide the sealing ring with a retainer element of a material which is substantially more rigid than the rubber-elastic material of the sealing ring, for example plastic or rubber having great hardness. The retainer element can for example be constituted by a locking ring which is mounted in a groove formed in the rubber-elastic material of the sealing ring, for example as is previously known from the Swedish Patent Specification No 7803870.0. In order to provide the locking ring with satisfying characteristics with regard to the mounting as well as with regard to the locking action the size of the locking ring must within small tolerances be adapted to the diameter of the groove of the socket, in which the sealing ring shall be positioned. If the locking ring is too large in relation to the groove it is difficult to mount the ring and if it is too small there is an unsatisfying locking of the sealing ring. It is also a drawback that the sealing element and the retainer element of the sealing ring are constituted by separate parts which means that it is necessary to handle double as many parts as if the sealing ring consists of one single part and that the correct relative position between the sealing element and the retainer element can be lost during or after the mounting. It may also happen that the retainer element consisting of a separate ring or a sealing ring provided with such a retainer element can be distorted or twisted to a position which makes it difficult or even impossible to provide the pipe joint.
In order to obviate the disadvantages present in a sealing ring provided with a separate locking ring it is previously known to manufacture a sealing ring in which the sealing element and the retainer element are permanently bound to each other. Different types of such sealing rings are previously known. A previously known type of sealing ring is shown and described in the U.S. Pat. No. 4,834,398. The sealing ring according to this patent specification has a sealing element and a retainer element which are positioned axially adjacent each other and are connected with each other at a binding surface extending from the inner periphery of the sealing ring to the outer periphery thereof. In a sealing ring of the kind shown in said US patent specification the sealing ring is positioned in the groove of the socket so that the spigot end initially engages the retainer element when being introduced into the socket.
In another previously known type of a sealing ring comprising a sealing element and a retainer element bound thereto the sealing element and the retainer element are so positioned axially adjacent each other after the mounting of the sealing ring in the groove of the socket that the spigot end when being introduced into the socket initially engages the sealing element. A sealing ring of this kind is previously known from the U.S. Pat. No. 4,818,209. The last mentioned type of sealing ring can be used at the type of method in which the sealing ring is used as a mould portion when the pipe socket is manufactured. In accordance with this method the sealing ring is positioned on a mandrel whereupon a pipe end portion consisting of thermoplastic material softened by heating is pushed over the mandrel and the sealing ring positioned thereon. Thereby the pipe end portion initially engages the part of the sealing ring which is constituted by the retainer element designed so as to guide the pipe end portion over the sealing ring. The softened pipe end portion connects with the sealing ring which forms a groove in the pipe socket. When the pipe end portion and the sealing ring are separated from the mandrel by being withdrawn therefrom the sealing ring is retained in the groove in the socket in a locked-in position.
Also other types of sealing rings consisting of sealing elements and retainer elements bound thereto are previously known.
The object of the invention is to provide a method and a sealing element for facilitating the manufacturing of sealing rings of different types comprising at least two annular elements which are bound to each other and with regard to their hardness are of different kinds, such as a sealing element consisting of rubber-elastic material and at least one retainer element consisting of a material which is substantially more rigid than the rubber-elastic material of the sealing element, for example a plastic material.
In order to comply with this object the method according to the invention is characterized in that an annular element of a first kind is manufactured with one and the same design irrespectively of the type of sealing ring which is to be manufactured, the element of the first kind being at the manufacturing provided with at least two separate binding surfaces for binding to element or elements of the second kind, and that the element or elements of the second kind is or are manufactured with a design adapted with regard to the desired type of sealing ring and is or are bound to one of or each one of the binding surfaces provided at the element of the first kind.
An annular sealing element according to the invention is adapted to be used for manufacturing different kinds of sealing rings according to the method of the invention which sealing rings are adapted for sealing a space between an inner surface of a pipe socket formed with an annular groove and an outer surface of a spigot end introduced into the socket at a pipe joint, each sealing ring comprising at least two annular elements which are connected with each other and with regard to their hardness are of different kinds, such as a sealing element consisting of rubber-elastic material and at least one retainer element consisting of a material which is substantially more rigid than the rubber-elastic material of the sealing element for example a plastic material, the annular element being characterized in that it has at least two separate binding surfaces adapted to be bound to element or elements of the second kind, the element or elements of the second kind being formed and bound to the desired binding surface or surfaces with regard to the desired type of sealing ring.
Thus, by means of the method according to the invention it is possible to manufacture different types of sealing rings while using one and the same annular element, which substantially facilitates and reduces the costs of the manufacturing.
REFERENCES:
patent: 4379559 (1983-04-01), Bohman
patent: 4410479 (1983-10-01), Cyriax
patent: 4693483 (1987-09-01), Valls
patent: 4818209 (1989-04-01), Petersson et al.
patent: 4826028 (1989-05-01), Vassallo et al.
patent: 4834398 (1989-05-01), Guzowski et al.
patent: 5064207 (1991-11-01), Bengtss
Gustavsson Leif
Hallstedt Goran
Hellström Börje
Motes Johnny
Baker & Daniels
Ortiz Angela
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