Abstract: An improved pipe belling process is shown which features a mandrel having spring loaded detents at one circumferential position on an outer working surface. A gasket is installed on the outer working surface in abutment with the exposed detents. The heated socket end of a thermoplastic pipe is forced over the mandrel exterior and over the gasket with the detents in an extended position. This action causes the heated socket end of the pipe to flow over the gasket and form a retention groove for retaining the gasket before again contacting the working surface of the mandrel. The heated end of the pipe is cooled and retracted from the working surface of the mandrel. The retraction step serves to force the spring loaded detents to the retracted position to allow travel of the thermoplastic pipe over the working surface of the mandrel with the gasket being retained within the formed groove.

Abstract: A method of socketing a pipe of oriented plastic having an annular groove inside the socket. An end portion (15) of the pipe is pushed onto a cylindrical mandrel element (11) and the region (l.sub.1) of the end portion at the opening thereof where the groove is to be located is heated to a temperature above the glass transition temperature of amorphous plastic and the crystalline melting point of crystalline plastic, respectively. The rest of the end portion is maintained at a temperature below the glass transition temperature or the crystalline melting point, respectively. The end portion (15) when said region is at a temperature above the glass transition temperature or the crystalline melting point, respectively, is pushed onto a second mandrel element (13) axially aligned with the first mandrel element the bottom portion of the socket being formed by said second mandrel element (13). The rest of the end portion is expanded to form the bottom portion of the socket.

Abstract: An elastomeric flange lining is provided for the metal flange of a pipe, the flange lining being structured with an annular channel with allows lateral movement of the elastomeric material of the flange lining when the flange lining is subjected to high compression forces, such as when two pipes are joined together end-to-end at their respective pipe flanges. The design of the flange lining and manner in which the flange lining is produced prevents outward bulging of elastomeric material into the interior of the pipe when subjected to compression forces. A flange mold for forming the flange lining is disclosed, and the method of making the flange lining is also disclosed.

Abstract: A tube reforming apparatus provides efficient mass production of reformed tube end portions. In a preferred embodiment, a tube reforming apparatus has a loading station, two heating stations, a forming station, and an unloading station. The loading station permits rapid loading of a series of laterally spaced apart tubes into clamping fixtures, and accurately meters a downwardly extending end portion of each tube. The heating stations permit accurate and evenly distributed heat to be applied to the end portions to make them pliable. The forming station reforms the end portions between a mating die pair, while compensating for any volume variation in the end portions. The unloading station automatically unloads the tubes from the clamping fixtures. Automation features of the apparatus permit these operations to be efficiently accomplished.

Abstract: A tool for automatically forming on thermoplastic pipes, bellings of considerable longitudinal extension for sealingly joining pipes subject to high stresses. The tool includes a shaped spindle on which there is axially inserted a heated end of the thermoplastic pipe, and a first and second mechanical body that receives pressurized fluids which act on the pipe. The heated pipe end is plastically deformed in the region of the shaped portion of the spindle to form an annular seat and bell portion of the belling.

Abstract: A pressurized-fluid workhead for permanent belling of end portions of plastic pipes. A die has a cavity for receiving a thermally plasticized end portion of a pipe. A forming buffer is insertable into the end portion of the pipe and arranged centrally of the die. A flange is mounted coaxially and slidably with respect to the buffer and die and has a striking surface which can be associated to an edge of the end portion of the pipe. Sealing elements are located on the die and the buffer. These interact with an external surface and an internal surface of the end portion of the pipe. The die, the buffer and the flange together peripherally define a forming chamber for the end portion of the pipe. The forming chamber is subdivided by the pipe into first and second pressure chambers for a fluid. The first pressure chamber is arranged between the lateral surface of the buffer and the internal surface of the pipe.

Abstract: The invention relates to the method and apparatus for producing a cured elastomeric hose having an internal socket or other internal configuration formed therein. The invention also relates to the product produced according to the method and the apparatus. Cured elastomeric hose can be formed having an internal socket by mounting the hose on a mandrel assembly having the desired internal configuration formed therein. An end forming cap assembly is selectively mounted on the hose and mandrel assembly, tightly engages the hose and forces the hose to assume the shape of the mandrel assembly. The hose is cured and then the end forming cap is removed from the hose through the use of an air removal tool. The product produced according to this invention is suitable to receive a wide variety of articles such as an anti-splashback valve or a molded thermoplastic connector.

Abstract: A tool is used for expanding a pipe-end which includes a plurality of jaws that can be moved radially in relation to a centre axis, between a retracted position and an outer expanding position. The jaws are inserted to a given distance in the pipe-end with the jaws in their retracted position. The jaws have outer surfaces which lie adjacent one another in the retracted positions of the jaws and have a circular-arcuate shape in cross section for engagement with the inner surface of the pipe-end. The radial distance of the outer jaw surfaces from the centre axis increases from the insertion end of the jaws to their opposite end. The pipe-end is expanded successively in several stages with relative small jaw movements, wherein the jaws are retracted and inserted further into the pipe-end between each expansion stage. The jaws of the tool can be moved radially through a distance which is smaller than the ultimate radial expansion of the pipe-end.

Abstract: A method of making a composite tube utilizing known equipment and process to form spaced end sections and a central section having an inner corrugated portion and surrounding portion bonded to at least certain crests of the corrugations. A spaced pair of generally cylindrical end couplings are formed by sequentially telescoping the end sections over an internal cylindrically contoured die part and continuing the telescoping until an inner surface of the telescoped end section engages at least three circumferentially spaced fingers to locate the telescoped end section in concentric relationship with the core part. Positioning an external die part in spaced concentric relationship around the telescoped end section, the external die part having an inner surface contoured to the desired external configuration of a coupling being formed. Injecting a heat softened thermoplastic material into the space between the die inner surface and the core to form a coupling.

Abstract: An apparatus is disclosed for making a composite tube with end couplings. The composite tube is made utilizing known equipment and process to form spaced end sections and a central section having an inner corrugated portion and surrounding portion bonded to at least certain crests of the corrugations. A spaced pair of generally cylindrical end couplings are formed by sequentially telescoping the end sections over an internal cylindrically contoured die part and continuing the telescoping until an inner surface of the telescoped end section engages at least three circumferentially spaced fingers to locate the telescoped end section in concentric relationship with the core part. An external die part is positioned in spaced concentric relationship around the telescoped end section, the external die part having an inner surface contoured to the desired external configuration of a coupling being formed.

Abstract: The invention relates to a machine for bell-forming ends of thermally plasticized pipes, including a vise for blocking pipes having jaws which are mobile along a vertical plane, wherein the introduction and unloading of the pipes occurs tangentially to the plane. The machine is provided with a forming device having a pressurized-fluid forming chamber, internally containing a forming chuck. The forming chamber exhibits an elastic wall which is strengthened during the pressurization operation by rigid striking elements borne directly by the jaws of the vice, and is fed by a single pipe for feeding fluid for pressurization of the forming chamber and for cooling the chuck.

Abstract: The components forming the layers of a composite pipe are successively introduced into a rotary drum (1). Initially, a plastic reinforcing layer (8), including a fibre reinforcement, is introduced into the drum, the ends of the drum (1) being bounded by rings. A concrete core layer (16) is then introduced and the length of the core layer (16) is shortened relative to that of the drum (1) by shaping rings fixed to the drum ends. The shaping rings are then replaced by other shaping rings (20, 21) so that, on either side of the core layer (16), two annular spaces (22, 23) are formed which are filled by a socket material (24, 25) of the same composite as the reinforcing layer (8). Thus, at one pipe end a socket end (28) is formed and at the other pipe end a spigot end (30) is formed, each such end being located within the composite pipe wall thickness. After introducing a second reinforcing layer (26), the production of the composite pipe is completed.

Abstract: A method of making a flanged pipe length includes flaring a metal pipe by rotating a grooved tool about the inside of the pipe and introducing a plastic tubular sleeve into the pipe. The tubular sleeve is subsequently heated and forced against the flanged portion of the metal pipe whereby the plastic material assumes a shape complementing the projections formed by the grooved tool.

Abstract: A coupling apparatus and method is disclosed for coupling a first hose for enabling the flow of a fluid therethrough, comprising a first coupling member having a first coupling internal bore extending between an inner end and an outer end. First coupling threads are defined in the first coupling member proximate the inner end whereas first coupling linking threads are defined by the first coupling internal bore of the first coupling member proximate the outer end. A second coupling member has second coupling threads defined therein. A first attachment member has first attachment linking threads with means for affixing the first hose attachment member to the first hose. The first attachment linking threads are engagable with the first coupling linking threads for securing the first hose to the first coupling means. The first coupling threads are engagable with the second coupling threads for interconnecting the first coupling member and the second coupling member for coupling the first hose thereto.

Abstract: A method of forming at the end portion of a thermoplastic material pipe in a pipe socket. The pipe end portion is molded around an annular sleeve onto which is bonded a sealing ring having an outer sealing ring adapted for sealing against the pipe end portion and an inner sealing ring, connected to the outer sealing ring, adapted for sealing against an outer surface of a spigot end of a connecting pipe introduced into the socket.

Abstract: In a method for forming an end portion of a plastic pipe wherein the end portion is transferred to softened state and the end portion is provided with an internal groove by axially displacing the pipe end portion in relation to a mould ring which is thereby introduced into the pipe end portion. After the forming of the pipe end portion the mould ring is left in the pipe end portion for forming a sealing ring therein. During the forming operation the pipe end portion is supported on a mandrel. In accordance with the invention the mould ring is displaced into the pipe end portion by displacing the ring along the mandrel while the pipe end portion is in its softened condition supported by the mandrel substantially without being displaced along the mandrel.

Abstract: An apparatus for flaring the end of a thermoplastic liner installed in a metal pipe. The end extends beyond the pipe and the pipe having at least one flange mounted thereon. The apparatus includes a first forming head having a liner contacting surface disposed at an acute angle relative to said liner, said surface being adapted to be pushed against said end to cause said end to flare outwardly about an acute angle and a second forming head having a liner contacting surface being disposed at an angle of at least ninety degrees relative to said liner. The second forming head is adapted to be pushed against said end to cause said end to bend into contact with said flange.

Abstract: In order to improve the introduction or uptake of force in a hollow section (1), in particular a tube, of long fibre reinforced plastic having an integrated force induction element (2) and to simplify its manufacture, a radial enlargement (4) is pressed into the hollow section (1) by means of a moulding body before the plastic matrix has hardened, which radial enlargement tapers into a narrow section (6) towards its free end (5), the jacket (3) which is formed in the process later enclosing an expansion element (9) with a clamping member (10) which merges into a tie rod (11), the expansion element (9) lying in a form-fitting manner against the interior of the enlargement (4,47) over the length of said enlargement.

Abstract: An apparatus for flanging tubular articles of a thermoplastic polymer which has been drawn and heat-set to an elevated temperature comprises a heating die (20) shaped to receive an end of one of the tubular articles (10) and to restrain it from shrinkage, transfer means such as a star wheel (24) to transfer the article (10) from the heating die (20) to a forming die (22) shaped to form an outward flange (12) on said end. Heater coils (33,40) are provided to maintain the dies at the required temperatures; namely the heating die (20) at a softening temperature above the glass transition temperature of the polymer but below the elevated temperature to which it has been heat-set and the forming die (22) at a forming temperature below the softening temperature.

Abstract: A method for closing the opening of each of the through-holes in the pipe-wall of a resin pipe and which extend parallel to the axis of the pipe, the method comprises pressing one end portion of the pipe in the direction parallel to the axis in a mold for closing the opening, the mold being connected to a high frequency current source, and heating the end portion by applying a high frequency current to the mold so as to melt the hole-partition walls which partition the through-holes, and the inner surface of the through-holes, thereby closing the opening.

Abstract: An apparatus for forming an end portion of a plastic pipe wherein the end portion is transferred to softened state and the end portion is provided with an internal groove by axially displacing the pipe end portion in relation to a mould ring which is thereby introduced into the pipe end portion. After the forming of the pipe end portion the mould ring is left in the pipe end portion for forming a sealing ring therein. During the forming operation the pipe end portion is supported on a mandrel. In accordance with the invention the mould ring is displaced into the pipe end portion by displacing the ring along the mandrel while the pipe end portion is in its softened condition supported by the mandrel substantially without being displaced along the mandrel.

Abstract: A gasket seating ring is disclosed which includes a specially designed hard plastic ring. The hard plastic ring in molded as a shaped annulus having a rearward, radially outwardly inclined ramp and a joined, forward, radially inwardly inclined ramp wherein the junction between the rearward and forward ramps defines the outer periphery of the ring. The shaped annulus further includes a radially inwardly angular junction.

Abstract: An apparatus for molding a sleeve on a corrugated pipe having an inner wall and fusion-bond ridges. Two clamps can close to engage several of the ridges. One to three of the ridges project into a molding space between the clamps. A core is inserted into the pipe and closes the molding space. Hot pressurized resin softens and collapses the projected ridges and fusion bonds the pipe to the sleeve portion of the molding space.

Abstract: The tubular body is laid in a horizontal position on a tapered suction drum and pivoted thereby into a vertical axis which is in coaxial relationship with the axis of a mandrel with a punch. The tubular body is then pushed from the surface of the suction drum on to the mandrel by a thrust member. The mandrel and/or the die is mounted displaceably in a vertical direction, which permits particularly stable and precise guidance. A plurality of dies with mandrels and punches associated therewith is disposed on a rotary member. In the course of a revolution of the rotary member, the tubular body on the mandrel is connected to a squeeze moulding in the die.

Abstract: Apparatus for seating a gasket in a plastic pipe bell is disclosed which includes providing a peripheral groove in a belling mandrel and seating a specially designed hard plastic ring in the groove. The hard plastic ring is molded to provide exterior ramps for forming an annular pocket in the pipe bell and is inwardly configured to provide a secure seating surface to receive and retain a resilient gasket thereon. The mandrel is urged into a preheated end of the pipe and vacuum forces are employed to pull the end of the pipe about the periphery of the mandrel and tightly against the exterior ramps of the hard plastic ring for forming the bell shape. Upon sufficient cooling of the pipe end, the mandrel is withdrawn and the plastic ring remains encapsulated within the bell shape. Upon removal of the mandrel, a resilient gasket is then seated within the bell in intimate overall contact with the seating surface of the plastic ring.

Abstract: A mould which is used for the production by injection moulding of fittings which have an inner annular groove includes a divisible outer mould, a mould core and a mould ring. The mould core has a plurality of segments which can be folded together. In order to ensure with absolute reliability that the fitting does not remain clinging to the mould ring during removal of the fitting from the mould, the mould ring is connected to the mould core and is withdrawn together with the mould core from the fitting.

Abstract: In order to improve the bonding strength between a synthetic resin-coated steel pipe and concrete applied around the synthetic resin-coated steel pipe for weight coating or protection, unevenness formed of groove portions and ridge portions arranged alternately is formed on the outer surface of the synthetic resin-coated steel pipe by pressing the synthetic resin coating layer with a working tool having an uneven inner surface under a condition where at least one member of the working tool and the synthetic resin coating layer is kept at a temperature at which the synthetic resin is melted.

Abstract: A vaccuum mandrel for forming a plastic pipe and inserting a seal ring in a groove in the pipe. The mandrel has plural segments mounted on inclined dowels so as to be expandible.

Abstract: A method for seating a gasket in a plastic pipe bell is disclosed which includes providing a peripheral groove in a belling mandrel and seating a specially designed hard plastic ring in the groove. The hard plastic ring is molded to provide exterior ramps for forming an annular pocket in the pipe bell and is inwardly configured to provide a secure seating surface to receive and retain a resilient gasket thereon. The mandrel is urged into a preheated end of the pipe and vacuum forces are employed to pull the end of the pipe about the periphery of the mandrel and tightly against the exterior ramps of the hard plastic ring for forming the bell shape. Upon sufficient cooling of the pipe end, the mandrel is withdrawn and the plastic ring remains encapsulated within the bell shape. Upon removal of the mandrel, a resilient gasket is then seated within the bell in intimate overall contact with the seating surface of the plastic ring.

Abstract: An object is produced from a tubular blank (10,15,17) of thermoplastic material of polyester or polyamide, preferably of polyethylene terephthalate by reducing the thickness of amorphous material in one or several areas of the blank by means of one or several consecutive re-shaping operations. A mechanical shaping device (23,29,71,81) moves a transitional zone (13,14,113) situated between thicker and thinner material along the blank and simultaneously elongates the blank in the moving direction of the transitional zone while reducing the thickness. After the last re-shaping operation the thinner material preferably has an oriented state. During the re-shaping operation the temperature of the material in the transitional zone (13,14,113) is controlled at a level which, immediately before the re-shaping operation, is within or close to the range of the glass transition temperature (TG).

Abstract: A pipe belling method and apparatus are disclosed which includes an elongated frame to support all of the operating components. A pressure chamber is reciprocal upon frame supported rails between an initial position and a belling position for continuous plastic pipe belling operations. Within the pressure chamber is supported a shaped mandrel to impress a desired hub or bell shape in one previously heated end of a length of pipe. Transverse pipe clamps are carried upon the frame forwardly of the pressure chamber to secure one end of the length of pipe in concentric alignment with the mandrel. When the pressure chamber and the mandrel are urged along the rails to the belling position, the mandrel will be inserted into the heated end of the pipe and a resilient, planar gasket will seal the forward end of the pressure chamber against the pipe clamps and against the pipe itself.

Abstract: Undercut tubular synthetic plastic articles, such as fittings, are formed in the mold cavity of an injection molding machine on a one- or two-piece core a portion of which is surrounded by the undercut portion of the article and a first smaller-diameter portion at one side of the undercut portion. If the core consists of two components, a cylindrical component of the core slidably guides the aforementioned portion and is surrounded by a second smaller-diameter portion of the article at the other side of the undercut portion.

Abstract: A method of producing plastic pipe having air channels axially extending through the wall thereof, with at least one of the respective ends of the air channels being closed by an annular slotted channel-closure filled with a caulking material in its annular slot. The channel-closure is force-fitted on the pipe end, so that the caulking material is pressed into the air channels.

Abstract: A tubular article having a peripheral groove is formed by providing the groove in the wall of a tubular blank made of thermoplastic material such as polyethylene terephthalate by applying simultaneously a pressure against the wall of the blank and axial stretching forces. In the bottom of the groove the material is drawn to yielding and the blank is simultaneously elongated.

Abstract: A belling mandrel assembly for forming in the end of a plastic pipe a belled socket having therein an annular seal pocket. A lip mold for forming the lip of the socket and a base mold for forming the base of the socket are operable to press a plurality of form block segments trapped between them. Upon the application of such pressure, the form block segments expand to form an annular ring for molding an annular seal pocket in the socket. Upon widening the distance between the lip mold and the base mold the form block segments retract to allow the mandrel to be withdrawn from the belled socket.

Abstract: Apparatus for automatically forming a bell-shaped socket on an end of thermoplastic pipe or the like. The apparatus includes a stripper plate separate from the belling mandrel, and positioned to be engaged and carried by the mandrel during a belling operation. The stripper plate carries a switch which is engaged by the end of the pipe when a predetermined bell depth is attained by the mandrel. Automatic control circuitry is disclosed to initiate a cooling water spray, to retract the mandrel, and to signal the absence of a good bell.

Abstract: A improved apparatus for molding pipes is dislosed. A hood of convex shape having an outer surface corresponding to the shape of the interior of the pipe and has an annular rim on the widest part thereof and a molding shank rigidly attached to the narrowest part of the hood. A flat annular washer is support on the rim and being separable therefrom to provide a flat terminal end for the molded pipe.

Abstract: For the purpose of making a joint socket comprising at least two portions, namely a portion for receiving a plastic pipe end and another portion into which a rubber ring is fitted, a device for heating and softening a plastic pipe end and enlarging the radius of the softened pipe end to twice its size which includes, an inwardly slanted portion between a first outwardly slanted portion and a second outwardly slanted portion whose radius becomes smaller as it comes nearer to the front end thereof. As the result, the frictional resistance between an improved core and the radius enlarged softened pipe is reduced to a value which enables the device to be operated such that wall-thickened sockets can be made without loss of wall thickness subsequent to the radius enlarging process.

Abstract: A method for forming a connecting sleeve having an internal groove at the end section of a tube made of crystalline or partially crystalline thermoplastic material in which the end section is heated to the deformation temperature and then is axially upset in a heatable device which defines an annular gap until the annular gap is filled. This increases the wall thickness of said end section, which is then shaped to form the connecting sleeve during axial displacement in a mold. The end section is heated to a processing temperature within the range of the deformation temperature and up to the crystalline melting temperature. In the initial step in the heatable device the application of the first axial upsetting force is such that the upsetting begins at the front end of the end section and continues until the annular gap in the heatable device is filled.

Abstract: To ensure that a socket formed on a pipe-end in plastically deformable condition is in no part thinner than the pipe material out of which it is made, the pipe-end is first enlarged in diameter and encased within a contour die formed as envelope for the external shape required of the socket. The enlarged pipe-end is then longitudinally compressed to thicken it and internally formed so as to smooth the internal surface of the pipe-end and impose on it the internal shape and dimensions required of the socket. The required socket shape preferably includes a circumferential groove to house a resilient sealing ring.

Abstract: Disclosed herein is a mechanical expansion plug for the internal calibration of plastic material tubes in general, particularly for fashioning the seats for gaskets, that comprises a tubular extending body provided, along the lateral surface thereof, with a circumferential aperture. Inside the said body, able to slide in the two directions coaxially thereto and without the possibility of one rotating with respect to the other, there is a movable element of truncated cone conformation, provided peripherally with a first and second set of equidistant guides that extend along generatrices of the said element and alternate one with the other.

Abstract: A socket of a thermoplastic pipe is provided with an internal groove by subjecting the tube to an upsetting action and simultaneously inflating the tube by an inner pressure. Subsequently a moulding ring is expanded and the tube is shrunk onto the expanded ring by cooling. Before shrinkage the inner diameter of the bottom of the groove is at least equal and preferably greater than the outer diameter of the moulding ring in expanded form.

Abstract: A mandrel for forming a bell shape and an annular groove in the bell in one end of a plastic pipe which comprises a shaped profile and a plurality of identically formed segments which are movable relative to the profile. The segments are radially urged in identical radial paths from an initial position which is inwardly of the bell shaped profile to an expanded position wherein the segments cooperate and interact to form an expanded ring of diameter greater than the pipe bell, thereby to impress a circular groove therein. An actuating shaft rotatively reciprocates a pair of actuating plates to radially reciprocate the plurality of segments simultaneously between their initial positions and expanded positions. The segments each include link pairs in pivoted engagement with the actuating plates and keys which respectively ride within guide slots to radially guide the segments between their initial positions and expanded positions upon rotative reciprocation of the actuating plates.

Abstract: To ensure that a socket formed on a pipe-end in plastically deformable condition is in no part thinner than the pipe material out of which it is made, the pipe-end is first enlarged in diameter and encased within a contour die formed as envelope for the external shape required of the socket. The enlarged pipe-end is then longitudinally compressed to thicken it and internally formed so as to smooth the internal surface of the pipe-end and impose on it the internal shape and dimensions required of the socket. The required socket shape preferably includes a circumferential groove to house a resilient sealing ring.

Abstract: A thermoplastic socket pipe part with a sealing member comprising a sealing head and sealing sleeve, the sealing head being retained by means of a retaining ring, which retaining ring is formed by bending back the end part of an extruded plastic tube provided with three widenings with decreasing inner diameter as seen from the free end of the plastic tube.

Abstract: An injection mold comprises an outer mold structure defining an abutment surface and a core axially slidable in this structure between a molding position and a second position. The core defines a mold cavity with the outer mold structure in the molding position to mold a tubular end portion of a synthetic thermoplastic resin article therein. The core includes an annular rib defining an internal peripheral annular groove of the end portion and an end to which a mold sleeve is axially immovably connected. The mold sleeve has an end face facing and conforming to the abutment surface upon axial sliding of the core into the molding position. The mold sleeve and core end have converging confronting surfaces defining an annular gap tapering toward the core end, the annular gap defining a free end of the tubular end portion extending outwardly from an annular section thereof surrounding the groove.

Abstract: The internal core of a molding apparatus does not have to be axially moved for molding a plastic pipe provided with a peripheral groove therein. This is accomplished by providing the internal core with a groove of such narrow width as to always be open to the surrounding cooperating mold body while at the same time preventing plastic material from entering the groove as the plastic material is being introduced into the mold cavity.

Abstract: A plastic pipe comprises an inner wall and an outer wall, being integral with longitudinal partitions between them and bounding longitudinally extending channels and a circumferential, helically, or non-helically extending groove, which groove has been formed by closing the channels by pressing channel wall parts onto each other. A retaining ring may be snapped into an external groove.

Abstract: The mandrel uses a single anchoring groove in order to fixedly mount the forming and sealing element thereon for subsequent passage of a heated thermoplastic pipe end thereover. The forward wall of the anchoring groove may be directed radially outwardly or may be inclined rearwardly in order to abut the sealing portion of the element. The sealing portion fills the anchoring groove while the trailing wedge-shaped end fits into a small recess to avoid "fish-mouthing.

Abstract: Undercut tubular synthetic plastic articles, such as fittings, are formed in the mold cavity of an injection molding machine on a two-piece core a tubular component of which is surrounded by the undercut portion of the article and a first smaller-diameter portion at one side of the undercut portion. A cylindrical component of the core slidably guides the tubular component and is surrounded by a second smaller-diameter portion of the article at the other side of the undercut portion.