WO2000074926A1 - Procede de tulipage de tubes - Google Patents

Procede de tulipage de tubes Download PDF

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Publication number
WO2000074926A1
WO2000074926A1 PCT/US1999/013456 US9913456W WO0074926A1 WO 2000074926 A1 WO2000074926 A1 WO 2000074926A1 US 9913456 W US9913456 W US 9913456W WO 0074926 A1 WO0074926 A1 WO 0074926A1
Authority
WO
WIPO (PCT)
Prior art keywords
mandrel
gasket
working surface
socket end
thermoplastic pipe
Prior art date
Application number
PCT/US1999/013456
Other languages
English (en)
Inventor
Samuel Gusowski
Original Assignee
S & B Technical Products, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by S & B Technical Products, Inc. filed Critical S & B Technical Products, Inc.
Priority to PCT/US1999/013456 priority Critical patent/WO2000074926A1/fr
Publication of WO2000074926A1 publication Critical patent/WO2000074926A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C57/00—Shaping of tube ends, e.g. flanging, belling or closing; Apparatus therefor, e.g. collapsible mandrels
    • B29C57/02—Belling or enlarging, e.g. combined with forming a groove
    • B29C57/025—Belling or enlarging, e.g. combined with forming a groove combined with the introduction of a sealing ring, e.g. using the sealing element as forming element

Definitions

  • the present invention relates generally to sealing systems for thermoplastic pipes and, specifically, to an improved belling process for installing a gasket in a socket end of a thermoplastic pipe.
  • Pipes formed from thermoplastic materials including polyethylene and PVC are used in a variety of industries.
  • the spigot or male pipe end is inserted within the female or socket pipe end .
  • An annular, elastomeric ring or gasket is typically seated within a groove formed in the socket end of the thermoplastic pipe.
  • the gasket provides the major seal capacity for the joint. It is critical, during the installation process, that the gasket not be able to twist or flip since a displaced or dislocated gasket will adversely affect the ultimate sealing capacity of the joint.
  • the elastomeric gasket was inserted within an internal groove in the socket end of the female pipe as the female or belling end was simultaneously being formed .
  • the provision of a prestressed and anchored elastomeric gasket during the belling process at the pipe factory provided an improved socket end for a pipe joint with a sealing gasket which would not twist or flip or otherwise allow impurities to enter the sealing zones of the joint.
  • an object of the present invention is to provide a method of installing a gasket in a socket end of a thermoplastic pipe in a Rieber-type process in which fewer mould parts are required and in which fewer operational steps are employed.
  • a method for installing a gasket in a socket end of a thermoplastic pipe which is used to form a pipe joint or coupling A mandrel is provided with an inner end and an outer end and having a generally cylindrical outer working surface.
  • a gasket is installed at a first circumferential position on the outer working surface of the mandrel.
  • a plurality of outwardly biased detents are provided at a second circumferential location on the mandrel nearer the inner end of the mandrel.
  • the outwardly biased detents have exposed lip portions which abut the gasket in a normally extended position.
  • the detents are also retractable to a retracted position flush with the outer working surface of the mandrel.
  • the socket end of the thermoplastic pipe is heated and then forced over the working surface of the mandrel and over the gasket with the detents in the extended position, whereby the heated socket end of the thermoplastic pipe flows over the gasket to form a retention groove for retaining the gasket and again contacts the working surface of the mandrel.
  • the heated socket end of the thermoplastic pipe is then cooled and retracted from the working surface of the mandrel.
  • the retracting step serves to force the detents to the retracted position to allow travel of the thermoplastic pipe over the working surface of the mandrel.
  • the method of the invention also allows two or more gaskets to be simultaneously installed within the socket end of a thermoplastic pipe during the belling process.
  • Figure 1 is a side, partial cross-sectional view of the improved mandrel used in the belling process of the invention
  • Figure 2 is a simplified, end view of the mandrel of Figure 1 showing the spring loaded detents thereof;
  • Figures 3-8 are simplified, schematic views of the method steps used in the method of installing a gasket of the invention.
  • Figure 9 is a side, partial cross-sectional view of the mandrel of Figure 1 modified to accept an additional gasket and showing the heated pipe end being forced over both gaskets; and Figures 1 0-1 3 are simplified, schematic views of the prior art Rieber process for installing a gasket in a socket end of a thermoplastic pipe.
  • Figure 1 0 shows a section of a conventional elastomeric sealing gasket 1 1 having a steel reinforcing ring 1 3 in place on the generally cylindrical outer working surface 1 5 of the mandrel 1 7 used in the belling process.
  • the elastomeric gasket 1 1 can be formed of, for example, rubber and is a ring shaped, circumferential member having an inner compression surface 1 9 and an exposed nose portion 21 which, as shown in Figure 1 , abuts a forming collar 23.
  • the forming collar 23 has a first generally cylindrical extent 25 which is joined to a second cylindrical extent 27 by a step region 29, whereby the second extent 27 is of greater external diameter than the first cylindrical extent 25, shown in Figure 10.
  • the steel reinforced elastomeric ring 1 1 is thus placed onto the working surface of the mandrel 1 7 and pushed to a position against the back-up or forming collar 23. In this position, the gasket is firmly anchored to the mandrel surface with the rubber between the mandrel and the steel- ring of the gasket being compressed by approximately 20% .
  • the socket end 33 of the thermoplastic pipe 31 is heated and pushed over the steel mandrel 1 7, gasket 1 1 and back-up collar 23.
  • the socket end 33 is expanded due to the thermoplastic nature of the pipe.
  • thermoplastic materials such as polyethylene, polypropylene and polyvinylchloride (PVC) are known in the prior art having the required expansion characteristics, depending upon the end application of the pipe joint.
  • the socket end 33 flows over the first cylindrical extent 25 of the back-up collar 23 and abuts the step region 29 in the second step of the process. It was critical in the prior art technique that the first cylindrical extent 25 of the back-up collar 23 be maintained at the correct temperature, otherwise flaws were produced in the interior mouth region of the socket end of the pipe.
  • the pipe socket end 33 is cooled by means of a water spray bar 39 and spray nozzles 41 .
  • the pipe socket end 33 shrinks around the gasket 1 1 , thus compressing the rubber body of the gasket between the steel reinforcing ring 1 3 and the socket-groove to establish a firm seal. Because the sealing of the gasket against the socket took place under controlled conditions in the factory, there was no possibility that sand or similar contaminates would penetrate the crucial sealing zone of the gasket during storage, transportation or installation.
  • the mandrel is a generally cylindrical member including an outer cylindrical extent 45 which, in this case, is joined to an inner cylindrical extent 47 of slightly greater external diameter forming a gently sloped external region 49.
  • the inner and outer extent 45, 47 can be of steel and together form the generally cylindrical outer working surface 51 between the inner end 53 and outer end 55 thereof.
  • a gasket 57 is installed at a first circumferential position 59 which forms a slight recess on the outer working surface 51 of the mandrel 43.
  • a plurality of spring loaded detents 61 are located at a second circumferential location 63 which is nearer the inner end 53 of the mandrel 51 . As shown in Figure
  • the spring loaded detents 61 have exposed lip portions 65 which, as shown in Figures 3-6 abut the gasket 57 in a normally extended position.
  • the gasket 57 ( Figure 3) has a circumferential compression surface 67 and a circumferential nose region 69 which protrudes generally in the direction of the inner end 53 of the mandrel in the relaxed state.
  • the spring loaded detents 61 are " L-shaped" members having a vertical extent 71 joined to a horizontal extent 73.
  • a biasing member, such as coil spring 75, is located within a spring chamber 77 and acts upon the horizontal extent 73 of the detent, normally biasing the detent to the exposed position shown in Figure 1 .
  • the spring chambers 77 can be mounted in any convenient fashion within the interior of the mandrel 51 , such as by bolting a mounting plate 79 to a spacer plate 81 which is located at one circumferential location within the interior of the mandrel
  • two or more detents and associated spring chambers will be located about the circumference of the first circumferential location on the mandrel.
  • four spring loaded detents are located at equally spaced positions about the periphery of the mandrel at the first circumferential location. The additional positions are indicated at 62, 64 and 66 in Figure 2.
  • the spring loaded detents are also retractable to a retracted position ( Figure 7) with the lip portions 65 flush with the outer working surface 51 of the mandrel 43.
  • Figures 3-8 illustrate, in simplified schematic fashion, the improved method of the invention .
  • a gasket 57 is installed on the outer working surface 51 of the improved mandrel 43, according to the prior art placement techniques.
  • the gasket 57 is installed at a first circumferential location on the outer working surface 51 of the mandrel 43 so that the concave region which joins the nose region 69 to the compression surface 67 abuts the lip portion 65 of the spring loaded detent 61 .
  • the spring loaded detents 61 have an arcuate external profile 83, best seen in Figure 8 with a leading edge 85 and a trailing edge 87, the trailing edge 87 being connected to the leading edge 85 by an inclined surface which slopes in an upward radial direction from the inner end 53 of the mandrel toward the outer end 55 thereof.
  • the socket end 33 of the thermoplastic pipe 31 is heated in conventional manner and forced over the exterior surface of the gasket 57.
  • the gasket 57 has an external steel band 59 which serves to pre- compress the gasket against the mandrel exterior and assist in retaining the gasket in the desired position. Additionally, the gasket 57 is retained in position by the exposed lip portions 65 of the spring loaded detent 61 .
  • Other gasket designs will be familiar to those skilled in the art and include reinforcing rings and bands of various shapes either exposed on the gasket exterior or embedded within the gasket material.
  • the heated pipe end 33 begins to flow over the rear exterior surface 91 of the gasket 57.
  • the pipe socket end 33 continues to flow over the gasket, it is gradually retracted about the mandrel exterior ( Figures 5-6) .
  • the action of retracting the gasket can be facilitated by applying a vacuum through the mandrel ports 91 , 93.
  • the heated socket end would typically be cooled, as by spraying with a water bath as described with respect to Figure 1 3 of the prior art.
  • FIGs 7 and 8 show the final steps in the improved process in which the pipe
  • Figure 9 illustrates a pair of sealing gaskets 57, 99 with the socket end 33 of the heated pipe being forced over both gaskets, the gaskets being retained in position by means of the spring loaded detents 101 , 103. Vacuum is applied through parts 1 04, 1 06, 1 08 to facilitate contraction of the gasket material to the position shown in Figure 9. The pipe 31 and gaskets 57, 99 are then withdrawn from the mandrel working surface 51 in the same manner as previously described with respect to Figures 7 and 8.
  • the improved mandrel of the invention simplifies the Rieber process, requiring fewer parts and fewer method steps.
  • the simplified manufacturing process saves time and is more reliable since the temperature of the exposed surface of a back-up collar is not critical to the process.
  • the precise location of the gasket is set constant by the detents, instead of relying upon a moving mechanism like the back-up collar of the prior art.
  • the flow of the heated pipe end is actually facilitated by the absence of the back-up collar.
  • the heated plastic attempts to return naturally to the mandrel diameter, causing a better formed bell over the gasket and assuring the fit of the gasket inside the bell. It is not necessary to provide an intricate control mechanism for the back-up collar including limit switches temperature measurement devices and other components. Also, alignment of the heated pipe end with the exposed surface of the collar is not critical.
  • the method of the invention also allows multiple gaskets to be installed within multiple grooves formed within the pipe socket end.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Shaping Of Tube Ends By Bending Or Straightening (AREA)

Abstract

L'invention concerne un procédé amélioré de tulipage de tubes lequel utilise un mandrin (43) présentant des ergots à ressort (61) au niveau d'une position circonférentielle (63) sur une surface d'usinage extérieure (51). Une garniture (57) est disposée sur la surface d'usinage extérieure (51) en aboutement avec les ergots exposés (61). L'extrémité de manchon chauffé d'un tube thermoplastique est forcée à venir sur la partie extérieure (51) du mandrin et sur la garniture (57), les ergots (61) étant en position déployée. Cette action a pour effet de faire passer l'extrémité de manchon chauffé du tube sur la garniture (57) et de former une rainure de retenue de la garniture (57) avant un nouveau contact de la surface d'usinage (51) du mandrin (43). L'étape de rétraction sert à forcer les ergots à ressort (61) en position rétractée pour permettre le déplacement du tube thermoplastique sur la surface d'usinage (51) du mandrin (43) avec la garniture (57) retenue à l'intérieur de la rainure formée.
PCT/US1999/013456 1999-06-08 1999-06-08 Procede de tulipage de tubes WO2000074926A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/US1999/013456 WO2000074926A1 (fr) 1999-06-08 1999-06-08 Procede de tulipage de tubes

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1999/013456 WO2000074926A1 (fr) 1999-06-08 1999-06-08 Procede de tulipage de tubes

Publications (1)

Publication Number Publication Date
WO2000074926A1 true WO2000074926A1 (fr) 2000-12-14

Family

ID=22272968

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1999/013456 WO2000074926A1 (fr) 1999-06-08 1999-06-08 Procede de tulipage de tubes

Country Status (1)

Country Link
WO (1) WO2000074926A1 (fr)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4030872A (en) * 1974-09-02 1977-06-21 Rieber & Son Plastic-Industri A/S Combined mould element and sealing ring
US4107249A (en) * 1975-03-12 1978-08-15 Sekisui Kagaku Kogyo Kabushiki Kaisha Method for forming an annular groove in a thermoplastic pipe
US4353860A (en) * 1979-09-21 1982-10-12 Gordon John H Method for pressure forming pipe bells
US4395218A (en) * 1980-11-14 1983-07-26 S.I.C.A. Serrande.Infissi.Carpenteria.Attrezzatura S.P.A. Mechanical expansion plug for the internal calibration of plastic material tubes in general, particularly for fashioning the seats for gaskets
US4403938A (en) * 1978-03-20 1983-09-13 James Hardie & Coy. Pty. Limited Pipe socket forming
US5928451A (en) * 1995-09-20 1999-07-27 Uponor B.V. Method of socketing a pipe

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4030872A (en) * 1974-09-02 1977-06-21 Rieber & Son Plastic-Industri A/S Combined mould element and sealing ring
US4107249A (en) * 1975-03-12 1978-08-15 Sekisui Kagaku Kogyo Kabushiki Kaisha Method for forming an annular groove in a thermoplastic pipe
US4403938A (en) * 1978-03-20 1983-09-13 James Hardie & Coy. Pty. Limited Pipe socket forming
US4353860A (en) * 1979-09-21 1982-10-12 Gordon John H Method for pressure forming pipe bells
US4395218A (en) * 1980-11-14 1983-07-26 S.I.C.A. Serrande.Infissi.Carpenteria.Attrezzatura S.P.A. Mechanical expansion plug for the internal calibration of plastic material tubes in general, particularly for fashioning the seats for gaskets
US5928451A (en) * 1995-09-20 1999-07-27 Uponor B.V. Method of socketing a pipe

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