AU2013100592A4 - Apparatus for forming bends in thermoplastic pipe - Google Patents

Abstract

An apparatus for forming a bend in a section of thermoplastic pipe, the apparatus comprising: a retaining portion adapted to receive and retain part of the thermoplastic pipe; a forming portion including a forming surface about which a bend in the section of thermoplastic pipe is formed; and a drive portion operative to cause movement of the retaining portion along a forming path, the forming path including a curved portion, and wherein the section of thermoplastic pipe is brought into contact with the forming surface as the retaining portion moves along the curved portion of the forming path, thereby forming the bend in the section of thermoplastic pipe. 12a 20 21 11 12b ............................ ........ ........................................................................ .................................. -......... ........................................................................ ................................. --........ ............................................................ .................................. .......... ...................................... ................................................... ........ ............................................... .......................................... ...................................................................... ... ................................................................ ............ ................................. ........................... ....................... ... ..................... ............... .............................. ............................ .......... ......................... ........................ .............. ................. ...... ........... ............... .............. ...... ....... ...... ............. ............... ........... ....... ............... ............................. ....... ... ............................. .. ........ - -- ..... ............. .......... ........................................... ................................. ................................. .............. ............... ...................... ........... ... ........... ................. .......... ............. ............. ................ ................. ...... ................. ............ ................ .......... ............ ........ ............ ................... ................ .............. ............ .................. ............ ...... .......... ................ ...... . 22 13 20 21

Description

APPARATUS FOR FORMING BENDS IN THERMOPLASTIC PIPE TECHNICAL FIELD [0001] The present invention relates to an apparatus for forming bends in thermoplastic pipe. The invention also relates to the forming of a bend in thermoplastic pipe using the apparatus of the invention. BACKGROUND ART [0002] Thermoplastic piping is now widely used for water and sewage reticulation and for gas supply. Such piping can be supplied as discrete lengths but, in some instances, is provided as rolls allowing continuous laying of pipe over long distances. [0003] Irrespective of the length of the sections used to make up a piping system, bends are invariably required. Bends are typically required at all angles between 110 and 90' in centreline radii of curvature varying from 2 to 3 times diameter. [0004] To be incorporated into the piping system the bends must be connected to the adjacent pipe sections in the same fashion as the pipe sections per se must be joined. Thermoplastic pipe sections are commonly connected by electrofusion or butt welding. In some cases, a butt flange may be provided between sections but each half of the butt flange must be connected to a section using the foregoing methods. [0005] So that a join can be formed that is commensurate with the pressure rating of the pipe, it is important that the ends of pipe sections to be joined are both circular. That is, if one section has a circular end while the other end has a slightly oval end, an inferior joint will be produced. [0006] According to generally accepted practice, bends are formed in sections of thermoplastic pipe by supporting a section of softened pipe at its ends and applying pressure at the centre of the section to form the desired bend. [0007] A disadvantage of the foregoing method for forming bends in thermoplastic pipe is that the pipe is stretched preferentially in the middle of the arc during the bending process. This is particularly the case with the outside wall of the bend. The stretching weakens the pipe wall and leads to derating of the pressure rating of the bend. [0008] In UK patent application no. GB 2 351 936 A, there is disclosed a method and apparatus for forming bends in thermoplastic pipe. This disclosure overcomes the disadvantages of the methods that existed at the filing date of that application. An improved apparatus is disclosed in Australian Patent No. 2003203314. However, a particular apparatus according to either of these disclosures can be used to form bends in thermoplastic pipe usually of only one size. That is, a specific apparatus has to be constructed for each size of pipe in which a bend is to be made. It would therefore be desirable to have available apparatus that can be used with thermoplastic pipe of a range of sizes. [0009] It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country. SUMMARY OF INVENTION [0010] The present invention is directed to an apparatus for forming bends in thermoplastic pipe, which may at least partially overcome at least one of the abovementioned disadvantages or provide the consumer with a useful or commercial choice. [0011] With the foregoing in view, the present invention resides broadly, in one form, in an apparatus for forming a bend in a section of thermoplastic pipe, the apparatus comprising: a retaining portion adapted to receive and retain part of the thermoplastic pipe; a forming portion including a forming surface about which a bend in the section of thermoplastic pipe is formed; and a drive portion operative to cause movement of the retaining portion along a forming path, the forming path including a curved portion, and wherein the section of thermoplastic pipe is brought into contact with the forming surface as the retaining portion moves along the curved portion of the forming path, thereby forming the bend in the section of thermoplastic pipe. [0012] The term 'thermoplastic' as used herein applies particularly to polyolefins such as polyethylene and polypropylene. In the present invention, it will be understood that the sections of pipe used are typically circular in cross-section (although may suitably be of any cross-sectional shape), have one or more wall members defining an internal bore extending along the longitudinal length of the section of pipe. It is envisaged that the opposed ends of the section of pipe will be open.

[0013] It is envisaged that any suitable size section of pipe may be used in the apparatus. For instance, bends may be formed in thermoplastic pipe sections of any diameter including diameters of about 90 mm up to about 1000 mm. More preferably, bends may be formed in thermoplastic pipe sections having diameters of between about 200 mm and 400 mm. It will be appreciated, however, that certain apparatus components must be appropriately sized for the diameter of the section of pipe in which the bend is to be formed. [0014] Similarly, any suitable length of pipe section may be used with the apparatus. It is envisaged that certain components of the apparatus (and particularly the retaining portion) may be adjustable so as to accommodate sections of pipe having different lengths. [0015] Any suitable bend may be formed in the section of pipe. Preferably, however, a bend of less than 900 is formed in the section of pipe. It will be understood that the actual degree of bending formed in the section of pipe is not critical to the working of the invention, and may be varied as required. [0016] In a preferred embodiment of the invention, the section of thermoplastic pipe may be heated so as to facilitate forming a bend therein. The section of pipe may be heated to any suitable degree, although in a preferred embodiment, the section of pipe may be heated to approximately its Vicat softening temperature. [0017] The section of pipe may be heated remotely to the apparatus, and then the heated section may be transported to, and received by, the apparatus. For instance, the section of pipe may be heated in an oven or the like, and then transported to the apparatus using any suitable technique. [0018] Alternatively, the section of pipe may be received in the retaining portion prior to being heated. In this embodiment, the section of pipe may be heated using any suitable technique. For instance, the retaining portion may be at least partially located within an oven, or a heating device (such as a thermal lance) may be used to heat the section of pipe in situ. [0019] The retaining portion may be of any suitable form or configuration. It is envisaged, however, that the retaining portion may comprise one or more receptacles adapted to receive and retain at least a portion of the section of pipe. Preferably, when the section of pipe is received in the retaining portion, the section of pipe is oriented substantially horizontally. [0020] In a preferred embodiment of the invention, the retaining portion may comprise a first receptacle and a second receptacle, each adapted to receive and retain a portion of the section of -r pipe. In this embodiment, it is envisaged that each of the first and second receptacles may be positioned spaced apart from one another, so that a length of the pipe section is located therebetween. Preferably, each of the first and second receptacles is spaced apart from one another so that an opposed end of the section of pipe is located retained in, or adjacent to, each of the receptacles. [0021] Preferably, the location of the first and second receptacles relative to one another may be adjusted. For instance, when a relatively long section of pipe is to be received in the retaining portion, the first and second receptacles may be moved further apart from one another to accommodate the relatively long section of pipe. Similarly, when a relatively short section of pipe is to be received in the retaining portion, the receptacles may be moved closer together. [0022] Each of the first and second receptacles may be capable of movement relative to one another. Alternatively, the position of the first receptacle may be fixed, while the second receptacle may be capable of movement relative to the first receptacle. [0023] In a preferred embodiment of the invention, each of the first and second receptacles may comprise a cup, box or similar vessel in which at least a portion of the section of pipe is received. In a preferred embodiment of the invention, each of the receptacles includes one or more substantially vertical walls. In this embodiment, each of the receptacles is provided with an aperture in at least one of the substantially vertical walls through which at least a portion of the section of pipe may project once received in the receptacles. [0024] Preferably, the first receptacle is formed with or mounted to the forming portion. The forming portion may be pivotally movable about a pivot axis. As the forming portion moves by pivoting about the pivot axis, it is envisaged that the retaining portion may move with it and bring the pipe into contact with the forming surface. [0025] At least one of the receptacles may be provided with a retention means adapted to retain the section of pipe therein. The retention means may be of any suitable form, and may be formed integrally with the receptacle or may be formed externally to the receptacle and adapted for fixed or temporary association therewith. For instance, the retention means may comprise one or more clips, clamps or the like adapted to preclude the section of pipe from being removed from the receptacles. Alternatively, when the section of pipe is positioned substantially horizontally within the retaining portion, the retention means may comprise a lid, cover or the like for at least one of the receptacles. In this embodiment, the lid, cover or the like may be adapted to prevent the section of pipe being removed from the retaining portion in a substantially vertical direction. [0026] In a preferred embodiment of the invention, the retention means may comprise a collar adapted to retain the section of pipe within the receptacle. Preferably, a collar may be provided in each of the receptacles so that each end of the section of pipe is retained by a collar. The collar may be formed integrally with the receptacle, or may be formed separately therefrom. In a preferred embodiment of the invention, the collar may be formed separately from the receptacle, but may be inserted into, and retained in, the receptacle when in use. [0027] In some embodiments of the invention, the collar may be adjustable so that sections of pipe of differing diameters may be retained by the collar. Alternatively, a plurality of collars may be provided, each adapted to retain a section of pipe of a different diameter. In this embodiment of the invention, it is envisaged that the collar may be selected based on the diameter of the section of pipe to be bent. The collar will then be inserted into the receptacle, and the section of pipe will be inserted into the collar, thereby retaining the section of pipe in place during the bending process. [0028] It is envisaged that, after the bending process, coolant may be provided to one or both of the pair of receptacles and over the formed bend. Any suitable coolant may be used, including water. Similarly, a suitable lubricant may be used, such as an oil, and more particularly a soluble oil in a water cooling solution. [0029] The forming portion may be of any suitable size, shape or configuration. As previously stated, the forming portion includes a forming surface that is brought into contact with the section of pipe so as to form a bend in the section of pipe. The forming surface may be of any suitable type, although in a preferred embodiment of the invention, the forming surface comprises an anvil that is attached to the forming portion. In this embodiment of the invention, the anvil may be removably attached to the forming portion so as to allow anvils of different dimensions to be attached to the forming portion. [0030] The anvil may be attached to the forming portion using any suitable technique. For instance, the anvil may be attached using mechanical fasteners such as bolts, rivets, screws, or the like, or a combination thereof. [0031] The anvil may be fabricated from any suitable material. Preferably, however, the anvil is fabricated from a material having sufficient rigidity such that the anvil will not bend, buckle or otherwise deform during the process of forming a bend in the section of pipe. In a preferred embodiment, the anvil may be fabricated from metal, such as steel or aluminium.

[0032] The anvil may be of any suitable dimensions, although in a preferred embodiment of the invention, the anvil is dimensioned such that between 5% and 20% of the circumference of the section of pipe to be bent is supported by, or in contact with, the anvil. More preferably, the anvil is dimensioned such that between 5% and 15% of the circumference of the section of pipe to be bent is supported by, or in contact with, the anvil. Most preferably, the anvil is dimensioned such that approximately 10% of the circumference of the section of pipe to be bent is supported by, or in contact with, the anvil. [0033] Preferably, the forming surface may be positioned on the forming portion such that the forming surface is brought into contact with the section of pipe in substantial alignment with the axial centreline of the pipe. In this way, the bend may be formed along the axial centreline of the section of pipe. [0034] In a preferred embodiment of the invention, the portion of the forming surface that is brought into contact with the surface of the section of pipe may be substantially planar. In this way, no marks or deformities are placed on the surface of the section of pipe during the bending process. Alternatively, the forming surface may be provided with one or more raised portions adapted to imprint upon the surface of the section of pipe. The raised portions may comprise one or more letters, numbers, figures, or a combination thereof. For instance, the raised portions may be used to identify the manufacturer of the pipe, the destination or purpose of the pipe, or properties of the pipe (such as the diameter). [0035] While the portion of the forming surface that is brought into contact with the surface of the section of pipe may be substantially planar, it is preferred that the forming surface itself may be curved. Thus, when the section of pipe is brought into contact with the curved forming surface, the section of pipe will bend to the shape of the forming surface, thereby forming a bend in the section of pipe. [0036] In some embodiments of the invention, the forming portion may be fixed relative to the section of pipe, and the section of pipe may be driven along the forming portion so as to form a bend in the section of pipe. Alternatively, the forming portion may move with the section of pipe. Any suitable movement of the forming portion may be used, such as a sliding movement or the like. In a preferred embodiment of the invention, movement of the section of pipe may actuate a pivoting movement of the forming portion. In a most preferred embodiment of the invention, the forming portion may be associated with the retaining portion such that movement of the retaining portion actuates a corresponding movement of the forming portion.

[0037] Preferably, the speed of the movement of the forming portion and the speed of the movement of the retaining portion is substantially identical. In this way, there is no relative movement between the forming surface and the section of pipe during the formation of the bend in the section of pipe. [0038] The drive portion may be of any suitable type or configuration. In a preferred embodiment of the invention, however, actuation of the drive portion of the apparatus results in a contact portion of the drive portion being brought into contact with the forming portion and/or the section of pipe. The contact between the contact portion and the forming portion and/or the section of pipe may be of any suitable type. For instance, the contact portion may be brought into engagement with the forming portion and/or the section of pipe, or may be brought into abutment with the forming portion and/or the section of pipe. Preferably, the contact portion comprises a mandrel. [0039] In some embodiments of the invention, a mandrel assembly may be provided, wherein the mandrel forms a portion of a mandrel assembly. The mandrel assembly may be of any suitable form. However, in some embodiments of the invention, the mandrel assembly may include a mandrel support (such as a box or the like), and a contact portion (mandrel). In a preferred embodiment of the invention, the mandrel assembly may also comprise a drive member. [0040] In a preferred embodiment of the invention, the contact portion extends at least partially into the bore in the section of pipe. The contact portion may extend any suitable distance into the bore. In a preferred embodiment of the invention, however, the extent of movement of the contact portion into the bore is controlled by providing the drive portion with one or more limit means. Preferably the one or more limit means may be adapted to engage with or abut a portion of the section of pipe or the retaining portion, thereby preventing further movement of the contact portion into the bore. Preferably, the limit means also prevent any backward movement of the section of pipe during the process of forming the bend. [0041] The limit means may be of any suitable form. For instance, the limit means may comprise one or more projections extending from the drive portion and adapted to abut the retaining portion and/or the section of pipe. [0042] Simultaneously to the limit means being brought into abutment with the retaining portion and/or the section of pipe, it is envisaged that the drive member of the mandrel assembly will abut one or more guide members associated with the forming path. In this embodiment of 0 the invention, further actuation of the drive portion forces the movement of the retaining portion along the forming path. In a preferred embodiment of the invention, movement of the retaining portion along the forming path actuates the pivoting movement of the forming portion. As the retaining portion moves along the curved portion of the forming path, the surface of the section of pipe is brought into contact with the forming surface, thereby forming a bend in the section of pipe. [0043] The drive portion may be of any suitable form. For instance, the drive portion may be actuated using any suitable mechanism, such as a motor, winch or the like. In a preferred embodiment of the invention, however, the drive portion is actuated using a ram (such as a hydraulic or pneumatic ram). Preferably, actuation of the ram brings the drive portion into abutment with the retaining portion and one or more guide members, thereby pushing the section of pipe along the forming path. [0044] In a preferred embodiment of the invention, the drive portion may be provided with a mechanism adapted to withdraw the contact portion from the section of pipe, and/or to draw the one or more guide members back along the forming path once the formation of the bend in the section of pipe is completed. Any suitable mechanism may be provided, such as, but not limited to, a second ram. [0045] The movement of the retaining portion along the forming path by the drive portion may be achieved using any suitable technique. For instance, the drive portion may drag the retaining portion along the forming path in a pulling motion, or may push the retaining portion along the forming path. Alternatively, the drive portion may abut the retaining portion (for instance, one or more guide members), and further actuation of the drive portion may push the section of pipe along the forming path. [0046] The forming path may be of any suitable form. In some embodiments of the invention, the forming path may be defined by one or more walls that define the limits of the forming path, and prevent the section of pipe from extending beyond these limits. Preferably, at least a portion of the forming path is defined by the position of the forming surface. [0047] In one embodiment of the invention the forming path may be provided with guide means. It is envisaged that the retaining portion may be associated with the guide means such that the guide means prevents any movement of the section of pipe away from the forming path. In embodiments of the invention in which the drive means pushes the section of pipe along the forming path, this is particularly advantageous in order to prevent lateral movement of the section of pipe or the retaining portion as it moves along the forming path. [0048] In a preferred embodiment of the invention, the guide means may comprise one or more channels. More preferably, the guide means may comprise one or more channels in which one or more guide members are located. [0049] The guide members may be of any suitable form. However, in one embodiment of the invention, the guide members comprise a chain including a plurality of chain links. The use of a chain including a plurality of links is preferred as it allows the guide members to move smoothly around the curved portion of the forming path, thereby ensuring that an even, smooth bend is formed in the section of pipe. [0050] As previously stated, the drive portion may further comprise a drive member adapted to abut with (or engage with) the guide members. It is envisaged that, when the drive portion is actuated, the contact portion may abut the retaining portion and/or the section of pipe, while the drive member may abut the guide members. Further actuation of the drive portion may result in the drive member pushing the guide members along the channel. [0051] In a preferred embodiment of the invention, the guide members may be associated with the retaining portion, such that movement of the guide means along the channel results in a corresponding movement of the retaining portion along the forming path. The guide members may be associated with the retaining portion in any suitable manner. However, in a preferred embodiment of the invention, the guide means may be connected to one or both of the receptacles. More preferably, one or more links at one end of the chain (the end furthest from the drive member) are connected to the receptacle at the leading end of the retaining portion (i.e. the receptacle that moves around the curved portion of the forming path first. In this way, any movement of the guide members results in a corresponding movement of the retaining portion. [0052] Furthermore, it is envisaged that the receptacle at the leading end of the retaining portion may also be connected to the forming portion. Thus, as the chain is drive along the channel by the drive member, resulting in a corresponding movement of the retaining portion along the forming path, a corresponding pivoting movement of the forming portion will also occur. [0053] In embodiments of the invention in which the guide member comprises a chain including a plurality of chain links, it is envisaged that it may be necessary to prevent unwanted movement of the links relative to one another, particularly when the chain is being pushed along the channel by the guide portion. Thus, in some embodiments of the invention, the channel may be provided with a cross-sectional profile that restricts the movement of the chain links in any direction other than along the forming path and precludes unwanted lateral movement of the chain links. It will be understood that the actual cross-sectional profile of the channel will vary depending on the shape of the chain links. [0054] As previously stated, it is preferred that the section of pipe is received in the retaining portion in a horizontal orientation (i.e. with the longitudinal axis of the section of pipe positioned substantially horizontally). Preferably, the section of pipe is maintained in a horizontal orientation at all time during the process of forming a bend in the pipe. One advantage of maintaining the pipe in a horizontal orientation is that it is easier to load an unload he section of pipe from the apparatus. [0055] In another aspect, the invention resides broadly in a method for forming a bend in a section of thermoplastic pipe, the method comprising the steps of: heating the section of pipe to approximately its Vicat softening temperature to form a heated section; loading the heated section onto a retaining portion of an apparatus for forming a bend in a section of thermoplastic pipe; advancing the retaining portion along a forming path such that the heated section is brought into contact with a forming surface associated with a forming portion of the apparatus; and further advancing the retaining portion along a curved portion of the forming path while simultaneously pivoting the forming portion to form the bend in the heated section. [0056] Any of the features described herein can be combined in any combination with any one or more of the other features described herein within the scope of the invention. [0057] The reference to any prior art in this specification is not, and should not be taken as an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge. BRIEF DESCRIPTION OF DRAWINGS [0058] Various embodiments of the invention will be described with reference to the following drawings, in which: 1[ 1 [0059] Figure 1 illustrates a perspective view of an apparatus for forming bends in a section of thermoplastic pipe according to an embodiment of the invention. [0060] Figure 2 illustrates a detailed view of an apparatus for forming bends in a section of thermoplastic pipe according to an embodiment of the invention. [0061] Figure 3 illustrates a detailed view of an apparatus for forming bends in a section of thermoplastic pipe according to an embodiment of the invention. [0062] Figure 4 illustrates a section of a retaining portion of an apparatus for forming bends in a section of thermoplastic pipe according to an embodiment of the invention. [0063] Figure 5 illustrates collars for use with an apparatus for forming bends in a section of thermoplastic pipe according to an embodiment of the invention. [0064] Figure 6 illustrates a section of a drive portion of an apparatus for forming bends in a section of thermoplastic pipe according to an embodiment of the invention. [0065] Figure 7 illustrates a section of a drive portion of an apparatus for forming bends in a section of thermoplastic pipe according to an embodiment of the invention. [0066] Figure 8 illustrates a section of a forming portion of an apparatus for forming bends in a section of thermoplastic pipe according to an embodiment of the invention. DESCRIPTION OF EMBODIMENTS [0067] In Figure 1 there is illustrated a perspective view of an apparatus 10 for forming bends in a section of thermoplastic pipe according to an embodiment of the present invention. The apparatus 10 comprises a retaining portion 11 including a pair of cups 12a, 12b adapted to receive opposed ends of a section of pipe (not shown). A first cup 12a is connected to a forming portion 13 of the apparatus 10, such that the first cup 12a is only capable of movement with, and at the same speed as, the forming portion 13. The second cup 12b is capable of movement relative to the first cup 12a so that sections of pipe of differing lengths can be received in the retaining portion 11. Once a section of pipe (not shown) is received in the retaining portion 11, the distance between the cups 12a, 12b will be fixed. [0068] The apparatus further includes a drive portion 14 comprising a hydraulic cylinder 15. Upon actuation of the hydraulic cylinder 15, a ram 16 extends from the cylinder 15 towards the retaining portion 11. The ram 16 is attached to a mandrel support (in the form of a mandrel box, to which a mandrel (not shown) would be attached in use) 17, such that the ram 16 pushes the mandrel box 17 towards the retaining portion 11 until the mandrel (not shown) abuts the second cup 12b. Simultaneously to this, a drive member (not shown) abuts a chain (not shown) located in a channel (not shown) positioned substantially below the mandrel box 17. Further actuation of the hydraulic cylinder 15 cause the drive member (not shown) to push the chain (not shown) along the channel (not shown) such that the section of pipe (not shown) moves along a forming path that includes a curved portion 18. This movement of the section of pipe (not shown) is achieved by the fact that the chain (not shown) is connected to the forming portion 13 under the first cup 12a. Thus, movement of the chain (not shown) results in a corresponding movement of the first cup 12a, which in turn results in the movement of the section of pipe (not shown) along the forming path. The forming portion 13 is connected to the first cup 12a such that movement of the retaining portion 11 along the forming path results in the forming portion 13 pivoting about pin 19 in response to the, bringing the surface of the section of pipe (not shown) into contact with a forming surface (obscured) and thereby forming a bend in the section of pipe. [0069] In Figure 2 a detailed view of the drive portion 14 of the apparatus shown in Figure 1 is illustrated. In this Figure, the attachment of the mandrel box (alternatively called the mandrel retaining box) 17 to the ram 16 may be more clearly seen. [0070] In Figure 3 a detailed view of the retaining portion 11 and forming portion 13 of the apparatus shown in Figure 1 is illustrated. The cups 12a, 12b may be seen spaced apart from one another in preparation for receiving a section of pipe (not shown). The cups 12a, 12b are provided with lids 20 that can be opened to allow collars (not shown) adapted to retain pipes of different sizes to be inserted into the cups 12a, 12b. It may also be seen that the first cup 12a is connected to the forming portion 13. [0071] In this Figure, it may be seen that the cups 12a, 12b include apertures 21 in a wall thereof through which the section of pipe (not shown) is adapted to at least partially extend. Once a section of pipe (not shown) is received in the retaining portion 11, the cups 12a, 12b become incapable of movement relative to one another. [0072] In use, an internal mandrel box (not shown) moves into abutment with the second cup 12b, while a drive member (not shown) simultaneously moves into abutment with a chain (not shown). Further movement of the drive member (not shown) pushes the chain (not shown) along the channel (not shown). As the chain is connected to the forming portion 13 and the first cup 12a, movement of the chain (not shown) forces the retaining portion 11 to move along the forming path, including the curved section 18 of the path. The retaining portion 11 and the forming portion 13 are connected to one another such that movement of the retaining portion 11 along the forming path results in the pivotal movement of the forming portion 13 about pin 19. As the forming portion 13 pivots, the surface of the pipe is brought into contact with a curved forming surface in the form of an anvil 22. As the forming portion 13 is associated with the retaining portion 11, the forming surface 22 and the section of pipe (not shown) move along the forming path at the same speed relative to one another. Thus, the forming surface 22 is maintained in static contact with the section of pipe (not shown) during the entire process of forming the bend in the pipe. [0073] In Figure 4, a partial view of the retaining portion 11 is shown. In this Figure the second cup 12b and the aperture 21 through the walls thereof through which a section of pipe (not shown) extends in use may be seen. [0074] In the embodiment of the invention shown in Figure 4, the drive member (not shown) would abut the chain 23 which would in turn be connected to the first cup (not shown). Thus, as the chain 23 is driven along the channel or track 24, the section of pipe (if present)would be pushed along the curved section of track 24 so that the forming portion 13 pivots. Thus, if a section of pipe was present, the surface of the section of pipe would be held in abutment with the curved forming surface 22 and a bend would be formed in the pipe. [0075] In Figure 5 collars 25 for use with an apparatus for forming bends in a section of thermoplastic pipe may be seen. The collars are adapted to be inserted into the cups (not shown) so that the section of pipe (not shown) may extend therethrough. It will be noted that the collars 25 are provided with different diameter apertures therein so that pipes of different diameters may be used with the apparatus. [0076] In Figures 6 and 7 there are shown sections of a drive portion of an apparatus for forming bends in a section of thermoplastic pipe according to an embodiment of the invention. In this Figure, a guide member in the form of a chain having a plurality of chain links 26 may be seen. The chain links 26 are located in a track 24, along which the chain links 26 move when the drive portion is actuated (through the abutment of a drive member (not shown) attached to the lower wall of the mandrel box 17 with the chain link having a free end). The drive member effectively pushes the chain along the track 26. The track 24 is provided with a profile that is shaped so as to restrain the chain links 26 and prevent unwanted lateral movement. As a result, the chain links 26 move along the track 24 smoothly and at a constant speed to one another. [0077] In Figure 8 there is shown a section of the forming portion 13 of an apparatus for 1 -r forming bends in a section of thermoplastic pipe according to an embodiment of the invention. In this Figure, the pin 19 about which the forming portion 13 pivots on actuation of the drive means is more clearly seen. The pin 19 is supported by a bearing 27 that allows the forming portion 13 to pivot about the longitudinal axis of the pin 19. [0078] In the present specification and claims (if any), the word 'comprising' and its derivatives including 'comprises' and 'comprise' include each of the stated integers but does not exclude the inclusion of one or more further integers. [0079] Reference throughout this specification to 'one embodiment' or 'an embodiment' means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases 'in one embodiment' or 'in an embodiment' in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations. [0080] In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims (if any) appropriately interpreted by those skilled in the art.

Claims (5)

1. An apparatus for forming a bend in a section of thermoplastic pipe, the apparatus comprising: a retaining portion adapted to receive and retain part of the thermoplastic pipe; a forming portion including a forming surface about which a bend in the section of thermoplastic pipe is formed; and a drive portion operative to cause movement of the retaining portion along a forming path, the forming path including a curved portion, and wherein the section of thermoplastic pipe is brought into contact with the forming surface as the retaining portion moves along the curved portion of the forming path, thereby forming the bend in the section of thermoplastic pipe.

2. An apparatus according to claim 1 wherein the forming surface comprises an anvil dimensioned such that approximately 10% of the circumference of the section of pipe is supported by, or in contact with, the anvil.

3. An apparatus according to claim 1 or claim 2 wherein the section of pipe is maintained in a substantially horizontal orientation at all times during the formation of the bend.

4. An apparatus according to any one of claims 1 to 3 wherein the drive portion includes a ram adapted to abut the retaining portion, thereby pushing the section of pipe along the forming path.

5. A method for forming a bend in a section of thermoplastic pipe, the method comprising the steps of: heating the section of pipe to approximately its Vicat softening temperature to form a heated section; loading the heated section onto a retaining portion of an apparatus for forming a bend in a section of thermoplastic pipe; advancing the retaining portion along a forming path such that the heated section is brought into contact with a forming surface associated with a forming portion of the apparatus; and IV further advancing the retaining portion along a curved portion of the forming path while simultaneously pivoting the forming portion to form the bend in the heated section.