GB2214859A

GB2214859A - Pipe expanding device

Info

Publication number: GB2214859A
Application number: GB8803958A
Authority: GB
Inventors: Martin Lawrence
Original assignee: British Gas PLC
Current assignee: British Gas PLC
Priority date: 1988-02-19
Filing date: 1988-02-19
Publication date: 1989-09-13
Anticipated expiration: 2008-02-19
Also published as: GB2214859B; GB8803958D0

Abstract

A device for expanding the internal diameter of a plastics pipe has two internally threaded members 3, 4 mounted on opposite-hand screw threaded portions 2a and 2b, respectively, of rotatable element 2. The member 3, 4 slidably engage segments 5. Rotation of the element 2 causes the members to move along the element and urge the segments radially outwardly. In use, the segments engage the internal wall of the pipe and are forced outwards to expand the pipe. <IMAGE>

Description

Pipe Expanding Device The present invention relates to devices or tools used on pipes and, more particularly, to a device for expanding a pipe, such as a plastics pipe.

In order to introduce a fitting or insert into a plastics pipe, for example, it may first be necessary to expand the diameter of the pipe.

The invention consists in a device for expanding the internal diameter of a pipe, comprising an elongate externally threaded element, at least one internally threaded member located on the element, a plurality of expander means in movable engagement with the at least one threaded member and means for substantially preventing relative movement in a longitudinal direction between the element and the expander means, said element being rotatable about its axis with respect to the at least one member to cause the latter to move the expander means generally radially outwardly as the member moves along the element.In use the device is inserted in the end of a pipe, and the threaded element is rotated to cause the expander means to abut the internal surface of the pipe wall and to expand the diameter of the pipe as the expander means is forced further radially outwardly of the threaded element by the movement of the threaded member along the element.

Two such threaded members may be provided with both being in movable engagement with the expander means. In this case, one member may be located on a portion of the element having a screw thread of one hand and the other member may be located on a portion of the element having a screw thread of the opposite hand. Thus, when the element is rotated the two members move in opposite directions to each other.

Conveniently, the or each threaded member and the expander means may comprise interengaging grooves or channels and formations which extend substantially longitudinally of the threaded element such that the or each member is substantially non-rotatable with respect to the expander means about the axis of the element. In one embodiment the expander means may comprise radially inwardly extending extending formations which are slidably engaged in grooves or channels in, and opening outwardly from, the or each threaded member.

Preferably, in a longitudinal direction of the element, the surfaces of the or each threaded member and expander means which interengage to cause the expander means to move radially outwardly are substantially linear and extend at a substantially common angle to the axis of the element. Where the device has two members which move in opposite directions along the element, the respective interengaging surfaces of each member and the expander means, in a direction longitudinally inwardly of the device, may be inclined towards the axis of the element, such that it is the movement of the members towards each other along the element which causes the expander means to move generally radially outwardly.

The means for substantially preventing longitudinal movement between the element and the expander means may be an annular flange provided on the element, the annular flange being rotatably located in grooves or channels opening radially inwards from the expander means. Where the device comprises two threaded members movable in opposite directions, conveniently the annular flange is located between the two members.

Preferably, the expander means are retained in engagement with the or each threaded member by resilient biasing means which urge the expander means generally radially inwardly. The expander means may, for example, be connected together by resilient biasing means such as tension springs.

Advantageously, the outer surface of each expander means is of part cylindrical form. Thus, the part cylindrical forms may be such that together they substantially conform to or match the internal cylindrical surface of a pipe on which the device is to be used. Adjacent one end of the the device the outer surfaces of the expander means may be of part frustoconical form and taper in a direction towards said one end. When the device is in use, these tapered portions together may provide a region of transition between the pipe material expanded by the part cylindrical forms and the adjacent non-expanded pipe material to reduce stresses in the pipe material as the pipe is expanded.

Where the pipe material more readily accommodates expansion the tapered portion may be omitted from the device.

Conveniently, the threaded member or one of the threaded members is provided with means to facilitate holding the or said one member in a substantially fixed rotary position to resist it turning with the element as the latter is rotated. The holding facilitating means may comprise a handle connected to the or said one member. For example, the handle may extend transversely from a tubular part which is connected to the or said one member and surrounds the elongate element.

The invention will now be further descirbed, by way of example only, with reference to the accompanying drawings, in which Figure 1 is a perspective view of one embodiment of the device according to the invention, and Figure 2 is a side view of the device shown in Figure 1 with one of the expander means removed and an end tubular part partly broken away to reveal the end of the threaded element.

With reference to the drawings, a device 1 made from suitable metal components for expanding the internal diameter of a pipe, comprises a rotatable elongate element 2 having a screw threaded portion of one hand 2a and a screw threaded portion of the opposite hand 2b. On each threaded portion 2a, 2b is a respective internally threaded annular member 3,4 which when the device is in use serve as wedge-like members.

Equidistantly disposed around the peripheries of each of the two members 3,4 are three radially extending grooves or channels 3a, 4a opening outwardly. Each groove also extends longitudinally of the threaded element 2 and is aligned with a corresponding groove in the other annular member.

Three expander means or segments 5 are mounted on the threaded members 3,4 by means of longitudinally extending web portions 6, each of which is slidably engaged in a respective pair of aligned grooves 3a, 4a. The three expander means 5 are held in position in the grooves 3a, 4a by tension springs 7 which at each end of the device connect each expander means to each adjacent expander means.

In a longitudinal direction of the element 2, the surfaces 3b, 4b and 8 respectively of the annular members 3,4 and web portions 6 which interengage are linear and, in a direction inwardly from each end of the device, such surfaces incline or slope towards the longitudinal axis of the element as can be seen in figure 2.

Centrally of the device between the two threaded members and at the junction of the different hand screw threaded portions 2a, 2b, an annular flange 9 is provided on the element 2. The flange 9 is rotatably located in grooves or channels 10 opening radially inwards from the web portions 6 of the expander means.

The location of the flange 9 in the grooves 10 serves substantially to prevent relative movement in a longitudinal direction substantially parallel to the axis of the element 2 between the individual expander means 5, and also between the element 2 and the expander means 5, whilst the location of the web portions 6 in the grooves 3a, 4b also serves substantially to prevent rotation of the annular members 3, 4, with respect to the web portions 6 and thus the expander means 5 about the element.

The radially outer surface of each expander means has a portion which is part cylindrical 5a and a portion which is part frustoconical 5b and tapers in a direction to an adjacent end of the device.

The threaded element 2 is rotated about its axis by means of torque applied to a nut 11 fixed to the element adjacent the end thereof whilst the annular members 3,4 and expander means 5 are held rotably fixed by manual holding of a handle 12 which extends radially from a tubular part 13 which is connected to the annular member 4 and surrounds but is spaced from the element. A coaxial tubular part 14 having a closed or sealed outer end is connected to the annular member 3 and projects from the end of the device. Part 14 surrounds but is spaced from the end portion of the element 2 and serves to protect the screw thread, for example, from dirt or corrosive material. The tubular part 14 may also be used to facilitate lifting and moving of the device.

As may be appreciated from Figure 2, row toting the element in one direction will cause the annular threaded members 3,4 to move toward each other along the element and slide along the engaged web portions 6. The bases of the groove; in the annular members serve as wedging surfaces 3b,4b which slidably engage the radially inner surfaces 8 of the web portions 6 and, as the annular members move toward each other, force the expander means radially outwardly of the element. It will also be appreciated that the various surfaces of the component parts which move over each other may be lubricated e.g. with grease, as required.

The device may be used to expand the internal diameter of an end portion of a pipe, for example a polyethylene pipe, such that a previously too large a diameter fitting or insert can be introduced into the end of the pipe.

The device may also be used in a method of coupling two polyethylene pipes together wherein the method comprises expanding the internal diameter of at least one of the pipes, introducing an insert into the expanded pipe to retain the pipe in an expanded condition and fitting a coupling, such as an electrofusion coupling, to the expanded insert-containing pipe.

The pipe to be expanded may initially be of a non-standard, smaller external diameter compared with the internal diameter of the coupling.

Claims

1. A device for expanding the internal diameter of a pipe, comprising an elongate externally threaded element, at least one internally threaded member located on the element, a plurality of expander means in movable engagement with the at least one threaded member, and means for substantially preventing relative movement in a longitudinal direction between the element and the expander means, said element being rotatable about its axis with respect to the at least one member to cause the latter to move the expander means generally radially outwardly as the member moves along the element.

2. A device as claimed in claim 1, comprising two said threaded members which are moveable along the threaded element.

3. A device as claimed in claim 2, in which one said member is located on a portion of the element having a screw thread of one hand and the other said member is located on a portion of the element having a screw thread of the opposite hand, the members moving in opposite directions when the element is rotated relative to them.

4. A device as claimed in any of the preceding claims, in which the or each threaded member and the expander means comprise interengaging grooves or channels and formations which extend substantially longitudinally of the threaded element, such that the or each member is substantially non-rotatable with respect to the expander means about the axis of the element.

5. A device as claimed in claim 4, in which the expander means comprise radially inwardly extending formations which are engaged in grooves or channels in, and opening outwardly from, the or each threaded member.

6. A device as claimed in any of the preceding claims, in which in a longitudinal direction of the element, the surfaces of the member or members and expander means which interengage to cause the expander means to move radially outwardly are substantially linear and extend at a substantially common angle to the axis of the element.

7. A device as claimed in claim 6 as dependent on claim 3, in which the respective said interengaging surfaces associated with each member, in a direction longitudinally inwardly of the device, are inclined towards the axis of the element, such that movement of the members towards each other cause the expander means to move generally radially outwardly.

8. A device as claimed in any of the preceding claims, in which the means for substantially preventing longitudinal movement between the element and expander means is an annular flange on the element which is rotatably located in grooves or channels opening radially inwards from the expander means.

9. A device as claimed in claim 8 as dependent on claim 3, in which the annular flange is located between the two said members.

10. A device as claimed in any of the preceding claims, in which the expander means are retained in engagement with the or each threaded member by resilient biasing means which urge the expander means generally radially inwardly.

11. A device as claimed in claim 10, in which said resilient biasing means connect the expander means together.

12. A device as claimed in any of the preceding claims, in which the outer surfaces of the expander means are of part cylindrical form.

13. A device as claimed in claim 12, in which adjacent one end of the device the outer surfaces of the expander means are of part frusto-conical form tapering in a direction towards said one end.

14. A device as claimed in any of the preceding claims, in which the threaded member or one of the members is provided with means to facilitate holding the or said one member in a substantially fixed rotary position to resist it turning with the element.

15. A device as claimed in claim 14, in which the holding facilitating means comprises a handle connected to the or said one member.

16. A device as claimed in claim 15, in which the handle extends transversely from a tubular part which is connected to the or said one member and surrounds the elongate element.

17. A device for expanding the internal diameter of a pipe substantially as hereinbefore described with reference to the accompanying drawings.