GB2306600A

GB2306600A - An upright socket and spigot assembly

Info

Publication number: GB2306600A
Application number: GB9701061A
Authority: GB
Inventors: John Sydney Holgate
Original assignee: Glasdon Ltd; Glasdon Group Ltd
Current assignee: Glasdon Ltd; Glasdon Group Ltd
Priority date: 1993-04-20
Filing date: 1993-04-20
Publication date: 1997-05-07
Anticipated expiration: 2013-04-20
Also published as: GB2277292B; GB2277292A; GB9308067D0; GB9701061D0; GB2306600B

Abstract

An upright assembly comprises a double-walled socket 50 and a spigot 52. The spigot has axially spaced annular walls 53, 54 which mate with corresponding walls 58, 59 in the socket 50 to provide an assembly which is easily releasable. An intermediate annulus 55 between walls 53, 54 remains spaced from an inner wall 60 of socket 50 upon mating with spigot 52. Socket 50 includes a projection 61 to assist anchorage of socket 50 in a hole in the ground.

Description

AN UPRIGHT ASSEMBLY The present invention relates to an upright assembly having a spigot and socket assembly at least part of which may be produced by a method of moulding a double-walled product.

This is a divisional application derived from UK Patent Application No.

9308067.9.

It is known to produce moulded products using the technique of rotational moulding. In such a technique a hollow mould, usually of sheet steel or a thin walled aluminium casting, is charged with finely ground thermoplastic powder and gently rotated about t'vo axes whilst the mould is heated externally either by direct gas flame or by placing it in an oven. As the mould temperature approaches the melting point of the thermoplastic, a layer of powder fuses to the surface of the mould and the residual powder continues to be tumbled by the rotational motion.

The loose powder is tumbled such that it flows over all internal surfaces of the mould until it has all been fused to form a homogeneous layer of molten plastic on the internal wall of the mould. The mould is then cooled, the plastic solidifies and its natural thermal contraction causes it to separate from the wall of the mould which will have been treated with a surface coating prior to charging to aid this release. The mould is then opened and the finished moulding removed.

It is inherent in the rotational moulding process that the amount of shrinkage and distortion which occurs in a moulding as it cools and solidifies is variable and is not controlled or restrained by the mould itself. In addition, the wall thickness and the evenness of the internal surface of the moulding are subject to variation as a result of the flow of the plastic powder under the rotational motion of the mould and the fact that only one surface of the moulding is controlled by contact with the mould.

Accurate dimensions and minimal distortion are important in moulded products such as spigot and socket connections in which a close fit is required.

Such a spigot and socket connection is commonly used in a bollard and socket assembly, the components of which are conventionally moulded. The socket is permanently set in the ground and the bollard is removably mounted in the socket such that the external surface of the spigot mates with the internal surface of the socket. A conventionally moulded socket or spigot will often be subjected to axial and/or radial distortion during the cooling step as described above. Furthermore, the socket and spigot are likely to have different amounts of shrinkage. These distortions and shrinkages and the uneven internal surface of the socket affect the fit of the connection which is either too sloppy or has unacceptable interference preventing easy release.

It is an object of the present invention to obviate or mitigate the aforesaid problems.

According to the present invention there is provided an upright assembly having a spigot and socket connection, the socket being designed for anchorage in the ground, the connection comprising a socket having an inner wall shaped to receive a spigot, the spigot having at least two annular surfaces axially spaced by an intermediate annulus, the annular surfaces contacting the inner wall of the socket and the intermediate annulus being spaced from the inner wall of the socket.

The invention will now be further described by way of example only, with reference to the accompanying drawings, in which: Figs. 1 and 2 are side views of a product being moulded according to the method of the present invention; Fig. 3 is a cross-sectional side view of a mould with a double-walled moulded product of an aspect of the present invention located therein; Fig. 4 is an exploded view of figs. 1 and 2 showing moulded products released from respective moulds; Fig. 5 is a side view of a bollard having a spigot according to an aspect of the present invention; Fig. 6 is a side view of a doublc-walled socket moulded according to the method of the present invention; Fig. 7 is a side view of an assembly of the bollard and socket of figs 5 and 6 respectively, the socket shown in cross-section.

Referring now to figures 1 and 2 of the drawings there is shown moulding apparatus for moulding a bollard and a socket which are to be used in combination.

A socket mould 1 and a bollard mould 2 are mounted on a frame assembly 3 which comprises t'vo circular end frames 3a connected to a central frame 3b which receives the moulds 1,2. In engagement with each end frame 3a is a drive wheel 4, one wheel 4 being mounted at each end of a drive shaft 5.

The drive shaft S can be driven by means (not shown) to rotate the shaft 5 and the drive wheels 4 about the longitudinal axis of the shaft 5. The frame assembly 3 is driven by the rotating drive wheels 4 such that it rotates (as indicated by arrow Y) about a longitudinal axis parallel to the drive shaft axis and passing through the moulds 1,2.

The drive shaft 5 is mounted such that is pivotable about an axis passing through point X and perpendicular to the plane of the page on which figures 1 and 2 are shown. Drive means (not shown) can be operated to pivot the shaft 5 causing the frame assembly 1 to pivot as shown by arrow Z about a small arc both clockavise and anticlockwise to provide a rocking motion to the frame assembly 1.

One extremity of the rocking motion of one end of the shaft 5 is shown in dotted line in figure 1.

Figure 4 shows the component parts of the socket and bollard moulds 1,2.

The bollard mould 2 comprises a top portion 6, t'vo main body halves 7 and an end spigot mould portion 8. The socket mould 1 comprises a female portion 9, a male portion 10, a top plate 11 and a base 12.

The male portion 10 of the socket mould 1 is of cylindrical cross-section and is hollow, a first part 10a of the cylinder is of constant diameter whereas the remainder has a radially inward gradual taper 10b. The end of the taper 10b has a radially inward directed flange 13. The male portion 10 is shown in figure 4 with the top plate 11 mounted thereon.

The top plate 11 (see figure 3) is ring shaped with a central circular aperture 14 offset from the central axis.

The female portion 9 of the socket mould 2 is a hollow cylinder with radially outwardly extending flanges 15,16 at each end. Immediately adjacent the flange 15 the cylinder wall is inclined radially outwardly. The base 12 is frustoconical and is formed from an annular wall 17 of U-shaped cross-section (see figure 3), the limbs of the U providing an inner and an outer wall 18 and 19 respectively.

The outer wall 19 has a radially outwardly directed flange 20, whereas the inner wall 18 has a radially inwardly directed flange 21.

The components of the socket mould 1 are shown assembled in Figure 3.

The outer wall flange 20 of the base 12 is held (by means not shown) in abutment with the radial flange 16 of the female portion 9 and the male portion 10 is inserted into the female portion 9 until the inwardly directed flanges 13,21 of the male portion 10 and the base 12 abut one another. The mould assembly is closed by top plate 11 which abuts the outwardly extending flange 15 of the female portion 9. It can be seen from figure 3 that the assembly forms an closed internal mould cavil 22 defined by the outside surface of the male portion 10, the inside surface of the female portion 9, the top plate 11 and the interior surface of the U-shaped wall 17 of the base 12.

The male portion 10 has an aperture 23 in the constant diameter wall 10a and prior to the moulding process a first core piece 24 of substantially circular cross-section with an abutment flange 25 is fitted into the aperture 23 to close it with an end of the core piece 24 protruding from the outer surface of the male portion 10. The protruding end has a semi-circular cross-section. In addition, the male portion 10 has an elongate axially extending slot 26 roughly diametrically opposite the aperture 23. A second core piece 27 is passed through the offset aperture in the top plate 11 and fits in the slot 26 to close it hen the mould is assembled for the moulding process.

The components and assembly of the bollard mould 2 are not described in detail as in the embodiment shown they do not comprise part of the various aspects of the present invention.

The bollard and socket moulds 1, 2 each have an aperture designed to receive a filler pipe 28 which extends into the mould cavity. Filling of the mould with mould material is accomplished partly by filling a mould half and is completed through the filler pipe 28 of the closed mould which also allows the moulded product to breathe during the moulding process.

Using the moulds described above the bollard and socket are rotationally moulded in a conventional manner. The moulds are charged with finely ground thermoplastic powder through the filler pipes 28 and gently rotated and rocked (as indicated by arrows Y and Z) about the respective axes whilst the mould is heated by a fuzed gas burner 29 with a plurality of flame jets (see figure 1). The thermoplastic material melts as described in the preamble above until all the loose powder has been fused to form a homogeneous layer of molten plastic on the internal wall of the mould cavity. As can be seen from figure 3 the molten plastic in the cavity 22 socket mould 1 forms a hollow double walled moulded socket product 50.

The mould is then cooled by water jets 30 (see figure 2). During cooling the plastic undergoes natural contraction. An outer wall 51 of the socket moulding 50 separates from the female portion 9 of the socket mould 1 and the base 12 whilst the inner wall 52 of the socket moulding 50 contracts on to the male portion 10 and the inner wall of the base 12.

After cooling the mould assemblies are opened to release the moulded products. In the socket mould 1 release of the socket moulding 50 can be assisted by removal of the core pieces 24,26 from their respective apertures which enables the socket moulding 50 to be released by twisting it relative to the male portion 10.

The shape and configuration of the moulded bollard and socket and their assembly in use will now be described in detail with reference to figures 5 to 7.

Figure 5 shows a bollard 51 of cylindrical cross-section. The upper part of the bollard 51 is a conventional decorative design not forming part of the present invention and will be described no further. The lower part of the bollard 51 is a spigot indicated generally by arrow 52 which is designed to locate in a bore of the socket 50. The spigot 52 comprises two axially spaced relatively narrow annular walls 53,54 of constant diameter spaced by a tapered wall 55. The upper annular wall 53 is of greater diameter than the lower wall 54. The spigot 52 has longitudinal grooves 52a along its surface traversing the tapered wall 55 and the annular walls 53,54. The upper annular wall 53 has an integral key 56 extending down the upper wall 53 to the tapered wall 55. Diametrically opposite the key 56 there is a circular aperture (hidden in figure 5).

Figure 6 shows the socket 50 with an internal bore 57 shown in dotted line.

The bore 57 has an upper and lower annular walls 58,59 of constant diameter spaced axially by a tapered wall 60. The external surface of the socket is cylindrical with a step 61 which separates an upper portion 62 being of substantially constant diameter from a base portion 63 which has a slight radially inward taper. The upper annular wall 58 of the bore 57 has a narrow slot 63 extending along its full length. Diametrically opposite the slot 63 is a semicircular recess 64. The slot 63 and recess 64 are formed in the moulding process by the core pieces 23,26 described above.

In use the socket 50 is permanently set in the ground such that its top edge is roughly flush with the ground surface. The bollard 51 is then removably located in the socket 50 (as shown in figure 7) by aligning the spigot key 56 with the corresponding slot 63 in the socket 50 and pushing downwards until the bollard body 51 abuts the top surface of the socket 50. In this position the exterior surfaces of the annular walls 53,54 of the spigot 52 mate with the corresponding surfaces of the annular walls 58,59 of the socket 50 whereas there is a clearance between the surfaces of the tapered walls 55,60 of the spigot 52 and the socket 50 respectively.

B'hen the spigot 52 of the bollard 51 is inserted into the socket 50 it is automatically locked in place by a gravity latch which is fitted in the interior of the bollard 51. The latch is generally indicated by arrow 65 and comprises a hook shaped member 66 pivotally connected to a hinged bracket 67. A stem of the hook 66 has an inclined upwardly extending release plate 68. One half of the hinged bracket 67 is connected to the hook 66 whereas the other half is connected to the interior of the upper annular wall 53 of the spigot 52. In the rest position under the bias of gravity the end of the hook 66 protrudes through the aperture in the spigot 52 and abuts the top surface of recess 64. An attempt to lift the bollard 51 from the socket 50 is prevented by the engagement of the hook 66 with the recess 64.In order to release the latch 65 a specially designed key 69 is inserted through an aperture provided in the bollard 51 just above the spigot projection 56. The action of inserting the key 69 brings its tip into engagement with the plate 68 and continued insertion causes the plate 68 to move and the hook 66 to pivot against its gravity bias to disengage it from the recess 64. The bollard can then be removed from the socket. The engaged and disengaged positions of the latch 65 are shown in the fragmentary enlarged view of figure 7.

The primary advantages of the above described moulding method and moulded products lie in the socket 50 being a double-walled moulding and in the mating of the spigot 55 and socket 50 on the surfaces of the constant diameter annular walls 53,58;54,59. The double-walled moulding of the socket 50 is achieved by using a male mould portion 10 on to which the moulded socket bore 57 contracts during cooling. The socket bore is thus provided with a surface which is can be accurately controlled in terms of diametric tolerances and surface accuracy.

The provision of the two pairs of relatively narrow mating surfaces reduces the mating area and thus the binding effect caused by axial and radial distortion and general unevenness of the respective surfaces and dirt or debris which may become trapped between the two surfaces of each pair when the bollard and socket are in use. The use of two different diameters of mating surfaces facilitates disengagement of the bollard from the socket as the bollard only needs be lifted through the vertical depth of one annular surface in order to free it from close engagement.

The provision of the longitudinal grooves 52a in the spigot 52 provide venting channels which permit egress and ingress of airAvater as the bollard is inserted or withdrawn.

It will be appreciated that the latch mechanism 65 described above is by way of example only and that other releasable locking members could be used.

The key 56 and slot 63 provide an aid to location of the bollard 51 in the socket 50 in the correct orientation and also prevent undesirable rotation of the bollard 51 in the socket 50 which may damage the engaged latch mechanism 65 of the assembly.

The stepped feature 61 on the exterior of the socket 50 assists in the permanent anchorage of the socket 50 in the ground.

The socket 50 may have an opening (not shown) adjacent its lower end to allow drainage of rainwater from the assembly. Such an opening will not be effective if the socket 50 is set in concrete so as an addition, or an alternative the spigot 52 may have an opening (not shown) at or near its end to allow rainwater to rise up in the interior of the spigot 52. In the latter case an opening towards the top of the spigot is also provided to allow the air displaced by the rainwater to escape, thus preventing a build up of pressure in the bollard.

It will be appreciated that the moulding process described above is not necessarily limited to the production of the socket described but is suitable for the production of any double-walled product.

Claims

1. An upright assembly having a spigot and socket connection, the socket being designed for anchorage in the ground, the connection comprising a socket having an inner wall shaped to receive a spigot, the spigot having at least two annular surfaces axially spaced by an intermediate annulus, the annular surfaces contacting the inner wall of the socket and the intermediate annulus being spaced from the inner wall of the socket.

2. An upright assembly according to claim 1, wherein the annular surfaces have different diameters.

3. An upright assembly according to claim 1 or 2, wherein the spigot has a longitudinal venting channel to allow ingress and egress of air or water as the spigot is inserted or removed from the socket.

4. An upright assembly according to any one of claims 1 to 3, wherein there is provided a latch for releasably retaining the spigot in the socket.

5. An upright assembly according to claim 4, wherein the latch is biased to engage an abutment in the interior wall of the socket.

6. An upright assembly according to claim 5, wherein the spigot has an aperture and the latch is releasable from the abutment by inserting a key in the aperture.

7. An upright assembly according to any preceding claim, wherein there is provided a protrusion which mates with a corresponding groove to prevent rotation of the socket relative to the spigot.

8. An upright assembly according to any preceding claim, wherein there is provided a projection on the exterior of the socket to assist anchorage of the socket in a hole in the ground.

9. An upright assembly according to any preceding claim, wherein the socket has an opening at or near one end to permit drainage of water.

10. An upright assembly according to any preceding claim, wherein the spigot has a first opening to allow water in the assembly to rise inside the spigot and a second opening to allow air to escape as it is displaced by the collected water.

11. An upright assembly substantially as hereinbefore described with reference to the accompanying drawings.