GB2150071A - Mould for producing concrete articles - Google Patents

Abstract

A mould for producing a pre-stressed concrete article having securing members projecting from the surface thereof at pre-determined, selected, spacings, the mould including a bottom (32) and two side walls (21,52) at least one of the side walls (52) having apertures corresponding to the positions of the securing members in the completed article and means enabling ready interchangeability of the apertured side wall so that alternative side walls can be substituted with different aperture spacings. The moulds are particularly used to manufacture railway crossing bearers. <IMAGE>

Description

SPECIFICATION Manufacture of concrete articles This invention relates to the manufacture of concrete articles such as railway crossing bearers in which it is necessary to provide securing members at various points in the manufactured article.

For many years prestressed concrete railway sleepers have been used in the United Kingdom and many other parts of the world with considerable success because of the longevity and lower maintenance costs than for wooden sleepers. For conventional sleepers or railroad ties the spacing between the securing members for the rails is precisely predetermined by the track gauge and hence an identical mould can be used for hundreds or possibly thousands of moulding operations. In contrast, crossing bearers (switch ties in the United States) present special problems because the spacing of the securing devices varies from point to point as the track diverges or converges.At the immediate zone of divergence (or convergence) it is only practical to support the diverging tracks on the same bearers or ties although the more remote from the actual point of the junction the less the need to employ elongate bearers so that it becomes possible to revert to conventional sleepers or railroad ties.

Nevertheless, there is some advantage in carrying both tracks for a short distance beyond the point where there is complete divergence because forces at the crossing or switch generated by the trains on the rails are higher than normal and elongate crossing bearers spanning both tracks give rise to greater stability.

it has already been proposed to cast concrete crossing bearers without any apertures for receiving rail securing members and subsequently to form apertures or blind holes and then fix the rail securing members by means of an epoxy resin. The process is, however, expensive in time and the use of an epoxy in the quantities involved is also comparatively costly.

According to the present invention there is provided a mould for producing a prestressed concrete article having securing members projecting therefrom at predetermined spacings, said mould comprising a bottom and two side walls, at least one of the side walls having apertures corresponding to the positions of the securing members in the completed article, and means enabling ready interchangeability of the apertured side wall so that alternative side walls can be substituted with different aperture spacings.

Further according to the present invention there is provided a mould for producing a prestressed concrete article having securing members projecting therefrom at predetermined spacings, the mould comprising an elongate bottom wall, an elongate side wall fixed relative to the bottom wall, an elongate side wall movable relative to the fixed side wall and having apertures therein corresponding to the locations of the said securing members, a series of upright members supporting the movable side wall, means detachably secured to the upright members and engageable in further apertures of the movable side wall, readily detachable bracing means extending between the upper ends of the upright members and the upper edge of the fixed side wall, and means detachably securing the upright members relative to the elongate bottom wall, the movable, apertured, side wail being also readily removable to enable substitution of a corresponding side wall with a different aperture spacing.

The invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings in which: Figure 1 is a perspective view of part of a crossing bearer mould assembly; Figure 2 is a fragmentary side elevation of the assembly illustrated in Figure 1; and Figure 3 is an end view of the assembly of Figures 1 and 2.

Referring now to the drawings, the mould includes a plurality of inverted, channel-section, transverse support members 10 which each pivotally carry a stirrup 1 2 including a bolt 14 and a transverse, tapped, block 16.

The bolt 1 4 co-operates with a triangularshaped member 1 8 which co-operates with other parts of the mould assembly to be described hereinafter.

The inverted channel section members 10 carry the mould assembly which includes a plurality of upright, fixed, box section members 20 which together support at least one fixed plate 21 each forming a fixed side wall of the mould. Alternative ones of the upright members 20 have at the upper end two upstanding spigots 22 which are bifurcated at their upper, free, ends and receive screwthreaded rods 24 by which the opposed mould side wall assemblies are held together at their upper ends. The spacing of the side wall assemblies is adjustable by means of nuts 26 but for any given article, the inner nuts 28 will be welded to the rod so that the spacing of the side wall assemblies is always the same after a de-moulding operation. The nuts 26 are removable.

An adjustable and removable side wall assembly 30 is spaced from the first-mentioned side wall assembly by a mould bottom in the form of a horizontal plate 32 welded to an upright plate 34 and strengthened by gussets 36 at each corner. The horizontal plate is also welded to the fixed side wall 21 of the lefthand (as shown) side wall assembly 20. An end plate 35 and corresponding plates (not shown) along the length of the mould bottom ensure additional strength. The right-hand side wall assembly 30 includes a plurality of upright members 31 which are mounted on the channel section members 10 and are accurately and firmly located thereon by means of the stirrups 1 2 and the triangular shaped members 1 8 engaging the inverted channel section member and the corresponding upright member.Each upright member 31 has welded thereto a plate of angle section 38, an upright limb 40 of which abuts the upright plate 34 of the mould base. A bolt and nut 42,44 serve to assist in the demoulding operation, the nut being welded to a seal member 46 which is also welded to a further plate 48 of L-section which is welded itself to the movable right-hand upright 31.

The seal member 46 carries a circular section seal 50 and also supports the lowermost edge of a movable, exchangeable, side wall 52 which at its upper edge is received in a notch formed in a trapezoidal section member 54 which is welded to a further L-shaped member 56 having a support purpose inasfar as it is welded to the upper end of the righthand upright 31. The L-shaped member 56 has a reinforcing plate 58 welded to it and to the member 54 and also a reinforcing plate 59 welded to the corresponding upright 31.

The exchangeable side wall 52 has apertures arranged in two rows (possibly more) each of which receives a coach bolt 60 and each coach bolt also passes through a vertical strap 61 secured to vertical limbs of the Lsection further plate 48 and to the further Lshaped member 56. The screw-threaded ends of the coach bolts each receive a washer and butterfly nut 62. The heads of the coach bolts protrude into the mould cavity, but since crossing ties do not require a smooth finish the shallow dimples formed by the heads are of no consequence. The interaction of the external plate on the L-section members 62, the trapezoidal section upper member 54 and the lower seal member 46 all ensure complete rigidity and dimensional stability of the exchangeable side wall 52 when ready for casting. The angled surfaces of the members 46 and 54 provide for chamfers in the finished crossing tie.

The side wall 42 will have a plurality of apertures additional to those required for bolts 60 (not shown) spaced along its length and each aperture receives a securing member at a precise location required for the particular article to be cast. Where crossing bearers are to be manufactured, the cross-sectional dimensions will be standard, but even for a given crossing the locations of the securing members will be different for each bearer. The side wall 52 will therefore also be different for each bearer. To avoid producing individual side walls for each crossing a store of these walls will be kept.

As is indicated in Figures 1 and 3, the central upright can serve to co-operate with two fixed side walls and two exchangeable, removable, side wall assemblies.

While the invention has particular applicability to crossing bearer manufacture, it will be appreciated that the invention can readily be applied to other concrete articles which require fixing members distributed over one face of the article. If securing members are required in another face the exchangeable side wall will be duplicated and the fixed side wall eliminated.

The manner of use of the mould assembly is believed clear from the above description of the parts, but will nevertheless be briefly described.

For any given crossing bearer the crosssection will normally be the same, but a side wall 52 is selected which corresponds to the specific spacing requirements for the securing members of the particular bearer. The fixed parts of the assembly illustrated in Figure 1 will then receive the side wall 52 mounted between the seal member 46 and the trapezoidal support member 54. The latter are, of course, rigid with the L-shaped members 48,56 and the uprights 31. The bolts 42 will be withdrawn to prevent interference with seating of members 34 and 40. The coach bolts 60 together with the straps 61 are then mounted, butterfly nuts 62 tightened, the bolts 14 of the stirrup are tightened, the screwed rods 24 located in the spigots 22 and the nuts 26 tightened.

The reinforcing rods (not shown) are then located in the mould assembly, pre-tensioned to the calculated degree and the concrete cast. When sufficiently cured the movable side wall assembly 30 is removed and subsequently the pre-tensioning force released. The bolts 42 are used to break the side wall 52 away from the concrete.

Although the preferred embodiment is intended for use with railway crossing ties, the invention is also applicable wherever a basically standard article is made with variations in the location of securing points.

The exchangeable side wall can be duplicated, a common fixed side wall assembly cooperating with the duplicate wall.

Claims (11)

1. A mould for producing a prestressed concrete article having securing members projecting therefrom at predetermined spacings, said mould comprising a bottom and two side walls, at least one of the side walls having apertures corresponding to the positions of the securing members in the completed article, and means enabling ready interchangeability of the apertured side wall so that alter native side walls can be substituted with different aperture spacings.

2. A mould for producing a prestressed concrete article having securing members projecting therefrom at predetermined spacings, the mould comprising an elongate bottom wall, an elongate side wall fixed relative to the bottom wall, an elongate side wall movable relative to the fixed side wall and having apertures therein corresponding to the locations of the said securing members, a series of upright members supporting the movable side wall, means detachably secured to the upright members and engageable in further apertures of the movable side wall, readily detachable bracing means extending between the upper ends of the upright members and the upper edge of the fixed side wall, and means detachably securing the upright members relative to the elongate bottom wall, the movable, apertured, side wall being also readily removable to enable substitution of a corresponding side wall with a different aperture spacing.

3. A mould according to claim 1 or claim 2 wherein the apertured side wall is supported at its lower end by a seal member which ensures fluid-tightness when the apertured side wall and the bottom wall are in operative relationship.

4. A mould according to any one of claims 1 to 3 wherein means are provided to break the apertured side wall away from a concrete article after the latter has set.

5. A mould according to any one of the preceding claims wherein the bottom wall and the side walls are supported on inverted channel section members extending transversely to the length direction of the side walls.

6. A mould according to any one of the preceding claims wherein the fixed side wall is mounted on a further series of upright members spaced along the length of the mould.

8. A mould according to any one of the preceding claims wherein apertured, movable side wall has at its upper edge an elongate member arranged to define a chamfer in the article to be manufactured.

8. A mould according to any one of claims 2 to 7 wherein the upright members are interconnected by an upright plate.

9. A mould according to anyone of claims 2 to 8 wherein the detachable bracing means comprises a series of rods spanning the side walls and mounted at one end on a respective one of the upright members and at the other end in bifurcated spigots upstanding from the fixed side wall.

10. A mould according to any one of claims 2 to 9 wherein the means detachably secured to the upright members and engageable in the further apertures of the movable side wall are coach bolts.

11. A mould substantially as hereinbefore described with reference to the accompanying drawings.