GB2122129A

GB2122129A - Moulding a concrete article with a recess around an aperture therethrough

Info

Publication number: GB2122129A
Application number: GB08311876A
Authority: GB
Inventors: Brian Edgar Levey; Patrick Edwin Wade
Original assignee: Humes Ltd
Current assignee: Humes Ltd
Priority date: 1982-05-03
Filing date: 1983-04-29
Publication date: 1984-01-11
Also published as: AU542448B2; SE8302472L; SE8302472D0; GB8311876D0; AU1400783A

Abstract

A concrete railway sleeper is moulded by casting, to incorporate a transversely extending lining tube (19) at each end, for containing anchor pins for spring clips which secure the rail to the sleeper. A recess (24%) is moulded into the concrete, around the tube (19) ends, by a grommet (25) of resiliently deformable (rubber) material having a shank (26) which is received within the tube end, and a head (28) which protrudes from the tube end to define the recess and is resiliently deformable into sealing engagement with the tapered wall (38) of the sleeper casting mould. The grommet (25) and tube (19) are retained in the mould during moulding, by a positioning rod (36) which passes through the bore (27) of a steel grommet lens (34). The grommet (25) bears on the mould wall, at a steel caster (33), and the grommet shank (26) is externally tapered, and has axially extending ribs which locate against the tube (19). <IMAGE>

Description

SPECIFICATION Forming concrete articles Technical Field This invention relates to forming concrete articles, and more particularly to forming concrete articles having apertures extending therethrough.

The invention has been primarily developed for use in relation to forming concrete sleepers having apertures extending laterally therethrough, which apertures are lined with a steel tube and which receive a pin for a rail fastening system, and the remainder of this specification will be directed primarily to such an application of the invention.

However, the concept of the invention is applicable to forming other types of concrete articles which are to have apertures therethrough, and is not iimited to the application to concrete sleepers.

Background Art It is known in the art of rail fastening systems to provide a system of fastening rails to sleepers which involves providing an aperture through the sleeper in that portion thereof beneath the rail to be fastened thereto and extending parallel to the rail. An anchor pin is placed through the aperture and a spring clip is provided which engages beneath the anchor pin and bears tightly against the upper surfaces of the rail foot on either side of the rail to fasten the rail to the sleeper via the anchor pin.The spring clip basically comprises a length of spring steel bent to provide, a central portion which engages on the surface of the rail foot on one side of the rail; side portions which are bent upwardly and away from the rail foot and thereafter downwardly and around the exposed ends of the anchor pin which protrude from the aperture on either side of the sleeper and thereafter upwardly around the opposite side edge of the rail foot to terminate in end portions which bear against the other surface of the rail foot on the opposite side of the rail. In order to strengthen the wall of the aperture through the concrete sleeper during the moulding thereof.The fastening system is normally completed by a base plate positioned within a laterally extending recess in the sleeper and such as to be interposed between the rail foot and the sleeper and having a recess formed therein for receiving the rail foot and in which a layer of insulating material is applied to insulate the rail from the base plate. A major proportion of the length of the anchor pin which will be in contact with the steel lining tube within the aperture is covered with a layer of plastic or other suitable insulating material to electrically insulate the anchor pin from the steel lining tube.

Such a known form of fastening system is marketed under the name FIST-BTR by BTR Rail Fasteners (Australia) Pty. Ltd. of Welshpool, Western Australia.

As in modern track systems electrical signals for signalling systems are transmitted through the rails it is necessary to electrically insulate therail from the sleeper and thus the reason for the insulated base plate and anchor pin in the fastening system described above. It is however further necessary to ensure that no electrical leakage occurs between the elements of the fastening system and the steel lining tube within the aperture, and as such minimum dimensions have been specified between the various elements of the fastening system and the ends of the steel lining tube on either side of the sleeper.These minimum dimensions are normally achieved by providing recesses in the side walls of the sleeper around the openings for the aperture therethrough at the points where the ends of the steel lining tube are exposed, and these recesses are formed in the sleeper wall at the time of moulding of the sleeper. Insofar as the side walls of the sleeper conventionally diverge downwardly it is known to preposition elements of plastic material on the ends of the steel lining tubes to produce the required recesses in the opposed side faces of the sleeper during its moulding, and which elements because of their shape are known as "ears" and have a vertical dimension less than that of the dimension longitudinally of the sleeper.The side face of the "ear" which in the mould will bear against the inside wall of the mould is inciined relative to the body of the "ear" so as to match the inclination of the mould wall and as such have to be manipulated into the right position prior to the pouring of the concrete, whilst it has also been found that as these elements are relatively rigid in nature the slightest misalignment and any variation to precise surface to surface contact results in seepage of concrete between the surfaces which results in undesirable plugs of solidified concrete.

One attempt at solving this problem which has been attempted by the applicant has involved the positioning of an "0" ring between the "ear" and the lining tube which has complicated the manufacturing process and furthermore did not solve the problem of the requirement to correctly position the "ear".

It has therefore been an object of the present invention to devise a manner of achieving a seal between the recess forming element and the interior mould wall which is not subject to the disadvantages associated with the conventional element discussed above, and the disadvantages associated with the previous attempt to solve the problems and as also discussed above.

Disclosure of the Invention The invention therefore envisages a recess forming element for positioning in the end of a lining tube to be moulded in an aperture through a concrete article during the moulding thereof in a mould, said element being formed from a resiliently deformable material and adapted to be substantially tightly received within the end of the tube and to resiliently deform during positioning within a mould to form a tight seal between said element and the interior wall of the mould.

Preferably the face of the element which is to bear and seal against the interior wall of the mould is lined with a layer of material having good wear characteristics to reduce wear at said face and thus prolong the life of the element during repeated use thereof whilst at the same time assisting in distributing load forces on the element to provide uniform distortion of the element during positioning in the mould.

Preferably the element is provided with an aperture therethrough through which a positioning rod is to be inserted during positioning in the mould, and said aperture incorporates a metal bush or liner.

Preferably the element has ribs or flutes formed on its external surface.

The invention further envisages a method of forming, in a mould, a concrete article having at least one aperture extending therethrough with recesses at least one opening therefrom, said method comprising, placing a lining tube for said aperture, with a recess forming element (as hereinbefore defined) positioned in at least one end thereof, at the desired position within said mould, pouring said concrete, allowing said concrete to solidify, removing said solidified article from said mould and thereafter removing said elements.

One preferred embodiment of the invention will now be described with reference to the accompanying drawings, in which: Brief Description of the Drawings Figure 1 is a perspective view of a rail and sleeper combination incorporating a fastening system of the type to which the concrete article formation of one application of the present invention relates, Figure 2 is a cross-sectional view through the arrangement of Figure 1, Figure 3 is a perspective view of a recess forming element in accordance with one preferred embodiment of the invention, Figure 4 is a longitudinal cross-sectional view of the end portion of a steel lining tube into which the recess forming element in accordance with a preferred embodiment of the present invention has been inserted, Figure 5 is a cross-sectional view similar to that of Figure 4 with the assembly in position within a sleeper mould and bearing against the wall thereof, Figure 6 is a cross-sectional view through the resulting recess configuration in a moulded concrete sleeper, Figure 7 is a cross-sectional view through a test arrangement of a series of wall portions for a simulated parallel arrangement of sleeper moulds as may be utilised in a manufacturing situation and showing a series of aligned lining tube and recess forming element combinations.

Best Mode for Carrying Out the Invention With reference to Figures 1 and 2 of the drawings the rail fastening system for which the present invention has been devised involves providing an aperture 10 through the sleeper 11 in that portion thereof beneath the rail 1 2 to be fastened thereto and extending parallel to the rail.

An anchor pin 13 is placed through the aperture 10 and a spring clip 14 is provided which engages beneath the anchor pin 13 and bears tightly against the upper surfaces of the rail foot 1 5 on either side of the rail to fasten the rail 12 to the sleeper 11 via the anchor pin 13.The spring clip basically comprises a length of spring steel bent to provide; a central portion 1 6 which engages on the surface of the rail foot 1 5 on one side of the rail; side portions 1 7 which are bent upwardly and away from the rail foot and thereafter downwardly and around the exposed ends of the anchor pin 1 3 which protrude from the aperture 10 on either side of the sleeper 11 and thereafter upwardly around the opposite side edge of the rail foot 1 5 to terminate in end portions 1 8 which bear against the other surface of the rail foot 1 5 on the opposite side of the rail. In order to strengthen the wall of the aperture it is lined with a steel tube 1 9 which is cast into the aperture through the concrete sleeper 11 during the moulding thereof.

The fastening system is normally completed by a base plate 21 in the sleeper 11 and such as to be interposed between the rail foot 1 5 and the sleeper 11 and having a recess 22 formed therein for receiving the rail foot 1 5 and in which a layer (not shown) of insulating material is applied to insulate the rail 12 from the base plate 20.As shown in Figure 2, a major proportion of the length of the anchor pin 13 which will be in contact with the steel lining tube 1 9 within the aperture 10 is covered with a layer 23 of plastic or other suitable insulating material to electrically insulate the anchor pin 13 from the steel lining tube 1 9. As stated previously a known form of fastening system of this type is marketed under the name FIST-BTR by BTR Rail Fasteners (Australia) Pty. Ltd. of Welshpool, Western Australia.

As also stated previously it is necessary to ensure that no electrical leakage occurs between the elements of the fastening system and the steel lining tube 1 9 within the aperture 10, and as such minimum dimensions have been specified between the various elements of the fastening system and the ends of the steel lining tube 1 9 on either side of the sleeper 11. These minimum dimensions are normally achieved by providing recesses 24 in the side walls of the sleeper 11 around the openings for the aperture 10 therethrough at the points where the ends of the steel lining tube 1 9 are exposed, and these recesses 24 are formed in the sleeper wall at the time of moulding of the sleeper 1 The recess 24 shown in Figures 1 and 2 is of a known configuration resulting from the use of "ear" shaped elements of plastic material which had been placed on the ends of the steel lining tube 1 9 during the moulding of the sleeper, and to which reference has been made previously, and which are subject to the disadvantages also referred to previously.

Referring to Figures 3 to 5 of the drawings the recess forming element 25 of the present invention, which is to be interpositioned between the end of a lining tube to be moulded in an aperture through a concrete sleeper during the moulding thereof in a mould in accordance with the method of the present invention, is formed from a resiliently deformable material such as rubber and is adapted to be substantially tightly received within the end of the tube 19, which is slightly flared as shown. The recess forming element basically takes the form of a grommet having a first portion 26 to be received within the end of the tube and having a slightly tapered outer surface and a bore 27 therethrough of circular cross-section corresponding to the diameter of the positioning rod to be discussed later.The grommet is completed by a second portion 28 of frustoconical configuration as shown with an intervening step 29 in the outer surface thereof against which the end of the tube 19 abuts. The section of the bore through the second portion 28 has a tapered opening 30 thereto and a portion 31 of circular cross-section and of a diameter greater than that of the bore 27 through the first portion of the grommet, whilst both ends of the bore 27 are also tapered at 32 as shown. All tapered portions 30 and 32 may be in the order of 450 and assist in guiding the tube and grommet combination onto the positioning rod to be referred to later. The grommet may be formed from rubber of a hardeness 45-55 Shore A.

In this preferred embodiment of the invention a steel washer 33 is bonded to the end face of the grommet which is to bear and seal against the interior wall of the mould which not only reduces wear at said face, and thus prolongs the life of the element during repeated use thereof, but also assists in distributing load forces on the grommet to provide uniform distortion thereof during positioning in the sleeper mould.

Furthermore, the bore 27 through the first portion 26 of the grommet incorporates a metal, preferably steel, bush or liner 34. The bush or liner 34 ensures an accurate diameter for the passage which is not affected by climatic changes. The metal bush also provides a lower coefficient friction between it and the positioning rod, to be later described, compared with that between the positioning rod and the types of resiliently deformable materials envisaged for the grommet.

In addition, the integrity of the passage incorporating the metal bush is not affected by distortion of the resiliently deformable material when the grommet is subjected to compressive and sheet forces, whilst the metal bush is more resistant to wear and enables a more accurate final location of the positioning rod.

Furthermore, the outer surface of the first portion 26 of the grommet has formed thereon a plurality of longitudinally extending, parallel, and circumferentially spaced apart, ribs or flutes 35.

The ribs or flutes 35 allow for positive engagement of the grommet within the steel lining tube 1 9 to prevent the grommet from slipping out of position, and to allow for variations in the internal diameter of the tube. The provision of ribs or flutes also allows for easier withdrawal of the grommet after the article has been cast.

Referring to Figure 5 of the drawings there is shown a wall portion 38 of a sleeper mould. In accordance with the preferred method of the present invention a concrete sleeper is formed in a mould represented by the wall portion 38, by firstly positioning reinforcing rods in the mould to extend longitudinally thereof. The lining tube 1 9 for the aperture to be formed, and with the grommets 25 positioned in the ends thereof, is placed at the desired position transversely of said mould.A positioning rod 36 is inserted through aligned apertures in the walls 38 of the mould and the combination of the lining tube 1 9 and the grommets 25 in the ends thereof to accurately position said combination and to draw the end faces of the grommets into tight sealing engagement with interior walls of the mould as the body of the grommet resiliently deforms as shown in Figure 5 to adjust to the inclination of the wall 38. The concrete is then poured, allowed to solidify, the positioning rod 36 is retracted and the solidified sleeper removed from the mould whereafter the grommets 25 can be removed leaving recesses 24' in the opposed wall of the sleeper of a shape conforming to the external shapes of the second portions 28 of the respective grommets (see Figure 6).

In practice the manufacture of relatively large volumes of concrete sleepers is carried out in long lines of moulds divided into individual cavities for each sleeper to be moulded and up to eight such lines may be placed in parallel relationship. A simulation of such an arrangement is shown in Figure 7 and is an indication of the effectiveness of the present invention in such an arrangement.

Figure 7 shows sleeper moulds 37 placed side by side in parallel relationship with aligned holes through the walls of the mould portions and adapted to receive an elongate positioning rod 36 normally having a tapered end for ease of insertion. As shown combinations of steel lining tubes 19 with their grommets 25 positioned in the ends thereof are placed in general alignment with the holes through the mould walls which define the positions where the lined apertures are to be formed in the moulded sleepers. The positioning rod 36 is then pushed through the aligned arrangement with its leading tapered end cooperating with the tapered configurations of the bores through the grommets to accurately draw the combinations into their required positions whilst the respective grommets resiliently deform to force their outer end faces into tight sealing engagement with the interiors of the mould walls.

One additional advantage which the present invention offers over existing sleeper forming techniques is that it lends itself to mechanical, rather than manual, placement of the lining tube and grommet combination within the mould, by utilisation of a mechanical arm programmed or controlled to firstly lower the combinations down between the reinforcing rods (rods 39 in Figure 7) and parallel thereto, and thereafter rotate them through 900 so as to extend transversely of the mould at, or close to, the required position. Such a procedure is not possible in the prior art situation where the "ears" have to be positioned manually tc ensure correct orientation.

Claims

1. A recess forming element for positioning in the end of a lining tube to be moulded in an aperture through a concrete article during the moulding thereof in a mould, said element being formed from a resiliently deformable material and adapted to be substantially tightly received within the end of the tube and to resiliently deform during positioning within a mould to form a tight seal between said element and the interior wall of the mould.

2. A recess forming element as claimed in Claim 1, wherein the face of the element which is to bear and seal against the interior wall of the mould is lined with a layer of material having good wear characteristics.

3. A recess forming element as claimed in Claim 2, wherein the lining is a metal washer which also assists in distributing the load forces on the element to provide uniform distortion of the element during positioning in the mould.

4. A recess forming element as claimed in any one of the preceding claims, wherein the element is formed with an aperture therethrough and through which aperture a positioning rod is to be inserted during positioning in the mould, and said aperture incorporates a metal bush or liner.

5. A recess forming element as claimed in any one of the preceding claims, wherein the element has ribs or flutes formed on its external surface.

6. A method of forming, in a mould, a concrete article having at least one aperture extending therethrough with recesses at at least one opening therefrom, said method comprising, placing a lining tube for said aperture, with a recess forming element, according to any one of the preceding claims, positioned in at least one end thereof, at the desired position within the mould, pouring concrete into the mould, allowing the concrete to solidify, removing said solidified article from said mould and thereafter removing said elements.

7. A method as claimed in Claim 6, wherein, when recesses are to be provided at both openings from said aperture, a recess forming element is positioned in both ends of said lining tube, and a positioning rod is inserted through aligned apertures in the walls of the mould and a passage through the combination of said lining tube and said elements to accurately position said combination, and wherein said positioning rod is retracted before removing the solidified article from the mould.

8. A method as claimed in Claim 6 or 7, wherein a plurality of moulds are provided in side by side relationship with the holes through the walls thereof, and the lining tube and element combinations, in alignment, whereby a single positioning rod may be inserted through all said combinations.

9. A recess forming element, substantially as hereinbefore described with reference to Figures 3 to 7 of the accompanying drawings.

10. A method of forming a concrete sleeper with an aperture therethrough having recesses at the openings therefrom, substantially as hereinbefore described with reference to Figures 3 to 7 of the accompanying drawings.