IE84516B1 - A precast reinforced concrete slab - Google Patents

Abstract

ABSTRACT A process for manufacturing pre—cas:gconcrete floor slabs includes shaping a number of steel bars at a shaping station. A number of spaced—apart loops are formed in the bars by pressing the bars downwardly between spaced—apart cylindrical formers at the shaping station. A pair of the shaped bars are mounted in a slab—forming mould, at opposite sides of the mould, together with a steel reinforcing frame. The mould is then filled with concrete, leaving the loops of the bars projecting upwardly of the top surface of the concrete. After setting the concrete to form the pre—cast concrete slab, the slab is removed from the mould.

Description

A pre-cast reinforced concrete slab This invention relates to a process and apparatus for manufacturing a pre-cast reinforced concrete slab, and in particular slabs used in the construction of floors in buildings.

According to the invention there is provided a process for manufacturing a pre-cast reinforced concrete slab, comprising the steps: forming a plurality of shaped tie bars by delivering elongate steel bars to a shaping station, at the shaping station laying the steel bars side by side on a shaping bed, the bars extending across a plurality of space-apart formers which are seated on top of the bed, securing the bars on the formers, delivering a press beam on a carriage incrementally along the bed between a number of bending positions, at each bending position positioning the press beam between an adjacent pair of formers and stopping the carriage, extending the press beam downwardly to press the bars downwardly together between the formers and then retracting the press beam, shaping a number of spaced-apart loops in the bars in this manner for forming the shaped tie bars, delivering the tie bars to a moulding station, at the moulding station mounting a pair of the tie bars in a slab forming mould, locating the tie bars adjacent opposite sides of the mould, '° 84516 inserting a steel reinforcing frame into the mould with a top of each tie bar projecting above the reinforcing frame, pouring a quantity of liquid concrete into the mould, covering the steel reinforcing frame with the concrete and leaving an uppermost portion of each tie bar projecting upwardly from a top surface of the concrete in the mould, setting the concrete in the mould to form the reinforced concrete slab, and removing the reinforced concrete slab from the mould. in a preferred embodiment of the invention the process includes clamping the bars at each bending position by extending a clamp beam which is mounted on the carriage to engage and clamp the bars against the bed before extending the press beam downwardly for shaping the bars.

In another embodiment the clamp beam is extended downwardly for engagement with the bars within previously formed looped portions of the bars.

In a further embodiment the process includes securing the bars on the formers by laying a cross bar across the bars at each former and fastening the cross bar to the former for clamping the bars between the cross bar and the former.

In a preferred embodiment the formers are cylindrical in shape, the formers being mounted on the bed in a parallel spaced-apart relationship.

The invention will be more clearly understood by the following description of some embodiments thereof, given by way of example only with reference to the accompanying drawings, in which; Fig. 1 is a perspective view of a pre-cast reinforced concrete slab manufactured according to the process of the invention; Fig. 2 is an elevation view of a shaping station used in the process; Fig. 3 is an end elevational view of the shaping station; Fig. 4 is a detail perspective view showing portion of the shaping station; Fig. 5 is a schematic elevational view illustrating operation of the shaping station; and Fig. 6 is an elevational view of a shaped tie bar formed during the process at the shaping station.

Referring initially to Fig. 1 there is shown a pre-cast reinforced concrete slab manufactured according to the process of the invention indicated generally by the reference numeral 1. The slab 1 has a reinforced concrete body 2 of generally rectangular shape. it will be noted that roughly midway along a top face 3 of the slab 1 at opposite sides of the slab 1 a number of spaced-apart steel loops 4 project upwardly above top face 3 of the slab 1. These are for the reception of and engagement with tie rods which extend between loops 4 on adjacent slabs 1 which are laidside by side in a building to construct a floor prior to covering the slabs 1 with a further layer of concrete to provide a uniform floor surface.

A process for manufacturing the slab 1 will now be described. Shaped tie bars 10 (Fig. 6) are formed by delivering elongate steel bars to a shaping station 12. The shaping station 12 has a ground engaging frame 13 formed by a pair of spaced-apart elongate I-beams 14 interconnected by a number of box section cross beams 15. A shaping bed 16 is supported on the frame 13 and comprises a bed plate 17 mounted between upper flanges 18 of the I-beams 14. A number of spaced-apart cylindrical formers :20 are mounted spaced-apart on the bed plate 17 in a parallel relationship.

Locking bolts 22 project upwardly at each end of each former 20 for engagement by a complementary cross bar 23 which can be extended between the locking bolts 22 and secured thereto by lock nuts 24. Rails 25 extend along an outer edge of each upper flange 18 of the I-beams 14. A carriage 30 is moveable along the rails 25 between opposite ends of the shaping bed 16. Rollers 31 on the carriage 30 engage the rails 25 for rolling the carriage 30 along the shaping bed 16.

A press ram 34 is mounted on the carriage 30 and comprises a box section press beam 35 mounted by a pair of spaced-apart rams 36 on the carriage 30 above the shaping bed 16. The rams 36 are operable to raise and lower the press beam 35.

Mounted on the carriage 30 behind the press beam 35 is a clamp beam 38 which is also of box section and is secured on the carriage 30 by means of a pair of rams 39 which are operable to raise and lower the clamp beam 38 on the carriage 30. All the rams 38, 39 are connected to a hydraulic power supply for operation of the rams 36, 39.

To form the shaped tie bars 10 a number of elongate steel bars 50 are laid side by side on the shaping bed 16. lying across the formers 20 as shown in Figs. 4 and 5.

The bars 50 are secured to each former 20 by laying a cross bar 23 over the bars 50 in engagement with the locking bolts 22 and securing the cross bars 23 to each former 20 by means of the lock nuts 24. This prevents any vertical movement of the bars 50 but will allow longitudinal movement if required to accommodate bending as described later. The carriage 30 is advanced to position the press beam 35 between a first pair of formers 20 on the shaping bed 16 and the rams 36 operated to extend the press beam 35 downwardly thus pressing the bars 50 downwardly between the formers 20 forming a loop in the bars 50. The press beam 35 is then retracted and the carriage 30 is moved along the rails 25 to position the press beam 35 above the next pair of formers 20. Before lowering the press beam 35 the clamp beam 38 is lowered by the rams 39 into the previously formed loop 51 to securely clamp the bars 50 against the bed 17. Then the rams 36 are extended to move the press beam 35 downwardly to form the next loop 51 in the bars 50 as shown in Fig. 5. The carriage is moved incrementally along the bed 16 in this fashion forming a new loop 51 in the bars 50 between each pair of formers 20. When the carriage 30 reaches the end of the bed 16 it is returned to the start position and the shaped tie bars 10 with the loops 51 are then removed from the shaping station 12 and delivered to a moulding station.

At the moulding station a pair of the tie bars 10 are mounted in a slab forming mould, the tie bars 10 being located at opposite sides of the mould. A steel reinforcing frame is also inserted into the mould with a semi-circular loop 4 at atop of each tie bar 10 projecting above the reinforcing frame. A quantity of liquid concrete is poured into the mould covering the steel reinforcing frame but leaving an uppermost portion of each loop 4 of the tie bar 10 projecting upwardly from the top surface of the concrete in the mould (thus leaving the exposed loops 4 shown in Hg. 1). The concrete is allowed to set in the mould to form the reinforced concrete slab 1 and then the reinforced concrete slab 1 is removed from the mould.

The invention is not limited to the embodiments hereinbefore described which may be varied in both construction and detail within the scope of the appended claims.

Claims (1)

1. A process for manufacturing a pre-cast reinforced concrete slab, comprising the steps: forming a plurality of shaped tie bars by delivering elongate steel bars to a shaping station, laying the steel bars side by side on a shaping bed, the bars extending across a plurality of spaced-apart formers which are seated on top of the bed, securing the bars on the fonners, delivering a press beam on a carriage incrementally along the bed between a number of bending positions, at each bending position positioning the press beam between an adjacent pair of fomrers and stopping the carriage, extending the press beam downwardly to press the bars downwardly between the fonners and then retracting the press beam, shaping a number of spaced-apart loops in the bars in this manner for forrnhg the shaped tie bars, delivering the tie bars to a moulding station, atthe moulding station mounting a pairofthetie bars in a slab forming mould, locating the tie bars adjacent opposite sides of the mould, inserting a steel reinforcing frame into the mould with a top of each tie bar projecting above the reinforcing frame, pouring a quantity of liquid concrete into the mould covering the steel reinforcing frame with the concrete and leaving an uppermost portion of each fie bar projecting upwardly from a top surface of the concrete in the mould, setting the concrete in the mould to form the reinforced concrete slab, and removing the reinforced concrete slab from the mould. A process as claimed in claim 1 induding the step of clamping the bars at each bending position by extending a clamp beam which is mounted on the carriage to engage and clamp the bars against the bed before extending the press beam downwardly for shaping the bars. A process as claimed in claim 1 or claim 2 including extending the clamp beam downwardly for engagement with the bars within previously fonned looped portions of the bars. A process as claimed in any preceding claim including securing the bars on the fomters by laying a cross bar on the bars at each former and fastening the cross bar to the fcmier for clamping the bars between the cross bar and the former. A process as claimed in any preceding claim wherein the fomwers are cylindrical in shape, the fonners being mounted on the bed in a parallel spaced-apart relationship. A process for manufacturing a pre-cast reinforced concrete slab substantially as hereinbefore described with reference to the accompanying drawings. A pie-cast reinforced concrete slab whenever produced by the process as ceimed in any preceding claim.