GB2085349A - Process for the production of ducts in structural members - Google Patents

Abstract

A process for producing ducting in structural members such as concrete panels comprises passing flexible rubber tubes (5b) through hollow bodies (4) within formwork members (1), passing a rigid, supporting element (6) e.g. of metal through a part (5k) of the interior of a tube (5b), and then fastening the ends of the elements (6) to the formwork members (1). Then the assembly is concreted and when the concrete has set, the elements (6) and rubber tubes (5b) can be readily removed, to leave ducts in their place. Instead of the elements (6) and rubber tubes (5b) solid rubber rods (not shown) may be used. <IMAGE>

Description

SPECIFICATION Process for the production of ducts mainly in concrete, or reinforced concrete construction units of granular binding material The invention relates to the production of ducts to be formed mainly in concrete, or reinforced concrete construction units of granular binding material.

In the construction with prefabricated panels gaining ever increasing ground in the up-to-date overground construction, the production of ducts for fitting work, primarily for the electrical fitting work represents a special problem both in the prefabricated panels and in the constructional units (fastening elements, corner elements, units at points of junction).

The simplest form of the ducts is grooving to be plastered over after emplacement of the electric wires.

This solution has several drawbacks. It requires double-covered cables, which are more expensive than single-covered cables in the earlier-used internal sleeve pipes. It requires separate plastering, and floating after the fitting work which could be dispensed with in case of internal ducts. One of the advantages of the panel construction is that prefabricated, large wall surfaces can be produced without the need of surface finish requiring plastering and painting; however, in case of fitting into grooves this surface finish will be broken, and is difficult to patch up. Should any failure occur in the cable, the repair is difficult. Once installed, the electric network cannot be expanded.

In the case of the prefabricated panels, emplace- ment of the sleeve pipe into similarly made grooves is out of the question. The increased size of the groove should be followed with the statics of the panel construction, otherwise the afterwork of patching up the groove would remain as a drawback.

For the above reasons the solution of using built-in sleeve pipe is being experimented with. Accordingly, a sleeve pipe - suitably of synthetic material - is placed into the concrete of the panel. This however, is not a simple problem, actually it requires a great deal of meticulous work, and high technological discipline. Even the accurate fastening of the pipe requires special methods, as for instance the two solutions presented in the West German patent specifications Nos 1 815036 and 2 162 156, dealing exclusively with this problem; in addition, in the preparation of the concrete, the connection may break down in the unit at the point of junction, it may slide apart without being noticed immediately - and should this fault be discovered only at the time of fitting - it can no longer be repaired.For this reason this solution is too expensive and it appears to be unreliable.

Ducts without sleeve pipes are also experimented with. Such method is for instance when fabricreinforced rubber hose inflated with compressed air is arranged at the designed locations: the basic material of the panel, i.e. the concrete is produced, then after its setting the air is let out of the rubber hose. Thereafter the hose can be pulled out of the panel. It is evident that specially woven rubber hose with shut-off valves has to be produced in this process, which valves are made in several sizes according to the various dimensional requirements, and separate compressed air should be provided for in the course of production. Fastening of the inflated hose at the designed location is difficult; on compaction of the concrete deformation may easily occur.

Formation of the units at points of junction is not solved. For these reasons this process is difficult, fairly expensive and thus it gained no ground in the practice.

In view of above it is obvious that the mater of ducting in the prefabricated and locally produced concrete or reinforced concrete construction units of granular binding material, used primarily for panels, is far from being reassuringly solved.

Thus the invention is aimed at the realization of a process by which it is possible to produce internal ducts both in prefabricated panels and at points of junction formed during assembly on site - as in constructional units of granular binding material and which can be carried out with simple means at a low cost without the risk of failure in the line of the duct, into which single-covered electric wire can be inserted, in case of fault the wire is easily repaired, replaced and within the limits of possibilities given by the built ducts, the network can be easily expanded.

The invention is based on the recognition that, for instance, flexible rubber hose of suitable wall thickness and internal support is suitable for fulfilling the role of formwork, which after usage following the removal of the internal support elongates as a result of the pulling force, its cross-section contracts and thus it can be pulled out of the solidified basic material. The wall thickness of the rubber hose is to be such as to ensure a certain degree of retentivity by itself, yet this wall thickness generally does not exceed 4 mm. The rubber material of the hose well withstands the effect of the aggressive material possibly present in the concrete, it endures the arising max. 70-80"C temperature.

Accordingly the substance of the process according to the invention is that the flexible, preferably rubber, moulding tube - the outside diameter of which fits the diameter of the required duct and the inside diameter corresponds to about 2/3 - 4/5the of the outside diameter - is coated with an antiadhesion liquid, e.g. oil, then it is arranged according to the required traceline between the already emplaced boxes, and afterwards or previously a rigid, cylindrical support (hereafter: propping) linear element the diameter of which is smaller by 1-2 mm, than the outside diameter of the casing pipe - is placed into the moulding tube along its full length, thereafter the basic material of the constructional unit is produced - generally by the pouring and compaction of the concrete - then after the retentive setting of the basic material first the propping linear element, then the casing pipe itself are pulled out of the basic material.

In case of prefabricated flat constructional units (panel wall and ceiling), rod, or tube, suitabley metal e.g. steel rod or tube is used as propping linear element. In this case the duct divided into two sections by a hollow body or box along each straight line, can be produced by using moulding tube and propping linear element placed in, or pulled out in two directions from the outside.

Our experiments demonstrated that the propping linear element in the inner section of the moulding tube can be effectively substituted by stretching the moulding tube. According to one of the recommended implementation methods the propping linear element is placed into the moulding tube only at the two extreme sections of the casing pipe, suitably reaching into at the edge of the model frame, otherwise reaching over it in every case, here the casing pipe is pulled with a gripping tool and fixed in a stretched condition, then the constructional unit is produced, and after setting of the basic material, the tension is released and the casing pipe is pulled out of the basic material.In this case the transverse ducts in the flat constructional units are formed with a straight by-pass traceline (contour), and their projection intersecting point with deeper boxes connecting the transverse ducts.

This stretching process can be successfully used even when the propping linear element is formed from rubber, united with the casing pipe, i.e. a solid rubber rod used in place ofthe casing pipe and the propping linear element.

No matter which process is used for formation of the ducts in the flat constructional units, in the course of building in the ducts into the contructional units at the points of junction (corner element, etc.) they are formed in such a way that the coil spring or other similar axially flexible, suitably metal, e.g.

steel, supporting element is used as propping linear element, while the casing pipe and propping linear element are so arranged at the point of junction as to extend into the open space through the box of two adjacent panels, and the extending parts are connected for the time of producing the basic material, and then the casing pipe and propping linear element are pulled out through one of the boxes.

The box itself is suitably formed for the process as to have the necessary openings toward the ducts with outwardly rounded necks, in order to carry out the guiding ofthe casing pipe and propping linear element, as well as the fitting elements (wire) with elbow bends at the lowest possible resistance.

The invention is described in detail by way of examples with reference to the enclosed drawings, in which: Figure lisa diagrammatic arrangement of the panel conforming to the design prepared according to the implementation method of the invention, showing the plan view of the horizontal position; Figure2 is a partial, diagrammatic perspective view of the corner points of same, showing the preparatory elements of the duct to be produced; Figure 3 is a diagrammatic arrangement of the panel according to the design shown in Figure 1, prepared according to the implementation method of the invention showing the plan view in its horizontal position; Figure 4 is a diagrammatic perspective view of the corner points of same, with the preparatory ele mentsoftheductto be produced;; Figure 5 is a diagrammatic perspective view of the finished panels assembled at the point of junction produced as shown either in Figures 1-2 or 3-4, with the implementation method according to the invention, including the preparatory elements; and Figure 6 is a perspective view of a box member.

Figure 1 illustrates the outlines of door 3 between the model (form) sides 1 in the arrangement dccord- ing to the design, which are determined by the sides rising in the form or model. The separately not illustrated protruding discs over which the boxes (hollow elements) 4 are pulled, are fastened at the bottom of the form or model at the location of the boxes according to the design; this way the boxes are fixed without shifting during the concreting work. The frame sides 1 in the line of the boxes are provided with holes 2 and lugs 8 at a short distance from the holes.

After placement of the reinforcing steel into the model or form, the boxes 4 are pulled over the discs, taking care to align the circular cross sectional side-openings of the boxes above each other. The upper boxes 4 are generally used for fastening, while the intermediate and lower boxes are used for arrangement of the fittings (switches, connectors).

This is followed by arrangement of the elements used for the formation of the ducts. Figure 2 gives the clear view of these elements in the vicinity of the form sides The duct 2 formed in the form side is surrounded suitably with casing pipe 9, which may extend from the model side. The moulding tube 5 is oiled e.g. with H2 oil available in the trade. Then the rubber moulding tube 5 is pulled through the casing pipe 9 and through the circular openings of boxes 4, the outside diameter of which in the present case is 25 mm, inside diameter 1 9mm. In the longer direction ofthe panel, the mould pipe 5 is pulled in divided from two sides to box 4', but in a single section in the vertical direction.The propping or supporting linear element 6, a 16 mm steel rod in this example, is pulled into mould pipe 5 extending over the model sides 1.The inner end of the propping linear element 6 approximateiy coincides with the inner end of the moulding pipe 5 where it is bent, and its end is formed in lug 7. Lug 7 and lug 8 fitted into the model side 1 are connected with bracket 10, in order to prevent loosening of the propping linear element 6 and the moulding pipe element 5 during compaction of the concrete.

Now the concreting work is carried out. After the proper setting of the concrete, the bracket 10 is removed, the propping linear element 6 and the moulding pipe 5 are pulled out. Due to the rubber material of the moulding pipe 5, it gradually elongates from the edge inward, its cross-section contracts, it separates from the concrete wall and thus it can be pulled out of the duct. This way production of the duct in the panel is completed.

Figure 3 shows the plan view of the schematic arrangement of the same panel as the one shown in Figure 1, but according to another simple method of the process according to the invention. The difference is that the boxes 4 are deeper, the model or form 1 is provided with holes 2 for formation of the transverse (parallel with the door opening) duct, and at a higher and lower level conforming to the two directions, furthermore the lugs 8 are unnecessary.

Figure 4 assists in understanding the implementation of the duct formation. The propping linear element 6 - e.g. steel tube - is pushed into the linear element 5 only to the length of the outer section 5k, so as to reach further inwardly than the edge of the side 1; the other internal sections Sb remain empty.

Then the moulding tube 5 with the pushed-in propping linear element 6 are pulled on section 5k with a gripping tool 17 and in its stretched condition is fixed, in present case with clamp 18. Nowthe concreting takes place: the rubber moulding tube 5 will be straightened in its stretched condition during vibration and remains in its position, while after setting when the stretching is released and the propping linear element 6 is pulled out through one of its sides, the moulding tube 5 together with the propping linear element 6 or after its removal can be pulled out in the other direction.

Naturally this implementation method requires a suitable flexibility and strength of the rubber. For information it is mentioned that the same rubber hose was used in the experiments of both implementation method with a tensile strength of 10 MPa, hardness of 55Q Shore, and elongation at rupture: 300-350 %. In the implementation method described in connection with Figures 3-4, the tensile strength was between 30-50 N according to the varying length of the duct.

Further possible implementation method of the process according to the invention may be where the ducts are formed with the aid of solid rubber rod passing throughout, using the stretching process described in connection with Figures 3-4. The method of gripping and stretching is the same, the process is easily conceivable without separate illustration.

Formation of the duct on assembly at the points of junction by way of example is shown in Figure 5 and the box used here is illustrated in Figure 6. Setting the panel 11 in its position, the oiled moulding tube 5 is pulled through the upper opening 14 and side opening 15 of boxes 4 and through the finished duct section 50, the propping linear element 12 being placed in suitably in advance, which in this example consists of coil springs. The over-extending ends of the propping linear element 12 are pulled together in the corner space, then connected with hook 13. This is followed with the concreting work, then after proper setting - releasing the connection 13 - first the propping linear element 12, then the moulding tube 5 are pulled out through the end opening 14 of one of the boxes 4, and this way the duct is completed at the points of junction between the two panels 11.

The box 4 itself - as shown in Figure 6 - has side openings 15, which are formed with rounded necks 16.

The box - according to the purpose - can be formed with one or two lines of side openings; in the latter case they are separated from each other with an intermediate partition wall. One line may contain only through side holes at the fittings, or perpendicular branching third or possibly fourth side opening as well (at the fastenings). If the box 4 has superfluous (unused) openings, they should be sealed before concreting.

Claims (8)

1. Process for the production of duct, mainly in concrete or reinforced concrete constructional units of granular binding material, characterized in that a flexible, preferably rubber, moulding tube - the outside diameter of which corresponds to the diameter of the required duct, and the inside diameter corresponds to e.g. 2/3-4/5th of the outside diameter - is coated with anti-adhesive liquid, e.g. oil, then it is arranged according to the required traceline or contour to be formed between already emplaced boxes or hollow bodies, then afterwards or previously a rigid, cylindrical propping or supporting linear element - the diameter of which is smaller by e.g. 1-2 mm than the inside diameter of the moulding tube is placed into the moulding tube along its full length, which is followed by production of the constructional unit, generally the arrangement and compaction of the concrete, then after setting of the basic material, first the propping linear element is pulled out of the moulding tube, and finally the moulding tube itself is pulled out of the basic material.

2. A process is claimed in claim 1, characterized in that a rod or tube, suitably of metal, e.g. steel rod or tube, is used as the propping linear element in flat constructional units.

3. A process as claimed in claim 1 or 2, characterized in that the duct is produced with the use of a propping linear element and moulding tube placed in, or pulled out in two directions in two sections divided by a box or hollow body along each straight line.

4. A process as claimed in claim 1 or 2, characterized in that the propping linear element in the flat construction units along the inner section of the moulding tube is substituted by stretching the moulding tube, accordingly the propping linear element is placed into the moulding tube only at the two extreme sections of the moulding tube, suitably reaching into the model frame, otherwise extending over the frame, where the moulding tube is pulled with a gripping tool and fixed in its stretched condition, then the constructional unit is produced, then setting of the basic material is followed by releasing the stretched condition and the moulding tube is pulled out of the basic material.

5. A process as claimed in claim 4, characterized in that the transverse ducts in the flat constructional units are formed with straight by-pass traceline, and their projection intersection point is formed with deeper boxes or hollow bodies connecting the transverse ducts.

6. A process as claimed in any of claims 1-5, characterized in that a coil spring or other similar cylindrical, axially flexible, suitably metal, e.g. steel, propping element is used as propping linear element during assembly of the flat constructional units at the points of junction (corner elements, etc.), while the moulding tube and propping linear element are arranged in the point ofjunction in such a way as to extend into the open space through the box or hollow body of the two adjacent panels, the extending ends of the linear element are suitably connected for the time of producing the point of junction, thereafter the propping linear element and the moulding tube are pulled out through one of the said boxes or bodies.

7. A process for producing ducting in structural members substantially as herein described with reference to and as shown in Figures 1 and 2, or Figures 3 and 4, or Figures 5 and 6 of the accompanying drawings.

8. Structural members with ducting therein, whenever produced by a process as claimed in any of claims 1 to 7.