IE910187A1

IE910187A1 - Installation conduit and apparatus for the manufacture¹thereof

Info

Publication number: IE910187A1
Application number: IE018791A
Authority: IE
Original assignee: Alexander Faller Senior; Manfred Bast; Alexander Faller Junior
Priority date: 1990-01-19
Filing date: 1991-01-21
Publication date: 1991-07-31
Also published as: JPH04505096A; CS12291A2; EP0473732A1; WO1991011045A1; DE9000546U1

Abstract

The invention relates to a conduit for electrical wiring or cable duct for laying lines which can be drawn in by means of a draw-in cord (12). The draw-in cord (12) is longer than the conduit (10), preferably one-third longer, so that it can be firmly gripped and does not recede into the conduit (10) when the latter is cut to a desired length. A device for manufacturing a plastic conduit for electrical wiring (10) comprises an injection head (28) which has a connecting channel (30) for supplying the plasticized raw material and an outlet nozzle (36). A pneumatic transport channel (50) which moves the draw-in cord (12) forward and is connected to a source of compressed air passes through the injection head (28).

Description

The invention relates to a wiring conduit or cable conduit for the laying of cables and supply lines as well as an apparatus for manufacture of a conduit of this kind with previously inserted pull-cord.

Wiring conduits are to a constantly increasing extent being installed under plaster in new buildings in order to subsequently or even at a much later stage allow supply lines to be pulled in appropriately as and when required without need to knock off the plaster for the purpose. The wiring conduit is in such case comprised of flexible plastic or metal and contains a pull-cord with the aid of which electrical lines, aerial cables, telephone lines, compressed- air piping, water hoses or the like can be pulled in. By comparison with steel tapes of limited rigidity of which use also continues to be made, the pull-cord has the advantage that kinks and bends do not impair the operation of pulling in, even over extended lengths of insertion.

Wiring conduits with pull-cord in use to date have the disadvantage that, on cutting off a desired length of the wiring conduit delivered on site in coils, the end of the pull-cord can recede into the wiring conduit, so that at best it is possible only with difficulty to take hold of it IE 91187 and connect it to the cable being inserted. In the process, it is impossible to avoid the other end of the pull-cord being pulled back into the wiring conduit.

To avoid these difficulties, a method is proposed in DE-OS 24 11 156 in accordance with which the wiring conduit is cut open in such way prior to cutting off the length required that the pull-cord is not severed in the process. In this process of cuttinq to lenqth, a piece of the wirinq conduit of about 10 cm in lenqth is first cut out, by which means is obtained a surplus length of the pull- cord which will be required at one end to attach the conductor wires which are to be pulled into the wiring conduit, while the other end is required to allow the pull-cord to be taken hold of by hand. A stopper is attached to an end exhibiting the surplus length, to prevent the pull-cord from being accidentally pulled back inward in the course of laying.

Subject matter of German utility model 79 36 836 is a cable conduit for electrical cable, which internally contains a wire and therefore relatively rigid part which is intended to be of greater length than the cable conduit itself in order that a piece of sufficient length can be pulled out.

The foregoing is achieved in that the wire- type part __ IE 91187 protrudes from the cable conduit at both ends. The run of the wire-type part inside the cable conduit is not described in detail.

The invention is based on the problem of making available a wiring conduit of the specified generic type which can be cut to length without problem on the dealer's premises, in the workshop or on the construction site without need in the process for special precautions in order to prevent receding of the pull-cord into the conduit.

According to the invention, this problem is solved in the wiring conduit conforming to above-mentioned type in that the pull- cord is longer than this accommodating conduit and that this extra length is essentially uniformly distributed inside the conduit. It has proven favourable in this case for the pull- cord to be at least one third longer than the conduit.

The advantage of the invention resides in that, on cutting off a desired length of conduit from a coil supply, it is unnecessary to consider the pull-cord, since the latter is essentially longer than the cable conduit itself, so that subsequent to severing, the end of the pull-cord can in all cases be taken hold of without in the process pulling the IE 91187 other end into the cable conduit. The additional length of the pull-cord exceeding the length of the cable conduit prevents a slight or even a somewhat more forcefull pull at one end from pulling the pull-cord back into the wiring conduit at the other end.

In order that subsequent pulling in of the cable into the cable conduit can be performed with as little friction as possible, it is advantageous if a lubricant easing the pulling in of the cable is applied to the inside surface of the cable conduit. This lubricant can be grease, oil or (in the case of cable conduits composed of oil-sensitive plastics) can be composed of a powder-type lubricant, for example.

It is envisaged in development of the invention that at least one end of the wiring conduit exhibits a clamping component designed to fix the pull-cord in position. With the aid of the clamping component, the two ends of the pull-cord are secured inside the cable conduit, for example during transport to the construction site, in the course of laying operations or prior to the insertion of cables.

It is advantageous in this connection if the clamping element is comprised of an essentially cylindrical sleeve - 5 IE 91187 with a conically extending rim area. A sleeve of this kind can be frictionally inserted in or placed on the open end of the cable conduit, with the end of the pull-cord thereby being gripped between the cable conduit and the sleeve.

The bottom plate at one end of the sleeve prevents the penetration of dirt, humidity or the like into the cable conduit.

In a preferred development, a cylindrical split taper 10 socket is inserted in removable form in the conical rim area of the sleeve. The end of the pull-cord can be fixed in the sleeve with the aid of this split taper socket, so that pulling back of the pull-cord into the wiring conduit is prevented even if the sleeve is not fixed at the end of the wiring conduit. This arrangement also simplifies the locating of any one of several cables, which feature is discussed in further detail below.

The pull-cord can subsequently be pulled into any wiring 20 conduit. It is desirable, however, for the pull-cord to be already incorporated on manufacture of the conduit.

To solve this problem, an apparatus is envisaged as indicated in Claims 8 to 11 and having the advantage that the pull-cord is already inserted during extrusion of the IE 91187 - 6 conduit, without need for extensive modifications to already existing injection moulding dies.

The invention will hereinafter be more particularly 5 described with reference to the accompanying drawings, which show by way of example only, a number of embodiments according to the invention.

In the drawings: o Figure 1 is a diagrammatic partial view of a wiring conduit according to the invention; Figure 2 is an enlarged cutaway diagram of one end of the wiring conduit illustrated in figure 1, after cutting to length; Figure 3 is the cut-off end illustrated in figure 2, with pull-cord attached thereto; Figure 4 is a view of a modified embodiment of the clamping component removed from the end of the wiring conduit; Figure 5 is a view of the clamping component illustrated in figure 4, inserted in the end of the wiring conduit; Figure 6 is a longitudinal section through an apparatus for manufacture of the wiring conduit with integrated pull-cord; IE 91187 Figure 7 is a variant of figure 6; and Figure 8 is a further variant of figure 6.

Figure 1 diagrammatically illustrates a part of a wiring 5 conduit 10 which is composed of flexible plastic and which can be kept on hand on a supplier's premises or on a construction site in the form of a supply coil. The wiring conduit 10 contains a pull-cord 12 the length of which is substantially greater than the length of the wiring conduit . The pull-cord 12 can for instance be inserted by compressed-air into the wiring conduit 10.

Figure 2 illustrates, in enlarged scale, one end of the wiring conduit 10 subsequent to severing at a cutting plane 14. After the wiring conduit 10 has been cut off at this point, the pull-cord 12 can be taken hold of and a piece of it can be pulled out of the wiring conduit 10 as shown in figure 3. Since, because of the extensive length of the pull-cord 12, this operation does not exert any pulling action on the other end of the pull-cord, the other end of the pull-cord 12 is effectively prevented from being pulled into the wiring conduit 10 in the process.

Figure 3 further illustrates that the pulled-out end of the IE 91187 pull-cord 12 can be secured by being gripped by a sleeve 16 which is placed frictionally engaged onto the end of the wiring conduit 10.

In the examples in figures 2 and 3, both the wiring conduit and the sleeve 16 are provided with a corrugated wall. Smooth designs are of. course feasible as well.

The example in figures 4 and 5 illustrate one end of a 10 wiring conduit 10 cut to length, from which a piece of pull-cord 12 has been pulled out. The end of the pull-cord 12 is led through a cylindrical split taper socket 18 which is subsequently inserted in a conically extended rim area 20 of an essentially cylindrical sleeve 26 with bottom plate 22. In the process, the end of the pull-cord 12 is frictionally engaged between the split taper socket 18 and the sleeve 26.

The clamping component 24 designed in accordance with 20 figure 4 is particularly advantageous when several wiring conduits 10 come together from different directions in one wiring box and a workman is required without the assistance of any further person to find a particular wiring conduit 10. The workman can then proceed by providing all pull-cords 12 at the ends of the wiring - 9 IE 91187 conduits 10 coming together in the wiring box with a clamping component 24 and placing these at like distance from the ends of the wiring conduits. Accordingly, he can then pull on the pull-cord 12 at the other end of the desired wiring conduit, which can be far removed from the first end, in order to subsequently discover which of the clamping components 24 has been pulled closer to the first end. Any accidental pulling of the pull-cord 12 into the wiring conduit 10 will be prevented by the clamping component 24.

In figure 5, the clamping component 24 is inserted beforehand with the base plate 22 of the sleeve 26 into the end of the wiring conduit 10, so that the latter is closed off.

Figure 6 illustrates, in longitudinal section, an apparatus according to the invention, which is suitable for manufacture of a wiring conduit 10 with previously integrated pull-cord 12 (Variant A). This apparatus has an extrusion head 28 as known per se with a feed channel 30 designed to feed in the plastified material, for example a thermoplastic plastic such as polyvinylchloride. Inside the extrusion head 28, this material passes over a partition 32 with radial spokes 34 into an outlet nozzle IE 91187 36. The end of the outlet nozzle 36 has placed on it a conduit section 44 which exhibits a first closure plug 46 downstream of the outlet nozzle 36 and a second closure plug 48 at it's end. Between the two closure plugs 46 and 48, the conduit section 44 is provided with radial outlet holes 54.

On one side, the extrusion head 28 is joined in radial direction by a supporting air channel 40, which is connected to a compressed-air supply over a connection 42.

The compressed-air developed is in the order of magnitude of 1 bar. Inside one of the spokes 34, the supporting air channel 40 runs in an arc to subsequently extend concentrically with the outlet nozzle 36. This circular arc shape can be worked by erosion into the partition 32.

The wiring or cable conduit 10 extruded through the outlet nozzle 36 obtains its bellow-type shape within the area between the two closure plugs 46 and 48 by means of continuously rotating moulding dies 38 distributed over the circumference. The compressed-air flowing out of the supporting air channel 40 through the outlet holes 54 presses the still soft material against the appropriately profiled segmental surfaces of the moulding dies 38.

IE 91187 According to the invention, the inside of the supporting air channel 40 is provided with a conveying air channel 50 running concentrically with the former and ending at the second plug closure 48 and downstream of the supporting air channel 40. The conveying air channel 50 is likewise supplied with compressed-air at its inlet 52, in which case the pressure is substantially higher than in the supporting air channel 40, for example 10 bar.

The pull-cord 12 is led from a coil 56, the speed of rotation of which is adjustable, into the conveying air channel 50, in which, under the assistance of the conveying air, it reaches the end downstream of the closure plug 48. Since at this point the compressed-air flowing out of the conveying air channel 50 flows at slower speed up to the end of the already finished conduit 10, the pull-cord 12 is laid in approximately helical line along the internal wall of the more slowly moved conduit 10, so as to produce, inside this conduit, the desired, uniformly distributed extra length of pull-cord 12.

The conveying air channel 50 can easily be dismantled within the supporting air channel 40 and replaced by another in order to adapt it to the particular material being used for the pull-cord 12. Depending on desired - 12 IE 91187 characteristics (resistance to breaking, tensile force or the like), the latter can be comprised of hemp, plastic, metal or other materials.

Figure 7 illustrates a variant of the extrusion head 28 without supporting air channel (Variant B). In this case, compressed-air is not injected to produce the bellow-type shape of conduit 10, but the moulding dies 38 are provided with vacuum holes 58 some of which are indicated and 10 through which the extruded material is pulled into the profiled grooves on the inner side of the moulding dies 38.

As the extrusion head in figure 8 shows, it is sufficient for the supporting air tc act simultaneously as conveying air in the manufacture of very thin conduits 10 in accordance with Variant A or B. Corresponding to the example in figure 7, only one channel 50 is provided in this case, into which the conveying air at about 10 bar is introduced to emerge downstream of the plug closure 48 into 2° the conduit 10. The corrugation can be produced by overpressure or vacuum. The channel 50 can further pass in axial direction through the extrusion head 28, while the feed channel 30 through which the material is supplied can join the extrusion head from the side. Inside the extrusion head 28, the channel 50 is protected against - 13 IE 91187 overheating by an annular space 60 filled with air.

It is of course feasible as well to manufacture conduits 10 with smooth outer wall. In this case, the moulding dies 38 can be replaced with smooth evener rollers.

Claims

1. An installation or cable conduit for the laying of cables or supply lines, comprising an accommodating conduit 5 and a pull-cord for pulling in a cable or supply line, wherein the pull-cord is longer than the accommodating conduit and the extra length of the pull-cord is distributed uniformly inside the conduit. 10

2. A conduit as claimed in Claim 1, characterised in that the length of the pull-cord corresponds to approximately twice the length of the wiring conduit.

3. A conduit as claimed in Claim 2, characterised in that 15 the pull-cord is at least one third longer than the conduit.

4. A conduit as claimed in any of Claims 1 to 3, characterised in that a lubricant easing the pulling in of the cable is applied to the inside wall of the wiring 20 conduit.

5. A conduit as claimed in any of the preceding Claims, characterised in that at least one end of the wiring conduit embodies a clamping component designed to fix the pull-cord. IE 91187

6. A conduit as claimed in Claim 5, characterised in that the clamping component is comprised of an essentially cylindrical sleeve with a conically extending rim area. 5

7. A conduit as claimed in Claim 6, characterised in that a cylindrical split taper socket is inserted in removable manner into the conical rim area.

8. An apparatus for the manufacture of a conduit according 10 to any of the preceding Claims which is made of plastic, the apparatus comprising an extrusion head which exhibits a feed channel for supplying of the plasticized material and an outlet nozzle, characterised in that the extrusion head has incorporated in it a conveying air channel designed to 15 advance the pull-cord and connected to a compressed-air supply.

9. An apparatus as claimed in Claim 8, characterised in that the conveying air channel passes inside a supporting 20 air channel formed inside the extrusion head and ends downstream of the latter channel.

10. An apparatus as claimed in Claim 9, characterised in that the conveying air channel acts simultaneously as 25 supporting air channel. - 16 IE 91187

11. . An apparatus as claimed in any of Claims 8 to 10, characterised in that the conveying air channel enters a spoke-shaped partition of the extrusion head from the side in approximately radial direction, passes in an arc inside 5 one of the spokes and subsequently runs in axial direction of the outlet nozzle.

12. An apparatus as claimed in any of Claims 8 to 11, characterised in that the pressure in the conveying air 10 channel is in the order of magnitude of 10 bar.

13. An installation or cable conduit for the laying of cables or supply lines substantially in accordance with any of the embodiments herein described with reference to and as 15 shown in Figures 1 to 5 of the accompanying drawings.

14. Apparatus for manufacture of an installation or cable conduit substantially in accordance with any of the embodiments herein described with reference to and as shown 20 in Figures 6 to 8 of the accompanying drawings.

15. The features described in the foregoing specification, or any obvious equivalent thereof, in any novel selection.