EP0579809B1 - Process and device for manufacturing precast elements made of prestressed concrete with immediate tensioning, in particular prestressed concrete sleepers - Google Patents

Abstract

PCT No. PCT/EP93/00289 Sec. 371 Date Dec. 23, 1993 Sec. 102(e) Date Dec. 23, 1993 PCT Filed Feb. 8, 1993 PCT Pub. No. WO93/15889 PCT Pub. Date Aug. 19, 1993.A method for the manufacture of pretensioned prestressed concrete sleepers wherein, the tensioning wires are taken directly from one or more rolls of wire and are introduced in a longitudinal feed into a tensioning frame, and the tensioning wires (5) are initially anchored at the end thereof located at the front in feed direction. The wires are tensioned by a tensioning device arranged outside of the tensioning frame and resting against the opposite end thereof, and the wires (5) are anchored at the tensioning device; only then are the wires severed by means of a severing device. In this manner, it is possible to combine in a single station the operating stages of cutting to length, introducing and tensioning the wires, which stages in the past were distributed over several manufacturing stations, so that the labor intensive and time consuming manipulation of wires which have been previously cut to length is eliminated.

Description

The invention relates to a device for producing prefabricated components from prestressed concrete with an immediate bond, in particular prestressed concrete sleepers, according to the preamble of patent claim 1.

Prestressed concrete sleepers are pronounced mass-produced articles, in which everything is important, at least while preserving, but if possible, while improving the quality, saving manufacturing costs. This can be done either by saving material for the sleepers themselves or by saving manufacturing costs, either in terms of the equipment to be kept available for production or in terms of the working time to be used.

The saving of material for the sleeper itself is in the foreground with a known prestressed concrete sleeper, in which the reinforcement of the monolithic sleeper body consists of individual tensioning elements in the form of steel bars, wires or strands that cross each other in the middle of the sleeper in a vertical plane and from there radiate straight to the threshold ends (DE-A-38 32 504). Through the use of individual straight tensioning elements and their radiation-like propagation starting from the middle of the sleeper, even with wide sleeper ends and a slim middle section, even distribution of the end anchorages over the cross-sectional areas of the sleeper ends and good penetration of the sleeper body with prestressing steel can be achieved with this known sleeper; a high prestressing force can thus be achieved without the need for a slack additional reinforcement. These measures, together with the lower bending moments in the slim sleeper middle section, lead to a considerable reduction in the steel requirement for a prestressed concrete sleeper.

This known prestressed concrete sleeper can be produced both with prestressing against the hardened concrete and subsequent bonding, as well as in the prestressing bed, i.e. with an immediate bond. When producing the sleepers in the prestressed bed, in which the individual tension wires are anchored at their ends by means of an adhesive bond, for example, the costs for the anchoring parts of the individual prestressing elements that have to be tensioned against the hardened concrete in the case of prestressed concrete sleepers with a subsequent connection can be avoided.

Prestressed concrete sleepers with an immediate bond are usually manufactured in a long prestressed bed. When producing prestressed concrete sleepers in a long prestressed bed, the tension wires are first laid out, tensioned against fixed end abutments and concreted in in the tensioned state. Depending on the length of the fitted bed or sleeper, a large number of formwork forms are required, which are to be arranged on the fitted bed. The tension wires are only released from their anchors or cut between the individual sleepers after the hardening of the sleeper bodies, whereby the tension force entered as tensile force in the tension wires is transmitted to the sleepers as pretensioning force.

Instead of guiding the tensioning wires over the entire length of a tensioning bed and anchoring them only at the ends of the tensioning bed, it is also known to tension the tensioning wires, which each comprise one or more sleepers next to or behind one another, against so-called tensioning frames made of steel and concreting them in this state; For this purpose, appropriately designed forms of formwork must be combined with the clamping frame (DE-C-39 31 201). Because the tension force of the tension wires here compared to the tension frame This has the advantage that the formwork can be recovered at a relatively early point in time by means of immediate demolding, while the prestressing forces only need to be transferred to the individual sleepers after they have completely hardened.

In this known method, the tensioning wires are first cut to length, then inserted into the tensioning frame and tensioned relative to the tensioning frame by means of a tensioning device integrated in the tensioning frame. These work steps must necessarily take place at different workstations, which involves a comparatively large amount of work.

In order to rationalize the introduction of the reinforcement in the manufacture of prefabricated components made of slack-reinforced reinforced concrete, it is known to arrange unwinding devices for the reinforcement wires wound on rings in front of a concrete form and to lay them out on the concrete form after unwinding (DE-A-35 43 369). For this purpose, the wires are pulled longitudinally over the concrete form using a pulling carriage. Means are also provided for fixing the reinforcement wires to the ends of the concrete form and for separating the wires. Since the wires do not have to be tensioned as required for the production of prestressed concrete, the use of drive rollers is sufficient to exert sufficient tension for straightening and the use of simple clamping devices for fixing the wires.

Against this background, the invention is based on the object in the manufacture of prestressed concrete sleepers with an immediate bond using a stenter economic way of working, especially to improve the processes of inserting the tensioning wires into the tensioning frame and the tensioning process itself, above all to simplify and accelerate it.

According to the invention, this object is achieved by the features specified in the characterizing part of patent claim 1.

Advantageous further developments result from the subclaims.

The basic idea of the invention is that the tensioning wires, which run directly from one or more wire rolls, are introduced into the tensioning frame by means of a wire guide device that can be brought into the plane of the tensioning frame. This makes it possible to bring the individual tensioning wires into the intended position in the tensioning frame in free feed, which is particularly important in the case of tensioning wires which do not run parallel in the respective prefabricated components but, as described at the beginning, cross each other.

The wire guide device is expediently equipped with a number of guide channels for one tension wire each; it allows a simultaneous guided and thus orderly and sag-free insertion of all wires, both with parallel as well as with crossing wires for prestressed concrete sleepers. This not only eliminates the need to arrange the tensioning wires after pulling them in; since the tension wires have no or at least all the same sag, the pretension can be applied simultaneously and in one go.

Due to the direct attack of the tensioning device on the tensioning wires, the previously required displaceable wire anchorings on the tensioning side of each tensioning frame can be omitted; they are replaced by a simple fixed anchor. This also results in lower acquisition costs. The use of known clamping anchors for the tensioning wires both in relation to the tensioning frame and in relation to the tensioning device is particularly expedient and in turn saves time.

Fig. 1

schematisch die Ausbildung einer Spannbetonschwelle mit teils parallel zueinander, teils gekreuzt verlaufenden Spanndrähten,

Fig. 2

eine Seitenansicht der Spannbetonschwelle,

Fig. 3

eine Stirnansicht der Spannbetonschwelle in Richtung III-III und

Fig. 4

einen Querschnitt entlang der Linie IV-IV in Fig. 1,

Fig. 5

in schematischer Darstellung eine Draufsicht und

Fig. 6

eine Seitenansicht einer Einrichtung gemäß der Erfindung,

Fig. 7

eine Draufsicht auf eine Drahtführungsvorrichtung in geschlossenem Zustand, die

Fig. 8a und b

Stirnansichten der Drahtführungsvorrichtung entlang der Linie VIII-VIII in Fig. 7 in geschlossenem und geöffnetem Zustand, die

Fig. 9a und b

Querschnitte durch die Drahtführungsvorrichtung entlang der Linie IX-IX in Fig. 7 in geschlossenem und geöffnetem Zustand und

Fig. 10

eine Seitenansicht eines beweglichen Außenteils der Drahtführungsvorrichtung entlang der Linie X-X in Fig. 7.

The invention is explained below with reference to the drawing. It shows

Fig. 1

schematically the formation of a prestressed concrete sleeper with tension wires running partly parallel to one another and partly crossed,

Fig. 2

a side view of the prestressed concrete sleeper,

Fig. 3

an end view of the prestressed concrete threshold in the direction III-III and

Fig. 4

2 shows a cross section along the line IV-IV in FIG. 1,

Fig. 5

a schematic representation of a top view and

Fig. 6

a side view of a device according to the invention,

Fig. 7

a plan view of a wire guide device in the closed state, the

8a and b

End views of the wire guide device along the line VIII-VIII in Fig. 7 in the closed and open state, the

9a and b

Cross sections through the wire guide device along the line IX-IX in Fig. 7 in the closed and open state and

Fig. 10

a side view of a movable outer part of the wire guide device along the line XX in Fig. 7th

1 to 4 each show a schematic representation of an embodiment for the design of the sleeper body 1 of a prestressed concrete sleeper with an immediate bond and the guidance of the prestressing reinforcement as it can be positioned and tensioned by means of a device according to the invention. In the exemplary embodiment shown, the sleeper body 1 consists of two comparatively wide lateral support bodies 2 and 3, which carry the rail fastening (not shown for the sake of clarity) and a central part 4 with a comparatively narrow, high cross-section. The prestressing reinforcement consists of eight straight tension wires 5, which are additionally labeled a to h to make their course clear.

The prestressing reinforcement comprises two pairs of tension wires a and b or e and f, which penetrate the sleeper body 1 parallel to its longitudinal axis, and two further pairs of tension wires c and d or g and h, which cross each other in the central axis of the sleeper body 1 . The end anchors of the tensioning wires 5, which are made by adhesive bonding, are evenly distributed at the ends of the threshold over its cross section (FIG. 3); in the central axis of the sleeper body 1, the tension wires 5 are very strongly concentrated in a vertical axis (FIG. 4). In addition to this mixed form with parallel and crossed tension wires, the relatively wide support body 2, 3 with slim Middle part 4 of the sleeper body 1 enables, of course, other embodiments are also conceivable and can be realized with the device according to the invention, for example reinforcements which consist exclusively of parallel tension wires, as well as reinforcements which consist exclusively of tension wires crossing one another in the central axis.

In order to be able to produce a pre-stressed concrete tie with an immediate bond in this way, the pre-tensioning wires 5 must be brought together in advance in a position that results in the desired reinforcement, tensioned in this position and held within a formwork form until the concrete in which the tensioning wires are embedded are inserted, compacted and hardened in the formwork. This is done according to the invention by means of a tenter and by means of a device which is shown schematically in FIGS. 5 and 6.

The device according to the invention comprises a feed path 6 which extends over rows of supports 7 and over which a number of clamping frames can be pushed in the direction of arrow 9, of which only one clamping frame 8 is shown. In the simplest case, a support structure for a stenter frame is sufficient if these are fed in in another way.

In the course of the feed path 6, a station S is formed, at which the tensioning wires 5 can be fed and brought into their positions in the tensioning frame 8. A wire bearing with a number of wire rings 10, which corresponds to the number of individual tension wires from which the respective reinforcement is composed, is assigned to the side of the wire bearing. In Fig. 5 only two wire rings 10 are shown; further wire rings connect to the outside.

The station S is assigned a feed device 11 for the tensioning wires 5, which also has a number of driven roller pairs 12 corresponding to the number of wires, and a tensioning device 13 which is supported in a bridge-like manner with respect to the tensioning frame 8 by means of two tensioning cylinders 14. The feed device 11 and the tensioning device 13 are combined as a unit on a carriage 15, which can be moved by means of rollers 16 in the direction of the axis of symmetry of the reinforcement to be produced, in order to be able to absorb the elongation of the wires occurring during tensioning. The tensioning device 13 is equipped with a clamping device 17 known per se, by means of which the tensioning wires 5 running between the clamping plates can be fixed and released again by a single lifting movement.

The tenter frame 8 consists of a rectangular frame made of two side longitudinal members 18, a front edge cross member 19, a rear edge cross member 20 and a central cross member 21. The stenter frames 8 are expediently formed as a steel structure from rolled sections. 5 and 6 comprises four positions I to IV, in each of which a prestressed concrete sleeper can be produced. Corresponding to these positions, clamping anchors 17, which correspond to those on the tensioning device 13, are arranged in the region of the edge cross members 19 and 20. On the central cross member 21 there are rollers 22 for deflecting the crossed tension wires.

The device according to the invention is operated as follows:
On the feed path 6, a number of clamping frames 8 are guided in the horizontal direction to the wire feed and clamping station S shown in the drawing. Once a 5 has reached the position shown in Fig. 5, the tension wires 5 are advanced by the wire rings 10 by means of the feed device 11 in the direction of arrows 23 and brought into the position required for the respective reinforcement in positions I and II.

The positioning of the individual tensioning wires 5 is served by a wire guide device 24, of which two identical units are arranged one behind the other in the direction of the reinforcement axis. The wire guide devices 24 can be brought into the plane of the clamping frame 8 by a vertical lifting movement or can also be removed from this plane. From this wire guide device 24, which will be explained in more detail with reference to FIGS. 7 to 10, the left unit is raised into the plane of the clamping frame 8 according to FIG. 6, the right unit is shown lowered.

In the lowered position of the wire guide devices 24, a clamping frame 8 can be moved into the station S in a horizontal feed. The two wire guide devices 24 are then raised in the positions I and II of the clamping frame 8. Then the tension wires 5 are inserted and first anchored to the front edge cross member 19 by means of the clamping anchor 17. Then the tensioning wires 5 are tensioned by means of the tensioning device 13 and also anchored by means of the clamping anchor 17 on the rear edge cross member 20. Then the wires 5 are cut by means of a wire cutting device 25 and the clamping anchor 17 on the tensioning device 13 is released. In the next step, the clamping frame 8 is transported in the feed direction (arrow 9) until the positions III and IV in the station S are above the wire guide device 24. Then the tensioning wires 5 are inserted, tensioned and anchored in the same way at these positions.

The tensioning frame 8 provided with tensioning wires in this way is then transported further in the feed direction (arrow 9). It is then brought together with the formwork that is pushed over the tensioned tension wires and into which the concrete can finally be introduced. The formwork can be removed before the concrete has completely hardened by means of immediate demoulding. For the time being, the tentering frames are left in their position with respect to the fresh sleepers until the concrete has completely hardened and the tensioning force can be transferred to the sleeper body by loosening the clamping anchors 17. Thereafter, the tenter 8, if necessary, cleaned and reused via the feed path.

A wire guide device 24 is shown in plan view in FIG. 7 and in further views or sections in FIGS. 8 to 10. The wire guide device 24 is used to position the tensioning wires 5 for reinforcement, as is the case with a prestressed concrete sleeper according to FIGS. 1 to 4. For the explanation of the wire guide device 24, this reinforcement arrangement is chosen only as an example; the wire guide device 24 according to the invention can of course also be used in an analogous manner for other forms of reinforcement.

The wire guide device 24 consists of a number of partly fixed, partly movable components, two of which each form guide channels 30 for a tensioning wire 5 in the closed state shown in FIGS. 7 and 8a and 9a. 7, according to the image of the reinforcement symmetrical to the central axis of the threshold, consists of two fixed triangular inner parts 31 and two fixed, also triangular outer parts 32. Two movable outer parts 33 and two movable inner parts 34 interact with these.

While the fixed parts 31 and 32 have flat smooth side surfaces, the movable parts 33 and 34 have longitudinal grooves in the surfaces facing the fixed parts 31 and 32, respectively, which are closed in cooperation with the flat surfaces of the fixed parts 31 and 32, respectively Form guide channels 30 (Fig. 8a, 9a).

In this closed position, the wire guide device 24 is raised (FIG. 6), so that the tensioning wires 5 can easily be inserted along the guide channels 30 and brought into the shape required for the reinforcement. FIG. 8a shows in the end view along the line VIII-VIII in FIG. 7 the reinforcement guide which approximately corresponds to the end view of the sleeper according to FIG. 3. FIG. 9 shows, in section along the line IX-IX in FIG. 7, an image roughly corresponding to the cross section of FIG. 4.

As can be seen from FIGS. 8b and 9b, after the tension wires 5 have been inserted, the two movable outer parts 33 are moved outwards in the direction of the arrows 35 and the movable inner parts 34 in the direction of the arrows 36. As a result, the reinforcement wires 5 are clear of the guide channels, so that the wire guide device 24 can be lowered in the direction of the arrow 37 before the wires are tensioned and a new operation begins elsewhere.

Fig. 10 still shows the arrangement of the grooves in the inner surface of the movable outer part 33 in a view along the line X-X in Fig. 7. Here, the upper and lower guide channels serve to guide the parallel wires 30a and 30f; the middle guide channels serve to guide the crossing wires 30h and 30g on the left side of the outer part 33 and 30c and 30d on the right side.

Claims (8)

1. An apparatus for producing prefabricated components from pretensioned prestressed concrete, in particular prestressed concrete sleepers, with at least one tensioning frame and anchoring devices disposed thereon for the tensioning wires, and also with a tensioning device for tensioning the tensioning wires, characterised in that a support device for the level support of a tensioning frame (8) for introducing thereinto the tensioning wires (5) wound from one or more rolls of wire (10) is associated with a feed device (11) and a severing device (25) for the tensioning wires (5) connected in series, and also with a tensioning device (13) disposed outside the tensioning frame (8) and bearing against the latter for tensioning the tensioning wires (5), and in that at least one wire-guiding device (24), provided with guide channels (30) for the insertion of the tensioning wires (5), is disposed in the vicinity of the support device, which wire-guiding device (24) by vertical displacement can be guided into a position in the plane of the tensioning frame (8) and out of the this plane, said position making possible the insertion of the tensioning wires (5).
2. An apparatus according to Claim 1, characterised in that the support device is formed as a station (S) in the course of a feed path (6) for the tensioning frame (8) extending in a horizontal plane.
3. An apparatus according to Claim 1 or Claim 2, characterised in that the tensioning device (13) - viewed in the feed direction of the tensioning wires (5) - is disposed forward of the support device.
4. An apparatus according to any one of Claims 1 to 3, characterised in that the tensioning device (13) is mounted displaceably in the feed direction of the tensioning wires (5).
5. An apparatus according to any one of Claims 1 to 4, characterised in that the feed device (11) and the tensioning device (13) are combined to form a unit mounted displaceably in the feed direction of the tensioning wires (5).
6. An apparatus according to any one of Claims 1 to 5, characterised in that the wire-guiding device (24) is disposed below the feed path (6) for the tensioning frame (8).
7. An apparatus according to any one of Claims 1 to 6, characterised in that the wire-guiding device (24) is in the form of a framework with guide channels (30) which are adapted to the respectively predetermined three-dimensional position of the tensioning wires (5) serving as reinforcement and into which the tensioning wires (5) can be inserted at one end, wherein the guide channels (30) can be brought from a closed position allowing guidance of the tensioning wires (5) during feed, by opening along joints extending in longitudinal direction, into an open position allowing removal of the framework from the region of the three-dimensional reinforcement.
8. An apparatus according to Claim 7, characterised in that the guide channels (30) are formed from substantially longitudinally extending grooves in the lateral surfaces of components (33, 34), which for opening and closing the guide channels (30) are displaceable transversely to the longitudinal axis of the reinforcement with respect to fixed components (31, 32) with flat surfaces extending parallel thereto.

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