EP0392336B1 - Arrangement used while erecting concrete shutterings - Google Patents

Abstract

In an arrangement used while erecting concrete shutterings, there are provided spacers (1) which are produced as ready-to-use units in each case from an anchor bar (2) and two supporting parts (3), made of corrosion-resistant material or provided with such a material, at the ends of the anchor bar (2), the supporting parts (3) being firmly connected to the anchor bar (2). The supporting parts (3) possess screw-in threads (7), ending in the manner of blind holes, for tension bars (17). The screw-in threads (7) and the corresponding threads on the tension bars (17) advantageously have a special design with regard to their profile. <IMAGE>

Description

The invention relates to a concrete formwork system according to the preamble of claim 1.

For concrete formwork, it is important, on the one hand, to ensure that the required distance between the formwork walls is maintained. In addition, the formwork walls must be clamped together so that they can withstand the pressure of the filled concrete.

In the case of a method which has been customary for a long time, a correspondingly long tensioning rod is used which runs from one side to the other through the formwork. To secure the distance, a plastic tube is pushed onto the tension rod, on the ends of which cones are placed, which come to rest on the formwork walls. The parts of the relevant tensioning rod that protrude from the formwork on both sides are used to attach those parts, such as shims, clamping nuts, etc., with which the formwork is tensioned. In devices of this principle, which is also referred to as "tensioning", the idea of recovering the tensioning rod when dismantling the formwork after the concrete had set played an important role.

The bracing process has a number of problems. When erecting the formwork, the plastic pipes delivered in longer lengths are cut accordingly on the construction site, the separate cones have to be put on, the spacer made on site has to be pushed onto the tensioning rod and this has to be threaded into the formwork. When removing formwork, the cones have to be removed, the open ends of the plastic pipe have to be closed separately and the remaining conical openings have to be greased with mortar. These are diverse and sometimes very complex work steps.

In addition, cavities in the concrete are always left behind in structures that were built with formwork according to the span principle. This makes it possible for moisture to creep through, allows undesired sound transmission and can also lead to other intolerances or even dangers.

In the case of concrete walls that are subject to higher requirements with regard to impermeability to water, the through-tensioning method with the recovery of tension rods cannot be used because of the remaining voids. Another type of known device must then be used, namely one in which there is a threaded steel spacer or anchor rod which remains in the concrete. The length of this spacer or anchor rod is less than the distance between the formwork walls. Certain conical parts are screwed onto the ends of the anchor rod for abutment against the formwork walls, which consist of a steel inner body with a thread and a rotatable outer body made of plastic with a conical outer surface consist. Tension rods or similar tensioning elements are screwed into the cone parts from the outside, or other parts such as plates, nuts or the like. are assigned to tension the formwork. A device of this type is shown in DE-A-28 53 349.

Problems of various kinds also exist with such devices. Before installation, the cone parts must be screwed onto the ends of the anchor rod and unscrewed again after removal of the formwork. They have to be screwed out of the finished concrete, which is difficult. Standard keys cannot be used to loosen them, but specially made special keys must be used. Before such cone parts are reused because of their value, they often have to be cleaned with corresponding effort. A particular problem also lies in how an undesired or inadmissible twisting or even loosening of the parts screwed together can be reliably prevented. The risk of this is often present to a great extent under the various influences on the construction site when moving from the assembly site to the installation site and when the device is installed, especially when the concrete is shaken. Finally, even with these clamping devices, there is a need to lubricate the relatively large openings remaining after the cone parts have been unscrewed.

From EP-A-00 16 468 it is known to incorporate into the formwork in a building wall to be cast from concrete for technical systems, for example nuclear power plants, fastening elements from a threaded rod and threaded sockets for the later attachment of pipelines or other system parts.

A device for mutually bracing and spacing two formwork walls has also been proposed (DE-B-12 88 779), in which a central anchor part is formed from two parallel pieces of metal wire. Their ends are received by recesses in head pieces, which are made of plastic and have a blind hole between the wire ends for screwing in a clamping screw. Because of its low resilience, such a concept could not find its way into practice.

The requirements for the individual walls or parts of the building are often different in the same construction project. In some of them, the so-called through-clamping method is accepted, whereas otherwise only the other type of the devices explained above can be used. This requires careful planning with appropriate decisions already in the preliminary stage, i.e. before the start of construction. In the work preparation, it must then be taken into account which formwork is used for one component and which formwork is used for the other component. Accordingly, all of the different material for the erection of the different types of formwork must be procured or made available.

The object of the invention is to show a way that takes into account existing difficulties and inadequacies in the construction of concrete formwork, in particular in order to facilitate the operations to be carried out, to simplify these and the preparatory work and to be able to meet accuracy requirements as well as possible. The invention also strives for advantageous designs of the elements used in detail. Other related problems with which the invention is concerned deals, result from the respective explanation of the solution shown.

The invention provides that the support parts are made of cast stainless steel and have blind hole-like screw threads for the clamping elements, the cross-sectional centers of the screw threads for the clamping elements and the internal thread for the ends of the respective anchor rod are on the same longitudinal axis, and that the anchor rods with the Support parts are produced as ready-to-use units with a fixed connection of the support parts to the anchor rod, the end faces of the support parts being at a fixed distance from one another given by the manufacture of the unit and corresponding to the desired spacing of the formwork walls, and wherein the units introduced into the formwork after Setting of the concrete poured into the formwork should be left completely in it.

A number of essential advantages are achieved with the invention. Only one principle is used to achieve dense concrete everywhere. Time-consuming and tedious dispositions for the procurement or storage of different devices and accessories are no longer necessary. Because the unit to be used, consisting of the anchor rod and supporting parts, is already available, there is no longer any need to screw together at the construction site. As a result, errors or inaccuracies can no longer occur, which cannot otherwise be ruled out during this work or when handling the individual parts roughly on the construction site. The prefabricated spacer unit has an exact length. Therefore, an absolute dimensional accuracy of the walls or other construction parts is achieved without difficulty. There is no waste and no waste like with parts that only have to have the correct dimensions on site. A particularly important advantage is that there are no large openings in the concrete after stripping, so that the time-consuming work of lubricating such openings is eliminated. Nevertheless, the concrete has an impeccable appearance that does not require rework. The supporting parts are expediently matt on their end faces and can be color-matched to the concrete. If there is a desire to close the small thread ends that are open on the end faces of the support parts, this can be achieved with a quick-insert stainless steel stopper. The plug has a thread so that it can be screwed into the screw-in thread of the support parts.

The screw-in threads of the support parts remain easily accessible, if necessary after removing a stopper, so that they can be used as anchor or fastening points for work to be carried out later on the building. This is another important advantage.

Depending on the type of formwork used by the building contractor, the length of the outer tie rods required for the construction of the formwork and for tensioning the same can be adjusted and kept in stock. The use of very long bars, such as the through-tension method, which necessarily protrude far on thin walls, narrow the working area and can lead to injuries, is eliminated.

The support parts expediently have a matt or rough surface, at least on their circumference, which further improves the adhesion in the concrete. Such a surface can be caused by the casting process, but can also be reinforced in other ways, in particular also by immersing the support part in a suitable coating material.

The support parts advantageously have an external shape that differs from a rotationally symmetrical shape, so that security against rotation is achieved if this is desired. The external shape can e.g. be polygonal or have another non-circular contour, in particular also lateral projections or the like. exhibit.

The support parts each have a threaded hole ending as a blind hole, into which the relevant end of the anchor rod can be screwed.

Securing the connection of the support parts to the anchor rod can be effected in various ways, in particular by pressing, squeezing or the like. of the support parts on the ends of the anchor rod.

Because there are only blind holes in the support parts, there is no passage or connection path for moisture or gaseous media, so that the finished concrete component is always tight.

In an advantageous embodiment of the system, the invention provides threads with a pitch of 6 mm for the clamping elements and for the screw-in thread of the support parts. Such a thread has the advantage that it is largely insensitive to influences that could loosen the connection. This is essential for use in formwork construction and for handling such parts on the construction site. Furthermore, the associated parts or their threads can be kept shorter in the case of bars with such a thread than in the larger thread pitches conventionally used. Finally, there is also a more precise adjustability.

• das im Längsschnitt gesehene Gewindeprofil hat einen Grundbereich, einen Kopfbereich und einen Übergangsbereich zwischen beiden,
• die Kontur des Grundbereichs ist zumindest überwiegend ein Kreisbogen,
• die Kontur des Kopfbereichs ist zumindest überwiegend eine parallel zur Gewindeachse verlaufende Gerade,
• der Übergangsbereich hat zumindest teilweise eine Kreisbogenkontur.

In a further advantageous embodiment of the system, the invention provides a thread for the clamping elements with the following features, to which the screw-in thread is designed:

• the thread profile seen in longitudinal section has a base area, a head area and a transition area between the two,
• the contour of the basic area is at least predominantly an arc,
• the contour of the head area is at least predominantly a straight line running parallel to the thread axis,
• the transition area has at least partially an arcuate contour.

Such a thread is particularly well suited for all screw connections that are to be carried out when erecting and dismantling concrete formwork with tension rods, anchor rods and the parts assigned to them. This applies among other things for the creation and loosening of these threaded connections as well as with regard to the load-bearing capacity and also largely insensitivity to the effects occurring on the building.

The radius of the circular arc contour of the base area is advantageously approximately 1.4 mm, although other values are also not excluded.

A radius of approximately 1.0 mm is favorable for the circular arc contour of the transition area. However, other values can also be considered.

A dimension can be referred to as the head width of the thread, that between the intersection points of tangents at turning points of the profile or such corresponding intermediate parts can be measured with extensions of the straight line of the head contour. In an advantageous embodiment of the thread, the head width is approximately 2.6 mm. However, other values are not excluded here either.

The respective angle between a tangent to a turning point or a corresponding intermediate section of the profile and a radius line or a perpendicular to the straight line of the head contour is advantageously approximately 30 °.

In a further advantageous embodiment of the system, the invention provides threads with external diameters of approximately 17 mm, 23 mm and 29 mm for clamping elements and for screw-in threads of the support parts.

The core diameter of a thread for clamping elements and for screw-in threads of the supporting parts is - especially in the case of the aforementioned outer diameters - advantageously about 14 mm or 20 mm or 26 mm.

• Fig. 1 eine Ausführung einer Abstandhaltereinheit in Ansicht,
• Fig. 2 eine besondere Ausbildung eines Gewindes in vergrößerter Schnittdarstellung,
• Fig. 3 einen Vertikalschnitt durch den mittleren Bereich einer Schalung für eine Wand,
• Fig. 4 einen Vertikalschnitt durch den außenliegenden Teil der Schalung nach Fig. 3 auf einer Seite derselben,
• Fig. 5 einen Stützteil in einem Längsschnitt nach der Linie V-V in Fig. 6,
• Fig. 6 eine Rückansicht des Stützteiles nach Fig. 5,
• Fig. 7 eine andere Ausführung eines Stützteiles in einem Längsschnitt nach der Linie VII-VII in Fig. 8,
• Fig. 8 eine Rückansicht des Stützteiles nach Fig. 7,
• Fig. 9 eine weitere Ausführung eines Stützteiles in axialem Längsschnitt,
• Fig. 10 einen Stopfen in Seitenansicht und
• Fig. 11 eine Stirnansicht zu Fig. 10.

Further details, features and advantages of the invention result from the following explanation of exemplary embodiments, from the associated drawing and from the claims. Show it:

• 1 shows an embodiment of a spacer unit in view,
• 2 a special design of a thread in an enlarged sectional view,
• 3 shows a vertical section through the central area of a formwork for a wall,
• 4 shows a vertical section through the outer part of the formwork according to FIG. 3 on one side thereof,
• 5 shows a support part in a longitudinal section along the line VV in Fig. 6,
• 6 is a rear view of the support member of FIG. 5,
• 7 shows another embodiment of a support part in a longitudinal section along the line VII-VII in FIG. 8,
• 8 is a rear view of the support member of FIG. 7,
• 9 shows a further embodiment of a support part in an axial longitudinal section,
• Fig. 10 is a plug in side view
• 11 is an end view of FIG. 10.

In Fig. 1 a spacer is shown, which forms a finished unit 1 for installation in a formwork. An anchor rod 2 is fixedly connected at its ends to support parts 3, each of which has a collar 8 and their end faces 4 are intended for direct contact with the walls of the formwork to be erected. The distance A of the end faces 4 determined during the manufacture of this unit 1 is thus equal to the desired distance of the formwork walls to be erected and thus the thickness of the wall to be concreted.

1 has a thread 5, in particular around a thread, as will be explained in detail in connection with FIG. 3 becomes. The support parts 3 are each provided with a corresponding thread in blind holes (cf. thread 9 in FIGS. 3, 5, 7 and 9), so that they can be screwed to the anchor rod 2 during the manufacture of the unit 1. The final securing of the position of the parts relative to one another can then take place in particular by pressing the support parts 3 with the anchor rod 2. The latter is the case in the embodiment according to FIG. 1. The number 6 indicates deformation points caused by a tool attack. A slight squeezing or pressing of the support part is sufficient to achieve a secure cohesion.

Each support part 3 is also provided in a blind hole open to its end face 4 with a screw thread 7 for a clamping element. The thread 7 and the corresponding thread of the tensioning element can be of the same type as the external thread 2 of the anchor rod 2. In particular, it is a suitable internal thread for the external thread shown in FIG. 2.

In the formwork construction according to FIGS. 3 and 4, a unit 1 of the embodiment shown in FIG. 1 forms the spacer between two formwork walls S1, against which the support parts 3 bear directly. As indicated by dash-dotted lines in Fig. 3, the anchor rod 2 can additionally be provided with a water barrier in the form of a plate 14 which e.g. is attached to the anchor rod by welding. In the left half of Figure 3, the support part 3 is shown in section, so that the blind hole with the thread 9 for the anchor rod 2 and the blind hole with the thread 7 for the tie rod 17 can be seen.

Solid wall girders T rest on the outer sides of the formwork walls S1. U-profile supports P are attached to their outer sides, against which a plate wing nut 15 supports. This is screwed onto a tie rod 17, which has the same thread 5 as the anchor rod 2. The arrangement of the parts is the same on the other side of the formwork. The tie rod 17 is screwed into the screw thread 7 of the support part 3. The formwork is tensioned with the plate wing nuts 15.

Instead of solid wall girders and U-shaped girders, other common parts can of course also be used to support the formwork, such as squared timbers and crossbeams or the like.

A modified embodiment of a support part 21 is shown in FIGS. 5 and 6. There is also a front collar 8, the outside of which gives the end face 4 for abutment against a formwork wall. The part of the support body 21 which adjoins the collar 8 has two strip-shaped projections 22 at diametrically located locations. The screw-in thread for a tensioning element in the blind hole of the supporting part which is open towards the front side 4 is also designated here by the number 7. To the other side there is a blind hole with a thread 9 for screwing in the anchor rod.

In the case of the embodiment according to FIGS. 7 and 8, features which correspond to the embodiments already described are designated with the same reference numbers as there. The supporting part 23 has a square shape 24 in its main body adjoining the collar 8, as particularly shown in FIG.

Finally, FIG. 9 shows a further exemplary embodiment of a support part 25 with a screw thread 7 for a tie rod and a screw thread 9 for an anchor rod. With its end face 4 to rest against the formwork wall determined front part of the Support part has a larger diameter than the rear part, so that there is a correspondingly large contact surface. The transition between the two areas is appropriately conical, as indicated by the angle 26.

After stripping, the end faces 4 of the support parts are normally flush with the outside of the concrete surface. If desired, the blind hole with the screw thread 7 can be closed by a plug. This can be an elastic plug of known type, which can be pressed into the threaded bore 7. FIGS. 10 and 11 show a stopper 30 which can be made of plastic or also corrosion-resistant metal and which has a thread 31 which fits into the screw-in thread 7 of the supporting part in question, which is slightly countersunk at its beginning, so that the stopper 30 screwed into it. The front of a head part 32 of the plug 30, which is bevelled in the manner of a countersunk screw, comes to lie flush with the end face 4 of the support part. A slot 33 or another type of key attack can be provided in the head part 32.

In Figure 2, a particularly advantageous embodiment of a thread is shown in an enlarged sectional view, as it is for the clamping elements, e.g. the tension rods 5 in Figures 3 and 4, and for the screw thread 7 in the support parts, but is also advantageous for an anchor rod, at least at the ends screwable into the support parts.

The thread profile according to FIG. 2 has a base region 41, the contour of which is at least predominantly an arc 42 with the radius R, and a head region 43, the contour of which is predominantly formed by a straight line 44. There is a between the base area and the head area Transition area 45, which is at least partially delimited by a circular arc contour 46 with the radius r.

A head width is designated with the letter B. It results from the intersections of tangents 48 at turning points 47 or small straight intermediate parts between the contours 42 and 46 with extensions of the straight line 44 of the head contour. The angles between the tangents 48 and radius lines are designated by the letter b. The thread has an outer diameter D and a core diameter d with a profile height h as the difference between them. The thread has a pitch t.

t =

6,0 mm

R =

1,4 mm

r =

1,0 mm

B =

2,6 mm

b =

30 °

   Für viele Einsatzfälle sind u.a. Außendurchmesser D von etwa 17 mm, 23 mm und 29 und Kerndurchmesser d von 14 mm, 20 mm und 26 mm besonders günstig.Advantageous values for the execution of such a thread are given below:

t =

6.0 mm

R =

1.4 mm

r =

1.0 mm

B =

2.6 mm

b =

30 °

Outer diameters D of approximately 17 mm, 23 mm and 29 and core diameters d of 14 mm, 20 mm and 26 mm are particularly favorable for many applications.

Such a thread is to a high degree insensitive to unfavorable effects, can be screwed easily and can absorb high loads. It is therefore particularly suitable for clamping elements, in particular of the type explained above, but can also be used advantageously for other parts in concrete construction.

Claims (15)

1. A concrete shuttering system with the shuttering walls (S1) being supported by spacers, each formed by a single tie bar (2) of steel with supporting parts (3, 21, 23, 25) on the ends which allow tensioning elements (17) in the form of bolts, bars or the like to be screwed in from the outside of the shuttering and which have end surfaces (4) suitable for resting against the inside of the shuttering walls (S1) or against abutments or the like inserted therein, wherein the respective tie bar (2) is provided with a thread (5) at least on its ends and is screwed into internal threads (9) of the supporting parts (3, 21, 23, 25), characterised in that the supporting parts (3, 21, 23, 25) consist of cast stainless steel and have screw threads (7) - ending in the manner of a blind hole - for the tensioning elements (17), the cross-sectional centres of the screw threads (7) for the tensioning elements (17) and the internal threads (9) for the ends of the respective tie bar (2) lying on the same longitudinal axis, and in that the tie bars (2) with the supporting parts (3, 21, 23, 25) are manufactured as ready-to-use units (1) with the supporting parts (3, 21, 23, 25) fixedly connected to the tie bar (2), the end surfaces (4) of the supporting parts (3, 21, 23, 25) being at a fixed distance (A) from each other which is determined through the manufacture of the unit (1) and corresponds to the desired distance of the shuttering walls (S1) from each other, and the units (1) placed in the shuttering being entirely left in the concrete after the concrete poured into the shuttering has set.
2. A system according to claim 1, characterised in that the supporting parts (3, 21, 23, 25) have a rough surface at least on their periphery.
3. A system according to claim 1 or 2, characterised in that the supporting parts (3, 21, 23) have an outer shape which deviates from a rotationally symmetrical form.
4. A system according to any one of claims 1 to 3, characterised in that the supporting parts (3) are connected to the tie bar (2) by pressing, squeezing or the like.
5. A system according to any one of claims 1 to 4, characterised in that threads with a pitch of 6mm are provided as screw threads (7) of the supporting parts (3, 21, 23, 25) and for tensioning elements (17) which can be screwed into the latter.
6. A system according to any one of claims 1 to 5, characterised in that for tensioning elements (17) which can be screwed into the supporting parts (3, 21, 23, 25), a thread with the following features is provided, to which the screw thread (7) is adapted:

   - the thread profile viewed in longitudinal section has a base region (41), a head region (43) and a transition region (45) between the two,

   - the contour (42) of the base region (41) is at least predominantly an arc,

   - the contour of the head region (43) is at least predominantly a straight line (44) extending parallel to the thread axis,

   - the transition region (45) at least partly has an arc-shaped contour (46).
7. A system according to claim 6, characterised in that the radius (R) of the arc-shaped contour (42) of the base region (41) is approximately 1.4mm.
8. A system according to claim 6 or 7, characterised in that the radius (r) of the arc-shaped contour (46) of the transition region (45) is approximately 1.0mm.
9. A system according to any one of claims 6 to 8, characterised in that a head breadth (B), measured between the points of intersection of tangents (48) at inflection points (47) or corresponding intermediate parts of the profile with prolongations of the straight line (44) of the head region (43), is approximately 2.6mm.
10. A system according to any one of claims 6 to 9, characterised in that the respective angle (b) between a tangent (48) at an inflection point (47) or a corresponding intermediate part of the profile and a radial line is approximately 30°.
11. A system according to any one of claims 1 to 10, characterised in that threads with an outer diameter (D) of approximately 17mm or 23mm or 29mm are provided for the tensioning elements (17).
12. A system according to any one of claims 1 to 11, characterised in that threads with a core diameter (d) of approximately 14mm or 20mm or 26mm are provided for the tensioning elements (17).
13. A system according to any one of claims 1 to 12, characterised in that the tie bar (2) is provided with the same thread (5) as the tensioning elements (17).
14. A system according to any one of claims 1 to 13, characterised by a plug (30) or the like which can be inserted into the screw thread (7) of at least one supporting part (3, 21, 23, 25) and which is made of stainless steel.
15. A system according to claim 14, characterised in that the plug (30) is provided with a thread (31) which fits the screw thread (7).

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