Patent Application
20120080431
This claims the benefit of German Patent Application DE 10 2010 041 904.4, filed Oct. 4, 2010 and hereby incorporated by reference herein.
The invention relates to a filler for an anchor rail. Such a filler is configured with an elongated filling element and with a tear strip for removing the filling element from the cavity of the anchor rail, said tear strip being joined to the filling element in a joining area. The invention also relates to a method for producing a filler with an elongated filling element and with a tear strip for removing the filling element from the cavity of the anchor rail, whereby the tear strip is joined to the filling element in a joining area.
Anchor rails that have a C-profile and that can be embedded into concrete are known. On one lengthwise side, two such anchor rails have two opposing rail lips between which an opening that runs along the length of the anchor rail is formed in the interior of the anchor rail.
Since such anchor rails are installed in the formwork before the concrete is poured, as a rule, they have to be sealed off to prevent the penetration of concrete so as not to lose their function. This can be done by inserting a filling element into the cavity of the anchor rails. Anchor rails with temporary filling materials are disclosed, for example, in German utility model DE 87 05 644 U, in U.S. Pat. No. 4,532,740 A and in German utility model DE 295 15 152 U1.
The foam-like filler is normally removed before the anchor rail is used. In order to facilitate the removal of the temporary rail filling, U.S. Pat. No. 4,532,740 A and German utility model DE 87 05 644 U, for instance, disclose tear strips that have been applied to the underside of the filling material in the lengthwise direction of the rails.
One way to position the anchor rails prior to pouring the concrete consists of placing the anchor rails on the formwork and affixing them to the formwork, for example, with nails. When the anchor rail is put into place, the opening, which runs lengthwise along the anchor rail and which faces outwards so as to receive fastening elements (such as, for example, hammer-head bolts) once the element has been embedded into the concrete, comes into contact with the formwork.
However, it has been found that it is not always possible to reliably install the anchor rail. Sometimes, the anchor rail can be improperly oriented when it is fastened to the formwork, which can cause the incorrect orientation of the anchor rail once the element has been embedded in the concrete.
It is an object of the present invention is to aid in positioning anchor rails reliably positioned without much effort.
The present invention provides that the filler according to the invention is characterized in that the tear strip is joined to the filling element with extra length in at least part of the joining area.
Within the scope of the invention, it was observed that, with the prior-art anchor rails, under certain circumstances, the filling element comes out of the anchor rail between the rail lips and that this phenomenon can be the reason for the difficulties encountered when the prior-art anchor rail is positioned on the formwork. After all, when the filling element comes out of the anchor rail, a flat contact surface is no longer present in the area of the rail lips, as a result of which the rail can tilt when the rail is placed on the formwork.
The invention has also recognized that the design of the prior-art filling element might be responsible for the unwanted effect that the filling element comes out of the anchor rail, and thus for the difficulties encountered when the rail is positioned. Therefore, with the prior-art fillers, the tear strip is glued onto the entire surface of the filling element. In other words, when the anchor rail is not under tension, the part of the tear strip that forms the adhesive connection and the glued surface have the same length. The tear strip, however, fundamentally has a greater tensile strength and, as a rule, also a greater tensile stiffness, than the foam material. As a result, the stiffness of a prior-art filler does not remain constant over the cross section of the filler. Such different stiffness values over the cross section, however, can cause the composite material to bend when it is subjected to centered forces, and/or when changes in temperature cause the length of the tear strip and of the filling element to change differently because of their different coefficients of thermal expansion.
Therefore, in the familiar combinations of filling elements and tear strips, heat can cause the filling element to bend and to come out when the pull strip is arranged underneath the filling element since the pull strip hinders the expansion of the foam. As a result, the foam is pushed towards the outside through the rail lips so that, under certain circumstances, a flat contact surface is no longer present and the above-mentioned difficulties arise when the rail is positioned.
With the familiar rails that have a tear strip glued onto the entire surface of the filling element, an unwanted bending of the filling element can occur not only in the case of exposure to heat but also if the walls of the cavity inside the rail are not flat, but rather, have elevations of the type that can be created, for example, by anchoring elements of the anchor rail. In this case, the elevations can press into the filler, whereby the soft filling element can easily accommodate this deformation. In contrast, however, the tear strip into which the elevations likewise press, is spatially dislodged by the elevations and considerable tensile forces are generated due to the existing tensile stiffness in the strip. As a result, the tear strip, which is on the underside, becomes tensioned like a wire and pushes the foam between the rail lips towards the outside.
These two effects have in common the fact that the foam that has been pushed out between the rail lips can detrimentally affect the nailing of the rail onto the formwork, especially since there is no longer a flat contact surface.
This is where the invention comes to the fore and provides a design of the filling element in which the tear strip has extra length in the joining area, in other words, a surplus in the length with respect to the adjacent filling element. In order to create such an extra length, it can be provided, for instance, that the strip does not run parallel to the filling element in the joining area, but rather, its distance from the filling element varies along the joining area. In this case, the strip extends into an additional spatial direction with respect to the surface of the adjacent filling element, whereby the extra length stems from this additional spatial direction. Therefore, the term extra length can especially refer to the fact that the length of the tear strip in the joining area is greater than the lengthwise extension of the filling element in the joining area.
Thanks to this extra length, the tear strip can be lengthened in the lengthwise direction of the filling element without the need to stretch the relatively tensile-stiff strip for this purpose. Rather, the greater length in the lengthwise direction stems from the extra length of the tear strip, that is to say, the greater length in the lengthwise direction is not brought about by deformation of the tear strip, but rather, by a geometrical rearrangement of the strip. Due to the extra length, the strip exhibits an effective tensile stiffness that is less than the actual tensile stiffness.
Owing to the reduced effective tensile stiffness, in turn, the strip can follow along with the thermal expansions of the filling element and/or with the mechanical deformations of the filling element brought about, for example, by pressing elevations, without this causing tensioning between the strip and the filling element. Therefore, the invention prevents the foam from being pushed out through the rail lips towards the outside, thus avoiding the resultant difficulties known from the state of the art when it comes to positioning the rail.
The extra length in the tear strip can be present especially at least at room temperature (20° C.) and/or at least before the filler is inserted into the anchor rail. The extra length can amount to at least 1%, especially at least 5%, preferably at least 10% or 13%, especially preferably about 15%, that is to say, the tear strip is longer by this percentage value than the surface of the adjacent filler. The extra length can then accommodate thermal deformations of the filling element when it warms up above room temperature or if mechanical deformation of the filling element occur when it is inserted into the anchor rail. In particular, according to the invention, the extra length is present in those cases when the molded part runs straight, in other words, when it is in a geometrical configuration that it also has when it is inside the anchor rail.
The tear strip preferably can be fiber-reinforced. In a suitable manner, the tear strip has a backing strip that can be made, for example, of polyethylene (PE), polypropylene (PP) or polyethylene terephthalate (PET). The filling element can especially be a foam element and can contain, for instance, plastic foam such as polyethylene foam, low-density polyethylene foam (LDPE) or polystyrene foam.
The joining area where the tear strip is joined to the filling element can be contiguous or non-contiguous.
Extra length according to the invention can be provided along the entire length of the joining area of the filling element. But is likewise possible to provide concentrated extra length that is created, for example, where the elevations that press into the filling element will be present later. Accordingly, it can be sufficient if the tear strip is joined to the filling element only in a part of the joining area of the filling element that has the extra length. Extra length that has been concentrated according to the invention can also be created by a roller that has a varying surface geometry along its circumference. Thus, a roller can be provided that has a circular circumference over an angular range of, e.g., 270°, and that is provided with teeth over the remaining angular range (here 90°, for example). When the filling element passes over this roller, a concentrated extra length is created with each revolution of the roller. Therefore, continuously recurring areas of extra length can be created, for instance, for rivets.
It is particularly preferred if, in the at least one part of the joining area where the tear strip is joined to the filling element with extra length, the tear strip has a meandering, especially a wavy, layout along the filling element, with a varying distance from the filling element. For one thing, the meandering layout translates into an especially large extra length. At the same time, numerous contact sites with the filling element can be created, so that a very good bond is obtained. In particular, it can be provided that the strip and the filling element are joined at upper reversal points with a meander-like cross section.
Furthermore, it is advantageous for the tear strip to be glued to the filling element in the joining area. In this manner, the bond between the strip and the filling element can be created particularly easily. In order to achieve proper adhesion, the strip can have, for instance, an adhesive layer.
Especially with an eye towards a very large extra length, but also in terms of the manufacturing work involved, it can be advantageous for the filling element to have an at least approximately flat surface in the joining area.
The invention also relates to an anchor rail that can be cast into a component, comprising a rail element having a cavity that extends in the lengthwise direction of the rail element, whereby the anchor rail is characterized in that a filler according to the invention is provided in the cavity, whereby the tear strip is joined to the filling element with extra length in at least part of the joining area. Due to the extra length of the tear strip of the filler arranged in the cavity, in other words, due to the fact that the strip is provided with a greater length than the corresponding unwinding of the filling element, it is ensured that the filler does not come out of the rail in the case of changes in temperature.
The method according to the invention for the production of a filler is characterized in that the tear strip is joined to the filling element in at least part of the joining area, thereby creating extra length.
In particular, according to the invention, this extra length is present when the molded part runs straight and/or when it is in a geometrical configuration that it also has when it is inside the anchor rail. Owing to the enlarged length of the tear strip in comparison to the underside of the filler, extra length of the filler is created to accommodate tensile stretching, and this extra length can be utilized before the pull strip itself has to absorb tensile forces. Even local elongations that can occur, for instance, due to elevations in the rail element, can be accommodated by the distributed extra length since locally limited stretching differences can be quickly overcome.
For example, it can be provided that the filling element is stretched, especially stretched elastically, at least partially, in the lengthwise direction, and that the tear strip is joined to the filling element in an elongated area of the filling element. Accordingly, the filling element is elastically lengthened, at least on the underside. In this phase, the tear band is glued onto the underside. During the subsequent recovery, no compressive stress can build up in the tear strip, which is soft to pressure. Consequently, the strip, which is installed tension-free, retains its original length, which is indeed greater than that of the filling element. This is how the extra length in the strip is created.
As seen in the lengthwise direction, the filling element can be stretched along its entire length. For this purpose, a tensile load, for example, can be applied onto the opposite ends of the filling elements. Insofar as the filling element is stretched along its entire length, the tear strip can be simultaneously joined to the filling element along the entire length of the filling element. The filling element, however, can also be stretched only in certain sections, in which case the strip is applied onto the stretched section. This is particularly advantageous within the scope of a continuous process. In this case, only one section of the total length of the filling element can be stretched at a given point in time.
The stretching, in other words, the positive elongation of the filling element, can act upon the entire cross section of the filling element. This corresponds to a pure tensile load. Fundamentally speaking, however, it is sufficient if the stretching is only present on the underside of the filling element, that is to say, on the side that is joined to the strip. In the remaining cross-sectional areas, smaller positive elongations or even negative elongations can be present.
It is also preferred for the filling element to be curved, especially elastically curved, at least in certain areas, namely, particularly around a roller and/or around a guide element, and for the tear strip to be joined to the filling element in a curved area of the filling element. According to this embodiment variant, the filling element is curved, so that its underside is lengthened with respect to the neutral tear strip. This can be done, for instance, when it passes around a roller. The strip is applied in this state. Once the filler recovers from being bent, the lengthened underside of the filling element reacquires its original length, which is the same as the length of the neutral fiber. The tear strip is compressed in this process. Since it does not have any compressive stiffness, detached sections and waves are formed in certain areas and these create the extra length.
As seen in the lengthwise direction, the filling element can be curved along its entire length. Insofar as the filling element is curved along its entire length, the tear strip can be simultaneously joined to the filling element along the entire length of the filling element. The filling element, however, can also be curved only in certain sections, in which case the strip is applied onto the curved section. This is particularly advantageous within the scope of a continuous process. In this case, just one section of the total length of the filling element can be curved at a given point in time.
According to the invention, the bending can be around an axis that runs transversally, preferably perpendicularly, to the lengthwise direction of the filling element, whereby the at least one bending axis advantageously runs above the filling element when the strip is installed on the underside of the filling element.
Another preferred embodiment of the invention comprises the fact that the filling element is profiled, especially elastically profiled, at least in certain sections, namely, especially by means of a toothed roller, and that the tear strip is joined to the filling element in a profiled area of the filling element. For example, it can be provided that a toothed roller with projecting teeth runs over the back of the filling element. These teeth are pressed into the filling element and thus lengthen the unwinding surface of the filling element on the underside. When the tear strip is subsequently applied, it follows the embossed profile since the elastic/viscous recovery of the impression takes place with a time delay. Once the deformation of the filling element is reversed, the underside of the filling element reacquires its original dimensions. The tear strip is compressed in this process. Since it does not have any compressive stiffness, detached sections and waves are created in certain areas and these create the extra length. In contrast to the above-mentioned embodiment variant, in this embodiment, the underside is not lengthened continuously but rather, discontinuously,
The invention can also encompass a method for the production of an anchor rail that can be cast into a component, comprising a rail element that has a cavity that extends in the lengthwise direction of the rail element. With such a method, it can be provided that a filler corresponding to the invention is produced and then the filler is inserted into the cavity, a process in which it is provided that, at least when the filler is being inserted, the tear strip is joined to the filling element with extra length in at least one part of the joining area.
The features mentioned in conjunction with the method according to the invention can also be utilized for the products according to the invention, by the same token that, conversely, the features mentioned in conjunction with the products can be utilized with the methods.
The invention will be explained in greater detail below on the basis of embodiments that are schematically depicted in the accompanying figures. The following is shown:
FIG. 1—the cross section of an anchor rail with a filler according to the invention;
FIG. 2—a side view of the filler from
FIG. 3—another embodiment of a filler in a side view, whereby the meandering layout of the tear strip is shown in a markedly elevated view for the sake of clarity;
FIG. 4—a first embodiment of a method according to the invention for the production of a filler;
FIG. 5—a second embodiment of a method according to the invention for the production of a filler;
FIG. 6—a third embodiment of a method according to the invention for the production of a filler; and
FIG. 7—a fourth embodiment of a method according to the invention for the production of a filler.
As shown in
The tear strip 21 also has an extra length 24 by which the tear strip 21 projects beyond the underside of the filling element 16, allowing the tear strip 21 to be gripped.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2010 041 904.4 | Oct 2010 | DE | national |
