EP4086054A1

EP4086054A1 - A molding strip

Info

Publication number: EP4086054A1
Application number: EP22169895.4A
Authority: EP
Inventors: Jørn Dahl Blomstrøm
Original assignee: Gottfred Petersen AS
Current assignee: Gottfred Petersen AS
Priority date: 2021-04-29
Filing date: 2022-04-26
Publication date: 2022-11-09

Abstract

A molding strip (1) for use in a mold for molding concrete elements (50) having end faces with cavities (51, 53) and locking means (52), which molding strip (1) comprises: a support module (2) having a front and a back (3) and comprising at least one opening (4, 4', 4'') extending from the front to the back (3) for receiving locking means (52); at least two identical shaping modules (10) mutually adapted to the support module (2), said shaping modules (10) having: two end faces and a substantially flat back side. The at least two identical shaping modules (10) are releasably attached to the support module (2) such that an end face of one shaping module (10) abuts an end face of the other shaping module (10), while the back sides of the two shaping modules (10) abut the support module (2) and the at least one opening (4, 4', 4'') for receiving locking means (52) in the support module (2) is aligned with an opening (4, 4') for receiving locking means (52) in a shaping module (10).

Description

Technical field of the invention

This invention relates to a molding strip for use in a mold for molding concrete elements having an upper-side, a lower-side and four side surfaces, at least one side surface comprising a cavity and locking means, which molding strip comprises: a support module having a front and a back and comprising at least one opening extending from the front to the back for receiving locking means; at least two identical shaping modules mutually adapted to the support module, said shaping modules having: two end faces and a substantially flat back side; a front side with at least one projection for forming said cavity in the concrete elements; at least one opening extending from the front side to the back side for receiving locking means.
Prefabricated concrete elements are widely used today in many buildings. The concrete elements are typically made such that they can be connected two and two. Since the concrete elements are typically made with inlaid steel reinforcement, the actual assembly point (normally a whole side) of the individual concrete elements is manufactured such that the steel reinforcements from two joined concrete elements can be joined/fastened together.
Usually, the reinforcing bars protrude beyond an end side of the concrete element and the extensions protrude from an inner side of a cavity formed in the concrete element's end side. Normally, the steel reinforcement bars are placed in the mold such that the bars extend from side to side. When concrete elements are to be molded in a mold with a molding strip according to the invention, the steel reinforcement is laid into the mold such that a part of the steel reinforcement extends from the front of the molding strip (the side facing the mold), through the molding strip to its back (that side facing out of the mold).
The end side from which the reinforcing bars protrude from is made with a cavity adapted such that reinforcing bars protruding beyond an inner side in a cavity in an adjacent and identical concrete element can be accommodated therein. Thereby, two end sides can be joined tightly, while reinforcing bars protruding beyond an end side in a cavity in one concrete element are accommodated in the corresponding cavity in the other concrete element and vice versa.
Such a cavity can extend over almost the entire extent of the end side, and it is advantageous to make at least one end side of the concrete elements with a cavity from which reinforcing bars protrude. The idea is then that the end sides of the two concrete elements are put together with their cavities facing each other such that the reinforcing bars protruding from cavities in one concrete element are accommodated in the adjacent concrete element's cavities.
In prior art, the end sides of concrete elements are made with cavities by forming the cavities during the molding process by means of a so-called toothing strip or molding strip. The purpose of a molding strip is to form a cavity in one side of the concrete elements. The cavity usually extends as a longitudinal groove in the entire side and when two concrete elements are to be put together in a building, this happens such that the cavities abut each other. The cavity created thereby is subsequently filled with concrete. Experience has shown that it is advantageous to form the cavity in concrete elements such that it - along the cavity / groove - has varying depth. This is done by providing the molding strip with protruding areas. These areas have character of teeth and therefore a molding strip is also called a toothing strip.
The molding strip is inserted into the mold so that it lies along one side and such that the teeth form cavities in the side of the concrete element to be molded. The molding strip normally comprises a support member on which protruding parts (the teeth) are attached. Molding strips are normally made from wood, and they are heavily worn during the molding process and the removing of the molding strip from the molded concrete element is especially a task that often results in the molding strips being destroyed.
It is an object of the invention to provide an improved molding strip and / or to provide an alternative solution.
This is achieved in that the at least two identical shaping modules are releasably attached to the support module, such that an end face of one shaping module abuts an end face of the other shaping module, while the back sides of the two shaping modules abut the support module and the at least one opening for receiving locking means in the support module is aligned with an opening for receiving locking means in a shaping module.
In an embodiment of the invention, the support module comprises wood and the shaping modules comprise plastic.
When a toothing strip needs to be removed from the molded concrete, as described above, it will often be damaged. The reason for this is not completely clear, but it is realized with the invention that the combination of a support member and two shaping modules for forming the toothing strip entails an easier release of the toothing strip from the molded concrete. The release can be further improved by manufacturing shaping modules as injection molded modules in plastic, preferably with rounded edge(s)/corner(s). Rounded corners can be utilized in all aspects/embodiments of the invention. When the shaping modules are attached to a support member made of preferably wood, the release is even easier. At the same time, the modular construction is advantageous as individual parts can be easily replaced or even adapted in size to a specific task/mold.
In an embodiment of the invention, the openings in the shaping modules and the support module are adapted for receiving locking means in form of steel reinforcing bars. Reinforcement of concrete is often performed with steel bars. This embodiment will therefore, also in this respect, be advantageous, however, an opening adapted to steel reinforcement is of course also suitable for other types of reinforcement.
In an embodiment of the invention, the support module and the shape modules comprise mutually adapted guide means, which guide the shape modules to their intended position when shape modules are to be placed on a support module.
In a preferred embodiment, the guide means comprise magnets in the shape modules and/or the support module.
During the molding of concrete, sub-elements of the molding strip may break, and it may therefore be necessary to replace them. However, concrete often settles on the molding strip and it can therefore be difficult to visually guide a new sub-element into place. This problem is solved by means of guide means, which in a preferred embodiment comprises magnets which to a large extent - regardless of dirt - will guide a new sub-element to its intended place.
In an embodiment of the invention, the support module comprises electromagnetic means for positioning and releasable attachment of the support module to/in the mold.
In an embodiment of the invention, each shape module has a plane of symmetry extending along a longitudinal axis and a vertical axis of the shape module.
In an embodiment of the invention, each shape module has a plane of symmetry extending along a transverse axis and a vertical axis of the shape module.
By making the shape modules symmetrical, an easier manufacture of the individual modules is achieved. By making the shape modules symmetric about the longitudinal axis and the transverse axis is also achieved an easier montage of these on the support module, as the individual shape modules can be turned 180 degrees on the support module without affecting the functionality of the molding strip. This facilitates the assembly of the molding strip.
Other embodiments are recited in the dependent claims.
In this application the words "toothing strip" and "molding strip" are used about the same technical means. The reason for switching between these terms is purely linguistic. Technically, there is no difference between a toothing strip and a molding strip.
The shaping modules are referred to as having two end faces, these two end faces could just as well be called end sides. The choice to call them "end faces" rather than "end sides" is made solely for linguistic reasons.

Brief description of the figures

Figure 1 shows in perspective an embodiment of the invention.
Figure 2 shows in perspective an embodiment of a molding strip seen from the backside.
Figure 3 shows in perspective an embodiment of a molding strip seen from the frontside.
Figure 4 shows in perspective an embodiment of a shaping module.
Figure 5 shows schematically a connection between two concrete elements.

Detailed description of the invention

It should be noted that embodiments and features described in the context of one of the aspects of the present invention also apply to other aspects of the invention.
An embodiment of the present invention will now be described in more detail in the following with references to the figures.
Prefabricated concrete elements are widely used today in many buildings. The concrete elements are typically made so that they can be connected. Since the concrete elements are typically made with inlaid steel reinforcement, the actual assembly point (normally a whole side) of the individual concrete elements is manufactured such that the steel reinforcements from two joined concrete elements can be joined/fastened together.
In figure 1 is shown an embodiment of a molding strip 1 according to the invention. The molding strip is for use in a mold for molding concrete elements having an upper-side 50', a lower-side (not shown in the figures), and four sides of which only the front- side is shown in figure 1. The front-side comprises two end sides 55, 57. The two end sides 55, 57 are situated on each side of a cavity 51, 53 comprising locking means 52. The molding strip 1 comprises: a support module 2 having a front (not visible) and a back 3 and comprising at least one opening 4 extending from the front to the back for receiving locking means 52. The front of the support module comprises two profiles 56 having planner surfaces 55', 55"extending in the longitudinal direction L of the support module. These surfaces are not shown in figure 1, however, their positions are indicated. The surfaces 55' and 55" are, in the shown embodiment, forming (shaping) the concrete element's end sides 55, 57. The molding strip further comprises at least two identical shaping modules 10. The shaping modules 10 are attached on the upper side (the side facing the mold) of the molding strip 1. The shaping modules in the shown embodiment comprise five protruding parts 11, of which only one is applied with reference 11 in the figure. The purpose of the protruding parts 11, are to form cavities of different depths in the molded concrete elements. A shaping module 10 is shown in greater detail in figure 4. A molding strip according to the invention comprises at least two identical shaping modules.
To the right in Figure 1 is shown a holding/end piece 22. This end piece is not a part of the molding strip but serves to hold the molding strip 1 in place during molding/casting of concrete elements.
As seen in figure 1, the back of the support module 2 comprises three sets of round areas 4, 4 ' and 5. These areas are normally directly connected to the shaping modules such that compressive forces applied to the shaping modules during casting are transferred directly to the holding piece 22. The areas 4,4'and 5 can be regarded as feet supporting the shaping modules as explained above. At the bottom of Figure 1, reference numeral 6, is shown a channel opening. The channel runs between the support module 2 and the shaping module 10 and the channel 6 extends, in the longitudinal direction L, along the entire length of the molding strip. The shaping modules are thus supported along their edges on the support module, but a large part of the forces applied to them during the casting of concrete elements are absorbed through the above-mentioned feet 4, 4' and 5, which pass through the support module and abut against the holding module 22.
By not performing the molding strip as a solid element, but with an internal longitudinal channel 6 and feet 4, 4'and 5, material and weight savings are achieved.
Usually, the feet are made as sub-areas of the back of the shaping modules, which are simply extended and mutually adapted to the support module such that they can extend through the support module and transmit the compressive forces applied to the shaping modules during casting directly to the holding piece 22. Normally, the round areas/feet 4,4'and 5 are integrated parts of the support modules and may be produced during injection molding of the support modules and accordingly be produces in mainly the same material as the support module. However, the feet may be produces as independent parts attached to the shaping modules. The feet 4, 4' and 5 can be machined and adapted in order to e.g. contain magnets, preferably neodymium magnets.
The molding strip may be produced such that the profiles 56 are situated on the back of the support module 3, such that they create a channel between the support module 22 and the back of the support module. If the molding strip comprises such a support element having an essentially flat front (the side facing the mold), said molding strip must accordingly comprise thereto complementary shaping modules having flat back sides supporting directly on the support module.
In figure 1 is seen reinforcing bars 52 protrude beyond an end side 55 of the concrete element. The reenforcing bars 52 protrude from an inner side of a cavity 51 formed in the concrete element. Normally, the steel reinforcement bars are placed in the mold such that the bars extend from side to side. When concrete elements are to be molded in a mold with a molding strip according to the invention, the steel reinforcement is initially laid into the mold such that a part of the steel reinforcement extends from the front of the molding strip 1 (the side facing the mold), through the molding strip to its back 3 (that side facing out of the mold).
The area 4, are usually made with an opening (not shown) so that steel reinforcement can pass through it and support directly against the holding piece 22.
To the left in figure 1 is shown a finished concrete element 50 comprising reenforcing steel bars 52. The steel bars protrude beyond the end sides 53 in a cavity 51 in the concrete elements 50. The steel bars are normally placed in the mold before the actual molding takes place, and normally situated such that the bars extend from side to side. When concrete elements are to be molded in a mold with a molding strip according to the invention, the steel reinforcement bars are placed into the mold such that a part of the steel reinforcement bars 52 extends through the mold and further through the molding strip. In figure 1 is shown a concrete element 50 made by use of a molding strip 1 according to an embodiment of the invention. The molding strip 1 is in figure 1 removed from the molded concrete element 50 and the steel bars 52, formed as bends are protruding beyond the concrete element's end side (s) 55. The bent steel reinforcement bars 52 are usually made as explained above, but they can of course be made in other ways. For example, the bent steel reinforcement bars 52 do not need to extend all the way from side to side in the finished concrete element.
The cavity and bends from which the reinforcing bars 52 protrude are mutually adapted such that reinforcing bars from an adjacent and identical concrete element can be accommodated in the cavity.
This functionality of the cavity and steel bars is best seen in figure 5, showing an embodiment of a connection between two molded concrete elements 101, 102. Each of these concrete elements 102, 101 are provided with steel reinforcing bars 52 that protrudes beyond an end side 55 in form of bends. The bends from one concrete element protrudes into the other concrete element's cavity and the bends from one concrete element are together with the bends from the connected concrete element forming loops 103. These loops 103 are normally used to further fixate the two concrete elements in a mutual engagement and the fixation may be strengthened by e.g., a steel reinforcement bar 104 introduced through these loops. When two concrete elements are assembled, the cavity between the two elements is usually filled with concrete as also indicated in figure 5, which will further strengthen the connection.
In figure 2 is shown (from the back side) another embodiment of a molding strip according to the invention. The support member 2 shown in this embodiment comprises three openings 4,4', 4", each extending through the molding strip. The support member further comprises three magnets 21, 21'and 21". The magnets 21, 21 'and 21" entail an easy positioning of the molding strip in the mold. The magnets shown in figure 2 are protruding beyond the back of the support module, which is normally not the case. The magnets are normally attached to the shaping modules.
In figure 3 is shown a molding strip 10 according to an embodiment of the invention. The molding strip is seen from the front (the side which faces into the mold when molding). The molding strip in this embodiment comprises two identical shaping modules. Each module comprises an opening 4, 4' for steel reenforcing bars. And each shaping module, in figure 3, comprises two protruding parts 40, 41, 40' 41'. The joint between the two modules is indicated in the figure by the arrows. The molding strip shown in figure 3 comprises two shaping modules, however the skilled person may change the number depending on the task. The person skilled in the art may even use half shaping modules or parts of one or more shaping modules, to build a molding strip for a given mold. The shaping modules are usually made of plastic and by injection molding. One material that has been shown to have good slip properties is polypropylene (PP). However, other materials can be used. It is with the invention realized that the combination of shaping modules made mostly of plastic and a support module made mostly of wood give the molding strip some attractive slip properties, which entail easy detachment/removal of the molding strip from finished concrete elements. Furthermore, the modular construction also entails savings as the individual shaping modules may easily be removed and replaced with new ones if they are damaged.
In figure 4 is shown a shaping module according to an embodiment of the invention. The shown shaping module comprises to protruding parts 40, 41. Between the protruding parts the opening 4, 4' is situated for the receiving of reenforcing bars. The shaping module is symmetric about a transverse axis parallel with the opening's longitudinal center axis C (shown in figure 3). The shaping module in figure 3, shown embodiment comprises openings 75 for releasably fastening to a support module, e.g. by a screw connection. In a preferred embodiment the shaping modules are made with deburred and/or rounded edges. This entails easy release/removal of the molding strip from a molded concrete element.
In figure 5 is shown, in side view, a connection between two concrete elements 101 and 102. Each of the elements comprises reenforcing steel bars 52, in form of bends, which protrude beyond the end side of each element and into the connected/adjacent element's cavity. The bends form a loop 103. The connection/joint between the two elements are strengthened/locked by use of a steel bar 104 inserted through the loop (s), which in the shown embodiment is in and out of the drawing. After the insertion of a steel bar through the loop(s) concrete and/or other harden-able material is poured into the cavity between the elements to harden there.
Wood has been a widely used material for building concrete molds and usually the wood is easily removed from the mold, once the concrete has hardened. However, it has been found that this ease is due to the wood being removed in a single motion, essentially perpendicular to the surface from which it is removed. When the mold is to form concrete elements of more complex shapes, such as concrete elements with a cavity in one side, the parts forming the cavity will not be removable in a single movement, essentially perpendicular to all the surfaces of the cavity.
In a preferred embodiment, the molding strip is adapted such that the support member forms the flat surfaces on the end of the concrete element (i.e., the edges of the cavity), while the shaping elements form the cavity. These flat surfaces are end-surfaces being essentially perpendicular to the top and bottom of the concrete element. A molding strip made like this can therefore be removed in a single motion, essentially perpendicular to the end-surfaces which entails that said molding strip is easily removed from a molded concrete element, even if the support member is mostly made of wood. The shaping modules in this embodiment are preferably made of plastic with good slip properties. They can, for example, be made of injection-moldable plastic like polypropylene. The functionality of these embodiments is best illustrated in figure 6, where the flat surfaces of the concrete element formed by the support member are seen with reference 60. This figure shows a part of a concrete element formed by a molding strip according to the invention and a support member (made mostly of wood), having all but one of the shaping modules (made mostly of injection molded plastic) removed. These embodiments may be used in any aspects or embodiments of the invention.

Claims

A molding strip for use in a mold for molding concrete elements having an upper-side, a lower-side and four sides, at least one of the four sides comprises a cavity and locking means, which molding strip comprises:
• a support module having a front and a back and comprising at least one opening extending from the front to the back for receiving locking means;

• at least two identical shaping modules mutually adapted to the support module, said shaping modules having:
∘ two end faces and a substantially flat back side;

∘ a front side with at least one projection for forming said cavity in the concrete elements;

∘ at least one opening extending from the front side to the back side for receiving locking means;

characterized in that,
the at least two identical shaping modules are releasably attached to the support module such that an end face of one shaping module abuts an end face of the other shaping module, while the back sides of the two shaping modules abut the support module and the at least one opening for receiving locking means in the support module is aligned with an opening for receiving locking means in a shaping module.
A molding strip according to claim 1, characterized in that, the support module comprises wood and the shaping modules comprise plastic.
A molding strip according to claim 1 or 2, characterized in that, the openings in the shaping modules and the support module are adapted for receiving locking means in form of steel reinforcing bars.
A molding strip according to any of the claims 1-3, characterized in that, the support module and the shape modules comprise mutually adapted guide means, which guide the shape modules to their intended position when shape modules are to be placed on a support module.
A molding strip according to any of the claims 1-4, characterized in that, the guide means comprise magnets in the shape modules and/or the support module.
A molding strip according to any of the claims 1-5, characterized in that, the shape modules are made by molding, preferably injection molding.
A molding strip according to any of the claims 1-6, characterized in that, the support module comprises electromagnetic means for positioning and releasable attachment of the support module to/in the mold.
A molding strip according to any of the claims 1-7, characterized in that, each shape module has a plane of symmetry extending along a longitudinal axis and a vertical axis of the shape module.
A molding strip according to any of the claims 1-8, characterized in that, each shape module has a plane of symmetry extending along a transverse axis and a vertical axis of the shape module.
A molding strip according to any of the claims 1-9, characterized in that, the support module's front comprises at least one surface adapted for forming a surface on the concrete elements.