Weight-optimized telescopic construction support

Abstract

Telescopic construction support, especially for use in formwork construction in accordance with standard EN 1065, comprising: a) a hollow outer tube (1) with a lower end connected to a base plate (3); b) a hollow inner tube (2) which is telescopically guided in the outer tube (1) and can be locked at various extension lengths relative to it and has an upper end which is connected to a head plate (4); and c) a height adjustment device, typically comprising an external thread (5) arranged on the outer tube (1) and an adjusting nut (6) running thereon, characterized by the fact that d) the outer tube (1) has in its wall a plurality of recesses (7) serving to reduce weight, which are arranged in at least two helical paths offset around the longitudinal axis of the tube (1) in such a way that no continuous weakening line extending in the axial direction is formed.

Description

Technical field

[0001] The invention relates to the technical field of construction site equipment and specifically to adjustable telescopic steel construction props, such as those typically used for the temporary support of formwork for slabs or other loads in building construction and civil engineering. Such construction props are subject to the stringent requirements of the European standard DIN EN 1065:1999-01, which defines the essential specifications for material, design, dimensioning, and testing to ensure safety on construction sites. State of the art

[0002] Telescopic construction props according to EN 1065 have been an established and widely used product on the market for decades. They essentially consist of an outer tube in which an inner tube is telescopically slidable. Coarse height adjustment is achieved using a locking pin inserted through corresponding holes in the inner and outer tubes, while fine adjustment and pre-tensioning are accomplished via a robust thread with an adjusting nut. Leading manufacturers such as Doka, PERI, Hünnebeck, and GBM offer a variety of models that differ in load-bearing capacity classes (e.g., class B, D, E), extension lengths, and weight.

[0003] A significant disadvantage of these conventional steel columns is their high weight, which makes handling on the construction site difficult, increases the physical strain on workers, and affects transport costs. The industry has responded to this problem with two basic strategies: 1. Material substitution: The use of lighter materials. For example, Doka offers the “Eurex 60”, a high-strength support made of aluminum. However, this approach involves significantly higher material costs and is therefore often uneconomical for the mass market. 2. Geometry and material optimization: The use of higher-strength steels in combination with optimized pipe geometries, i.e., the adjustment of pipe diameters and wall thicknesses to maximize the strength-to-weight ratio. Products such as PERI's PEP columns aim for such optimization but are invariably based on the use of closed, unperforated pipe profiles for the load-bearing outer tube.

[0004] A detailed analysis of the products from all leading suppliers reveals that not a single commercially available construction prop uses perforations or cutouts in the load-bearing outer tube to reduce weight. This practice has become a deeply ingrained technical misconception within the industry. The integrity of the outer tube is considered an essential quality and safety feature. For example, it is explicitly advertised that the external thread is produced using a roll forming process without material removal in order to maintain material integrity.

[0005] This misconception is rooted in fundamental engineering challenges. The most critical failure criterion for a slender, compression-loaded column is buckling – a sudden lateral deflection of the structure that can occur well below the material's yield strength. The entire design process according to EN 1065 aims to reliably prevent this buckling. Technical literature confirms that perforations significantly reduce the critical buckling load of a compression member. The reduction depends complexly on the size, shape, and arrangement of the holes. A perforation in the middle of the column's length, where maximum deflection occurs during buckling, has the most detrimental effect.

[0006] Additionally, any geometric discontinuity, such as a hole, leads to a local increase in mechanical stress, known as stress concentration or notch effect. At the edges of the holes, the stresses can reach many times the nominal stress in the undisturbed pipe cross-section, which can lead to premature material failure or fatigue cracking.

[0007] Due to these known and serious risks, experts (e.g., structural engineers in formwork construction) instinctively reject the idea of ​​perforating the load-bearing outer tube of a construction support as unsafe and non-compliant with standards. The state of the art is therefore limited to solid-walled tube constructions made of steel or aluminum. Object of the invention

[0008] The invention is based on the objective of further developing a telescopic steel construction support in such a way that its own weight is significantly reduced while maintaining or comparable load-bearing capacity and stability in accordance with the requirements of standard EN 1065, in order to facilitate handling on the construction site and reduce transport costs without having to resort to expensive materials such as aluminum. The aim is to create a solution that overcomes the aforementioned technical prejudice and represents a safe, standards-compliant, and economical alternative to existing constructions. Solution to the problem and advantages

[0009] This problem is solved by a telescopic construction support with the features of claim 1. Advantageous embodiments of the invention are described in dependent claims 2 to 10.

[0010] The core idea of ​​the invention is to provide the outer and / or inner tube of the construction support with a plurality of recesses specifically designed to reduce weight. The invention lies not in the trivial act of creating holes, but in overcoming the associated technical problems. The solution consists of the specific, non-obvious, engineering design of the shape, size, number, and, in particular, the arrangement of these recesses.

[0011] A key feature of the invention is that the perforations are arranged offset around the longitudinal axis of the tube in such a way that no continuous, axially extending weak line is created. This is crucial for maintaining the overall buckling stability of the column. This configuration is designed to control the critical failure modes—in particular, the overall buckling of the column and local stress concentrations at the perforation edges—and to ensure that the column fully meets the load-bearing capacity and safety requirements of EN 1065. This is preferably achieved through the use of modern computer-aided simulation methods such as finite element analysis (FEA), which allow for precise optimization of the perforation pattern.

[0012] The construction support according to the invention offers a number of significant advantages over the prior art: • Significant weight reduction: Through targeted material removal, the column's own weight is significantly reduced compared to a solid-web steel column of the same load-bearing capacity. This improves ergonomics and reduces physical strain for construction workers. • Reduced transport costs: The lower weight per support allows for the transport of more units per truckload, resulting in logistical savings. • Improved handling and productivity: Lighter supports can be positioned, adjusted and repositioned more quickly, easily and safely by workers, increasing efficiency on the construction site. • Cost-effectiveness: The weight reduction is achieved through intelligent design and not through the use of expensive materials such as aluminum, which allows the support to be manufactured cost-effectively. Brief description of the drawing

[0013] Further advantageous embodiments of the invention can be found in the claims and are explained in more detail below with reference to an exemplary embodiment shown in the drawing. It shows: Fig. 1: A perspective view of an exemplary embodiment of the weight-optimized construction support according to the invention.

[0014] The locking pin, commonly used for coarse height adjustment, is shown in the illustration. Fig. 1 not shown for clarity. Detailed description of the embodiment examples: First embodiment example (perforated outer tube)

[0015] Fig.Figure 1 shows an embodiment of the telescopic construction support according to the invention. This comprises an outer tube (1) to the lower end of which a square base plate (3) is welded for load distribution on the ground. In the upper region of the outer tube (1) an external thread (5) is formed, on which an adjusting nut (6) with handles runs.

[0016] An inner tube (2) is telescopically guided within the outer tube (1). A head plate (4) is attached to the upper end of the inner tube (2), which serves to receive the load to be supported. The inner tube (2) has regularly spaced, typically circular, fixing holes (not shown) which serve to receive a locking pin for coarse adjustment of the support height.

[0017] According to the invention, the wall of the outer tube (1) is provided with a plurality of recesses (7). In the preferred embodiment shown, these recesses (7) are elliptically shaped and arranged in several helical paths around the longitudinal axis of the outer tube (1). This specific arrangement is the result of an engineering optimization. The staggered, helical arrangement ensures a uniform weakening of the cross-section along the length of the support and avoids the formation of a critical, straight weakening line in the axial direction, which significantly improves buckling stability.

[0018] The elliptical shape with its longitudinal axis in the circumferential direction, as claimed in claim 5, is particularly advantageous for minimizing disruption of the force flow in the tube and reducing the notch effect. These recesses (7) can be produced using modern manufacturing processes such as laser cutting, plasma cutting, or precision punching. A key manufacturing step is the subsequent processing of the edges of the recesses (7), as defined in claim 8. Deburring, slight chamfering, or rounding of the edges eliminates sharp notches, which increases the fatigue strength of the support under the alternating loads of everyday construction site use and minimizes the risk of injury during handling.

[0019] To compensate for the reduction in cross-sectional area caused by the cutouts (7) and still meet the high load-bearing capacity requirements of EN 1065, a high-strength steel is preferably used for the outer tube (1). The combination of a high-strength material and intelligent perforation enables maximum weight savings while maintaining full safety and functionality. The dimensions of the cutouts are optimized as described in claim 6. For example, the total opening area can range from 5% to 25% of the shell area, and the minimum web width between adjacent cutouts must not fall below a predetermined value to achieve a noticeable weight reduction without unduly compromising structural integrity. Second embodiment (perforated outer and inner tube)

[0020] In a further advantageous embodiment of the invention, as claimed in claim 2, not only the outer tube (1) but also the inner tube (2) is provided with weight-reducing recesses. These additional recesses in the inner tube (2) are clearly distinguishable in their shape, size, and arrangement from the standard, round fixing holes for the locking pin and serve exclusively to save material and weight.

[0021] The technical challenge in perforating the inner tube (2) differs from that of the outer tube (1). While the outer tube (1) is primarily subjected to buckling resistance along its entire free length, the inner tube (2) is exposed to high axial compressive stress. The design of the perforations in the inner tube (2) must therefore pay particular attention to avoiding excessive weakening of the areas around the fixing holes and the contact zone with the adjusting nut (6). To prevent combined weakening, the perforation patterns of the inner and outer tubes are advantageously offset from each other such that a flush overlap of the recesses is avoided in the extended state, as claimed in claim 7.

[0022] The optimization of the entire system is ideally carried out using FEA, as described in claim 10. The virtual model is subjected to the load scenarios prescribed in EN 1065, such as the flexural buckling test, in order to demonstrate maximum weight reduction while ensuring local and global stability. List of reference symbols 1 outer pipe 2 inner tube 3 Footplate 4 Head plate 5 external threads 6 adjusting nuts 7 cutouts for weight reduction QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited non-patent literature

[0000] Standard DIN EN 1065:1999-01

[0001]

Claims

[1] Telescopic construction support, especially for use in formwork construction in accordance with standard EN 1065, comprising: a) a hollow outer tube (1) with a lower end connected to a base plate (3); b) a hollow inner tube (2) which is telescopically guided in the outer tube (1) and can be locked at various extension lengths relative to it and has an upper end which is connected to a head plate (4); and c) a height adjustment device, typically comprising an external thread (5) arranged on the outer tube (1) and an adjusting nut (6) running thereon, characterized by , that d) the outer tube (1) has in its wall a plurality of recesses (7) serving to reduce weight, which are arranged in at least two helical paths offset around the longitudinal axis of the tube (1) in such a way that no continuous weakening line extending in the axial direction is formed. [2] Construction support according to claim 1, characterized by , that in addition the inner tube (2) has a plurality of recesses in its wall serving to reduce weight, which are different from the fixing holes provided for coarse height adjustment by means of a locking pin. [3] Construction support according to claim 1 or 2, characterized by , that the recesses (7) have a geometric shape suitable for minimizing stress concentrations, in particular being elliptical, circular, oblong with rounded ends or polygonal with rounded corners. [4] Construction support according to one of claims 1 to 3, characterized by , that the helical paths are distributed essentially uniformly around the circumference of the respective tube (1, 2). [5] Construction support according to claim 3 or 4, characterized by, that the recesses (7) are elliptical in shape, with their longitudinal axis being oriented essentially in the circumferential direction of the tube (1, 2). [6] Construction support according to one of the preceding claims, characterized by , that the total area of ​​the recesses (7) constitutes between 5% and 25% of the surface area of ​​the perforated pipe section and / or that the minimum web width between two adjacent recesses does not fall below a predetermined value. [7] Construction support according to claim 2, characterized by , that the patterns of the recesses in the inner tube (2) and in the outer tube (1) are offset from each other in such a way that an alignment of the recesses is avoided when the support is extended. [8] Building support according to one of the preceding claims, characterized by , that the edges of the recesses (7) are deburred, chamfered or rounded to reduce the notch effect and increase fatigue strength. [9] Building support according to one of the preceding claims, characterized by , that the outer tube (1) and / or the inner tube (2) are made of a high-strength steel in order to ensure a high load-bearing capacity despite the reduction of material through the cutouts (7). [10] Construction support according to one of the preceding claims, characterized by , that the total area, shape and arrangement of the recesses (7) are dimensioned and optimized using a numerical simulation method, in particular finite element analysis (FEA), such that the support column demonstrably meets the load-bearing capacity and safety requirements of standard EN 1065, in particular with regard to buckling stability.

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