SPACER ELEMENT

Abstract: The invention relates to a spacer for sandwich panels and sandwich elements for forming preferably a door element, a floor element or a wall element (2) consisting of at least two plates (4, 5) welded together at a predetermined distance from each other via at least one spacer (3). The spacer (3) is constituted by a cylindrical or cylinder-like pipe (6), which has been deformed in a repeated pattern in the form of depressions (7) along the length of the pipe (6), wherein the depressions (7) extend transverse to the pipe at optional angles to form bulges or lugs (8) projecting from the mantle surface of the pipe (6), which bulges or lugs constitute contact points with a small abutment or contact surface against adjacent plates (4, 5), in order to facilitate the welding operation.

Description: SPACER ELEMENT. The present invention relates to a new spacer for assembling sandwich panels and sandwich elements, preferably door elements, floor elements or wall elements, in the form of plane structure elements . Currently on the market there are different types of sandwich elements for a number of different fields of use, for example buildings, bridge structures, vehicle structures, air plane structures and so -on. In these structures different types of spacers have been used between the plates of polymer material forming a body of the sandwich element in question, for example completely covering polymer material with varying density or separate, longitudinal elements with varying different patterns with the plane plates incorporated in the sandwich element. This type of polymeric sandwich element in composite material assembled with the aid of gluing has the disadvantage that it is difficult to obtain a strong and temperature insensitive joint between the plates. Furthermore, difficulties arise with these elements when welding against adjacent, weldable, metal structures, since the sandwich elements are composed of different materials. Nor is it possible to continuously vary the volumetric efficiency, i.e. the distance between spacers and the size of the latter, in X-direction and in Y-direction. Besides, these sandwich elements are difficult to recycle because of different material composition. The Swedish patent no. SE 381 906 discloses a sandwich element having two external plates welded together on each side of a spacer in the form of a wire net. However, by using this solution it has not been possible to provide satisfactory welding joints because of the large abutment surface against the plates, and therefore it has not been possible to obtain an optimal product. It has also been proved to be difficult to obtain a large building height with this type of sandwich element and, furthermore, many welding operations have give rise to a local buckling around the welding [joints . The object of the present invention is to provide a new type of spacer m a sandwich structure, where the above mentioned disadvantages are eliminated and m which a satisfactory and optimal positional fixing is provided by welding the spacers at adjacent plates. The characterising features of the invention are stated m the accompanying claims. Thanks to the invention a sandwich structure has been provided which m an excellent manner fulfils its purpose and, moreover, is both inexpensive and easy to manufacture . As the spacer for the positional fixing of the sheet shaped plate elements incorporated m the sandwich element, a cylindrically shaped or cylinder like pipe is use according to the invention. The pipe has a plurality of transversely extending formations located at predetermined distances from each other m the longitudinal direction of the pipe and consisting of depressions at optional angles along the pipe. As a result, bulges or lugs projecting from the mantel surface of the pipe are formed and are intended to constitute contact points during welding. Also spacers w th other shapes may be used only they have such a design that contact surfaces against adjacent plates will be as small as possible to facilitate welding, which is one of the requirements m order to make the welding operation as favourable as possible . Before welding the spacers may have been put m a predetermined pattern m the intermediate space between the plates, wherein the plates thereafter have been pressed against the projecting bulges formed by the deformations of the spacer and been fixed to these by the welding operation, preferably by pressure welding. By the fact that the contact surfaces between the spacers formed m accordance with the invention and adjacent plates before welding are very small, a very strong joint between the spacers and plates is obtained. Thus, when using this type of spacers a very safe weld is achieved between the spacers and the plates, which m turn results in that the sandwich elements will have a large torque resistance and bending resistance and, furthermore, the structure will have a small weight m spite of its thickness and also a low relative density. Besides the low weight, the position and pattern of the welding points can be varied within one and the same element. Furthermore, by varying the wall thickness of the pipe forming the spacer and varying the flattening of the pipe it may be possible to achieve an optimal lug or bulge, which is formed m correspondence to the plate thickness of the covering or external layers As opposed to solid spacers it is possible to compress the spacer according to the invention m subsequent machining operations, such as drawing, edging, roll forming etc Finally, the spacers according to the invention enable the use of ultra high-tensile less formable metallic materials m the covering layers . The field of use for the sandwich element comprising spacers according to the present invention may be as a general structure element and is very vast. For example, it may be used for doorplates, platform plates for lorries, trains or the like or for walls and floors m various buildings. The diameter and wall thickness of the spacer pipes can be varied depending on the load the sandwich element is to be subjected to and also for individual sandwich element the dimensions of the spacers may be varied to make tne element uniformly strong or stiff. The invention is described m more detail below with the aid of a preferred embodiment with reference to the accompanying drawing, m which Fig. 1 shows a schematic perspective view obliquely from above of a sandwich element with two plates arranged at a predetermined distance from each other with a spacer according to the invention, Fig. 2 shows another view of the sandwich element with incorporated spacers shown in Fig. 1, Fig. 3 shows a side view of a spacer according to the invention incorporated m a sandwich element, Fig. 4 shows the spacer according to Fig. 3 m a view from above , Fig. 5 shows a perspective view of a sandwich element provided with spacers according to the invention m a view obliquely from below, Fig. 6 shows an alternative embodiment of the spacer according to the invention as seen m a side view, and Fig. 7 shows the spacer shown m Fig. 1 as seen m a perspective view. As is evident from the drawings these show a sandwich element 1 for forming of for example a door element, floor element or wall element 2, which m the preferred embodiment shown consists of two plates 4, 5 fixed by pressure welding at a predetermined distance from each other via the spacers 3. As the spacer 3 between the plates 4, 5 is used a cylindrical or cylinder-like pipe 6, which has been deformed m a repeated pattern in the form of depressions 7. The depressions 7 are arranged with a predetermined distance between adjacent depressions 7 along the longitudinal direction of the pipe 6 and they extend transverse the pipe 6 at optional angles to form bulges or lugs 8 projecting from the mantel surface of the pipe 6. The distance between the depressions 7 may be varied from case to case but are for most cases dependent on the current load situation. The bulges or lugs 8 are intended to facilitate the welding operation and form contact points at a small abutment or contact surface against the adjacent plates 4, 5. In the example shown the depressions 7 are situated at a predetermined distance from each other along the longitudinal direction of the pipe 6 and extend perpendicular to the pipe. According to this embodiment, the depressions 7 are made m such a manner that they flatten the cylindrical shape of the pipe 6, so that a number of pockets 9, preferably evenly spaced from each other, are formed and the degree of flattening corresponds to the size of the formed bulges or lugs 8. The wall thickness of the pipe 6 and the flattening for forming the depressions 7 are variable to form an optimal pressure lug or pressure bulge 8 m relation to the current plate thickness m the covering layers formed by the plates 4, 5. To fix the plates 4, 5 at the spacers 3, according to the invention preferably pressure welding is used and the spacers 3 are positioned between the plates 4, 5 m different patterns with mutually varying distances depending on the calculated load or deflection the sandwich element is intended to be subjected to. Thanks to the invention the spacers are also compressible m a controllable manner during the forming operation of the sandwich element. The spacers 3 may have a diameter and wall thickness, which correspond to the plate thickness and the load, or the deflection the element is intended to resist. As for instance appears m more detail from Fig. 5 the side edges of the sandwich element 1 may be formed with a groove 10 which is intended to co-operate and be connected with a tongue projecting from an adjacent element. Thus, the sandwich element 1 may take different shapes. For example it can be completely plane with open sides, completely plane with closed sides with the aid of for example m or on mounted U-profiles, formed with a groove and a tongue, so that a joint can be made when one element s placed for example at an angle of 90° or at other angles to another element. In Figures 6 and 7 there is shown an alternative embodiment of the spacer 3' , the pipe 6' of which is substantially the same as the first embodiment with depressions 7' arranged at a predetermined distance from each other along the longitudinal direction of the pipe 6' to form bulges or lugs 8' projecting on the mantel surface of the pipe 6', but which pipe 6 1 m addition has been provided with depressions 11 extending transverse across the pockets 9' . As a result a spacer 3 1 is obtained having two rows with bulges or lugs, namely 8' and 8' ' whereby the complete sandwich element achieves a better stiffness.

Claims: CLAIMS 1. A spacer for sandwich panels and sandwich elements for forming preferably a door element, a floor element or a wall element (2) consisting of at least two plates (4, 5) welded together at a predetermined distance from each other via at least one spacer (3), characterized in that the spacer (3) is constituted by a cylindrical or cylinder-like pipe (6), which has been deformed m a repeated pattern m the form of depressions (7, 7') along the length of the pipe (6, 6'), wherein the depressions (7, 7') extend transverse to the pipe at optional angles to form bulges or lugs (8, 8 1 , 8' ') projecting from the mantle surface of the pipe (6, 6') , which bulges or lugs constitute contact points having a small abutment or contact surface against adjacent plates (4, 5), in order to facilitate the welding operation. 2. A spacer according to claim 1, characterized in that the depressions (7) of the spacer (3) lie m the same plane perpendicular to the longitudinal directions of the pipe (6) and are substantially evenly spaced from one another. 3. A spacer according to claim 2, characterized in that the projection of the lugs (8) from the mantle surface of the pipe (6) is depending on the flattening of the cylindrical shape of the pipe (6) through the depressions (7) , wherein the pipe (6) as a result have pockets situated m series (9) . 4. A spacer according to claim 1, characterized in that the flattening and wall thickness of the pipe (6) forming the spacer (3) is variable to provide an optimal pressure lug or pressure bulge (8) corresponding to the plate thickness of the covering layers formed by the places of the sandwich elemen . 5. A spacer according to claim 1, characterized in that the spacer (3) is welded to the plates (4, 5) preferably by pressure welding. 6. A spacer according to claim 1, characterized in that the spacer (3) is placed between the plates (4, 5) in different patterns with mutually varying distances between the spacers depending on the calculated load or deflection the sandwich element (1) is intended to be subjected to. 7. A spacer according to claim 1, characterized in that the spacer (3) has a wall thickness and a diameter corresponding to the plate thickness and the current load on or deflection of the element (1) . 8. A spacer according to claim 1, characterized in that the spacer is controllably compressible during the forming operation of the sandwich element . 9. A spacer according to claim 1 or 3 , characterized in that the pockets (9') situated in series on the pipe (6') are provided with further depressions (11) situated in series along the length of the pipe (6') for forming a further row of bulges or lugs (8', 8' ') projecting from the mantle surface of the pipe (6) .

Inventors: CARLSSON LEIF, CARLSSON, LEIF
Applicants: AVESTA SHEFFIELD AB, CARLSSON LEIF, CARLSSON, LEIF
Application year: 2000
Main classification: E04C2
IPC codes: B32B3, E04C2