Method for manufacturing a louver for a throttling and shut-off device

Abstract

Method for producing a lamella (10) with a lens-shaped streamlined profile, for forming a louver-like throttling and shut-off device, in which a one-piece sheet is formed into a hollow profile and closed along a joint seam (18), characterized in that the joint seam (18) is formed by butt-welding two edges of the sheet together, that the hollow profile in the state in which the joint seam (18) is closed is a slotted tube (20') having a round cross-section that differs from the streamlined profile of the lamella, and that a welded tube (20) formed by closing the slotted tube (20') is deformed in at least one further forming step to the profile of the lamella (10).

Description

[0001] The invention relates to a method for manufacturing a lamella with a lens-shaped streamlined profile, for forming a louver-like throttling and shut-off device, in which a one-piece sheet is formed into a hollow profile and closed along a joint seam.

[0002] Louvers of this type are used, for example, in ventilation technology to form so-called louvered dampers. Such a damper has several louvers arranged parallel to each other, which can be rotated synchronously around their respective longitudinal axes. In the closed position, the ends of the louvers' lens-shaped profiles abut each other, so that together they form a substantially closed barrier. Seals are usually arranged on the edges of the louvers that correspond to the ends of the lens-shaped profiles, sealing the gaps between the individual louvers. When the louvers are rotated 90° each from the closed position, the lens-shaped profiles lie parallel to each other and extend in a direction perpendicular to the plane in which the multiple louvers are arranged.There are relatively large gaps between the individual lamellae, through which a medium (air) can flow, whereby the streamlined profiles of the lamella achieve low flow resistance and suppress noise formation.

[0003] In some well-known louvered dampers of this type, the louvers are formed from extruded profiles made of plastic or aluminum. However, these dampers either have low temperature resistance and are therefore unsuitable for applications such as fire protection systems, or the production of the louvers as extruded metal profiles is very complex and therefore relatively expensive.

[0004] In DE 100 08 099 C23, a method of the type mentioned above is described, in which the lamella is formed by forming a single-piece sheet. The joining seam is formed by a joining fold located in one of the convexly curved outer surfaces of the hollow profile, and in which the edges of the sheet are bent over several times so that they interlock in a form-fitting manner.

[0005] However, this process is relatively complex and time-consuming and always carries the risk that the joining seam will not form properly, resulting in a flow-technically unfavorable disturbance in the surface of the lamella.

[0006] In DE 10 2004 046 687 B3 a method for closing a slotted tube with a circular cross-section is described, in which the opposing edges of the slotted tube are pressed together with two tools complementary to the outer contour of the slotted tube and then welded.

[0007] The object of the invention is to provide a method that enables the simple and rational production of lamellae with a flow-optimized profile.

[0008] This problem is solved according to the invention by forming the joint seam by butt-welding two edges of the sheet metal. The closing of the sheet metal at the joint seam occurs in a state where the sheet metal forms a preform, which, although it has a hollow profile, does not yet have the final profile of the lamellae. Specifically, the preform is a slotted tube, as is also used in the production of welded tubes. Conventional and proven techniques can then be used to produce the slotted tube and to close the joint seam to form a welded tube. In particular, the welded tube can also be produced in a large length, or the maximum length possible due to the process, and then cut to the desired length of the lamellae.

[0009] To obtain the lamella with the desired streamlined profile, one or more forming steps can follow, in which the circumferential wall of the preform is deformed, for example, with pressing tools attacking from the outside and possibly also from the inside, or possibly also with rolling tools.

[0010] The joint is barely visible on the finished lamella and does not create any disturbance where the flowing medium could be disrupted.

[0011] Advantageous embodiments of the invention are specified in the dependent claims.

[0012] The following section explains an exemplary embodiment in more detail with reference to the drawing.

[0013] They show: Fig. 1 a cross-sectional view of a lamella produced according to the inventive method, Fig. 2 a cross-section of a slotted tube that forms a preform for the lamella; Fig. 3 the preform after Fig. 2 with closed joint; Fig. 4 a schematic sketch of a continuous process for the production of the slotted tube according to Fig. 2 in the form of an endless strand and for the formation of welded pipes according to Fig. 3 from this strand; and Fig. 5, Fig. 6, Fig. 7 to Fig. 8 further steps in the transformation of a welded tube into the lamella according to Fig. 1.

[0014] In Fig. Figure 1 shows a cross-section of a lamella 10 which has an approximately lenticular streamlined profile and together with other similar lamellae 10', which are in Fig. 1. A shut-off device, indicated only by a dash, forms a shut-off device that can, for example, be installed in a flow channel and serves to control the flow of a medium in this channel, for example from right to left. Fig. 1, to throttle or shut off. The lamella 10 has two approximately symmetrical, convexly curved side walls 12, which are attached to the in Fig. 1. The upper and lower edges of the lamella converge at a point. A groove 14 is formed in each edge of the lamella 10, running longitudinally along the lamella, perpendicular to the plane of the drawing. Fig. 1 runs and is bounded on one side by a nose 16. The openings of the grooves 14 are each slightly inclined to one side, so that the profile of the lamella 10 is not perfectly mirror-symmetrical overall, but exhibits point symmetry.

[0015] The grooves 14 are designed to accommodate sealing profiles not shown. In the Fig. In the locking position of the shut-off device shown in Figure 1, the lugs 16 of the lamella 10 rest against the sealing profiles of the lamellae 10' (which are also not shown), while conversely, the lugs of the lamellae 10' rest against the sealing profiles in the grooves 14 of the lamella 10. When the lamellae 10, 10' are removed from the position shown in Figure 1, the lugs 16 of the lamellae 10 rest against the sealing profiles of the lamellae 10' (which are not shown). Fig. Position 1 shown, extending around their respective central axis (which is in Fig. 1 perpendicular to the plane of the drawing) e.g. rotated counterclockwise, the noses 16 and the grooves 14 move apart, and the lamellae each pivot into an open position in which they can be surrounded by the medium and, due to their streamlined profile, offer only slight resistance to this flow.

[0016] The lamella 10 is formed by a single sheet of metal which is closed along a welded joint 18 to form a hollow profile. The edges of the sheet are butt-welded together at the joint 18.

[0017] In the example shown, the joint 18 is located at the base of one of the grooves 14. This has the advantage that the joint 18 is not only practically invisible, but is also located at a point where the sheet metal is stiffened by the profile of the groove 14, so that the joint is exposed to minimal mechanical stress. In the open position of the barrier element, the joint is therefore not located in an area exposed to airflow, and thus any irregularities in the joint 18 do not increase the flow resistance of the lamellae. Furthermore, the joint is protected against corrosion, e.g., from moisture in the airflow, by the sealing profile arranged in the groove.

[0018] A method for producing the lamella 10 according to Fig. 1. Now, based on the Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7 to Fig. 8 will be explained.

[0019] Fig. Figure 2 shows a cross-section of a cylindrical slotted tube 20', which forms a preform for the lamella 10. The edges of the sheet metal are butted against each other at the upper apex of the slotted tube and together form a narrow slot 18'. To close the slotted tube 20' into a closed tube, the edges of the sheet metal are butted against each other and aligned, or lightly pressed against each other and welded together, for example by laser welding, so that the welded joint 18 is created at the location of the slot 18' and the slotted tube is closed to form a welded tube 20, as shown in Figure 2. Fig. 3 is shown.

[0020] Fig. Figure 4 schematically illustrates a process for the continuous production of the welded tubes 20 according to Fig. 3.

[0021] An endless path of an initially flat sheet 22 is continuously drawn from left to right in the direction of arrow A. Fig. 4 transported and formed in a known manner by means of forming rollers not shown into the slotted tube 20', which then moves past a stationary welding head 24, for example a laser welding head, and into the welded tube 20 according to Fig. 3 is closed. The continuous strand of the welded tube 20 is then divided into sections that have the desired length of the lamellae 10 and form preforms for the individual lamellae 10. Alternatively, other welding techniques can be used instead of laser welding.

[0022] Fig. Figure 5 illustrates a further forming step in which the beads 14 are formed in the preform, i.e., the cut section of the welded tube 20. For this purpose, the welded tube is clamped in a forming tool such that the weld seam 18 faces one of two diametrically opposed embossing tools for the beads 14 (not shown). The embossing tools then press the beads 14 into the sheet metal, while the sheet metal inside the tube is supported by a counter-support that forms matrices for the contours of the beads 14 on the inside of the tube.

[0023] Fig. Figure 6 illustrates a further forming step in which the tube 20 is compressed into a tube with an elongated cross-section in the direction perpendicular to the line on which the beads 14 lie, by applying external pressure to the tube walls. An expandable internal forming tool (not shown), adapted to the contours of the beads 14, is then inserted into the resulting enlarged space between them. By expanding the internal forming tool, the cross-section of the tube 20 is further stretched, so that the tube 20 assumes the lenticular cross-section of the subsequent lamella 10, as shown in Figure 6. Fig. 7 is shown.

[0024] Fig. Figure 8 shows a final forming step in which the setting tools (not shown) are inserted into the grooves 14 and then rotated clockwise about their respective longitudinal axes, as indicated by arrows B in Fig. 8 is specified. This distorts the overall cross-section of the tube, resulting in the point-symmetric profile of the lamella 10, as also shown in Fig. 1 is shown.

[0025] The lamellae 10 are then closed off at the ends by end caps, in which the axes of rotation or bearings are also located, in which the lamellae 10, 10' of the shut-off device can be rotated about their respective longitudinal axis.

Claims

[1] Method for producing a lamella (10) with a lens-shaped streamlined profile, for forming a louver-like throttling and shut-off device, in which a one-piece sheet is formed into a hollow profile and closed along a joint seam (18), characterized by , that the joining seam (18) is formed by butt-welding two edges of the sheet together, that the hollow profile in the state in which the joining seam (18) is closed is a slotted tube (20') having a round cross-section that differs from the streamlined profile of the lamella, and that a welded tube (20) formed by closing the slotted tube (20') is formed in at least one further forming step to the profile of the lamella (10). [2] Method according to claim 1, wherein the slotted tube (20') has a circular cross-section. [3] Method according to claim 1 or 2, wherein two opposing beads (14) are formed in the welded tube (20), one of which is formed at the location of the joining seam (18). [4] Method according to claim 3, wherein the tube (20) is compressed in the direction perpendicular to the connecting line between the beads (14) to produce a lenticular cross-section. [5] Method according to claim 3 or 4, wherein parts of the wall of the tube (20) in which the beads (14) are located are spread from the inside. [6] Method according to claim 4 or 5, wherein the tube (20) formed into a lens-shaped cross-section is grasped in the area of ​​the beads (14) and twisted in such a way that the opening directions of the beads (14) deviate in the same direction of rotation from the direction of the connecting line between these beads. [7] Method according to one of the preceding claims, wherein the closing of the joining seam (18) is carried out in a continuous welding process on an endless strand of the hollow profile and the strand is then divided into sections of the length of the lamella (10). [8] Lamella (10) for a louver-like throttling and shut-off device, with a lens-shaped streamlined profile formed from a single sheet and shot along a joint seam (18), characterized by , that the joining seam (18) is a weld seam where the edges of the sheet are butt-welded together. [9] Lamella according to claim 8, with grooves (14) formed in the tapered ends of the lenticular streamline profile, wherein the joining seam (18) lies in one of the grooves (14).

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