Method and manufacturing apparatus for the production of a pipe

Abstract

Method for manufacturing a tube (1) wherein the method comprises at least the following steps: In a first step (10) two outer edges (2) of a bent sheet are welded together, resulting in a weld seam running axially along a longitudinal axis (3) of the tube (1), In a second step (11) unevenness of the weld seam is leveled out by means of a rotary swaging process, wherein the sheet metal is bent in a preparatory step (12) before the first step (10) so that two outer edges (2) at least partially abut each other, wherein the second step (11) follows the first step (10) without a drawing process, and wherein the second step (11) includes at least one further shaping of the tube (1) in addition to compensating for the unevenness.

Description

[0001] The present invention relates to a method for manufacturing a pipe, a correspondingly manufactured pipe and a manufacturing device for manufacturing a pipe.

[0002] Precision tubes are hollow cylindrical tubes with a round or polygonal cross-section, characterized by high dimensional accuracy in terms of outer diameter, inner diameter or wall thickness.

[0003] In the prior art, such pipes are produced from sheet metal (see, e.g., DE 563 468 A). The sheet metal is bent until two outer edges are in contact, thus creating, for example, a closed circular shape. The butt joint is then welded. The weld seam creates irregularities in the form of local raised areas and / or depressions. To smooth these irregularities, protrusions, such as those resulting from the weld bead, are removed by planing or scraping (see, e.g., DE 27 58 138 C2 or DE 25 12 486 A1). The workpiece is then subjected to a drawing process, for example (see DE 521 446 A). Internal calibration can be performed, for instance, by drawing the workpiece over a mandrel.

[0004] A disadvantage of the drawing process as a cold forming process is the additional work step after welding and, moreover, the resulting reduction in the original wall thickness.

[0005] The object of the invention is therefore to provide a method and a manufacturing device for the production of a tube and in particular a precision tube, which represent an alternative to the prior art.

[0006] The invention solves the problem by providing a method for manufacturing a pipe.

[0007] The procedure includes at least the following steps: In a first step, two outer edges of a - preferably bent - sheet metal are welded together, resulting in a weld seam - preferably running axially along a longitudinal axis of the pipe. In a second step, irregularities in the weld seam are smoothed out using a rotary kneading process.

[0008] The second step follows directly from the first. The second step follows the first step without any pulling process.

[0009] In the inventive process, a welding process is carried out on a sheet metal part in a first step, as in the prior art. Welding results in a weld seam and thus also in undesirable irregularities in the pipe. These irregularities (this also applies to irregularities that may be created by the mechanical removal (i.e., grinding) of the weld bead) are, according to the invention, smoothed out in a second step by a rotary swaging process. Thus, no drawing process, as in the prior art, takes place. The second step therefore follows directly after the first step without a drawing process. Depending on the embodiment, other treatment steps—besides a drawing process—can also be carried out on the pipe before the second step. Alternatively, as already indicated, irregularities, e.g., protrusions, can be at least partially or mechanically removed before the second step.

[0010] The tube produced or manufactured is, in particular, a precision tube. In one embodiment, it is specifically a steel precision tube, so that the sheet metal used is also made of steel.

[0011] The invention thus also relates to a method for processing a tube produced by welding a sheet of metal. In this process, irregularities in the weld seam – e.g., after an intermediate mechanical machining step – are smoothed out by a rotary swaging process. The descriptions of the aforementioned manufacturing process therefore also apply accordingly to the method for processing a tube.

[0012] In one embodiment of the process, the irregularities consist of a weld bead and / or protrusions and / or depressions and / or structures resulting from a scraping process. In the second step, either undesirable structures resulting directly from the welding process are smoothed out, or irregularities resulting from post-treatment of the welded sheet metal are reduced. The scraping process is understood to mean any mechanical processing of the weld seam and its surrounding area. In this latter variant, the scraping process reduces some of the irregularities, and further surface smoothing is achieved in the second step through rotary swaging.

[0013] In a further embodiment of the process, a preparatory step takes place before the first step, in which the sheet metal is bent so that two outer edges at least partially touch each other.

[0014] In a further embodiment, the second step, in addition to leveling the irregularities, includes at least one further forming of the tube. In this embodiment, the tube is thus formed in the second step by the rotary swaging process, and the irregularities are also leveled out in this same rotary swaging process. In other words, leveling the irregularities becomes part of a further processing of the tube. This further processing of the tube includes, for example, creating a shape that deviates from a continuous cylinder or creating curves, etc.

[0015] The invention further solves the problem by means of a tube that has been produced using the method according to one of the preceding embodiments or by the following manufacturing device. As a result of a rotary swaging process, the tube is free of irregularities around a weld seam. In one embodiment, the tube has a shape that deviates from a cylinder with a round or polygonal cross-section as a result of the rotary swaging process.

[0016] In one embodiment of the tube, the sheet metal used as the starting material is strip steel.

[0017] The task is further solved by a manufacturing plant for producing a pipe using the method according to one of the preceding embodiments.

[0018] The production plant includes a welding device and a rotary kneading device. The rotary kneading device allows for the compensation of unevenness in a weld seam of the pipe produced by the welding device.

[0019] In one embodiment, the rotary kneading device also serves to change the shape of the tube. This is done in addition to leveling out the unevenness.

[0020] The welding device and the rotary kneading device can also be distributed across separate units. Accordingly, the invention can relate to only one rotary kneading device designed to perform the rotary kneading process for leveling out unevenness.

[0021] In detail, there are numerous possibilities for designing and further developing the inventive method, the inventive tube, and the inventive manufacturing device. Reference is made, on the one hand, to the claims subordinate to the independent claims, and on the other hand, to the following description of exemplary embodiments in conjunction with the drawing. The drawing shows: Fig. 1 a spatial representation of a pipe, Fig. 2 a flowchart of a design for the manufacture of a pipe and Fig. 3 A schematic representation of a manufacturing device for the production of a pipe.

[0022] The Fig. Figure 1 shows a tube 1 produced from a bent sheet of metal. The outer edges 2 of the sheet were brought into contact by a bending process. In a subsequent step, a weld seam was created along these outer edges 2 by a welding process, thus forming the actual tube shape. The weld seam runs longitudinally along the longitudinal axis 3. The irregularities formed during welding were subsequently smoothed by rotary swaging, resulting in a smooth surface.

[0023] It is indicated that, in the illustrated variant, the rotary swaging process creates a depression in the cylindrical shape of the tube 1. This clarifies that, in this variant, leveling the irregularities in the second step is part of a general shape change of the tube 1 through the rotary swaging process. The separate drawing step in the prior art is thus avoided according to the invention, and the leveling of irregularities achieved by the drawing process is incorporated into the further forming of the tube. The forming shown is a depression, but could also be a raised area or any other deviation from the cylindrical shape.

[0024] The Fig. Figure 2 illustrates the manufacturing process in an exemplary embodiment. In a preparatory step 12, a sheet metal part is bent so that two outer edges are in contact with each other. In the first step 10, the two outer edges are welded together. The irregularities caused by the weld are smoothed out and thus essentially eliminated in the second step 11 by a rotary swaging process. In particular, no drawing process takes place between the first step 10 and the second step 11. In one embodiment, the second step 11 can include a further forming of the tube (see, for example, the result of such an embodiment in Figure 2). Fig. 1) In a further embodiment - not shown - the weld bead is removed by a scraping process after the first step 11.

[0025] The one in Fig.The manufacturing device shown in Figure 3 (an alternative description is manufacturing plant) comprises a bending device 102, a welding device 100, and a rotary swaging device 101. The bending device 102 bends a sheet metal part, e.g., a steel sheet, into the desired shape so that two outer edges of the sheet are in contact with each other. The resulting butt joint is welded by the welding device 100, forming a weld seam. The irregularities of the weld seam and around it—or, in a further embodiment, the irregularities resulting from mechanical removal, e.g., of the weld bead—are smoothed out by the rotary swaging device 101. In one embodiment, the rotary swaging device 101 also allows for further forming of the tube produced from the sheet metal part.

[0026] In an alternative variant - not shown - only a rotary kneading device 101 is provided, which serves to compensate for unevenness of an already welded - and in one embodiment already machined with regard to the removal of the weld bead - pipe.

Claims

[1] Method for manufacturing a tube (1) wherein the method comprises at least the following steps: In a first step (10) two outer edges (2) of a bent sheet are welded together, resulting in a weld seam running axially along a longitudinal axis (3) of the tube (1), In a second step (11) unevenness of the weld seam is leveled out by means of a rotary swaging process, wherein the sheet metal is bent in a preparatory step (12) before the first step (10) so that two outer edges (2) at least partially abut each other, where the second step (11) follows the first step (10) without a drawing process, and wherein the second step (11) includes at least one further shaping of the tube (1) in addition to compensating for the unevenness. [2] Method according to claim 1, wherein the irregularities are a weld bead and / or elevations and / or depressions and / or structures resulting from a scraping process. [3] Manufacturing plant for the production of a pipe (1) using the method according to one of claims 1 to 2, wherein a welding device (100) and a rotary kneading device (101) are provided, and wherein the rotary kneading device (101) compensates for unevenness around a weld seam of the pipe (1) produced by the welding device (100).

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