SU1409388A1 - Method of producing heat-exchanger tube - Google Patents

Abstract

The invention relates to the processing of metals by pressure (and can be used in the energy maneuver by creating tenloobmennyh apparatus. The goal is to reduce the consumption of the metal and increase technology. In the manufacture of tenlo exchange tube with internal fins, its core is made of sheet G1 width, paBHoii is the internal diameter of a smooth-wall tubular billet. Cuts are made on the edges of the strip not less than half its width, with the same pitch. Cuts on one edge are offset relative to the cut core half is placed inside blank 2. Then, successively moving from one core segment to another, the core is attached to the inner surface of the blank, at the same time rotating the non-curviline part of the core and the blank relative to each other. - Ply the longitudinal axis 3. In the manufacture of pipes with internal and external fins, attaching the core to the internal surface of the workpiece is combined with the attachment to its external poner of the spiral fin. At the same time, the inner and outer ribs are attached by crimping the inner rim and by welding the outer ribs, crimping the inner ribs and tension with fastening the ends of the outer ribs. 1 hp (}) - ly, 5 it.t. with s

Description

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The invention relates to the processing of metals by pressure and can be used in power engineering and the chemical industry for the manufacture of heat exchangers.

The purpose of the invention is to improve the manufacturability and reduce metal consumption.

FIG. 1 shows a core (with notches) made by the proposed method, before being placed in a tubular

the extrusion method used to manufacture cores or the tubes with internal fins is applicable only to relatively expensive highly plastic materials (copper, aluminum) and therefore the scope of application of such tubes is limited. In addition, the method allows the manufacture of steel tubes with internal fins, which significantly expands this area, ultimately leading to metal savings, preparation; in fig. 2 and FIG. 4 - options 10 as the finned tubes due to the development

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heat exchanger pipe manufactured according to the proposed method: with conditionally not shown part of the billet; in fig. 3 and FIG. 5 shows sections AA, BB and B-B in FIG. 2 and 4.

The method is carried out as follows.

The core 1 of the heat exchanger tube is made of a sheet strip with a width equal to the inner diameter of the smooth-wall tubular billet, for which cuts 20 are not less than half the width of the strips with equal pitch, with the cuts of one edge being offset by half the pitch of the other. The core 1 is placed inside the workpiece 2. Then, sequentially, the transition from one core segment to another is attached to the inner surface of the workpiece, while simultaneously rotating the unattached part of the core and the workpiece relative to each other around their common longitudinal axis 3.

Attaching the core to the inner surface of the workpiece is carried out in various ways: by crimping the workpiece, squeezing out the grooves on its outer surface to form protrusions on the inside, by welding or in another way ensuring the thermal contact of the core with the inner surface of the workpiece.

25

thirty

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heat transfer surfaces provide high intensity.

Pipes manufactured by the proposed method have a smaller internal fins surface (it is equal to twice the area of the diametral section of the pipe) in comparison with pipes having a continuous ribbed core (1.5-3 times). However, as shown by calculations supported by experiment, this is more than compensated for by the high intensity of heat exchange in the flow around single core segments of the pipe produced by the proposed method in comparison with the flow around a continuous longitudinal edge, which is associated with an increase in the intensity of heat exchange with a decrease in the length of the flow path due to a decrease in the thickness of the boundary layer.

An important advantage of the finned tubes manufactured by the proposed method is the possibility of mixing the fluid flowing in different intercostal channels. The absence of such mixing in pipes with internal fins, formed by a core with solid fins, can seriously impair the intensity of heat transfer when the pipe is unevenly heated (cooled) around the perimeter.

In the manufacture of pipes with internal and external fins, attaching the core to the inner surface of the workpiece is combined with attaching the spiral fins to its outer surface. In this case, various combinations of methods of attaching the inner and outer ribs are possible: crimping - inner and welding - outer, welding - inner and welding - outer, crimping - inner and tension with fastening the ends - outer, etc.

The proposed method allows, with a simple degree of mechanization, to produce heat exchanger tubes with internal and double-sided fins, which have a lower metal consumption compared to pipes made using both the prototype technology and the traditional technology of extruded solid pipes with internal fins. It should also be noted that

the extrusion method used to manufacture cores or the tubes with internal fins is applicable only to relatively expensive highly plastic materials (copper, aluminum) and therefore the scope of application of such tubes is limited. Furthermore, the method allows the manufacture of steel tubes with internal fins, which significantly expands this area, ultimately leading to savings in metal, since the finned tubes due to the development of

heat transfer surfaces provide high intensity.

Pipes manufactured by the proposed method have a smaller internal fins surface (it is equal to twice the area of the diametral section of the pipe) in comparison with pipes having a continuous ribbed core (1.5-3 times). However, as shown by calculations supported by experiment, this is more than compensated for by the high intensity of heat exchange in the flow around single core segments of the pipe produced by the proposed method in comparison with the flow around a continuous longitudinal edge, which is associated with an increase in the intensity of heat exchange with a decrease in the length of the flow path due to a decrease in the thickness of the boundary layer.

An important advantage of the finned tubes manufactured by the proposed method is the possibility of mixing the fluid flowing in different intercostal channels. The absence of such mixing in pipes with internal fins, formed by a core with solid fins, can seriously impair the intensity of heat transfer when the pipe is unevenly heated (cooled) around the perimeter.

The sequence of operations in the manufacture of finned tubes according to the proposed method allows simultaneously with the attachment of the core to the inner surface, the attachment of the outer spiral fin. The advantage of this method is the possibility of varying the degree of external fins over a wide range up to values unattainable in the method of forming the external ribs by extruding the workpiece from the body (as in the prototype) and of great practical interest. It is also significant that the outer edges in this case can be made steel, whereas in the method of the prototype both the workpiece and the ribs formed from its body should be from a highly plastic metal (copper, aluminum).

Example. From sheet metal (for example, steel) strip of thickness Y, equal to the required thickness of the internal ribs, and width L equal to the inner diameter dew of a smooth-walled cylindrical billet, with a negative tolerance ensuring free rotation of the strip inside the billet (for example, but suitable for fit) around the longitudinal axis make core. For this, both longitudinal edges of the strip are notched to not less than half the width of the strip (for example, the notch length is equal to b / 2 - | -th) with the same step S of the notches equal to the required length of an individual edge (for example, 5 ε „/ 2). In this case, the cuts of one edge are shifted along the longitudinal axis of the strip by an amount equal to S / 2 - half the pitch of the cuts. The length of the core is equal to the length of the pipe billet. The core 1 thus fabricated is completely placed inside the blank 2, and then proceeds to attach the core to the inner surface of the blank. To do this, for example, crimp the workpiece by running in its outer surface with rollers. The attachment can also be carried out in any other way that ensures the thermal contact of the edge of the core with the inner surface of the workpiece: by welding, squeezing depressions on the outer surface of the workpiece with the formation of protrusions on the inner surface fixing the core segments, etc. Attaching the core to the inner surface of the workpiece (X is segmented in segments, successively moving from one end of the pipe to the other. At the same time, the unattached part of the core and the workpiece are rotated relative to each other around their common longitudinal smallpox 3. The rotation of the unattached part of the core is impaired, for example, using the carrier covering this part inside the workpiece. The carrier driving is kinematically connected with the drive of the rollers compressing the pipe so that the longitudinal speed of movement along the pipe /

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1 bb

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five

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five

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The boundaries between the loose and attached parts of the core coincided with the longitudinal velocity of the carrier. Thus, as soon as the attachment of the core segments to the inner surface of the workpiece, the carrier releases new segments for attachment, thus allowing the unattached part of the core to rotate relative to the workpiece around the hypodal axis. When the unattached part of the core rotates relative to the workpiece, separate edges are formed by successively bending the attached core segments from the unattached part while attaching them to the inner surface of the workpiece.

Claims (2)

1. A method of manufacturing a heat exchange tube, comprising placing the core inside a smooth-walled tubular billet and fixing it to the inner surface of the billet, characterized in that, in order to improve processability and reduce metal consumption, the core is made from sheet material so that both edges of the strip are notched with the same tag of cuts and with the displacement of the cuts on one edge relative to the cuts of the other up to half of the tag, attaching the core to the inner surface of the workpiece is combined with the rotation and the unattached portion of the workpiece relative to each other around their common longitudinal axis and to the pri-) splenpe core to the inner surface is carried out sequentially from ODN01CH) end of the tube to the other. 2. A method according to claim 1, characterized in that the edges of the strip are notched not less than to n (; its widths are lov. B- B 2 / Aa Fy 5-6 Bb