SU737057A1 - Blanks for making heat-exchange tubes - Google Patents

Description

The invention relates to the production of heat exchange tubes with internal helical fins by the gilding method.

The well-known billet for the heat exchange tube, consisting of a cylindrical shell and a core with radially diverging BINT ribs, is twisted by 1PO spirals about its axis located inside the shell (1. Screw ribs impart a rotational motion to the heat exchange medium, which turbulenizes the flow fluid and improves the heat transfer properties of pipes.

Also known is a blank for the manufacture of heat exchange tubes, comprising a cylindrical shell with a core arranged in it with radial longitudinal ribs, the ends of which are made with bevels 2.

For the manufacture of screw ribs, the core is preliminarily closed along its axis with a P01 twisting force applied to the ends, for example, on twisting machines. Then, a sheath is put on it with a gap, and by joint reduction of the core and the Shell, a heat exchange tube is obtained with screw ribs on the inside.

A disadvantage of the known preform is that for forming helical ribs with certain helix spacings, the use of additional technological torsion of core ribs is required. This increases the labor intensity of manufacturing heat exchanger tubes.

The aim of the invention is to eliminate the twisting of the core and

10 receipt of pipes with screw anutrients / edges directly in the process of drawing.

To achieve this goal, the end bevels of the ribs are made asymmetric with respect to the radial axis of the rib.

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On; FIG. 1 shows the relative position of the shell and core before drawing; in fig. 2 - core before drawing; in fig. 3 - a variant of making the top of the rib, the top of the rib with one-sided full bevel; in fig. 4 - the same, the top of the rib with one-sided incomplete bevel; in fig. 5 - the same, the top of the rib with a two-sided bevel; in fig. 6 is a schematic of an engagement path consisting of a shell and a core; in fig. 7 is a section A-A in FIG. 6 (the cross-section of the pipe at the moment when the vertices of the ribs touch the inner surface of the shell); on .fig. 8 — node I in FIG. 7; in FIG. 9 is a cross section bb la fig.

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6 (cross-section of the finished pipe after drawing); in fig. 10 - core after dragging.

Heart 1, on the tops of the ribs 2 of which asymmetrical bosoms 3 are made, is placed in sheath 4 (fig. 1) before being drawn. In case of locomotion through the conical fiber 5 of the sheath 6 and the core / the degree of deformation is chosen so that, after deformation, the core 7 is obtained, in which the bevels 3 of the tops of the ribs 8 take a symmetrical shape (Fig. 6, 9). In this case, due to the initial displacement of the line of action of force P relative to the plane of symmetry (edges at angle y at the top of the edge., A normal A and tangential T forces appear in the deformation zone (Fig. 7, 8).

The force T leads to a torque M, the magnitude of which is the maximal x-metal at the entrance to the deformation zone and ra: zero at the exit from it. Under the action of torque, the straight longitudinal ribs (Fig. 2) of the bridge are formed by B, Screw | Vye edges (Fig. 10), and the free core of the core is out of translational motion in the post-rotational position. . After drawing 1, a pipe consisting of a core is obtained.

7c with screw. Edges: mi S and shells 6 {fig. 9).

By adjusting the shape of the vertex (Fig. 3-5), you can get a twist angle within

0.2-2 turns of one cross section relative to another, separated by a distance of 1 m. The presence of asymmetrical bevels on the tops of the edges of the core edges leads to the twisting of the edges directly during the drawing process, which increases the production rate of the heat exchanger tube with helical finning.

Formula of Invention

A billet for the manufacture of heat exchanging tubes with SCREWS and inner ribs, containing a cylindrical shell with a core placed in it with radial longitudinal ribs, the ends of which are made with bevels, characterized in that, in order to eliminate the operation of the core twisting and to obtain tubes with screw internal edges directly in the process of drawing, face bevels of the ribs, are asymmetrical relative to the radial axis of the edge.

Sources of information accepted in | Knowledge of the examination:

1. US Patent L 2960114,: Cl. 138-38, 1960.

2.Pa rent US number 3871407 ,.kl. 138-38, 1975.

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Claims (1)

Claim A workpiece for the manufacture of heat exchange tubes with screw inner ribs, comprising a cylindrical shell with a core placed therein, with radial longitudinal ribs, the ends of which are made with bevels, characterized in that, in order to exclude the operation of twisting the core and obtain pipes with screw inner ribs directly in In the process of drawing, end-bevels of the ribs are made asymmetric with respect to the radial axis of the ribs.