SU774736A1 - Method and roll for producing finned tubes - Google Patents

Description

between the offset and previous edges, which allows a thicker disk to be inserted between them. Possessing durability and rigidity, as well as in connection with the other direction of the axial forces acting on it, this disk not only does not bend itself, but also supports the thin disks in front of it, reducing their bending. Thus, the use of a rolling offset method with a rib offset allows to obtain a pipe with a rib's pitch smaller than the thickness of the disc, carried out its shift, and thereby expand the range of sizes of rolled tubes in the direction of decreasing rib spacing and increasing the fin ratio. reni over 15.

FIG. 1 and in FIG. Figure 2 shows the rib offset and pin crimping pattern; in fig. 3 - scanning of rolled ribs and their sequence of transition from caliber to caliber.

In the output part of the cylindrical section of the roll behind the last of the edge-forming thin disks 1, a disk 2 is installed, which has a greater thickness (FIG. 1). The entrance to the narrow groove between the ribs with its profile part, the disk 2 shifts the edge 3 towards the pipe outlets until it takes the position of the edge 4. At the same time, it compresses the cavity of the suction located under the edge. The top of the disk 2 is smoothly matched to the sides with a large radius of rounding and polished to ensure displacement of the rib without disrupting the integrity of the metal and preventing sunsets and cracks.

The edge 3, when displaced by its disk 2, can be bent to the position of the edge 5. To prevent this from happening, disk b is installed behind disk 2, width is O; silt which is less than the width of the depression between the edges of the rolled pipe. Its purpose is only a sub-surface. —Lite the top of the rolled rib, but not to deform either the ribs or the base of the pipe.

The increased resistance of the biasing discs 2 is provided not only by their greater thickness, but also by changing the direction of the forces acting on it. So, if, with the known rolling method, the axial force P from the rib to the disk is directed toward the exit of the pipe, in the proposed method this force is counteracted by the axial force P from the displaceable rib directed in the opposite direction.

When the edge of the disk 2 is displaced, the distance between adjacent edges 4 and 7 increases, but at the next turn of the pipe disk 2 enters between the next two edges 7 and 8 and shifts edge 7, the distance between edges 4 and 7 decreases and the pitch

recovered or increased slightly due to some stretching of the base.

When rolling on a three-roll mill, the wheels on three rolls can be displaced with the same width. In this case, the edge will be displaced only by the displacing disk of the first one as the roll rolls.

Depending on the plasticity of the materials being rolled, the fin can be shifted gradually by disks of different widths, as shown in FIG. 2. The numbers I, N and (l designate the sequence number of the roll during rolling, the arrows indicate the direction of rotation of the rolls and the movement of the pipe fins (Fig. 3).

It is also possible to install not one, but two or more displacing discs on a roller bed.

An example of an embodiment of the invention is the rolling technology of bimetallic pipes (aluminum steel) with a finning ratio of 20 protruding ribs of 15 mm and a pitch of 2.5 mm. Rolling is carried out on a three-roll mill of cross-helical rolling with an angle of rotation of the rolls to the axis of the workpiece on. Roll speed 700 rpm. Vlok consists of a drive shaft on which 30 disks are fixed.

Edge-forming discs have a hub thickness of H 2.3iO, 05 mm, an outer diameter D of 116 to 128 mm, a cusp angle of ci from 3 to 2 ° 15, a profile width at apex B from 1.3 to 1.5 mm, a radius of rounding g from 0.4 to O, 6 mm.

The bias disk has the following dimensions:, 2 ± 0.05 mm, mm,,, 1 mm, mm and produces an edge displacement of 0.6-0.7 mm along the base.

The dimensions of the supporting disk 6 are as follows:, 3 ± 0.05 mm, mm, оС 2 ° 15,, 4 mm,, 4 mm. The dimensions of the original blanks: aluminum pipe (outer diameter, wall thickness) - 3 mm, steel pipe - mm.

Pipes rolled by the above technology do not have wets under the ribs; in the pipe, the pipe is tightly seated on the inner one; the pressing force on samples with a length of 100 mm varies from 1,500 to 3,500 kg.

The method of rolling with offset ribs provides pipes with a finning ratio higher than 15, as a result of which it becomes possible to increase the performance of heat exchangers, reducing their metal consumption and cost. Mastering the production of pipes with a finning ratio of 20 only at the Tallinn Machine-Building Plant will provide an annual economic effect of 240 thousand rubles, and in the entire industry of chemical and petroleum engineering for air-cooled apparatuses - over 3 million rubles.

The application of the method is also advisable when rolling tubes with a finning ratio of less than 15, since it allows one to simply and reliably eliminate the weft under the fins and increase the durability of the rolling tool.

Testing the method and the roll under production conditions at the Tallinn Machine-Building Plant showed the possibility of stable pipe rolling with a finning ratio of 20, and compared to rolling the same pipes in a known manner without using shifting discs, the tool consumption was reduced by 8 times, respectively, reduced by simple rolling equipment.

Claims (2)

1. A method for manufacturing ribbed tubes by cross-helical rolling by successive formation of a rib on the pipe billet, which is aimed at increasing the finning coefficient of the pipes, eliminating the weft under the ribs and increasing the durability of the rolls, the ribs are subsequently deformed into axial direction offset relative to the cylindrical base of the finned tube in the direction of the last of the rolls. 2. A roller for carrying out the method according to claim 1, comprising a set of variable profile disks forming a conical and cylindrical portions, characterized in that at least one disk of the cylindrical portion is 1.2-2 times wider than its adjacent in the direction of the conical section of the disk. Sources of) Ormatia taken into account in the examination 1.Cherpillo E.P. and others. Production of high-ribbed pipes for air-cooled apparatuses. - Chemical and petroleum engineering, № 2, 1973, p. 24-25.x 2. USSR author's certificate 5 No. 217344, cl. B 21 B 3/00, 1965.