SU1388132A1 - Method of manufacturing tubes - Google Patents

Abstract

The invention relates to the processing of metals by pressure and can be used in the manufacture of cold-formed pipes. The purpose of the invention is to increase productivity and improve the quality of pipes with smooth surfaces. The deformation of the pipe is carried out in a die at the mandrel, and one of these tool elements is reported to rotate. The rotating element of the tool has screw grooves on its surface. The axial speed of movement of the screw grooves is 2-10 times the axial speed of movement of the metal at the exit of the die. At the same time, due to the development of alternating deformation and an increase in the share of compressive stresses in the deformation zone, the plasticity of the metal increases and it becomes possible to manufacture pipes for large single compression with a smooth surface. To prevent the pipe from twisting onto the surface in contact with the stationary element of the tool, a grid of mutually perpendicular corrugations inclined to the axis of the pipe and at an angle of + 40-50 ° is rolled. 5 ill., 1 tab. (L with

Description

with oo

00

with y

The invention relates to the processing of metals by pressure and can be used in the manufacture of cold-deformable pipes.

The purpose of the invention is to increase productivity and improve the quality of pipes with smooth surfaces.

Figure 1 shows the diagram of the deformation zone; FIG. 2 is a section A-A in FIG. on fig.Z - section bb in figure 1; Fig, 4 is a section bb In figure 1; FIG. 5 shows the outer surface of the pipe before entering;

The method is carried out as follows.

The pipe 1 is put on the rod with the mandrel 2 and set by the feed mechanism to the fiber 3. Before the die 3, the pipe surface is corrugated in the device 4, the corrugations being applied as a grid of mutually perpendicular recesses inclined at an angle of ± 40-50 ° to the pipe axis .

The change in the cross-section of the workpiece during the passage of the hearth. The deformations are as follows.

At the first stage (Fig. 2), the billet enters the reducing zone of the -fillers, where it reduces its outer diameter. In this zone, the contact of the pipe with the mandrel does not occur. In the deformation zone on the mandrel (Fig. 3), the inner perimeter of the said section is divided into two characteristic areas. The section metal in section C is located opposite the groove cut on the mandrel and, under the action of radial forces, plastically flows into it, forming a rib. The metal in zone D is located opposite the protrusion of the mandrel separating two adjacent grooves, and, plastically deformed, moves in the axial direction. The number of sections C and D in the inner perimeter of the cross section of the pipe depends on the number of inserts of the screw thread of the mandrel — when they are single-pass cutting one at a time, two-start cutting — two each, and so on.

With further deformation, the position of zones C and D depends on the ratio of the metal feed rates VQ and the rotation of the mandrel. If the velocity of the metal at the exit from the deformation zone v f is equal to the axial component of the speed of movement of the grooves of the mandrel wS, where S is the groove pitch of the groove, then the ribs extruded on the pipe surface

slide along the grooves of the mandrel do not crush, and the type of the deformation zone in any section along the length of the die is such

as in fig.Z.

If the axial speed of movement of the grooves of the mandrel is 2-10 times higher than the speed of axial metal flow, the position of the grooves relative to the specified cross section of the pipe varies (Fig. 4). The extruded rib is opposite the protrusion of the mandrel and is smoothed as a result of plastic deformation. the pipe is squeezed out by a new rib in the groove of the mandrel. With the subsequent rotation of the mandrel, the position of the zones is again. varies, screw ribs are smoothed and re-drawn, etc.

Thus, with w, Vo / S, the process of extruding the ribs and smoothing them out for each cross section of the pipe proceeds continuously and is repeated many times while moving this section through the spinneret. As the degree of deformation increases, the metal hardens and its volume, flowing into the grooves of the mandrel, becomes less and less (Figure 4). As a result, in the calibration die calibrating, extrusion and smoothing of the ribs are completely stopped and the pipe exits also from the deformation zone with a smooth inner surface.

When passing through fiber 3, the mesh of corrugations 5 increases the frictional forces in the circumferential direction between the pipe and the die, compensating for the torque that arises between the pipe and mandrel. This prevents the pipe from twisting and improves its quality. The arrangement of the corrugations along the action of the greatest tangential stresses ensures their full smoothing in the process of deformation and obtaining smooth pipes with high surface quality. Such deformation leads to the cyclic softening of the metal, to a significant increase in the plastic properties, which allows one-time reduction and process efficiency to be improved. The choice of parameters for implementing the method is confirmed experimentally. The deformation of the pipes from alloy 157 is carried out. The mill allows pushing the metal through the fiber and rotating the mandrel with different speed ratios. The mandrel has a three-way screw thread with a screw line pitch S 5 mm. The depth of the grooves is 1.0 mm. The wire has an angle of working cone 16. The corrugations on the outer surface of the pipes are applied by longitudinal rolling in rollers. During the experiments, the ratio of the velocities V and U), the angle of inclination of the corrugations are changed. The conditions and results of the experiments are given in the table. It can be seen from the above data that the angular rotational speed, equal to (l VQ / S and corresponding to the prototype), is ensured by extruding a screw rib on the pipe surface and calibrating it when the metal moves through the die plate (test 1).

Any increase in the circumferential velocity of the movable element leads to the smth of a sprouting edge (experiments 2-14). However, if the rotational speed is less than 2 Vg / 5, then the rib edge is not fully complete and its trace remains on the surface of the pipe in the form of a spiral-like thickening of the pipe wall (experiment 2). At a rotational speed equal to the above, the metal flowed into the groove.

completely smoothed out and the surface of the pipe in contact with the movable element of the tool is smooth. However, with an increase in the circumferential velocity of the moving element, the velocities of relative slip between the tool and the pipe metal increase. This significantly increases the temperature of the deformation zone, which leads to the burning of lubricant and the formation of gaps and adhesions on the surface of the pipe in contact with the moving element. Experiments have established that the quality of the pipe surface decreases at the speed of rotation of the tool.

Q 5

0 5

0

five

five

0

10; Х УО / З (EXPERIENCE 6), This speed is taken as the limit.

A change in the orientation of the corrugations shows that the optimum angle of inclination is 4r40-5CP. With smaller and larger slopes, traces of corrugations remain on the pipe surface (experiments 11 and 13). In addition, at large corners of the corrugations, the adhesion to the surface of the die is reduced, which leads to pipe twisting (experiments 10, 13, 14).

The experiments performed show the possible and effective implementation of the method for corrugating the inner surface of a pipe and rotating filaments with helical grooves with a fixed mandrel.

Thus, the present invention, due to the indicated deformation conditions, allows one-time shrinking by 3-5 times, increasing productivity by 40-60% and ensuring high quality of the twisting surface of fibers.

Claims (1)

Invention Formula A method of manufacturing pipes that involves dragging a workpiece through a die on a mandrel, one of the tools being reported to rotate and one of them has screw grooves on the working surface, characterized in that, in order to increase productivity and improve the quality of pipes with smooth surfaces, the workpiece in contact with the stationary tool, pre-applied grid of mutually perpendicular corrugations at an angle of ± 40-50 to the axis of the tube, and the speed of axial movement of the grooves of the rotating tool is set 2-10 times more than the axial velocity of the tube at the outlet of the die is cast. Warming up pipes h Aa ugb 5 Yes The ripples of riffles Traces of corrugations and pipe twisting y /////// J // A FIG. 2 Figz Fy