SU1547932A1 - Method of producing tubes with thickened ends - Google Patents

Abstract

The invention relates to the processing of metals by pressure and can be used in the manufacture of pipes with external bulges at the ends. The purpose of the invention is to improve the quality of products by eliminating corrugation. The tube blank is mounted on the mandrel and its front end is heated by a ring inductor. Then move the pipe until it stops its front end in the annular matrix with a conical working surface. At the same time, an axial force is applied to the rear end of the workpiece and the thickening is carried out, maintaining the ratio of the speeds of movement of the inductor and the rear end of the workpiece. Landing lead on a stepped mandrel with a gap between the workpiece and the mandrel. Local heating of the billet during the whole process is carried out at a site equal to the wall thickness of the billet. As a result of uniform deformation of the metal along the length and thickness of the pipe, corrugation is reduced, which improves the quality of the planted thickening. 1 hp f-ly, 2 ill.

Description

The invention relates to the processing of metals by pressure and can be used in the manufacture of pipes with external bulges at the ends.

The purpose of the invention is to improve the quality of products by eliminating corrugation.

FIG. 1 shows a scheme for implementing a method for producing a thickening at the end of a billet at the initial stage and a device for carrying it out; in fig. 2 - the same in the landing process.

The method is carried out as follows.

The preform pipe 1 slides onto the stepped mandrel 2 so that the end of the pipe goes to the mandrel stage with a diameter equal to the internal diameter of the pipe without a gap. The pipe end does not reach the support surface of the annular matrix 3 (FIG. 1). In this position, the end part of the pipe is heated to the forging temperature by an inductor 4, followed by placing the heated end into the annular matrix 3 and applying working pressure P through the clamping mechanism 5. After the specified thickness / wall is set, the rest of the pipe is set to the length the drawing (Fig. 2).

Both the initial heating and the subsequent sequential heating of the pipe are carried out at a site equal in length to the wall thickness of the preform. At the same time, the speed of movement of the inductor and the speed of movement of the rear (cold) end of the billet pipe are fixed, their ratio CK1 is determined at given parameters of wall thickness and pipe diameter, respectively, before and after disembarkation, i.e.

FT - 1

where So, Do and 5, D, respectively, are initial and after the landing of the wall thickness and pipe diameter.

sd

Ј

WITH

with y

The stop of the end of the pipe heated to the forging temperature is carried out into a conical matrix, the taper angle of which decreases with increasing degree of relative thinness of the pipe billet and is equal to a - - tg4Sn DQ. This creates favorable conditions for disembarking not only regarding the alignment of the process and eliminating the trimming operation, but also about the stress state across the pipe wall thickness (the maximum value of the axial stress component on the outer surface and the minimum on the inside). The landing of the thickenings is carried out with a gap between the tube and the mandrel, for which the latter is made with two cylindrical sections, between which there is a conical section with an angle of 45 ... 60 °, which provides the required gap size. In this case, a more uniform heating of the pipe wall is achieved due to the absence of intensive heat extraction by the stepped mandrel and the process energy consumption is reduced.

Example. A pipe with an outer diameter of 273 mm and a wall thickness of 24.0 mm, material steel 40XH2MASH, was used as the initial blank. The landing was carried out in two operations: the first landing, the second landing. The dimensions of the upset end after the first landing: outer diameter 308 mm, wall thickness 42.0 mm, length of the disembarked part 800 mm. Dimensions of the planted end pic, -

0

15

20

pressure and carried out the landing of the front part of the workpiece to a diameter of 300 mm. During the landing process, the inductor was not turned off and during this time the subsequent pipe section was heated, then the system of automatic tracking of the landing process was turned on. When the required length of the landed part was reached, the inductor was disconnected, the working pressure was released, the clamping mechanism released

0 pipe and it along the roller table was removed from the working zone of the landing vehicle. A new pipe was set and the cycle of operations was repeated. The second landing after replacing the inductor was carried out in the same sequence as the first one.

The use of the method of manufacturing pipes with thickened ends allows one to more accurately obtain the geometry of the thickened end of the pipe in a wide range of changes in the mechanical properties, diameter and wall thickness of the pipe due to specifically selected modes of the technological process.

0

Claims (2)

1. A method of manufacturing pipes with thickened ends, including the installation of a billet on a mandrel, local heating of the billet at a pre - forging temperature with an annular inductor moved along it At the second landing, the outer diameter is 30 and the free landing of the bulge at 370 mm, the wall thickness is 73 mm, the length of the planted part is 280 mm. The dimensions of the matrix at the first landing: the angle of the cone of the supporting surface is a tg4So JDn / # 4-241273, the inner diameter is 226 mm, the outer diameter is mm, the thickness is 35 to 120 mm. Material steel 40X. On the second landing, the outer diameter of the ring is 360 mm, the other dimensions are the same. Step mandrel: the diameter of the lead-in part of 226 mm, the diameter of the end part of 216 mm, the length of the transition cone from the end part to the feed part of 50 mm. The billet was heated by serial split ring inductors. The internal diameter of the inductor on the first landing is 310 mm, on the second 360 mm. 40 axial force to the rear end of the workpiece with the ratio of the speed of movement of the inductor to the speed of movement of the rear end of the workpiece, corresponding to the reciprocal of the degree of thickening, characterized in that the absence of its contact with the stop before the application of axial force to the rear end, and the landing of the thickening is performed on a stepped mandrel when placing the workpiece on the mandrel with a gap and focusing the front end of the workpiece into an annular matrix with a taper angle a of the working surface equal to The landing was carried out in the following modes: 45 tg4So Do, where So Do is the wall thickness and diameters. At the first landing, the inductor's power is 115-120 kW, the ratio of the speeds of the mobile beam Vr and the inductor Vu was j, - (308 / 42-1) / (273 / 24-1) 6.33 / 10.37 "0.61. Dust rate 6–8 mm / min. The working pressure of the landing Pp 50 23.0 MPa. At the second upset, the pipe on the mandrel of the end of the pipe did not reach the stop ring for a distance of 30-50 mm (Fig. 1). In this position, the end section was heated to forging temperature. Then the heated end was applied to the stop with the ring matrix (Fig. 2). Included working a meter of pipe before planting, while local heating of the workpiece to the forging temperature throughout the whole process is carried out at a site equal to the wall thickness of the workpiece. 2. A method according to claim 1, characterized in that the ratio of the speed of movement of the inductor Vv to the speed of movement of the rear end of the workpiece Vf is determined from the ratio 1L, DIS - 1 Ut - 1 where S, Z) is the wall thickness and pipe diameter after disembarkation. axial force to the rear end of the workpiece with the ratio of the speed of movement of the inductor to the speed of movement of the rear end of the workpiece, corresponding to the reciprocal of the degree of thickening, characterized in that the absence of its contact with the stop before the application of axial force to the rear end, and the landing of the thickening is performed on a stepped mandrel when placing the workpiece on the mandrel with a gap and focusing the front end of the workpiece into an annular matrix with a taper angle a of the working surface equal to tg4So Do, where So Do is the wall thickness and the diameter of the pipe before planting, while local heating of the workpiece to the forging temperature throughout the entire process is carried out in an area equal to the wall thickness of the workpiece. 2. A method according to claim 1, characterized in that the ratio of the speed of movement of the inductor Vv to the speed of movement of the rear end of the workpiece Vf is determined from the ratio 1L, DIS - 1 Ut - 1 where S, Z) is the wall thickness and pipe diameter after disembarkation. figure 1