RU2056227C1 - Method for separating pipes into annular billets - Google Patents

Abstract

FIELD: plastic working of metal. SUBSTANCE: method involves providing rotation of pipe 1; acting upon annular portion 3 of pipe 1 by rolls 2 and 4 from inner and outer pipe surfaces, with annular pipe portion having predetermined width and radial forces Pin and Pout applied to pipe surfaces being equal and directed one toward the other. At the initial moment rollers 4 and 2 are moved one toward the other till plastic deformation of billet is obtained. Rollers 4 and 2 are then radially moved in synchronism from pipe axis, with motion pitch of rollers being of predetermined ratio. EFFECT: increased quality of annular billets by reduced distortion of ring shape in the process of separating annular billets and reduced consumption of metal by decreased working allowance. 1 dwg

Description

 The invention relates to the processing of metals by pressure and can be used in mechanical engineering for the separation of pipes into rings, in particular in the bearing industry in the manufacture of ring billets from pipes for subsequent rolling or turning of bearing rings.

A known method of separating pipes into annular blanks, including feeding the pipe into the separation zone, rolling and separating the annular blank by radially moving the roller from the side of the inner surface in the pipe section of a given width [1]
When separating the rings by a known method, the ring profile and pipe profile are distorted, which reduces the quality of the products. This phenomenon occurs because when a local radial force is exerted from the inside on a section equal to the width of the detachable ring, before the pipe breaks at the place of the cut on the pipe’s inner surface, a so-called elongation is formed as a result of plastic deformation.

 At the same time, an influx is formed on the outer surface of the pipe at the end in the place of the cut, and on the outer surface of the detachable ring in the same zone, a sag. These defects are similar to defects that occur when cutting blanks on scissors or in a stamp.

There is also a method of separating annular billets from the pipe, including the rotation of the original pipe and the impact through the rollers from its inner and outer surfaces on the annular section of the pipe of a given width by radial forces equal in magnitude and directed one towards the other [2]
This method does not completely eliminate the distortion of the profile of the detachable rings, since the inconsistent movement of the outer and inner rollers leads to distortion of the round shape of the detachable ring, which reduces the quality of the products, causes an increased consumption of metal for subsequent machining and, in some cases, leads to marriage.

 The aim of the invention is to improve the quality of the workpieces by preventing distortion of the roundness of their shape.

где S_в, S_н величины перемещения соответственно внутреннего и наружного роликов, мм;
D_o, d_o соответственно наружный и внутренний диаметры трубы, мм;
D₁ текущий наружный диаметр деформируемого кольцевого участка трубы, мм.This is achieved by the fact that in the method of separating pipes into annular billets, including the rotation of the original pipe and the impact by means of rollers from its inner and outer surfaces on the annular section of the pipe of a given width with radial forces equal in magnitude and directed one towards the other, at the initial moment of application of radial forces the outer and inner rollers move one towards the other until the plastic deformation of the workpiece is achieved, and then both rollers synchronously move in the radial direction from si pipes, while the displacement of the inner and outer rollers are related by the ratio:
S _in = S _n •

where S _in , S _{n the} displacement values, respectively, of the inner and outer rollers, mm;
D _o , d _o respectively the outer and inner diameters of the pipe, mm;
D ₁ current outer diameter of the deformable annular pipe section, mm

 With this method of cutting the pipe into annular billets with bilateral radial deformation of the annular section, its tangential deformation also occurs, which contributes to an increase in the diametrical dimensions. In this case, at the initial moment of application of radial forces, the outer and inner rollers move one towards the other until the plastic deformation of the workpiece is achieved, and then both rollers synchronously move in the radial direction from the pipe axis, and the displacement values of the inner and outer rollers are connected by the indicated ratio.

 During deformation, compressive tangential stresses arise in this annular section, which cause radial shear stresses to appear in the mating plane of the pipe and the deformable annular section, which leads to a high-quality segment of the annular workpiece without the formation of sagging and sagging in the boundary zone of the shear plane both on the pipe and on separated ring blank.

 In addition, the synchronous movement of the inner and outer rollers, determined by the stated ratio, ensures the preservation of the round shape of the deformable ring billet throughout the process from the beginning of deformation to the separation of the ring billet.

 The drawing shows a diagram of a pipe cutting into ring blanks.

 The method of cutting pipes into ring blanks is as follows.

From the side of the inner surface of the pipe 1, the roller 2 exerts a radial force P _vn to the annular section 3 of the pipe of a given width b, and from the outer surface of the pipe, the roller 4 applies the force P _vn and the equal radial force P _n to the same annular portion 3. In this case, first, the rollers 2 and 4 are moved one towards the other until the plastic deformation of the annular section of the pipe 3 is reached, the moment of which is determined indirectly, and then, while maintaining the direction of movement of the roller 2 from the axis of the pipe to 4 they begin to move synchronously to the roller 2 in the radial direction also from the axis of the pipe, and the magnitudes of their movements are related by the indicated ratio, i.e. the amount of movement of the inner roller S _in depends on the amount of movement of the outer roller S _n and the ratio between the original and current dimensions of the detachable ring.

As a result of radial deformation, the annular section 3 tends to elongate in the tangential direction, in the radial plane of the conjugation of the pipe 1 and the deformable annular section 3 from the tangential compressive stresses σ _sr occurring in the detachable ring, the resulting shear stress component σ _cp directed to the periphery of section 3 is created.

Similarly, in the rest of the pipe 1, tensile stresses occur in the same plane, creating the resulting component shear stress directed to the pipe axis. Multidirectional resulting stresses (shear stresses σ _av ) in two pipe elements conjugated along the separation plane ensure separation of the annular workpiece from the pipe.

 The interconnected movement of the inner and outer rollers ensures the preservation of the round shape of the detachable annular workpiece throughout the deformation.

 PRI me R. The initial billet was a hot-rolled pipe with a diameter of 72.4 mm and a wall thickness of 8.8 mm from ShKh15 steel. Outside and inside the rotating pipe, a section with a width of 20 mm was exposed to the outer and inner rollers in the radial direction when moving them one towards the other until plastic deformation was achieved. At this moment, by switching the movement mechanism, the outer roller begins to be moved in the same direction from the axis of the pipe, depending on the amount of movement of the inner roller and the initial and current dimensions of the detachable annular workpiece.

 As a result of shear stresses, a ring 20 mm high with an outer diameter of 80.9 mm and a wall thickness of 7.5 mm was separated from the pipe. The deviations in the dimensions of the separated ring were ± 0.15 mm in diameter and wall thickness, while when separating the rings according to the known prototype method, the deviations in dimensions reached ± 0.25 mm in diameter and ± 0.15 mm in wall thickness. The resulting product is a workpiece for subsequent manufacturing by machining the outer rings of the bearing 208 with the minimum required allowances of 0.9 mm in outer diameter and 1.4 mm in inner diameter.

 Using the method of separation of pipes provides an increase in the quality of annular blanks by reducing distortion in the shape of the detachable ring both around the perimeter (maintaining a circular shape of the ring) and in cross section. In addition, the use of the method provides metal savings of up to 15% by reducing the allowance for subsequent processing due to slight distortion of the shape of the ring.

Claims (1)

METHOD FOR DIVIDING PIPES TO RING Billets, including the rotation of the original pipe and the impact by means of rollers from its inner and outer surfaces onto the annular section of the pipe of a given width by radial forces equal in magnitude and directed one towards the other, characterized in that the external moment of application of radial forces and the inner rollers move one towards the other until the plastic deformation of the workpiece is achieved, and then both rollers synchronously move in the radial direction from the axis tr loss, while the displacement of the inner and outer rollers are related by the ratio

where S _in , S _n - the displacement, respectively, of the inner and outer rollers, mm;
D _o , d _o - respectively, the outer and inner diameters of the pipe, mm;
D ₁ - current outer diameter of the deformable annular pipe section, mm