RU2725445C1 - Input device for thin-walled pipes rolling, intended for use in multi-grooved automatic mill - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to rolling production and can be used as input wire for hot-rolling mill of thin-wall pipes at pipe rolling mill with multi-grooved automatic mill. Pipe rolling device comprises horizontally two rolling rollers to form a caliber, each having a groove and flanges having an inner edge on the side of the groove and an outer edge spaced from the groove, as well as mandrel and lower input lead intended for pipe direction and having cross-section the shape of chute with vertical walls. Vertical walls are made stepped so that high part of walls is located directly in front of rolls, and facing the surface of adjacent flanges edge of said high part of each wall is made with curvilinear profile, repeating profile of said flanges, and is located in relation to them with a gap, wherein facing each other surface of high part of each wall, which is inner side of wall, is flush with inner edge of adjacent flanges and is made with height of not more than height of caliber. In particular case of the invention implementation, the high part of the walls is made by the wiring walls extension using the shaped parts, each of which is fixed on the side part of the corresponding wiring wall by the bolt joint, wherein shaped part width in direction of roll split plane is selected within 200–300 mm.

EFFECT: higher quality of thin-wall pipes, reliability of the device due to stability of roll calibers, safety of rolling tool due to reduction or exclusion of peak loads on the motor, which drives rolls.

1 cl, 3 dwg

Description

The invention relates to the field of rolling production and can be used as input wiring multi-strand automatic mill.

A technical problem in the technical field is the search for means to prevent lateral ovalization of the end sections of thin-walled pipes (when the ratio of pipe diameter to wall thickness is more than 25), which occurs due to the flow of metal and leads to a violation of the rolling regime, and therefore, to a decrease in pipe quality. When rolling a pipe in an automatic mill, the multi-strand wiring design does not provide a tight roll gauge, and under load, the technological gap between the rolls, taken 5 mm, increases to 7-8 mm. Given the loss of stability of the rear ends of thin-walled pipes due to the lack of supporting factors in the form of pipe metal or a technological tool, the pipe metal flows into the increased gap between the rolls, which is the reason for the negative consequences.

The prior art device for rolling pipes used in high-quality mills, having rolling rolls equipped with streams, and input wiring for orienting the workpieces entering the streams of various profiles (A.A. Korolev. Rolling mills. - M .: Mashgiz. 1958 , p. 171-173).

Using this device does not solve the indicated technical problem. Thus, a decrease in the stiffness of the end section of thin-walled pipes causes its transverse ovalization and during rolling of pipes does not exclude the appearance of defects, such as longitudinal flaws and folds. As a result, an incorrect (oval) cross section of the end section of the pipes leads to the flow of metal between the flanges of the rolls with the further appearance of folds, the presence of which complicates the subsequent rolling operations on the tube rolling unit.

As the closest analogue, a device was selected for rolling pipes on an automatic multi-grooved mill, including rolling rolls having horizontal streams and flanges, as well as a mandrel and wiring in the form of a tray with a groove for guiding a replaceable mandrel and a tube stock along a semicircular groove, width which is 20% larger than the diameter of the rolled pipe and includes the width of the flanges (F.A. Danilov, A.Z. Gleiberg, V.G. Balakin. Hot rolling and pressing of pipes. - M .: Metallurgy. 1972., p. 205, 206).

The use of this device for thin-walled pipes causes the loss of stability of the end of the pipe during rolling due to a decrease in the rigidity of the end section of the pipe. As a result of this phenomenon, the end section takes an elliptical shape, and the cross section of the pipe expands in the flange region. This causes a subsequent flow of metal into the gap between the flanges of the rolls. With further movement in the rolls of the deformed pipe section, the formation of a transverse fold occurs, the presence of which prevents the quality of the rolling process. At the same time, other defects are formed, such as local thickening of the pipe wall, flaws at the end sections of the pipe, causing more intensive wear of the rolling tool and leading to damage to the surface of the stream and mandrel during the second passage of the pipe into the rolls of the automatic mill. In addition, the subsequent rolling of pipes having at the ends of the thickening from the formation of folds leads to the appearance of peak loads on the engine, which drives the rolls.

The proposed technical solution solves the problem of improving the quality of rolling thin-walled pipes in an automatic mill with multi-wiring while providing a technical result:

- the exception of the end defects of the pipes, manifested in the form of folds and longitudinal flaws;

- improving the reliability of the device by eliminating the flow of metal between the flanges of the rolls, reducing wear and damage to the rolls.

The proposed input device for rolling pipes includes horizontally mounted two rolling rolls with the formation of a caliber, each of which is made with a stream and flanges having an inner edge on the side of the stream and an outer edge spaced from the stream, as well as a mandrel and lower input wiring for guiding the pipe and having a cross-sectional shape of a gutter with vertical walls; new in the device is that the vertical walls are stepped so that the high part of the walls is located directly in front of the rollers, and the edge of the indicated high part of each wall facing the surface of adjacent flanges is made with a curved profile that repeats the profile of these flanges, and is located with a gap moreover, facing each other the surface of the high part of each wall, which is the inner side of the wall, is flush with the inner edge of adjacent flanges and is made with a height of not more than the height of the caliber.

In the particular case of the invention, the high part of the walls is made by expanding the walls of the wiring using shaped parts, each of which is fixed to the side of the corresponding wall of the wiring with a bolt connection, and the width of the shaped part in the direction of the plane of the rolls is selected within 200-300 mm.

The invention is illustrated as follows.

The vertical walls of the wiring are stepped with a high part located directly in front of the rolls and flush with the inner edge of the flanges, which allows to limit the lateral deformation of the end section of the pipe due to the loss of its stability and to prevent the flow (advance) of the deformable metal of the pipe wall into the area between the flanges of the rolls.

For convenience of presentation of the essence of the invention, the high part of each wall is hereinafter referred to as the working wall.

So, in the conditions of the existing production of hot-rolled thin-walled pipes on an automatic multi-grooved mill, it is advisable to carry out the working walls by building up the walls of the existing wiring. It is possible, for example, to install fittings made on the existing wiring walls by turning forgings or rolled products. Moreover, the shape of each such part ensures its installation on existing wiring walls with the formation of a high part of each wall having a flat vertical surface representing the inner side of the high part of the wall.

In addition, the implementation of the edges of the working wall with a curved profile facing the flanges of the rolls and repeating their shape, implies a gap of 10 mm between the specified wall edge and the flanges. This gap value is selected based on the ability of the rolls to perform their function without risk of touching the working walls as a result of the runout of the rolls.

Thus, the implementation of the walls of the input wiring stepwise with the location of their high part in front of the rolls with the possibility of bending around the section of the flanges of the rolls due to the presence of a curved part of the walls is a prerequisite for preventing defects in the end section of the pipe due to the flow of metal pipe between the flanges of the rolls with further negative consequences for rolling, about which was discussed above. Prevention of metal flow into the area between the flanges of the rolls with a high degree of reliability and accuracy is possible with an optimal height of the working walls, selected based on the caliber of the rolls. In addition, the height of the working walls depends on the presence of the top wiring in automatic multi-grooved mills, for this reason the maximum height of the stepped wall is limited by the height of the caliber of the rolls.

Eliminating the formation of folds and flaws, further rolling of the pipe leads to an increase in the quality of the pipes, as the rear ends of the pipes are devoid of the above disadvantages. In addition, during subsequent rolling of pipes without folds, peak loads on the engine are reduced or eliminated, while maintaining reliable operation of the device.

The input device for rolling thin-walled pipes is illustrated by drawings, which depict:

- figure 1 is a front view of the device;

- figure 2 is a view of the device in cross section;

- figure 3 is a view of the device in cross section with an image of the end section of the pipe.

The input device for rolling thin-walled pipes used as part of an automatic multi-grooved mill includes rolling rolls 1 located on horizontally mounted axes, having streams 2 and flanges 3, as well as a mandrel 4, input wiring 5 made in cross section in the form of a groove with walls, having a stepped profile with a high part of the walls located directly in front of the rolls 1.

The walls of the wiring 5 are expanded to form a high part of the walls by installing shaped parts 6 on each wall, each of which is made with a seat 7, which is interfaced with the corresponding surfaces of the wiring 5, also with curved edges 8 that face the flanges 3. This surface shaped parts 6, facing each other, are the inner side of the high part of the vertical walls of the wiring 5, located flush with the inner edge of the flanges 3 of the rolls 1. The shaped part 6 is made so that its height does not extend beyond the border of the caliber of the rolls,

As indicated above, each shaped part 6 is made by machining forgings or rolled products from steel 45. To install the shaped part 6 on the existing vertical walls of the wire groove 5, a bolted connection made with a proppant (not shown) is used.

The curved edges 8 of the shaped part 6 can form a shape close to the pointed one, as shown by the dotted line in figure 2, so that the edges 8 of the curved shape go as far as possible into the space between the flanges 3 of the rolls 1, literally to the plane of the rolls connector 1. This design reception is necessary to prevent the flow of metal between the rolls.

The gaps between the curved edge 8 of the high part of the walls 6 of the wiring 5 are selected 10 mm to ensure the functioning of the device and prevent the flow of metal between the rollers.

When using input wiring for rolling thin-walled pipes (with a diameter to wall ratio of more than 25), the height of the walls on the inside is selected based on the maximum height of the roll caliber.

In the initial stage of rolling thin-walled pipes, the input wiring 5 perform the traditional function of directing the billet pipe 9 into the streams 3 of the rolling rolls 1, as well as loading and unloading the mandrel 4. Moreover, in the final stage of rolling for each passage of the pipe, the stepwise shape of the walls of the wire 5 prevents metal penetration, when an increased gap is formed between the flanges 3 of the rolls 1, which eliminates the formation of transverse folds, longitudinal cracks and tears. In addition, due to the presence of a high portion 6 of the walls of the wiring 5, the initial billet of the pipe 9, entering the stream 2 of the rolls 1, is deformed and moves in the rolling direction due to their rotation, while maintaining a stable size.

As the rear free end of the thin-walled pipe 9 approaches a distance of about 0.05 of the length of the rolled pipe from the deformation region under the action of rolling forces, the cross section of the free end of the pipe loses its transverse stability, expanding until it touches the surface of the high part of the walls 6 and forming a cross section 10 having based on a rounded rectangle, as shown in figure 3, which under the action of streams 2 rolls 1 and mandrel 4 with further advancement of the pipe 9 turns into a circular cross section, eliminating the penetration of the deformable metal of the pipe into the flange region 3 and preventing the formation of wrinkles and flaws at the end sections of thin-walled pipes.

The use of the present invention leads to an increase in the quality of thin-walled pipes devoid of the above defects, improves the reliability of the device due to the stability of the caliber of the rolls, the safety of the rolling tool, and also by reducing or eliminating peak loads on the engine, which drives the rolling rolls.

Claims (2)

1. A device for rolling pipes in caliber, containing two horizontally mounted rolling rolls forming a gauge, each of which is made with a stream and flanges having an inner edge on the side of the stream and an outer edge spaced from the stream, a mandrel and a lower input wiring, intended for direction pipes and having a cross-sectional shape of a gutter with vertical walls, characterized in that the vertical walls of the wiring are made stepped with the location of the high part of the walls directly in front of the rolls, while the edge of the specified high part of each wall facing the surface of the adjacent roll flanges is made with a curved profile repeating the profile of these flanges, and is positioned with respect to them with a gap, with the facing surfaces of the high part of each wall being the inner sides, located flush with the inner edge of the adjacent flanges of the rolls and made not higher than the height of the caliber. 2. The device according to claim 1, characterized in that the high part of the walls is formed by expanding the walls of the wiring by means of shaped parts, each of which is fixed to the side of the corresponding wall of the wiring by bolt connection, and the width of the shaped part in the direction of the plane of the rolls connector is 200-300 mm

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