RU2238808C1 - Blank rolling method - Google Patents

Abstract

FIELD: manufacture of rolled products, in particular, methods for rolling of blanks with increased stretch extent.

SUBSTANCE: method involves rolling blanks by means of pair of rolls rotating in opposite directions; providing deflection of vectors of circumferential speed of rolls from rolling axis in plane of said axis combined with turning of blank around rolling axis; providing alternate rolling process with intervals between reduction processes at relative reciprocation movement of rolls and blank rotation axes along axis of rolling resulting in formation of deformation cone on blank. Rolling process is performed with the use of rolls of variable radius, said rolls defining round pass, with angle of deflection of circumferential speed vector of each roll from rolling axis being regulated by mathematical dependence taking into account such parameters, as angle of turning of blank around longitudinal axis, roll shaft spacing, rolling radius of rolls, and length of deformation cone.

EFFECT: increased efficiency of step-by-step rolling process and elimination of employment of special tilting devices synchronized with rolling stand drive.

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Description

The invention relates to rolling production, mainly to methods for rolling billets with large hoods.

A known method of cold rolling pipes [1], in which the sleeve mounted on the mandrel is pressed with two work rolls. In this case, the axis of the rolls together with the stand are reciprocating along the axis of rolling, and the roll-back motion is reported to the rolls. After each double stroke of the stand between the rolls and the workpiece, a gap is formed. At this time, the workpiece is fed along the rolling axis and its pitching is 90 degrees along with the mandrel.

The disadvantages of this method are: the need to use for turning the workpiece special overturning devices synchronized with the drive of the movement of the working stand, complicating the design of the mill.

Closest to the proposed solution in terms of technical nature and the achieved effect is the rolling method [2], carried out by a pair of rolls rotating in different directions when the vectors of the peripheral speeds of the rolls deviate from the axis of rolling in the plane of this axis. That is, the axis of the rolls are rotated relative to each other in horizontal planes. In this method, which is used in continuous groups of stands of longitudinal rolling to exclude the operation of turning the workpiece exiting the rolls by special tilters or using alternating horizontal and vertical rolling stands, the workpiece leaving the work rolls is rotated by the rollers simultaneously with its deformation.

However, with this rolling method, the billet is rotated at the exit of the rolls. At the entrance to the rolls, the workpiece remains in the same position. This does not allow the use of this method for step rolling, where before each rolling cycle it is necessary to turn the workpiece along the entire length of the transition zone from the original workpiece to the finished profile, called the deformation cone.

The task of the invention is to eliminate the operation of tilting the workpiece with a special device synchronized with the rolling stand, which allows to simplify the design of the mill stepping rolling, to increase the reliability of its operation and thereby increase the productivity of stepping rolling.

The problem is achieved in that in the known method of rolling billets, comprising compressing the workpiece with a pair of rolls rotating in opposite directions with the deviation of the vectors of the peripheral speeds of the rolls from the axis of rolling and turning the workpiece around the axis of rolling, according to the invention, the compression of the workpiece, alternating with pauses between reductions, with a relative reciprocating movement of the axis of rotation of the rolls and the workpiece along the axis of rolling with the formation of a deformation cone on the workpiece is carried out in the rolls radius forming a round gauge, and the angle of deviation of the peripheral speed vectors of each of the rolls from the rolling axis is set equal to

,

,

where φ _K is the angle of rotation of the workpiece around the longitudinal axis; D ₀ - the distance between the axes of the rolls; R _K is the rolling radius of the rolls; L is the length of the deformation cone.

The implementation of compression in round gauges on rolls of variable radius allows the resulting round conical billet (deformation cone) to rotate the rolls to rotate along its entire length around the axis of rolling. In the next rolling cycle, after a pause, the workpiece with a deformation cone rotated around the rolling axis by a certain angle will be set in the rolls. To rotate the workpiece by the required angle φ _K, the deviation angle of the vectors of peripheral speeds of each roll from the rolling axis is set equal

.

.

Thus, when applying the proposed rolling method, the need for the use of special devices for tilting the workpiece, synchronized with the drive of the rolling stand, is eliminated. This greatly simplifies the design of the mill, increases the reliability of its operation and thereby the productivity of the rolling process.

The proposed rolling method is illustrated in FIGS. 1 and 2, where rolling rolls are shown with a blank pressed therein in an arbitrary position of the rolling cycle, in plan and on the side of the resulting finished profile, respectively; figure 3 shows a plan view of the rolling rolls with the workpiece at the end of compression.

The method is as follows. A pair of rolls 1 with a distance between the axes D ₀ rotates in different directions. The vectors of peripheral speeds of each of the rolls V ^B and V ^{H are} deviated from the rolling axis in the plane of this XY (Fig. 1, 2) axis by an angle γ. In each rolling cycle, a workpiece 2 with a deformation cone rolled out on it is defined in the rolls. Compression of the workpiece begins at the beginning of T.A. The workpiece progressively moves relative to the axis of rotation of the rolls in the direction of the axial components of the vectors of the peripheral speeds of the rolls V ^B , V ^H. At the same time, it rotates along the entire length around the axis of rolling in the direction of the component rotating the workpiece V $\genfrac{}{}{0ex}{}{\text{B}}{\text{y}}$ , V $\genfrac{}{}{0ex}{}{\text{H}}{\text{y}}$ vectors of peripheral roll speeds V ^B , V ^H (figure 2). During compression during one rolling cycle, an arbitrary point on the workpiece moves along the ABC line (Figs. 1, 2). In this case, the rotation of the workpiece by an angle dφ (Fig. 2) is accompanied by rolling out the generatrix of the deformation cone onto an elementary segment. The projection of this elementary segment onto the ZY plane perpendicular to the rolling axis is

where R _K is the rolling radius of the rolls in an arbitrary deformation zone.

The compression of the workpiece ends at the end of the deformation cone t.S. At this point, the workpiece is rotated through an angle φ _K. The projection length of the generatrix of the deformation cone onto the ZY plane perpendicular to the rolling axis is

The length of the deformation cone at the end of the rolling cycle is L (Fig. 3), then the angle of deviation of the vectors of the peripheral speed of each of the rolls from the rolling axis, which ensures the workpiece is turned over by the rolling angle φ _K , will be equal to

.

.

Thus, at the beginning of the next rolling cycle, the compression of the deformation cone already rotated around the rolling axis begins. Each cross section of the deformation cone is rotated relative to its position in the previous rolling cycle by an angle φ _K. The proposed rolling method eliminates the need for special workpiece turning devices that are synchronized with the rolling mill drive. This simplifies the design of the mill, increases the reliability of its operation and, ultimately, the productivity of the rolling process.

The proposed method of step rolling was tested on a designed and manufactured pilot two-roll mill. The studies were carried out when rolling the initial circle with a diameter of 40 mm into a circle with a diameter of 20 mm. The center distance on the pilot mill is 180 mm. A round caliber was made on rolls of variable radius. The design of the experimental mill allows you to adjust the angle of the deviation of the vectors of peripheral speeds of each of the rolls from the axis of rolling.

Rolls, rotating in opposite directions during compression of the workpiece, formed a deformation cone with a length of approximately 230 mm. In the experiment, the angle of deviation of the circumferential velocity vectors of each of the rolls from the rolling axis γ varied from 0 to 5 degrees, while the optimum pitching angle φ _K equal to 85 ... 95 degrees corresponded to the value γ = 2.5 ... 3 degrees. During compression, the rotation of the workpiece occurred along the entire length.

The experiment showed that when the peripheral speeds of the rolls deviate from the rolling axis by the calculated angle γ, after each rolling cycle, the workpiece is turned around the rolling axis by the required angle γ. This eliminates the need for a canting device.

Thus, when applying the proposed method, simplification of the mill design is achieved, increasing the reliability of its operation, which leads to an increase in the productivity of the step rolling process.

The inventive method of step rolling allows you to get varietal profiles of circular cross section, including pipes.

Sources of information

1. Verderevsky V.A., Gleiberg A.Z., Nikitin A.S. Pipe rolling mills. - M.: Metallurgy, 1983.

2. USSR author's certificate No. 1036108, cl. B 21 B 1/02, 1983.

Claims (1)

A method of rolling blanks, comprising compressing the blank with a pair of rolls rotating in opposite directions with a deviation of the vectors of the peripheral speeds of the rolls from the axis of rolling and turning the blank around the axis of rolling, characterized in that the blank is alternated with pauses during relative reciprocating movement of the axes of rotation of the rolls and billets along the rolling axis with the formation of a deformation cone on the billet are carried out in rolls of variable radius forming a round gauge, and the angle of deviation of the vectors zhnoy rate of each of the rolls from the rolling axis is set to

where φ _K is the angle of rotation of the workpiece around the longitudinal axis; D ₀ - the distance between the axes of the rolls; R _K - rolling radius; L is the length of the deformation cone.

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