SU1488041A1 - Method of rolling rounds - Google Patents

Abstract

The invention relates to rolling production, and specifically to the production of round profiles, mainly periodic reinforcing bars, on section rolling mills. The purpose of the invention is to increase the level of strength properties while saving metal by reducing residual stresses in finished steel. Before serving in pre-finishing and finishing calibers, vibrations are applied to the rolls, creating alternating bending. Vibration oscillations are delivered to peals from vibrators with an adjustable oscillation frequency, and the vibrators themselves are installed in the wiring. The optimal frequency is 0.9-1.1 frequencies of the first mode of shear oscillation of the roll. In comparison with the base object, the proposed method for rolling reinforcement profiles with a standard weight reduction ratio of 1 meter of m from 3.0 to 5.0% improves the mechanical properties of rolled products, the court increases the complex indicator of the overall strength of reinforcing bars by 10-18 % while reducing residual stresses in finished products and the best combination of strength and plastic properties. 1 ill., 1 tab.

Description

The invention relates to rolling production, in particular to the production of round profiles, mainly periodic reinforcing, at the section rolling mill.

The purpose of the invention is to increase the level of strength properties while saving metal by reducing residual stresses in finished steel.

The drawing shows the arrangement of mechanisms for implementing the method in the finishing line of the mill.

Before rolling the rolls in the pre-finishing and finishing calibers they are subjected to vibrational vibrations, creating an alternating bend. leads to the fact that in each elementary volume of the cross section of the roll the unevenness of deformation disappears, caused by the uneven distribution of the stretches over the section, i.e. the areas with the greatest stretch, where compressive stresses act, and those with the least, where tensile, stresses act, disappear.

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The magnitude of the stresses caused by the rolling process in the last passes is reduced and approaches before rolling in the finishing caliber to the level of stresses in the undeformed metal. As a result, the component of rolling stresses in the total residual stresses of the finished product decreases with and is determined only by the deformation conditions in the finishing caliber.

The imposition of peals before compression in the pre and clean calibrations of vibrations makes it difficult to correct induced lattice defects (increased amount of free dislocations, subgrain boundaries, etc.) obtained by rolling deformation (stretching 1.10-1.35) . This contributes to the fact that the recrystallization process is difficult and the number of lattice defects increases from passage to passage. The combination of the proposed rolling method with accelerated. After-formation cooling ensures a high complex of mechanical properties, thermally hardened steel and a minimum level of residual stresses. in the finished rental.

When the frequency of vibrations coincides with the natural frequency of shear oscillations, the amplitude of oscillations of the roll is maximum, i.e. maximum and deformation caused by alternating bending. At the same time, energy costs and the formation of vibrations are minimal.

Ilpii reduce the frequency of vibration less than 0.9 frequency of the first mode of shear oscillations of roll occurs

a sharp decrease in the amplitude of oscillations, leading to a decrease in the magnitude of the deformation caused by the sign

variable bending. This increases the proportion of stresses caused by the rolling process at the total residual stresses. The growth of residual stresses leads to a deterioration in the quality of products, expressed in a decrease in the level of service characteristics of the finished product.

. In addition, a decrease in the frequency of vibrations of less than. 0.9 the frequency of the first mode of shear oscillations of a roll leads to a sharp increase in the cost of energy used to generate vibrations, i.e. same effect achieves

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0

five

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five

one

with at greater power consumption, which is impractical.

Increasing the frequency of vibrations by more than 1.1 frequencies of the first mode of shear vibrations of the roll causes the frequency of vibrations to become close to or equal to the frequency of the second, third, and so on modes of shear vibrations of the roll, which leads to a decrease in amplitude at the same or greater power consumption, those. The rolls are smaller in deformation during alternating bending, and as a result - a deterioration in the quality of rolled finite sizes due to an increase in residual stresses.

Example. The method is carried out at rolling-rebar periodic profile No. 18 of 35GS steel melts with carbon equivalent of 0.60-0.70%, supplied from a continuous short section mill with a rolling end temperature of 1050 ° C.

The distance between the adjacent stands of the finishing group is 5 m. The cross-sectional area of the pre-finishing oval is 319 mm, the width of the oval is 28.2, the height is 14.5 MM; the cross-sectional area in front of the pre-oval is 374 mm, the oval width is 19.7 mm, and the height is 25.5 mm. The rolling speed in the pre-finishing stand was 12.71 m / s, and in the pre-finishing roll-out - 10.84 m / s.

The frequency of the first mode of shear oscillation of the roll between the finishing and pre-cleaning cells is 1.5 Hz, and between the pre-finishing and pre-finishing cells - 0.84 Hz.

Rolling in the last three cells is carried out with equal second volumes or with a slight tension. -Rolled delivered with guaranteed overall strength.

The quality control of the bars is carried out by comparing the total breaking strength with a complex measure of the overall strength.

For reinforcing bars No. 18 of 35GS class A-III steel, a complex indicator of the overall strength of Pg with a decrease in mass of 1 running. m by 3% is Pg 147.7 kH by 4% - P - 146.3 kN; by 5% - Р, 144,8 kN.

The results of rolling armature periodic profiles of the proposed method are shown in the table.

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In the last two interstates between the section mill, for implementing the modes of the proposed method, vibration lines 1 are installed. Each vibration line 1 contains an odd number of vibrators 2 connected via power supply means 3 to an overflow valve 4 connected to an energy carrier.

Vibrators 2 in one vibroprovodka relative to rolls are positioned so that two of them interact with the end parts of the rolls on one side, and the third vibrator is installed on the opposite side of the strip in the middle of two edge, and in the subsequent vibroprovodka vibrators have opposite orientation relative to the roll: from the side one central vibrator has two end valves, and where two vibrators are installed in the previous vibration system, one is installed - central.

Performing an odd number of vibrators and their orientation provides conditions for the creation of standing waves in peals. In this case, the two nodes are located in the roll x, and the antinodes are located at the locations of the vibrators.

Regulation of the required frequency. oscillations are produced by flap valves. After the front end of the roll has passed, the vibrators include vibrators: wave pulses affect the roll, creating alternating bending conditions.

After rolling one roll, the vibrators are turned off. Their re-activation is carried out after the passage of the front end of the next roll in the vibrating wiring.

In comparison with the base object, the proposed method when rolling rebar periodic profiles

with a standard weight reduction ratio of 1 p. m from 3 to 5% allows to increase the mechanical properties of rolled products by increasing the complex index of the overall strength of reinforcing bars by 10-18% while reducing residual stresses in the finished steel, with the best combination of strength and plastic properties can be obtained immediately

after rolling and accelerated post-deformation cooling.

Claims (1)

Invention Formula The method of rolling round cross-sectional profiles, mainly periodic reinforcing, including crimping rolls in pre-finishing and finishing passes in the oval-oval-gauge system, is a circle characterized in that, in order to save the strength properties while saving metal by reducing the residual stresses in the finished steel , before the pre-finishing and finishing passes, the roll is subjected to oscillations with a frequency of 0.9-1.1 frequencies of the first mode of shear vibrations of the roll.