RU20265U1 - ROLLER FOR FORMATION OF MICROGEOMETRY OF THE SURFACE OF A ROD AND A SMALL GRADE - Google Patents

Description

Roll for forming microgeometry of wire rod and small grade

The utility model relates to the processing of metals by pressure and can be used for hot rolling of wire rod and small grades.

It is known that when drawing, to reduce the coefficient of friction, the drawing force and the wear of the dies, a stable capture of the lubricant by the workpiece is necessary. This is possible with a sufficiently developed surface of the workpiece. It has been experimentally established that the microgeometry of the surface of wire rod and fine grades is optimal for the drawing process, having parameters of the average deviation of the profile Ra 4-15 μm and the average pitch of roughness S 15-30 μm.

The problems of the formation of a regulated surface roughness at the current moment are solved mainly in relation to cold rolling of the sheet. Analysis of most works shows that the most effective effect on the formation of the microrelief of rolled products is the state of the surface of the rolls: an increase in the roughness of the surface of the rolls leads to an increase in the roughness of the rolled products. The transfer of the roughness of the rolls to the strip can be represented in the form of a relation: where Л „and R are the arithmetic mean deviations of the roughness profiles

strip and roll surfaces, respectively.

This relation is considered, for example, in the book Meleshko V.I., Kachainova A.P., Mazur V.L. Progressive methods of rolling and finishing sheet steel, M., Metallurgy, 1980, p. 154-160, and lies in the range of 0.3-0.5.

However, the process of forming microroughnesses on a strip in the deformation zone for cold rolling of a sheet and hot rolling of round steel in calibration rolls is different. The roughness of the strip during hot rolling, in contrast to cold, is closer to the roughness of the rolling rolls; this is explained by various temperature-deformation conditions and the work of friction forces at the contact of the rolls and strip. In addition, the relationship between the roughness of the rolls and the strip, obviously, depends on the rolling speed and on the strength characteristics of the rolled metal.

MKIV2GS9 / 00 V 21 C 1/16

RJR.

The closest analogue to the claimed is a roll for the formation of microgeometry of the surface of the wire in preparation for drawing on A. with. USSR No. 820962 class MKI B 21 C 9/00, B 21 C 1/16, publ. 04/25/81, having a microrelief of caliber with a roughness height in the range of (0.006-0.02) d with a step equal to (0.0070.015) d, where d is the diameter of the wire rod. The disadvantage of these calibers is that the roughness of the wire rod will not be identical to the roughness of the rolling rolls.

The technical task of the utility model is to obtain rolled metal with the required parameters of surface microgeometry to improve the capture of grease by the workpiece during drawing by regulating the surface roughness of the gauges of the rolling rolls.

To solve this problem, we propose a roll for the formation of microgeometry of the surface of a wire rod and a fine grade, having a microrelief of caliber with a given roughness, in which the roughness has parameters of the average deviation of the profile R and the average step of roughness S, determined by

dependencies:

R 38.689xF ° + R + m;

5, 39.487xF- + S, + k,

F is the rolling speed, m / s;

n is (0, KO, 9);

w, k - coefficients depending on the ultimate strength cg, the initial workpiece

for rolling, moreover:

for cr, 700 MPa:

w - O, k 0; for 700 MNa cTi 1200 MPa:

m 1, k 2; for o-1200 MPa:

w 2 to 4.

The value of the exponent n lies in the range - (O, K 0.9) depending on the magnitude of the required surface roughness of the rolled metal with a constant diameter: the higher the parameters R and S., the larger the item. For example, wire rod with a diameter

the parameters Ld are 3.5–10 μm and S is 15–30 μm; therefore, for R 3.5 μm and 5.15 μm, the value of n is −0.1, and for „15 μm and S. 30 μm, the value of n is 0.9.

All of the above dependencies were obtained as a result of processing experimental data and are empirical.

In FIG. 1 shows the proposed roll, in FIG. 1 - section aa in figure 2. The roll has the shape of a cylinder 1 with annular recesses - gauges 2 on a cylindrical surface, having a circular arc in cross section.

The essence of the proposed technical solution lies in the fact that the caliber of the rolls of mills for hot rolling of round steel, designed for drawing, is performed with a roughness in the recesses 2, having parameters of the average deviation of the profile R and the average pitch of roughness S taking into account the final speed

rolling, the ultimate strength of the initial billet for rolling and the required microgeometry of the finished steel, and the roughness parameters of the roll calibers are determined by the dependencies:

R -38.689xF- + + w;

5, -39.487xF- ° + S, + k.

Industrial tests were carried out on a fine wire mill. Some data of experimental rolling of wire rod and small grades are given in the table.

Table

Thus, experimental studies have confirmed the acceptability of the proposed utility model for solving the problem and its advantages over the known.

When implementing the proposed utility model, it is first determined which microgeometry must be obtained on the wire rod, then, taking into account the final rolling speed and the ultimate strength of the initial billet, from the dependencies

R, 38.689xF- ° + + m;

S, 39,487xF- + S, + K

find the surface roughness parameters of the roll caliber.

An example of a specific implementation of the method

To improve the capture of grease by the workpiece for drawing, it is necessary to obtain a wire rod with a diameter of 6.5 mm from carbon steel, having:

MPa, with roughness parameters R 6 μm, S 20 μm. Rolled wire is produced in a fine mill at a final rolling speed of 50.8 m / s with compression in the last stand of 18%.

In order to obtain the required roughness on a wire rod, it is necessary that the gauges of the rolling rolls in the last mill stand have a microrelief with the following parameters:

R 38.689xF- ° + R + m;

5, 39.487xF- + 5-; + k.

The calculation results give:

R 38.689x50.8 ° + 6 ° + O - 8.4;

S 39.487x50.8 ° + 20 ° + O 20.8.

Thus, the gauges of the last mill stand are made with a microrelief, which they have; they have parameters R 8.4 microns and 5 20.8 microns.

Claims (1)

Roll for forming microgeometry of the surface of wire rod and small grades, having a microrelief of caliber with a given roughness, characterized in that the roughness has parameters of the average deviation of the profile Ra _in and the average pitch of roughness S _in , determined by the dependencies
Ra _in = 38.689 • V ^-0.4345 + Ra _k ⁿ + m;
S _in = 39.487 • V ^-0.1948 + S _k ⁿ + k,
where V is the rolling speed, m / s;
n = - (0.1-0.9);
m, k are the coefficients depending on the tensile strength σ _{b of the} initial billet for rolling, and
for σ _b <700 MPa:
m = 0, k = 0;
for 700 MPa ≤ σ _b <1200 MPa:
m = 1, k = 2;
for σ _b ≥ 1200 MPa:
m = 2, k = 4.