SU1437119A1 - Tool for periodic deformation of tubes - Google Patents

Abstract

The invention relates to the periodic rolling of pipes in HPT mills, specifically determining the shape of the ridge of a stream in relation to the generator of the mandrel of a curved shape. The aim of the invention is to increase the productivity of the mill with the lowest anisotropy of mechanical properties by ensuring the constant ratio of the absolute partial deformations of the diameter and the wall of the pipes along the length of the compression zone. The tool includes a swath with a stream having successively arranged reduction, reduction and calibration zones, and a mandrel. The geometrical parameters of the ridge and the generator of the mandrel are determined between themselves in all sections along the length of the reduction zone from the ratios given in the description. 2 Il. , 1 tab. F (L

Description

SAE

i The invention relates to the treatment of: metals by pressure, in particular to the pipe production, and concerns the shape of the working profiles of the tool, namely the crest of a stream on a roll and mandrel, for cold periodic rolling of pipes.

The aim of the invention is to increase the productivity of the mill at; the lowest anisotropy of mechanical properties I, due to the provision of the constant ratio of absolute partial I deformations in diameter and thickness i of the wall of rolled tubes.

. Fig. 1 shows the forming op-1 with a radius of curvature at an arbitrary 1 point y (x equal to R (lower 1 n curve), and a crest I forming a stream with a radius of curvature R. at U. Boundary points curvilinear forming mandrels and ridge I brook at the beginning and end of the reduction zone with length Igjjt are indicated for the largest sizes D I smallest sizes (r, j) and I Sizes. UK, R ,,, g ,, R correspond to m from the axis of the mandrel to the corresponding 1 tool points at the boundaries of the reduction zone.

 Figure 2 shows a longitudinal section of the sweep of the ridge creek 1, frame 2 in the process of periodic deformation of the pipe 3. The zones of the re-; dividing (with a length of 1p) -compression (IQ, calibration 1ts. Curvilinear generators, mandrels, (K) and ridge stream (x limited to the initial dfl, Pn and end d.

D.

diameters. Arbitrary points in identical cross-sections that are separated from each other by the distance xX are determined by the value of their diameters, D (x; +1)., D (xi + 1),

Calibrations obtained by selecting curves that provide an approximate (with an error) constant ratio of absolute partial reductions (but cannot ensure compliance with a given value of the ratio of these reductions due to specific curves) are applicable due to the unevenness of deformation generated by them and all the consequences of this, only with relatively small reduction in non-deformable steel grades and small pipe batches, as with the increase in the specified characteristics that determine the intensity of rolling

on the mill COD, the error increases.

The compression mode, obtained by fitting the curves, has a different magnitude of the error in the ratio of compression for different routes and steel grades, does not take into account the mechanical properties and the total strain, does not allow to vary the parameters of the distribution of forces. Therefore, for each grade of steel of each route under intensive regimes, it is necessary to select new combinations of curves. -. The condition of uniform change in the basic dimensions of the workpiece — the inner or outer diameter and wall thickness of the deformable workpiece (if the values of partial reductions are recorded), which simultaneously determines the uniform distribution of metal pressures on the rolls, can be represented in the following ratio:

AC: & YH ". (1)

.or

Hi

bty. : udx,

where WH, id, ut are the changes in the radius, diameter and wall thickness - deforming. . my workpiece in: considered section;

“T is a constant value.

Changes in the partial deformations ut and (4D.j) can be expressed in terms of the geometrical parameters of the ridge and the generator of the mandrel (3)

, (tgo,) (2) (tget,), (3)

where is the linear displacement (the product of feed for the current is the draw ratio); tg УХ tangent of the angle of inclination of the tangent to the profile of the ridge stream (the taper of the ridge stream in section x); tgoix is the tangent of the angle of inclination of the tangent to the generator of the mandrel (the taper of the mandrel in section (x).

Since the tangent of the angle of inclination of the tangent to the graph of the function at any point is equal to the first derivative of this function (4), the change of variables is valid:

 (x) 1 / d)

tigct., y (x)

U37119

Substitute the values of Jit and uV, (iDjf) from expressions (2) and (3), taking into account equality (4), into relation (1).

m | u, (y (x) -y (x) miuJyjTx))

(five)

ten

15

After reducing the numerator and denominator by m | u and transfer to the right-hand side of the equation, we get:

y; (x) y; (x). (BB) (6)

Freeing from the derivatives, we obtain the dependence of the point of a point on the ridge of the stream and of the generator y. in any section

yi (x) y, (x) - (d + 1) + C: (7)

An elementary analysis of the dependence (7) shows that the curves y and y for any type of task of their equations differ in form. With a given curve y, (or y.j.), the second curve Y– (y or y, respectively) can be obtained as a result of a scale-changing transformation, i.e., i .e. when (d + 1) 1 curve is obtained in the right-hand part of equations (8a) and takes place where 3 mm is half of the input gap between the inner surface of the workpiece and the cylindrical part of the mandrel at its larger diameter. 1,08t - the value of the wall of the workpiece, taking into account the thickening.

,, 08t,

R., Rp - the radii of the workpiece and the finished pipe; t ,, t, is the wall thickness of the workpiece

and finished pipe.

Left on the right side of C and then equating the left sides of equation (8a) 5 we get about:

Win - 1 -. (ten)

 - yu Similarly, left in

y, i (x) yv (y.K-y,)

X, ni

where y,

0

five

---, the right side of equations (8a) and committed R

U, to (Rrt5) -3 mm,

where 3 mm is half the input gap between the inner surface of the workpiece and the cylindrical part of the mandrel at its larger diameter. 1,08t - the value of the wall of the workpiece, taking into account the thickening.

,, 08t,

R., Rp - the radii of the workpiece and the finished pipe; t ,, t, is the wall thickness of the workpiece

and finished pipe.

Left on the right side of C and then equating the left sides of equation (8a) 5 we get about:

Win - 1 -. (ten)

 - yu Similarly, left in

It comes from y, stretching, and, with (tt + 1): - 1 - by compression.

The shape of the curves is different if their equations are different. Thus, the curves of the same name (5), having 1e various exponents, have a different form. The exponents of the curves y, -, and Y 2 (7) are equal to each other, however, all points of the curve y are (ci + 1) + C times different in distance from the axis of rolling from the corresponding points :: curve y. The shape of the function graphs is significantly different. Other indicators of the shape of the curves y and yy also differ significantly among themselves.

Definition of constant WB and C you-. complete according to equation (7), given in accordance with fkg, the distance from the axis of rolling to the extreme segments of the points y and y in the sections

yj, () y, (xj + clf.

y, (l-I) y, (XO + C /

or at „(° C + 1) th + C

) Y, K + S

The distances from the rolling axis to the extreme points of the curves y ,, (x) and Y (x,) - y ,, Y4, Y, o, yjK are determined from the equations of a particular rolling route using the equations

V 1 |

(R) (9)

y "((yiK-yw) (L

(eleven)

shiv necessary conversions, we define C:

iK C:

0U10 - U1K

The value of the constant coefficients y, q.y-iK of various mass rolling routes on the mills used is presented in the table.

5 The values of the coefficient of determining the reduction, specifically, the ratio of partial reductions of diameter and wall for a given steel grade (1) can either be set in advance or determined by given values of y,

I TEACH U 10 U-gk (10) If the value of "i

j are given, as well as the value of the dimensions of the screen of Y2 (((V1k vary the value of

y, (j or y, depending on the finite size of the available tool; or other technological conditions, can be determined from the dependence (10) value of the remaining parameter, and then calculate C using formula 1G.

 given the values of oi and the dimensions of the finished pipe in the same way, you can select the dimensions of the workpiece. The metal pressure on the rolls is proportional to the deformation and the resistance to deformation. Since the strain resistance increases in length from the beginning of the crimping zone to its end, the total contact surface is reduced by the same amount to

. 51

The pressure on the rolls was uniform. The more evenly partial deformations are reduced, the larger the total deformation can be at given maximum allowable metal pressures on the rolls.

The deformation of the workpiece into the pipe by the proposed tool is as follows. ,

The workpiece is precipitated along the diameter by a reducing section of the ridge stream 1 on the mandrel 2, after which, at point A, the deformation of the workpiece along the diameter and wall thickness begins simultaneously along the entire length of the crimping zone AB. The magnitudes of the absolute partial strains & D and ut decrease as one approaches the point B, so that their ratio along the length of the crimp: AB zone remains constant. In the calibration zone, the deformation of the working cone ends.

The rate of reduction is determined by the geometrical parameters of a given curve ridge stream or mandrel.

The initial curve is the profile of a ridge stream or a forming mandrel can be specified either as an equation; or immediately in the form of points located at a certain distance x.

In practical terms, the operation of a tool CPT when rolling from one blank, first one size of the finished pipe, and then the next one, which has a new diameter of the inner surface, it becomes necessary to select the forming mandrel. The forming mandrel must be selected in accordance with the profile of the ridge stream, which is obtained after the production of a certain period of work and polishing.

If you choose the points of the generator of the new mandrel in accordance with the actual profile of the ridge, then the resulting tool will differ significantly from the one that is laid in the calibration.

In order for the tool to ensure a constant ratio of the absolute deformations of the diameter and wall along the length of the crimping zone, the actual dimensions of the ridge of the brook and mandrel must be chosen from relation (7). The mastering (1) of the similarity (multiplicity) or equality of compression of the diameter and wall for real routes can be fulfilled if

d

g n

five

Q

five

0

196

according to the formulas (10) and (11), the given dimensions of the workpiece and the finished pipe with pa; using the known (specified) profile of one of the tools (a ridge stream or a forming mandrel). In this case, as follows from the table, the value of C is not always a number. To obtain a given integer, for example, it is necessary to correct one of the radii of the outer and inner surface of the pipe or workpiece. By presenting (10) as the difference between the specified radii and specifying the value ci ,, we determine that the difference of the radii of the outer surface of the reduction zone exceeds the difference radii of the inner surface. From this it follows that in order to obtain an integer similarity of partial reductions, a similar integer ratio of the dimensions of the workpiece and the finished pipe is necessary. Adjusting the size of the workpiece in the direction of increasing reductions does not significantly increase the pressure of the metal on the rolls. Increasing the uniformity of shaping in the reduction zone by matching the sweep profile of the ridge and forming the mandrel allows reducing the length of the reduction zone by 25-65% and thereby increasing the uniformity of the reduction in the deformation zone.

For any form of a ridge or forming a mandrel, the second curve, respectively forming a mandrel or a ridge stream, determined from relation (7), provide for rolling constant (or equal) ratio of absolute partial deformations along the length of the reduction zone.

The values of the corrected sizes of the boundaries of the reduction zone:

.. „

(12)

Have

1 TO

3fi.k - Ugo Oil

The brook profile, according to its width within the reduction zone, is chosen similarly to the ridge profile (7), calculating the coefficients LY | and C according to formulas (10) and (11), only substituting for the size of the ridge (at Hz and) instead of the dimensions of the brook releases, determined by known methods at the corresponding boundary points of the reduction zone.

The proposed correspondence between the points of both curves forming the longitudinal profile of the rolling gap.

 one

allows you to provide the necessary, specified deformation conditions, taking into account the errors of manufacture of the tool and its wear.

As a result of inaccurate production of a ridge brook (or mandrels), the resulting curves are significantly different from the calculated ones, which leads to a deviation of the rolling process. If the second tool is manufactured with regard to manufacturing errors, the first one (which at present is difficult to take into account in advance or significantly reduced without additional costs) or changes in its profile as a result of wear and repolishing during operation, only in this case will the deviations of the deformation modes be minimal from calibrated.

As a result of these random deviations of manufacture and operation, an innumerable set of curves can be obtained, which, only with this proposed correction of the second profile in the first, allow one to obtain a given deformation mode.

Thus, the specified conditions of deformation, in particular, the mode / private obgatiy, can be obtained by observing the following conditions and the implementation of their actions.

Based on the given dimensions of one of the tools at the boundaries of the reduction zone of a given value oi, the ratio of the dimensions of the workpiece and the finished pipe (10) determines the value of the coefficient C (11).

The measured current values of the dimensions of the outer or inner tool (7) determine the sizes of the corresponding sections and the tool itself in the reduction zone.

If the value is oi. For the rolling route under consideration, this steel grade is satisfactory, then the dimensions of the billet and finished pipe are not adjusted.

These advantages of the proposed tool allow you to create a quality reserve and use it both to increase rolling conditions and the number of pipes produced, as well as to obtain high-quality pipes for responsible use.

Tests of the proposed tool were carried out at the KhPT 32 mill at

five

about

five

five

198

rolling tubes 16x2,5 mm stainless steels.

Compared with the prototype, tests showed a significant decrease in rolling defects on the inner surface of pipes under normal and elevated deformation modes (with a one-and-a-half increase in feed rate).

The yield compared with the known tools increased by 1.3-1.5 times.

Claims (1)

Formula shade shadow A tool for periodically deforming pipes, containing a swath with a stream and a mandrel, having successively reduced, crimped areas, where the crest and the forming mandrel are described by equations of the same name with equal degrees and calibrations, in order to improve performance with the smallest anisotropy of mechanical properties, it ensures the constant ratio of absolute partial deformations in diameter and wall thickness of rolled tubes The parameters of the brook and mandrel are determined by the length of the crimping zone from the ratio yi (x) y, (x) ("L + O + C, where Y2, (x), y (x) are, respectively, the radii of the stream and mandrels in arbitrary like sections of the blooming zone; X, С - constant coefficients set by dependencies WITH about iiiiio U1K - U, about Uyo U 1 U10 U1K -Y one, where Ul1, Ulp respectively external  IV; m the radii of the stream at the beginning and end of the compression zone; The radius of the mandrel corresponding to the beginning and end of the reduction zone. pui. 7 .Stagemaster V.Shaymardanov Editor N.Gorvat hred L.Serdyukova Corrector O. Kravtsova Order 5824/12  Circulation 467 VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 2 Subscription