Stability of the cross-sectional profile during pipe reduction. On the reduced section of thin-walled tee, angle and cruciform profiles after local buckling. Calculation of design indicators

where, p is the number of the current iteration; vt is the total speed of metal sliding over the tool surface; vn is the normal speed of metal movement; wn is the normal speed of the tool; st - friction stress;
- Yield stress as a function of the parameters of the deformable metal, at a given point; - Medium voltage; - Intensity of strain rate; x0 - strain rate of all-round compression; Kt - penalty factor for the speed of metal sliding over the tool (specified by the iteration method) Kn - penalty factor for metal penetration into the tool; m - conditional viscosity of the metal, refined by the method of hydrodynamic approximations; - tension tension or backwater during rolling; Fn - area cross section the end of the pipe to which tension or support is applied.
The calculation of the deformation-speed mode includes the distribution of the state of deformations along the stands along the diameter, the required value of the coefficient of plastic tension according to the state Ztot, the calculation of the drawing ratios, roll diameters of the rolls and the rotational speed of the main drive motors, taking into account the features of its design.
For the first stands of the mill, including the first stand that rolls, and for the last, placed after the last stand, rolls, the coefficients of plastic tension in them Zav.i are less than the required Ztot. Due to such a distribution of the plastic tension coefficients over all stands of the mill, the calculated wall thickness at the exit from it is greater than necessary along the reduction route. In order to compensate for the insufficient pulling capacity of the rolls of the stands located in the first and after the last stands that are rolled, it is necessary, using an iterative calculation, to find such a value Ztotal that the calculated and specified wall thicknesses at the exit from the state are the same. The greater the value of the required total coefficient of plastic tension according to the state Ztotal, the greater the error in its determination without iterative calculation.
After the iterative calculations have calculated the coefficients of the front and rear plastic tension, the thickness of the pipe wall at the inlet and outlet of the deformation cells along the stands of the reduction mill, we finally determine the position of the first and last stands that are rolled.
Of course, rolling the diameter is determined through the central angle qk.p. between the vertical axis of symmetry of the roll groove and the line drawn from the center of the pass, coincides with the rolling axis to a point on the surface of the pass groove, where the neutral line of the deformation zone is located on its surface, is conventionally located parallel to the rolling axis. The value of the angle qk.p., first of all, depends on the value of the coefficient of the rear Zset. and front Zper. tension, as well as the coefficient
hoods.
Determination of rolling diameter by the value of the angle qk.p. usually performed for a caliber, has the shape of a circle with a center in the rolling axis and a diameter equal to the average diameter of the caliber Dav.
The largest errors in determining the value of the rolling diameter without taking into account the actual geometric dimensions of the pass will be for the case when the rolling conditions determine its position either at the bottom or at the groove flange. The more the real shape of the caliber differs from the circle accepted in the calculations, the more significant this error will be.
The maximum possible range of change of the actual value of the diameter rolls the caliber is a roll cut. The greater the number of rolls forms a caliber, the greater the relative error in determining the rolling diameter without taking into account the actual geometric dimensions of the caliber.
With an increase in the partial reduction of the pipe diameter in the caliber, the difference between its shape and the round one grows. So, with an increase in the reduction of the pipe diameter from 1 to 10%, the relative error in determining the value of the rolling diameter without taking into account the actual geometric dimensions of the caliber increases from 0.7 to 6.3% for a two-roller, 7.1% for a three-roller and 7.4% - for a chotirio-roll "rolling" stand when, according to the kinematic conditions of rolling, rolling the diameter located along the bottom of the caliber.
Simultaneous increase in the same

3.2 Calculation of the rolling table

The basic principle of constructing the technological process in modern installations is to obtain pipes of the same constant diameter on a continuous mill, which allows the use of a billet and a sleeve of also a constant diameter. Obtaining pipes of the required diameter is ensured by reduction. Such a system of work greatly facilitates and simplifies the setting of the mills, reduces the stock of tools and, most importantly, allows you to maintain high productivity of the entire unit even when rolling pipes of a minimum (after reduction) diameter.

We calculate the rolling table against the rolling progress according to the method described in. The outer diameter of the pipe after reduction is determined by the dimensions of the last pair of rolls.

D p 3 \u003d (1.010..1.015) * D o \u003d 1.01 * 33.7 \u003d 34 mm

where D p is the diameter of the finished pipe after the reduction mill.

The wall thickness after continuous and reduction mills must be equal to the wall thickness of the finished pipe, i.e. S n \u003d Sp \u003d S o \u003d 3.2 mm.

Since a pipe of the same diameter comes out after a continuous mill, we take D n \u003d 94 mm. In continuous mills, the calibration of the rolls ensures that in the last pair of rolls the inner diameter of the pipe is 1-2 mm larger than the diameter of the mandrel, so that the diameter of the mandrel will be equal to:

H \u003d d n - (1..2) \u003d D n -2S n -2 \u003d 94-2 * 3.2-2 \u003d 85.6 mm.

We take the diameter of the mandrels equal to 85 mm.

The inner diameter of the sleeve must ensure the free insertion of the mandrel and is taken 5-10 mm larger than the diameter of the mandrel

d g \u003d n + (5..10) \u003d 85 + 10 \u003d 95 mm.

We accept the wall of the sleeve:

S g \u003d S n + (11..14) \u003d 3.2 + 11.8 \u003d 15 mm.

The outer diameter of the sleeves is determined based on the value of the inner diameter and wall thickness:

D g \u003d d g + 2S g \u003d 95 + 2 * 15 \u003d 125 mm.

The diameter of the used workpiece D h =120 mm.

The diameter of the mandrel of the piercing mill is selected taking into account the amount of rolling, i.e. rise in the inner diameter of the sleeve, which is from 3% to 7% of the inner diameter:

P \u003d (0.92 ... 0.97) d g \u003d 0.93 * 95 \u003d 88 mm.

The drawing coefficients for piercing, continuous and reduction mills are determined by the formulas:

,

The overall draw ratio is:

The rolling table for pipes 48.3×4.0 mm and 60.3×5.0 mm in size was calculated in a similar way.

The rolling table is presented in Table. 3.1.

Table 3.1 - TPA-80 rolling table

Size of finished pipes, mm

Workpiece diameter, mm

Piercing mill

Continuous mill

reduction mill

Overall elongation ratio

Outside diameter

Wall thickness

Sleeve size, mm

Mandrel diameter, mm

Draw ratio

Pipe dimensions, mm

Mandrel diameter, mm

Draw ratio

Pipe size, mm

Number of stands

Draw ratio

Wall thickness

Wall thickness

Wall thickness

3.3 Calculation of the calibration of the reduction mill rolls

Roll calibration is important integral part calculation of the operating mode of the mill. It largely determines the quality of the pipes, tool life, load distribution in the working stands and the drive.

Roll calibration calculation includes:

distribution of partial deformations in the stands of the mill and calculation of average diameters of calibers;

determination of the dimensions of the rolls.

3.3.1 Partial strain distribution

According to the nature of the change in partial deformations, the stands of the reduction mill can be divided into three groups: the head one at the beginning of the mill, in which the reductions increase intensively during rolling; calibrating (at the end of the mill), in which the deformations are reduced to a minimum value, and a group of stands between them (middle), in which partial deformations are maximum or close to them.

When rolling pipes with tension, the values ​​of partial deformations are taken on the basis of the stability condition of the pipe profile at a plastic tension value that ensures the production of a pipe of a given size.

The coefficient of total plastic tension can be determined by the formula:

,

where
- axial and tangential strains taken in logarithmic form; T is the value determined in the case of a three-roll caliber by the formula

where (S/D) cp is the average ratio of wall thickness to diameter over the period of pipe deformation in the mill; k-factor taking into account the change in the degree of thickness of the pipe.

,

,

where m is the value of the total deformation of the pipe along the diameter.

.

The value of the critical partial reduction at such a coefficient of plastic tension, according to , can reach 6% in the second stand, 7.5% in the third stand and 10% in the fourth stand. In the first cage, it is recommended to take in the range of 2.5-3%. However, to ensure a stable grip, the amount of compression is generally reduced.

In the pre-finishing and finishing stands of the mill, the reduction is also reduced, but to reduce the load on the rolls and improve the accuracy of the finished pipes. In the last stand of the sizing group, the reduction is taken equal to zero, the penultimate one - up to 0.2 from the reduction in the last stand of the middle group.

AT middle group stands practice uniform and non-uniform distribution of partial deformations. With a uniform distribution of compression in all stands of this group, they are assumed to be constant. The uneven distribution of particular deformations can have several variants and be characterized by the following patterns:

compression in the middle group is proportionally reduced from the first stands to the last - falling mode;

in the first few stands of the middle group, partial deformations are reduced, while the rest are left constant;

compression in the middle group is first increased and then reduced;

in the first few stands of the middle group, partial deformations are left constant, and in the rest they are reduced.

With decreasing deformation modes in the middle group of stands, the differences in the rolling power and the load on the drive decrease, caused by an increase in the resistance to deformation of the metal during rolling, due to a decrease in its temperature and an increase in the strain rate. It is believed that reducing the reduction towards the end of the mill also improves the quality of the outer surface of the pipes and reduces the transverse wall variation.

When calculating the calibration of the rolls, we assume a uniform distribution of reductions.

The values ​​of partial deformations in the stands of the mill are shown in fig. 3.1.

Crimp Distribution

Based on the accepted values ​​of partial deformations, the average diameters of the calibers can be calculated using the production formula pipes, and, directly, ... failures) during production foam concrete. At production foam concrete are used by various ... workers directly related to production foam concrete, special clothing, ...

Production non-pressure reinforced concrete pipes

Degree work >> Industry, production

rolled Production pipes by centrifugal rolling. Reinforced concrete pipes are made ... with a centrifugal method production pipes. Loading of centrifuges with concrete... allows to make forms demoulding. Production pipes by radial pressing. This...

Ilyashenko A.V. – Associate Professor of the Department of Structural Mechanics
Moscow State Construction University,
candidate of technical sciences

The study of the bearing capacity of compressed elastic thin-walled rods that have an initial deflection and have undergone local buckling is associated with the determination of the reduced cross section of the rod. The main provisions adopted for the study of the stress-strain state in the supercritical stage of compressed non-ideal thin-walled rods are given in the works. This article discusses the supercritical behavior of the rods, which are presented as a set of jointly working elements - plates with an initial loss, simulating the work of corner, tee and cruciform profiles. These are the so-called shelves-plates with one elastically pinched edge and the other free (see figure). In the works, such a plate is referred to as type II.

It was found that the breaking load, which characterizes the bearing capacity of the rod, significantly exceeds the load P cr (m), at which there is a local buckling of the imperfect profile. From the graphs presented in , it can be seen that the deformations of the longitudinal fibers along the perimeter of the cross section in the supercritical stage become extremely unequal. In fibers far from the ribs, compressive strains decrease with increasing load, and at loads close to the limit, due to the sharp curvature of these fibers due to initial bends and ever-increasing arrows of longitudinal half-waves formed after local buckling, strains appear and grow rapidly. stretching.

Sections of the cross section with curved longitudinal fibers release stresses, as if they are switched off from the operation of the rod, weakening the effective section and reducing its rigidity. So the bearing capacity thin-walled profile not limited to local buckling. The full load, perceived by more rigid (less curved) sections of the cross section, can significantly exceed the value of P cr (m) .

We will obtain an effective, reduced section, excluding non-working sections of the profile. To do this, we use the expression for the stress function Ф k (x, y), which describes the stress state of the kth plate of type II (see).

Let's move on to supercritical stresses σ kx (in the direction of the external compressive force), determined in the most unfavorable section of the rod (x=0). Let's write them down in general view:

σ kx =∂ 2 Ф k (A km ,y, f kj , f koj , β c,d , β c,d,j ,ℓ, s) ∕ ∂ y 2 , (1)

where the integration constants А km (m=1,2,…,6) and the arrows of the acquired deflection components f kj (j=1,2) are determined from the solution of the system of resolving equations . This system of equations includes nonlinear variational equations and boundary conditions that describe the joint operation of non-ideal profile plates. Arrows f koj (j=1,2,…,5) components of the initial deflection k-th plate are determined experimentally for each profile type;
ℓ is the length of the half-wave formed during local buckling;
s is the plate width;

β c,d = cs 2 + dℓ 2 ;

β c,d,j = cs 4 + dl 2 s 2 + gl 4 ;

c, d, j are positive integers.

The reduced or effective width of the reduced section of the plate-shelf (type II) will be denoted by s p. To determine it, we write out the conditions for the transition from the actual cross section of the rod to the reduced one:

1. The stresses in the longitudinal fibers at the initial face of the plate (at y=0) adjacent to the rib (see figure) remain the same as those obtained by the nonlinear theory (1):

where F 2 kr =f 2 kr +2f k0r f kr .

To determine the stress σ k2 =σ k max it is necessary to substitute in (1) the ordinate of the most loaded longitudinal fiber, which is found from the condition: ∂σ kx /∂y=0.

2. The sum of internal forces in the plate during the transition to the reduced section in the direction of the compressive force does not change:

3. The moment of internal forces relative to the axis passing through the initial face (y=0) perpendicular to the plane of the plate remains the same:

From the figure, it is obvious that

σ ′ k2 = σ k1 + y p (σ k2 -σ k1) / (y p + s p). (5)

We write down the system of equations for determining the reduced width of the plate s p. To do this, we substitute (1) and (5) into (3) and (4):

where α=πs/ℓ ; F kr,ξ =f kr f koξ +f kr f kξ +f kor f kξ ;
r, ξ are positive integers.

The resulting system of equations (6) and (7) makes it possible to determine the reduced width s p of each of the plates-shelves that make up a compressed thin-walled rod that has undergone local buckling. Thus, the actual cross section of the profile was replaced by a reduced one.

The proposed method seems to be useful both in theoretical and practical terms when calculating the bearing capacity of compressed pre-curved thin-walled rods, in which local wave formation is permissible according to operational requirements.

Bibliographic list

1. Ilyashenko A.V., Efimov I.B. Stress-strain state after local buckling of compressed thin-walled rods, taking into account the initial deflection. Stroitel'nye konstruktsii i materialy. Corrosion protection. - Ufa: Works of in-ta NIIpromstroy, 1981. - P.110-119.
2. Ilyashenko A.V. To the calculation of thin-walled tee, angle and cruciform profiles with initial camber // Pile foundations. - Ufa: Sat. scientific tr. Niipromstroy, 1983. - S. 110-122.
3. Ilyashenko A.V., Efimov I.B. Experimental study of thin-walled rods with curved lamellar elements // Organization and production construction works. - M .: Tsentr.Buro n.-t. Information of Minpromstroy, 1983.

UDC 621.774.3

STUDY OF THE DYNAMICS OF CHANGES IN THE PIPE WALL THICKNESS DURING REDUCTION

K.Yu. Yakovleva, B.V. Barichko, V.N. Kuznetsov

The results of an experimental study of the dynamics of changes in the wall thickness of pipes during rolling, drawing in monolithic and roller dies are presented. It is shown that with an increase in the degree of deformation, a more intense increase in the thickness of the pipe wall is observed in the processes of rolling and drawing in roller dies, which makes their use promising.

Key words: cold-formed pipes, thick-walled pipes, pipe drawing, pipe wall thickness, pipe inner surface quality.

The existing technology for the manufacture of cold-formed thick-walled pipes of small diameter from corrosion-resistant steels provides for the use of cold rolling processes on cold rolling mills and subsequent mandrelless drawing in monolithic dies. It is known that the production of pipes of small diameter by cold rolling is associated with a number of difficulties due to a decrease in the rigidity of the "rod-mandrel" system. Therefore, to obtain such pipes, a drawing process is used, mainly without a mandrel. The nature of the change in the pipe wall thickness during mandrelless drawing is determined by the ratio of wall thickness S and outer diameter D, and the absolute value of the change does not exceed 0.05-0.08 mm. In this case, wall thickening is observed at the ratio S/D< 0,165-0,20 в зависимости от наружного диаметра заготовки . Для данных соотношений размеров S/D коэффициент вытяжки д при волочении труб из коррозионно-стойкой стали не превышает значения 1,30 , что предопределяет многоцикличность известной технологии и требует привлечения новых способов деформации.

The aim of the work is a comparative experimental study of the dynamics of changes in the wall thickness of pipes in the processes of reduction by rolling, drawing in a monolithic and roller die.

Cold-formed pipes were used as blanks: 12.0x2.0 mm (S/D = 0.176), 10.0x2.10 mm (S/D = 0.216) from steel 08Kh14MF; dimensions 8.0x1.0 mm (S / D = 0.127) from steel 08X18H10T. All pipes were annealed.

Drawing in monolithic dies was carried out on a chain drawing bench with a force of 30 kN. For roller drawing, we used a die with offset pairs of rollers BP-2/2.180. Drawing in a roller die was carried out using an oval-circle gauge system. Pipe reduction by rolling was carried out according to the “oval-oval” calibration scheme in a two-roll stand with rolls 110 mm in diameter.

At each stage of deformation, samples were taken (5 pcs. for each study option) to measure the outer diameter, wall thickness, and roughness of the inner surface. Measurement of the geometric dimensions and surface roughness of the pipes was performed using an electronic caliper TTTC-TT. electronic point micrometer, profilometer Surftest SJ-201. All tools and devices have passed the necessary metrological verification.

The parameters of cold deformation of pipes are given in the table.

On fig. 1 shows graphs of the dependence of the relative increase in wall thickness on the degree of deformation e.

Analysis of the graphs in fig. 1 shows that during rolling and drawing in a roller die, in comparison with the process of drawing in a monolithic die, a more intense change in the thickness of the pipe wall is observed. This, according to the authors, is due to the difference in the scheme of the stress state of the metal: during rolling and roller drawing, the tensile stresses in the deformation zone are smaller. The location of the wall thickness change curve during roller drawing below the wall thickness change curve during rolling is due to slightly higher tensile stresses during roller drawing due to the axial application of the deformation force.

The extremum of the function of the change in wall thickness as a function of the degree of deformation or relative reduction along the outer diameter observed during rolling corresponds to the value S/D = 0.30. By analogy with hot reduction by rolling, where a decrease in wall thickness is observed at S/D > 0.35, it can be assumed that cold reduction by rolling is characterized by a decrease in wall thickness at a ratio of S/D > 0.30.

Since one of the factors determining the nature of the change in wall thickness is the ratio of tensile and radial stresses, which in turn depends on the parameters

Pass No. Pipe dimensions, mm S,/D, Si/Sc Di/Do є

Reduction by rolling (pipes made of steel grade 08X14MF)

О 9.98 2.157 О.216 1.О 1.О 1.О О

1 9.52 2.23O 0.234 1.034 0.954 1 .30 80.04

2 8.1O 2.35O O.29O 1.O89 O.812 1.249 O.2O

Z 7.01 2.324 O.332 1.077 O.7O2 1.549 O.35

Reduction by rolling (pipes made of steel grade 08X18H10T)

О 8,О6 1,О2О О,127 1,О 1,О 1,О О

1 7.OZ 1.13O O.161 1.1O8 O.872 1.O77 O.O7

2 6.17 1.225 0.199 1.201 0.766 1.185 0.16

C 5.21 1.310 0.251 1.284 0.646 1.406 0.29

Reducing by drawing in a roller die (pipes made of steel grade 08X14MF)

О 12.ОО 2.11 О.176 1.О 1.О 1.О О

1 10.98 2.20 0.200 1.043 0.915 1.080 0.07

2 1O.O8 2.27 O.225 1.O76 O.84O 1.178 O.15

Z 9.O1 2.3O O.2O1 1.O9O O.751 1.352 O.26

Reducing by drawing in a monolithic die (pipes made of steel grade 08X14MF)

О 12.ОО 2.11О О.176 1.О 1.О 1.О О

1 1O.97 2.135 0.195 1.O12 O.914 1.1O6 O.1O

2 9.98 2.157 O.216 1.O22 O.832 1.118 O.19

C 8.97 2.160 0.241 1.024 0.748 1.147 0.30

Di, Si - respectively, the outer diameter and wall thickness of the pipe in aisle.

Rice. 1. Dependence of the relative increase in pipe wall thickness on the degree of deformation

ra S/D, it is important to study the influence of the S/D ratio on the position of the extremum of the function of changing the pipe wall thickness in the process of reduction. According to the data of the work, at smaller S/D ratios, the maximum value of the pipe wall thickness is observed at large deformations. This fact was studied on the example of the process of reduction by rolling pipes with dimensions of 8.0x1.0 mm (S/D = 0.127) of steel 08Kh18N10T in comparison with the data on rolling pipes with dimensions of 10.0x2.10 mm (S/D = 0.216) of steel 08Kh14MF. The measurement results are shown in fig. 2.

The critical degree of deformation at which the maximum value of the wall thickness was observed during pipe rolling with the ratio

S/D = 0.216 was 0.23. When rolling pipes made of steel 08Kh18N10T, the extremum of the increase in wall thickness was not reached, since the ratio of pipe dimensions S/D, even at the maximum degree of deformation, did not exceed 0.3. An important circumstance is that the dynamics of the increase in wall thickness during the reduction of pipes by rolling is inversely related to the ratio of the dimensions S/D of the original pipe, which is demonstrated by the graphs shown in Fig. 2, a.

Analysis of curves in fig. 2b also shows that the change in the S/D ratio during the rolling of pipes made of steel grade 08Kh18N10T and pipes made of steel grade 08Kh14MF has a similar qualitative character.

S0/A)=0.127 (08X18H10T)

S0/00=0.216 (08X14MF)

Degree of deformation, b

VA=0;216 (08X14MF)

(So/Da=0A21 08X18H10T) _

Degree of deformation, є

Rice. Fig. 2. Changes in wall thickness (a) and S/D ratio (b) depending on the degree of deformation during rolling of pipes with different initial S/D ratios

Rice. Fig. 3. Dependence of the relative value of the roughness of the inner surface of pipes on the degree of deformation

In the process of reduction different ways the roughness of the inner surface of the pipes was also evaluated by the arithmetic mean deviation of the microroughness height Ra. On fig. Figure 3 shows the graphs of the dependence of the relative value of the parameter Ra on the degree of deformation when pipes are reduced by rolling and drawing in monolithic dies

woolness of the inner surface of the pipes in the i-th passage and on the original pipe).

Analysis of curves in fig. 3 shows that in both cases (rolling, drawing) an increase in the degree of deformation during reduction leads to an increase in the Ra parameter, that is, it worsens the quality of the inner surface of the pipes. The dynamics of change (increase) in the roughness parameter with an increase in the degree of deformation in the case of

ducting of pipes by rolling in two-roll calibers significantly (about two times) exceeds the same indicator in the process of drawing in monolithic dies.

It should also be noted that the dynamics of changes in the roughness parameter of the inner surface is consistent with the above description of the dynamics of changes in wall thickness for the considered reduction methods.

Based on the research results, the following conclusions can be drawn:

1. The dynamics of pipe wall thickness change for the considered cold reduction methods is of the same type - intense thickening with an increase in the degree of deformation, subsequent slowing down of the wall thickness growth with reaching a certain maximum value at a certain ratio of pipe dimensions S/D and a subsequent decrease in the wall thickness growth.

2. The dynamics of changes in pipe wall thickness is inversely related to the ratio of the original pipe dimensions S/D.

3. The greatest dynamics of the increase in wall thickness is observed in the processes of rolling and drawing in roller dies.

4. An increase in the degree of deformation during reduction by rolling and drawing in monolithic dies leads to a deterioration in the state of the inner surface of the pipes, while the increase in the roughness parameter Ra during rolling occurs more intensively than during drawing. Taking into account the conclusions drawn and the nature of the change in the wall thickness during deformation, it can be argued that for drawing pipes in roller dies,

The change in the Ra parameter will be less intense than for rolling, and more intense in comparison with monolithic drawing.

The information obtained about the regularities of the cold reduction process will be useful in designing routes for the manufacture of cold-formed pipes from corrosion-resistant steels. At the same time, the use of the drawing process in roller dies is promising for increasing the thickness of the pipe wall and reducing the number of passes.

Literature

1. Bisk, M.B. cold deformation steel pipes. In 2 hours, Part 1: Preparation for deformation and drawing / M.B. Bisk, I.A. Grekhov, V.B. Slavin. -Sverdlovsk: Mid-Ural. book. publishing house, 1976. - 232 p.

2. Savin, G.A. Pipe drawing / G.A. Savin. -M: Metallurgy, 1993. - 336 p.

3. Shveikin, V.V. Technology of cold rolling and reduction of pipes: textbook. allowance / V.V. Shveikin. - Sverdlovsk: Publishing House of UPI im. CM. Kirova, 1983. - 100 p.

4. Technology and equipment for pipe production /V.Ya. Osadchiy, A.S. Vavilin, V.G. Zimovets and others; ed. V.Ya. Osadchy. - M.: Intermet Engineering, 2007. - 560 p.

5. Barichko, B.V. Basics technological processes OMD: lecture notes / B.V. Barichko, F.S. Dubinsky, V.I. Krainov. - Chelyabinsk: Publishing House of SUSU, 2008. - 131 p.

6. Potapov, I.N. Theory of pipe production: textbook. for universities / I.N. Potapov, A.P. Kolikov, V.M. Druyan. - M.: Metallurgy, 1991. - 424 p.

Yakovleva Ksenia Yuryevna, junior researcher, Russian Research Institute of the Pipe Industry (Chelyabinsk); [email protected]

Barichko Boris Vladimirovich, Deputy Head of the Seamless Pipe Department, Russian Research Institute of the Pipe Industry (Chelyabinsk); [email protected]

Kuznetsov Vladimir Nikolaevich, head of the cold deformation laboratory of the central plant laboratory, Sinarsky Pipe Plant OJSC (Kamensk-Uralsky); [email protected]

Bulletin of the South Ural State University

Series "Metallurgy" ___________2014, vol. 14, no. 1, pp. 101-105

STUDY OF DYNAMIC CHANGES OF THE PIPE WALL THICKNESS IN THE REDUCTION PROCESS

K.Yu. Yakovleva, The Russian Research Institute of the Tube and Pipe Industries (RosNITI), Chelyabinsk, Russian Federation, [email protected],

B.V. Barichko, The Russian Research Institute of the Tube and Pipe Industries (RosNITI), Chelyabinsk, Russian Federation, [email protected],

V.N. Kuznetsov, JSC "Sinarsky Pipe Plant", Kamensk-Uralsky, Russian Federation, [email protected]

The results of the experimental study of dynamic changes for the pipe wall thickness during rolling, drawing both in single-piece and roller dies are described. The results show that with the deformation increasing the faster growth of the pipe wall thiknness is observed in rolling and drawing with the roller dies. The conclusion can be drawn that the usage of roller dies is the most promising one.

Keywords: cold-formed pipes, thick-wall pipes, pipe drawing, pipe wall thickness, quality of the inner surface of pipe.

1. Bisk M.B., Grekhov I.A., Slavin V.B. Kholodnaya deformatsiya stal "nykh trub. Podgotovka k deformatsii i volochenie. Sverdlovsk, Middle Ural Book Publ., 1976, vol. 1. 232 p.

2 Savin G.A. Volochenie tube. Moscow, Metallurgiya Publ., 1993. 336 p.

3. Shveykin V.V. Tekhnologiya kholodnoy prokatki i redutsirovaniya trub. Sverdlovsk, Ural Polytechn. Inst. Publ., 1983. 100 p.

4. Osadchiy V.Ya., Vavilin A.S., Zimovets V.G. et al. Tekhnologiya i obrudovanie trubnogo proizvodstva. Osadchiy V.Ya. (Ed.). Moscow, Intermet Engineering Publ., 2007. 560 p.

5. Barichko B.V., Dubinskiy F.S., Kraynov V.I. Osnovy tekhnologicheskikh protsessov OMD. Chelyabinsk Univ. Publ., 2008. 131 p.

6. Potapov I.N., Kolikov A.P., Druyan V.M. Teoriya trubnogo proizvodstva. Moscow, Metallurgiya Publ., 1991. 424 p.