RU2540057C1 - Manufacturing method of tubes using continuous tube-welding machines - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method involves use of strips with a width having a shrinkage margin as to width at deformation, butt welding of ends of strips to a continuous strip, its deformation by alternating-sign plastic bending with tension with non-driven rolls of a multiroll bending-tensioning device, drawing through this device of the strip with a pulling mechanism, moulding of the strip into a tube workpiece, welding of its edges and calibration or shaping of a welded tube. Actual drawing value of the strip in the bending-tensioning device is determined. Thickness of the strip is measured at the inlet of the bending-tensioning device; drawing value is calculated for sections of the strip with thickness of more than H"гран" and drawing value for its sections with thickness in the range of hmin to H"гран" and its drawing is controlled by changing the total value of angles of all bends of the strip so that the actual drawing value is equal to its design value. The above parameters are subject to mathematical relationships.

EFFECT: improving a deformation degree of a strip and reducing metal consumption.

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Description

The invention relates to the processing of metals by pressure, in particular to the production of welded pipes on continuous tube welding units.

A known method of manufacturing pipes on continuous tube-welding units, including the use of a strip with a width that has a margin of its tightening in width during deformation, butt welding of the ends of the strips into a continuous strip, deformation of this strip by its alternating plastic bending with tension by non-driven rollers of a multi-roller bending-tensioning devices, measuring the thickness of the strip at the outlet of this device, determining the actual value of the strip hood in the bending and tensioning device, adjusting the hood and the strip by the total amount of change of the angles of all its bends in the bending and tensioning device ensuring the thickness of the strip after the deformation is not less than the allowable value h _min and limiting drawing value for the maximum permissible level, reducing the strip stretching magnitude in the passage through the bending and tensioner its sections with the joint of the ends of the strips, pulling the strip through this device with a pulling device, forming the strip into a pipe billet, welding its edges and calibrating or profiling the welded pipe, for example, the method according to RF patent No. 2351423 "Method for the manufacture of pipes on continuous tube welding units" (prototype).

The disadvantages of this method are the insufficient value of the deformation of the strip and the increased consumption of metal per unit length of the manufactured pipes.

The task of the invention is to increase the deformation of the strip and reduce the consumption of metal per unit length of the manufactured pipes.

The technical result is achieved due to the fact that in the method of manufacturing pipes on continuous tube-welding units, including the use of a strip with a width that has a margin of its width extension during deformation, butt welding of the ends of the strips into a continuous strip, deformation of this strip by its alternating plastic bending with tension by non-drive rollers of a multi-roller bending and tensioning device (GNU), measuring the strip thickness, determining the actual amount of strip drawing in the GNU, adjusting the exhaust by of the strip by changing the total value of the angles of all its bends in the GNU with ensuring the strip thickness after deformation is not less than the permissible value of h _min , reducing the amount of strip stretching for the time it passes through the GNU of its sections with the joint of the ends of the strips, pulling the strip through the GNU with a pulling device (TU), forming a strip into a pipe billet, welding its edges and calibrating or profiling a welded pipe according to the invention:

1. The thickness of the strip is measured at its entrance to the GNU.

2. The boundary value of the measured thickness H _{gran is} determined by the formula (1);

3. Sections of the strip with a thickness of more than H _gran deform with a drawing value λ ₁ determined by the formula (2).

4. Sections of the strip with a thickness in the range from h _min to H _gran deform with a drawing value of λ ₂ determined by the formula (3).

Formulas for the determination of H _gran ; λ ₁ and λ ₂ :

$$H_{gR\mathrm{but}n}=h_{m\mathrm{and}n}\cdot \left[\mathrm{one}+\left(N_{m\mathrm{but}\mathrm{to}\mathrm{from}}-N_{m\mathrm{and}n}\right)\cdot \pi :k:B\cdot \left(\mathrm{one}-k\right)\right];\begin{array}{ccc}& & \end{array}\left(\mathrm{one}\right)$$

$${\lambda }_{\mathrm{one}}=\mathrm{one}+\left(N_{m\mathrm{but}\mathrm{to}\mathrm{from}}-N_{m\mathrm{and}n}\right)\cdot \pi :k:B+\left(N_{\mathrm{and}sm}-N_{gR\mathrm{but}n}\right):N_{gR\mathrm{but}n}\cdot f:\left(\mathrm{one}-k\right);\begin{array}{ccc}& & \end{array}\left(2\right)$$

$${\lambda }_2=\mathrm{one}+\left(N_{\mathrm{and}sm}-h_{m\mathrm{and}n}\right):h_{m\mathrm{and}n}:\left(\mathrm{one}-k\right);\begin{array}{ccc}& & \end{array}\left(3\right)$$

Where

H _gran - the boundary value of the measured strip thickness;

h _min - the minimum allowable thickness of the strip after its deformation in the GNU, at which the wall thickness of the pipes will not be lower than the minimum allowable;

N _max and N _min - the largest and smallest strip thickness in the middle of its width, mm;

π is the Pi number equal to about 3.14;

k is the elongation coefficient of the deformable strip by reducing its width;

B is the width of the strip, including the margin for its tightening in width during deformation;

λ ₁ - the amount of stretching of sections of the strip with a thickness of more than H _gran ;

H _ISM - strip thickness, measured at the entrance to the GNU;

f = 0.1866 is a coefficient that determines for sections of the strip with a thickness of more than H _{gran the} proportion of deformation from the relative difference in thicknesses (H _ISM -H _gran ): H _gran .

λ ₂ - the amount of stretching sections of the strip with a thickness in the range from h _min to H _gran .

In the proposed method, in comparison with the prototype, the deformation of the strip sections with a thickness greater than H _gran will increase and, accordingly, the strip length after deformation will increase, which will reduce the metal consumption per unit length of the manufactured pipes. At the same time, the deformation of sections of the strip with a thickness of more than H _grains will be carried out according to such a law that the outer perimeter of the pipe billet formed from these sections of the strip after their deformation is at a permissible level, which will ensure satisfactory quality of the pipe joint.

The proposed method is as follows:

1. Determine the actual amount of strip exhaust in the GNU, for example, by dividing the measured speed of the strip at the outlet of the GNU by its measured speed at the entrance to it.

2. Measure the thickness of the strip at its entrance to the GNU using a thickness gauge equipped with an automatic signaling device.

3. Determine, according to the formula (1), the boundary value of the measured strip thickness H _gran .

4. On the automatic signaling device of the thickness gauge set the values of h _min and H _gran . The signaling device generates “minus”, “nominal” or “plus” signals with a measured thickness of less than h _min , respectively, in the range from h _min to H _gran or more than H _gran .

5. When the signal is “plus” according to the formula (2) calculate the amount of stretching of the strip λ ₁ .

6. When the signal "nominal" according to the formula (3) calculate the magnitude of the strip strip λ ₂ .

7. Regulate the deformation of the strip by changing the total value of the angles of all the bends of the strip in the GNU so that the actual stretch value of the strip is equal to its calculated value.

8. When the signal is “minus” the deformation of the strip is not carried out (the total value of the angles of all the bends of the strip in the GNU is zero).

9. For a time from the moment the junction of the ends of the strips approaches the GNU and until it leaves it, the stretch of the strip in the GNU is reduced to exclude the joint rupture.

10. The continuous strip drawn by the control unit from the GNU enters the molding mill and is molded into the tube billet.

11. A pipe billet formed from a continuous strip deformed according to the laws described above has an outer perimeter not lower than the minimum permissible, which will ensure satisfactory quality of the weld of the pipes being manufactured.

12. The welded pipe is calibrated in a calibration and milling mill (ensuring a round, square, rectangular or other pipe profile).

As an example, in the table below, the results of calculating the values of H _gran ; λ ₁ and λ ₂ at different values of the measured strip thickness for the case of implementing the proposed method for manufacturing welded pipes with an external diameter of 159 mm with a nominal wall thickness of 4.5 mm, for which, according to GOST 10705, the minimum allowable wall thickness is 4.00 mm. For a strip with a nominal thickness of 4.3 mm, the deliveries of OJSC Magnitogorsk Iron and Steel Works H _max and H _min are 4.60 and 4.00 mm, respectively. The minimum allowable strip thickness after deformation h _min , determined taking into account the transverse thickness difference of the indicated strip, the error of the thickness gauge and the minimum thickening of the metal with the existing technology for manufacturing these pipes, is 4.09 mm. The width of the strip B, including the margin for its tightening in width during deformation, is 496.6 mm. Testing the manufacture of these pipes by the proposed method showed that when the diameter of the bending rollers GNU equal to 150 mm, the coefficient k was 0.1. Coefficient f = 0.1866.

The table for the proposed method shows the results of calculating the values of H _gran ; λ ₁ ; λ ₂ ; h; b and P _trig and for comparison, the results of calculating the values of λ; h; b and P _{tr zag} for the method according to patent No. 2351423. The values of H _gran ; λ ₁ and λ _{2 were} calculated by the formulas (1), (2) and (3), respectively, and the values of h, b and P _{tr were} calculated by the formulas: h = H _meas · [1- (λ-1) · (1 -k)]; b = B · [1- (λ-1) · k]; P _{tr zag} = b + h · π.

The table shows that the strip drawing value when deformation in its thickness and width after deformation and the outer circumference of the formed tubular blank on the proposed method and RF patent №2351423 coincide only for the strip portions with a thickness H _edited 4.23 mm or less. For strip portions with a thickness of 4,24-4,60 mm H _edited value hoods according to the method of the patent of RF №2351423 equals 1.0380 or 3.80%, and the inventive method it is in the range of 1.0384 to 1.0561, or from 3.84 to 5.61%, which is compared with the prototype more by 0.04-1.81%.

In addition, the table shows that the proposed method of the strip portions with a thickness of 4,24-4,60 mm H _edited after deformation will be obtained with portions of the strip thickness and 4,099-4,380 mm in width respectively and 494,69-493,81 mm . The outer perimeter of the tube stock formed from these sections of the strip will be equal to the minimum allowable value of 507.57 mm. And this means that when welding the edges of a pipe billet having such an external perimeter, a satisfactory weld quality will be ensured.

Thus, with the proposed method of manufacturing pipes for the considered example, the amount of stretching of the sections of the strip with a thickness H _{ism of} 4.24-4.60 mm will increase by 0.04-1.81% compared with the prototype. This will increase the amount of extraction by about 0.5-0.6% on average in all sections of the strip and reduce by about the same the metal consumption of the pipes and the metal consumption per unit length.

The proposed method of manufacturing welded pipes will reduce metal consumption while ensuring the outer perimeter of the molded pipe billet at a level not lower than the minimum acceptable value, that is, while ensuring the manufacture of pipes without reducing the quality of the weld.

Claims (1)

A method of manufacturing welded pipes on continuous tube-welding units, including butt welding into a continuous strip of strip ends with a width that has a margin for tightening during deformation, deformation of said strip by alternating plastic bending with tension by non-driven rollers of a multi-roll bending and tensioning device by pulling a strip through this device device, measuring the thickness of the strip, determining the actual value of the strip hood in the bending and tensioning device, adjusting the hood by of the strip by changing the total value of the angles of all its bends in the bending and tensioning device, ensuring the strip thickness after deformation is not less than the permissible value of h _min and reducing the stretching time for the joint of the ends of the strips passing through the bending and tensioning device, forming the strip into a tube billet, and welding its edges and calibration or profiling welded tube, characterized in that the inlet bending and tensioner measured strip thickness determined limit value of the thickness H _gran, wherein portions with the strips schinoy more H _gran deformed with the magnitude of stretching λ _1, and portions of the strip having a thickness in a range from H to h _{min gran} deformed with a reduction value of λ _2, the values of H _gran, λ ₁ and λ ₂ is determined by the formulas:
H _gran = h _min · [1+ (H _max -H _min ) · π: k: B · (1-k)];
λ ₁ = 1 + (N _max -N _min ) · π: k: B + (N _meas -H _gran ): H _gran · f: (1-k);
λ ₂ = 1 + (N _meas- h _min ): h _min : (1-k);
Where
H _gran - the boundary value of the measured strip thickness;
h _min - the minimum allowable thickness of the strip after deformation, at which the wall thickness of the pipes will not be lower than the minimum allowable;
N _max and N _min - the largest and smallest strip thickness in the middle of its width, mm;
π is the Pi number equal to about 3.14;
k is the elongation coefficient of the deformable strip.
B is the width of the strip, including the margin for tightening the width when it is deformed;
λ ₁ - the amount of stretching of sections of the strip with a thickness of more than H _gran ;
N _ISM - strip thickness, measured at the entrance to the GNU;
F = 0.1866 is a coefficient that determines for sections of the strip with a thickness of more than N _{gran the} proportion of deformation of the relative difference in thicknesses (N _ISM- N _gran ): N _gran ;
λ ₂ - the amount of stretching sections of the strip with a thickness in the range from h _min to H _gran .