RU2188092C1 - Method for straightening round rolled pieces - Google Patents

Abstract

FIELD: plastic metal working, namely processes for straightening round rolled products such as tubes. SUBSTANCE: method comprises steps of changing eccentricity values of rings according to predetermined schedule of straightening, namely at straightening front and back ends of rolled piece using minimum number of standard rings; placing them by groups at maximally possible approaching of one to another and realizing inclination system of rings necessary for motion at eccentricity value in group equal to 0.8-0.9 of its tuned value; at straightening mean portion of rolled piece using at least four correct rings distributed along length of straightening zone and setting eccentricity according to nominal value while taking into account changed spacing between rings. EFFECT: enhanced quality of straightened rolled products due to use of different straightening systems with changed eccentricity of straightening rings. 19 dwg, 1 ex

Description

 The invention relates to the processing of metals by pressure, in particular to the technology of straightening round rolled products, for example pipes.

A method is known straightening of thin-walled pipes (see. SU, AS 1278055, M Cl. ³ 21 D 3/02, BI 47, 1986), which includes alternating flattening simultaneously at several evenly spaced around the perimeter of the radial cross sections and the bend pipe in the longitudinal direction. The essence of the invention lies in the fact that the flattening of the pipe is carried out according to the proposed dependence to the value at which plastic deformations occur in the material within 0.45-0.52 of the pipe wall thickness, which, in the opinion of the inventors, does not cause fears of losing its transverse stability sections from this type of deformation. The bending of the pipe is carried out in the elastic zone, for example, according to the trapezoidal pattern, which is set based on the calculation of creating the maximum elastic deformation in the pipe section with its longitudinal bending.

 The disadvantage of the described method of straightening thin-walled pipes is: the presence of sufficiently long non-straightened ends of the roll when using hyperboloid forms of straightening rolls, the low quality of the straightening with an unstable curvature of the rolling along its length, at which it is necessary to change the eccentricity during the straightening, the possibility of microcracks in the rolled, as in the area of contact of the rolls with the pipe, stress concentration sections arise that can exceed the tensile strength of the rolled material with multiple sign-cutting its bends.

The closest to the purpose and technical nature of the claimed technical solution and the authors have chosen as a prototype is the method of editing round steel, set forth in the invention, "The right machine" (see SU, AS 927367, M CL ³ B 21 D 3/02 , BI, 18, 1982).

 The essence of the method lies in the fact that dressing is carried out by alternating, elastoplastic bending of the rolled metal passing through the right rings, which are eccentrically placed relative to the dressing axis, creating a dressing zone. Before starting editing, the adjustment value of the eccentricities is determined depending on the diameter of the rental and mechanical characteristics. Moving the rental is carried out using a predetermined scheme of the inclination of the rings to the axis of editing, before rotating the drum with the correct rings.

 The disadvantage of the prototype is the difficulty of obtaining high-quality edits, especially of the front end of the rental, since the rotation of the correct rings due to the inability to change their eccentricities is performed when the front end of the rental is found in all rings, thereby the front end of the rental is practically not subject to editing. The use of one editing scheme does not allow qualitatively editing the product mix with a large difference in diameters. When dressing in a drum with three regular rings, only a triangular dressing scheme is possible, and with relatively large diameters of rolled products, the correct rings experience a very high load and microcracks may appear on the surface of the rental with such a scheme. When editing a rental with different curvatures along its length, it is impossible to carry out high-quality editing, since a constantly established eccentricity corresponds to high-quality editing of a rental only with a specific, constant curvature along the length of the rental.

 The basis of the invention is the task: to improve the quality of straightening of the rolling regardless of the change in the initial curvature, to minimize unrepaired sections of the ends of the rolling and to get the surface of the rolling without scratches and microcracks due to the use of various and necessary straightening schemes in the process of editing, with a change in the eccentricities of the correct rings, to ensure the possibility of using the proposed technology in existing and newly built rolling mill workshops.

 The problem is achieved by the fact that in the method of straightening round rolled products, including alternating, elastoplastic bending of rolled products, forcibly rotated, right rings eccentrically placed relative to the straightening axis, creating a straightening zone, having previously determined the nominal value of the eccentricity and moving the rolled steel, using the given scheme of tilting the rings to the axis corrections according to the invention when determining the tuning value of eccentricities take into account the average rolling curvature and distance e between the centers of the correct rings, in the process of straightening the rental, the eccentricities are changed according to the specified program: for the front and rear ends of the rental, use the minimum necessary number of correct rings, group them with the closest possible approximation to each other, while providing the specified ring tilt scheme for moving the rental , set the eccentricity in the group equal to 0.2-0.9 of the tuning value, and for the middle part of the rental, at least four regular rings are used, provide the specified circuit mu their tilt and disperse them along the length of the dressing zone.

 The above set of features of the proposed method for editing round-rent is sufficient in all cases to which the scope of legal protection applies.

 Changing the eccentricities for a given dressing program provides the opportunity, by changing the editing schemes of the rental, to regulate the distribution of bending moments during deformation of the rental. Using the minimum required number of rings makes it possible to choose a rational scheme for editing the front and rear ends of the rental, and in combination with grouping the rings with the closest possible approximation to each other, it is possible to carry out the editing of the rental with the minimum unregulated ends of the rental, and in some cases to exclude unregulated end sections of the rental.

Setting the eccentricity of the rings when editing the front and rear ends of the rental to a value of 0.2-0.9 tuning (e _n ) eccentricity, set depending on the average curvature along the length of the rental and the rigidity of the rental material, is necessary for editing the ends of the rental according to different editing schemes with taking into account the convergence and distance of the correct rings from each other involved in editing the ends of the rental.

By reducing the magnitude of the eccentricity adjusting the eccentricity of at least 0.2 (e _n), the process changes is not possible, since there may be no elastoplastic deformation in the pipe and increase the magnitude of the eccentricity more 0,9e _N may exceed the tensile strength of the material at the deformation end of short sections of steel.

 The method is illustrated in figures 1-19.

In FIG. 1-3 shows diagrams of simultaneous deformations using a straightening machine with four regular rings:
in FIG. 1 - stage editing the front end of the rental, concentrated in the zone L ₁ ;
in FIG. 2 - the stage of editing the middle part of the rental with the rotation of the ring K ₃ , implementing a given scheme of the inclination of the rings;
figure 3 is a stage of editing the rear end of the rental with the rotation of the ring K ₂ .

 Figure 4-6 shows a diagram of the distribution of bending moments during deformation of the rolling in the longitudinal direction along the stages of editing.

7-9 - shows a diagram of deformations with the movement of the regular rings, grouping them in the process of editing;
7 is a diagram of the editing of the front end of the rental, the rings K ₂ , K ₃ , K4 are shifted to the ring K ₁ , forming a zone of editing L _I ;
on Fig - editing scheme of the middle part of the rental, the rings are spaced throughout the editing area L _ZP ;
in FIG. 9 - dressing diagram of the rear end of the rental, the rings K ₁ , K ₂ , K _{3 are} shifted to the ring K ₄ , forming a new dressing zone L _II .

 Figure 10-12 shows a diagram of the moments of bending according to the editing schemes (Fig.7-9).

In FIG. 13-15 - strain diagrams are shown using a straightening machine with six regular rings:
Fig.13 is a diagram of the edits of the front end of the rental;
in FIG. 14 - editing scheme of the middle part of the rental (K ₂ and K ₅ ) - not involved;
on Fig - edit the rear end of the rental.

 In FIG. 16-18 show diagrams of bending moments according to editing schemes (Figs. 13-15).

 On Fig - kinematic diagram of the cassette of the correct machine with the correct ring.

 To implement the method of editing round rolled metal, as an example, a correct machine is proposed, consisting of a block of cartridges (in Fig. 19, one cartridge is shown) placed along the axis of the edit.

 The cassette consists of a housing 1, in which a sleeve 3 with an internal eccentric hole is installed through the bearing assembly 2, in which a cage 4 is placed with an inner surface made in longitudinal section along the radius. A groove is made in the surface 5. The inner surface of the casing 4 is in contact with the ball cage of the regular ring 6. In the ring 6, a working sleeve 8 is placed through the bearing assembly 7, the inner surface of the hole of which is made convex in radius. The gear wheel of the sleeve 3 is engaged with the gear 9 of the drive 10. The yoke 4 is connected by a silent circuit 11 to the drive 12 through an asterisk 13.

 The regular ring 6 has an end face on one side in the form of a sleeve 14, which, through the cracker 15, contacts the eccentric bore in the driven sprocket 16 and which is connected through the noiseless chain 17 and sprocket 18 to the tilt drive of the rings 6.

 The housing 1 is mounted on guides 20 with the possibility of moving the housing 1 along the rolling axis through a screw 21 located on the supports 22, the coupling 23 and the drive 24. The rotation of the correct ring 6 is achieved from the drive 10, setting the eccentricity by turning the cage 4, braking the cage 4 by the drive 12.

 The inclination of the rings 6 relative to the axis of editing, the angle α is carried out by rotating the driven sprocket 16 with an internal eccentric hole, changing the position of the cracker 15, acting on the end sleeve 14 of the correct ring 6.

The way to edit the round hire is as follows. Create alternating elastoplastic bending of the steel by forcibly rotating regular rings 6 (Fig. 19), eccentrically placed relative to the axis of the dressing, creating the dressing zone L _sn (Figs. 1-3, 7-9, 13-15), having previously determined taking into account the pipe stiffness and its initial curvature adjusting eccentricity "e". Moving the rental is carried out using the specified necessary scheme for the inclination of the rings to the axis of editing.

 The editing process is carried out with a change in eccentricities according to a given program. Changing the eccentricities "e" is carried out by turning the cage 4 (Fig.19), braking or increasing the speed of rotation of the drive 12.

 When editing the front end 2 (Fig. 1), the hire is defined by rollers 3 (Fig. 1, 7) and the minimum number of regular rings 6 (Fig. 19) is used with the closest possible approach to each other, taking into account the structural capabilities and mechanical characteristics of the product edits. Set the inclination of the rings 6 in this group according to a given pattern, necessary for the forced movement of the rental along the axis of editing.

 The inclination of the rings 6 relative to the axis of editing by the given angles ± α is carried out, for example, by turning the driven sprocket 16 (Fig. 19) with an internal eccentric hole, changing the position of the cracker 15 acting on the surface of the end sleeve 14 of the regular ring 6.

 Set in the group of rings 6 the eccentricity equal to 0.2-0.9 of its tuning value.

When editing the middle part of the rental 2 (figure 2) use at least four regular rings 6, dispersing them ( _figure 2, 8, 14) along the length of the editing zone L _ZP. The eccentricity is set to the tuning value.

The dispersion of the rings 6 along the length of the dressing zone L _sn can be carried out by moving the casing 1 of the cassette (Fig. 19) with the correct ring 6. The movement is carried out by the actuator 24 using the screw 21 and installing the housing 1 on the guides 20. The dispersion of the correct rings 6 can be carried out selectively using certain rings in the dressing zone (FIG. 14).

When editing the rear end of the rental, as well as the front, use the minimum number of regular rings (Fig.3,9,15) with the maximum approximation to each other, forming the editing zone L _II . Similarly, as when editing the front end of the rental, the eccentricity is reduced to a value equal to 0.2-0.9 tuning.

Method embodiments
Option I. Assume that the total number of regular rings in the correct machine is four.

The front end of the rental 2 (figure 1) is set and the correct rings K ₁ , K ₂ , K ₃ (figure 1) participate in the work. The eccentricities of the rings are respectively e ₁ , e ₂ , e ₃ , the relative eccentricity is formed between the middle ring K ₂ and the extreme rings K ₁ and K ₃ . The eccentricities e ₁ , e ₂ , e ₃ are 0.2-0.9 adjusting eccentricities of the rental editing process. Tuning eccentricity is the value at the average value of the curvature of the rental, taking into account its rigidity and the distance between the centers of the regular rings 6 (Fig. 19). Editing the front end 2 of the rental is carried out according to the distribution of bending moments (figure 4), i.e. according to the triangular editing scheme, in the zone L _I.

Moving the rental is carried out by rotating the rings K ₁ K ₂ K ₃ , while the ring K _{3 is} rotated and set to an angle (-α), providing the necessary scheme for tilting the rings 6.

After the front end of the rental 2 (Fig. 2) falls into the fourth regular ring K ₄ , the ring K _{3 is} tilted at an angle (+ α) so that the middle rings K ₂ and K ₃ are installed parallel to each other. The eccentricities e ₁ , e ₂ , e ₃ , e _{4 of the} rings K ₁ , K ₂ , K ₃ , K _{4 are set} by an amount equal to e _n - adjustment taking into account the distances between the rings (in this embodiment, the distance did not change, and e ₁ , e ₂ , e ₃ , e ₄ = e _n . Editing the middle end of the rental are trapezoidal (figure 5).

After the rear end of the rental 2 (Fig. 3) exits from the first straightening of the regular ring K _1, the K ₂ ring is tilted by an angle (+ (+ α),), providing the tilt scheme specified for the group of rings K ₂ , K ₃ , K ₄ , the eccentricity of e ₂ , e ₃ , e ₄ change, reducing it to 0.2-0.9 e _n . The editing zone for this group of rings is L _II . After the exit of the rear end of the rental from the ring K ₂ include rollers 4 for forced movement of the rental.

If during the editing process, the curvature along the length of the rental changes above the average, then when editing the middle part of the rental, the eccentricities of the rings K ₁ , K ₂ , K ₃ , K _{4 are} changed taking into account the change in the curvature of the rental.

где Δρ - изменение радиуса кривизны,
ρ - радиус кривизны,
L_зп - длина зоны правки (расстояние между крайними правильными кольцами).The magnitude of the change in eccentricity can be determined from the expression:

where Δρ is the change in the radius of curvature,
ρ is the radius of curvature,
L _sn - the length of the dressing zone (the distance between the extreme right rings).

Option II
Let the correct machine has a sufficiently long dressing zone L _sn (Fig. 7-9). Then, when setting the front end of the rental, the rings K ₁ , K ₂ , K ₃ , K ₄ are grouped in the zone L _I (Fig. 7) by moving the regular rings along the guides along the editing axis. Editing the front end is carried out in four rings with eccentricities e ₁ , e ₂ , e ₃ , e ₄ equal to 0.2-0.9 e _n , according to the trapezoidal editing scheme (figure 10).

After the front end of the rolled product passes through the fourth ring K ₄ , the rings K ₂ , K ₃ and K _{4 are} moved along the guides at a speed equal to the speed of the rolled _car , until they are uniformly dispersed throughout the entire zone L _{cp of} dressing, changing - increasing the eccentricity evenly at this time rings K ₁ , K ₂ , K ₃ , K ₄ to the tuning, taking into account the increase in the distance between the rings. Editing is carried out according to the trapezoidal pattern and L _sn ( _figure 10).

где ΔL - изменение расстояния между правильными кольцами;
е_н - настроечная величина эксцентриситета.The magnitude of the eccentricity depending on the change in the distance between the rings (L) can be determined by the expression:

where ΔL is the change in the distance between the regular rings;
e _n - tuning value of eccentricity.

After the exit of the rear end 2 of the rental (Fig. 9) from the transporting roller 3, the rings K ₁ , K ₂ , K _{3 are} moved to the ring K ₄ with the speed of movement of the rental and are grouped in zone L _II with the closest possible proximity to each other. Editing is carried out according to the scheme (Fig. 12). After the rear end of the rental exits the ring K ₁ , the pulling rollers 4 are connected to work.

Option III. The straightening machine has six regular rings (FIGS. 13, 14, 15). When editing the front end 2 (Fig.13) use rings K ₂ , K ₃ , K ₄ , K ₅ . The rings K ₁ and K ₆ have an eccentricity of zero. The eccentricity of the rings K ₂ , K ₃ , K ₄ , K ₅ is equal to 0.2-0.9 e _n - tuning. Editing the front end is trapezoidal in the zone L _I (Fig. 16). (There is no need to change the angle of inclination according to the scheme necessary for moving the rental).

After exiting the front end of two products (14) from the K ₆ eccentricities change in K _1, K _3, K _4, K ₆ and tuning, the eccentricities of the rings K ₂ K ₅ are set to zero, i.e. they are not involved. Thus, the distance between the extreme rings K ₁ and K _{6 is} increased with respect to the middle rings K ₃ K ₄ . Editing is carried out according to the trapezoidal scheme 17. Increasing the distance between the rings K ₁ and K ₃ and K ₄ and K ₆ , increase the eccentricity above the adjustment.

After the tail end of the rolled ring K ₁ change eccentricities in the rings K ₂ K ₃ K ₄ K ₅ to a value of 0.2-0.9 e _n, and in the ring _6, the eccentricity is zero (15).

The process of editing the rear end of the rental is conducted according to the trapezoidal editing scheme (Fig. 18) with the length of the editing zone L _III .

After the rear end of the rental exits the K ₂ ring, pulling rollers 4 are used.

A specific example of the method
A pipe with an outer diameter of 114.3 mm and a wall thickness of 6.883 mm is assigned to the correct machine, which consists of 4 regular rings. The pipe material has the following mechanical characteristics:
- modulus of elasticity E = 2.1 • 10 ¹¹ Pa;
- yield strength σ _T = 760 MPa;
- tensile strength σ _B = 862 MPa;
- elongation corresponding to tensile strength, δ _B = 0.15.

 The inner diameter (diameter of the working surface) of the correct rings (inner diameter of the working sleeve 8 - Fig.19) is equal to 150 mm The average curvature of the front end of the pipe is 10 mm / m (radius of curvature ρ = 12,505 m).

Rings K ₁ K ₂ K ₃ K ₄ (figure 1) set as close as possible to each other. The distance between the centers of the rings is 300 mm. Slope of the rings: K ₁ (+ 5 ^o ); K ₂ (- 5 ^o ), K ₃ (+ 5 ^o ); K ₄ (+ 5 ^o ).

Eccentricity of rings e ₁ (K ₁ ) = - 8.5 mm; e ₂ (K ₂ ) = + 8.5 mm; e ₃ , (K ₃ ) = - 8.5 mm, i.e. relative eccentricity of e ₂ with respect to e ₁ , e ₃ = 17 mm Editing occurs when the front end of the pipe is simultaneously in 3 rings, K ₁ K ₂ K ₃ . When the front end of the pipe reaches the correct ring K ₄ using the control system of the correct machine, the following operations are simultaneously performed.

The angle of inclination of the ring K _{3 is} set to a value (-5 ^o ). The eccentricities of the rings K ₁ K ₂ K ₃ K ₄ set in the following values:
e ₁ = -12 mm; e ₂ = + 12 mm; e ₃ = + 12 mm; e ₄ = -12 mm.

Relative eccentricities e _2- e ₁ = 24 mm and e _2- e ₄ = 24 mm. This eccentricity corresponds to the tuning value with the above mechanical characteristics and the curvature of the rental.

When you exit the correct ring K _{1 the} rear end of the rental (figure 3) perform the following actions:
- the angle of inclination of the ring K ₂ set to a value (+5 ^o );
- eccentricity of the rings e ₂ = -8.5 mm; e ₃ = + 8.5 mm; e ₄ = -8.5 mm.

 The process of dressing the rear end are trapezoidal dressing scheme (Fig. 6).

 The proposed invention can be used in existing and under construction workshops of rolling mills for straightening pipes of various diameters, as well as other round rolled products.

 According to the proposed technology, when the correct elements are rings with adjustable eccentricity during the dressing process, it was possible to reduce the dimensions of the correct machine, reduce energy consumption and achieve high quality dressing rental.

Claims (1)

 The method of straightening round rolling by alternately alternating, elastoplastic bending of the rolling forcibly rotated regular rings creating an editing zone eccentrically relative to the straightening axis, preliminarily determines the tuning value of the eccentricity of the rings depending on the diameter and stiffness of the rolling and sets a predetermined pattern of inclining the rings to the straightening axis to move the rolling, characterized in that when determining the tuning value of the eccentricities take into account the average curvature of the rental and the distance between the centers of the correct rings, and in the process of editing the rental, the eccentricities of the rings are changed according to a given program: for the front and rear ends of the rental, use the minimum necessary number of correct rings, group them with the closest possible approximation to each other with a given ring tilt pattern to move the rental , set the eccentricity in the group equal to 0.2-0.9 of its tuning value, and for the middle part of the rental use at least four regular rings, dispersing m along the length of the zone changes, and provide a predetermined circuit of inclination.

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