CN104475459B - Improve the control method of pierced shell rolling quality - Google Patents

Abstract

The present invention provides a kind of control method improving pierced shell rolling quality, and this control method is to adding control hollow billet tail end stable rolling technique in two roller oblique milling piercing mill of seamless steel tube rolling mill practice the second halfs；Concrete control method step is: steel is stung in base speed end；The establishment of hollow billet tail end rolling start time point；Hollow billet tail end rolling slope controls the output of speed preset.It is safe and reliable, reasonable in design that effect of the present invention is that novel process and mathematical model control; improve the serviceability of three roller arrangements after roll mill; fault rate is decreased obviously; product lumber recovery more than 1% can be improved; reduce equipment failure rate 80%; reduce equipment maintenance cost, improve running rate, be conducive to optimizing protective measure and extend the service life of motor.Through nearly practice test more than a year, achieve extraordinary effect；Reduce loss, many wound benefits year more than 12,000,000 yuan.

Description

Improve the control method of pierced shell rolling quality

Technical field

The present invention relates to pierced shell rolling process, particularly a kind of control method improving pierced shell rolling quality, the technique changing tradition steel rolling, it is achieved the tail end stable state in the perforating steel pipe operation of rolling uniformly rolls.

Background technology

In seamless steel tube production process, application piercing process is very economical.The Mannesmann brother of Germany in 1886 has applied for producing the patent of tubular sections product with cross roll perforating machine.Described in document, the effect of internal forces and use two or more tapered roll to bore a hole during flow of metal, is therefore referred to as mannesmann piercing process.

In seamless steel tube production, perforation process be by solid heating after pipe wear into hollow hollow billet.Perforation is as the first operation of flow of metal, and the pipe wall thickness passed is thicker, length is shorter, surfaces externally and internally is second-rate, is commonly called as hollow billet.But usually require that the hollow billet physical dimension rolled out meets the requirements and smooth outer surface, and there is corresponding punching rate and rolling cycle, to adapt to the rhythm of production of whole unit.If there are some defects on hollow billet, the operation through below also is difficult to eliminate or alleviate.So extremely crucial in steel pipe's production middle punch operation, the quality of perforation quality is directly connected to whether the technique of next procedure can normally perform and the height of end product quality.For this, piercing process is proposed following 3 requirements by spy:

(1) first having to the hollow billet uniform wall thickness ensureing to pass, ovality is little, and geometric accuracy is high.

(2) secondly, the surfaces externally and internally of hollow billet is smooth, must not scab, the defect such as folding, crackle.

(3) finally there are corresponding punching rate and rolling cycle, to adapt to the rhythm of production of whole unit, make the finishing temperature of hollow billet disclosure satisfy that the requirement of tandem rolling tube machine.

Current seamless steel tube production middle punch technique is more reasonable, and perforation procedure achieves automatization.

1, two roller Mannesmann piercing mill perforation procedure and perforation kinematics analysis

The 1.1 whole processes of roll piercing

The whole process of roll piercing can be divided into three phases

First erratic process--pipe forward metal is gradually filled with the deformed area stage, and namely pipe comes into contact with forward metal with roll and goes out deformed area, and this stage exists once nips and secondary is nipped.

Stable process--this is perforation procedure Main Stage, initially moving off deformed area from the full deformed area of pipe forward metal to pipe tail end metal.

Second erratic process is that pipe tail end metal leaves deformed area all leaves roll to metal gradually.

Stable process and erratic process have obvious difference, and this is readily observed aborning.As on a hollow billet end to end size and intermediate sizes just have difference, be usually hollow billet point diameter big, tail end diameter is little, and mid portion is consistent.Dimensional discrepancy is greatly one of erratic process feature end to end.The reason causing head diameter big is: forward metal is in being gradually filled with deformed area, metal is gradually increased with the frictional force on roll contact face, maximum is just reached to being completely filled with deformed area, particularly when meeting with top in pipe front end, due to the axial resistance come directly towards, metal is subject to resistance to axially extending, axially extending deformation is reduced, and transversely deforming increases, adding does not have outer end to limit, thus causing that point diameter is big.Tail end diameter is little, is because pipe tail end when being started to penetrate by top, and top resistance is decreased obviously, it is easy to extensional, and laterally exhibition is rolled little simultaneously, so external diameter is little.

The front card occurred in production, rear card are also one of unstable features, although three processes are otherwise varied, but what they realized in same deformed area.Deformed area is to be made up of roll, top, godet (guide plate).As Figure 1-1, whole deformed area is a more complicated geometry, and substantially it is believed that transverse section is oval, having the top stage to centre is a cyclic deformation district.Longitudinal section is two cones connecting of handle, middle inserts an arc top.

Deformed area shape decides the deformation process of perforation, and changing deformed area shape (determining and tool design and adjustment of rolling mill) will cause the change of perforation deformation process.Perforation deformed area is broadly divided into four sections, as shown in Figure 1-2.

Ith district is referred to as perforation area in preparation, (rolling filled circles pipe district).The Main Function in Ith district is to prepare for perforation and realize secondary smoothly to nip.The deformation characteristics of this section is: owing to roll approach cone surface is tapered, diametrically compressed gradually along the progressive pipe in perforation side, the part metals compressed is a part of to horizontal mobility, its blank corrugated is become oval by circle, a part of metal axial extends, mainly make coating metal deform upon, therefore form the depression of " horn mouth " shape in blank front end.This depression and internal point ensure that the nose center to preformed body, top, thus the wall unevenness of hollow billet front end can be reduced.

IIth district is called punch block, and the effect in this district is perforation, is namely become hollow hollow billet by solid billet, and the length in this district starts to the circular cone band of top for meeting from metal and top.This section deformation characteristics is mainly wall thickness pressure, owing to the spacing of roller surface with surface, top is gradually reduced, therefore hollow billet wall thickness is while rotating, while pressure, therefore being continuous rolling process, the deformation parameter of this section represents with diameter relative reduction, the metal being diametrically depressed, can be subject to the interception of godet equally to horizontal mobility (expanding) and longitudinal flow (extension) but transversely deforming, longitudinal extension deformation is main.The effect of godet is possible not only to restriction transversely deforming but also metal can be pulled to axially extending, due to the result of transversely deforming, cross section ovalize.

IIIth district is called rolloff district, and the effect in this district is rolloff expansion, improves tube wall dimensional accuracy and surfaces externally and internally quality, due to top bus and roll bus less parallel, so drafts is only small, acts primarily as expansion effect.Rolled piece cross section is also oval at this section, and is gradually reduced.

IVth district is called circle area.The effect in this district is oval hollow billet, is gradually reduced drafts diametrically to zero by the roll rotated, and hollow billet is turned round, and this section length is very short, is actually without coming directly towards hollow hollow billet plastic bending deformation in the deformation of this district, and deformation force is also only small.

In deformation process, four sections connect each other, and carry out simultaneously, and metal cross section deformation process is to be returned round process again by circle variation ellipse, sees Fig. 1-3.

1.2 roll piercing kinesiologys

Piercer roll is that same direction rotates, and the relative milling axis of roll mandrel tilts, and intersects an angle and is called advancing angle.When circular pipe blank is sent in roll, by the frictional force effect between roll and metal, roll drives circular pipe blank hollow billet to reversely rotate, existence due to advancing angle, pipe hollow billet rotate while to moving axially, in deformed area, on pipe hollow billet surface, every bit is all screw, namely rotates, while advancing.

The basic parameter of performance screw is: the shift value (pitch) of tangential motion speed, axially-movable speed and the every half way around of roll.

First analyze the speed of any point on roll, if roll speed is VR, then can be decomposed into two components (tangential component and axial component).

The tangential rotary speed (1) of VaR=VRCOS β=π DNb/60 × COS β------

VtR=VRsin β=π DNb/60 × Sin β-----axial velocity (2)

The roller diameter in the discussed cross section of D----, mm in formula；

Nb----roll rotational speed, rpm；V β----nip angle.

Owing to blank drives by roll in the operation of rolling, corresponding speed is passed to pipe by roll, then pipe speed is: VB=π DNb/60 × COS β (3)

But actually the speed of rolls and metal speeds are not essentially equal.Common metal movement velocity, less than the speed of rolls, namely produces sliding between the two, can represent both speed with slip coefficient, so

VaR=π DNb/60 × COS β × η τ (4)

VtR=π DNb/60 × sin β × η 0 (5)

In formula: η τ---tangential slip coefficient,

η 0---axial slip coefficient, both are less than 1.

Different materials has different slip coefficients, such as carbon steel: η 0=0.8～1.0, low-alloy steel: η 0=0.7～0.8, high-alloy steel: η 0=0.5～0.7.

Be of practical significance most aborning be hollow billet that speed when leaving roll it can be seen that muzzle velocity is bigger, productivity ratio is also higher.In order to simplify calculating, generally assuming that roll exit speed is equal to VtR, actual error is included in slip coefficient.

Hollow billet leaves any axial slip coefficient of roll can obtain axial velocity with formula (2), the aperture time of theory is drawn divided by hollow billet length, comparing with the elapsed time, namely η 0=T reason/T is real again. and after so determining η 0, then can calculate hollow billet and leave the axial velocity of roll.

Pitch is variable value in deformation, and increases along with pipe enters deformed area degree and increase, and this is caused by owing to pipe-hollow billet basal area constantly reduces, axial flow velocity is continuously increased.

Hollow billet leaves any pitch computing formula of roll:

T=pi/2 × η 0/ η τ × d × tg β (6)

In formula: d----hollow billet diameter

The bite condition of 1.3 perforation

Roll piercing process also exists twice and nips, and first time nips and is pipe and roll comes into contact with moment, roll drive pipe motion that pipe is drawn in deformed area.When metal enter deformed area to and top meet, overcoming the axial resistance of top to go successively to deformed area is that secondary is nipped.Condition that general satisfaction is once nipped also may not be certain just can meet secondary bite condition.We usually see aborning, and due to axial resistance effect when secondary is nipped, forward travel stops and rotating and continue and namely skid.

1.3.1 a bite condition

Once nip and should meet pipe blank rotary condition and meet axial advancement condition again.

The power energy condition that pipe is nipped is determined by following formula:

Mt≥Mp+Mq+Mi(7)

In formula: Mt-makes the resultant couple of pipe blank rotary

The prevention blank turning moment that Mp produces due to pressure

The moment of friction that Mq produces in pipe rear end due to pusher thrust

The moment of inertia of Mi pipe blank rotary

If ignoring Mq, Mi (being worth only small), general expression formula is:

N (Mt+Mp) >=0 (n roll number) (8)

Advance bite condition refers to pipe axial force balance condition, it is, the axial force drawing into pipe should be greater than or equal to axial resistance, its expression formula is:

n(Tx-Px)+P′≥0(9)

In formula: each roll of Tx acts on the axial friction on pipe

The each roll of Px--acts on normal pressure axial component P ' back pressure (being generally zero) on pipe

Once nip required rotating condition

Equation below shows the balance of power when pipe is nipped, two important parameters, and coefficient of friction and angular velocity can be calculated by formula below.

$\mathrm{\μ}\≥\tan \mathrm{\ω}+\frac{\sin {\mathrm{\α}}_e}{\tan \mathrm{\γ}\cos \mathrm{\ω}}$

$\mathrm{\ω}=\arccos \frac{\mathrm{Dw}-\mathrm{\Δd}}{\mathrm{Dw}}---\left(10\right)$

In formula: α_eRoll entrance cone angle

The diameter tube reducing value at γ nip angle Δ d roller larynx place

If thinking, pipe is nipped smoothly, it is possible to nip angle becomes entrance cone angle big, roll less, or by applying the push-on force of pipe and strengthening the roller flower degree of depth of roller surface.

1.3.2 two bite conditions

The power energy condition that secondary is nipped

Secondary middle rotating condition of nipping adds the inertia resistance square of a top/ejector rod system than once nipping, and its value is only small.Therefore secondary is nipped rotating condition, substantially and once nips identical.That secondary is nipped it is crucial that advance condition.

The equilibrium condition of axial force when secondary is nipped:

n(Tx-Px)-Q′≥0(11)

In formula: Q ' comes directly towards the axial resistance of nose

Secondary is nipped required rotating condition

The condition that secondary is nipped is greater than the frictional force come directly towards with between pipe and roll at the push-on force of axial pipe, and can realize the premise that secondary nips is that (x=drift) pipe at least to rotate a circle before pipe contact top.

X=π * d_B*tanγ

(12)

In formula: dB pipe diameter

2, flow of metal during roll piercing

2.1 pipe stressing conditions

Fig. 2-1 shows the stressing conditions of pipe, shows the power that F is roll direction (plane) in figure, and for compressive stress, the position display at contact point is maximum.Centre (godet direction) is shown as tension, and the centre stress at godet is maximum in theory.Because the continuous rotation of pipe, the stressing conditions at same position is continually changing, and causes that the metal in centre is subject to the effect of alternate stress, and center produces loose, forms vestibule.

2.2 flows of metal

Basic deformation is entirely the change of physical dimension, unrelated with the character of material, and basic deformation depends on the geometry (being determined by tool design and adjustment of rolling mill) of deformed area.

Additional deformation refers to the deformation of material internal, be directly perceived less than deformation, additional deformation, caused by internal stress in material, is the distortional stress increasing material, cause the defect produced in material, so it is critically important for how reducing additional deformation in actual production.

2.2.1 basic deformation

Basic deformation and extensional, tangential deformation and radial deformation (wall thickness compression).These three deformation is all macroscopic deformation, represents face shaping and change in size.Basic deformation can be represented by the formula:

Radial strain increment:

Longitudinally (extension) strain increment:

Tangentially (circumference) strain increment:

2.2.2 additional deformation

Additional deformation includes torsional deflection, longitudinal shear deformation etc., additional deformation is the uneven generation of deformation due to metal each several part, additional deformation can bring a series of consequence, as caused strain energy of distortion to increase, and the additional stress caused by additional deformation, it is easy to cause on hollow billet surfaces externally and internally and inside produces defect etc..Longitudinal shear deformation causes mainly due to the axial resistance come directly towards, roll drives tubing axially to flow on the one hand, and come directly towards and to stop metal axial to flow, ultimately result in the flowing of each metal axial variant, each layer metal interknits again, it is an entirety, so necessarily leading to additional deformation and additional stress at each layer intermetallic, the surface layer metal particularly directly contacted with roll, top, be can be seen that by figure, larger, therefore hollow billet surfaces externally and internally is easy to occur defect or makes the original development of defects in pipe surface expand additional deformation.Tangentially cutting deformation causes hollow billet surfaces externally and internally to produce one of defect cause (such as defects such as crackle, folding, absciss layers) often.

In original control process, often produce pierced shell infolding, scab, the having of the prevailing quality accident such as lose flesh:

(1) the rolling parameter adjustment impact on infolding defect

The size of roll rotational speed is that result shows according to multifactor designs such as strand material, lengthening coefficient, slip coefficient and roller footpath sizes: high rotating speed is more readily formed infolding, reduces rotating speed, and infolding reduces accordingly.Mainly increase roll rotational speed of tracing it to its cause will cause that sliding increases, and namely axially efficiency reduces, and pipe increases in the section of nipping number of revolutions, form the probability increasing of infolding.Result of the test determines the adjustment direction of perforating machine: use big nip angle, reduces along with nip angle strengthens pipe sliding, and the reduction of sliding can reduce pipe and nip required number of revolutions.The comprehensively experience of external producer, nip angle advance efficiency when 10～12 degree is best, but still uncontrollable tail end hollow billet stable rolling, reducing rolling stable state height rotating speed is also effectively control infolding method, but the method to sacrifice rhythm of production, reduces production efficiency.

(2) impact of raising speed ratio

The effect adopting raising speed ratio is roll low speed rotation, is conducive to pipe steadily to nip, and after nipping, high-speed rolling throws steel at a high speed.General by 30% setting, in production depending on roll wear situation frequently be 40% or 45%, experimental result show: adopt the infolding amount that the raising speed of 30% produces than perforation lower than adopting 45% raising speed infolding amount than perforation generation.Rationale is, in low speed bite stage and high-speed rolling stage, the two speed difference is little, and the deformation condition of strand is close.It is to say, when low speed changes to high speed, metal flow can smooth transition.If the two speed difference is big, flow of metal produces fluctuation and is easy for producing large stretch of infolding.This infolding 400～500MM place, hollow billet front end that is everlasting finds, the method is also intended to sacrifice rhythm of production, reduces under production efficiency premise just realization.

In addition, other quality accidents of also often generation and having of equipment breakdown:

(1) to individual product specification, it is easy to cause rolling hollow forging outer wall to produce " scabbing " phenomenon, produce quality of lot accident；

(2) easily generation " blocking after main frame " production accident in adjustment process is produced；

(3) hollow forging tail end wall thickness control is unstable, cause back-end crop length to increase, cause waste.

(4) production process is easily generated " the ferrum ears or side handles of a utensil ", causes bigger waste, and cause very big impact to normal rolling, it is necessary to clear up timely, bring great inconvenience to normal production work.

(5) during tail end rolling, perforation mair motor throwing steel speed moment raises rapidly, makes throwing steel electric current promote rapidly, engine commutator is produced " surge " and impacts, and often makes diverter produce to destroy；Regularly maintenance timely is needed to process.

(6) rising of steel rolling speed thrown by perforating machine at afterbody, three roller arrangements after machine is produced bigger vibrations so that it is fragile, as shown in Fig. 2-2,2-3.

(7) through practice have shown that for many years, by the mode of " centering of afterbody flame cutting ", it is possible to above-mentioned situation is obtained certain alleviation；But monthly need to increase the consumption of corresponding acetylene gas, oxygen, and artificial recruitment cost, the monthly expense of nearly 80,000 yuan, and there is certain production safety hidden danger.

Summary of the invention

The present invention provides a kind of control method improving pierced shell rolling quality, what solve traditional two roller roll piercing units rolls the moment throwing steel raising speed phenomenon that hollow forging is about to penetrate, hollow forging afterbody is effectively controlled in milling train when hollow billet rolling is nearly completed, avoid the shake of rolling, reduce varied products' quality accident and equipment breakdown.

For achieving the above object, the technical solution used in the present invention is to provide a kind of control method improving pierced shell rolling quality, and this control method is to adding control hollow billet tail end stable rolling technique in two roller oblique milling piercing mill of seamless steel tube rolling mill practice the second halfs；This technique is that in the high-speed rolling control program segment that the one-level basic automatization by controlling for the unit controls program PLC, editor adds hollow billet tail end stable rolling mathematical model and realizes；AMS procedure logical control system PLC system for the ANSALDO electric corporation of one-level basic automatization employing Italy that the unit controls.

Concrete control method step is as follows:

(1) steel is stung in base speed end

Perforation unit roll runs under base speed state, wait pipe supplied materials, nipped pipe by base speed, that is: steel is stung in base speed end, realize base speed steady operational status to first instability and sting the process of steel state, according to different grade of steel kinds, it is differentiated that base degree of hastening is set, and base speed is set to the 70-80% being generally stable state high-speed rolling speed；

(2) stable rolling in the middle of high speed

Perforation unit detects unit at top and bottom rolls equipped with independent roll-force instrument, in order to detects in time and stings steel signal and throw steel signal, and provides foundation for technologist's Reasonable adjustment device parameter；After perforation main frame rolling force sensor detects and stings steel signal, when more than 50 tons of roll-forces, detect unit by roll-force instrument and send the switching value actuating signal I0443=1 speed controlling program to the one-level basic automatization PLC system of perforating machine, perforation main frame raising speed enters high speed steel rolling state, it may be assumed that high speed intermediate rolling；

(3) mathematical model controls hollow billet tail end stable rolling technique

When be arranged on the roll-force instrument above piercer roll detection unit detect pipe sting steel signal after, perforation main frame raising speed enter high speed steel rolling state；In fully automated as-rolled condition, and no longer carry out any device parameter when adjusting, start automatically to carry out that hollow billet is pure rolls time data collection；Change once any as-rolled condition having control mode or rolling parameter, when will re-start that hollow billet is pure to be rolled

Between data acquisition, the main contents of as-rolled condition change include manually or the switching of semiautomatic control mode, roll rotational speed, roll drafts, pipe length adjustment；Gather compared with first three hollow billet pure time of rolling takes that average is pure with Theoretical Calculation hollow billet and roll the time by steady and continuous, whether normal to judge rolling, when continuous first three hollow billet is pure roll time average be not less than that Theoretical Calculation hollow billet is pure rolls the time time, it is good that devices illustrated runs as-rolled condition, controls hollow billet tail end stable rolling explained hereafter by starting to control the mathematical model of new edited in program PLC according to one-level basic automatization from the rolling of next hollow billet.

Newly-built mathematical model control to be built upon the second half of hollow billet high-speed rolling process close to an end rolling time automatically implement, it first has to determine hollow billet tail end rolling start time；Secondly, design hollow billet afterbody starts to roll the moment to rolling the speed controlling being fully completed period, to complete effectively to throw steel, it is achieved the steadily rolling to pipe afterbody, and concrete grammar is:

) the pure calculating rolling the time of hollow billet

The pure time of rolling of oblique milling refers to that rolled piece is played, by end in contact roll before pipe, the hollow billet tail end shut out by the time needed for deformed area and leaves roll interval only:

$T=\frac{l+L}{{\mathrm{\η}}_x\frac{\mathrm{\π}{D}_1{n}_r}{60}\sin \mathrm{\α}}---\left(16\right)$

In formula: l asynchronous region length；L hollow billet length；

T is pure rolls the time；η_xThe coefficient that slides axially of Outlet Section；

D₁Roller diameter on Outlet Section；n_rThe rotating speed of roll；α feed angle

) hollow billet tail end rolling start time point Tn establishment

Tn=T-Ta (17)

In formula: the time point Tn of Tn hollow billet tail end roll control；T is pure rolls the time；

Ta afterbody rolling time, this time point is variable, is adjusted according to rolling different kinds；

Supplied materials pipe state owing to rolling pierced shell has length difference, now, the milling train pressure-measuring head Real-time Collection effectively omnidistance steel rolling time will be utilized, and effective rolling time sum of first three hollow billet of continuous acquisition, average again, it is actually active average rolling time Tm during continuous rolling state, as Tm > T

Tn=Tm-Ta (18)

In formula: the time point Tn of Tn hollow billet tail end roll control；

The actually active average rolling time Tm of Tm；

) control of hollow billet tail end mill speed

When drilling/rolling process enters the time point Tn of hollow billet tail end roll control, being about to carry out the tail end to hollow billet and roll, now, perforation milling train rotation speed control program is automatically into hollow billet tail end roll control, until returning to perforating machine base speed rotating speed after throwing steel；The computing that perforating machine hollow billet tail end roll control is proportionally integration completes, and is export according to slope curve form to realize speed controlling；

The theoretical expression of mathematical model is:

△ V=∫ (Vmax-Vmin) dt (19)

Steel rolling maximum speed value Vmax, base hastens angle value Vmin, afterbody rolling time value t=Ta, and control method is, the program scanning cycle is set to Tsac=5ms, and speed maximum is steel rolling speed Vmax, and minima is base degree of hastening Vmin_,, afterbody rolling time is set to t=Ta, so programme-control is to be divided into the N=Ta/Tsac time period according to by afterbody rolling time Ta according to program scanning cycle T sac, each time period performs the variable quantity of △ V=(Vmax-Vmin)/N, if the speed during detection n-th scan period should be Vn, Vn=Vmax-n* ((Vmax-Vmin)/N, due within the afterbody rolling time time period at most 5 seconds program scanning cycle, perforation motor mill speed is made up of nearly 1000 speed Vn, difference of successively decreasing each other is △ V, actual monitored speed output effect is slope curve form；

The time point Tn of hollow billet tail end roll control is when rolling pipe distance tail end also surplus 30cm place, starts to perform numerical control tail end stable rolling, both ensure that the stability throwing steel rolling, met again the requirement of production process and rhythm of production.

The effect of the present invention is to adopt this control method to set up mathematical control model by electricians to control rolling process, through nearly practice test more than a year, achieves extraordinary effect；Reduce loss many wounds benefit year at more than 1,200 ten thousand yuan,

Direct economic benefit:

(1) raising of product quality

Perforation is thrown steel steady state process control program and is mainly aiming at inside hollow billet afterbody wall thickness and hollow billet afterbody ferrum ears or side handles of a utensil entrance hollow billet to cause inner surface to lose flesh and design.

Improve product lumber recovery every year at least more than 1% o'clock by this project implementation, produce 850000 tons of high-quality seamless steel pipe, 1000 yuan of calculating of high-quality seamless steel pipe profit per ton per year for our factory in 2013

Much annual wound benefit is: 850000 tons of * 0.01*0.1 ten thousand yuan=8,500,000 yuan

(2) original " centering of afterbody flame cutting " technical process is reduced

Eliminate original " centering of afterbody flame cutting " technique, the annual consumption reducing the materials such as corresponding acetylene gas, oxygen, and artificial recruitment cost by this project implementation, reduce cost at least 90 ten thousand yuan.

(3) impact of disorderly closedown

Reduce " blocking after main frame " every year by this project implementation, cleaning is easily generated production accidents such as " the ferrum ears or side handles of a utensil " and shuts down at least 6 hours；Equipment fault is shut down at least 8 hours, calculates with minimum 45 seconds discharging machines of rhythm of production, and annual few (6+8) * 60*60/45=1120 that produces props up steel pipe, 1.5 tons every, 1000 yuan of calculating per ton, annual loss 1.5*1120*0.1=168 ten thousand yuan

(4) annual at least 120 ten thousand yuan of equipment fault equipment maintenance cost, recruitment cost

Therefore, by this project implementation, annual many wound benefits, more than 8,500,000 yuan, reduce various cost payout or are lost in 90+168+120=378 more than ten thousand yuan

Economic results in society: by this project implementation, obtain on experiential basis in summary, at present this technology controlling and process tries to shift onto other units such as " the 460 large-sized seamless steel pipe factory ", " 258 seamless steel tubing mill " within our company, all achieves good economic benefit and social benefit.

Accompanying drawing explanation

Fig. 1-1 roll piercing deformed area pass figure；

Fig. 1-2 bores a hole four sections in deformed area；

Fig. 1-3 rolled piece cross section variation diagram；

Fig. 1-4 velocity diagram；

Fig. 2-1 metal force analysis figure；

The original rolling process curve of Fig. 2-2；

The original rolling process speed of Fig. 2-3/time Real-time Collection curve；

Fig. 2-4 is the rolling process curve of the present invention；

Fig. 2-5 is the rolling process speed/time Real-time Collection curve of the present invention；

Fig. 3-1 is the functional control module of the present invention；

Fig. 3-2 is the rolling mill practice mathematical model structure chart of the present invention.

Detailed description of the invention

In conjunction with accompanying drawing, the control method improving pierced shell rolling quality of the present invention is illustrated.

The original process control procedure of comprehensive analysis, in the three phases of the whole process of roll piercing,

First erratic process-----pipe forward metal is gradually filled with the deformed area stage, namely once nips and secondary is nipped, it is possible to eliminate first erratic process by suitably adjusting trying one's best of rolling parameter.

Stable process-----this be perforation procedure Main Stage, be full of deformed area initially moves off deformed area to pipe tail end metal from pipe forward metal.

Second erratic process-----is left deformed area all leaves roll to metal for pipe tail end metal gradually, and this process generally can not eliminate by adjusting parameter.

The control method improving pierced shell rolling quality of the present invention is primarily directed to traditional two roller oblique milling piercing mill of seamless steel tube rolling mill practices and supplements with perfect to new improvement.That is: original rolling mill practice-----" stable rolling in the middle of steel-high speed is stung in base speed end ", its the second half adds mathematical model and controls pipe tail end stable rolling technique, effectively overcome steel rolling and throw in steel process, the impact that the disturbance of equipment is unstable on the hollow billet tail end operation of rolling.This technique is that in the high-speed rolling control program segment that the one-level basic automatization by controlling for the unit controls program PLC, editor adds hollow billet tail end stable rolling mathematical model and realizes；AMS procedure logical control system PLC system for the ANSALDO electric corporation of one-level basic automatization employing Italy that the unit controls.

Concrete control method comprises the following steps:

(1) steel is stung in base speed end

Perforation unit roll runs under base speed state, wait pipe supplied materials, nipped pipe by base speed, that is: steel is stung in base speed end, realize base speed steady operational status to first instability and sting the process of steel state, according to different grade of steel kinds, it is differentiated that base degree of hastening is set, and base speed is set to the 70-80% being generally stable state high-speed rolling speed；

(2) stable rolling in the middle of high speed

Perforation unit detects unit at top and bottom rolls equipped with independent roll-force instrument, in order to detects in time and stings steel signal and throw steel signal, and provides foundation for technologist's Reasonable adjustment device parameter；After perforation main frame rolling force sensor detects and stings steel signal, when more than 50 tons of roll-forces, detect unit by roll-force instrument and send the switching value actuating signal I0443=1 speed controlling program to the one-level basic automatization PLC system of perforating machine, perforation main frame raising speed enters high speed steel rolling state, it may be assumed that high speed intermediate rolling；

(3) mathematical model controls hollow billet tail end stable rolling technique

When be arranged on the roll-force instrument above piercer roll detection unit detect pipe sting steel signal after, perforation main frame raising speed enter high speed steel rolling state；In fully automated as-rolled condition, and no longer carry out any device parameter when adjusting, start automatically to carry out that hollow billet is pure rolls time data collection；Change once any as-rolled condition having control mode or rolling parameter, to re-start that hollow billet is pure rolls time data collection, the main contents of as-rolled condition change include manually or the switching of semiautomatic control mode, roll rotational speed, roll drafts, pipe length adjustment；Gather compared with first three hollow billet pure time of rolling takes that average is pure with Theoretical Calculation hollow billet and roll the time by steady and continuous, whether normal to judge rolling, when continuous first three hollow billet is pure roll time average be not less than that Theoretical Calculation hollow billet is pure rolls the time time, it is good that devices illustrated runs as-rolled condition, controls hollow billet tail end stable rolling explained hereafter by starting to control the mathematical model of new edited in program PLC according to one-level basic automatization from the rolling of next hollow billet.

3, the foundation of mathematical model

Newly-built mathematical model control to be built upon the second half of hollow billet high-speed rolling process close to an end rolling time automatically implement, it first has to determine hollow billet tail end rolling start time；Secondly, design hollow billet afterbody starts the ramp velocity rolled during moment extremely rolling is fully completed and controls, and to complete effectively to throw steel, it is achieved the steadily rolling to pipe afterbody, concrete grammar is:

The determination of 3.1 rolled by piercing mill times

In motor is checked, it is necessary to use and pure roll time and off time.

3.1.1 the pure Theoretical Calculation rolling the time of hollow billet

The pure time of rolling of oblique milling refers to that rolled piece is played, by end in contact roll before pipe, the hollow billet tail end shut out by the time needed for deformed area and leaves roll interval only:

$T=\frac{l+L}{{\mathrm{\η}}_x\frac{\mathrm{\π}{D}_1{n}_r}{60}\sin \mathrm{\α}}---\left(20\right)$

In formula: l asynchronous region length；L hollow billet length；

T is pure rolls the time；η_xThe coefficient that slides axially of Outlet Section；

D₁Roller diameter on Outlet Section；n_rThe rotating speed of roll；α feed angle

3.1.2 the establishment of hollow billet tail end rolling start time point Tn

Tn=T-Ta (21)

In formula: the time point Tn of Tn hollow billet tail end roll control；T is pure rolls the time；

Ta afterbody rolling time, this time point is variable, is adjusted according to rolling different kinds；

Supplied materials pipe state owing to rolling pierced shell has length difference, now, the milling train pressure-measuring head Real-time Collection effectively omnidistance steel rolling time will be utilized, and effective rolling time sum of first three hollow billet of continuous acquisition, average again, it is actually active average rolling time Tm during continuous rolling state, as Tm > T

Tn=Tm-Ta (22)

In formula: the time point Tn of Tn hollow billet tail end roll control；

The actually active average rolling time Tm of Tm；

3.1.3 hollow billet tail end mill speed controls

When drilling/rolling process enters the time point Tn of hollow billet tail end roll control, being about to carry out the tail end to hollow billet and roll, now, perforation milling train rotation speed control program is automatically into hollow billet tail end roll control, until returning to perforating machine base speed rotating speed after throwing steel；The computing that perforating machine hollow billet tail end roll control is proportionally integration completes, and is export according to slope curve form to realize speed controlling；

The theoretical expression of mathematical model is:

△ V=∫ (Vmax-Vmin) dt (23)

Steel rolling maximum speed value Vmax, base hastens angle value Vmin, afterbody rolling time value t=Ta, and control method is, the program scanning cycle is set to Tsac=5ms, and speed maximum is steel rolling speed Vmax, and minima is base degree of hastening Vmin_,, afterbody rolling time is set to t=Ta, so programme-control is to be divided into the N=Ta/Tsac time period according to by afterbody rolling time Ta according to program scanning cycle T sac, each time period performs the variable quantity of △ V=(Vmax-Vmin)/N, if the speed during detection n-th scan period should be Vn, Vn=Vmax-n* ((Vmax-Vmin)/N, due within the afterbody rolling time time period at most 5 seconds program scanning cycle, perforation motor mill speed is made up of nearly 1000 speed Vn, difference of successively decreasing each other is △ V, actual monitored speed output effect is slope curve form；

The time point Tn of hollow billet tail end roll control is when rolling pipe distance tail end also surplus 30cm place, starts to perform numerical control tail end stable rolling, both ensure that the stability throwing steel rolling, met again the requirement of production process and rhythm of production.

3.1.4 equipment interlocking and application are arranged

In order to effectively implement tail end stable rolling, and it is beneficial to observation statistics, early stage carrying out step by step.

That is: once work as equipment and being in:

(1) manually the required pipe length (6) of rolling (2) jerk (3) latching operation platform (4) replacing product specification (5) change rolling hollow billet adjusts device parameter, such as the drafts of roller gap, roll rotational speed etc..

During any or more than one modes of above-mentioned six kinds of states, equipment will return to original rolling mill practice in time, to avoid when automatic rolling state, produces uncertain equipment and quality of production accident.

The control method improving pierced shell rolling quality of the present invention is in practice produces, achieve good effect, the hollow billet operation of rolling ideally is to be controlled by rational temperature and stable rolling, perforating machine makes pipe homogeneous deformation, reach hollow billet ovality less, the physical dimension of uniform wall thickness.Should being directly spend in terms of profile, afterbody cross section be have less ovality round-shaped, and should not have the unnecessary ferrum ears or side handles of a utensil；Checked by production practices, the hollow billet produced before adopting the control method improving pierced shell rolling quality is due to afterbody rolling instability, cause afterbody cross section ovality bigger, very big oblique stubble occurs, next procedure also can be had a huge impact by this, be unfavorable for that follow-up continuous rolling produces, and final products pipe tail to cut useless amount bigger.And adopt improve pierced shell rolling quality control method after produce hollow billet through check afterbody cross section ovality only small, afterbody does not have oblique stubble；Illustrate that hollow billet wall thickness is very uniform, after new technology adopts, to improving pierced shell quality clearly, reached the ideal effect of desired design.

Fig. 2-4 shows that founding mathematical models controls main transmission given operation rolling process curve and Fig. 2-5 shows rolling process main transmission actual motion velocity feedback detection curve, can be found out by upper figure, it is very stable that rolling hollow billet tail end throws steel speed controlling, has reached the ideal effect of desired design；

3.1.5 improve pierced shell rolling quality control method mathematical model set up structure chart

According to manufacturing technique requirent, draw out and conventionally produced produce control structure figure with new technology, the automatic switchover under different production environments of two kinds of techniques can be realized in putting into practice production process.As shown in figure 3-2, it is shown that the new and old two kinds of production technologies in rolling process select and the process of control.

The determination of 3.2 off times

Determined by practical situation.

After implementing due to the control method of this raising pierced shell rolling quality, effect is obvious, brings many production advantages, improves production quality, is more suitable for the Development and Production of new product；Decrease substantial amounts of equipment fault maintenance cost；And have adjusted traditional handicraft, eliminate " pipe afterbody flame cutting ", this control method is primarily to the technical process improving hollow billet afterbody rolling quality and increase, therefore, very popular in intra-company, now being generalized to other units of intra-company gradually, after the units such as " 460 large-sized seamless steel pipe factory " " 258 seamless steel tubing mill ", effect becomes apparent from, and other three units are also organizing technological transformation to implement.

Claims (1)

1. the control method improving pierced shell rolling quality, this control method is to adding control hollow billet tail end stable rolling technique in two roller oblique milling piercing mill of seamless steel tube group rolling mill practice the second halfs, controlling in program segment by controlling the high-speed rolling of program PLC for the one-level basic automatization in controlled rolling technique the second half unit, editor adds hollow billet tail end stable rolling mathematical model and realizes；AMS procedure logical control system PLC system for the ANSALDO electric corporation of one-level basic automatization employing Italy that the unit controls；

Concrete control method step is as follows:

(1) steel is stung in base speed end

Perforation unit roll runs under base speed state, wait pipe supplied materials, nipped pipe by base speed, that is: steel is stung in base speed end, realize base speed steady operational status to first instability and sting the process of steel state, according to different grade of steel kinds, it is differentiated that base degree of hastening is set, and base degree of hastening is set to the 70-80% being generally stable state high-speed rolling speed；

(2) stable rolling in the middle of high speed

Perforation unit detects unit at top and bottom rolls equipped with independent roll-force instrument, in order to detects in time and stings steel signal and throw steel signal, and provides foundation for technologist's Reasonable adjustment device parameter；After perforation main frame rolling force sensor detects and stings steel signal, when more than 50 tons of roll-forces, detect unit by roll-force instrument and send the switching value actuating signal I0443=1 speed controlling program to the one-level basic automatization PLC system of perforating machine, perforation main frame raising speed enters high speed steel rolling state, it may be assumed that high speed intermediate rolling；

(3) mathematical model controls hollow billet tail end stable rolling technique

When be arranged on perforation unit roll above roll-force instrument detection unit detect pipe sting steel signal after, perforation main frame raising speed enter high speed steel rolling state；In fully automated as-rolled condition, and no longer carry out any device parameter when adjusting, start automatically to carry out that hollow billet is pure rolls time data collection；Change once any as-rolled condition having control mode or rolling parameter, to re-start that hollow billet is pure rolls time data collection, the main contents of as-rolled condition change include manually or the switching of semiautomatic control mode, roll rotational speed, roll drafts, pipe length adjustment；Gather compared with first three hollow billet pure time of rolling takes that average is pure with Theoretical Calculation hollow billet and roll the time by steady and continuous, whether normal to judge rolling, when continuous first three hollow billet is pure roll time average be not less than that Theoretical Calculation hollow billet is pure rolls the time time, it is good that devices illustrated runs as-rolled condition, controls hollow billet tail end stable rolling explained hereafter by starting to control the mathematical model of editor in program PLC according to one-level basic automatization from the rolling of next hollow billet；

Described mathematical model control to be built upon the second half of hollow billet high-speed rolling process close to an end rolling time automatically implement, it first has to determine hollow billet tail end rolling start time；Secondly, design hollow billet afterbody starts the ramp velocity rolled during moment extremely rolling is fully completed and controls, and to complete effectively to throw steel, it is achieved the steadily rolling to pipe afterbody, concrete grammar is:

) the pure Theoretical Calculation rolling the time of hollow billet

The pure time of rolling of oblique milling refers to that rolled piece is played, by end in contact roll before pipe, the hollow billet tail end shut out by the time needed for deformed area and leaves roll interval only:

$T=\frac{l+L}{{\mathrm{\η}}_x\frac{{\mathrm{\πD}}_1{n}_r}{60}sin\mathrm{\α}}---\left(1\right)$

In formula: l asynchronous region length；L hollow billet length；

T is pure rolls the time；η_xThe coefficient that slides axially of Outlet Section；

D₁Roller diameter on Outlet Section；n_rThe rotating speed of roll；α feed angle

) hollow billet tail end rolling start time point Tn establishment

Tn=T-Ta (2)

In formula: Tn hollow billet tail end rolling start time point Tn；T is pure rolls the time；

Ta afterbody rolling time, this time point is variable, is adjusted according to rolling different kinds；

Supplied materials pipe state owing to rolling pierced shell has length difference, now, the milling train pressure-measuring head Real-time Collection effectively omnidistance steel rolling time will be utilized, and effective rolling time sum of first three hollow billet of continuous acquisition, average again, it is actually active average rolling time Tm during continuous rolling state, as Tm > T

Tn=Tm-Ta (3)

In formula: the time point Tn of Tn hollow billet tail end roll control；

The actually active average rolling time Tm of Tm；

) control of hollow billet tail end mill speed

When drilling/rolling process enters the time point Tn of hollow billet tail end roll control, being about to carry out the tail end to hollow billet and roll, now, perforation milling train rotation speed control program is automatically into hollow billet tail end roll control, until returning to perforating machine base speed rotating speed after throwing steel；The computing that perforating machine hollow billet tail end roll control is proportionally integration completes, and is export according to slope curve form to realize speed controlling；

The theoretical expression of mathematical model is:

△ V=∫ (Vmax-Vmin) dt (4)

nullSteel rolling maximum speed value Vmax，Base hastens angle value Vmin,Afterbody rolling time value t=Ta，Control method is，The program scanning cycle is set to Tsac=5ms，Speed maximum is steel rolling speed Vmax，Minima is base degree of hastening Vmin,,Afterbody rolling time is set to t=Ta，So programme-control is to be divided into the N=Ta/Tsac time period according to by afterbody rolling time Ta according to program scanning cycle T sac，Each time period performs the variable quantity of △ V=(Vmax-Vmin)/N，If the speed during detection n-th scan period should be Vn，Vn=Vmax-n* (Vmax-Vmin)/N,Due within the afterbody rolling time time period at most 5 seconds program scanning cycle,Perforation motor mill speed is made up of nearly 1000 speed Vn，Difference of successively decreasing each other is △ V，Actual monitored speed output effect is slope curve form；

The time point Tn of hollow billet tail end roll control is when rolling pipe distance tail end also surplus 30cm place, starts to perform numerical control tail end stable rolling, both ensure that the stability throwing steel rolling, met again the requirement of production process and rhythm of production.