CN104475459A - Control method for improving rolling quality of perforated shell - Google Patents

Abstract

The invention provides a control method for improving the rolling quality of a perforated shell. The rolling process for controlling the steady state of the tail end of the shell is added to the last half process of the rolling process of a two-roller skew rolling seamless steel pipe perforating machine. The control method specifically comprises the steps of performing the base speed end portion steel snapping; establishing a starting time point of the rolling of the tail end of the shell; performing the given output on the slope control speed of the rolling of the tail end of the shell. According to the control method for improving the rolling quality of the perforated shell, the novel process and the mathematical model control are safe and reliable and reasonable in design, the use performance of a rolling machine rear-three-roller device is improved, the failure rate is significantly reduced, the product yield can be improved by more than 1%, the equipment failure rate can be reduced by 80%, the equipment maintenance cost can be reduced, the operation rate can be improved, the optimization of the protection measures is facilitated, the service life of a motor is extended, the good effect is obtained after the nearly more than a year of practice test, and the reduced loss and the more created benefit are more than 12 million yuan every year.

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, changes the technique of traditional steel rolling, realizes the even rolling of tail end stable state in the perforating steel pipe operation of rolling.

Background technology

In seamless steel tube production process, application piercing process is very economical.The Mannesmann brother of Germany in 1886 has applied for the patent with cross roll punch production tubular sections product.Describe the effect of internal forces during flow of metal in document and use two or more tapered roll to bore a hole, being 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.Bore a hole as the first operation of flow of metal, 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, be also difficult to eliminate or alleviate through operation below.So very crucial in steel pipe's production middle punch operation, whether the technique that the quality of perforation quality is directly connected to next procedure can normally perform and the height of end product quality.For this reason, special to following 3 requirements of piercing process proposition:

(1) first will ensure the hollow billet uniform wall thickness passed, 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 to there be corresponding punching rate and rolling cycle, to adapt to the rhythm of production of whole unit, enable the finishing temperature of hollow billet meet the requirement of tandem rolling tube machine.

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

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

The whole process of 1.1 roll piercing

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

First erratic process--pipe forward metal is full of the deformed area stage gradually, and namely pipe starts to touch forward metal with roll and goes out deformed area, and this stage exists once nips and secondary is nipped.

Stabilization process--this is perforation procedure Main Stage, is full of deformed area leaves deformed area to pipe tail end metal from pipe forward metal.

Second erratic process-leave deformed area gradually to metal all leaves roll for pipe tail end metal.

Stabilization process and erratic process have obvious difference, and this is easy to observe aborning.As on a hollow billet end to end size and intermediate sizes just have difference, be generally that hollow billet point diameter is large, 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 large is: forward metal is being full of in deformed area gradually, metal increases gradually with the frictional force on roll contact face, just maximum is reached to being full of deformed area completely, particularly when meeting in pipe front end and top, due to the axial resistance come directly towards, metal is subject to resistance to axially extending, axial extensional is reduced, and transversely deforming increases, adding does not have outer end to limit, thus causes point diameter large.Tail end diameter is little, and be because when pipe tail end is started to penetrate by top, top resistance obviously declines, and 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 distinguished to some extent, they realize in same deformed area.Deformed area is made up of roll, top, godet (guide plate).As Figure 1-1, whole deformed area is a more complicated geometry, roughly can think, cross section is oval, has the top stage to be a cyclic deformation district to centre.Longitudinal section is two cones that handle connects, middle insertion arc top.

Deformed area shape decides the deformation process of perforation, changes deformed area shape (determining and tool design and adjustment of rolling mill) by the change of the deformation process that causes boring a hole.Perforation deformed area is broadly divided into four sections, as shown in Figure 1-2.

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

IIth district is called punch block, and the effect in this district is perforation, namely becomes hollow hollow billet by solid billet, the length in this district for from metal and top meet to coming directly towards circular cone band.The mainly wall thickness pressure of this section deformation characteristics, because the spacing of roller surface with surface, top reduces gradually, therefore hollow billet wall thickness is while rotate, while pressure, therefore be continuous rolling process, the deformation parameter of this section represents with diameter relative reduction, the metal be diametrically depressed, equally can to lateral flow (expanding) and longitudinal flow (extension) but transversely deforming is subject to the interception of godet, distortion extending longitudinally is main.The effect of godet not only can limit transversely deforming but also metal can be pulled to axial extension, due to the result of transversely deforming, and 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 very little, mainly plays expansion effect.Rolled piece cross section is also oval at this section, and reduces gradually.

IVth district is called circle area.The effect in this district is the hollow billet ellipse, and the roll by rotating reduces drafts diametrically gradually to zero, and hollow billet is turned round, and this section length is very short, and be actually without the hollow hollow billet plastic bending deformation in top in the distortion of this district, deformation force is also very little.

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

1.2 roll piercing kinematics

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, due to the existence of advancing angle, pipe-hollow billet rotation while to moving axially, in deformed area pipe-hollow billet on the surface every bit be all screw, namely rotate, on one side advance.

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 D Nb/60 × COS β------

VtR=VR sin β=π D Nb/60 × Sin β-----axial velocity (2)

In formula D----the roller diameter in cross section, mm are discussed;

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

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

But the in fact speed of rolls and metal speeds non-fully is equal.Common metal movement velocity is less than the speed of rolls, namely produces slippage between the two, can represent both speed, like this with slip coefficient

VaR＝πD Nb/60×COSβ×ητ (4)

VtR＝πD Nb/60×sinβ×η0 (5)

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

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

Different materials has different slip coefficients, 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.

What be of practical significance most aborning is that hollow billet that speed when leaving roll is known, and muzzle velocity is larger, and productivity ratio is also higher.In order to simplify calculating, general hypothesis roll exit speed equals VtR, and actual error is included in slip coefficient.

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

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

Hollow billet leaves any pitch computing formula of roll:

T＝π/2×η0/ητ×d×tgβ (6)

In formula: d----hollow billet diameter

The bite condition of 1.3 perforation

Roll piercing process also exists twice and nips, and it is that pipe and roll start Contact that first time nips, and drives pipe to move and pipe is drawn in deformed area by roll.When metal enter deformed area to and top meet, it is that secondary is nipped that the axial resistance overcoming top continues to enter deformed area.The condition that general satisfaction is once nipped also may not be certain just to 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

Mp-due to pressure produce prevention blank turning moment

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

The moment of inertia of Mi-pipe blank rotary

If ignore Mq, Mi (value is very little), general expression formula is:

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

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

n(Tx-Px)+P′≥0 (9)

In formula: Tx-each roll 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 to nip required rotating condition

Formula below shows the balance of the power when pipe is nipped, two important parameters, and coefficient of friction and angular speed can pass through formulae discovery below.

$\begin{array}{c}\mathrm{\μ}\≥\tan \mathrm{\ω}\frac{\sin {\mathrm{\α}}_e}{\tan \mathrm{\γ}\cos \mathrm{\ω}}\\ \mathrm{\ω}=\arccos \frac{\mathrm{Dw}-\mathrm{\Δd}}{\mathrm{Dw}}\end{array}---\left(10\right)$

In formula: α _e---roll entrance cone angle

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

If think, pipe is nipped smoothly, nip angle can be become entrance cone angle that is large, roll less, or by the push-on force applying pipe and the roller flower degree of depth strengthening 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 to nip, and its value is very little.Therefore secondary is nipped rotating condition, and fundamental sum is once nipped identical.The key that secondary is nipped is advance condition.

The equilibrium condition of axial force when secondary is nipped:

n(Tx-Px)-Q′≥0 (11)

In formula: the axial resistance of Q '-top nose

Secondary is nipped required rotating condition

The secondary condition of nipping is greater than top and the frictional force between pipe and roll at the push-on force of axial pipe, and can realize the prerequisite that secondary nips is that (x=drift) pipe at least will rotate a circle before pipe contact top.

x＝π*d _B*tanγ

(12)

In formula: d B---pipe diameter

2, flow of metal during roll piercing

2.1 pipe stressing conditions

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

2.2 flow of metal

Basic deformation is the change of physical dimension completely, has nothing to do with the character of material, and basic deformation depends on the geometry (determined by tool design and adjustment of rolling mill) of deformed area.

Additional deformation refers to the distortion of material internal, be intuitively less than distortion, additional deformation, due in material caused by internal stress, is the distortional stress increasing material, cause the defect produced in material, so it is very 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 kinds distortion are all macroscopic deformations, represent 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 distortion etc., additional deformation is the distortion uneven generation due to metal each several part, additional deformation can bring a series of consequence, increase as caused strain energy of distortion, and the additional stress caused by additional deformation, easily cause hollow billet surfaces externally and internally produces defect etc. with inner.Longitudinal shear distortion mainly causes due to the axial resistance come directly towards, roll drives tubing axial flow on the one hand, and top will stop metal axial to flow, each metal axial is finally caused to flow variant, each layer metal interknits again, an entirety, so certainly lead to additional deformation and additional stress at each layer intermetallic, the superficial layer metal particularly directly contacted with roll, top, can find out by figure, additional deformation is larger, and therefore hollow billet surfaces externally and internally is easy to occur defect or the original development of defects in pipe surface is expanded.Tangentially cutting distortion causes hollow billet surfaces externally and internally to produce one of defect cause (as defects such as crackle, folding, absciss layers) often.

In original control procedure, having of prevailing quality accidents such as often producing pierced shell infolding, scab, lose flesh:

(1) impact of rolling parameter adjustment on infolding defect

The size of roll rotational speed is that result shows: high rotating speed more easily forms infolding according to multifactor designs such as strand material, lengthening coefficient, slip coefficient and roller footpath sizes, reduces rotating speed, the corresponding minimizing of infolding.Mainly increase roll rotational speed of tracing it to its cause will cause slippage to increase, and namely axial efficiency reduces, and pipe increases in the section of nipping number of revolutions, and the possibility forming infolding strengthens.The adjustment direction that result of the test determines punch is: use large nip angle, reduces along with nip angle strengthens pipe slippage, and the reduction of slippage can reduce pipe and to nip required number of revolutions.The experience of comprehensive external producer, nip angle advance efficiency 10 ~ 12 degree time 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 will 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 and steadily nips, and after nipping, high-speed rolling throws steel at a high speed.General by 30% setting, what often adopt depending on roll wear situation in production is 40% or 45%, and experimental result shows: adopt the infolding amount that the raising speed of 30% produces than perforation lower than employing 45% raising speed than the infolding amount that perforation produces.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.That is, when low speed changes to high speed, metal flow can smooth transition.If the two speed difference is large, flow of metal produces fluctuation and just easily produces large stretch of infolding.This infolding 400 ~ 500MM place, hollow billet front end that is everlasting finds, the method is also will to sacrifice rhythm of production, reduces just realization under production efficiency prerequisite.

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

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

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

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

(4) easily produce " the iron ears or side handles of a utensil " in production process, cause larger waste, and cause very large impact to normal rolling, need to clear up timely, bring great inconvenience to normal production work.

(5) during tail end rolling, perforation mair motor is thrown steel speed and is raised rapidly instantaneously, and throwing steel electric current is promoted rapidly, produces " surge " impact engine commutator, often makes commutator produce and destroys; Need regularly to safeguard process timely.

(6) rising of steel rolling speed thrown by punch at afterbody, produces larger vibrations, make it fragile, as shown in Fig. 2-1,2-2,2-3 to three roller arrangements after machine.

(7) show through practice for many years, by the mode of " centering of afterbody gas flame cuttiug ", certain alleviation can be obtained to above-mentioned situation; But monthly need the consumption increasing 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 invention provides a kind of control method improving pierced shell rolling quality, the moment that the rolling hollow forging solving traditional two roller roll piercing units is about to penetrate throws steel raising speed phenomenon, in milling train, hollow forging afterbody is effectively controlled close to when completing in hollow billet rolling, 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 controls hollow billet tail end stable rolling technique to adding in two roller oblique milling piercing mill of seamless steel tube rolling mill practice the second halfs; This technique is in the high-speed rolling control program section by the one-level basic automatization control program PLC for this unit allocation, and editor adds hollow billet tail end stable rolling Mathematical Modeling and realizes; One-level basic automatization for this unit allocation adopts the AMS procedure logical control system PLC system of Italian ANSALDO electric corporation.

Concrete control method step is as follows:

(1) steel is stung in base speed end

Perforation unit roll runs under base speed state, wait for pipe supplied materials, to be nipped pipe by base speed, that is: steel is stung in base speed end, realize base speed steady operational status stings steel state process to first instability, according to different grade of steel kind, be differentiated to base speed Speed Setting, the setting of base speed be generally to the 70-80% of stable state high-speed rolling speed;

(2) stable rolling in the middle of high speed

Perforation unit is equipped with independently roll-force instrument detecting unit at top and bottom rolls, so that detect in time and sting 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 being greater than 50 tons of roll-forces, switching value actuating signal I0443=1 is sent to the speeds control program of the one-level basic automatization PLC system of punch by roll-force instrument detecting unit, perforation main frame raising speed enters high speed steel rolling state, that is: high speed intermediate rolling;

(3) Mathematical Modeling controls hollow billet tail end stable rolling technique

When be arranged on the roll-force instrument detecting unit above piercer roll detect pipe sting steel signal after, perforation main frame raising speed enters high speed steel rolling state; In complete automatic rolling state, and when no longer carrying out the adjustment of any device parameter, start automatically to carry out that hollow billet is pure rolls time data collection; Change once there be any one as-rolled condition of 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 comprise manually or the switching of semiautomatic control mode, roll rotational speed, roll drafts, pipe length adjustment; Gather first three hollow billet pure time of rolling by steady and continuous and get that average and theory calculate hollow billet are pure to be rolled compared with the time, to judge that whether rolling is normal, when continuous first three hollow billet is pure roll time average be not less than that theory calculate 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 from next hollow billet rolling according to the Mathematical Modeling of new edited in one-level basic automatization control program PLC.

Newly-built Mathematical Modeling control be the second half being based upon hollow billet high-speed rolling process close to an end rolling time automatically implement, first it will determine hollow billet tail end rolling start time; Secondly, design hollow billet afterbody starts the speeds control between the rolling moment to rolling complete tailend, and effectively throw steel to complete, realize the rolling steadily to pipe afterbody, concrete grammar is:

I) the pure calculating of rolling the time of hollow billet

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

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

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

T---purely roll the time; η _x---the coefficient that slides axially of Outlet Section;

D ₁---the roller diameter on Outlet Section; n _r---the rotating speed of roll; α---feed angle

II) establishment of hollow billet tail end rolling start time point Tn

Tn＝T-Ta (17)

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

Ta---afterbody rolling time, this time point is variable, and the kind different according to rolling adjusts;

Because the supplied materials pipe state of rolling pierced shell has length difference, now, the milling train pressure-measuring head Real-time Collection effective omnidistance steel rolling time will be utilized, and effective rolling time sum of first three hollow billet of continuous acquisition, average again, the effectively average rolling time Tm of reality when being continuous rolling state, as Tm > T

Tn＝Tm-Ta (18)

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

Tm---actual effectively average rolling time Tm;

III) control of hollow billet tail end mill speed

When drilling/rolling process enters the time point Tn of hollow billet tail end roll control, be about to carry out the tail end rolling to hollow billet, now, perforation milling train rotation speed control program enters hollow billet tail end roll control automatically, until get back to punch base speed rotating speed after throwing steel; Punch hollow billet tail end roll control is that the computing of proportionally integration has come, and is export according to slope curve form to realize speeds control;

The theoretical expression of Mathematical Modeling is:

△V＝∫(Vmax-Vmin)dt (19)

Steel 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, minimum of a value is base degree of hastening Vmin, , afterbody rolling time is set to t=Ta, so programme-control is divided into the N=Ta/Tsac time period according to by afterbody rolling time Ta according to program scanning cycle T sac, the variable quantity of △ V=(Vmax-Vmin)/N is performed in each time period, if speed when detecting n-th scan period should be Vn, Vn=Vmax-n* ((Vmax-Vmin)/N, due within the afterbody rolling time time period 5 seconds at the most 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 remains 30cm place, starts to perform numerical control tail end stable rolling, both ensure that the stability of throwing steel rolling, and met again the requirement of production process and rhythm of production.

Effect of the present invention adopts 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; Many wound benefits reduce the loss 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 entered for hollow billet afterbody wall thickness and the hollow billet afterbody iron ears or side handles of a utensil that hollow billet is inner to be caused 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, high-quality seamless steel pipe per year, high-quality seamless steel pipe profit 1000 yuan calculating per ton 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 gas flame cuttiug " technical process is reduced

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

(3) impact of disorderly closedown

Reduce " blocking after main frame " every year by this project implementation, cleaning easily produces production accident shutdown such as " the iron ears or side handles of a utensil " at least 6 hours; Equipment fault is shut down at least 8 hours, calculates with rhythm of production minimum 45 seconds discharging machines, and annual few (6+8) * 60*60/45=1120 that produces props up steel pipe, often props up 1.5 tons, 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, this technology controlling and process has tried other units such as " 460 large-sized seamless steel pipe factory ", " 258 seamless steel tubing mill " shifting our company inside onto at present, 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 accepts analysis chart;

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

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

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

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

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

Fig. 3-2 is rolling mill practice Mathematical Modeling structure chart of the present invention.

Detailed description of the invention

By reference to the accompanying drawings the control method of raising 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 full of the deformed area stage gradually, namely once nips and secondary is nipped, and can eliminate first erratic process by what suitably adjust rolling parameter as far as possible.

Stabilization process-----this be perforation procedure Main Stage, be full of deformed area leaves deformed area to pipe tail end metal from pipe forward metal.

Second erratic process-----leaves deformed area to metal all leaves roll gradually for pipe tail end metal, and this process is general not to have been eliminated by adjustment parameter.

The control method of raising pierced shell rolling quality of the present invention is mainly given and new improvement Supplementary and perfect for traditional two roller oblique milling piercing mill of seamless steel tube rolling mill practices.That is: original rolling mill practice-----" stable rolling in the middle of steel-high speed is stung in base speed end ", add Mathematical Modeling in its second half and control pipe tail end stable rolling technique, effectively overcome steel rolling to throw in steel process, the disturbance of equipment is on the impact of hollow billet tail end operation of rolling instability.This technique is in the high-speed rolling control program section by the one-level basic automatization control program PLC for this unit allocation, and editor adds hollow billet tail end stable rolling Mathematical Modeling and realizes; One-level basic automatization for this unit allocation adopts the AMS procedure logical control system PLC system of Italian ANSALDO electric corporation.

Concrete control method comprises the following steps:

(1) steel is stung in base speed end

Perforation unit roll runs under base speed state, wait for pipe supplied materials, to be nipped pipe by base speed, that is: steel is stung in base speed end, realize base speed steady operational status stings steel state process to first instability, according to different grade of steel kind, be differentiated to base speed Speed Setting, the setting of base speed be generally to the 70-80% of stable state high-speed rolling speed;

(2) stable rolling in the middle of high speed

Perforation unit is equipped with independently roll-force instrument detecting unit at top and bottom rolls, so that detect in time and sting 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 being greater than 50 tons of roll-forces, switching value actuating signal I0443=1 is sent to the speeds control program of the one-level basic automatization PLC system of punch by roll-force instrument detecting unit, perforation main frame raising speed enters high speed steel rolling state, that is: high speed intermediate rolling;

(3) Mathematical Modeling controls hollow billet tail end stable rolling technique

When be arranged on the roll-force instrument detecting unit above piercer roll detect pipe sting steel signal after, perforation main frame raising speed enters high speed steel rolling state; In complete automatic rolling state, and when no longer carrying out the adjustment of any device parameter, start automatically to carry out that hollow billet is pure rolls time data collection; Change once there be any one as-rolled condition of 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 comprise manually or the switching of semiautomatic control mode, roll rotational speed, roll drafts, pipe length adjustment; Gather first three hollow billet pure time of rolling by steady and continuous and get that average and theory calculate hollow billet are pure to be rolled compared with the time, to judge that whether rolling is normal, when continuous first three hollow billet is pure roll time average be not less than that theory calculate 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 from next hollow billet rolling according to the Mathematical Modeling of new edited in one-level basic automatization control program PLC.

3, the foundation of Mathematical Modeling

Newly-built Mathematical Modeling control be the second half being based upon hollow billet high-speed rolling process close to an end rolling time automatically implement, first it will determine hollow billet tail end rolling start time; Secondly, the ramp velocity that design hollow billet afterbody started between the rolling moment to rolling complete tailend controls, and effectively throw steel to complete, realize the rolling steadily to pipe afterbody, concrete grammar is:

The determination of 3.1 rolled by piercing mill times

In motor is checked, need to use and purely roll time and off time.

3.1.1 the pure theory calculate rolling the time of hollow billet

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

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

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

T---purely roll the time; η _x---the coefficient that slides axially of Outlet Section;

D ₁---the roller diameter on Outlet Section; n _r---the 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: Tn---the time point Tn of hollow billet tail end roll control; T---purely roll the time;

Ta---afterbody rolling time, this time point is variable, and the kind different according to rolling adjusts;

Because the supplied materials pipe state of rolling pierced shell has length difference, now, the milling train pressure-measuring head Real-time Collection effective omnidistance steel rolling time will be utilized, and effective rolling time sum of first three hollow billet of continuous acquisition, average again, the effectively average rolling time Tm of reality when being continuous rolling state, as Tm > T

Tn＝Tm-Ta (22)

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

Tm---actual effectively average rolling time 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, be about to carry out the tail end rolling to hollow billet, now, perforation milling train rotation speed control program enters hollow billet tail end roll control automatically, until get back to punch base speed rotating speed after throwing steel; Punch hollow billet tail end roll control is that the computing of proportionally integration has come, and is export according to slope curve form to realize speeds control;

The theoretical expression of Mathematical Modeling is:

△V＝∫(Vmax-Vmin)dt (23)

Steel 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, minimum of a value is base degree of hastening Vmin, , afterbody rolling time is set to t=Ta, so programme-control is divided into the N=Ta/Tsac time period according to by afterbody rolling time Ta according to program scanning cycle T sac, the variable quantity of △ V=(Vmax-Vmin)/N is performed in each time period, if speed when detecting n-th scan period should be Vn, Vn=Vmax-n* ((Vmax-Vmin)/N, due within the afterbody rolling time time period 5 seconds at the most 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 remains 30cm place, starts to perform numerical control tail end stable rolling, both ensure that the stability of throwing steel rolling, and 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 be beneficial to observation statistics, carrying out step by step in earlier stage.

That is: once when equipment is in:

(1) manual rolling (2) is anxious stops required pipe length (6) the adjustment device parameter that (3) latching operation platform (4) changes product specification (5) change rolling hollow billet, as the drafts, roll rotational speed etc. of roller gap.

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

The control method of raising pierced shell rolling quality of the present invention is in practice is produced, achieve good effect, the hollow billet operation of rolling is ideally controlled and stable rolling by rational temperature, punch makes pipe homogeneous deformation, reach hollow billet ovality less, the physical dimension of uniform wall thickness.Should be directly spend viewed from profile, afterbody cross section be have less ovality round-shaped, and should not have the unnecessary iron 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 larger, there is very large oblique stubble, this also can have a huge impact next procedure, be unfavorable for that follow-up continuous rolling is produced, and final products pipe tail to cut useless amount larger.And the hollow billet produced after adopting the control method of raising pierced shell rolling quality is very little through the ovality of inspection afterbody cross section, afterbody does not have oblique stubble; Illustrate that hollow billet wall thickness is very uniform, after new technology adopts, to raising pierced shell quality clearly, reach the ideal effect of desired design.

Fig. 2-4 shows founding mathematical models control 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 speeds control, reaches the ideal effect of desired design;

That 3.1.5 improves the Mathematical Modeling of the control method of pierced shell rolling quality sets up structure chart

According to manufacturing technique requirent, draw out traditional handicraft and produce and new technology production control structure chart, two kinds of technique automatic switchovers under different production environment can be realized putting into practice in production process.As shown in figure 3-2, the new and old two kinds of production technologies shown in rolling process are selected and control procedure.

3.2 the determination of off time

Determined by actual conditions.

Control method due to this raising pierced shell rolling quality implements rear successful, brings many production advantages, improves production quality, is more applicable to the Development and Production of new product; Decrease a large amount of equipment fault maintenance costs; And have adjusted traditional handicraft, eliminate " pipe afterbody gas flame cuttiug ", this control method is mainly in order to improve the technical process that hollow billet afterbody rolling quality increases, therefore, very popular in intra-company, now be generalized to other units of intra-company gradually, after units such as " 460 large-sized seamless steel pipe factory " " 258 seamless steel tubing mills ", effect is more obvious, and other three units are also organizing technological transformation to implement.

Claims (1)

1. one kind is improved the control method of pierced shell rolling quality, this control method controls hollow billet tail end stable rolling technique to adding in two roller oblique milling piercing mill of seamless steel tube group rolling mill practice the second halfs, by in the high-speed rolling control program section for the one-level basic automatization control program PLC in controlled rolling technique the second half unit, editor adds hollow billet tail end stable rolling Mathematical Modeling and realizes; One-level basic automatization for this unit allocation adopts the AMS procedure logical control system PLC system of Italian ANSALDO electric corporation;

Concrete control method step is as follows:

(1) steel is stung in base speed end

Perforation unit roll runs under base speed state, wait for pipe supplied materials, to be nipped pipe by base speed, that is: steel is stung in base speed end, realize base speed steady operational status stings steel state process to first instability, according to different grade of steel kind, be differentiated to base speed Speed Setting, the setting of base speed be generally to the 70-80% of stable state high-speed rolling speed;

(2) stable rolling in the middle of high speed

Perforation unit is equipped with independently roll-force instrument detecting unit at top and bottom rolls, so that detect in time and sting 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 being greater than 50 tons of roll-forces, switching value actuating signal I0443=1 is sent to the speeds control program of the one-level basic automatization PLC system of punch by roll-force instrument detecting unit, perforation main frame raising speed enters high speed steel rolling state, that is: high speed intermediate rolling;

(3) Mathematical Modeling controls hollow billet tail end stable rolling technique

When be arranged on the roll-force instrument detecting unit above perforation unit roll detect pipe sting steel signal after, perforation main frame raising speed enters high speed steel rolling state; In complete automatic rolling state, and when no longer carrying out the adjustment of any device parameter, start automatically to carry out that hollow billet is pure rolls time data collection; Change once there be any one as-rolled condition of 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 comprise manually or the switching of semiautomatic control mode, roll rotational speed, roll drafts, pipe length adjustment; Gather first three hollow billet pure time of rolling by steady and continuous and get that average and theory calculate hollow billet are pure to be rolled compared with the time, to judge that whether rolling is normal, when continuous first three hollow billet is pure roll time average be not less than that theory calculate 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 from next hollow billet rolling according to the Mathematical Modeling of one-level basic automatization control program PLC inediting;

Described Mathematical Modeling control be the second half being based upon hollow billet high-speed rolling process close to an end rolling time automatically implement, first it will determine hollow billet tail end rolling start time; Secondly, the ramp velocity that design hollow billet afterbody started between the rolling moment to rolling complete tailend controls, and effectively throw steel to complete, realize the rolling steadily to pipe afterbody, concrete grammar is:

I) the pure theory calculate rolling the time of hollow billet

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

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

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

T---purely roll the time; η _x---the coefficient that slides axially of Outlet Section;

D ₁---the roller diameter on Outlet Section; n _r---the rotating speed of roll; α---feed angle

II) establishment of hollow billet tail end rolling start time point Tn

Tn＝T-Ta (2)

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

Ta---afterbody rolling time, this time point is variable, and the kind different according to rolling adjusts;

Because the supplied materials pipe state of rolling pierced shell has length difference, now, the milling train pressure-measuring head Real-time Collection effective omnidistance steel rolling time will be utilized, and effective rolling time sum of first three hollow billet of continuous acquisition, average again, the effectively average rolling time Tm of reality when being continuous rolling state, as Tm > T

Tn＝Tm-Ta (3)

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

Tm---actual effectively average rolling time Tm;

III) control of hollow billet tail end mill speed

When drilling/rolling process enters the time point Tn of hollow billet tail end roll control, be about to carry out the tail end rolling to hollow billet, now, perforation milling train rotation speed control program enters hollow billet tail end roll control automatically, until get back to punch base speed rotating speed after throwing steel; Punch hollow billet tail end roll control is that the computing of proportionally integration has come, and is export according to slope curve form to realize speeds control;

The theoretical expression of Mathematical Modeling is:

△V＝∫(Vmax-Vmin)dt (4)

Steel 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, minimum of a value is base degree of hastening Vmin, , afterbody rolling time is set to t=Ta, so programme-control is divided into the N=Ta/Tsac time period according to by afterbody rolling time Ta according to program scanning cycle T sac, the variable quantity of △ V=(Vmax-Vmin)/N is performed in each time period, if speed when detecting n-th scan period should be Vn, Vn=Vmax-n* ((Vmax-Vmin)/N, due within the afterbody rolling time time period 5 seconds at the most 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 remains 30cm place, starts to perform numerical control tail end stable rolling, both ensure that the stability of throwing steel rolling, and met again the requirement of production process and rhythm of production.